US2425782A - Preparation of filaments - Google Patents

Description

Aug. 19, 1947. E, BLUDWORTH ETAL 2,425,782

PREPARATION OF FILAMENTS Filed March 4, 1944 .IHHIII.

I N VEN TORS W R 0 W D U L B E H P E s O J N O 5 T U H D L E F N A C 0 w MA iatented Aug. 19 1947 UNITED STATES PATENT OFFICE PREPARATION OF FILAMENTS Joseph E. Bludworth and Canfield Hutson, Cumberland, Md., assignors to Celanese Corpora tion of America, a corporation of Delaware Application March 4, 1944, Serial No. 525,036

Claims.

This invention relates to the production of artificial filaments by spinning operations, and relates more particularly to the preparation by wet-spinning processes of artificial filaments having a basis of an organic derivative of cellulose, such as cellulose acetate, or other filamentforming material, from solutions of said filamentforming materials in a volatile solvent.

Artificial filaments or threads having a basis of an organic derivative of cellulose, such as cellulose acetate, or other filament-forming material, are usually prepared by extruding a solution of cellulose acetate in acetone under pressure through a jet on spinneret into an atmosphere of warm or hot air or other evaporative medium circulating through a spinning cabinet. The filaments become solidified on evaporation of the volatile solvent and are then associated to form a thread which is wound into a package form by suitable winding means. Such dry spinning operations require a substantial capital outlay since the cabinets are of a height of feet or more and large volumes of air must be heated and passed through the cabinets by means of blowers to carry oiT the voltaile solvent Vapors. Then, too, the Valuable solvent must be recovered from the air by means of an expensive solvent recovery system. To avoid these disadvantages, it has been proposed to prepare such artificial filaments by wet-spinning methods wherein a solution of cellulose acetate in acetone or other solvent is extruded through a jet or spinneret into an aqueous coagulating bath. Various coagulating baths have been suggested with a View toward producing strong and elastic filaments. Among the various coagulating baths which have been mentioned are aqueous baths containing thiocyanates and aqueous baths containing various organic compounds which are solvents or latent solvents for the filament-forming cellulose acetate material. These coagulating baths yield artificial filaments having somewhat improved properties over those obtained by extrusion into a water bath free of inorganic salts or organic solvents. However, it has not been possible, heretofore, by the usual wet-spinning operations, to form said filaments at spinning speeds greater than 66 to 100 meters per minute, which speeds do not approach the usual commercial spinning speeds achieved by. dry-spinning, and, consequently wet-spinning is comparatively uneconomical.

It is, therefore, an important object of this invention to provide an improved process for the production of artificial filaments having a basis 2 of an organic derivative of cellulose, such as cellulose acetate, or other filament-forming material by wet-spinning processes, whereby filaments of improved tenacity and elongation characteristics may be obtained.

Another object of this invention is the production of artificial filaments by wet-spinning processes at speeds substantially higher than those which have heretofore been practical on a commercial scale.

Other objects of this invention will appear hereinafter from the following detailed description and the accompanying drawing.

In the drawing:

Fig. 1 is a perspective View of our novel spinning apparatus for the production of artificial filaments by wet-spinning methods.

Fig. 2 is a perspective view of another embodiment of our novel spinning apparatus, and

Fig. 3 is a perspective view of another embodiment of our novel spinning apparatus.

Like reference numerals indicate like parts throughout the views of the drawing;

In accordance with our invention, the production of artificial filaments having a basis of cellulose acetate, or other filament-forming material, of improved tenacity and elongation characteristics may be achieved by extruding a solution of said filament-forming material in a volatile solvent through a jet or spinners-t into an enclosed chamber filled with a fog or mist, comprising droplets of a liquid in which the volatile solvent employed is soluble but in which the filament-forming material is insoluble, and then, after solidification oi the filaments in the chamber passing the solidified filaments into a bath of the liquid placed outside of the chamber. The volatile solvent evaporated from the filaments in the fog-filled chamber is absorbed by the fog or mist and the solvent remaining in the solidified filaments after they leave the chamber is Washed out in the liquid bath. After leaving the liquid bath, the filaments are dried in warm air, or other suitable, drying media. The filaments may then be collected in package form. The filaments obtained by our novel wet-spinning process are of substantially increased tenacity compared with filaments heretofore produced by wet-spinning operations and possess excellent elasticity characteristics. Furthermore, the filaments may be produced at spinning speeds of 300 meters per minute, and more. The filaments are of commercial quality. Optimum results are obtained with a solution of cellulose acetate in acetone by employing a fog or mist of Water droplets in the 3 spinning chamber and then passing the solidified filaments through a water bath or solution prior to forming the yarn package.

Preferably, the solution of cellulose acetate in the acetone is heated prior to extrusion. Suitable heating means may be provided and the temperature at which is it extruded may be from 80 F. to 206 F. The temperature of the water bath may be any temperature above the freezing point of water and may vary from temperatures as low as 33 F. up to 170 F. or more, but preferably the temperature is maintained at lower than the usual room temperatures. The water sprayed and atomized in or into the cabinet to form the fog or mist of water droplets through which the filaments pass may be any temperature above the freezing point of water or even be preheated, but preferably the temperature is from about 33 F. to 60 F. so that the temperatures of 40 F. to 60 F. are maintained in the cabinet.

In order further to illustrate our invention, reference may be had to the accompanying drawing.

Referring now to the drawing and more particularly to Fig. 1, reference numeral 3 indicates an enclosed cabinet of cylindrical or other shape provided at 3 and 5 with suitable spraying or atomizing nozzles adapted to form a finely divided fog or mist when water is forced through said nozzles under pressure. At the top of cabinet 3 is tube 6 connected to a candle filter l which carries at the lower end thereof a spinning nozzle or jet 8 through which the spinning solution is continuously extruded under pressure to form filaments 9. To heat the spinning solution prio to extrusion, candle filter l is surrounded by a heating jacket IE] adapted to receive a circulating fluid heating medium H, such as steam, hot water, heated oil or the like. The fluid medium II enters jacket l through a pipe l2 and is discharged through a pipe is.

Filaments 9 traverse a vertical path through the fog or mist in cabinet 3 and leave through a suitable opening id at the base of the cabinet 3. They are then taken up by a rotating feed roller l5, rotating in the direction shown, which is partly submerged in a trough l8 containing water or other non-solvent liquid. After making several revolutions about rotating feed roller l5, filaments 9 pass around an auxiliary rotating feed roller or thread guide ll, again around roller l and then through a suitable guide it to be taken up in any suitable manner to form a yarn package Hi. The feed roller [5, when rotating and partially submerged in trough l6, agitates and imparts motion to the water. The depth and quantity of water which adheres or clings to the outside circumferential surface of the revolving roller 15, is proportional to the speed of rotation. At higher speeds water tends to be flung from the wetted surface of the roller [5 by centrifugal force. In order to regulate the quantity of water retained on the roller surface and the throw-off, there is provided an adjustable dcctor blade, deflector or wiper l5-a, with a suitable facing of felt, rubber or other material. The volatile solvent which is evaporated from filaments 9 is dissolved by the water mist or fog which condenses in cabinet 3 and drips into trough E6. The solvent remaining in the filaments 9 is washed out during the passage of the filaments through the water bath. Suitable means (not shown) are provided for circulating the water in trough 95 whereby the solvent-laden water is continuously or intermittently removed and replaced with fresh water free of solvent. The liquid removed from trough I6 is then sent to a suitable solvent recovery system where the organic solvent is separated from the water, concentrated and then employed again to form a spinning solution. Suitable yarn finishes may also be added to the water bath, if desired.

In the embodiment of our invention shown in Fig. 2, the filaments 9 are extruded into the cabinet 3 through jet 3 and, after traversing through the fog or mist of Water droplets, the filaments are passed directly into the water bath or solution contained in trough iii. The running filaments 9 pass under guides 20 and 2| which are submerged beneath the liquid, then over guide 22 and around driven feed roller 23. The filaments leaving roller 23 are passed to suitable winding means (not shown) are then taken up to form a suitable yarn package if). In this modification of our invention, a somewhat increased path through the liquid bath in trough i6 is provided and the feed roller is outside of the bath instead of being submerged therein. In lieu of directing the filaments in a vertical path through cabinet 3, they may, of course, be caused to traverse a substantially horizontal or semihorizontal path, as shown in Fig. 3, by suitably positioning cabinet 3, or they may enter into the aqueous medium at any other desired angle. Entering the filaments into the water bath at an angle allows for a more extended path through the liquid bath.

While our invention has been more particularly described in connection with the production of filaments having a basis of cellulose acetate from solutions thereof in acetone, it is to be understood, of course, that the filament-forming material employed may be any other organic derivative of cellulose or any other suitable filament-forming material. Suitable organic derivatives of cellulose are, for example, cellulose esters, such as cellulose propionate or cellulose butyrate, mixed esters such as cellulose acetate-butyrate or cellulose acetate-propionate, or cellulose ethers, such as ethyl cellulose or benzyl cellulose. Other materials from which filaments may be formed by extrusion of said filament-forming material in a volatile solvent may also be employed in the preparation of artificial filaments by our novel wet-spinning process. As suitable volatile solvents which may be employed in lieu of acetone there may be mentioned ethyl etheralcohol, di-chlor-methane, carbon disulfide, etc., while suitable liquids in which the volatile solvents are soluble but in which the filament-forming material is insoluble and which may be employed to form the mist and the liquid bath are methanol, hexane, etc.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for the production of artificial filaments having a basis of a filament-forming material by wet-spinning processes, which comprises extruding a solution of a filament-forming material in a volatile solvent into a setting atmosphere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and saidfilament-forming material is insoluble, wherein saidextruded material is solidified, and

passing said solidified materials through a bath of said liquid.

2. Process for the production of artificial filaments having a basis of a filament-iorming material by wet-spinning processes, which comprises extruding a solution of a filament-forming organic derivative of cellulose mate-rial in a volatile solvent into a setting atmosphere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and said filamentforming material is insoluble, wherein said extruded material is solidified, and passing said solidified materials through a bath of said liquid.

3. Process for the production of artificial filaments having a basis of a filament-forming material by wet-spinning processes, which comprises extruding a solution of a filament-forming cellulose acetate material in a volatile solvent into a setting atmosphere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and said filament-forming material is insoluble, wherein said extruded material is solidified, and passing said solidified materials through a bath of said liquid.

4. Process for the production of artificial filaments having a basis of a filament-forming material by wet-spinning processes, which comprises extruding a heated solution of a filament-forming material in a volatile solvent into a setting atmos phere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and said filament-forming material is insoluble, wherein said extruded material is solidified, and passing said solidified materials through a bath of said liquid.

5. Process for the production of artificial filaments having a basis of a filament-forming ma.- terial by wet-spinning processes, which comprises extruding a heated solution of a filament-forming organic derivative of cellulose material in a volatile solvent into a setting atmosphere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and said filament-forming material is insoluble, wherein said extruded material is solidified, and passing said solidified materials through a bath of said liquid.

6. Process for the production of artificial filaments having a basis of a filament-forming ma terial by wet-spinning processes, which comprises extruding a heated solution of a filament-forming cellulose acetate material in a volatile solvent into a setting atmosphere consisting essentially of a mist of droplets of a liquid in which said volatile solvent is soluble and said filament-forming material is insoluble, wherein said extruded material is solidified, and passing said solidified materials through a bath of said liquid.

7. Process for the production of artificial filaments having a basis of a filament-forming material Iby Wet-spinning processes, which comprises extruding a solution of cellulose acetate in acetone into a setting atmosphere consisting essentially of a mist of water droplets wherein said extruded cellulose acetate material is solidified, and passing the solidified cellulose acetate material through water.

8. Process for the production of artificial filaments having a basis of a filament-forming material by Wet-spinning processes, which comprises extruding a heated solution of cellulose acetate in acetone into a setting atmosphere consisting essentially of a mist of water droplets wherein said extruded cellulose acetate material is solidified and passing the solidified cellulose acetate material through water.

9. Process for the production of artificial filaments having a basis of a filament-forming material by wet-spinning processes, which comprises extruding a solution of cellulose acetate in acetone heated to a temperature of F. to 206 F. into a setting atmosphere consisting essentially of a mist of water droplets wherein said extruded cellulose acetate material is solidified, and passing the solidified cellulose acetate material through water.

10. Process for the production of artificial filaments having a basis of a filament-forming material by wet-spinning processes, which comprises extruding a solution of cellulose acetate in acetone heated to a temperature of 80 F. to 206? F. into a setting atmosphere consisting essentially of a mist of Water droplets wherein said extruded cellulose acetate material is solidified, and passing the solidified cellulose acetate material through water at a temperature of 33 F. to F.

JOSEPH E. BLUDWORTH. CANFIELD l-IUTSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,838,121 Vles Dec. 29, 1931 2,032,606 Whitehead Mar. 3, 1936 2,054,852 Dreyfus Sept. 22, 1936 2,081,171 Dreyfus May 25, 1937 2,186,135 Childs Jan. 9, 1940 888,260 Planchon May 19, 1908 2,252,684 Babcock Aug. 19, 1941 1,979,403 Ostermann Nov. 6, 1934 2,161,354 Imray June 6, 1939 FOREIGN PATENTS Number Country Date 251,680 Great Britain Apr. 30, 1926 289,233 Great Britain Apr. 26, 1928 368,230 Great Britain Aug. 26, 1930 645,696 Germany June 2, 1937 175,296 Germany Sept. 7, 1906

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