US2874069A - Method for reducing the pilling tendencies of fabrics - Google Patents

Description

r H amass Pa tented Feb.17,1959

METHOD FOR REDUCING THE PILLING TENDEN'CIES OF FABRICS Dmitry M. Gagarine and Henry Repokis, Clemson, S. C., assignors to Deering Milliken Research Corporation, Pendleton, S. C., a corporation of Delaware No Drawing. Application March 12, 1954 Serial No. 415,966

18 Claims. (Cl. 117-103) This invention relates to fabrics resistant to pilling and more particularly to pill resistant fabrics containing approximately 40% or more non-cellulosic, synthetic, organic fibers, herein referred to for convenience simply as synthetic fabrics, and to methods for reducing the pilling tendencies of fabrics containing 40% or more non-cellulosic, synthetic, organic fibers.

The phenomenon of pilling has been encountered for years with woolen fabrics when such fabrics are worn as clothing and is apparently caused by lint from the textile material becoming entangled with the surface fibers and forming small pills or balls. With woolen fabrics, however, pilling has presented no serious problem since the pills are very loosely held and either fall off or are unconsciously brushed off before there is a serious accumulation.

With the advent of non-cellulosic synthetic fibers, and particularly polyester fibers, it was found that fabrics composed to a large extent or entirely of such fibers not only pill as do woolens but that the pills on such ,materials cling tenaciously, cannot be brushed off, and

can only be pulled off with effort. Because of this, the pills soon reach such an accumulation on such materials, and in particular on polyester materials, as to result in an unsightly appearance and embarrassment to the wearer of clothing made therefrom. It can be seen, therefore, that a method to impart resistance to pilling in synthetic fabrics would be a welcome advance in the art.

According to this invention non-pilling characteristics are imparted to synthetic fabrics by applying to the fabric an aqueous emulsion of a vinyl resin having a softening point below about 350 F., drying the fabric and heating the same at least momentarily to a temperature at least as high as the softening point of the resin.

Vinyl type resins have in the past been employed in a few instances to obtain shrinkage control in woolen fabrics although their use for this purpose never became widespread for the reason that it was found that certain thermosetting resins were far superior for this purpose. Vinyl type resins have also been employed on cotton textiles to increase the body and for other purposes. It will be apparent that such uses of the vinyl resins are completely non-analogous to their use in the present invention where no severe shrinkage problem exists and any increase in the body of the material is purely incidental.

The method by which the vinyl resin treatment of this invention decreases the tendency of synthetic fabrics to pill is not fully understood. Pilling difliculties in synthetic fabrics are generally assumed to be due, at least in part, to the high strength of the synthetic fibers and the great force necessary to dislodge the fibers from the surface of the material but the resin treatment of this invention would not be expected to lower the tensile strength of the polyester fibers and would tend to make the surface fibers even more ditficult to dislodge. In fact, many experiments conducted in connection with this invention to establish the reason or reasons that a given fabric does or does not pill have failed to give a. completely satisfactory answer and appear to contradict previously accepted ideas in some respects so that a satisfactory theoretical explanation of the new process of this invention at this time cannot be given.

It is an advantage of the present invention that the process of rendering synthetic fabrics non-pilling is exceedingly simple and does not require equipment not readily available in most textile finishing plants. It is a further advantage of the invention that it makes possible the production of non-pilling synthetic fabrics in an inexpensive manner. However, the most important advantage of the invention is that the treated fabrics are, under optimum condition, substantially unchanged in hand from the untreated materials. Synthetic fabrics are exceedingly sensitive to surface treatments and many processes that are routinely employed on woolen fabrics for various purposes cannot be employed Without rendering the hand of the synthetic material unacceptable. For example it has been found to be impractical to apply to polyester fabrics certain thermosetting resins of types commonly applied to woolens because their application to polyester fabrics completely ruins the hand of the material.

Substantially any vinyl type resin can be employed in the preparation of non-pilling fabrics according to this invention as long as the resin possesses the necessary physical properties of being water emulsifiable, and of having a softening point below about 350 F. Illustrative examples of suitable resins are polymers or copolymers of compounds as illustrated by vinyl chloride, vinyl acetate or other vinyl esters, styrene, methyl acrylate, methyl methacrylate or others esters of acrylic or methacrylic acid, butadiene, and isoprene. If desired, the vinyl resin may also contain a plasticizing agent.

Vinyl resins of the above types vary Widely in their film forming characteristics depending upon the amount and type of plasticizer employed, the degree of polymerization and other factors. Various aqueous emulsions of resins of the above types may form on drying and heating a readily pliable film, a tough stiff film, a very brittle film or only a broken granular mass. If an aqueous emulsion of a resin forms a granular mass on drying and heating, it is considered in this specification as being devoid of film forming characteristics and it is indeed surprising that such resins give results, in some instances, superior to resins having film forming propertics.

The vinyl resin should be applied to the fabric in amounts of at least about 0.4% by weight since smaller quantities sometimes do not result in the treated fabric having the desired degree of anti-pilling properties and amounts of at least 0.8% by weight of the fabric are generally preferred. If the resin has appreciable film forming ability and is applied in amounts greater than about 5%, the hand of the treated polyester fabric is sometimes adversely affected. Resins substantially devoid of film forming characteristics can, in most instances, be safely applied in amounts up to 10% or more. However, it is generally not advantageous for economic reasons to apply more than about 4% of the vinyl resin so that the preferred range is from about .8 to 4% by weight of the fabric.

Vinyl resins suitable for use in this invention are, in many instances, commercially available as aqueous emulsions and substantially all of these preparations may suitably be employed in the new process when diluted to an appropriate concentration. If an aqueous emulsion of a selected vinyl resin is not commercially available, one can readily be prepared by dispersing the powdered dry resin in an aqueous solvent with a suitable emulsifier or by emulsion polymerization of a selected monomer or combination of monomers. When preparing an emulsion from the powdered polymer or from the monomer, substantially any emulsifier, non-ionic, cationic, or anionic that is capable of resulting in a satisfactory emulsion of the resin in an aqueous solvent may be employed. The preferred emulsifying agents are ammonium salts of fatty acids or other materials of this type that are destroyed by the drying operation and cannot thereafter act as rewetting agents.

When an emulsion of a vinyl resin substantially devoid of film forming characteristics is employed, the hand of the resulting fabrics is frequently quite satisfactory without any special measures being taken. However, if one is employing a film forming emulsion, it has been found that a better hand is often obtained if the emulsion is applied in combination with a textile softening agent and even when employing non-film forming emulsions, the hand can sometimes be improved by this procedure. It has been found, however, that the use of a softening agent frequently requires the use of larger quantities of resin for equivalent results.

Any of the many commercially available textile softening agents can be employed for hand improvement. These agents are generally surface active type compounds with insufiicient solubilizing groups to give high detergency and one can employ anionic, cationic or non-ionic materials with satisfactory results. Illustrative examples of anionic softening agents are salts of fatty carboxylic, carbamic or sulfonic acids such as those sold under the trade names of Avitone A by E. I. du Font, and Ahcovel E by Arnold Hoffman & Co. Examples of suitable non-ionic softening agents are polyglycol ethers, esters, or amides such as those sold under the trade-names of Ethofat 60/15 and Ethomid HT 25 by Armour and Co. and under the name Avcosol 100 by American Viscose. And examples of suitable cationic softening agents are amines and quaternary ammonium compounds such as those sold under the trade names of Ahcovel G by Arnold Hoffman & Co., Lupomin Q by Jacques Wolf and Co., Onyxsan HSB by Onyx Oil and Chemical, Triton K60 by Rohm & Haas and Armac HT, Ethomeen 18/15 and Texsoft Cone. by Armour and Co. As a general rule the cationic materials are preferred as they lend themselves well to application with the vinyl resins and since in addition to resulting in a better hand, they also decrease the tendency of the treated fabrics to gather static electricity.

The softening agent can be applied concurrently with the resin or it may be applied before or after resin application. A slightly better hand is often obtained if the resin is first applied and the softening agent is then applied immediately thereafter although it is sometimes more convenient to apply the softening agent to the fabric immediately proceeding the resin application. The softening agent should be applied in amounts equal to at least about 0.1% :by weight of the fabric and best results are obtained if the softening agent is applied in amounts equal to from about 0.5% to 2% by weight of fabric. No added benefits are generally obtained by applying more than about 4% by weight of the softening agent and because of economic factors, such large quantities are not usually employed to advantage.

A convenient and generally satisfactory procedure for applying the emulsion to a polyester fabric comprises simply immersing the fabric in the emulsion, for instance, in a pad :box, and then removing excess liquid, for example by passing the fabric through a pair of pressure rollers. The weight gain resulting from such a procedure is generally from about 50 to 100% of the dry weight of the textile material depending upon the type of fabric and the pressure on the squeeze rolls. In this method of application, the amount of vinyl resin deposited on the fabric depends primarily upon the amount of liquid remaining in the fabric after passage through the squeeze rolls and upon the concentration of resin in the emulsion. Since, as has been previously stated, the weight of resin deposited on the fabric should be equal to from about 0.4% to 10% and preferably from about 0.8% to 4% of the dry weight of the fabric, it can :be seen that the concentration of vinyl resin in the emulsion when employing this method of application should be from about 1% to 12% and preferably from about 2% to 8% by weight of the emulsion.

A novel and preferred procedure for applying the vinyl resin which gives a better hand and more desirable pilling characteristics comprises repeatedly passing the fabric into the emulsion and gradually adding a material to break the emulsion so that the resin is deposited on the fabric as the emulsion is broken. The emulsion can be conveniently broken by any suitable procedure, such as for instance adding a material to destroy the effectiveness of the emulsifying agent. For example, if a water soluble salt of a fatty acid is employed as an emulsifying agent, the emulsion can be broken by adding a salt of a polyvalent metal which reacts with the emulsifying agent to form a water insoluble material. Since in this procedure for applying the vinyl resin substantially all of the resin is eventually deposited on the textile material, the primary consideration is the ratio of total weight of resin to weight of fabric and the exact concentration of the emulsion is of little importance.

Applying the vinyl resin by the exhaustion technique described above not only results in a better hand and better pilling characteristics in most instances but is also advantageous in instances where padding equipment is not available since the procedure can be conveniently performed in a dolly washer or dye beck. Most apparatus of this type 'is designed to best operate with the weight of liquid equal to from about 5 to times the weight of the fabric, and, therefore, the concentration of vinyl resin in the emulsion at the beginning of operations should generally be from about .008 to 0.8% by weight of the emulsion. there being deposited on the textile material an amount of vinyl resin equal to from about .8 to 4% by weight of the textile material which is within the preferred range.

It is an advantage that the exhaustion technique of resin application can readily be combined with a softener application so that both can be applied to the fabric in a single bath. One suitable procedure for accomplishing this result is to employ a cationic softening agent such as a fatty amine that is only soluble in acid solution. The fabric to be treated is then loaded into a dye beck with an acidic solution containing the desired quantity of the softening agent and a molar quantity, equal to at least that of the emulsifying agent in the emulsion to be subsequently added, of a metal salt, such as zinc chloride or other inorganic salts of zinc or metals such as calcium, magnesium and lead, capable of reacting with the emulsifying agent to give a water insoluble material. The pH is then gradually raised to result in the deposition of the softening agent on the fabirc. When the pH has reached a basic value, a concentrated dispersion of the resin employing an anionic dispersing agent, such as a sodium alkylarylsulfonate, sodium oleate or other water soluble salt of an organic acid, is then added to the bath and the pH lowered very gradually. The dispersing agent reacts with the inorganic salt so that the emulsion is broken and deposits completely on the fabric before the pH becomes more acidic than about pH 6. Other satisfactory techniques are also available and will suggest themselves to those skilled in the art in view of the above.

The temperature of application by either of the above procedures is not critical and the resin can be applied at any convenient temperature from about the solidification temperature of the emulsion to the boiling temperature of the aqueous solvent. Excellent results are ob.

As can be seen, this concentration results in tainable at room temperature which is preferred for convenience.

Drying of the fabric after treatment can be effected at any convenient temperature at which the fabric is not damaged. As is Well known to those skilled in the art, however, some synthetic fibers, such as polyester materials, should not be heated for prolonged periods at temperatures of above 200 or 250 P. so that a drying temperature below this range is generally advantageous. On the other hand, it is generally advantageous to dry the fabric at a temperature in excess of the softening temperature of the vinyl resin employed if this is possible without injury to the material. In instances where the softening temperature of the vinyl resin is above about 250 F., the fabric can be dried at a lower temperature and at or near the completion of drying, heated to a temperature above the softening point of the resin for only a sufficient period of time to actually obtain a softening of the resin. Since this requires only a few seconds, it can be readily accomplished withoutmaterial damage to the fabric if the melting point of the resin is below about 350 F.

The invention will now be illustrated by the following specific examples in which all parts are by weight unless otherwise specified:

Example I ,An emulsion containing 2.6% solids is prepared by mixing 30 parts of a commercially available aqueous emulsion containing 45% of a polyvinyl chloride resin (Polyco 446) with 500 parts of water. This emulsion when dried and heated in an open dish forms only a granular mass. A sample of a polyester textile material containing 55% polyester fibers and 45% wool fibers is then immersed in the emulsion until thoroughly wetted and then passed through squeeze rollers to give a liquid pick-up of approximately 84% based on the dry weight of the textile material. The sample is then dried and cured for 10 minutes at 200 F.

The pilling characteristics of the treated samples are then compared to those of an untreated sample .by placing both in a pilling machine in which the samples in each instance are first brushed with stiff nylon bristles for minutes to work up the nap and then rubbed against themselves for 3 minutes. The number of pills on the treated sample are then visually compared to the number on the. untreated sample. The untreated sample is in each instance rated at a value of 100 and the treated sample is rated from 0 to 100 dependingupon the number of pills as compared to the untreated sample. If for instance the untreated sample has a total of 50 pills per unit area and the treated sample had one pill per unit area, the untreated sample would be given a rating of 100 and the treated sample would have a rating of 2.

In this instance the treated sample containing approximately 2.2% polyvinylchloride polymer had a rating of 0 as compared to the untreated fabric. The treated sample'was then subjected to 3 Varsol tumblejar dry cleanings of 20 minutes each and again tested for its pilling characteristics. The sample againhad a rating of 0. In other words, the sample of material resulting from this example was completely resistant to pilling both before and after 3 dry cleanings.

The hand of the treated sample, which as previously explained, is an important consideration when dealing with polyester fabrics, was quite acceptable although somewhat raspy.

Example 11 An emulsion is prepared containing 1.65% solids by adding 15 parts of a commercially available polyvinyl acetate emulsion, having substantially no film forming characteristics (Polyco 117 SS), to 500 parts of water. In the resulting solution there are treated two samples of polyester materials, the first being composed 100% made,

of polyester fibers (Dacron) and the second containing 55 polyester fibers and 45% wool fibers. In each instance the treated samples are passed through squeeze rolls to give a liquid weight gain of approximatey based on the dry weight of material and the samples are then dried and cured 10 minutes at 200 F.

When samples above were tested for pilling characteristics as described in Example I, the sample composed entirely of polyester fibers gave a value of 15 before and 25 following three 20 minute dry cleanings. The hand of the sample was good although slightly boardy. The second sample composed of 55% polyester fibers and 45% wool fibers had a pilling rating of 10 before dry cleaning and a rating of 20 after three 20 minute Varsol washes. The hand of the wool-polyester fabric was excellent and only very slightly difiercnt from the hand of the untreated material.

Example 111 An emulsion is prepared containing 2.4% solids by diluting 30 parts by Weight of a commercially available aqueous acrylic emulsion containing 40% solids (Polyco 319) with 500 parts of water. A sample of a polyester fabric, plain weave, which had been previously dyed is then padded through the emulsion and passed through squeeze rolls to give a liquid pick-up of approximately 80%. The material is then dried on a renter frame, sheared in the usual manner and its tendency to pill tested by the procedure of Example I. The pilling characteristics of the treated material are greatly improved as compared to the untreated control and are found to improve still further following three Varsol dry cleanings. The hand of the treated fabric is excellent and can hardly be distinguished from that of the untreated control. p 7

Example IV In each of three suitable containers there is placed 500 parts by Weight of water and to the first there is added 10 parts by weight of a commercially available acrylic resin emulsion containing 40% by Weight of s lids (RhopleX WG-9), to the second there is added 20 parts by weight of-the acrylic emulsion and to the third there is added 30 parts by weight of the acrylic emulsion. Separate samples of a material composed of 55% polyester fibers (Dacron) and 45% wool fibers are then padded through each of the three emulsions to give in each instance a liquid pick-up of approximately 80%. This results in there being deposited on the three samples 0.6 5%, 1.3%, and 1.9% respectively of acrylic resin. The three samples are then dried and tested against a control sample for pilling, hand and mark-off. The sample of material on which there is deposited 0.65% resin shows only a slight pilling tendency, has an excellent hand and gives no mark-off. The sample on which there is deposited 1.3% by weight of resin displays only a very slight tendency to pill, has a good hand and no mark-off. The sample on which there is deposited 1.9% resin displays no pilling whatsoever although the hand is slightly firm and the material has a slight markoif. The hand of the last two samples is noticeably improved by topping the material with /2% of a commercial nonionic softening agent (Ethofat C15).

Example V of ammonium hydroxide (28% NH Stirring produces a good emulsion.

In a small dyebeck there is placed 5,000 parts by weight of water and the beck loaded with 100 parts by weight of a fabric composed of 55% polyester fibers (Dacron) and 45% wool fibers. The above described emulsion is then added to the beck and the temperature gradually raised to 200 F. in about 1 hour. The exhaustion of the resin onto the fabric is substantially complete. The fabric is then dried and tested for its physical properties. It is found to have a good hand and forms no pills when tested by the procedure described in Example 1.

Example VI To 5,000 parts by weight of water there is added 60 parts by weight of a commercially available aqueous emulsion of a butadiene-isoprene copolymer containing 32.5% solids (Hycar 1500 x 151). A sample of material woven from 55 polyester fibers (Dacron) and 45% wool is then padded through the emulsion and passed through squeeze rolls to give a liquid pick-up of approximately 85%. The material is then dried and found to have a good hand and to be substantially free of pilling tendencies.

Example VII In a suitable container there is placed 100 parts by weight of a wool-polyester fabric, containing 55 polyester fibers (Dacron) and 45 wool, and 3,000 parts by weight of cold water. The cloth is agitated gently while there is added a mixture containing 0.5 part by weight of soybean fatty amines (Armeen SD), 0.5 part by Weight of zinc chloride, and 1 part by weight of acetic acid. The cloth is then agitated an additional 20 minutes at room temperature at the end of which time there is slowly added suflicient ammonium hydroxide to raise the pH to a value of 7.5. To the slightly basic solution there is added 6 parts by weight of a commercially available aqueous acrylic resin emulsion containing 40% by weight of solids (Rhoplex WB-9), with continuous agitation. There is then added very slowly sufiicient sulfuric acid to lower the pH to a value of 6.8 which results in a uniform exhaustion of the resin onto the cloth. The cloth is then passed through squeeze rolls and dried. The dried material has an excellent hand and pilling tendencies are reduced to within satisfactory limits.

Example VIII Example IX Example VII is repeated except that in place of the acrylic resin there is substituted 12 parts by weight of a commercially available aqueous polystyrene resin emulsion containing 50% solids (Monsanto Polystyrene 601- 40). The exhaustion of the resin onto the fabric again proceeds in a satisfactory manner and the treated material has a good hand and satisfactory pilling characteristics.

Example X Example VII is repeated except there is substituted for the wool-polyester fabric an equal weight of a wool-polyacrylonitrile fabric containing 55% polyacrylic fibers (Orlon) and 45 wool. The hand of the treated material is excellent and the pilling tendencies of the wool polyacrylic fabric are measurably reduced.

Example XI Example VII is repeated except that in place of the wool-polyester fabric there is substituted an equal weight of a wool-nylon fabric containing wool and 45% nylon. Again the hand of the treated material is excellent and the pilling tendencies of the wool-nylon fabric are measurably reduced.

Having thus described our invention What we claim is:

1. A method for reducing the pilling tendencies of fabrics containing at least about 40% staple length polyester fibers which method comprises applying to the fabric an aqueous emulsion of a thermoplastic vinyl resin having a softening point above about 250 F. but below about 350 F., and thereafter heating the fabric at least momentarily to a temperature at least as high as the softening point of the resin.

2. The method of claim 1 wherein the resin is an acrylic resin.

3. The method of claim 1 wherein the resin is a polystyrene resin.

4. The method of claim 1 wherein the resin is a butadiene-isoprene copolymer.

5. The method of claim 1 wherein the resin is a vinylchloride polymer resin.

6. A method for reducing the pilling tendencies of fabrics containing at least 40% staple length polyester fibers which method comprises applying to the fabric from about 0.4% to 10% by weight of a thermoplastic vinyl resin having a softening point above about 250 F. but

- below about 350 F., and from about 0.1% to 4% of a textile softening agent and thereafter heating the fabric to a temperature at least as high as the softening point of the resin.

7. A method for reducing the pilling tendencies of fabrics containing at least 40% staple length polyester fibers which method comprises padding the fabric through an aqueous emulsion of a thermoplastic vinyl resin having a softening point above about 250 F. but below about 350 F. to result in there being deposited on the fabric from about 0.4% to 10% by weight of the resin, drying the fabric and thereafter heating the fabric at least momentarily to a temperature at least as high as the softening point of the resin.

8. A method according to claim 7 wherein the resin emulsion is substantially devoid of film forming characteristics.

9. A method according to claim 7 wherein the resin is an acrylic resin.

10. A method according to claim 7 wherein the resin is a butadiene resin.

11. A method for reducing the pilling tendencies of fabrics containing at least 40% staple length polyester fibers which method comprises immersing the fabric in an aqueous emulsion of a thermoplastic vinyl resin containing from about 0.4% to 10% resin based on the weight of the fabric, breaking the emulsion to result in said resin being exhausted onto said fabric, drying the fabric and thereafter heating the fabric to a temperature at least as high as the softening point of the resin, said resin having a softening point above about 250 F. but below about 350 F.

12. A method for reducing the pilling tendencies of fabrics containing at least 40% staple length polyester fibers which method comprises immersing the fabric in an acidic aqueous medium containing from about 0.1% to 4%, based on the Weight of fabric, of a cationic textile softening agent and an inorganic heavy metal salt, gradually raising the pH of the solution until the medium is slightly basic, adding an aqueous emulsion containing from about 0.4% to 10%, based on the weight of fabric, of a thermoplastic vinyl resin having a softening point above about 250 F. but below about 350 F., said emulsion being formed with an anionic emulsifying agent, gradually lowering the pH to an acidic value to result in the exhaustion of the resin onto the fabric, and drying and heating the fabric to a temperature at least as high as the softening point of the resin.

13. The method of claim 12 wherein the cationic softening agent is a fatty amine and the heavy metal salt is zinc chloride.

14. The method of claim 13 wherein the resin is an acrylic resin.

15. The method of claim 13 polystyrene resin.

16. The method of claim 13 wherein the resin is a butadiene resin.

wherein the resin is a 17. The method of claim 12 wherein said emulsifying agent is decomposed by said heating.

18. The method of claim 17 wherein said emulsifying agent is a fatty acid ammonium salt.

References Cited in the file of this patent UNITED STATES PATENTS Rossin Sept. 8, 1953

Claims (1)

1. A METHOD FOR REDUCING THE PILLING TENDCIES OF FABRICS CONTAINING AT LEAST ABOUT 40% STAPLE LENGTH POLYESTER FIBERS WHICH METHOD COMPRISES APPLYING TO THE FIBRIC AN AQUEOUS EMULSION OF A THERMOPLASTIC VINYL RESIN HAVING A SOFTENING POINT ABOVE ABOUT 250*F. BUT BELOW ABOUT 350*F., AND THEREAFTER HEATING THE FABRIC AT LEAST MEMENTARILY TO A TEMPERATURE AT LEAST AS HIGH AS THE SOFTENING POINT TO THE RESIN.