U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-251 819
MANUFACTURE AND USE OF
SELECTED ALKYLTIN COMPOUNDS:
TASK II
MIDWEST RESEARCH INST,
PREPARED FOR
ENVIRONMENTAL PROTECTION AGENCY
MARCH 1976
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EPA 560/-6-76-011 PB 251 819
THE MANUFACTURE AND USE
OF SELECTED ALKYLTIN COMPOUNDS
TASK II
^ PDfll#
JANUARY 15, 1976
FINAL REPORT
ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
401 M STREET, S.W.
WASHINGTON, D.C. 20460
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BIBLIOGRAPHIC DATA
SHEET
I l. Keport No.
EPA 560/6-76-011
3. Recipient's Accession No.
4. Title and Subtitle
Manufacture and Use of Selected Alkyltin Compounds
5. Report I'ntc -Issutld
March 1976
6.
7. Author(s)
Thomas W. Lapp
B. Performing Organization Kept.
No.
9. Performing Organization Name and Address
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
10. Project/Task/Work Unit No.
Task II
11. Contract/Grant No.
68-01-2687
12. Sponsoring Organization Name and Address
Environmental Protection Agency
Office of Toxic Substances
Washington, D.C. 20460
13. Type of Report & Period
Covered
Final Report
14.
15. Supplementary Notes
16. Abstracts xhe purposes of this study were to identify the production methods, importa-
tion, exportation, use patterns, and exposure to man and the environment for selected
alkyltin compounds from 1965 to 1974. For this study, only organotin compounds having
alkyl groups with eight carbon atoms or less attached to the tin were considered. Data
for the production methods included the specific process, raw materials, annual produc-
tion quantities, major manufacturers, waste products, environmental management of pro-
cess wastes, and other production data. Use patterns were identified and annual consump-
tion data were compiled for each compound in the respective areas of utilization. Major
consumers in each use area were identified. Various possible methods for the exposure of
man and the environment to alkyltin compounds were discussed and evaluated. Future pro-
duction quantities and areas of usage were estimated for the next 10 years.
17. Key Words and Document Analysis.
Organometallic compounds
Tin organic compounds
Production methods
Waste treatment
Stabilizers (agents)
Biocides
Catalyst
Antifouling coatings
17b. Identifiers/Open-Ended Terms
17a. Descriptors
17e. COSAT1 Field/Group Chemistry/Organometallic Chemistry
18. Availability Statement
Release unlimited
19.. Security Class (This 21. No. of Pages
Report): '-• ' ~
20. Security Class (This
NCLASSIFIED
NTI«-»» (REV. io-7»i ENDORSED BY ANSI AND UNESCO.
THIS FORM MAY BE REPRODUCED
USCOMM-DC »28B-P74
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STUDY ON CHEMICAL SUBSTANCES FROM INFORMATION CONCERNING
THE MANUFACTURE, DISTRIBUTION, USE, DISPOSAL,
ALTERNATIVES, AND MAGNITUDE OF EXPOSURE TO
THE ENVIRONMENT AND MAN
Task II - The Manufacture and Use of Selected Alkyltin Compounds
by
T. W. Lapp
FINAL REPORT
April 2, 1976
EPA Contract No. 68-01-2687
MRI Project No. 3955-C
For
Environmental Protection Agency
Office of Toxic Substances
4th and M Streets, S.W.
Washington, D.C. 20460
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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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PREFACE
This report presents the results of Task II of a project entitled
"Study on Chemical Substances from Information Concerning the Manufactur-
ing, Distribution, Use, Disposal, Alternatives, and Magnitude of Exposure
to the Environment and Man," performed by Midwest Research Institute (MRI)
under Contract No, 68-01-2687 for the Office of Toxic Substances of the
U.S. Environmental Protection Agency, Mr» Thomas Kopp was project officer
for EPA.
Task II "The Manufacture and Use of Selected Alkyltin Compounds," was
conducted by Dr. T. W. Lapp, Associate Chemist, who served as project leader
and prepared this report, under the supervision of Dr. E. W. Lawless, Head,
Technology Assessment Section. Dr. I. C. Smith, Senior Advisor for Environ-
mental Science, provided technical consultation and Ms. Cassandra Collins
provided technical assistance throughout the course of this study. This
program had MRI Project No. 3955-C.
MRI would like to express its sincere appreciation to the several com-
panies who provided technical information for this report.
Approved for:
MIDWEST RESEARCH INSTITUTE
L. J. Shannon, Assistant Director
Physical Sciences Division
April 2, 1976
iii
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CONTENTS
Section Page
I Introduction ..................... 1
II Summary ........ 3
III Historical Development and Future Outlook 5
Historical Developments ........ 5
Future Outlook 7
IV Market Input-Output Data 10
Production ......... 10
Importation 10
Exportation 12
Use Patterns ••• 13
Final Products 14
V General Manufacturing Processes 15
Grignard Method 17
The Direct Synthesis 20
Ester Formation ........ 22
Manufacturing Costs 23
Environmental Management .............. 24
VT Process Technology ..... .. 28
General Production Capacity 28
Specific Organotin Compounds . 30
Handling and Transportation 58
Preceding page blank
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CONTENTS (concluded)
Section Page
VII Areas of Utilization 60
Heat Stabilizers for Poly(Vinyl Chloride) ...... 60
Catalysts 82
Biocidal Application ..... 88
Miscellaneous Specialized Uses 92
VIII Future Production and Utilization 96
Heat Stabilizers 97
Catalysts 100
Biocidal Applications 101
IX Material Balance and Energy Consumption 104
Raw Materials 104
Energy Consumption 107
Waste Material Produced 107
Exposure to Man and the Environment ......... 110
X Use Alternatives 118
Alternative Raw Materials ..... 118
Alternative Manufacturing Processes ......... 118
Alternative Final Use Products ..... 120
vi
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FIGURES
No. Page
1 Production and Waste Flow Diagram for Alkyltin
Compounds 18
2 Consumption of PVC in Rigid Pipe and Conduit and
Estimated Consumption of Alkyltin Compounds as
Heat Stabilizers 98
3 Reaction Schematic for the Preparation of Alkyltin
Compounds ................. 105
vii
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TABLES
No.
1 Estimated Annual U.S. Production of Selected Alkyltin
Compounds 11
2 Estimated Annual U.S. Consumption of Selected Alkyltin
Compounds by Use Area 13
3 Estimated Production Capacities 29
4 Trade Names of Common Alkyltin Compounds ....... 31
5 Estimated Consumption of Organotin Compounds as Heat
Stabilizers .... ........ 62
6 Major PVC Compounders 66
7 Estimated Consumption of Organotin Compounds in Pipe
and Conduit . ... 68
8 PVC Pipe and Conduit Use by Area 68
9 Estimated Consumption of Organotin Compounds in Injec-
tion Molding 70
10 Estimated Consumption of Organotin Compounds in Rigid
Siding . . . 72
11 Estimated Consumption of Organotin Compounds in Foam
and Nonfoam Rigid Profiles ....... 74
12 Estimated Consumption of Organotin Compounds in Non-
food Bottles 75
viii
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TABLES (concluded)
No.
13 Estimated Consumption of Organotin Compounds in Food
Use Bottles 77
14 Estimated Consumption of Organotin Compounds in Rigid
Sheet and Film for Nonfood Uses 80
15 Estimated Organotin Consumption in Semirigid Sheet and
Film for Nonfood Applications 81
16 Estimated Consumption of Octyltins and BTSA in Rigid
and Semirigid PVC Sheet and Film for Food Use .... 83
17 Major Rigid Polyurethane Foam Producers . 85
18 Major Silicone Elastomer Producers ... 86
19 Estimated Consumption of Organotin Compounds as
Catalysts . 87
20 Consumption of Raw Materials, 1965 to 1974 106
21 Energy Consumption ........ ..... 107
22 Waste Material Production 108
IX
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SECTION I
INTRODUCTION
Organotin compounds find widespread distribution throughout the
industrial environment in four basic categories: heat stabilizers for
poly(vinyl chloride) (PVC), biocides, polyurethane foam catalysts and
catalysts for the room temperature vulcanization (RTV) of silicone rub-
ber. Their potential exposure to man and the environment is exemplified
by the diversity of applications these four categories encompass, in-
cluding: PVC water pipe (both potable and nonpotable); marine antifoul-
ing agents; fungicides; vinyl exterior construction cladding; vinyl
paints; polyurethane foam furniture; silicon rubber coatings and seal-
ants; rigid PVC packaging for food products; and rigid and foam PVC
extruded profiles,
MRI's objective has been to conduct a survey of selected compounds
in the organotin industry to provide data on manufacturing processes,
production quantities, importation and exportation, use areas, environ-
mental management at production and formulation sites and other perti-
nent information concerning the use and manufacture of these materials.
This report then serves to present a view of the status and scope of
organotin technology and the industry this technology serves.
The chemicals investigated were selected on the basis of production
volume and usage. Many of the commercially available organotins were
omitted, because their usage was deemed minor with respect to the total
consumption of organotin compounds. In this study MRI was also limited
in its consideration only to those alkyl organotin compounds in which
the alkyl groups bonded directly to the tin atom have eight carbon atoms
or less. This limitation excluded two pesticides of economic importance:
tricyclohexyltin hydroxide and triphenyltin hydroxide.
The following list of organotin compounds represents those materi-
als which find major usage in the industry:
* Mono- and dimethyltin isooctylmercaptoacetates
* Mono- and dibutyltin isooctylmercaptoacetates
* Dibutyltin-bis(laurylmercaptide)
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* Dibutyltin dilaurate
* Dlbutyltin-bis(alkyl maleate ester)
* Dioctyltin-S,S'-bis(isooctylmercaptoacetate)
* Dioctyltin maleate polymer
* Bis(tributyltin)oxide
* Tributyltin fluoride
Our task is to assist the Environmental Protection Agency in the
evaluation of the potential for environmental contamination by the sel-
ected organotin chemicals*
The organization of the compiled information is presented in a for-
mat which we hope will enable the reader to get a rapid and specific
survey of the manufacture and use of organotihs.
The limitations of this survey are those inherent in any study con-
cerned primarily with proprietary information* As such, the report is of
necessity dependent on the available literature and personal consulta-
tions with industry representatives. In many instances, estimations have
been necessary due to the absence of published data. Therefore, the quan-
tities stated constitute the best extrapolations MRI could make from the
currently available data.
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SECTION II
SUMMABY
For the time period 1965 to 1974, approximately 113 million pounds
of selected alkylcin compounds were produced, of which dibutyltin iso-
octylmercaptoacetate accounted for about 72 million pounds. The other
alkyltin compounds studied and their respective approximate production
figures, in million pounds, were dimethyltin isooctylmercaptoacetate
(14), dibutyltin laurylmercaptide (11), dibutyltin alkylmaleate (4),
dibutyltin dilaurate (6), dioctyltin isooctylmercaptoacetate (3), di-
octyltin maleate polymers (0.4), mixed metals (1), tributyltin oxide (3),
and tributyltin fluoride (0.3). Nearly all of the production of these
compounds are utilized in the United States with only approximately 4 to
57o being exported each year.
In the United States all alkyltin compounds, except for the methyl-
tins, are produced commercially by starting with the Grignard reaction
to form the tetraalkyltin, followed by a rearrangement reaction with
stannic chloride to form the alkyltin chlorides. Methyltins are prepared
by the direct reaction of methyl chloride with tin metal to form methyl-
tin chlorides. The alkyltin chlorides are either hydrolyzed to the cor-
responding oxide or reacted directly with the appropriate ester to form
the final product. Currently, the four major companies who produce these
alkyltin compounds are M&T Chemicals, Cincinnati Milacron Chemicals,
Argus Chemical Company, and Cardinal Chemical Company. Of these, the
first two are larger producers than the latter two companies.
The major area of utilization of most of these compounds is as a
heat stabilizer for rigid and semi-rigid poly(vinyl chloride). This area
consumes approximately 80% of the total annual production of all of these
alkyltin compounds. Of the 10 materials listed previously, all except di-
butyltin dilaurate, tributyltin oxide, and tributyltin fluoride, are used
as heat stabilizers. Dibutyltin dilaurate was used at one time as a heat
stabilizer but currently finds only very limited usage in this area. The
two dioctyltin compounds are used only in poly(vinyl chloride) applica-
tions that are in contact with food. All of the remaining compounds are
rather general purpose heat stabilizers and find usage in several areas
of application. The largest single area for the consumption of alkyltin
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compounds is for rigid pipe and conduit, as well as pipe fittings. Other
areas of application for these compounds are as catalysts for polyure-
thane and silicone elastomer production, biocides and poultry anthelmin-
tics. Dibutyltin dilaurate is used as the catalyst in the foam and elas-
tomer production as well as in poultry anthelmintics. The major biocidal
compounds are tributyltin oxide and tributyltin fluoride.
While the major use of these compounds is in the area of heat stabi-
lization, the greatest potential for direct contact with the environment
probably is with the biocidal applications. Tributyltin oxide and fluoride
are both active ingredients in antifouling paints and coatings for marine
craft. As such, they are leached directly into seawater, particularly in
the vicinity of the docks and marinas.
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SECTION III
HISTORICAL DEVELOPMENT AND FUTURE OUTLOOK
The historical development of selected alkyltin compounds as PVC
heat stabilizers, biocidal compounds, and catalysts is reviewed. Their
future outlook, from 1975 to 1985, is discussed from a generalized view-
point.
HISTORICAL DEVELOPMENTS
Organotin chemicals were synthesized over a century ago by the
chemist Frankland (diethyltin dioxide in 1849>i/ and Lowig (1852)JLt2/
Laboratory work continued through the next 75 years, but no practical
applications were found until 1925^' when organotins were claimed as
mothproofing agents. No organotin chemicals, however, have enjoyed not-
able usage in this capacity.
The use of organotin compounds as stabilizers for chlorinated
transformer oils dates back to 1932,4' At that time, the transformer
insulation consisted of paper and mineral oil. Large temperature gradi-
ents generated across the oil by power fluctuations in the transformer
caused decomposition of the mineral oil to a sludge. This oxidative de-
composition was prevented by the addition of tetraalkyl or tetraaryltin
compounds.
In 1936, V. Yngve, working for Carbide and Carbon Chemicals Corpo-
ration, received the first patent involving dialkyltin compounds in the
stabilization of PVC. This occurred just 3 years after the first patent
on the plasticization of PVC.-^' It has been reported by a knowledgable
source that the original work done here was by Dr. W. M. Quattlebaum but
that in order to quickly get patent coverage, the work was included in
the patent application of Yngve, which was about to be filed.
Carbide and Carbon Chemicals Corporation also employed Rugeley and
Quattlebaum, who in 1939, claimed the use of dibutyltin dilaurates, di-
butyltin oxides and similar compounds as stabilizers for dry spun vinyl
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chlorine-acetate copolymer fibersr=' Further patents by Yngve covered
tetraaIky1tins and dialkyltin dicarboxylic acid salts for general vinyl
stabilization.
Quattlebaum and Young£' were the first to use organotin salts com-
mercially for the stabilization of vinyl chloride resins, and to produce
dibutyltin oxide, dibutyltin dilaurate, and related salts which proved
soluble in vinyl chloride resins.
Dibutyltin maleate, first mentioned in a 1942 patent application by
Quattlebaum and Noffsinger, was a far more effective stabilizer than the
dilaurate and it also prevented yellowingJLJJ'
During the late 1940's, the General Electric Company^' used tetra-
organotin compounds as scavengers for HC1 released from askarels in cer-
tain short-circuited transformers. Although they were highly effective,
present tetraorganotin usage in this capacity is of little note.-='
The biocidal effects of organotins were not studied until the 1950's
when workers at the Tin Research Institute discovered that triorganotin
compounds had pronounced biocidal properties. This discovery led to a
wealth of new uses for the organotin compounds. Toxicological interest
was further stimulated in organotins when 100 cases of human poisonings
and deaths occurred in 1954 in France. A pharmaceutical preparation based
on dieLhyltin diiodide was contaminated with a highly toxic triethyltin
impu,-:ty» This disastrous event retarded further research into the deve-
lopment of nrganotin compounds as practical biocides.Tt^i''
An important step forward was the discovery, in 1950, that compounds
containing tin-sulfur bonds had remarkable stabilizing action. «. The
first compounds of this type to be patented were the mercaptides and sul-
phides, and the di- and tri-mercaptides soon followed.
In 1951, the alkyltin mercapto acids and their esters were deve-
loped^' and have found extensive use in the manufacture of blow-molded
products because of the outstanding heat stability they impart to PVC.
The next important development was the introduction of dioctyltin
stabilizers for food contact application. In addition to negligible mam-
malian toxicity, dioctyltin compounds have lower odor levels and better
lubrication properties than corresponding butyltin compounds. 1"*°' How-
ever, stabilization by the octylthiotin compounds is not as good as di-
butyltin derivatives, but the best results are obtained using di-ji-
octyltin derivatives of thioglycollic acid.
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M&T Chemical, Inc., conducted a 2 year chronic toxicity study as
part of a 5 year screening project with the organotins*^' The results
were submitted to the U.S. Food and Drug Administration, and in 1968 ap-
proval was given for the use, in food-contact application, of di(n-
octyl)tin maleate polymer and di(n-octyl)tin-S,S'-bis(isooctylmercapto-
acetate).
In summary, after the inception of the first organotin compound,
this new chemical field has enjoyed a wealth of investigation. However,
it was not until after 1945 that the organotins were studied to any great
extent as commercially important chemicals.
A further in-depth study of the organotin history can be found in
H. Verity Smith's "The Development of the Organotin Stabilizers," pub-
lished by the Tin Research Institute, December 1959.—
The developments in the organotin industry occurring after 1965 will
be the subject of further investigation in this study.
FUTURE OUTLOOK
The future use of alkyltin compounds during the next 10 years ap-
pears to be towards increased consumption with yearly fluctuations de-
pending upon the poly(vinyl chloride) market. Usage as heat stabilizers
during the processing of rigid and semi-rigid PVC products is, by far,
the largest use of alkyltin compounds and should continue to dominate
their consumption pattern during the next 10 years. Biocidal applica-
tions have begun to consume increasing quantities of alkyltin compounds
during the past 2 to 3 years, and this market should be a good growth
area during the next 10 years. The alkyltin share of the catalyst mar-
ket, both in urethane foam and silicone elastomers, has not increased
during the past 10 years and should not increase to any appreciable ex-
tent during the next 10 years. Growth will occur as a result of increas-
ing production of urethane foams and silicone elastomers, not as a re-
sult of an increase in the market shares.
There are at least three major factors which tend to cloud the pic-
ture regarding the future consumption of alkyltin compounds. The primary
factor probably is the overall effect that the vinyl chloride monomer
restrictions will have on future poly(vinyl chloride) production. Alkyl-
tin consumption virtually lives and dies with the PVC market so that the
future of PVC will dictate the future of alkyltin compounds. A second
factor is the recent FDA proposed regulation to restrict PVC containers
intended to contact food. At the present time, this proposed regulation
directly affects only the two dioctyltin compounds. However, included in
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the FDA proposal is a possible restriction on rigid PVC pipe for potable
water. This use area includes large quantities of other alkyltin com-
pounds and restriction in this area could be a major depressant for the
entire industry. The third factor is the general economic conditions pre-
vailing at the present time and, in particular, the construction industry.
This industry consumes relatively large quantities of rigid and semi-rigid
PVC products, almost all of which are stabilized with alkyltin compounds.
At the present time, rigid PVC for uses such as siding, profiles, etc.,
control.less than 2% of those markets. If rigid PVC was to increase its
share of the siding market at the expense of aluminum, this would repre-
sent a tremendous increase in the PVC and organotin stabilizer market.
A significant recovery of this industry or an expanded share of existing
markets would lead to increased consumption of alkyltin compounds. By
1984, the overall consumption of alkyltin compounds in all areas could
be in the range of 45 million pounds annually.
With respect to individual compounds, the methyl and butyltin iso-
octylmercaptoacetates and their blends should continue to be the star
performers of the PVC heat stabilizers. These two systems have been the
major materials for the past 2 to 3 years and should continue in this
capacity during future years. The previous statement does not take into
account the introduction of new materials which could capture a signifi-
cant share of the market in specific areas. All other current alkyltin
compounds play a rather secondary role to the two major systems and will
probably continue this role in the future with their growth occurring as
a result of increased PVC production rather than an increased share of
the market.
In biocidal applications, bis(tributyltin) oxide (TBTO) and tributyl-
tin fluoride (TBTF) are the only two compounds included in this study
that have found usage in this general area. Specific applications are cur-
rently in antifouling paints and coatings, water and emulsion paint addi-
tives, and as additives to industrial cooling water. Spurred by the desire
to decrease energy consumption, the antifouling paints and coatings area
has seen increased activity during the past couple of years. Future con-
sumption of alkyltin compounds in this area may well be in the form of
alkyltin polymers as opposed to the present system of being a paint or
coating additive. Increased consumption should also occur in the addition
of TBTO to paints for the prevention of mold and mildew. A major future
use of TBTO may be in the control of the disease, bilharzia. This disease
currently affects millions in underdeveloped tropical countries. Its con-
trol is directly related to the control of freshwater snails, which serve
as a carrier. At a research level, tests have shown that incorporation
of TBTO into a vulcanized elastomer pellet, producing continual, low-
level release of TBTO, provides effective control of the freshwater snail.
Commercialization of this process could lead to significant increases in
the consumption of bis(tributyltin) oxide in future years.
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REFERENCES TO SECTION III
1, Anonymous, Tin Chemicals For Industry» Tin Research Institute, TRI
Publication No. 447, Greenford, Middlesey (1972).
2. van der, Kerk, G. J. M., Conference on Tin Consumption, pp. 183-197,
Paper No. 9, London, March 1972.
3. Sawyer, A. K., ed., Organotin Compounds, pp. 931-971, Marcel Dekker,
New York (1971).
4. Piver, W. T., Environmental Health Perspectives, Issue 4» pp. 61-79,
June 1973.
5. Smith, H. V., "The Development of Organotin Stabilizers," pp. 1-27,
Tin Research Institute, Greenford, Middlesey, December 1959.
6. Hardwicke, J. E., Modern Plastics Encvlopedia. 43(1A):438-441 (1966).
7. Neumann, W. P., "The Organic Chemistry of Tin," pp. 230-266, Inter-
science Publishers, New York (1970).
8. Evans, C. J., Tin and Its Uses. 87:13-17 (1971).
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SECTION IV
MABKET INPUT-OUTPUT DATA
Cumulative data are presented for the selected alkyltin compounds
during the time period 1965 to 1974. The data are considered in terms of
production, importation, exportation, use patterns, and final products
of these compounds.
PRODUCTION
The estimated total production quantities of each of the alkyltin
compounds included in this study on an annual basis and for the 10-year
time span (1965 to 1974) are shown in Table 1. In the United States, the
four major manufacturers of alkyltin compounds are M&T Chemicals, Argus
Chemical Company, Cincinnati Milacron Chemicals, and Cardinal Chemical
Company. Smaller quantities of these compounds are produced by several
other companies. In terms of total production over the 10-year span, the
three major alkyltin compounds are the butyltin isooctylmercaptoacetates,
methyltin isooctylmercaptoacetates, and dibutyltinbis(laurylmercaptide).
As shown in Table 1, the estimated total quantity of alkyltin com-
pounds produced during the 10-year span was approximately 113 million
pounds. Additional information concerning the specific alkyltin compounds
may be found in Section V.
IMPORTATION
Importation of alkyltin compounds over the 10 years from 1965 to
1974 have generally not accounted for an appreciable percentage of the
total overall production of these materials. Except for the importation
of quantities of bis(tributyltin)oxide and tributyltin fluoride during
the past 3 to 4 years, the only alkyltin compounds imported were either
the tetraalkyltin or dialkyltin oxides, which are used as intermediates
in the production of alkyltin heat stabilizers. No end product materials,
for use as heat stabilizers, were imported. However, this would not ex-
clude intracompany transfers of these materials. According to one manu-
facturing source, imports of the intermediates were 10 to 15% of the
10
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Table 1. ESTIMATED ANNUAL U.S. PRODUCTION OF SELECTED ALKYLTIN COMPOUNDS (MILLION POUNDS PER YEAR)
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Total
Bu
IOMA
2.3
4.6
4.9
6.2
7.1
8.3
8.2
10.5
10.1
-2-2
71.5
Appreviations:
Me Bu Bu Oct. Oct. Mixed
IOMA LM Maleate IQMA Maleate metals
1.0 0.22 ...
1.0 0.22
0.9 0.48 -
0.9 0.52 0.16 0.02
0.9 0.57 0.20 0.03
0.7 1.1 0.59 0.32 0.05
1.4 1.1 0.62 0.37 0.06
2.9 1.3 0.26 0.56 0.08
4.0 1.3 0.22 0.62 0.08 0.8
4.5 1.3 0.21 0.37 0.07 0.5
13.5 10.8 3.91 2.60 0.39 1.3
Bu IOMA = Butyltin isooctylmercaptoacetate + blends.
Me IOMA = Methyltin isooctylmercaptoacetates + blends.
Bu LM = Dibutyltin-bis(laurylmercaptide).
Bu Maleate = Dibutyltin alkylmaleate esters.
Oct. IOMA = DiCji-octyOtin-S.S'-bisdsooctylmercapto-
acetate).
Oct. Maleate = Di(n-octyl)tin maleate polymers.
DBTDL = Dibutyltin dilaurate.
TBTO = Bis(tributyltin) oxide.
TBTF = Tributyltin fluoride.
DBTDL
0.3
0.3
0.35
0.4
0.5
0.6
0.7
0.7
0.9
_UO
5.75
TBTO
0.50
0.50
0.10
0.10
0.15
0.17
0.20
0.25
0.30
0.50
2.77
TBTF Total
4.32
6.62
6.73
8.30
9.45
0.01 11.84
0.02 12.67
0.05 16.60
0.08 18.40
0.12 17.87
0.28 112.80
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total U.S. production during the raid-I960's. After about 1966, U.S.
production capacity increased and the need for imports decreased to ap-
proximately 5% or less of the. total U.S. production. Following devalua-
tion of the U.S. dollar in foreign money markets, it often became more
economical to import intermediates than to produce them at the U.S. pro-
duction facilities. Thus, depending upon the economic conditions, impor-
tation of intermediates increased somewhat during the past 2 to 3 years.
The listing shown below gives the importation of alkyltin compounds dur-
ing the years 1966 and 1972 to 1974, Imports for the intervening years
between 1966 and 1972 were not recorded as it was during this period
that imports constituted less than 5% of the total annual production of
alkyltin compounds and were mainly tetrabutyltin and dibutyltin oxide.
a/
Quantity imported (pounds)~
Material 1966 1972 1973 1974
Dibutyltin dichloride ... 3,442
Dibutyltin oxide 344,580 719,794 248,349 71,400
Dioctyltin oxide - 12,998 84,963 47,681
Bis(tributyltin) oxide 1,116 56,358 9,834 82,756
Tributyltin fluoride - 9,140 4,940
Tributyltin chloride - 2,320 2,900
Tetrabutyltin - 25.000 - 144.029
Total 345,696 825,610 350,986 349,308
j/ Data from weekly listing in Chemical Marketing Reporter.
The originating countries for these imports were as follows:
1966 - Japan; 1972 - Japan; 1973 - Japan, Germany; 1974 - Japan, Germany,
Imports from Japan originated from five ports: Yokohoma, Kobe, Nagoya,
Tokyo, and Osaka; those from Germany all originated from Hamburg.
EXPORTATION
During the past 10 years, exportation quantities have remained in
the range of 4 to 5% of the total annual U.S. production of the materi-
als under study. Exportation has been only in the form of the end prod-
ucts, i.e., no intermediates such as tetraalkyltin, alkyltin oxides (ex-
cept TBTO), etc. Countries to which exportation occurs include Taiwan,
Singapore, and South American countries. The exportation figures stated
above, which are estimates by U.S. manufacturers of organotin compounds,
do not include any intracompany transfers of materials. Since the three
12
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major companies have subsidiaries in foreign countries, considerable
transfer of material occurs but the quantities of such material would be
very difficult to determine.
USE PATTERNS
Utilization as heat stabilizers for rigid poly(vinyl chloride) con-
sumes the vast majority of the total annual production of alkyltin com-
pounds. Other areas in which these compounds are used include catalysts
for polyurethane foam and RTV silicone elastomers, biocidal applications,
poultry anthelmintics, and other miscellaneous applications. Consumption
in each of these areas is overshadowed by the use as heat stabilizers.
The estimated annual consumption in each of these areas is listed in
Table 2.
Table 2. ESTIMATED ANNUAL U.S. CONSUMPTION OF SELECTED ALKYLTIN
COMPOUNDS BY USE AREA (QUANTITIES IN MILLION POUNDS)
PVC
Year Heat stabilizer Catalysts Biocidal Anthelmintic Miscellaneous
1965 3.3 0.01 0.50 0.15 0.36
1966 5.6 0.03 0.50 0.16 0.33
1967 5.9 0.06 0.10 0.17 0.50
1968 7.4 0.10 0.10 0.18 0.52
1969 8.3 0.21 0.15 0.19 0.60
1970 10.6 0.28 0.18 0.21 0.57
1971 11.2 0.36 0.22 0.22 0.67
1972 15.5 0.41 0.30 0.23 0.16
1973 17.0 0.52 0.38 0.24 0.26
1974 16.2 0.62 0.62 0.24 0.19
The division between the various alkyltin compounds used in each of
the areas is relatively straightforward. Of the materials listed in Table
1, only dibutyltin dilaurate, bis(tributyltin) oxide, and tributyltin
fluoride are not used as heat stabilizers for rigid and semi-rigid poly-
(vinyl chloride). Dibutyltin dilaurate was used in past years as a heat
stabilizer but its utility in this area had virtually ceased prior to
1965. Of those compounds used as heat stabilizers, the two dioctyltin
compounds are used almost solely in PVC intended to contact food. All of
the others are strictly for nonfood PVC usage in the United States. Di-
butyltin dilaurate is used as a catalyst for polyurethane foam and RTV
silicone elastomers and as a poultry anthelmintic. Bis(tributyltin) oxide
13
-------
(TBTO) and tributyltin fluoride (TBTF) are used exclusively for biocidal
applications, such as antifouling marine paints. Use areas such as fiber
stabilization, exportation, and other miscellaneous areas employ rela-
tively small quantities of alkyltin compounds. The utilization of each
of the alkyltin compounds is discussed more fully in Section VIII.
FINAL PRODUCTS
Currently, the ultimate use of the majority of the alkyltin com-
pounds in this study is in rigid and semi-rigid poly(vinyl chloride) ma-
terials. Some of the compounds also find use in PVC copolymers, such as
with vinyl acetate or vinylidene chloride. Other products containing
alkyltin compounds include marine antifouling paints and coatings, water
or emulsion-based paints, anthelmintics for poultry, polyurethane foams,
silicone elastomers, and other minor use areas.
In rigid and semi-rigid PVC applications, the major consumption area
is in the pipe and conduit field. Since 1965, this area has annually con-
sumed between approximately 40 to 60% of the total quantity of alkyltin
compounds in the area of PVC. Alkyltin compounds are used exclusively to
stabilize potable water pipe. All other types of rigid PVC pipe (nonpot-
able water pressure pipe, drain-waste-vent (DWV) pipe, conduit, and sewer
and drain) are largely stabilized with alkyltin compounds, the largest
market for this type of product is the construction industry. As would
be expected, the injection molding of PVC pipe fittings is also another
large use area for alkyltin compounds. Other areas of rigid and semi-rigid
PVC that employ alkyltin compounds as heat stabilizers include rigid sid-
ing for buildings; extruded foam and nonfoam interior wall paneling trim;
bottles for food and nonfood uses; clear, rigid and semi-rigid packaging
items, such as blister packs; rigid sheets for patio covers, skylights,
carports, etc.; rain gutters, downspouts, and other rainwater accessories;
window frames; credit cards; industrial safety windows; and numerous other
uses of rigid PVC material.
The largest use of alkyltipi compounds in biocidal applications is in
antifouling marine paints and coatings. At the present time, this is the
sole use for tributyltin fluoride and the major use for bis(tributyltin)
oxide (TBTO). Other current uses for TBTO are in water and emulsion paints
to prevent mildew as well as to extend shelf-life and as an additive to
industrial cooling water.
As an anthelmintic, dibutyltin dilaurate is formulated into tablets
or granules for use with poultry. It is also formulated into the same two
forms as a toxicidiostat for young turkeys. In addition to its anthelmin-
tic usage, dibutyltin dilaurate is also used as a catalyst in polyurethane
foams and in the room temperature vulcanization of silicone elastomers.
14
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SECTION V
GENERAL MANUFACTURING PROCESSES
There are four companies who currently produce the majority of
the organotin compounds under consideration in this study. These are:
M&T Chemicals, Inc., a subsidiary of American Can Company; Argus Chemi-
cal Corporation, a subsidiary of Witco Chemical Corporation; Cincinnati
Milacron Chemicals, Inc.; and Cardinal Chemical Company. Other companies,
who produce organotin compounds primarily from purchased intermediates,
include: Ferro Chemical Company; Tenneco Chemicals; and Synthetic Prod-
ucts Company, a division of Dart Industries. Further information regard-
ing the various compounds manufactured by each company, production sites,
capacities, and yearly production can be found in Section VI.
1 2/
Recent review articles and the references contained therein—4—
state that there are basically four commercial methods available for the
preparation of the organotin compounds under consideration in this study.
These are the: (a) Grignard method; (b) Wurtz method; (c) aluminum alkyl
method; and (d) "direct synthesis" method. To our knowledge, only the
Grignard and the so-called direct synthesis methods are presently being
used to produce organotin compounds in the United States.
The Wurtz method has been used in previous years but it was discon-
tinued in approximately 1965. This production procedure can present prob-
lems associated with flammability.
In Europe, the aluminum alkyl method is used for the commercial
preparation of butyl and octyltin compounds but this method has never
been adopted on a widespread scale in the United States. During the mid-
dle 1960's, Stauffer Chemical Company supposedly investigated the usage
of this method but subsequently dropped plans to enter into production.
Additional information concerning this method is presented in Section X,
page 118.
The basic steps for the Grignard and direct synthesis methods are
outlined below for the preparation of the alkyltin chlorides. Once the
alkyltin chlorides have been produced, the subsequent steps leading to
15
-------
the alkyltin esters are the same for both methods. The sole reason for
separating the production flow diagram in this manner is to show that the
formation of the oxide and, subsequently the ester, proceeds by the same
process regardless of the initial method of preparing the alkyltin chlo-
ride. The basic reaction steps for each process are as follows:
Grignard method:
RC1 + Mg
KMgCl + SnCl
R. Sn + SnCl.
4 4
Direct synthesis:
2RX + Sn
RMgCl
R. Sn
4
R = G, or higher
R SnCl + R-SnCl + RSnCl
R — C or smaller
o
X = halogen
3. Ester formation:
R SnCl
y
+ NaOH
Ester \
\
R Sn (ester)
R Sn oxide
y
Ester
The reaction yields for each step of these processes is generally 95% or
above.
From 1965 to 1970, the Grignard method was the basic method for the
production of organotin compounds. Since 1970, many of the U.S. producers
have been importing large quantities of tetrabutyltin and, in some cases,
tetraoctyltin from Germany (Schering AG) and using this material for the
redistribution reaction with stannic chloride. The German preparation oc-
curs by the alkyl aluminum process and, depending upon the German mark/U.S.
dollar (exchange) rate, can be purchased cheaper than it can be prepared
by the Grignard process. Thus, the importation of the tetrabutyltin and
tetraoctyltin was purely for economic reasons. In this respect, it has
been confirmed, from sources in the manufacturing segment, that Schering
AG is now searching for a plant in the United States or will build a plant
to produce organotin compounds by the alkyl aluminum process for the U.S.
market. For a more complete discussion of this process, see Section X.
16
-------
During the period 1970 to 1975, the so-called direct process also
came into commercial usage for the preparation of methyltin compounds.
The basic step in this process was stated previously and a more complete
discussion is presented later in this section.
THE GRIGNARD METHOD
This process is normally operated by the batch process. A generalized
process flow diagram for the production of butyl and octyltin compounds
is presented in Figure 1. All current producers of alkyltin compounds em-
ploy multipurpose plants similar to the one outlined for preparing butyl-
and octyltin compounds. A process flow diagram for the preparation of bis-
(tributyltin) oxide has been published by Glosky-Z' and the basic parameters
in his article have been incorporated into Figure 1.
The first step in the production of organotin compounds, the prep-
aration of the Grignard reagent (RMgX), is very dependent upon the type
of solvent employed; in some cases, the solvent is termed the coordinat-
ing solvent. Originally the Grignaxd base was prepared in the presence of
toluene with suitable ethers, such as diethyl or dibutyl, used in various
amounts to give the complex better solubility. The use of toluene ceased
some years ago because it interfered with the yield and produced side
products. In the preparation of butyltins, essentially all of the current
producers employ cyclohexane as the solvent with small amounts of dibutyl
ether added for stability and to reflux the magnesium. Butyl bromide is
added as the catalyst or initiator. The use of other types of catalysts
has been stated in the literature, especially the patent literature, but
in actuality a bromide, such as butyl, is the principal type.
Because low levels of metallic contamination can provide an inhibit-
ing effect on die reactions for the preparation of organotin compounds,
the process equipment used in the manufacture is predominantly glass-
lined, including reactors, heat exchangers, columns, piping, and storage
facilities.
The process for the preparation of the Grignard, base can be divided
into (a) the initiation mix; (b) the reaction mix; and (c) the reaction.
In the initiator or activator mix, butyl bromide, butyl chloride, and
stannic chloride are added, with stirring, to cyclohexane to form a 50%
solution. A small quantity of the initiating mix is added to the magnesium
and the reaction started. Once the reaction begins, the remaining initia-
tor mix, additional cyclohexane, and the reaction mix (a stoichiometric
mixture of butyl chloride and stannic chloride) are added. The total quan-
tity of cyclohexane solvent is such to provide about a 10% concentration
of magnesium in the final reaction mixture. Initially the temperature of
17
-------
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-------
the reaction mixture rises to approximately 100°F (31°C) and, as the re-
action progresses, continues to about 170°F (71°C) where it is held for
2 hr. At the end of about 2 hr, the reaction mixture is cooled and pumped
to the extractor. The final product is a mixture of tetrabutyltin and
other butyltin chlorides. With proper handling, tetrabutyltin can be pro-
duced in a 95 to 98% yield. One controlling factor in the yield is the
purity of the butyl chloride. A contamination of 1 to 2% butyl alcohol
can decrease the rate of reaction and lower the yield by as much as 10%.
In the extractor the reaction mixture is washed with dilute acid,
likely hydrochloric, at a pH of 2 to 3, to remove the magnesium chloride
and unreacted stannic chloride. Two phases form and the water phase is
removed for disposal. The cyclohexane solvent is then flashed off and re-
turned to storage.
After analysis of the crude mixture, it is pumped to a redistribu-
tion reactor where a stoichiometric quantity of stannic chloride is added.
Through 1970, most manufacturers attempted to achieve a maximum purity of
98% dibutyltin dichloride. However, it was found that small quantities of
monobutyltins were very desirable, particularly for initial color control
in heat stabilizers. Consequently, the redistribution reaction is cur-
rently carried out to yield 75 to 85% dibutyltin dichloride and 15 to 25%
monobutyltin trichloride.
Upon addition of the stannic chloride, the reaction mixture is heated
to approximately 400°F (200°C) for 2 to 3 hr. Samples of the reaction mix-
ture are taken periodically and analyzed to increase the proper ratio of
the products. After the reaction is complete, the mixture is distilled
under a vacuum of about 0.5 mm. The forerunner is removed and recycled
for further alkylation. The monobutyl dibutyltin chloride mixture is then
distilled and either pumped to storage, reacted with alkali to form the
oxide, or reacted directly to form the ester. Tributyltin chloride is re-
cycled to the redistribution reactor.
Octyltins; For the preparation of octyltins, the process is essen-
tially the same except that the solvent is a mixture of cyclohexane and
tetrahydrofuran (THF). THF is a very good coordinating solvent but is
rather expensive and very difficult to recover so only a sufficient quan-
tity is used to complex the magnesium. Aluminum chloride is the catalyst
for octyltins. Prior to the use of the cyclohexane-THF solvent mixture,
reaction yields were only in the range of 60 to 757o. With the modification
of the solvent mixture, the reaction yield has improved to perhaps 85%.
However, this lower yield, compared to the butyltins, is the reason that
octyltins are more expensive as produced by the Grignard process; the
Schering aIky1aluminum process is cheaper.
19
-------
Methyltins: Until mid-1972 M&T Chemicals was producing methyltins
by various processes. Although the processes yielded high purity mate-
rial with low trimethyltin content, they were discontinued due to eco-
nomic considerations. A direct tin process was employed in early 1973.
In 1974 the production of methyltins was voluntarily ceased due to the
environmental effects described on page 115.'
THE DIRECT SYNTHESIS !
There are two methods for the direct synthesis process: (a) the
batch process;.?.' and (b) the continuous processJJ' Since the continous
process is quite new, it is not known whether it is practiced on a com-
mercial scale or not. For either method, the only materials produced com-
mercially are the dimethyltin homologs. This lack of commercial adapta-
bility of the direct batch process is due to the slower reaction rate of
the butyls and octyls.
At the present time, only two of the current producers of organotin
compounds use the direct process, Cincinnati Milacron and Argus Chemical.
The process used by Cincinnati Milacron-^' is a batch process with a pow-
dered tin using a phosphonium catalyst, more specifically, probably methyl-
triphenylphosphoniuro bromide. A reaction yield of 90 to 95% is obtained
with relatively small quantities of mono- and trimethyltin chlorides as
by-products. The process must be directed to give the highest mono- and
dimethyltin chloride content as the trimethyltin chloride is quite toxic
(LD5Q = 20)-=' and obviously an undesirable contaminant. Argus Chemical
uses basically the same process but instead of finely divided and powdered
tin, they utilize tin shot or pellets. A phosphonium type catalyst, sim-
ilar to that stated above, is used.
Batch Process
According to the British patent,— a typical reaction for the batch
process involves heating mossy tin metal (1.0) and tetrabutyl phosphonium
iodide (0.2) to 150 to 160°C and gassing with methyl chloride (3.0 to 4.0)
for 10 hr. The numbers in parentheses represent molar ratios. At the end
of this time period, the reaction mixture is distilled under vacuum (10
mm Hg) to a pot temperature of 220°C. The distillate is dissolved in boil-
ing hydrocarbon (isooctane), cooled to room temperature, and the dimethyl-
tin dichloride (0.6) filtered. After distillation of the isooctane from
the filtrate, a residue of mixed (mono-^nd tri-) methyltin chlorides-
iodides remains, which is recycled to the reactor and added to the dis-
tillation residue of dimethyltin dichloride complexed with the phosphonium
iodide catalyst. The isooctane is also recycled. Mossy tin (1.0) is added
to the combined filtrate residue and distillation residue and the mixture
20
-------
gassed with methyl chloride for 10 hr at 150 to 160°C. Distillation, fil-
tration, and recycling are repeated* The entire procedure can be repeated
many times without loss of catalyst potency or the formation of further
by-products.
A source closely associated with the commercial manufacturing pro-
cesses has provided another description of the batch process. In this pro-
cess, a reactor is charged with mossy, foil, or small pellet tin (0.25),
and KI (0.02). Methyl chloride (1.0) and the catalyst (0.01), e.g., methyl-
triphenyl phosphonium bromide, are added simultaneously under pressure
and the mixture heated, with stirring, for 2 hr at 183 to 193°C. Again,
the figures in parentheses are molar ratios. The success of this reaction
is dependent upon the use of very finely divided tin and efficient stir-
ring so that the tin is constantly exposed to the methyl chloride. At the
end of the heating period, the reaction mixture is distilled at atmospheric
pressure to give monomethyltin trichloride (0.01), dimethyltin dichloride
(0.22), and trimethyltin chloride (0.006) for a total reaction yield of
94.4% based on tin. The unreacted methyl chloride is recycled.
Continuous Process
HechenbleiknerJ?' has recently patented a continuous process for the
production of alkyltin halides with the alkyl groups having less than five
carbon atoms. The method consists of packing a long, small diameter (about
1 in.) stainless steel reaction column with granular tin and filling the
small spaces between the granules with liquid catalyst (tributylmethyl-
phosphonium iodide). After heating the column to 150°C, methyl chloride
is pumped into the bottom of the column. As the methyl chloride rises in
the column, it reacts with the tin to form the methyltin chlorides. At the
top of the reaction column, the mixture of methyltin chlorides and liquid
catalyst pass to a distillation column, which is maintained at 180°C and
10 mm Hg pressure. In the distillation column, the liquid catalyst, con-
taining some complexed methyltin chloride, is separated from the methyltin
chlorides. The methyltin chlorides, being more volatile, are distilled to
a product holding tank; the liquid catalyst decends to the bottom of the
distillation column and is pumped to the bottom of the reaction column for
recycling. Any methyl chloride present in the product holding tank is
stripped and recycled to the reaction column. After 5 hr of operation,
the process becomes a steady state with essentially all of the methyl chlo-
ride being converted to the methyltin chlorides. During the process, addi-
tional tin is added at the top of the reactor column. The yield, based on
tin, is essentially quantative after the steady state is established. No
analysis of the reaction products with respect to the distillation between
mono-, di-, and trimethyltin chlorides is stated.
21
-------
ESTER FORMATION
From this point forward, the alkyltin chlorides are treated in the
same manner regardless of the initial method [of preparation, i.e., Grignard
or direct synthesis. Commercially, alkyltin chlorides are used in the prep-
aration of about 75 to 80% of the organotin compounds, particularly the
mercaptoesters. Conversion of the butyl- or dioctyltin dichlorides to the
oxide, by the major manufacturers, was only done for commercial reasons,
i.e., resale to another heat stabilizer producer or for the production of
carboxylate-type stabilizers, such as dibutyltin dilaurate or dibutyltin
isooctylmaleate.
From the Bichloride (and Trichloride)
The formation of the alkyltin mercaptoesters is accomplished by a
relatively straightforward reaction of the appropriate alkyltin chloride
and mercaptoester with provisions for the immediate removal of the hydro-
gen chloride by-product*^' A 2:1 molar ratio of isooctylmercaptoacetic
acid to dibutyltin dichloride are combined and heated to about 35°C. An-
hydrous ammonia is slowly added below the surface. The resulting exo-
thermic reaction raises the temperature to approximately 80°C; this is
followed by a decrease in temperature to 50°C, which denotes that the
reaction is complete. When the temperature drops, the flow of NH3 is
ceased and nitrogen bubbled through the reaction mixture to remove ex-
cess ammonia. After cooling, the alkyltin ester is washed with an aque-
ous 2.5% citric acid solution to remove any residual ammonia and the am-
monium chloride. The organic layer is separated, heated to 120°C to remove
any residual water, filtered, and pumped to storage tanks for packaging.
The aqueous layer is directed to the waste treatment system. In this pro-
cess, other alkaline substances, such as sodium hydroxide, bicarbonate,
or carbonate, can be used. The removal of residual water is very impor-
tant, otherwise precipitation can occur, which is highly undesirable as
the precipitate is a poor stabilizer and affects the efficiency of the
overall product. Methyltin chlorides are not converted to the oxides and
all esters of these compounds are prepared in this manner.
From the Oxide
As stated previously, the oxide is prepared only for the following
reasons: (a) resale; (b) preparation of nonsulfur esters; or (c) if the
oxide has a specific end use (e.g., bis(tributyltin)oxide).
Conversion of the alkyltin chloride to the corresponding oxide is
effected by treatment of the chloride with a 107o aqueous solution of NaOH
at 75 to 80°C with stirringJ?' Reaction times are generally about 1 hr.
If the resultant oxide is a solid, a very small quantity of a detergent,
22
-------
such as Santomerse, is added to prevent caking of the solid and aid in
ease of handling, the slurry is centrifuged to separate the solid from
the saline solution, vacuum dried, and transferred to bulk storage. The
saline solution waste material is generally discharged directly into the
plant sewer system. If residual alkyltin chloride concentrations are pres-
ent, the alkyltin chlorides would probably be further neutralized.
Preparation of the alkyltin ester is accomplished by mixing stoichio-
metric quantities of the alkyltin oxide and the appropriate ester (or acid)
in toluene. The reaction mixture is refluxed in the toluene for 6 to 8 hr,
depending upon the ester or acid used. Water produced during the reaction
is azeotropically distilled from the reaction mixture and is used as a
measure of the progress of the reaction. When a stoichiometric quantity
of water has been removed, the reaction is complete. The reaction mixture
is transferred to a still, where the toluene is stripped and recycled and
the alkyltin ester is pumped to storage tanks for shipment.
For those processes in which the oxide is purchased to produce sulfur-
containing esters, the reaction is usually done in situ, i.e., without a
solvent, and proceeds very quickly. Water, produced as a by-product, must
be removed from the reaction mixture, as well as the final product, to pre-
vent precipitation. Wastewater from the reaction is normally discharged
into municipal sewer lines. The alkyltin ester is pumped to storage tanks
to await packaging and shipment.
MANUFACTURING COSTS
The manufacturing facilities of current producers of organotin com-
pounds are multipurpose plants capable of producing a variety of materi-
als (see Figure 1). Since metal impurities are undesirable in the fin-
ished product, all reactors, wash tanks, storage tanks, and weighing tanks
are glass-lined. All heat exchangers, fractionating columns, centrifuges,
vacuum dryers, and filters are constructed from either stainless steel
or stainless clad steel.
Using current major equipment costs, it has been calculated that the
capital value of a new plant capable of producing 1 million pounds of al-
kyltin heat stabilizer would be slightly less than $3 million. This plant
investment would include major equipment, its installation, and all neces-
sary piping, electrical wiring, instrumentation, a building to house the
facility, and a 1/2 acre plant site. A manufacturer of organotin compounds
has estimated that a 1 million pound production site, with all ancillary
facilities, would cost approximately $5 million. This estimate is based
on a larger plant site and includes waste treatment facilities, which were
not included in the $3 million figure.
23
-------
Cost estimates have been calculated to produce 1 Ib of a common
alkyltin heat stabilizer, dibutyltin-S,S'-bis(isooctylmercaptoacetate),
in the production facility shown in Figure 1, Based on the current raw
material prices shown below, the cost per pound based solely on raw ma-
terials is $1.934. I
Butyl chloride 45.0^/lb Isooctylmercaptoacetic acid 100.0^/lb
Stannic chloride 210.4^/lb Cyclohexane 13.90/lb
Magnesium chips 92.0<£/lb Toluene 8.60/lb
50% Sodium hydroxide 8.0<£/lb Ethyl bromide 61.5*/lb
Sodium carbonate 2.80/lb Diethyl ether 49.6^/lb
Using utility costs of $2.00/lb for steam, $1.00/1,000 cu ft for gas, and
$0.02/kw-hr electricity, an additional cost of 0.775*7Ib is derived. As-
suming a total labor cost, including a plant manager, of $100,000/year,
an additional 10.004/lb is added to the product.
The total cost per pound of product can be summarized as follows:
Cost item Price/lb
Raw materials $1.9340
Utility costs 0.0078
Labor costs . 0.1000
Total $2.0418 = $2.04
The original price was $1.934/lb, based solely on raw materials. If
the additional charges for utilities and labor of $0.10775/lb are added,
the total cost is $2.0418/lb of the dibutyltin isooctylmercaptoacetate.
This cost is exclusive of the prorated original plant investment cost.
The current selling price for a typical butyltin isooctylmercaptoacetate
of this type is approximately $2.30/lb.
ENVIROMMENTAL MANAGEMENT
In this subsection, the available information is presented with re-
spect to the disposal methods, losses, and reclamation process, if any,
for each manufacturer of organotin compounds. Letters were sent to nine
manufacturers or sellers of organotin compounds. The EPA regional offices
associated with each manufacturing site were contacted with respect to
NPDES discharge permits that may have been issued to the respective com-
panies. The results of the written request and the search for discharge
permits are summarized in the following discussion.
24
-------
Argus Chemical Company: The production facility at Taft, Louisiana,
utilizes deep-well disposal methods for the effluents from their methyl-
tin production facilities. Although a NPDES discharge permit was issued
for effluent disposal into the Mississippi River, Argus states that all
of the effluent from the methyltin facility is being discharged to the
deep well. According to this manufacturer, the only effluent consists of
a brine solution resulting from the neutralization with sodium hydroxide
of the hydrogen chloride evolved during ester formation with dimethyltin
dichloride. No trimethyltin by-products are present in the aqueous ef-
fluent. The only other by-product of the reaction process is the spent
phosphonium catalyst, which is present as a thick semisolid. This mate-
rial is periodically cleaned from the reactor, stored and removed by a
contract hauler.
Cardinal Chemical Company: Received no response on waste management
procedures. No record of any NPDES discharge permit.
Cincinnati Milacron Chemicals, Inc.: Mr. R. C. Witman reported in
a letter that any description of effluent handling involves proprietary
information concerning their manufacturing techniques. He stated that,
in general, their final effluents are handled by outside disposal ser-
vices, municipal sewers, or settling ponds. No wastes are discharged di-
rectly to rivers or other waterways and that their sewer effluent is
monitored periodically by municipal and state officials. There is no
record of any NPDES discharge permit.
Ferro Chemical Company; Ferro purchases alkyltin oxide and tetra-
butyltin intermediates for conversion to the esters at their Bedford,
Ohio, facility. Dr. Larry Wilson stated that waste effluent streams are
handled by two methods depending upon the chemical nature of the efflu-
ent: (a) contract disposal services; and (b) waste treatment facilities
to produce a burnable component and a component discharged to the sewer
system. Some hydrolyses products of the ester, e.g., mercaptoacetic acid,
may be present but probably would not be detected as a component of the
"Organic" phase due to their water solubility. He also stated that for
those companies using alkyltin chlorides to produce the alkyltin esters,
the HCl by-product is generally scrubbed, neutralized with a sodium hy-
droxide solution and discarded into the sewer system as a saline solution,
Interstab Chemicals. Inc.: A letter from Mr. A. R. Wilson stated
that they are presently reentering the organotin market but on a limited
scale and that, since they are not basic in tin chemicals, no disposal
or effluent problem exists at the present time.
25
-------
M&T Chemicals, Inc.; The Carrollton, Kentucky, facility produces
compounds only by the Grignard method. In addition to the alkyltin com-
pounds of interest to this report, tricyclohexyl and triphenyltin com-
pounds are also manufactured at this site. Atithe present time, the site
has a settling pond and an aerated lagoon to treat the 0.75 MGD of waste-
water. New facilities for a wastewater treatment process, consisting of
the following unit operations; equalization, neutralization, clarifica-
tion, biological oxidation, and final settling, are presently under con-
struction. The future facility will treat only 0.25 MGD as several direct
uses of cooling water will be replaced with indirect, surface heat ex-
changers to reduce the volume of wastewater. ;
Although the waste materials associated with the production of al-
klytin compounds are primarily water-borne effluents, some solid waste
products are generated. Suspended tin solids result from the hydrolysis
of stannic chloride during the initial wash of the tetraalkyltins and
from the centrifuge process during the formation of alkyltin oxides from
the corresponding alkyltin chloride. These suspended tin solids are set-
tled, stored, and periodically shipped by barge to a tin smelter. During
the wash of the tetraalkyltins, some magnesium may also be included in
the suspended solids. It is not separated from the tin solids to be sent
to the smelter.
In the production of tetraoctyltins, aluminum chloride is used as
the catalyst. During the wash of the tetraoctyltin, the aluminum precipi-
tates as hydrated aluminum oxides. This thick, white mass is disposed in
a landfill.
All other waste materials resulting from the manufacturing process.
are water-borne effluents. Acidic and caustic materials, produced either
as by-products or used as processing material, are neutralized prior to
their introduction into the settling pond and aerated lagoon. M&T esti-
mates that approximately 50,000 Ib/year of organotin compounds are dis-
charged in the raw waste load. This figure includes tricyclohexyl and
triphenyltin waste compounds from other production processes.
Mooney ChemicalSi Inc.; Mooney does not manufacture organotin com-
pounds. Their products are strictly resale items.
Pennwalt Industrial Chemicals; Declined to comment on waste manage-
ment procedures. No record of any NPDES discharge permit.
i •
Synthetic Products Company; They stated that they would not provide
any information on waste management procedures. No record of any NPDES
discharge permit.
R» T. Vanderbilt Company, Inc.; Declined to comment on waste manage-
ment procedures. No record of any NPDES discharge permit.
26
-------
REFERENCES TO SECTION V
1. Bokranz, A., and H. Plum, Fortschritte der Chenu Forschung, 16:366
(1971).
2. Neumann, W. P., Ed., The Organic Chemistry of Tin. Interscience Pub-
lishers, New York (1970).
3. Kirk, R. E., and D. F. Othmer, Eds., Kirk-Othmer Encyclopedia of Chem-
ical Technology. 2nd Ed., Interscience Publishers, New York (1969).
4. Molt, K. R., and I. Hechenbleikner, British Patent 1222642 (1971).
5. Hechenbleikner, I., U.S. Patent 3792059 (1974).
6. Mack, G. P., U.S. Patent 3115509 (1963).
7. Glosky, C. R., Chem. Eng. Prog.. 58j(9), 71 (1962).
8. Metal and Thermit Corporation, British Patent 797976 (1958)j CA., 53.
3061 (1959).
27
-------
SECTION VI
PROCESS TECHNOLOGY
In this section, each of the alkyltin compounds studied during this
task is discussed individually with respect to the various aspects of its
manufacturing process and, for heat stabilizers, a tabular summary is pre-
sented with regard to the usages. Since all of the alkyltin compounds
under consideration are manufactured by one of two processes, no detailed
presentation is given with regard to the specific production process for
an individual material. A detailed discussion of the general manufacturing
processes was presented earlier in Section V.
Information relative to each alkyltin compound which is presented
in this section includes the manufacturing company's corporate address
and production site, years of production and production figures, speci-
fic preparative reaction, raw materials, type or grade of products, and
transportation and handling information.
GENERAL PRODUCTION CAPACITY
The estimated capacity for each manufacturer of alkyltin compounds
is given in Table 3. Since all of the Grignard production facilities are
multipurpose plants, a production capacity for a specific ester cannot
be provided but will vary considerably dependent upon demand for a spe-
cific ester during the year. Under the heading of production years, the
year 1965 does not denote that the facility began production in that year
but rather that 1965 was the earliest year for the purposes of this re-
port.
The estimated production capacity for M&T Chemicals of 20 million
pounds per year (9.1 x 10^ MT) takes into consideration their capacity
for the production of biocidal agricultural chemicals. If the capacity
for these materials is eliminated, a figure of 15 million pounds per year
(6.8 x 10-^ MT) would be applicable to the manufacture of compounds used
as heat stabilizers. M&T produces all of their materials by the Grignard
process.
28
-------
Table 3. ESTIMATED PRODUCTION CAPACITIES-
a/
to
vO
Manufacturer
M&T Chemicals, Inc,
Cincinnati Milacron
Chemicals, Inc.
Argus Chemical Company
Cardinal Chemical Company
Synthetic Products Company
Tenneco Chemicals Company
Ferro Chemical Company
R. T. Vanderbilt
Site
Carrollton, Kentucky
Reading, Ohio
Brooklyn, New York
Taft, Louisiana
Columbia, South Carolina
Cleveland, Ohio
Piscataway, New Jersey
Bedford, Ohio
Norwalk, Connecticut
Production years
1965-present
1965-present
1966-present
1970-present
1965-present
1971-present
Late 1969-present
1971-present
1974-present
Estimated capacity"
20
15
8
5
1
1
1.5
< 0.5
b/
_a/ Production capacities for alkyltin end products only.
b/ Current capacity in million pounds per year.
-------
Argus Chemical Company has transferred the majority of their produc-
tion capacity to the facility at Taft, Louisiana. The remaining facili-
ties at the Brooklyn, New York, site are primarily for the production of
dibutyltin oxide and presently represent a capacity of 0.5 to 1 million
pounds per year. Within the past year, Argus announced a direct methyl-
tin process at their Taft production site.
Ferro Chemical Company produces organotin compounds from the alkyl-
tin oxide or tetrabutyltin intermediates purchased from sources in the
U.S. or foreign countries. They react the intermediates with appropriate
other materials to produce the alkyltin esters. This same information also
applies to R. T. Vanderbilt, except that it is not known from which pro-
ducer they purchase their materials. They are basically resellers but do
have a very small capacity for making organotins.
Cincinnati Milacron Chemical is the largest producer of methyltin
compounds and thus their production facilities are primarily centered on
the direct process. However, they have some capacity for production of
alkyltin compounds other than methyltins.
Synthetic Products Company produces all of their compounds from the
oxide, which they purchase either in the U.S. or from Germany. They may
purchase some compounds for resale.
Tenneco Chemicals Company produces organotin compounds basically for
captive uses but some materials are for resale.
In addition to the manufacturers, there are some companies who strictly
purchase materials for resale. Two of these companies are Stecker Chemical
Company, Ho-Ho-Kus, New Jersey, and Mooney Chemical Company, Franklin,
Pennsylvania. Stecker purchases and resells only biocidal compounds, whereas
Mooney handles basically heat stabilizer compounds. Both of these companies
are very minor factors in the overall market.
SPECIFIC OKGANOTIN COMPOUNDS
In this subsection, each organotin compound will be reviewed with re-
spect to its method of production, manufacturers, raw materials utilized,
waste products, trade names and production quantities.
With respect to the trade names of the numerous alkyltin compounds,
there are a few basic compounds with the remainder being blends or varia-
tions of these materials. The basic compounds and their respective trade
names are shown in Table 4. In this listing, only those companies consid-
ered to be major factors in the market are listed; trade names for mate-
rials produced by lesser companies are given in the discussion of the
individual compounds.
30
-------
Table 4. TRADE NAMES OF COMMON ALKYLTIN COMPOUNDS
Producers
Chemical
Butyltin alkylmercaptoace-
tate
Dibutyltin bis (laurylmer-
captide)
Dibutyltin maleate ester
Dibutyltin dilaurate
Methyltin alkylmercaptoace-
tates
M&T
THERMOLITE 31
THERMOLITE 66
THERMOLITE 73
THERMOLITE 310
THERMOLITE 20
THERMOLITE 25
THERMOLITE 26
THERMOLITE 12
THERMOLITE 106
Argus
MARK 292
MARK 534B
MARK 649A
MARK A
MARK 275
MARK 693
MARK 1038
MARK 1900
MARK 1920
Cincinnati
Milaceon
ADVASTAB TM-180
ADVASTAB TM-220
ADVASTAB TM-918
ADVASTAB T-52N
ADVASTAB T-150
DBTDL
ADVASTAB TM-181
ADVASTAB TM-181FS
Cardinal
No. 11
CC-54
CC-78
CC-10
CC-200
CC-1
-
ADVASTAB TM-387
Di(n-octyl)tin-S,S'-bis(iso-
octylmercaptoacetate)
Di(n-octyl)tin maleate
polymer
Bis(tributyltin)oxide
Tributyltin fluoride
THERMOLITE 831
THERMOLITE 813
BioMET TBTO
BioMET tributyl-
tin fluoride
MARK OTM
MARK OTS
CAR-BAN T-0
QCTYL 11
-------
In addition to those compounds shown in Table 4, there are numerous
other materials offered by each company. Such materials are blends of the
basic compounds with antioxidants, synergists, extenders, and other addi-
tives. For compounds having alkyl ester groups, quantities of esters with
larger or smaller alkyl groups may be added to change the final viscosity
of the mixture or to slightly alter the properties of the blend to satisfy
the requirements of specific customers. All of the blending components and
the actual composition of the final mixture are considered proprietary by
each manufacturer. In materials such as high efficiency heat stabilizers,
other organotin compounds, i.e., butylthiostannoic acid or anhydride (BTSA)
and dibutyltin sulfide, are used in combination with the basic compounds
to increase the tin content, improve performance, and modify the physical
properties. Again, the actual composition of these mixtures are proprietary
with each company.
32
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BUTYLTIN ISOOCTYLMERCAPTOACETATES
Sn(SCH2C02C8H17)y
Production Quantities
Year
M&T
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1.5
1.8
2.1
2.7
3.2
3.6
3.6
5.5
5.5
5.4
-
0.5
0.6
0.7
0.7
0.7
0.7
1.0
1.2
1.1
x = 1 or 2
Cincinnati
Milacron
0.3
1.1
1.1
1.8
2.2
3.0
2.9
2.0
1.0
0.5
y = 2 or 3
Cardinal
0.5
1.1
1.1
1.0
1.0
1.0
1.0
2.0
2.4
2.3
Total quantity
(million Ib)
2.3
4.6
4.9
6.2
7.1
8.3
8.2
10,5
10.1
9.3
Butyltin isooctylmercaptoacetates are usually mixtures of the raono-
and dibutyl compounds. The ratio is variable depending upon the specific
customer and the specific use of the material; however, the most common
mono:di ratio is 40:60. Other alkyl groups are often used in place of the
isooctyl to change the viscosity of the final mixture.
Manufacturers
Manufacturer
M&T Chemicals,
Inc.
Argus Chemical
Corporation
Cincinnati
Milacron
Cardinal Chemi-
cal Company
Corporation
office site
Rahway, New Jersey
Brooklyn, New York
Reading, Ohio
Columbia, South
Carolina
Produetion site
Years
produced
Carrollton, Kentucky 1965-
Brooklyn, New York
Taft, Louisiana
Reading, Ohio
Columbia, South
Carolina
present
1966-1969
1970-
present
1965-
present
1965-
present
33
-------
Production Process
C4H9SnCl3 + 3 HSCH2C02C8H17 —> C4H9(SCH2C02C8H17)3 + 3 HC1
I
(C4H9)2 SnCl2 + 2 HSCH2C02CgH17 —> (C^^CSCH^CgH^^ + 2 HC1
The weight ratio of the starting materials are adjusted to produce
a final product having a 60:40 weight ratio of di:mono.
Required Raw Materials
Basis; 2,000 Ib of 60:40 weight ratio di:mono butyltin isooctyl-
mercaptoacetate
C4H9SnCl3: 286 Ib
(C4H9)2SnCl2: 567 Ib
HSCH_C00CQH._: 1,391 Ib
/ / o i/
Waste Material Produced
HC1: 244 Ib
Energy Consumed
Gas: 1,000 cu ft; Steam: 6,000 Ib; Electricity: 125 kw-hr
Price History
Year Price/lb ($) Value (million dollars)
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
2.25
2.25
2.00
1.80
1.80
1.75
1.67 (avg.)
1.40
1.50
2.06 (avg.)
5.175
10.350
9.800
11.600
12.780
14.525
13.694
14.700
15.150
19.158
34
-------
Trade Names (not included in Table 4)
Synthetic Products, Inc.: 1001
Tenneco Chemicals: Nuostabe V-1562, V-1902
Ferro Chemical Company: Ferro 803, 807, 814, 820, 832, 835, 837,
840, 871, 873, 876A, 877
Physical Properties
Physical form: Clear pale yellow liquid
Specific gravity at 25°C: 1.115 to 1.135
Refractive index at 25°C: 1.5071
Estimated Consumption By Use Area (million pounds)
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Pipe and
conduit
1.08
3.05
2.91
3.67
3.65
3.62
3.05
4.25
3.68
3.32
Injection
molding
0.20
0.19
0.37
0.47
0.68
0.88
1.00
1.12
1.26
1.08
Siding and
profiles
0.54
0.72
0.85
1.01
1.14
1.69
1.97
2.61
2.68
2.41
Bottles
0.10
0.19
0.29
0.39
0.56
0.78
0.72
0.88
0.94
0.92
Sheet and
film
0.35
0.42
0.49
0.65
1.10
1.33
1.43
1.59
1.54
1.53
Total
2.27
4.57
4.91
6.19
7.13
8.30
8.17
10.45
10.10
9.26
35
-------
DIBUTYLTIN-BIS(LAUHYLMERCAPTIDE)
Production Quantities
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
M&T
0.7
0.5
0.4
0.4
0.4
0.4
0.4
0.5
0.5
0.5
Argus
l—
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Cincinnati
Milacron
0.1
0.1
0.2
0.2
0.2
0.2
0.1
0.1
-
-
Cardinal
0.2
0.3
0.2
0.2
0.2
0.4
0.5
0.6
0.7
0.7
Total quantity
(million Ib)
1.0
1.0
0.9
0.9
0.9
1.1
1.1
1.3
1.3
1.3
Manufacturers
Manufacturer
M&T Chemicals,
Inc.
Argus Chemical
Corporation
Cardinal Chemi-
cal Company
Cincinnati
Milacron
Corporation
office site
Production site
Years
produced
Rahway, New Jersey
Brooklyn, New York
Carrollton, Kentucky 1965-
present
Brooklyn, New York 1966-1969
Taft, Louisiana 1970-
present
Columbia, South Carolina Columbia, South 1965-
Carolina present
Reading, Ohio Reading, Ohio 1965-1972
Production Process
(C4H9)2Sn(SC12H25)2 + 2 HC1
* y-z i + 2 C12H25SH * VW2°"WVJ121125'
Required Raw Materials
Basis; 2,000 Ib of dibutyltin bis(laurylmercaptide)
(C4H9)2SnCl2: 956 Ib
°12H25SH: 1>274 lb
36
-------
Waste Material Produced
HC1: 230 Ib
Energy Consumed
Gas: 1,000 cu ftj Steam: 6,000 Ib; Electricity: 125 kw-hr
Price History
Year Price/lb ($) Value (million dollars)
2.250
2.250
2.025
2.025
2.025
2.475
2.475
3.250
3.380
3.575
Trade Names (not included in Table 4)
Ferro Chemical: Ferro 822
Physical Properties
Physical form: Clear pale liquid
Specific gravity at 25°C: 1.006
Refractive index at 25°C: 1.498
Viscosity at 25°C: 22 centipoises
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
2.25
2.25
2.25
2.25
2.25
2.25
2.25
2.50
2.60
2.75
37
-------
Estimated Consumption by Use Area (million pounds)
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Pipe and
conduit
0.88
0.87
0.75
0.74
0.63
0.70
0.53
0.56
0.55
0.64
Injection
molding
0.03
0.03
0.06
0.08
0.12
0.16
0.19
0.22
0.25
0.20
Siding and
profiles
i
0.10
0.11
0.11
0.12
0.15
0.27
0.37
0.52
0.54
0.46
Total
1.01
1,01
0.92
0.94
0.90
1.13
1.09
1.30
1.34
U30
38
-------
DIBUTYLTIN MALEATE ESTERS
(C4H9
R = C H is the most
common, however, other
alkyl groups ranging from
C2 t0 C12 are
Production Quantities; Octylmaleate ester
Year
M&T
Cincinnati
Milacron
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
0.04
0.04
0.05
0.03
0.04
0.04
0.04
0.05
0.05
0.04
-
-
-
0.03
0.04
0.04
0.04
0.04
0.04
0.04
Cardinal
0.01
0.02
0.02
0.02
0.02
0.02
0.02
Total quantity
\rgus (million Ib)
0.04
0.04
0.05
0.01 0.08
0.01 0.11
0.01 0.11
0.01 0.11
0.01 0.12
0.01 0.12
0.01 0.11
Other alkylmaleate esters have been produced from 1965 to 1974. Aside
from the octylmaleate esters, probably the most common alkylmaleate esters
were the C-^, C^ and C^ groups. It is believed that each of these materi-
als is produced by only one company so that specific information is diffi-
cult to obtain. MRI estimates the following production years and annual
quantities for each of the alkylmaleates: C3H7 (1965 to 1971, 50,000 to
330,000 Ib); C4H9 (1965 to 1974, 50,000 to 100,000 lb)j C12H25 (1967 to
1974, 40,000 to 90,000 Ib). Dibutyltin maleate was also produced in small
quantities (25,000 to 50,000 Ib annually) from 1965 to 1971. All of the
above dibutyltin alkylmaleates, except for octyl, find usage in semi-rigid,
calendered PVC applications, such as fiber stabilization, flexible plastic
strips, etc. The estimated total annual production of these alkylmaleate
esters have been included with the data for the octylmaleates and presented
in Table 1.
39
-------
Manufacturers
Manufacturer
Argus Chemical
Corporation
M&T Chemicals,
Inc.
Cardinal Chemi-
cal Company
Cincinnati
Milacron
Production Process
Corporation
office site
Brooklyn, New York
Production site
Years
produced
Brooklyn, New York
Taft, Louisiana
Rahway, New Jersey
Columbia, South
Carolina
Reading, Ohio
1968-1969
1970-
present
Carrollton, Kentucky 1965-
present
Columbia, South 1968-
Carolina present
Reading, Ohio 1968-
present
00 00
(C,Hj0SnO + 2 HOCCH=CHCOC0H, , —> (C.Hrt)0Sn(OCCH=CHCOC0H1 _),
4 9'2
Required Raw Materials
8 17
4 9'2
8 17'2
Basis; 2,000 Ib of dibutyltin octylmaleate ester
(C4H9)2SnO: 724 Ib
_
I/
: 1,328 Ib
Waste Material Produced
Water: 52 Ib
Energy Consumed
Gas: 1,000 cu ft; Steam: 7,000 Ib; Electricity: 167 kw-hr
NIOSH Standards
LD5() = 284 mg/kg (oral-rat)
Trade Names (not included in Table 4)
Ferro Chemical: Ferro 832, 835, 837
Tenneco Chemicals: Nuostabe V-1525
40
-------
Price History
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Physical Properties
Price/lb ($)
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.35
2.60-3.00
Value (million dollars)
0.080
0.080
0.100
0.160
0.220
0.220
0.220
0.240
0.282
0.308 (avg.)
Physical form: Clear, pale liquid
Specific gravity at 25 °C: 1.230
Viscosity at 25 °C: 140 centipoise
Estimated Consumption of Dibutyltin Maleate Esters by Area
(million pounds
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Bottles
0.01
0.01
0.02
0.05
0.06
0.06
0.04
0.05
0.06
0.05
Sheet and
film
0.03
0.03
0.03
0.03
0.05
0.05
0.07
0.07
0.06
0.06
Total
0.04
0.04
0.05
0.08
0.11
0.11
0.11
0.12
0.12
0.11
41
-------
DIBUTYLTIN DILAURATE
0
Production Quantities
Year M&T Argus
Cincinnati
Milacron
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
0.3
0.3
0.3
0.3
0.4
0.5
0.6
0.5
0.7
0.7
Manufacturers
Manu facturer
0.1
0.1
0.1 0.1
Corporation
office site
Cardinal
0.05
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Total quantity
(million Ib)
0.3
0.3
0.35
0.4
0.5
0.6
0.7
0.7
0.9
1.0
Rahway, New Jersey
Brooklyn, New York
Reading, Ohio
Production site
Carre11ton, Kentucky
Taft, Louisiana
Reading, Ohio
Columbia, South
Carolina
Years
produced
1965-
present
1974-
present
1972-
present
1967-
present
M&T Chemicals,
Inc.
Argus Chemical
Corporation
Cincinnati
Mi lacron
Cardinal Chemi- Columbia, South
cal Company Carolina
Production Process
Bu2SnO
Dibutyltin dilaurate is a liquid or low melting solid, depending on
the type and purity of the lauric acid used in the preparation.
42
-------
Required Raw Materials
Basis; 2,000 Ib of dibutyltin dilaurate
)2SnO: 789 Ib
C11H23C°2H: Ij27° lb
Waste Materials Produced
Water: 59 lb
Energy Consumed
Gas: 1,000 cu ft; steam: 7,000 lb; Electricity: 167 kw-hr
NIOSH Standards
LD = 243 mg/kg oral-rat
Price History
Year Average price/ lb ($) Value (million dollars)
1965 2.00 0.600
1966 2.00 0.600
1967 2.00 0.700
1968 2.00 0.800
1969 1.75 0.875
1970 1.75 1.050
1971 1.75 1.225
1972 1.75 1.225
1973 2.00 1.800
1974 2.43 2.430
Trade Names (not included in Table 4)
Ferro Chemical: Ferro 820
Physical Properties
Physical form: Oily liquid; low melting solid
Specific gravity at 25 °C: 1.04
Refractive index at 20°C: 1.471
43
-------
Boiling point: 205°C at 10 mm
Freezing point: 4°C
Melting point: 22 to 27°C
Viscosity at 25°C: 42 centipoise
Solubility: H20 - insoluble
benzene - soluble
acetone - soluble
44
-------
METHYLTIN ISOOCTYLMERCAPTOACETATES
x=lor2 y = 2or3
Production Quantities
Total quantity
Year Cincinnati Milacron Argus (million Ib)
1970 0.7 - 0.7
1971 1.4 - 1.4
1972 2.6 0.3 2.9
1973 3.6 0.4 4.0
1974 3.5 1.0 " 4.5
Methyltin isooctylmercaptoacetates are usually mixtures of the mono-
and dimethyl compounds. The ratio is somewhat variable depending upon the
specific customer and the specific use of the material; however, the most
common monordi ratio is 40:60.
Methyltin compounds were not new compounds when introduced commer-
cially in 1970. Some quantities had been sold commercially in 1959 to 1960
but, due to problems with the trimethyl compounds as impurities, the prod-
uct was removed from the market. By using the "direct" synthesis, the pro-
ducers are able to reduce the trimethyltin impurity to less than 0.5%.
Commercial formulations began as the dimethyl compounds and have been
progressing to blends with an increasing monomethyltin content.
Manufacturers
Corporation Years
Manufacturer office site Production site produced
Argus Chemical Brooklyn, New York Taft, Louisiana 1972-
Corporation present
Cincinnati Reading, Ohio Reading, Ohio 1970-
Milacron present
Production Process
XLC,,H,,K + 3 HC1
—> (CH3)2Sn(SCH2C02C8H17)2 + 2 HC1
45
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The weight ratio of the starting materials are adjusted to produce
a final product having a 60:40 weight ratio of di:mono.
Required Raw Materials
Basis; 2,000 Ib of 60:40 di:mono methyltin isooctylmercaptoacetate
CH3SnCl3: 257 Ib
(CH3)2SnCl2: 471 Ib
HSCH.CO-C-H,..: 1,540 Ib
£• £. O 1 /
Waste Materials Produced
HC1: 268 Ib
Energy Consumed (estimated)
Gas: 300 cu ft; Steam: 0; Electricity: 33 kw-hr
Price History
Year
1970
1971
1972
1973
1974
Price/ Ib ($)
1.84
1.84
1.84
1.84
2.26 (avg.)
Value (million dollars)
1.288
2.576
5.336
7.360
10.170
Physical Properties
Physical form: Clear water white liquid
Specific gravity at 25°C: 1.177
Refractive index at 25°C: 1.5106
Viscosity at 25°C: 50 centipoise
46
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Estimated Consumption by Use Area (million pounds)
Pipe and Injection Siding and Sheet and
Year conduit molding profiles Bottles film Total
1970 0.43 0.06 0.10 0.04 0.04 0.67
1971 0.97 0.09 0.21 0.09 0.07 1.43
1972 2.14 0.13 0.45 0.10 0.09 2.91
1973 2.85 0.21 0.69 0.11 0.09 3.95
1974 3.31 0.24 0.70 0.12 0.09 4.46
47
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DI(n-OCTYL)TIN-S,S'-BIS(ISOOCTYLMERCAPTOACETATE)
Production Quantities
Year
M&T
Cincinnati
Milacron
1968
1969
1970
1971
1972
1973
1974
0.16
0.20
0.32
0.30
0.50
0.50
0.27
-
-
-
0.05
0.05
0.05
0.05
0.02
0.01
0.07
0.05
Total quantity
(million Ib)
0.16
0.20
0.32
0.37
0.56
0.62
0.37
According to FDA regulations, this compound must have 15.1 to 16.4%
by weight of tin and 8.1 to 8.9% by weight of mercapto sulfur. It is made
from di(n-octyl)tin dichloride having an organotin composition that is
not less than 95% by weight di(n-octyl)tin dichloride, not more than 5%
by weight total of _n-octyltin trichloride and/or tri(n-octyl)tin chloride,
not more than 0.2% by weight total of other eight carbon isomeric alkyltin
derivatives, and not more than 0.1% by weight total higher and lower homo-
logous alkyltin derivatives. In actuality, the di(n-octyl)tin dichloride,
meeting the above specifications, is converted to the oxide prior to the
ester formation.
Manufacturers
Manufacturer
M&T Chemicals,
Inc.
Argus Chemical
Corporation
Cincinnati
Milacron
Production Process
Corporation
office site
Production site
Rahway, New Jersey Carrollton, Kentucky
Brooklyn, New York Brooklyn, New York
Reading, Ohio Reading, Ohio
Years
produced
1968-
present
1971-
present
1971-
present
48
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Required Raw Materials
Basis; 2,000 Ib of di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate)
(n-C8H17)2SnO: 961 Ib
HSCH-CO.C-H...: 1,087'Ib
(. /.oil
Waste Material Produced
H20: 48 Ib
Energy Consumed
Gas: 1,000 cu ft; Steam: 7,000 Ib; Electricity: 167 kw-hr
NIOSH Standards
LD = 2,010 mg/kg (oral-mus.)
Price History
Year Price/lb ($) Value (million dollars)
1968 2.75 0.440
1969 2.75 0.550
1970 2.75 0.880
1971 2.75 1.018
1972 2.65 1.484
1973 2.81 1.742
1974 3.55 1.314
Physical Properties
Physical form: Clear yellow liquid
Specific gravity at 25°C: 1.085
Refractive index at 25°C: 1.5005
Solubility: Soluble in esters, ethers, ketones, alcohols, aliphatic
and aromatic hydrocarbons, chlorinated hydrocarbons,
and other organic solvents.
Insoluble in water.
49
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Estimated Consumption by Use Area (million pounds)
Year
1968
1969
1970
1971
1972
1973
1974
Bottles
0.02
0.04
0.06
0.07
0.16
0.15
0.09
Sheet and
film
0.14
0.16
0.30
0.30
0.40
0.47
0.28
Total
0.16
0.20
0.32
0.37
0.56
0.62
0,37
50
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DI(n-OCTYL)TIN MALEATE POLYMER
00
•£(n-C0H1,).SnOCCH=CHC09- n = 2 to 4
o 1 / i n
Production Quantities
Total quantity
Year M&T (million Ib)
1968 0.02 0.02
1969 0.03 0.03
1970 0.05 0.05
1971 0.06 0.06
1972 0.08 0.08
1973 0.08 0.08
1974 0.07 0.07
According to FDA regulations, the polymer must have 25.2 to 26.6%
by weight tin and a saponification number of 225 to 255. It is made from
di(n-octyl)tin dichloride meeting the same specifications described ear-
lier for the di(n-octyl)tin-S,Sl-bis(isooctylmercaptoacetate). In actual-
ity, the di(n-octyl)tin dichloride is converted to the corresponding oxide
prior to formation of the maleate polymer.
Manufacturers
Corporation Years
Manufacturer office site Production site produced
M&T Chemicals, Rahway, New Jersey Carrollton, Kentucky 1968-
Inc. present
Production Process
00 00
II II r || || n
(n-CH, ),,SnO + HOCCH=CHCOH —> L(n-C0H1 ^)-SnOCCH=CHCOj + 2 H.O
o L.I / o 1 / f. n 2.
n = 2 to 4
51
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Required Raw Materials
Basis: 2,000 Ib of di(ji-octyl)tin maleate polymer
(n-C0H17)0SnO: 1,573 Ib
O 1 / L. .
00
HOCCH=CHCOH: 505 Ib
Waste Material Produced
Water: 78 Ib
Energy Consumed
Gas: 1,000 cu ft; Steam: 7,000 Ib; Electricity: 167 kw-hr
Price History
Year Price/Ib ($) Value (million dollars)
1968
1969
1970
1971
1972
1973
1974
Physical Properties
3.15
3.15
3.15
3.15
3.15
3.33
4.06 (avg.)
0.063
0.095
0.158
0.189
0.252
0.266
0.284
Physical form: Powder
Specific gravity at 25°C: 1.33
Estimated Consumption by Use Area (million pounds)
Year
1968
1969
1970
1971
1972
1973
1974
Bottles
0.003
0.004
0.010
0.012
0.027
0.027
0.016
Sheet and
film
0.01
0.02
0.03
0.05
0.05
0.05
0.05
Total
0.01
0.02
0.04
0.06
0.08
0.08
0.07
52
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MIXED METALS
These mixtures were introduced in 1973 primarily to compete in the
rigid PVC pipe and conduit market* They consist of mixtures of the stan-
dard dimethyl or dibutyltin isooctylmercaptoacetates with calcium or bar-
ium salts of phenols, cresols, 2-ethylhexanoic acid, or other long-chain
branched acids. Newer mixed metals have also incorporated strontium* The
most common mixture probably consists of the barium phenolate with one
of the alkyltin compounds in a 50:50 mixture ratio.
It is estimated that in 1973, approximately 0.8 million pounds of
the mixture were consumed; by 1974 the consumption had decreased to about
0.5 million pounds. These mixtures are offered by all of the alkyltin pro-
ducers in varying ratios of calcium to barium and in different mixture
ratios with the alkyltin compounds depending upon the specific end use
of the compounded PVC resin. The price of these mixtures has risen from
$1.08/lb in 1973 to the current price of $1.89/lb.
The major manufacturers of mixed metals are Argus Chemicals, Ferro
Chemical, and Synthetic Products. In 1973, the production quantities are
estimated at Synthetic Products: 0.4 x 10^ Ib, Ferro: 0.1 x 106, and
Argus: 0.3 x 10^ Ib. For 1974, the estimated quantities are Synthetic
Products: 0.2 x 106 Ib, Argus: 0.2 x 106 Ib. and Ferro: 0.1 x 106 Ib.
53
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BIS(TRIBUTYLTIN) OXIDE
U.S. Production Quantities
Year
Total quantity (million Ib)
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
0.50
0.50
0.10
0.10
0.15
0.17
0.20
0.25
0.30
0.50
The above figures are the estimated U.S. production; however, quan-
tities of this material are imported.
Manufacturers
Manufacturer
Corporation
office site
Production site
Years
produced
M&T Chemicals,
Inc.
Rahway, New Jersey
Carrollton, Kentucky 1965-
present
Production Process
2 (C4H9)3SnCl + 2 NaOH
Required Raw Materials
+ 2 NaCl +
Basis; 2,000 Ib of bis(tributyltin) oxide
(C4H9)3SnCl: 2,185 Ib
NaOH: 628 Ib
Waste Materials Produced
NaCl: 392 Ib
H20: 61 Ib
54
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Energy Consumed
Gas: 1,000 cu ft; Steam: 6,200 Ib; Electricity: 135 kw-hr
NIOSH Standards
LD5Q = 194 mg/kg (oral-rat)
LD5Q = 7 mg/kg (ipr-rat)
Price History
Year Price/Ib ($) Value (million dollars)
1965 3.15 1.575
1966 3.15 1.575
1967 3.15 0.315
1968 3.15 0.315
1969 2.90 0.435
1970 2.90 0.493
1971 2.90 0.725
1972 2.90 0.725
1973 3.22 (avg.) 0.966
1974 4.06 (avg.) 2.030
Physical Properties
Physical form: Colorless to slightly yellow liquid
Specific gravity at 20°C: 1.17
Refractive index at 20°C: 1.486 to 1.488
Boiling point: 210 to 214°C at 10 mm
Freezing point: -45°C
Viscosity at 20°C: 9 centipoise
Solubility: Soluble in organic solvents, insoluble in water.
55
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TKEBUTYLTIN FLUORIDE
U.S. Production Quantities
Year
Total quantity (million Ib)
1970
1971
1972
1973
1974
0.01
0.03
0.05
0.08
0.12
The above figures are the estimated U.S. production; however, quan-
tities of this material are imported.
Manufacturers
Manufacturer
M&T Chemicals,
Inc.
Production Process
Corporation
office site
Production site
Rahway, New Jersey CarrolIton, Kentucky
Years
produced
1970-
present
NaF
NaCl
Required Raw Materials
Basis; 2,000 Ib of tributyltin fluoride
(C H9) SnCl: 2,106 Ib
NaF: 272 Ib
After completion of the reaction, the product is centrifuged to form
a wet cake (containing up to 40% water) and stored in this form. Immedi-
ately prior to packaging, the wet cake is thoroughly dried. The dried pow-
der will absorb moisture if allowed to remain open to the atmosphere.
Waste Material Produced
NaCl: 378 Ib
56
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Energy Consumed (estimated)
Gas: 1,000 cu ft; Steam: 7,400 Ib; Electricity: 146 kw-hr
Price History
Year Price/Ib ($) Value (million dollars)
1970
1971
1972
1973
1974
3.20
3.20
3.20
3.47 (avg.)
4.54 (avg.)
0.032
0.096
0.160
0.278
0.545
Physical Properties
Physical form: White powder
Melting point: 240°C (decomposition)
Solubility: Slightly soluble in inorganic solvents. Insoluble in
water.
57
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HANDLING AND TRANSPORTATION
All of Che alkyltin compounds in this study, including those with
biocidal applications, are eye and skin irritants and can cause irrita-
tion of the upper respiratory tract*!' The most common result of contact
with these materials is a skin rash of rather short duration. In case of
eye contact, a rather severe irritation and reddening of the eye can oc-
cur. For workers contacting these materials, either in production facili-
ties, PVC compounding plants, or shipyards, it is recommended that these
personnel wear eye goggles, rubber gloves, longsleeved coveralls, and,
depending upon the product, dust masks* In all cases, good ventilation
should be provided to remove fumes and powder.
For workers spraying organotin paints, a full-face, air-supplied
respirator is recommended in addition to the above precautions^' Other
personnel working within a 25 ft radius or within 100 ft downwind of the
spray should be protected in a similar manner. These footage figures ob-
viously should be modified depending upon atmospheric conditions, partic- .
uiarily wind velocity.
The revised Section 311-(b)(2)(B) of the Federal Water Pollution Con-
trol Act Amendments of 1972 (Federal Register. August 22, 1974) does not
list any of the selected organotin compounds as being hazardous substances.
The Code of Federal Regulations, Title 49, Transportation (October 1, 1973)
does not list alkyltin compounds as being hazardous materials and requires
no special labeling or handling of the shipping containers. Bis(tributyl-
tin) oxide and tributyltin fluoride are registered with the Environmental
Protection Agency, Office of Pesticides and, as such, each container of
active ingredient or antifouling paint, containing the active ingredient,
must have appropriate directions for its use, accidental contact, and dis-
posal of the container. In addition, each container of antifouling paint
must clearly show a label analysis.
When packaged for shipment, the alkyltin compounds are normally avail-
able in 55 gal. drums. Larger quantities are available by tanktruck deliv-
ery if desired. Smaller quantities are also available at increased cost.
For users, one common method of storage is in 250, 300 or 350 gal. cubic
stainless steel containers, fitted with automated pumping and metering
devices.
58
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REFERENCES TO SECTION VI
1. Sheldon, A. W., J. Paint Technology. 47^ 54 (1975).
2. Engelhart, J. E., and A. W. Sheldon, 15th Annual Marine Coatings Con-
ference, Point Clear, Alabama, February 1975,
59
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SECTION VII
AREAS OF UTILIZATION
In this section, the specific uses will be discussed for each of the
organotin compounds listed in Section VI. The principal areas of heat stab-
ilizers for poly(vinyl chloride), urethane and silicone catalysts, and bio-
cidal applications will be discussed as separate subsections. Minor use
areas will be discussed separately but under the general heading of mis-
cellaneous uses.
The overall consumption of organotin compounds has not changed to any
appreciable extent during the past 10 years* Heat stabilization of rigid
poly(vinyl chloride) has accounted for 85 to 90% of the domestic consump-
tion of the selected organotins. Catalytic, biocidal, anthelmintic, and
other uses have accounted for the remaining: 10 to 15%. During this same
time interval, exportation remained fairly constant at 4 to 5% of the to-
tal annual production.
A cursory look at the numerous current review articles on organotin
compounds reveals several applications in the catalyst and biocidal areas;
however, most of these applications, as discussed later in this section,
consume relatively small quantities of organotin compounds.
HEAT STABILIZERS FOR POLY(VINYL CHLORIDE)
This area represents, by far, the major usage of the mono- and di-
alkyltin compounds. Within the scope of this subsection, their utiliza-
tion with certain copolymers will be included; therefore this area is not
strictly for poly(vinyl chloride).
The most widely accepted viewpoint of PVC breakdown relates to a de-
hydrochlorination reaction at the allylic or tertiary chlorine site with
the formation of a double bondw=' As tihe degradation continues, the devel-
opment of a chromophoric conjugated structure occurs which leads to color
formation. Poly(vinyl chloride) will show a black coloration when as little
as 0.1% of the polymer decomposes. The dehydrochlorination reaction is auto-
catalytic and is further accelerated by the presence of oxygen and contami-
nants, such as iron, residual polymer catalysts, or suspension agents. To
60
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prevent color formation and preserve the appearance of the compound, the
primary approach is to inhibit the formation of the conjugated double
bonds by the addition of stabilizers, which will also reduce the effect
of any catalytic components. For additional information with regard to
PVC degradation and the mechanism of stabilization, see Ref. 2.
In the processing of unplasticized PVC resin, temperatures are at-
tained which are well in excess of the initial temperature required for
the degradation process to be initiated. The principal means of process-
ing rigid poly(vinyl chloride) is by extrusion and, depending upon the
final use of the plastic, extrusion processes occur either by a single
screw or a double (or multi) screw extruder. In single screw extruders,
processing temperatures reach up to 205 to 215°C whereas with multi-screw
machines, the temperature may reach 190 to 195°C»^' At these temperatures,
the use of a heat stabilizer is mandatory to produce a clear product.
Mono- and dialkyltin mercaptoesters are the most effective of the metal-
lic stabilizersj:/
Estimated U.S. consumption of organotin compounds as heat stabiliz-
ers for rigid and semi-rigid poly(vinyl chloride) and copolymers is shown
in Table 5.
There are two factors which must be considered, respective to the
quantity of material consumed as heat stabilizers.
1. The production of rigid and semi-rigid PxC products has risen
tremendously over the past 10 years from approximately 181 million pounds
in 1965^/ to over an estimated 1,700 million pounds in 1975 Ji/
2. During the same time interval, the use of multiscrew extruders,
which use up to 40% less heat stabilizers, began to replace single screw
extruders. In 1965, it was estimated that 957o of all extrusion was using
single screw machinery but by 1974, this figure had dropped to approxi-
mately 25% single screw and 75% multi-screw£' Thus a situation exists in
which a large increase in the production of rigid poly(vinyl chloride) has
occurred but at the same time, the advent of new processing machinery has
decreased the required quantity of heat stabilizers per pound of PVC.
The major organotin compounds which have been utilized over this 10
year time interval are as follows:
* Mono- and dimethyltin isooctylmercaptoacetates
* Mono- and dibutyltin isooctylmercaptoacetates
* Dibutyltin-bis(laurylmercaptide)
* Dibutyltin-bis(alkylmaleate esters)
* Di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate)
* Di(n-octyl)tin maleate polymer
61
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Table 5. ESTIMATED CONSUMPTION OF OBGANOTIN
COMPOUNDS AS HEAT STABILIZERS
Estimated consumption (million pounds)
Year Modern Plas.ticag/
1965 (3.9>£' 3.3
1966 (4.2) 5.6
1967 (4.6) 5.9
1968 5 7.4
1969 5.7 8.3
1970 6.1 10.6
1971 7.6 11.2
1972 10.9 15.5
1973 16.7 17.0
1974 16.5 16.2
j/ Modern Plastics. McGraw-Hill, Inc., New York, September
issues.
b/ MRI estimates based on consumption data in specific use
areas and discussions with PVC resin processors and
consumers.
_c/ Estimates based on MP consumption data for subsequent
years.
62
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Dibutyltin sulfide has never been used commercially as a stabilizer by
itself but is only present as a component in blends and mixtures with
other mono- and dialkyltin compounds* Butylthiostannoic anhydride (BTSA)
has been used as a single component stabilizer only in PVC food applica-
tions and, like dibutyltin sulfide, is also a component of blends and
mixtures of other organotin compounds. The two di(n-octyl)tin compounds
have been used primarily only in PVC food applications.
Dibutyltin-bis(g-mercaptopropionate) has appeared in the literature
through the years since about 1965 and did find some usage as a highly
specialized heat stabilizer in PVC blown nonfood bottles. Its main sell-
ing point was that it did not affect the distortion point of the resin
as did the more widely used liquid mercaptoester stabilizers. Due to the
high cost of the mercaptopropionic acid, it was an expensive stabilizer
and never achieved an appreciable commercial consumption volume. The "old
line" stabilizers, such as dibutyltin dilaurate and dibutyltin maleate,
had been replaced as major heat stabilizers prior to 1965. However, in
certain highly specialized areas, they still are used to a very minor ex-
tent as heat stabilizers.
At this point, a brief chronology and description of the terminology
used with organotin heat stabilizers should be provided. This chronology
can be summarized as follows:
1965 - "standard" tin compounds
1967 - "high efficiency" tin stabilizers introduced
1968 - Dioctyltin compounds approved by FDA
1970 - "super tins" and dimethyltin compounds introduced
1972 - "mixed metal" tins introduced
1973 - First mention in the literature of "low cost straight" methyl
and butyltins.
"Standard" tins; These were the normal dibutyltin-S,S-bis(isooctyl-
mercaptoacetate), dibutyltin-bis(laurylmercaptide), dibutyltin-bis(alky1
maleate esters), and others.
"High efficiency" tins; xhis group of stabilizers was introduced
after a considerable search for lower cost, more efficient stabilizers.
They were mixtures of organotin compounds which yielded a higher tin con-
tent stabilizer. In this case, surprisingly it led to a better heat stab-
ilizer at lower use levels (2 phr versus 3 phr); however, after they had
63
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been on the market for sometime, it was found that they seem to be sheer
sensitive in the new twin screw extruders. These stabilizers were usually
a mixture of mono- and/or dibutyltin mercaptoacetates, a thiostannoic
acid or dibutyltin sulfide, and an antioxidant, usually a hindered phenol.
"Super tins"; This terminology is sometimes confused with the high
efficiency tins but, in this case, the changes in efficiency are based on
changes in the redistribution reaction to give a higher monoalkyltin con-
tent. The higher monoalkyltin content of the product led to better initial
color, clarity, and lubrication; in addition, it also had an overall lower
tin content than the "high efficiency" tins.
"Mixed metal" tins; These are mixtures of the mono- and dibutyl- or
mono- and dimethyltin-S,S-bis(isooctylmercaptoacetates) with calcium or
barium salts of phenols, cresols, or 2-ethylhexanoic acid. The most com-
mon salts are the barium phenolates. Typically, the mixed metals contain
approximately 50% organotin compounds. These materials have not achieved
a high degree of popularity.
"Low cost straight" tins; The materials are based on a mixture of
mono- and dialkyltin mercaptoacetates with a ratio of di- to mono- of ap-
proximately 60:40. These mixtures are then diluted with an inert material,
such as mineral oil or a similar diluent, to increase the bulk of the mix-
ture and provide better processing and handling for the formulators of the
PVC resin. The straight tins, with a tin content of about 11 to 12%, are
very suitable for twin screw extrusion where low stabilizer content is
used.
Actually, in Europe, materials with a ratio of 50% mono- to 50% di-
alkyltins have been used, as they give more stabilizer per pound of tin.
Increased physical properties, such as plasticizing effect and better
extrusion, can be obtained with PVC resins stabilized with an organotin
compound containing a high monoalkyl content.
In the ensuing subsections of this section, the processing technology
of heat stabilizers will be discussed, as will the various areas of utili-
zation. Within each use area, the topics of specific organotin compounds,
the quantities consumed, major users, and final products will be detailed.
PVC Process Technology
i
The method of incorporation of organotin heat stabilizers into PVC
resin is basically the same as for the incorporation of any other additive
to the resin. Liquid organotin compounds are withdrawn from bulk storage
tanks or drums through a system of metered valves to either a ribbon
blender or a high speed blender, such as the Henshel mixer. The ribbon
64
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blender is used mostly for extrusion and calendering compounds, but the
Henshel mixer is necessary for pipes and extrusions where dry blends are
used. In dry blends, very fine disintegration must occur and the stabi-
lizer must be well blended with all other ingredients. The compound is
blended in a given period of time to insure uniform distribution of the
heat stabilizer among the PVC resin particles. Any other additives, such
as lubricants, etc., are also added during this mixing process.
At the end of the mixing period, the dry blend is either piped to
an extruder or, if the dry blend is to be sold, to the packaging operation
where the formulated resin is placed in suitable containers for shipment
to their customers. Packaging can range from 80 Ib plastic-lined paper
bags to tankcars, depending upon the specific customer.
Formulated PVC resin is also sold in pelletized form. From the ribbon
blender, the resin is extruded into thin rods, which are then cut into
pellets. After pelletizing, the PVC is packaged in the same manner as the
granular resin.
In operations where the organotin heat stabilizer may be handled,
full eye goggles, rubber gloves, coverall, and a dust mask should be worn
by personnel in direct contact with these materials. Prolonged contact
with the skin can produce irritation. Contact with the eyes can produce
severe irritation. Once the heat stabilizer is incorporated into the com-
pounded resin, the resin requires no special handling other than the nor-
mal procedures.
The major PVC producers having compounding facilities as of January
1975, are listed in Table 6. These plant capacities are for all PVC not
necessarily organotin stabilized PVC. Actual stabilization would depend
upon the product being manufactured or upon the desires of specific cus-
tomers. There have been no companies who, within the last 10 years, were
major contributors to the compounding of PVC resins and subsequently with-
drew from the market.
Use in PVC Pipe and Conduit
Pipe and conduit represents the single largest area of utilization
for mono- and dialkyltin compounds. Prior to 1970, only two types of tin
compounds were used in this area, dibutyltin-S,S-bis(isooctylmercaptoace-
tate) and dibutyltin-bis(laurylmercaptide). Isooctylmercaptoacetate was
used both as the standard compound and as its "high efficiency" mixture.
The increasing usage of twin screw extruders signaled the introduction of
the methyltin compounds, which had been known for many years but offered
no advantage over the butyltin compounds. With the twin screw extruder
and its lower processing temperature, the higher tin content of the methyls
offered a significant advantage over the butyls in that less material could
65
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Table 6. MAJOR PVC COMPOUNDERS
Capacity (million pounds/year)
Company and site (as of January 1975)
B. F. Goodrich Company 1,080
Avon Lake, Ohio
Henry, Illinois
Long Beach, California
Louisville, Kentucky
Pedricktown, New Jersy
Robintech, Inc. 500
Fainesville, Ohio
Tenneco Chemicals, Inc. 450
Burlington, New Jersey
Flemington, New Jersey
Pasadena, Texas
Borden, Inc. 400
Illiopolis, Illinois
Leominster, Massachusetts
Diamond Shamrock Corporation . 400
Delaware City, Delaware
Deer Park, Texas
Ethyl Corporation 300
Baton Rouge, Louisiana
Occidental Petroleum Corporation 150
Hooker Chemical Corporation (Ruco
Division)
Burlington, New Jersey
Pantasote Company 100
Passaic, New Jersey
Point Pleasant, West Virginia
Uniroyal, Inc. 75-100
Painesville, Ohio
Sources: Modern Plastics, January 1975; Directory of
Chemical Producers, SRI.
66
-------
be used to obtain the same stabilizing effect. In addition, the higher
volatility of the methyl compounds would not present problems at the
lower processing temperatures. Since 1970, the methyltin compounds have
been used to a progressively larger extent in this particular area. In
1973, mixed metals were introduced and have found some usage in the pipe
and conduit field as shown in Table 7.
The choice of extruder used in pipe and conduit is determined by
the type of pipe to be produced. In general, for pipe over 4 in, in di-
ameter, twin screw extruders are used, while for less than 4 in, diameter
pipe, single screw machines are the choice. Extruder type also dictates
the quantity of heat stabilizer to be used, as the twin or multi-screw
requires approximately 50 to 60% less stabilizer than the single screw.
Within the area of pipe and conduit, the breakdown by final product
for 1971 to 1974 is given in Table 8. At the present time, potable water
pipe is 100% organotin stabilized. All other types of pipe are about 95%
organotin stabilized with the remainder generally being lead stabilized.
While the use of organotin compounds is necessary only for potable water
pipe, many manufacturers of this pipe also produce all of the other types.
For those, lead stabilizers can be used but in order to avoid contamination
and, hence cross-staining of the organotin by lead, separate facilities
would be necessary. For that reason, most producers who manufacture the
full range of PVC pipe and conduit will use organotin compounds through-
out their production lines.
The primary use of PVC potable water pipe is from water mains to
buildings where a large volume of H20 flow occurs and the exposure tem-
perature is lowered because the pipe is buried.
Under the recent FDA proposal (see Ref. 8), PVC water pipe would be
subject to the provisions of 121.4000 concerning food additives approved
on an interim basis. Within 60 days following the effective date of a
final regulation, an interested party would be required to show FDA that
satisfactory studies have been undertaken to determine whether vinyl chlo-
ride may reasonably be expected to be present in water drawn from a system
containing poly(vinyl chloride) pipe. If no such commitment were made, or
adequate and appropriate studies were not undertaken, the regulation per-
mitting continued use of poly(vinyl chloride) water pipe could be revoked.
The major producers of dry blend resins for the pipe and conduit in-
dustry are B. F. Goodrich Chemical Company and Diamond Shamrock Corpora-
tion. These two companies supply about 30 to 40% of the total market. Pipe
and conduit producers, who formulate and blend their own resins, constitute
the majority of the remaining users of organotin heat stabilizers. These
producers, shown below, account for about 50 to 55% of the total market.
67
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Table 7. ESTIMATED CONSUMPTION OF OKGANOTIN COMPOUNDS
IN PIPE AND CONDUITS/
Total
PVC
(million Estimated quantity (million pounds
Total
1.96
3.92
3.66
4.41
4.28
4.75
4.55
6.95
7.87
7.77
_a/ Consumption figures calculated using percent tin stabilisation, aver-
age phr, and individual compound breakdown data supplied by pipe
producers and dry blend formulators.
b/ Source: 1965-1969 Modern Plastics. January issues; 1970-1974 Plastic
Pipe Institute data.
_c/ Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
_d/ Dibutyl tin-bis (laurylmercap tide).
_e/ Dimethyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
pounds X^'
65
125
140
186
238
387
541
877
1,148
1,066
Bu-IOMAS/
1.08
3.05
2.91
3.67
3.65
3.62
3.05
4.25
3.68
3.32
Bu-Uid7
0.88
0.87
0.75
0.74
0.63
0.70
0.53
0.56
0.55
0.64
Me-IOMAS7
'—
-
-
-
-
0.43
• 0.97
2.14
2.85
3.31
Mixed metals
_
-
.
-
-
-
- .
-
0.8
0.5
Table 8. PVC PIPE AND CONDUIT USE BY AREA
2
Quality of PVC (million pounds)
Type of pipe
Potable water
Pressure (nonpotable)
Drain-waste-vent (DWV)
Conduit
Sewer and drain
Other^
1971
280.1
93.4
44.9
103.8
-
18.6
1972£/
412.8
137.6
86.0
184.0
-
56.8
1973
465.6
155.2
101.4
331.3
-
94.8
1974
416.8
139.9
119.2
275.9
107.0
8.1
_a/ Data supplied by Plastic Pipe Institute.
b/ Includes sewer and drain In 1971 to 1973.
c/ Estimated from PPI data.
68
-------
Major Pipe and Conduit Producers
Carlon
Certain-Teed
Gifford-Hill
Johns-Manville
Precision Thermoplastics
Robintech
Geneva Pipe
Amoco Chemicals
The remaining 10 to 15% are comprised of numerous medium and small pro-
ducers and formulators.
Injection Molded PVC
Approximately 757, of all injection molding of poly(vinyl chloride)
is consumed in the production of pipe fittings. Within the area of pipe
fittings, the usage falls into two major categories: NSF approved fit-
tings for potable water pipe axd non-NSF approved for sewer, drains, vents,
conduit, etc. All potable water pipe is stabilized with organotin compounds
and, probably, 90% of all non-NSF pipe is presently stabilized with organo-
tin compounds to avoid the contamination and cross-staining that can occur
with lead stabilizers. This problem was discussed in the previous subsec-
tion on pipe and conduit.
The remaining 25% of all injection molded PVC is consumed for gen-
eral purpose uses, such as computer housing and parts, typewriter hous-
ings, television cabinets, telephone industry switch gears, and others.
Very little, if any, of the general purpose uses are stabilized by organo-
tins.
Table 9 lists the specific organotin compounds and the quantities
of each material consumed in injection molded PVC. The major producers
of dry blends or pellets for injection molding, as well as the manufac-
turers of injection molded products, who formulate their own PVC resins,
are as follows:
Compounding only; B. F. Goodrich
Diamond Shamrock
Compounders and producers; Certain-Teed
Robintech
Ethyl Corp.
Minor contributors: Hooker-Rueo
Goodyear Chemicals
Sloane
69
95% of the market
for injection mold-
ing resins
-------
Table 9. ESTIMATED CONSUMPTION OF OBGANOTIN COMPOUNDS IN
INJECTION MOLDING^/
Total PVC Estimated quantity (million pounds)
Year (million pounds)£/ Bu-IOMAS/Bu-LMS/Me-IOMA6/ Total
1965 13 0.20 0.03 - 0.23
1966 12 0.19 0.03 - 0.22
1967 25 0.37 ' 0.06 - 0.43
1968 34 0.47 0.08 - 0.55
1969 52 0.68 0.12 - 0.80
1970 68 0.88 0.16 0.06 1.10
1971 75 1.00 0.19 0.09 1.28
1972 86 1.12 0.22 0.13 1.47
1973 101 1.27 0.25 0.21 1.73
1974 90 1.10 0.20 0.24 1.54
_a/ Consumption figures calculated using percent tin stabilization,
average phr, and individual compound breakdown data supplied by
major formulators and producers.
_b/ Source: Modern Plastics, January issues; Plastic Pipe Institute
data.
cl Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
_d/ Dibutyltin-bis(laurylmercaptide).
_e/ Dimethyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
70
-------
Uniroyal was in the PVC injection molding business, however, they
have recently announced that they are withdrawing from the PVC market.
Consumption in Extruded Profiles
This area covers many consumer products but can be conveniently di-
vided into three areas: nonfoam profiles, foam profiles, and rigid sid-
ing. Foam profiles is a relatively new area but has been growing at a
rapid pace since about 1972.
Rigid siding; The primary organotin compound used in the extrusion
of rigid siding is the dibutyltin-S,S'-bis(isooctylmercaptoacetate), which
includes the high efficiency and the super tins. Methyltin compounds have
a volatility problem and, due to the large surface area of siding, show a
deterioration in impact strength and distortion point with time leading
to poor aging properties and maintenance problems. This volatility problem
has limited the usage of these materials in the siding area. Another fac-
tor is that approximately 75% of all rigid siding is produced with single
screw extruders so the advantage of methyltins over butyltins is diminished!
The specific organotin compounds and the estimated annual consumption of
each material is shown in Table 10.
The major compounders of PVC resin for rigid siding are B. F. Goodrich
and Diamond Shamrock, with Goodrich controlling about 90% of the market and
Diamond the remaining 10%. Certainteed, Bird and Son, and Mastic Corpora-
tion are the major extruders, who blend their own resins for captive use.
Nonfoam profiles; Nonfoam extruded profiles include consumer products
such as those exemplified below:
* Rain gutters, downspouts, etc.
* Vinyl trim for wall paneling
* Vinyl trim in mobile homes, prefab houses, etc.
* Window frames
* Folding door partitions in large office buildings
* Dance floors
As with rigid siding, the principal organotin compounds for heat stabil-
ity are the butyltin mercaptoacetates. The same volatility problem as with
siding, again limits somewhat the usage of the methyltin mercaptoacetates
in this field. Dibutyltin-bis(laurylmercaptide) is also used to a limited
71
-------
Table 10. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS
IN RIGID SIDING
Total PVC Estimated quantity (million Ib)
Year (million lb)b/ Bu-IOMAg/Bu-LMd/Me-IOMA§/Total
1965 6 0.16 0.01 - 0.17
1966 (12) 0.31 0.01 - 0.32
1967 20 0.44 0.01 - 0.45
1968 35 0,61 0.02 - 0.63
1969 50 0.62 0.02 - 0.64
1970 60 0.71 0.02 0.04 0.77
1971 59 0.63 0.02 0.06 0.71
1972 70 0.70 0.03 0.11 0.84
1973 86 0.81 0.03 0.19 1.03
1974 97 0.84 0.03 0.22 1.09
_a/ Consumption figures calculated using percent tin stabilization,
average per hour and individual compound breakdown data sup-
plied by major compounders and producers. Use of tin stabili-
zers in rigid siding has slowly decreased over the last 10
years.
b/ Source: Modern Plastics, January issues; 1966 data estimated
by MRI from data for other years.
£/ Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
d/ Dibutyltin-bis(laurylmercaptide).
_§/ Dimethyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
72
-------
extent in this area. Table 11 shows the specific organotin compounds and
the estimated yearly consumption of each material.
The major compounders of PVC resin and producers of extruded pro-
files are Ethyl Corporation, B. F. Goodrich, and Airco. Of these compa-
nies, the first two control over 80% of the market. Diamond Shamrock and
Goodyear Chemicals were in this market from 1965 to 1972.
Foam profiles; This is a relatively new field but it is growing
at a fairly rapid pace. The prime.advantage of the use of foamed poly
(vinyl chloride) versus the nonfearned is an approximate 38% savings in
resin consumption for foam PVC pipe and conduit, as well as improved
thermal insulation^' Other use areas encompass basically the same type
of products as described for nonfoam profiles (i.e., interior vinyl trim
for mobile homes, wall paneling, etc.).
Organotin stabilizers used in this area are basically the same as
those for nonfoam extruded profiles. The specific compounds and their
estimated annual consumption are shown in Table 11,
The major compounders of PVC resin and producers of extruded foam
profiles are B. F. Goodrich, Diamond Shamrock, and Goodyear.
Rigid PVC Food and Nonfood Bottles
The use of organotin stabilized poly (vinyl chloride) resin for use
in rigid blown bottles has been divided into food and nonfood sections
because distinctly different stabilizers are required for each area.
Nonfood PVC bottles: This area represents the larger of the two
areas of blown bottles. Among the consumer products which utilize vary-
ing degrees of organotin stabilized PVC resin are skin care products,
cosmetics, and toiletries such as: skin creams, lotions, and cleaners;
sun tan preparations; body powders; bath oil; makeup containers; medi-
cated creams and lotions; and baby products. Essentially all poly (vinyl
chloride) bottles are organotin stabilized; the only major exception is
Johnson products, for their baby oil, which uses a Ca-Zn heat stabilizer.
The organotin compounds which are being used as heat stabilizers for
nonfood PVC blown bottles and the estimated yearly consumption are listed
in Table 12. In addition to these compounds, dibutyltin 3-mercaptopropionate
was used in relatively small quantities from about 1965 to 1970. However,
this compound never achieved widespread usage in other areas, and thus, its
only application remained in PVC bottles. Even in this area, it never gained
any appreciable popularity, and at its peak (1967 to 1968), only approxi-
mately 40,000 Ib were used per year.
73
-------
Table 11. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS IN FOAM AND
NONFOAM RIGID PROFILES^'
Nonfoam profiles
Total PVC , Estimated quantity (million Ib)
Year (million lb)~
1965 23
1966 25
1967 27
1968 29
1969 41
1970 82
1971 110
1972 125
1973 128
1974 112
Foam profiles
1971 7 0.08 0.02 0.01 0.11
1972 51 0.55 0.14 0.08 0.77
1973 57 0.58 0.15 0.13 0.86
1974 48 0.46 0.13 0.13 0.72
Bu-IOMA^7
0.38
0.41
0.41
0.40
0.52
0.98
1.26
1.36
1.29
1.11
Bu-LM^7
0.09
0.10
0.10
0.10
0.13
0.25
0.33
0.35
0.36
0.30
Me-IOMA^
.
-
'
-
-
0.06
0.14
0.26
0.37
0.35
Total
0.47
0.51
0.51
0.50
0.65
1.29
1.73
1.97
2.02
1.76
&l Consumption figures calculated using percent tin stabilization,
average phr, and individual compound percentage data supplied
by compounders and producers.
b/ Source: Modern Plastics, January issues.
c./, _d/, _e/ See references in Table 10.
74
-------
Table 12. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS
IN NONFOOD BOTTLES^'
Total PVC
Estimated quantity (million Ib)
Year (million lb)b/
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
(6)
(11)
18
23
31.5
45
43
53
57
55
j/ See Reference &l
b/ Modern Packaging
Bu-IOMAS/ Me-IOMA^/ Bu-maleate esterS/
0.10
0.19
0.29
0.39
0.56
0.78
0.72
0.88
0.94
0.92
, Table 11.
Encyclopedia
-
-
-
-
0.04
0.09
0.10
0.11
0.12
and Planning
0.01
0.01
Oo02
0.05
0.06
0.06
0.04
0.05
0.06
0.05
Guide, December
TotaLf/
0.12
0.22
0.35
0.45
0.62
0.88
0.85
1.03
1.11
1.08
1974,-
Mr. R. Harting, Plastic Container Manufacturers Institute, New
Shrewsbury, New Jersey; data adjusted to reflect difference
between nonfood and food usage.
cl Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
d/ Dimethyltin-S,S'-bis(isooctylniercaptoacetate) and blends.
_e/ Dibutyltin isooctylmaleate ester.
_f/ Includes quantities of dibutyltin 8-mercaptopropionate.
75
-------
The two major compounders and producers of PVC blown bottles are
the Ethyl Corporation and Occidental Petroleum Corporation (Hooker-Ruco
Division). Minor contributors to this area are B. F. Goodrich Chemical
Company, Stauffer Chemical Company, and Pantasote.
PVC food bottles; This use area, as well as rigid and semirigid
PVC sheet and film, has been put under new restrictions as proposed by
the Food and Drug Administration (FDA).—' According to this proposed
regulation, rigid and semirigid PVC articles intended to contact food
will no longer be permitted. These uses would include bottles, boxes,
blister packs, and pipe (except for potable water). If this proposed
regulation becomes final, PVC could be used in rigid and semirigid ap-
plications only after approval of a food additive petition; in addi-
tion, data would be necessary to show that vinyl chloride monomer could
not be reasonably expected to become a cxmponent of food. The use of
organotin compounds in rigid and semirigid sheet and film will be dis-
cussed in the following subsection.
FDA approved di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate) and
di(n-octyl)tin maleate polymer are the only two compounds which have found
usage as heat stabilizers in PVC bottles intended to contact food. The use
of these two compounds was allowed in the FDA amendment to Part 121 of the
Food and Food Products Regulation issued January 20, 1968. This amendment
stated, in part, that for di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate),
it must have 15.1 to 16.4% by weight Sn and 8.1 to 8.9% by weight mercapto
sulfur. Among other preparative restrictions, it must be made from di(n-
octyl)tin dichloride having not less than 95% by weight di(n-octyl)tin
dichloride. Similar restrictions also apply to the preparation of di(jn-
octyl)tin maleate polymer. The estimated quantities of these two compounds
in PVC bottles intended to contact food are shown in Table 13. Cincinnati
Milacron Chemicals, Inc. has recently filed a petition with the Food and
Drug Administration proposing that the food additive regulations be amended
to provide for the safe use of dimethyltin/monomethyltin isooctylmercapto-
acetate as a stabilizer for use with PVC containers, bottles and rigid and
semirigid sheet and film (see next subsection), intended for contact with
dry food.— Industry sources indicate, however, that this petition probably
will not be granted.
The major compounders and producers of PVC bottles for food use are
basically the same as those stated above for nonfood use bottles.
76
-------
Table 13. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS
IN POOD USE BOTTLES^
Total PVC , Estimated quantity (million Ib)
Year (million
1968 2.0
1969 3.5
1970 5.0
1971 4.8
1972 9.3
1973 8.5
1974 4.8
Octvl-IOMA£/
0.02
0.04
0.06
0.07
0.16
0.15
0.09
Octvl maleatej/
0.003-/
0.004
0.010
0.012
0.027
0.027
0.016
Total
0.02
0.04
0.07
0.08
0.19
0.18
0.11
_a/ Consumption figures calculated using percent tin stabilization,
average phr, and individual compound percentage data supplied
by compounders and producers.
b/ Modern Packaging Encyclopedia and Planning Guide, December 1974;
Mr. R. Harting, Plastic Container Manufacturers Institute, New
Shrewsbury, New Jersey; data adjusted to reflect difference
between nonfood and food usage.
_c/ Di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate).
_d/ Di(n-octyl)tin maleate polymer,
_e/ Significant figures do not necessarily reflect accuracy but only
denote the small total quantities consumed.
77
-------
Extruded and Calendared Sheet and Film
This area can be divided into the semirigid and rigid packaging for
nonfood and food usage. Applications intended to contact food must, of
course, only use organotin stabilizers that have been FDA approved for
such usage.
Two main types of resins are used for these purposes: low molecu-
lar weight homopolymers of poly (vinyl chloride) and copolymers, which
can range from vinyl chloride-vinyl acetate to vinyl chloride-vinylidene
chloride systems. The latter are much more difficult to stabilize, par-
ticularly with respect to organotin compounds, as they may respond dif-
ferently than the homopolymers or the copolymers with vinyl acetate.
There are two main processes used for these materials: the sheet
die extruder and the calender. The die extruder type equipment is becom-
ing more predominant, especially with new equipment, as it is more eco-
nomical and produces sheeting at a lower cost.
Rigid and semirigid sheet and film for nonfood use; This area en-
compasses both packaging and nonpackaging applications. The butyltin iso-
octylmercaptoacetates are the preferred heat stabilizers for all facets
of sheet and film. Some problems arise due to the odor of the mercapto
compounds emitted during the processing of the sheet and film. The vol-
atility of the butyltin mercapto compounds is less than that of the
methyls so they are preferred. If the use of methyltin isooctylmercap-
toacetates is employed, very good ventilation is required.
. In nonpackaging applications of rigid sheet and film, considerable
quantities of clear rigid sheet are used for credit card stock. With
credit cards, a lead or Ba/Cd stabilized base sheet is produced, which
gives good printing capability, and an overlay of PVC copolymer is made
to improve the readability of the card. This copolymer overlay is sta-
bilized with organotin compounds. With the lead stabilized base stock
and organotin stabilized overlay, a problem of cross-staining can occur.
To prevent this discoloration, dibutyltin isooctylmaleate half ester is
used as the organotin stabilizer. It is rumored that M&T is now selling
a major credit card stock producer a special stabilizer for this use.
This stabilizer is reported to be dibutyltin 1/2 isooctylmaleate ester
and 1/2 isooctylmercaptoacetate plus other additives. A material of this
type would incorporate the better heat stability of the mercapto esters
and the reduced cross-staining properties of the maleate esters all in
one compound.
78
-------
Aside from credit card stock, other consumer products of rigid sheet
and film are household items (e.g., lamp shades, shower doors, room divid-
ers etc.), corrosion resistant tank liners, duct work, patio covers, rigid
roofing panels, wall coverings, industrial safety windows, blister packss
and others. The specific organotin compounds and the estimated quantities
of each consumed in rigid and semirigid sheet and film for nonfood usage
are given in Tables 14 and 15.
The major compounders and producers using organotin compounds as
heat stabilizers in rigid and semirigid sheet and film for nonfood uses
are: B. F. Goodrich, Tenneco, Union Carbide, General Tire and Rubber,
and American Hoechst. These companies are estimated to control 85 to 90%
of this particular market.
Rigid and semirigid sheet and film for food use; The proposed FDA
restriction on the use of PVC intended to contact food and the specifi-
cations for the di(n-octyl)tin compounds have been previously discussed.
In both rigid and semirigid sheet and film, the isooctylmercaptoacetate
is the preferred material for heat stabilization. Use of the isooctyl-
maleate ester is normally restricted to those applications where a lower
odor and better physical properties are required. In such applications,
the maleate ester is used in combination with the mercaptoester.
Typical uses of rigid and semirigid PVC for food usage are as film
wrapping (for meats, fruit, produce, etc.), vacuum packs, rigid trays
and produce pre-packs.
In the areas of rigid and semirigid sheet and film, one other or-
ganotin heat stabilizer has FDA approval for PVC intended to contact
food. This material is butylthiostannoic acid (BTSA). Its only utility,
thus far, is in sheet and film and is not used in PVC food bottles. BTSA,
and mixtures with butylstannoic acid, have been used since about 1962 in
Germany for PVC sheet and film in food packaging. Later research showed
that, when properly prepared, BTSA was superior to the mixture and the
butylstannoic acid was eliminated. A PVC film, called "Luvatherm," used
BTSA as the heat stabilizer. It found wide usage in Germany and was ex-
ported to the United States. In 1965, Hoechst, who originally produced
the film and BTSA, formed a joint operation with Stauffer Chemical to
produce the film in Wilmington, Delaware. Later, in 1970, Hoechst pur-
chased Stauffer"s interest and gained sole control over the production
of this film in the United States.
79
-------
Table 14. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS IN RIGID
SHEET AND FILM FOR NONFOOD USES*
a/
Nonpackaging applications
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Total PVC
(million
Estimated quantity (million Ib)
Bu-IOMAS7 Me-IOMA^/Bu^maleateS/ Total
37
38
41
40
50
55
55
(55)
(50)
(48)
0.08
0.08
0.09
0.09
0.15
0.16
0.14
0.13
0.13
0.12
0.01
0.01
0.02
0.01
0.01
0.03
0.03
0.03
0.03
0.05
0.05
0.07
0.07
0.06
0.06
0.11
0.11
0.12
0.12
0.20
0.22
0.22
0.22
0.20
0.19
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
6.8
9.3
11
17
34
45
50
55
50
50
Packaging applications
0.12
0.17
0.20
0.32
0.65
0.84 0.02
0.91 0.04
1.00 0.05
0.90 . 0.05
0.90 0.05
0.12
0.17
0.20
0.32
0.65
0.86
0.95
1.05
0.95
0.95
_a/ Consumption figures calculated using percent tin stabilization,
average phr, and individual compound percentage data supplied
by compounders and producers; the principal heat stabilizers
for nonpackaging applications are materials other than organo-
tin compounds.
b/ Source: Modern Plastics. January issues; Modern Packaging Ency-
clopedia, December 1974; data in ( ) estimated by MRI on figures
for past years and general market trends.
_c/ Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
_d/ Dimethyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
j/ Dibutyltin isooctylmaleate ester.
80
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Table 15. ESTIMATED ORGANOTIN CONSUMPTION IN SEMIRIGID SHEET AND
FILM FOR NONFOOD APPLICATIONS^'
Total PVC Estimated quantity (million Ib)
Year (million Ib)^ Bu-IOMA£/ Me-IOMAJ? Total
1965 (7.5) 0.15 - 0.15
1966 (8.5) 0.17 - 0.17
1967 (10) 0.20 - 0.20
1968 12 0.24 - 0.24
1969 15 0.30 - 0.30
1970 17 0.33 0.01 0.34
1971 20 0.38 0.02 0.40
1972 (24) 0.46 0.02 0048
1973 (27) 0.51 0.03 0.54
1974 (27) 0.51 0.03 0.54
j/ Consumption figures calculated using percent tin stabilization,
average phr, and individual compound percentage data supplied
by compounders and producers; the principal heat stabilizers
for nonpackaging applications are materials other than organo-
tin compounds.
_b/ Source: Modern Plastics, January issues; data in ( ) are extra-
polated for 1965 to 1967 from subsequent years; 1972 to 1974
data are estimates from PVC compounders for this area.
_c/ Dibutyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
d/ Dimethyltin-S,S'-bis(isooctylmercaptoacetate) and blends.
81
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"Luvatherm" or "Genotherm" film requires special calendering equip-
ment and special techniques as compared to film normally made in the U.S.
Its use in the U.S, is rather limited and confined only to the Hoechst
type film as they hold all patents on the products as well as a process
claim on the PVC film. The film is used primarily for packaging cold meat.
American Can Company is the largest consumer of this film.
As stated previously, Cincinnati Milacron has petitioned the FDA
for approval to use a dimethyl/monomethyltin isooctylmercaptoacetate
blend, probably in a 80:20 di- to mono ratio, as a heat stabilizer in
PVC containers for dry food. Such combinations have received prior ap-
proval in England, Germany, and other European countries.
Table 16 lists the estimated annual quantities of di(n-octyl)tin-
S,S'-bis(isooctylmercaptoacetate) and di(n-octyl)tin maleate polymer
used in rigid and semirigid PVC sheet and film intended to contact food*
The major compounders and producers of rigid and semirigid PVC
sheet and film for food and nonfood usage are B. F. Goodrich Chemical
Company, Tenneco Chemicals Company, Union Carbide Corporation, General
Tire and Rubber Company, and American Hoechst. These companies probably
control 85 to 90% of this particular market for organotin heat stabilizers.
CATALYSTS
The catalytic usage of organotiris is found mainly in the rigid poly-
urethane foam and in the room temperature vulcanization of silicon elasto-
mer industries. In both of these areas, the major organotin compound is
dibutyltin dilaurate. For the purposes of this study, stannous octoate
is not considered to be an organotin compound but rather a tin salt.
Argus Chemical Company has a dibutyltin X compound currently on the mar-
ket; X probably is the dodecanate. The synthetic dodecanoic acid is manu-
factured by Exxon. This material was introduced 2 to 3 years ago and is
estimated by sources in the area of catalysts to have captured about 30%
of the current market relative to dibutyltin dilaurate. Its primary ad-
vantage is at low temperature where it is a liquid as opposed to the di-
laurate, which tends to solidify. In past years, dibutytin dioctoate may
have been used in very small quantities as a catalyst.
Rigid Polyurethane Foam
There are two methods of producing rigid urethane foam: the one
shot method and the prepolymer technique^- In either method a syner-
gistic mixture of a tertiary amine and a tin catalyst is added to an
aromatic isocyanate, such as toluene diisocyanate (TDI), and a polyhy-
droxyl compound, i.e., containing more than two hydroxyl (OH) groups.
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Table 16. ESTIMATED CONSUMPTION OF OCTYLTINS AND BTSA IN RIGID AND
SEMIRIGID PVC SHEET AND FILM FOR FOOD US&S/
Total PVC , _ Estimated quantity (mill ion Ib)
Year (million lb>^ Octvl-IOMA2' Octvl-maleate~' BTSA Total
1968 17 0.14 0.01 0.2 0.35
1969 22 0.16 0.02 0.2 0.38
1970 28 0.26 0.03 0.1 0.39
1971 33.4 0.30 0.05 0.1 0.45
1972 39.2 0.40 0.05 0.1 0.55
1973 46 0.47 0.05 0.1 0.62
1974 27.2 0.28 0.05 0.1 0.43
j/ Consumption figures calculated using percent tin stabilization,
average phr, and individual compound percentage data supplied
by compounders and producers; differences in phr account for
the apparent discrepancy in consumption data for 1970 and 1974.
b/ Source: Modern Plastics, January issues, Modern Packaging Ency-
clopedia, December 1974; figures adjusted for food and nonfood
use through discu'ssion with a major resin compounder.
_c/ Di(n-octyl)tin-S,S'-bis(isooctylmercaptoacetate).
_d/ Di(n-octyl)tin maleate polymer.
83
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In rigid polyurethane the organotin compounds are primarily restricted
to the polyester type foams and the polyethers are based on stannous
octoate or stannous oleate type catalysts. Dibutyltin compounds oxidize
the polyethers, resulting in foam degradation.
One shot method; In this method, the liquid reactants are fed
from stock drums into a special injection machine via two synchronized
meter pumps under varying pressures, where the liquids are mixed and
dispensed through a nozzel.—' In one shot applications, the machine
can be adjusted to dispense a fixed amount of the reaction mixture,
which is then introduced into a mold or spraygun according to the par-
ticular end usage.— A dispensing machine typically provides for re-
cycling the ingredients to and from the chemical storage tanks, a
cleaning solvent-flush system of methylene chloride, and temperature
control.
For personnel in contact with the catalyst, the same precautions
should be observed as for the PVC resin compounding, i.e., eye goggles,
rubber gloves, overalls, and a dust mask.
Prepolymer method: This technique involves premixirig of the iso-
cyanate with some of the polyol to provide a formulation with the de-
sired foam action when the mixture is dispensed and catalyzed.-=2' This
method allows for the two-component packaging of a variety of formula-
tions. These two-component packaged urethane systems may range in quan-
tity from large tank cars to the more commonly used 55 gal. drums for
on-site dispensing by the user.
The major producers of rigid polyurethane foams and their total
isocyanate capacities are listed in Table 17. These companies combine
to supply over 50% of the total rigid polyurethane market; the remainder
is supplied by numerous small companies.
121
RTV Silicone Elastomers—
Two-pack products are supplied in separate containers, e.g., a
catalyst solution and the siloxane polymer, which is mixed with a fil-
ler to control the consistency of the uncured products. A suitable
cross linking agent is added to either the filled polydimethylsiloxane
or the catalyst. Premixing of the individual constituents and subse-
quent final mixing of reactants is done in a manner similar to that of
the prepolymer polyurethane foam method. In cases where large quantities
are involved, the catalyst is stored in bulk form where it is diluted
with silicone polymer and filtered to make addition easier and exact
quantities less critical.
84
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Table 17. MAJOR RIGID POLYURETHANE FOAM PRODUCERS^
Total isocyanate
capacity
Company Location (x Id6
Mobay Chemical Company Santa Anna, California 300
Polyurethane Division
Upjohn Company
CPR Division Fairbanks, Alaska \
Polymer Chemicals Torrance, California > 300
Division ;
BASF Wyandotte Corporation Wyandotte, Michigan 100
Industrial Chemicals
Group
Dow Chemical Company Ironton, Ohio 100
(1976)
_a/ Urethane Plastics and Products, 4_(10):3, October 1974.
b/ All isocyanate quantities are in 2,4-toluene diisocyanate (TDI),
except for Upjohn and 100 x 10^ Ib for Mobay which is methylene-
bis(4-phenyl isocyanate) (MDI).
85
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In the one-pack systems, the reactants are pumped through automatic
weighing devices to a blender. After mixing, the uncured product is dis-
pensed in cartridges, tubes, or other packages in a manner similar to the
one shot method for urethane foams. Many firms supply special dispensing
equipment that protects any of the remaining mixture from exposure to air.
The one-pack system may also be in the form of a dispersion in an organic
solvent, which will remain stable for a sufficient length of time for the
silicone mixture to be applied by spraying or painting.
The major manufacturers, their location and approximate shares of the
silicone elastomer market are shown in Table 18. Information relating to
the market shares was obtained from sources in the silicone production
facet of the industry.
Table 18. MAJOR SILICONE ELASTOMER PRODUCERS
Producer % of Market Location
Dow Corning Corporation ~- 45 Costa Mesa, California
(Silastic) Midland, Michigan
Trumball, Connecticut
General Electric Company ~ 40 Waterford, New York
Silicone Products Department
Stauffer Chemical Company ~ 10 Adrian, Michigan
SWS Silicones Division Matawan, New Jersey
Note: The remaining 5% of the market includes imports and minor contri-
butors, e.g., Union Carbide, Eagle Picher, etc.
Table 19 shows the estimated annual quantities of dibutyltin dilaurate
and dibutyltin X consumed as catalysts for rigid polyurethane foams and for
dibutyltin dilaurate as a catalyst for RTV silicone elastomers.
86
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Table 19. ESTIMATED CONSUMPTION OF ORGANOTIN COMPOUNDS
AS CATALYSTS*/
RTV silicons
Rigid polyurethane foam- elastomers^'
Year DBTDL^/DBTXg/ DBTDL Total
1965 0.01 - 0.003 0.01
1966 0.03 - 0.004 0.03
1967 0.06 - 0.003 0.06
1968 0.10 - 0.003 0.10
1969 0.20 - 0.005 0.21
1970 0.27 - 0.005 0.28
1971 0.35 - 0.007 0.36
1972 0.4 (0.1) 0.012 0.51
1973 0.5 (0.2) 0.017 0.72
1974 0.6 (0.3) 0.018 0.92
_a/ Quantities in million pounds.
b/ Polyurethane foam production data: Modern Plastics, January
issues; adjustments for spray and nonspray applications,
quantities organotin stabilized, and catalyst concentrations
were obtained from sources at M&T, Cook Paint and Varnish
Company and Mobay Chemical Company.
zl Significant figures are shown to denote the very low quantities,
not necessarily accuracy; silicone elastomer consumption data:
International Trade commission data; adjustments for one- and
two-pack systems and catalyst concentrations from General
Electric Company.
di Dibutyltin dilaurate.
el Dibutyltin X (X 3: dodecanate).
87
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BIOCIDAL APPLICATION
Organotin compounds used for biocidal applications are the trialkyl-
or triaryltin materials; no mono- or dialkyltin compounds are used at the
present time. Tricyclohexyltin hydroxide and triphenyltin hydroxide are
two of the major compounds with biocidal applications but fall outside
the scope of this study. The third major compound is bis(tributyltin)oxide,
commonly referred to as TBTO. Since 1970, tributyltin fluoride (TBTF) has
found some usage, particularly in antifouling paints, but all other tri-
alkyltin compounds, states as possessing biocidal applicationsri^' have
very highly specialized end uses and only minor quantities are consumed.
At the present time, the major use of TBTO is as the active ingredi-
ent in antifouling marine paints. The importance to the shipping industry
of the elimination of marine growth, such as barnacles, tubeworms, shells,
and algae, can be illustrated by the following example* A merchant ship,
immediately out of dry-dock will cruise in temperate waters at 20 knots.
After 6 months in these waters, a 40% increase in fuel consumption is re-
quired to maintain the 20-knot speed.-^ Several publications are avail-
able which present discussions of the use of organotin compounds, basi-
cally TBTO, in antifouling paints and the reader is referred to
these articles, and the references contained therein, in lieu of a de-
tailed discussion here. Although copper (I) oxide is still the major
compound used in this area, it does have a number of deficiencies r-i2
In addition to some aesthetic values, bis(tributyltin)oxide has a lower
leaching rate than copper compounds»i2' TBTO finds its greatest utility
in vinyl paint formulations. The material has little compatibility with
chlorinated rubber; therefore it is preferable to use a solid organotin
compound, such as TBTF, in chlorinated rubber paints. TBTO is also a
component of No-Foul , a proprietary B. F. Goodrich neoprene sheet,
which is applied to ship bottoms by use of an adhesive. At the present
time, the primary use of No-Foul is by the U.S. Navy but Goodrich an-
ticipates an advertising campaign to broaden its usage.
Two other current uses of TBTO which employ appreciable quantities
of this material are as a mildew preventative (mildewcide) and fungicide
in water or emulsion paints, particularly those based on vinyl acetate
and copolymers, and as an additive to cooling water in industrial plants.
The usage in the paint systems has been increasing during the past 2 to
3 years, whereas the use in industrial cooling water has remained rather
static.
88
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Other frequently cited biocidal applications include textile protec-
tion, wood preservation, bacterlcide in the paper mill industry, biocide
for plastics, molluscicide, and hospital disinfectant.-!.?' Relatively small
quantities of TBTO were used over the last 10 years for textile protection
and as a hospital disinfectant but these uses have declined very rapidly
and very small quantities, if any, are used at the present time. Organotin
compounds have never been used to any extent for wood preservation in the
U.S. although it is used in England and Europe. Very little, if any, orgavio-
tin compounds are consumed as biocides in plastics. In 1965 and 1966, ap-
proximately 400,000 Ib/year of TBTO were used in the paper mill industry
as a bactericide in the pulping operation. While TBTO was very effective
in this operation, it was found to be substantive on cellulose, which re-
moved the TBTO from the pulping operation, and hence, decreased its bac-
tericidal action. When no satisfactory solution could be found for this
problem, the use of TBTO decreased markedly in 1967 and has not been used
to any extent since that time.
The area of molluscicides is definitely an area of the future. At
the present time, there is no activity in this field on a commercial
scale but considerable research is being conducted. A widespread tropi-
cal disease, bilharzia, is caused by certain species of trematodes,
which are carried by freshwater snails. — It is currently estimated
that over 1 million people suffer from this disease, particularly in
underdeveloped tropical countries. TBTO has been found to be effective
in eradicating the snails but, to be effective, a continuous, low con-
centration (1 ppm) of TBTO must be introduced to the surface water. A
system has been developed, in which TBTO is incorporated into vulcan-
ized elastomer pellets. These pellets are spread over the surface of
the water and the TBTO diffuses slowly from the elastomer at a concen-
tration sufficient to kill the snails without harming fish or aquatic
Tributyltin fluoride was introduced in 1970 and is used only as
an ingredient in antifouling marine paints, Tributyltin chloride has
been tested as a rodent repellant for telephone wire cables and other
similar applications. M&T Chemicals tested this material for the U.S.
Army Signal Corp for use against termites, rats, and other rodents,
particularly in jungle warfare. It is not known if any commercial usage
is being made of this material at the present time.
M&T Chemicals is the sole U.S. producer of the trialkyltin com-
pounds used in biocidal applications; hence it is very difficult to
obtain information relative to the production quantities of these com-
pounds. According to the weekly import data published in the Chemical
Marketing Reporter, approximate imports of TBTO, TBTF, and tributyltin
chloride (TBTC1) are shown on the following page for 1972, 1973, and
1974.
89
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IMPOST DATA
Compound Origin Quantity (Ib)
TBTO Germany 82,756
TBTO Germany 9,834
TBTF Japan 4,940
TBTC1 Japan 2,900
1972 TBTO Japan 56,358
TBTF Japan 9,140
TBTC1 Japan 2,320
Domestic production of TBTO is estimated by sources closely associated
with the biocidal area to have been 500,000 Ib in 1965 and 1966. Becauae
of decreased usage in the paper mill industry, quantities in 1967 fell
to about 100,000 Ib. Since that time, the domestic production has slowly
risen to a value of about 500,000 Ib in 1974*^2' Other sources, who wish
to remain anonymous, very familiar with TBTO production and consumption
indicate that the total in 1974 may be approximately twice that stated
by M&T.
Tributyltin fluoride (TBTF) and bis(tributyltin)oxide (TBTO) have
been granted full registration by the Environmental Protection Agency
and any company selling either material or an antifouling paint contain-
ing these materials must have label directions for their safe usage, pro-
cedures in case of accident, and disposal of the empty containerr=-2' In
a manufacturing facility, regardless of the end product, the use of eye
goggles, rubber gloves, and longsleeved overalls should be employed. For
operations involving large quantities of these materials, a dust mask or
air hood should also be worn.—'
In spray painting objects with antifouling coatings, containing
either TBTO or TBTF, airless spray equipment is recommended to minimize
overspray. Personnel involved in the spraying should be adequately cov-
ered (stated above) to preclude eye and skin contact, as well as inhala-
tion of the spray mist. A full-face, air-supplied respirator is recom-
mended. Other personnel within a 25-ft radius or 100-ft downwind from
the object being coated should also be protected against eye or skin
contact and inhalation.JJJ'
90
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For 1972, an approximate percentage breakdown of TBTO by use area
would be: 40% marine antifoulantsj 25% paint additive; 25% industrial
cooling water, and 10% miscellaneous uses. The last 2 years have 3een
an increase in the domestic consumption of compounds with biocidal
applications.
The major formulators of antifouling coatings and paints, contain-
ing TBTO or TBTF, are given below:
* International Paint Company, Inc.
New York, New York
* Celanese Coatings and Speciality Chemicals Company
Devoe Paint Division
Louisville, Kentucky
* Mobil Chemical Company
Mobil Chemical Coatings Division
New York, New York
* Carboline Company
Admiral Paint Company, Inc., subsidiary
Lake Charles, Louisiana
* Exxon Oil Company
Houston, Texas
* B. F. Goodrich Chemical Company
Akron, Ohio
Manufacturers of No-Foul®
Other minor formulators of TBTO and TBTF antifouling coatings and paints
are Parboil Company, Division of Beatrice Foods Company, Baltimore,
Maryland; Henkel, Inc., Teaneck, New Jersey; Baltimore Paint and Chemical
Corporation, subsidiary of Elt, Inc., Baltimore, Maryland; and Standard
Paint and Varnish Company, subsidiary of Ogden Corporation, Harvey,
Louisiana.
Commercial production of tributyltin fluoride began in 1970 and by
1974 had reached a value of approximately 120,000 Ib/yearjs2' To our
knowledge, tributyltin chloride is produced only in very small quantities.
91
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MISCELLANEOUS SPECIALIZED USES
In this subsection, use areas will be discussed which consume rela-
tively small quantities of organotin compounds or which encompass the use
of a single compound. Such areas are anthelmintics, fiber stabilization,
and exportation*
Anthelmintic and Toxcidiostat
Dibutyltin dilaurate is used as an anthelmintic and growth stimulant
for poultry and as a toxcidiostat for young turkeys. The largest, and per-
haps sole, consumer in the U.S. is Salsbury Laboratories in Charles City,
Iowa. According to Salsbury,— the poultry anthelmintic, "Wormal," is
produced in granular and tablet form and is the only tapeworm application
approved by the FDA. Two forms of the toxcidiostat for turkeys is produced:
"Tinostat" and "Polystat." Of these three formulations, the poultry anthel-
mintic and two toxcidiostats, about 15% of the total annual production is
exported, primarily to Canada, and the remainder used in the U.S. Consump-
tion of dibutyltin dilaurate in these areas ranged from 75 tons (0.15 x 10
Ib) in 1965 to 120 tons (0.24 x 106 Ib) in 1974. During the intervening
years, the annual consumption was basically linear with time.
Fiber Stabilization
Within the past 10 years, quantities of dibutyltin oxide and a spec-
ialized dibutyltin maleate ester have been used for the stabilization of
certain types of acrylic fibers, especially those where vinyl chloride
was used with the acrylic to enhance the fire resistancy of the finished
fiber. Dibutyltin oxide was the preferred compound, as it was the least
extractable material during the spinning process, and thus the most ef-
ficient compound.
The major users of these compounds for fiber stabilization are Mon-
santo and Eastman Kodak, each using approximately equal amounts. In 1970,
a total of about 800,000 Ib of these two materials were used.
Exportation
During the past 10 years, exportation quantities have remained in
the range of 4 to 5% of the total annual U.S. production of the materials
under study. Exportation has been only in, the form of ,the end products,
i.e., no intermediates such as the tetraalkyltins, alkyltin oxides (ex-
cept TBTO), etc. Countries to which exportation occurs include Taiwan,
Singapore, and South American countries. The exportation figures stated
92
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above, which are estimates by the U.S. manufacturers of organotin com-
pounds, do not include any intracompany transfers of materials. Since
the three major companies have subsidiaries in foreign countries, con-
siderable transfer of material occurs but the quantities of such ma-
terial would be extremely difficult to ascertain.
93
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REFERENCES TO SECTION VII
1. Stimpfl, R. J., "Popular Plastics," p. 33, May 1973.
2. Sawyer, A. K., Ed., Organotin Compounds. 3rd Ed., Marcel Dekker, Inc.,
New York, p. 936 (1971) (and references cited therein).
3. Modern Plastics Encyclopedia. McGraw-Hill, Inc., New York, p. 896
(1968).
4. Modem Plastics. McGraw-Hill, Inc., New York, September 1966.
5. MRI estimate based on data published in Modern Plastics, and contacts
with industrial users of PVC resin, September 1975.
6. Estimates from Johnson Plastics Machinery, a large manufacturer of
extrusion equipment.
7. Modern Plastics, McGraw-Hill, Inc., New York, p. 42, February 1975.
8. "Vinyl Chloride Polymers in Contact with Food," FR Doc. 75-23241,
Federal Register. Vol. 40, September 3, 1975.
9. FR Doc. 75-15521, Federal Register, Vol. 40, June 16, 1975.
10. Tin and Its Uses. Vol. 90, No. 7 (1971).
11. Modern Plastics Encyclopedia. McGraw-Hill, Inc., New York, pp. 136-
137 (1975).
12. Tin and Its Uses. Vol. 89, No. 5 (1971).
13. Poller, R. C., Chemistry of Organotin Compounds, Academic Press, New
York, p. 274 (1970) (and references cited therein).
14. Vizgirda, R. J., Paint and Varnish Production, December 1972.
15. Sheldon, A. W., J. Paint Tech.. 47_(54) (1975).
16. Engelhart, J» E., and A. W. Sheldon, 15th Annual Marine Coatings
Conference, Point Clear, Alabama^ February 1975.
17. Beiter, C» B., et al., Symposium on Marine and Fresh Water Pesticides,
American Chemical Society Meeting, Atlantic City, New Jersey, August
1974.
94
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18. Bufkin, B. G., R. D. Bounds, and S. F. Thames, Paint and Varnish Pro-
duction, p. 25, February 1974.
19. Bokranz, A., and H» Plum, Fortschritte der Chem. Forschung, 16:366
(1971).
20. Personal written communication from Mr. A. A. Keller, M&T Chemicals.
21. Personal communication with Mr. Anderson, Salsbury Laboratories,
Charles City, Iowa.
95
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SECTION VIII
FUTURE PRODUCTION AND UTILIZATION
This is an extremely difficult area to assess at the present time
as its future is, quite obviously, directly related to the future of
poly(vinyl chloride). The complicating factors are the restrictions on
vinyl chloride monomer and the resultant effect on PVC production, the
recent FDA proposal to restrict the use of PVC in food packaging and
possibly in potable water pipe, and the general economic conditions
prevailing at the present time. The economic recession has led to a
severe decrease in the construction industry, which consumes large
quantities of PVC pipe, conduit, fittings, etc. These areas, in turn,
are the largest consumers of alkyltin heat stabilizers. Future con-
sumption of heat stabilizers will be directly related to the recovery
of economic conditions, in particular the construction industry.
Prior to the recession, it can be stated that the consumption of
alkyltin heat stabilizers increased from 8.3 million pounds in 1969 to
17.0 million pounds in 1973. During this same time period, the produc-
tion of poly(vinyl chloride) increased from 238 to 1,148 million pounds,
However, with the advent of new higher efficiency materials and the in-
creased usage of twin screw extruders, the actual quantity of alkyltin
heat stabilizer per pound of rigid PVC has decreased. Twin screw ex-
truders presently account for approximately 75% of all extruders. Since
these machines are not presently applicable to all extrusion processes,
the growth of the twin screw extruder may have reached a plateau. Fur-
ther developments to decrease the quantity of alkyltin heat stabilizer
used per pound of poly(vinyl chloride) will probably occur in new, more
efficient heat stabilizers rather than in new equipment.
Further consumption of alkyltin compounds as urethane and silicone
catalysts will probably continue to progress at the same, rather slow,
rate it exhibited during the past 10 years. Newer, more suitable alkyi-
tin compounds will probably be developed but no real increase in mar-
ket share is foreseen.
96
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Biodical applications, in particular antifouling paints, is a rather
difficult area to assess because production of these compounds has been
thus far entirely the domain of M&T Chemicals. This area will be treated
in more detail later in this section.
HEAT STABILIZERS
A recent forecast of poly(vinyl chloride) end use markets in 1978
and 1980 predicted that the total consumption of PVC would be 6,330 mil-
lion pounds in 1978 and 6,820 million pounds in 1980.— Linear extrapola-
tion of these values shows a potential consumption of 7,800 million pounds
by 1984.
The consumption of poly(vinyl chloride) in rigid pipe and conduit,
as well as the total consumption of alkyltin compounds as heat stabili-
zers, are shown in Figure 2 for the years 1965 to 1974. The similarity
in the shapes of the two curves is striking but not entirely unexpected,
since rigid pipe and conduit has consistently been a major area for the
consumption of alkyltin heat stabilizers. Since 1972, this use area has
consumed approximately 38% of the annual production of alkyltin heat
stabilizers. A recent article on pipe and conduit projected the consump-
tion of PVC in pipe and conduit in 1975 and 1980 to be 1,349 million
pounds and 2,108 million pounds, respectively.—' This estimate, however,
was based on a 1974 consumption of 1,221 million pounds. Data from the
Plastic Pipe Institute state that the 1974 consumption of PVC in pipe
and conduit was 1,066 million pounds; Adjusting the Modern Plastics
projected figures to a 1974 base value of 1,066 million pounds yields
a 1975 figure of 1,178 million pounds and a 1980 value of 1,840 million
pounds. Extrapolation of these values, as shown in Figure 2, projects a
consumption of 2,360 million pounds of PVC in pipe and conduit in 1984.
As a check on the extrapolated 1984 quantities for total PVC con-
sumption and the value for PVC in pipe and conduit, the ratios of the
two quantities were calculated for the period 1965 to 1974. Using the
1980 ratio from the two cited projections and extrapolation shows that
in 1984, 30.5% of the total PVC consumption will be in pipe and conduit.
The extrapolated 1984 figure for total PVC consumption was 7,800 million
pounds; 30*5% of this value is 2,379 million pounds, which is in good
agreement with the 1984 value of 2,360 million pounds from the adjusted
Modern Plastics data.
97
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2400r
Consumption of PVC in
Rigid Pipe and Conduit
^ 18
|
I
§ U
| 10
a
j
•D
£
Estimated Consumption of
Alkyltin Heat Stabilizers
1965 1967 1969 1971 1973 1975 1977 1979 1981
1983
Figure 2. Consumption of PVC in Rigid Pipe and Conduit and Estimated
Consumption of Alkyltin Compounds as Heat Stabilizers.
98
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During the past 3 years, the percentage of total consumption of
alkyltin heat stabilizers in rigid pipe and conduit has remained rela-
tively constant in the range of 45 to 48%. Using an average concentra-
tion of approximately 0.6 phr and the estimated 2,360 to 2,379 million
pounds of PVC resin in pipe and conduit in 1984, a consumption of 14.2
to 14.3 million pounds of alkyltin heat stabilizers in pipe and conduit
is calculated. Since 1965, the area of pipe and conduit has accounted
for at least 40% of the total annual consumption of alkyltin heat sta-
bilizers. If this 40% figure can be assumed for 1984, a total annual
consumption of about 36 million pounds is projected.
A more simplified approach would be to take the ratio of the 1974
PVC resin consumption in pipe and conduit to the projected 1984 value
and multiply this figure times the total 1974 consumption of alkyltin
compounds as heat stabilizers. This procedure leads to a value of ap-
proximately 36.0 million pounds in 1984.
These rather elementary calculations show that, based on a 1974
consumption of 16.2 million pounds, the total quantity of alkyltin com-
pounds consumed as heat stabilizers in 1984 would be in the range of
approximately 36 million pounds. More realistically, perhaps a range
of 35 to 45 million pounds in 1984 should be projected in view of the
simplicity of the calculations. As stated earlier in this section, any
projections of consumption in the area of heat stabilizers 10 years in
advance should be viewed as rather tenuous estimates due to the uncer-
tainties in the future of poly(vinyl chloride).
With respect to specific alkyltin compounds, the situation is
probably even more uncertain than the projections for total heat sta-
bilizers. Based on past performance, the two major materials will
probably continue to be the methyl and butyltin isooctylmercaptoace-
tates and their blends.
The nonsulfur alkyltin compounds, exemplified by the dibutyltin
octylmaleate, have played a relatively minor role as heat stabilizers
and probably will continue this role. In 1974 approximately 100,000 Ib
of the octylmaleate were consumed as heat stabilizers. This quantity
may double to about 200,000 by 1984, but not significant break through
in the use of these compounds is envisioned to increase their share of
the market.
Dibutyltin-bis(laurylmercaptide) is used in pipe and conduit, in-
jection molding, rigid siding, and other extruded profiles. It would
not be considered the major heat stabilizer in any of these use areas;
its major utility lies in its good lubricating properties rather than
99
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its heat stabilization properties. During the past 10 years, the con-
sumption of the laurylmercaptide has ranged from about 1 to 1.5 million
pounds per year. The production of this compound in 1984 will be very
dependent upon the production of rigid pipe and conduit and pipe fit-
tings. If current projections are correct, pipe and conduit and pipe
fittings will increase by slightly over 100% by 1984. Based on these
figures, the production of dibutyltin-bis(laurylmercaptide) should be
in the range of 2.5 to 3.0 million pounds in 1984.
Currently the sole use of the two octyltin compounds are in PVC
intended to contact food. In view of the recent FDA proposed restric-
tions, it would be extremely difficult to predict any future consump-
tion figures for these materials. It is known that the octyl compounds
are virtually nontoxic (11)50 > 1,000) and have low odor levels during
processing. From sources closely associated with the manufacturing seg-
ment of the organotin industry, it has been learned that not everyone
is thoroughly convinced of the nontoxicity of the methyl and butyltin
isooctylmercaptoacetates. It is also a fact that odor production can
be a problem during processing with both the methyl and butyl compounds,
particularly the methyl compounds. It may be that a future use of the
octyl compounds might be in conjunction with the methyl or butyl com-
pounds to reduce possible toxicity and odor production.
During the past 2 years, the methyl and butyltin isooctylmercapto-
acetates (plus blends) have accounted for over 80% of the total consump-
tion of alkyltin heat stabilizers. There is no reason to believe that
this percentage will decrease during the next 10 years barring the in-
troduction of a new compound or compounds that could capture an appre-
ciable share of the market. Assuming that this 804% value holds true,
then by 1984 the combined production of these two systems could be 32
to 36 million pounds. The consumption of the methyltin systems has been
growing rapidly, particularly in pipe and conduit, and in 1974 an esti-
mated 4.5 million pounds were used as compared to about 9.3 million
pounds for the butyltin systems. The present gap between the two sys-
tems could continue to narrow but this is difficult to predict since
the two systems compete directly in almost all use areas. If an esti-
mate is necessary, perhaps a 60 to 40% division between the butyltins
and methyltins might occur but this is a very tenuous estimate.
CATALYSTS
This area should not experience any unexpected increases in usage
during the next 10 years. It has been an area of steady but low consump-
tion during the past 10 years, particularly with respect to silicone
elastomers.
100
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In 1974, only approximately 20,000 Ib of alkyltin compounds, in
particular dibutyltin dilaurate, were used as a catalyst for silicone
elastomers. During the next 10 years, no appreciable increased share
of the market is envisioned and the consumption should parallel the
production of silicone elastomers. By 1984, the use of dibutyltin di^
laurate may double to a value of approximately 40,000 Ib. In the over-
all scope of the consumption of alkyltin compounds, this is very minor.
Consumption of dibutyltin dilaurate as a catalyst in polyurethane
foams has been increasing by an estimated 200,000 Ib/year during the
past 3 years. Usage in this area is restricted to the polyester type
foams so that the consumption is somewhat restricted. The urethane foam
use area covers a very broad range of end products, but the primary area
for alkyltin-catalyzed foams is in the construction area. Thus future
consumption will be dictated to some extent by the overall economic re-
covery and the construction industry in particular.
Another possible factor which may play an important role in the
future of urethane foams, and hence in the future of dibutyltin di-
laurate, is the current controversy concerning the use of chlorofluoro-
carbons or "Freons®." The materials are used as blowing agents in many
urethane foams. Should the future use of the chlorofluorocarbons be
limited or restricted, this could have a detrimental effect on the en-
tire urethane foam industry and consequently produce a decrease in cat-
alyst consumption. At the present time, the outcome of the chlorofluoro-
carbon controversy is unclear so that the ramifications of its effect on
the urethane foam industry are uncertain.
Considering the possible influences on the consumption of alkyl-
tin compounds in urethane foam, it is very difficult to predict the
possible consumption in 1984. From past consumption data, a figure of
2 to 2.5 million pounds in 1984 might be anticipated depending upon
the future economic factors and the influence of the outcome of the
chlorofluorocarbon controversy.
BIOCIDAL APPLICATIONS
This area should experience a fairly rapid relative growth rate
during the next 10 years. The three primary areas of application are
in antifouling paints and coatings, mildew preventative in water and
emulsion paints, and as an additive to industrial cooling water.
101
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Use of TBTO as an industrial cooling water additive will possibly
show the lowest increase in consumption of any of the three areas. In
1972, an estimated 60,000 to 70,000 Ib of TBTO were used in this area.
By 1984, the consumption may be approximately 150,000 to 175,000 Ib/
year. This is a relatively minor area with limited prospects for en-
larging its share of the market so its growth should progress at a
rather slow, steady pace.
Consumption of TBTO in antifouling paints and coatings has been
the largest use area in biocidal applications during the past 6 to 7
years. Its growth during that period has been at a rather steady pace
as the promotion of organotin compounds in this area has been in prog-
ress for the last 10 years. M&T Chemicals estimates that the consump-
tion of TBTO and TBTF in antifouling saints and coatings will grow 100%
by 1980 and by another 100% by 1985«^7 If an estimated 200,000 to 250,000
Ib of TBTO and 120,000 Ib of TBTF were consumed in 1974, then by 1984 it
is estimated that approximately 900,000 Ib of TBTO and 475,000 Ib of TBTF
could be consumed in the production of antifouling paints and coatings.
Future incorporation of organotin compounds for antifouling applications
will probably be in the form of organotin polymeric coatings. This area
is currently receiving considerable research attention, particularly by
the U.S. Navy.
The area which has probably shown the greatest relative growth
within the past 2 to 3 years is the use of TBTO as an additive to paints.
Two problems, which exist in water and emulsion paints, are the bacter-
ial growth during the shelf life of the paint leading to in-can spoilage
before the paint is used and the growth of mold or mildew on paint films
exposed to hot, moist climatic conditions. The anticipated growth rate
of TBTO in this area should at least parallel that of the consumption
in antifouling paints during the next 10 years. For an estimated con-
sumption of approximately 120,000 Ib in 1974, a projected annual con-
sumption in 1984 may be expected to be in the range of 450,000 to
500,000 Ib.
On the basis of the above discussion, a projected annual consumption
of TBTO for biocidal applications in 1984 would be in the range of 1.5 to
1.9 million pounds and approximately 500,000 Ib for tributyltin fluoride.
102
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REFERENCES FOR SECTION VIII
1. Rubber World, p. 38, January 1975.
2. Modern Plastics, p. 42, February 1975.
3. Personal written communication from Mr. A. A. Keller, M8tT Chemicals.
103
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SECTION IX
MATERIAL BALANCE AND ENERGY CONSUMPTION
This section briefly discusses the total quantities of raw mate-
rials and energy required, as well as the quantities of waste material
produced, for the manufacture of those alkyltin compounds for which
production quantities were published or estimated by MRI. A reaction
schematic for the various steps in the preparation of the alkyltin com-
pounds in shown in Figure 3. The total production of all alkyltin com-
pounds in this report was approximately 113 million pounds for the time
period 1965 to 1974. Production quantities of each compound on a yearly
basis was given previously in Table 1. In terms of total quantity the
major compounds produced during the 10-year span were the butyltin iso-
octylmercaptoacetates and their blends, which accounted for approximately
63.5% of the production of all alkyltin compounds.
RAW MATERIALS
The calculated total quantity of each of the raw materials con-
sumed in the manufacture of these alkyltin compounds is shown in Table
20 for each of the years of production from 1965 to 1974. It should be
noted that some alkyltin compounds are produced from imported inter-
mediates. These intermediates result in a reduction in the quantity
of alkyl chloride, magnesium, and stannic chloride consumed as raw ma-
terials.
Since the butyltin isooctylmercaptoacetates accounted for well
over half of all of the alkyltin compounds produced during the period
1965 to 1974, it is no surprise that the three raw materials consumed
is the largest quantity, both on an annual basis and total for the 10-
year period, are ji-butyl chloride, stannic chloride, and isooctylmer-
captoacetic acid. Except with the use,of imported ,dialkyltin oxide in-
termediates, stannic chloride is consumed at one stage or another in
all production processes of alkyltin compounds.
104
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C4H9CI + SnCI4 +Mg
SnCI4
C4H9SnCI3
IOMA
IOMA
(C4H9}2 SnCI2
NaOH
—»• (C4H9)3SnCI
NaF
NH3
NH4CI
(IOMA)3 + HCI
Butyltin Isooctylmercaptoocetates + Mixed Metals
NH3
(C4Ho)2Sn[s(CH2)nCH3]2
CH3(CH2),0C02H
H2O
H2O
C4H304R
(C4H9)2Sn(C4H204R)2
NaOH
(C4H9)3SnF + jNoCl]
NaCI
CH3CI
+ Sn
(CH3)2SnCI2
lsnCI4
CH3SnCI3
IOMA
CH3Sn(IOMA)3
NH4CI
Methyltin Isooctylmercaptoacetates + Mixed Metals
NH3
{ NH4CI
C8H17CI + SnCI4 + Mg ». (C8H17)4Sn
SnCI>
(C8H17)2SnCI2
NaOH
MgCI2
(C8H17)2SnO + | NoCl
IOMA
NOTE: | Denotes Waste Products
*• (C8H17)2Sn(IOMA)2 + | H2O
C4H404
H,O
Figure 3. Reaction Schematic for the Preparation of Alky 1 tin Compounds.
-------
Table 20. CONSUMPTION OF RAW MATERIALS, 1965 to 1974 (in million pounds)
Year Sn
1965
1966
1967
1968
1969
1970 0.111
1971 0.223
1972 0.461
1973 0.668
1974 0.735
Total 2.198
SnCl4
1.719
2.582
2.310
2.872
3.272
3.929
4.005
5.097
5.232
.4*7.98
35.816
MS
0.333
0.466
0.379
0.468
0.535
0.636
0.647
0.803
0.824
0.762
5.853
NaF NaOH CH^l C^H^Cl CgH17Cl
0.
0.
0.
0.
0.
0.001 0.
0.004 0.
0.006 0.
0.010 0.
070
070
018
041
054
072
082
105
108
0.016 0.105
0.037 . 0.
725
1.
1.
1.
1.
1.
0.095 2.
0.189 2.
0.392 2.
0.568 2.
0.626 2t
1.870 21.
269
775
443
737 0.068
981 0.088
331 0.142
355 0.165
896 0. 247
999 0.213
810 0. 143
596 1.066
Laurie Maleic
acid acid
0.191
6.191
0.222
0.254 0.005
0.318 0.008
0.381 0.013
0.445" 0.015
0.445 0.020
0.572 0.020
0.635 0.018
3.654 0.099
Alkylmaleic Lauryl /
acid raercaptide IOM*2
0.143
0.143
0.315
0.342
0.375
0.392
0.412
0.173
0.146
0.139
2.580
0.637
0.637
0.573
0.573
0.573
0.701
0.701
0.828
0.828
0.828
6.879
1.600
3.199
3.408
4.399
5.047
6.486
6.982
9.840
10.735
10.317
62.013
Total
5.962
9.063
8.668
10.759
12.251
15.290
16.225
21.313
22.923
21.932
144. 386
_§/ IOMA = Isooctylmercaptoacetic acid.
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ENERGY CONSUMPTION .
The calculated total energy consumed, as gas, steam and electricity,
in the production of alkyltin compounds on an annual basis for the years
1965 to 1974 is given below in Table 21.
Table 21. ENERGY CONSUMPTION
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
Gas
(x 106 ft3)
1.912
3.062
2.969
3.718
4.217
5.103
5.212
6.746
6.917
6.262
Electricity
(x 106 kw-hr)
Total 46.118
6.018
Steam
(x 106 Ib)
11.781
18.681
18.237
22.866
25.964
30.794
30.927
38.715
38.722
34.375
271.062
Energy consumption by type for the individual alkyltin compounds can
be found in Section V in the discussion of the respective compound.
WASTE MATERIAL PRODUCED
The major waste materials or by-products from the production pro-
cess are shown on the following page (Table 22) in million pounds on
an annual basis and for the 10-year period.
107
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Table 22. WASTE MATERIAL PRODUCTION
Year MgCl2 HCl NaCl H20 Total
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1.305
1.825
1.484
1.832
2.097
2.493
2.534
3.145
3.229
2.987
0.396
0.676
0.701
0.860
0.970
1.233
1.315
1.819
1.969
1.919
0.102
0.102
0.027
0.060
0.078
0.107
0.126
0.161
0.172
0.176
0.030
0.030
0.027
0.039
0.048
0.059
0.067
0.068
0.075
0.070
1.833
2.633
2.239
2.791
3.193
3.892
4.042
5.193
5.445
5.152
Total 22.931 11.858 1.111 0.513 36.413
All of these waste materials are water-borne effluents which are
discharged in municipal sewer systems. If the manufacturer produces
the end product from the alkyl chloride starting material, these waste
materials will generally undergo treatment in an aerated lagoon prior
to discharge. However, if the manufacturer purchases the dialkyltin
dichloride or oxide intermediate to produce the final product, the
waste materials are generally discharged into the sewer system with-
out treatment. One exception is Argus Chemical Company who discharge
all of their aqueous waste material in a deep-well at the Taft,
Louisiana, production facility. Aqueous effluents at their Brooklyn,
New York, facility, however, are discharged in the sewer system.
Magnesium chloride, produced during the initial Grignard reac-
tion, constitutes the largest single waste material. It is removed
from the reaction mixture during the acidic wash of the tetraalkyl-
tin product. On the basis of reaction stoichiometry, approximately
1.1 Ib of magnesium chloride waste are produced per pound of tetra-
alkyltin. In Section X, the alkylaluminum process for preparing tetra-
alkyltin compounds is described. By this method, approximately 0.74
Ib of NaAlCl/ waste would be produced per pound of product or a net
reduction in waste load of 0.36 Ib/lb of product. The quantities of
all other waste material would remain the same.
108
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The hydrogen chloride produced during the reaction of the mercapto-
acids with the alkyltin chlorides is neutralized either with ammonia,
during the reaction process, or with sodium hydroxide to form the cor-
responding saline solution. Regardless of the type of neutralization,
the final salt solution is discharged either to a deep-well or the sewer
system. If ammonia is used, the neutralization would result in about 17.4
million pounds of ammonium chloride; for sodium hydroxide neutralization,
the result would be about 19 million pounds of sodium chloride. Since
both methods are used, the true quantity is somewhere between the figures
of 17.4 and 19 million pounds.
In addition to the major waste effluents, relatively small quanti-
ties of solid waste products are produced. In the preparation of tetra-
octyltin, aluminum chloride is used as a catalyst. Following the Grignard
reaction and subsequent acidic wash, the white viscous material is removed
from the reaction vessel. M&T Chemicals disposes of this material in a
landfill. .Argus Chemical did not specifically state their method of dis-
posal but it is likely disposed in their deepwell. The total quantity
of this material is thought to be quite small. If a concentration of 1%
based on octyl chloride, which is about normal for catalytic quantities,
is assumed and the total quantity of octyl chloride consumed from 1968
to 1974 is 1.066 million pounds, the total quantity of aluminum oxide
trihydrate waste produced during this time period would be approximately
6,230 Ib, or an average of 890 Ib/year.
Stannic chloride is added during the production process at two
points: (a) the initial preparation of the tetraalkyltin and (b) the
comproportionation of the tetraalkyltin to the alkyltin chlorides. The
major source of unreacted stannic chloride would be during the first
step since the stoichiometry of the comproportionation reaction must
be closely controlled to insure the proper mixture of final products.
During the acidic wash of the tetraalkyltins, unreacted stannic chlo-
ride is removed in the washwater and during subsequent waste treatment
converted to the hydrated oxide. The oxide is collected, stored, and
sent to a smelter by M&T Chemicals. Cardinal Chemical Company, the
other major producer by the Grignard method, did not respond to the
inquiries concerning their waste treatment. It is assumed that Cardinal
discharges this material along with the other waste materials. The ac-
tual quantities of unreacted stannic chloride discharged as waste ma-
terial is unknown but assumed to be very small. This assumption is
based on the fact that stannic chloride is, by far, the most expensive
starting material and precautions would be taken to prevent its exces-
sive usage..
109
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A phosphonium catalyst is used in the "direct synthesis" of methyl-
tin chlorides by both Cincinnati Milacron and Argus. Both of these com-
panies periodically clean the spent catalyst from the reactors and have
it removed by a contract hauler* Again, the exact quantities are unknown
but thought to be small since the catalyst is used repeatedly for several
batch "runs" before it is discarded.
The data presented thus far with respect to the raw materials con-
sumed, the imported intermediates, waste materials produced, and the al-
ky 1 tin production are summarized as shown:
Year
Total raw
materials
(x 10° Ib)
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
5.962
9.063
8.668
10.759
12.251
15.290
16.225
21.313
22.923
21.932
Equivalent starting
material from
imports
(x 10° Ib)
0.186
0.185
0.296
0.327
0.387
0.442
0.487
0.480
0.522
0.840
Waste materials
produced
(x 105 Ib)
1.833
2.633
2.239
2.791
3.193
3.892
4.042
5.193
5.445
5.152
Total aIky1tin
production
(x 106 Ib)
4.315
6.615
6.725
8.295
9.445
11.840
12.670
16.600
18.000
17.620
EXPOSURE TO MAN AND THE ENVIRONMENT
The possibility of exposure of man and the environment to alkyl-
tin compounds are many, as indicated in the discussion of the uses of
these compounds. Spurred by the unfortunate Stalinon incident in France
in 1954, a wealth of information has been developed on the toxicologi-
cal effects of a wide number of organotin compounds on a large number
of subjects. Unfortunately, very little published information is avail-
able concerning the rates, quantities and distribution of loss of or-
ganotins to the environment.
In the following paragraphs, .the discussion will be directed towards
the quantities of alkyltin compounds exposed to man and the environment
based on published data, the reactions of these compounds under environ-
mental conditions, and finally a brief discussion of the personnel sub-
jected to the greatest concentrations of alkyltin compounds.
110
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Alky1tin compounds from rigid PVC; The use of alkyltin compounds
as heat stabilizers for rigid, unplasticized PVC represents the largest
use area of these compounds. Within the category of heat stabilizers,
their use in rigid PVC pipe, conduit, and pipe fittings consumes ap-
proximately 50% of the total quantity produced.
Extraction data have been reported- for commercial dibutyltin-
bis(isooctylmercaptoacetate) and dimethyltin-bis(isooctylmercaptoacetate)
for tests on poly(vinyl chloride) pipe in distilled water at 100°F for
72 hr. The results show an average extraction for the dibutyl compound
to be 0.7 ppm and 0.5 ppm for the dimethyl compound; both results were
obtained using a heat stabilizer concentration of 0.6 phr. Recent in-
formation from a major organotin manufacturer shows lower results for
extraction tests for the same time and temperature stated in the pre-
vious data. These data show an aqueous extraction level of 0.11 ppm
for dimethyltin isooctylmercaptoacetate, 0.04 ppm for the correspond-
ing dibutyltin compound, and zero quantity for the dioctyltin isooctyl-
mercaptoacetate. Using the data for the higher extraction rates and
combining the two values, an average concentration of 0.6 mg/liter of
water is obtained at 100°F after 72 hr. If assuming an average consump-
tion of 2 liters of water per person per day, this equates to a daily
intake of 1.2 mg of organotin from such a source. For an average body
weight of 60 kg, the average daily intake would be 0.02 mg/kg. Using
the lower extraction rates, a considerably smaller daily intake would
be calculated. The acute oral toxicity of the dibutyl comoound is 500
mg/kg, while that for the dimethyl compound is 620 mg/kg.— Test con-
ducted by or for a major organotin producer show these values to be
919 mg/kg for the dibutyl compound and 800 mg/kg for the dimethyl com-
pound.
The above calculations obviously contain some overstatements but
represent a maximum daily intake from this source. Very little, if any,
potable water pipe within the household is PVC; its primary utility is
for water mains and, according to a local supplier of PVC pipe, only
then for towns of approximately 10,000 and under population. It is very
doubtful that water would remain stationary at 100°F for 3 days in a
water main. The assumed daily consumption of 2 liters of water per per-
son is also probably an overstatement.
Poly(vinyl chloride) food containers, stabilized with dioctyltin
compounds, probably present the most direct method for the introduction
of an alkyltin compound into the human body. Pivei4 has reported that
the diffusivity of organotin stabilizers into liquid foods and biologi-
cal fluids is approximately 10" cm /sec for rigid, unplasticized PVC
containers. To provide a slightly different perspective, this diffusion
constant (10~^ cm /sec = ~ 3 x 10 cnr/hr) is comparable to many of
111
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the constants found for the diffusion of metals into metals. Data in
the review article by Piver- show that the extraction of dioctyltin-
bis(isooctylmercaptoacetate) from PVC containers averages approximately
0.06 ppm (0.06 mg/liter of fluid) for many of the food products listed.
These results were obtained after storage of the food in the PVC con-
tainers for 2 months at 30eC. Comparing these data to that for PVC pipe,
it should be noted that the extracted quantities from PVC food containers
is approximately 10 times less than that for pipe even under extended ex-
traction time periods.
If data of this type are approximately applicable to other products
produced from rigid, unplasticized poly(vinyl chloride), then it is rather
apparent that the extent of exposure to the general public and the overall
environment resulting from the use of dialkyltin compounds as heat stabili-
zers is small.
Alkyltin compounds as catalysts; The area of catalysts for urethane
foams and silicone elastomers is basically very similar to the area of
heat stabilizers in that the dialkyltin compounds are incorporated or
entrapped in a fairly rigid structure and their exposure to the general
public and the environment is dependent upon their diffusion through the
structure to the surface. While no specific data are available, it is
felt that these diffusion processes would probably be of the same order
of magnitude as for the rigid poly(vinyl chloride). It should also be
noted that the total quantities of dialkyltin compounds involved in this
area are considerably less than those in rigid poly(vinyl chloride).
Biocidal and anthelmintic applications; The use of di- and trial-
kyltin in these two areas presents a situation in which the alkyltin
compounds are much more readily available to the environment. For an-
thelmintic applications, dibutyltin dilaurate (11)50 = 175 mg/kg) is the
only organotin compound used in this area. The tablets and granules con-
taining the dibutyltin dilaurate active ingredient are considered a med-
ication for poultry and it is presumed that these materials would be
treated with care. However, due to the physical form of this medication,
a relatively direct method of introduction of this alkyltin compound to
man and the environment does exist. The total quantities of dibutyltin
dilaurate used in this application ranged from 150,000 to 250,000 Ib
annually during the period 1965 to 1974.
The other major source of direct introduction into the environment
is the use of trialkyltin compounds in antifouling paints and coatings.
As a class, the trialkyltins are more toxic than the dialkyltinsj mono-
alkyltins are considered to be the least toxic. Bis(tributyltin)oxide
and tributyltin fluoride are the only alkyltin compounds used in this
application.
112
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It has been estimated by M&T Chemicals that 10 to 30% of the origi-
nal trialkyltin concentration is still present in the coating at the
time the spent coating is removed from the ship hull by sandblasting0~
The level of trialkyltin antifoulant in the sandblast grit was 0.05 to
0.2% by weight which, according to M&T, is unlikely to cause problems
in shipyard use. The precise method of disposal of the sandblast grit
is unknown but it is possible that a portion of the grit is collected
and removed by a contract hauler and a portion is probably deposited
in the water adjacent to the shipyard.
The major part of the trialkyltin compounds is leached from the
coating directly into the seawater. If 3 years is assumed to be a us-
able lifetime for an antifoulant coating, then 70 to 90% of the origi-
nal compound is released to the environment (seawater) during that time
span. Taking an average loss of 80% during the 3 years and assuming a
loss rate (for a 3:1 vinyl to rosin mixture5-/) of 30% for the 1st year
and 25% for each of the next 2 years, the approximate quantities of
bis(tributyltin)oxide and tributyltin fluoride introduced to seawater
can be calculated as shown below:
Approximate total Quantity released Quantity in
Year quantity used (Ib) to seawater (Ib) residual grit Clb)
1965 100,000 30,000+
1966 100,000 55,000+
1967 75,000 72,500 20,000
1968 90,000 70,750 20,000
1969 140,000 83,250 15,000
1970 151,000 102,800 18,000
1971 143,000 115,650 28,000
1972 150,000 118,500 30,200
1973 200,000 133,250 28,600
1974 320,000 183,500 30,000
In 1975, the total quantity of trialkyltin compound released to the
seawater would be 130,000 Ib from 1973 and 1974 plus 30% of the total
quantity applied in 1975. Waste grit would contain 40,000 Ib result-
ing from the removal of coatings applied in 1973. For 1965, the only
quantity released to the environment shown is 30% of the total applied
in 1965, and for 1966 the value shown is 30% of the 1966 quantity plus
25% of the 1965 value. To make these values consistent with the follow-
ing years, the value for 1965 should include 25% of the total quantity
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applied in 1963 and 1964. For 1966, 25% of the 1964 quantity should be
added. For the quantities in residual sandblast grit, the 1965 quan-
tity would be 20% of the total quantity applied in 1963 and the 1966
value would be 20% of the quantity applied in 1964. These simplified
calculations inherently assume that all coatings are applied on January
1 of the respective year and that all spent coatings are removed on
December 31 2 years hence. While these circumstances are unrealistic,
the calculated figures will perhaps provide an indication of the order
of magnitude for the quantities released to the environment by antifoul-
ant coatings.
Reactions of alkyltin compounds in the environment; The results
of studies of the degradation of alkyltin compounds show that the de-
composition process occurs by successive dealkylation of the tin com-
pound to produce stannic oxide (SnC^). M&T Chemicals has stated that
the degradation of tributyltin fluoride occurs by natural stress fac-
tors, such as ultraviolet light, heat, oxygen, and ozone, in the fol-
lowing manner:^ '
C f\ "^
•J TjJa ^ o Y* J J J
•wdi*^ i.
TBTO
'« UV UV
R3SnOSnR3 + C02 > R3SnOCOSnR3 >• 2 R2SnO 3
The initial hydrolysis of the tributyltin fluoride occurs rapidly under
very dilute conditions and the resultant bis(tributyltin)oxide is known
to readily convert to a carbonate salt in the presence of carbon dioxide,
which occurs in seawater exposed to air.^J ' It would seem likely that
the formation of the carbonate would occur in fresh water or under most
situations where the material is exposed to air.
Organotin compounds bind strongly to soil and cellulosic materials
and thus would be readily removed from waterway systems in which tur-
bulence occurs to mix the silt and mud from the bottom with the water
supply.—
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Studies of the degradation of triphenyltin acetate by ultraviolet
light show that after 60 hr irradiation, triphenyltin is 89% degraded
to diphenyltin, monophenyltin and inorganic tin.— It has been stated
that the half-life (tj/2) f°r triphenyltin acetate on plant leaves in
the field is approximately 4 days and that ensilage causes a complete
breakdown to inorganic tin within 5 weeks.—'
According to M&T Chemicals, any dialkyltin compounds present in
the waste material are sufficiently degraded after 18 days in their
waste treatment lagoon that the material can be safely discharged
Worker exposure: It has been stated by M&T Chemicals that manu-
facturing personnel will generally face the greatest potential hazard
from organotin compounds.— This should also include personnel involved
in the processing of materials containing alkyltin compounds. The po-
tential for exposure to alkyltin compounds for man and the environment
from the final consumer products containing these materials is cer-
tainly present. However, in view of the slow diffusion rates of al-
kyltins from the majority of the final products and the moderately
rapid, if weeks can be considered moderately rapid, degradation of
these materials to lower alkylated forms and to inorganic tin, the
greatest potential for general exposure to the general public and the
environment would appear to be in those instances when direct inges-
tion of alkyltins can occur.
Accidental exposures to the public within the immediate vicinity
of production facilities obviously can occur and could lead to situa-
tions that may endanger the health and life of humans or animals. The
incident at the methyltin production facility in Kentucky would serve
as an example in which the loss of animal life occurred. The facility
was voluntarily shut down and has not been restarted as of this date.
Almost all of the alkyltin compounds included in this study are
eye and skin irritants and will cause irritation to the upper respira-
tory tract. Workers can be directly exposed to skin contact and inhala-
tion of the fumes and particles of alkyltin compounds during the manu-
facture and handling of these materials, as well as the fumes emitted
during the extrusion processes with PVC resin incorporating these heat
stabilizers. Precautions employed by the manufacturers and processors
to help protect workers from the effects of these compounds have been
discussed earlier in this report.
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Thus, in view of the available data, it would appear that the
greatest potential for exposure and health effects of such exposures
would occur with the .workers. After the alkyltin compounds have been
incorporated into the final consumer products, it would appear that,
in general, the potential for exposure to man and the environment is
small and not likely to pose a human or environmental health hazard*
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REFERENCES FOR SECTION IX
1. Cincinnati Milacron Chemicals, Inc., U.S. Patent 3810868 (1974).
2. Bokranz, A., and H. Plum, Fortschritte der Chem. Forschung, 16,
366 (1971).
3. Piver, W. T., Environmental Health Perspectives, 4_, 61, June 1973.
4. Engelhart, J. E., and A. W. Sheldon, 15th Annual Marine Coatings
Conference, Point Clear, Alabama, February 1975.
5. Beiter, C. B., et al., Symposium on Marine and Fresh Water Pesti-
cides, American Chemical Society Meeting, Atlantic City, New
Jersey, August 1974,
6. Sheldon, A. W., J. Paint Tech., 47_, 54 (1975).
7. Vizgirda, R. J., Paint and Varnish Production, December 1972.
8. Chapman, A. H., and J. W. Price, Int. Pest Control, pp. 11-12,
January-February 1972.
9. Sawyer, A. K., Ed., Organotin Compounds, 3rd Ed., Marcel Dekker,
Inc., New York (1971).
10. Personal communication, A. A. Keller, M&T Chemicals, Inc.
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SECTION X
USE ALTERNATIVES
In this section, possible alternative methods of production and
end-use materials are discussed. Topics include alternative raw mate-
rials and production processes, as well as alternative materials for
the current end-uses of the organotin compounds* »
ALTERNATIVE RAW MATERIALS
Very little work has been reported regarding new synthetic methods
for the production of aIky1tin compounds which could utilize present
production facilities. The commercial market for these compounds is
rather small (~ 17 million pounds) as compared to other commercial
products in this same general area of PVC additives, e.g., alkyl and
aryl phosphate esters are ~ 100 million pounds per year. Thus the al-
kyltin market is very competitive with each company seeking any slight
advantage to increase their share of the market or profit margin. The
present production methods have been refined over the years to produce
alkyltin compounds in the most efficient manner at the lowest possible
costs. Any alternative raw materials that could be suggested would re-
sult in a material being produced at a lower yield with more expensive
raw materials than the present process.
ALTERNATIVE MANUFACTURING PROCESSES
It has been known for many years that alkyl aluminum compounds
could be used as alkylating agents for stannic chloride to produce
tetraalkyltins. However, it has only been within the last few years
that alkyl aluminum compounds have been commerically available in large
quantities for use in the Ziegler stereospecific polymerization of ole-
fins. With the large quantities of alkyl aluminums available, an effort
was made to utilize this process for the manufacture of tetraalkyltin
compounds.
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For the preparation of tetrabutyltin,— 35 parts by weight of tri-
butyl aluminum and 11 parts by weight of NaCl are mixed into 60 parts
by weight of methylene chloride. While stirring, a mixture of 3004 parts
by weight of stannic chloride in 60 parts by weight of methylene chloride
is slowly added with the temperature being maintained between 40 and 150 Cc
After the reaction is complete, the methylene chloride solvent is removed
by distillation. Thus, 39.6 parts by weight (97% yield) of the theoretical
amount of tetrabutyltin is obtained. The addition of a complexing agent,
NaCl, reacts with the aluminum chloride formed during the reaction and
prevents its reaction to dealkylate the tetraalkyltin compound by the
formation of a complex salt, i.e., NaAlClA. Other complexing agents,
which may be utilized, include ethers and tertiary amines. After comple-
tion of the reaction, the tetraalkyltin compound can be separated from
the complex salt by-product by decanting or centrifuging, since the com-
plex salt is insoluble in the tetraalkyltin and, upon cooling, will set-
tle to the bottom of the reactor. To the best of our knowledge, the pro-
duction of tetraalkyltin compounds by this method is a batch process.
Based on an estimated price of $1.00/lb for tributylaluminum,— $2.104/lb
for stannic chloride (anhydrous),-^' and $1.99/100 Ib for NaCl,- the
calculated cost per pound of tetrabutyltin would be $2.41 (based only
on raw material cost). The cost of methylene chloride solvent was not
included since this material is stripped from the reactor and recycled.
It should also be noted that for each pound of tetrabutyltin (or tetra-
octyltin), 0.736 Ib of waste NaAlCl/ would be generated. The estimated
cost of tri(n-octyl)aluminum is $1.50/lb for large scale purchases.—'
Both tributylaluminum and tri(n-octyl)aluminum are liquids that
must be stored, transferred, and reacted in the absence of air (0£)
or moisture, as these will react with either of the two alkylaluminums.
Both aluminum compounds are highly pyrophoric and will also react with
any acidic hydrogen.—'
To date there is only one producer of tetraalkyltin compounds,
or derivatives of these, via the alkylaluminum route, Shering AG in
Germany. Shering has expanded their facilities in the last few years,
not only for the butyltins but also for octyltins, and exported con-
siderable quantities to the United States. At the present time,
Shering does not manufacture organotin heat stabilizers, only the
intermediates. It is common knowledge in the organotin industry that
Shering is presently exploring plans to either purchase or develop a
manufacturing facility in the U.S.
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ALTERNATIVE FINAL USE PRODUCTS
From recent review articles in trade publications related to the
plastics industry, PVC, and heat stabilizers (e.g., Modern Plastics,
Popular Plastics. Plastics Technology. Plastics Engineering, etc.),
it is apparent that much of the current emphasis in the heat stabilizer
area is directed towards finding replacement materials for the heavy
metal stabilizers, particularly cadmium, with relatively little thought
to the organotin compounds. Thus most of the new products are directed
more towards the flexible PVC applications rather than to the rigid
applications.
For alternative stabilizers in PVC applications intended to con-
tact food, Ca-Zn type stabilizers have FDA approval, as must all ma-
terials to be used in this area. Ca-Zn stabilizer systems generally
are calcium and zinc salts of fatty acids, which require high epoxy
and high phosphite content. These stabilizer systems are currently
priced in the range of $1.25 to $1.28/lb-* but require higher resin
loadings than organotin compounds to provide the same amount of heat
stability. Argus Chemical Corporation has an organophosphite chelat-
ing agent (Mark 1500) for use in conjunction with the nontoxic Ca-Zn
systems in rigid PVC. This additive, priced at $1.17 to $1.20/lb,
provides better clarity and improved processing conditions but is
not suitable for rigid PVC applications outside of FDA approval areas.—
In Europe, nonmetallic organic compounds have been used in con-
junction with calcium stearate for many years as heat stabilizers for
PVC, especially those intended to contact food. Two of these materials
are currently being marketed in the U.S. by Mobay Chemical Corporation
as heat stabilizers C and I-FF (1097).-' Stabilizer C is diphenylthio-
urea and can find usage in both rigid and plasticized PVC compounds.
It has FDA sanction for additions up to 0.5 phr and is priced at $1.22
to $1.26/lb depending upon quantity purchased. Stabilizer I-FF (1097)
is 2-phenylindone and is used in unplasticized emulsion-polymerized
PVC formulations at a level of 0.5 to 1.0 phr in blow-molded-bottles.
Its use in PVC intended to contact food has been approved in several
European countries but no FDA approval has been obtained in the U.S.
Stabilizer I-FF (1097) is a flammable liquid, which would necessitate
careful handling in areas near high temperature sources. It is cur-
rently priced at $1.77/lb in quantities greater than 1,650 lb.—
For clear rigid nonfood applications in homo- and copolymers,
there are virtually no nontin materials that can withstand the rig-
orous processing conditions and still produce an acceptable end prod-
uct. Only one nontin containing material has been recently introduced
which may be an alternative heat stabilizer. Synthetic Products Com-
pany has recently introduced antimony-tris(isooctylmercaptoacetate)
to be used in combination with calcium stearate to achieve maximum
stabilizing potential^' The combination is directed primarily at
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the PVC pipe and conduit market: as of this time, NSF approval has not
been obtained for this combination in potable water pipe. The antimony
compound is currently priced from $1.39 to $1.69/Ib depending upon which
type of material is desired.
New tin-containing materials have been introduced to compete with
the established materials but the antimony compound is the only nontin-
containing material. Among the newer tin-containing materials, Cincinnati
Milacron Chemicals Inc., has recently introduced TM-692 and TM-585.
TM-692 is a methyltin alkylmercaptoethanoate, containing alkyl groups
in the Cj^ to C18 range, and is priced at $1.66/lb. Other new tin-
containing compounds or mixtures could be cited but they would only
constitute substitutions for current materials, not alternatives.
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REFERENCES TO SECTION X
1. Kali-Chemie Aktiengesellschaft, Brit, patent 802,796, October 8, 1958.
2. Mr. George Miller, Stauffer Chemical Company, Westport, Connecticutt.
3. "Chemical Marketing Reporter," 11/24/75 and 11/17/75 issues.
4. Argus Chemical Corporation, Chicago, Illinois sales office.
5. Mobay Chemical Corporation, Chicago, Illinois sales office.
6. Plastics Engineering, p. 24, September 1975.
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