US2721440A - Process for producing direct spun yarns from strands of continuous fibers - Google Patents

Description

OCt. 25, 1955 H. E. NEW 2,721,440 PROCESS vFOR PRODUCINO DIRECT sPUN yARNs FROM sTRANDs OF CONTINUOUS FIBERS Filed Feb. 15, 1951 INVENTOR- Arron/v4- United States Patent() PROCESS FOR PRODUCING DIRECT SPUN YARNS FROM STRANDS OF CONTINUOUS FIBERS Harry E. New, Swarthmore, Pa., assignor to American Viscose Corporation, Wilmington, Del., a corporation of Delaware Application February 13, 1951, Serial No. 210,715

4 Claims. (Cl. 57--2) This invention relates to a method of producing high quality spun yarns comprising short or-long staple fibers .from untwisted strands comprising continuous filaments 1n a continuous operation. i

The primary object of this invention is to provide an improved process for producing high quality spun yarns from strands or bundles comprising continuousfilaments or semi-continuous (i. e. long length) filaments by a direct-spinning procedure involving stretching or drafting the bundles to break the filaments into shorter lengths. Another object is to provide an improved process for producing novelty direct spun yarns or yarns duplicating those produced on the cotton, woolen, worsted, silk and linen systems as desired. Another object is to provide an improved process for producing direct spun yarns with sufficient extensibility to promote good subsequent processing. Another object is to provide an improved process for producing a direct spun yarn from filaments that have been stabilized prior to twisting or spinning into yarns. Another object is to provide an improved process for producing yarns from either a small, medium or large number of fibers into high quality yarns in one continuous operation.l Another object is to provide an improved process for producing high quality yarn by controlling the amount of draft at each processing point. Another object is to provide an improved process for producing high quality yarns comprising fibers reduced V latinmail oct. v25,1955

ice

produced from the yarns, which is in contrast with staple yarns spun on the cotton system wherein irregularities generally occur only about two to three'inches apart so that the irregularities are not noticeable in fabrics made from such yarns. Also, the number of bers in the starting bundle or strand which it has been possible to reduce in spinning directly into yarn has been limited pletely overcomes these disadvantages and limitations and enables. one to make a satisfactory spun yarn to desired specifications.

vThe invention will be more easily understood by reference to the'following detailed description and the drawing in which:

Figure l is a diagrammatic representation in side elevation of one embodiment of the invention,

Figure 2 is a diagrammatic representation in side elevation of another embodiment of the invention, and

Figure 3 is a diagrammatic representation in side elevation of` a third embodiment of the invention.

Figure `1 illustrates one modification of the invention that is adapted particularly `to the handling of strands of large total denier, lsuch as 100,000 to 250,000 total denier. The continuous strand 3 comprises, as it enters the equipment from the left as viewed in Figure l, a plurality of continuous filaments in an untwisted condition or extremely long filaments either of synthetic or natural character, such as flax, wool, or ramie, in an untwisted condition or in a condition of extremely low twist to staple length from l to 20 in length. Another object is to provide an improved process for producing high quality yarns from fibers without expensive treatment with special lubricating and anti-static finishes. Another object is to convert yarns of two or more kinds of fibers into high quality uniformly blended yspun yarns. Other objects and advantages will appear hereinafter from the description, drawing and claims. f

The objects are accomplished by the following invention wherein the strand or bundle comprising continuous or semi-continuous fibers enters a drafting and reducing area where the fibers are broken to the. desired vlength while maintaining optimum draft conditions, then passes into a control area for shrinking or stabilizing, as desired, then passes directly into a drafting area or series of consecutive drafting areas, and then is twisted into yarn which may be collected by winding into a package.

Direct spun yarns as referred to herein are those produced directly from strands of continuous filaments or semi-continuous fibers by reducing the long filaments or fibers to suitable staple length Without destroying the continuity of the strands, that is, without cutting to loose staple fiber and then opening and carding to produce another strand of shorter fibers. These yarns as conventionally produced have certain peculiarities that make them undesirable at the present time for satisfactory knitting, weaving as Warp and other general textile usage. The appearance and uniformity of the yarn has been found unsatisfactory because the irregularities generally occur widely spaced apart, such as about twelve inches or more apart, and they are quite noticeablein fabrics such as not yover 1/2 turn per inch. The strand 3 passes around the l,roll 4 and between the nip of rolls 5 and 6 and enters the drafting and reducing zone which extends from such rolls to the nip between rolls 7 and 8. The rolls 7 and 8 are driven at higher speed than rolls 4, 5, and 6 so that the filaments are stretched beyond their breaking ylimit Aas they pass through the reducing zone. The draft for this purpose varies between 1.2 and 2.5 depending on the extensibility of the particular filaments being handled, and is preferably 1.3 to 2. As they pass through the zone, they may be subjected to cutting and shearing forces such as by means of the cutters 9 and 10 provided with radially outwardly projecting blades 11. Preferably, these rotors extend diagonally across the width of the filament bundle or strand and they serve to predetermine the position of breaking ofa large proportion of the filaments. These blades may be in the form of sharp-edged knife blades, or roughor jagged-edged strips which tend to weaken the filaments as the latter pass therebetween. If desired, the blades maybe moistened with a liquid weakening agent, such as a solvent or swelling agentfor the substance ofthe filaments, in which event, they may be sharp or smooth as desired.

- After passing beyond the reducing stage, the bundle of shorter fibers proceeds through a condensing guide or funnel 12 and may thenproceed directly to a final drafting zone or, if desired, tothe first of a series of drafting Zones, or to a conditioning zone in advance of one or more drafting zones. As` shown, the condensed strand passes between rolls 13 and 14 which feed it into a conditioning zone from which it is discharged by the delivery rolls 15, 16 and 17. Rolls 13to 17- may be driven at the same linear peripheral speed as rolls 7 and 8 or, if desired, draftingrnay be performed in either or both ofV the spans or passes of the strand between adjacent pairs of rolls. 1f desired, rolls 13 and 14 may be omitted in which case the rolls 16 and 17 may operate at the same speed as rolls 7 and 8. Preferably, however, in all ernbodiments of the invention, there is some draft in the conditioning zone, which may vary from 1.09 to 1.7 but is preferably 1.3 to 1.7. When rolls 13 and 14 are omitted, the entire span of the bundle between rolls 7, 8 and rolls 16, 17 may be subjected to the humidifying means, the bundle being condensed early in the humidifying stage.

In the conditioning zone, a duct 18 is disposed beneath the span or stretch of the strand and another duct 19 may be disposed above the strand. A gaseous conditioning medium may be introduced by either of the ducts, such as by duct 18. In the latter case, duct 19 may serve to withdraw the conditioning medium for refreshment and recirculation. If desired, the conditioning medium may be introduced through nozzles 20 connected to a common header 21. This latter arrangement is particularly useful when the conditioning medium is a liquid since in that case, it is necessary to atomize or vaporize the liquid before it strikes the filamentary strand. By so atomizing such a liquid, serious soaking of the strand, which would necessitate involved drying equipment, is avoided. Atomization controls the application of the conditioning agent and ducts 13 and 19 may serve to withdraw the excess, for recovery if such is desired. From roll 15, the strand proceeds through one or more drafting zones which may be provided with any suitable form of drafting equipment. As shown, a pair of rolls 22 and 23 driven at higher speed than roll 15 serves this purpose. From the rolls 22 and 23, the strand proceeds through a guide 24 and is twisted during collection upon a bobbin 25, such as in a ringtwister comprising the ring rail 26 and the traveler 27 by means of which the twisted yarn is wound upon the bobbin in conventional fashion.

The system of the present invention may be applied to the production of direct spun yarns from any continuous filaments, such as those of silk, synthetic filaments, such as regenerated cellulose rayon, cellulose acetate rayon, nylon, polyvinyl resin yarns, casein or other proteinaceous fibers, etc. Depending on the particular nature of the material from which the fibers are formed, different weakening agents may be applied to the strand in the reducing zone by the blades 11. For regenerated cellulose rayon, water alone is adequate. A solvent may be applied, however, and in the case of the other types of yarns, such as cellulose acetate, the application of a solvent, such as acetone, is suitable. Also, in the conditioning zone, various conditioning agents may be applied. EX- amples are steam, hot air of high humidity, or atomized shrinkage agents, for example, materials which have a solvent or swelling effect but are extremely volatile, such as acetone for cellulose acetate. To illustrate the operation of the system, the following details for the handling of a bundle of untwisted continuous filament-regenerated cellulose rayon having a total denier of 150,000 are given: In the reducing zone, the ratch (distance from center of roll 8 to center of roll 6) was l0 inches and the draft was 2. No weakening agent was applied to blades 11. The draft was 1.3 in the conditioning zone and in the next drafting zone, a ratch of 10 inches and a draft of 30 was employed. The humidity in the reducing zone and the second drafting zone was 50% at ordinary room temperature and the conditioning agent applied in the conditioning zone was heated air at 100 F. and about 80% relative humidity.

Figure 2 shows a modification of the embodiment of Figure l in which the strand discharged from rolls 7 and 8 passes through means for separating and drawing out the fibers to the form of a sliver or top, such as the gill box 28.

In Figure 3, an embodiment is shown which is particularly suitable for handling filamentary bundles of low total denier or medium total denier. In this embodiment, the strand of continuous filaments passes about rolls 4, and 6, the lowermost of which is provided with an apron 7a which is driven thereby and proceeds under the path of travel of the strand and around a roll 6a which is immediately adjacent the higher speed drafting rolls 7 and 8. The reduced strand is supported by the apron 8a which extends around roll 8 and auxiliary roll 8b. In the conditioning zone, a conditioning agent may be applied by means of nozzles 20 or duct 19 as in the embodiments of Figures l and 2, ducts 18 and 19 serving to withdraw any excess as in the previous embodiments. From the apron 8a, the strand proceeds through a condenser guide or funnel 12 between rolls 13 and 14, the lowermost 14 again being provided with an apron 14a which passes also about the roll 14b and serves to support the strand in its passage between rolls 13, 14 and rolls 16, 17. Roll 17 is provided with an apron 17a which passes also about roll 17b adjacent the delivery rolls 22 and 23 from which the strand passes through a guide 24 into the twister which may be the same construction as that shown in the other embodiments. In this embodiment, the strand may be drafted in each of the four stages between successive pairs of rolls. Filaments in the strand are broken in the first stage and additional drafting is effected in subsequent stages.

The conventional method of producing spun-yarns directly from continuous strand materials breaks and drafts the fibers in the same area. It has been found that the upper limit of draft possible in this area varies from 8 to 30 according to the count being produced. It is impossible to draft above 30 and still produce satisfactory spinning conditions. When draft above 30 is used extreme yarn unevenness results. Also, yarns produced by breaking and drafting in the same area have a wide variation in fiber length which is undesirable for most conventional textile usages. Likewise, in the reduction of heavy denier tow, for example, of 100,000 to 250,000 total denier, it has been found necessary to maintain a minimum amount of draft in order to produce uniform distribution of the fibers within the strand of material being processed. The draft during reduction for optimum results should be maintained approximately 1.3 to 2. This invention provides a means for maintaining optimum draft conditions in the reducing area and for immediately feeding the material into one or more controlled drafting zones to uniformly draft the fibers into spun yarn and subsequently twist and wind onto a package. By accomplishing a majority of the drafting of the fibers outside of the reduction Zone, a smooth uniform yarn may be produced. Also, by drafting the fibers in a continuous operation, the necessity for rubbing, mechanically crimping or otherwise promoting inter-fiber cohesion is eliminated. The character of the yarn may be made to resemble cotton, woolen, worsted, silk, linen or other systems of spinning by controlling the length to which the fiber is reduced and the amount of draft which is taken after the fiber is reduced.

It has been found that the lower the draft and the shorter the ber length, the more nearly cotton type spun yarns can be duplicated. Likewise, the longer the fiber length and the higher the draft, the more nearly wo-rsted yarns are duplicated. In the prior practices of producing direct spun yarns, it has been necessary to limit the length to which the fibers are reduced in order to have satisfactory spinning operation. The distance maintained between the feed and delivery rolls in the reducing zone is known as the ratc Heretofore, it has been necessary to use a ratch of 7 to 8 inches in order to give a satisfactory spinning operation. This invention makes it possible to use a ratch of 2 to 20 inches or longer, if desired, because the maintenance of the optimum draft condition in the reducing zone is made possible by the installation of a subsequent drafting means.

Direct spun yarns of viscose rayon as heretofore produced by the stretch-break method using the reducing system shown in Figure 2 and immediately twisting the strand discharged from such reducing zone, have an extensibility varying from 3 to 6 percent. A normal spun rayon yarn made from carded staple fiber by any of the conventional systems has from 8 to 20 percent extensibility. In order to have a yarn which will be satisfactory generally for weaving and knitting purposes, it is desirable and, for many purposes, necessary to have a yarn extensibility of 8 percent or more. Consequently, yarns heretofore produced by direct spinning processes are suitable only as filling yarns or for use as ply yarns or novelty type. This invention provides a means for introducing the fibers into a controlled area wherein the fibers may be treated with hot air, steam, water, chemicals or any other suitable means in order to cause them to shrink prior to being twisted into a spun yarn, whereby to increase the extensibility of the yarn. Also, if low extensibility yarns are desired or if yarn or fabric stability is desired, this invention provides the means wherein the fibers may be treated in a control area or areas prior to twisting into yarn to provide the desired extensibility of stability.

As before described the draft in the reducing zone should be maintained comparatively low if uniform distribution of the fibers is to be maintained. It is therefore impossible by the prevous direct-spinning techniques to spin certain yarns, such as 10s to l50s cotton count, from heavy denier tows, such as 50,000 or higher denier. At present, the total deniers of tows used to produce direct spun yarn in cotton count from 10s to l00s is in the 1000 to 5000 total denier range. This invention provides a means of increasing the total draft taken in a continuous processing operation to produce any desired count of yarn from any desired total denier type tow. This invention, therefore, makes it economically practical to spin yarns on the direct spinner at a cost which is competitive with conventional type spinning systems such as cotton, wool, etc. Heretofore, in order to produce satisfactory yarns from heavy denier continuous filament tows such as 100,000 to 250,000 total denier, it has been necessary to reduce the filament to the desired length and subsequently use several processes for drafting, twisting and doubling in order to spin a satisfactory yarn.

In the conventional method of direct spinning, the type of finish applied to the material is quite critical insofar as lubrication and anti-static and fiber separation properties are concerned. This invention eliminates the necessity of having specially prepared fibers and finishes in order to produce satisfactory spinning conditions. This is accomplished by reducing the draft in the reduction area and continuously maintaining the fibers under control during subsequent processing and drafting them as they proceed through the machine. By so doing, it is not necessary to mechanically crimp or rub or otherwise treat the fibers in order that they will adhere to one another as there are no subsequent operations. This invention provides a means for obtaining an intimate blending of two or more kinds or types of fibers prior to their being spun into yarn. This is accomplished by the control of the draft, condensing of the fibers after drafting, and the use of higher drafts than have been possible heretofore. In prior methods of direct spinning yarn, it was possible to obtain only a mock twist effect when blending two or more fibers.

I claim:

1. In the direct spinning of yarn having an extensibility in the range of 8% to 20% from a running bundle comprising substantially untwisted continuous filaments, the process consisting of the steps of breaking the filaments in a first zone under low draft not exceeding 2.5, directly passing the bundle of broken filaments into Aa second zone, relaxing the bundle in said second zone under a draft not exceeding 1.3, directing a fluid shrinking agent against the relaxed bundle in said second zone, and twisting the broken, drafted, and shrunk filaments onto a package.

2. In the direct spinning of yarn having an extensibility in the range of 8% to 20% from a running bundle comprising substantially untwisted continuous filaments, the process consisting of the steps of breaking the filaments in a first zone under low draft not exceeding 2.5, directly passing the bundle of broken filaments into a second zone, relaxing the bundle in said second zone under a draft not exceeding 1.3, directing a gaseous shrinking agent at elevated temperature against the relaxed bundlein said second zone, and twisting the filaments onto a package.

3. In the direct spinning of yarn having an extensibility in the range of 8% to 20% from a running bundle comprising substantially untwisted continuous filaments, the process consisting of the steps of breaking the filaments in a first zone under low draft not exceeding 2.5, passing the bundle of broken filaments into a second zone, relaxing the bundle in said second zone under a draft not exceeding 1,3, directing a uid shrinking agent onto the bundle in said second zone, directly passing the bundle into a third zone, drafting the bundle in said third zone, and directly twisting the bundle onto a package.

4. In the -direct spinning of yarn having an extensibility in the range of 8% to 20% from a running bundle comprising substantially untwisted continuous filaments, the process consisting of the steps of breaking the filaments in a first zone under low draft not exceeding 2.5, passing the bundle of broken laments into a second zone, relaxing the bundle in said second zone under a draft not exceeding 1.3, directing a humidifying and shrinking agent onto the bundle in said second zone under relaxed draft, directly passing the bundle into a third zone, drafting the bundle in said third zone, and directly twisting the bundle onto a package.

References Cited in the file of this patent UNITED STATES PATENTS 2,067,062 Oswald Jan. 5, 1937 2,077,283 Taylor Apr. 13, 1937 2,255,755 Bell Sept. 16, 1941 2,260,314 Halin Oct. 28, 1941 2,261,259 Kosslinger et al. Nov. 4, 1941 2,305,692 Halin Dec. 22, 1942 2,358,854 Elvin et al. Sept. 26, 1944 2,359,847 Hays et a1 Oct. 10, 1944 2,362,572 McLain Nov. 14, 1944 2,363,019 Schurmann et al. Nov. 21, 1944 2,366,785 Hays Jan. 9, 1945 2,464,882 Neisler, Ir. Mar. 22, 1949 2,497,511 Neisler, Ir. Feb. 14, 1950 2,602,964 Sisson July 15, 1952

Claims (1)

1. IN THE DIRECT SPINNING OF YARN HAVING AN EXTENSIBILITY IN THE RANGE OF 8% TO 20% FROM A RUNNING BUNDLE COMPRISING SUBSTANTIALLY UNTWISTED CONTINUOUSLY FILAMENTS, THE PROCESS CONSISTING OF THE STEPS OF BREAKING THE FILAMENTS IN A FIRST ZONE UNDER LOW DRAFT NOT EXCEEDING 2.5, DIRECTLY PASSING THE BUNDLE OF BROKEN FILAMENTS INTO A SECOND ZONE, RELAXING THE BUNDLE IN SAID SECOND ZONE UNDER A DRAFT NOT EXCEEDING 1.3, DIRECTING A FLUID SHRINKING AGENT AGAINST THE RELAXED BUNDLE IN SAID SECOND ZONE, AND TWISTING THE BROKEN, DRAFTED,A ND SHRUNK FILAMENTS ONTO A PACKAGE.

Images