CA1176120A - Method for sizing and pigmenting a polyester yarn - Google Patents

Abstract

PATENT APPLICATION OF
HAL C. MORRIS, GEORGE C. KANTNER
AND DONALD L. GLUSKER
for A METHOD FOR SIZING AND PIGMENTING A POLYESTER YARN
Docket No. 80-59 By: HLG:rmg ABSTRACT
A method for sizing and optionally pigmenting a polyester or polyester-blend yarn by applying thereto (1) a latex of a polymer of monomers comprising, by weight, 45 to 65% of one or more of a C4-C8 alkyl acrylate, 28% - 52%
one or more of a vinyl aromatic monomer or a mixture thereof with up to an equal weight of methyl methacrylate, 3 to 14%
acrylic acid, methacrylic acid, itaconic acid, or a mixture thereof; (2) a melamine aminoplast resin and (3) optionally, a pigment and curing the treated yarn.

Description

~ .1 76l2n BA~KGROUND OF THE INVENTION
-This invention relates to a method for permanently sizing and, optionally, pigmenting a polyester or polyester-blend yarn.
The sizing of textile yarns prior to weaving is con-ventional in the art. A principal object of sizing is to protect the yarn from abrasion during the weaving operation and material such as starches, polyvinyl alcohol, polyacrylates, polyacrylamides and poly-esters are applied to the yarn and subsequently removed after the weaving operation. Permanent sizes are also used to protect the yarn during weaving, to stiffen the fabric and to bind a pigment or dye.
The present invention teaches a particularly suitable method for per-manent size application employing a polymer latex formulation which provides: a superior balance of polymer adhesion to polyester fibers, fiber abrasion resistance under weaving conditions, wash and dry clean durability of fabric produced from the fiber and, in many embodiments, low foaming tendency of the formulation applied to the fiber.
Warp yarns, whether spun or filament, are composed of many fine fibers which are soft and abrade easily. If left unprotected, they could not withstand the rough mechanical action and abrasion they are subjected to on a loom, whether shuttle or shuttleless. Therefore, a size is applied to these yarns to protect them during the weaving process, thus making fabric production possible. After the fabric is woven, the size detracts from the textile aesthetics (hand or feel), for most uses, and properties of the fabric (dyeability) so the size is usually removed following weaving. ~owever, there are certain textiles such as drapery, upholstery fabric, and mattress ticking, in which the presence of a siz,e does not detract from the fabric but actually enhances the desirable properties thereof.
The manufacture of such sized textiles may entail the permanent sizing of polyester or polyester-blend yarn where the yarn is not only sized in a normal slashing operation but permanently colored simultaneously. This process protects the yarn for weaving and eliminates the necessity of post-dyeing the yarn after it is woven into fabric. This is especially useful when yarn dyed filling (weft) is used to give a solid or multi-colored fabric. Also energy *`

- 3 ~76121) can be saved when easily dyeable filling yarns are used. The principal required properties for such a size are:
Warp Size Requirements: (1) good bath stability,

(2) no foaming, (3) no building up on dry cans, (4) good leasing properties, (5) minimal binder or color migration during drying, (6) no tack in the warp beam, and (7) no shredding during weaving.
Pigment Dyeing Requirements: (1) binder must cure in available heat (ca. 130 C.), (2) be durable to a peroxide bleach process, (3) be durable to home laundering and dry cleaning, (4) withstand spot cleaning without a loss in color, and (5) produce maximum color yield.
Employing the pigmented size of the instant invention represents considerable savings over prior art processes because a process step, the post-dyeing of the fabric or yarn, is eliminated.
With polyester yarns, the dye step normally requires both high temperature and pressure each of which represents a considerable use of energy. Another energy consuming step, the desizing of the fabric normally done in a hot bath, is also eliminated.
Partial savings are realized when a warp yarn is pre-dyed, by the process of this invention, and used with an undyed fill yarn which is more easily dyed, such as cotton or rayon, and thus may be dyed by a mild and less energy demanding process. A particular example would be a drapery which uses a polyester warp and a viscose fill.
This pigmented sizing produces materials with as good or better color fastness than dyed yarn. Elimination of the desizing step means that the many advantages are carried over into the final fabric. Altogether the process of this invention thus makes available an inexpensive, color fast, con-venient, high quality, pigment dyed yarn at a considerable reduc-tion in the use of energy, labor, equipment and chemical raw materials. Pigments are generally cheaper than dyes but hereto-fore high quality color fastness via pigment has been difficult.
The process of this invention achieves good fastness as well as high color yield thus representing a further saving. Dyes, especially for polyester, require auxiliaries such as defoamers, leveling agents, solvents, and carriers in addition to the dye itself as well as a size which then must be removed before ~ 17612~

the dyeing step. Thus the process of the instant invention inherently entails the ecological improvements of requiring 1 no solvent or carrier, 2) no disposal of the removed size, 3) less dissipated heat, 4) less water usage and 5) less waste water disposal. The yarn produced by the process of the instant invention yields, by ar~-known weaving processes, a fabric which has a firm hand, is abrasion resistant, strong and peroxide bleach resistant (particularly required if any direct dyes are present) as well as being laundry and dry clean resistant. The yarn size of this invention gives better adhesion to the, chemi-cally similar, acrylic back coatings widely used with drapery,mattress ticking and upholstery fabrics. The improved strength, abrasion resistance and adhesion all work together to increase the fabric life.
BRIEF DESCRIPTION OF INVENTION
In accordance with the present invention there is provided a method for permanently sizing and optionally pig-menting polyester filaments and yarns or blends of polyester with other fibrous or filament ma~erials which blends are prefer-ably at least 50% polyester. The method entails applying to the yarn a polymer latex, a melamine aminoplast resin, and, optionally, a pigment and subsequently curing the treated yarn. The latex polymer is of monomers comprising, by weight, 45 to 65% of one or more of a C4 to C8 alkyl acrylate, 28 to 52% of one or more of a vinyl aromatic monomer or a mixture thereof with up to an equal weight of methyl methacrylate, and 3 to 14% of acrylic acid, methacrylic acid, itaconic acid or a mixture thereof.
DETAILED DESCRIPTION
There is provided in the present invention a method for permanently sizing and optionally pigmenting polyester and polyester-blend yarns by applying thereto a formulation com-prising a polymer latex and a melamine aminoplast resin, suitable for crosslinking the latex polymer, and, optionally, a pigment, and subsequently drying and curing the treated yarn.

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The polymer latex of the instant invention prefer-ably is made by a gradual addition thermal emulsion polymerization process to yield the product at about 35 to 50% solids. Such processes are taught in books entitled "Emulsion Polymerization"
by D. C. Blackley (Wiley, 1975) and S. A. Bovey et al (Inter-science Publishers, 1965). The polymer is preferably a linear polymer free of crosslinks and branch points. The polymer is prepared from monomers comprising, by weight, 4S to 65~, preferably 50 to 59% of a C4 to C8 alkyl acrylate or a mixture thereof, preferably n-butyl acrylate; 28 to 52~, preferably 31 to 46%, of a vinyl aromatic monomer such as styrene, alpha-methyl styrene, and vinyl toluene, or a mixture thereof preferably styrene, with the further proviso that up to half of the vinyl aromatic monomer may be replaced by methyl methacrylate; and

3-14%, preferably 4-12% acrylic acid, methacrylic acid and, less preferably, itaconic acid or a mixture of these. Most preferably the monomers consist essentially of 50 to 59% butyl acrylate, 31 to 46% styrene and 4 to 12% acrylic acid or methacrylic acid.
Desirably, the latex polymer has a weight average molecular weight of about 0.3 to about 2.5 million with 0.5 to about 2.0 million being preferred and 0.6 to 1.5 million being most preferred.
- The diameter of the latex particles is usually between 0.05 and 0.5 microns with the range 0.1 to 0.2 microns being preferred.
The stiffness of the latex polymer is a particularly significant property. If the polymer is too stiff the size will be too hard and will flake off of the yarn as the yarn is flexed during weaving. If the polymer is too soft it will be too sticky causing friction in the loom, sticking to the reeds, and easy removal from the yarn by abrasion, and these processes may further cause a build up of the polymer on parts of the machines employed in processing the yarns and making fabric. Because of these property limitations it is preferred that the latex polymer have I ~7612(1 a T300 between 0 C. and 40 C. with the range 10 C. to 30 C.
being more preferred. T300 is the temperature at which the ten secor.d, torsional modulus of a film, made by drying the polymer latex, is 300 kilograms per square centimeter as measured by the American Society For Testing And Materlals standard method of test D 1043-72. As 300 kgs. per sq. cm. is roughly twenty fold below the glassy modulus of amorphous polymers, such as those of interest herein, the T300 is appreciably higher than the ylass transition temperature (Tg); the difference is usually about 15 C. which value may be used to obtain estimates of T300 from tables of Tg data or calculations (see Fox, Bull. Am. Physics Soc. 1, 3 page 123 (1956) and "Polymer Handbook" 2nd ed, Brandrup and Immergut eds, (John Wiley, N.Y. 1975) Section III, part 2 by Lee and R~therford).
The melamine aminoplast condensates which are employed are either low molecular weight oligomeric or monomeric reaction products of formaldehyde and melamine such as N,N-dimethylolmelamine and alcohol-modified melamine formaldehyde thermosetting resin condensates, e.g. methyl and ethyl alcohol modified, for example, dimethoxymethyl monomethylolmelamine, etc. Preferably, the extent of condensation of these resin-forming aminoplast condensates is such that they are still soluble in water or self-dispersible therein to a colloidal condition. The melamine aminoplast is present at 2 to 40%, preferably 4 to 25% and most preferably 8 to 15% by weight of the latex copolymer. The preferred aminoplasts ~5 are hexamethoxymethyl melamine, such as CymelR 303, and partially methylated polymeric melamine having an equivalent weight about 225 to about 325, such as Cymel 373. Other useful melamine amino-plasts are sold under the tradename AerotexR including Aerotex M-3, Aerotex 900 and Aerotex 23SP.
The amount of copolymer applied to the yarn material may vary from about 0.5 to about 20% by weight depending on the purpose for which the application is intended and on whether or not auxiliary conditioning or sizing agents are included in the composition when it is applied to the yarn. The aqueous bath I l7612~

formulation comprising the copolymer latex may be applied by spraying, dipping, padding, by sizing rolls, transfer rolls or the like, dipping being preferred. An entire warp may be passed through a conventional slasher or a yarn may be individually treated in a single end sizer. The latex has a concentration of 1-25~ by weight solids in the application formulation and excess is removed, such as by squeeze rolls or wipers, and the treated yarn is then dried. Drying is effected by any suitable means such as by heated air or drying cans. Drying may be effected at a wide range of temperatures, such as from 70-120 C, or in conjunction with curing. The formulation is applied at room temperature or at elevated temperatures such as up to about ~0 C. For warp sizing of spun yarns the preferred proportion of polymer applied to the yarn is from 5-15% by weight of the initial weight of the yarn. For the sizing of continuous filament yarns, the preferred proportion is from about 1% to about 10~ copolymer on the weight of the yarn. The higher amount of size is often needed for fine (low) denier zero or low twist yarn. The preferred size add-on for 150 denier zero twist polyester filament is 2.5 - 3.0% (copolymer on yarn).
The article obtained, after application of the sizing composition to the yarn and drying, is essentially free from the disadvantage of developing static charges and loss of sizing material by transfer to guides or by shedding.
The permanent size of the instant application is applied to a yarn which is a polyester, preferably polyethylene terephthalate, yarn or alternatively a polyester-blend yarn.
Filament yarn substrates are preferred although spun yarns are useful. Blend yarns include blends of polyester with up to 50 of other, préferably organic, fibers including natural fibers, such as cotton, and synthetic fibers, such as rayon; the cotton blend being preferred.

! ~76121~
7_ The formulation for application of the polymer to the yarn preferably contains a rheology modifier, such as a homopolymer or a copolymer of an ethylenically-unsaturated acid, such as polyacrylic acid, polymethacrylic acid and hydrolyzed styrene/maleic anhydride copolymer; other carboxyl polymers such S as carboxymethyl cellulose; water-soluble or water-dispersible non-ionic polymers/ such as hydroxyethyl cellulose, polyoxyethylene polymers (although the latter polymers are not as efficient as the ionic polymers), and homo- and co-polymers of acrylamide. Volatile bases, such as ammonia and amines, are used for partial or complete neutralization of the rheology modifiers.
For immersion treatment of the yarn a desirable formulation has, on a solids basis, 3 to 15%, preferably 4 to 8 latex polymer; 0 to 12~, preferably 0 to 8%, most preferably 0 to 4% pigment; 0.05 to 6%, preferably 0.3 to 3% melamine amino-plast, 0.1 to 2.0%, preferably 0.3 to 1.0%, rheology modifier or thickener, and up to 0.6~, preferably up to 0.3~
catalyst for the melamine resin; in many embodiments of this invention no such catalyst is preferred. Optionally, surfactants, anti-foam agents, penetrants, alkaline materials to control the pH tpreferably volatile amines and most preferably ammonia), penetrants and other additives known to those skilled in the art are used to achieve specific desirable properties in the formula-tion or the yarn.
Anionic surfactants which may be added to the formula-tion include the following: sulfosuccinates, such as sodium bis(2-ethylhexyl)sulfosuccinate; sulfates, such as sodium lauryl sulfate; sulfonates, such as sodium isopropylnaphthalene sulfo-nate; alkyl aryl polyester sulfates and sulfonates, phosphate ester types and the like.
Nonionic surfactants which may be added to the formula-tion include the following: octylphenoxypoly(ethyleneoxy)ethanol, trimethylnonyloxypoly(ethyleneoxy)ethanol, nonylphenoxypoly (ethyleneoxy)ethanol, glyceryl trioleate, ethyleneglycol ethyleneglycol monostearate, sorbitan trioleate, sorbitan tri-stearate, and the like.

I ~7612~

Nonionic and anionic penetrating agents and antifoaming agents commonly used by those skilled in the art of sizing and coloring may also be employed. Suitable penetrating agents which may be used include the following: diethanolamine, N-aminoethyl ethanol-amine, ethylene glycol monobutyl ether, diethylene glycol, diethyl-ene glycol monobutyl ether, dipropylene glycol monomethyl ether,ethylene glycol, dihexyl sodium sulfosuccinate, and the like.
Suitable antifoaming agents which may be used include the following isobutanol, n-butanol, iso-decanol, dibutyl phthalate, diethylene glycol laurate, 2-ethylhexanol, n-octanol, polypropylene glycol, tributyl citrate, and the like.
The curing catalysts ~or the aminoplast which may be used include amine or ammonium salts such as ammonium chloride, ammonium nitrate~ ammonium sulfate, ammonium acid phosphate, isopropanolamine hydrochloride, and the like. Generally, any such catalyst may be used with about equal results as may other latent acid catalysts including Lewis acid catalysts.
Any pigments commonly used in textile pigmentation are usable. Suitable water-immiscible colorants which may be used include the following wherein C. I. means Colour Index (published by The Society of Dyers and Colourists): C. I. Direct Blue 86, C.
I. Pigment Yellow 14, C. I. Pigment Blue 15, C. I. Pigment Black 7, C. I. Pigment Green 1, C. I. Pigment Orange 5, C. I. Pigment Red 12, and the like. The preferred colorants are C. I. Pigment Blue 15, and Yellow QR.
The application of the sizing, or colorant-binding, composition to the yarn is by the methods described above, to deposit thereon about 1-10~, preferably 2-5%, by weight solids from the aforedescribed latex polymer formulation. The preferred substrate material is a polyester filament warp yarn.
The treated yarn is dried and cured by heating at 100-350 F. for a period of about 5 seconds to 5 minutes, preferably at 250-320 F. for a period of about 15 seconds to 2 minutes.

~ .~76l2n 1 Optionally the treated yarn may be dried at a lower temperature, such as by standing at room temperature until dry, and then cured at 225-320 F. for a period o~ about 10 seconds to 2 minutes, preferably at 225-300 F. for a period of about 15 seconds to 1 minute.
The process of this invention produces an insoluble size or colorant-binding coating on the yarn substrate which is durable to laundering and dry cleaning. The treated substrate has satisfactory handle and is tack-free. The treated polyester warp yarn is characterized by excellent weaving characteristics.
In the following examples, which are illustrative of the invention, the parts and percentages are by weight and the temperatures are in degrees Celsius unless otherwise expressly noted. The following abbreviations are used.
SLS sodium lauryl sulfate ME monomer emulsion APS ammonium persulfate AA acrylic acid St styrene BA n-butyl acrylate OPE 9.7 octylphenoxypoly(8.7)ethoxy ethanol S/S solids on solids T-300 temperature at which the 10 second torsional modulus is 300 kg/cm2 Tg glass transition temperature MAA methacrylic acid MHI methyl hydrogen itaconate HEMA hydroxyethyl methacrylate EA ethyl acrylate EHA 2-ethylhexyl acrylate IBA isobutyl acrylate MD machine direction MMA methyl methacrylate Example A - Preparation of Emulsion Polymer at 4% Acid The preparation is a gradual addition thermal process producing a latex polymer 58.5% BA, 37.5% St and 4~ AA.

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Ingredients Kettle Charges Monomer Emulsion (ME) 885 g. Water 987 g. Water 1.8 g. SLS (28~) 16.1 g. SLS (28~) 100 g. ME 80 g. AA
( 4.0 g.~ APS in 650 g. St 25_ g.) Water 1270 g. BA
915.8 g. (without ME) 3003.1 g.

Cofeed

4.0 g. APS
120 g. Water 124 g.

Process Water and SLS are charged to a 5-liter kettle and heated to 82 C. The monomer preform, a 100 g. portion of the monomer emulsion, is added, followed by the APS in water, initiator solution.
Ten minutes later, gradual addition of the monomer emulsion, to which had been added the co-feed solution, is begun at 82 C.
and continued at a constant rate for 2 hours, while the temperature is held at 82 - 86 C. A 15-minute hold at that temperature follows the end of the gradual addition, then the reaction mixture is cooled to 55 C. Residual monomers are removed by free radical chasers. The batch is then cooled to room temperature and filtered through cheesecloth.
Properties % Solids = 46.1 % conversion = 99.1 Viscosity avg. molec. wt. = 700,000 pH = 2.1 Viscosity = 32 cps. (Brookfield Viscometer, spindle #1,60 rpm) I l7612~

1 The pH may be elevated by the addition of aqueous ammonia to about 4.5, as was done in the case of the material used in formulations I, V, and IX, Table I, or higher such as 6, for convenience, long term stability, etc.
Example B - Preparation of Emulsion Polymer at 12% Acid The preparation is a gradual addition thermal process producing a latex polymer, 57% BA, 31% St, and 12~ MAA.
Ingredients Kettle Charges Monomer Emulsion (ME) 976 g. Water 968 g. Water 2.6 g. SLS (28%) 18.7 g. SLS (28%) 114 g. ME 191 g. ~AA
4.0 g.~ APS in 473 g. St ~ 25 g. ~ Water 906 g. BA

Cofeed 4.0 g. APS
205 g. Water Process Water and SLS are charged to a 5-liter kettle and heated to 84C. The monomer preform, a 114 g. portion of the monomer emulsion, is added, followed by the APS in water kettle charged initiator solution. Ten minutes later, gradual addition of the monomer emulsion at 20 g./min. and of the cofeed catalyst at 1.7 g./min. is begun and continued at a constant rate while the temperature is held at 83 to 85C. A 15 minute hold at the final temperature is maintained and then the reaction mixture is cooled to 55C. Residual monomers are removed by means of free radical chasers. The batch is then cooled to room temperature and filtered through cheesecloth~
Properties % solids = 38.7 pH = 2.6 Viscosity = 7.0 cps. (grookfield Viscometer, spindle #1, 60 rpm) ~ ~7612~t Example C - A Harder 4~ Acid Emulsion Polymer Employing the preparation method of Example A, a co-polymer having the composition 50 BA/46 St/4 AA is prepared at 45% total solids and a pH of 4.5.

S Example D - A Harder 12~ ACid Emulsion Polymer Employing the preparation method of Example B, a polymer emulsion is made having the composition 50.5 BA/37 St/12 AA
at a total solids of 39.5% and pH of 2.3.
Preparation of Formulations A control formulation for the pigment sizing of polyester warp yarns is based on a commercial water dispersible polyester used as a size (Eastman WD), a melamine formaldehyde resin for crosslinking (Cymel 373), a latent acid catalyst, Acrysol G-llO as rheology modifier and anti-migrant, and a pigment.
The formulation follows:

Water 72.8 Eastman3 WD (30% in water) 20.0 polymer size Acrysol~ G-1104(50% in water) 5.0 rheology modifier, (Rohm and Haas Co.) antimigrant Cymel~ 3731(American Cyan- 1.0 crosslinker amide Co.) Ammonium Nitrate(25~ in water)0.2 catalyst Pigment2 dispersion 1.0 Colorant Total 100.0 Brookfield Viscosity Model LVT, #1 spindle at 60 rpm 1~ cps % Size polymer Solids 6%
(Eastman WD) Notes:
30 lCymel 373 - partially methylated polymeric melamine;
equivalent wt. 225 to 325.
2Pigment- American Hoechst - Yellow QR
3Eastman WD - water dispersible polyester size 4Acrysol G-llO- ammonium polyacrylate solution; viscosity 5 aqueous is 90 to 170 cps.

~ ,1 76l2n 1 The above formulation is compared to the following systems based on the Examples A-D copolymers ~Table I). A
water insoluble melamine formaldehyde resin, Cymel 303, is employed at two levels, 0.3 and 1.0%, the second is e~uivalent to the Cymel 373 level used in these formulations and with Eastman WD. Following the first three formulations the latent acid catalyst is removed from the for~.ulation since the desired performance is achieved without a catalyst.

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I 17612(1 1 Preparation of Yarn Each formulation is applied to polyester filament yarn (Avitex Fibers, Inc. Type 200-F polyester 150 denier, 50 filament, 0 twist) on a laboratory single end slasher run at 4M/min. The yarns are either dried thru a dry tube (a 1 meter heated glass tube) for 15 seconds at 115 C. and post cured in a forced air oven for 45 seconds at 132 C. (Example 1) or dried and cured in the dry tube set at 132 C. for 15 seconds (Example 2). The amount of polymer applied to the yarn is believed .o be 3 to 5% of the weight of the yarn.
All sized yarn is conditioned one day at 21 C. and 60%
RH before testing.
Preparation of Fil~s Thin films are cast on a 2 mil Mylar~ film with a #30 wire wound rod, dried for 3 minutes at 115 C. and cured for 45 seconds at 132 C. in a forced air oven.
Evaluation of Results - See Table 2 Adhesion: The sized yarns are evaluated for adhesion using a laboratory sand tumble test (as follows):
Sand Tumble Test: Duplicate 3 yd. skeins of sized yarn are placed in an 8 oz. jar containing 150 g.
of course sand, rotated for 30 minutes on an Atlas Launder-ometer~, removed and rated for percent of the fiber bundle remaining intact; the sand rating (STR).
In a second "adhesion to polyester" test the adhesion to Mylar (thin film) of each formulation is determined by a crinkle test. The test is designed to measure film adhesion to polyester sheet by crumbling the sheet by hand and flattening it noting film separation or cracking.
All the formulations including the control ha~e excellent adhesion. No cracks or separation are noted. Tack is also rated and none of the films are tacky.

~ .17612n 1 Durabilit tG a Peroxide Bleach Process Y
Each formulation is tested for durability to a rather stringent process solution. Thirty yard skeins of the sized yarns are subjected to bleaching in the bleach process solution with mild agitation at the stated time and temperature conditions. The yarn is then compared to unbleached yarn for changes in color, feel and filament to filament adhesion and for the amount of color in the bleach .solution.
Bleach Process Solution 1% H22 - 50% Active 0.1% Sodium Silicate 0.05% NaOH - 50% Active 0.05% Detergent Triton~ X-305 Rohm and Iic~s Co~
Run for 1 hour at 93 C. Ri~se in hot water.
The results are recorded as follows:
Yarn Conditions -Excellent = no loss in color or feel Good = slight loss in feel Fair = separation of yarn filaments Poor = major loss in color and separation of yarn filaments Bleach Solution - ~ellow, pale yellow, pale tinge, clear in improving order.
_olvent Resistance Two solvent resistance tests are run - one relating to dry cleaning, the other to spot cleaning. The dry cleaning test consists of soaking pieces of the thin film, cast on Mylar, in perchloroethylene for 30 minutes and evaluating changes. In each case, the wet films are "grabby" and show a slight reduction in adhesion, however, when dried there are no differences between the soaked and control films. There is no color bleeding into the perchloroethylene.

~ .1 76l2n 1 The resistance to spot cleaning is tested by mounting small skeins of yarn on white cardboard and spraying them with 1,1,1 trichloroethane noting color loss or color running. This test is done on yarn dried and cured simultaneously (Example 2) and in all cases there is no loss in color or running of the pigment. Therefore, all are considered to have excellent spot clean resistance and good durability to dry cleaning.
Formulation Stability Each formulation is monitored for stability (settling or coagulation).

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Example 3 - Polymer Substantivity to Polyester Other emulsion polymers are tested for substantivity to a polyester substrate by determining the tensile strength of a water wet non-woven polyester fabric employing the polymer as its binder. High strength indicates good substantivity of the polymer composition to the polyester or polyester-blend and thus is indicative of good performance, when formulated, cross-linked and cured, as a permanent size.
Polymer emulsions ~Example E through O), prepared by the general procedure of Example A, are formulated to 6% binder solids.
A typical formulation is:
Water - 521.1 g.
25% OPE 9.7 - 0.7 g.
Polymer emulsion (46~ -78.9 g.
solids) The pH of the mix may be adjusted with ammonia as desired without significantly effecting web properties, in these examples it is between 2 and 9.
Carded polyester web (0.5 oz./yd., 17.2 g./m.2) is prepared using Dacron ~ type 54W (Merge 113505) (DuPont) fiber of 1.5 denier and 1.5 in., 3.8 cm., staple length. The webs are supported between two layers of fiberglass scrim and saturated by 6% polymer solids baths on a Birch Brothers Padder at 40 lbs., 18 kg nip roll pressure with a speed of 7.6 yds./min.,

6.9 m./min. The padded webs are dried for 7 minutes at 65 C.
in a forced air oven. To insure that all samples receive a similar heat treatment, all webs are cured for 1.5 minutes at 150 C. except when otherwise noted. The finished fabrics weigh 0.7 oz./yd.2, 24 g./m.2, and contain 30% binder.
Fabrics are tested for wet tensile strength after soaking for 30 minutes in room temperature water and blotting lightly with a towel after removal from the water bath. Specimens are cut to 1" x 6.5" (2.5 cm x 16.5 cm) in the machine direction and are tested on an Instron~ tester with a jaw separation of 5" (12.7 cm) and an extension rate of 2" (5.1 cm)/minute in the machine direction.

I .t76l2n All compositions contain 4~ acrylic acid monomer as does Example A which is used as an internal control for the series.
Properties of polymers yielding fabrics ~ith a water-wet tensile strength similar to that of a fabric of Example A produce sized yarns having the acceptable adhesion, durability to bleach, solvent resistance and stability,characterized by the polymer of Example A,when formulated and applied as a permanent size to a polyester or a polyester-blend yarn.
Water Wet Tensile Binder Composition Strength, Kg Example E 96 BA/4 AA 0.3 " F 85 BA/ll St/4 AA 0.8 " G 75 BA/21 St/4 AA 2.3 " H 70 BA/26 St/4 AA 2.6 " I(l) 63.5 BA/32.5 St/4 AA 2.3 A(2) 58.5 BA/37.5 St/4 AA 2.3 " J 40 BA/56 St/4 AA l.l " K 30 BA/66 St/4 AA 0.6 " L 63.5 EHA/32.5 St/4 AA 3.0 n M 63.5 IBA/32.5 St/4 AA 2.8 " N 63.5 BA/16.25 St/16.25 2.0 " O 53.5 BA/10 EA/32.5 St/4 AA l.9 (1) Viscosity average molecular weight 950,000 (2) Viscosity average molecular weight 700,000 Inspection of these data shows a number of interesting things. There is a marked drop-off in substantivity when the polymer contains more than 75% butyl acrylate mer units and, at the other end of the range, when the butyl acrylate mer units are as low as 40% of the polymer. Substitution of methyl meth-acrylate for half of the styrene in the copolymer produces a small decrease in the water-wet tensile strength of the fabric. Replacement of a limited amount of butyl acrylate by ethyl acrylate has a similar effect.

- ~
~ 17612(1 When binder A is used to bond a rayon/polyester (1/1) non-woven fabric a water-wet tensile strength of 1.6 kgs. is obtained, thus the polymer is effective on this sub-strate as well. The rayon/polyester fabric is made from DuPont Dacron~ type 54 W (1.5 denier/4.0 cm.) polyester and FMC viscose rayon (1.5 denier-4.0 cm.). The finished fabric weighs 23.7 g. per sq. meter and contains 30% binder on fabric weight. Polyester-rayon yarns permanently sized with Example A
po~ymer, using the procedures and formulations of experiments 1 and 2,are acceptable sized yarns.

Claims (21)

WHAT IS CLAIMED IS:

1. A method for sizing a polyester or polyester-blend yarn by applying thereto (1) A latex of a polymer of monomers comprising, by weight, 45 to 65% of one or more of a C4-C8 alkyl acrylate, 28 to 52% of one or more of a vinyl aromatic monomer or a mixture thereof with up to an equal weight of methyl methacrylate, 3 to 14% acrylic acid, methacrylic acid, itaconic acid, or a mixture thereof;
(2) A melamine aminoplast resin; and curing the treated yarn.

2. The method of claim 1 wherein a pigment is applied to the polyester or polyester-blend yarn.

3. The method of claim 1 wherein the monomers comprise 45 to 65% butyl acrylate, 28 to 52% styrene or vinyl toluene and 3 to 14% acrylic acid or methacrylic acid.

4. The method of claim 3 wherein the melamine to polymer ratio is from about 2% to about 40% by weight and wherein the application is by immersion in an aqueous bath and the polymer is about 0.5% to about 20% of the yarn by weight.

5. The method of claim 4 wherein the monomers comprise 50 to 59% n-butyl acrylate, 31 to 46% styrene, and 4 to 12% acrylic acid or methacrylic acid.

6. The method of claim 5 wherein the monomers consist essentially of 50 to 59% n-butyl acrylate, 31 to 46% styrene and 4 to 12% acrylic acid or methacrylic acid and wherein the melamine to polymer ratio is from about 4% to about 25 by weight and the polymer is about 1% to about 10% of the yarn by weight.

7. The method of claim 4 comprising a pigment.

8. The method of claim 6 comprising a pigment.

9. The method of claim 4 wherein the yarn is essentially a polyester filament yarn.

10. The method of claim 6 wherein the yarn is essentially a polyester filament yarn.

11. A yarn comprising polyester fibers or filaments, or a major proportion thereof in a blend with other fibers or filaments and a size; wherein the size is a melamine aminoplast crosslinked polymer of monomers comprising, by weight:
45 to 65% of one or more of a C4-C8 alkyl acrylate, 28-52% of one or more of a vinyl aromatic monomer or a mixture thereof with up to an equal weight of methyl methacrylate, 3 to 14% acrylic acid, methacrylic acid, itaconic acid, or a mixture thereof.

12. The yarn of claim 11 comprising polyester fibers or filaments, or a major portion thereof in a blend with other fibers or filaments, a size and a pigment.

13. The yarn of claim 11, the monomers comprising 45 to 65% butyl acrylate, 28 to 52% styrene or vinyl toluene and 3 to 14% acrylic acid or methacrylic acid and the polymer is about 0.5% to about 20% of the yarn by weight.

14. The yarn of claim 13 wherein the ratio of the melamine aminoplast crosslinker to latex polymer is between about 2% and about 40% by weight.

15. The yarn of claim 14 wherein the monomers comprise 50 to 59% n-butyl acrylate, 31 to 46% styrene and 4 to 12%
acrylic acid or methacrylic acid and the polymer is about 1%
to about 10% of the yarn by weight.

16. The yarn of claim 15 wherein the polymer consists essentially of 50 to 59% n-butyl acrylate, 31 to 46% styrene and 4 to 12% acrylic acid or methacrylic acid and wherein the melamine to polymer ratio is between about 4% and about 25% by weight.

17. The yarn of claim 14 comprising a pigment.

18. The yarn of claim 16 comprising a pigment.

19. The yarn of claim 14 being essentially a polyester filament yarn.

20. The yarn of claim 16 being essentially a polyester filament yarn.

21. A fabric comprising the yarn produced by the method of claims 1, 4 or 6.