US2875099A

US2875099A - Finish for polyester textile materials

Info

Publication number: US2875099A
Application number: US690529A
Authority: US
Inventors: Keith B Bozer; Robert S Montgomery; Wesley L Archer
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1957-10-16
Filing date: 1957-10-16
Publication date: 1959-02-24
Anticipated expiration: 1976-02-24

Description

Feb. 24, 1959 FR" POINT IN BYBLES K. a. BOZER EIAL mus FOR pouss'rzn TEXTILE MATERIALS Filed Oct. 16. 195'? Po/yes/er po mer yarn fih/ISAGO will; ,o/as/i/Teo 000/ 00/0 fWm.

0' oouvsnnom musn ron POLYESTER mu 0 con AOIDS FINISH o I l l l I l o 2 4 e 8 l0 l2 I4 mu UP or rnusu on POLYESTER mu m PERCENTAGE av \mcur INVENTORS. Kai/A 6.6o er Robert 6. Montfgomery By Wes/e5 1.. flrc/aer HTTORNEYS United States Patent air/5,099 FINISH FOR POLYESTER raxms MATERIALS Application October 16,1957, Serial No. 690,529

18 Claims. (Cl. 117-1383) This invention relates to the finishing of polyester yarns, threads, cords, and the like filamentary structures and textile materials in order to facilitate their construction into cloth and fabric. The invention has particular reference to the sizing of polyester warp ends for subsequent weaving operations. It also relates to the finished polyester yarns and the like that are obtainable through its practice. r

The polyester textile materials that are contemplated as being adapted for employment in the practice of the present invention include any of the polyester high polymers of the type that are well known in the art which are capable of being fabricated into useful fiber structures. Such fiber-forming polyester polymers are the essentially linear condensationzproducts of glycols and polyglycols with dicarboxylic organic acids, which acids are ordinarily aromatic in nature as, for example, dicarboxylic benzene and substituted benzene acids. In particular, the polyester polymers that are contemplated may be similar and analogous to those which have been described, amongst other places, in United States Letters Patent No. 2,465,319. Specifically there may be mentioned as especially desirable species of such materials the polyester polymers of terephthalic acid and propylene or ethylene glycol, or their mixtures. Synthetic textile fibers that are comprised of polyester polymers of terephthalic acid and ethylene glycol are commercially available from the -E. I. du Pont de Nemours & Co., Inc., under the trade name Dacron.

' It would be an advantage to provide an effective and relatively inexpensive means for finishing textile yarns and the like that are comprised of essentially linear, fiberforming polyester polymer fibers and filaments (which frequently are generically characterized and referred to as being polyester fibers) in order to facilitate their construction into cloth and fabric. Such a finish would be especially desirable if it could adequately protect theyarn during the course of its construction and conversion into cloth and fabric without exerting any adverse effect upon its physical or chemical constitution. Its utility would be replete and its desirability greatly enhanced if it were capable of temporary or fugitive application and would not require or involve the utilization of unusual or extraordinary scouring techniques to achieve its complete removal from the polyester yarn or from fabric constructed therefrom. It would be particularly advantageous to provide such means to size warp ends of polyester yarn for subsequentweaving operations. A polyester yarn finished accordingly would be a most proficuous commodity. The achievement of these desiderations and corollary advantages and benefits are, therefore, amongst the principal objects and purposes of the present invention.

To the realization of these and related ends, polyester yarn may advantageously be finished for its construction into cloth and fabric by the application thereto or deposition thereon of a plastified film of mixed aromatic from the oxidation of coal which, for convenience, are hereinafter referred to as coal acids compounds. The coal acids compounds may either be the free coal acids, the water soluble salts, particularly the alkali metal (including lithium, sodium and potassium), magnesium and ammonium salts of the coal acids, or mixtures thereof. Beneficially, the finishing film of the'coal acids compounds may be plastified by a solvent materialfor the coal acids compounds selected from the described group and the finish application may be accomplished with a solution of the coal acids compounds in such solvent material. Preferably, the 'film is plastified with water and the coal acids compounds are applied in an aqueous solution in order to finish the polyester yarn. It is usually desirable and economically attractive to utilize the free coal acids for finishing polyester yarn, although in many instances andfor many purposes, particularly where. a less acidic finish may be required, the water soluble coal acids salts may be used suitably. Advantageously, warp ends of polyester yarn may be sized, preparatory to weaving, by application of an aqueous solution or mixture of the free coal acids or their water soluble salts or mixtures of the free acids and their salts to the yarn by means of conventional slashing techniques.

polycarboxylic acid compounds such as may be obtained Polyester yarn that is finished or sized in accordance with the present invention with a plastified coal acids film (which, as indicated, may be comprised of either the free coal acids, their water soluble salts or mixtures thereof) is adequately lubricated to minimize friction and has excellent resistance to' abrasion upon passage through mechanical yarn handling apparatus. This facilitates its being woven or knit into cloth or fabric without injury or operational difficulty. In addition, the yarn is not harmfully or objectionably influenced by either discoloration or diminishment of physical properties due to the presence of the coal acids sizing finish. Besides this, a coal acids finish, whether it is comprised of either the free acids or their water-soluble salts, is not injurious or significantly corrosive to the guides and other yarn contacting surfaces and elements in conventional yarn handling and cloth or fabric manufacturing equipment. Furthermore, polyester yarn that is provided with a coal acids finish may be scouredto a clean and finish-free condition by conventional techniques using the ordinarily employed detergent baths and scouring agents. The polyester yarn that is finished according to the invention is at least commensurate and may frequently be superior in these and other particulars to yarns finished or sized with conventional materials, such as the partial sodium salt products of polymethacrylate which is substantially devoid of free carboxylic substituents and is commercially available from Rohm and Haas Company under the trade-designation Acrysol P-4, and the like. A specimen of a polyester polymer synthetic textile yarn finished in accordance with the present invention is schematically represented in Figure 1 of the accompanying drawing.

Any solvent substance for the coal acids compounds that is inert to the polyester polymer in the yarn being sizedmay be employed for the applicatin'g solution and to plastify the finishing substance. It is, as indicated, usually most beneficial and preferred to utilize water for such purpose. However, in many cases, other solvent substances, particularly polar solvents, may be suitable, including glycerine, normally liquid glycols and polyglycols and the like, especially those having relatively high boiling characteristics. Aqueous mixtures of many polar solvents, such as water-glycol combinations, may also be found satisfactory for dissolving and plastifying the coal acids compounds.

A sufiicient quantity of the solvent should be retained in the n'lastified film of coal acids compounds that envelopes the yarn as a finish to permit it to be soft, adequately flexible or pliable and sufiiciently lubricatory to achieve the desired function. The film should be sufficiently plastified toallow suitable permeation of the yarn, especially when multiple filament yarn is involved, while remaining in a substantially continuous film phase on the surface of the yarn. It should also be capable of substantially regaining its essential continuity on the surface after having been temporarily broken by such deformations of the yarn as bending or flaring of multiple filament yarn which may occur in handling.- Generally, a plastified film of the coal acids compounds that contains between about'0.5 and 10.0 percent by weight of water, based on the weight of the film, will exhibit these desirable properties. A water content in an aqueous plastified coal acids compounds film that is in the desired range may usually be simply maintained by keeping the finishing film in equilibrium with air at a relative humidity that is relatively greater than usually normal, as is ordinarily effected during conventional cloth and fabric manufacturing operations. Such a water content, or equivalent concentrations of other solvents, may usually be achieved in the film after application of the solution of the coal acids compounds by permitting the applied solution to approach or achieve equilibrium conditions through air drying. In some cases, however, it may be beneficial to employ heat at elevated temperatures in order to more quickly achieve the desired degree of plastification in the film after application of the solution. As is apparent, the actual water content of aqueous plastified films of coal acids compounds is generally dependent on the relative humidity of the atmosphere to which the finish films are exposed.

The polyester yarn may be finished so as to pick up or retain any desired quantity of the plastified coal acids compounds in film as a finish. For purposes of most fabric construction, there is usually little benefit to be achieved when a finish pick up greater than about 20 percent by weight, based on the weight of the yarn, is exceeded. Advantageously, the pick up may be between about 0.5 and percent by weight. oftentimes, an amount of the plastified film of coal acids compounds on the yarn that is in the neighborhood of 3 percent by weight may be found suitable, especially for purposes of finishing continuous filament yarn. When yarn that has been mechanically spun from staple lengths is being finished, it may sometimes be advantageous to apply comparatively greater quantities of the coal acid film than may be best suited for filament yarn. In addition, especially when a spun yarn is being finished, it may also be beneficial to employ thickening agents in the applicating solution of the coal acids compounds in order to facilitate achievement of the desired finish pick up on the yarn.

The finish application may be accomplished readily by immersing the yarn in the aqueous or other solution of coal acids compounds until the desired quantity of the coal acids compounds that are to remain in the plastified finishing film has been assimilated by the yarn. The usual type of operation that is involved in conventional slashing procedures using ordinary slashing or sizing mechanisms may be employed with expedience for such purposes. If desired, however, the aqueous or other solution of the coal acids compounds may be applied to the polyester yarn according to other known procedures for the application of textile finishes. Thus, as will be apparent to those skilled in the art, roller or wick finish applicators and liquid jet or spray devices and techniques may also be employed for application' of the solution of the coal acids compounds. As mentioned, air or other types of drying, as with the assistance tiple or individual continuous filament lengths or is fabricated by being spun from staple lengths may advantageously be finished according to the invention.

of heated ovens or their equivalent, such as heat lamps,

after application of the solution is usually sufiicient for formation of the desired film finish. Any polyester yarn in twisted or untwisted condition that consists of mul- The mixed aromatic coal acids compounds that are employed for finishing polyester yarns in the practice of the invention may be identical with or similar to those which may be obtained by the oxidation with gaseous oxygen, which may be contained in the air, of an aqueous alkaline slurry of a finely divided carbonaceous material selected from the group consisting of coal and coke that has been obtained by the carbonization of coal at temperatures beneath about 1300 F. Coal acids compounds that have been obtained by the nitric acid oxidation of suitable carbonaceous materials are also generally satisfactory. Such coals that are of the varieties known as anthracite, bituminous and lignite and other low grade coals are generally suitable for production of coal acids. Satisfactory cokes are those produced according to conventional techniques from coal at a temperature beneath about 1300" F. The utilization of higher coking temperatures frequently causes the cokes that are obtained to be graphitic and rendered unsuitable for conversion to coal acids compounds in satisfactory yields.

The preparation of coal acids compounds from coal may, by way of illustration, involve mixing a ground bituminous coal with a caustic alkali, such as sodium hydroxide, and water using an excess of the caustic with respect to the amount that is contemplated as being required for neutralizing the coal acids compounds that are formed. Generally, an apparatus is employed that is constructed from a corrosion-resisting material of construction and that is adapted for operation under pressure. The apparatus is also equipped with an efficient mixing or agitating mechanism andwith suitable heat-exchanging means. The weight ratio of the charged ingredients may, for example, be in the proportion of about three parts by weight of the coal to nine parts by weight of the caustic alkali to about onehundred-twenty-five parts by weight of water. Oxygen is bubbled through the agitated charged ingredients while they are maintained at a temperature between about 390 and 575". F. and under a pressure of from about 500 to 1200 pounds per square inch. The exothermic reaction is continued until substantially all of the carbonaceous ingredients of the coal have gone into solution. This usually requires a period of time between about two and three hours. In the oxidation reaction that occurs, about half of the carbon in the coal is converted to organic acid compounds while the remainder is oxidized to carbon dioxide. Upon tcrmi nation of the reaction and cooling of the reaction mass, the coal ash is filtered out of the alkali-neutralized coal acids solution that is obtained.

The free coal acids may then be isolated by acidifying the solution with sulfuric acid and, after filtration,-

recovering the water-soluble free acids by extraction with a suitable solvent, such as methyl ethyl ketone, which does not dissolve in water in the presence of such salts as sodium sulfate, which is obtained in the acidified free coal acids solution. Evaporation and drying techniques may be employed for subsequently isolating the free coal acids. The coal acids may thus be prepared as solid materials that are often pulverized for subsequent handling in a power form.

The free coal acids product is a hygroscopic, usually yellowish, essentially water soluble material. Its water-soluble salts usually have similar characteristics. The free coal acids product is believed to be substantially comprised of various aromatic polycarboxylic acids. The average molecular weight of the coal acids that are ordinarily obtained is frequently in the neighborhood of 250-270. Their average molecular weight is seldom less than 200 or more than 300. The average equivalent weight of the coal acids is generally about 80; seldom being less than 70 or more than 90. The free coal acids ordinarily appear to have an average of from two and one-half to five carboxylic groups per molecule with an apparent average of about three to four being common. While their exact chemical nature and constitution may be somewhat conjectural, they evidently contain considerable quatities of triand tetracarboxylic benzene acids as well as aromatic acids having more complex nuclei. Frequently, for example, the greatly preponderant proportion of aromatic nuclei obtained in coal acids compounds prepared in the described fashion have been found to consist of methyl naphthalene, benzene, biphenyl, naphthalene, phenanthrene, alkyl benzene (including toluene) and benzophenone nuclei.

The employment of either the free coal acids, or their water-soluble salts, or mixtures thereof, for finishing polyester yarn depends to a great extent, as has'been mentioned, on the degree of acidity that is desired in the finish. It is frequently more beneficial and may often be preferred, as indicated, to employ the free coal acids, which generally have a pH near 2, for this purpose. Less acidic finishes of coal acids compounds may be provided by utilization of the salts or various mixtures of the salts (including partial or acid coal acids salts) with the free coal acids product.

By way of further illustration, the efficacy of a coal acids finish on Dacron polyester multiple filament yarn was determined in a series of tests in which a 150 weight of combined nitrogen; about 0.16 percent by weight of combined sulphur; and to have a carbon-to hydrogen ratio of about 1.46:1, respectively; with an average functionality or number of carboxylic groups per molecule of about 3.36. The coal acids finish was i applied on the yarn by conventional slashing techniques using an aqueous solution of the coal acids that contained about 6 percent by weight of dissolved solids. The temperature of the applicating solution during the slashing was about 120 F. The resulting plastified coal acids finished film was, with respect to its water content, in substantial equilibrium with air at a temperature of about 70 F. that had a relative humidity of about 65 percent. The equilibrium condition was obtained by the conditioning the finished yarn for at least 24 hours in an atmosphere of the indicated character after the slashing operation. For purposes of comparison, the coal acids finished polyester yarn was tested along with identical polyester yarn that was finished with cortimercially available Acrysol P4. The -Acrysol P4 was employed in a conventional manner according to the manufacturers recommendation by means of a slasher. The temperature of the applicating solution of the Acrysol P-4 was controlled at about 140 F.

Several samples of both the coal acid finished and the Acrysol P-4 finished yarn, containing varied amounts of finish were subjected to abrasion tests in which the yarn was run to a fray point at which the component individual filaments in the yarn remained flared out or spread apart when the yarn was not under tension. The test consisted of subjecting a plurality of taut ends of the finished yarn to the reciprocal abrading action of a pair of oscillating knife edges that were opposed to one another and in contact, in about perpendicular relative disposition, with both sides of the yarn. The tests were conducted on a modified version of an apparatus that is open circles.

known as a Duplan Cohesion Tester (for rayon and raw silk) which is manufactured by Geier 8t Bluhm, Inc., of Troy, New York, and were performed in a generally analogous manner to the equipment manufacs turers recommended procedure. The number of oscillations or cycles required to cause failure of the yarn size and fraying of the yarn were observed in each of the tests. The results of the tests are graphically illustrated in Figure 2 of the accompanying drawing in which the fray point, as expressed in the number of cycles required for its' accomplishment, is plotted against the quantity of finish on the yarn, expressed in percent by weight based on the weight of the yarn. The coal acids finished yarn is represented by the solid data points in the graph while the data points obtained on the yarn finished with the Acrysol P4 are represented by the For convenience in interpretation, an average or mean value line is drawn through the represented data points. As is apparent, the coal acids finish was at least as effective in protecting the yarn from abrasion as was the conventional Acrysol P-4 finish.

Two other samples of the same yarn, which respectively contained one or other of the finishes, were tested at intervals during a 36 day period after application of the finishin order to determine whether any adverse effect on the physical properties of the yarn could be noted. The results are given in the following tabulation:

Coal Acids Finished Acrysol P4" Finished Sample Sample D y:

Tenacity, Percent Tenacity, Percent gmsJden. Elongation gins/den. Elongation t From the foregoing it is apparent that the coal acids finish did not have a degradative effect upon the polyester yarn, even when it was permitted to remain thereon for a considerable period of time.

Various scouring tests were performed on the finished polyester yarns. In one of the tests, a skein of yarn that had been sized with about 5-6 percent by weight of the water plastified coal acids film was washed with water for about 15 minutes at a temperature between about .100 and F. After the plain water scouring, the washed yarn was dried and analyzed for residual acid. None could be found. This indicated that the coal acid finish had been completely and readily removed by the plain water wash. In another of the tests, a similar yarn sample that had a coal acids finish application of about 8.3 percent by weight was examined colorimetrically for traces of finish after having been washed at a temperature of about F. for several minutes in an aqueous solution containing about 0.25 percent by weight of Triton X-100 (an alkyl aryl polyester alcohol type of detergent that is available under the indicated trade-designation from Rohm & Haas Company) and about 0.25 percent by weight of sodium pyrophosphate. The scoured yarn sample was subsequently rinsed for 10 minutes in warm water and dried. The sample was compared with a similarly scoured sample of unfinished yarn. The colorometric examination consisted of wrapping the scoured yarn samples on small white plastic chips and analyzing them with a Model No. 75 Hunter Color and Color-Difference Meter supplied [by the Henry A. Gardner Laboratory, Inc. of Bethesda, Maryland.

This instrumentphotoelectrically measures the amount ure of the amount of light reflected from the yarn samples in comparison to that reflected from a standard white tile. The color value indicates the deviation of the sample from white. Negative "a" values are indicative of the presence of a blue-green color in the sample and positive b values are indicative of the relative degree of yellow that is present. The results that were obtained are included in the following table, which also includes a numerical "b" value that was obtained from the stand- As is evident, the scouring with Triton X-100 served to completely remove the coal acids from the yarn. Had they remained after scouring, the "b value of the color tested coal acids finished sample would have been significantly increased due to the inherent characteristic color of the free coal acids.

In addition, similar samples of 150 denier, 68 filament or other forms of Dacron yarn that has been sized in accordance with the invention to obtain about 3 percent by weight (or more or less) of the finish film on the yarn may be advantageously employed for both the warp and filling to weave excellent square woven and other fabrics without operational difficulties that might arise if the finish were inadequate for the purpose. Woven coal acids compounds finished fabric is at least as good as similar fabric woven identically from like yarn that is sized with Acrysol P-4 or other presently employed commercial finishes for the yarn.

Excellent results similar to the foregoing may also be obtained when coal acids compounds finishes, including those comprised of water-soluble coal acids salts, such as sodium, ammonium, or magnesium salts, or mixtures thereof, or with one another or with free coal acids are applied on spun yarns, or when polyester yarns, either filament or spun, are sized or finished with coal acids compounds for subsequent knitting operations. Besides this, the coal acids compounds may also be advantageously utilized for other varieties of polyester polymer synthetic textile fibres in addition to that specifically illustrated herein. Furthermore, the coal acids compounds may also be employed with benefit for finishing polyester yarns in accordance with the present invention when they are employed in combination with other finishing or sizing materials for yarns of polyester polymers which are compatible with the coal acids compounds.

What is claimed is:

1. Method for finishing polyester polymer yarn to facilitate its construction into cloth and fabric which comprises depositing on the surface of the yarn up to about 20 percent by weight, based on the weight of the yarn, of a plastified film of coal acids compounds selected from the group consisting of free coal acids, watersoluble salts of freecoal acids, and mixtures thereof; said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about 70 to 90, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nucleus in their molecule, said film being plastified with a solvent for said coal acids compounds that is inert to said polyester poly'mer yarn.

2. Method for finishing polyester polymer yarn to facilitate itsconstruction into cloth and fabric which comprises applying to theyarn a solution of coal acids coal acids compounds that is inert to said polyester polymer yarn; and forming therefrom up to about 20 percent by weight, based on the weight of the yarn, of a plastified film of said coal acids compounds that is plastified with said solvent on the surface of the yarn; said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about 70 to 90, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nucleus in their molecule.

3. Method for finishing polyester polymer yarn to facilitate its construction into cloth and fabric which comprises applying to the yarn an aqueous solution of coal acids compounds selected from the group consisting of free coal acids, water-soluble salts of free coal acids, and mixtures thereof; and forming therefrom up to about 20 percent by weight of a water plastified film of said coal acids compounds on the surface of the yarn; said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about 70 to 90, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nucleus in their molecule.

4. The method of claim 3, wherein between about 0.5 and 10 percent by weight of said water plastified film of said coal acid compounds is formed on the surface of the yarn.

5. The method of claim 3, wherein the aqueous applicating solution of the coal acids compounds contains between about 0.5 and 30 percent by weight of said coal acid compounds, based on the weight of the solution.

6. The method of claim 3, wherein the aqueous applicating solution of the coal acid compounds contains between about 2 and 8 percent by weight of said coal acid compounds, based on the weight of the solution.

7. The method of claim 3 and including the intermediate step of drying the applied aqueous solution of said coal acids compounds to about moisture equilibrium with the surrounding atmosphere to formthe plastified film thereof on the surface of the yarn.

8. The method of claim 3, wherein said coal acids compounds are the free coal acids.

9. The method of claim 3, wherein the polyester polymer yarn is multiple filament yarn.

10. Synthetic textile yarn of a fiber-forming polyester polymer provided with up to about 20 percent by weight, based on the weight of the yarn,- of a finish comprised of a plastified film of coal acids compounds selected from the group consisting of free coal acids, water soluble salts of free coal acids, the mixtures thereof; said coal acids being the water-soluble mixed aromatic polycarhoxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about 70 to 90, and contain an average of from about 2.5 to 5 c'arboxylic groups per aromatic nucleus in their molecule, said film being plastified with a solvent for said coal acids compounds that is inert to said polyester polymer yarn.

11. Synthetic textile yarn of a fiber'forming polyester polymer provided with up to about 20 percent by weight, based on the weight of the yarn, of a finish comprised of a water plastified film of coal acid compounds selectedfrom the group consisting of free coal acids, water soluble salts of free coal acids and mixtures compounds selected from the group consisting. of fre e e f; said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about 70 to 90, and contain an average of from about 2.5 to carboxylic groups per aromatic nucleus in their molecule.

12. Polyester polymer yarn finished in accordance with claim 11 with between about 0.5 and percent by weight of the water plastified film of said coal acids compounds, based on the weight of the yarn.

13. Polyester polymer yarn finished in accordance with claim 11, wherein the water plastified film of said coal acids compounds is substantially in moisture equilibrium with the surrounding atmosphere.

14. Multiple filament polyester polymer yarn finished according to claim 10.

15. Sized warp ends of polyester polymer yarn in accordance with claim 10.

16. Yarn finished according to claim 10, wherein said polyester polymer is a fibre-forming condensation product of terephthalic acid and ethylene glycol.

17. Synthetic textile yarn of fibre-forming polyester polymer finished with up to about 20 percent by weight, based on the weight of the yarn, of a water plastified film of free coal acids; said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids typically have an average molecular weight of from about 200 to 300, an average apparent equivalent weight of from about to 90, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nucleus in their molecule.

18. Yarn finished according to claim 17, wherein said polyester polymer is a fibre-forming condensation product of terephthalic acid and ethylene glycol.

References Citedin the file of this patent UNITED STATES PATENTS 2,199,989 Dickey et al. May 7, 1940 2,292,211 Dickey Aug. 4, 1942 2,779,684 Alles Jan. 29, 1957 2,803,607 Stroh Aug. 20, 1957 2,808,340 Learn Oct. 1, 1957

Claims

1. METHOD FOR FINISHING POLYESTER YARN TO FACILITATE ITS CONSTRUCTION INTO CLOTH AND FABRIC WHICH COMPRISES DEPOSITING ON THE SURFACE OF THE YARN UP TO ABOUT 20 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE YARN, OF A PLASTIFIED FILM OF COAL ACIDS COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF FREE COAL ACIDS, WATERSOLUBLE SALTS OF FREE COAL ACIDS, AND MIXTURE THEREOF; SAID COAL ACIDS BEING THE WATER-SOLUBLE MIXED AROMATIC POLYCARBOXYLIC ACIDS THAT ARE THE PRODUCTS OF THE OXIDATION OF COAL AND THE LIKE CARBONACEOUS MATERIALS, WHICH ACIDS TYPICALLY HAVE AN AVERAGE MOLECULAR WEIGHT OF FROM ABOUT 200 TO 300, AN AVERAGE APPARENT EQUIVALENT WEIGHT OF FROM ABOUT 70 TO 90, AND CONTAIN AN AVERAGE OF FROM ABOUT 2.5 TO 5 CARBOXYLIC GROUPS PER AROMATIC NUCLEUS IN THEIR MOLECULE, SAID FILM BEING PLASTIFIED WITH A SOLVENT FOR SAID COAL ACIDS COMPOUNDS THAT IS SAID POLYESTER POLYMER YARN.