March 3, 1970 J. GQHOPKINS 3,498,044
METHOD FOR PRODUCING A LATENT TEXTURIZED YARN Filed Nov. 15, 1968 2 Sheets-Sheet 1 A? 6 a e lllOll F219. 3 INVENTOR.
JOHN G. HOPKINS 3,1970 J. HOIPKIIYNS METHOD FOR PRODUC 'Il IG A LATENT 'IEXTURIZED YARN 2 Sheets-Sheet 2 Filed Nov.
INVENTOR. JOHN G. HOPKINS ATTORNEY United States Patent US. Cl. 57-157 6 Claims ABSTRACT OF THE DISCLOSURE The subject invention relates to a method for producing a latent texturized effect in a multifilament thermoplastic yarn. The multifilament thermoplastic yarn is drawn around a heated surface under a controlled tension such that some of the multifilaments shrink, whereas other of the multifilaments do not shrink but rather some of the filaments are caused to become convoluted or looped. After being passed about the heated surface, the multifilament yarn is wound under a sufficient tension in order to straighten out the convolutions or loops in said filaments and thereafter the yarn is collected in an unlooped state whereby a latent texturized yarn is produced. When the yarn is woven or knitted into a fabric, the tex turizing effect is noticed as it produces a soft or silky hand.
This invention relates to a method for processing yarns. In one aspect it relates to a method for treating continuous multifilament thermoplastic yarns to impart a latent texturized effect thereto. In another aspect this invention relates to a latent texturized yarn which, when either woven or knitted into a fabric, imparts a pleasing silklike surface effect to said fabric by reason of the presence on the surface of the fabric of very short slack lengths or loops of some of the continuous filaments forming said multifilament yarn.
In recent years the introduction of synthetic yarns has led to fabrics having high strength, improved durability and most important improved laundera-bility and wrinkle resistance. However, fabrics made from these yarns and particularly those made from continuous filament yarns possessed imperfections and had to be improved in a number of respects. Fabrics of filamentary thermoplastic yarns tend to have a slick cold hand and are deficient in cover and lustre in many end uses. Thus in spite of certain superior functional properties fabrics produced from these yarns do not have all the properties and the aesthetic qualities desired in an ideal fabric. Synthetic fabrics having the warm dry hand, good lustre and other properties of natural yarns, particularly silk, are desirable.
In order to improve these properties of the end use fabrics a number of commercially available processes were developed to texturize these thermoplastic yarns. By texturizing these yarns it is possible to obtain a fabric having a resilient or elastic nature in addition to having increased bulkiness, coverability, a dry hand and other properties which are ideal for the end use of the fabric.
It is known that a texturized or elastic nature can be imparted to a continuous multifilament thermoplastic yarn by passing the yarn while in elevated temperature around a surface which stresses the yarn such that the filaments thereof tend to assume a highly convoluted configuration. This method of texturizing continuous multifilament thermoplastic yarns is highly desirable for the reason that yarns elasticized by this method normally have little or no tendency to twist and can therefore readily be employed as single ply. It also differs from most other methods of elasticizing or texturizing thermoplastic yarns in that the elastic nature of a yarn processed 3,498,044 Patented Mar. 3, 1970 ice in this manner is only partially apparent, following passage of the yarn about the heated surface. Although this texturizing process provided a yarn which provided excellent aesthetic effects to the fabric, it was difficult to process these yarns in knitting or weaving machines because of their bulkiness due to the loopiness or convolutions of some of the filaments.
Therefore, one of the objects of this invention is to provide a method for subjecting a multifilament yarn capable of being differentially shrunk and forming convolutions to a randomized shrinking consequent convolution among the various filaments by passing over a heated surface, the differentially shrunk filaments are then tensioned and collected in an unlooped yarn state;
Another object of this invention is to provide a texturized yarn which imparts to said fabric improved properties and aesthetic qualities;
Yet another object of this invention is to provide a process which enables differentially shrunk yarns to be easily knitted or woven without losing the benefit of the inherent residual shrinkage when the woven or knitted fabric is finished;
A still further object of this invention is to provide apparatus for carrying out the process of this invention.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description which is to be considered in connection with the accompanying drawings wherein:
FIGURE 1 schematically illustrates the method according to the subject invention;
FIGURE 2 shows the yarn prior to being differentially shrunk;
FIGURE 3 shows the yarn after being dilferentially shrunk;
FIGURE 4 shows the yarn after it has been wound under tension and packaged;
FIGURE 5 schematically illustrates another embodiment of the invention.
Briefly this invention comprises the steps of passing a multifilament thermoplastic yarn about a heated surface; correlatively controlling the speed and tension on the yarn as well as the temperature of the heated surface in order to maintain the tension lower than the dynamic retractive forces on the said yarn so that shrinkage of some of the individual filaments is caused with consequent convolutions or looping of the other filaments; applying sufficient tension to straighten out the convolutions or loops in said filaments and collecting the yarn in an unlooped state whereby a latent texturized yarn is produced.
Suitable materials for use in this process are the synthetic linear polymers having a substantial degree of crystallinity or otherwise exhibiting strong interchain molecular forces such as polyamides, e.g., polyhexamethylene adipamide, polyhexamethylene sebacide and polyaminocaproic acid; polyesters, e.g., polyethylene terephthalate; the l-olefins, e.g., polyethylene, polypropylene; polyamino triazoles; polyacrylonitrile; polyvinylidene chloride; triacetates and the like.
With reference to the drawing, the multifilament yarn 1 passes from a supply bobbin 3, supported on a suitable creel holder, through a guide eye 11, then through a tension regulator 13, which controls the tension of the yarn as it is Passed over a first heated surface 15 and then over a second heated surface 17.
The shape of these surfaces is not critical. They can have shapes which may be flat, curved, tubular, corrugated, around or the like. As shown in FIGURE 1, the heated surfaces 15 and 17 are formed as two pins. The pins 15 and 17 are matte finished or sandblasted at their surfaces in order to minimize the friction of the yarn passing thereover. Each of these pins is heated from a separate source in order to obtain a greater control of the bulking of the yarn 1 passing thereover. It is to be understood that only a single pin need be employed or that a single heat source need be used for both pins. It is also within the scope of this invention that the pins themselves could also be the conductor of current passing therethrough whereby they by themselves form the resistance heating elements. Other forms of heat, such as radiant, are also within the scope of this invention.
An energy source 19 operatively connected to the first pin 15 maintains it at a temperature ranging from 150 to 400 F., preferably from 250 to 350 F., and a second energy source 21 operatively connected to the second pin 17, maintains it at a temperature ranging from 300 to 600 F. and preferably from 350 to 450 F.
The yarn passes circumferentially over the surfaces so as to just touch the surfaces and the friction is maintained at a minimum. After passing over the second pin 17 the yarn 1 passes vertically downward through a pigtail guide eye 23 wherein it then passes between a pair of cot rolls 25 and 27 respectievly. The cot rolls control the speed of the multifilament yarn passing over the pins 15 and 17. The yarn then passe about a conventional draw pin 29. It may be noted at this juncture that draw pin 29 or its equivalent is not considered essential to the practice of the instant invention and any suitable means for generating a drag or tension upon the yarn 1 as it proceeds through the guide means 31 and thence to a conventional yarn takeup means 33, here illustrated as comprising a traveller 32 and spindle array. The yarn is then collected by the takeup means 13 in the form of a conventional yarn package. By proper selection of the traveller (Weight and shape) and spindle speed, one can maintain a sufficient tension on the yarn so as to straighten out the loops or convolutions contained in some of the filaments.
This tension ranges from 0.1 gram per denier to 2.0 grams per denier preferably from 0.3 gram per denier to 1.2 grams per denier and is critical to the performance of this inventive concept.
When the yarn made according to the above described process is knit into fabric, the fabric possesses a pleasing silk-like hand by reason of the presence on the surface of the fabric of very short slack lengths or loops of some of the continuous filaments of the multifilament yarn. This is due to the fact that all the filaments of the yarn are somewhat extended on being knitted or woven and on relaxation of the tension (via hot-wet finishing). After the yarn has been knitted into the fabric, a loopy or puckering effect is produced because each filament in the yarn has a different residual shrinkage than its neighbor.
Although this differentially shrunk multifilament yarn contains filaments having various degrees of shrinkage from neighboring filaments when wound onto the winder under tension, all the filaments will appear straight rather than loopy. As a result, the filaments having low shrinkage do not cause great difficulties in yarn handling during the preparation of the fabric. However when the resulting fabric is scoured in hot or boiling water the filaments having low shrinkage tend to crimp or loop thus giving the fabric greater bulk and cover as well as an improved hand.
FIGURE represents another embodiment of the subject invention wherein two different synthetic polymeric multifilament compositions are subjected to the process. One of the components has a higher shrinkage than the second component so that a greater differential shrinkage effect is effected in the composite yarn formed from these two yarns.
With reference to FIGURE 5, two multifilament yarns of different compositions 35 and 37 pass from two separate supply bobbins 39 and 41, through guide 43, through the tension regulator 47 around the heated rolls 49 and 51, through guide means 53, between cot rolls 55 and 57, around draw pin 59 and then wound onto a conventional wind-up means 61 under tension as described hereinabove. Traveller 62 controls the tension on the yarn during the winding step. The winder 61 plies the two yarns together to make a composite yarn.
With two multifilament yarns each having different chemical compositions and different shrinkage values and each having been subjected to the process, one is able to obtain a greater texturizing effect in the fabric. However, it, like the yarn texturized as described hereinabove, will have a low bulk value prior to being knitted and does not cause any knitting or weaving problems.
The following examples are given by way of specifically illustrating the invention and are not intended to 'be construed as limiting in any sense.
EXAMPLE 1 A 70-denier, 14-filament poly(ethylene terephthalate) yarn 1 was passed from supply bobbin 3 at the rate of 259 feet/minute. At the start the filaments all were of equal length as shown in FIGURE 2. The temperature of pin 15 was maintained at 280 F. and the temperature of pin 17 was maintained at 330 F. The tension on the yarn was maintained under 1 gram as it passed around pins 15 and 17. The speed of the spindle 33 was maintained at 6200 r.p.m. After the yarn was passed over the pins 15 and 17, some of the filaments shrunk more than did some of the others (FIG. 3). The yarn was then wrapped around a frictional pin fabricated from aluminum oxide materials or the like and then wound onto spindle 33. The traveller mechanism 32 maintained a wind-up tension of 62 grams. The yarn resembled an untexturized yarn (FIG. 4). A length of this texturized yarn was cut and measured. It was then boiled for 30 minutes. After boiling the sample was measured again and the percent shrinkage was calculated. Each of the 14 filaments making up the yarn was measured separately and the shrinkage was calculated for each filament (net boil shrinkage). An untextured 14- filament poly(ethylene terephthalate) yarn was employed as a control yarn and after being subjected to the 30 minute boil shrink, a 10% shrinkage in each of its filaments occurred.
Percent total shrinkage Percent net boil after boil: shrinkage 10.0 3.32 10.0 5.00 10.0 5.00 10.0 5.82 10.0 6.81 10.0 7.00 10.0 7.00 10.0 7.50 10.0 8.15 10.0 8.30 10.0 8.30 10.0 10.0 10.0 10.0 10.0 10.0
Single end shrinkage method Scope.-This method has been developed by J. P. Stevens & Co., Inc. to test the shrinkage of an individual strand of filament yarn and has been found to be suitable for testing texturized yarns.
(1) Loop to cm. of yarn. Tie ends together.
(2) Hang yarn on vertical meter stick (attached to rvall) that has a peg at top which serves as a hook for yarn (3) Attach 0.1 gm./denier X2 (number of ends in loop) to yarn loop at bottom. Record reading (A).
(4) Remove weight and boil off (210-212" F.) yarn wrapped in cheesecloth for 30 minutes.
(5) Centrifuge, dry and recondition at 65% RH. and 70 F. at least for four hours.
(6) Hang looped yarn on vertical meter stick and repeat step (3). Record reading (B).
It is noted that some of the filaments have different shrinkage values and it is this difference in shrinkage values between adjoining filaments that gives the latent texturized effect to these yarns when they have been processed into fabrics and the fabrics finished so as to remove all the shrinkage from the yarns. The filaments which have had some of their shrinkage removed during the process described hereinabove will pop or curl depending on the tightness of the knit or weave. Filaments with the least shrinkage left will pop the least in a tight weave.
For the purpose of comparing the relative bulk of untexturized yarn, differentially shrunk yarn which has been wound up under relatively no tension and differentially shrunk yarn which has been wound under the tension ranges described hereinabove, the following method was employed.
Each of the yarns was wound onto a slotted wheel which had a volume of 50 cubic centimeters while under a tension of 0.1 gram per denier. The tension was intermittently checked by a hand-held tensiometer. When the yarns were flush with the flange on the wheel, the tester was stopped and the yarn cut loose from the wheel, conditioned, and weighed. This provides a known volume of yarn, the specific volume of which is given by the formula Specific volume (cu. cum/gm.)
Xolume of wheel (cu/cm.) Weight of yarn (grns.)
The interfilament air space was calculated according to the following general equations:
Bulk density (gm./cu. Cm.)me
Bulk density Packing coefiicient- Air Space=1-Packing co-efficient Determination of additional interfilament air space due to the texturizing process is carried out by the same procedure as outlined hereinabove using the texturized yarn. Knowing the values of original air space (control yarn with no crimp) and the air space of the crimped yarns, a comparative value for the parent yarn bulk was then obtained.
Bulk ind6X=AS AS where:
AS =Air space in bulked yarn, and AS =Air space in control yarn.
The results were tabulated as follows:
6 has a bulk index of 0.67. This represents a net of .12 in bulk index.
EXAMPLE 2 In order to show the effect of this yarn when woven into a fabric, a 5-shaft satin fabric was made up. This weave had the following construction:
difference Warp: Filling Width, 52.00 inch reed picks/inch 90 Dents:
Count, 180 reed sley.
The warp yarns were non-texturized -denier 20-filament having a twist of 2Z. The filling yarns were the latent texturized yarns of the subject invention 70-denier, 34-filaments polyethylene terephthalate having a twist of 2.58. The fabric was then scoured and subjected to a free boil-off so that after boil-off the fabric exhibited a full silk-like hand.
A control was woven in the same construction as hereinabove except the filling yarns were not latent texturized but were yarns used as received from the producer. There was considerable difference in the hand, and in the fullness of the control fabric from that of the woven fabric using the latent texturized filling yarns. The fabric using the latent texturized filling yarns had far more fullness and a much more silky hand than did the control fabric. The boil-off resulted in some of the polyester filaments shrinking more than did the others with the result that the extended lengths of some of the filaments were greater than the lengths of some of the other filaments which had some of their shrinkage removed during the texturizing process described hereinabove.
EXAMPLE 3 A combination of 70-denier 14-filament poly(ethylene terephthalate) yarn 35, and 70-denier 13-filament poly- (hexamethylene adipamide) yarn 37 was passed from supply bobbins 39 and 41 respectively and differentially shrunk over pins 49 and 51 at the same time. Pin 49 was maintained at a temperature of 280 F. and pin 51 was maintained at a temperature of 320 F. The yarns were delivered at a speed of 230 feet per minute. The tension on the yarns as they passed around pins 49 and 51 was maintained under 1 gram. Spindle 61 was rotated 6250 revolutions per minute. After passing around pins 49 and 51, the yarns passed between cot rolls 55 and 57 one turn around an alsimag pin 59 and then wound onto spindle 61 under a tension of 40 grams.
A specified length of composite yarn was cut and measured. It was then boiled for 30 minutes. After boiling, the sample was measured again and the percent shrinkage was calculated. Each of the 14 filaments making up the poly(ethylene terephthalate) was measured separately and each of the 13 filaments making up the poly(hexamethylene adipamide) was also measured separately and the shrinkage values calculated for each filament (net boil Specific Bulk Sample and fiber type, polyester (poly- Nominal Weight volume density Packing Bulk ethylene terephthalate) denier (grams) (cm./gm.) (gm./cm.) coeflicient Air space index Control (n') crimp yarn) 40 31. 045 1.61 621 450 550 Latent texturized yarn (yarn texturized according to subject invention) 40 34.961 1. 43 669 507 493 0. 06 Differentially shrunk yarn wound under substantially no tension 40 26. 412 1. 89 529 383 617 067 By reference to the data it is seen that the yarn wound under tension according to the subject invention has a bulk index of minus 0.06 where the differentially shrunk yarn in which the crimp has not been removed by windshrinkage). A control 14 filament poly(ethylene terephthalate) yarn showed a total shrinkage of 10% in each of its filaments. A control 13 filament poly(hexamethylene adipamide) yarn showed a total shrinkage of 10.5%
ing it under the tension ranges of the subject invention in each of of its filaments.
7 Poly (ethylene terephthalate) Percent total shrinkage Percent net boil after boil: shrinkage 10.0 3.32 10.0 5.00 10.0 5.00 10.0 5.82
Poly(hexamethylene adipamide) Percent shrinkage Percent net boil after boil: shrinkage 10.5 7.17 10.5 8.35 10.5 8.84 10.5 9.00 10.5 9.00 10.5 9.17 10.5 9.25 10.5 9.25 10.5 9.34 10.5 9.42 10.5 10.00
EXAMPLE 4 In order to show the effects of this plied yarn when knitted into a fabric, a two-bar tricot fabric was made on a 21 inch (28 gauge) sample tricot machine.
Both 'bars full Top bar, 77 inch runner "knitting" 1.0-2.3
Bottom bar, 37 /2 inch runner do 1.2-1.0
Weight of finished sample lbs./ sq. yds. 2.35
Top beam 70/ 14 poly (ethylene terephthalate) 70/ 13 poly(hexamethylene adipamide) These two yarns were latent texturized and plied together as described in Example 3.
Bottom beam 15/ 1 poly (hexamethylene adipamide) One, by knitting a lose top runner and a tight bottom runner in order to permit the latent texturized yarn to relax, is able to produce a fabric having much bulk and a luxurious silk hand.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.
What is claimed is:
1. In a process wherein a multifilament thermoplastic yarn is passed about a heated surface and the speed and tension on the yarn as Well as the temperature of the heated surface is controlled so as to maintain the tension lower than the dynamic retractive forces on the yarn whereby shrinkage of some of the individual filaments is caused along with consequent convolution or looping of the other filaments, the improvement therewith comprising the step of winding said yarn under sufficient tension in order to straighten out the convolutions or loops in said filaments whereby the yarn is collected in an unlooped latent texturized condition.
2. A method according to claim 1 wherein two multifilament yarns each having a different shrinkage value from the other are passed about said heated surface and are collected under sufficient tension in order to straighten out the convolutions or loops produced in said filaments of each yarn.
3. A process according to claim 1 wherein the tension during the winding step is maintained in a range from 0.1 gram per denier to 2.0 grams per denier.
4. A method according to claim 2 wherein a poly(ethylene terephthalate) multifilament yarn is mixed with a poly(hexamethylene adipamide) multifilament yarn.
5. A process according to claim 1 wherein the yarn is made from a composition comprising one selected from the group consisting of polyhexamethylene adipamide, polyhexamethylene sebacide, polyhexamethylene acid, polyethylene terephthalate, polyethylene, polypropylene, polyamino triazoles, polyacrylonitrile, and polyvinylidene chloride.
6. A latent texturized yarn made according to the process of claim 1.
References Cited UNITED STATES PATENTS 2,979,883 4/1961 Waltz. 3,273,328 9/1966 Bloch 2872.17 3,330,896 7/1967 Fujita et al. 57l40 3,357,655 12/1967 Iwnicki et a1 57-157 3,439,490 4/1969 Tarkington et al. 57157 DONALD E. WATKINS, Primary Examiner US. Cl. X.R.