US2142119A - Crepe thread and fabric and the manufacture thereof - Google Patents

Description

Patented Jan. 3, 193a UNITED STATES PATENT OFFICE CREPE THREAD AND FABRIC AND THE MANUFACTURE THEREOF No Drawing. Application January 30, 1935, Serial No. 4,086. In Great Britain February 8, 1934 80laims.

This invention relates to crepe threads and fabrics and the manufacture thereof, and has for its particular object the production of crepe fabrics of an improved character using threads containing filaments of cellulose acetate or other organic derivatives oi cellulose.

Fabrics exhibiting crepe eiiects have long been obtained by employing in their construction highly twisted threads of natural silk in the gummed state, the crepe eifects appearing more particularly when the fabric so formed is subjected to an aqueous scouring -treatment. The fabrics obtained in this way are highly valued an account of their pleasing appearance and handle. The production of crepe fabrics in an analogous manner by the use of threads containing cellulose acetate filaments has, however, been accompanied by difilculties in various directions, both as regards the production of a satisfactory figure on the fabrics, and the obtaining of sufiicient strength.

We have now found that an exceedingly good crepe eflect as well as a high degrees of strength can be obtained by employing cellulose acetate threads which have been stretched in the presence a hot aqueous medium, 1. e. hot water or steam, and afterwards twisted to the necessary degree. Where water is employed, it should be maintained at or near its boiling point. Thus, the threads may be guided through an open trough containing water maintained by suitable means such as steam pipes or jackets or gas jets at a temperature of about 98 to 100 C. Where steam is employed its pressure may range from say atmospheric up to or lbs. per square inch or more. Thus, threads may be led through a small orifice into a chamber containing steam at the desired pressure and led from the chamber through a similar orifice,. the orifices preventing undue escape of the steam, If the threads are to be considerably stretched, the steam is preferably applied in a wet condition; dry steam is, however, efiicacious as a stretch assisting agent.

The threads are exposed to the hot water or steam for a period of time depending upon the extent to which they are to be stretched and the speed at which they are carried through the apparatus. Any desired number of threads may be treated simultaneously, the treatment of a number of threads spaced in the form of a warp sheet and suitably guided over rollers which apply the stretch enabling the large scale production of threads having substantially uniform final characteristics.

Under some conditions, and particularly when the stretching is carried out in the presence of wet steam, cellulose acetate threads can be stretched to many times their original length, with a corresponding diminution in denier. It has been found, however, that very good results can be obtained with a relatively low degree of stretch, e. g., by '70% and particularly in the neighbourhood of of their original length, l. e. with relatively little reduction in denier, At the same time, the threads may receive an increase in tenacity of about 30-50% or more of their original tenacity. Such a degree of stretch can be effected by subjecting the threads to a stretching tension of the order of 14-16 grams per 100 denier during their exposure to the hot water or steam, though the actual tension will vary with the conditions.

The stretched thread is twisted by means of any suitable apparatus, for example one in which the thread is drawn off over the end of a rotating package to a guide substantially in line with the axis of the package, and thereupon led to a takeup device collecting the yarn at a predetermined speed which determines in accordance with the rate of rotation of the package the degree of twist applied. The rotating bobbin may be provided with a fiyer to guide the thread from the package, or with advantage the twisting device may be provided with means on an extension of the spindle projecting beyond the package to prevent twist which has been inserted running back to the yarn on the package as described in U. S. Patent No. 1,784,581.

During twisting the thread may be subjected to the action of wet steam as by passing it through a steam box disposed between the guide above the spindle and the take-up-package. Thread twisted in this way has a final strength considerably higher than that obtained by twisting untreated thread. For example 100 denier stretched thread may be twisted to about 80 turns per inch and have a tenacity on its final denier ofover .6 gram per denier.

The tension maintained during twisting may be such as under the action of the applied steam to stretch the thread still further and overcome in part at least the tendency of the thread to increase in denier during twisting. However, even if the twist is allowed to give a denier increase, higher final tenacities are obtained.

The degree of twist applied to the threads according to the invention may vary within wide limits; for example twist from to or more turns per inch may be applied, it being understood that in general the finer the thread the higher the degree of twist required. Apart from this the degree of twist desirable in any particular case depends upon a number of other factors, including the precise efi'ects required, the material of the filaments, and the fineness of the filaments in the threads.

In using the improved crepe threads according to the invention for the production of woven fabric, they may be applied in any desired manner either in the weft or warp or both and with any suitable disposition as regards threads havingleftand right-hand twists, as for example leftand'right-hand twists alternating singly or in pairs in the weft. By using highly twisted threads in the weft only, i'abrics may be obtained having a shrinkage amounting to as much as 40% in the weft direction and nearly as much in the warp direction.

Upon scouringya crepe figure is developed having an excellent well-pronounced character. Moreover, due to the high tenacity of the high twist threads, the resultant fabric has considerable strength adequate for all usual commercial purposes.

The threads may also be used otherwise than in woven fabrics; for example they may be knitted. In addition to cellulose acetate threads, threads containing filaments of other cellulose esters, e. g. cellulose formate, propionate, butyrate, and oxyethyl cellulose acetate, or of cellulose ethers, e. g. ethyl and benzyl cellulose, may be treated according to the invention.

The cellulose derivative threads may with advantage be formed from cellulose derivatives of high viscosity characteristics; for example, there may be, employed cellulose acetate or other cellulose esters as described in U. S. Patent No.

1,708,787. Thus the cellulose acetate should have a viscosity of at least and preferably exceeding 50, for example, of the order of 75, 100, 150, or even 200 or more as measured by comparing the viscosity of a -6% solution of the cellulose acetate in acetone with that of glycerine taken as a standard of 100.

The threads to be stretched may have normal or bright lustre, or they may be threads having a reduced or subdued lustre. For example, where the crepe threads are desired to have a dull appearance, the threads to be treated may with advantage contain a certain amount of pigment, e. g. 1, 2 or 3% of their weight, in accordance with the dullness required. Thus, cellulose acetate threads containing. e. g. in the proportions above indicated, antimony oxide, stannic oxide, or titanium oxide may be employed according to the invention. Y

After being stretched in a hot aqueous medium, cellulose acetate and other cellulose ester threads may be saponlfled. Such saponiflcation may be complete or only partial, it being, however, in general preferable to employ materials in which saponiflcation has extended considerably below the surface or even throughout the whole section of the material.

The saponified materials may acquire an affinity for cotton dyestufls by the saponiflcation treatment which may, or may not, involve loss of afiinity for cellulose ester dyes, for example dyes of the dispersed insoluble type. It has been found of particular advantage in connection with cellulose acetate to carry the saponiflcation to such an extent that the material is insoluble in acetone but yet retains a relatively high acetyl content.

The filaments contained in the threads used according to the invention may be continuous or discontinuous in character. I

Whatweclaim anddesiretosecurebyhetters Patent is:-

1. Process for the production of crepe threaa, which comprises stretching threads containing filaments of organic derivatives of cellulose in the presence of a hot aqueous medium and immediately thereafter twisting the stretched threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted.

2. Process for the production of crepe threads, which comprises stretching threads containing cellulose acetate filaments in the presence of a hot aqueous medium and immediately thereafter twisting the stretched threads to a high degree,

while applying steam thereto at the point where and while the twist is being inserted.

3. Process for the production of crepe threads, which comprises stretching threads containing cellulose acetate filaments in the presence of wet steam by about -75% of their original length,

and immediately thereafter twisting the stretched threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted.

4. Process for the production of crepe threads, which comprises stretching threads containing cellulose acetate filaments in the presence of hot water by about 35-70% of their original length, and immediately thereafter twisting the stretched threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted.

5. Process for the production of crepe threads, which comprises stretching threads containing cellulose acetate filaments in the presence of a hot aqueous medium, partially saponifying the threads and immediately thereafter twisting the stretched and saponified threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted;

6. Process for the production of crepe threads, which comprises stretching threads containing filaments of cellulose acetate of viscosity at least 30, measured as hereinbefore defined, in the presence of a hot aqueous medium, and immediately thereafter imparting to the stretched threads a high degree of twist while applying steam at the point where and while the twist is being inserted.

7. Process for the production of crepe threads which comprises stretching threads containing filaments of cellulose acetate of viscosity at least '30, measured as hereinbefore defined, inthe presence of a hot aqueous medium, and immediately thereafter twisting the threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted.

8. Process for the production of crepe threads which comprises stretching threads containing cellulose acetate filaments of viscosity at least 50, measured as hereinbefore defihed, in the presence of wet steam by about 35-75% of their original length, and immediately thereafter twisting the threads to a high degree, while applying steam thereto at the point where and while the twist is being inserted.

HENRY DREYFUS. DONALD FINLAYSON. CHARLES ERNEST STAFFORD.