US2296394A - Manufacture of novelty artificial yarn - Google Patents

Description

p 1942- I D. T. MELOON 2,296,394

MANUFACTURE OF NOVELTY ARTIFICIAL YARN Filed Nov. 22, 1940 D and E1 T..ME1 DDTL Patented Sept. 22, 1942 MANUFACTURE OF NOVELTY ARTIFICIAL YARN Daniel T. Meloon, Buffalo, N. Y., assignor to E. E. du Pont de Nemours & Company, Wilmington, DeL, a. corporation of Delaware Application November 22, 1940,.Serial No. 366,778

2 Claims.

This invention relates to the manufacture of a yarn or ribbon comprised of continuous filaments of artificial thermoplastic material, having sharply defined alternate stretched and unstretched portions along its length. More particularly the invention relates to a yarn or ribbon comprised of continuous filaments of cellulose acetate h'aving sharply defined, alternate stretched and unstretched portions along its length; to a process for heat-treating and stretching by a substantially uniform stretching force a yarn or ribbon of continuous filaments of cellulose acetate, at intervals along its length; and to apparatus useful in carrying out the process.

Several methods have heretofore been proposed for producing a novelty yarn of cellulose acetate or like artificial material, comprised of continuous filaments made up of alternate stretched and unstretch'ed portions. One method consists in applying variable tension to the freshly spun filaments of the yarn while they are still in the plastic stage. The second method consists in softening pre-set yarn by the continuous or intermittent application of a softening agent or solvent, and then applying a stretching force, either intermittently in the case of continuously softened yarn, or uniformly in the case of an intermittently softened yarn. The yarn produced by either of these two methods is characterized by a gradual rather than a sharp, i, e., abrupt, change in the denier of the yarn between the stretched and the unstretched portions.

An object of this invention is to produce a novelty yarn of thermoplastic artificial material, which yarn shall be comprised of alternately disposed and sh'arply defined stretched. and unstretched portions. Another. object is to produce a continuous yarn of cellulose acetate comprised of alternate and sharply defined stretched and unstretched portions. A further object resides in a process for intermittently softening and applying a uniform stretching force to yarn of cellulose acetate or like artificial thermoplastic material. A still further object is to provide apparatus especially suited for the softening treatment and uniform stretching of a continuous yarn or ribbon at intermittent points along its length. These and other objects will more clearly appear hereinafter.

I have found that if a continuous yarn or ribbon of an artificial thermoplastic material, cellulose acetate for example, is softened at intermittent points along its length, by heat alone, and subjected to a uniform stretching force, a novelty yarn is produced which is characterized by sharply defined, i. e., abrupt, change in" denier from the stretched to the unstretched portions of the yarn.

I have further found that a driven heated roll having its surface indented with longitudinally extending channels, or other surface modification which will serve to provide longitudinally extending, alternate hot and cold zones about the cylindrical surface of the roll, is. best suited for the intermittent application of heat to the yarn and also allows for the simple application to the yarn of a uniform stretching force.

The invention is best understood by reference to the following description and accompanying drawing wherein Fig. 1 is a diagrammatic illustration of a preferred arrangement of guide, heating,and stretching means. Figs. 2, 3 and 4 show in end elevation, and Figs. 5 and 6 show in cross section, various modifications of hot roll structure,

With reference to Fig. 1, a thermoplastic yarn, such as cellulose acetate yarn, possessing a mild twist or more preferably no twist at all, and of any reasonable denier and comprised of a plurality of filaments, is unwound from a supply package (not shown) and passed through a tension device d, and then passed around roller A and finally around guide e. After leaving guide e, the yarn is wound a plurality of times around roller B, after which the yarn is wound up in any suitable manner. Tension device d is ad- Justed in such a manner so as to feed the yarn onto roll A with a very slighttension. Roll A is provided with longitudinal channels 0 which may be only 1 or 2 in width, or in some cases the width of the channels may be as much as 5, 10, 20 or more degrees. The cylinder A is heated in any suitable manner, for instance, by electrical means, high pressure steam, or vapor or liquid to a sufliciently high temperature to effect a suitable softening of the yarn in contact therewith. Roll A is driven in a counterclockwise direction, as indicated. Roller f is positioned with respect to roll B in such a manner as to prevent the yarn from tracking on itself in making the plurality 'of passes around roll .3. By suitably adjusting the ratio of peripheral speeds of rolls A and B, the yarn may be subjected to any reasonable and desirable uniform degree of stretch such as 2, 5, 10, 20, or more times its original length in passing from one .roll to the other. The yarn passing around roll A becomes uniformly heated and softens except for the small lengths that bridge the channels 0, which remain relatively cool, un-

softened and therefore unstretched-in traveling from roll A to roll B.

If desired, 1, 2, 3 or more channels may be formed in the surface of the hot roll A. The channels may be of uniform width and uniformly spaced-as in Fig. 2, or of uniform width but non-uniformly spaced as in Fig. 3, or of non-unlform width but evenly spaced as in Fig. 4, in order to prodiice any desired arrangement of beads or flakes, i. e., unstretched portions, in the final yarn. The spacing of the flakes may further be effected by changing the diameter of hot roll A. Furthermore, two or more hot rolls may be used in series. In such' a case, the second hot roll would be driven at a greater peripheral -speed than the first hot roll, thereby imparting a small amount of stretch between the first and second hot rolls. The final stretch would be applied be-, tween the second hot roll and roll B. Through the use of a number of hot rolls driven at prog'ressively'greater peripheral speed, a non-repeating pattern of stretched and unstretched portions could be imparted. to the yarn;

In Fig. 5 is shown in cross-section an alternate form of the hot roll A, the interior of the roll being divided into two chambers Sand T, between the twochambers an insulating layer, as shown by the heavy black line, is alsopreferabl'y incorporated. By introducing a heating medium into chamber Sv and a cooling medium into chamber T, a portion of the cylindrical surface may be heated while another portion is cooled. ,By suitable selection of the degree of heating and cooling of these two sections of the cylinder, an uneven-denier novelty yarn may be produced by substituting this cylinder for cylinder A in Fig. 1.

Fig. 6 shows in cross-section another form of the hot roll A, in which the longitudinal channels of the hot roll are filled with a suitable heat insulating medium h producing thereby a temperature differentialbetween the surface elements of the hot roll and the insulating medium of such an amount which will not allow the 'yarn to have varied gradually along the yarn length. The use of the yarn produced by the herein described process, the thick and thin portions of which change abruptly along the length of the yarn, makes possible an unusually large assortment of pleasing fabric effects.

By suitably adjusting the relative speeds of the rolls,the temperature of roll A, the size and location of the channels, or equivalent cooling area, and the number of hot rolls almost any conceivable pattern may be. produced. Due to its simple construction, the apparatus is easily and cheaply maintained and is economical to operate. I

The following specific examples further illustrate the invention.

Example I A 3000 denier cellulose acetate yarn (about 54% combined acetic acid) containing 150 filaments and possessing no twist was fed on to a and unstretched portions, was 600 denier while the average denier of the unstretched portion was approximately 3000 and that of the stretched portion was approximately 475. The length of the nub was inch and the distance between nubs was approximately 3 inches, thus causstretch while in'contact with the insulating medium, ,whereas the yarn will stretch readily while in contact with the hot roll surface. Heat insulatin'g' media which may be used for this purpose may be such materials as magnesia, asbestos,

I chalk, 0r silicious-cements or lutes of various types. I

While the yarn produced according to the process previously described may have a decidedv variation. in denier, an additional effect may be produced by imparting a twist of such a magnitude to the processed yarn as to cause the twist 'tobecome localized only in the thinner and stretched portion of the yarn. In this manner, little or no twist is imparted to the heavy denier,

" unstretched portions of the yarn, resulting in a variation in luster between stretched and unstretched portions which whenproperly regulated ing a repeat pattern to be formed every 3% inches along the length of the yarn. After stretching, the yarn was wound up on a suitable bobbin and then twisted to' the extent of 4 turns per inch. In the resulting twisted yarn, all of the twist was localized in the stretched portion, while no twist occurred in the nub. The resulting thick.

and thin yarn was very attractive in appearance and was useful in producing novelty fabrics.

Example I! A 600 denier, 30 filament cellulose acetate yarn (about 54% combined acetic acid) possessing no twist. was passed over the hot roll described in Example I. The peripheral speed of the hot roll was 248 inches per minute, while the peripheral speed of thetake-up roll B was620 inches per and controlled enable fabrics of unusual and pleasing appearance to be produced.

The yarn produced by the herein described process differs from that obtained through the use of known methods, such as stretching the solvent swollen yarn, in that the denier changes from the stretched to the unstretched portion in a sharp and abrupt manner. Yarns which have been treated at interyals along their length with a swelling agent, and then stretched under a uniform tension, or yarns which have been treated uniformly along their length 1 and stretched with a varying tension, have resulted minute. The roll temperature was approximately 245 C. The overalldenier of the yarn was 240, While the average denier of the unstretched portion was 600, and the average denier of the stretched portion was 200. A repeat pattern of thick and thin portions occurred every 1% inches along thelength of the yarn.

Example III of the unstretched portion of the yarn was approximately 200, while that of the stretched'porin products, the thick and thinportions of which tion was approximately 86. The repeat. pattern 5 of the thick and thin yarn occurred every 1 inches along the length of the yarn.

Example IV however, of the hot roll were filled in with pieces of chalk which acted as an insulating material.

The temperature of the heated portions of the roll was about 245 C. The denier characteristics of the stretched yarn were the same as those given under Example I. A repeat pattern of thick and thin portions occurred every 3% inches along the length of the yarn.

It is understood of course that the invention is not limited by the exact description herein but comprehends rather all modifications and equiva-' lents falling within the spirit and terms oi! the definition of the invention set out in the following claims. a

I claim: v

'1. Process for the production of artificial yarns which comprises heating yarn comprised of filaments of artificial thermoplastic material,'to the softening point at intervals along its length, and applying substantially uniform stretching tension thereto so as to stretch the yarn at the softened intervals, whereby to produce artificial yam having sharply defined alternate stretched and unstretched portions along its length.

2. Process tor the production of artificial yarns which comprises heating yarn comprised of preset filaments of cellulose acetate, to the softening point at intervals along its length, and applying substantially uniform stretching tension theretoso as to stretch the yarn at the softened intervals,

whereby to produce a yarn having sharply defined stretched and unstretched portions along its length. v DANIEL T. MELOON.

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