US2252038A - Production of hairy yarn - Google Patents

Description

Patented Aug. 12, 1941 PRODUCTION or may YARN Frank Rue Scull, Scarsdale, N. Y., assignor, by mesne assignments, to Celanese Corporation of America, a corporation of Delaware No Drawing. Application October 5, 1938,

Serial No. 233,411

17 Claims.

This invention is concerned with making hairy rayon yarn from continuous filaments of cellulose acetate and aims to improve the durability, strength and appearance of such yarn and to avoid losses in its manufacture and during its use.

It has been proposed heretofore to impart hairiness or pubescence to continuous filament rayon yarn by rupturing some of the filaments at a succession of places along the yarn. The ends fray out from the main body of the yarn, so that the appearance of .yarn made from short textile fibres such as cotton, wool and staple fibre is approximated. Freshly formed rayon yarn is a body of continuous and more or less parallel filaments which are subjected to twisting in the finishing treatment, and it has been proposed heretofore to accomplish the above-mentioned rupture by causing the yarn to impinge upon an abrasive during the twisting operation.

Cellulose acetate filaments have high dielectric characteristics and when rubbed under certain conditions acquire static charges which cause the filaments to repel each other. The rubbing in the winding and other rayon finishing operations to which yarn is subjected is such as to impart a considerable static charge to cellulose acetate so that the filaments thereof do not tend to cohere. This behaviour of the filaments is not particularly harmful in the case of continuous filament yarns, but when some of the filaments are loose-ended, as in the case of yarn that has been subjected to abrasion, there is a strong tendency for the yarn to fly apart in subsequent yarn finishing operations and in textile manufacture. Loose broken filaments are lost as fly, and in aggravated instances as much as 50% of the weight of'the yarn may be lost before it is finally converted into fabric. Even then the tendency of the cellulose acetate filaments to separate continues and thus seriously impairs the fabric, which has inferior durability and an annoying tendency to lose its nap. To take a specific instance, hairy cellulose acetate yarn which was abraded, twisted and finished in the v heretofore customary manner with about 6% of fhaired" appearance, 'as distinguished from the rich short napped appearance (similar to that of fine worsted or high twist mohair) which was desired.

As a result of my investigations, however, I have discovered how the aforementioned difficulties in the manufacture of hairy cellulose acetate yarn from continuous filaments may be combated successfully.

In accordance with my invention, cellulose acetate yarn is abraded, preferably during a primary twisting operation, and after abrasion is subjected to further twisting and treated with a tacky liquid, by which I mean a fiuid of mucilaginous character capable of imparting to the yarn a coefiicient of friction of at least 0.4 (as measured with the method and apparatus described in an article entitled Yarn-Friction tests" by W. B. Sellars in the Textile World for December, 1934, at pages 79-80). This treatment brings about a decreased tendency for the filaments'to accumulate like static charges which cause them to repel each other, a binding together of the filaments in which the tacky character of the oil cooperates with the imparted secondary twist, and a softening of the filaments so that their tendency to break and be lost from the yarn in passing over guides and other contacts is diminished. The abraded yarn, after being subjected to the above-described twisting and oiling treatment, becomes stable, does not lose substantial proportions as fly during subsequent treatment and may be fabricated intocloth having a desirable and durable nap.

The novel product of the above-described operation is, therefore, a yarn comprising a twisted bundle of ruptured cellulose acetate filaments having a twist of at least 6 turns per inch and containing a tacky fluid selected from the group consisting of blown sperm oil, blown olive oil, castor oil, glycerine and diethylene glycol or equivalent liquid capable of imparting a coefiicient of friction of at least 0.4 to the filaments.

As cellulose acetate yarn comes from the spinning machine, it usually has a slight twist (say about a third of a turn to the inch) and in carrying out the practice of my invention, this yarn conveniently is abraded as it balloons in a primary twisting operation which imparts to the yarn a portion (say 2 turns per inch) of the total desired twist. The abrasion and primary twisting may be carried out by the method and with the apparatus disclosed by James E. Moore in United States Patent No. 2,099,215 granted November 16, 1937. Thereafter, the yarn is twisted further and at or about the same time a suitable tacky liquid, for example, blown olive oil, blown sperm oil, castor oil .(either blown or untreated), glycerine or diethylene glycol is applied. At least 4% by weight of the liquid should beapplied, and except in rare instances it is neither necessary nor desirable to employ more than about 7% of the liquid by weight of the yarn. My presently-preferred practice is to employ of the tacky oil on the weight of the yarn, and excellent results are obtained with such proportions especially when blown olive oil is used.

In the practice of my invention, superior results are obtained if the yarn is abraded during or immediately before a preliminary twisting operation. The slight twist (say 0.35 turn per inch) which the cellulose acetate yarn has when it comes from the spinning machine is not suflicient for optimum results. A further twist of say 2 to 3 turns per inch is, therefore, imparted. The yarn may be abraded conveniently-at this state of the operation. Many types of twisters cause the yarn to describe a balloon or other curved surface of rotation, and by disposing an abrasive so that the yarn impinges on it in travelling through the balloon, preliminary twisting and abrasion are accomplished substantially simultaneously. The yarn may be abraded after preliminary twisting but the product is less satisfactory.

Following preliminary twisting and abrasion, the yarn is subjected to further or secondary twisting, preferably in the presence of a tacky liquid capable of imparting to the filaments a coefficient of friction of at least 0.4. The secondary twisting should not be less than about 4 turns per inch for good results, 5 turns being preferred.

A secondary twisting of as high as turns per inch gives yarn of good character, but above 5 turns per inch the rule of diminishing returns applies and the advantages realized through the extra twist are not in proportion to the expens involved in imparting it.

Preferably, the tacky liquid is applied to the abraded yarn as it passes to the secondary twisting operation. In other words, the tacky oil is supplied to the yarn just prior or during the secondary twisting. The oil may be applied conveniently by passing the yarn over a wick or rotatable roller dipped in a bath of the oil or by other convenient means. The linear speed of the yarn passing in contact with the applicator for tacky liquid, for example, a wick, should not be A greater than 100 yards per minute and even lower speeds are preferred. At higher speeds the oil is not applied uniformly. Moreover, high speed application involves danger of completely rupturing the yarn.

Satisfactory results may be obtained by applying the tacky liquid promptly after the further or secondary twist, provided that the yarn speed is not too high. However, the coning operation which usually follows twisting is carried on at very high speeds; sometimes as high as 800 yards per minute. Hence, application of the tacky oil or the like during coning is not recommended.

The application of an oil of relatively low viscosity of the finishing type to the yarn both before and after application of the tacky liquid is recommended, and gives improved results both from the standpoint of fly loss and final fabric characteristics. Any of the customary thin finishing oils may be employed. The viscosity of the oil should not, however, exceed 100 seconds Saybolt at 100 C., and preferably should have a viscosity ranging from to 85 seconds Saybolt at 100 C. A small proportion of the total thin finishing oil should be employed prior to abrasion and preliminary twisting, the balance of the thin oil being applied after secondary twisting, for example, during the coning operation. My presently-preferred practice is to apply about one-sixth of the total thin finishing oil as the yarn leaves the spinningmachine.

To take a specific example of a presently-preferred practice of my invention, fresh cellulose acetate yarn of 150 denier and comprising 40 filaments is taken from a spinning machine. During withdrawal from the machine about 1% on the weight of the yarn of a finishing oil comprising 9'7 parts of 65 second mineral oil and 3 parts of free oleic acid is applied to the yarn by means of a Wick, and the yarn is then passed to the ring twister equipped with an abrasive ring through which the yarn passes as it'balloons prior to being wound on the bobbin. Abrasion and preliminary twisting is done conveniently with the apparatus disclosed by James E. Moore in U. S.

Patent No. 2,123,635 granted July 12, 1938. In-' this preliminary twisting operation a twist of about 2 turns is imparted to the yarn while it is being abraded and wound on a bobbin.

The presence of a limited proportion of the finishing oil on the yarn tends to hold the filaments together during abrasion, but a larger proportion of finishing oil (say in excess of 2%) is disadvantageous in that it lubricates the abrasive and interferes with uniform rupture of filaments along the yarn. The linear speed of the yarn during abrasion and primary twisting is about yards per minute.

The bobbin holding a cake or the abraded and partially twisted yarn is withdrawn from the ring twister. Thereafter, the yarn is unwound from this bobbin and passed through a second ring twister of conventional type that is not equipped with abrading means. Immediately preceding this second twister is a series of wicks over which the yarn passes and which apply to the yarn about 5% by weight of tacky blown olive oil. The yarn passing thewicks has a linear speed of about 40 yards per minute. About 5 turns per inch are imparted to the yarn on the second twister in the presence of the blown olive oil.

After the secondary twisting the yarn is coned on conventional apparatus, about 5% by weight of the yarn of the thin finishing oil described hereinbefore being applied from a wick during coning. Other suitable thin oils for use in the practice of the invention are a mixture of parts of 65 second Saybolt C.) mineral oil and 15 partsof Twitchell W base emulsifier" which is a sulphonated mineral oil product, and a mixture comprising 20% sulphonated vegetable oil, 70% of 65 second mineral oil and 10% sperm oil. The linear speed of the yarn during coning ranges from 187 to 619 yards per minute. The coned yarn is then ready for shipment- I claim:

1. In a proces in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises twisting the yarn after it has been. abraded and applying thereto a non-lubricating tacky fiuid capable of imparting to the filaments a coefficient of friction of at least 0.4.

2. In a process in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises twisting the yarn after it has been abraded and applying thereto a non-lubricating tacky oil capable of imparting to the filaments a coefiicient of friction of at least 0.4.

3'. In a process in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises twisting the yarn (after it has been abraded) in the presence of a tacky fluid capable of imparting to the filaments a coeflicient of friction of at least 0.4.

4. In a process in which yarn comprising substantlally continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along theyarn and impart pubescence thereto, the improvement which comprises applying to the abraded yarn while it is travelling at a speed not in excess of 100 yards per minute a non-lubricating tacky fluid capable of imparting to the filaments a coeflicient of iriction of at least 0.4 and twisting the yarn in the presence of the fluid thus applied.

5., In a process in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises applying a tacky liquid selected from the group consisting of blown sperm oil, blown olive oil, castor oil, gly'cerlne and diethylene glycol to the abraded imparting to the filaments a coeificient of irlctlon of at least 0.4. I o

7. In a process in which a yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to partially rupture the yarn at. intervals along its length and impart pubescence thereto, the improvement which comprises twisting the yarn after it has been abraded and applying thereto at least 4% on the weight of the yarn of a non-lubricating oil capable of imparting to the filaments a-coemcient of friction of at least 0.4.

8. In a process in which a' yarn comprising ubstantially continuous cellulose acetate filaments is subjected to abrasion to partially rupture the yarn at intervals along its length and impart pubescence thereto, the improvements which comprises twisting the yarn after it has been abraded to impart thereto at least 4 turns per inch and applying thereto a non-lubricating oil capable of imparting to the filaments a coemcient of friction of at least 0.4.

9. In a process in which a yarn comprising substantially continuous cellulose acetate filaimpart pubescence thereto, the improvement which comprises twistingthe yarn after it has been abraded so as to impart thereto from about 4 turns per inch to about 10 turns per inch and applying to the yarn a non-lubricating oil capable of imparting to the filaments a coefllcient of friction of at least 0.4.

11. In a process in which a yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises abrading the yarn in a primary twisting operation during which between '2 and 3 turns are imparted to the yarn and thereafter subjecting the yarn to further twisting and applying thereto an oil capable of imparting to the fila-, ments a coe'flicient of friction of at least 0.4.

12. In a process in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impart pubescence thereto, the improvement which comprises adding to the yarn a relatively small proportion of an oil of low viscosity, subjecting the oiled yarn to abrasion during a primary twisting operation and thereafter subjecting the yarn to further twisting and applying thereto an oil capable of imparting to the filaments a coeificient of friction of at least 0.4.

v 13. In a process in which yarn comprising substantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn and impartpubescence thereto, the improvement which comprises adding to the yarn a relatively small proportion of an oil of low viscosity, subjecting the oiled yarn to abrasion during a primary twisting opments is subjectedeto abrasion to partially rupture the yarn at intervals along its length and impart pubescence thereto, the improvement which comprises imparting to the yarn about 5 eration, thereafter subjecting the yarn to further twisting, applying thereto a tacky oil capable of imparting to the filaments a coeflicient of friction of at least 0.4, and then addingv to the yarn a relatively large proportion of a finishing'oil of low viscosity.

of the tacky oil and thereafter by'the addition of about 5% of oil of low viscosity.

17. In a process in which yarn comprising sub- I stantially continuous cellulose acetate filaments is subjected to abrasion to rupture the filaments at intervals along the yarn to impart pubescence thereto. the improvement which comprises adding to the yarn about 1% by weight of the yarn of an oil of relatively low viscosity, subjecting the yarn thus treatedto abrasion while imparting thereto a primary twist ranging from about 2 to about 3 turns per inch thereafter adding to the yarn about-5% by weight of the yarn of a tacky oil capable of imparting to the filaments a coefflcient of friction of at least 0.4, subjecting the yarn to a further twisting of at least 4 turns per inch, and adding to the yarn thus treated about 5% by weight of an oil of relatively low viscosity.

FRANK RUE SCUIL-