US2679072A

US2679072A - Method of producing a staple fiber yarn

Info

Publication number: US2679072A
Application number: US163882A
Authority: US
Inventors: Harry E New
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1950-05-24
Filing date: 1950-05-24
Publication date: 1954-05-25
Anticipated expiration: 1971-05-25

Description

May 25, 1954 H. E. NEW

METHOD OF PRODUCING A STAPLE FIBER YARN Filed May 24, 1950 A ass #10? /en 77/; 0/ 6fap/e//'/b 2/5 IN V EN TOR. HARRY E. NEW BY ATTORNE Patented May 25, 1954 UITED STATES PATENT OFFICE METHOD OF PRODUCING A STAPLE FIBER YARN Harry E. New,

American .Viscose Corporation,

Swarthmore, Pa., assigncr to Wilmington,

6 Claims.

This invention relates to the production of artificial yarns and fabrics having increased resilience. More particularly the invention relates to a method of drafting an artificial filament strand, such as a sliver or roving, in such manner that yarns and fabrics produced therefrom have increased resilience and luster.

In the manufacture of yarn from staple fiber, it is the practice to form the fibers into a strand, sliver, or roving which in turn is drawn and twisted into a yarn. It .is a common practice to subject textile fibers to a series of drafting or drawing operations which are designed especially to bring the fibers into a more nearly parallel relationship sothat when the final strand of loosely assembled fibers is twisted, the maximum strength of the fibers may be utilized.

A typical drawing mechanism used in a spinning frame comprises several pairs of drawing rolls, usually three or four, each pair including a lower and a cooperating upper roll, and the pairs being arranged, one in advance of the other, so that they act successively on a continuous strand or sliver guided through them. In a common arrangement, each pair is revolved at a higher speed than the pair immediately preceding it so that during the travel of the sliver the fibers of which it is composed are drawn out, the sliver is attentuated, and the fibers are brought into a more nearly parallel relationship.

It has now been found that increase in the parallel relationship or straight nature of the fiber when twisting into yarn results in a yarn which is not only stronger but also has increased resilience and luster and fabrics made therefrom have increased crispness which is often desirable.

Rayon staple, including viscose, or acetate, and other synthetic fibers, are normally made with sufficient crimp in the fiber to facilitate fiber cohesion during the carding and subsequent mill spinning operations, such as on the cotton system for example. The crimp may be formed by immersing the fibers in hot water or by any other method suitable for the particular fiber to be crimped. Short length fibers, for example 1 to 3 inch staple length, normally processed on the cotton system, require considerable crimp and fiber cohesion in order to assist the fibers in holding together during processing. Other systems of spinning, such as the worsted, silk and linen systems, which use fibers from 3 to inches in length, do not require as much crimp in the fiber in order to facilitate processing. Further, it is well-known that long fibers, which are processed on the worsted, linen and silk systems,

give a yarn which is considerably firmer than the yarn produced on the cotton system using shorter length staples. This firmness is attributed to low drafting and longer, straighter fiber in the yarn.

It has long been the desire to successfully produce a yarn having this same firmness from short or regular rayon staple fiber on the cotton system. Double carding, that is passing the crimped regular staple rayon fiber through the carding machine twice, has been proposed in order to produce a rayon staple yarn having increased resilience. However, this procedure is undesirable due to increased cost and excessive staple breakage, resulting in increased neppiness of the yarn.

It is a general object of the present invention to provide a method whereby short staple fibers, of viscose, or acetate rayon, and other synthetic fibers, may be formed into a yarn on the cotton system having a firmness comparable to those produced on the worsted, linen and silk systems.

It is another object of the present invention to produce a yarn formed from artificial staple fibers which has increased resilience and luster.

It is another object of the invention to provide a method of producing a yarn from artificial staple fibers wherein all the fibers are in more nearly parallel relationship.

It is another object of the present invention to produce a yarn which when woven into a fabric imparts increased luster, resilience, and crispness to the same.

Other objects and advantages of the present invention will be obvious from the description thereof hereinafter.

The objects of the present invention are generally accomplished by setting the drafting rolls closer together in at least one stage of drafting than the minimum staple fiber length being processed and under low draft conditions in order to straighten or parallelize the fibers without breaking them. While this may be accomplished at any drafting operation, it is preferably done where the bulk of the stock is the greatest, for

example, on the drawing frame.

The term drafting rolls refers herein to any pair of rolls in a drafting system which nip or clamp the fibrous material being attenuated tightly between them so as to substantially determine the linear speed of the material as it proceeds between them and practically prevent any substantial slipping of the material through them. It will be understood that the expression draft as used herein is broad enough to include either or both or any combination of a longitudinal slipping of the staple fibers in the sliver as well as stretching or elongation of the individual staple fibers. Where the ratch between the draw rolls is less than the shortest staple fiber length, elongation of the fibers is inherent.

While the present invention is equally applicable to any type'of staple fibenvsuch-ascotton, wool, viscose and acetate rayon, synthet'ic fibers, and the like, the same will be described in connection with viscose staple fiber, but it should be understood that this is merely intended to be i1- lustrative and not limitative.

In accordance with the present invention, it is usually necessary that the machine draft be maintained at a degree or i-peroent'ajge less than the extensibility of the staple fiber in order to avoid fiber breakage. However, under normal drafting conditions, a certain amount of fiber slippage occurs, in which case a slightly higher machine draft, i. e., one higher than the extensiibilityof the staple fiber, may be maintained thus taking :into consideration, or compensating for, the :fiber slippage. Thus, when using viscose staple fiber, which has an extensibility in the :range of from 15 to 20% when dry and trom 13 to 2.2% when wet, in-accordance with the present invention, the actual draft should not exceed 15 to 18% in the drafting zone where the rolls are set closer together than the staple length. The drafting or drawingzone referred to herein may be defined as the 'efiective distance between the nipsofsucces'sive pairsof drafting-rolls, the-rolls "of each pair being adjusted with sufficient .pressure to minimize orsubst-antialiy eliminate fiber slippage. Such drafting rolls are to be distinguished from control rolls which are not intended to prevent slippage. It follows, therefore, that the term ratch, as used herein, refers to the lengthier drawing zone as defined above. It has been Zound, when processing viscose staple fiber, that maintaining a draft of 153 or 1.3% be ween two sets of drafting rolls at the drawing frame with a "rollsetting closer than the staple length, that a materially firmer yarn'is produced.

As an illustration of the present invention, the following specificexarnple is set forth. Regular dull 3 inch viscose staple rayon (BB-denier) was processed through cotton machinery using a standard organization for producing 16/1 yarn (since normal single-plyyarn runs "840 yards per pound, a 16/1 yarn is a sin leeply .yarn running 16 X 840 yards per pound or 13,440 .yards per pound l. Special roll settings and drafts were used-as follows and as illustrated in the accompanying drawing. A setting or ratch A (measured distance between the centers of the rolls) equal to 3% inches was employed be ween the pairs "of rolls amid, a setting B equal to 2' /2 inches between rolls 2 and 3, and a setting C ecjual to 3% inches between rolls 3 l. LA'dr'aft of 1114 to 115 was employed between rolls 2 fand 3, there being an overall-draft of 4.

A control sample was carried through using standard drawing roll settings a n'd, organization. In the control setting A was equal t'o'3 inches, setting B 3% inches, and setting '0 3 inches. An overall 01 l employed. When the two yarns so produced were woven into 'fabrics and evaluated it was fountlthat the former yarn, or the one ting the close roll settings a t-drawing produced a fabric having a firmer hand and a higher luster than the latter or control.

in another aspect "of the present invention, a higher humidity 'be maintained in the straightening zoneandjif desired, adrying zone processing on the cotton system.

t may follow the strai htening zone and heat may be applied in this zone. When employing a high humidity in the drafting zone, it is possible to draft higher and straighten the fibers more due to the fact that the staple fiber normally has a higher extensibility when Wet. However, the

stretch requirements or amount of draft should not exceedith'e extensibility properties of the fiber at operating relative humidity conditions.

By means of the present invention, it is now possible to obtain firm yarn and fabric effects (similar to those presently obtained. only by the use of long length fibers) from short length fiber Further, the present invention enables one to produce a yarn from short staple length fibers having greater yarn strength. Staple lengths as short as 1 /2 inches maybe so'processed. While it is desirable that staple fiber possess a slight criin it is possible to employ straight staple fibers in the present invention although the results are not as pronounced.

Among the many advantages of the present inventionmay be mentioned, in addition to those hereinbefore pointed out, the ease with which the method-is controlled. There is no additional cost over theregular cotton system of producing yarns. The present invention enables one to use staple fibers to produce yarn having increased resilience. Also, it enables one to produce yarns on the cotton system having worsted or spun silk system yarn characteristics.

As previously pointed-out, the roll setting will depend upon the length of the staple fiber being processed and the draft, on theextensibility of such fiber. Further, it'should be note-1 that the invention is applicable to any type of fiber draftingordrawing mechanism.

It should be understood that changes and variations may be made Without departing from the spirit and scope of the invention as defined in the ap-pended"claims.

ll. A l'lfl9l3l510flf0l prod sing a staple fiber yarn comprising passing 'a roving of 3-inch viscose rayonstap-le fibers through a drafting zone under a draft of about 1.14 to 1.15 and wherein the pairs of drafting rolls the ends of the zone are spaced 2%; inches apart, said staple fibers having 'an extensibility above 15%.

2. The method of producing staple fiber yarn which comprises "the steps of passing a sliver of staple fibers through s. drafting zone having a ratch less'than the minimum staple fiber length, and drafting the sliver .in said zone to impart an elongation to su'bstantiallyall of the fibers in the sliver.

3. An improved :draiting method for staple fiber sliver comprising steps of compressing :asliver of staple fiber yarn between-roll nips having 'a r'at'ch not greater than the length of the individual staple fibers in "the sliver, and simultaneously elongating substantially all of the fibers injthes'liverbetween said nice.

4. An improved drafting method for staple fiber sliver comprising the steps of compressing a sliver of staple fiber yarn between roll nips having a ratc'h not greater'than the length of the individual staple fiber yarn which comprises stretching a sliver of staple fibers in an amount less than the extensibility of the individual fibers in a drawing zone having a ratch not greater than the length of the shortest individual staple fiber in the sliver to elongate the fibers in said zone.

6. The method of producing a staple fiber yarn which comprises the step of continuously elongating in a single drafting zone substantially all the individual staple fibers in a sliver of staple fibers passing through said zone.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name I Date Owen Dec. 25, 1928 Draper July 29, 1930 Reynolds Apr. 15, 1941 Kettley June 3, 1941 FOREIGN PATENTS I Country Date Great Britain Feb. 20, 1918