US3415051A - Piece-dyeable carpet and yarns therefor - Google Patents

Description

United States Patent 3,415,051 PIECE-DYEABLE CARPET AND YARNS THEREFOR Raymond Adrian Levesque, Stamford, and Richard Cecil Newton, Norwalk, Conn., assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Apr. 13, 1966, Ser. No. 542,223

8 Claims. (Cl. 57-140) ABSTRACT OF THE DISCLOSURE Piece-dyeable carpets of acrylonitrile polymer fibers and yarns for making such carpets are provided wherein such yarns are composed of bicomponent fibers of acrylonitrile polymer, the components of which have a shrinkage ditferential of -20% and substantially the same hydrophilic properties, the yarn developing in water at 200 C. a compression bulk of at least 6.0 cc./ g. under a load of 18 g./inch of yarn and/or a specific bulk of at least 7.0 cc./ g.

This invention relates to a method of making piece-dyeable carpet fabrics from yarns prepared from bicomponent fibers of acrylonitrile polymers. It relates further to the process of dyeing such carpet fabrics whereby the carpet fabric develops high bulk under hot-wet dyeing conditions and retains its bulk after being removed from the dyebath and dried. It relates further to the new carpet fabrics having the foregoing properties. Still further, it relates to the yarns used to prepare the said new carpet fabrics.

It is a well-known fact that bulky carpet fabrics provide covering power and a luxurious feel not found with carpet fabrics of the same material and weight, but with less bulk. The desirable property of bulkiness results from crimping in the fiber that makes up the carpet yarn. Crimped fibers cannot lay together as closely as the same fibers without crimp, and thus they stand apart from each other with the result that they occupy a relatively large amount of space. Acrylic yarns have been designed to have high bulk, and they have been used in carpet fabrics. However, there has been no satisfactory way to dye the fibers once they have been woven into a carpet since during the hot-wet dyeing operation conventionally used fibers tend to lose their crimp (i.e., they tend to lean out); the yarns consequently tend to lose bulk. Also, the carpet tufts tend to lean over and mat down (i.e., they tend to develop a condition known as pile lay). Furthermore, through loss of crimp or by failure to develop crimp,

the weakly-held fibers are easily pulled out under the tension and abrasive action concountered by the carpet when it is dipped in and out of the dyebath, resulting in a fuzzy carpet surface. While the fuzz can be sheared from a carpet having a single level pile or the top level of a multi-level pile, it cannot be sheared from the lower levels of a multilevel pile. All these phenomena result in a loss of value. These effects can be minimized, but only by costly special carpet constructions or elaborate post-dyeing procedures, e.g., jet steaming, back-beating, shearing, etc. In practice, all dyeing has been done either on the fiber itself (i.e. stock dyeing) or on the unwoven yarn (skein dyeing).

Both skein and stock dyeing involve some difficulties which would be desirably avoided, but unfortunately cannot be. In both processes an inventory of dyed fiber or yarn must be maintained for each carpet color in the manufacturers line.

In view of these difficulties in the manufacture of acrylic carpet fabrics, it is an object of this invention to provide a commercially feasible method for the production of a 3,415,05 l Patented. Dec. 1 0, 1 968 piece-dyeable carpet which does not require special carpet construction or expensive post-dyeing procedures for pile restoration, development of bulk and elimination of fuzz. An additional object is to produce a carpet which does not lose value during the piece-dyeing step. Still another object is to produce a piece-dyed carpet with reduced fuzz. A still further object is to produce a piece-dyeable, multilevel pile carpet. Still another object is to produce a piecedyed carpet with improved firmness and little lean out or pile lay and high bulk and covering power. Yet another object is to provide a yarn suitable for the production of such carpets. Other objects will be apparent from the ensuing description of this invention.

In accordance with the present invention, these objects are achieved by providing a carpet fabric tufted of low twisted yarn composed of bicomponent fibers of acrylonitrile polymer whose monocomponent parts have substantially the same swelling potential, shrink 5 20% differentially, and develop under the conditions of hot-wet dyeing in a high degree of essentially irreversible and dimensionally stable crimp. Little or no further crimp is developed upon drying and the crimp is substantially permanent to subsequent hot-wet treatments. This characteristic is for convenience referred to as irreversible crimp. Due to the self-crimping nature of these fibers, yarns comprised of such fibers develop a high degree of bulk which generally results in a yarn contraction of 10 to 40% during the dyeing step.

It is essential to the invention that all components of the composite fiber possess nearly comparable hydrophilic properties, i.e., the components must possess nearly comparable longitudinal and low radical swellabilities.

Fibers of the irreversible crimp type should not be confused with fibers of the reversible crimp type. Illustrative of reversible crimp fibers are those disclosed and claimed in U.S. Patent No. 3,038,236 and the rayon fibers in U.S. Patent No. 2,439,815. Illustrative of irreversible crimp fibers are those disclosed generally in U.S. Patents Nos. 2,439,815 (column 2 line 41 et seq.) and 3,182,106 as well as sample (B) of Example VI of U.S. Patent No. 3,038,236. It is noted above and has been found that such reversible crimp fibers cannot provide the advantages of the present invention since they develop most of their crimp only upon drying. Thus, in piece-dyeing carpets, fibers having reversible crimp will not crimp to a high degree when hot and wet; and the carpet is consequently beset with problems of pile lay, lean out and fuzz. The yarns of the present invention must develop during the dyeing step or other hot-wet processing to which the carpet fabric is exposed a specific bulk of at least 7.0 cc./ g. and/ or a compression of at least 6.0 cc./ g.

By the term specific bulk is meant the volume to weight ratio of a dry yarn as determined by the following test at room temperature, hereinafter referred to as Test (A):

BULK TEST A A cm. length of yarn is weighed and its diameter measured with a vertically counted Federal C8lS thickness gauge. Ten thickness readings along the length of a yarn sample are taken by raising the pressure foot /8 inch above the yarn surface and allowing it to drop onto the yarn. The specific bulk is then calculated by the following equation:

i Specific bulk 1n cm. /g.-- 4M D=yarn diameter in cm. M =weight of yarn in grams L=length of yarn in cm.

While the specific Bulk Test A above is a useful measurement of yarn bulk under constant load, the following compression bulk test (Test B) can be used to measure A yarn sample is placed between two circular plates each having a diameter of 1 inch. One plate is connected to a micrometer which measures the distance between the plates while the other plate in connected to a load cell which measures the force on the sample between the plates. A simultaneous record of plate separation and associated forces can, therefore, be displayed on an X-Y recorder. The bulk can be calculated at different loads from the plate separation by the following:

d=distance in cm. between plates tex=weight of yarn in gms./ 1000 meters.

Compression bulk= Yarn shrinkage is measured as the difference in length of a single end of yarn with a load of 0.001 g./denier prior to and following exposure to boiling water for 30 minutes. The water is cooled to 120 F., then the yarn is removed and air dried. The measurement may be expressed as:

Percent shrinkage:

original length-resultant lengthX 100 original length Fibers of acrylonitrile polymer which will develop irreversible crimp may be obtained by co-spinning, side by side, two or more polymers of acrylonitrile of nearly identical swelling potential but of different comonomer proportions, each polymer containing at least 70% acrylonitrile. The components of the bicomponent fiber useful for the practice of the present invention have a differential shrinkage of about 5% to about 20%, and preferably of about to about This means that one component will have a greater loss of original length upon shrinking than the other component by these amounts. This shrinkage ditferential induces a crimp in the composite filament. Too low a shrinkage differential results in a yarn which does not develop enough compression bulk to piece-dye satisfactorily. Too high a shrinkage differential results in a yarn which has a harsh hand. Also, a high shrinkage differential gives a high yarn shrinkage which, if too high, cannot be accommodated with existing carpet tufting equipment.

By polymer of acrylonitrile is meant a polymer composition which contains an average of at least about 70% acrylonitrile in the polymer molecules. When acrylonitrile is not homopolymerized, the remainder of the polymer molecules may contain an average of up to about 30% of another ethylenically unsaturated material as is well known in the art. Illustrative of these other compounds which may be copolymerized with acrylonitrile to form polymers which can be used in the practice of the present invention are those which may be found, for example, in US. Patent 3,104,938, issued Sept. 24, 1963, and US. Patent 3,040,008, issued June 19, 1962, and in the various other United States patents mentioned therein.

The individual bicomponent fibers used in the piecedyeable carpet fabric of this invention resemble helical springs when viewed under a microscope. The coils of this spring will be in one direction for several coils and then in the other direction for several coils. These reversals, seen throughout the fiber length, are caused by restraints when the fiber crimp is developed and are believed to provide a higher yarn bulk than in fiber with a symmetrical helical shape. It may be visualized that this configuration will resist deformation in any lateral direction unlike a fiber hving only co-planar crimp.

To practice the present invention, bicomponent fiber of the type defined above is stretched at a temperature required to temporarily remove the helical crimp and is cooled under tension. After the fiber is mechanically crimped to give it co-planar bale crimp, it is cut into staple and converted to carpet yarn. The yarn is of relatively low bulk at this stage since the fibers therein do not exhibit their latent helical crimp. The yarn is converted into carpet fabric and then dyed.

The aqueous dyebath containing conventional acrylic dye must be at a temperature between about 180 and 270 F. While in the dyebath, the bale crimp disappears. The latent helical crimp is developed and the yarn in the carpet fabric becomes bulky. Intrinsic crimping forces are only slightly nullified by the tension involved in transporting the carpet in and out of the dyebath. The wet dyed carpet fabric is then dried conventionally.

The dyed carpet fabric thus produced, even without elaborate post-dyeing treatment, will be observed to be high in value in that it is of high bulk as compared to conventional carpet fabric of the same weight. It will have very little surface fuzz, will be substantially free of pile lay or lean out, and in multi-level carpets, it will be free of fuzz on the lower levels as well.

It will be recognized, therefore, that great benefits are realized through the use of yarns of irreversibly selfcrimping bicomponent fibers of acrylonitrile polymers, which yarns develop bulk in hot water under tensions imposed by piece-dyeing, as described above.

While the present invention has been described and will be exemplified in terms of carpeting and yarn made of irreversibly self-crimping bicomponent fibers, it will be understood that it also includes the preparation of carpeting from yarns containing minor amounts of other fibers, e.g., monocomponent acrylic fibers, squirming bicomponent fibers, wool, nylon, etc. Likewise, while it is preferred to allow the hot-wet conditions incident to the dyeing operation to develop the bulk of the carpet yarn of the present invention, it will be understood that this invention also comprehends an operation whereby the carpet fabric is pre-bulked before dyeing. This prebulking operation can be accomplished by exposure to either hot-wet or hot-dry conditions at any time prior to the dyeing operation. The carpet material with its predeveloped bulk may then be dyed by conventional means.

In the following examples presented to illustrate the present invention, some properties of carpet fabric are determined by measurements on the yarns and fibers contained therein and other properties are determined by measurements on the carpets themselves.

Example 1 Two spinning solutions A and B were formed as follows:

Component Solution A Solution B N aCN S 40 parts 40 parts. Water 48.8 parts 48.8 parts. Acrylomtrrle/methyl- 11.2 parts of 89.2/10.8 11.2 parts of 91.7/8.3

methacrylate copolymer. copolymer. copolymer.

In a manner similar to that disclosed in commonly assigned copending application No. 249,203, filed Jan. 3, 1963, spinning solutions A and B were metered separately, but concurrently side by side through each hole of a spinnerette, at a weight ratio of 72 parts of solution A to 28 parts of solution B, into a sodium thiocyanate coagulating bath to form bicomponent filaments. The filaments were washed, stretched to 10 times their length and dried. These composite fibers were further subjected to steam under pressure at a temperature of 270 F. and allowed to shrink 40% of their stretched length. The resultant high degree of crimp was removed by restretching the fibers in a hot 1% aqueous solution of an antistatic-lubricating textile aid, by the minimum amount sufficient to just remove said crimp. Minimum temperatures required to remove the crimp without damage to the fiber were used. The straightened fibers were mechanically crimped, dried and cut into 4 inch staple.

A sample of these staple fibers was exposed to water at the boil and dried. The dried fiber had a crimp frequency of 14.7 crimps per inch (c.p.i.) as compared to only 3.0 c.p.i. for the mechanically crimped fiber before exposure. Fiber shrinkage was 4.9% and fiber contraction (i.e., total change in length due to fiber shrinkage and crimp development) was 20.0%.

The mechanically crimped, undeveloped, staple fibers were processed into 2 ply 50s (Philadelphia count) greige carpet yarn of 4.0 t.p.i. (twists per inch) in singles and 2.5 t.p.i. in the plied yarn. The yarn had a specific bulk of 6.0 cm. g. After a sample of this yarn was immersed in boiling water and then dried, it had a specific bulk of 12.8 cm. /g. and had shrunk 25.0%.

Multilevel pile carpet was made from the greige yarn and piece-dyed in equipment commercially used for piecedyeing nylon carpet at 208 F. to 212 F. for 2%. hours followed directly by drying at 250 to 290 F. without jet-steaming, back-beating, shearing or any other special procedures. Examination of the dyed carpet before and after drying indicated that in both cases the tufts were erect and pattern definition was excellent. There was substantially no pile lay, no lean out, very little fuzz at any level and the carpet had a pleasant, firm hand which gave the impression of containing more fiber than a comparable weight stock-dyed acrylic carpet. There was no loss of value.

Example 2 A bicomponent fiber was prepared as in Example 1 from 50 parts of solution A and 50 parts of Solution C of the following composition:

Solution C Parts NaCNS 40 Water 48.8

Polymer of 94/6 acrylonitrile-methylmethacrylate 11.2

A sample of the mechanically crimped fiber having 7.0 c.p.i. was immersed in boiling water and dried. After drying, it was found to have 15.5 c.p.i. Fiber shrinkage was 12.3% and fiber contraction was 41.2%.

The remainder of the fibers were processed into yarn as in Example 1. It had a specific bulk of 3.5 cm. g. A sample of the yarn was immersed in boiling water and then dryed. It had a specific bulk of 8.5 cm. g. and had shrunk 30% The remainder of this yarn was tufted into carpet fabric and dyed as in Example 1. Examination of the dyed carpet fabric indicated substantially no pile lay, no lean out and very little fuzz at any level. Again, there was no loss of value.

Example 3 Spinning solution A was extruded through a spinnerette into an aqueous sodium thiocyanate coagulating medium to form monocomponent filaments. The filaments were washed to further remove the solvent, stretched to ten times their extruded length, and then dried. The denier of the stretched fibers before drying was approximately denier per filament. These fibers are identified as fiber 3A. Monocomponent fibers were spun under identical conditions from spinning solution B. These fibers are identified as fiber 3B. In a like manner, monocomponent fibers (identified as fiber 3C) were spun from a spinning solution C.

The dried fibers 3A, 3B and 30, in a relaxed, unrestrained condition, were then steamed under pressure at temperatures in the range of 240 to 270 F. The amount of fiber shrinkage in each case at 10 increments over this temperature range is shown in Table I. Shrinkage was calculated as the stretched length of the fibers minus the final relaxed fiber length divided by the final fiber length.

TABLE I Shrinkage (Percent) Fiber 240 F. 250 F. 260 F. 270 F.

3A 28 31. 5 36. 0 44 3B 32 32. 5 33.0 34 3C 23. 5 23. 7 23. 9 24. 2

TABLE IL-CRIMP FREQUENCY AND FIBER SHRINKAGE OF FIBERS 3A, 313 AND 30 Property Before boil-011 After boil-0h (measured dry) Crimp frequency 8. 0 3. 0 Fiber shrinkage 2. 0

Each of the fibers was spun into 2-ply 50s resultant count carpet yarn of 4.0 x 2.5 twist. The resultant yarn count is the count (on the worsted system using Philadelphia counts) of the fiber after boiling, the yarn being originally spun to a lower count. Again, these yarns had approximately the same properties with respect to specific bulk and yarn shrinkage as shown in the following table.

TABLE IIL-SIEOIFIC BULK AND YARN SHRINKAGE OF FIBERS 3A, 313 AND 30 Property Before boil-off After boilmf (measured dry) Specific bulk i 3. 3 4. 0 Yarn shrinkage at .001 g./den 6. O

Yarn 3A was tufted into 32 oz./yd. commercial multilevel W and A carpets and piece-dyed in rope form in a dye beck at 200 to 210 F. An evaluation of the finished carpet showed severe lean-out, pile lay and considerable surface fuzz in the lower levels of the carpet.

In another test, when the carpets were subjected to the post-dyeing measures of jet steaming and back-beating to restore the pile and were then sheared to remove surface fuzz, the deficiencies noted above were somewhat diminished, but the carpet was still unsatisfactory and showed loss of value.

Example 4 The following experiment was conducted to demonstrate the piece-dyeing technique as applied to a carpet prepared from producers high bulk yarn. Producers high bulk yarns are a blend of high-shrinkage and low shrinkage staple fibers.

Fiber 3A prepared from spinning solution A described in Example 3 was restretched 1.3 times its shrunken length in 180 F. water prior to crimping and staple cutting, thereby imparting a potential shrinkage of 23% upon reexposure to 200 F. water. A staple blend of fibers containing 40% of the stretched fiber thus prepared and 60% of unstretched fiber 3A was made into 2-ply 50s resultant count carpet yarn as shown in Example 3. The resulting yarn had the following properties:

TABLE IV.SPECIFIC BULK AND YARN CONTRACTION OF PRODUCERS HIGH HULK It will be noted that the producers high bulk yarn developed a high degree of bulk after shrinking the untufted yarn in hot water.

The unbulked producers high bulk yarn of this example was tufted into carpets and dyed as in Example 3, employing post-dyeing corrective procedures designed to restore the tufts to an erect position and toeliminate fuzz. The carpet exhibited fair bulk and cover and very little lean-out. However, it had excessive fuzz on the lower level of the pile. The carpet had a loss of value and a gard as compared to the other yarns tested. This test, therefore, shows the superiority of the yarns of the present invention over the range of forces incurred during piece dyeing.

While the foregoing examples have illustrated embodiments of the present invention whereby bulk development has been accomplished under hot-wet conditions, it should be understood that the yarns f the present invention develop bulk under hot-dry conditions as Well. Bulk developed this way is stable to subsequent hot-wet treat- 0 mushy hand mdlcatlng a lack of firmness. ments and therefore is further resistant to loss by subse- When the carpeting prepared above and dyed by the quent dyeing operations in the same manner and to the piece-dyeing method was not subjected to post-dyeing same extent as the yarns of Examples 1 and 2. corrective procedures, the piece-dyed carpet was matted, Moreover, though the foregoing examples have illusdue to pile lay. There was very little bulk or cover and 5 trated the improvement of the present invention whereby the lean-out was excessive. bulk development and dyeing were accomplished simultaneously in a dye bath, it should be understood that these Example 5 two operations can be accomplished separately. Thus, the Thls example demohstrates the dlfferhce P carpet of the yarn of the present invention may be sub SI1 bulk Vah1e f VaFIPUS yp of lf Yearnsl lfichld' jected to hot-dry conditions or hot-wet conditions not conlflg y 0f thls lhventlOIl P p as In p h 1 and nected with the dyeing operation to thereby produce an Y Prepared from mohocomphheht acryhc fiber undyed carpet with developed bulk. The latter may then (the yarn of Example 3); producers high bulk yarns (the be dyed by conventional means. yarns of Example 4); and yarns prepared from Orlon We claim; 33 acrylic fiber. The latter fiber is a blend of bicomponent A yarn composed f bicomponent fib f acwlofiber Wlth reverebh? crimp and moeoqomponqntjiber and nitrile polymer, the COInpOIlCnts of which have a shrinkhas bean reported 111 Fhl'hlshlh gs l y of June age differential of 520% and substantially the same 17, 1965, to be useful in makmg comer cially p1ece-dyeable h d hili Properties, the yam devfiloping in Water at Carpets feqlllhlng p f restoratlvc p h 200 F. a compression bulk of at least 6.0 cc./ g. measbulk and Shrlnkage Propeftles 0f the 0f10h 33 acryhc ured under a load of 18 g./inch of yarn, said compression Yarns are as fhhows: bulk being maintainable at a level of at least 6.0 cc./g. TABLE V.SPEOIFIG BULK AND YARN SHRINKAGE OF when sublectfld t0 the forces imposed y repeated pp ORLON 33 of the yarn 1n water at 200 F. Property Before boibofi Afte b iL fi 2. A yarn composed of bicomponent fibers of acrylo- (p 35 nitrile polymer, the components of which have a shrink- Specific bulk 7, 5 age differential of 5-20% and substantially the same Yarnshrinkage 11 hydrophilic properties, the yarn developing in water at 200 F. a specific bulk of at least 7.0 cc./ g. The yarns of Examples 1 through 4 and Orlon 33 3. A piece-dyeable carpet fabric prepared from the acrylic yarn were exposed to a series of wetting and dryyarn of claim 1. ing treatments which simulate piece-dyeing operations. 4. A piece-dyeable carpet fabric prepared from the These treatments are (1) exposure to 200 F. water for yarn of claim 2. 5 minutes followed by (2) dipping in and out of 200 F. 5. Dyed yarn prepared from bicomponent fibers of water (minimum time lapse) followed by (3) drying at acrylonitrile polymer, the fibers being characterized by temperatures up to 200 F. for 15 minutes. Tumble drying an irreversible helical crimp, said yarn having a comwas used to simulate back-beating, a post-dyeing restorapression bulk of at least 6.0 cc./ g. measured under a load tive procedure. The compression 'bulk of the yarn under of 18 g./inch of yarn, said compression bulk remaining increasing compressional forces was measured while the at a level of at least 6.0 cc./ g. after being subjected to yarn was in the wet state and after it had been air dried or the forces imposed by repeated dipping in water at 200 F. tumble dried. These values are given in the following 6. Dyed yarn prepared from bicomponent fibers of table: acrylonitrile polymer, the fibers being characterized by an TABLE VI Original Static 5 min. Dipping 5X in 200 F. water Fiber sample Compression yarn bulk, in 200 F.

load, g./in. ce./g. water wet bulk Wet bulk Air dried 250 F. tumble bulk dried bulk Example 1 (this invention) 3. 0 10.7 10. 5 15. 7 10.0 8.6 8.5 11.0 18.0 7.5 7.3 9.2 Example 2 (this invention) 3. 0 10. 6 10. 5 16. 3 10.0 9.0 9.1 11.0 18.0 7.7 8.0 10.1 Example 3, Fiber 3A 3. 0 8. 5 8.0 10.8 10.0 5.2 5.8 6.5 18.0 5.3 4.9 5.3 Example 4 (producers high bulk) 3. 0 10.5 9.1 18. 5 10.0 0.3 5.3 9.2 18.0 4.6 4.5 5.2 0r1on 33 acrylic fiber. 3.0 8. 5 12. 1 19. 0 10.0 5.6 7.8 13.4 18.0 4.9 5.8 10.3

The foregoing data clearly show that the yarns of the present invention develop bulk in hot water and are able to retain the bulk despite the presence of increasing compressional forces both while the yarn is in the wet state and after it has been air dried. The yarns of the present invention are shown to be definitely superior in this reirreversible helical crimp, said yarn having a specific bulk of at least 7.0 cc./ g. after exposure to water at 200 F.

7. Carpets prepared from the yarn of claim 5. 8. Carpets prepared from the yarn of claim 6.

(References on following page) 9 10 References Cited 3,225,534 12/1965 Knospe 2- 57-140 3,330,896 7/1967 Fujita et 211. 57140 UNITED STATES PATENTS 4/1961 Waltz 57-1 40 5 STANLEY N. GILREATTI, Przmary .Exammer. 5/1961 Weldon 57 140 XR W. H. SCHROEDER, Assistant Exammer.

3/1963 Evans 57-140 5 CL 5/1965 Tanner 57140 XR 2872, 75