US3403433A

US3403433A - Method of producing pill resistant polyester fiber containing fabrics

Info

Publication number: US3403433A
Application number: US586583A
Authority: US
Inventors: Werner A P Schoeneberg
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1964-06-01
Filing date: 1966-08-10
Publication date: 1968-10-01
Anticipated expiration: 1985-10-01
Also published as: DE1460383A1; NL6506880A; FR1455913A; BE664663A

Description

United States Patent M ABSTRACT OF THE DISCLOSURE A method of producing pill resistant fabrics from polyester fiber containing blended yarns comprising restraining the fabric and then heating the restrained fabric whereby the polyester fiber components shrink and migrate to the center of the yarns making up the fabric.

This invention, which is a divisional application of copending application Ser. No. 371,768 filed June 1, 1964, now abandoned, relates to the production of pill-free, soft, brushed polyester/cellulosic and polyester/wool blend fabrics.

Fabrics of polyester/cellulosic and polyester/wool blends have been gaining substantial commercial importance, especially such fabrics containing wool or wherein the cellulosic is cotton. However, the low covering power of typical polyester/ cotton and polyester/wool blend fabrics emphasizes the unevenness of the yarn while all-cotton and all-wool fabrics with yarns of equivalent evenness appear more even due to the surface cover of the cotton or wool fibers.

It is accordingly an object of this invention to improve the surface cover of polyester/cellulosic and polyester/ wool blend fabrics.

It is also an object of this invention to provide polyester/cellulosic and polyester/wool blend fabrics having a soft brushed surface and good surface cover.

When polyester fiber in staple form is used in polyester/ cellulosic and polyester/wool blend fabrics, a serious problem with regard to pilling of the polyester at the surface of the fabric may be encountered. Such pilling, of course, substantially lessens the desirability of the fabric. The pilling is unpleasing in appearance; at times, large pills will shed from the surface of the fabric, which, of course, is undesirably messy.

Thus, it is a further object of this invention to produce soft, pilling-resistant fabrics of blends comprising polyester staple fibers and cellulosic or wool fibers.

The cellulosic fibers to be used in the blend often will be in staple form, too. This is because the most common of the cellulosic fibers, cotton, occurs only in staple form and because staple fibers, as compared with continuous filaments, generally have a softer hand, softer surface, warmer feeling and are found by the consumer to be more aesthetically pleasing.

Accordingly, it is yet another object of this invention to produce soft pilling-resistant fabrics of blends comprising polyester and cellulosic staple fibers.

Other objects of this invention will be apparent from the following detailed description and claims.

In accordance with one aspect of this invention, there .is provided a method of producing soft, pilling-resistant 3,403,433 Patented Oct. 1, 1968 because in subsequent wet processing, such as dyeing, the polyester fibers remain relatively stable while the cellulosic or wool shrinks substantially, thereby offsetting some of the coring effect obtained. The term coring effect, of course, refers to the selective shrinkage and migration of the polyester fibers in the blend to the center of the yarn. The fabric thus produced will be referred to hereinafter in the specification and claims as a cored yarn fabric. For the same reason that it is preferred to avoid dyeing of the cored yarn fabric, it is also preferred to avoid mercerization or Sanforization of such fabric. The above-mentioned restraining and heating of the restrained fabric will hereinafter be referred to as restrained heat setting.

In another aspect of this invention, it is preferred to remove any polyester fibers remaining at the surface of the heat-set fabric by the use of singeing. Singeing generally involves the exposure of the surfaces of the fabric to a flame, whereby the polyester fibers remaining near the surface of the fabric are selectively burned away because the polyester fibers have a lower decomposition point than the cellulosic or wool fibers. Of course, any other source of sufiicient heat could be used, such as heated rolls or plates past which the fabric would move either near the surface thereof or in contact therewith.

In another aspect of this invention, after the singeing operation, if employed, the fabric is brushed for the purpose of further raising cellulosic or wool to the surface thereof. Preferably after the singeing operation, but prior to the brushing operation, a brushing softener is applied to the fabric. The brushing softener may comprise any of the following, alone or in a mixture: anionic, nonionic and cationic stearic compounds, silicone oils, sulfated oils and fats, alkyl quaternaries or solutions, emulsions or suspensions of'any of the preceding substances, mineral oil emulsions and polyethylene emulsions and the like. Preferably, steam is applied to the fabric during the brushing operation for the purpose of effecting lubrication between the bristle surfaces and fabric surface.

It is preferred to apply the softener alone for best brushed pile formation. However, a finishing resin may be applied with the softener. Such resins may be applied as a solid, melt, solution, suspension or emulsion and, if thermosetting, the unreacted or partially reacted components of the resin may be so applied and subsequently cured. Typical thermosetting finishing resins or reactant resin components which may be applied are methylol urea, methylated methylol urea, methylol cyclic ethylene urea, methylol melamine, methylated methylol melamine, polyesters, phenolic formaldehyde, acetone formaldehyde, epoxy resins, melamine resin acid colloid, dirnethylolpropyleneurea, dimethylol-uron-dimethylether and methylol triazone. Typical thermoplastic resins which may be applied are butadiene/styrene and butadiene/acrylonitrile copolymers and polymers and copolymers of acrylate esters, vinyl acetate, vinyl alcohol, vinyl butyral, vinyl chloride, vinylidene chloride, styrene, ethylene, propylene, linear ester condensates, linear amide condensates, natural rubber and the like.

If it is desired to incorporate calendering in the fabric finishing operations, it is preferred to calender after singeing and brushing because calendering before brushing flattens the fabric and hinders good pile formation in brushing. However, the results achieved in terms of pile formation and pilling performance if the calendering is performed before brushing can be improved by low pressure calendering (e.g., silk calendering) subsequent to the initial calendering and before the brushing. Silk calendering is generally performed by passing the fabric in sequence between the two nips of a three-bowl calender, the top and bottom bowl (roll) surfaces of which are 3 usually paper and the center bowl (roll) surface of which is usually metal.

The resin finish is then cured. For this purpose, a conventional loop dryer is particularly suitable. However, any other type oven or dryer which would provide adequate dwell time (e.g., a conventional roller curing oven) would also be satisfactory. Temperature and dwell time are, of course, dependent on the particular resin finish. However, since conventional resin finishes are used, conventional curing times and temperatures for these resins are well known in the art.

Subsequent to all the above steps, the fabric may be conventionally pressed and/ or decated or semi-decated.

The above referred to restrained heat setting is carried out at from about 325 to about 425 F., preferably from about 350 to 415 F., for a duration of from about 300 to 5 seconds, preferably from about 60 to about seconds (temperature and time being correlated inversely).

The above referred to singeing preferably is carried out at a flame temperature of about 2000 to about 4000 F. for a duration of from about 0.02 second to 0.08 second (temperature and time being correlated inversely).

Hinneken boil off and prescouring are conventional and may be performed at conventional temperatures and durations, which, of course depend upon the specific fabric treated.

The extent of drying of the fabric, subsequent to padding, is preferably to a moisture content of from about 1 to preferably from about 2 to about 10%, whereby, the fabric is suitably soft for the subsequent brushing.

The curing of the finish on the fabric and the decating are performed under conventional conditions.

The term polyester as used in the specification and claims refers to polyesters of glycols and dibasic acids, particularly glycols of the series HO(CH ),,OH where n is an integer within the range of 2-10, and the dibasic acid is one or more of terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dibenzoic acid and the like.

The term cellulosic includes cotton, regenerated cellulose, cross-linked regenerated cellulose derivatives, sisal, hemp, jute, linen, ramie, tampico and the like.

It is not absolutely necessary to use a tenter frame or other restraint during the drying; the major purpose of such restraint is to control the final fabric dimensions. Whether or not the fabric is restrained during drying has no noticeable effect on the results of the subsequent heatsetting operation. The drying temperature is not critical; however, generally temperatures not in excess of about 250 F. are used in order to avoid any premature coring.

The following examples further illustrate the present invention:

EXAMPLE I A sample of viyella flannel made of 26/1s (i.e., yarn made from one end having a cotton count of 26) (19 turns/inch S-twist) of 65% 1.5 denier x 1 /2" polyethylene terephthalate staple fibers and 35% combed Pima cotton both in the Warp and in the filling and having a loom count of 74 ends/inch x 70 picks/inch, the reed width being 50.5" with 37 reed dents per inch and 2 ends per dent and the weave being a 2 x 2 twill, is treated as follows:

(A) Hinneken boil oil. of the fabric at 200 F. with prescouring boxes at 120 F.;

(B) Desizing and scouring of the fabric in a beck;

(C) Union dyeing of the fabric in a beck to a periwinkle shade, using disperse dye with carrier for the polyester and fixable direct dyes for the cotton;

(D) Drying of the fabric with hot air at 250 F.;

(E) Heat setting of the fabric while laterally restrained against shrinkage on a Famatex tenter pin frame at 400 F. for 20 seconds, holding the dyed width (dyed width is the width of the fabric in a completely relaxed state after dyeing and subsequent drying; alternatively, dyed width will be referred to as pre-heat set lateral dimension);

4 (F) Thorough singeing of the fabric; (G) Padding of the following resin finish and fabric softener mixture onto the fabric:

Grams/liter Permafresh LF (dimethyloldihydroxyethylene urea) 60 Catalyst W (organic acid complex sold by Sun Chemical Company, Warwick Division) 12 Moropol 700 (nitrogen-free nonionic polyethylene emulsion) 15 Buffer DCY (dicyandiamid) 4 (H) Drying of the fabric on a tenter clip frame with hot air at 250 F., leaving approximately 5% moisture content;

(I) Brushing of the fabric three times on each side on soft steel bristle brush roll with an open steam pipe attached through which steam is applied to the fabric as it is brushed;

(J) Loop curing of the fabric at 315 F. for four minutes;

(K) Semi-decating of the fabric by the use of a semidecator, with alternate steam and vacuum cycles of from 10 to 60 seconds each.

EXAMPLE II A sample of hopsacking made of 16/1s (15.5 turns per inchZ twist) of 55% 3.0 denier x 2" semi-du1l polyethylene terephthalate staple and 45% 3.0 denier x 2" semi-dull Corval cross-linked regenerated cellulose) both in the warp and in the filling (but the filling being package dyed black) and having a loop count of 72 ends/inch X 54 picks/inch, the reed width being 50" with 36 reed dents per inch and 2 ends per dent and the weave being a 2 x 2 basket weave is treated as follows:

(A) Hinneken boil off of the fabric at 200 F. 'with prescouring boxes at F.;

(B) Desizing and securing of the fabric in a beck;

(C) Dyeing of warp yarns to ironwood (a medium tan shade) union using dye carrier for the polyester;

(D) Drying the fabric with hot air at 250 F. to a dyed width of 48";

(E) Heat setting of the fabric on Famatex tenter pin frame at 400 F., for 20 seconds, holding the dyed width;

(F) Thorough singeing of the fabric at a cotton setting on an Industrial Heat Engineering Singer of Flame 6, Speed 10;

(G) Pad-ding of the following resin finish and fabric softener onto the fabric:

Grams/liter Aerotex resin M3 (melamine formaldehyde condensate resin) 50 Catalyst MX (magnesium chloride) 15 Ahcovel G (cationic softener-fatty carbamide) 15 Triton X-lOO (ethoxylated nonylphenol) 1 (H) Drying of the fabric on a tenter clip frame with hot air at 250 F., leaving approximately 5% moisture content;

(J) Loop curing of the fabric at 320 F. for four minutes;

(K) Silk calendering of the fabric at 5 tons total pressure through both nips of a three-bowl silk calender, the top and bottom roll surfaces of which are paper and the middle roll surface of which is stainless steel;

(L) Pressing of the fabric on a rotary press at setting 35. (This is a number in a range of 0 to 60 indicating about medium pressure. It is a regulation of the distance between a stationary pan and a turning roll. The temperature is constant at about 280 F.)

(M) Decating of the fabric.

EXAMPLE III A sample of lawn made of 70/ ls of 65% polyethylene terephthalate staple and 35% cotton both in the warp and in the filling and having a greige construction of 88 ends/inch x 76 picks/inch, the greige width being 40" is treated as follows:

(A) Desizing and scouring of the fabric in a beck (a lawn is not such a fabric construction as would tend to crack if not relaxed first; this type fabric may or may not be boiled off; as a matter of convenience, it was not; for any particular fabric, whether or not a Hinneken boil off is to be performed is a matter of choice);

(B) Bleaching of the fabric with peroxide in a beck to remove motes;

(C) Dyeing of the fabric in a beck to light union pink shade (using a dye carrier for the polyester);

(D) Tenter clip frame drying of the fabric at 37" (1" over dyed wet width) with hot air at 250 F.;

(E) Heat setting of the fabric on Famatex tenter pin frame at 415 F. for 15 seconds, holding the 37" width;

(F) Singeing of the fabric at a cotton setting on an Industrial Heat Engineering Singer of Flame 6, Speed (G) Silk calendering of the fabric at 5 tons total pressure through both nips of a three-bowl silk calender, the top and bottom roll surfaces of which are paper and the middle roll surface of which is stainless steel;

(H) Padding of the following resin finish and fabric softener onto the fabric:

Grams/liter Permafresh LF (dimethyloldihydroxyethylene urea) 60 Catalyst W (organic acid complex) 12 Moropol 700 (nitrogen free nonionic polyethylene emulsion) 15 (I) Drying of the fabric on a tenter pin frame with hot air at 250 F., leaving approximately 5% moisture content;

(K) Loop curing of the fabric at 315 F. for four minutes;

(L) Decatizing of the fabric.

EXAMPLE IV A sample of oxford made of 42/ ls (with 24 turns per inch-Z twist) in the warp and 15/ ls (with 14 turns per inch-Z twist) in the filling, both of 65% polyethylene terephthalate staple and 35% cotton, the greige width being 48.5 and the weave being a 2 x 1 plain weave is treated as follows:

(A) Desizing and scouring of the fabric in a beck;

(B) Bleaching of the fabric with peroxide in a beck to remove motes;

(C) Dyeing of the fabric in a beck to a mint green union using dye carrier for the polyester; the dyed width is forty-four inches;

(D) Drying of the fabric on a tenter pin frame at the dyed width with hot air at 250 F.;

(E) Calendering of the fabric by passing each side once through a hydraulic calender operating at 280 F. and 30 tons total pressure to a fabric width of 43% inches;

(F) Heat setting of the fabric on a tenter pin frame at 415 F. for 15 seconds while held at a forty-five inch width.

(G) Thorough singeing of the fabric at a cotton setting on an Industrial Heat Engineering Singer of Flame 6, Speed 10;

6 (H) Padding of the fabric with the following resin finish:

(I) Drying of the fabric on a tenter pin frame with hot air at 250 to a width of 45% inches;

(J) Loop curing of the fabric at 320 F. for three minutes to a width of 44 /2 inches;

(K) Brushing of the fabric three times on each side on soft steel bristle brush roll with an open steam pipe attached through which steam is applied to the fabric as it is brushed;

(L) Decatizing of the fabric.

Treatment of the fabric with hot strong caustic solution (15 g./liter) (preferably prior to dyeing so as not to effect the dye and preferably prior to the heat setting step so as not to reverse the coring effect due to the greater shrinkage of cotton than polyester when treated with caustic solution) may be used as an additional and independent anti-pilling measure. Such treatment tends to decrease pilling by partly degrading the polyester yarn whereby the polyester is weakened so that polyester fibers at the yarn surfaces, when rubbed, gradually break away from the surfaces rather than form bunches or balls of tangled fibers on the surfaces (which bunches or balls are commonly known as pills) However, it is generally found that incorporating a caustic treatment into the present selective coring processes gives only a marginal improvement with regard to the brush and sponge pilling test (ASTM Dl37559*T Method C), results which generally cannot justify the concomitant strength loss; also, excellent random tumble pilling test (ASTM 1375) results, comparable to those achieved by the use of caustic treatment with the present selective coring processes, are achieved without the use of caustic and concomitant strength loss.

The following example is illustrative of the effect of an anti-pilling caustic treatment:

EXAMPLE V A sample of the same fabric that is the starting material in Example I is treated as follows:

(A) Hinneken boil off of the fabric at 200 F. with prescouring boxes at 120 F.;

(B) Desizing and scouring in a winch;

(C) Thirty yards of the sample is taken off at this stage and caustic treated on a winch for fifteen minutes with an aqueous sodium hydroxide solution of 15 grams/liter concentration and at a temperature of C. Both this thirty-yard portion of the sample and the balance of the sample are treated alike for comparative purposes as follows:

(D) Union dyeing of the fabric in a beck to a periwinkle shade, using disperse dye with carrier for the polyester and fixable direct dyes for the cotton;

(E) Tenter clip frame drying of the fabric with hot air at 250 F.;

(F) Heat setting of the fabric on a tenter pin frame at 400 F. for 20 seconds, holding the dyed width;

(G) Thorough singeing of the fabric;

(H) Padding of the fabric with the following resin composition:

Grams/liter Permafresh LP (dimethyloldihydroxyethylene urea) 60 Catalyst W (organic acid complex) l2 Moropol 700 (nitrogen-free nonionic polyethylene emulsion) 15 Triton X- (ethoxylated nonylphenol) '1 Buffer DCY (dicyandiamid) 4 (I) Drying of the fabric on a tenter clip frame with hot air at 250 F. to a moisture content of 5%;

Property No caustic Caustic Thread count (ends/inch x picks/inch) 84 x 76 84 x 76 Weight (on/yd?) 4. 53 4. 31 Grab tensile strength (1115.) (ASTM-D39- 75 x 65 53 x 36 59) (breaking strength-grab method) Tear strength (lbs.) (ASTM-Dl424-59) (Elmendorf method) 4. 7 x 4. 4 2. 5 x 2. Random tumble pilling test (15/30/60 minuteS (ASTM-D1375) 515/ 5/515 Brush and sponge pilling test (ASTM-D- 137559T method C) 2 2-3 Samples of all fabrics to be treated by the processes of the present invention may be cross dyed (e.g., cotton 1 to 3% in excess of the pre-heat set dimension during heat setting. When the fabric contains highly shrinkable polyester, the lateral restraining may be within the same range as the lateral restraining used for normally shrinkable polyester, but more latitude of choice is permissible: specifically, the fabric may be allowed to shrink up to about 10% below its pre-heat setting lateral dimension during heat setting while being laterally restrained against further shrinkage; thus, even under such conditions, it is properly said that the fabric is laterally restrained against shrinkage. When the fabric contains highly shrinkable polyester, the lateral restraint during heat setting preferably is such that the percentage to which the lateral dimension of the fabric during heat-setting is maintained above or allowed to decrease below the pre-heat setting lateral dimension is within the range of from about 3% above to about 5% below the pre-heat setting lateral dimension.

The following table (Table I) shows the influence of heat setting with minor stretching, after dyeing (experiment Numbers 1 to 5) and before dyeing (experiment Number 6), followed by singeing alone or with other process steps in sequence, as listed, in accordance with the present invention, upon the pilling resistant properties of polyester/ cotton blend yarns:

TABLE I (SS/% polyethlene (SS/35% polyethylene terephthalate/cotton terephthalate/cotton blcnd oxford containing blend oxford containing Experiment Additional fabric processing steps highly Shrinkable normally shrinkable N0, polyethylene terephthalate polyethylene terephthalate fibers fibers Filling 1 Width (in.) Filling 1 Width (in.)

1 Singeing 1 1 46 2 Singeing, padding softener, brushing.. 4 43% 3 47 3-.- Singeiug, padding resin, hot calender- 2 41% 1 44% ing, curing. 4 Singeing, padding resin, hot calender- 2 41% 1 44 ing, curing, brushing. 5 Singeing, silk calendaring, padding 4 42% 1 4 resin, brushing, curing. 6 Singeing, padding softener, brushing 3 44% 2-3 47 1 Brush and sponge, after washing of fabric.

black and polyester orange) to facilitate identification of fiber components and thus determine fiber migration. Comparison of the cross-dyed fabric samples will show the fabric to become darker in color as the polyester yarn is selectively cored and to become still darker in color as residual polyester is signed from the surface and even darker as the cotton (or other black-dyed cellulosic is brushed to the surface; comparison of yarn samples at these various stages will confirm that polyester is selectively cored and removed from the yarn surfaces and that cellulosic is selectively raised to the yarn surface. By dissolving cotton from a sample of the fabric before heat setting and dissolving cotton from another sample of the same fabric after heat setting and by comparison of the polyester shades of the two samples, which shows them to be the same, it is confirmed that the observed shade changes in the blend fabrics upon heat setting are due to selective coring of the polyester rather than heat-induced migration of the dye.

The term restrained heat setting as used in the present specification and claims means heat setting of the fabric while it is laterally restrained against shrinkage. Restraining may be accomplished by use of a tenter frame (pin or clip or any other type), pinch rolls or any other conventional means for laterally restraining fabric. When the fabric contains normally shrinkable polyester, it is preferred that the lateral restraining during heat setting constitute maintaining the fabric at its initial (i.e., pre-heat setting) lateral dimension or at lateral dimension of up to about 5% in excess thereof; preferably, the lateral dimension of the fabric is maintained at about It is thus apparent that a highly shrinkable polyestercontaining blend will tend to demonstrate greater pilling resistance than an identically processed normally shrinkable polyester-containing blend. This apparently is because the coring effect in the former is greater than in the latter yarns. Highly shrinkable polyester means polyester filaments which have not been conventionally heat set during their manufacture and thus will shrink in boiling water substantially more than the 10-l2% which is typical of conventionally heat set, i.e., normally shrinkable, polyester.

The following table (Table II) shows the effect of shrink-proofing ("Sanforize process) preceded or not by mercerization on pilling performance. The fabrics tested in each of these experiments are oxfords each having a warp of 88 ends/inch of 50/ ls of 30 turns/inch Z-twist 35/ polyethylene terephthalate/cotton yarn. Under the heading Filling Yarn, px. means picks/inch and P/ C means polyester/ cotton blend yarn. Under the heading Pilling Test, B & S means 12 minute duration Brush & Sponge Test and RT means 30 minute duration Random Tumble test. The headings Original" and Washed mean, respectively, that the fabric was not washed after being processed and before being tested and that the fabric was so washed. The fabric processing steps are, of course, listed inchronological order.

Prior to the performance of the listed processing steps, each fabric in each experiment was heat set while laterally restrained against shrinkage at 415 F. for 20 seconds. Each singeing and resingeing was performed at an Industrial Heat Engineering Singer Setting of Flame 6, Speed 10.

TABLE II Singed and resin Singed, resin finished Singed, resin finished, Mercerized, singed and finished and shrink-prooied reslnged and shrinkshrink-prooted Filling Yam 1 Pilling test proofed Original Washed Original Washed Original Washed Original Washed 46 px., /1s 65/35% PIC; polyester is 1.5 B & S 2 2 3 3 2 1 1 1 denier x 1 sta is. RT 5 2 5 5 1-3 1 1 5 46 px., 30/2s 50/509 P/C; polyester is 1.5 B & S 3-4 3 3 4 1 2 3 3 denier x 1% stop RT- 5 5 5 5 5 5 H 5 46 px., 1.5/1's (ES/35% P/C; polyester is 3.0 B & 1 2 4 4 1 1 1 1 denier x 1, 4 staple. RT 5 5 5 5 5 5 3 5-4 1 In each fabric, warp yarn is 50/ls 30 turnslinchZ twist, 65/35% PIC.

The following table (Table III) shows the effect of mercerization on pilling performance. The mercerization consisted of caustic impregnation (4852 TW. concentration) of the fabric on a pad, removal of excess caustic by squeezing, holding the fabric under filling tension on a tenter clip frame and partially washing out the caustic from the fabric while under tension, and completing of washing of the fabric in a 6-box open width washer with neutralization of the fabric in the last box. Prior to the steps listed in the table, each fabric was heat set at 400 F. for seconds while laterally restrained against shrinkage, brushed two times on each side with a soft steel bristle brush roll and singed at an Industrial Heat Engineering Singer Setting of Flame 6, Speed 10. In the table, the fabric tested is a gabardine having a warp of 132 ends/inch and a fill of 72 picks/inch each of ls of Z-twisted 65/ polyethylene terephthalate/ cotton yarn.

TABLE III Random tumble Elmendorf Additional processing steps pilling test tear test (lbs.)

30 min. 60 min. Warp Fill Mercerized and finished 4 34 4. 0 2. 9 Finished only 4-5 4 4. 5 2. 8

The following table (Table IV) sets forth pilling and strength data for the fabric produced in each of the Examples I to IV, above.

With the processes of the present invention it is now possible to produce pilling-resistant polyester/cellulosic or polyester/wool fiber flannels, sleepwear lawns, soft oxfords for womens wear, suiting fabrics with an all woollike hand and the like.

It will, of course, be understood that the above exampies and tables are not limitative but merely illustrative of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Method of producing soft, pilling-resistant fabric of blend yarn comprising polyester staple fibers and fibers selected from the group consisting of cellulosics. and wool comprising the steps of restraining the fabric and heating said restrained fabric whereby the polyester staple fibers shrink and migrate to the center of the yarn.

2. The method of claim 1, wherein said selected fibers comprise a cellulosic.

3. The method of claim 1, wherein said selected fibers comprise wool.

4. The method of claim 2, wherein said cellulosic comprises cotton.

5. The method of claim 1, wherein the fabric is dyed prior to said restraining and heating steps.

6. The method of claim 1, wherein after said restraining and heating steps the fabric is singed so as to remove residual polyester fibers from the surface thereof.

7. The method of claim 6, wherein after the singeing step the fabric is brushed in order to raise additional selected fibers to the surface thereof.

8. The method of claim 1, wherein said heating step is at a temperature in the range of from about 325 to about 425 F.

9. The method of claim 7, wherein lubricant is. incorporated with the fabric thereby to facilitate the raising of the selected fibers.

10. The method of claim 9, wherein moisture is applied to serve as lubricant.

11. The method of claim 10, wherein the moisture application is accomplished by feeding steam through a pipe attachment to the brushes.

12. Method of producing soft, pilling resistant fabric of blend yarn comprising polyester fibers and fibers selected from the group consisting of cellulosics and wool comprising the steps of restraining the fabric, heating said restrained fabric whereby the polyester staple fibers shrink and migrate to the center of the yarn, applying an aqueous composition to said fabric, drying said aqueous composition containing fabric to a moisture content of from about 1 to about 10% based on the weight of the dry fabric, applying lubricant to said dried fabric thereby to facilitate the subsequent raising of the selected fibers, and brushing said lubricant-containing fabric thereby to raise additional selected fibers to the surface thereof.

13. The method of claim 12, wherein said selected fibers comprise a cellulosic.

14. The method of claim 12, wherein said selected fibers comprise wool.

15. The method of claim 13, wherein said cellulosic comprises cotton.

16. The method of claim 12, wherein said aqueous composition comprises brushing softener.

17. The method of claim 12, wherein said aqueous composition comprises finishing resin.

18. The method of claim 12, wherein said aqueous composition comprises finishing resin and brushing softener.

19. The method of claim 12, wherein said heating step is at a temperature of from about 325 to about 425 F.

References Cited UNITED STATES PATENTS 2,897,042 7/1959 Heils 57-140 X 3,006,055 10/1961 Chapin 2619 3,060,551 10/ 1962 Bogaty et al. 28--76 X 3,279,163 10/1966 Lulay et a1 57-140 FOREIGN PATENTS 133,874 8/ 1949 Australia. 466,070 6/ 1950 Canada.

LOUIS K. RIMRODT, Primary Examiner.