US3298079A

US3298079A - Method for producing a novel crimped yarn and fabric

Info

Publication number: US3298079A
Application number: US458354A
Authority: US
Inventors: Albert H Agett; Jr William L Aspy
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1965-05-24
Filing date: 1965-05-24
Publication date: 1967-01-17
Anticipated expiration: 1984-01-17

Description

.Jan. 17, 1967 A. H. AGETT ETAL 3,298,079

METHOD FOR PRODUCING A NOVEL CRIMPED YARN AND FABRIC Filed May 24, 1965 2 Sheets-Sheet 1 THIS INVEN'HON FIG. I.

PRIOR ART FIG. 3.

ALBERT H. AGETT INVENTORS Y QMM ATTORNEYS WILLIAM L. ASPY 3Y2 Jan. 17, 1967 Filed May 24. 1965 TOW FROM SPINNING CABINETS SPECIFIC VOLUME-CUBIC INCHES PER LB.

A. H. AGETT ETAL 3,298,079

METHOD FOR PRODUCING A NOVEL CRIMPED YARN AND FABRIC 3 Sheets-Sheet 2 PREHEAT ROLL SECOND DRAFT ROLL FIRST DRAFT 28 ROLL THIRD DRAFT ROLL UNBULKED BULKED BY HEAT TREATMENT PRIOR ART HIGH SHRINK HIGH SHRINK INVENTORS MODACRYLIC UNMODIFIED MODACRYLIC Q I YARN POLYACRYLO- YARN BY W NITRILE YARN 7W ATTORNEYS WILLIAM L. ASPY United States Patent M 3,298,079 METHUD FOR PRGDUCING A NOVEL CRIMPED YARN AND FABRIC Albert H. Agett and William L. Aspy, J12, both of Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed May 24, 1965, Ser. No. 458,354 8 Claims. (Cl. 28-72) This is a continuation-in-part of Serial No. 150,320, filed November 6, 1961, now abandoned.

This invention relates to production of a bulky yarn and fabric. More particularly this invention concerns a drafting procedure for manufacture of a high-bulk yarn of high crimp retention and high crimp recovery adapted for use in fabrics exhibiting a shearling look or interlocking crimp.

A loopy, bulky surface texture is often highly desirable, particularly in synthetic fabrics and blends thereof with natural fibers such as cotton and wool, e.g., in items such as rugs and batting. Attempts have been made to prepare a fabric characterized by such a surface texture as well as a high degree of cover or backing hiding power and Wearability, but thus far all such attempts have fallen short of a way of obtaining a combination of all of these desirable features in the same fabric. Therefore it is apparent that the develop-ment of a process for producing yarn adapted for the manufacture of fabrics which will have the desired 'bulkiness or fluffiness, high crimp retention, high crimp recovery, high cover, and capability of forming wavelike loops in what may be described as a shearling or interlocking-crimp effect represents a highly desirable result. As is known in the rug industry, there is a need for carpet yarn which will provide more cover or degree of hiding of the backing with the same or less weight of yarn and the ability to form an interlocking or quasi S-shaped parallelized-fiber appearance of high crimp retention and high crimp recovery. After extended investigation we have discovered a simple and economic way to manufacture such a yarn and fabric prepared therefrom.

This invention has for one object to produce a nonwoven fabric containing a bulky, loopy and fluffy yarn of high cover. Another object is to provide a process and apparatus especially adapted for producing manmade fibers capable of being formed into a non-Woven fabric containing yarn that has good cover, increased strength, high crimp recovery and high crimp retention. A further object is to provide a yarn production method comprising successive steps of drafting, crimping, heatsetting and forming filaments into a yarn of high crimp retention and high crimp recovery after heat treatment. Still another object is to provide a process and apparatus for producing high-bulk yarn wherein the filaments are stretched with a relaxing step prior to crimping and thus enabled to be crimped under relatively mild conditions in such a way that a high-shrink yarn of high crimp retention and high crimp recovery is obtained after a heatsetting operation. Other objects will appear hereinafter.

As indicated above, it is highly desirable to produce fibers of high cover for a small weight, particularly when a bulky or loopy material such as used in the production of rugs and similar products is desired. Prior-art methods at least about 100 cu. in./lb. after heat treatment.

3,298,079 Patented Jan. 17, 1967 of producing such fiuffable fibers involve crimping operations which inherently decrease the strength of the fibers and thus make them incapable of forming the highly desirable lasting hand and appearance in the finished piece. Conventional methods of lofting, entangling individual fibers with one another and crimping generally tend to decrease the strength and durability of the fluffy highcover yarn desired by the trade.

After extended investigation We have found an apparatus arrangement and method whereby the preceding difliculties may be substantially overcome and a yarn of 2-24 denier per filament, preferably 816 denier per filament, greater than 12% crimp retention, and a specific volume of greater than 100 cu. inches per pound is obtained. We have also found a method and apparatus for manufacturing pile carpet, the pile or yarn in which is characterized by high bulk, high crimp retention and a substantially parallel fiber arrangement wherein the yarn ends are interlooped in a snake-like or S-like tortuous path in such a way as to exhibit a permanent nub, all these characteristics resulting from heat treatment, preferably by steaming of said carpet. By high bulk We mean a specific volume of The yarn of our invention is adapted for formation of fabric blends of natural and man-made fibers which exhibit these same highly desirable characteristics. In a preferred embodiment of the process and apparatus of this invention a high bulk yarn is obtained by imparting a the filaments are drafted to from about 100% to about 850% or above), with a relaxing step in which the draft ratio is less than about 1, preferably about 0.8 to 0.9. The relaxing step is preferably the third step of a three-step drafting procedure. The fiber produced has a shrinkage or shrinkability of 25'75% or higher after drafting and before further processing.

By increasing the pressure in the crimping zone we produce a high crimp in the fiber which, even though removed by a certain amount of mechanical stretching during the subsequent carding and spinning operations, is re developed by a subsequent heat treatment which may consist of steaming, treating with hot water, heating in an oven or piece dyeing, for example, This heat treatment is characteristic of all embodiment of our invention. The crimping may be improved by guiding the continuous filament tow to the crimping zone by passing over and under a series of guide rolls and providing a widthadjustment arrangement whereby the tow is kept at a substantially uniform width and thickness upon entering the crimping zone. Alternatively, a clapper-gate pressurecontrolled mechanism may be set up whereby the crimping operation is made substantially self-continuing by allowing the tow to build up in the crimping zone in a manner such that sufiicient pressure is produced to cause it to be pushed out at the proper time in a uniform, high crimp form.

We have found that our novel operation may be successfully conducted both when continuous-filament yarn is produced and when the tow is cut into staple which is further processed by carding, drawing, and roving. The crimp may be recovered or restored and the high bulk imparted by heat treatment of the processed staple fibers or continuous filament tow (for example, with hot water, hot air, or steam) either before or after the yarn is tufted into a carpet or converted to a fabric.

We have found the method and apparatus herein described particularly useful on modacrylic fibers. These fibers are made from compositions consisting of, for example, 40-85% acrylonitrile modified with various modifiers and soluble in acetone and dimethyl formamide, for example. Further disclosure of such type of fibers will be had by reference to US. Patents 2,811,409, 2,831,826 and 2,843,572.

In producing non-woven fabrics from high-shrink or high-bulk yarn according to this invention, a more or less tenuous web of loosely associated textile-length fibers or mixture thereof disposed in sheet form may be produced by carding, garnetting, air-laying, or the like to form an oriented web or batting. In the carding operation Webs are made by-passing the fiber through a card or other appropriate device to form a web or sheet of loosely associated fibers. A plurality of the webs may then be superimposed to provide a laminated web weighing from about 100 to 5,000 grams per square yard. An oriented web may be converted into a fabric by bounding, e.g., impregnating the web with a bonding agent such as a natural or synthetic resin or spraying a plurality of webs with a suitable plasticizer (115%), e.g., dimethoxyethyl phthalate or triacetin for cellulose ester fibers, and then heating by passing between calendering rolls or through a curing oven.

When cut staple fibers are used in this invention, spinning systems such as worsted, American, and cotton which parallel the fibers result in the greatest bulkiness, although woolen system yarns may be prepared having a lower degree of bulk. The bulkiness may be developed by steaming, piece dyeing, or latex curing of the carpeting. The mild steaming used in prior-art carpet finishing is insufficient to develop a significant amount of bulk in the yarn. Latex curing at 115' C. or above will do an effective job of developing bulk. Piece dyeing or skein dyeing will develop the bulkiness completely. An excellent Saxony textured carpet can be made with modacrylic high-bulk yarn without the need for twist setting. When the carpet pile is steamed, the yarn ends form a permanent nub. Shearing of the pile then gives a Saxony effect which holds its texture very well in service and in cleaning. We have found that the desired degree of brightness or dullness of luster may be imparted to the yarn of this invention by blending bright fibers with dull fibers. When this is done, at least 70% bright fiber should ordinarily be used and preferably at least from 8590% bright. By our invention in addition to the highbulk, high-crimp retention and high-crimp recovery coupled with the permanent nub effect, an improved soil resistance is imparted to the yarn. When the product is carpeting, the back or backing suitably comprises jute, cotton, rayon, nylon, or other appropriate natural or synthetic fibers as desired. A rubber or latex coating may be applied on the back of the carpet.

For a more complete understanding of our invention reference is made to the attached drawing forming a part of the present application.

FIG. 1 is a diagrammatic vertical cross section through a carpet showing the pile and the back of a product made according to the present invention and a prior art product.

FIG. 2 is an enlarged view of the drafting portion of the process with the details of a preferred embodiment of the drafting operation set out.

&

FIG. 3 is a side elevation view of a crimping step and heat-setting arrangement which may be used in our invention.

FIG. 4 is a block graph comparing the bulked yarn prepared according to this invention with unbulked yarn.

In FIG. 1, in the prior art carpet, yarn ends 10 are sufficiently straight, shallow, and far enough apart for the backing 12 to be observed at some points by one looking downward from above, whereas in the carpet prepared from high bulk yarn produced using the drafting-relaxing procedure of this invention the yarn ends 14 are intermingled in a substantially parallel, interlooping or interlocking nodular arrangement in such a manner that the backing 16 is almost substantially concealed or covered, it being impossible to look downward between the individual ends, that is, see the backing 16 through the yarn ends 14. This is true regardless of whether a loop-pile or cut-pile carpet is used, the chief difference being that in the loop-pile arrangement, the yarn ends are continuous in the form of loops rather than being cut at appropriate places.

Referring now to FIG. 2, which represents a preferred embodiment of the drafting procedure of this invention, the tow 18 is passed from spinning cabinets under an idler roll 20 for about of its peripheral surface and then over and around a preheat roll 22, which may be heated by shoes or other conventional heating means (not shown). The tow should be in contact with the preheat roll 22 for at least 200 degrees of a circular path. It then passes over and around a first draft roll 24 moving at about 1.6 times faster than preheat roll 22 in order to provide the necessary tension for an initial drafting or stretching step. Again the tow should be in contact with at least 200 of a circular path while in contact with said first draft roll 24. Additional tension is then applied as the tow moves over a second draft roll 26. The tow should again move over greater than 200 of a circular surface. The tow is drafted between first draft roll 24 and second draft roll 26 an additional drafting or stretching of 3.0 to 4.1 more or less above the draft imposed between preheat roll 22 and the first draft roll 24. After leaving second draft roll 26 the tow continues around about 40% of the surface of a third draft roll 28 moving counterclockwise and opposite to the direction of second draft roll 26. An additional 1.1 to 1.3 draft may be applied between the second draft roll 26 and third draft roll 28.

Referring next to FIG. 3, in a crimping zone which may be used in our invention, a clapper gate is provided which is controlled by air cylinders in such a manner as to allow the tow to move through the crimping zone continuously and more or less unrestrictedly, the imparted crimp being substantially uniform. A plurality of strands of stretched yarn 30 after passing through yarn guide 35, which aligns the yarn to form a single sheet of parallel yarns, may be moistened by means of water or steam spray nozzles 34, which also control the temperature of the yarn, prior to being fed into a stulfer box crimper through the bight of feed rolls 36 and 38. The water may applied from a humidifier nozzle. Top feed roll 36 has a straight mechanical linkage (not indicated) to air cylinder 40, which is used to transmit pressure to the roll nip. Feed rolls 36 and 38 operate cooperatively, one being driven by the other either by gear or surface friction. The stuffer box crimper outlet 42 is restricted by a clapper gate 44 which is pivoted at point 46 and controlled from air cylinder 48. The untreated yarn 30, which is .in the form of a sheet, may pass through a vapor cloud produced by the vapor nozzles 34 prior to passing through the bight of the feed rolls 36, 38 and next into the st-uifer box crimping chamber formed between

walls

50 and 52. As the yarn passes from the feed rolls 36, 38 into the stutfer box defined by

walls

50 and 52, it is heated to semi-plasticity and further moistened by steam which is directed into the stuifer box through

inlets

54 and 56. The crimper clapper gate pressure should be less than about 30 p.s.i.g. and the steam pressure at least about 5 p.s.i.g The steam admitted through

inlets

54 and 56 also heats the

stuffer box walls

50, 52. This helps to keep the yarn in a semi-plastic state during treatment. The heated, moistened, semi-plastic yarn inside the stuffer box crimping chamber defined by

walls

50 and 52 accumulates and fills the crimping chamber in a configurated mass 58 which exerts a pressure on the clapper gate 44. When the mass pressure equals or exceeds the pressure produced by the air cylinder 48 operating on the clapper gate 44, the configurated yarn 60 then flows out of the stuifer box crimper restriction 42 to fall freely on a variable speed endless conveyor 64 and be carried through a drying or heat-setting chamber 66 in which the moist, hot yarn, now crimped and curled, is dried to a heat-set form 68 in a high amplitude, low frequency, crimped and curled state. The treated, heat-set, and dried yarn 68 upon leaving the heating chamber 66 may be removed from variable'speed endless conveyor 64 by means of a plurality of mechanical packaging devices such as parallel package winders 70. Packaging devices 70 could also be a beamer or a ball-warping apparatus or a baling device which would package a plurality of the yarns after treatment. The yarn could also be formed substantially directly into a non-woven yarn fabric, tufted into a carpet after plying and coning, or cut into staple fibers to be further processed.

It is sometimes helpful to apply a stream of air against the yarn 60 just as it leaves the crimping chamber restriction 42 to immediately cool the yarn and direct it toward the endless conveyor 64. A finishing agent may be applied to the yarn prior to packaging or further processing.

The air pressure (p.s.i.g.) at air cylinder 40 is adjusted to exert such pressure between rolls 46 and 48 as to prevent yarn slippage. The pressure applied to the clap per gate 44 is adjustable to obtain the desired amount of kinkiness of crimp in the yarn. Higher pressures produce a higher frequency, sharper crimp or curl. The pressure application at the air cylinders may also be accomplished in other ways, e.g., by dead weights, hydraulic devices, and the like.

The amount of moisture which may be applied to the sheet of yarn 30 from vapor nozzles 34 will control the hold-up time factor and temperature for the heat setting and drying of the yarn within the heat-setting and drying chamber 66.

FIG. 4 will be described in connection with Example VIII hereinafter.

A further understanding of our invention will be had from a consideration of the following examples which are set forth to illustrate certain preferred embodiments.

EXAMPLE I A spinning solution consisting of 19% of modified acrylonitrile polymer containing about 60% acrylonitrile and about 40% vinylidene chloride polymer modifier with an average molecular weight of 50,700 dissolved in dimethyl formarnide to give a solution having a viscosity of 1020 poises at 100 C. was converted into filaments in a plurality of spinnerettes. A more complete description of such an operation may be found in HS. Patent 2,811,409. The spinnerettes were 3 inches in diameter, and each contained 300 holes of 0.20 mm. in diameter. The top air temperature was 501-5 C. and the bottom air tempera 5?;15015" C. in the spinning cabinet.

45 cabinet ends of tow were passed continuously from the spinnerettes at a rate of 19.3 meters per minute (m./m.) and treated with mineral oil base lubricant. The denier per filament of the tow was 16. The tow was then drafted on a series of 5 rolls such as those illustrated in FIG.2. The first roll was an idler roll turning counterclockwise. The second roll or first draft roll moved clockwise, the tow passing over and around 60% of the surface thereof. The second and third draft rolls moved respectively counterclockwise and clockwise, the tow being in contact with the former 60% and the latter 30% of the surface thereof. The draft. ratio between the preheater roll and the first draft roll was 1.6:020. The draft ratio is the ratio of the length of the same portion of the yarn after stretching to the length before stretching or, expressed in another way, the rate of the draft roll r.p.m. to the pre-draft r.p.m. Between the second draft roll and the preheater roll the draft ratio was 48:0.20 and between the third draft roll and the second 0810.20, the total draft ratio being 56:06. This amounts to about 500% tension or stretching in terms of percent increase in length. The preheater and first two draft rolls were kept at the following temperatures by the use of a Dowtherm heat exchange agent.

Dowtherm Temp.

Preheater 255i5 C. First draft roll 240il0 C. Second draft roll 210110 C.

The tow was next passed through a crimping zone such as that of FIG. 3 where a substantially uniform crimp of 7 crimps per inch (c.p.i.) was imparted. Crimper conditions were as follows:

After leaving the crimping zone the tow was conducted through a drying, shrinking and heat-setting zone heated to a temperature of from C. to C. for a hold-up time of 3 minutes. The fiber after being heat-set had the following properties:

Instron, g.d. 0.65 Elongation percent 3 0 Crlmp c.p.i 15

Denier per filament (d./f.) 16

EXAMPLE II A modified acrylonitrile yarn was prepared in accordance with the general procedure of Example I, except that the solvent used in spinning this time was acetone, and the yarn cut into staple fiber. The staple fiber was stock dyed in a Riggs and Lombard dye kettle at 71 C. with a basic dye formula in a medium brown shade. The staple was then dried at 104 C. on a belt-type dryer. The staple was then processed in a 2 /2s 3-ply yarn on the following equipment:

(1) Whitin roller card (2) Warner Swazy pin drafter (3) Whitin draw frame (4) Whitin roving frame (5) Whitin twister The spun yarn was made with four turns per inch (t.p.i.) in the singles and 2 /2 t.p.i. in the ply. Skeins of this yarn were tested and found to have a specific volume of 75 cubic inches per pound. The skeins were treated in steam at 100 C. at atmospheric pressure. Specific volume after treatment was found to be 115 cubic inches per pound. The skeins were then tufted into a high-bulk, high-cover cut-pile rug. Steaming of a modacrylic yarn prepared by a prior art lower-drafting and unmodified crimping and heat-setting procedure employing none of the novel techniques of the present invention caused an increase in specifi volume of the yarn skeins of from 75 to 85 cu. in./ lb. only.

EXAMPLE III Skeins before steaming made by conditions described in Example II were tufted in a cut-pile rug construction. Steaming of the rug caused the fiber to bloom into a highbulk yarn. A 25-ounce rug made from this high-bulk yarn was found to be equivalent in bulk or loft to a 32- ounce rug produced from yarn formed without the special high-draft, no-relaxing, substantially self-imposed crimping of the present invention.

EXAMPLE IV Skeins made from fiber produced at plant conditions described in Example II were made up in natural yarn form and tufted in a loop-pile rug construction at 3 ounces per square yard. This rug was piece-dyed at 71 C. with a grey premetallized dye formula and then dried at 104 C. During the dyeing and drying operations, the bulk was developed in the carpet. The carpet was of high bulk and free from defects. A carpet made from yarn produced by prior art stretching and relaxing techniques followed by mechanical crimping under 30-60 p.s.i. without the use of banding guides or clapper gates was of an unattractive, non-durable appearance having cracks in the pile, laydown of individual loops or substantially no interlooping bulkiness, and could not be successfully piece dyed.

EXAMPLE V A comparison was made by preparing 2 high-bulk staple-yarn samples. The samples were prepared by a process wherein double drafting was followed by a relaxing step, with especially harsh crimper conditions employed. For these samples substantially the same process was used as in Example I. Table I which follows gives the comparative results.

Table 1 Sample 1 Sample 2 Number cabinet ends in tow 45 45 First draft ratio 1. 6 1. 6 Total draft ratio 4. S 4. 8 Draft or relax ratio .90 9O Preheat temperature (Dowthenn), C 255 255 Draft temperature (Dowtherm), C. 240 240 Relax temperature (Dowtherm), C 200 200 Steam rotameter RD G (Orirnper) 5. 24 Steam pressure (Crimper chamber) 50 50 Crimper discharge temperature, 0.. 85 95 Crimper clapper gate pressure 26 10. 5 Heat set crimped, d./f 13. 8 17. 5 Heat set ribbon, d./i. (no crimp) 12.0 12. 9 Percent Crimp recovery on steam G. 9 16. 5 Crimps per inch (heat set tow) 11. 9 10. 7 Strength of heat set tow, g./d 0. 43 0. 45 Percent Gain in crimp recovery". Percent Gain in strength Hot water shrinkage (before heat setting) 18 19. 5

Total draft ratio including the draft between the second and third draft rolls.

In the samples 1 and 3 in Table 1 the item marked draft or relax ratio is the relax ratio between rolls such as 26 and 28 of FIG. 2. The compositions used in this comparison were modaerylic polymer tow prepared as in US. Patent 2,811,409, the polymer having an acrylonitrile content of approximately 65% EXAMPLE VI Heat-set tow was prepared substantially as in Example I, using a clapper gate modification of the clapper gate stufier box-type crimper such as that depicted in FIG. 3. The yarn and treating conditions were as follows:

Yarn2200 denier, 16 cl./f., brown, continuous filament lofted acetate twisted and piled to about 6600 denier with 6Z turns per inch.

Feed roll speed 50 m./m, Feed roll air pressure 1 A p.s.i.g. Moistening air pressure 10 p.s.i.g. Clapper gate air pressure 5 p.s.i.g. Steam pressure 3 /2 p.s.i.g. Oven temperature C.

The treated, textured yarn was subsequently tufted into a rug with A-inch cut-pile height weighing about 32 oz./sq.- yd. (tuft weight). The resulting appearance and texture were excellent, with the highly desirable surface loopiness or interlooping clearly exhibited, including a high retentive crimp,

EXAMPLE VII The procedure of Example VI was followed with the exception of the following:

Yarn3 ends of 3-plied 2200 denier, 16 d./f., brown continuous filament, lofted acetate, 6Z turns per inch a total of about 20,000 denier Feed roll speed 50 m./m. Feed roll air pressure 2 p.s.i.g. Moistening air pressure 15 p.s.i.g. Clapper gate air pressure 7 /2 p.s.i.g. Steam pressure 5 p.s.i.g. Oven temperature C.

The treated, textured yarn was subsequently tufted into a rug with it-inch cut-pile height weighing 32 oz./ sq. yd. The enhanced loopiness, good cover, bright color and crimp recovery and crimp retention were again clearly exhibited.

EXAMPLE VIII The increase in specific volume brought about by subjection to steam was measured for three yarn samples, viz., 1) a prior art modacrylic yarn prepared by conventional stretching, relaxing, and drying low-shrink meth ods, (2) a high-shrink unmodified polyacrylonitrile yarn and (3) a high-shrink modacrylic yarn, the latter two prepared by the high-shrink, high-bulk process of this invention. The results are shown in FIG. 4. The increase in specific volume to greater than 100 cu.in./lb. upon bulking by heat treatment is evidenced by the two samples prepared according to this invention, particularly the modacrylic sample.

EXAMPLE IX In this example the effect of steaming and aging on the specific volume of modacrylic yarn produced in accordance with the present invention yarn is demonstrated. The crimper pressure and the steam pressure in the crimping zone are increased in some instances. The results of 3 /2 months aging are indicated in the following chart wherein 8 samples are compared as to percent increase in specific volume upon steaming both before and after aging. The example indicates the crimp retention or lasting bulkiness of our yarn.

Eflect of 3 months aging on specific volume tests on steamed modacrylic yarn Sample No 1 2 3 4 5 6 7 8 Crimper pressure (p.s.i.g. 15 6 6 15 15 6 6 Steam pressure (p.s.i.g.). 6 7O 6 6 6 70 70 70 Relax temp. C 190 190 190 240 240 240 240 190 Draft temp. C ,1 210 190 190 210 190 210 190 210 SPECIFIC VOLUME TESTS (.05 GJD TENSION) In. /lb., initially on /1 yarn:

Unsteamed 69 77 71 70 70 75 73 75 Steamed 111 110 108 104 104 114 109 108 Percent increase 38 34 33 33 34 33 31 In /1b., aged 3% months on 2.5/3 yarn:

Unsteamed 82 9O 79 79 83 82 79 81 Steamed 121 110 104 100 111 110 109 106 Percent increase 32 18 24 21 25 25 28 24 EXAMPLE X This example illustrates the use of the high bulk yarn of this invention in a blend with a natural fiber. A 28- oz. per sq. yd. loop-pile carpet was tufted. After tufting, the carpet was steamed and examined for bulk, cover, hand and appearance. The characteristics of the sample, including the specific volume before and after steaming are shown in the following table. Again it can readily be seen that the specific volume after steaming is considerably over 100 cu. inches per pound. The modacrylic yarn used in the blend of this type was produced by the increased crimper steam and pressure conditions in the above-described process. This sample exhibited excellent cover, good hand, high crimp, high bulk, and fluffy appearance.

Percent High-bulk modacrylic 71.5 Percent Wool 28.5 T.p.i. Singles, Z 4.5 T.p.i. Ply, S 2.6 Denier 4600 G./D. .66 Percent Elongation 28.9 Specific volume, in. lb. (.05 g./d. Tension) Before steaming 96 After steaming 107 Percent Increase 11 /z EXAMPLE XI A comparison of various methods of bulking by heat treatment to produce the high bulk, high crimp retention yarn of this invention was made. Six-inch stock-dyed modacrylic carpet samples were heat treated in the following ways.

(1) Latex, air-cure (control) (2) Latex, oven-cure face up at 121 C.

(3) Latex, oven-cure face down at 121 C.

(4) Latex, surface spray with water, oven-cure face up at 121 C.

(5 Steam on Hoffman press latex, air-cure (6) Mock piece dye, latex, air-cure (7) Wet out, tumble dry at 82 C. latex, air-cure (8) Latex, oven-cure face down at 82 C.

All types of heat treatment were satisfactory, the steaming on the Hoffman press giving what appeared to be a somewhat better development of bulk than the other types, with curing in the oven face down at 121 C. giving second-best results. Piece dyeing was also highly satisfactory in imparting the desired loopy high bulk.

The results indicated that there is an apparent dulling of the fiber when the high-bulk crimp is developed upon heat treatment, this dulling imparting improved resistance to soiling over yarn produced by prior art procedures.

EXAMPLE XII An evaluation was made of modacrylic fibers of from 8-16 denier per filament, high-bulk yarn produced in accordance with the present invention. 20 pounds of each of 3 lots of 8, 12 and 16 d./f. respectively were processed on a roller card and pin drafted into 50 grain slivers of 4 inches in length. The 12 d./f. fibers were processed extremely easily. However, 8 d./f. and 16 d./f. extremities were found appropriate, since the 16 d./f. fibers exhibited a small tendency to not detach quite so readily from the surface of the roller and the 8 d./f. denier fibers barely maintained a cu. inch per lb. specific volume or representative high bulk after steaming. The fibers were pin drafted and processed into a 2.5 1 cc. yarn with a 2.5 TM, which is a representative carpet yarn. Several finer-count yarns were also spun from each of the fibers approaching the spinning limit of each denier, viz. for 8 d./f., 16/1 00.; for 12 d./f., 12/1 cc. and for 16 d./f., 6.1/1 cc. As the counts approached the fine extremity a slight cockling or non-uniform effect was detected, indicating that the limit of fineness was being approached. Yarn was spun using twist multifilament of 2.0, 2.5, 3.0 and 3.5, indicating that substantially any degree of twist could be inserted in the yarn without decreasing the desired bulk development. The following table indicates the results of evaluation of separate lots of 8, l2 and 16 d./f. modacrylic high-bulk yarn of this invention. Part of the yarn was skeined and steamed on a Hoffman press and the specific volume in cubic inches per pound of the steamed and unconditioned yarn determined.

Evaluation of 8, J2, and 16 d./f. modacrylic high-bulk yarn Ratio avg. specific volume before/after steaming on Hoffman press Percent ncrease in bulk Length 0 0 From an examination of the above table it can be seen that the carpet yarns of all the samples produced the increase in bulk by which yarn prepared according to this invention is typified. The 16 d./f. yarns developed high bu-lk all the way from a 25/1 cc. yarn to near a denier per filament spinning limit of 6.6/1 cc. The higher the twist, in general, the more difficult became the development of bulk.

EXAMPLE XIII This example illustrates that loop pile carpets made from high bulk modacrylic fiber prepared in accordance with this invention may be stock dyed or piece and dried in such a way as to produce improved cover and soil resistance. A quantity of 16 d./f., 4" bright high-bulk modacrylic staple was stock and piece dyed under the conditions of the following table with the crimp-retention, high-bulk retention, and wear-resistance as indicated therein.

Carpeting tests D./f. x length 16 x 4 Luster Bright Stock dyeing temperature, C 71 88 }Piecc Dyed {Undyed Undyed Stock drying temperature, C 03 93 at 71 C. Steamed Unstcarned Yarn counts TPI singles/ply Denier singles GJd. singles Percent elongation singles Hot Water shrinkage Specific volume tests, ind/lb Original Floor test:

Initial thickness Percent thickness retained 10,000

steps Percent thickness retained 20,000

steps Stair test, down flight:

Beginning wear Moderate wear Severe wear;

Table leg test, 100 ps. Initial thickness. Percent thickness min. recovery h 52 52 Percent thickness retained, 24.

hr. recovery 67 67 In the preceding table, in addition to a showing of high bulk and good wear, is seen a heat and moisture shrinkage of approximately and an increase in specific volume of up to 50% in high bulk yarn spun on an American system.

EXAMPLE XIV Crimp reten- Nominal tion, percent Steam/Chamd./I. x length ber, p.s.i.

It can be seen from the above table that a minimum crimp retention of about 12% is characteristic of the heat-treated high-bulk yarn prepared according to the present invention.

EXAMPLE XV Continuous filament textured yarn was prepared in accordance with the embodiment of this invention wherein the crimping pressure and steam pressure in the crimping zone were increased and the filaments were twisted slightly prior to the crimp-operation. The yarn had a total denier of 2700. The drafting operation was conducted on an apparatus such as that shown in FIG. 2 with the second and third drafting rolls operated respectively as relaxing and take-up rolls. The various spinning, twisting, crimping, and heat-setting or drying conditions were as follows- Speeds: m./m. Preheat roll 43.5

Draft roll 68.6

Relax roll 202 Take-up roll 186 Draw roll 188.5 Crimpcr 182 Draw roll 112 Draw roll 113.5

Temps: C. Preheat 185 Draft 202 Relax 180 Dryer 1st stage Dryer 2nd stage 141 Spinning machine: C. Bottom air temp. 154 Top air temp 51 Crimper: p.s.i.g. Chamber pressure 19 Spray pressure 19 Roll pressure 2.5

A qualtity of this 2700 total denier, bright-textured filament modacrylic yarn of 14 denier per filament was package dyed nutria and dark brown by a commercial dyer. The yarns were plied with 1.0 t.p.i. (turns per inch) and as follows:

1 end of nutria with 1 end of natural 1 end .of brown with 1 end of natural 1 end of nutria with 1 end of brown The yarn was combed up on the gauge tufting machine to make the following samples.

Sample 1.A1ternate ends of 2700 denier 2-ply nutria and natural, and nutria and brown, tufted into 7 pile bright, 25 oz./yd. loop-pile carpet.

Sample 2.2700 denier, 2-ply in the following arrangement:

1 end natural/nutria 1 end nutria/brown 1 end natural/ brown 13 These yarns were tufted into A pile height, 22 oZ./yd. loop-pile carpet.

Both these carpets had excellent bulk and cover. The 22 oz./yd. carpet, Sample 2, had approximately equal bulk and cover to a 25 oz./yd. staple modacrylic carpet of comparable pile height.

EXAMPLE XVI Several pounds of 3 d./f., 1-2-inch prestretched modacrylic yarn were carded into oz./yd. batting of (1) 100% modacrylic and (2) 50% blend of modacrylic with polyethylene. The batting was subjected to two types of heat treatment, viz. (a) steam in an open Hoffman press with the batting unrestrained for 30 seconds at 146 C. and (b) dry heating in a glass radiant press using no pressure and with batting for 4 minutes at 177 C. The application of heat to the unrestrained batting resulted in considerable shrinkage and high bulk, particularly at the extreme edges of the batting where the fibers were more loose and fluffy. Batting of 1 6 d./ f. modacrylic high-bulk fiber similarly made which had not been prestretched exhibited even more shrinkage and bulk development than the 3 d./f. fiber.

EXAMPLE XVII This example demonstrates the effect of drafting the same modacrylic yarn at a ratio of 1.0 or higher and less than 1.0, viz., about 0.85. The following table presents the results on yarn thus drafted. The drafting step for which the data for the samples of the following table were obtained was substantially the third step of a threestep drafting process such as depicted in FIG. 2, specifically, the drafting step between second draft roll 26 and third draft roll 28. As indicated in the table a comparison was made between heatset and unheatset yarn.

a way of manufacturing a yarn of surprising high bulk and strength with an enhanced crimp permanency or crimp retention. This high bulk and highly retentive crimp results at least in part from a high-d-raft operation which includes a relaxing step. The overall result is a stronger yarn with much less harsh and plastered filaments. A shrinkage of 3060% is often obtainable by the heat treatment step as well as an increase in specific volume to at least 100 cu.in./lb. Without the application of the high draft-relaxing step, preferably coupled with the high pressure crimping techniques and heat-treatment or bulking step, the crimp uniformity and strength generally decrease rapidly with an increase in crimps per inch. Thus, when the technique of controlling the draft and including a relaxing step is followed by imposing fewer crimps per inch in the crimping zone to obtain a high-shrink yarn, a high crimp-per-inch value in the yarn is obtained upon subsequent shrinking by heat treatment, prefer-ably steaming, together with an enhanced crimp retention.

We do not wish to be bound by any particular theory as to the cause of the ability of the high-bulk yarn of this invention to shrink when subjected to elevated temperatures after textile processing. However, it is possible that this high-bulk, high crimp recovery characteristic is due to (l) a tendency of each individual fiber to revert when heated to the orginal high-crimp configuration lost to a certain extent in the mechanical stretching action of drawing, carding, and the like when staple fiber is used or (2) to an actual imparting of an added crimp in the shrinking action upon heating as a result of the preceding steps of a high degree of stretching with negligible relaxing and without a separate relaxing step and a mild uniform width and thickness crimping operation when continuous filament yarn is used. This shrinkage or bulking with resulting high crimp recovery and high crimp reten- Percent shrinkage vs. relax ratio modacrylic yarn Heatset 1 Unheatset Draft Percent Test ratio Tenacity Percent Percent Tenacity Percent Percent Shlll'lk (grams/ elongation at hot water Denier (grams/ elongation at Modulus of hot water Denier age 2 denier at break Shrinkage denier at break elasticity shrinkage break) break) Average 0.85 1. 77 39. 2 0.0 2, 450 1.82 29. 0 40. 4 11. 6 2, 090 17. 2

Average- 1. 0 1. 62 37.8 0. 27 2, 840 1. 89 17. 6 48. 4 22. 1 2, 003 4]. 8

1 At 140 C. for 5 minutes after drafting.

From the preceding tabular results comparing a thirdstep drafing at a ratio of 1.0 with one at a ratio of less than 1, specifically, 0.85, it is apparent that the following advantages are obtained by use of a ratio of less than 1.0.

(a) The unheatset fiber has a higher elongation (30% versus 18%). This makes the fiber tougher and better able to stand crimping, texturizing, or the like.

(b) The hot Water shrinkage is lower (11.6% versus 22.1%). This means that the fiber shrinks less in subsequent treatments. As shown by a heatset fiber with 140 C. heatsetting, this amounted to only 17% shrinkage during heatsetting versus 42% using the 1.0 ratio.

(c) The final properties of the fiber were as good or 7 better after heatsetting.

((1) By using the same manufacturing process, a lower d./f. fiber can be produced after heatsetting due to the lower shrinkage during heatsetting.

It is believed that it can readily be observed by the preceding description and examples that we have invented effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. A method for preparation of a. high-bulk modacrylic 0 yarn product which comprises spinning a modacrylic yarn of 2-24 d./f., drafting the yarn at a draft ratio of from about 2:1 to 8.5 :1 by passing over a series of draft rolls arranged to draft the yarn in at least three stages the last of which is at a draft ratio of less than about 1.0, steam crimping the drafted yarn at a clapper-gate pressure of less than about 30 p.s.i.g. and a steam pressure of at least about p.s.i.g., conducting the yarn in a substantially tensionless condition into a heat-setting zone and forming the yarn into a high-bulk staple modacrylic yarn.

2. The process according to claim 1 wherein the draft ratio of less than about 1.0 is between about 0.8 and 0.9.

3. A method for the preparation of a high-bulk yarn product which comprises extruding a plurality of continuous modacrylic filaments of 2-24 d./f., drafting the filaments over a series of draft rolls in at least three stages, the third stage of drafting being at a ratio of less than 1, crimping the drafted filaments and heating and moistening them with high-pressure steam while they are compressed in a crimping zone under less than 30 p.s.i.g. clapper-gate pressure and at a steam pressure of at least about 5 p.s.i.g., removing the steamed filaments from the crimping zone so that they fall of their own weight on a moving surface, conducting said filaments on said moving surface in a tensionless manner through a heat-setting zone having a temperature of at least 100 C. for at least 3 minutes and cutting said filaments into staple fiber lengths, processing said cut filaments into a staple yarn and subsequently subjecting said yarn to treatment with steam to develop a high degree of bulkiness and crimp.

4. The process of claim 3 wherein the first stage of drafting has a ratio between 12:1 and 2:1, the second stage of drafting has a ratio between 2:1 and 5: 1, and the third stage of drafting has a ratio between 08:1 and 1.0: 1.

5. The process of claim 3 wherein the filament-s are subjected to a steam pressure in the crimp zone of greater than p.s.i.g.

6. The method of claim 3 wherein the staple yarn is subjected to the final steaming treatment after being processed into fabric form.

7. The method of claim 3 wherein the 3-stage drafted, steam-crimped, heat-treated cut staple is processed into a yarn and further processed into a pile floor covering, and the final steaming treatment is then carried out.

8. The method of claim 3 wherein the 3-stage drafted, steam-crimped, heat-treated cut stalple is processed into a non-woven fibrous batting and subjected to a final steaming treatment to enhance its bulk and loftiness.

References Cited by the Examiner UNITED STATES PATENTS 2,669,001 2/1954 Keen 28--72 2,686,339 8/1954 Holt l966 2,917,806 12/1959 Spence et a1.

3,017,684 1/1962 Pittman l966 X 3,024,517 3/1962 Bromley et a1 l966 X 3,101,521 8/1963 Rosenstein et al l966 X 3,142,147 7/1964 Betsch 57157 X ROBERT R. MACKEY, Primary Examiner.

DONALD W. PARKER, Examiner.

Claims

1. A METHOD FOR PREPARATION OF A HIGH-BULK MODACRYLIC YARN PRODUCT WHICH COMPRISES SPINNING A MODACRYLIC YARN OF 2-24 D./F., DRAFTING THE YARN AT A DRAFT RATIO OF FROM ABOUT 2:1 TO 8.5:1 BY PASSING OVER A SERIES OF DRAFT ROLLS ARRANGED TO DRAFT THE YARN IN AT LEAST STAGES THE LAST OF WHICH IS AT A DRAFT RATIO OF LESS THAN ABOUT 1.0, STEAM CRIMPING THE DRAFTED YARN AT A CLAPPER-GATE PRESSURE OF LESS THAN ABOUT 30 P.S.I.G. AND A STEAM PRESSURE OF AT LEAST ABOUT 5 P.S.I.G., CONDUCTING THE YARN IN A SUBSTANTIALLY TENSIONLESS CONDITION INTO A HEAT-SETTING ZONE AND FORMING THE YARN INTO A HIGH-BULK STAPEL MODACRYLIC YARN.