US2098980A - Yarn manufacture - Google Patents

Description

Patented NW. 16, 1931 UNITED I STATES PATENT OFFICE YARN MANUFACTURE No Drawing. Application January 14, 1933, Se-

rial No. 1932- 6 Claims.

This invention relates to-the manufacture of yarns, and particularly yarns of cellulose acetate or other organic derivatives of cellulose, having the appearance of spun yarn or yarn made from 5 staple fibre, and also relates to therefrom In the manufacture of spun yarn from artificial fibresthe usual practice is to cut the continuous artificial filaments or waste filaments into comparatively short lengths, for example of 1V; to 2 inches or more, and then to subject the staple fibres thus produced to. a series of operations appropriate to the-length of the fibre, such operations being similar to those accorded to 15 natural fibres, such as cotton or wool, including opening, carding, drawing and spinning. .These operations, while presenting comparatively'little difllcultyin the case of the cellulosic type of fibre,

which, as is well known, is produced exclusively by wet spinning processes and is not susceptible to electrification, are somewhat tedious and dimcult in the case of cellulose acetate and similar yarns which are usually produced by the dry spinning operations, and which are liable, par- 25 tlcularly on the carding machines and in the light twisting and drawing of the slivers, to acquire a degree of electrification which considerably impedes the said operations.

' The present invention aims toproduce a spun o yarn", and especially a spun yarn of cellulose acetate or other organic derivative of cellulose, whilst avoiding the said disadvantages. According to the present invention during or subsequent to the spinning or extrusion bf the fila-' a ments, toform a yarn of continuous filaments the materials are subjected to a stretch while in a softened state so as to break the continuity of one or morefilaments, but not all thefilaments associated in the bundle, so that the resulting fabrics made 0 yarn has'a'numberof broken ends which give it when twisted, and particularly when doubled with a number of such bundles, he appearance of a spun yarn. 1

I find that the best means of I achieving- 45 this object is-to stretch the yarn subsequent to the manufacture of the yarn and with or without previous twisting and to stretch it to a point at which the main filament bundle does not break 651,847 In Great Britain February 5,

effect a'very considerable stretching of the filament bundles, so that reduction in denier takes place and, when a number of the filament bundles is subsequently doubled to produce theyarn, the latter has not an unduly high denier. The stretching operation may take place for example while the yarn is'in hank form or while it is mult-aneously so as to bring about the desired breakage of some of the individual filamentsand a number of such bundle for example 5 to or more, may be associate continuously with the stretching operation and twisted to produce the spun yarn directly.

The stretching may becarried out by passage of the filaments in substantially non-slipping contact with two or more rollers rotating at different peripheral speeds.

As previously stated it is desirable to reduce the denier of the initial filament bundles as much as possible. This may be achieved by applying a relatively high stretching treatment and suitably softening the filaments so that breakage .only takes place after a relatively high stretch; such as 300. to 500% on the initial length of the filaments. Thusfo'r instance in the case of threads of acetone-soluble cellulose acetate a soaking in 40-50%dioxane, or an equivalent concentration of dlacetone alcohol, ethyl lactate, glycol monoacetate, methyl glycol monoacetate or the like, may take place and the filament bundle then stretched to 300500% or until a sufficient number of filaments have been broken.

' The stretching to the breaking pointof some of the" filaments may take place as described above continuously with the production-of-the filaments and also even during their manufacture. For example in a dry spinning operation the stretch imparted by the customary feed "roller may be sufliciently high to produce the requisite number of breakages. In such case it is desirable to adopt meansyfor example a suction at the point of exit of the filaments, so as to carry the broken ends along with the main yarn. Similarly in wet spinning operations the stretch may be such as to break some filaments of the filament bundle during the actual formation in baths designed to produce filament bundles of .lose butyrate, nitro-a'cetate March 20th, 1930, 469,622 filed July 21st, 1930, 573,421 filed November 6th, 1931, 589,428 filed January 28th, 1932 and 607,668 filed April 26th, 1932. It is only necessary to supply suificient stretching by the usual feed roller or other stretching device to produce an elongation great er than the filaments will withstand having regard to the amount of plasticity induced by the coagulating bath. In wet spinning operations the body of liquid carried by the main yarn is usually capable of carrying the broken ends, so that no special means need be adopted to achieve this object.

Breakage of the filaments results in a number of filament ends projecting from the'yarn. If considerable hairiness of this character is not desired, twisting may serve to bind the ends as far as possible in the yarn. If desired the yarn may be treated, as for example by passage between or over brushes or between rollers, so as to lay the ends substantially in the direction of the length of the yarn to facilitate twisting-in of the ends. The yarnmay' be subjected to a gassing operation to remove superfluous projecting filaments.

While a number of specific methods of introducing discontinuities in the individual filaments have been described above, the invention envisages the broad principle of introducing such discontinuities by stretching softened yarn to an extent such that individual filaments are broken while the continuity of the yarn as a whole is preserved. As already indicated the inventionis of most practical importance in relation to the production of spun yarns of cellulose acetate or other organic esters, ethers, mixed esters or ethers or ether-esters of cellulose, for instance cellulose formate, cellulose propionate and celluand methyl, ethyl and benzyl cellulose.

Yarns having broken filaments, produced as described above, may be doubled with any type of yarn of a similar or dissimilar nature, whether as regards type of constituent filaments or fibres, continuous or discontinuous, or as regards the substance constituting the filaments or fibres. Two or more broken filament yarns may be doubled together for the purpose of increasing the denier and/or improving the regularity or for any other purpose, such as the production of a yarn having differential dyeing properties.

The basic yarn may be of high, medium or low lustre, the lustre being modified for example by incorporation of pigments, by' treatment with boiling soap or other aqueous liquors or by any other method, and similarly the lustre of yarns doubled therewith may be either that normal to the fibre in question or mayv be'suitably modified. Association of lustrous and non-lustrous yarns or filaments may take place before or after breaking of constituent filaments.

The yarns may be subjected to any desired after-treatment to modify their properties or appearance, e. g. they may be treated with shrinking agents in order to improve their extension or other properties or for the production of efiects, in which connection reference is made broadly -to the processes described in U. S. applications S. Nos. 611,240 .filed May 13th, 1932, 607,667 filed April 26th, 1932 and 609,255 filed May 4th, 1932.

The yarns or mixed yarns of the invention may be woven, knitted or otherwise made up into fabrics consisting solely of the said yarns or condiacetone alcohol.

taining them'in admixture with other yarns. For example, the yarns may be introduced into the weft or warp or both to produce a woven fabric having the appearance of one constituted wholly of staple fibre yarn or having pattern eifects with or. without difierential lustre. Similarly, knitted fabrics of allkinds may contain the yarns either as effect yarns or as the sole or principal constituent of the fabrics.

Thefollowing examples are given in order to illustrate the invention but it is to be clearly understood that they do not limit it in any way: Example 1 A cellulose acetate yarn of 1000 denier, 104 filaments and 1- turn per inch twist, is run at a' rate of 2 metres-per minute take up speed through a Example 2 A similar yarn to that employed in the above example is run at a rate of 2 metres per minute take up speed through a bath of 30% aqueous acetic acid at 25 C. between rollers 10 feet apart which impart a stretch of 2 to 1. The filaments in this condition are readily broken and further hairiness may, if desired, be produced. by passing the whole over a roughened surface or edge during washing or drying. The yarn is washed in cold water and when twisted has a matt appearance.

Example 3 A cellulose acetate yarn of 750 denier, 150 filaments is run through a bath of 40 to 48% dioxane in water at 22 C. between rollers which are 100 feet apart and driven to impart a stretch of from 3 to 4:1. The stretching roller is driven at 25 metres per minute and either it has a slipping drive or alternatively the yarn isallowed to slip on it so that total breakage does not occur, but individual filaments are ruptured. The total stretch is less than the ratio of the circumferential velocities of the supply and take-up rollers by about 25%. The yarn is then passed over a roughened surface to fray out the broken filaments and collected with washing in a Topham box running at 5,000 revolutions per minute and putting in a twist of 8 turns per inch.

Example 4 A 25% solution of cellulose acetate is extruded through a spinning jet having 26 holes of .08 mm. diameter into an aqueous bath containing 40-45% The filaments are passed round a draw roller and then round a second roller rotating at a higher peripheral speed so as to' impart'a stretch such that breakage of the individual filaments occurs, e. g. 400-500%,,and are then collected with washing in a Topham box.

What I claim and'desire to secure by Letters Patent i'sz- 1. Process for the manufacture of imitation spun yarn, which comprises softening the whole of a bundle of filaments having a basis of an organic derivative of cellulose and stretching the softened bundle of filaments while in transit to such an extent that individual filaments are broken while the bundle still contains long lengths of unbroken filaments.

2. Process according to claim 1, wherein the bundle of filaments is soitened to such an extent that it is necessary to stretch the bundle to a high degree to obtain the desired number of individual broken filaments.

3. Process for the manufacture of imitation spun yarn, which comprises softening the whole of a bundle of filaments having a basis of cellulose acetate, stretching the softened bundle of filaments while in transit to such an extent that individual filaments are broken while the bundle still contains long lengths of unbroken filaments, and twisting the bundle while in a softened contion.

4.Processaceordingtoclaim3,whereinthe bundle of filaments is soitenedto sum an extent that it is necessary to stretch the bundle to at least 300% of its original length to obtain the desired number of individual broken filaments.

5. Process for the manufacture of imitation spun yarn, which comprises softening the whole of a bundle of filaments having a basis of an organic derivative of cellulose, stretching the softened bundle of filaments while in transit to such an extent that individual filaments are broken while the bundle still contains long lengths of unbroken filaments, and subjecting the yarn containing the broken filaments to a shrinking operation. a

6. An imitation spun yarn which contains broken filaments having a basis of cellulose ace-v tate and long lengths oi unbroken filaments having a basis of cellulose acetate.

I PERCY FREDERICK COLIBE SOWTER.