US2294154A - Treatment of spinnerettes to prevent accumulations thereon - Google Patents

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STATE-S PATENT OFFIC TREATMENT OF SPINNERETTES TO PRE- VENT ACCUMULATION S THEREON Henri L. Barthelemy and Glover Hood Robinson, Rome, Ga... assignors, by mesne assignments, to American Enka Corporation, Enka, N. C., a corporation of Delaware Application April 25, 1941, Serial No. 390,334

' 11 Claims. (01. 18-8) This invention relates to the spinning of visthat, as a result thereof, the solid materials which cose rayon and has for its object the provision accumulate in the spin-bath, such as precipiof certain improvements in spinning apparatus tated sulphur, salts, complex compounds, etc., do and methods for suppressing the formation of not accumulate in and on the spinnerettes and incrustations and craters which form on metallic form the incrustations and craters as they do in spinnerettes. It is an object of the invention to th said practices. provide a methodof treating metallic spin- As a result of our investigations and discover- 4 nerettes to produce an improved spinnerette as ies, we have found that a sort of micro-film or a well as an improved arrangement of spinning cation-active compound can be caused to form apparatus for employing the improved spinon, or attach itself to, the metallic surface of a nerette. spinnerette and that it adheres thereto with a The invention contemplates the treatment of good degree of stability. Moreover, we have dismetallic spinnerettes with a cation-active comcovered that when, for instance, a gold-platinum pound to form a thin coating of the compound spinnerette is immersed in any Muller type of on the surface of the.spinnerette, and particuspin-bath, the splnnerette acquires a negative larly that portion thereof immediately surroundcharge which varies from about 50 to 300 milliing the orifices. The coating of cation-active volts. This potential is apparently of sufllcient compound is a very thin film, what may be remagnitude to prevent too quick a difiusion into garded as a sort of micro-film, and will hereint e bath f e C c ve C mpo forming after, for convenience, be called simply a film. the film. The time of protection afforded is The invention aims to provide an improved spinabout to days. We have found that a film ning method employing spinnerettes coated'with of the cation-active compound may be formed a cation-active compound and the maintenance on the metallic surface of spinnerettes by'treatof a spinning environment which preserves the ing the spinnerettes with an aqueous solution of film in stable attachment on the spinnerette. 20 a cation-active compound under conditions which We have found that a film of a cation-active eliminate the air layer on the metallic surface compound when applied toa metallic spinnerette and permit the film to form thereon. A very will enable the spinnerette to be used in a viscose effective method of accomplishing the removal spin-bath for relatively long periods without the 4 of the gas film and forming the film of cationaccumulation of incrusting substances near the active compound is to treat the spinnerettes in a outer surface of the orifices and which have hereboiling aqueous solution of the cation-active comtofore formed, especially in spin-baths free of pound for about fifteen minutes. However, fair cation-active compounds or rich in zinc sulphate. results can also be obtained by performing the Spinning operations carried out by using the same treatment in hotor lukewarm solutions, film coated spinnerettes of the invention will 3. preferably with the-help of a small difierence of produce, over relatively long periods of time, electrical potential to promote the migration of filaments of uniform normal denier and with the cation to the spinnerette, I practically no minute filaments such as cus- The optimum concentration of cation-active tomarily result from the accumulations of solid material in water is determined by systematic matter in the form of craters around, and in-- 0 tests, as cation-active compounds found on the crustations in, the orifices. market exhibit different activities, and as ex- In practices heretofore proposed and also comperience taught us there exists for each one an mercially used, cation-active compounds are optimum concentration above which spinning either mixed with the spinning solution, or disstability is impaired again. solved in the spin-bath for the purpose of pre- The invention in its more or less complete venting or suppressing the formation of the craaspects contemplates the provision of an imters and incrustations. In the said practicesit proved spinning method which comprises emis necessary to use a relatively large quantity of ploying a metallic spinnerette coated with a film the cation-active compound in the spinning soluof a cation-active compound under conditions tion, or in the spin-bath, as the case may be, in 5 causing the spinncrette to be under a negative order to effect a suppression of the accumulations electrical potential. In. spinning viscos rayon in and on the spinnerettes. It has been the prein accordance with the invention, th liquid envailing belief that the cation-active compounds vironment in contact with the spinnerette .is have a pronounced effect upon the surface tenkept substantially free of anion-active compounds sion of the medium in which it is dissolved and or other like materials or conditions tending to (30%) of platinum, is

displace or inhibit the cation-active compound from its stable attachment to the spinnerette.

In the accompanying drawing: Fig. l is a side view of a metallic spinnerette having a film or a cation-active compound on its surface, and Fig. 2 is a diagrammatic illustration of apparatus which may be used in a method of the invention.

In practicing the invention for producing a spinnerette coated with a film of cation-active compound, a metallic spinnerette, especially one formed of noble metal, for example a spinnerette formed of an alloy containing approximately seventy percent (70%) of gold and thirty percent thoroughly cleaned to remove adhering solid and liquid matter. The

cleaned spinnerette is submerged in a solution comprising, for example, approximately two grams of lauryl pyridinium chloride in one liter of distilled water. The solution is boiled for a sufiicient length of time to eliminate surface gases, about fifteen minutes being ordinarily suitable to accomplish this purpose. As the film of gas is removed from the surfac of the spinnerette, the cation-active compound attaches itself to the surface of the spinnerette in the form of a film which seems to have the characteristics of a micro-film. In applying the film of cationactive compound to a metallic spinnerette in the apparatus illustrated in Fig, 2, an aqueous solution of a cation-active compound, like lauryl pyridinium chloride, is heated in the basin until it becomes warm or hot and a small difference of electrical potential is applied to the spinnerette by means of the battery, to promote the migration of the cations to the spinnerette.

The spinnerette coated with the cation-active compound is removed from the solution and is thereafter dried in any suitable manner to remove the water, due precautions being taken not to disturb or injure the film. A satisfactory manner of removing the water is accomplished by heating the spinnerette in a ventilated drier at a temperature not exceeding 65 C.

The coated spinnerette is attached to the spinning apparatus in the usual' way, care being taken not to touch or otherwise disturb the film on the surface of the spinnerette in the immediate vicinity of the orifices. covers the large surfaces of the spinnerette, but seems to cover and coat the walls of the orifices themselves. The film appears to prevent wetting of the spinnerette by the spin-bath and also wetting of the insides of the orifices by the viscose solution. So long as the spinnerette is under a negative potential and the spin-bath substantially free of anion-active compounds, the film on the surface of the spinnerette remains in stable or firm adherence notwithstanding the solubility in the aqueous spin-bath of the cation-active compound forrning the film.

While many cation-active compounds are suitable for the purposes of this invention, we have found that lauryl pyridinium chloride, cetyl pyridinium bromide (sold by du Pont under the trade name Fixanol), and a product sold by Carbide and Carbon Chemicals Corporation under its trade nam Amine 22L are desirable because of their effectiveness and availability.

Spinnerettes formed of the noble metals, for example gold, platinum and palladium and alloys thereof, have negative potentials when in the presence of acid spinning baths and may be used The film not only in the apparatus and method of the invention. 7

Spinnerettes formed of tantalum may likewise beused.

In the usual viscose spinning operation, and particularly in those operations which employ relatively large quantities of zinc sulphate in the spin-bath, the orifices of the metallic spinnerettes become incrusted with solid matter of indefinite composition, which also frequently forms craters around the orifices. These incrustations and/or craters obstruct the free passage of spinning solution through the orifices, causing what is known as slow holes. These slow holes cause the filaments to be much smaller in diameter than they would normally be. These incrustations and craters form at such a rapid rate that the spinnerettes must be subjected to frequent inspection, for example once every forty-eight hours, to keep them in operating condition. Inspection includes removing the spinnerettes from the spin-bath, rubbing the surface with the thumb to remove the craters and seeing whether the flow from any of the holes appears sluggish. If the flow is sluggish, the spinnerette must be dismounted and replaced. When, however, the spinnerettes are coated with a film of a cation-active compound according to the invention, they may be operated continuously for a week or more without inspection and without producing any appreciable quantity of minute filaments.

The invention not only eliminates the necessity of contaminating the viscose and the spinbath with a cation-active compound in order to eliminate incrustations and craters, but it also reduces the quantity of the compound necessary for the purpose to almost an immeasurably small quantity.

We claim: I

l. A metallic spinnerette comprising a film of a cation-active compound in stable attachment on the surface of the metal.

2. Apparatus for the spinning of viscose which comprises a metallic spinnerette having a film of a cation-active compound, and means for maintaining said spinnerette under a negative electrical potential during spinning.

3. The method of treating a metallic spinnerette which comprises cleaning the spinnerette to remove solid or liquid matter, submerging the cleaned spinnerette in a hot solution of a cationactive compound for a sufiicient time to permit the cation-active compound to displace gas from the surface of the spinnerette and to form thereon a film of the cation-active compound.

4. The method of treating a metallic spinnerette which comprises heating the spinnerette in an aqueous solution of a cation-active compound for a sufficient time to form a film of the cationactive compound on the surface of the spinnerette.

' 5. The method of treating a metallic spinnerette which comprises submerging the spinnerette in a .boiling aqueous solution of a cationactive compound for a sufficient time to form a film of the cation-active compound on the surface of the spinnerette, removing the spinnerette from the solution, and evaporating water from the surface of the spinnerette. I

6. In a method of spinning viscose, the improvement which comprises employing a metallic spinnerette having in stable attachment on its surface a film of a cation-active compound, maintaining the spinnerette under a negative electrical potential, and maintaining the liquid environment in contact with the spinnerette sufficiently free'of anion-active compounds to maintain the film of cation-active compound for a relatively long period.

7. In a method of spinning viscose, the improvement which comprises applying a film of a cation-active compound on the spinnerette, placing the spinnerette in the spin-bath, and maintaining the spinnerette under a negative electrical potential and the spin-bath free of anionactive compounds that will displace the said film.

8. A spinnerette formed of a. noble metal comprising a film of a. cation-active compound in stable attachment on the surface of the metal.

9. Apparatus for the spinning of viscose which comprises a spinnerette formed of a noble metal having a film of a cation-active compound, and

, 3211sv f9. ,maintaining said spinnerette under a v negative electrical potential during spinning.

10. In a method of spinning viscose, the improvement which comprises employing a spinnoble metal having in stable HENRI L. BARTHELEMY. GLOVER HOOD ROBINSON.

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