EPA 560/6-77-033
MARKET INPUT/OUTPUT STUDIES
TASK 1
VINYLIDENE CHLORIDE
PR0Y
NOVEMBER 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
WASHINGTON D.C 20460
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EPA-560/6-77-033 AAI 2378/2379-101-FR-l
MARKET INPUT/OUTPUT STUDIES
TASK I
VINYLIDENE CHLORIDE
M. Lynne Neufeld
Marcus Sittenfield
Marcia J. Plotkin
Kathryn F. WoIk
Robert E. Boyd
October 1977
Final Report
Contract No. 68-01-1996
Project Officer
Vincent DeCarlo, Ph.D.
Prepared for:
Office.of Toxic Substances
U.S. Environmental Protection Agency
Washington, D.C, 20460
Document is available to the public through the National
Technical Information Service, Springfield, Virginia 22151
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NOTICE
This report has been reviewed by the Office of Toxic Substances,
Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and
policies of the Environmental Protection Agency. Mention of tradenames
or commercial products is for purposes of clarity only and does not
constitute endorsement or recommendation for use.
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ACKNOWLEDGEMENTS
This report was prepared by the staff of AAI, Philadelphia,
Pennsylvania, and their subcontractor, Marcus Sittenfield & Associates.
Dr. V. DeCarlo, Environmental Protection Agency, Office of Toxic
Substances, served as Project Officer, and some initial guidance
was provided by Mr. Perry Breunner, also of the Office of Toxic
Substances.
Many companies involved in the production, polymeriza-
tion or converting of VDC and its end products contributed substan-
tially to the report, both in providing detailed information and re-
viewing the conclusions drawn from the data. AAI, and Marcus Sitten-
field & Associates, however, assume full responsibility for any
errors or omissions. Our appreciation is specifically extended to
the following associations and individuals who provided invaluable
assistance with this study:
Dow Chemical Co.:
PPG Industries:
American Paper Institute;
W.R. Grace:
A.E. Staley Mfg. Co.:
FMC:
Olin:
American
Reicholds
DuPont:
& Paper Co„l
Robert J. Wintermyer
Joe Strasser
Gregory J. Lazarchik
Jack Do Hays
Richard Wieschman
David Ho Carleton
Ron Hoops
George Powers
R. Phipps
H.A. Cantor
John To Mass.engale
CoCo Taylor
C.N. Brunner
W,F. Boswell
Ro Theile
E.B. Gienger, Jr.
A. Kulka
RoMo Shepherd
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The patience and diligence of the secretarial staff in
typing drafts and numerous revisions is also gratefully acknowledged:
Ms. Elaine MacArthur
Ms. Georgette Molter
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TABLE OF CONTENTS
PARAGRAPH TITLE PAGE
SECTION I. STATUS AND OUTLOOK SUMMATION
1.0 OBJECTIVE AND SCOPE OF THE REPORT 1
1.1 MANUFACTURE AND DISTRIBUTION OF VINYLIDENE CHLORIDE .4
1.1.1 Manufacturing Processes and Sites . . . , 4
1.1.2 Sales and Distribution ...4
1.1.3 Shipping and Handling 5
1.1.4 Environmental Fate 5
1.1.5 Market Factors <. 6
1.2 CONSUMPTION OF VDC FOR 1,1,1-TRICHLOROETHANE (METHYL
CHLOROFORM) . . 6
1.2.1 Consumption Processes and Sites . 6
1.2.2 Environmental Fate. . 8
1.2.3 Distribution and Market Factors 8
1.3 CONSUMPTION OF VDC IN POLYMERIZATION PROCESSES. 9
1.3.1 Polymerization Processes and Sites. . . 9
1.3.2 PVDC Converting Processes, Sites and End Products . 10
1.3.3 Environmental Fate of VDC in Polymerization Process 14
1.3.4 Disposal and Ultimate Fate of the Polymer 15
1.3.5 Environmental Fate of VDC During Converting Processes 16
1.3.6 Market Factors for VDC Polymer End Products 16
1.4 TRENDS . ..20
1.4.1 Trends in VDC Production 21
1.4.2 Trends in PVDC Consumption In End Use Markets .... 0 ... ..26
1.5 POTENTIAL IMPACT ON HEALTH AND THE ENVIRONMENT ........ 35
REFERENCES FOR SECTION I 37
SECTION II. PHYSICAL AND CHEMICAL PROPERTIES OF VINYLIDENE CHLORIDE,
POLYVINYLIDENE CHLORIDE, 1,1,1-TRICHLOROETHANE AND CHLOROACETYL CHLORIDE
2.1 INTRODUCTION 39
2.2 VINYLIDENE CHLORIDE (VDC) 40
iii
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TABLE OF CONTENTS (CONT.NUED)
PARAGRAPH TITLE • PAGE
2.2.1 Physical Properties . . . . 40
2.2.2 Chemical Properties and Reactions .... 40
2.3 POLYVINYLIDENE CHLORIDE . . . . 4'3
2.3.1 Physical Properties 43
2.3.2 Chemical Reactions 52
2.4 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM) 55
2.4.1 Physical Properties 55
2.4.2 Grades 56
2.4.3 Chemical Reaction 56
2.5 CHLOROACETYL CHLORIDE 60
2.5.1 Physical Properties ... 0 ..... 60
2.5.2 Chemical Reactions 60
REFERENCES FOR SECTION II . „ 62
SECTION III. MANUFACTURING PROCESS STUDY
3.1 PRESENT STATUS OF THE INDUSTRY 64
3.2 MANUFACTURING SITES . 66
3.3 MANUFACTURING PROCESSES 67
3.4 DEVELOPMENT OF NEW TECHNOLOGY 68
3.5 PRODUCTION MARKETS 70
3.6 TRANSPORTATION AND HANDLING OF VINYLIDENE CHLORIDE 70
3.6.1 Mandatory Regulations for Vinylidene Chloride 71
3.6.2 Voluntary Regulations for Vinylidene Chloride 74
3.6.3 Handling Procedures and Hazards 77
3.6.4 Transportation Methods 79
3.6.5 Storage Methods 79
3.6.6 Accident Procedures 82
3.7 ENVIRONMENTAL MANAGEMENT FOR VINYLIDENE CHLORIDE
MONOMER PRODUCTION 83
REFERENCES FOR SECTION III 87
iv
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TABLE OF CONTENTS (CONTINUED)
PARAGRAPH TITLE PAGE
SECTION IV. CONSUMPTION PROCESSES STUDY
4.1 PRESENT STATUS OF THE INDUSTRY 39
4.2 1,1,1-TRICHLOROETHANE MANUFACTURE 91
4.2.1 Manufacture from Vinylidene Chloride 91
4.2.2 Alternate Routes of Manufacture 94
4.2.3 Development of New Technologies 95
4.2.4 Environmental Management of VDC in 1,1,1-Trichloro-
ethane Processes 95
4.3 POLYMERIZATION PROCESSES 96
4.3.1 Emulsion Latex and Suspension Polymerization ,96
4.3.2 Solid Resins 97
4.3.3 Modacrylics 99
4.3.4 Development of New Technologies 102
4.3.5 Polymerization Processing by Site . 102
4.3.6 Environmental Management of VDC Monomer in Polymerization
Processes „ 102
4.4 POLYMER CONSUMPTION PROCESSES 107
4.4.1 Film Extrusion 107
4.4.2 Coating Processes 110
4.4.3 Specialty Latexes .... 113
4.4.4 Environmental Management. 114
4.5 MARKET STUDIES FOR VINYLIDENE CHLORIDE CONSUMPTION 117
4.5.1 1,1,1-Trichloroethane (Methyl Chloroform) 117
4.5.2 Polymers of Vinylidene Chloride 119
4.6 TRANSPORTATION AND HANDLING OF POLYVINYLIDENE CHLORIDE
1,1,1-TRICHLOROE THANE (METHYL CHLOROFORM).. . .135
4.6.1 Transportation and Handling of Polyvinylidene Chloride . . . .135
4.6.2 Transportation and Handling of 1,1,1-Trichloroethane
(Methyl Chloroform) 135
REFERENCES FOR SECTION IV 144
SECTION V. USE ALTERNATIVES FOR VDC AND ITS END PRODUCTS
5.1 INTRODUCTION 146
v
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TABLE OF CONTENTS (CONTINUED)
PARAGRAPH TITLE PAGE
5.2 1,1,1-TRICHLOROETHANE 147
5.2.1 Production Alternatives 147
5.2.2 End Use Alternatives 148
5.3 POLYMERS OF VINYLIDENE CHLORIDE 148
5.3.1 Alternative Chemicals and Processes 148
5.3.2 End Use Alternatives .149
REFERENCES FOR SECTION V 154
SECTION VI. OVERALL MATERIALS BALANCE
6.0 OVERALL MATERIALS BALANCE 155
6.1 VINYLIDENE CHLORIDE MANUFACTURE 156
6.2 VINYLIDENE CHLORIDE CONSUMPTION 156
6.2.1 VDC Consumption in Manufacture of 1,1,1-Trichloroethane. . . . 156
6.2.2 VDC Consumption in Manufacture of Chloroacetyl Chloride. . . . 156
6.2.3 VDC Consumption in Polymerization 159
6.2.4 VDC Output from Polymerization Process 160
6.2.5 VDC Input/Output in Converting Processes 161
6.3 POLYVINYLIDENE CHLORIDE INPUT/OUTPUT SUMMARY H62
SECTION VII. SUMMARY OF CHEMICAL LOSSES
7.1 AIR EMISSIONS 164
7.2 SOLID. WASTE DISPOSAL 166
7.3 LIQUID EFFLUENT EMISSIONS 167
7.4 POTENTIAL FOR INADVERTENT PRODUCTION IN INDUSTRIAL PROCESSES . 168
7.5 SUMMARY OF GENERAL ENVIRONMENTAL POLLUTION BY VDC 169
7.6 SUMMARY OF OTHER CHEMICALS RELEASED TO THE ENVIRONMENT .... 169
REFERENCES FOR SECTION VII 171
VI
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LIST OF TABLES
TABLE TITLE PAGE
1-1 Input/Output Summary for Vinylidene Chloride Manufacutre
1976 7
1-2 Polymerization Sites and Type of Polymer Produced 11
1-3 Polymerization Processes, Products and End Products 12
1-4 VDC Production and Consumption Trends 1966-1976, Millions
of Pounds 22
1-5 PVDC End Market Proportions 27
1-6 Growth of Packaging Film Market (Millions of Pounds) .... 29 '
1-7 Comparative Costs of Coated and Uncoated Substrates .... 30 •
1-8 Projected Growth of Barrier Coatings 34
2-1 Physical Properties of Vinylidene Chloride 41
2-2 Compounds Forming Copolymers with Vinylidene Chloride
(Excluding Vinyl Chloride) 44
2-3 Compounds Forming Terpolymers with Vinylidene Chloride ... 45
2-4 Properties of Polyvinylidene Chloride 47
2-5 Crystallographic Data for PVDC Homopolymer 49
2-6 Comparison of the Permeabilities of Various Polymers to
Water Vapor 50
2-7 Permeability Coefficients for PVDC 50
2-8 Solvents for Polyvinylidene Chloride 51
2-9 Physical Properties of 1,1,1-Trichloroethane Uninhibited
and Inhibited Grades 57
2-10 Specifications and Typical Analyses for Two Grades of
1,1,1-Trichloroethane (Methyl Chloroform) 58
2-11 Physical Properties of Chloroacetyl Chloride 61
3-1 Production Sites and Capacities for VDC, 1976 66
3-2 Rules and Regulations for Transporting Vinylidene Chloride . 73
3-3 National Fire Protection Association Hazard Ratings for
Vinylidene Chloride Under Fire Conditions 76
3-4 Estimated Losses of VDC by Manufacturing Site 85
vii
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LIST OF TABLES
TABUE TITLE PAGE
4-1 Estimated Consumption Patterns for Vinylidene Chloride, 1976,
Millions of Pounds 92
4-2 Plant Sites for Polymerization of Vinylidene Chloride 101
4-3 VDC Emissions Losses at Major Polymerization Sites 103
4-4 Production of 1,1,1-Trichloroethane in Millions of Pounds. . . . 118
4-5 Calculated Consumption of VDC for 1,1,1-Trichloroethane
Production 118
4-6 Manufacturers of 1,1,1-Trichloroethane 119
4-7 Commercial Applications of Saran Wrap . . . 121
4-8 Major Extruders of PVDC Film 121
4-9 Current Production of PVDC Film 123
4-10 Cellophane Market 125
4-11 PVDC-Coated Cellophane Production, Millions of Pounds 127
4-12 Consumption of VDC as a Latex Coating 128
4-13 Major PVDC Latex Barrier-Coating Users 129
4-14 Producers of Specialty Latex Resins 131
4-15 U.S. Consumption of Modacrylic Fibers ..... 134
4-16 Rules and Regulations for Transporting 1,1,1-Trichloroethane . . 137
5-1 Transmission Rates for Plastic Films 150
5-2 Barrier Properties of Saran-Coated Films 152
7-1 Summary of Environmental Losses,.(1975) 165
viii
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LIST OF ILLUSTRATIONS
FIGURE
1-1
1-2
1-3
2-1
3-1
3-2
3-3
4-1
4-2
4-3
4-4
4-5
4-6
4-7
6-1
6-2
TITLE
Estimated Consumption of VDC in Production of
Estimated Losses for VDC Monomer from all Sources in 1975 . . .
Chain Structure of Polyvinylidene Chloride Eomopolymer ....
Typical Tank Car Unloading Station for Vinylidene Chloride . .
Estimated Losses for VDC Monomer from Monomer Producers in
1975
Block Flow Diagram for 1,1,1-Trichloroethane Production ....
Estimated Losses for VDC Monomer from Polymer Producers in
1975
Estimated Losses .of VDC Monomer from Converters in 1975. . . .
Vinylidene Chloride Input-Output Flow Diagram . .
Percentage Distribution of VDC Output
PACE
23
25
36
46
69
80
84
93
98
100
104
109
112
116
157
158
ix
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SECTION I» STATUS AND OUTLOOK SUMMATION
1.0 OBJECTIVE AND SCOPE OF THE REPORT
Vinylidene chloride (VDC) has been in extensive commercial
use since the early 1940's, when copolymerization and plasticiza-
tion techniques were developed at Dow Chemical Company. The chief
resultant copolymers of VDC, known as saran or polyvinylidene chloride,
have been produced continuously since that time.
Saran exhibits certain physical properties which render .
it ideally suited for use as a packaging film or barrier coating
on other materials used in the food packaging industry. These
properties include high barrier resistance to water vapor and other
gases such as oxygen and carbon dioxide, grease and oil resistance,
and flavor retention. In addition, saran is free of taste and odor,
has good heat seal properties, is flexible and abrasion resistant
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and has good printing qualities. Although a number of other poly-
mers can act as a substitute for saran in its applications as a
packaging film or barrier coating, none possess the same barrier
resistance to both oxygen and water vapor for a given film thick-
ness.
The discovery in the early 1970's that vinyl chloride was
a carcinogen at relatively low concentrations (20 ppm)* for chronic
exposures, prompted a reexamination of other chemicals which had
previously been regarded as safe, or having only acute toxicity
effects at high concentrations. Vinylidene chloride came under ex-
amination because of its structural similarity to vinyl chlorides
H H H ,C1
'
H Cl H
Vinyl Chloride Vinylidene Chloride
However, as will be evident from Section II, its physical and chemical
properties are significantly different.
More recently, concern has arisen over the possibility
of the migration of residual traces of monomers from their poly-
mers. In this connection, both vinylidene chloride and acrylonitrile
were specifically singled out.
*National Institute for Occupational Safety and Health., 1975.
Regietery of_ Toxic Substances, p. 534.
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It is because of the history of vinyl-type monomers and
their associated health problems that this research study was under-
taken. The objective of the report is to present a detailed
analysis regarding the production, consumption and losses to the
environment of vinylidene chloride. Most but not all aspects of
the study are addressed directly. Its scope includes a detailed
discussion of the current manufacturing sites and processes for VDC,
its associated shipping and handling practices, production markets,
and environmental management during production. An equally detail-
ed presentation of the consumption processes and sites, environ-
mental management of the monomer in the various consumption pro-
cesses, and the consumption markets for polyvinylidene chloride
are- also given, However, the mate-rials history for the past
ten years could not be presented directly, since production figures
for neither VDC nor its copolymers are reported separately
to the U.S. International Trade Commission; the individual produc-
ers and consumers regard these figures as highly proprietary and
would not divulge them to AAI. Thus, estimates in this area are
based on documented assumptions and calculations, and are identified
as such. The toxicology of VDC and PVDC and related impacts on human
health are not within the scope of this report.
The information presented in the report was collected
from many sources. Most important were the on-site and telephone
interviews conducted with the producers of VDC, the producer of
1,1,1-trichloroethane (1,1,1-TCE) from VDC, the polymerizers of
VDC, and representatives of the companies converting or otherwise
handling VDC-containing polymers. In addition, data were^obtained
from the published literature, from trade associations, and repre-
sentatives of state and federal agencies. The degree to which cer-
tain data were regarded as confidential, and the level of coopera-
tion obtained, varied widely among the industries concerned and the
individual companies contacted. This is reflected in the degree of
accuracy in the data reported by the various companies contacted in
the course of the study.
3
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1.1 MANUFACTURE AND DISTRIBUTION OF VINYLIDENE CHLORIDE
Vinylidene chloride is one of a number of chemicals which
are produced directly or indirectly from the chlorination of ethylene
or ethane. It is currently manufactured domestically by two companies,
PPG Industries and Dow Chemical Company, at an annual rate of approx-
imately 270 million pounds.
1.1.1 Manufacturing Processes and Sites
PPG currently produces about 170 to 180 million pounds of
VDC annually at its plant in Lake Charles, La. Dow Chemical Co.,
produces about 100 million pounds per year at two plant locations,
Freeport, Texas and Plaquemine,La. It is reported that the Freeport
plant produces about two-thirds of Dow's annual production.
Vinylidene chloride is made either as a coproduct of ethylene
dichloride, produced from the chlorination of ethane or ethylene, or
by the dehydrochlorination of 1,1,2-trichloroethane according to the
following reaction:
CH2C1-CHC12 -I- NaOH * CH2 = CC12 + Nad + H20
Dow uses both processes. The choice is economic and varies
with market demand and prices of the coproducts.
PPG currently produces VDC from the dehydrochlorination
of 1,1,2-trichloroethane.
1.1.2 Sales and Distribution
Both PPG and Dow consume captively about 85% of the total
VDC manufactured each year. The balance, or about 40 to 50 million
pounds, enters the merchant market. PPG uses about 130 million pounds
of VDC to produce 1,1,1-trichloroethane; Dow uses about 80 to 90 million
pounds to produce various polymers of VDC.
Approximately 11 companies buv VDC monomer from either PPG
or Dow to produce a wide variety of polymeric products containing VDC.
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Because of hazards inherent in the storage and handling of
VDC, storage is limited to the amount needed to meet the operating demand
of the consumer companies. This, combined with a reasonably stable
supply situation, makes stockpiling VDC monomer infeasible.
1.1.3 Shipping and Handling
VDC is usually shipped in bulk railroad tank cars or tank trucks.
A small quantity is shipped in drums. To prevent the formation of
peroxides and spontaneous polymerization, VDC is shipped inhibited (usually
with monomethyl ether of hydroquinone) and under a nitrogen blanket.
Even under these conditions, it is recommended that storage not exceed
four months.
Tank cars or tank trucks used to transport VDC are dedicated
to that service. Suitable precautions in loading and unloading transport
equipment should be used to prevent contact with air or water. Copper,
aluminum and their alloys should not be used in contact with VDC
monomer.
Stainless steel or nickel are the recommended materials
of construction for storage containers. Non-lubricated valves and
fittings are specified.
1.1.4 Environmental Fate
VDC emitted to the air during manufacture or its subsequent
polymerization is reported to react, under specific conditions, to
form peroxide and epoxide compounds which tend to decompose spontaneously
to form HC1,CCC1?, various oxygenated organic chlorides, ethylene
dichloride and chlorinated olef ins. The bulk (757.) of VDC loss
emissions are process derived; the balance result from storage, transfer
and filling operations.
Based on data supplied by the producing companies, total VDC losses
during manufacture are in the range of 0.0012 to 0.0031 Ibs. per pound produced.
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Table 1-1 summarizes estimated production, consumption
and environmental manufacturing losses for 1975-76.
1.1.5 Market Factors
Based on the present evaluation of the market, it is estimated
that approximately 130 million pounds of VDC are consumed captively
in the production of 1,1,1-TCE, 135 million pounds are polymerized, and
5 million pounds are used as a chemical intermediate.
The demand for VDC polymers has grown at an average rate of
5 percent per year since 1970. Since the major application of PVDC is in
the production of flexible film for food packaging, demand for the
polymer is closely tied to the market requirements and economic constraints
of this industry. Although this market is growing rapidly, chiefly in the
area of snack and convenience foods, the changing pattern of packaging mat-
erials is such that the future growth of VDC for polymerization is expected
to continue at about the same level as the general economic growth.
The demand for VDC as a raw material for 1,1,1-TCE appears
to have increased since PPG built its plant in 1967. PPG is the only
company presently manufacturing 1,1,1-TCE from VDC. It is reported
that when PPG's new plant for 1,1,1-TCE is put into operation in 1978,
it will use a new process that does not have VDC as the feed stock. PPG
will no longer have a captive use for its VDC. However, according to
industry reports, PPG will maintain facilities capable of producing
an anticipated 75 million pounds of VDC per year for merchant sales
to polymerizers.
1.2 CONSUMPTION OF VDC FOR 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)
1.2.1 Consumption Processes and Sites
1,1,1-TCE is manufactured at PPG's chlorinated hydrocarbon complex
plant in Lake Charles, La., by hydrochlorination of VDC, according to
the following reaction:
•6
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TABLE 1-1. INPUT/OUTPUT SUMMARY FOR VINYLIDENE CHLORIDE MANUFACTURE 1976
Company
Site
Estimated VDC Sales Distribution
Capacity 10b Iba/yr
VDC End Use Patterns
10 Ibs/yr
Estimated Manufacturing
Losses Ibs/year
PPG
DOW
TOTAL
Lake Charles, La.
Plaquemine, La.
Freeport, Tx.
10** Ibs/yr Captive Merchant
170 - 180 140 - 150 20 - 25
1,1.1-TCE
140 - 150
95 - 100
265 - 280
75 - 85 15 - 20
215 - 230 35 - 45
140 - 150
Polymers
20 - 25
95 - 100
115 - 125
Chemical
Intermediate
200,000 - 300,000
238,000
100,600
538,600 - 638,600
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CC12 + KC1
This is the only site at which 1,1,1-TCE is produced from VDC. 1,1,1-
TCE is also manufactured by Dow Chemical Company and Vulcan Chemicals
using other routes for its manufacture which include chlorination of
vinyl chloride, or direct chlorination of ethane. The specific process
used by the various manufacturers is dependent on the company's proprietary
technology, the desired product mix, and the economics of the overall
operation.
1.2.2 Environmental Fate
Losses of VDC from the PPG plant during the production of
1,1,1-TCE are reported to be non-existent •, because the process is con-
tinuous and all equipment is interconnected. Unreacted VDC and
HC1 are separated from the hydrochlorination product stream by dis-
tillation and recycled to the hydrochlorinator for further reaction.
The product is reported to contain a maximum of 100 ppm VDC.
Based on an estimated production of 1,1,1-TCE from VDC of 175 million
pounds in 1976, the possible amount of VDC monomer in the 1,1,1-TCE
sold in the U.S. could equal 17,500 pounds per year. The commercial
distribution of 1,1,1-TCE is so wide-spread that local concentrations
of VDC monomer would not exceed an order of magnitude of 0.006 pounds
per square mile.*
1.2.3 Distribution and Market Factors
1,1,1-TCE has many commercial uses and its distribution ranges
from large industrial users to small commercial establishments. From
1963 to 1973 the overall demand for 1,1,1-TCE grew at an average rate
of about 10 percent, dropping to an average of 2.5 percent per year over
the period 1973 to 1976. This slowdown in demand was attributed to the
setbacks to the U.S. economy with resultant decreased demand for such items
"-Calculated using area of continental U.S. equal to 2.98x10 sq. mi.
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as appliances, automobiles, housing and other metal fabrication products
that require a degreasing operation. Although the demand for VDC as a raw
material for 1,1,1-TCE has increased since 1967, paralleling PPG's sales, it
is expected to drop to nil when PPG's new process for 1,1,1-TCE becomes
operational in 1978.
1.3 CONSUMPTION OF VDC IN POLYMERIZATION PROCESSES
Vinylidene chloride monomer is copolymerized with other monomers
to form a variety of products with specific properties. Polymers
containing more than 50% VDC, usually in the range of 70 to 95%, exhibit
superior barrier properties to oxygen, water vapor and other gaseous mater-
ials, and are chemically inert. The comonomers most used in this
application are vinyl chloride, acrylic acid, and acrylonitrile. This
type of VDC copolymer may be used as a latex to coat various film sub-
strates such as paper products, polyester, polypropylene or polyethylene to
improve the barrier properties of the substrates. It may also be
converted into a film (saran) and used as such or laminated to other
plastic films * Again these films are used where superior barrier
properties are desired.
VDC is used in polymers containing less than 50% VDC, usually
in the range of 10 to 40% in order to improve the flame retardant properties
of the base polymer. Typical of this application are copolymers with
butadiene-styrene, used as carpet backing, and the modacrylic fibers.
There are some minor applications of VDC polymers for pipe or
pipe liner due to their chemical resistance.
1.3.1 Polymerization Processes and Sites
Vinylidene chloride polymers, like polymers of vinyl chloride,
are produced using either emulsion or suspension polymerization techniques.
Resin powder is prepared by filtering or centrifuging the polymer obtained
by emulsion or suspension techniques, and drying the resultant wet
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solids. The two polymerization techniques use essentially similar equipment.
The processes differ in such details as the type and quantity
of surface active agents used, the operating conditions, and stripping
techniques.
The reactants (VDC, comonomer, catalyst, emulsifier or
suspending agent, and water) are fed into an evacuated reactor. The
batch is heated and agitated for between 8 and 24 hours until the desired
degree of polymerization is obtained (90 to 98%). The polymerized batch
is stripped of unreacted monomer (in situ or transferred to a stripper
vessel) using steam and vacuum. The stripped VDC monomer may be recovered
and recycled, vented to a disposal system or vented to the atmosphere.
Solvent polymerization has been used in the copolymerization
of VDC with other monomers such as acrylonitrile to produce a textile
fiber by the use of wet spinning processes. A more generally used
process is to manufacture the dry polymer in conventional equipment,
dissolve the resin in a suitable solvent and then use a wet spinning
process.
There are approximately 13 sites where VDC is polymerized.
The sites and polymer produced are shown in Table 1-2. The polymeri-
zation processes,products and end products are shown in Table 1-3.
1.3.2 PVDC Converting Processes, Sites and End Products
PVDC is sold to converters as either an emulsion latex or
a solid resin. At present only one converter, DuPont, polymerizes VDC
for captive use.
Emulsion latexes are sold to companies who convert paper
products and plastic film into packaging materials. These companies
use the latexes to coat the substrate film with a thin (1 to 3 mil
thick) layer of PVDC to provide improved barrier properties to oxygen and
water vapor.
10
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TABLE 1-2. POLYMERIZATION SITES AND TYPE OF POLYMER PRODUCED
Company
Dow Chemical Co.
Location
^Midland, Mi.
"/Dalton, Ga.
W.R. Grace Chemical ^Owensburg, Ky.
Company
Morton Chemical Co. ^Ringwood, 111.
A.E. Staley Mfg. Co. Lemont, 111.
Rohm and Haas Co. '/Knoxville, Te.
GAF Corporation Chattanooga, Te.
Reichhold Chemical
National Starch
and Chemical
/Ch
eswold, De.
\/
Meridosia, 111.
y
Tennessee Eastman Kingsport, Te.
Monsanto Chemical Co. Decatur, Al.
American Cyanimide vpensacola, Fl.
li.I. DuPont
Circleville, Oh.
Polymer Type
Latex Suspension
Latex Emulsion
Soild Resin
Latex Emulsion
Specialy Latex
Latex Emulsion
Latex Emulsion
Latex Emulsion
Latex Emulsion
Latex Emulsion
Specialty Latex
Latex Emulsion
Specialty Latex
Latex Emulsion
Specialty Latex
Modacrylic Fiber
Modacrylic Fiber
Modacrylic Fiber
Solid Resin
Estimated VDC Consumption
Capacity (millions of pounds)
10
5 to 10
<5
5
-------
TABLE 1-3. POLYMERIZATION PROCESSES, PRODUCTS AND END PRODUCTS
PROCESS
PRODUCT
END PRODUCT
Emulsion Polymerization
Latex Emulsion
Barrier coating on plastic
films and paper products
Fire retardant carpet backing
Resin
Barrier coating
Molded plastics
Extruded films and pipe
Suspension Polymerization
Resin
Solution coating for barrier
properties
Molded plastics
Extruded film and pipe
Solution Polymerization
Fiber (modacrylics)
Flame retardant textiles
-------
Because coating of packaging film substrate is a normal part of
a converting line, there are a substantial number of sites where PVDC
latexes are used or can be used, depending upon the demand. The major
converters and plant sites are given in Table 4.4 (see Section 4.2).
PVDC resin has three uses; (1) for solvent coating of plastic
film and cellophane (2) for film extrusion, and (3) for molding.
Solvent coating of cellophane with PVDC is limited to three
companies, Olin, DuPont and FMC, at three sites.
This process comprises dissolving solid resin in a suitable
solvent, coating the cellophane, removing solvent in a drying oven,
conditioning the coated, dried film and winding the coated film for
shipment to packaging converters. The solvent removed in the drying
step is recovered and recycled.
Except for Dow Chemical Co., none of the film producers make
a PVDC resin. Conventional plastic film making techniques are
used in PVDC film manufacture. PVDC film may be produced by using
either a flat extrusion process or blown film techniques. The latter
process can produce a "biaxially" oriented "shrink film". There are
four manufacturers of PVDC film for merchant sale and several captive
film producers.
Specialty butadiene-styrene latexes containing less than 50%
VDC find their greatest outlet as a flame retardant carpet backing sold
to carpet and rug manufacturers. There are a large number of companies
capable of applying this type of latex as a backing.
There are no "by-products" as such for these converting processes.
The PVDC waste products of packaging converting operations, consist of
scrap film. Losses of this nature can range from 25 to 50 percent based
on film weight.
13
-------
1.3.3 Environmental Fate of VDC in Polymerization Process
Losses of VDC monomer during polymerization can result from
the following:
(1) Vent losses during transfer of monomer feed to
and from storage tanks and reactors.
(2) Losses to the atmosphere from stripping operations,
where unreacted monomer is reduced to lowest possible
levels in the polymer emulsion product.
Minor losses of VDC monomer can occur as a contaminant in
polymer sewered during periodic washing of reactor and stripping vessel,
as well as from the disposal of unuseable (bad) batches.
Substantially 98% of VDC emissions from polymer plants result
from the stripping of unreacted monomer from the finished polymer
latex. Control methods include:
(1) Modification of the polymerization process to minimize
the amount of unpolymerized VDC remaining in the batch.
(2) Installation of systems to recover VDC monomer
from the stripper vent gases.
(3) Installation of incineration systems to destroy the
VDC in the vent gases.
Almost all manufacturers of polyvinylidene chloride are striving to
decrease the amount of unreacted VDC monomer left after the polymerization
reaction. The criteria for installing either VDCM recovery systems or
incineration equipment are economic, and related to the size of the VDC
polymer plant. At present, only the largest polymer producers have found
it economically feasible to install either of the latter two methods to
control VDC emissions.
On the basis of reported polymerization losses from the smaller
polymer producers of 0.6% to 1.2%, emissions would range from 16 Ibs.
per day per million pounds VDC polymerized annually to 32 Ibs. per day.
Hence a plant polymerizing 10 million pounds per year of VDC would prob-
ably vent about 200 pounds of VDC per day.
14
-------
For those plants producing specialty latexes, such as the
VDC formulated flame retardant carpet backing, where conversion rate
is the lowest (90%) and VDC concentration in the feed is lowest
(under 40%) we find that the pounds of VDC emitted per 100 Ibs. VDC
polymerized are on the order of 1.26 for the largest and 2.8 for the
smallest companies. At present, the amount of VDC used in these
polymers is low (estimated at 7 to 9 million pounds per year) and based
on an average loss of 1.5%, the probable total loss from this source
is calculated to be betx^een 105,000 and 135,000 pounds per year.
It has been estimated that a total of about 520,000 pounds of
VDC monomer were lost to the atmosphere in 1975 from polymerization
operations conducted at 13 sites. One of the major polymerizers reported
that the plant that produces more than 60% of their VDC polymers has reduced
emission losses from about 4000 Ibs. per day in 1972 to probably less
than 200 Ibs. per day in 1977.
Other VDC monomer losses occur in the liquid wastes disposed by
polymer manufacturers to sewerage disposal facilities. This loss is
estimated to be between 3000 and 4000 pounds per year.
1.3.4 Disposal and Ultimate Fate of the Polymer
Over 95 percent of VDC polymers are used for packaging, in
the manufacture of textile fibers or as a component of flame
retardant carpet backing. These are all consumable items that are
thrown away at the end of their useful life. The ultimate disposal
is either the incinerator or solid waste land fills. Only a small
percentage of the PVDC enters the capital goods industry (chiefly
as pipe or a lining in pipe) where the useful life is relatively long.
Over the past 10 years it is estimated that between 700 million
and 1 billion pounds of PVDC have been ultimately disposed in the manner
noted above. Based on an estimated VDC monomer content of the converted
polymer ranging from a possible maximum of 60 ppm in 1966 to under
5 ppm in 1976, it can be postulated that between 25,000 and 50,000 Ibs.
of VDC monomer could have entered the environment from the finished
products during the past 10 years.
15
-------
1.3.5 Environmental Fate of VDC During Converting Processes
Significantly lower levels of VDC monomer in PVDC latexes and
solid resins have been achieved by the polymerizers since 1971. One
company stated they have reduced the content of VDCM in polymer emulsions
from over 600 ppm in 1971 to about 25 ppm in 1976. The average VDCM content
of the polymers currently produced in the U.S. is on the order of 50
ppm for the latexes and 20 ppm for the resins. Based on this range of
monomer content, and an average yearly VDC polymer production (exclusive
of specialty polymers and fibers) equal to 85 million pounds, it can be
calculated that between 2200 and 4200 pounds of VDC monomer were contained
in the polymers shipped to converters in the past year.
About 85 to 90% of this would be released during the converting
process, leaving an estimated 330 to 450 pounds of VDC monomer in the
converted product as sold to the final customer.
1.3.6 Market Factors for VDC Polymer End Products
Vinylidene chloride polymers have three properties that make
them unique among the various film forming polymers.
(1) Excellent barrier resistance to gases,
water vapor, organic vapors and odors.
(2) Flame resistance.
(3) Chemical inertness.
The major markets for VDC polymers are in packaging of foods of all
types where preservation of freshness is dependent on maintaining a
barrier to oxygen and water vapor.
Since PVDC barrier properties far exceed those of currently
used packaging materials, coatings as thin as 1 mil on films with
less effective barrier resistance are competitive with most other film
constructions made entirely from cheaper, but heavier film.
The market factors for this use are dependent on the product
to be packaged and the cost-effectiveness ratio of PVDC film or coated
films versus that of other packaging materials. For example, there is
16
-------
no effective shrink wrap film that can compete with Saran or Saran
laminates for packaging fresh meats, cheese or frozen poultry. The
snack food market is dependent on saran coated packaging films to main-
tain freshness and package integrity.
In the area of flame resistance, VDC competes with many other
products, both organic and inorganic. The basic market factors are cost-
performance compared to other materials, durability, and government
regulations. Competetion in this area is strong. Unless government require-
ments for flame retardant textiles or textile products become more
stringent, demand for VDC in this area will not be strong.
There are many, less expensive chemically inert materials
currently available. Hence use in areas where this property is important
will remain limited.
Imports are not a factor in the United States markets. It has
been reported that one company, Union Carbide, imports about 3 million
pounds of resin annually for film-extrusion. Dow reports exports of about
20 million pounds of VDC polymer products, mostly to Canada, Australia,
Latin American and Europe,
1.3.6.1 Extruded Film
Extruded monolayer PVDC film is used as a flexible packaging
material for meats, poultry and cheese. Over the past ten years this
market has grown steadily at a rate of about 10 percent per year. A
recently developed process that can produce a multi-layer sandwich film
laminate by combining a 1 mil layer of expensive Saran with heavier
layers of less expensive plastic film is tending to supplant the mono-
layer Saran film. The multi-layer laminate consists of PVDC sandwiched
between other plastic films, such as:
Polyethylene - PVDC - Polyethylene
Polyester - PVDC - Polyethylene
Nylon - PVDC - Polyethylene
The laminate uses only one-seventh the weight of PVDC currently
required for the monolayer film. One film producer noted that if mono-layer
17
-------
film is phased out in favor of the laminate during the next five
years, in which an overall expansion of the flexible film market in
the food industry of 5 to 10 percent per year is predicted, demand
for PVDC for film over the next five year period will remain fairly
static. Once the laminate consumption has stabilized, PVDC demand is
predicted to resume its growth rate of 5 to 10 percent over the
following five years.
The growth rate for household saran wrap is very small (two
to three percent yearly), and is not expected to exceed general popu-
lation growth. Current publicity concerning the possible hazards of
residual VDC in saran wrap* could have a negative impact on the • consumer
market.
1.3.6.2 Barrier Coatings
The market for flexible film packaging materials in the
food industry is highly competitive, and dependent upon a combination
of such factors as price, printability, convertability, handling
characteristics in packaging machines and in the store, and the ability
to preserve the freshness of the stored food. PVDC films (Saran wrap)
are expensive, but when used as coating, PVDC imparts its barrier resis-
tant properties to a substrate that is either cheaper or has other
desirable physical properties lacking in the PVDC film. Substrates
coated with PVDC or saran include:
• Cellophane
• Paper, paperboard and glassine
• Plastic films such as polyethylene,
polypropylene, polyester and nylor,
During the past six or seven years'the saran-coated film
market has sustained a growth of about five percent yearly, despite
fluctuations in demand for a given coated substrate. Thus, although the
PVDC coated paper product market has decreased, this decrease has been
offset by significant increases in the coating of polypropylene and
polyester films. In the case of cellophane film, we find that although
*See, for example, Brody, (1977), Chemical Marketing Reporter, (1977)
Chem. Eng. News (1977) and Chemical Week (1977).
18
-------
the total volume of cellophane has decreased, the percentage of
cellophane coated with PVDC has increased. The net effect in this
sector is a relatively constant demand for PVDC. However this demand
will tend to decline by 1980.
A slow net growth of PVDC consumption in the food packaging
industry should continue over the next five years at a rate of three
to five percent annually, mainly attributed to growth in the use of
PVDC coated polypropylene and polyester.
1.3.6.3 Specialty Latexes
The market factors affecting VDC consumption in the manufacture
of fire retardant latex carpet backing are a combination of economic
and legislative considerations. Alumina, PVDC or a mixture of these
materials are used to impart flame retardancy to the butadiene-styrene
latex backing. Currently, only about 10 percent of flame retardant back-
ing contains PVDC, equivalent to the consumption of seven to eight
million pounds VDC monomer.
Growth of this market is slow and not expected to exceed
the general expansion rate of the economy. Negative growth impacts
could be sustained if :the small producers opt to close manufacturing
plants rather then expend the capital to reduce emissions during polymer-
ization.* However, PVDC could capture a greater share of the
flame retardant rug-backing market if the cost of alumina increased
relative to the price of PVDC, or if more stringent federal regulations
concerning fire retardancy in rugs and carpets are passed, particularly
in the consumer area (current legislation is aimed more at carpet for
industrial and commercial use).
1.3.6.4 Textile Fibers
The market growth for modacrylic fibers, made by copolymeri-
zing 10 to 30 percent VDC with acrylonitrile, has been unique in the
*
One company producing VDC copolymers for carpet backing closed one
of its two plants for this reason within the past year.
19
-------
synthetic textile industry for its slowness. The modacrylics are
produced solely for their flame retardant character to satisfy the
need for this property in sleepwear, drapery fabric, and automobile
upholstery.
Growth of this market has been impeded by the poor "hand"
or physical characteristics of this fiber, the slow development of
government regulations concerning flame retardancy for wearing apparel
and home furnishings, and the relatively high cost of the fiber.
The consumer tends to ignore the potential benefits of flame retardancy,
preferring a less expensive and more attractive fabric. The market
for modacrylics is expected to sustain slow to moderate growth, about
five to eight percent annually.
1.4 TRENDS
Two basic problems were encountered in trying to provide
a picture of the VDC production and consumption markets over the
past ten years. Vinylidene chloride is manufactured by only two
companies, and does not fall under the reporting requirements of
the U.S. International Trade Commission. Thus, statistics on produc-
tion are not published in Synthetic Organic Chemicals - U.S. Produc-
tion and Sales, and must be derived from other data.
Further, sales and volume data on polyvinylidine chloride
are not reported separately in the Plastics and Resins Materials
section of the above mentioned publication. They are included in
the category "Other Vinyl Resins." The footnotes state this category
includes polyvinyl butyral, polyvinyl formal, PVDC latex, and PVDC
solid and solvent resins. However, the footnotes are not consistent
from year to year, and in two years (1973 and 1975) PVDC latex resins are
broken out as a separate category. The only end product of VDC
for which ITC data is reported is 1,1,1-trichloroethane, and VDC
is not the sole raw material from which this product is derived.
Companies polymerizing VDC gave general information on
current consumption of PVDC in end use sectors. Interviews with
the coating converters yielded little specific information on in-
dividual consumption of PVDC in the various end use areas they sup-
20
-------
plied since they regard this data as highly proprietary. Overall
growth data on various packaging materials is published in the Modern
Packaging Encyclopedia.
1.4.1 Trends in VDC Production
Based on various published data and industry estimates
collected during the course of this study, the amount of VDC pro-
duced for the past 10 years has been calculated and is shown in
Table 1-4. The VDC production is calculated based on estimates of
its consumption in 1,1,1-TCE and VDC copolymers:
(1) VDC Consumption for 1,1,1-TCE Manufacture
These calculations are based on U.S. International
Trade Commission (ITC)*reports in Synthetic Organic
Chemicals: U.S. Production and Sales, for the pro-
duction of 1,1,1-TCE and on the approximation
(Lowenheim and Moran, 1975) that 307, of 1,1,1-TCE
is derived from VDC. The appropriate stoichiometric
factors for the reaction were applied.
(2) VDC Consumption in Polymers
VDC polymer production is taken from the Plastics
and Resins Materials: U.S. Production Sales section
of the Synthetic Organic Chemicals: U.S. Produc-
tion and Sales (U.S. International Trade Commission).
There is an entry reported for "Other Vinyl and
Vinylidene Resins." Assumptions were made as to
the production of polyvinyl butyral based on es-
timates of its use in the auto industry (Sczesny,
1977). Assumptions as to the production of poly-
vinyl formal and other vinyl resins were based on
Chemical Marketing Reporter Chemical Profiles on
selected resins (see for example, Chemical Market-
ing Reporter, April 1, 1976.) relating production
of various vinyl resins to their raw material sources.
The estimated consumption of VDC in the production
of polymers over the past 10 years is shown graphic-
ally in Figure 1-1.
*Prior to 1975 this organization was known as U.S. Tariff Commission (TC)
21
-------
TABLE 1-4. VDC PRODUCTION AND CONSUMPTION TRENDS 1966-1976, MILLIONS OF POUNDS
Estimated VDC Consumption
in Polymers
a) Based on ITC data*
b) Based on SPI data
c) Milgrom, 1976
d) This Report
VDC Consumption for
1,1,1-TCE
TOTAL VDC CONSUMED****
Chemical Intermediate
Losses
a) VDC equivalent
vented to
atmosphere
b) VDC equivalent
lost as solid
polymer
TOTAL VDC PRODUCED
1966
73
53
126
1967
79
59
138
1968
84
66
150
1969
95
71
166
1970
95
80
175
1971
n . a . **
82
a. a.**
1972
90
97
187
1973
96
120
216
1974
118
132
112
129
241
n . a .**
4.06
n.a.**
1975
143
118
100
243
1976
156
143
128*
130
258
5.0
1.06
7.8
271.8
NJ
*ITC data include U.S. Tariff Commission Data (1966-197.. and U.S.
International Trade Commission (1973-1976)
**Not available
***This figure does not include polymerization process losses
****Not including losses or uses as chemical intermediate
-------
l-o
10
M
O
O
TJ
O
O
O
3
o
350
300
® Based on ITC data
/«\ Based on SPI data
^ Milgrom, 1976
Q Auerbach Associates, Inc. report
250
200
150 i-
n
PROJECTED VDC CONSUMPTION
100
50 r —<—r—
1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
i
0
I -
1966 1967 1968
1985 1986
Figure 1-1. Estimated Consumption of VDC in Production of Polymers (U.S.T C
1968, 1969, 1970, 1971, 1972, 1974; U.S.ITC, 1975-1977; SPI, 1974
1975, 1976; Milgrom, 1976, AAI Estimates)
-------
There is some uncertainty with the U.S. ITC data as to
exactly what is included in the "other vinyl resins" category, other
than polyvinyl formal and butyral. It is possible that this data
includes a chlorinated polyvinyl chloride product^Geon,produced by
B. F. Goodrich, and having the same formula and molecular weight
as PVDC. Further uncertainty arises in the ITC reports footnotes
in the later years (1975 and 1976) which pin point only the formal
and butyral resins and omit "other vinyl resins" which are included
in the previous years. The ITC itself was unable to clarify this
question.
Similarly, some uncertainty as to possible co-reporting
of "Other Vinyl Resins" exists in the Society of the Plastics In-
dustry (SPI) data, which would also include Geon in this category.
(Society of the Plastics Industry, Inc., 1974, 1975, 1976).*
The estimated total VDC production is arrived at as the
sum of its consumption in 1,1,1-TCE and polymers. ITC data was
used for all polymer consumption except for 1974, where the figure
reported by Milgrotn (1976) was taken as being more accurate, and
for 1976, where the figure for VDC consumption in polymers calculat-
ed for this report was used (132 million pounds). This latter figure
is confirmed by PPG's estimate that the 1976 market for VDC polymer
products was about 135 million pounds (PPG Industries, 1976).
Trends in VDC consumption for the period 1966-1976 are
shown graphically in Figure 1-2. These production estimates are
based on calculations of consumption in polymers and in 1,1,1-TCE,
and do not include estimates regarding losses, which would increase
the production totals. Table 1-4 includes estimates on losses for
1974 (MLlgrom, 1976) and 1976 (made during the current study). The
VDC emission loss figures for 1976 are much smaller than for pre-
vious years due to improvement in both emissions control technology
and polymerization process technology.
*The SPI only includes vinyl butyral and vinyl formal in their
"Other Resins" category. This category does not include the
modacrylics, and may not include the flame retardant latex for
rug backing, depending on how the latex producer reported this
data.
24
-------
O
23
C/3
ro h0
t_n O
n
450
400
350 ...
300
250
200
1.50
100j
1966
1967 1968 1969 1970 1971
1972 19'73 19*74 1975
F YEAR
1984
1985 1986
Figure 1-2. Estimated Total Consumption of VDC
(U.S. TC, 1968, 1969, 1970, 1971, 1972, 1974; U.S. ITC, 1975-1977;
SPI, 1974, 1975, 1976; Milgrom, 1976; AAI Estimates).
-------
Further production of VDC is dependent on two major use areas:
1) Polymerization
2) Chemical intermediate, chiefly manufacture
of 1,1,1-TCE.
Trends for the growth of VDC consumption in polymer manu-
facture have been predicted by industry representatives as being
5 to 10% per year for the next 3 to 5 years. PPG's prediction tend-
ed to the higher range (7 to 10%) possibly because it included uses
of VDC in fiber manufacture and as a flame retardant (PPG, 1976).
Other industry sources indicate a somewhat lower growth rate over
the next several years of between 5 to 8%. Because of the uncertain-
ties of future economic prospects, including the influence of
government regulations and availability of energy and raw material
supplies, industry representatives were unable to predict growth
trends beyond a 3 to 5 year period.
According to published reports as well as direct confirma-
tion, PPG is expected to discontinue manufacture of 1,1,1-TCE from VDC
by 1978. This will decrease VDC consumption by about 130 million
pounds per year.
1.4.2 Trends in PVDC Consumption In End Use Markets
The major factor in the growth of PVDC consumption is
its application as a barrier material in the production and convert-
ing of food packaging materials. As Table 1-5* shows, over 70 per-
cent of the PVDC produced domestically (excluding exports) goes into
this industry. This market will thus have the greatest impact on
the growth of PVDC consumption.
After many years of continuous growth and relative price
stability, flexible packaging materials have entered a period of un-
certainty. Following the brief but sudden period of shortages in
*Polymerizers considered specific polymer production and sales
figures proprietary and would not release that data to AAI.
Hence end market proportions are calculated on the basis of
industry estimates.
26
-------
TABLE 1-5. PVDC END MARKET PROPORTIONS*
(Industry Sources and AAI Estimates)
MARKET
MILLIONS LBS
VDC CONSUMED
Flexible Packaging Film 78.5
Barrier Coating 21.5
Cellophane & Solvent Coating 18.0
Extruded Film 39.0
% DOMESTIC
USAGE
72.7
19.9
16.7
36.1
PERCENT OF TOTAL
61.4
16.8
14.1
30.5
Modacrylic Fibers
Carpet Backing
Other Uses
Export
TOTAL
17.5
7.9
4.0
20.0
128.0
16.3
7.3
3.7
100
13.7
6.2
3.1
15.6
100
*Based on VDC consumption and excluding exports
27
-------
1973 to 1974, and the ensuing price escalation, the volume of these
materials declined in 1975 for the first time since prior to 1960.
Since that time, the demand for film packaging materials
has resumed and is expected to follow the general economic growth.
Safety issues for the consumer concerning monomer migration could
both increase federal regulation and decrease consumer demand for
specific packaging films (Chemical Marketing Reporter, February
28, 1977.
The greatest growth in the packaging materials market
has resulted from the growth of snack food, frozen and pre-
packaged food and convenience food markets. It is in this
specific area that the barrier properties of PVDC find their
greatest application. Hence the growth of PVDC consumption will
be tied directly to the growth of these markets. Table 1-6 shows
the growth of the PVDC packaging film market for the period 1965-
1975, in relation to the growth of other packaging materials.
Table 1^7 compares the cost of saran and saran-coated substrates
with other flexible packaging materials.
As can be seen from Table 1-6, the use of PVDC as a
packaging film has been much less than that of polyethylene, vinyl
or polypropylene film, despite its superior properties for food
storage, remaining steady at about 10 percent annually. The higher
cost of PVDC (see Table 1-7), compared to other films or coated
substrates, is an important factor in its small share of the market.
Because it is more expensive, industry sources predict the growth
rate for saran as a household wrap will be slow (two to three per-
cent annually) and parallel growth in the population.
28
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TABLE 1-6. GROWTH OF PACKAGING FILM MARKET (MILLIONS OF POUNDS)
VD
(Modern Packaging
PVDC
Polyethylene
Cellophane
Vinyl
Polypropylene
Co-extrusions
Polystyrene
Nylon
Polyester
lonomer
Cellulose acetate
Phofilm
Miscellaneous
1965
20
615
405
30
40
-
10
4
8
-
5
15
1
1966
20
730
395
40
45
5
11
5
8
-
5
15
2
1967
20
735
385
70
50
15
12
5
8
-
5
10
3
Encyclopedia, 1975)
1968
22
795
360
90
65
20
13
5
8
-
5
7
5
1969
22
895
350
105
75
30
15
6
8
3
5
5
3
1970
22
975
340
115
85
34
15
7
8
3
5
3
3
1971
23
1,100
330
125
90
40
15
7
9
4
4
3
3
1972
25
1,200
320
135
100
46
15
7
10
5
3
3
4
1973
25
1,300
325
150
110
50
15
7
12
7
3
3
4
1974
25
1,375
335
160
115
55
15
8
13
9
3
3
4
1975
25
1,150
270
150
120
50
15
8
12
10
3
2
4
TOTAL
1,153 1,281 1,318 1,395 1,522 1,615 1,753 1,873 2,011 2,120 1,819
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TABLE 1-7. COMPARATIVE COSTS OF COATED AND UNCOATED SUBSTRATES
(Modern Packaging Encyclopedia,
COST TABLE: Papers, films, foils*
Material
1
Glassine, Bleached, 25 Ib.
Lacquered, MS2, 28 Ib.1 l
Laminated, amber, 47 Ib.
Bleached, 47 Ib.1
Waxed, amber, 29/37 lb.L
Saran coated, 25/30 Ib.
Pouch paper, Coated, MS, 25, 29 Ib.
Waxed paper, Bread wrapper, 39 Ib.
Liner, amber, M2, 25, 29 Ib.
Cellophane,
MS 195
MS 220
Saran-coated, 140
Saran-coated, 195
Saran-coated, 250
Polyethylene-coated, 182
Vinyl-coated, 220
Cellulose acetate, Cast, 1 mil
Cryovac S, 6/10 mil
Fluorohalocarbon, 1 mil
lonomer, 1 mil
Nylon, 1 mil
Pliofilm, 3/4 mil
Polypropylene, Cast , 1 mil
Balanced, uncoated, 3/4 mil
Bal., saran-coated, 0.75 mil
Bal., acrylic-coated, 0.84 mil
Unbal., uncoated, 0.73 mil
Bal., uncoated, 0.90 mil
Polystyrene, oriented, 1 mil
Polyester,
Nonheat-sealing, 3/4 mil
Nonheat-sealing, 1/2 mil
Saran-coated, 3/4 mil base
Saran-coated, 1/2 mil base
1-975)
Cost
$/lb.
$0.44
0.59
0.48
0.49
0.42
0.70
0.59
0.35
0.45
1.08
1.09
1.12
1.16
1.14
1.30
1.13
1.25
1.78
9.26
0.95
1.43
1.61
0.68
1.05
1.40
1.34
1.05
1.35
1.05
1.55
1.60
2.10
1.80
Cost c/1,000
sq. in.
2.5C
3.8
5.2
5.4
3.6
4.8
4.0
. 3.2
3.3
5.5
4.9
8.0
5.9
4.6
7.1
5.1
5.7
6.5
71.2
3.2
5.8
4.9
2.2
2.6
3.6
3.6
2.5
4.0
4.0
5.8
3.9
8.8
5.4
30
-------
TABLE 1-7. COMPARATIVE COSTS OF COATED AND UNCOATED SUBSTRATES (CONT'D)
Material
Polyethylene,
Low density, 1 mil
Medium density, 1 mil
High density, 1 mil ,
Heat shrinkable, 1 mil
Conventional
Cross linked
Polyethylene-cellophane, 1 mil/ 195 MS
Polyethylene-polyester, 1 1/2 mil/1/2
Saran, 1 mil
Vinyl, Cast, 1 mil
Extruded, 1 mil
Water-soluble film, 1 1/2 mils5
Aluminum foil, 0.00035 in.
0.001 in.
Foil-acetate, 0.00035 in. /I mil
Labels tock, 0.0003 foil 30 Ib. paper
Cost
$/lb.
$0.50
0.51
0.60
0.50
1.33
1.69
mil 1.99
1.78
0.96
0.71
1.75
0.86
0.69
2.58
0.57
Cost
-------
A larger and more rapidly growing sector of the saran
film market is in the area of frozen poultry, processed meats,
fresh meats, cheese and cookie dough packaging. This sector of
the saran film market is predicted to increase at the rate of 10%
per year for the next several years and then tend to level off
following the economic growth of the country.
A new development in this area is the development of
multi-layer laminates in an effort to make this type of barrier
film more competitive with other food packaging films. These
laminates, consisting of PVDC sandwiched between other plastic
films such as polyethylene or polyester, use as little as one-
seventh the weight of PVDC as the monolayer film, but provide
equivalent barrier properties.
Although the overall food packaging film market is pre-
dicted to increase at a rate of about 10% annually, the switch
to laminates should result in a static to slow growth rate of PVDC
demand for this application over the next five years. Once mono-
layer film for the food industry is stabilized, the PVDC market is
predicted to resume its growth rate of five to ten percent annually
(Greenough, 1976).
There are many areas of food packaging where saran film
or saran laminates are too costly compared with other packaging
materials. However, it would be desirable to impart barrier pro-
perties to these cheaper materials. This can be done by coating
these with a thin film of PVDC from a latex emulsion.
The growth area for these coated films has been in snack
foods which, according to industry estimates, had reached its growth
peak of 10% per year several years ago. It is reported that the
current rate of growth of this market is on the order of 5% per year.
32
-------
The trends for saran coating of paper, glassine, paper-
board and cellophane are viewed as remaining static or declining,
with the major growth predicted for the coating of polypropylene
and polyester. Table 1-8 summarizes the trends in market growth
for barrier coatings over the next five years.
Overall PVDC consumption growth for coatings is predicted to
average between five and ten percent annually, with declines in
some areas being offset by greater growth in coating of some plastic
films. No new uses for barrier coatings are forseen which would in-
crease the demand. It is anticipated the acrylic coating, particular-
ly on polypropylene, could provide some competition for PVDC coated
films.
The entire packaging materials market for food packaging
is very competitive. Price is a deciding factor, in most instances,
in the selction of the type film or paper product to be used for
a given job. Consequently new combinations of film are being develop-
ed in an effort to provide the needed protection at the lowest cost.
It has been noted (Thiele, 1976), that a major reduction in Saran
coating, particularly of paper and glassine could be expected in the
next five years as the result of the development of co-extruded
polyethylene-polyester film.
33
-------
TABLE 1-8. PROJECTED GROWTH OF BARRIER COATINGS*
Substrate
Paper, glassine
Paperboard
Cellophane
Polypropylene
Polyester
Estimated Annual
Growth Rate
Zero to decline
Declining rapidly
Zero to decline
10 to 20%
Comments
Losing out to high density
polyethylene, saran coated
films, such as cellophane,
polypropylene, for snack
food packaging
Losing out to polyethylene
coatings on paperboard
Losing out to polyethylene,
and PVDC coated polypro-
pylene and polyester film
Major growth areas for next
five years ; then growth
predicted to slow to 7 to
10%
*Based on interviews with PPG, Grace,
FMC, Oscar Meyer and other industry
sources
34
-------
1.5 POTENTIAL IMPACT ON HEALTH AND THE ENVIRONMENT
The flame retardant uses of VDC in polymers, as a mod-
acrylic fiber, or as a comonomer with butadiene-styrene, have had
a relatively smaller impact on the total VDC consumption. The
growth of this market has been influenced by the relatively high
cost of VDC as compared to other flame retardant materials. The
effect of government regulations on the use of other flame re-
tardants particularly in the textile field could influence the de-
mand for VDC. A recent example is the banning of TRIS by CPSC-
and its removal from use in the textile industry. However, it is
too early to determine the impact of this regulation on the use
of modacrylic fibers as a substitute.
The concentration of VDC monomer in the finished polymer
product as used in consumer applications has been reported to be
less than 10 ppm and in some cases below 1 ppm. These concentra-
tions are based solely on the monomer concentration related to the
PVDC content and do not include the weight of the supporting
substrate.
Industry sources reported that there has been a continuing
program to reduce monomer concentration in the polymer products to
the lowest possible level.
The environmental management of VDC monomer emissions at
both manufacturing sites and major polymerization sites has been
substantially improved during the past several years. Total emissions
have been reduced from that reported by Milgrom (1976) of about four
million pounds per year in 1974 to a reported one million pounds
per year in 1975-76. The estimated total emissions are shown geographi-
cally in Figure 1-3.
35
-------
LO
I? _._J
I' bm*HOMA \
COIIVERTOR5 3,538 Ibl
POLYMER PRODUCERS 418.380 Ibl
CCNVERTORS 1.298 Ibl.
MONOMER PRODUCERS 538,600 Ibs.
POLYMER FRODUCKHS 179,003 Ibs.
BASE MAP CCPYflCHJ
J.L. SMITH CO.. PHILADELPHIA
MONOMER PRODUCERS
POLYMER PRODUCERS
Figure 1-3. Estimated Losses for VDC Monomer from all Sources in 1975
(Industry Sources, 1976)
-------
SECTION I. REFERENCES
Brody, J.E. (1977), "Cancer Experts Warn of Dangers in Some Plastic
Wrap Chemicals," New York Times, February 23, A10.
Chem. Eng. News (1977), "Vinylidene Chloride Linked to Cancer,"
55(9), 6-7.
Chemical Marketing Reporter (1977), "Saran Chemical Cancer Cause,
Italian Researcher Concludes," 2JL1(9), February 28, 3.
Chemical Week (1977), 'Vinylidene Challenged," ^20(9), March 2, 17.
Greenough, F.W. (1976), W.R. Grace Co., Cryovac Div.
Personal Communication, Oct. 26, 1976.
Lowenheim, F.A. and M.K. Moran, editors (1975) Faith, Keys and Clark's
Industrial Chemicals. 4th Edition, Wiley-Interscience, Inc., New
York
Milgrom, J. (1976), 'Vinylidene Chloride Monomer Emissions from the
Monomer, Polymer and Polymer Processing Industries," Arthur
D. Little, Inc.
Modern Packaging, (1975), "Encyclopedia," 48(12).
PPG Industries, Inc. (1976), Personal Communication, September 23.
Sczesny, E.R. (1977), Guardian Industries, Personal Communica-
tion, April 5.
Society of Plastics Industry, Inc. (1974), "Statistical Reports on
Thermosetting and Thermoplastic Resins."
Society of Plastics Industry, Inc. (1975), "Statistical Reports on
Thermosetting and Thermoplastic Resins."
Society of Plastics Industry, Inc. (1976), "Statistical Reports on
Thermosetting and Thermoplastic Resins."
Thiele, R. (1976), American Bag & Paper Co., Personal Communication,
December 28.
U.S. International Trade Commission (1975), "Synthetic Organic
Chemicals: United States Production and Sales, 1973."
U.S. International Trade Commission Pub. 728,
Government Printing Office, Washington, D.C.
U.S. International Trade Commission (1976), "Synthetic Organic
Chemicals: United States Production and Sales, 1974."
U.S. International Trade Commission Pub. 776, Government
Printing Office, Washington, D.C.
U.S. International Trade Commission (1977), "Synthetic Organic
Chemicals: United States Production and Sales, 1975."
U.S. International Trade Commission Pub. 804, Government
Printing Office, Washington, D.C.
U.S. International Trade Commission (1977), Preliminary data
from U.S. International Trade Commission concerning production
and sales of synthetic organic chemicals for 1976.
37
-------
SECTION I. REFERENCES (CONT'D)
U.S. Tariff Commission (1968), "Synthetic Organic Chemicals:
United States Production and Sales, 1966." U.S. Tariff
Commission Pub. 248, Government Printing Office,
Washington, B.C.
U.S. Tariff Commission (1969), "Synthetic Organic Chemicals:
United States Production and Sales, 1967." U.S. Tariff
Commission Pub. 295, Government Printing Office,
Washington, D.C.
U.S. Tariff Commission (1970), "Synthetic Organic Chemicals: United
States Production and Sales, 1968." U.S. Tariff Commission
Pub. 327. Government Printing Office,
Washington, D.C.
U.S. Tariff Commission (1971), "Synthetic Organic Chemicals: United
States Production and Sales, 1969." U.S. Tariff Commission
Pub. 412, Government Printing Office.
Washington, D.C.
U.S. Tariff Commission (1972), "Synthetic Organic Chemicals:
United States Production and Sales, 1970." U.S. Tariff
Commission Pub. 479, Government Printing Office,
Washington, D.C.
U.S. Tariff Commission (1974), "Synthetic Organic Chemicals: United
States Production and Sales, 1972." U.S. Tariff Commission Pub. 681
Government Printing Office, Washington, D.C.
38
-------
SECTION II. PHYSICAL AND CHEMICAL PROPERTIES OF VINYLIDENE CHLORIDE,
POLYVINYLIDENE CHLORIDE, 1,1,1-TRICHLOROETHANE AND CHLOROACETYL CHLORIDE
2.1 INTRODUCTION
The vinylidene chloride produced in the United States has
two basic applications: (1) the synthesis of 1-1,1-trichloroethane, an indus-
trial cleaning agent and (2) the formation, in conjunction with other
monomers, of polymers. These polymers are used in the production of
flexible packaging materials, as a coating on food packaging materials
to improve their barrier resistant properties to oxygen, water vapor
and other vapors, as a coating to impart flame resistance to textiles,
in the manufacture of flame-resistant textile fibers, and as a co-
monomer to impart flame resistance to the resulting polymer.
The physical and chemical properties of vinylidene chloride (VDC),
ljl,l-trichloroethane (1,1,1-TCE), and chloroacetyl chloride, a captively used
intermediate are presented in this section. Because polymerization is the most
important chemical reaction vin3'lidene chloride undergoes, the physical
and chemical properties of its polymer, polyvinylidene chloride are
also presented. A bibliography of the pertinent reference sources used
to obtain information for this chapter is listed at the end of this section.
39
-------
2.2 VINYLIDENE CHLORIDE (VDC)
VDC monomer, a di-halogenated, unsaturated hydrocarbon, poly-
merizes with other monomers to form copolymeric materials. Saran is
the generic identifier in the United States for this family of polymers
where the VDC content is greater than 50%.
2.2.1 Physical Properties
VDC, a colorless liquid with a mild sweet odor, is soluble in
most polar and non-polar organic solvents. The monomer forms an azeotrope
with 6% methanol. A detailed listing of the physical properties of
vinylidene chloride is shown in Table 2-1. Although the values given
are for pure vinylidene chloride (1,1-dichloroethylene), they also apply
to the commercial product, which is more than 99.6% pure (PPG 1975), and
always contains an inhibitor to prevent peroxide formation and subsequent
polymerization (see Section 2.2.2).
2.2.2 Chemical Properties and Reactions
In the presence of air or oxygen and at temperatures as low as
40°C, uninhibited vinylidene chloride may form a complex peroxide compound
that is violently explosive. The decomposition products of vinylidene
chloride peroxides are formaldehyde, phosgene, and hydrochloric acid. The
presence of a sharp acid odor thus indicates oxygen exposure and the
possible presence of peroxides. Since the peroxide is a polymerization
initiator, formation of insoluble polymer in stored vinylidene chloride
monomer may also indicate peroxide formation and a potentially hazardous con-
dition. The peroxides are absorbed on the precipitated polymer, and its
separation from monomer by filtration, evaporation, or drying may result
in an explosive composition. If the peroxide content is more than 15
percent, this solid may detonate from a slight mechanical shock or heat.
t
VDC residues containing peroxides can be rendered inactive by
adding water that is at room temperature, but the hazard may return if the
water evaporates. The peroxide can be destroyed by several washes with a
5% by volume solution of methanol in perchloroethylene. Any peroxide present
as a component of precipitated polymer in the monomer can be destroyed by
40
-------
TABLE 2-1. PHYSICAL PROPERTIES OF VINYLIDENE CHLORIDE
Molecular Formula
Structural Formula
CH2=CC12
Molecular Weight
Physical State
Boiling Point @ 760 mm Hg, °C
Melting Point, °C
Specific Gravity, 20°/20°C
Refractive Index, n^ at 20°C
Viscosity at 20°C, cps
Vapor Pressure
(T°C - mm Hg)
Flash Point, °C
(Cleveland Open Cup)
Autoignition Temp. °C
Explosive Limits
(% by volume in air)
Latent Heat of Vaporization,
31.8°C, kcal/mole
Specific Heat, cal/(g)(°C)
Heat of Formation, kcal/mole
Heat of Combustion, kcal/mole
Heat of Polymerization, kcal/mole.
Solubility of H_0 in monomer
at 25°C, wt%
Solubility of monomer in H_0
at 25"C, wt%
Dielectric Constant at 16°C
Beilstein Reference
96.95
Colorless liquid; mild, sweet odor
31.56
- 122.1
1.213
1.4249
0.330
0.0 = 215
20.0 = 495
30.0 = 720
31.8 = 760
- 15
570
7-16
6.257
0.27
- 6 (liquid monomer)
261.93
18
0.25
0.035
4.67
Bl,186
41
-------
mixing with one part perchlorethylene-cnethanol solution and four parts
VDC monomer.
To prevent formation of peroxide in the monomer, inhibitors
are used. The most common is 200 ppm rconomethyl ether of hydro-
quinone (MEHQ). Other inhibitors include alkylamines, phenol, and organic
sulfur derivatives. Inhibited VDC is shipped under a nitrogen blanket
to avoid contact with air and to prevent the formation of peroxides which
can develop very slowly even in the absence of oxygen. (See Section 4.6).
To retard polymerization, uninhibited VDC should be kept away from light
and at low temperatures, below -10°C. Uninhibited VDC can be stored in
mild steel, stainless steel or nickel equipment. Contact with copper,
aluminum and their alloys should be avoided as there is danger of acetylide
or aluminum chloralkyl formation, which are extremely reactive. Inhibited
VDC has indefinite storage life and will not polymerize when kept under a
dry blanket of nitrogen with a maximum of 100 ppm oxygen, in the absence
of water, light and excessive heat.
VDC vapor is flammable at concentrations between 7% and 16% by
volume in air. Vapors of the liquid monomer, once ignited burn strongly
but not violently. Vinylidene chloride and hydrochloric acid react to
produce 1,1,1-trichloroethane (methyl chloroform) the manufacture of which
will be discussed in Section 4.2. The chemical reaction for this process
is:
CH2=CC12 + HC1 » CH3-CC13
There is little information in the literature on the atmospheric
degradation of VDC. Recently, Gay et al. (1976) analyzed the products
of the photo-oxidation of various chlorinated ethylenes in the presence
of nitrogen dioxide with ultraviolet light. Reactivities of the ethylene
compounds studied fell in this decreasing order:
VDC} 1,2-dichloroethylene) trichlororethylene^ ethylene^
vinylchloride^ tetrachloroethylene
42
-------
The products of photo-oxidation of VDC were formic acid, hydrochloric
acid, carbon monoxide, formaldehyde, ozone, phosgene and chloroacetyl
chloride. Chloroacetyl chloride has also been reported as a product from
the ozonolysis of VDC (Hull, et al. 1973).
2.3 POLYVINYLIDENE CHLORIDE
Because of the difficulty of fabricating the homopolymer
of vinylidene chloride, it has not been used commercially. Wessling and
Edwards (1971), give a brief treatment of laboratory polymerization processes
for the homopolymer.
Vinylidene chloride copolymerizes with other monomers to
form a large number of commercially useful copolymers and terpolymers
as shown in Tables 2-2 and 2-3. These polymers contain more than 50%
VDC, and are used primarily to produce films with excellent barrier proper-
ties or to produce .latexes, for coatings on other materials. The commer-
cially important comonomers used with VDC are vinyl chloride, acrylonitrile,
and alkyl acrylates. Many commercial saran polymers contain three or more
components, vinylidene chloride being the major one. Usually one component
is introduced to improve the processability or solubility of the polymer, and
others are added to modify specific end-use properties.
VDC is also copolymerized with other monomers where the amount
of VDC present is less than 50%. In this case, it is used as an adjunct to
improve the fire-retardancy of the major monomer in the polymer. Examples
of this, use are in the production of modacrylic fiber, where VDC is copoly-
merized with acrylonitrile, and as a latex backing for carpets, where the
major polymer is styrene-butadiene.
2.3.1 Physical Properties
Generally, VDC copolymers are odorless, tasteless, non-toxic, and
flame-retardant. They show toughness and abrasion resistance. Oriented
filaments, fibers and films have tensile strengths of between 8,000-60,000
psi, depending on composition and the degree of orientation. Physical
43
-------
TABLE 2-2. COMPOUNDS FORMING COPOLYMERS
WITH VINYLIDENE CHLORIDE8
(EXCLUDING VINYL CHLORIDE)
(Gabbett and Smith, 1964)
Type
Aromatic Compounds
Allyl carbonate derivatives of aromatic hydroxy esters
Diallyl phthalate
Diesters of tetrahydro-endonethylene phthalic acid
9-Methylene fluorene
3-Methylene phthalide
Styrene and derivatives
Heterocyclic Compounds
N-Isopropenyl derivatives of 2-oxazinones and 2-oxa-
zolidinones
N-2-Norcamphanyl acrylamides
Vinylfuran
Vinyl oxazolidinone
Miscellaneous Compounds
Acrylonitrile
Aliphatic epoxides
Alkenyl silanes
Allyl-3,4-epoxy-2-hydroxybutyra te
Allyl esters of dicarboxylic acids
Butadienes
1,1-Dichloro-1,3-butadiene
N-Fluoroalkyl-N-vinyl amides
N-Hydroxymethyl maleimide
Isopropenyl isocyanate
6-Methylene-8-propiolactone
2,4,6-Trially-1,3,5-tricyclohexylbora zine
2,4,6-Trivinyl-1,3,5-tricylohexylbora zine
Unsaturated esters of halo derivates of acetic acid
Unsaturated ketones
Vinyl compounds (general)
Vinyl isocyanate
Vinylidene cyanide
Type
Olefinic Compounds
Chlorotrifluorethylene
Ethylene
Fluoroprene
Isobutylene
Haloolefins (general)
Olefins (general)
Tetrafluoroethylene
3,3,3-Trifluoropropene
Unsaturated Acids & Esters
Alkyl acrylates
Alkyl methacrylates
Allyl acrylate
Diamidophosphoroacrylates
Ethyl fumarate
Methyl 2-chloroacrylate
Sodium sulfopropyl arylate
Trialkyl aconitates
Vinyl isothiocyanate
Vinyl Esters
Butyl vinyl sulfonate
Vinyl acetate
Vinyl 3-alkoxybutyrates
Vinyl esters of car-
boxylic acids (general)
Vinyl Ethers
Dodecyl vinyl ether
Trifluoroethyl vinyl
ether
a - Copolymers containing at least 50% VDC.
44
-------
TABLE 2-3, COMPOUNDS FORMING TERPOLYMERS
WITH VINYLIDENE CHLORIDE3
(Gabbett and Smith. 1964)
Second Monomer
Acrylates or acrylonitrile
Acrylic or methacrylic acid
Acrylonitrile
a-Alky1 acrylates
Alkyl maleates
Allyl chloride
1,3-Butadiene
Butadiene
N-2-Formamidoethylacrylamide
Isobutylene
1-Chloro-l-bromoethylene
Glycidyl methacrylate
Methyl acrylate
Styrene
Vinyl halides
Third Monomer
Isopropenyl acetate
Vinyl or acrylate esters
Butadiene
Methyl methacrylate
a-Methyls tyrene
Vinylidene chloride
5-Vinyl-2-picoline
Vinyl chloride
Vinyl esters
Diallyl fumarate
Chloroprene
Ethyl acrylate
Isobutylene
Methyl methacrylate
a-Methylstyrene
Styrene
Vinyl acetate
Vinyl chloride
Vinyl compounds
Vinyl chloride
Polymerizable substances
Vinylidene bromide
(2-Methacryloyloxyethyl)
diethyl ammonium methyl
sulfate
Trichloroethylene
Vinyl chloride
Vinyl chloride
Acrylic or methacrylic
compounds
Tetrapolymer
Acrylic acid
Acrylonitrile
Methyl methacrylate
Limited to those copolymers containing at least 50% vinylidene chloride.
45
-------
properties of polyvinylidene chloride* are summarized in Table 2-4.
2.3.1.1 Structure
The chemical composition of polyvinylidene chloride homo-
polymer has been confirmed by various techniques including elemental
analysis, x-ray diffraction analysis, infrared, Raman, and NMR
spectroscopy and degradation studies. The polymer chain is made up of
vinylidene chloride monomer units added head to tail.
-CH2-CC12-CH2-CC12-CH2-CC12-
Since the repeat unit is symmetrical, no possibility exists for stereo-
isomerism. The chain structure of PVDC homopolymer is shown in Figure 2-1.
Although the chemical composition of the PVDC homopolymer chain is well-established,
almost nothing is known about its size or size distribution. No direct
measurements of molecular weight have been reported in the literature
(Wessling and Edwards, 1967).
Figure 2-1. Chain Structure of Polyvinylidene Chloride Homopolymer
(Gabbett and Smith, 1964)
r\
Unless stated otherwise, the use of the term polyvinylidene chloride (PVDC)
in this section refers to the copolymerized form of vinylidene chloride and
not to the homopolymer.
46
-------
TABLE 2-4. PROPERTIES OF POLYVINYLIDENE CHLORIDE HOMOPOLYMER
(Dean, 1973; Branciup and Immergut, 1975)
Physical
Specific gravity
Specific volume, cu. in./lb.
Coefficient thermal expansion,
linear x 1CH
Specific heat, cal/g.
Thermal conductivity x ICT"
Heat capacity kJ/kg °K .
Heat distortion temperature, °F
Heat resistance - continuous, °F
Flammability, in/min.
Water absorption, % ASTM D-570
after 24 hours
Glass transition temp. Tg (°K)
Refractive index n^ at 20° C
90OC
Critical surface tension'" ^
(mNnT1) = (dyn cm" )
Mechanical
1.65 - 1.72
16-17
19
0.32
2.2
0.857
150-180
160-200
none
0,8-1.2
255
1.60-1.63
40
Impact strength, Izod ft-lbs.in.
Tensile strength, ASTM D-638 (mPa)
Elongation at break, ASTM D-638
Flexural strength, ASTM D-790 (mPa)
Compressive strength, psi x 10~3
Hardness, ASTM D-785, ASTM D-1706
Electrical
Volume resistivity ASTM D-257 (Ohm.cm)
Dielectric strength, short time, ASTM
D-149 (Vcm~1).10~ to convert to volts/
mil., multiply by 2.54
Dielectric constant, ASTM D-150 at 60 Hz
Dissipation factor, ASTM D-150 at 60 Hz
Fabrication
Bulk factor
Injection molding temp., F
Injection molding, pressure, psi x 10"^
Mold shrinkage, mils/in.
0.3-1.0
High=250
29-43
4.5-5.5
M50-M65
1.0 x 1014 - 1.0 x 1016
160-240
4.5-6.0
0.03-0.045
300-400
10-30
5-15
Variation may occur in these values since the properties of a molded article
depend not only on the plastic used but on many other factors including con-
ditions of forming and design of the molded part itself.
47
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2.3.1.2 Crystallinity
The homopolymer of vinlyidene chloride and copolymers comprised
principally of viny]idene chloride show a strong tendency to crystallize,
have high softening temperatures and relatively sharp melting points.
Copolymers containing more than about 15 mole % acrylate or methacrylate
are amorphous. Substantially more acrylonitrile, (—25 mole %), or vinyl
chloride, (~45 Mole %), is required to destroy crystallinity.
The more common crystalline copolymers show their maximum rates
of crystallization in the range of 80-120°C. In many cases, these have
broad composition distributions containing both polymer unit fractions of
high vinylidene chloride content which crystallize rapidly, and other
polymer units that do not crystallize at all. The copolymers may remain
amorphous for considerable periods of time if quenched to room temperature.
The induction time before the onset of crystallization depends on both the
type and amount of comonomer; the homopolymer crystallizes within minutes at
25°C. Orientation or mechanical working accelerates crystallization and
has a pronounced effect on morphology. Crystallographic data for PVDC
homopolymer is given in Table 2-5.
Because VDC polymers are, in comparison with other polymers,
impermeable to a wide variety of gases and liquids, they exhibit barrier
properties which make them commercially important. Their impermeability is
a consequence of the combination of high density and high crystallinity
in the polymer. An increase in either tends to reduce permeability though
a more subtle factor may be the symmetry of the polymer structure. PVDC
has an unusually low permeability to H00 as is shown in Table 2-6.
Table 2-7 gives the permeability of PVDC to a variety of gases.
Permeability is affected by both kind and amount of comonomer as well as by
crystallinity.
2.3.1.3 Solubility
PVDC does not dissolve in most common solvents at ambient
temperatures. This is due less to its polarity than its high melting
point. It dissolves readily in a wide variety of solvents at temperatures
above 130°C (Wessling, 1970). Various solvents for PVDC are shown in Table 2-8.
48
-------
TABLE 2-5. CRYSTALLOGRAPHIC DATA FOR PVDC HOMOPOLYMER
(Brandup and Immergut, 1975)
-P-
vo
CRYSTAL
System
Mono
ii
ii
SPACE
Group
C2-2
UNIT
A
22.54
6.73
13.69
CELL
B
4.68
ii
4.67
PARAMETERS
C Angles
12.53 B=84.2
12.54 B=123.6
6.296 B=55.2
MONOMERS/
UNIT '
Cell
16
4
4
DENSITYg/CC
Crystal Amorph
1.958
1.957
1.948
1.66
1.7754
Mono = monoclinic
A, B, C = angstroms
Angles a and 6 are 90°. /3 (B) is given in Table.
Monomers/unit cell: no. of base units in cell unit
-------
TABLE 2-6. COMPARISON OF THE PERMEABILITIES OF VARIOUS POLYMERS
TO
WATER VAPOR (
Wessling and Edwards, 1967)
Density, g/ml
Polymer
ethylene
propylene
isobutylene
vinylchloride
amorphous
0.85
0.85
0.915
1.41
vinylidene chloride 1-77
crystalline
1.00
0.94
0.94
1.52
1.96
Permeability21
amorphous
200-220
420
90
300
30
crystalline
10-40
90-115
4-6
aln g/(hr) (100 in. ) at 53 mm Hg pressure differential and 39.5°C for
a film 1 mil thick.
TABLE 2-7. PERMEABILITY COEFFICIENTS FOR PVDC
(Brandup
T(°C)
34
30
30
30
25
30
and Immergut, 1975)
10
PX101
0.31
0.00094
0.0053
0.03
0.5
0.03
( amount of permeant)
Ep kl/mole
70.2
66.5
51.4
46.0
74.4
(film thickness
Permeant
He
N2
°2
co2
H20
P _ _ ___
(rate of transmission) (area) (time) (pressure - drop across the film)
Units of P: cm3 (STP)-cm/cm2-sec-cmHg
Ep: activation energy of permeation
50
-------
TABLE 2-8. SOLVENTS FOR POLYVINYLIDENE CHLORIDE
(Wessling and Edwards, 1967)
Solvents Tm,°Ca
nonpolar
1,3-dibromopropane 126
bromobenzene 129
a-chloronaphthalene 134
2-methylnaphthalene 134
o-dichlorobenzene 135
polar aprotic
hexamethylphosphoramide -7.2
tetramethylene sulfoxide, TMSO 28
N-acetylpiperidine 34
N-methylpyrrolidone 42
N-formylhexamethylenimine 44
trimethylene sulfide 74
N-n-butylpyrrolidone 75
isopropyl sulfoxide . 79
N-formylpiperidine 80
N-acetylpyrrolidine 86
tetrahydrothiophene 87
N,N-dimethylacetamide 87
cyclooctanone 90
cycloheptanone 96
n-butyl sulfoxide 98
Temperature at which a 1% mixture of polymer in solvent
becomes homogeneous.
51
-------
Copolymers with a high enough vinylidene chloride content to be
quite crystalline, behave much like PVDC horaopolymer. They are more soluble,
however, because of their lower melting points. The solubility of amorph-
ous copolymers is much higher. The selection of solvents, in either case,
varies somewhat with the type of comonomer. Solvents that dissolve the
homopolymer also dissolve the copolymers, but at lower temperatures.
Solution properties of PVDC homopolymers have not been studied in de-
tail.
2.3.1.4 Migration of Monomer from Polymer
Since VDC polymer finds many applications in the food industry
as a packaging material, it is of interest to know whether traces of un-
reacted monomer trapped in the polymer will migrate out into the con-
tacted substance. During the past year the Indirect Additives Laboratory
of the Food and Drug Administration has been conducting a study on the
migration of various monomers in plastics into foods. They have develop-
ed measurement methods for analyzing both vinyl chloride and vinylidene
chloride in food simulants (water, heptane and corn oil). The studies
consisted of placing plastic films in contact with food simulants, and
measuring the migration as a function of time and temperature. Pre-
liminary findings indicate that VDC monomer does migrate from the polym-
er (Breder, 1977). Results are to be published in the Journal of the
Association of Official Analytical Chemists in the coming year.
However, Dow researchers have stated that studies of foods
wrapped in plastics made from VDC had showed that none of the chemical
migrated from the wrapping to the food* The tests would have dis-
closed such contamination if the VDC concentration exceeded 10 ppb.
(New York Times, February 23, 1977, Chemical and Engineering News,
February 28, 1977). These reports have been confirmed by Dow spokes-
men (Wintermyer, 1977).
2.3.2 Chemical Reactions
2.3.2.1 Thermal Decomposition
PVDC begins to decompose at about 125°C . In the very early
stages of thermal decomposition (^1%), PVDC discolors and becomes in-
These tests were FDA recognized extraction studies from food wrap
materials in food simulated solvents.
52
-------
soluble. A gradual rise in temperature causes conjugated double bonds
to appear, after which the polymer becomes infusible, the crystal structure
is destroyed, aromatic structures form, and finally, graphitization
occurs (Wessling and Edwards, 1967). Upon incineration PVDC completely
breaks down with no ..intermediate oxychlorinated products formed. (PPG,
1976).
The basic degradation reaction of PVDC is:
1. Formation of a conjugated polyene
+ nHCl
2. Carbonization
•(CH-CCl* sl°W> 2n C + nHCl
n
Heat, ultraviolet and ionizing radiation, alkaline reagents,
and catalytic metals or salts can effect the process. The common
feature of these reactions is that chlorine is removed from the
polymer, either as chloride ion or hydrogen chloride depending on
the medium.
2.3.2.2 Photodegradation
PVDC does not appear to degrade at a measurable rate in the
dark at temperatures below 100°C. When exposed to ultraviolet radia-
tion (uv) or sunlight, it discolors. Hydrogen chloride is eliminated
in the process and crosslinking takes place. An interesting aspect
of a study by Oster et al. (1962) on photodegradation reactions was
that a photoconducting plastic can be produced by the ultraviolet irradia
tion of PVDC film.
Unlike UV, higher energy irradiation (gamma rays) of PVDC
causes chain scission. Copolymers of VDC and VC undergo both
crosslinking and chain scission. The relative amounts of the two
reactions are a function of VDC content in the copolymer (Tsuchida,
et *3i., 1964). A higher proportion of VDC produces more scission
than crosslinking. Crosslinking is increased at elevated temperatures
during irradiation, and decreased in the presence of oxygen. However,
a much larger effect is exerted by the physical form or heat history
53
-------
of the solid copolymer itself. Based on changes in viscosity of
vinylidene chloride/vinyl chloride copolymer material, it has been
shown that molded sheet specimens evince more crosslinking than un-
fabricated molding powder (Harmer and Raab, 1961).
2.3.2.3 Alkaline Decomposition
While the mechanism for alkaline decomposition is not known,
it is clearly an ionic reaction whose final products are carbon and
chloride ion. The reaction is very fast and is effected by strong
bases such as alcoholic KOH, metal alkyls, active metals and others.
The rate is based on surface area since PVDC is not soluble in the
solvents used for alkaline decomposition. Weak bases, such as ammonia
or amines, accelerate the decomposition but do not produce a simple
polyene product. Aqueous solutions have a limited effect on PVDC
because of the relative insolubility in water. However, PVDC can
be decomposed by hot concentrated caustic over a period of time, but
decomposition products do not have a simple polyene structure
(Wessling and Edwards, 1967).
2.3.2.4 Catalytic Decomposition
Various metal salts such as Fed.,, A1C1_, and ZnCl- catalyze
the thermal decomposition of PVDC. This problem is of great practical
importance because Saran polymers, when heated, release hydrogen chloride.
If they are in contact with a metal surface, the metal chloride forms
and catalyzes further decomposition, thereby greatly accelerating the re-
action. As a consequence, attempts to extrude unstablized saran in con-
ventional steel equipment lead to almost explosive decomposition. Very
little is known about the mechanism of the reactions; the major industrial
emphasis has been on preventative measures. Metal parts intended to be
used with saran are fabricated from acid-resistant alloys or nickel.
Nickel salts are much less active as catalysts. In addition, the polym-
ers are usually stabilized with some type of metal-ion scavenger (Wessling
and Edwards, 1967).
54
-------
2.3.2.5 Stabilization of PVDC
Since exposure of polymers to heat, ultraviolet light,
oxygen and metals is unavoidable in most applications, both during
processing and service life, these effects must be minimized by the
addition of stabilizers during compounding to insure a reasonable
service life for the material. An ideal stabilizer system should in-
clude: (1) an acid acceptor which will combine with HC1 but not strip
it from the polymer, (2) an ultraviolet absorber which prevents con-
jugation from occuring and breaks up discoloration due to the conjuga-
tion, (3) an antioxidant to prevent formation of carbonyl groups and
other chloride scavengers, and (4) chelating agents to prevent metal
chloride formation which accelerates PVDC degradation. The stabiliz-
ers are usually used in combinations and frequently produce synergistic
effects (Wessling and Edwards, 1967). Specific examples of the various
stabilizers can be found in the literature (Wessling and Edwards, 1967;
Chevassus and de Broutelles, 1963; Platzer, 1967; Thacker, 1971-1972;
Gross, 1974-1975).
2.4 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)*
Besides the formation of VDC polymers, vinylidene chloride
finds commercial use in the manufacture of 1,1,1-trichloroethane,
(1,1,1-TCE). At the present time, only one manufacturer (PPG Industries)
produces 1,1,1-TCE from vinylidene chloride. The most widespread appli-
cation of 1,1,1-TCE is as a cold solvent used in the cleaning and de-
greasing of metals and other items. In addition, the chemical is used as
a vapor pressure depressant in the aerosol industry and in the formula-
tions of such products as adhesives, cutting oils, and non-flammable
paints.
2.4.1 Physical Properties
1,1,1-TCE is noncorrosive to common metals, is non-flammable,
possesses no flash point or fire point and is one of the least toxic
names l,l,i-trichloroethane and methyl chloroform are used
interchangeably in the literature.
55
-------
chlorinated hydrocarbons. For commercial purposes, methyl chloroform
is stabilized or inhibited to prevent hydrolysis. A summary of physical
properties for 1,1,1-TCE, both inhibited and uninhibited, is presented
in Table 2-9. As is shown by this Table, the properties of the stabliz-
ed material differ little from the unstabilized form.
2.4.2 Grades
Grades of methyl chloroform are manufactured according to their
end-use. The small differences in properties among the various grades
are due to different types or concentrations of inhibitor; the purity of
the methyl chloroform is the same for all grades. The inhibitor may
affect the specific properties and uses of the solvent. These compounds
are considered proprietary by the manufacturers. Typical inhibitors
which have been reported are discussed in Section 2.4.3.3.
Table 2-10 shows specifications and typical analyses for two
grades of methyl chloroform, one used for cold cleaning, aerosol formula-
tions and vapor degreasing, and the other grade, which contains less in-
hibitors used for adhesives, and film processing and various syntheses.
2.4.3 Chemical Reactions
2.4.3.1 Thermal Decomposition
Different decomposition products result from heating methyl
chloroform under varying conditions.
Heated at 75-160°C, at elevated pressure and in the pre-
sence of sulfuric acid or metal chlorides, and depending on the quantity
of water present 1,1,1-TCE forms acetyl chloride, acetic acid or
acetic anhydride. At temperatures up to 370°C, 1,1,1-TCE is one of the
more stable chlorinated aliphatic solvents with respect to phosgene
formation. However, at temperatures above 700°C or when exposed to
open flames or electrical elements, uninhibited 1,1,1-TCE is subject
to atmospheric oxidation, yielding phosgene, carbon monoxide, carbon
dioxide^hydrogen chloride and water (The Franklin Institute, 1975).
56
-------
TABLE 2-9. PHYSICAL PROPERTIES OF 1.1,1-TRICHCLOBOETHANE
UNINHIBITED AND INHIBITED GRADES*
(PPG Industries, 1968)
Physical Properties
Chemical Formula
Physical State
Color
Odor
Boiling Range
Melting Point
Specific Gravity (?25/250C
Refractive Index ,20
nd
Explosive Limits
Autoignition Temperature
Deliquescence
Density at 25°C
Dielectric Constant
Hygroscopicity
Light Sensitivity
Flash Point
Tolerance
Specific Heat
Vapor Density (Air =1)
Vapor Pressure @30°C
Viscosity @25°C
Surface Tension, 20 C, dyn/cm.
Solubility of 1,1,1 TCE in water
Solubility of Water in 1,1,1 TCE
Solubility (room temp.) in:
alcohol
ether
Uninhibited Grade
CH3CC13
liquid
clear, water white
mild, chloroform-like
74.1°C (165.2°F )
-30.41°C
1.336
1.4379
flammable at elevated
temperatures and pressures
500°C(932°F)
Inhibited Grade
,(34.9UC)
no
1.332
5o007(
no
no
none
350 ppm in air
0.25 cal /gm /°C
4.55
144 mg Hg
0.59 Centistokes
25.56
0.44 g/lOOg .
Oo05 g/100 g
soluble in all proportions
liquid
clear, water white
mild, chloroform-like
70-88°C (158-190°F)
1.288-1,321
no
1.284-1.317
no
no
none
0.25 cal /gm /°C
4.55
144 mg Hg
0.61 Centistokes
* Blank spaces indicate lack of available data for that property*
57
-------
TABLE 2-10. SPECIFICATIONS AND TYPICAL ANALYSES FOR
TWO GRADES OF 1.1.1-TRICHLOROETHANE
(METHYL CHLOROFORM) (PPG, 1968)
INHIBITED METHYL CHLOROFORM LOW-STABILIZED METHYL CHLOROFORM
(VAPOR DECREASING & AEROSOL GRADE) (SPECIAL ADHESIVES GRADE)
PROPERTY SPECIFICATION TYPICAL SPECIFICATION
TYPICAL
Appearance _ Clear, water white Passes Clear, free of Passes
suspended matter
Color, APHA 15 maximum
15
Specific Gravity, 25°/25°C 1.300-1.320 _ 1.320-1.336 1.333
Distillation Range (100%), °C 72.0-88.0 — 73.0-83.3 -- 70-79 74.1-75.5
Acidity, as HC1,% 0.0010 maximum 0.0002 0.001 maximum - 0.0003
Aluminum Corrosion (Reflux) no effect on solvent Passes
or aluminum
Water Content, PPM - 100 maximum 65 100 — 50
Non-Volatile, % by wt _ 0.0010 maximum 0.0002 0.001 0.0005
Methyl Chloroform, 70 (Minimum) . 99.0 99 6
-------
o 2
3CH3CC13 + 502 700 C v 5HC1 + 2C02 -f 2CO + 2COC12 t H
2.4.3.2 Corrosion
When dry, uninhibited methyl chloroform has little effect
on common construction materials. However, in the presence of any
traces of moisture, corrosion occurs due to the formation of hydrogen
chloride. The inhibited or stabilized grade does not corrode any
common metal used commercially, including aluminum, brass, cooper,
iron, monel, steel, tin and zinc at temperatures up to 79.4°C (175°F)
(Manufacturing Chemists' Association, 1976).
The low stabilized grade, however, may corrode common commer-
cial metals, with the exception of stainless steel.
2.4.3.3 Stabilization
Although 1,1,1-TCE is substantially more stable to oxidation
than other chlorinated hydrocarbons, significant amounts (3-8%) of stab-
ilizing substances are always added to prevent thermal decomposition
or hydrolysis. Representative stabilizers are reported to be nitro-
methane, N-methylpyrrole, 1,4-dioxane, butylene oxide and 1,3-dioxolane
(Lowenheim and Moran, 1975).
2.4.3.4 Reactions with Alkaline Materials
Methyl chloroform reacts with a solution of sodium hydroxide
to yield vinylidene chloride. This reaction is the basis for commer-
cial production of VDC. In the presence of strong alkalies such as
caustic soda, flammable or explosive products may be formed. (PPG, 1968)
2.4.3.5 Other Reactions
Methyl chloroform forms an azeotrope with methanol (21.7%)
boiling at 56 C. In the presence of chlorine and sunlight, 1,1,1,2-
59
-------
tetrachloroethane and small quantities of penta- and hexachloroethane
are formed. Reaction with anhydrous hydrogen fluoride at 144°C in the
absence of a catalyst results in the formation of 1,1-dichloro-l-
fluoroethane and l-chloro-l,l-difluoroethane.
2.5 CHLOROACETYL CHLORIDE
Chloroacetyl chloride is of only marginal interest to the
present study. It is produced by Dow from vinylidene chloride. Dow
produces about 5 million pounds per year for captive use as an inter-
mediate for other syntheses.
Chloroacetyl chloride has also been used in the production
of chloroacetophenone, the principal ingredient of the riot control
gas MACE.
2.5.1 Physical Properties
Chloroacetyl chloride is a non-flammable liquid, highly
corrosive to metal and skin. A summary of its physical properties is
presented in Table 2-11.
2.5.2 Chemical Reactions
There are two chemical reactions of Chloroacetyl chloride of
interest to this study. Its decomposition in water liberates the mono-
chloracetic acid and HC1, which accounts for its lachrymatory effect
on the eyes and its corrosiveness to metals.
ClCHJDOCl + H_0 ^ HC1 + C1CH2COOH
In the presence of benzene and an aluminum chloride catalyst, it can
be used to prepare omega-chloroacetophenone, the principal ingredient
in tear gas or MACE.
r*lpu pnPT -4- p u A1 r*l r1 IT PHPTJ PI u. UPI
^•x\jrirtVj^\jx i^ \^.-n.f A^ui.A w^-ncwUoiiALfJ. ~ riwj.
£. DO J \ o .3 2
7
60
-------
TABLE 2-11. PHYSICAL PROPERTIES OF CHLOROACETYL CHLORIDE
Formula:
Molecular weight:
Physical State:
Color:
Odor:
Boiling Point
@760 mm Hg.
Freezing Point
Specific Gravity
@ 0°C
Refractive Index
nD20
20
Density, d,
Beilstein Ref.
Solubility:
in water
in alcohol
in acetone
in ether
C1CH2COC1
112.95
Liquid
Clear, water-white
Very pungent
107°C
-21.77°C
1.495
1.4541
1.4202
2,199
Decomposes
Decomposes
Soluble
Soluble in all proportion
61
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SECTION II. REFERENCES
Brandup, J. and E.H. Inmergut, editors (1975), Polymer Handbook, 2nd Edition
Interscience, New York.
Breder, C.E. (1977), Indirect Food Additives Laboratory, Food and
Drug Administration, Personal Communication, February 25.
Chevassus, F. and R. deBroutelles (1963), The Stabilization of Poly-
vinyl Chloride, St. Martin's Press, New York.
Dean, J.A., editor (1973), Lange's Handbook of Chemistry, llth Edition,
McGraw-Hill, New York.
The Franklin Institute (1975), "Preliminary Study of Selected Environ-
mental Contaminants: Optical Brighteners, Methyl Chloroform,
Trichloroethylene, Tetrachloroethylene, and Ion Exchange Resins,"
National Technical Information Service, PB-234 910.
Gabbett, J.F. and W.M. Smith (1964), "Copolymerization Employing Vinyl
Chloride or Vinylidene Chloride as Principal Components,"
High Polymers, John Wiley and Sons, New York, 18, 611-13.
Gay, B.W., P.L. Hanst, J.J. Bafalini, and R.C. Noonan (1976),
"Atmospheric Oxidation of Chlorinated Ethylenes," Environ. Sci.
Tech., 10(1), 58-67.
Gross, S., editor 1974-1975, "Chemicals and Additives Charts," Modern
Plastics Encyclopedia, McGraw-Hill, Inc., New York.
Harmer, D.E. and J.A. Raab (1961), "Radiation-Induced Crosslinking and
Degradation of Vinyl Chloride—Vinylidene Chloride Copolymers,"
J. Polym. Sci., 55_, 821-26.
Hull, L.A., I.C. Hisatsume, and J. Heicklen (1973), "The Reaction of
00 with CC10CH0," Can. J. Chem., 51, 1504-10.
J 2. L —•
Lowenheim, F.A. and M.K. Moran, editors (1975), Faith, Keyes, and
Clarke's Industrial Chemicals, 4th Edition, Wiley-Interscience,
Inc., New York.
Manufacturing Chemists' Association (1976), "Chemical Safety Data
Sheet, SD-90, Properties and Essential Information for Safe
Handling and Use of 1,1,1-Trichloroethane," Washington, D.C.
Oster, G., G.K. Oster, and M. Kryszewski (1962), "Modification of
Spectral and Semiconducting Polyvinylidene Chloride by Ultra-
violet Light of Specific Wavelengths," J. Polym. Sci., 57,
937*47.
62
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SECTION II. REFERENCES (CONT'D)
Platzer, N.A.J. (1967), "Stabilization of Polymers and Stabilizer
Processes," Symposium sponsored by Division of Industrial and
Engineering Chemistry, American Chemical Society, April 11-13.
PPG Industries, Inc. (1968), "Tri-Ethane," Pittsburgh.
PPG Industries, Inc. (1975), "Vinylidene Chloride: Handling/Properties/
Reactivity Ratios," Pittsburgh.
PPG Industries, Inc. (1976), Personal Communication, September 23.
Thacker, G.A. (1971-72), "Antioxidants," Modern Plastics Encyclopedia,
210-12.
Tsuchida, E., C. Shih, I. Shinohara, and S. Kambora (1964), "Synthesis
of a Polymer Chain Having Conjugated Bonds by Dehydrohalogenation
of Polyhalogen-Containing Polymers," J. Polym. Sci., Part A, 2^(7),
3347-54.
Wessling, R.A. (1970), "Solubility of Poly(Vinylidene Chloride),"
J. Appl. Polym. Sci., 14(6), 1531-45.
Wessling, R.A. and F.G. Edwards (1967), "Poly(Vinylidene Chloride),"
Kirk-Othmer's Encyclopedia of Chemical Technology, 2nd Edition
Interscience, New York, 21, 275-303.
Wessling, R.A. and F.G. Edwards (1971), "Vinylidene Chloride Polymers,"
Encyclopedia of Polymer Science and Technology, McGraw-Hill, 14,
540-79.
Wintermyer, R. (1977), Dow Chemical Co., Personal Communication,
March 3.
63
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SECTION III. MANUFACTURING PROCESS STUDY
3.1 PRESENT STATUS OF THE INDUSTRY
Vinylidene chloride (VDC) is one of a number of chemicals
obtained by the chlorination of ethylene or ethane. VDC, like vinyl
chloride, contains a double bond that enables it to be polymerized
into a long chain compound.
Polymers of pure vinylidene chloride form a crystalline
structure that have found little if any commercial application. When
copolymerized with other double bond containing monomers such as vinyl
chloride, butadiene, styrene, or acrylonitrile, VDC forms polymeric
compounds that are used as a barrier coating on paper and other
plastic film^ to produce a tough, flexible film; as a textile fiber
with flame retardant properties and resistance to many chemicals; and
as a flame retardant elastomer.
The copolymers of vinylidene chloride have not found the
large market enjoyed by vinyl chloride, styrene, acrylonitrile-
butadiene-styrene (ABS), or polyethylene because, on a cost-performance
64
-------
basis they are more expensive, or they do not possess the physical pro-
perties of the competing polymers.
At present, two companies manufacture vinylidene chloride
monomer: Dow Chemical Company and PPG Industries, Inc. Over the
years one other company has manufactured VDC, but, generally for
economic reasons, ceased production. Vulcan Materials Company pro-
duced VDC from late 1970 to January 1974.
Dow Chemical Company makes VDC monomer chiefly for captive
use. A portion of its production (industry estimates about 15 to 20%),
enters the merchant market. PPG Industries, Inc. manufactures VDC
monomer chiefly as an intermediate for the synthesis of 1,1,1-trichloro-
ethane (1,1,1-TCE) or methyl chloroform. It is estimated that 80%
of PPG's present production is used in the synthesis of 1,1,1-TCE,
the balance enters the VDC merchant market.
Substantially all the VDC sold in the merchant market is
used by approximately 12 companies to manufacture a variety of co-
polymers.
PPG's initial interest in producing vinylidene chloride was
developed from its desire to produce 1,1,1-trichloroethane by direct
hydrochlorination of vinylidene chloride, using the process indicated
by equations (la), (Ib) and (Ic). It has been reported within the
past year that PPG is expanding its production of 1,1,1-trichloroethane.
However, it has been stated that the plant expansion will be based
on the use of a new process that will not require the intermediate
formation of vinylidene chloride.
Dow's probable interest in both 1,1,1-trichloroethane and
vinylidene chloride production developed from its major position as
a producer of vinyl chloride and other chlorinated hydrocarbons.
Vinylidene chloride became a cost-effective addition to the product
mix using the route suggested by equations (2a), (2b), and (2c).
65
-------
(la) CH0C1-CH0C1 + C10 —> CH Cl - CHC1 + HC1
I.I,2-Trichloroethane
(Ib) CH Cl - CHC12 + NaOH > CH2 = CC12 + NaCl +
Vinylidene Chloride
(Ic) CH0 = CC10 + HC1 > CH., - CC1.
1,1,1-Trichloroethane
Art \S\SJ-n I li^JL. ' Ollrt O»-.-L A
- j -L j J.— J
(2a) CH3 - CH3 + 3C12 ^ CH2 = CC12 + 4 HC1
(2b) CH0 = CH0 + 2C19 > CH0 = CC10 + 4 HC1
4- Z / Z CH2C1 - CH2C1
Dow has the process flexibility to produce vinylidene chloride by
using 1,1,2-trichloroethane as the raw material, or as a co-product
of ethane or ethylene chlorination. However, current information
indicates that Dow uses 1,1,'2-TCE as the raw material, as well as
recovering VDC as a co-product of ethylene chloride manufacture. The
amount of vinylidene chloride produced from either of these processes
depends on the market demands for the various chlorinated products
of ethane or ethylene.
3.2 MANUFACTURING SITES
The two companies which are active producers of vinylidene
chloride monomer have a total of three plant sites, all located in
the south and southwest part of the United States. In all cases, they
form an integral part of a petro-chemical complex in which a variety
of chlorinated hydrocarbons are co-produced.
The VDC production sites and estimated capacities are shown
in Table 3-1.
TABLE 3-1. PRODUCTION SITES AND CAPACITIES FOR VDC, 1976
(PPG Industries, Dow Chemical Co., 1976, 1977)
Company Plant Site Estimated
Capacity 10°lbs/yr.
PPG Industries, Inc.* Lake Charles, La. 170 to 180
Dow Chemical Co.** Plaquemine, La. \ 95 to 100
Freeport, Texas
*By 1978, new process facilities to manufacture, 1,1,1-TCE should reduce
the VDC production level to about 75 million Ibs.
**A projected capacity expansion is under consideration. Currently the
Texas plant has the larger production.
66
-------
The output of a given chlorinated ethane (or ethylene)
derivative from a typical plant complex can be easily changed by
adjustment of overall operating conditions. Hence, potential capacity
available for the production of VDC monomer is difficult to assess,
and fluctuates with market demands. The capacities in Table 3-1
are based on the best available information.
3.3 MANUFACTURING PROCESSES
The chlorination. of ethane and ethylene produces a broad
spectrum of chlorinated products including ethyl chloride, ethylene
dichloride, vinyl chloride, vinylidene chloride, and trichloroethanes.
The patent literature describes many processes for the chlorination of
these materials under various process conditions that demonstrate the
variability of yields of co-produced chlorinated C. hydrocarbons.
Typical of these is one described in a British patent (Dow,
1955) issued to Dow Chemical in 1955 in which ethane or mixtures of
ethane and ethylene are reacted in a two step process to produce in
the first stage vinylidene chloride (32% yield); 1,2-dichloroethane
(30% yield) and trichloroethylene (7.170 yield) with a recovery of
8.5% trichloroethane and 15.2% vinyl chloride from the second stage.
A modification of this process claimed a yield of vinylidene chloride
of 657, (Crauland, 1954).
Because of the diversity of products obtained by the chlorina-
tion of ethane and ethylene, the specific process used will vary depend-
ing on the technology used by the producers. Both Dow and PPG report
that the specific process used to produce vinylidene chloride from
one of the products of the more general chlorination processes is the
dehydrochlorination of 1,1,2-trichloroethane. The reaction is:
CH2C1-CHC12 -^555* CH2=CC12 + Nad
1,1,2-trichloroethane Vinylidene Sodium
Chloride Chloride
It is believed that, in addition to the direct process
shown above, one or both companies obtain a portion of their vinylidene
67
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chloride as a "by-product" of the more general chlorinabion of
ethane or ethylene.
Figure 3-1 is a flow diagram of the direct process for pro-
ducing vinylidene chloride starting with 1,1,2-trichloroethane. Sodium
hydroxide solution is mixed with 1,1,2-TCE in a reactor at elevated
temperature and pressure. The reactants flow to a dehydration still
where the chlorinated hydrocarbons are separated by distillation.
The largely aqueous bottoms flow to a stripper where residual vinyl-
idene chloride is removed and flows to the dehydration column. The
stripped bottoms, consisting of a solution of sodium chloride in
water are recycled to the chlor-alkali plant. The vinylidene chloride
from the distillation column is condensed and flows to storage. The
bottoms,consisting of high boiling hydrocarbons, are incinerated.
Emissions are controlled by venting all equipment to a
common vent header. This is connected to a refrigerated condenser
that removes the bulk of the gaseous vinylidene chloride by conden-
sation. The condensate flows back to the dehydration still. VDC-
contaminated noncondensables are vented to the atmosphere or in-
cinerated. It is reported that the emission losses are of the order
of 0.2 to 0.3 Ibs of VDC per 100 Ibs of production.
3.4 DEVELOPMENT OF NEW TECHNOLOGY
The chemistry for the production of vinylidene chloride is
well established. The process used to produce vinylidene chloride is
a function of the market demands for both VDC and various chlorinated
hydrocarbons, and the desire to maximize the economic return for the
plant complex.
The two companies presently supplying the market have adequate
capacity and process flexibility to satisfy the present as well as the
probable future demands for VDC. Thus, there is no incentive to change
the current technology, as exemplified by the processes described.
68
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VENT TO ATMOSPHERE OR INCINERATOR
vo
VENT SYSTEM
. i . MANUAL CONTROL
\f.—f TO REMOVE
/1\ NONCONDENSABLES
FROM SYSTEM
BOTTOMS TO »
INCINERATOR /
AQUEOUS RESIDUE (NaCl Solution)
7 TO CHLOR-ALKALI PLANT
Figure 3-1. VDC Manufacture Via the 1,1,2-Trichloroethane Route
-------
3.5 PRODUCTION MARKETS
Based on the present evaluation of the industry, it is
estimated that production of VDC monomer in 1976 will have reached
270 million pounds. About 135 million pounds was polymerized with about
5 million pounds used as a chemical intermediate, and the balance of
130 million pounds consumed captively to produce 1,1,1-TCE.
Demand for VDC for polymerization has grown at an estimated
rate of five percent per year for the past five or six years. Its
future growth is expected to continue at about the same level, gener-
ally following the economy of the country.
From 1963 to 1973, the demand for 1,1,1-trichloroethane
grew at an average rate of 9.5 percent per year due to a shift of
demand from more polluting solvents. From 1973 through 1976, the
overall growth rate drooped to an average of 2.5 percent per year.
The reduction in the rate of growth for 1,1,1-TCE is attributed to
the slow down in the U.S. economy which decreased the demand for
appliances, machines and housing, as well as some saturation of the
market for this "nonrpolluting" solvent. These industries normally
consume large quantities of metal products that require solvent
degreasing prior to coating.
i
Since PPG built their plant to produce 1,1,1-TCE, there
have been no new installations of plants using VDC. The bulk of
VDC produced by PPG is used captively for the synthesis of 1,1,1-TCE.
The quantity produced has been a function of PPG's sales of 1,1,1-TCE.
Based on industry reports, we project a significant reduction in the
VDC produced in the U.S. when PPG puts its new 1,1,1-TCE plant in
operation in 1978, using new technology that does not require VDC
(see Section 4.2.3).
3.6 TRANSPORTATION AND HANDLING OF VINYLIDENE CHLORIDE
VDC monomer is a volatile liquid that will polymerize in
the presence of light, water, air or an oxidizing agent. In the
presence of air or 02 it forms an unstable, explosive peroxide.
70
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Since VDC vapor is heavier than air, it may travel a considerable dis-
tance along the ground to a source of ignition and flash back (National
Fire Protection Association, 1973). Under certain conditions, it
may present a fire or explosion hazard.
VDC is usually stored or shipped with inhibitors such as mono-
methyl ether of hydroquinone (MEHQ) to prevent polymerization.
In the presence of oxygen, peroxide formation and polymerization ,
will occur in uninhibited VDC. Fire presents an additional problem
in that toxic hydrogen chloride gas will be evolved. Preventive mea-
sures must therefore be taken handling and transporting VDC monomer.
These have been established by regulatory and voluntary agencies,
and by the vinylidene chloride producers. They are described in
the following sections.
3.6.1 Mandatory Regulations for Vinylidene Chloride
Vinylidene chloride is regulated by the Department of
Transportation, the Coast Guard and the International Air Transport
Association. These regulations are dynamic and regularly modified.
A government representative reports that recent revisions of the
Hazardous Materials Regulations have resulted in some Coast Guard
regulations being incorporated into those of the Department of
Transportation (DOT) (Smith, 1976). The International Air Trans-
port Association regulates international air shipments of hazardous
materials and those regulations are separate from the DOT. The most
current edition of the regulations should be consulted for specific
details in any one case.
3.6.1.1 Department of Transportation
The Department of Transportation (DOT) regulates inter-
state shipment by common carrier, truck, rail, or air. Its rules
are published in the Code of Federal Regulations and updated
in the Federal Register. They indicate the proper shipping
71
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container, shipping documents, and the form and content of labels
and placards required. On Janaury 3, 1975, Congress established
the Transportation Safety Act of 1974 to improve the regulatory and
enforcement authority of the Secretary of Transportation. By this
act, it is hoped DOT will be able to assess adequately the risks in-
herent in the transportation of hazardous materials such as VDC in
commerce. The most recent update to DOT shipping regulations was
published in the Federal Register on September 27, 1976 (Department
of Transportation, 1976).
A summation of the transportation and shipping regulations
for vinylidene chloride is shown in Table 3-2. Responsibility for
insuring that these standards are met rests with the manufacturer
and the shipper.
3.6.1.2 Coast Guard
The Coast Guard classifies vinylidene chloride as a Grade
A flammable liquid which must be shipped inhibited. Currently, the
Coast Guard uses DOT regulations for VDC container specifications as
shown in Table 3-2. Where the container is itself a vessel such as
a ship or barge, it is regulated under Title 46 - Shipping, of the
Code of Federal Regulations (1975). New regulations for tank barge
requirements are in preparation, but a Coast Guard representative
(Walker, 1976) states that present barge requirements are as follows
(1) A double skinned type 2 tank barge is to be
used under conditions of ambient temperature
and atmospheric pressure.
(2) Independent gravity tanks
(3) Pressure vacuum valves
(4) Type 2 piping class (normal barge requirements)
(5) Class P~ controls*
*Class P_ controls require:
1) one (1) manually operated stop-off valve
2) one (1) excess flow valve
3) one (1) remote-operated, quick closing, shut-off valve at each
cargo base connection when in use
4) no tank penetration shall be less than 1'" in diameter
72
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TABLE 3-2. RULES AND REGULATIONS FOR TRANSPORTING VINYLIDENE CHLORIDE
(Department of Transportation, 1976)
Proper Shipping Name: Vinylidene Chloride (inhibited)*
Hazard Class: Flammable Liquid
173.115(a,d): Defines a flammable liquid as any liquid which has a
flash point below 100°F (37.8°C). A flash point
being the minimum temperature at which a liquid gives
off vapor in sufficient concentration to form an
ignitable mixture with air near the surface of the liquid.
Labeling Requirements
172.519 (a-g): Regulations concerning the construction of hazard
placards.
172.542 (a,b): Specific regulations for "flammable liquid" placard.
Packaging Requirements
173.118 (a)(1): Regulates the shipment of small quantities. The liquid
must be packed in metal containers not over 1 quart
capacity each, packed in strong outside containers.
173.119 (a) (1.-25)' This section gives packaging regulations for large quanti-
ties of VDC. It gives specifications for packages which con-
tain 5 gallons up to specifications for tank cars.
Maximum Net Quantity in One Package
Passenger-carrying
aircraft or railcar: ^u
Cargo Only Aircraft: 10 gallons
Cargo Vessel: No quantity specified but must
be stored under deck away from heat
according to 176.63(d).
Passenger Vessel: 1 quart (is regulated by Section 173.118(a)(1)).
*
VDC is always shipped inhibited. No specifications for the uninhibited
material.
73
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(6) Environmental control: nitrogen padding
(7) Forced venting in cargo handling space
(8) Adequate fire protection
(9) No aluminum, copper or their alloys for pipes,
fittings, valves, or materials which come in
contact with VDC.
(10) Class I electrical hazard group
Title 46 also contains provisions for the inspection and
certification of unmanned tank barges and tank vessels (Code of
Federal Regulations, 1975).
3.6.1.3 International Air Transport Association
The International Air Transport Association (LATA) publishes
a detailed handbook of regulations for the international air shipment
of hazardous materials. Sax (1968) states that under IATA rules
uninhibited VDC is not acceptable for either passenger or cargo
carriers. Inhibited VDC is classed as a flammable liquid, and
given a red label. Passenger aircraft may carry one liter of chemi-
cal while cargo aircraft is allowed 40 liters of VDC. A comparison
with DOT regulations shows that the IATA allows the same amount of
VDC on board cargo aircraft as the Department of Transportation.
3.6.2 Voluntary Regulations for Vinylidene Chloride
3.6.2.1 American Conference of Governmental Industrial Hygienists
(ACGIH)
The ACGIH issues recommendations for acceptable levels of
chemicals in the work environment. Based on experiments by Prendergast
et al. (1967) and Gage (1970), the American Conference of Governmental
Industrial Hygienists (1971) has set the threshold limit value for air-
borne concentrations of vinylidene chloride at 10 ppm. The threshold
limit value as defined by the Manufacturing Chemists' Association
(1972) "represents conditions under which it is believed that nearly
all workers may be repeatedly exposed, day after day, without adverse
affect."
74
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3.6.2.2 National Fire Protection Association (NFPA)
The NFPA's "Committee on Fire Hazards of Materials 704M"
(National Fire Protection Association, 1973) has developed a numerical
rating system for identification of hazardous materials with respect
to fire hazards. The system allows ratings of hazards on a scale of
zero (non-hazardous) to four (extremely hazardous) in the categories
of health, fire and reactivity. Table 3-3 presents these hazard
ratings for VDC.
The NFPA has also developed a classification system of
hazardous locations and the appropriate wiring and electrical equip-
ment to be used for that location. Under the National Electrical
Code, locations are designated according to classes, divisions and
atmospheres. Standards for handling VDC in conjunction with elect-
rical equipment are discussed under the Article 500, Class 1, Division
2 location, which is defined as a location:
(1) in which volatile flammable liquids or flammable
gases are handled, processed, or used, but in
which the hazardous liquids, vapors, or gases
will normally be confined within closed con-
tainers or closed systems from which they can
escape only in case of accidental rupture or
breakdown of such containers or systems, or
in case of abnormal operation of equipment;
(2) in which hazardous concentrations of gases or
vapors are normally prevented by positive
mechanical ventilation, but which might be-
come hazardous through failure or abnormal
operation of the ventilating equipment; or
(3) that is adjacent to a Class I, Division 1 lo-
cation, and to which hazardous concentrations
of gases or vapors might occasionally be communi-
cated unless such communication is prevented by
adequate positive-pressure ventilation from a
source of clean air, and effective safeguards
against ventilation failure are provided.
To determine the relative hazards of flammable chemicals
in relation to their volatility, the NFPA also assigns chemicals by
atmosphere groups. Atmospheres are determined by a comparison of the
chemical to a representative chemical for each group. At the present
• 75
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TABLE 3-3. NATIONAL FIRE PROTECTION ASSOCIATION HAZARD RATINGS
FOR VINYLIDENE CHLORIDE UNDER FIRE CONDITIONS
(National Fire Protection Association, 1975)
HAZARD
HEALTH HAZARD
Type of Possible Injury
RATING
DESCRIPTION
Materials hazardous to health, but
areas may be entered freely with
self-contained breathing apparatus.
Highly toxic HC1 gas is evolved
during thermal degradation.
(See Section 3.6)
FLAMMABILITY
Susceptibility of
Materials to Burning
Very flammable gases, very volatile
flammable liquids, and materials
that in the form of dusts or mists
readily form explosive mixtures when
dispersed in air. Shut off flow of
gas or liquid and keep cooling water
streams on exposed tanks or containers.
REACTIVITY
Susceptibility
Materials which in themselves are
normally unstable and readily undergo
violent chemical change but do not
detonate. Includes materials which
can undergo chemical change with
rapid release of energy at normal
temperatures and pressures or which
can undergo violent chemical change
at elevated temperatures and pressures.
Also includes those materials which may
react violently with water or which
may form potentially explosive mix-
tures with water. In advanced or massive
fires, fire fighting should be done
from a safe distance or from a pro-
tected location.
76
-------
time 300 new chemicals are being added to the Group Atmosphere list,
for which the physical testing is being done by the National Academy
of Science. The physical parameters used are the flash point, auto-
ignition point and the vapor density. VDC is tentatively classified
as a Group D Atmosphere, in which gasoline is the representative
chemical (Beneditti, 1977).
3.6.2.3 Other Regulatory Agencies
An examination of rules administered by the Interstate
Commerce Commission revealed no shipping regulations for vinylidene
chloride.
While the Occupational Safety and Health Administration
(OSHA) does not directly regulate vinylidene chloride, OSHA current-
ly advises that the threshold limit value of 10 ppm set by the Ameri-
can Conference of Governmental Industrial Hygienists should be follow-
ed (Crenshew, 1976).
3.6.3 Handling Procedures and Hazards
Intelligent handling of VDC requires proper ventila-
tion and the elimination of ignition sources. Two of these pre-
cautionary measures as outlined by PPG (1975) are as follows:
Containers should not be left unattended
and open, giving off vapors. Nozzles for
steaming, hoses and purging-equipment must
be properly grounded to reduce the possibility
of an arc from an accumulated charge of static
electricity.
Special procedures have been developed for workmen handling
vinylidene chloride monomer as inhibited liquid VDC can be irritating
to the skin and eyes after a few minutes contact. Shelton, et al.
(1971) believes this irritation is caused by the volatile VDC evapor-
ating, thereby leaving the inhibitor to accumulate and cause local
skin irritations or burns. It is recommended, therefore that pro-
tective eye gear and clothing be worn to prevent chemical contact and
that once contaminated, clothing be immediately removed. Wearing
apparel splashed by VDC should be washed thoroughly before reuse,
77
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especially shoes, which should also be aerated. Personnel should
bathe thoroughly to remove any monomer that may have penetrated the
skin.
As noted earlier in this section, vinylidene chloride is
highly volatile and its vapor is heavier than air. PPG (1975) con-
cludes that "since the VDC odor threshold lies between 500 and 1000
ppm, the odor is not an adequate warning to prevent overexposure.
Persons working around open containers of VDC should stand upwind of
vapors or get the cross wind." Because overexposure to vapor for
even a few minutes can lead to anesthesia and unconsciousness, pro-
per respiratory equipment is required especially when concentrations
of VDC cannot be kept under the 10 ppm threshold limit value (see
Section 3.6.2). Shelton, et al. (1971) states that the high volat-
ility of vinylidene chloride will readily produce excessive vapor
concentrations from a spill or leak. In such situations and where
an oxygen deficiency might exist, an air-supplied mask or self-
contained breathing apparatus should be used. Persons responsible
for cleaning up the spill or diking the leak should wear spark-proof
shoes and use spark-proof tools.
Medical attention is required for all cases of over-
exposure and for persons contaminated by or accidentally swallowing
VDC.
In addition to clothing protection for workmen, transport-
ing and unloading VDC cargo requires precautionary techniques. Specific
instructions are provided by the manufacturer. In general it is most
important to prevent ignition. Static discharge is accomplished by
grounding arrangements. All wiring and electrical equipment should
be explosion-proof and in accordance with the National Electric
Code (National Fire Protection Association, 1975). Additional in-
structions for the general handling of flammable liquids, such as
VDC and for sampling VDC in tank cars and tank truck shipments
78
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are supplied by the Manufacturing Chemists' Association, Inc. (1963,
1975).
3.6.4 Transportation Methods
Vinylidene chloride can be shipped in drums, tank wagons,
rail tank cars, or barge. Regardless of vessel, it is shipped under
a nitrogen blanket at atmospheric pressure. PPG Industries (1975)
states that "nitrogen used in vinylidene chloride service should
have a maximum oxygen content of 100 ppm." In all cases, the tank
wagons or rail tank cars are used solely for the transportation of
VDC. A typical tank car capacity as described by PPG contains 11,000
gallons or 111,000 pounds of material. Unloading of the tank trucks
or cars is done following instructions supplied by the manufacturer;
Figure 3-2 shows a typical tank car unloading station for vinylidene
chloride. When emptied, the tank cars are normally returned direct-
ly to the monomer manufacturer. Because they are in "dedicated ser-
vice" the tank wagons/tank cars are not washed nor vented to the
atmosphere.
Drum containers are available in 5 to 55 gallon sizes and
are non-returnable. A sample drum size is DOT specification 17C,
which has a net weight capacity of 500 pounds. In Section 173.119,
part (a) (4) of 41 Fed. Reg. 42474, Specification 17C states that
"metal drums (single-trip), with openings not exceeding 2.3 inches
in diameter" are to be used. When emptied, the drums are flushed
with water to prevent explosive peroxide formation and are then
filled with water to displace all air. The inside of the drum is
washed with a 5% by volume solution of methanol in perchloroethylene
at room temperature to disolve any peroxide compound that may have
formed.
3.6.5 Storage Methods
The National Fire Protection Association (1973) recommends
that outside or detached storage of VDC containers be used and that
79
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[PI') (LI) Tl'r
J
, Vapor From Storage TankX
A
N
Nitrogen From
Manifolded Cylinders
and
Reducing
Station
To Use
STORAGE TANK
Flexible O
Joints
Padding
Connection
1
Grounding) Wire
I
/
Unloading /
Connection/ »
Rail Should be Grounded
RANGE: Full vacuum to 100 psig.
2RANGE: -20°F to 200°F
Figure 3-2. Typical Tank Car Unloading Station for
Vinylidene Chloride
[Reprinted from Vinylidene Chloride: Handling/Properties/
Reactivity Ratios by PPG Industries by permission of
PPG Industries. (Year of first publication, 1975.)]
80
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storage containers be protected from physical damage. Inside stor-
age is provided for by a standard flammable liquids storage room or
cabinet. Oxidizing materials must be kept away from VDC. It is im-
portant that storage areas be selected to comply with local codes or
authorities.
.In all cases where the monomer is pumped from tank truck
or tank car to plant storage or from storage to process vessel, a
closed vent loop system should be used. There should thus be no venting
loss of vinylidene chloride to the atmosphere from VDG transfer operations,
3.6.5.1 Construction Materials
The chemical reactions between VDC and other substances
must be accounted for in selecting construction materials for stor-
age containers. The following have been recommended (PPG, 1975):
Steel, stainless steel and nickel should be used as materials for
storage tanks, pumps, valves, fittings and pipe which handle vinyl-
idene chloride. For uninhibited VDC, nickel is the material of
choice. Cast iron is not acceptable because iron can cause vinyli-
dene chloride to polymerize. Since many lubricants are attacked
by VDC, valves and fittings should be of a type that does not re-
quire lubrication. As it is possible for VDC to form explosive
compounds with copper, aluminum and their alloys, these metals must
not be used in storage and handling equipment (Dow, 1975).
3.6.5.2 Drums
Drums should be stored unopened in a cool, dry place for
not more than four months. Since bulging of a drum may indicate
VDC monomer decomposition with the possible formation of an explosive
peroxide compound, disposal precautions and procedures as described
in Section 3.6.6.2 should be taken. Recommended safe practices can
also be found in the Manufacturing Chemists' Association (1960) safe-
ty guide for flammable liquids.
81
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3.6.5.3 Tanks
VDC must be protected from contact with oxygen, sunlight,
water and other polymerization initiators. In the absence of these
substances, and when dry and blanketed by nitrogen with a maximum of
100 ppm oxygen, inhibited VDC can be stored indefinitely (PPG, 1975).
Tanks for VDC should be designed for working pressure of 30 psig
and be equipped with a pressure-relief valve, level guage, pressure
guage, and remote shutoff valves. Usually these tanks are 10,000
to 20,000 gallons in size, are above ground, and in some instances,
they are cooled by the use of brine coils. A water spray system
keeps the tanks cool in case of fire. Adequate dikes and drainage
are provided to confine and dispose of the liquid in case of a tank
rupture.
3.6.6 Accident Procedures
3.6.6.1 Fires and Explosion
In advanced fires, fire fighting is done from a safe dis-
tance or from a protected location. Dry chemical, foam or carbon
dioxide agents are materials that can be used as extinguishers. The
National Fire Protection Association (1973) concludes:
"Water may be ineffective, but should be
used to keep fire-exposed containers cool....
If it is necessary to stop a leak, use water
spray to protect men attempting to do so."
PPG (1975) states however that "if the source of the vinylidene
chloride monomer leak has not been closed off, do not attempt to
extinguish a large fire because hot metal can re-ignite an unburned
vapor cloud."
The explosive nature and handling procedures of the peroxide
compound formed by the reaction of VDC and air is discussed in
82
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Section 3.6.2. Extreme caution should be exerted in separating
precipitated polymer and its adsorbed peroxide.
3.6.6.2 Spills and Leaks
Spills and leaks from vinylidene chloride containers and
equipment should be handled promptly. All possible sources of igni-
tion must be eliminated and only properly protected and trained per-
sonnel should be allowed to remain in the vicinity of the spill or
leak.
The following clean-up procedures are recommended (PPG,
1975; Dow, 1975):
(1) Keep people away and do not permit smoking.
(2) If it can be done without personal risk, shut
off a leak.
(3) Dike the liquid from a large spill and pump it
into a salvage tank.
(4) Spilled vinylidene chloride should not be delib-
erately ignited.
(5) Water spray can be used to "knock down" vapors.
(6) If a spill is small, cover it with an absorbent
material such as sand. After the liquid has been
absorbed, remove the sand to a safe area. Immed-
iately flush the sand with a lot of water, but
don't let the water run off into a sewer.
3.7 ENVIRONMENTAL MANAGEMENT FOR VINYLIDENE CHLORIDE MONOMER
PRODUCTION
According to information supplied by the manufacturers of
vinylidene chloride monomer, overall losses of VDC from all sources
is of the order of 0.003 pounds per pound manufactured. Estimated
losses of VDC monomer at the three manufacturing sites are shown in
Table 3-4 and Figure 3-3.
83
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oo
-p-
MOHOMER PRODUCERS 338,600 Ibs.
MONOMER PRODUCERS
Figure 3-3. EstJ.tnated Losses for VDC btonomer from Monomer Producers in 1975
(Industry Sources, 1976)
-------
TABLE 3-4. ESTIMATED LOSSES OF VDC BY MANUFACTURING SITE
(Industry Estimates)
Losses Ibs/yr.**
1975 1976
Company
Dow Chemical Co.
PPG Industries
Freeport, Tex.
Plaquemine, La.
Lake Charles, La.
Total
100,600
238,000
200,000 t
300,000
538,600
to
638,000
*
*
200,000
300,000
to
*Somewhat higher due to increased production in 1976.
**Estimates by manufacturer.
PPG Industries Inc. reported that a substantial reduction
in emissions compared to the 1974 data as reported by Milgrom (1976)
were effected by installing a new vent control system in which all
major sections of the process, including storage tanks were tied together
into a common header. The vented gases then pass through a refri-
gerated condensing unit that removes about 907, of the VDC monomer
that had been previously lost.
j
Dow's air pollution control system is reported to utilize
a similar process in which all equipment and storage tank vents are
connected to a common header. The vent gases then pass through con-
densing equipment prior to venting to the atmosphere.
Data supplied by Dr. J. Pennington of the Texas Air Con-
trol Commission (1976), confirmed the emission losses submitted by
Dow Chemical Co. for the Freeport plant. About 75% of Freeport
plant emissions were from process, the balance from storage and fill-
ing operations,according to the Texas Air Control Commission data.
85
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Both monomer producers indicated that liquid losses were
nil. Any waste bottom streams from distillation processes were
destroyed by incineration. If any leaks should occur (for example,
pump seals) VDC would vaporize almost immediately. Since the pro-
cess for the manufacture of chlorinated hydrocarbons is continuous,
equipment clean-out operations familiar to batch processes is not
required. There are, therefore, no wash waters to be treated before
disposal.
Tank cars and tank trucks used for shipping VDC monomer
are in "dedicated service" and do not have to be cleaned prior to
filling and shipping.
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SECTION III. REFERENCES
American Conference of Governmental Industrial Hygienists (1971),
"Documentation of the Threshold Limit Values for Substances
in the Workroom Air," 3rd Edition, Akron, 351-2.
Bendetti (1977), National Fire Protection Association, Personal
Communication, January 19.
Code of Federal Regulations (1975), Title 46, Chapter 1, Coast Guard,
Department of Transportation, Paragraph 151.01-.10; Application
of Vessel Inspection Regulations, U.S. Government Printing
Office, Washington, D.C.
Crauland, M.J.L. (1954), U.S. Patent 2,674,573, April 6.
Crenshew, E. (1976), Occupational Safety and Health Administration,
Regional Office, Personal Communication, September 27.
Department of Transportation (1976), "Department of Transportation,
Materials Safety Bureau, Hazardous Materials Regulations, 49 CFR
Parts 171-177 (Interim Publication)," Federal Register, 4_1(188),
September 27, 42364-42638.
Dow Chemical Co. (1955), British Patent 734, 131.
Dow Chemical Co. (1975), "Material Safety Data Sheet for Vinylidene
Chloride," Midland.
Dow Chemical Co. (1976), Personal Communication, December 10.
Dow Chemical Co. (1977), Personal Communication, January 18.
Gage, J.C. (1970), "Subacute Inhalation Toxicity of 109 Industrial
Chemicals," Br. J. Ind. Med., 27(1), 1-18.
Manufacturing Chemists' Association (1960), "Safety Guide SG-3,
Recommended Safe Practices and Procedures—Flammable Liquids:
Storage and Handling of Drum Lots and Smaller Quantities,"
Washington, D.C.
Manufacturing Chemists' Association (1963), "Safety Guide SG-16,
Recommended Safe Practices and Procedures—Liquid Chemicals :
Sampling of Tank Car and Tank Truck Shipments," Washington,
D.C.
Manufacturing Chemists' Association (1972), Guide for Safety in the
Chemical Laboratory, 2nd Edition, Van Nostrand-Reinhold, Inc.,
New York.
87
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SECTION III. REFERENCES (CONT'D)
Manufacturing Chemists' Association (1975), "Manual Sheet TC-29;
Loading and Unloading Flammable Chemicals—Tanks," Washington,
D.C.
Milgrom, J. (1976), "Vinylidene Chloride Monomer Emissions from the
Monomer, Polymer, and Polymer Processing Industries, Arthur D.
Little, Inc.
National Fire Protection Association (1973), "Fire Protection Guide
on Hazardous Materials," 5th Edition, Boston.
National Fire Protection Association (1975), "National Electrical
Code," NFPA No. 1975, Boston.
Pennington, J. (1977), Texas Air Control Commission, Personal Communi-
cation, January 27.
PPG Industries, Inc. (1975), "Vinylidene Chloride: Handling/Properties/
Reactivity Ratios," Pittsburgh.
PPG Industries, Inc. (1976), Personal Communication, September 23.
PPG Industries, Inc. (1977), Personal Communication, January 4.
Prendergast, J.A., R.A. Jones, L.J. Jenkins, and J. Siegel (1967),
"Effects on Experimental Animals of Long-Term Inhalation of
Trichloroethylene, Carbon Tetrachloride, 1,1,1-Trichloroethane,
Dichlorodifluoromethane, and 1,1-Dichloroethylene," Toxicol.
Appl. Pharmacol., 1£(2), 270-89.
Sax, N.I. (1968), Dangerous Properties of Industrial Materials, 3rd
Edition, Van Nostrand-Reinhold, Inc., New York, 1229-30.
Shelton, L.G., D.E. Hamilton, and R.H. Fisackerly (1971), "Vinyl
and Vinylidene Chloride, Part 3," Vinyl and Diene Monomers,
Wiley-Interscience, Inc., New York, 24_, 1254-1289.
Smith, D. (1976), Department of Transportation, Materials Trans-
portation Bureau, Personal Communication, December 28.
Walker, S. (1976), U.S. Coast Guard, Marine Inspection Office,
Personal Communication, December 29.
88
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SECTION IV. CONSUMPTION PROCESSES STUDY
4.1 PRESENT STATUS OF THE INDUSTRY
Vinylidene chloride currently has three commercial uses:
a) the manufacture of 1,1,1-trichloroethane (methyl chloroform)
b) the production of a wide variety of copolymers
c) the synthesis of other chemical intermediates such as the
alkoxy chlorinated hydrocarbons
1,1,1-trichloroethane and chlorinated chemical intermediates
are manufactured by PPG and Dow respectively using captive VDC monomer.
The use of vinylidene chloride in the manufacture of these chemicals is
determined largely by the economics of competing processes.
VDC monomer is sold by PPG and Dow Chemical as a merchant chemical
to companies who manufacture a variety of polymeric materials. In
addition, Dow Chemical is a major VDC consumer for captive polymerization
to produce various products. The homopolymer of VDC is a crystalline,
brittle material that has substantially little commercial value. When
VDC is copolymerized with other monomers, a number of useful compounds
89
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are produced. The major comonomers used in the polymerization of
VDC are vinyl chloride, acrylic acid, methacrylic acid, acrylonitrile,
butadiene, and styrene.
Currently about 120 million pounds of VDC are polymerized
by 13 companies. Of these, Dow Chemical Co., one of the two producers
of the monomer, produces more than 50% of the VDC copolymers made in the
United States.
VDC copolymers find applications in the following industries:
Flexible Packaging Materials
• as a barrier coating on other flexible packaging materials
• as a coextruded or multilayer film
• as a monolayer film
Textiles
• as a flame retardant modacrylic fiber when
polymerized with acrylonitrile.
• as a flame retardant carpet backing when
polymerized with butadiene and styrene
Other
• as a plastic pipe
• as a coating for steel pipe
• as an adhesive
The barrier coating market for VDC polymers has reached the
stage of mature growth. Future growth of this market will tend to
parallel that of the food packaging industry. The biggest shift will
occur in the type of substrate film to be coated, as for example, the
shift from cellophane to polypropylene.
VDC competes on the basis of cost vs. performance with
other materials that can provide improved flame retardant character-
istics, such as alumina and organic phosphates. Performance is
dictated by both governmental and industrial regulatory agencies.
As these become more stringent for plastics and textiles, the great-
er will be the market opportunity for more expensive materials such as
VDC.
90
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In the following section, the major uses of VDC will be
discussed from the viewpoint of:
• Current processes used to produce the major end
product from VDC.
• Alternate processes for producing these end products.
• The market structure and consumption patterns for
the end products
Estimated consumption patterns of VDC in 1976 are shown in Table 4-1.
4.2 1,1,1-TRICHLOROETHANE MANUFACTURE
1,1,1-Trichloroethane, commonly known as methyl chloroform,
is manufactured commercially using several different process routes:
• Hydrochlorination of vinylidene chloride
• Chlorination of vinyl chloride
• As a coproduct of the direct chlorination of
ethane and ethylene
At present, PPG is the only manufacturer of 1,1,1-trichloro-
ethane using vinylidene chloride as the starting material.
4.2.1 Manufacture from Vinylidene Chloride
1,1,1-Trichloroethane is manufactured from VDC in PPG's
chlorinated hydrocarbon complex in Lake Charles, La., using a continuous
hydrochlorination process shown in the flow diagram, Figure 4-1.
The equation for this reaction is:
= CHC12 + HC1
Vinylidene chloride is fed together with hydrogen chloride
into a reactor operating at an elevated temperature. The gases leaving
the reactor are fractionated. Unreacted HC1 and VDC are recovered from
the fractionating column and recycled to the hydrochlorination reactor.
The crude 1,1,1-TCE product from the bottom of the fractionator is puri-
fied by distillation in a second column. The distilled 1,1,1-TCE
product, containing a maximum of 100 ppm VDC, goes to a blend tank
for addition of corrosion inhibitor, and then to storage.
91
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TABLE 4-1. ESTIMATED CONSUMPTION PATTERNS FOR VINYLIDENE CHLORIDE,
1976, MILLIONS OF POUNDS
(Industry and M. Sittenfield and Associates Estimates)
Manufacture 1,1,1-Trichloroethane 130
Polymerization 126
PVDC Resin
Barrier Coatings 26.8
Cellophane Coating 16.2
Film and Molded Products 46.2
Export 20.0
Flame Resistant Resins with VDC content
Modacrylic Fiber 9.0
Carpet Backing 7.5
VDC Losses
VDC Manufacture - Vented .55
VDC Polymerization
Vented to Atmosphere •56
Equivalent VDCM content of solid PVDC in
sewered wastes 7.4
Other Uses (Chemical Intermediate) 5.0
TOTAL ESTIMATED VDC MANUFACTURED IN U.S. 270
92
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VD
U)
VTJTYTTDF.NE CHLORIDE
HCL
RECYCLE VDC AND HCL
MAKEUP CATALYST
HYDROCIILORINATOR
FRACTIONATOR
RKCTCLF. 1.1.1-THE WTTH CATALYST
FRACTIONATOR
, TO SHIPMENT,
OF 1,1,1-TCE
Figure 4-1. Block Flow Diagram for 1,1,1-Trichloroethane Production
-------
The process is totally enclosed and operates with no vents
to the atmosphere and the possibility of VDC process emissions or other
t^ •** rt/* aco InooAQ TO o 1 mrt e +• r% -i 1
process losses is almost nil.
The only possibility of VDC emission would result from the vents
on the inhibitor blend tanks and product storage tanks, due to the small
amount of VDC monomer (100 ppm) residual in the final distilled product.
This, under worst conditions, would not exceed 17,500 Ibs. per year.
However, it is improbable that all of this loss would occur at the
manufacturing site. Further emissions from these sources are controlled
by piping the tank vents to a common system connected to an incinerator.
4.2.2 Alternate Routes of Manufacture
As stated above , other processes for the manufacture of
1,1,1-TCE are used. The specific process used by any of the
several 1,1,1-TCE producers is dependent on the company's
technology, their product mix, and the economics of the overall
operation.
In the first two processes previously listed, 1,1,1-TCE
is produced from vinyl chloride or vinylidene chloride which would
have been synthesized from ethylene dichloride.
The third process is a more complex process since the direct,
continuous non-catalytic chlorination of ethane produces a variety of
chlorinated hydrocarbons including ethyl chloride, vinyl chloride,
vinylidene chloride and 1,1-dichloroethane. The economics of producing
1,1,1-TCE from this process is dependent on the recycling of ethyl
chloride, 1,1-dichloroethane and other chlorinated products.
According to Lowenheim and Moran (1975), over 60% of 1,1,1-
trichloroethane is produced from vinyl chloride, 30% from vinylidene
chloride and the balance from ethane.
It is believed that since Ethyl Corporation stopped production
of 1,1,1-TCE in 1976, the amount produced from ethane has diminished.
94
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4.2.3 Development of New Technologies
It is reported that PPG, the only company presently using VDC
as the raw material for 1,1,1-TCE, will not use VDC as the raw material for
its new plant scheduled for operation in 1978. The new plant, with an
announced capacity of over 300 million pounds of 1,1,1-TCE yearly, will
more than double present capacity (Chemical Marketing Reporter, 1977)
Details of the process technology have not been made public. This
change in process will release more of PPG's existing VDC capacity for mer-
chant sale, should the demand picture require additional production.
4.2.4 Environmental Management of VDC in 1,1,1-Trichloroethane
Processes
Emission losses of VDC from the PPG plant during the production
of 1,1,1-TCE have been reported to be non-existent. The reason given
is that the process is a continuous operation. Separation of unreacted
VDC monomer occurs in a distillation column from which it is recycled
directly to the hydrochlorination reactor.
Handling of the feed VDC is done in a completely closed
system with venting of the feed tanks back to the storage tanks.
The product blend and storage tanks are vented to a common
system that goes to an incinerator. Hence the potential loss of VDC
from these sources would be negligible.
VDC-produced 1,1,1-TCE is reported to contain up to 100 ppm of
VDC monomer. Based on a probable production of 1,1,1-TCE from VDC of
175 million pounds per year, the possible distribution of VDC
from this source could equal 17,500 Ibs. per year. However, in terms
of commercial or environmental contact, distribution of 1,1,1-TCE is
so widespread that local concentrations would not exceed an order of
magnitude of 0.004 Ibs. per square mile, per year.
95
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4.3 POLYMERIZATION PROCESSES
Vinylidene chloride copolymers are manufactured in the form
of latex emulsions, powder resins, or modacrylic fibers. Three
basic processes are used:
• Emulsion polymerization
• Suspension polymerization
• Solution (solvent) polymerization
The selection of one technique over another is determined
chiefly by the end use. For example, emulsion processes are used
historically to produce coating latexes. Both suspension and emulsion
techniques are used to produce solid polyvinylidene chloride (PVDC)
resins used for solution coating, molding or extrusion. Solution
polymerization may be used for manufacture of modacrylic fiber. Each
of these techniques is used to produce polymers of differing physical
properties, which can be utilized more readily in subsequent convert-
ing operations. The majority of PVDC is manufactured using emulsion
polymerization techniques.
The characteristics of the polymer are strongly influenced
by the content of vinylidene chloride. Resins containing more than
50% (typically 70 to 951) vinylidene chloride exhibit excellent barr-
ier resistance and chemical resistance. Polymers with less than 50%
vinylidene chloride, typically 10 to 40%, are used when it is desired
to improve the fire retardant characteristics of the base monomer
material.
4.3.1 Emulsion Latex and Suspension Polymerization
Emulsion and suspension polymerization processes use essentially
the same type of equipment, and are similar in their overall character-
istics. They differ in the formulation of the batch, operating con-
ditions of temperature, time and agitation, degree of conversion of
the monomer, and techniques for removal (stripping) of residual monomer.
Some industry sources indicate that the suspension process is easier to
control and that there are fewer "lost" batches that must be sewered.
96
-------
Vinylidene chloride latexes generally contain 50 to 63%
solids, whether produced by emulsion or suspension process. A typical
latex polymerization process is shown in Figure 4-2. The vinylidene
chloride is fed together with the comonomer, emulsifier, catalyst,
water or solvent, stabilizer, and suspension agent into a reactor
that has been purged with an inert gas and evacuated. Evacuation
removes oxygen from the vessel and assists in the transfer of the
raw materials so .that venting of VDC to the atmosphere is minimized
at this stage of the process.
Heat and agitation are applied for a number of hours (8 to
24) until 90 to 95% conversion has been reached. The reactor con-
tents are then stripped in situ or pumped to a stripper where un-
reacted VDC and other monomers are removed.
In some plants, unreacted VDC and comonomers are stripped
and vented through a vacuum jet system to the atmosphere. In other
plants they are condensed, the monomer recovered and recycled.
Solution polymerization is used in connection with produc-
tion of fiber by means of a spinneret.
4.3.2 Solid Resins
Solid polyvinylidene chloride resins are used in the follow-
ing applications:
• Extrusion into film
• Coextrusion with other plastic film' to form a multi-
layer film
• Extrusion to produce pipe
• Coating cellophane by dissolving PVDC resin
in an organic solvent, forming a lacquer.
• Molding
97
-------
WATER AND OTHER
VAPOR EOIIALIZINP. LINE
/VDC TANK CAR\
o o
00
VDC BULK
STORAGE
FEED MATERIALS
>
k
"r
f VDC ""\
FEED TANK )
\/
LI
s
J
(-
\
. N
•^N
>
VI
I
C VACUUM
WATERS
TO WASTE WATER
TREATMENT OR
INCINERATOR
\(_
DRUM
Figure 4-2. VDC Latex Polymerization Process
-------
Both suspension and emulsion processes are used as the first step
in the production of PVDC resins. Figure 4-3 illustrates a typical
process for converting a latex to the powdered resin. In this
step of the process, the stripped latex is filtered or centrifuged.
The solid resin mass is then dried and packaged in fiber drums or
large Gaylord containers. The resin may be used for solution coating
of cellophane or other water sensitive films; for extrusion into films,
pipe coatings or monofilament fibers; or to produce molded products.
Dow Chemical Co. is the sole producer of merchant PVDC resins. DuPont's
Circleville, Ohio plant makes some resins for captive use.
4.3.3 Modacrylics
The process for the manufacture of modacrylic fibers
parallels that for producing dry resins using emulsion and solution poly-
merization techniques. The reactant monomer mix for modacrylic
fibers contains between 10 and 20% VDC, the balance being acrylic
monomers. In this copolymer, the vinylidene chloride is used for its
flame retardant properties.
Following polymerization, the latex is dried. Stripping
steam and monomer are condensed to prevent emission to the
atmosphere, the monomer is recovered for recycling. The waste waters are
processed in a conventional waste treatment plant. The dried polymer
is dissolved in a suitable solvent and sent to conventional wet spinning
processes for fiber formation.
The major producers of modacrylic fibers are listed in
Table 4-2.
99
-------
SUSPENSION RESIN
FROM POLYMER PLANT
CENTRIFUGE
VENT
1
DRYER
DRY RESIN TO
PACKAGING
O
o
TO WASTE WATER
TREATMENT
\/
HOT AIR
Figure 4-3. Conversion of Latex to Powdered Resin Process
-------
TABLE 4-2. PLANT SITES FOR POLYMERIZATION OF VINYLIDENE CHLORIDE
COMPANY
SITE
POLYMER TYPE
Dow Chemical Co.
W.R. Grace Chem. Co.
Morton Chemical Co.
A.E. Staley Mfg. Co.
E.I. DuPont
Rohm & Haas Co.
GAP Corp.
Reichhold Chemical
National Starch & Chemical
Tennessee Eastman
Monsanto Chem. Co.
American Cyanamid
Midland, Mich.
Dalton, Geo.
11
Owensboro, Ky.
Ringwood, 111.
Letnont, 111.
Circleville, Oh.
Knoxville, Tenn.
Chattonooga, Tenn.
Cheswold, Del.
Meridosia, 111.
Kingsport, Tenn.
Decatur, Ala.
Pensacola, Fla.
Emulsion Latexes
Suspension Resins
Specialty Latex
Emulsion Latex
Specialty Latex
Emulsion Latex
Emulsion Latex
Emulsion Latex
Emulsion Latex
Specialty Latex
Specialty Latex
Emulsion Latex
Modacrylic Fiber
Modacrylic Fiber
Modacrylic Fiber
101
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4.3.4 Development of New Technologies
The trend in polymerization technology is in the direction
of increasing the amount of conversion of VDC into polymer without
changing the desirable properties of the end product. Increasing con-
version helps to reduce the amount of VDC monomer that is left in the
polymer to be removed during the stripping operation. New stripping
techniques are also being developed to permit greater recovery of the
monomer in a state capable of recycling.
4.3.5 Polymerization Processing by Site
Plant sites using monomer vinylidene chloride for polymeri-
zation are shown in Table 4-2.
4.3.6 Environmental Management of VDC Monomer in Polymerization
Processes
Polymerization processes can introduce contamination to the
environment through emissions of monomer VDC as a gas, and in liquid
and solid wastes.
The majority of VDC monomer losses to the environment
related directly to the polymerization process are from two main
sources:
• Vent losses resulting from transfer of monomer
from one vessel to another
• Losses resulting from stripping unpolymerized
monomer from the product at the end of the reaction
Other losses to the environment result from periodic washing of the
reactors, stripping vessels, and product storage tanks, and disposal
of solid wastes resulting from a bad polymerization.
Management of air emission losses due to handling and transfer
of VDC monomer from rail car or tank wagon to storage and from storage
to reactor is achieved by interconnection of vents between vessels.
Further management during the VDC feed step to the reactor
is accomplished by first purging the empty vessel with an inert gas
followed by complete evacuation of the vessel. The VDC is then
sucked into the evacuated reactor.
102
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Air emission losses resulting from stripping of unpolymerized
monomer from the batch is by far the major source of VDC emission.
It is estimated that this step accounts for over 95% of VDC monomer
losses due to VDC polymerization operations.
No process currently used in the United States achieves
100% conversion of monomer to polymer. This is due partly to the
inability to achieve 100% conversion in a reasonable period of time,
and partly because the desired characteristics of the polymer may be
altered by prolonging the reaction time. Common practice is to
polymerize 90 to 98% of the monomer and to strip substantially all of
the residual monomer from the latex product. In smaller capacity
plants, this stripped monomer is vented to the atmosphere (see Figure
4-3).
At this point a distinction should be made between rates
of polymerization for different monomers polymerized together to
form a polymer. Thus, although the average degree of polymeriza-
tion might be 95%, it should not be assumed that 95% of each of the
comonomers has polymerized. It is conceivable that one of the minor
component monomers could have achieved a 99% conversion. Because
of this it is not possible to equate average degree of polymeriza-
tion with the quantity of unreacted monomer for a specific chemical.
Typical VDC emission losses as reported by major polymeri-
zing sites are given in Table 4-3. Estimated losses from all polymer
producers are displayed geographically in Figure 4-4.
TABLE 4-3. VDC EMISSIONS LOSSES AT MAJOR POLYMERIZATION
SITES (Industry Sources, 1976)
Site Reported emissions Estimated Emission
Ibs VDC/100 Ibs. VDC Ibs/yr
processed
A > 0.3 260,000
B 1.3 90,000
c 2.8 9,000
D 1.0 10,000
E -64 60,000
103
-------
o
-p-
POLYMER PRODl'CERS 118.380 Ids
POLYMER PRODUCERS 179,QUO Ibo.
POLYMER PRODUCERS
Figure 4-4. Estimated Losses for VDC Monomer from Polymer Producers in 1975
(Industry Sources, 1976)
-------
As can be seen from Table 4-3, emission losses vary from
a reported low of 0.3 pounds per 100 pounds of VDC polymerized to
2.8 pounds per 100 pounds. The wide variation is related to the
type of product manufactured and to the volume of VDC polymerized.
The smallest emission loss was reported by a company that
polymerizes a large quantity of VDC where the quantity of VDC emitted
is sufficient to justify control equipment.
The largest emission loss was reported by a company that
polymerized less than 500,000 pounds of VDC per year. This company
noted that .the amount of emission loss was so small that the cost of
installing control equipment would make the operation uneconomical.
VDC latexes fall into two classes:
(1) Latexes, used principally in the production
of films, or in coatings for paper and plastic,
that contain over 50% VDC (typically 85 to 90%)
(2) Specialty latexes in which the percent VDC is
below 50% used in the production of fire retardant
rug backing
In the case of specialty latexes, the conversion is typically
in the 90% range. For this group of products, it is estimated that
VDC consumption is on the order of 7 to 8 million pounds per year.
Although average conversion is about 90%, it is reported
that smaller VDC concentrations tend to react more completely. The
composition of the vent gases is such that conventional emission control
systems using either condensation or incineration would be too
costly to install and would substantially increase energy demands .
and costs.
For the bulk of the copolymers, containing over 50%
VDC and used for films and coatings, the degree of monomer con-
version is between 90 and 98%. For the large volume VDC polymer
manufacturers, technology improvements and control systems have
been feasible.
105
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One company that produces approximately 75% of all VDC
polymer products, reported 1975 emissions of 0.27% equal to 258,000
Ibs. per year.
If the efficiency of the emission control systems of the
other polymerization plants is less than the most efficient site
and is of the order of 0.75%, then the VDC emissions from these
operations could approach 262,000 pounds per year. Adding the 258,000
Ibs. to this figure, it is estimated that 520,000 pounds of VDC are
emitted per year from all polymerization sources.
All major polymerization companies report continuing efforts
to improve the polymerization efficiency as a means of reducing the
amount of unpolymerized monomer that must be stripped from a given
batch. The installation of control equipment, such as condensers is
always considered by the processor. However, most of them have noted
that the cost of such installations for small capacity plants (less
than 3 million pounds per year) can be prohibitive. This is particul-
arly true if the site does not include other ethylenic type poly-
merization processes.
Polymerization processes are historically batch .operations.
Consequently, reactors, strippers and storage vessels must be cleaned
periodically. The wash waters contain polymerized VDC, plus small
quantities of VDC monomer. One source indicated that the PVDC content
of the waste liquid stream represented about 6% of the VDC monomer
polymerized. The residual VDC monomer in this waste stream was about
0.05% of the PVDC in the liquid waste. Another polymer manufacturer
reported that about 1-1/2 to 2% of the PVDC polymer produced is sent
to waste disposal.
106
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All polymerization companies reported that liquid wastes
are sent to waste control disposal areas. It is estimated that of the
.135 million pounds of VDC polymerized each year, up to 8.1 million pounds
of PVDC are sent to liquid waste disposal systems. About A,000 pounds
of monomer VDC are in the liquid wastes originating from polymer
operations.
4.4 POLYMER CONSUMPTION PROCESSES
Polyvinylidene chloride is sold as a latex emulsion contain-
ing 50 to 63% solids, or as a dry resin. The polymer content of these
resins typically contains 75 to 90% VDC, the balance being the
comonomer.
PVDC latexes are used chiefly for coating packaging film
substrates to improve their barrier properties and to provide
heat sealing properties to the film. Among the films that are
coated with this product are paper, polypropylene, nylon and polyester.
The flame retardant property of VDC is utilized in those latexes in which
the VDC content is less than 50%. Typical of this are latexes, pre-
pared by copolymerizing 10 to 40% VDC with butadiene-styrene, to be
used as a flame retardant, resilient backing for carpets.
Solid PVDC resin is used chiefly to extrude film, mono-
filament fiber, or pipe. A second use is in the preparation of
a solvent solution for coating cellophane.
When VDC is copolymerized with 70 to 90% of acrylic monomer,
the resultant polymer is used to manufacture modacrylic fibers, an
acrylic fiber with improved flame resistivity.
4.4.1 Film Extrusion
PVDC film is extruded using both conventional flat die
extrusion and blown film extrusion techniques.
The flat die extrusion process is often used as an in-
line unit which is part of a complete food packaging system.
This technique is used for smaller extrusion lines.
107
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The resin, purchased pre-blended in fiber drums, is fed to the
extruder. The molten resin is then forced through a flat die to
form a film. The film then moves to the packaging section where
it is wrapped around the food item. Film scrap losses from this
system can be as high as 50%.
Figure 4-5 is a representative flow diagram of the blown
film process. It is identical to that used to extrude PVC,
polyethylene and similar films. If a shrink film is desired, the
blown film process is modified so that tension is applied to the
blown film before it is completely cooled. This increases the
molecular orientation of the polymer forming a "biaxially" oriented
film.
As shown in Figure 4-5 the powdered resin is received either
in 1,000 pound Gaylord containers, or in bulk hopper rail car. From
here, the PVDC powder, which is an 85 to 90% copolymer with vinyl
chloride, is fed to the compounding line where it is blended with a
variety of additives, including stabilizers and plasticizers.
Mixing or compounding is carried out in a high intensity
blender (i.e. a Banbury)• The intense mechanical action in the blender
develops sufficient heat to raise the temperature of the compounded
plastic material to as much as 170°F (77°C).
From the Banbury mixer, compounded resin passes to the blown
film extruder. If a biaxially oriented film is desired, a process
is used in which the bubble, as it is formed, is subject to a
stretching technique. The film is then "converted," i.e., slit to
size and wound on rolls. Scrap losses as high as 25% are not uncommon
as a result of the converting operation.
If the blown, stretched film is cooled rapidly, the resulting
film has "shrink" properties. Upon reheating, it will shrink to
its original unstretched condition.
In 1974, the powdered resin had a residual VDC monomer
content of about 100 ppm. Since then, process improvements have
reduced the residual monomer content of these resins to 20 ppm
or less. The VDC monomer content in the preblended resin used in 1976
108
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HOPPER CAR
OOXA/OO
AIR COMVEYER
TRUCK OR
RAIL CAR
SILO
VENT
RECOVERED PVDC
AIR
CONVEYER
PLASTICIZERS AND
vcJk
ADDITIVES
WEIGH
TANK
VENT
7\AA>
RIBBON MIXER
HIGH INTENSITY
(BANBURY)
BLENDER
GAYLORD CONTAINERS
WAREHOUSE
EXTRUDER
TO FILM
WINDUP
Figure 4-5. Blown Film Process
-------
by one extruder of flat film is reported to be below 7 ppm. In the
blown film process, the residual monomer together with other fumes
generated in the blender as a result of the mechanically generated
heat, are vented to the atmosphere through an induced fan ventilation
system connected to a hood stack over the mixer. These fumes contain
some if not most of the VDC monomer residual in the purchased resin.
With adequate ventilation of the blender, VDC levels in the plant
environment are as low as 0.001 ppm.
In the smaller, flat die extrusion operations, the VDC
monomer contained in the resin would be vented through the extruder.
None of the film extruders treat the gases vented from the extrusion
process.
Coextrusion is a new development in which a customized film
may be made combining the mechanical and other properties of more
permeable polymers with the high barrier properties of PVDC copolymers.
Coextruded film permits the use of thin films of the expensive PVDC
copolymer with outer layers of resins that are easier to process, more
thermally stable and less expensive.
The process uses flat film extrusion techniques in which
each polymer is extruded separately and combined using a calender plus,
in most instances, an adhesive. Tubular coextrudates ean also be made
using those extruders to produce a five layered structure of poly-
ethylene, glue, high barrier PVDC, glue and polyethylene (Leahy,
1976).
4.4.2 Coating Processes
There are two different methods of coating flexible films
with PVDC. In one, the resin is dissolved in a suitable solvent to
produce the coating "dope"; in the other, an aqueous emulsion latex
is used. The aqueous emulsion latex is the more commonly used mater-
ial for application of a PVDC barrier coating. The solvent coating
method is used when the film to be coated is sensitive to water, such
as cellophane.
110
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4.4.2.1 Cellophane Coating
Cellophane is an example of a film coated from a solvent
solution. A representative cellophane solvent coating operation is
shown in Figure 4-6.
The polymer resin is received in 1,000 pound paperboard
unlined Gaylord containers and stored until required. The polymer
is taken from storage and fed into a mixing tank where it is dissolved
in a suitable solvent (such as tetrahydrofuran). From the mixer, the
lacquer is transferred to a closed, vented tank until ready to be used.
The lacquer is pumped from storage to the roll coater where it is
applied to the cellophane sheet. The coated cellophane film goes to
the solvent removal oven, then to the humidifying oven and finally
to wind-up.
All the equipment is enclosed and under a slight negative
pressure. The indraft of air prevents emission of fumes into the plant
operating area. The indraft air from the equipment is vented to a
common header together with the exhaust air from the solvent removal
oven. The exhausted air stream is blown through activated carbon adsorbers
in which the solvent is removed and the solvent-free gases are vented
to the atmosphere. The solvent is recovered by regeneration of the
adsorber system, purified and returned to the process. The adsorbers
are operated in such a way that any VDC monomer that might have been
released during the coating and drying operation is at best only
partially adsorbed. The majority probably "blows" through and is vented
to the atmosphere.
The maximum quantity of VDC monomer that could be emitted
at all the cellophane coating plants, based on a 20 ppra content in
the polymer, would not exceed 360 pounds per year, or about one pound
per day divided among the three coating locations (see Table 4-10).
4.4.2.2 Emulsion Coating
The great majority of flexible packaging film is coated
using a latex emulsion, since the water base does not adversely
effect the quality of the flexible film base. Because the PVDC
111.
-------
SOLVENT
STORAGE
VENT
p" •" "V N x
I
1
1
1
1
1
tax
t
ING
TANK
1
VENT
VENT HEADERS
A
PVDC
STORAGE
\ I
I I
RECOVERED
SOLVENT TO STORAGE
WATER TO WASTE TREATMENT
LACQUER
STORAGE
I
E
^ /
FT1.M
q_
c
iL-
V
N
COATER
\ >
\
X
' \
^ X
SOLVENT
' REMOVAL OVEN —
?
DISTILLATION
UNIT
VENT ^
VENT <
ABSORBER
ABSORBER
HUMIDIFYING
OVEN
TO FILM
WINDUP
o
FIGURE 4-6. CELLOPHANE SOLVENT COATING PROCESS
-------
latex used for coating packaging films is water based, they can be
applied by almost any packaging film converter using standard coating
machinery. The basic difference between a large and a small converting
operation is the size and complexity of the machines. Most converters
of packaging materials have coating equipment in their line. Hence they
would find it easy to apply a PVDC coating to any substrate when re-
quired. Although there are a number of major converters (see Table
4-2), there are an even larger number of small converters that can
coat paper or plastic film when they have orders.
The equipment used to coat flexible film consists of a roll
coater to which is fed the latex and the film. Depending on the coat-
er design the film may be coated on one or two sides. The coated film
then passes to the dryer oven. It is in this apparatus that sub-
stantially all the residual VDC monomer contained in the latex will
be released and vented to the air.*
Based on a residual monomer content in the latex product of
50 ppm, as reported by the major barrier latex producers, and an es-
timated consumption of approximately 30 million pounds in 1976, cal-
culations indicate that only 1,500 pounds per year of VDC monomer are
emitted by the more than 36 major converters.
4.4.3 Specialty Latexes
These latexes are usually copolytners of VDC with other monom-
ers where the VDC content is less than 50%, typically 10 to 40%. VDC
is used in these polymers for the flame retardant property that it
imparts,
Representative of these latexes are those in which butadiene-
styrene is copolymerized with VDC to produce a flame retardant elast-
omeric backing for carpets.
The process for using these latexes is common to the industry
and consists of applying the latex, usually compounded with foaming agents
*Industry Sources.
113
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as a relatively thick coating on the carpet. It then is conveyed to
the curing and drying ovens.
It is our present understanding that little effort is made
to control the emissions from this operation. Industry reports in-
dicate that the VDC monomer content of the specialty latexes is less
than 4 ppm, based on solids content. Based on the production of about
50 million pounds of these VDC-containing resins, it is estimated that
the total amount of VDC monomer that could be emitted by carpet manu-
facturers would not exceed 100 pounds annually.
4.4.4 Environmental Management
Current polymerization technology permits the production of
latexes with a VDC monomer content of less than 100 ppm, based upon
dry solids. Most latex manufacturers currently report they are pro-
ducing latexes with VDC monomer content on the order of 50 ppm.
Resins used for extrusion or for solvent coating have VDC monomer con-
tents on the order of 20 ppm.
These low levels of monomer for both classes of products have
been achieved within the past two to three years. The manufacturers
of PVDC latex report that they have been modifing their processes to
effect reduction in VDC monomer content. They report, typically, re-
ductions from a level of 600 ppm in 1971 to less than 50 ppm in 1976.
On this basis, total VDC monomer in the products sent to
latex coaters can be calculated to be 1,500 to 2,000 pounds per year
(based on 50 ppm content in 30 to 40 million pounds). This total
quantity is released in varying amounts by over 40 establishments in
all parts of the U.S.
Industry sources report that the rug backing latex as sold
contains from 15 to 20 ppm of VDC monomer. Based on a current sales
114
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of about 40 million pounds of PVDC containing latex to the rug in-
dustry, the maximum VDC monomer emission loss at all the rug and
carpet manufacturing plants is calculated to be 600 to 800 pounds
per year.
The quantity of VDC monomer in the resins used by cellophane
coaters is on the order of 320 pounds per year (an estimated 16 million
pounds consumed with 20 pptn VDCM content) at three sites. Based on an
estimated 80% loss of the residual VDC monomer content in the polymer,
during coating and drying of the cellophane the VDC monomer content.
of the polymer on the coated cellophane is calculated to be approxi-
mately 4.0 ppm.
Extruded products, chiefly films, consume about 38 million
pounds of VDC polymer resins annually. These resins contain a maximum
of 20 ppm VDC monomer content as shipped. The amount of VDC monomer
contained in the resins used for extrusion amounts to an estimated 760
pounds per year.
One industry source also indicated the sale in 1975 of an
experimental polymer containing a total of 3222 pounds of VDCM residue.
This material was used in perhaps 30 or so points in the U.S.
Information supplied by one source indicates that residual
VDC monomer in finished PVDC containing products, e.g. saran fiber;
extruded film; coated paper, plastic or cellophane film, is less than
2.5 pounds per million pounds of polyvinylidene chloride. Based upon
a total production of about 120 million pounds of FVDC copolymers, the
probable amount of VDC monomer in converted products sold in the U.S.
is calculated to be of the order of 200 to 300 pounds.
In those cases where the coating operation is a normal part
of a packaging converting line, the drying section is usually connect-
ed to an emission control unit. This unit may consist of an adsorbent
or an incinerator. In these cases, any VDC monomer emission would be
removed from the system effulent.
Estimated losses of VDC monomer from converters are shown
in Figure 4-7.
115
-------
( !
' •
Figure 4-7. Estimated Losses of VDC Monomer from Converters in 1975
(Industry Sources, 1976)
-------
Discussions with converters revealed an awareness of the
potential health and environmental implications of residual VDC
monomer in the polymer resins purchased. The thrust of this concern
has been directed more at obtaining resins from the polymerizers with
the lowest possible monomer contents, than at implementing pollution
control technology in their own converting operations. These pressures
on the polymer producers appear to have had a direct impact as witness-
ed by the significantly lower levels of monomer achieved in both
latexes and dry resins over the past two years.
4.5 MARKET STUDIES FOR VINYLIDENE CHLORIDE CONSUMPTION
Vinylidene chloride monomer has three major commercial uses.
(1) Synthesis of 1,1,1-trichloroethane
(2) Production of various polymeric compositions
(3) Intermediate for captive organic chemical synthesis
The production of vinylidene chloride is dependent on the
market for the various products derived from it. This section will
discuss past, present and future markets for the several products
derived from vinylidene chloride. Major emphasis will be placed on
the uses of VDC polymers since these have the widest dissemination
in the economy and have the greatest potential for containing residual
monomer.
4.5.1 1,1,1-Trichloroethane (Methyl Chloroform)
Production and sales data for 1,1,1-TCE are given in the
annual reports on Synthetic Organic Chemicals - U.S. Production and
Sales, published by the U.S. International Trade Commission (former-
ly U.S. Tariff Commission). This data is summaried in Table 4-4.
The average annual growth rate for production of 1,1,1-TCE
has been about 10%. It is estimated (Lowenheim and Moran, 1975) that
about 3070 of the methyl chloroform produced in the United States is
derived from vinylidene chloride. Based on this estimate, the amount
of vinylidene chloride consumed to synthesize 1,1,1-TCE for the period
1966-1976 can be calculated and is shown in Table 4-5.
117
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TABLE 4-4. PRODUCTION OF 1,1,1-Trichloroethane in Millions of Pounds
(U.S. International Trade Commission 1975-1977; U.S. Tariff Commission 1968-1974)
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976
242.9 269.7 299.4 324.3 366.3 374.6 440.7 548.4 591.6 458.7 582.8
£ TABLE 4-5. CALCULATED CONSUMPTION OF VDC FOR 1.1.1-TRICHLOROETHANE PRODUCTION
oo
MILLIONS OF POUNDS
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976
52.9 58.8 65.2 70.7 79.8 81.6 95.9 127.4 128.9 99.9 127
-------
TABLE 4-6. MANUFACTURERS OF 1,1,1-TRICHLOROETHANE
(Chemical Marketing Reporter, 1977)
.--.-- - I
Company Plant Capacity (millions of pounds)
Dow Chemical Co. Freeport, Texas 450
PPG. Inc. Lake Charles, La. 175
Vulcan Geismar, La. 65
The manufacturers of 1,1,1-TCE and their estimated capacities are shown
in Table 4-6. Based on the reported capacity for PPG's existing plant,
maximum VDC consumption is calculated to be about 130 million pounds.
Industry opinion is that the consumption of vinylidene
chloride used to manufacture 1,1,1-trichloroethane is perhaps 15
to 20% higher than the volume calculated in Table 4-5.
Future technology changes indicate that new plants will
use processes that do not start with vinylidene chloride. Indus-
try sources report that the new PPG plant expansion for 1,1,1-
trichloroethane scheduled for operation in 1978, which will double
its capacity to over 300 million pounds per year, will not be
based on vinylidene chloride. The change in PPG's technology is
believed to be related to the economics of their overall chlorin-
)
ated hydrocarbon operation.
A full study of the 1,1,1-TCE market is not part of the
scope of this study. There are several commercial routes for the
manufactuEe of 1,1,1-TCE, and PPG's announced plant expansion is
reported to use one of the alternate routes. Thus a study of the
overall market growth of 1,1,1-TCE could contribute little to the
understanding of the future impact of VDC on the environment.
4.5.2 Polymers of Vinylidene Chloride
Vinylidene chloride, because of its chemical structure
(described in Section 2.3) has the ability to react with itself
(polymerize) or with monomers of similar structure to form long
119
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chain polymeric materials.
The homopolymer VDC is used infrequently because it forms
a crystalline, brittle material. When copolymerized with other
monomers, these physical characteristics are modified and a number
of useful products can be made.
Some of the monomers used in forming copolymers include:
Vinyl Chloride
Acrylic Acid
Methacrylic acid
Acrylonitrile
Butadiene
Styrene
Vinylidene chloride copolymers have three properties
that contribute to their commercial usefulness:
• Barrier resistance to gases, chiefly oxygen, water
vapor, odors, fats and oils
• Non-flamtnability, that enables it to impart flame
retardant properties to other materials
• Chemical inertness
The principal commercial applications of vinylidene chloride
copolymers are:
• As an extruded film for packaging
• As a barrier coating on various flexible film
packaging materials
• To produce modacrylic fiber, a flame
retardant textile
• Extruded to form a mono-filament fiber
• To produce a flame retardant backing on
carpets
• To manufacture plastic pipe or as a liner for steel
pipe
4.5.2.1 Extruded Film
Extruded PVDC film, commonly known as Saran, is used
in food packaging. Because of its excellent barrier properties to
moisture and oxygen, it is used extensively in packaging fresh meats,
processed meats and cheese, frozen poultry, etc.
120
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"Shrinkwrap" saran film is used where tight fit is needed
to cover irregular objects. Non-shrink-wrap saran film finds
general use for food packaging and storage. The uses of saran wrap
are summarized in Table 4-7.
TABLE 4-7. COMMERCIAL APPLICATIONS OF SARAN WRAP
SHRINKWRAP
Packaging fresh meat for shipment
from the slaughter houses to
the butcher
. v^' i
Packaging frozen fowl
Processed meat products
Cookie dough
NON-SHRINKWRAP
Packaging processed meat
products
i
Cheese products
Fresh meat packages for sale
in supermarkets and meat stores
Household wrap
The major extruders of PVDC (Saran) film are shown in
Table 4-8. All the producers of film listed, except Union
Carbide Corp. use PVDC resin supplied by Dow Chemical Co. Union
Carbide uses resin imported from its Japanese partner, Kureha.
TABLE 4-8. MAJOR EXTRUDERS OF PVDC FILM
Company
Dow Chemical Co.
Cryovac Corp.
(Div. of W.R. Grace)
Dobekman (Div. of American
Can Company)
Oscar Mayer Co.
Union Carbide Corporation
Plants
Midland, Michigan
Simpsonville, S.C.
Cedar Rapids, Iowa
Iowa Park, Texas
Cleveland, Ohio
Madison, Wisconsin
Sherman, Texas
Los Angeles, Calif.
Davenport, la.
Chicago, 111.
Nashville, Tenn.
Philadelphia, Pa.
Centerville, Iowa
121
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The market for commercial applications of Saran film has
been increasing at a rate of over 10% per year until recently.
Changes both in technology and in the growth patterns in the consum-
ing industries indicate that this large growth rate may not be
sustained.
A major technological innovation that will affect PVDC
demand in the production of shrinkwrap film, is a change from the
use of a relatively thick PVDC mono-layer film to a multi-layer
laminate consisting of two layers of a poly-film (polyethylene,
nylon or polyester) with a thin sandwich of PVDC film. The Dow
tradename for this laminate is Saranex. The effect of this change
will be a reduction of the demand for PVDC film resin to one-seventh
its present consumption. However, since the phasing out of the mono-
layer film will be accomplished over the next five years, and the
demand for film for meat and poultry is expected to increase at a
5 to 10% per year rate, the actual impact on PVDC resin consumption
for commercial film will be slight.
The household wrap market is very competitive. Many
materials compete for a saturated market. Among these are:
Polyethylene
Wax paper
Aluminum foil
Polyester
Polyvinylidene chloride (Saran)
Polyvinyl chloride
The growth rate for household wrap Saran film is very small and
seems to follow the general growth of the population. This growth
rate will not increase unless the price of Saran wrap drops to a
more competitive level with respect to other films. The estimated
VDC consumption by PVDC manufacturers is shown ih.Table 4-9.
122
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TABLE 4-9. CURRENT PRODUCTION OF PVDC FILM
(Industry Sources, 1976)
Manufacturer* Estimated VDC Consumption (1976)
(millions of pounds)
A 10.8
B
C
D
Others
TOTAL
4.5.2.2 Barrier Coatings
Another major application of PVDC or Saran resin in food
packaging is as a coating on a variety of other substrates to pro-
vide improved barrier properties. Among the substrate films coated
are:
• Cellophane
• Paper and paper products (including glassine)
o Polyester
o Polypropylene
• Nylon
• Polyethylene
The markets for packaging film materials in the food
industry are highly competitive. Price, printability, convertibil-
ity, packaging machine handling characteristics, and ability to
withstand shipping and handling in the store all play a role in the
selection of a film for packaging a given food product.
PVDC copolymers provide the greatest barrier resistance
to diffusion of gases and vapors. Coating a less expensive, stronger
film base with a thin layer of PVDC resin can produce a film with
enhanced barrier properties at a lower cost than can be obtained
*The estimated consumption represents totals for each company and not
individual site consumption data.
123
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by using a PVDC film or the less expensive film in sufficient thick-
ness to provide the desired barrier properties.
The Saran coated film market has been stable over the last
few years despite fluctuations in demand for a given substrate. For
example, use of polypropylene and polyester films in food packaging
has increased dramatically in the last five to ten years. This has
been at the expense of older, more conventional materials such as
glassine and cellophane. Thus, while the paper product food pack-
aging market has decreased, other plastic film markets have opened
up in their place. In almost all cases, barrier properties are pro-
vided by Saran coatings.
Cellophane
The percentage of cellophane coated with PVDC has been
increasing with respect to the total production of cellophane. How*
ever, overall cellophane production in the United States has been
decreasing as it loses markets to other packaging films such as
polyethylene and polypropylene.
The share of the cellophane market among the three pro-
ducers is shown in Table 4-10.
The average weight of PVDC on cellophane is estimated to
be 8-1/2%, based on an average coating weight of 3 gms/sq m. Indus-
try sources estimate that approximately 18 million pounds of poly-
vinylidene chloride copolymer are currently being consumed for coating
cellophane. The present consensus of the industry is that the pro-
jected consumption of polyvinylidene chloride copolymer for coating
cellophane during the next five years will remain static or slowly
decline.
Loss of non-food cellophane markets to other plastic
films, chiefly polypropylene and polyester may be balanced by a
proportionate increase in the use of saran coated cellophane for
snack food packaging. Age of plants and increasing cost to
manufacture cellophane will have a negative impact on the cost
competitiveness of cellophane with plastic films.
124
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TABLE 4-10. CELLOPHANE MARKET
(Industry Sources)
Company Plant Location 70 Share of Market
DuPont Clinton, Iowa 40
FMC Fredricksburg, Va. 35
Philadelphia., Pa.*
Olin Corporation Pisgah, N.C. 25
100
*The Marcus Hook plant of FMC was closed
in January, 1977. All production of FMC's
coated cellophane will be done in the
Fredericksburg plant.
125
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The cellophane production in the U.S. is given in Table 4-11, with the,
estimated percentage that is coated with polyvinylidene chloride.
Paper Products, Glassine and Plastic Films
The primary application of PVDC emulsion latex is to pro-
vide barrier properties to paper, paper board, glassine, and plastic
flexible film.
In contrast to cellophane coating which uses a solvent
solution of PVDC resin, these flexible film substrates are coated
using an aqueous emulsion latex. The coating process, using a water
based emulsion latex, is non-hazardous (no solvent) and is compat-
ible with typical packaging converting equipment that would include
in its line a conventional roll coating unit. Consequently, the
coating of the flexible film materials other than cellophane can
be done in a large number of establishments. These range in size
from those capable of consuming as much as 5 to 6 million pounds
of PVDC per year, to those using as little as 40,000 pounds.
The emulsion copolymers used as barrier coatings contain
between 75 and 90% vinylidene chloride, the balance consisting of
vinyl chloride or acrylates. As discussed earlier, use of a PVDC
copolymer coating upgrades less expensive forms of packaging
material by providing them with improved barrier resistance to
water vapor, gases, odors, oils and greases. Coating weights of
from 3% to 20% are applied.
PVDC coated flexible films are used for packaging a variety
of foods including candy, bread, cake, crackers, potato chips, meat,
cheese, snack foods of all types, and cereals. Coated paper board
stock is used for bottle caps, mayonnaise jar covers, etc. In add-
ition PVDC coated papers are used for such non-food items as soap
and cosmetics because of their barrier properties.
Estimates of the quantities of PVDC latex used for coating
the various substrate films are shown in Table 4-12. The major
coaters and their plant locations are shown in Table 4-13.
126
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TABLE 4-11. PVDC-COATED CELLOPHANE PRODUCTION, MILLIONS OF POUNDS
(Modern Packaging Encyclopedia, 1975,
Industry sources, M. Sittenfield and
Associates, estimates)
N)
Total Cellophane
Estimated % Saran coated
Saran Consumption
VDC content in Saran (90%)
1970
340
40%
1973
325
52%
1974
335
54%
16
14.4
1975
1976
270
54%
12.4
11.2
300
56 to
18
16.2
60%
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TABLE 4-12. CONSUMPTION OF VDC AS A LATEX COATING
(M. Sittenfield & Associates estimates)
SUBSTRATE % SUBSTRATE VDC CONSUMED
COATED WITH PVDC (Millions of Ibs.)
Glassine and Paper 60% 14
Paperboard 5% 1.6
Plastic Film (Polypro-
pylene, Polyester,
Polyethylene) 32% 8
Miscellaneous Materials 10% 3.2
TOTAL 26.8
It has been estimated that approximately four to five
million pounds of polyethylene film are currently being coated
annually, consuming between 400,000 and one million pounds of
PVDC. Industry data indicate that currently 15 million pounds of
polyester film, 30 million pounds of oriented polypropylene, and
two million pounds of nylon film are being coated with PVDC. Based
on reported coating weights of 20% on polyester, 10 to 15% on
polypropylene and equivalent percentages on nylon, present PVDC
consumption on these films is estimated at 3.0, 3.0 to 4.5 and 0.3
to 0.45 million pounds respectively.
Both PVDC coated polypropylene and PVDC coated polyester
films are relatively new factors in the packaging field. As a
result, demand for these coated materials is expected to grow at
a relatively higher rate than the normal economic growth for the
next five years as they take over older packaging film markets.
It is expected that the growth will tend to slow to a rate in
keeping with the general growth of the economy.
Polyester film markets in food packaging opened up at
about the same time as polypropylene (mid-60's). Projected growth
rate of PVDC coated polypropylene is estimated at 20% per year, while
coated polyester is experiencing a somewhat slower growth rate,
128
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TABLE 4-13 MAJOR PVDC LATEX BARRIER-COATING USERS
CMilgrotn, 1976 and M. Sittenfield and
Associates, 1977)
PAPER AND GLASSINE SUBSTRATE
COMPANY
PLANT LOCATION
Oneida Packaging Div. (Deerfield-Reed Corp.)
American Bag and Paper
Consolidated Paper
Crown Zellerbach
Daniels
Diversa-Pak
Dixico
DuPont
I-Iilprint
Suretech Coating (Philip Morris)
Rexham
Rhinelander (Div. of St. Regis)
Thilmany
Chase Bag Co.
Print Pak
'PAPERBOARD SUBSTRATE
Clifton, N.J.
Philadelphia, Pa.
Wisconsin Falls Wis.
Portland, Oregon
Rhinelander, Wis.
St. Petersburgh, Fla.
Dallas, Texas
Circleville, Ohio
Milwaukee , Wis .
Nicholasville, Ky.
Memphis, Tenn.
Rhinelander, Wis.
Kaukauna, Wis.
Hudson Falls, N.Y.
Atlanta, Ga.
Gordon Cartons
Green Bay Packaging
Interstate Folding Box
Michigan Carton Co.
Olinkraft
Zumbril
Baltimore, Md.
Green Bay, Wis.
Middletown, Ohio
Battle Creek, Mich.
W. Monroe, La.
Cincinnati, Ohio
PLASTIC SUBSTRATE
COMPANY
DuPont
Cryovac
Minnesota Mining & Mfg.
Allied Chemical Corp.
Hercules
Milprint
Cryovac
Curwood, Inc. (Div. of
Bemis)
American Can Co.
Standard Packaging
Sealed Ait Corp
PLANT LOCATION
Circleville, Ohio
Simpsonville, S.C.
Irvington, N.J.
Decator, Ala.
Pittsville, Pa.
Convington, Va.
Milwaukee, Wis.
Simpsonville, S.C.
New London, Wis.
Neenah, Wis.
Clifton, N.J.
Fairlawn, N.J.
TYPE OF PLASTICS
Polyester
Polyester
Polyester
Nylon
Polypropylene
Polypropylene
Polypropylene
Polyethylene
Polyethylene
Polyethylene
Polyethylene
129
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estimated at about 107« per year. Another newcomer to the barrier-
coated packaging market is nylon. Legs than two million pounds per
year of nylon film are reported to be coated with PVDC resin. The
specific use areas of PVDC coated nylon film have not been fully demon-
strated.
The entire flexible packaging market is in a state of flux.
There are many products that compete on the basis of price, per-
formance, type of product to be packaged, availability, acceptance by
the consumer and compatability with a company's existing converting
and packaging equipment. Thus the choice of which film is to be used
for a given application, as well as whether the film should have a
barrier coating, is not made easily.
Many of the newer materials are replacing older ones. For
example, polypropylene and polyester are replacing cellophane. A co-
extruded polyethylene PVDC film sandwich is replacing coated polyethy-
lene, PVDC mono-layer film and glassine. Industry sources report that,
although some applications of PVDC coated film as a packaging material are
increasing, others are static or decreasing. The net result is an
average slow growth of PVDC consumption by the food and food products
packaging industry of perhaps 3 to 5% per year. The growth rate is
related to the general expansion of the economy and the change in con-
sumer eating habits in the direction of increased snack and convenience
food consumption. No new users for PVDC coated films are forseen that
will result in a sharp increase in demand.
Probable consumption in 1987 of VDCM in the production of barrier
coating polymers can be estimated to reach 45 million pounds.
4.5.2.3 Specialty Latexes
Specialty latexes are emulsion latexes that are not used as a
barrier coating on packaging films and typically, contain between 20
and 40% vinylidene chloride (dry solids basis). They are used to pro-
130
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vide fire retardant properties to the base polymer. The largest single
use of vinylidene chloride is as a comonotner with such other monomers
such as butadiene-styrene to produce a fire retardant carpet backing.
The producers of the specialty latex resins are shown in
Table 4-14. Goodrich Chemicals' Avon Lake, Ohio plant ceased production
in 1974.
TABLE 4-14. PRODUCERS OF SPECIALTY LATEX RESINS
Company Site
Dow Chemical Dalton, Ga.
Midland, Michigan
Grace Chemical Owensboro, Ky.
Reichhold Chemical Cheswold, Del.
Rohm & Haas Knoxville, Tenn.
National Starch & Chemical Corp. Meridosia, 111.
General Aniline & Film Corp. Chattanooga, Tenn.
Industry sources report about 520 million pounds per year
of latex are used as a rug and carpet backing. About 75% of this
quantity has flame retardant components built into the formulation.
131
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Flame retardancy can be built into the butadiene-styrene co-
polymer by the use of alumina, PVDC or a mixture of these materials.
Approximately 10% of flame retardant carpet backing contains some PVDC.
Based on an average VDC content of 30% and a solids content in the
latex as sold of 50%, it is estimated that about 6 to 8 million pounds
of VDC monomer are consumed for use in flame retardant carpet backing.
If all of the fire retardant carpet backing market used PVDC exclusive-
ly, VDC sales could approach 80 million pounds, a ten-fold increase.
Industry experts believe that the chance of reaching this level of de-
mand for VDC within the next 10 years is remote. The growth of this
market is not expected to exceed the general expansion rate of the U.S.
economy. However, growth in the direction of PVDC capturing a greater
share of the flame retardant rug backing market could occur if the
cost of alumina compared to that of VDC increased and a more favorable
cost effectiveness ratio resulted. Another boost to the use of VDC
would develop if more stringent federal regulations concerning fire
retardancy in rugs and carpets are promulgated, particularly for con-
sumer market applications.
One company that produced VDC-containing carpet backing polym-
ers reports that it has closed one of its two plants within the past
year. One reason given was, that based on the current polymerization
process and its pollution control technology, a further reduction of
VDC emissions would have required excessive capital expenditures in
the range of $500,000 to $1 million. This when combined with the high
price and low demand of VDC-containing polymers compared to alumina
filled products would have made the operation unprofitable. The com-
pany is now producing a flame retardant rug backing at this plant using
alternate methods and materials and will continue to do so until the
raw material cost becomes more favorable for VDC.
4.5.2.4 Textile Fibers
The textile fiber market is composed of two types: the ex-
truded monofilament, and the modacrylic fiber.
132
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Extruded Monofilaments
The extruded monofilament is manufactured by one company,
Amtek Company of Odenton, Md. A solid PVDC resin similar to that used
to extrude PVDC film is used in its manufacture. The market for this
specialty fiber is small and relatively static. According to industry
spokesmen, the demand is tending to contract chiefly because of high
cost relative to other polymers such, as polypropylene. Most is used
in the chemical industry for filter cloths. It also finds some use
where a flame retardant fiber is required combined with good outdoor
aging properties.
Losses of VDC monomer at the extrusion plant are of the same
order as those experienced by the film extrusion industry-less than 20
pounds per million pounds of product.
Production of this type fiber is estimated to consume 3 million
pounds of VDC per year and a maximum of 100 pounds of VDC monomer per
year are emitted during extrusion.
Modacrylic Fibers
The modacrylics are a modified acrylic fiber which are manu-
factured because of their flame retardant character. They are sold
under the trade names of VEREL (Tennessee Eastman), and ACRILAN (Mon-
santo). These fibers are made by copolymerizing between 10 and 30%
VDC monomer with acrylonitrile. They have been marketed for a number
of years to satisfy the demand for non-flammable fabrics, mostly sleep-
wear, draperies and automobile upholstery.
Growth of the modacrylic market has been impeded by several
factors. There has been slow development of mandatory government regu-
lations concerning flame retardant undershirts, childrens1 sleepwear,
etc., and textiles produced with modacrylic fibers do not have a good
"hand", do not dye well, and generally cost more. These fibers pro-
cess poorly compared to other textile fibers.
133
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There are two commercial developments that could restrict
further the expansion of the modacrylic market. These include the
use of flame retardant finishes on other fibers, such as Decloran,
and the development of flame resistance in such other fibers as nylon
and polyester. It is the consensus of industry spokesmen that sales
growth of modacrylics will be slow. A possible increase in demand
for the modacrylic fibers could develop if the flame retardant "Tris"
(Tris 2,3-dibromopropyl phosphate TBPP) is removed from the market
place because of its suspected carcinogenic potential. However, the
current situation is such that given a choice between the deficiences
of modacrylic fabrics, other flame retardant coated fibers, and no
flame retardant quality, the consumer will choose the fabric that is
(a) less expensive, and (b) more pleasing to the touch and eye.
Estimated U.S. consumption of modacrylic fibers is given in
Table 4-15. In addition, there is some exportation of these fibers
(chiefly to Canada) that represents about 15% of the U.S. consumption.
Industry sources conclude that neither more stringent federal
regulations concerning flame retardancy for wearing apparel nor im-
provement in the physical characteristics of the fiber will material-
ize within the next five years. Hence, growth rate will be slow to
moderate (perhaps 5 to 8% per year) with some surges due to changes
in fashion (e.g. reintroduction of pile fabrics).
TABLE 4-15. U.S. CONSUMPTION OF MODACRYLIC FIBERS
(Industry Sources, 1976)
Millions of Pounds
1971 1973 1976
Modacrylic Fiber Consumption 40 60 40-50
VDC Consumption 8 12 8-10
(based on 20% VDC content)
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4.6 TRANSPORTATION AND HANDLING OF POLYVINYLIDENE
CHLORIDE 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)
4.6.1 Transportation and Handling of Polyvinylidene Chloride
Because polyvinylidene chloride polymers are inherent-
ly flame-resistant, they are not considered hazardous for trans-
portation and handling purposes. In the past, the amount of VDC
monomer present in the final manufactured polymer might have re-
presented a possible hazard. It has however become practice for
most polymer manufacturers to strip their final product to the
extent possible to remove residual VDC. Consequently, their cus-
tomers, who are fabricators, have few problems with respect to
VDC monomer in their facilities (Milgrom, 1976).
Polyvinylidene chloride is transported in drums, tank
wagons or rail tank cars, and handled in a manner similar to other
polymer latexes. According to the U.S. Coast Guard (1974) manual
"all commercial latexes are shipped in a variety of concentrations
in water depending on the particular polymer involved and the in-
tended use of the latex. None are particularly hazardous ex-
cept in fires where all coagulate to gummy flammable material."
Because fires always constitute a hazard around chemicals, nor-
mal fire prevention measures should be taken. One of the pro-
ducts of PVDC incineration is phosgene. Therefore protective
respiratory equipment and clothing may be needed in fighting a
PVDC fire. Cooling water sprays can be used to wash down a small
spill but major spills should be diverted from sewers and clean-
ed up with suitable disposal methods.
4.6.2 Transportation and Handling of (1,1,1-Trichloroethane)
(Methyl Chloroform)
The Manufacturing Chemists Association (1976) in its
Chemical Safety Data Sheet on methyl chloroform states that:
"....although it is one of the least toxic of the chlorinated
hydrocarbons, 1,1,1-trichloroethane vapors, in low concentrations,
have anesthetic effects, and in high concentrations can have more
serious results."
135
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Reported cases (Kleinfeld and Feiner, 1966) of fatal con-
centrations of 1,1,1-TCE attained in confined spaces indicate that
skilled management practices for handling and transportating the
chemical must be followed.
4.6.2.1 Mandatory Regulations
Recent changes by the Materials Transportation Bureau,
Department of Transportation, have resulted in the addition of
1,1,1-TCE to their Hazardous Material Table. Unlike vinylidene
chloride, however, it is subject to packing regulations for air
shipment only. A summation of these rules can be found in Table
4-16.
1,1,1-TCE is also regulated by the International Air
Transport Association.
4.6.2.2 Voluntary Regulations
American Conference of Governmental Industrial Hygienists
The Threshold Limit Value (TLV) for 1,1,1-TCE set by the
ACGIH in 1963 is 350 ppm or 1.93 mg/1 (Stokinger, 1963). The TLV
indicates the safe level of the solvent vapor if it is inhaled over
a period of eight hours daily, five days/week. Patty, (1963) has
recommended a TLV of 500 ppm, but according to Aviado, et al. (1976)
an unacclimated person can detect 100 ppm and there is mild irration
due to low concentrations. There seems to be no reason to change
the TLV of 350 ppm.
American Industrial Hygiene Association (Toxicology Committee)
The American Industrial Hygiene Association (1964) pub-
lishes an evaluation of emergency exposure limits for various sub-
stances. The emergency exposure limits represent peak values of
times exposure that should not be exceeded. The values for 1,1,1-TCE
are as follows:
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TABLE 4-16 RULES AND. REGULATIONS FOR TRANSPORTING
1,1.1-TRICHLOROETHANE
(Department of Transportation, 1976)
Proper Shipping Name: Methyl Chloroform
Hazard Class: Other Regulated Material-A (ORM-A)
173.500(a)(1) Defines an ORM-A as a material which has an anesthetic,
irritating, noxious, toxic, or other similar property
and which can cause extreme annoyance or discomfort
to passengers and crew in the event of leakage during
transportation.
Labeling Requirements
172.101 No labeling is required.
172.316 The ORM-A designation must be placed on at least one
side.
Packaging Requirements
173.505(1) Governs limited quantities of ORM materials and limits
an ORM-A liquid to 1 pint/package.
173.510(a) Governs large quantities (general requirements for ORM
materials).
(1) Each material must be offered for transportation
and transported in compliance with Subpart B, C,
and D of Part 172 of this subchapter and sub-
part A of Part 173.
(2) For packagings of 110 gallon capacity or less,
sufficient outage (ullage) must be provided so
the packaging will not be liquid full at 130°F.
(55° C.).
(3) When a liquid or solid has an absolute vapor pre-
ssure exceeding 16 p.s.i. at 100°F. (38° C.), the
primary packaging must be capable of withstanding
the inside vapor pressure at 130°F. without leak-
age.
(4) Any material classed as an ORM material, which may
cause a hazard in transportation due to its re-
action with water, must be packaged with either
an inner or outer water proof packaging.
173.605(a) Specific requirements for 1,1,1-Trichloroethane (Methyl
Chloroform) when offered for transportation on a passenger-
carrying aircraft.
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TABLE 4-16 RULES. AND. REGULATIONS FOR TRANSPORTING 1.1,1-TRICHLOROETHANE
(Continued)
(1) Wooden box with inside earthenware, glass, metal,
or plastic packagings of not more than 2 gallons
capacity each, with sufficient cushioning and ab-
sorbent material to prevent breakage and leakage.
(2) Fiberboard box with inside earthenware, glass,
metal, or plastic packagings of not more than 1
gallon capacity each, with sufficient cushioning
and absorbent material to prevent breakage and
leakage.
(3) Metal drum of not more than 10 gallons capacity.
(4) Outside packaging with inside earthenware, glass,
plastic, or metal packagings of not more than 4
fluid ounces capacity each, with sufficient cush-
ioning and absorbent material to prevent break-
age and leakage. The maximum amount that may be
shipped in any one outside packaging is 5 gallons.
Maximum Net Quantity in One Package
Passenger Carrying Aircraft 10 gallons
Cargo Only Aircraft 55 gallons
138
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Concentration Emergency exposure
ppm mg/1 limits, minutes
2500 13.500 5
2000 10.800 15
2000 10.800 30
1000 5.400 60
National Fire Protection Association
The National Fire Protection Association's fire hazard
rating system has been described in Section 3.6.2. No fire or
reactivity ratings are given for methyl chloroform, but a health
hazard rating of two has been reported (Manufacturing Chemists'
Association, 1972).
4.6.2.3 Handling Procedures and Hazards
Because of its relatively low toxicity, there may be
a tendency for workers handling 1,1,1-TCE to regard it as com-
pletely safe, use it to excess or ignore spillage. The follow-
ing points should be considered in training employees in the pro-
per handling of this chemical.
Instructions for reporting to the proper medical auth-
ority and equipment supervisor should be detailed to the worker.
Sound manufacturing plant management requires that workers be
warned of unnecessary vapor inhalation and direct contact with
liquid 1,1,1-TCfc. Though they are not considered ser-
ious, various side effects may result from .1,1,1-TCE
contact. These include (1) dermatitis, caused by prolonged
daily contact, (2) eye irritation when splashed by the chemical,
(3) sickness from ingesting large amounts of the liquid.
When conditions are sufficiently hazardous to require
personal protective equipment these may take the following forms
(Manufacturing Chemists' Association, 1976):
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Eye protection Goggles or face shields
Respiratory protection: Self-contained breathing ap-
paratus, airline masks, in-
dustrial canister-type gas
masks, chemical cartridge
respirators.
Head protection: Hard hats or soft caps
Foot protection: Safety shoes made of leather;
overshoes made of neoprene may
be worn over the leather safety
shoes.
Body protection: Wash thoroughly after any ex-
posure. Protective clothing
made of polyvinyl alcohol or
neoprene.
One of the most hazardous operations involving the
handling of 1,1,1-TCE is the cleaning and repairing of tanks
and equipment. Tanks, equipment, pumps, lines and valves should
always be drained and thoroughly flushed with water before being
repaired. Electrical connections should be disconnected and the
tank steamed to remove residual TCE and its vapors. Steam lines
should be large enough to raise the tank temperature above the
boiling point (74° C) of 1,1,1-TCE. The vapors in the
steam effluent should be controlled so as to avoid air contamina-
tion in the work area in excess of the threshold limit value (350
ppm). The tank can then be cooled by filling with water and drain-
ing once or twice.
Tanks which have been steamed and flushed with water
should then be purged with fresh air.
4.6.2.4 Transportation Methods
1,1,1-Trichloroethane can be shipped in drums, rail
tank cars, or tank wagons (Lowenheim and Moran, 1975). Examples
of usual shipping containers are presented below (PPG, 1968).
DRUMS
54-Gallon at 77°F Drum - Lithographed
140
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Steel, DOT 17E, 55 gallons, 2" and 3/4" bungs in head
diametrically opposite; two rolling hoops; phosphatized interior;
green and white lithographed exterior.
54-Gallon at 77°F Drum - Black
Steel, DOT 17E, 55 gallons, 2" and 3/4" bungs in head
diametrically opposite; two rolling hoops; phosphatized interior;
black enameled exterior. Carload orders for drums can be loaded
in DF Hydro-Cushion cars where the maximum load is approximately
100 drums in 50' car. For tank wagons, maximum load is approxi-
mately 65 drums.
RAIL TANK CARS
Single Compartment
Filled Net Maximum
Car Size
4,
8,
10,
20,
000
000
000
000
gal.
gal.
gal.
gal.
Weight
22 Tons
43
54
105
Length
35'
41'
41'
48'
9"
on
2"
5"
Height
12
14
14'
15'
' 1"
' 0"
7-1/2"
1/2"
Width
9'
10'
10'
10'
9"
6-1/2
7-1/2
6-1/2
ii
ii
n
Multiple Compartment
In addition to the single unit cars, there are compart-
mented cars available: a two compartment, 6,000 gallon car (3,000
gallons each), and a three compartment, 8,000 gallon car (2,700
gallons each). Each compartment has its own dome, internal valve,
and outlet.
Tank Wagons
"Dedicated service" tank wagons are available in stain-
less steel or aluminum. For low-stabilized grade, stainless steel
only. They can be equipped with pump, hose, or nozzles.
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Maximum Load Limit
Bulk shipments are governed by local weight restric-
tions and available equipment.
The manufacturer and the shipper should be consulted
for details on proper unloading procedures for drums, rail tank
cars and tank wagons filled with 1,1,1-TCE.. Manufacturing
Chemists' Association (1976) has prepared a general guide for these
procedures.
4.6.2.5 Storage Methods
It is important to maintain properly ventilated areas
when storing 1,1,1-trichloroethane. Containers should not be
located near open flames, open electrical heaters or high temp-
erature operations because on exposure to high temperatures, the
vapor may decompose to toxic and corrosive substances (see Section
2.4.2). As is the case with all chemicals, storage selection
should be in accordance with local codes or authorities.
Steel is the most common construction material used
for 1,1,1-TCE storage, but in facilities where excessive moisture
occurs, resin linings or stainless steel may be preferred. In-
doors, drums of 1,1,1-TCE may be stored in a cool place with the
bung (stopper) up. Because there is a possibility water may be
sucked in through the bung, drums may be stored horizontally
outdoors. In all instances, drums should not be stored in pits,
depressions, or basements.
The Manufacturing Chemists Association (1976) recommends
the following storage procedures for 1,1,1-TCE stored in tanks. Whether
tanks are placed vertical or horizontal, they should have a top
and bottom manhold of at least 22 inches in diameter, in addition
to filling, vent and measuring device openings. A two inch or
two and one-half inch bottom outlet should be provided for use as
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a drain during clean-out operations. Vertical tanks should be
of the closed top design, with the top welded vapor-tight. Each
storage tank should have a vent to permit the escape of vapor
during filling. Vents from indoor tanks should terminate out-
doors in such a location so as not to contaminate work space air.
4.6.2.6 Accident Procedures
Although 1,1,1-TCE has no flash point or fire point,
a high energy source may ignite high concentrations of the vapor
in air (PPG,1968). Though this possibility is unlikely, if a
fire does occur, then carbon dioxide, dry chemical agents or foam
may be used to control it.
Spills should be cleaned up immediately by persons wear-
ing protective equipment. Cleaning materials wet with 1,1,1-TCE
should be placed in closed containers or dried outside. Cloth-
ing impregnated with 1,1,1-TCE should be immediately removed and
then dried out-of-doors.
4.6.2.7 Disposal Methods
Current disposal methods in common use are those es-
tablished by the Manufacturing Chemists Association (1976). They
recommend that 1,1,1-TCE contaminated discharge water be air
blown for a few hours in a well ventilated area. Limited amounts
may be poured on dry sand, earth or ashes at a safe distance
from occupied areas and allowed to evaporate into the atmosphere.
These recommendations are superceeded by any local or state reg-
ulations concerning waste disposal to streams, municipal treat-
ment plants or into the ground.
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SECTION IV. REFERENCES
American Industrial Hygiene Association, Toxicology Committee (1964),
"Emergency Exposure Limits," J. Am. Ind. Hyg. Assoc., 25, 578.
Aviado, D.M., S. Zakhari, J.A. Simaan, and A.G. Ulsamer (1976),
Methyl Chloroform and Trichloroethylene in the Environment,
CRC Press Inc., Cleveland, 15.
Chemical Marketing Reporter (1977), "Chemical Profile: 1,1,1-Tri-
chloroethane," jn.l(3), January 17, 9.
Department of Transportation (1976), "Department of Transportation,
Materials Safety Bureau, Hazardous Materials Regulations, 49
CFR Parts 171-177 (Interim Publication)," Federal Register,
41(188), September 27, 42364-42638.
Kleinfeld, M. and B. Feiner (1966), "Health Hazards Associated with
Work in Confined Spaces," J. Occup. Med., J5, 358-61.
Leahy, W.J. (1976) "High Barrier Saran Resins—Coextrusion Applica-
tion." Pages 87-102 in Symposium on Barrier Polymers and
Barrier Resins, Chemical Marketing and Economics Division,
American Chemical Society, New York, April 5-9.
Lowenheim, F.A. and M.K. Moran, editors (1975), Faith, Keyes, and
Clarke's Industrial Chemicals, 4th Edition, Wiley-Interscience,
Inc., New York.
Manufacturing Chemists' Association (1972), Guide for Safety in the
Chemical Laboratory, 2nd Edition, Van Nostrand-Reinhold, Inc.,
New York.
Manufacturing Chemists' Association (1976), "Chemical Safety Data
Sheet, SD-90, Properties and Essential Information for Safe
Handling and Use of 1,1,1-Trichloroethane," Washington, D.C.
Milgrom, J. (1976), "Vinylidene Chloride Monomer. Emission from the
Monomer, Polymer, and Polymer Processing Industries," Arthur
D. Little, Inc.
Modern Packaging (1975), "Encyclopedia," 48(12).
PPG Industries, Inc. (1968), "Tri-Ethane," Pittsburgh.
Patty, E.A., (1963), Industrial Hygiene and Toxicology
Vol. II 2nd Edition, Interscience, New York.
Stokinger, H.E., H.B. Ashe, E.J. Baier, A.L. Coleman, H.B. Elkins,
B. Grabois, W.J. Hayes, Jr., K.H. Jacobson, H.N. MacFarland,
W.F. Reindollar, R.G. Scovill, R.G. Smith, and M.R. Zavon
(1963), "Threshold Limit Values for 1963," J. Occup. Med.,
5, 491.
U.S. Coast Guard (1974), "CHRIS Hazardous Chemicals Manual, Volume
2," U.S. Coast Guard CG-446.
144
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SECTION IV. REFERENCES (CONT'D)
U.S. International Trade Commission (1975), "Synthetic Organic
Chemicals: United States Production and Sales, 1973."
U.S. International Trade Commission Pub. 728, Government
Printing Office, Washington, B.C.
U.S. International Trade Commission (1976), "Synthetic Organic
Chemicals, United States Production and Sales, 1974." U.S.
International Trade Commission Pub. 776, Government Print-
ing Office, Washington, D.C.
U.S. International Trade Commission (1977), "Synthetic Organic
Chemicals: United States Production and Sales, 1975." U.S.
International Trade Commission Pub. 804, Government Print-
ing Office, Washington, D.C.
U.S. Internation Trade Commission (1977), Preliminary data from
U.S. International Trade Commission concerning production
and sales of synthetic organic chemicals in 1976.
U.S. Tariff Commission (1968), "Synthetic Organic Chemicals:
United States Production and Sales, 1966." U.S. Tariff
Commission Pub. 248, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1969), "Synthetic Organic Chemicals:
United States Production and Sales, 1967." U.S. Tariff
Commission Pub. 295, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1970), "Synthetic Organic Chemicals:
United States Production and Sales, 1968." U.S. Tariff
Commission Pub. 327, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1971), "Synthetic Organic Chemicals:
United States Production and Sales, 1969." U.S. Tariff
Commission Pub. 412, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1972), "Synthetic Organic Chemicals:
United States Production and Sales, 1970." U.S. Tariff
Commission Pub. 479, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1973), "Synthetic Organic Chemicals:
United States Production and Sales, 1971." U.S. Tariff
Commission Pub. 614, Government Printing Office, Washington,
D.C.
U.S. Tariff Commission (1974), "Synthetic Organic Chemicals:
United States Production and Sales, 1972." U.S. Tariff
Commission Pub. 681, Government Printing Office, Washington,
D.C.
145
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SECTION V. USE ALTERNATIVES FOR VDC AND ITS END PRODUCTS
5.1 INTRODUCTION
Vinylidene1 chloride has been in extensive commercial use
since 1939, when copolymerization and plasticization techniques
were developed by workers at Dow Chemical Co. The resultant co-
polymers, known as saran or polyvinylidene chloride, have been pro-
duced continuously since that time.
Alternate raw materials and processes exist for the con-
sumption of VDC in 1,1,1-TCE manufacture, and will have completely
displaced VDC in this use by 1980.
A number of other polymers can substitute for saran in:
its applications as a packaging film or barrier coating. None,
however, possess the same barrier resistance to both oxygen and
water vapor for a given film thickness.
For the manufacture of flame retardant fibers, alternate
materials for PVDC containing polymers exist, and more are in the
developmental stages. The alternative material used as a replace-
ment for PVDC in producing a flame retardant carpet backing has
inferior physical and wearability characteristics.
146
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5.2 1,1,1-TRICHLOROETHANE
Of the three companies currently producing 1,1,1-TCE
(Dow Chemical Co., and PPG, Inc., and Vulcan), only PPG produces
it from vinylidene chloride. The other production routes are:
(1) Chlorination of vinyl chloride
(2) Direct chlorination of ethane or ethylene
The specific process used by any of the 1,1,1-TCE producers, in-
cluding PPG's hydrochlorination of vinylidene chloride, is depen-
dent upon the company's desired product mix and economics of the
overall chlorinated hydrocarbon operation.
5.2.1 Production Alternatives
In the first alternative, 1,1,1-TCE is derived from chlorin-
ation of vinyl chloride, which has been synthesized from ethylene
dichloride, in turn derived from chlorination of ethylene or ethane.
The second alternative results from the continuous non-catalytic
chlorination of ethane and produces a variety of chlorinated hydro-
carbons, including ethyl chloride, ethylene dichloride, vinyl chloride,
vinylidene chloride, and the trichloroethanes. The producer can
separate the various products and use them as is, or recycle them for
further chlorination e.g., vinyl chloride to produce 1,1,1-TCE. The
specific composition of the product ranges are considered proprietary,
and depend on the temperature, catalyst and reaction time.
Thus, neither the various raw materials nor the processes
discussed above can be considered true alternatives. The raw materials
are all interrelated and the production processes use equivalent
technology.
PPG will have phased out its 1,1,1-TCE plant using VDC by
1980 with an alternate process probably using ethylene dichloride or
vinyl chloride. Hence, "alternatives" will have replaced VDC as
the starting point for the production of 1,1,1-TCE within the next
three years.
147
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5.2.2 End Use Alternatives
The major use of 1,1,1-TCE is as a metal degreaser, in
a wide range of industrial and commercial applications. In this
regard, it is already functioning as the alternative to other sol-
vents such as trichloroethylene because it is a non-flammable and a
more chemically inert compound.
A major factor in its being the chemical of choice as a
degreasing solvent is its relative lack of reactivity in the vapor
state with atmospheric constituents. It is much less likely to
form the peroxides, smog, and other pollutants which are a frequent
by-product of the presence of unsaturated hydrocarbons in the atmos-
phere.
i
5.3 POLYMERS OF VINYLIDENE CHLORIDE
Vinylidene chloride is always used commercially with other
monomers, to produce a range of plastics with varying properties and
uses. The major comonomers used in the polymerization of VDC are
vinyl chloride, acrylic acid, methacrylic acid, acrylonitrlle, butadiene
and styrene.
5,3,1 Alternative Chemicals and Processes
The main properties, for which VDC copolymers find a market,
are barrier resistance and flame retardancy. VDC itself is the alter-
nate chemical added to the copolymer mix to achieve a desired property.
Thus, there are no alternatives to VDC for its specific applications in
polymerization.
The polymerization processes used to manufacture VDC co-
polymers are of two main types: emulsion, and suspension polymeriza-
tion. Both processes use essentially the same equipment and over-
all reactions, differing only in the reaction parameters, degree of
conversion, and stripping techniques. Suspension polymerization
148
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commonly yields a latex, but it can also be used to produce the
dry resin. Copolymerization with acrylic monomers to form mod-
acrylic fibers uses the emulsion process.
The latex suspension process is not as widely used as
the emulsion process, although some industry sources report that
the suspension process is easier to control and results in fewer
lost batches. However, the emulsion resin offers superior physical
characteristics, in that the resin particles are smaller and the
polymer extrudes and blends more easily.
The trends in alternate PVDC process technology are in
the direction of improving the characteristics of the polymer pro-
duced, increasing degree of conversion of monomer, and reducing
losses. New catalysts are being evaluated which would yield a
suspension resin with the more desirable physical characteristics
of the emulsion resin. The impetus for this new technology stems
from the higher VDC monomer losses associated with the emulsion
process, in terms of both sewered effluent from bad batches and
monomer emissions from the process.
Alternate process technology for polymerizati&n is aimed
at increasing the amount of conversion of VDC into polymer with-
out affecting the properties desired in the end product. This will
reduce the amount of VDC monomer to be removed by stripping, as well
as reducing the amount of residual monomer in the polymer.
5.3.2 End Use Alternatives
End use alternatives exist for all four major con-
sumption areas of VDC copolymers. However, all have some drawbacks,
either in terms of loss of specific desired properties in the end
product, or the cost or quantity of alternative substances that
would have to be used to achieve the same effect.
5.3.2.1 Alternatives to Saran Film
In contrast to other polymers, or copolymers of vinyl
chloride, saran copolymers require very little or no added plasticiz-
149
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er to yield.a flexible film. This characteristic is significant
since the addition of plasticizers tends to destroy the barrier
properties of the polymer films. The formulation chosen for a
saran film is always a compromise between the barrier requirements
and the physical characteristics, such as cling, clarity, machin-
ability and printability, required by the film (Leahy, 1976).
Saran's unique characteristic is its outstanding barrier
to transmission of both oxygen and water vapor. Other flexible
polymeric films may possess similar barrier properties for either
oxygen or water vapor, but not both. Table 5-1 compares oxygen and
water vapor transmission rates for common commercial packaging
films, all at 1 mil thickness and room temperature.
TABLE 5-1. TRANSMISSION RATES FOR PLASTIC FILMS
(Leahy, 1976)
Transmission Rate
Material Oxygen* Water Vapor""
Saran 1 0.2
Polyethylene 400 1
Polypropylene 245 0.5
Polyvinylchloride 25 5
Polyester 5 1.8
*units are cc/100 sq. in./day
**units are gm/100 sq. in./day
150
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From this table it can be seen that polyethylene, poly-
propylene or polyester could replace saran, depending on the part-
icular barrier properties required for a given application. Simil-
arly, increased thickness of the other films could approach the
barrier properties of the thinner saran film.
Another important alternative to the monolayer saran is
the coextruded laminate film. In these flat film structures saran
is sandwiched between polyethylene or other polyolefin skins. These
laminates have outstanding physical properties, combining the flexi-
bility, heat-sealability and low temperature properties of poly-
ethylene with the barrier resistance of saran itself. A possible
future advantage to the laminate may be that it isolates the saran
from contact with the food. Until the question of the alleged migra-
tion of VDC monomer from saran into foods has been resolved (Chemical
and Engineering News, 1977), this substitute for saran could
prove to be of even greater commercial significance.
5.3^2.2 Alternatives to Saran-Coated Substrates
Coating of cheaper substrates, such as cellophane, or
films with other desirable physical properties, such as polyethylene,
with saran brings about a dramatic barrier improvement in the pro-
perties of the original substrate. Table 5-2 compares the barrier
properties of various saran-coated and uncoated substrates.
Thus, depending on the nature of the food being
packaged and the nature of the barrier resistance required, alterna-
tives to saran-coated substrates could be selected. Again, the
coextruded saran laminate provides an attractive alternative in
terms of overall desirable physical characteristics, but it is
not cost competitive with some of the cheaper substrates.
5,3,2.3 Alternatives to PVDC Latex Rug Backings
VDC is used as a comonomer with butadiene-styrene to pro-
vide flame retardant properties to the base polymer. Flame
151
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TABLE 5-2. BARRIER PROPERTIES OF SARAN-COATED FILMS
(Roth, 1976; Modern Packaging Encyclopedia, 1975)
Transmission Rate
Material
Cellophane, Uncoated
Cellophane, Saran Coated
Polyester, Uncoated
Polyester, Saran Coated
Polypropylene, Uncoated
Polypropylene, Saran Coated
Nylon, Uncoated
Nylon, Saran Coated
Water Vapor
High
0.4
1
<.l
0.25
0.25
High
0.5
Oxygen
Variable
0.2
3
0.6
150
0.5
*gm/100 sq in/day/mil
**cc/100 sq in/day/mil
152
-------
retardancy can be built into the latex by the use of alumina, PVDC,
or a combination of these materials. Only the PVDC acts as a func-
tional additive. The VDC monomer forms part of the latex polymer
molecule and thus adds to its elastomeric character. Alumina is
heavy and when added in quantities sufficient to "quench" flame, it
produces a cracky material with poor physical and wear properties.
Other flame retardants, such as the aryl phosphates are
not suited to the latex plastics because they act as diluants, to
separate polymer chains and provide "slip", rather than being in-
corporated into the molecular structure.
The use of Dechlorane +25 and decabromobiphenyl oxide as
flame retardant melt additives for nylon carpets has also been re-
ported (Stoddard, 1975). In this application the flame retardant
material is blended into the polymer just prior to yarn formation,
rather than formulated with the backing material.
5.3.2.4 Alternatives to Modacrylic Fibers
Modacrylic fibers are manufactured for the market for
non-flammable fabrics, mainly sleepwear, draperies and automobile
upholstery. Alternatives to the modacrylics include the use of
flame retardant finishes on other fibers, such as Dechlorane. Work
is also being done in the development of flame' resistance in other
fibers which currently enjoy greater popularity in the consumer
market, such as nylon and polyester.
153
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SECTION V. REFERENCES
Chem. Eng. News (1977), "Vinylidene Chloride: No Trace of Cancer at
Dow," 55/11), 21-2.
Leahy, W.J. (1976), "High Barrier Saran Resins—Coextrussion Applica-
tions." Pages 87-102 in Symposium on Barrier Polymers and Barrier
Resins, Chemical Marketing and Economics Division, American
Chemical Society, New York, April 5-9.
Modern Packaging (1975), "Encyclopedia," 48(12), 32-4.
Roth, S.F. (1976), "Saran Coatings—Latex or Lacquer?" Pages 29-36 in
Symposium on Barrier Polymers and Barrier Resins, Chemical Market-
ing and Economics Division, American Chemical Society, New York,
April 5-9.
Stoddard, J.W., O.A. Pickett, C.J. Cicero, and J.H. Saunders (1975),
"Flame-Retarded Nylon Carpets," Text. Res. J., 45, 474-83.
154
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SECTION VI. OVERALL MATERIALS BALANCE
6.0 OVERALL MATERIALS BALANCE
Vinylidene chloride is manufactured chiefly by the de-
hydrochlorination of 1,1,2-trichloroethane, or as a co-product of
the reaction of ethane and ethylene with chlorine. It is not ob-
tained from natural sources, nor is it accidentally produced in a
natural environment.
Vinylidene chloride is consumed by
(1) Further chemical reaction to form other chemicals
(2) Polymerization with other monomers to form long
chain thermoplastic polymeric materials.
During the production of Vinylidene chloride, and in its
conversion to other chemicals or polymers, there are losses of VDC
to the environment as well as residual monomer remaining in the
products derived from it.
155
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Figure 6-1 is a flow diagram tracing the Input-Output
balance of vinylidene chloride monomer from its manufacture through
its consumption in various products to its conversion into end use
materials-
6.1 VINYLIDENE CHLORIDE MANUFACTURE
Approximately 270 million pounds of vinylidene chloride
were produced in 1976. Of this, estimated losses to the environ-
ment were calculated to be 550,000 Ibs.
Of the balance, 130 million pounds were reported to be
reacted to produce 1,1,1-trichloroethane; an estimated 5 million
pounds were converted to a chemical intermediate, chloroacetyl chloride;
the balance was co-polymerized with other monomers to produce VDC -
containing polymers.
Figure 6-2 represents the output of VDC according to the
percent consumed or lost.
6.2 VINYLIDENE CHLORIDE CONSUMPTION
6.2.1 VDC Consumption in Manufacture of 1,1,1-Trichloroethane
According to PPG, the sole manufacturer of 1,1,1-TCE from
VDCj the conversion of VDC to 1,1,1-TCE is 100%, with no process
losses of VD_C to the environment occurring. There is some con-
tamination of the 1,1,1-TCE produced with VDC monomer. This is re-
ported to be about 100 ppm or about 17,500 Ibs. per year.
The loss of this amount of VDC occurs at the very large
number of sites where 1,1,1-TCE is used. It probably is lost chiefly
by vaporization of 1,1,1-TCE during its transfer, use and recovery.
6.2.2 VDC Consumption in Manufacture of Chloroacetyl Chloride
This chemical is manufactured for captive use by Dow
Chemical Co. They report no losses of VDC to the environment during
156
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VINYLIDENE
CHLORIDE
MANUFACTURE
0.55 MM (M)
272 MM (M)
M = MONOMER
P = POLYMER
A = AIR EMISSIONS
W = WATER EMISSIONS
S = SOLID SCRAP
* = RESIDUAL VDC CONTENT IN PRODUCT
** = NOT AVAILABLE
MM = MILLIONS OF POUNDS
ALL FIGURES IN LBS/YR OF VDC
136.45 MM (M)
130 MM (M) . I . ._^_,
R
8.16 MM (M) 110.9 'MM (M) 17.5 MM (M)
1,1,1-TRI- PVDC
CHLOROETHANE - A 0 MM (M) ^nr^Arcv "A °'112 m (M) EMULSION/ _A 0-56 M^ (M) MODACRYL
MANUFACTURE PVDC LATEX SUSPENSION FIBE
LA 1 t X
1 10 LBS (M) 1 0.004 MM (M) |_
W 0.15 MM (P) W 7.8 MM (P)
0.018 MM* RUG BACKING, 0.003 MM (M) 17 LBS (
ADHESIVES 102.6 MM (P) 17.5 MM (
100 LBS (M)
7.9 MM (P)
V
MM (M)
IC -A 100 LBS (M) CHEMICAL _A Q m (M)
INTERMEDIATE
. w **
M) o
P)
\
MM
/
(M)*
1200 LBS (M) 1100 LBS (M)
61 MM (P) 21.5 MM (P)
i i
IMPORT 35MMLBS (p) ^ PVDC RESIN
1350 LBS (M) 11
64 MM (P) - 2]
W
360 LBS (M) 840 LBS (M) 60 LBS (M) 20 LBS (M) 700 LBS (M)
18 MM (P) 42 MM (P) 3 MM (P) 1 MM (P) 13.5 MM (P)
1 I i I i
SOLVENT COATED
COATING pVDC FI,M pJnrUDED EXTRUDED, PAPER
CELLO- FIBER MOLDED PVDC PRODUCTS,
PHANE, ETC, • GLASSINE
LA 320 LBS (M) LA 716 LBS (M) LA 45 LBS (M) L A 15 LBS (M) LA 570 LBS
s 10 T.RS (M) 1 74 T,BS (M) I n 30 T.R
w ° 4.5 MM (P) ^ b 7.8 MM (P) f 2.7 Ml
^ 30 LBS (M) 100 LBS (M) 15 LBS (M) 5 LBS (M) 100 LBS (M)
\^13.5 MM (P) 34.2 MM (P) 3 MM (P) 1 MM (P) 10.8 MM (P)
PVDC
COATING
LATEX
00 LBS (M)
.5 MM (P)
X
400 LBS (M)
8 MM (P)
COATED
PLASTIC
FILM
(M) LA 370 LBS (M)
S (M) 1 6 LBS (M)
M (P) ^ 1.6 MM (P)
25 LBS (M)
6.4 MM (P)
EXPORT
\
0.00
20
i
2 (M) /
(P) ^/
PVDC PRODUCTS AS MARKETED
FIGURE 6-1, VINYLIDENE CHLORIDE INPUT-OUTPUT FLOW DIAGRAM
-------
50% CONSUMED
IN POLYMER
MANUFACTURE
1.8% CONVERTED TO
CHLOROACETYL CHLORIDE
0.2% EMISSION LOSS
DURING MANUFACTURE
FIGUE 6-2, PERCENTAGE DISTRIBUTION OF VDC OUTPUT
158
-------
manufacture, and no contamination of the purified product that is
used as an intermediate for further chemical reactions.
6.2.3 VDC Consumption in Polymerization
Many types of copolymers are produced in the United States,
Approximately 70 percent of all VDC-containing polymers manufactured
are produced by one company. The balance are manufactured by about
12 companies.
The copolymers fall into the following groups:
(1) Resins for manufacture of saran films
(2) Resins for molding and extrusion
(3) Resins for solvent coating of cellophane
and similar products
(4) Latexes for barrier coating of paper, paper
products, glassine and plastic film
(5) Latexes for carpet backing
(6) Modacrylic fiber production
(7) Exported products
In the polymerization process that reacts VDC monomer,
substantially all the VDC monomer is converted to polymers. There
are environmental losses to the air, water and landfills as well
as some contamination of the polymer products.
The majority of losses to the atmosphere occur during
the polymerization process. These were calculated to be about
560,000 pounds in 1976.
The liquid and solid waste losses of VDC monomer re-
sult from the sewering of bad polymer batches or cleaning of polymer
reactors and storage vessels. In these instances, the monomer VDC
is present as a contaminant of the polymer.
159
-------
Industry sources indicate that the domestic total of these
losses of VDC amount to perhaps 3,600 to 4,000 pounds per year.
VDC input to polymerization processes has been estimated
to be 135 million pounds in 1976, divided into the following end
use categories:
VDC INPUT
MILLIONS OF LBS.
Resins for Saran Film 37.7
Resins for Molding & Extrusion 4.8
Resins for Solvent Coating 19.2
Latexes for Barrier Coatings 33.2
Latexes for Carpet Backing & Miscellaneous
Applications 8.6
Modacrylic Fiber 10.0
Export 21.8
TOTAL 135.3
The data presented represents the input of VDC monomer
to polymerization processes. Process losses to the environment
and waste polymers have been prorated among the various end use
categories.
VDC output from polymerization processes in each end
use category would be somewhat smaller as discussed in Section 6.3.
6.2.4 VDC Output From Polymerization Process
The VDC output from polymerization processes comprise
essentially direct atmospheric losses plus VDC contamination of
polymeric materials that are sold, sewered or disposed into land
fills. The direct atmospheric losses have been estimated to be
560,000 pounds per year.
PVDC polymerization products are contaminated with
between 10 and 75 ppm VDC monomer depending on the type of polymer.
160
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Resins for manufacture of films', solvent coatingt
molding and extrusion processes are reported by the manufacturers
to contain a maximum of 20 ppm monomer as sold. This would amount
to about 1,100 pounds per year, based on resin sales of 57.5 million
pounds in 1976.
Latexes for barrier coatings using present technology
contain about 50 ppm of monomer. Based on 1976 estimated sales
of barrier coatings containing 30.88 million pounds of PVDC, these
barrier latexes are estimated to contain 1,544 pounds VDC monomer.
Specialty latexes are reported to contain 13 pounds of
VDCM per million pounds of PVDC. Based on an 8 million pound
PVDC content of these latexes, the residual monomer would not ex-
ceed about 100 pounds annually.
It is estimated that about 7.8 million pounds of PVDC
are sewered as a waste of polymerization processes. These wastes
contain an estimated 3,600 to 4,000 pounds of VDC monomer.
The total VDC output from polymerization operations is
thus that lost to the environment as a result of polymerization pro-
cesses, and that contained as a contaminant in the finished polymer
latexes or resins.
Approximately 566,500 Ibs of VDC, out of a total input
of 135 million pounds, remain unconverted from polymerization pro-
cesses. This is equivalent to 99.6% utilization of VDC monomer in
the polymerization operations.
6.2.5 VDC Input/Output in Converting Processes
Converting processes include coating of paper, glassine
and paper products; coating of cellophane and plastic films; ex-
trusion of films and monofilament fibers, and molding operations.
161
-------
VDC input to this sector consists of the residual VDC
monomer content of the latex or resin used in these operations.
In the previous section this was calculated to be about 2,700 pounds.
Industry sources indicate that about 95% (or 2,500 Ibs.)
was lost to the atmosphere during converting operations.
On this basis, some 200 pounds of VDC monomer remains in
the approximately 125 million pounds (PVDC content) of film or
coated products produced by the many converting companies in the
United States. This is equivalent to 1.6 ppm VDCM in the PVDC con-
tent of the copolymers consumned.
6.3 POLYVINYLIDENE CHLORIDE INPUT/OUTPUT SUMMARY
In section 6.2.3, it was shown that about 135 million
pounds of VDC monomer were fed into polymer production facilities.
Approximately 125 million pounds of PVDC-containing polymer were
sold for the uses indicated. The balance was lost in the form of
monomer vented to the air or in copolymers sent to sewerage ponds or
land fills. Industry sources reported that of the 135 million
pounds of VDC input, about 560,000 pounds were lost directly to
the atmosphere and 7.8 million pounds* lost as solid or latex emul-
sion going to sewerage ponds or land fills.
Table 4-1 on page 92 summarizes the end uses of the 125
million pounds that are consumed in various converting and food
packaging operations, as a flame retardant carpet backing and as
a modacrylic fiber.
In addition to the PVDC manufactured in the U.S., it is
reported that about 3 million pounds of resin are imported annually
from Japan bringing total U.S. consumption to about 128 million
pounds in 1976.
*VDC lost as monomer or in polymerized form.
162
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Converting processes usually refer to those processes
in which a flexible material is "converted" into the finished
package. These operations are notoriously wasteful of material.
Between 25 and 50% of the input packaging materials are normally
lost and disposed in land fills or incinerators.
Taking an average of 25% converting loss on all PVDC
or PVDC-containing materials manufactured and consumed in the
U.S., then about 26 million pounds out of 105 million* are wasted
at the converting level and only about 79 million pounds of PVDC
containing materials enter the end^use sectors where there is con-
sumer contact. These 79 million pounds of PVDC materials
are estimated to contain less than 200 pounds of VDC monomer
(2.5 ppm).
*Excludes 20 million pounds exported
163
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SECTION VII. SUMMARY OF CHEMICAL LOSSES
This section will discuss briefly losses of VDC monomer
to the atmosphere, to water streams or to solid waste disposal opera-
tions. PVDC losses will not be considered in this section except
for those cases where it is a carrier of residual VDC monomer. The
losses are summarized in Table 7-1.
7.1 AIR EMISSIONS
VDC emissions to the atmosphere occur from the following
sources:
(1) Manufacture of VDC
(2) As a residual in 1,1,1-TCE manufactured
from VDC
(3) Polymerization operations
(4) Polymer conversion operations
(5) Migration of residual VDC from polymer
products
These losses have been estimated and shown in Table
7-1 and for 1975, they have been calculated to be 1,132,920 Ibs.
164
-------
TABLE 7-1. SUMMARY OF ENVIRONMENTAL LOSSES. 1975
VDC,lbs./yr.
Air Water Solid
Monomer Production 550,000 0 0
1,1,1-TCE Production 17,500 0 0
Chemical Intermediate
Production 000
Polymerization - Total 560,000 4,100 0
Converting Plants 2,500 0 180
Barrier Coating 2,000 0 0
Cellophane Coating 320 0 0
Film Extrusion 200 0 0
Rug Backing 200 10 0
Modacrylic 200 0 • 0
TOTAL 1,132,920 4,100 180
165
-------
It is believed that the quantity in 1976 has remained at about this
level, or decreased slightly. By 1978, this quantity should be
reduced by about 150,000 pounds when PPG starts operation of a new
1,1,1-TCE plant that does not use VDC as the raw material. Accord-
ing to industry reports, some continued technology improvements can
be expected in reducing emissions in both manufacturing and poly-
merization operations. However, these reductions are not expected
to be more than 10 to 20% without the expenditure of substantial
quantities of capital.
It is believed that technological developments leading to
further reduction of residual VDC monomer in polymer products to
substantially below the current 50 ppm in latexes and 10 ppm in
resins can only be achieved by very substantial capital investments.
98% of the VDC monomer contained in latexes or resins is released
during converting operations. Based on current technology, this
amounts to about 2,000 pounds annually.
The total monomer residual in finished products as they
reach the consumer is estimated to be on the order of 300 to 400 Ibs.
per year, or less than 3 ppm. In some instances, as with
saran films or saran coated cellophane, these levels have been re-
ported to be less than 1 ppm.
This quantity of monomer would be released very slowly.
The rate of release is a function of the rate of migration through the
polymer. It is believed that the rate is so slow, that the bulk of
the residual VDCM in the converted product remains with the product
and is disposed along with the polymer to solid waste disposal systems.
7.2 SOLID WASTE DISPOSAL
The amount of VDC monomer lost in solid form is limited
to the small residual quantities of monomer remaining in the polymeric
products that are manufactured and sold as "converted" materials.
These includes
166
-------
(1) Saran film and film laminates
(2) Saran coated paper and paper products
(3) Saran coated plastic film products
(4) VDC copolymers used as carpet backing
(5) Molded and extruded saran products other than film
(6) Modacrylic fibers
Based on information supplied by industry sources, residual
VDC monomer in these converted products as manufactured ranges from
below 1 ppm to 3 ppm. If for purposes of this study, an average
value of 1.5 ppm is used, and the entire quantity of VDC polymerized
is assumed to be disposed in municipal solid waste disposal opera-
tions, then the maximum potential quantity of VDC monomer contained
in solid wastes would be of the order on 1.5 ppm x 120 million
pounds or 180 pounds per year for 1975/1976.
Some industry estimates have been reported as high as
220 pounds.
Industry sources indicate there is no evidence to show
that monomer VDC accumulates in the environment. Rather, on exposure
to oxygen, it tends to form peroxides which decompose spontaneously
(Gay, et al., 1976).
7.3 LIQUID EFFLUENT EMISSIONS
Liquid effluent containing VDC monomer is limited to that
occurring as a result of polymerization operations. This consists
of:
(1) VDC monomer contained in waste polymer sludges
arising from reactor cleaning and bad batches.
(2) VDC monomer dissolved in condensed water streams
obtained by condensation of gases obtained during
stripping operations.
167
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The amount of this has been reported to be between 375 and
430 ppm of PVDC wasted. The amount of PVDC sent to latex ponds,
sludge sewers or plant liquid waste disposal systems has been esti-
mated to be in 1975, about 7.0 million pounds and in 1976, about
7.4 million pounds.
Based on these data, it is estimated that between 2,600
and 3,000 pounds per year of VDC monomer are lost in liquid waste
streams.
Substantially all of this loss is either bio-degraded in
the chemical waste disposal units or diffuses into the atmosphere
where it is oxidized.
7.4 POTENTIAL FOR INADVERTENT PRODUCTION IN INDUSTRIAL PROCESSES
VDC monomer, as has been discussed in Section III, can be
produced as a co-product (by-product) during the chlorination, hy-
dro chlorination or dehydrochlorination of ethane, ethylene or acety-
lene, or any of their chlorinated derivatives. Except for those
processes in which VDC is removed from the product stream and re-
covered for its economic value, current manufacturing procedures re-
cycle the intermediate chlorinated ethanes, ethylenes or acetylenes
(such as VDC) for further reaction into the desired chlorinated
chemical.
The potential for this to occur as part of an overall re-
action process is not insignificant. However, the potential for this
product to remain as a contaminant of the final chlorinated chemical
that is recovered for further use or for sale is believed to be very
unlikely. Should it occur, as in the case of 1,1,1-TCE manufactured
from VDC, it would not be present beyond an order of magnitude of a
few ppm as a maximum.
168
-------
There does not seem to be any likelihood for producing
VDC in the environment. It is synthesized under conditions of tempera-
ture, pressure and catalyst from ethylene dichloride in a complex
series of reaction steps which can include the formation of vinyl
chloride. The alternate method is the dehydrochlorination of 1,1,2-
trichloroethane in the presence of an alkali. None of these chemi-
cals occur naturally in the environment in contact with chlorine or
hydrogen chloride under conditions that would cause them to react
to form VDC.
7.5 SUMMARY OF GENERAL ENVIRONMENTAL POLLUTION BY VDC
VDC emissions and losses in 1975 from all sources amount
to approximately 1,132,920 Ibs; of this, an estimated 99+7« enters
atmosphere.
It is estimated that perhaps 3,000 pounds annually could
enter the environment as a liquid effluent and a probable maximum
of 200 to 300 pounds per year are disposed as a component of solid
waste materials.
Approximately 550,000 Ibs. of VDC are vented to the air
by three manufacturing sites. An additional 568,000 Ibs. of VDC
enter the atmosphere from 13 polymerization sites.
The bulk of liquid effluent VDC monomer contamination
occurs at the 13 polymerization sites.
Negligible environmental pollution of the environment
occurs from conversion operations or from ultimate disposal of the
final packaging materials products.
7.6 SUMMARY OF OTHER CHEMICALS RELEASED TO THE ENVIRONMENT
By-products or co-product chemicals that could be re-
leased to the environment during the manufacture of VDC can include
169
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other chlorinated hydrocarbons such as ethylene dichloride, hydrogen
chloride.
In processes that use VDC as a raw material to produce
other chlorinated hydrocarbons such as 1,1,1-TCE, and chloroacetyl-
chloride, it is conceivable that these chemicals could also be re-
leased to the environment.
The comonomers of VDC could be released jointly with VDC
from polymerization and conversion processes.
The bulk of VDC copolymers contain 70 to 95% VDC, the
balance comprised of such monomers as vinyl acetate, acrylonitrile,
acrylic and methacrylic acids. These comonomers can also be emitt-
ed together with VDC during polymerization processing. However,
because they are present in the monomer mixture in lesser quantities,
it is unlikely that they would be present in significant quantities
in polymerization wastes (air, liquid or solid).
170
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SECTION VII. REFERENCES
Gay, B.W., P.L. Hanst, J.J. Bufalini, and R.C. Noonan (1976), "Atmospheric
Oxidation of Chlorinated Ethylenes," Environ. Sci. Tech., 1£(1), 58-67,
171
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA 560/6-77-033
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Market Input/Output Studies
Task I
Vinylidene Chloride
s. REPORT DATE
October 1977
6. PERFORMING ORGANIZATION COOE
7. AUTHOR(S)
M. Lynne Neufeld, Marcus Sittenfield (Marcus Sittenfield
and Associates), Kathryn F. Wolk and Robert E. Boyd
8. PERFORMING ORGANIZATION REPORT NO.
AAI 2378/2379-101-FR-l
9. PERFORMING ORGANIZATION NAME ANO ADDRESS
AUERBACH Associates, Inc. (AAI)
121 North Broad Street
Philadelphia; Pa. 19107
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
EPA 68-01-1996
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Toxic Substances
U.S. Environmental Protection Agency
Washington, B.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Recent reports of the possible carcinogenic properties of
vinylidene chloride, because of structural similarity to vinyl chloride,
prompted this investigation. This report views the chemical and
physical properties of vinylidene chloride (VDC) and its important derivitives and
polymers. A detailed discussion of the manufacturing process, including sites, new
technologies and environmental management is presented. The consumption of VDC
in the manufacture of methyl "chloroform and alternative manufacturing processes
for methyl chloroform which do not involve VDC are discussed. The most important
end use of VDC, polymerization, is described in detail. A cost performance analysis
of copolymers containing VDC, VDC laminated films, multilayer "PVDC sandwich"
type films and other films not containing VDC such as .polyethylene and polyproplene
is reported. Finally a summary of the chemical losses due to air emissions, liquid
effluents and solid wastes is discussed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lOENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Vinylidene Chloride
Polyvinylidene Chloride
Chemical Marketing Information
Saran
1,1,1-Trichloroethane
Pollution
Environmental Fate
Polymers
18. DISTRIBUTION STATEMENT
Document is available to the public through
the National Technical Information Service,
Springfield, Virginia 22151
19. SECURITY CLASS (This Report/
Unclassified
21. NO. OF PAGES
182
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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