US2515697A

US2515697A - Treatment of spinnerettes

Info

Publication number: US2515697A
Application number: US659875A
Authority: US
Inventors: Cresswell Arthur
Original assignee: American Cyanamid Co
Current assignee: Wyeth Holdings LLC
Priority date: 1946-04-05
Filing date: 1946-04-05
Publication date: 1950-07-18
Anticipated expiration: 1967-07-18

Description

Patented July 18, 1950 2,515,697 TREATMENT or SPINNERETTES Arthur Cresswell, Stamford, Conn., assignor to American Cyanamid Company, New York, N. Y., a corporation oi. Maine N Drawing. Application April 5, 1946, Serial No. 659,875

8 Claims. ,1 The present invention relates to the treatment of spinnerettes employed in the production of synthetic or artificial filaments and threads and more particularly to the treatment of spinnerettes employed in the wet spinning" of such filaments and threads to prevent plugging of the minute orifices contained in such spinnerettes.

Synthetic or artificial threads and filaments are generally prepared by extrusion through very small orifices located in a multi-orifice spinnerette. Such newly formed filaments are then frequently passed into a spinning bath containing dissolved salts, acids or bases depending upon the particular material extruded. This is the socalled wet spinning method in contrast to dry spinning methods where no spinning bath is employed. Difiiculties with keeping the spinnerette orifices open are encountered in wet spinning both in starting up the spinning operation and in the course of such operation. These dimculties are occasioned by the strong tendency of the newly formed filaments to adhere to the metal surface of the spinnerette when the filaments or threads are prepared from protein materials as in the process disclosed in copending application Serial No. 527,339, filed March 20, 1944. Particular diificulty is experienced in starting up the spinning operation where the first portion of the extruded filaments must be pulled away from the spinnerette and attached toa spool. Also, if in the course of operation impurities or air bubbles interrupt the continuity of the filament extrusion, the extrudate tends to form a tenacious film over the surface of the spinnerette causing further filament rupture and eventually plugging a large number, if not all, of the orifices. In the extrusion of viscose rayon to form filaments, difliculty is likewise occasioned .by the adherence of minute particles which are insoluble in the spinning bath and which likewise tend to plug the spinnerette. The viscose rayon filaments and threads are formed by extrusion of the plastic viscose into a spinning bath containing dilute H2804, ZnSO4 and NazSO4, and it is believed that the plugging difficulties experienced in the operation of the spinnerette are due to the formation of very small particles of elemental sulfur which adhere to the surface of the spinnerette immediately adjacent to the orifices. The growth of the adhering deposit of insoluble particles results in encrustation and plugging of the orifices. In the formation of protein filaments and threads such as those prepared from soy bean protein, casein, collagen, keratin, gelatin and the like, there is apparently no reaction with the material contained in the spinning bath, the filament formation being solely a process of coagulation. Thematerials contained in the spinning bath used in the formation of protein filaments are the necessary acid-or base required to maintain the pH at the desired value, formaldehyde, and such salts as A12(SO4)3, Na2SO4 (NH4) 2304 and the like.

It has been discovered that the above detailed difficulties with plugging of the spinnerette in the production of artificial threads and filaments can be substantially eliminated by applying a film of a silicone to the surface of the spinnerette. Covering the metal surface of the spinnerette with a film of silicone apparently results in sub stantial elimination of any tendency for the newly formed filaments or other materials to adhere to the surface of the spinnerette. Accordingly, in starting up the spinning operation the filaments are more easily pulled away from the spinnerette for attachment to the winding spool and any interruption in the filament extrusion in the course of production does not result in plugging, such broken filaments being carried along with the large number of other filaments emerging from the spinnerette. Likewise, the tendency to encrustation in the production of viscose rayon filaments and threads is considerably reduced, the minute impurities formed in the course of the reaction which results in the rayon filament having a considerably reduced tendency to adhere to the surface of the spinnerette.

The silicones employed in the present invention have been described in U. S. Patents Nos. 2,258,219-2,258,222, inclusive, as linear polymers oi silicon in which the following is believed to be the structural unit where the Rs may be hydrogen and the same or different aliphatic or aryl radicals. The silicon and oxygen atoms are directly connected, alternating in the chain of which the polymer is composed.

The silicones are employed in solution in a volatile organic solvent such as benzene, toluene, butylacetate, ethylacetate, ether, acetone and the like. The solution may contain from 0.01% to 25% of silicone, preferably 5%, and is applied to the spinnerette by any suitable means such as spraying, or brushing or simply by dipping the spinnerette into the silicone solution. The solvent is evaporated at a suitable temperature,

preferably below 100 C. In order to insure keeping the orifices of the spirmerette open it is advisable to blow or draw air or other gas through the orifices of the spinnerette while the solvent is being evaporated. Preferably the air is drawn through the orifices from the outside of the spinnerette to the inside to draw the silicone through said orifices and coat the orifice walls and the inside surface of the spinnerette immediately adjacent to said orifices. While this results in a film suitable for use in wet spinning filaments a more adherent film is obtained by curing" the film of silicone by suitable heat treatment. The heat treatment required depends upon the particular silicone involved, but generally the film is heated at 150-250 C. for V -6 hours, the longer periods of time being required at the lower temperatures. However, periods as long as 24 hours have been required in some cases especially where temperatures below 150 C. must be employed. It is believed that the curing operation results in the formation of cross-linkages between the respective chains of the silicone linear polymer.

A spinnerette treated according to the process of the present invention may be employed in the extrusion of a dilute organic acid solution of collagen containing from 5-15% of the latter, said spinnerette being immersed in a spin bath containing at least 35% ammonium sulfate and maintained at a pH of 7.8 without initial sticking and with substantially no stoppage during operation.

The following is a description of the preferred procedure of the present invention: A 5% solution of a silicone in toluene is prepared and the spinnerette to be treated is dipped into the silicone solution. The solvent isremoved by evaporation at a temperature not exceeding 100 C. while drawing air through the spinnerette orifices from the outside to the inside. After evaporation of the toluene the spinnerette is heated at 150-250 C. for a period sufficient to cure the silicone film and render it more strongly adherent and resinous. In the case of methyl silicones heating at 225 C. for 1-2 hours or at 200 C.

for 3-6 hours is suflicient to effect curing while the phenyl silicones heating at 250 C. for 1-3 hours or at 225 C. for 6-15 hours is sufflcient while in the case of methyl phenyl silicone heat ing at 175 C. for about 25 minutes is all that is required to cure the film. Examples of silicones which may be applied in this manner are methyl phenyl silicone, ethyl phenyl silicone, ethyl chlorophenyl silicone, diphenyl silicone, diethyl silicone, dibutyl silicone, dipropyl silicone, propyl phenyl silicone and the like.

To facilitate further starting up of the spinning operation and pulling away the first portion of the extrudate for attachment to a winding spool, a thin film of an amine of the type disclosed in copending application Serial No. 580,081, now Patent Number 2,475,128, filed February 27, 1945, may be applied to the spinnerette over the silicone film. Such amines are of the formula where R1 is a member of the group consisting of hydrogen, alkyl, aryl and acyl radicals and R2 may be any aliphatic radical containing more than eleven carbon atoms. Such amines form films only slightly adherent, wearing ofi' readily as the spinning operation proceeds and, therefore, must be renewed almost every time on the occa- 4 sion of starting up the spinning operation. Such a film of amine is preferably applied to the more strongly adherent silicone filament resulting from the aforementioned curing process because of the manipulative difiiculties involved in applying the film of amine without disrupting the continuity of the film of silicone which has been applied simply by evaporation.

What is claimed is:

1. A metallic spinnerette carrying an adherent cured film of a silicone consisting of a linear polymer of the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the R's being the same or different.

2. A metallic spinnerette carrying an adherent cured film of a methyl silicone consisting of a linear polymer of the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the HS being the same or different.

3. A metallic spinnerette carrying an adherent cured film of a phenyl silicone consisting of a linear polymer of the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the R's being the same or different.

4. A metallic spinnerette carrying an adherent cured film of a silicone consisting of a linear polymer of the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the Rs being the same or different upon which is superimposed a film of an amine of the following formula RAPE where R1 is a member of the group consisting of hydrogen, alkyl, aryl and acyl radicals and R2 may be any aliphatic radical containing more than eleven carbon atoms.

5. In a wet spinning process comprising extruding a suitable liquified material through a spinnerette into a spinning bath wherein said material is solidified into threads, filaments and the like, the improvement comprising using a spinnerette carrying an adherent cured film of a silicone consisting of a linear polymer of the structural unit R [has] in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the R's being the same or difierent.

6. In a wet spinning process comprising extruding a suitable liquifled material through a spinnerette into a spinning'bath wherein said material is solidified into threads, filaments and the like, the improvement comprising using a spinnerette carrying an adherent cured film of a methyl silicone consisting of a linear polymer oi! the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the R's being the same or diflerent.

7. In a wet spinning process comprising extruding a suitable liquified material through a spinnerette into a spinning bath wherein said material is solidified into threads, filaments and the like, the improvement comprising using a spinnerette carrying an adherent cured film of a phenyl silicone consisting of a linear polymer of the structural unit in which R is a member of the group consisting of hydrogen, aliphatic, and aryl radicals, the It's being the same or different.

8. In a wet spinning process comprising extruding a suitable liquified material through a spinnerette into a spinning bath wherein said material is solidified into threads, filaments 'and thelike, the improvement comprising using a spinnerette carrying an adherent cured film of a silicone consisting of a linear polymer or the structural unit REFERENCES CITED The following references are of record in the file oi. this patent:

UNITED STATES PATENTS Number Name Date 2,100,581 weeldenburg Nov. 30, 1937 2,294,154 Barthelemy et al. Aug. 25, 1942 2,310,207 Bley Feb. 9, 1943 2,333,206 Sloan Nov. 2, 1943 2,356,542 Sloan Aug. 22, 1944 2,386,259 Norton ..l.'.. Oct. 9, 1945 2,386,466 Hyde Oct. 9, 1945 2,405,988 Barry Aug. 20, 1946

Claims

8. IN A WET SPINNING PROCESS COMPRISING EXTRUDING A SUITABLE LIQUIFIED MATERIAL THROUGH A SPINNERETTE INTO A SPINNING BATH WHEREIN SAID MATERIAL IS SOLIDIFIED INTO THREADS, FILAMENTS AND THE LIKE, THE IMPROVEMENT COMPRISING USING A SPINNERETTE CARRYING AN ADHERENT CURED FILM OF A SILICONE CONSISTING OF A LINEAR POLYMER OF THE STRUCTURAL UNIT