US2118840A - Production of textile threads and fabrics - Google Patents

Description

Patented 3i, 1938 PRODUCTION 01F TEX'lllllLlE THREADS AND lFAilBlltlllUS Henry lllreyfus, London, England No Drag. Application May 22, 1936, Serial No. 81,264. In Great Britain June 8, 1935 6 Claims.

This invention relates to the manufacture of crepe twisted threads of cellulose esters or ethers. The invention is especially concerned with the production of crepe twisted threads of cellulose acetate, and will be more particularly described with reference to the production of such threads.

The production of commercially useful crepe twisted cellulose acetate threads is a matter involving considerable dimculty. threads of regenerated cellulose, commercially useful crepe threads can readily be obtained by applying a crepe twist of much the same order as that commonly used in the case of natural silk. The precise degree of twist desirable depends upon the denier of the thread and the number of its constituent filaments. In the case of cellulose acetate threads, however, very much higher twists are necessary and special twisting methods must be employed, both to obtain the desired crping power and to produce threads of sufficient strength for commercial purposes. British Patents Nos. 437,019, 438,590 and 438,591 describe methods whereby crepe-twisted cellulose acetate threads of very good strength and creping power may be obtained.

I have found that valuable crepe-twisted cellulose acetate threads of good strength and creping power may be prepared by the action of shrinking agents on threads of substantially lower twist than that required in the final thread. Bysubjecting to the action of shrinking agents a cellulose acetate thread having a certain humber of turns per inch twist, a thread having a greater number of turns per inch may be obtained. In order that the resulting threads may have suficient crping power, it is preferable that the final twist, after the subjecting to the action of the shrinking agent, should not be below a certain minimum, depending upon the denier of the crepe twigted thread. This desirable minimum is of the order of '70 to '75 turns per inch in the case of threads of about 165 denier, and to turns per inch in the case of threads of about denier. By the new process crepe-twisted threads of cellulose acetate having these desirable twists and exhibiting good crping power may be obtained from threads having lower twists, for example twists lower by one fifth, one-quarter or one-third.

By the term shrinking agent is meant an agent which is capable of effecting a shrinkage in length of filaments of the cellulose acetate of which the threads are made. The shrinking treatment is preferably effected by means of agents of such character and under such condi- In the case of tions as would shrink filaments of the cellulose acetate by about 10 to 30% of their length, for

example 15 to 20 or 25% of their length. Agents which efiect a greater shrinkage may, however, be employed, though agents which are capable of effecting very high shrinkages, for example shrinkages of the order of 40, 50 or 60% frequently diminish the strength of the materials to'a substantial degree. Agents which are only capable .of shrinking to a comparatively low degree may be employed, but with the disadvantage that correspondingly smaller increases in the number of turns per unit length of the thread are obtained.

It is desirable that the treatment with the shrinking agent should be effected under conditions permitting shrinkage of the threads treated, e. g. in the absence of any substantial thread tension.

Various shrinking agents may be employed, for example inorganic swelling agents for cellulose acetate, such as aqueous solutions of alkali metal, alkaline earth metal, and ammonium thiocyanates. Preferably, however, the shrinking agents employed are organic substances, mixtures of organic substances or solutions thereof, which have a substantial swelling action upon the cellulose acetate. The shrinking agent may, for example, consist of or comprise one or more of the following substances which have a swelling or solvent action upon cellulose acetate Alcohols, e. g. ethyl alcohol.

Organic acids, for example acetic acid, formic acid and lactic acid. v

Ketones, for example diacetone alcohol and acetone.

Monoand di-ethers of olefine glycols or polyolefine glycols, e. g. the monoand di-methyl and ethyl ethers of ethylene glycol, the monomethyl and ethyl ethers of propylene glycol, and the mono-ethyl ether of diethylene glycol.

Esters, for example ethyl lactate or diethyl tartrate or esters of olefine glycols or polyolefine glycols, e. g. glycol mono-acetate, or esters of glycerol and other polyhydric alcohols, e. g. mono-, diand tri-acetin.

Ether-esters of olefine glycols or poly-olefine glycols, e. g. the acetate of glycol mono-ethyl ether.

Cyclic ethers, e. g. dioxane, methylene-ethylene-ether and other cyclic di-ethers. I

Phenols.

ylene.

It is especially advantageous to efiect the shrinking with the aid of agents which at least at ordinary temperatures are incapable of dissolving cellulose acetate, but which are capable of swelling it to a high degree. Such agents, for example methylene chloride, ethylene chloride, chloroform, tetrachlorethane, ethyl acetate and the like, usually become solvents forthe cellulose acetate when mixed with a comparatively small proportion of another liquid, particularly an alcohol such as ethyl alcohol. Thus, methylene chloride, chloroform, and tetrachlorethane, when mixed with comparatively small proportions of alcohol, are capable of dissolving cellulose acetate. The methylene chloride, tetrachlorethane and the like are commonly referred to as latent solvents for the cellulose acetate and will be so referred to in this specification.

As indicated above, the shrinking agent may consist of a single organic substance having a swelling action upon the cellulose acetate. Generally speaking, however, it is, found most convenient to modify the action of an organic swelling agent by admixture with another substance. Such other substance may, for example, be water, glycol, glycerol or other hydroxy compound. Thus, the shrinking may be eflected with the aid of aqueous ethyl alcohol, for example alcohol. of 50 to 80% strength, particularly alcohol of about 70% strength. In this way very considerable shrinkages may be produced. Again, aqueous acetic acid, aqueous diacetone alcohol,

aqueous acetone, e. g.. aqueous acetone of to 45% by volume, or aqueous dioxane, e. g. aqueous dioxane of 38 to 43% by volume, may be employed.

However it is preferred to employ water-immiscible liquids as diluents or modifying agents for the organic swelling agents or latent solvents. With such water-immiscible diluents or modifying agents it is possible to secure good shrinkages and yet obtain products of good strength and/or extensibility. As examples of such water-immiscible modifying agents or diluents may be mentioned benzene, toluene, xylene and other cyclic hydrocarbons, be he, petrol ether, kerosene and other hydrocarbons of the aliphatic series, and carbon tetrachloride, trichlor-ethylene, perchlorethylene, pentachlorethane, hexachlorethane, and other chlorinated or halogenated compounds which are substantially inert towards cellulose acetate. The diluent employed may be of relatively high boiling point, as is the case, for example, with tetrahydro naphthalene and decahydro naphthalene.

Excellent results may be obtained with a 55 to 70 or 75% solution of methylene chloride in benzene or a similar solution of ethyl acetate in benzene.

Shrinking agents are conveniently used at ordinary temperatures. Other temperatures may be employed if desired according to the particular shrinking agent employed.

The treatment of the twisted threads with the shrinking agent may be effected in various ways. Thus, the threads may be wound on supports which permit shrinkage of the thread, and thereafter immersed in the shrinking agent and the shrinking process allowed to take place. A more convenient method, however, is to subject running threads to the action of the: shrinking agent. This may be accomplished, for instance, by feeding the thread at a definite rate through a bath of the shrinking agent to a winding device where it is wound at a lower rate than the feed rate. The winding rate is adjusted according to the shrinkage which is required, Control of the feed rate may be efiected by mans of a pair of nip or feed rollers in the well known manner. Similarly, after the shrinkage treatment the speed of the thread may be controlled by a further pair of nip or feed rollers preceding a suitable winding device. itself, e. g. a drum winder, may be utilized directly to efiect the desired rate of winding.

When applying a shrinking agent to running threads in the aforesaid manner, it is desirable that the shrinking agent should be removed from the threads prior to rewinding. To this end the threads may be passed through a suitable dryer after treatment with the'shrinking agent.

The shrinking agent treatment is in general most'conveniently applied as an operation distinct from the twisting of the yarn. If desired, however, the treatment with shrinking agent may be efiected on the running thread continuously with the twisting of the thread. Such a combined process may be carried out with the aid of a twisting spindle of the kind in which twist is inserted as the thread is drawn off from a rotating package. The twisted thread may be drawn oil by a pair of nip or feed rolls and led through a bath of shrinking agent or other device wherein treatment with shrinking agent is efiected, and the desired shrinkage allowed to take place. Any necessary drying and winding then follows, as in the case of treating running threads in an operation separate from twisting.

The cellulose acetate threads treated in accordance with the invention may have been prepared by ordinary dry spinning from solutions of cellulose acetate. Again they may have been made by wet spinning processes or by stretching filaments of cellulose acetate, for example while in a softened state, as described for example in Patent No. 1,709,470 and British Patents Nos. 323,790, 370,430, 371,461, 438,584 and 438,586.

The cellulose acetate threads to be treated with shrinking agents in accordance with the present invention may have had their twist inserted in a single stage or in two or more stages. In the case oi. dior multi-stage twisting, the threads may, between stages of twisting, be subjected to a wetting or other treatment as described in British Patent No. 386,344, or to a steaming treatment as described in British Patent No. 386,374. The twisting may be effected in a manner commonly practised in the twisting of textile threads, or most advantageously, the threads may be twisted while under the influence of steam, preferably in the presence of moisture, or while under the influence of hot water, as described in British Patents Nos. 437,019, 438,590 and 438,591 in connection with the crpe twisting of cellulose acetate threads.

The degree of twist of the cellulose acetate threads prior to the treatment with shrinking If desired, however, the winding .device agents will, in general, be less than suffices to give the threads any substantial crping power, but usually at least 70% of that requisite for crping power. The twist may be less than a value determined according to the thread denier with shrinking agents may be utilized to enhance the crping power of threads already exhibiting substantial crping power, for example crpetwisted cellulose acetate threads produced by the methods described in the above-mentioned British Patents Nos. 437,019, 438,590 and 438,591.

While the invention is of particular value in the production of threads having a twist sumcient to afford crping power, it may be utilized in the production of threads having substantial twists but less than is required in a crepe thread. For example, cellulose acetate threads having a twist of 50 to 70 turns per inch or more (but less than is required for crepe purposes) may be produced by the action of shrinking agents on threads of lower twist than is required in the finished thread. The new method, as compared with direct twisting to the required degree, enables improved results to be obtained as regards strength and other properties of the resultant threads.

In place of cellulose acetate threads, crepe twisted and other highly twisted threads of other esters or ethers ofcellulose may be treated by the new process. Thus the threads may be made of filaments of cellulose formate, proplonate or butyrate, or of mixed esters of cellulose, e. g. cellulose nitro-acetate or cellulose acetate-butyrate. Again the threads may be of cellulose ethers e. g. methyl cellulose, ethyl cellulose or benzyl cellulose, or of ether-esters of cellulose, e. g. an esterified low ether of cellulose, or an acetylated or otherwise esterified hydroxy ethyl cellulose or other hydroxy alkyl cellulose.

Crepe twisted and other threads produced in accordance with the invention may be incorporated in fabricsin the manner well known in the art of making crepe and other fabrics. For example, for the production of a fabric of the crepe de Chine type, a warp of cellulose acetate threads of low twist may be employed, the weft consisting of cellulose acetate crepe threads prepared in accordance with the present invention, pairs of picks of right-hand twisted threads alternating with pairs of picks of left-hand twisted threads. To develop the crepe efiect the fabrics may be given a hot aqueous treatment, for example a hot soap treatment such as is commonly employed in the case of natural sillr crepe fabrics or regenerated cellulose crepe fabrics.

According to a further feature of my invention I apply the treatment with the shrinking agent to fabrics containing the twisted threads. In this way fabrics exhibiting crepe efiects may be obtained even when the twist of the threads is lnsufiicient to giverise to crepe efiects when the same fabric is subjected to hot aqueous treatment as in ordinary crepe practice. Where treatment with shrinking agents is applied to threads in a fabric it is advantageous that the fabric should have a rather more open construction than in the case of a fabric on which crepe eflect is to be developed solely by a hot aqueous treatment. For example, where the warp is of material which does not undergo substantial shrinkage under the action of the shrinking agent, the warp threads alone may be spaced more widely than in similar fabrics designed to be crped without substantial shrinkage of the filaments of the threads. Where, however, the warp, like the weft, is of filaments which are shrunk by the action ofthe shrinking agent, then both warp and weft are advantageously more widely spaced.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for the production of a highly twisted crepe thread of cellulose acetate filaments, which comprises subjecting a cellulose acetate thread, having substantially no crping power but a twist of at least 70% of that required to impart crping power to the action of a shrinking agent so as to shrink the filaments of the thread to such a degree that creping power is imparted to the thread.

2. Process for the production of a highly twlsted crepe thread of cellulose acetate filaments,

which comprises twisting a cellulose acetate thread, while under the influence of a hot aqueous medium, to a twist insumcient to impart creping power but at least 70% of that required to impart crping power, and thereafter subjecting the thread to the action of a shrinking agent so as to shrink the filaments of the thread to such a degree as to impart creping power to the thread.

3. Process for the production of a highly twisted crepe thread of cellulose acetate filaments, which comprises twisting a cellulose acetate thread, while under the influence of steam under conditions such that moisture is present, to a power, and thereafter subjecting the threads to the action of a shrinking agent so as to shrink the filaments of the thread to such a degree asto impart crping power to the thread.

4. Process for the production of a highly twisted crepe thread of cellulose acetate filaments, which comprises twisting a cellulose acetate thread, while under the influence of a hot aqueous medium, to a twist less than a value deter= mined according to the thread denier, said value being '70 turns per inch for threads of 165 denier and 85 turns per inch for threads of 115 denier, and thereafter shrinking the filaments of the thread until the number of turns per inch is greater than said value.

5. Process for the production of a highly twisted crepe thread of cellulose acetate filaments, which comprises twisting a cellulose acetate thread, whileunder the influence of a hot aqueous medi, to a twist insumcient to impart crtping power but at least 70% of that required to impart creping power, and thereafter shrinking the thread, sumcient to impart creping power thereto, by the action of a cold non aqueous shrinking agent capable of shrinking cellulose acetate filaments by from to 30% of their original length.

6. Process for the production of fabric exhibiting crepe efl'ects, which comprises twisting cellu lose acetate threads, while under the influence of a hot aqueous medium, up to a twist oi. at least '70 per cent but less than 100 per cent of that required to impart crping power, incorporating the threads in a fabric and subjecting the fabric to the action of a shrinking agent so