US2366785A - Conversion of continuous filaments into staple fiber yarns or like products - Google Patents

Description

C. H. HAYS CONVERSION OF CONTINUOUS FILAMENTS Jan. 9, 1945.

INTO STAPLE FIBER YARNS OR LIKE PRODUCTS Filed June 10, I941 Patented Jan. 9, 1945 CONVERSION OF CONTINUOUS FILAMENTS INTO STAPLE FIBER YARNS OR LIKE PRODUCTS Claude Horrocks Hays, London, England, as- 4 signor to Celanese Corporation of America, a

corporation of Delaware Application June 10, 1941, Serial No. 397,370

In Great Britain June 28, 1940 .12 Claims.

This invention relates to the direct conversion of continuous filaments into staple fiber yarns or like products, especially by the application of a breaking tension to a bundle of continuous filaments.

Although continuous filaments can be cut into staple fiber and spun, by methods appropriate to the length of the fiber, in a similar manner to naturally occurring fibers such as cotton, wool, linen and so on, the operation involved in converting the continuous filaments to a finished yarn involves a long series of steps on many different kinds of machines, and is therefore costly both as regards labour and in capital outlay on machines and buildings. With the development of commercial interest in staple fiber yarns of artificial continuous filament origin, much thought has been given to the more direct conversion of the continuous filaments. It has, for

instance, been suggested to pass a bundle of continuous filaments through the drafting rollers of a drawing frame, which, instead of pulling separate fibers as in the case of cotton, wool, and the like, have to apply sufiicient tension to break the filaments in the bundle. The rollersare thus called on to grip the bundle sufflciently for the necessary breaking tension to be ,applied, and U. S. Patent No. 2,030,252 particularly describes the use of lntermeshing grooved rollers for the purpose of causing the bundle to follow a sinuous path at the gripping points, so as to avoid either slipping of the rollers on the bundle or cutting of the bundle as a whole by any crushing action of the rollers.

Another method, which has achieved considerable commercial importance, employs the principle described in U. S. Patents Nos. 1,959,142, 2,077,078 and 2,077,079, of passing a continuous filament bundle between two surfaces, oneat least of which is a cutting surface, e. g. a roller with sharp-edged flutes, pressure between the surfaces and differential speed between the filaments and the cutting surface causing the filaments to be severed into fiber by a cutting action. The method does not depend on any drafting action on the bundle as its filaments are being converted into fiber, and therefore has the advantage that the size of' the final fibrous product can be made substantially equal to that of the original continuous filament bundle, and also that the filaments are cut-which substantially preserves their original extensibility. This is of importance in the production offibrous threads of light counts or denier. The method also results in a very even thread. It, however, necessitates the use of special cutting surfaces, such as the fiuted rollers mentioned above.

It has now been found that a much-improved yarn can, be produced directly from continuous.

filaments by the use of two pairs or sets of drafting rollers of the kind used for the drawing of.

natural staple or cut fiber, provided that the f rollers are driven so as to have a high draft, 1. e.,,

at least 10-15 times, and preferably 20, 30, 40, 50

or 60 times or more, the weight (1. e., counts or denier) of-the initial bundle being appropriately 10-15 or preferably 20, 30, 40, 50, 60 or more times as large as that desired in the final prod uct. Unless I used drafts of at least 10 times, I

have not found it possible successfully to convert the continuous filaments into staple fiber. With lower drafts, abnormal loading hadto be applied to the rollers, tending to damage the. rollers and resulting incrushing of the filaments and-breakdown of the operation; withlesser loading, breakdown occurred by reason of slip. I therefore regard a draft of 10 times as critical, such a draft, and drafts of the higher order mentioned, making it possible to use loadings that are nor-. mal in corresponding draw-roller systems em ployed for drawing staple fiber.

The loading of the first draw rollers, which are called on to grip that initial bundle, maybe greater than that of the second rollers, which have to break successive filaments in the bundle.

The usual adjustment provided in drawing heads may be used to apportion the loading. It is preferable for the second rollers to be of substantial diameter, in order to reduce any tendency to licking of the drafted fibrous product.

The maximum fiber length produced depends in some degree on the spacing (the reach) of the rollers, and the amount of the reach may therefore be used to determine the character of the product. Although reaches down to 5" may be employed, fine quality products call for longer reaches such as 6" to 10" to be used, and for most purposes even longer reaches such ,as 14",16", 18" and 20 are the most advantageous.

The process according to the invention lends itself to the production of a wide range of fibrous products, the size of the initial bundle of continuous filaments being chosen (in accordance with the high draft employed) "to yield coarse threads of say 800-2000 denier, or finer threads down to say 100, 55, 45, or 30 denier, or threads of intermediate denier, say 450-500 denier. 'Thus, the initial bundle maybe 1000-2000 denier for reduction in asingle step to fine deniers of the.

ate and cellulose aceto-butyrate.

breaking step may, however, be subjected to simple drafting in a second operation, using draw roller spacings slightly in excess of the maximum fiber length. In this way, a 6000 denier bundle may be reduced to say 50-55 denier or less.

The yarn produced is very evenin character and closely resembles a spun yarn produced by the longer sequence of operations necessary with natural staple fiber. The final yarns may be smooth and substantially free from beard. If, however, the operation is carried out on a worsted spinning machine, a product closely resembling a yarn made from natural fibers is obtained.

The initial bundle should be such that breaking tension can be readily applied to the individual filaments. If, therefore, it is built up from smaller threads or bundles, these should contain little or no twist. Likewise, there should be no size or lubricant that might tend to make the filaments agglomerate.

Very good results are obtained by using artificial filaments of cellulose ester basis that have been stretched, e. g. in the presence of moist steam or hot water, so as to have a high strength, say 4.5 grams per denier or upwards, or stretched and saponified so as to be still stronger, say 6 grams per denier or upwards. Although such stretched filaments may have for certain purposes a somewhat low extensibility, this is no disadvantage, since extension beyond the breaking point itself reduces the extensibility of unstretched filaments from about 23-25%, to much the same figure, i. e. 6-10%. Examples of cellulose esters 'of which the stretched filaments may be formed are cellulose acetate, formate, propionate, and butyrate, cellulose acetate-propion- The filaments may be shrunk after stretching; a shrinking treatment may also be applied to the materials after drafting according to the invention. Strong yarns having initially a cellulosic basis may also be used, as for example regenerated cellulose yarns; such yarns may be subjected to stretching after coagulation or during a. late stage of coagulation in the spinning process in which they are formed. The invention is also applicable to the treatment of stretched polyamide .filaments, and generally to any synthetic continuous filaments. Thus, the invention is also applicable to the conversion into staple fiber threads of artificial filaments of normal character, i. e. of normal strength, e. g. ordinary cellulose acetate or other cellulose ester and ether filaments or viscose or cuprammonium filaments, these materials working very well under the conditions already mentioned of starting with a large bulk and reducing this by very substantial draft.

The initial filaments may be lustrous (bright) or delustered, in accordance with the requirements of the final yarn, especially if the desire is to simulate natural yarns having brightness or dullness as a characteristic. Pigments,

which can be incorporated in various proporaeearcs tions, are particularly useful in controlling the degree of dullness.

The operation according to the invention may be carried out on machines that are basically matically shown in the accompanying drawing, in

which Fig. 1 is a side elevation of a machine of the type used for spinning worsted or natural silk;

Fig. 2 is a side elevation of a machine of the type used for wet-spinning linen; and

Fig. 3 is a side elevation of a machine of the type used for dry-spinning linen or hemp.

The machine shown in Fig. 1 is generally built to give reaches varying from say 6" up to 20". Normal dry-spun cellulose acetate filaments can be transformed on machines of this type into yarn having wool-like characteristics. The continuous filament bundle i is fed from an inclined creel bobbin 2 controlled by a friction washer 3 to the first set of rollers 4 without the use of the usual slit"-type traverse guide, since the latter tends to produce undesirable bunching of the filaments. A gate-tension 5 is provided between the creel and the first rollers.

The first set of rollers 4 comprises a springloaded presser roller 6 (which may advantageously be covered with leather, cork, or the like) resting on a pair of fine-fluted steel rollers l. The filaments I then pass to a second set of rollers 8 comprising a leather-, rubber-, or corkfaced roller 9 spring loaded ,on to a steel roller l 0.

If the 'machine is provided with carrier rollers for dealing with worsted or silk, it may be advisable to remove them, and to fit a tube or guide H to serve as a conductor between the first and second sets of rollers (the feed rollers and the drawing rollers) in which the bundle can run and by which it can be guided into the nip of the drawing rollers in a compact form instead of spreading over the roller face.

A draft of 40-50 times or more may be applied between the first and secon'drollers, although, as

stated above, drafts of from 10-times upwards may be used. For ease in obtaining a uniform (level) yarn and generally consistent working, it is, however, advisableto use a draft of at least ZO-times. High draft enables light loading to be used, which is advantageous in that it enables normal worsted or silk machines to be used under normal loading conditions, and generally without modification, except for the relative speeding-up of the drawing rollers and the minor modifications already mentioned above. Long reach (e. g. 15") is also helpful in producing a level yarn. A cap-spinning device I2 collects the product delivered by the rollers 9, I0, inserting twist appropriate in amount to the weight of the product.

By employing a 40-times draft, a 6000 denier bundle may be reduced in one stage to denier, or, by a IOU-times draft, to60 denier. Two-stage operation, may, howeverpbe employed. Thus, a 6000-denier bundle may be first reduced to an intermediate denier yarn or roving, in which say in. advance of the feed rollers.

being carried into a trough disposed immediately The wetting may be carried out simply by means of water, which may be cold, but with advantage is heated to, say, 90-95 C. It is found that this wetting facilitates the breaking and drafting operation in a way similar to that of wet linen spinning and thus improves the quality and especially the uniformity of the product. Possibly some softening of the material of the filaments is obtained and in addition a lubrication of the material that facilitates the sliding resulting from the substantial drafting. It has also been found of ad-.

vantage to include in the wetting liquid soaps or other saltsof compounds having a long aliphatic chain, preferably with more than 12 carbon atoms; salts of higher fatty acids, sulphonated oils, e. g. Turkey red oil, and salts of sulphates of higher fatty alcohols. Such additions probably assist the wetting out of the material as well as aiding the lubrication.

The drafting rollers in Fig. 2 are similar to those of the wet line machine-used in the spinning of flax. After leaving the vertical bobbin I3, the bundle I4 is guided by rods Hi to and through a trough i6 and thenceto the first pair of rollers H which are of brass about 1 in diameter and have about 28 longitudinal corrugations to the inch; the next pair of rollers [8 are similarly corrugated, the lower roller is being of brass about 2 /2" in diameter and the upper one of wood, say, 3 /2-4 /2" in diameter. The size of the rollers may be varied in accord-. ance with the reach employed, which, as already stated, is upwards of 5". The use of a metal such as brass guards against rusting in the case where the material is treated wet. are suitably loaded so that the filaments are firmly gripped by the intermeshing corrugations. Preferably the greater part of the load should be applied to the first pair of rollers to maintain good control over the bulky bundle during the drafting. The drafted product is twisted by a fiyer spindle 2 I.

In the dry type of line-spinning machine shown in Fig. 3 a different roller-system is used. The bundle 22 is fed from a substantially horizontal bobbin (or cheese) 23 to the first pair of rollers 24, which are about 1 in diameter, with. about 8 corrugations or flutes to the inch. Alternatively, the rollers maybe leather faced. The direction of rotation of these rollers is reversed so that by carrying the bundle from a traverse bar 25 above the rollers round the back of the rear roller, up through the nip, and over the front roller, a greater suface of contact is obtained to retain full control over the bundle. The other pair of rollers 26 are plain, the front one 21 being of steel about 3 /2-4 in diameter and the rear one 28 of wood about 5-6" in diameter. Suitable loading is applied as in the case of the wet operation. A conductor 29 leads the material into the nip of the rollers 21, 28.

Reaches of 5" upwards may be used, the machines usually having. a roller adjustment 1 by means of which various spacings can be obtained. In the dry operation a reach of 14" upwards, say 16", 18", or 20", is very convenient, but lower reaches of say 6", 8", 10" or 12' maybe used.

For the production of a thread suitable for use in the manufacture of a coarse sewing thread a bundle of 8000, 12,000 or 15,000 deniermay be subjected to a draft of l0-times or upwards to produce a staple fiber thread of say 8004500 The rollers A twist of, say 3 or 4 /2 turns per inch may be inserted, for example, by ring spinning or fiyer spinning the productdelivered from the breaking rollers, and the thread may then be transformed into sewing thread. Although a substantial number, say,12 threads, may be cabled together, theinvention is particularly useful in that it enables a serviceable thread to be made by doubling or cabling a small number, say 3, of relatively coarse threads into a product that may be finally sized and polished. A heavy thread of this character isuseful for sewing boots or shoes.

A finer thread suitable for manufacture into higher grade handkerchief and similar fabrics maybe produced by subjecting an initial bundle of 1000 to 2000 denier to a draft of 10-times or upwards. In this way, a final thread of about -180 denier with 6-8 turns or more per inch may be formed in the one operation.

If the initial filaments have been produced by a stretching operation considerable variation may be made in the filament denier. Thus, for example, by stretching a cellulose acetate filament of 15 denier 10 times and then saponifying the stretched product a final filament denier of one may be obtained. By stretching filaments initially of finer denier and/or applying greater degrees of stretch finer filament deniers, e. g. 0.4

. or less, say 0.1, may be employed. Likewise filament deniers of 1, 1.5, or 2 may be used if desired, the choice available permitting substantial variation in the final staple fiber product. Generally, however, higher filament deniers such as 3, 3 /2, 4 or 4 /2 draft satisfactorily and yield good yarns, and in such cases nonstretched yarns, bright or dull, may conveniently be used.

From the foregoing description it will be seen that whereas with aparticular continuous filament bundle fed at a particular rate an attempt to draft to a higher degree might have been ex- ,pected to involve the exertion of greater tension on the bundle than would be involved in drafting to a lower degree and, therefore, to require a stronger girpping action to be exerted by the drafting rollers,the surprising fact emerges that no such excessive gripping action with its atthe rollers in each set of drafting rollers being loaded with a force not -lsubstantially exceeding that employed in the drafting of. products consistlng initially of staple fibers.

2. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of continuous cellulosic filaments and passing said bundle in a wet condition through two sets of drafting rollers of which the second is driven at a speed at least 15-20 times greater than the first, the reach of said drafting rollers being at least 10 inches, the rollers in each set of drafting rollers being loaded with a force not substantially ex ceeding that employed in the drafting of products consisting initially of staple fibers.

denier having an average staple of say about 5". 3. Process for the conversion of continuous fllaments into staple fiber yarns and like products comprising wetting a bundle of continuous cellulosic filaments, and passing said bundle in a wet condition through two sets of drafting rollers the first of which is more heavily loaded than the second, and the second of which is driven at a speed at least 10 times greater than the first, the reach of said drafting rollers being at least 5 inches and the rollers in each set of said drafting. rollers being loaded with a force not substantially exceeding that employed in the draf ing of products consisting initially of staple fibers.

4. Process for the conversion of continuous filaments of an organic derivative of cellulose into staple fiber yarns and like products, comprising wetting a bundle of continuous filaments having a basis of an organic derivative of cellulose, and passing asid bundle 'while in a wet condition through two sets of drafting rollers of which the second is driven at a speed at least 10 times greater than the first, the reach of said drafting rollers being at least 5 inches and the rollers in each set of said drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers. I l

5. Process for the conversion of continuous filaments into staple fiber yarns and like products,. comprising wetting a bundle of continuous filaments of an organic derivative of cellulose that have been stretched so as to have a highstrength, and passing said bundle in a wet condition through two sets of drafting rollers, the second of said sets of rollers being driven at a speed at least 10 times greater than the first, the reachof said drafting rollers being at least 5 inches and the rollers in-each set of said drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

6'. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of continuous filaments of an organic ester of cellulosethat have been stretched and then saponified so as to have a high strength, and passing said bundle in a wet condition through two sets of drafting rollers, the second of said sets of rollers being driven at a speed at least 10 times greater than the first, the reach of said drafting rollers being at least 5 inches and the rollers in each set of said drafting rollers being loaded with'a force not substantially exceeding that employed in the drafting of products consisting-initially of staple '7. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising Wetting a bundle of continuous filaments of an organic ester of cellulose that have been stretched and then saponified so as to have a high strength, and passing said bundle in a wet condition through two sets of drafting rollers, the first of said sets of drafting rollers being more heavily loaded than the second, and the second of said sets of rollers being driven at a speed at least 10 times greater than the first, the reach of said drafting rollers being at least 5 inches and the rollers in each set of said drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

8. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of pigmented continuous cellulosic filaments, and passing said bundle in a wet condition through two sets of drafting rollers of which the second is driven at a speed at least 10 times greater than the first, the reach of said drafting rollers being at least 5 inches and the rollers in each set of said drafting rollers being loaded with' a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

9. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of continuous filaments of pigmented cellulose acetate that.

have been stretched and then saponified so as to have a high strength, and passing said bundle in a wet condition through two sets of drafting rollers, the second of said sets of drafting rollers being driven at a speed at least 1520 times greater than the first, the reach of said sets of.

rollers being at least 5 inches, the rollers in each set of drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

10. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of continuous filaments of cellulose acetate that have been stretched and then saponified so as to have a high strength and passing said bundle in a wet condition through two sets of drafting roller of which the second is driven at a speed at least 15-20 times greater than the first, the reach of said sets of drafting rollers being at least 5 inches,

the rollers in each set of drafting rollers being loaded with a force not substantiall exceeding that employed in the drafting of products consisting initially of staple fibers.

' 11. Process for the conversion of continuous filaments into staple fiber yarns and like products, comprising wetting a bundle of continuous filaments of cellulose acetate that have been stretched and then saponifie-d so as to have a high strength and passing said bundle in a wet condition through two sets of drafting rollers the first of which is more heavily loaded than the second, and the second of which is driven at aspeed at least 15-20 times greater than thefirst, the reach of said sets of drafting rollers being at least 5 inches, the rollers in each set of drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

12. Process for the conversion of continuous filaments into staple fiber yarns and like prod-' driven at a speed at least 15-20 times greater than the first, the reach of said sets of drafting rollers being at least 5 inches, the rollers in each set of drafting rollers being loaded with a force not substantially exceeding that employed in the drafting of products consisting initially of staple fibers.

CLAUDE HORROCKS HAYS.

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