US3549310A - Method for mercerizing stretchable core spun yarns - Google Patents

Description

United States Patent 3,549,310 METHOD FOR MERCERIZIN G STRETCHABLE CORE SPUN YARNS Walter A. Gardner, 506 Piccadilly Circle, Gastonia, NC. 28052 Continuation-impart of application Ser. No. 550,526, May 16, 1966. This application July 29, 1966, Ser. No. 568,791

Int. Cl. D06m 1/02; D02g 3/36 US. Cl. 8125 6 Claims ABSTRACT OF THE DISCLOSURE Core-spun yarns of stretchable core yarns and sheathes of stable fibers are continuously drawn from yarn packages at a rate of approximately 150 to approximately 375 yards per minute by driven rolls. The continuously moving yarn is subjected to a drag working against the driven rolls to tension the yarn and maintain the tension at approximately 80 percent of that which the yarn is capable of withstanding without breaking. The continuously moving tensioned yarn passes through a mercerizing solution and then a neutralizing solution before being dried and packaged.

This application is a continuation-in-part of my copending application, Ser. No. 550,526, filed May 16, 1966, now abandoned.

The invention relates generally to methods and apparatus for manufacturing textiles, and particularly to a method and apparatus for commercially mercerizing corespun yarns consisting of stretchable core yarns and sheathes of staple fibers.

Mercerization is a finishing process extensively used on cotton yarn and cloth, essentially consisting of impregnating the material with a cold, strong sodium hydroxide solution. The treatment increases the strength and affinity for dyes, and, most important, if done under tension, the luster is remarkably increased. Conventional apparatus used commercially for warp mercerizing cotton yarn may handle approximately twenty-two or more warps at a time. Since each warp consists of hundreds of ends of yarn, it will be appreciated that commercial mercerization of cotton yarn is a large scale operation requiring very expensive apparatus.

In the use of conventional apparatus, the warps are passed through two sets of rolls. The second set is operated at a higher surface speed than the first set, in consequence of which the yarn therebetween is tensioned. While thus tensioned, the yarn is impregnated with the treatment solution. Due to the great number of yarns being processed, the pressure applied by the rolls to the yarns in order to develop the grip necessary to prevent slippage of the yarns between the rolls is very substantial. In fact it is so great that there is danger of crushing the yarns. In addition, since each warp contains the same number of yarns, and since the diameter of the yarns may vary from warp to warp, the size of the warps in transverse section may vary from warp to warp. Thus the grip of the rolls on the larger warps tends to be firmer than that on the smaller warps, as a consequence of which there may be some slippage between the smaller warps and the rolls. This means that the tensioning effort applied to the larger warps will tend to be greater than that applied to the smaller warps, which may not be desirable. Furthermore, some of the yarns in each warp will not come into contact with the rolls. Thus there will be slippage not only between some of the warps and the rolls, but also between the individual yarns of each warp. This means that the tensioning etlort applied to the yarns that 3,549,310 Patented Dec. 22, 1970 ice come into contact with the rolls will be greater than that applied to those that do not come into contact with the rolls, which may not be desirable. Due to this possibility of slippage, tensioning the yarns by passing the warps through two sets of rolls operating at dillerent surface speeds is not satisfactory for all purposes.

For example, commercial core-spun yarns consisting of stretchable core yarns and sheathes of staple fibers, are known, but such yarns are not mercerized because of the difiiculties experienced in tensioning the yarns properly when utilizing conventional apparatus. In order to develop an acceptable luster, the yarns must be processed without being crushed, each yarn must be subjected to the same tension while passing through the treatment solution, and the tension must be a predetermined high percentage of the maximum tension which the yarn is capable of withstanding without breaking. These desiderata cannot be realized when conventional apparatus is utilized.

Another reason for not mercerizing core-spun yarns consisting of stretchable core yarns and sheathes of staple fibers is that if the stretchable core is made of a material (for example, spandex) that will deteriorate if overexposed to the mercerizing solution, excessive loss of yarn occurs when the apparatus is threaded up at the beginning of a run and when there is a breakdown in the operation. Normally, the yarn is not exposed to the mercerizing solution for more than about ninety seconds. However, when threading up and when there is a breakdown, perhaps a yard or so of each yarn passing through the mercerizing solution may be exposed thereto for more than the maximum safe period of time, as a consequence of which a minimum of approximately 8000 yards of yarn is lost. Needless to say, such a loss is prohibitive.

Mercerization of commercial core-spun yarns consisting of stretchable core yarns and sheathes of staple fibers is important because without such yarns the manufacturer of mens half-hose, for example, has only a choice between several evils. He may use filamentary yarns, in which case his product will lack a good hand and luster. In addition, the sizes that must be stocked will be excessive. He may use conventional spun yarns of staple fibers, in which case his product will have a good hand and luster. However, the sizes that must be stocked will be excessive. He may use core-spun yarns consisting of unstretchable core yarns and sheathes of staple fibers, in which case his product will have a good hand, but, whether mercerized or not, will lack luster. In addition, the sizes that must be stocked will be excessive. He may use core-spun yarns consisting of stretchable core yarns and sheathes of staple fibers, in which case his product will have a good hand and the number of sizes that must be stocked will be held to a minimum. However, as pointed out hereinabove, such yarns are not mercerized, and, therefore, the product will lack luster.

Accordingly, an important object of this invention is to provide a method and apparatus for commercially mercerizing core-spun yarns consisting of stretchable core yarns and sheathes of staple fibers.

Another object is to provide such a method and apparatus wherein the yarns are not processed in the form of warps, but individually in small numbers, and tension in the individual yarns is maintained at a constant high level while the yarns are passing through the mercerizing solution.

Another object is to provide such a method and apparatus wherein the individual yarn end mercerizing is effected at a comparatively high rate of speed and the lengths of the several individual yarn ends in the tension zone are simultaneously subjected each to a substantially uniform predetermined high percentage of of core-spun yarn 16. The yarn passes from the cone 14 horizontally to a roll 21 and then at least once about the roll 21. From the roll 21 the yarn passes horizontally over a guide roll 22," downwardly and under a guide roll 23, upwardly and over a guide roll 24, downwardly and under. a guide 25, upwardly and over a guide roll 26, downwardly and under a guide roll 27, upwardly and over a guide roll 28, downwardly and under a guide roll 29, and upwardlyv and through the nip of a pair of rolls 30. It then passes preferably at least once about one of the rolls 30 and then again throughthe nip of the rolls 30. From the nip of the rolls 30 the yarn passes horizontally through an electric or other heater 31, from whence it passes to and is wound into a cone 32 turned by a winder roll33. The rolls 23, 24 and 25 are disposed in a compartment A of a tank 34, and the rolls 27, 28 and 29 are disposed in a separate compartment B of the tank 34. The compartment A contains a mercerizing solution 36, and the compartment B contains a neutralizing solution 38. The tank 34 is mounted for being lowered, as shown in brokenlines, to facilitate the operation of threading up the apparatus. The rolls 21 through 30 are fixed in position. The rolls 21 through 29 idle while the rolls 30 are driven. The rolls 30 pull the yarn from the cone 14 against a drag induced by conventional means applied to the roll 21, as, for example, a weight 39. Stop motion means (not shown) may be provided to terminate operation of the apparatus in the eventthat the thread breaks.

In theoperation of the apparatus, the yarn is drawn from the cone 14 and through the mercerizing solution 36 and the neutralizing solution 38 by the rolls 30. The grip of the rolls 30 on the yarn is firm enough to prevent slippage between the yarn and the rolls, without being great enough to crush or otherwise injure the yarn. The yarn is drawn through the heater 31 by the cone 32 actuated by the winder roll 33. At the present time, yarn is processed by conventional apparatus at the rate of approximately twenty-five yards per minute, but yarn 16 preferably is processed in the order of 150 to 375 yards per minute.

When the yarn is wetted, it tends to shrink. However, in order to do so, the yarn must overcome the influence of the drag on the roll 21 induced by the weight 39, in consequence of which the yarn is tensioned to a level depending upon the weight 39, which is selected to produce a constant tension which preferably is approximately 80 percent of that which the yarn is able to withstand without breaking.

The arrangement of the rolls 22 through 26 is such that each successive length of yarn preferably is immersed in the mercerizing solution 36 for about ninety seconds. The mercerizing solution is conventional (a 25 percent solution of sodium hydroxide plus agents to wet out the yarn) and, is maintained at room temperature. The arrangement of the rolls 26 through 30 is such that each successive length of yarn is immersed in the solution 38 for a period of time sufiicient for neutralizing the solution 36 which the yarn picked up while passing through the compartment A. The neutralizing solution 38 may be acid, but water might be used.

After the yarn passes through the nip of the rolls 30, it passes through the heater 31. The temperature of the heater must not be high enough to injure the material, and the yarn must not be subjected to the heat for an excessive period of time. Preferably, when the yarn 4 leaves the heater, its moisture content should be at least equal to its moisture regain, and its pH should be approximately what it was before it entered the mercerizing solution 36.

If desired, the tank 34 may be provided with several additional compartments, and the, yarn ends may be passed successively through the treatment solutions in the several compartments. For example, there may be a treatment solution for tinting the yarn ends for identification, a treatment solution for dyeing, and a liquid for a resin treatment.

Although, as illustrated, one yarn end is processed at a time, it will be understood that in practice my individual yarn end mercerizing may involve simultaneously processing many yarn ends. In this event, a roll 21 may be provided for each yarn end, and a drag inducing device may be provided for each roll 21. Thus while the several yarn ends 16 are drawn from cones 14 by the rolls 30, each yarn end is tensionedindependently of the others by reason of the drag on the associated roll 21 working against the yarn drawing effort of the rolls 30. Thus tension in the several yarn ends is maintained uniform and at the desired level.

The stretchable core yarn may be any filamentary yarn, natural or synthetic, which is stretchable to some appreciable degree. The core yarn may be a filamentary elastometric yarn, such as rubber or spandex (Lycra by E. I. du Pont de Nemours & Co., and Vyrene by US. Rubber Co.). It may be a bulk yarn of the crimp type, such as Textralized or Banlon. It may be a stretch yarn of the conventional type, such as Helanca, or of the false twist type, such as Superloft or Flufion, or of the nontorque type, such as Agilon. The staple fibers may be of any natural or synthetic material.

In the event of a break in the yarn, the stop motion acts to terminate operation. The tank is lowered, as shown in broken lines, the machine rethreaded and the tank raised again. If the core yarn is not spandex, no appreciable loss will occur due to overexposure to the mercerizing solution. If the core yarn is spandex, the loss will be negligible.

It will be understood, of course, that the method and apparatus hereinabove described is susceptible to various changes and modifications which may be made without any departure from the general principles or real spirit of the invention. For example, the positions of the rolls 26 and 30 may be reversed because while it is essential that the yarn be tensioned during its passage through the mercerizing solution 36, it is not necessary for it to be tensioned during its passage through the neutralizing solution 38.

What is claimed is:

1. A continuous method of mercerizing stretchable composite yarn comprising a continuous-filament elastomeric core having staple fibers thereabout, said method comprising the steps of:

(a) continuously drawing the composite yarn from a source through a mercerizing solution at a rate of at least 100 yards per minute to maintain the composite yarn immersed in the mercerizing solution for the order of ninety seconds;

(b) maintaining a constant drag of such magnitude on the yarn at a point upstream of the mercerizing so lution that the yarn in the mercerizing solution is stretched to the order of of its capacity;

(0) continuously drawing the mercerized composite yarn through a neutralizing solution;

(d) continuously drying the yarn, and then (e) packaging the yarn.

2. The method according to claim 1 characterized in that the mercerized neutralized composite yarn is continuously dried by drawing the yarn through heater means.

3. The method according to claim 1 characterized in that the composite yarn is drawn through the merceriz- 6 ing solution at a rate of the order of 150375 yards per References Cited minute. NI ED TAT ATEN 4. The method according to claim 3 characterized in U T S ES P TS that the mercerizing solution is a 25% solution of sodium 3334482 8/1967 Neel 28 76 hydroxide plus wetting agents.

5. The method according to claim 4 characterized in 5 JOHN DAVID WALSH Pnmary Exmamer that the mercerizing solution is at room temperature. US Cl. XIR

6. The method according to claim 5 characterized in that the elastomeric core is spandex.

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