US2070031A - Lusterless yarn from cellulose acetate - Google Patents

Description

Patented Feb. 9, 1937 UNITED STAES LUSTERLESS YARN FROM CELLULOSE ACETATE Herbert G. Stone and Henry R. Childs, Kingsport, Tenn, assignors, by mesne assignments, to Eastman Kodak Company, Jersey City, N. 5., a corporation of New Jersey No Drawing. Application November 5, 1932, Serial No. 641,466

8 Claims.

This invention relates to cellulose organic ester yarn, and particularly to such yarn which is substantially lusterless. In recent years much attention has been directed to reducing the luster of artificial silk or rayon, in order to make it more closely resemble natural silk. Woven or knitted rayon textiles have been subjected to after-treatments designed to reduce the luster. The effects of some of these after-treatments are not permanent, and in any case the after-treatment constitutes an added step in the manufacture of the textile. Pigments have been introduced into the spinning solutions from which the rayon threads are spun, in order to produce dull luster yarn. Yarns so produced, however, are of lower strength than unpigmented yarns.

One object of our invention is to provide substantially lusterless cellulose organic ester yarn which is free from pigments and other loading materials. Another object is to provide a process for making such yarn. Other objects will hereinafter appear.

We have discovered that substantially lusterless cellulose organic ester yarn having strength and stretch characteristics approximating those of good bright-luster yarns may be produced by adding a small percentage of certain petroleum fractions to the cellulose organic ester solution from which the thread is to be spun by the dry spinning method. As is well known in the art, in the dry spinning method for producing cellulose acetate yarn a solution of cellulose acetate is extruded from a spinneret, into a long narrow cell through which passes an evaporative atmosphere such as a current of heated air. The thread so formed is usually stretched before being wound up, preferably by being passed over a draw-roll whose circumferential speed of rotation is greater than the rate at which the thread emerges from the spinneret. One modification of this form of dry spinning process is described in the co-pending application of Herbert G. Stone, Serial No. 634,185 filed September 21, 1932. Our process for producing substantially lusterless yarn may be carried out by the particular method described in that application, or by any of the known methods of dry spinning.

The petroleum fractions which we use in carrying out our invention are those whose boiling ranges lie between 150 C. and 230 C. Fractions boiling below 150 C. are not satisfactory for our purpose on account of their high volatility and the fact that they do not have an appreciable delustering action. Fractions boiling above 230 C. act as more or less viscous lubricants, and do not effect the desired result of producing a lusterless thread. We prefer to use a petroleum fraction whose boiling range lies between 150 and 200 C. We may use a fraction boiling between 200 and 230 C., but in this case the spinning conditions must be very closely controlled in order to secure uniformly lusterless thread.

As a solvent for making up our spinning solutions, we prefer to use acetone containing a small amount of water. The use alone of acetone containing a small amount of Water results in a thread with a bright luster. However, when a small percentage of one ofthe petroleum fractions described above is added to the solution, the thread produced is substantially lusterless. Preferably, the temperature of the evaporative atmosphere into which the thread is extruded should at nopoint be above the minimum of the boiling range of the petroleum fraction employed. We have, however, found that it is desirable to maintain higher temperatures in spinning lusterless yarn by our process than in spinning brightluster yarn from solution in acetone containing a small amount of Water, but containing no petroleum fraction.

The following example is given as illustrative of one method of carrying out our invention. It is to be understood, however, that the invention is in no way limited thereby, except as indicated in the appended claims.

Composition of typical spinning solution The spinning conditions employed, while not absolutely critical, must be regulated, as indicated above, in order to obtain the best results. A spinning cabinet from 15 to- 20 feet high and preferably less than a foot in diameter is suitable to employ. The inlet for the current of heated evaporative atmosphere is, of course, at the bottom of the cabinet. The air outlet is preferably located at a point approximately to of the distance from the top of the cabinet. We have found that, if the spinning solution is introduced at a temperature of approximately 67 0., good results can be obtained, although this temperature may vary several degrees either way. Under the foregoing conditions, an air inlet temperature of approximately 120 C. and an air outlet temperature of about 90 C. has been found satisfactory. The humidity of the evaporative atmosphere should not be too high, the humidity resulting from the use of air which is saturated at C. to 5 C. being satisfactory. Under the foregoing conditions one may employ a draw-roll speed of, for instance, 220 meters per minute and a space velocity for the evaporative atmosphere of from 20 to 25 cubic feet per minute. These conditions may, of course, be varied considerably, although reduction of the temperatures and of the space velocity of the air will slow down the spinning speed. We have also found that the more rapid th evaporation of the solvent from the yarn after its extrusion from the spinneret, the greater the delustering of the yarn. Rapid evaporation of the solvent may be brought about either by increased temperature of the current of evaporative atmosphere or by increased space velocity thereof. This increased delustering efiect is quite unexpected as one would ordinarily assume that the higher the temperature of spinning the more readily the petroleum fraction would leave the yarn'and hence that delustering would be lessened by its loss. Contrary to this expectation we have found that subjecting the yarn to unusually high evaporative temperatures causes very rapid evaporation of the solvent from the surface of the, yarn with skinning over thereof, so that the hydrocarbon remains occluded in the interior of the yarn. This is supported by the facts that finished yarn produced by our process contains appreciable amounts of the hydrocarbon employed in the spinning solution, and that microscopic examination of the finished yarn shows it to be lusterless throughout its entire cross-sec- 7 tion.

The amount of petroleum fraction may be varied from about 2% to about 6% of the weight of the spinning solution. The cellulose acetate employed may be anyacetone-soluble cellulose acetate. The concentration of cellulose acetate in the solution may be varied considerably, although from 25% to 28% concentration is most satisfactory. The water content of the solution may be varied, or may be omitted altogether; more than 6 to 8% or possibly 10% should not,

however, be used, as it will have a precipitating action upon the cellulose derivative. Other well known solvents for cellulose acetate, which are miscible with our petroleum fractions, may be substituted for acetone, such, for instance, as ethylene chloride-alcohol and the like. Other lower aliphatic esters and mixed esters of cellulose, such, for instance, as cellulose propionate,

cellulose butyrate, cellulose acetate-.propio'nate,

cellulose aoetate-butyrate, etc., may be used in place of cellulose acetate, 2. suitable solvent which gives flexible threads of the cellulose ester and which is miscible with our petroleum fractions being employed in the same manner as above set forth. The spinning conditions given above have been found to give good results, but any or all of them may be varied within considerable limits, according to the judgment of the operator. In order to obtain uniformity lusterless yarn, however, they should be held as nearly constant as possible during the spinning of any given batch of thread.

What we claim as'our invention and desire to be secured by Letters Patent of the United States is:

1. Unpigmented, solid, cellulose organic ester yarn, lusterless throughout its entire cross-section and permanently containing a petroleum fraction whose boiling range lies between 150 C, and 200 C., the filaments of the yarn having been subjected during their formation to an evaporative atmosphere maintained at a temperature between 90 C. and the lowest boiling point of the petroleum fraction.

2. Unpigmented, solid, cellulose acetate yarn,

lusterless throughout its entire cross-section and permanently containing a petroleum fraction whose boiling range lies between 150 C. and 230 0., the filaments of the yarn having been subjected during their formation to an evaporative atmosphere maintained at a temperature between 90 C. and the lowest boiling point of the petroleum fraction.

3. Unpigmented, solid, cellulose acetate yarn, lusterless throughout its entire cross-section and permanently containing. a petroleum fraction whose boiling range lies between 150 C. and 200 C., the filaments of the yarn having been subjected during their formation to an evaporative atmosphere maintained at a temperature between 90 C. and the lowest boiling point of the petroleum fraction.

4. Unpigmented, solid, cellulose organic ester yarn, lusterless throughout its entire cross-section, and permanently containing a petroleum fraction whose boiling range lies between 150 C. and 230 C., the filamentsof the yarn having been subjected during their formation to an evaporative atmosphere maintained at a temperature between 90 C. and the lowest boiling point of the petroleum fraction.

5. A process of producing, by the dry spinning method, unpigmented, solid, cellulose organic ester yarn, lusterless throughout its entire cross- 7 section, which comprises extruding a spinning solution containing an organic ester of cellulose and from 2% to 6%, approximately, of a petroleum fraction whose boiling range lies between 150 C. and 230 0., into a current of evaporative atmosphere, substantially all of which current is at a temperature between about 90 C. and the minimum of the boiling range of the petroleum fraction.

6. A process, of producing, bythe dry spinning method, unpigmented, solid, cellulose acetate yarn, lusterless throughout its entire cross-section, which comprises extruding a spinning solution containing cellulose acetate and from 2% to 6% approximately, of a petroleum fraction whose boiling range lies between 150 C. and 230 0., into a current of evaporative atmosphere, substantially all of which current is at a temperature between about 90 C. and the minimum of the boiling range of the petroleum fraction. V

'7. A process of producing; by the dry spinning method, unpigmented, solid, cellulose organic ester yarn, lusterless throughout its entire cross-' section, which comprises extruding a spinning solution containing an organic ester of cellulose and from 2% to 6%, approximately, of a petroleum fraction whose boiling range lies between 150 C. and 200 C., into a current of evaporative atmosphere, substantially all of which current is at a temperature between about 90 C. and the minimum of the boiling range of the petroleum fraction.

8. A process of producing, by the dry spinning method, unpigmented, solid, cellulose acetate HERBERT G. STONE. HENRY R.'CHILDS.