EPA-600/2-77-126
July 1977
Environmental Protection Technology Series
USE OF ORGANIC SOLVENTS
TEXTILE SIZING
AND DESIZING
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental Protection
Agency, have been grouped into five series. These five broad categories were established to
facilitate further development and application of environmental technology. Elimination of
traditional grouping was consciously planned to foster technology transfer and a maximum
interface in related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION TECHNOLOGY
series. This series describes research performed to develop and demonstrate instrumenta-
tion, equipment, and methodology to repair or prevent environmental degradation from point
and non-point sources of pollution. This work provides the new or improved technology
required for the control and treatment of pollution sources to meet environmental quality
standards.
EPA REVIEW NOTICE
This report has been reviewed by .the U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily reflect the views and
policy of the Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
This document is available to the public through the National Technical Information Service,
Springfield. Virginia 22161.
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EPA-600/2-77-126
July 1977
USE OF ORGANIC SOLVENTS
IN TEXTILE SIZING
AND DESIZING
by
W.S. Perkins, D.M. Hall, B.L. Slaten,
R.P. Walker, and J.C. Farrow
Alabama Textile Education Foundation
115 Textile Building
Auburn, Alabama 36830
Grant No. R803665
Program Element No. 1BB610
EPA Project Officer Max Samfield
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, N.C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
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FOREWORD
Most of the work done in this study involved the use of tetra-
chloroethylene (perchloroethylene) as the solvent for textile slashing
and desizing operations. On March 25, 1977, the National Cancer Institute
reported that perchloroethylene is a carcinogenic material, causing
liver cancers in mice. The report covering these findings will be
available from the National Cancer Institute about July 1, 1977.
This report has been reviewed by the Industrial Environmental
Research Laboratory, U. S. Environmental Protection Agency, and approved
for publication. Such approval does not constitute endorsement or
recommendation for use of perchloroethylene in textile processes.
K./Burchard, Director, IERL/RTP
iii
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KBSTBPCT
Results of a study of slashing and desizing in organic solvents are re-
ported. Properties of materials applicable as warp sizes in systems utilizing
organic solvents were satisfactory for utilization as warp sizes. Evaluations
wherein solvent sized yarns were successfully woven into fabric using conven-
tional weaving techniques are described. Properties of fabrics made from sol-
vent sized yarns are compared to properties of fabrics made from aqueous sized
yarns. No deterioration in quality of the fabric occurred when organic sol-
vents replaced water in slashing and desizing.
The energy consumption of solvent slashing and desizing systems is com-
pared to energy consumption in conventional aqueous systems. Total energy con-
sumption of solvent slashing and solvent desizing systems currently available
is essentially equivalent to that in conventional aqueous systems.
Economic aspects of solvent slashing and desizing are discussed. Cost of
solvent and aqueous slashing and desizing were nearly equivalent when the cost
calculation included 1983 wastewater treatment costs. The majority of the
materials cost in solvent slashing and desizing is the cost of solvent lost in
the process. Elimination or reduction of the 7.2% loss calculated in this
study could result in a distinct cost advantage for the solvent system.
Solvent slashing and desizing would eliminate virtually all of the BOD
load typically resulting from sizing and desizing. The retention of perchloro-
ethylene in polyester fiber can be maintained at a very low level provided the
temperature of exposure of the fiber to the solvent is below the glass transi-
tion temperature of the fiber. Perchloroethylene is rapidly and easily remov-
ed from cotton fibers in the drying process. Solvent loss to the atmosphere
from currently available solvent slashing and desizing machinery is reported
to total about 0.0723 pounds per pound of fabric. Reductions in this level
of loss can probably be expected if the machinery and techniques are refined.
This report was submitted in fulfillment of EPA Grant No. R803665 by the
Auburn University Textile Engineering Department under the partial sponsorship
of the U.S. Environmental Protection Agency. The work was performed in cooper-
ation with the Alabama Textile Education Foundation through the Auburn Univer-
sity Engineering Experiment Station. This report covers the period from May 1,
1975 to December 31, 1976 and work was completed as of January 15, 1977.
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CONTENTS page
Foreword iii
Abstract iv
Figures vi
Tables vii
Abbreviations and Symbols ix
Acknowledgement x
1. Introduction 1
2. Conclusions 4
3. Recommendations 6
4. Properties of Solvent Sizing Materials 7
5. Properties of Solvent Sized Yarns 12
6. Weaving of Solvent Sized Yarns 24
7. Fabrics Containing Solvent Sized Yarns 27
8. Solvent Removal During Drying 32
9. Effects of Solvent Sizing and Desizing on the Environment. . 44
10. Energy Consumption of Aqueous and Solvent Sizing and Desizing 54
Systems
11. Economic Evaluation of Solvent Sizing and Desizing 60
Reports and Publications 65
Appendices 66
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FIGURES
Number Page
1 Schematic Diagram of a Solvent Slashing and Solvent
Desizing Process 3
2 Schematic Diagram of Single Yarn Size Applicator 13
3 Schematic Diagram of Laboratory Slasher 14
4 Photograph of the Laboratory Slasher 15
5 Scanning Electron Micrograph of 100% cotton yarns
unsized (first 3 on left) and containing about 15%
by weight of ethyl cellulose (last 4 on right).
Magnification 20X 20
6 Scanning Electron Micrograph of 100% Cotton Yarns
containing about 10% by weight of Polyvinyl Alcohol.
Magnification 100X. 21
7 Scanning Electron Micrograph of 100% Cotton Yarns
containing about 12% by weight of Hydroxypropyl
Cellulose. Magnification 100X 22
8 Weave, draw and cam drafts used for weavability trials 25
9 Effect of Bath Temperature on the Retention of
Perchloroethylene in Polyester Fabrics 34
10 Effect of Perchloroethylene Bath Tenperatures
on the Retention of Perc in Polyester Fabrics 35
11 Weight Percentage of Perchloroethylene Retained
by Polyester Fabric After Drying for 2.5 Minutes
at Various Ternperatures 39
12 Weight Percentage of Perchloroethylene Retained
by Polyester Fabric After Drying for 5.0 Minutes
at Various Tenperatures 40
13 Solvent Sizing Flow Diagram 58
14 Solvent Desizing Flow Diagram 59
vi
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TABLES
Number Page
1 Properties of Ethyl Cellulose, Hydroxypropyl
Cellulose, Polyvinyl Alcohol and Carboxymethyl
Cellulose 10
2 Breaking Strength of 100% Cotton and 50/50
Polyester/Cotton Blend Yarns Sized with Polyvinyl
Alcohol from Water, Ethyl Cellulose from Perchloro-
ethylene or Hydroxypropyl Cellulose from Water 17
3 Elongation at the Break of 100% Cotton and 50/50
Polyester/Cotton Blend Yarns Sized with Polyvinyl
Alcohol from Water, Ethyl Cellulose from Perchloro-
ethylene or Hydroxypropyl Cellulose from Water 18
4 Abrasion Resistance of 100% Cotton and 50/50
Polyester/Cotton Blend Yarns Sized with Polyvinyl
Alcohol from Water, Ethyl Cellulose from Perchloro-
ethylene or Hydroxypropyl Cellulose from Water 23
5 End Breakage Rates for Warps Sized with Various
Sizing Materials 26
6 One-Inch Ravelled Strip Strength and Elongation for
Fabrics Sized with Various Sizing Materials 28
7 Tear Strength for Fabrics Sized with Various Sizing
Materials as Determined on the Elmendorf Tear Tester 29
8 Abrasion Resistance of Fabric Samples Sized with
Various Sizing Materials 30
9 Retention of Perchloroethylene by Polyester Fabric
After Immersion for 15 Minutes at Various Bath Tem-
peratures and Ambient Air Drying 36
10 Rates of Removal of Perchloroethylene from Polyester
Fabric at Various Drying Temperatures 38
11 Retention of Perchloroethylene in Polyester Fabric
After Drying the Perc Saturated Fabric for 2.5 and
5.0 Minutes at Various Temperatures 38
vii
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Number Page
12 Rates of Removal of Dichloromethane f ran Polyester
Fabric 42
13 Retention of Dichloromethane in Polyester Fabric
After Drying the Saturated Fabric for 2.5 and 5.0
Minutes at Various Temperatures 42
14 Energy Consumption, Exhaust Air Quality and Cost
for Sizing Warp Yarn with Aqueous Systems in Typical
Plants 45
15 Energy Consumption, Exhaust Air Quality and Cost
for Desizing with Aqueous Systems in Typical Plants 46
16 Pollutional Load Contributed by Desizing Various
Sizing Materials 48
17 Environmental Effects of Aqueous and Solvent Sizing
(Slashing) Systems 49
18 Environmental Effects of Aqueous and Solvent Desizing
Systems 52
19 Summary of Enviroranental Effects of Aqueous and
Solvent Sizing and Desizing Systems 53
20 Energy Consumption of Aqueous and Solvent Sizing
(Slashing) Systems 55
21 Energy Consunption of Aqueous and Solvent Desizing
Systems ..... 56
22 Summary of Energy Consumption of Aqueous and Solvent
Sizing (Slashing) and Desizing Systems 56
23 Costs of Aqueous and Solvent Sizing (Slashing)
Systems 61
24 Costs of Aqueous and Solvent Desizing Systems 62
25 Summary of Costs of Aqueous and Solvent Sizing
(Slashing) and Desizing Systems 63
viii
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
BAT — Best Available Technology
BOD — Biochemical Oxygen Demand
BPT — Best Practicable Control Technology
CMC — carboxymethyl cellulose
cm — centimeter (s)
COD — Chemical Oxygen Demand
EC — ethyl cellulose
HPC — hydroxypropyl cellulose
in — inch(es)
mil — 0.001 inch
min — minutes
oz — ounce (s)
PE — polyester
perc — perchloroethylene
psi — pounds per square inch
PVA — polyvinyl alcohol
sec — second (s)
ix
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ACKNOWLEDGEMENT
This work was performed under Grant No. R803665 of the U.S. Environmen-
tal Protection Agency. Also sharing in the costs of the work were the Engi-
neering Experiment Station and Water Resources Research Institute of Auburn
University and the Alabama Textile Education Foundation. The support of these
groups is acknowledged and appreciated.
Thanks are due the Agricultural Research Service of the U.S. Department
of Agriculture at Khoxville, Tennessee, for the loan of the laboratory slash-
er used in the project. Dr. Harmon Ramey is thanked for his help in making
the arrangements for the loan.
Hercules, Inc. supplied numerous product samples at no cost to the pro-
ject. This support is gratefully acknowledged. Thanks are also expressed to
all other chemical companies who kindly supplied samples at no cost to the
project.
Special thanks are expressed to Professor James C. Warman/ Director of
the Water Resources Research Institute at Auburn University and Project Mana-
ger for this study. His guidance in financial matters, editorial assistance
and general management of the project were invaluable.
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SECTION 1
INTRCOUCTICN
Warp sizes make a sizeable attribution to the waste load from a textile
finishing plant. Published data indicates that 45% of the BOD load from a
textile finishing plant usually results from warp sizes, and as much as 75%
of the BOD load may result from this source. This BOD loading by warp sizes
comes from three processes. Slashing, application of size to give the yarn
the necessary characteristics for weaving, contributes some waste size
material which must be discharged. Desizing and scouring, conversion of the
size to water soluble products and removal of these materials from the woven
fabric, also contributes greatly to the BOD load. Many figures on the BOD
load resulting from desizing and scouring are available in the literature.
However, these figures differ greatly depending on the source from which they
are obtained and the type of process they represent. Therefore, the hypo-
thetical situation described below is probably as typical as any published
data.
If a fabric consisting of 60% warp is being processed and the warp
yarn in the fabric contains 15% starch size, then 90 pounds* of starch will
be removed from each 1000 pounds of fabric processed in the desizing and
scouring. Since starch has a BOD of approximately 50%, 45 pounds of BOD per
1000 pounds of fabric will result. Also, 5% fats, waxes and oils having
BOD of about 80% will be removed from the fabric. This will contribute an
additional 4 pounds of BOD per 1000 pounds of fabric processed. If 10 gal-
lons of water are used per pound of fabric in these processes, this 49 pounds
of fabric will give a wastewater from these processes of 588 ppm of BOD.
While the greatest polluting characteristic of starch based warp sizes
is the BOD load generated, the amounts of COD and suspended and dissolved
solids are also large. This is especially true where sizes such as carbox-
ymethyl cellulose (CMC) or polyvinyl alcohol (FVA) are substituted for starch
sizes. Substitution of these materials lowers the BOD load from the process,
but they must be dealt with from the standpoint of COD and suspended solids.
The logic for study of the application of size materials to warp yarns
from organic solvents is in the potential for recovery and reuse of the
solvent and size material. Solvent technology in textile processing has been
the subject of much study in recent years. The solvents which have been
deemed most appropriate for processing of textile materials are the chlori-
nated hydrocarbons. Dichloromethane, 1, 1, 1- trichloroethane, trichloro-
*English units are most commonly used and best understood in the textile in-
dustry. Factors for conversion to metric units are in Appendix 1.
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ethylene and tetrachloroethylene (perchloroethylene) have all been found
applicable in certain processes. Of these, perchloroethylene (perc) has
been most studied and used. Most of the work done in this study involved
the use of perc, but in certain instances 1, 1, 1,- trichloroethane,
dichloraraethane and 1, 1,2- trichloro-1,2,2- trifluoroethane ware used. The
properties of these solvents are extensively documented.
Since cotton, polyester and blends of these two fibers comprise the
largest group of textile fabrics, these fibers were used for this work.
The process which was the subject of the research proposal leading to
this study is diagrammed schematically in Figure 1. The size material would
be applied to the yarn in an enclosed size box probably at room temperature.
The solvent would be removed from the yarn in an enclosed drier and reclaimed
by condensation. The size would be removed from the fabric using solvent.
Insoluable impurities such as loose fiber would be removed by filtration.
The size solution from desizing would be distilled to recover most of the
solvent and to concentrate the solution back to the solids content required
for sizing.
The results reported in the following sections pertain to properties of
potential solvent warp sizes, weaving performance of yarns containing solvent
sizes, and the environmental and economic impact of sizing/desizing systems
using organic solvents.
Early in the project the idea evolved that size which could be desized
using an organic solvent but which could be applied in slashing using con-
ventional aqueous techniques would be more acceptable and more easily
adaptable in the textile industry than a complete solvent slashing/solvent
desizing system. Further, this aqueous slashing/solvent desizing would still
accomplish the objective of reclamation of the size material for reuse.
Therefore, an additional aspect of the work was to determine the potential as
warp sizes of materials which are soluble in both water and organic solvents.
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WARP
RECLAIMED
SIZE STORAGE
FINISHING
ADO
VIRGIN
SIZE
FIGURE 1. SCHEMATIC DIAGRAM OF YARN,FABRIC, SOLVENT AND SIZE FLOW IN A SOLVENT SLASHING,
SOLVENT DESIZING SYSTEM.
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SECTION 2
OCCLUSIONS
Textile yarns nay be sized vising perchloroethylene or methylene chloride
as the size application medium. Ethyl cellulose and hydroxypropyl cellulose
are applicable as warp sizes from these solvents, respectively. These sol-
vent warp sizes can be desized using organic solvents after which the solvent
and size material can be partially recovered through a distillation process.
The properties of the recovered size and solvent are adequate for recycle.
Since the cost of production of a woven fabric depends very closely on
the efficiency with which the yarn can be woven into fabric, much work was
done regarding the performance of the solvent sized yarns. The properties of
yarns sized with ethyl cellulose and hydroxypropyl cellulose were essentially
equivalent to those of aqueous sized yarns. Weaving tests indicated that the
solvent sized yarns can be woven satisfactorily into fabric.
The properties of fabrics made from solvent sized yarns are equivalent
to properties of fabrics from yarns sized by conventional aqueous techniques.
Fabrics made from solvent sized yarns can be processed satisfactorily through
conventional aqueous scouring, bleaching, dyeing and finishing processes sub-
sequent to the desizing step.
Polyester fibers absorb perchloroethylene when the fibers are exposed to
the solvent at elevated temperatures. Some of this solvent is released by
the fiber only slowly even at high drying temperatures. Thus, perchloro-
ethylene loss from polyester scouring systems, which has often been reported
as 3% to 7% of fabric weight, probably results mainly from solvent carried
out of the system in the fiber. However, polyester fibers absorb and retain
little or no solvent if the ejqaosure of the fiber to the solvent is at room
temperature. Since solvent slashing and desizing can be done at room
temperature solvent loss from these processes could conceivably be reduced to
very low levels if the machinery and techniques are refined. Cotton fibers
do not present the solvent retention problems that are encountered with poly-
ester because they do not absorb and retain perchloroethylene. The solvent
is quickly and easily removed from this fiber with heat.
Solvent desizing would substantially reduce or eliminate that portion of
wastewater treatment typically resulting from the desizing process. The
environmental advantage of this is similar to that which is obtained by
recovery of polyvinyl alcohol (EVA) by hyperfiltration. Cost comparison of
size recovery by solvent systems and hyperfiltration could not be made in
this project because complete information on energy consumption in PVA
desizing and recovery by hyperfiltration could not be obtained.
Loss of solvent to the atmosphere from solvent slashing and desizing of
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polyester/cotton blends can be reduced to very low levels provided exposure
of the fabric to the solvent is below the glass transition temperature of the
polyester, machinery maintenance is adequate and carbon absorption units are
used to clean the air.
The solvent slashing and desizing systems currently available consume
about the sane total amount of energy as conventional aqueous systems. If
the drying of the fabric between desizing and subsequent processes can be
eliminated, energy consumption in the solvent process would be considerably
less than in the aqueous process. This may be possible with 100% synthetic
materials where the desizing and scouring processes might be combined. How-
ever, these processes cannot at present be combined if the material contains
cotton since perchloroethylene is not effective in the removal of motes from
the cotton. Therefore, solvent slashing and solvent desizing may be more
readily and economically applicable to yarns containing only fibers such as
polyester, nylon, acrylics, glass, etc. which do not contain the large
amounts of nonfibrous impurities found in cotton.
The economic comparison of solvent slashing and desizing to aqueous
slashing and desizing depends on the level of recovery and recycle of
materials that can be achieved. Cost of energy, machinery and wastewater
treatment are all much smaller than cost of materials in both aqueous and
solvent sizing and desizing systems. Therefore, it is the cost of the size
material and cost of solvent lost which largely determines the relative
economics of the tvro types of processes. At total solvent losses of 0.072
pounds per pound of fabric processed and size material loss of 15% of the
amount applied to the yam, the costs of aqueous and solvent slashing and
desizing are approximately equal. Much higher solvent and size recovery
levels are feasible and if attained in practice would result in a significant
cost advantage for solvent sizing and desizing compared to aqueous systems.
While this study was concerned primarily with solvent sizing and solvent
desizing, the feasibility of aqueous sizing with nydroxypropyl cellulose and
subsequent desizing in methylene chloride was also investigated. This type
of process appears feasible and would circumvent the solvent sizing equip-
ment cost that would be necessary for solvent slashing. The benefits of
recovery and recycle of the size material should be available in this type
of system.
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SECTION 3
The technical and economic feasibility of sizing and desizing vising
organic solvents has been demonstrated on a laboratory scale. Since the
economic success of woven fabric itanuf acturing depends greatly on the
efficiency with which the yarn can be woven into fabric, in-plant demonstra-
tions will be necessary to determine whether or not solvent slashing and
desizing are commercially practical.
The studies reported herein pertain mainly to processing of cotton and
blends of polyester with cotton. However, solvents such as perchloroethylene
are very efficient in cleaning synthetic fibers such as polyester and not so
effective for cleaning of cotton. Therefore, solvent slashing and desizing
may be more readily applicable to yarns and fabrics containing only
synthetic fibers. Further study is needed of solvent desizing of 100%
synthetic fabrics wherein the desizing and scouring processes might be
combined.
The data on solvent retention by polyester fibers reported herein is
applicable to other processes such as scouring and finishing in which poly-
ester is treated in perchloroethylene. The polyester fibers should be ex-
posed to the solvent only at temperatures below the glass transition temp-
erature of the fiber so that efficient removal of the solvent from the fiber
can take place in the drying step.
The feasibility of slashing in aqueous medium and subsequently desizing
in solvent medium should be studied in greater depth. The shift from water
to organic solvent in slashing would require a high level of education and
retraining of personnel since the process as now performed in the textile
industry does not require the usage of sophisticated chemical and chemical
engineering technology as would be required for solvent slashing. On the
other hand, the solvent desizing process would be carried out in finishing
plants where the personnel are trained in chemical handling techniques and
in many instances have experience in the use of organic solvents. There-
fore, the shift to use of solvents in desizing would not represent nearly as
great a technology change as would be required for solvent slashing. Con-
sequently, an aqueous slashing process that could be used in conjunction with
solvent desizing could be a valuable development if economically and envi-
ronmentally advantageous. Further study of a process of this type is needed.
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SECTION 4
PROPERTIES OF SOLVENT SIZING MATERIALS
EXPERIMENTAL PROCEDURES
Film Casting
Films were cast from dilute solutions in the appropriate solvent. The
solution was poured on mercury in a square dish or spread uniformly on glass
to allow the solvent to evaporate.
Tensile Properties
Strips of film 0.5 inches (1.27cm) wide and of measured thickness were
broken on an Instron Tensile Tester. The gauge length was 3 inches, and the
crosshead speed was 2 inches/minute.
Flexibility
Strips of film 1.0 inches (2.54 cm.) wide were wrapped around a one-inch
(2.54 cm) diameter glass rod. The test was performed at 2QOC, OOC and -KPC.
If the film could be wrapped around the rod without cracking, it was rated as
having passed the test.
Resolubility
The length of time necessary for a 0.003 inch (3 mil) thick film to
dissolve in the appropriate solvent at the appropriate temperature was
determined.
Adhesion
Strips of the fiber substrate (cellophane or mylar polyester) 1 inch
(2.54 cm) wide by 7 inches (17.78 on) long were used for the adhesion tests.
One (1) drop of the size material dissolved in the appropriate solvent at 5%
solids concentration was placed on the end of one (1) strip of film. A
second strip of film was placed over the first with a one (1) square inch
overlap. The strips were placed under 10 pounds {4.54 kilograms) of pressure
for 12 hours at 50°C to dry. The force necessary to separate the strips was
determined using an Instron Tensile Tester.
SIZE SELECTION
Since the polymers commonly used as warp sizes for textile yarns are not
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soluble in chlorinated hydrocarbon solvents such as perchloroethylene (perc),
the initial phase of the research involved screening a large number of poly-
mers for solubility in organiq. solvents. This screening resulted in the
selection of ethyl cellulose (EC) of various types and grades for further
study. The ethyl celluloses are soluble in perc in concentrations high
enough to apply them to yarns in slashing but they are not soluble in water.
Also selected for further study were several grades of hydroxypropyl cellu-
lose (HPC). Hydroxypropyl cellulose is not soluble in perc but is soluble in
dichlorcmethane or mixtures of 1, 1, 1-trichloroethane and isopropanol. HPC
is also soluble in water at room temperature but precipitates when the water
temperature rises to about 40-45°C. Therefore, a process using ethyl cellu-
lose as the size ngteT* qi would require the use of perc for both size
application and desizing. Cn the other hand, hydroxypropyl cellulose can be
applied in sizing from either cold water or msthylene chloride and also de-
sized from the fabric using either water or the organic solvent.
SIZE FUM PHYSICAL PROPERTIES
All size materials are film forming agents. It is generally accepted
that physical properties of films of size materials can be used to predict
the effect of the size on yarn physical properties. The physical properties
of the yarn in turn affect the performance of the yarn in weaving. Size
material film properties which affect the properties of the yarn to which
they are applied include tensile strength, elongation, flexibility and ad-
hesion to the fiber being sized. Each of these properties was measured using
films of ethyl cellulose and hydroxypropyl cellulose and compared to proper-
ties of films of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) f
typical aqueous warp sizes.
The size material must possess sufficient tensile strength to bond to-
gether the individual fibers in a yarn. However, the strength of the size
material must be low enough to allow the yarns to be separated at the slasher
split rods without causing yarn breakage. Polyvinyl alcohol is known to
cause splitting problems in certain cases, and the add-on of polyvinyl
alcohol to the yarn must be low if fine yarns are to be sized successfully.
The tensile strength of ethyl cellulose (Table 1) is probably satisfactory
for warp sizing purposes. However, its high tensile strength implies that
control of add-on may be necessary to enhance splitting at the lease rods.
The tensile strength of hydroxypropyl cellulose appears ideal for warp
sizing.
Sufficient elongation of the size materials is necessary if the material
is to withstand the repeated cyclic stresses encountered by the yarn in
weaving. A certain minimum elongation of 4-5% is desirable, but higher
elongation is not essential. The elongation of hydroxypropyl cellulose is of
the same order of magnitude as that of polyvinyl alcohol. The elongation of
ethyl cellulose is similar to that of carboxymethyl cellulose, a commonly
used warp size. While the elongation of ethyl cellulose is much lower than
that of polyvinyl alcohol, the elongation of ethyl cellulose is probably
adequate for good performance as a warp size.
8
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A warp size must be easily removable from the woven fabric in desizing.
ease of removal of the size material is related to its solubility in the
desizing medium. Polyvinyl alcohol is normally desized using large volumes
of hot water. Films of ethyl cellulose dissolved more rapidly in perchloro-
ethylene at 25 °C than did films of polyvinyl alcohol in water at 100 °C.
Hydroxypropyl cellulose films dissolved as readily in water or dichloro-
methane at 25 °C as did polyvinyl alcohol in water at 100 °C. Heating of films
of ethyl cellulose and hydroxypropyl cellulose at 110 °C for 6 hours had little
effect on the ability of the film to dissolve in the test solvent.
Adhesion of the size material is imperative since the size must bond to-
gether the fibers in the yarn. Further, the size material must adhere to
both fibers if the yarn being sized is a blend. Ethyl cellulose does not
adhere as well to either polyester or cellulose as does polyvinyl alcohol.
Hydroxypropyl cellulose adheres well to both polyester and cellulose.
Flexibility of size materials is desirable since the size film on the
yarn must withstand repeated bending as the yarn passes through the weaving
elements. Ihe flexibility of both ethyl cellulose and hydroxypropyl cellu-
lose is excellent in the freshly cast film. Recovered ethyl cellulose and
ethyl cellulose exposed to elevated temperatures for extended periods of time
was brittle. The embrittlerosnt of the ethyl cellulose can be attributed to
oxidation.
Antioxidants can be added to ethyl cellulose formulations to alleviate
the problem. However, even with an antioxidant present in the size film at
a concentration of 1-3% by weight, the ethyl cellulose became brittle when
heated for one (1) hour at 110°C.
DKYING CHARftCTEKISTICS OF EKDROXYPRCPYL CELLULOSE
Since hydroxypropyl cellulose is not soluble in water at temperatures
greater than 45-50°C, tests were performed to ascertain whether satisfactory
films formed from solutions of HPC in water when heat is used to vaporize the
water. Film formation by the size material on the yarn is necessary to
achieve good size performance.
Thin coatings of a 5.0% aqueous solution of hydroxypropyl cellulose
(HPC) were applied to glass plates. Individual plates were dried at differ-
ent temperatures ranging from room temperature to 200 °C. The appearance of
the HPC during drying was observed and tensile properties of the resulting
films were measured.
When the drying temperatures was below 45°C, the HPC formed a clear
film from the clear solution of HPC on the glass. At drying temperatures
above 50°C, the HPC solution on the glass became cloudy, and a film formed
over the top of the liquid. The solution dried gradually from edge to
center of the glass plate leaving a clear film appearing virtually the same
to the eye as the film deposited at temperatures below 45°C. However, the
physical properties of the films deposited at high and low temperatures were
not the same. The films formed at 85°C had tensile strength of about 1500
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TABTE 1. PROPERTIES OF BUHL CELLULOSE1, HYDRDXYPROPYL CELUJLOSE2,
POLYVINYL ALCOHOL3 AND CARBOXXMETHXL CELLULOSE4
PROPERTY
MATERIAL
Hydroxypropyl
Cellulose
Ethyl- Polyvinyl
cellulose Alcohol
Carboxymethyl-
Oellulose
Tensile
Strength?
(psi) 800-1300
Elongation at
Break6 (%) 66-106
Resolubility
of film? good
Adhesion to Mylar**
polyester (pounds) 19
Adhesion? to
cellophane
(pounds)
Flexibility
high9
excellent
3500-4900 3100
13-18 200-210
excellent good
8
16
1000-1500
6-7
excellent
9 high9
excellent excellent excellent
Hercules, Inc. Ethooel N-10
2
Hercules, Inc. KLucel J
DuPcrrt Elvanol T-25
4
Hercules, Inc. Warp Size Grade CMC
Range of averages for various films rounded to nearest 100 psi
6
Range of averages measured for various films rounded to nearest 1.0%
In water for CMC and PVA, perc for ethyl cellulose, water and methylene
g chloride for hydroxypropyl cellulose.
Average of a minimum of 10 specimens
strength of .cellophane which is approximately
strop used in thetest.
10
-------
psi and elongation of about 22%, while the films forned at room tenperature
had tensile strength of about 800 psi and elongation of about 42%. There-
fore, high drying tenperatures apparently do not prevent the HPC from forming
films having good properties.
11
-------
SECTION 5
PROPERTIES OF SOLVENT SIZED YARNS
The performance of yarns in weaving depends on the presence of certain
physical properties of the yarn. Among these are yarn tenacity, elongation
at the break and abrasion resistance. The required level of these properties
for good weaving performance depends on the type of yarn being processed.
Evaluation of these properties was made by comparison of yarn sized with
the experimental materials to yarns sized with the conventional aqueous size
polyvinyl alcohol which is conmonly used to size polyester/cotton blend yarns.
One of the yarns was 100% cotton, 22's cotton count and the other was 50/50
polyester/cotton intimate blend, 22's cotton counts.
EXPERIMENTAL PROCEDURES
Size Applicators
Two separate techniques were used to apply the experimental size materi-
als to the yarns. The applications for the preliminary tests were made to a
yarn passed through a single yarn sizing apparatus. A schematic diagram of
the apparatus is shown in Figure 2. The supply package was a cone of yarn.
After passing through the size solution, the yarn was wiped as it passed
through a slit in a wool felt pad. In tests requiring a hot size solution,
the size container was heated on a hot plate during the size application.
After the size application, the yarn was dried during passage through a well-
ventilated chamber. The sized yarn was taken up on a spool at a rate deter-
mined by the drying capacity of the device. The wet pickup in this single.
yarn applicator was approximately 300%. Therefore, the concentration of size
material required in the size solution was much lower than that used for a
warp subjected to squeezing by rubber covered rolls as is typical in slash-
ing.
The second device used for the size applications was a laboratory scale
slasher which produced a sized warp one inch (1 in, 2.54 cm) wide (Figures 3
& 4). The supply package was a beam 4 3/8 inches (11.1 cm) wide. The yarn
passed under a single immersion roll in an indirectly heated size box and was
squeezed between a bottom brass roll and a top viton roll (75 durometer Shore
A, cold). The squeeze pressure was regulated by spring loading each end of
the top squeeze roll. Hot air was circulated through the drying chamber to
remove the solvent or water from the warp. All warps consisted of seventy-
five (75) ends. Prior to take-up on: the loom beam, the yarn was split by a
single lease rod and passed through an expansion comb with three (3) ends per
dent. Tension on the warp was controlled via a spring loaded compensator roll
which activated limit switches to increase or decrease the take-up speed as
12
-------
H
oo
Supply
Package
Size
Box
Drying (hot air)
Take up
Spool
FIGURE 2. SCHEMATIC DIAGRAM OF SINGLE YARN SIZE APPLICATOR.
-------
INFRARED
HEATLAMP
LOOM
BEAM
HOT AIR
DRYER
FIGURE 3. SCHEMATIC DIAGRAM OF LABORATORY SLASHER.
-------
FIGURE 4. PHOTOGRAPH OF THE LABORATORY SLASHER.
-------
required. The yarn speed at the size box squeeze rolls was constant.
Size Md-on Determination
The size was removed from a previously dried and weighed sample by soxh-
let extraction using an appropriate solvent. The size add-on and content were
calculated by the usual methods.
Tensile Properties
Breaking tenacity and elongation of the yarns was measured on the Instron
Tester using 10 inch (25.4 cm) gauge length and 2 inches/min (5.08 cm/min)
crosshead speed.
Abrasion Resistance
The tendency of the yarns to withstand cyclic abrasive forces was measur-
ed using a Duplan Cohesion Tester. The timber of cycles of the tester requir-
ed to cause the test yarn to break was determined.
Size Location
Sized and unsized yarns were examined using a Scanning Electron Micro-
scope and a light microscope to assess the uniformity of the coating of the
size material on the yarn and to determine the degree of penetration of the
size material into the yarn.
YARN
The breaking tenacity of the yarns was increased by addition of the size
materials. The data in Table 2 shovgthat the break factor of 100% cotton
yarns was greater when the add-on of size material was higher regardless of
which size material was used and whether the system used solvent or not. At
similar add-on levels, the ethyl cellulose applied from perchloroethylene and
the hydroxypropyl cellulose applied from water at room temperature increased
the yarn tenacity by about the same amount as did the polyvinyl alcohol ap-
plied by conventional aqueous techniques.
The increase in tenacity upon sizing the 50/50 polyester/cotton blend
yarns was much smaller than obtained on the 100% cotton yarns. However, the
three size materials caused comparable increases in the tenacity of the 50/50
blend yarns.
YARN ELONGATION
The elongation at the break of all of the sized yarns was less than that
of the unsized yarns (Table 3) . This is the typical result of slashing. How-
ever, the elongation of the 100% cotton yarns sized in the solvent system with
ethyl cellulose was significantly higher than that of similar yarns sized in
water with polyvinyl alcohol using conventional techniques. The retention of
elongation in the sized yarn is an important characteristic with regard to
weaving performance of the yarns. This difference in elongation between sol-
16
-------
TABLE 2. BREAKING STRENGTH OF 100% COTTON AND 50/50 POLYESTER/COTTON BLEND YARNS SIZED WITH
POLYVINYL ALCOHOL (PVA) FROM WATER, ETHYL CELLULOSE (EC) FROM PERCHLOROETHYLENE (PERC)
OR HYDROXPROPYL CELLULOSE (HPC) FROM WATER.
Sample, Size, Application Medium
Control, unsized cotton
100% Cotton, PVA, water
100% Cotton, PVA, water
100% Cotton, EC, perc
100% Cotton, EC, perc
100% Cotton, EC, perc
100% Cotton, HPC, water
100% Cotton, HPC, water
100% Cotton, HPC, water
Control unsized 50/50 blend
50/50 PE/Cotton, PVA, water
50/50 PE/Cotton, EC, perc
50/50 PE/Cotton, HPC, water
Size Add-on
(%)
0
4.2
10.8
5.1
8.2
14.2
6.1
10.0
15.0
0
7.0
11.3
13.8
Mean Break Factor
(oz x counts)
268
320
352
324
366
380
313
352
359
363
384
405
426
Standard
Error
7
7
11
7
7
7
11
11
7
7
7
11
14.
% Increase Cc/npared
to Unsized Yarn
-
19
31
21
37
42
17
31
34
6
12
17
-------
TABLE 3. EDONSATJON AT THE BREAK CP 100% COTTON AM) 50/50 POLYESTER/COTTON BLEND YARNS SIZED WITH
HYDROXYPROPYL CELLULOSE
*• *»•»•* MTU,UE\, Et±imj
(HPC) FROM WATER.
y.ni u MJ-*AJC< v^-*"/ j-iM-i-
1 J. X H *^j-* *f-iri" "• r" '-*
**^^JfcJfc^*^ ^d. *<4*V^/ -%^&V
Sample, Size, Application Medium
Control, unsized cotton
100% cotton, PVA, water
100% cotton, EVA, water
100% cotton, EC, perc
100% cotton, EC, perc
£ 100% cotton, EC, perc
100% cotton, HPC, water
100% cotton, HPC, water
Control, unsized 50/50 blend
50/50 PE/cotton, PVA, water
50/50 PE/cotton, EC, Perc
50/50 PE/cotton, HPC, water
Size Add-on
(%)
0
4.2
10.8
5.1
8.2
14.2
10.0
15.0
0
7.0
11.3
13.8
Mean Elongation
(%)
7.0
5.4
5.5
6.3
6.6
6.4
5.2
5.2
11.2
7.9
8.3
8.1
Standard
Error
0.1
0.2
0.2
0.1
0.2
0.1
0.1
0.1
0.1
0.2
0.2
0.3
% Decrease Cornpared
to Unsized Yarn
-
24
21
10
7
9
26
26
30
26
28
-------
vent and aqueous sized 100% cotton yarns did not occur to the same extent in
the 50/50 polyester/cotton blend yarns. The 50/50 blend yarns decreased in
elongation by about the same amount regardless of whether the solvent or
aqueous sizing system was used.
When hydroxypropyl cellulose was applied from water at room temperature,
the resulting 100% cotton and 50/50 blend yarns had about the same elongation
as the corresponding control yarns sized with PVA.
ABRASION RESISTANCE
The number of abrasive cycles to cause breakage of 100% cotton yarns on
the Duplan Cohesion Tester increases as the size add-on is increased as indi-
cated by the data in Table 4. Yarns sized with PVA in a conventional aqueous
system gave better results in this test than did yarns sized with ethyl cellu-
lose from perc or hydroxypropyl cellulose from water at room temperature.
Since the film properties and adhesive characteristics of ethyl cellulose and
hydroxypropyl cellulose are comparable to those of polyvinyl alcohol, these
abrasion results indicate that additional developments in the size formulation
and/or application techniques are needed. For example, lubricants ccrmonly
used in aqueous slashing systems are not suitable for solvent formulations or
cold aqueous sizing so the experimental formulations contained no lubricants.
Studies of the effects of lubricants on properties of films of HPC were con-
ducted late in the project but were inconclusive.
SIZE LOCATION
The scanning electron photomicrographs in Figures 5,6, & 7 are represen-
tative of the appearance of polyvinyl alcohol, ethyl cellulose and hydroxy-
propyl cellulose on the yarns. In Figure 5 are 100% cotton unsized yarns
(first three on the left) and yarns containing about 15% by weight of ethyl
cellulose (last four on the right) . The size coating is continuous and uni-
form. The size on the 50/50 blend yarns appeared much the same as on these
100% cotton yarns. In Figure 6 are three 100% cotton yarns containing about
10% by weight of polyvinyl alcohol. The fibers protruding from the surface of
the yarn are not encapsulated by the size material as they are with the ethyl
cellulose. In Figure 7 are 100% cotton yarns containing about 12% by weight
of hydroxypropyl cellulose. As was the case with the ethyl cellulose, the
hydroxypropyl cellulose uniformly coats the yarn surface and almost complete-
ly encapsulates the protruding fibers binding them to the yarn bundle. The
difference in the surface appearance of yarns sized with PVA compared to EC
or HPC may be the result of the much lower viscosity of the PVA size solution.
The surface characteristics of the 50/50 blend, yarnswere very similar to that
of the 100% cotton yarns in all cases when the same size was applied.
Penetration cf the size materials into the yarn was assessed by examina-
tion of cress sections of the yarns using a light microscope. Dyes were add-
ed to the size fontoilae to aid the identification of the size material in the
yarn cross section. There was no apparent difference in the depth of pene-
tration of the three size materials into the yarn bundle. The PVA applied
from hot water, the EC applied from perchlorothylene at room temperature and
the HPC applied from water at room temperature all penetrated about 1/3 to 1/2
the distance from the surface to the center of the yarns.
19
-------
FIGURE 5. SCANNING ELECTRON MICROGRAPH OF 100% COTTON YARNS, UNSIZED (FIRST 3 ON LEFT) AND CONTAINING
ABOUT 15% BY WEIGHT OF ETHYL CELLULOSE (LAST FOUR ON RIGHT). MAGNIFICATION 20X.
-------
FIGURE 6. SCANNING ELECTRON MICROGRAPH OF 100% COTTON YARNS CONTAINING ABOUT 10% BY WEIGHT
OF POLYVINYL ALCOHOL. MAGNIFICATION - 100X.
-------
to
NJ
FIGURE 7. SCANNING ELECTRON MICROGRAPH OF 100% COTTON YARNS CONTAINING ABOUT 12% BY WEIGHT
OF HYDROXYPROPYL CELLULOSE. MAGNIFICATION 100X.
-------
CO
TABLE 4. ABRASION RESISTANCE OF 100% COTTON AND 50/50 POLYESTER/COTTON BLEND YARNS SIZED WITH
POLYVINYL ALCOHOL (PVA) FROM WATER, ETHYL CELLULOSE (EC) FROM PERCHLDROETHYLENE (PERC)
OR HYDROXYPROPYL CELLULOSE (HPC) FROM WATER.
Sample, Size, Application Medium
Control, unsized cotton
100% cotton, PVA, water
100% cotton, PVA, water
100% cotton, EC, perc
100% cotton, EC, perc
100% cotton, EC, perc
100% cotton, HPC, water
100% cotton, HPC, water
100% cotton, HPC, water
Control, unsized 50/50 blend
50/50 PE/cotton, PVA, water
50/50 PE/cotton, EC, perc
50/50 PE/cotton, HPC, water
Size Add-on
0
4.2
10.8
5.1
8.2
12.8
6.1
10.0
15.0
0
7.0
11.3
13.8
Mean Abrasion Resistance
(cycles to break)
67
274
10,000+
240
417
1,087
212
649
3,261
67
10,000+
4,315
5,500
-------
SECTION 6
WEAVING OF SOLVENT SIZED YARNS
All yarn samples were woven on a Draper E model loom at 175 pick in-
sertions per minute. Initially the test yarns were entered into the loom as
a strip approximately one inch wide on the left selvage of an 18-inch wide
fabric. Later, more test yarns were entered until finally the entire warp was
made up of yarns sized in this study. The yarns were entered into four har-
neses weaving a birdseye diamond weave as shown by the draft in Figure 8.
Yarns were drawn 4 ends per dent into a 17 dent reed; and, a 50-tooth pick
gear was used. This gave an on-the-loom construction of 68 ends per inch and
50 picks per inch. Off the loom, the average construction was 72 ends per
inch and 52 picks per inch which gave a fabric weight of about 5 ounces per
square yard.
results of the weaving trials are shown in Table 5. All satrple
warps performed within reasonable breakage rates. In general, the warps
sized with PWA performed scroewhat better in weaving than did the warps sized
with ethyl cellulose or hydroxypropyl cellulose. This behavior is understand-
able based on the abrasion resistance figures previously discussed. Attempts
to lubricate the warps with hydrophilic carbowax lubricants resulted in poor-
er weaving performance in HPC sized warps. Since the strength, elongation
and adhesion to polyester and cellulose of ethyl cellulose and hydroxypropyl
cellulose are adequate, their performance in weaving can probably be iitproved
by optimizing the size formulation, add-on level and application techniques.
24
-------
Order of Entering
Order of Lifting
Order of Interlacing
FIGURE 8. WEAVE, DRAW AND CAM DRAFTS USED FOR WFAVABILITY TRIALS.
-------
TART.E 5. END BREAKAGE RATES FOR V&RPS SIZED WITH VARIOUS SIZING MATERIALS.
Sizing
Material
EVA
EC N-10
HPC-J1
HPC-E2(with
wax)
HPC-E (w/o
wax)
EVA
EC N-10
HPC-J
HEC-E (wax)
HEC-E (no-
wax)
Fiber
Content
100% cotton
100% cotton
100% cotton
100% cotton
100% cotton
50/50 PE/cotton
50/50 PE/cotton
50/50 PE/cotton
50/50 PE/ootton
50/50 PE/ootton
Percent
Add-on
7.4
12.8
14.5
17.4
17.0
7.0
11.13
11.4
13.8
12.5
Total Weaving
Minutes
200
200
200
400
400
200
200
200
200
200
Average Breaks
Per Loom Hour
0.3
0.6
2.1
4.0
1.4
0.0
2.7
1.5
3.0
1.5
^•Hercules, Inc. - KLucel, J.
^Hercules, Inc. - KLucel, E.
26
-------
SECTION 7
FABRICS CONTAINING SOLVENT SIZED YARNS
PHYSICAL PROPERTIES
Woven fabric samples were subjected to various strength and abrasion
tests. Ten determinations were performed in the warp and the filling direc-
tion for each sample and each test. The averages for strength and elongation
as determined on the Instron for a one-inch ravelled strip are shown in Table
6. It can be seen that there is no significant difference between fabric sam-
ples sized with the different sizing materials of this study. The Instron was
equipped with a "D" cell and set for 3-inch gauge, 100 pound full scale load,
12 inches per minute crosshead rate and 50 inches per minute chart speed.
Tear strengths were determined for warp and filling directions on the
Elmendorf Tear Tester. These data are given in Table 7 except for the PVA
sized samples which would not tear at the maxinnum load of this test. The re-
sults obtained for the samples which did tear are not significantly different
from one sample to the other.
The Stall Flex Abrader with a three-pound tension weight and a one-and-
one-half pound head weight was used to determine fabric abrasion resistance.
These results are given in Table 8 where it is shown that the PVA sized warps
produced fabrics with much greater abrasion resistance as measured by this
particular test. The other samples were essentially equal in terms of resis-
tance to abrasion.
DESIZING, ra-.FACHiNG, DYEING
Samples of the 50/50 polyester/cotton blend fabric were desized, bleach-
ed and dyed to ascertain the effect of solvent slashing and desizing on these
subsequent processes. A sample size with PVA was desized using boiling water.
A sample sized with ethyl cellulose was desized by washing for 30 seconds in
each of two portions of clean perchloroethylene. These two fabrics were then
bleached simultaneously with hydrogen peroxide and later dyed in a common bath,
first with C.I. Disperse Blue 3 for the polyester and then with C.I. Direct
Blue 1 for the cotton. The reflectance curves of the bleached and dyed sam-
ples were measured.
The water absorbency of the aqueous desized sample (PVA) was greater than
that of the solvent desized sample (EC). The aqueous desized sample (PVA) was
slightly whiter after bleaching than was the solvent desized sample (EC). The
dyeability of the two samples was essentially the same. The difference in re-
flectance of the samples after dyeing was about the same as the difference in
reflectance of:the samples after bleaching. The solvent desized fabric proces-
27
-------
TABLE 6.
ONE-INCH RAVELLED STRIP STRENGTH AND ELONGATION FOR FABRICS SIZED
WITH VARIOUS SIZING MATERIALS.
Sizing
Material
EVA
EC N-10
HPC-J1
HPC-E2
EVA
EC N-10
HPC-J
HPC-E
Fiber Filling Direction Warp Direction
Content Elongation (%) Strength (Ibs) Elongation (%) Strength
(Ibs)
cotton
cotton
cotton
cotton
PE/cotton
PE/cotton
PE/cotton
PE/cotton
12.8
13.1
11.4
11.9
14.0
13.6
12.4
12.1
53.9
53.3
46.4
49.7
59.0
51.6
53.0
49.9
12.1
10.0
11.8
11.3
15.8
16.1
17.0
15.7
62.7
54.5
59.1
60.9
85.0
87.0
84.6
87.7
^Hercules, Inc. KLucel J
2Hercules/ Inc. KLucel E
28
-------
TABLE 7. TEAR STRENGTH FOR FABRICS SIZED WITH VARIOUS SIZING MATERIALS AS
DETERMINED ON THE ELMENDORF TEAR TESTER
Sizing
Material
EC N-10
HPC-J1
HPC-E2
EC N-10
HPC-J
HPC-E
Fiber
Content
cotton
cotton
cotton
Poly/cotton
Poly/cotton
Poly-cotton
Filling
Strength (g)
3500
2540
3329
3596
2897
3164
Warp
Strength (g)
3400
3690
4021
5863
6193
6307
•'•Hercules, Inc. KLucel J
^Hercules, Inc. Klucel E
29
-------
TABLE 8. ABRASION RESISTANCE OF FABRIC SAMPLES SIZED WITH VARIOUS SIZING
MATERIALS.
Sizing
Material
PVA
EC N-10
HPC-J1
HPC-E2
FVA
EC N-10
HPC-J
HPC-E
Fiber
Content
cotton
cotton
cotton
cotton
PE/ootton
PE/cotton
PE/ootton
PE/cotton
Filling
Abrasion Cycles
1620
1114
955
933
2394
589
1325
914
Warp
Abrasion Cycles
2567
792
1132
1076
7238
1147
1298
1297
^flercules, Inc. KLucel J
2Hercules/ Inc. KLucel E
30
-------
sed satisfactorily and no difficulties in bleaching and dyeing were encounter-
ed.
CHEMICAL AND PHYSICAL EFFECTS
The possibility of an effect of perchloroethylene on the properties of
polyester fiber was investigated in order to insure that no significant
changes would occur in the fiber during solvent slashing.
Experiments were performed to observe the effect of solvent on the sur-
face characteristics of the fibers. Polyester fabric was heated in perchloro-
ethylene at 121°C for 15 minutes. The fabric was allowed to air dry for 15
minutes. These specimens were then coated with a gold alloy using vacuum
deposition techniques. The coated specimens were then observed by scanning
electron microscopy. Photographs of the fiber surfaces were taken at 500X
and 1000X magnification. These surfaces were then compared with the surfaces
of similar polyester fibers not subjected to the solvent bath. These experi-
ments indicated no significant change in the surface of the polyester fibers.
The thermal properties of the polyester fibers before and after treat-
ment in the solvent bath at 121°C were compared utilizing thermal gravimetric
analysis and differential scanning calorimetry. These experiments indicate
no significant change in the thermal properties of the polyester fabric with
the exception of the effects caused by solvent expiration from the fiber as
the fibers are heated. There appeared to be no change in the glass transition
temperature or melting point of the fiber.
31
-------
SECTION 8
SOLVENT REM3VAL DURING DRYING
The use of organic solvents in textile dyeing and finishing has been ex-
plored by industry and independent researchers extensively for the past sever-
al years. This research was prompted by the need for an alternative solvent
to replace the traditional solvent, water. This interest in solvent process-
ing dates back earlier than 1937 when a Celanese patent (1) referred to the
use of organic solvents for continuous dyeing. In other early research, Gar-
ret (2,3) described the use of trichloroethylene vapor to fix disperse dyes on
polyester and cellulose acetates. More recently, solvent processing has been
demonstrated to be economical in the removal of oils from knitted fabrics.
As an outgrowth of studies (4) on dyeing rates from perchloroethylene
solvent with polyester fibers, a new study was initiated in an attempt to de-
fine the various economic, processing conditions and materials and also the
environmental significance of a solvent slashing and desizing operation for
cotton/polyester fabrics. One of the obvious questions to be answered was the
effect and extent of solvent retention by the polyester fibers. The answers
here are important from two basic standpoints; the first is the economics of
solvent recovery and the second, is an environmental question of the release
of solvent from the fiber after processing has been completed.
Previous reports have indicated that retention of perchloroethylene by
polyester fiber may be of concern. Byland, et. al., (5) gave a brief indica-
tion of the drying conditions of polyester under conditions of superheated
perchloroethylene. His reported data showed some information on vapor concen-
tration at various processing conditions over short drying time (seconds).
More recently, Brodmann (6) gave retention data for chlorinated solvents in
fabrics under conditions of dry-cleaning processing. These data again indi-.
cate some retention of solvent by polyester.
A more in depth study was performed to provide a better description of
the total retentions and rates of loss of chlorinated solvents from polyester
fabric. This information was necessary for a thorough economical and environ-
mental evaluation of solvent slashing and desizing processes for fabrics con-
taining polyester fibers.
EXPERIMENTAL
The fabrics used in this study were obtained from Test Fabrics, Inc. The
fabrics were 100% polyester, one was heat set, one was without heat set. Sol-
vents used were of reagent grade. Thermal analysis experiments were performed
using a Dupont Thermogravimetric Analyzer.
32
-------
The fabrics used were exposed to solvent in the following manner. In or-
der to determine the retention of solvent as a function of temperature the
following procedure was followed. Fabric pieces which had been previously
taken to constant weight were immersed in a solvent bath which was maintained
at the desired temperature. The solvent and fabric were stirred at regular
intervals. After immersion in the solvent bath for 15 minutes, the fabric
was removed and allowed to dry at room temperature for 10 minutes. This al-
lowed surface solvent to evaporate. The fabric was then weighed to determine
the percent retention of solvent within the fiber. After weighing, the fabric
was allowed to expire solvent under ambient room conditions and was reweighed
at various time intervals. This experiment therefore gave data of percentage
retention versus time. Different bath temperatures were employed and the pro-
cedure above repeated in order to determine the retention of solvent under
these conditions.
A second experiment was devised in order to determine the rate of removal
of solvent from the fiber at various drying temperatures and under flow condi-
tions. Small pieces of fabric were heated in the solvent for 15 minutes at
the boiling point of the solvent. This gave a maximum value for initial re-
tention. The fabrics were then allowed to dry as before. The dry samples
were then placed in the Thermal Gravimetric Analyzer. The sample was then
heated under nitrogen gas flow and at isothermal conditions. The percent
weight (solvent) loss of the sample versus time was obtained. The experiment
was performed in triplicate at several temperatures.
The two solvents tested were perchlorothylene and dichloromethane.
RETENTION CF PERCHLQiRaEfflYLENE
In any solvent process the economics will be partially dependent on the
ability to recover the solvent efficiently. One possible pathway for solvent
loss in finishing of polyester or other synthetic fibers is by retention in
the fibers.
The retention of perchloroethylene by two specific polyester fabrics as
a function of temperature is shown in Figure 9 and tabulated in Table 9. These
data indicate the temperature dependent nature of perchloroethylene sorption -
by polyester. The curves in Figure 9 show that between bath temperature of
60°C and lOO^C, there is direct relationship of retention with temperature.
After 100°C these data indicate a saturation level. Obviously, if the proces-
sing temperature is maintained below 60°C, there will be little or no reten-
tion of solvent. At room temperature (22°C) there is no significant retention
of perchloroethylene in the fabric. Therefore, solvent processing at this
temperature would cause no solvent loss by retention.
REMOVAL OF PERCmOROETHYLENE
Further experiments were conducted to determine the removal behavior of
the solvent from polyester fabric. Data showing the retention of perchloro-
ethylene from the fabric at room temperature as a function of drying time are
presented in Figure 10 These data show a gradual reduction of solvent in the
fabric. The initial concentrations were those achieved by treating the fabric
33
-------
(D
to
0> -H
f-r
-------
8 J
!'J
4 .
2 .
»
Not Heat Set
Heat Set
A § B
n
D
20 40
60 80 100
200
Room Air Drying Time (Minutes)
FIGURE 10. EFFECT OF PERCIILOROETHYLENE BATH TEMPERATURES ON THE RETENTION OF
PERC IN POLYESTER FABRICS WITHOUT AND V7ITH HEAT-SET. BATH TEMPERA-
TURES: A-121°C, B-100°C, C-80°C, D-60°C. FABRIC IMMERSION TIME:
15 MINUTES.
35
-------
TABLE 9. RETENTION OF PERCHLORQETHYLENE BY POLYESTER FABRIC AFTER IMMERSION
FOR 15 MINUTES AT VARIOUS BATH TEMPERATURES AND AMBIENT AIR DRYING.
Temperature Weight Percent Perchloroethylene
°C Heat Set W/O Heat Set
22 < 0.01 < 0.01
60 0.6 0.8
80 3.9 5.4
100 7.0 8.8
120 7.2 8.8
36
-------
at different bath temperatures. The rates of loss of solvent vs. time at
constant temperature are the same and therefore independent of initial reten-
tion level in the fabric. Also, these data indicate the slow loss of the re-
tained solvent under ambient drying conditions.
PERCHLORDETHYLENE REM3VAL vs. DRYING TEMPERATURE
As shown by the ambient condition data, elevated temperatures will be
necessary to remove the solvent from fabric after it has been retained. Poly-
ester fabric was treated at the maximum perchloroethylene bath temperature
(121°C) in order to achieve a high level of retention. This fabric was then
heated isothermally using a thermogravimetric analyzer as previously described.
The isothermal conditions were set at different levels to obtain the rates of
removal and removal behavior at these temperatures. Table 10shows the rates
of removal, in percent per minute, of the perchloroethylene from polyester
fabrics. The removal behavior of the perchloroethylene indicated two differ-
ent curves. An initial, very rapid, removal followed by a much slower removal.
This is reflected in the initial and final rate data shown in Table 10. As
expected the initial rates of removal of solvent are highly temperature depen-
dent. At 60°C the removal is slow so that one cannot distinguish between the
initial and final rate.
RETENTION OF PERCHLOROETHYLENE AFTER DRYING
The information shown in Table 11 is of more significance to this project
than the previously discussed rates of removal. This table gives the reten-
tion of solvent after 2.5 minutes and 5.0 minutes of drying at the indicated
temperatures. These data are also plotted in Figures 11 and 12 for easier
interpretation. It is shown that at the lower temperatures most of the re-
tained solvent is still in the fabric after 5 minutes of drying and that a
significant amount of the retained solvent is present after 2.5 minutes of
drying at the higher temperature, 120°C. Therefore, under normal industrial
processing conditions retained perchloroethylene would not be efficiently re-
moved.
Thus, the temperature of perchloroethylene solvent in the finishing of
polyester fiber or fabric must be maintained low enough to prevent the solvent
from entering the fiber and being retained. Low treatment temperatures were
therefore used in the sizing experiments which were successfully conducted in
this project so that the drying of the yarn or fabric could be accomplished.
At elevated drying temperatures the solvent would be evaporated from the sur-
face before the fabric temperature is raised high enough to allow significant
sorption.
With the data described herein one should be able to calculate any of the
retention information needed for any type of solvent finishing of polyester
fiber or fabric using perchloroethylene solvent.
DIGHLORCMETHANE SOLVENT
The rates of removal of dichloromethane from the two polyester fabrics
previously described was determined at drying temperatures ranging from 40°C
37
-------
TABLE 10. RATES OF REMDVAL OF PERCHLOROETHYLENE FROM POLYESTER FABRICS AT
VARIOUS DRYING TEMPERATURES.
Temperature
^C Rate of Removal (%/Min)
Heat
Initial
60 —
80 1.0
100 2.4
120 4.5
Set
Final
0.03
0.03
0.02
0.01
W/O Heat
Initial
—
1.1
2.5
4.1
Set
Final
0.03
0.03
0.03
0.02
TABLE 11 RETENTION OF PERCm£«ROETHYLENE IN POLYESTER FABRIC AFTER DRYINS THE
PERC SATURATED FABRIC FOR 2.5 AM) 5.0 MINUTES AT VARIOUS TEMPERA-
TURES.
Temperature
°C
60
80
100
120
2.5
Minutes
Beat Set W/O Heat Set
7.7
6.0
4.2
1.8
8.3
6.8
5.3
2.4
Heat Set
7.2
5.2
3.0
0.9
5 Minutes
W/O Heat Set
7.8
6.0
4.0
1.6
38
-------
CD
8
•P O
CD -H
O fi
M ,0
O Cfl
i— I U-i
U
CD
C
CD
O
?-i
CD
CD
•(->
tO
O
X
iH
O
•a
2.0 -
80 100
Temperature (PC)
120
FIGURE 11. WEIGHT PERCENTAGE OF PERCHLOROETHYLENE RETAINED BY POLYESTER
FABRIC AFTER DRYING FOR 2.5 MINUTES AT VARIOUS TEMPERATURES WITH HEAT
SET O WITHOUT HEAT SET A
39
-------
80
100
120
Temperature ( C)
FIGURE 12. WEIGHT PERCENTAGE OF PERCHLOROETHYLENE RETAINED BY POLYESTER
FABRIC AFTER DRYING FOR 5.0 MINUTES AT VARIOUS TEMPERATURES WITH HEAT
SET O WITHOUT HEAT SET A
40
-------
to 120°C. These rate data are shown in Table 12. These data again indicate
a two slope behavior with the initial slope very temperature dependent.
The retention of dichloroniethane after drying intervals of 2.5 and 5.0
minutes are shown in Table 13. These data show that there is significant re-
tention of the solvent even at temperatures well above the solvent boiling
point. The use of the low boiling solvent therefore shows no particular ad-
vantage over perchloroethylene as far as its retention behavior is concerned.
SUMMARY
The sorption and retention behavior of solvents by polyester has been
shown to be dependent on the solvent bath temperatures and on the drying tem-
peratures. At high bath temperatures there is a large quantity of solvent ab-
sorbed, greater than 9 percent. At low bath temperatures, for example room
temperature, there is little or no percholoroethylene absorbed. The rates of
removal of the solvent from the fiber were higher at higher temperatures and
lower at low temperatures. The obvious conclusion is that in order to avoid
solvent retention the solvent must be prevented from entering the fiber. This
can be accomplished by using low bath temperatures (room temperature) and by
removing the surface solvent rapidly, preventing penetration of the solvent
into the fiber during drying.
Prevention of retention of solvent in the fiber removes the danger of air
pollution by expiration of the solvent after the fabric has left the process-
ing facility.
The loss of solvent would have a significant effect on the economics of
the process. As shown in the economic evaluations of the process, material
costs are important. However, from the information on solvent retention pre-
sented herein, the loss of solvent through retention can be avoided to such a
degree as to make the loss insignificant.
41
-------
TABLE 12. RATES OF RENEWAL OF DICHLCKCWETHANE FROM POLYESTER FABRIC.
(FABRIC SATURATED AT 41CC)
Drying Tenperature
°C
40
60
80
100
120
Rate of Removal - %/Minute
Heat Set
Initial
0.2
1.2
1.4
2.1
5.6
Final
0.026
0.021
0.008
0.001
~ 0
W/O Heat Set
Initial
0.2
0.9
1.2
2.5
4.5
Final
0.033
0.025
0.014
0.004
~ 0
TABLE 13. RETENTION CF DICHLORQMETHANE IN POLYESTER FABRIC AFTER DRYING THE
SATURATED FABRIC FOR 2.5 AND 5.0 MINUTES AT VARIOUS TEMPERATURES.
Temperature
60
80
100
120
Retention - Weight %
2.5 Minutes
Heat Set W/O Heat Set
2.9 3.8
1.8 2.6
0.8 1.3
0.2 0.5
5.0 Minutes
Heat Set W/O Heat Set
2.2 3.0
1.1 1.7
0.3 0,7
0.08 0.12
42
-------
REFERENCES
1. British Patent 470, 333, 1937.
2. Garret, D.A., Journal of the Society of Dyers and Colorists,
Vol. 73, 1957, p. 365.
3. Garret, D.A., Textil-Praxis, Vol. 13, 1958, p. 287.
4. Hall, D. M. and Perkins, W.S., Auburn University, Water Resources
Research Institute Bulletin 20, 1974.
5. Byland, H.R., M. Capponi, Gerber, H., and Sam, F., Journal
of the American Association of Textile Chemists and Colorists
Vol. 3, No. lo, 1971, p. 33.
6. Brodmann, George L., Journal of the American Association of
Textile Chemists and Colorists, Vol. 7, ab. 5, 1975, p. 20.
43
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SECTION 9
EFFECTS OF SOLVENT SIZING AND DESIZING ON THE
One of our Nation's goals in its efforts to eliminate or change those
practices which are detrimental to our environment is water pollution abate-
ment. The effluent from textile aqueous wet processes contains pollutants
which nust be removed or changed to prevent stream pollution. The removal
of sizing materials on woven fabrics in the finishing plant is a major con-
tributor to the BCD characteristic of the plant's waste water effluent.
Reduction in water consumption and recovery of the sizing materials
which can be realized by the use of solvent sizing and desizing systems
would substantially reduce waste water pollution. This reduction in pollu-
tion can also be achieved by use of a recently developed polyvinyl alcohol
size reclamation system. Several plants have installed this system which
provides for the recovery and recycling of approximately 75% of the poly-
vinyl alcohol size and recycling of the water used in desizing to the desize
washer. Obviously, recycling of the water in the desizing process reduces
water and energy consumption. However, energy used in the reclamation units
must be considered in the total energy consumption. Information on this
system was obtained from publications by Union Carbide Corporation (1) and
Gaston County Dyeing Machine Company (2).
One of the concerns in considering the replacement of aqueous textile
wet processing with solvent systems is that the loss of solvent might result
in serious air pollution. Therefore, all aspects of the effects on the
environment must be considered when a new process is being evaluated.
MILL SURVEY
In order to determine the present consumption of water and energy,
process exhaust and cost of sizing (slashing) and desizing processes, infor-
mation was requested from a number of textile plants. The information re-
ceived from typical plants is shown in Tables 14 and 15. The averages for
the appropriate categories were used as the data for the conventional aqueous
systems in Tables 17, 18, and 19.
VftTER CONSUMPTION AND WASTE WATER TREATMENT
Water is used in conventional aqueous sizing systems for making the
size mix, washing the size applicator and washing the size mix and slasher
areas. These operations do not require a great amount of water. These wash
waters plus infrequent dumping of sizing materials are the only contribution
from the slashing or sizing operation to the plant's water pollution and
waste water treatment is not a major problem for weaving mills. Since the
44
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TABLE 14. ENERGY CONSUMPTION, EXHAUST AIR QUANTITY AND POST FOR
Ul
ITEMS:
Type sizing material
% solid add-on to warp
No. size boxes
No. drying cylinders
ENERGY CONSUMPTION:
Thermal-BTU's/lb. warp
(size and drying)*
Electrical-BTU's/lb. warp
(slasher operation)
Electrical-BTU's/lb. warp
(exhaust system)
Exhaust air (cu. ft./lb. warp)
Cost of material, labor and
overhead (cents/lb. warp)
SIZING WARP YARNS WITH AQUEOUS SYSTEMS IN TYPICAL PLANTS
'% cotton)
>
>
'lb. warp
warp)
A
50/50
Starch
11.0
1
12
1,837.5
24.4
12.2
1,874.1
636
B
50/50
Starch/PVA
12.5
2
13
2,503.1
81.8
102.2
2,687.1
3,255
TYPICAL PLANTS
C
50/50
Starch/PVA/CMC
12.5
2
11
1,816.5
81.1
32.7
1,930.3
678
AVERAGE
D
50/50
Starch
12.0
2
12
2,432.0
37.4
15.0
2,484.4
1,172
E
50/50
Starch/CMC
14.0
2
14
1,837.5 2
34.4
17.2
1,889.1 2
1,189 1
12.4
,085.3
51.8
35.9
,173.0
,386.0
2.41
7.41
8.74
4.08
6.58
5.84
*Calculated from Jbs. of steam used and adjusted for fuel consumption based on losses in boiler
efficiency and steam distribution lines losses.
-------
TABLE 15. ENERGY CONSUMPTION, EXHAUST AIR QUANTITY AND COST FOR
(Tv
EESIZING WITH AQUEOUS SYSTEMS
ITEMS;
Fiber blend (% polyester/% cotton)
Type sizing material
Water consumption (gals./lb. of goods)
Wash water temperature (°F)
ENERGY OCNSUMPTION:
Thermal-BTU's/lb. of goods*
Electrical-BTU's/lb. of goods
(process machinery)
Electrical-BTU's/lb. of goods
(exhaust system)
TOTAL energy consumption/lb.
of goods
Exhaust air (cu. ft./lb. of goods)
IN TYPICAL PLANTS
TYPICAL PLANTS
A
50/50
Starch
1.0
180
1,837.5
7.6
0
1,845.1
0
Cost of material, labor and
overhead (cents/lb. of goods) Not
Available
B
50/50
Starch/PVA
0.6
140
649.8
21.2
4.2
675.2
100
0.78
C
50/50
PVA
0.5
180
680.6
3.5
3.5
687.6
167
0.80
D
50/50
Starch
1.2
190
1,640.8
65.8
24.4
1,731.0
804
Not
Available
E
50/50
Starch
1.6
170
1,998.7
100.5
20.1
2,119.3
270
6.85
AVERAGE
0.98
172
1,361.5
39.7
10.4
1,411.6
268.2
2.81
*Calculated from Ibs. of steam used and adjusted for fuel consumption based on losses in boiler
efficiency and steam distribution line losses. Does not include drying after desizing.
-------
sizing material in the PVA reclamation system is applied in the normal manner,
the water consumption and waste water effects should be the same in sizing as
the conventional systems.
The principal investigators made several visits to manufacturers of
solvent equipment and received information from them and others. As shown in
Table 17, 3.4 gallons of water are consumed per pound of warp yam. The
majority of this is used by the condenser and is suitable for use as warm
process water. It is reported that the waste water from the water solvent
separator for the condensate from washing activated charcoal filters contains
0.015% by weight perchloroethylene and that this could be eliminated (3) .
Information from typical plants showed an average of 0.98 gallons of
water consumed per pound of fabric for the desizing process using conventional
aqueous systems. In the PVA reclamation system (1-2) the permeate from the
filtration system is reusable hot water which is returned to the desize
washer. The actual water consumption is 0.54 gallons per pound of fabric and
possibly less. In a solvent desizing machine the use of water is similar to
that in the sizing machinery and the consumption is approximately the same.
As shown in Table 17, 3.4 gallons of water are consumed per pound of fabric
and most of this is used in the condenser. Since it is not polluted it is
suitable for use as warm process water.
Table 16 shows the pollutional load contributed by desizing various
sizing materials in aqueous systems. Warp yarns which have been sized with
starch are responsible for a large part of the pollutants in the waste water
effluent from a woven fabric finishing plant. The majority of the 6005 is
due to the modified and converted sizing material which is removed from the
fabric. In the PVA reclamation system 75% or more of the sizing material is
reclaimed (1-2) (4). This will greatly reduce the waste water pollution from
this desizing process. The effect of the solvent desizing system on the
pollutants in the waste water effluent would be similar to that from the
solvent sizing system.
EFFECTS CN AIR QUALITY
The majority of air exhausted from the slasher using conventional
aqueous sizing systems is that taken from the hood over the drying cylinders.
An additional general exhaust of the area is also normal for this operation.
As shown in Table 17, 1,386 cubic feet of air are exhausted per pound of warp
yam. This air contains water vapor and small quantities of sizing materials
and lint. The air exhausted from the slashers using the PVA reclamation
system should be very similar to that from conventional systems.
In a solvent sizing or desizing system the majority of the solvent must
be recovered in order for the process to be economically feasible and to
prevent air pollution by solvent vapors which are exhausted from the system.
Procedures which are being used to recover solvent from the one commercial
sizing range and commercial desizing and scouring ranges are as follows:
A. Distillation—The solvent used to clean rolls in a sizing or
desizing range and the soiled solvent is pumped to a storage
47
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TABLE 16. PCLLUTIQNAL LOAD CONTRIBUTED BY EESIZING VARIOUS SIZING MATERIAL^
Type Fabric
100% Cotton
100% Cotton
100% Cotton
100% Cotton
Type Desizinq
Pollution Loads
gH Effluent
00
(lbs/1,000 Ibs of Fabric)
Enzyme Starch
Acid Starch
CarboxiTOSthyl Cellulose
Polyvinyl Alcohol
Inzyme Starch
:arboxymethyl Cellulose
'olyvinyl Alcohol
BODc
45.60
45.60
3.93
2.50
38.50
3.93
2.50
TSS*
89.0
89.5
5.0
5.0
77.0
5.0
5.0
TDS**
5.1
7.5
45.0
48.0
19.8
54.4
50.4
Oil & Toxic
Grease Materials
4.8
4.8
9.4
2.4
3.6
9.4
2.4
6-8
1-2
6-8
6-8
6-8
6-8
6-8
Water (gal/lb
of Fabric
1.5
1.5
1.5
1.5
1.5
1.5
1.5
*Total suspended solids.
**Total dissolved solids.
SOURCES: 1. In-Plant Control of Pollution. Upgrading Textile Operations to Reduce Pollution,
EPA-625/3-74-004.
2. Private files of investigator.
-------
TABLE 17. ENVIRCMMENTAL EFFECTS OF AQUEOUS AND SOLVENT
SIZING (SLASHING) SYSTEMS
CATEGORY
AQUEOUS SYSTEMS
PVA
Conventional Eeclaraation
SCLVENT SYSTEM
Gallons of water
consumed per pound of
warp yarn
Effect on plant's
total waste water
Cubic feet of air
exhausted per
pound of warp yarn
Pounds of perchloro-
ethylene loss per
pound of warp yarn
Concentration in ppm
of perchloroethylene
in atmosphere at:
production machine
distillation unit
exhaust stack
0.25
minor
1,386.0
0.25
minor
1,386.0
3.4*
minor
44.2**
0.033
40.0
30.0
100.0**
*Majority is recovered and available for process water.
**From carbon filters. Does not include other units.
49
-------
tank for soiled solvent. This solvent is introduced into
a still where it is heated by means of steam. The vapors
are fed into a water-cooled condenser and the liquid is
then passed through a water-separator. The water from the
separator is passed to waste and the solvent goes to a
clean solvent tank from which it is introduced again into
the system. The residue in the still will contain the
sizing material plus waxes, fats and oils which have been
removed from the fibers. Machinery manufacturers have
reported 90% size recovery which would require only 10%
new material to be added to the system.
B. Condensation—Practically all of the solvent should be
evaporated from the yarn or fabric in the drying chamber
and a test probe and controlled unit for monitoring the
proportion of solvent in the drying chanber is available.
The saturated air from the drying chamber passes through a
water-cooled condenser and a portion of this air is
recirculated in the dryer and the other goes to an activated
carbon adsorption unit. The solvent which is condensed in
this unit goes to the clean solvent storage tank.
C. Adsorption by activated carbon—The dried warp or fabric
passes through a vacuum or deodorizing section as it
leaves the dryer. Some manufacturers also use a similar
vacuum at the entrance slot to help maintain a slight
negative pressure in the unit and to capture any solvent
which might escape from, this opening. The air from the
vacuum section is passed through an activated carbon filter
system. The carbon adsorbs the solvent from the air and
the clean air is then exhausted to the atmosphere. When
the carbon bed nears its efficiency limit, the air is
diverted to a second carbon unit for adsorption. The first
carbon bed then goes into the desorption portion of the
cycle which consists of passing steam through the carbon bed
in the direction opposite to that in which the solvent laden
air had been flowing. The steam distillate goes through a
water-cooled condenser and the oondensate passes through a
water separator. The water from the separator goes to
waste and the solvent is puiped to the clean solvent storage
tank. The adsorption and desorption cycles of the carbon
filter beds can be automatically controlled.
As shown in Table 17, 44.2 cubic feet of air per pound of warp yam are
exhausted from the carbon filters. Some have reported a concentration of
100-150 parts per million of solvent in this air, and the concentration may
be higher toward the end of the cycle time of the carbon adsorption unit.
This concentration could be reduced with a more efficient carbon bed and more
frequent transfer to the alternate beds.
50
-------
Perchloroethylene is lost from the solvent system in the exhaust air
from the carbon filters, general exhaust, water-solvent separators, residue
from the still and residual solvent in the polyester fiber. The total loss
should not exceed 0.033 pounds of perchloroethylene per pound of warp yam.
No one has reported any problems in meeting the TLV for perchloro-
ethylene in the working area around the ranges since most of these units are
engineered to maintain a slight negative pressure in the units to prevent
escape of solvent at the machine. A report on solvent scouring for knit
goods (5) shows concentration of perchloroethylene in the atmosphere as shown
in Table 17.
Table 18 shows the exhaust air from the carbon filters on a solvent
desizing system as 29.4 cubic feet of air exhausted per pound of fabric and
a total loss of 0.0525 pounds of perchloroethylene per pound of fabric. The
concentration of perchloroethylene in the atmosphere should be similar to
that on the solvent sizing system.
The combined environmental effects of various sizing and desizing
systems are shown in Table 19. These totals are per pound of fabric for
sizing and desizing and the warp yarns are considered to be 60% of the fabric
weight.
51
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TABLE 18. ENVIRCNMEMaL EFFECTS OF AQUEOUS AND SOLVENT
DESIZING SYSTEMS
CATEGORY
AQUEOUS SYSTEMS
PVA
Conventional Reclamation
SOLVENT SYSTEM
Gallons of water
consumed per pound
of fabric
Effect on plant's
waste water treatment
Cubic feet of air
exhausted per
pound of fabric
Pounds of perchloro-
ethylene loss per
pound of fabric
Concentration in ppm
of perchloroethylene
in atmosphere at:
production machine
distillation unit
exhaust stack
0.98
major
268.2
0.54
minor
268.2
3.4*
minor
29.4**
0.0525
40.0
30.0
100.0**
"Majority is recovered and available for process water.
**From carbon filters. Does not include other units.
52
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TABLE 19. SUMMARY* OF ENV1IO3MENTAL EFFECTS OF AQUEOUS AND SOLVENT
SIZING AND EESIZING SYSTEMS
CATEGORY
Gallons of water
consumed per
pound of fabric
Effect on plant's
waste water
treatment
Cubic feet of air
exhausted per
pound of fabric
Pounds of perchloro-
ethylene loss per
pound of fabric
AQUEOUS SYSTEMS
PYA
Conventional Reclamation
1.13
major
1,099.8
0.69
minor
17099.8
SOLVENT SYSTEM
5.44**
minor
55.92***
0.0723
*Totals per pound of fabric for sizing and desizing. Warp yarns
are considered as 60% of fabric weight.
**Majority is recovered and available for process water.
***From Carbon filters. Does not include other units.
53
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SECTION 10
ENERGY CONSUMPTION OF AQUEOUS AND SOLVENT SIZING
AND DESIZING SYSTEMS
ENERGY CONSUMPTION OF SIZING SYSTEMS
Table 20 contains data en energy consumption of aqueous and solvent
sizing systems as determined from mill surveys, technical literature and in-
formation provided by solvent processing machinery manufacturers. The
majority of thermal energy consumed in a conventional aqueous system is in
tiie form of steam which is used for the drying cylinders around which the
warp yarn passes for removal of water. Iliis can be minimized by use of a
single-dip system and low wet pickup (4). Steam is also required for pre-
paring the sizing materials and to maintain the correct temperature in the
size applicator. The thermal energy in Tables 20,21 and 22 has been calcu-
lated as BTU's of fuel since the steam requirements have been adjusted for
boiler efficiency and line losses. Electrical energy is consumed by the
motors which are required by the process machinery (slasher) and exhaust fans
for the hoods over the drying cylinders. Conventional equipment and proce-
dures are used for applying the size on the PVA reclamation system. There-
fore the energy consumption would be the same for both aqueous systems.
In the solvent sizing system thermal energy is required to heat the air
in the hot air dryer and in the still for the solvent recovery system. Since
less energy is required to evaporate perchloroethylene compared to water, the
thermal energy consumption of the solvent system for sizing is approximately
40% that of the aqueous systems. Electrical energy is consumed by the
motors on the process machinery including the circulating and exhaust fan in
the dryer section and the pumps for the recovery units. The total consump-
tion of energy for the solvent system is less than 50% of that for the
aqueous systems.
ENERGY CONSUMPnON OF DESIZING SYSTEMS
Lnergy consumption of aqueous and solvent desizing systems is shown in
Table 21. in removing conventional sizing materials from yarns thermal
energy is required to heat the desizing solution, maintain the correct temp-
erature of the fabric during the chemical reactions and to heat the water
which is used to remove the materials from the fabric. Energy for drying the
fabric is not included since in a continuous aqueous process the fabrics nor-
mally pass from desizing to a subsequent process without intermediate drying.
Detail information on the energy consumption of the PVA reclamation de-
sizing system was not available to the investigators. According to reports
and personal ccranunications with machinery manufacturers, the total energy
54
-------
consumption should be less than that for conventional systems due to reuse of
water in the desize washer. The thermal energy consumption would be consid-
erably less since the wash water is recycled to the desized washer but the
electrical energy consumption would be much higher on account of the require-
ments of the PVA recovery system.
Drying of the fabrics is required in the solvent system so that the
solvent may be recovered. Thermal energy is required for drying the fabric
and for the solvent and sizing material recovery systems. These demands
result in a high thermal energy consumption for the solvent system compared
to aqueous systems. The electrical energy consumption includes the demands
for the process machinery and the recovery systems.
The total energy consumption of a solvent desizing system is consider-
ably higher than that for an aqueous system. This is due to the requirements
for drying the fabric and recovering the materials in the solvent system.
TOTAL ENERGY CONSUMPTION OF SIZING AND DESIZING SYSTEMS
Table 22 contains a summary of energy consumption of aqueous and solvent
sizing and desizing systems. The total energy consumptions were calculated
based on the fabric containing 60% warp yarn by weight. The percentage of
warp yarn will vary with different fabric styles but 60% is a reasonable
average.
As compared to aqueous systems for sizing and desizing, the solvent
system requires less energy for sizing but more for desizing. The total
energy consumption for sizing and desizing with an aqueous system is approxi-
mately the same as the energy consumption for solvent systems. Therefore,
there would be no appreciable energy savings for replacement of aqueous
sizing and desizing systems with solvent systems.
TABLE 20. ENERGY CONSUMPTION OF AQUEOUS AND SOLVENT
SIZING (SLASHING) SYSTEMS
CATEGORY AQUEOUS SYSTEMS SOLVENT SYSTEM
PVA
Conventional Reclamation
Thermal BTU's
consumed per pound
of warp yarn 2085.3 2085.3 802.3
Electrical BTU's
consumed per pound
of warp yarn 87.7 87.7 193.0
TOTAL BTU's consumed
per pound of nn_ _
warpyarn 2173.0 2173.0 995.3
55
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21. ENERGY CCNSUMPTICN OF AQUEOUS AND SOLVENT
EESIZING SYSTEMS
CATEGORY
Thermal BTU's
consumed per pound
of fabric
Electrical BTU's
consumed per pound
of fabric
AQUEOUS SYSTEMS SOLVENT SYSTEM
FVA
Conventional Reclamation
1361.5
50.1
1960.0
149.8
TOTAL BTU's consumed
per pound of
fabric
1411.6
2109.8
*Exact information not available.
TABLE 22. SUMMARY* OF ENERGY OCNSUMPTICN CF AQUEOUS
AND SOLVENT SIZING (SIASHING) AND EESIZIMG SYSTEMS
CKEEOQRY
SYSTEM SOLVENT SYSTEM
Conventional
Thermal BTU's
consumed per pound
of fabric
Electrical BTU's
consumed per
pound of fabric
2612.7
102.7
2441.4
265.6
TOTAL BTU's consumed
per pound of
fabric
2715.4
2707.0
*Totals per pound of fabric for sizing and desizing. Warp
yarns are considered as 60% of fabric weight.
56
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SOLVENT SIZING AND DESIZING FLOW DIAGRAM
Figure 13 is a flew diagram of a solvent sizing system. The size is
applied from perchloroethylene at 75-80°F. Drying occurs in air at between
212 °F. and 266 °F. The add-on of ethyl cellulose or hydroxpropyl cellulose to
the yarn is about 9.0% and 3.3% perchloroethylene on weight of fabric is lost.
This loss can probably be further reduced by improved machinery maintenance
and additional carbon adsorption capacity.
Figure 14 is a flow diagram of a solvent desizing system. Size removal
from the fabric would take place at 75-80° F. Drying of the fabric is in air
at 212° to 266 °F. All of the size is removed by the solvent and 85% of the
size is recovered for recycle. Solvent loss is 5.25% of the weight of fabric
processed. This loss can probably be reduced by improved machinery mainte-
nance and additional carbon adsorption capability.
57
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Figure 13. Solvent Sizing Flow Diagram
SECTION
BEAMS
SIZING APPLICATOR
75 - 80VF
DRYING SECTION
21 Z - Z66UF
BEAMER
»
LOOM
BEAM
STORAGE
Ul
00
MATERIAL BALANCE
In Put Recovered Out Put
Item (Ibs/lM IE? fabric) (lbs/100 Ibs fabric) Clbs/IM IEs" fabric)
Sizing Material 9.0
Perchloroethylene 141.0
137.7*
9.0 (in yarn)
3.3**
*From condenser at dryer, distillation unit and carbon filters.
**0.5 Ibs in yarn. 2.8 Ibs from filters, water separator and general exhaust.
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Figure 14. Solvent Desizing Flow Diagram
W3VEN
FABRIC
SOLVENT UNIT
75 - 80UF
DRYING SECTION
212 - 266UF
BATCHER
Ul
10
MATERIAL BALANCE
Item
In Put
(Ibs/lW TEs" fabric)
Recovered
(lbs/100 Ibs fabric)
Out Put
(lbs/100 IBs" fabric)
Sizing Material
5.4*
Perchloroethylene 150.0
4.59
144.75**
0.81
5.25***
"Based on fabric containing 60% warp by weight.
**From condenser at dryer, distillation unit and carbon filters.
***0.5 Ibs in fabric. 4.75 Ibs from filters, water separators and general exhaust.
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SECTION 11
ECONOMIC EVALUATION OF SOLVENT SIZING .AND EESIZING
Before any new process is adopted the economic impact of the process
must be evaluated. The economic impact of replacing aqueous sizing systems
with solvent systems depends on the comparative cost of materials, energy,
machinery depreciation and waste water treatment. These are the costs which
may substantially vary between these processes and there should be no signifi-
cant differences in the other items of cost. Material costs for solvent
systems will be greatly dependent on the recovery of sizing materials and loss
of perchloroethylene. Improvement in efficiencies in these areas would have
a great effect on the total cost of this system.
Reduction in material cost and waste water treatment are objectives of
the recently developed PVA reclamation system. The majority of the sizing
material is recovered and reused in the sizing (slashing) process. This
greatly reduces not only the material cost but also the pollutants in the
waste water from the finishing plant.
COST OF SIZING SYSTEMS
Table 23 contains cost of material, energy and machinery depreciation
per pound of warp yarn for two aqueous systems and a solvent system of sizing.
The material cost for the conventional aqueous system is higher than the other
two due to the fact that starch, CMC or starch blended with other materials is
removed from the fabric and is not recovered. A majority of the sizing
material is recovered in the solvent system but the material cost is greatly
affected by the loss of perchloroethylene. The material cost for the PVA
reclamation system is the lowest of the three and a majority of the sizing
material is recovered for approximately l/6th the cost of new material. This
cost also includes shipping the recovered PVA a moderate distance from the
finishing plant to the weaving mill. The energy cost for the conventional
and PVA reclamation aqueous systems should be the same but it is approximately
twice that for the solvent system. This is primarily due to the lower energy
requirenents for removing perchloroethylene compared to water. The machinery
depreciation cost for the solvent system is approximately 50% greater than
that for the aqueous systems. The total cost of the items evaluated of the
conventional aqueous system is slightly higher than that of the solvent
system. The cost for the PVA reclamation aqueous system is considerably less
than for the other two.
60
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TABUS 23. POSTS OF AQUEOUS AND SOLVENT SIZING (SLASHING) SYSTEMS
CATEGORY AQUEOUS SYSTEMS SOLVENT SYSTEM
PVA
Conventional Iteclamation
Cost of material
per pound of
warp yarn $ 0.0394 $ 0.0220 $ 0.0361
Cost of energy per
pound of warp
yarn 0.0059 0.0059 0.0031
Cost of machinery
depreciation per
pound of warp
yarn 0.0014 0.0014 0.0020
TOTAL $ 0.0467 $ 0.0293 $ 0.0412
COST CF EESIZING SYSTEMS
Cost of material, energy, machinery depreciation and waste water treat-
ment are shown in Table 24. Exact information on energy consumption of the
PVA reclamation aqueous system was not available and therefore this system
will not be considered in evaluating desizing systems. Contribution of the
perchloroethylene which is lost in the solvent system to the cost of material
for this system results in the material cost being much higher than that for
conventional aqueous systems. The energy cost for the solvent desizing
system is also much higher than that for the conventional aqueous system
since only the solvent system requires drying of the fabric. The machinery
used in the solvent desizing system is much more ecxpensive than that used for
the aqueous systems and therefore the machinery depreciation cost is higher
The cost of waste water treatment varies widely from the 1977 to the 1983
requirements. Only a very small quantity of the waste water from the solvent
system is introduced into the plant effluent and therefore the cost of treat-
ment relating to this process is small.
The comparative cost of aqueous and solvent desizing depends greatly on
cost of waste water treatment. Using the figure $0.0014 for BPT treatment in
1977, the aqueous system has a decided cost advantage over the solvent system.
When the figure $0.0066 for BAT treatment in 1983 is used, the aqueous system
has a small cost advantage. Although information on desizing cost with the
PVA reclamation system was not complete, the cost of reclaimed PVA was avail-
able to the investigator by means of personal communication from a machinery
manufacturer.
61
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TABLE 24. COSTS OF AQUEOUS AND SOLVENT DESIZING SYSTEMS
CATEGORY
Cost of material
per pound
fabric
Cost of energy
per pound of
fabric
Cost of machinery
depreciation per
pound of fabric
Cost of waste water
treatment per
pound of fabric**
(BPT-1977)
TOTAL (BPT-1977)
(BAT-1983)
AQUEOUS SYSTEMS
PVA
Conventional Reclamation
SOLVENT SYSTEM
$ 0.0041
0.0033
0.0033
$ 0.0006
0.0025
$ 0.0103
0.0052
0.0014
0.0014
0.0066
$ 0.0091
* n m AI
* 0.0001
* 0.0007
$n m "70
« n nnfi
*Inforxnation not available
**Waste water from sizing and desizing processes.
62
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TOTAL COST OF SIZING AND DESIZING SYSTEMS
The total cost of aqueous and solvent sizing, and desizing systems has
been calculated and is shown in Table 25, The total cost per pound of fabric
was calculated with warp yarns being considered as 60% of fabric weight. The
total cost for the conventional aqueous system shows a slight advantage over
the solvent system based on water treatment cost for 1977. The cost for the
two systems is practically the same when water treatment costs for 1983 are
included.
TABLE 25. SUMMARY* OF COSTS OF .AQUEOUS AND SOLVENT SIZING
(SLASHING) AND CESIZING SYSTEMS
CATEGORY AQUEOUS SYSTEMS SOLVENT SYSTEMS
Conventional
Cost of material per
pound of fabric $ 0.0277 $ 0.0320
Cost of energy per
pound of fabric 0.0068 0.0071
Cost of machinery
depreciation per pound
of fabric 0.0011 0.0026
Cost of waste water
treatment per pound
of fabric**
(HPT-1977) 0.0014 0.0001
(BAT-1983) 0.0066 0.0007
TOTAL (BPT-1977) $ 0.0370 $ 0.0418
(BAT-1983) $ 0.0422 $ 0.0424
*Totals per pound of fabric for sizing and desizing warp yarns are
considered as 60% of fabric weight.
**Waste water from sizing and desizing processes.
63
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REFERENCES
1. Anon. PVA Reclamation Solves Textile Mill Waste Treatment Problem;
Yields Substantial Savings, Union Carbide Corporation F-44993 11/75 - 5M.
2. Anon. The Gaston County PVA Reclamation System, Gaston County Dyeing
Machine Company 17-0772, 10/76 Rev.
3. Gierse, F. J. Problems of Sizing From the Point of View of Environmental
Protection. Melliand Textilberichte 57; 540-541, July 1976.
4. Rozelle, Walter N. Hike Slashing Efficiency, Cut Costs, Textile World
132-137, October 1976.
5. Rolb, K. Practical Experience with the Continuous Solvent Scouring
Machine for Knit Goods. Textile Solvent Technology Update '73. Atlanta
AATCC, January 1973, 91-96.
64
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REPORTS AND PUBLICATIONS
1. "Solvent Slashing Update", Warren S. Perkins and David M. Hall, 1975
Textile Slashing Short Course Lecture Notes, Auburn University Textile
Engineering Department, 1975.
2. "Solvent Slashing for Size Recovery and Pollution Abatement," Warren S.
Perkins, Proceedings of the Textile Wastewater Treatment and Air Pollu-
tion Control Sen-dinar, Clemson University/ Hilton Head, S.C., January 1976.
3. Textile Solvent Processing; A Literature Survey, WRRI Bulletin 25,
Warren S. Perkins, Auburn University, May 1976.
4. "Solvent Slashing", Warren S. Perkins America's Textiles Reporter/Bulle-.
tin ATS, 20-21 (May 1976).
5. "Progress in Solvent Slashing," Warren S. Perkins, J.C. Farrow, D. M.
Hall, B.L. Slaten, R.P. Walker 1976 Textile Slashing Short Course Lec-
ture Notes, Auburn University Textile Engineering Department, 1976.
65
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APPENDIX 1
ENGLISH TO METRIC CONVERSION FACTORS
1 inch (in) = 2.540 centimeters (on)
1 foot (ft) = 30.48 on
1 yard (yd) = 0.914 meters (m) = 91.44 on
1 on = 0.394 in
1 pound (Ib) = 0.454 Kilograms (Kg) = 453.6 grams (g)
1 Kg = 2.205 Ib
1 gallon (gal) = 3.785 liters (1)
11= 0.264 gal
°F = 9/5 (°C) + 32
°C = 5/9 (°F - 32)
66
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APPENDIX 2
GLOSSARY
Certain terms used in this report have special meanings in the field of tex-
tiles. These definitions are provided here to assist readers who do not have
a textile background.
Break factor - the numerical product of the breaking strength in ounces of a
yarn and the yam's cotton count.
Bust, lease or split rod - stainless steel rods used in a slasher to split or
separate the yarns which have been stuck together with sizing material.
Cam draft or Order of lifting - technical draft illustrating the order by
which the harnesses of a loon are raised and lowered during the weft inser-
tions of the weave pattern.
Cotton Count - A number expressing a yarn's length per unit weight where the
number represents the "count" of 840^yard lengths that weigh exactly one
pound.
Creel - that section of a textile process or machine where stock is placed
for feeding into the process or machine.
Dent - in a loom reed, the space between two reed wires usually expressed as
"dents per inch" meaning spaces available in one inch of reed. Also known as
the reed number.
Draw draft or Order of entering - technical draft illustrating the order by
which the warp yarns are drawn into the heddles of the loom harnesses or
which yarns of the weave pattern are controlled by each harness frame.
End - a single yarn, usually in the warp.
Expansion comb - a device used at the slasher to properly space the yarns
prior to winding of the yarn sheet onto the loom beam.
Filling - the widthwise yarns in a woven fabric also weft yarns.
Harnesses - frames that contain the heddles for control of warp yarns in a
loom.
Motes - small pieces of seed or vegetable matter which were not removed fron
cotton in ginning or subsequent processes.
67
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Pick - a single filling or weft yarn in a woven fabric.
Iteed - that part of a loom that dictates the spacing of warp ends to determine
ends per inch in the fabric.
Splitting - separation of sized warp yarns by action of the bust or lease
rods.
Warp - the lengthwise yarns in a woven fabric.
Weave draft or Order of interlacing - technical draft illustrating the order
by which warp yarns are interlaced with the weft or filling yarns of the
weave pattern.
68
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-77-126
2.
3. RECIPIENT'S ACCESSION-NO.
TITLE AND SUBTITLE
Use of Organic Solvents in Textile Sizing and
Desizing
5. REPORT DATE
July 1977
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
W.S.Perkins, D.M.Hall, B.L.Slaten, R.P.Walker,
and J. C. Farrow
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORGANIZATION NAME AND ADDRESS
Alabama Textile Education Foundation
115 Textile Building
Auburn, Alabama 36830
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
Grant R803665
2. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final: 5/75-3/77
14. SPONSORING AGENCY CODE
EPA/600/13
s.SUPPLEMENTARY NOTES jjERL-RTP project officer for this report is Max Samfield, Mail
Drop 62, 919/541-2547.
s. ABSTRACT ^^ report gives results of a study of textile sizing and desizing in organic
solvents. Properties of materials applicable as warp sizes in organic solvents were
satisfactory for utilization as warp sizes. Properties of fabrics made from solvent-
sized yarns were equal in quality to those of fabrics made from aqueous-sized yarns.
Energy consumption for solvent sizing and desizing is essentially equivalent to that
required in conventional aqueous systems. Costs of solvent and aqueous sizing and
desizing are about equivalent if the estimates include anticipated 1983 wastewater
treatment costs. Major materials cost in solvent operations is for solvent lost in the
process (7. 3%); the loss can be reduced by proper engineering design. Solvent
sizing and desizing would virtually eliminate all of the biochemical oxygen demand
(BOD) load in wastewater effluents typical in aqueous operations.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Pollution
Textile Processes
Textiles
Sizing
Organic Solvents
Industrial Water
Waste Water
Wastewater Treat -
ment
Biochemical Oxygen
Demand
Yarns
Fabrics
Pollution Control
Stationary Sources
Slashing
Desizing
Aqueous Sizing
13B
13H
11E
11K
06C
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
79
20. SECURITY CLASS (Thispage}
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
69
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