US1580843A - Manufacture of artificial silk from viscose - Google Patents

Description

Patented Apr. 13, 1926.

UNITED STATES 1,580,843- PATENT OFFICE.

WILLIAM MENDEL, OF BEVERLY, NEW JERSEY, ASSIGNOR TO SAMUEL A. NEIDICH, O1 EDGEWATER PARK, NEW JERSEY.

MANUFACTURE OF ARTIFICIAL SILK FROM VISCOSE.

No Drawing.

To all whom it may concern:

Be it known that 1, WILLIAM MENDEL, a citizen of the United States, residing at Beverly, in the county of Burlington and State of New Jersey, have invented a certain new and useful Improvement in the Manufacture of Artificial Silk from Viscose, whereof the following is a specification.

llgy invention relates to the manufacture of aments projectin viscose (variously known as ce ulose sulphocarbonate or cellulose thiocarbonate) through minute spinneret orifices into baths containing chemicals which coagulate the viscose as a semisolid impure cellulose hydrate, which must be subjected to subsequent cleaning processes and thereafter dried to form the commercial artificial silk.

Natural silk filaments have an average diameter of .015 millimeter and, therefore, its is highly desirable to produce artificial silk filaments of approximately the same diameter. However, the aforesaid coagulated viscose elements must, of course, be of sufiicient strength to withstand the stresses of manipulation incident to their production, and as the viscose products of ordinary processes are much weaker and more frangible than the natural silk filaments; it has been found impossible to commercially manufacture viscose silk filaments which are less than double the diameter of the natural silk filaments. For instance, if dried in air, the minimum diameter of ordinary viscose silk filaments is .03051 millimeter and if viscose silk filaments are subjected to the action of glycerine, as is usual to improve their flexibility, the minimum ultimate diameter attainable is .03545 millimeter.

Therefore, an object and effect of my invention is to provide a method and means for commercially producing viscose silk filaments as fine, lustrous and elastic as natural silk filaments.

Various chemicals are used in the precipitating bath aforesaid. For instance, because of their prom t action and relatively low cost, strong acid baths, such as aqueous solutions containing eight percent of sulphuric acid or five percent of hydrochloric acid, are commonly used. With baths of that character, substantially all of the sulphur rimarily chemically combined with the cellulose in viscose is released as free sulphur, but is occluded in the mass of Application filed m 28, 1925. Serial No. 33,502.

cellulose hydrate, causing the latter to present an undesirable dull yellow white appearance, whereas, natural silk has a characteristic lustrous, translucent appearance. Therefore, such ordinary processes of coagulation must be supplemented by successive treatments of the coagulated viscose in chemical baths with a view to removal of the sulphur impurities therefrom. However, although such cleansing operations are only partially successful, they leave the viscose filaments weak, brittle and inelastic as compared with natural silk.

Microscopic examination of such ordinary viscose silk filaments discloses that their inherent weakness as compared with natural silk filaments is due to the fact that whereas, a natural silk filament is of substantially uniform homogeneous solid structure with a smoothly continuous surface; an ordinary viscose filament is of porous structure with a pitted surface; the formation of such pores and pits being incident to the primary inclusion and occlusion of sulphur derivatives in the cellulose hydrate and subsequent partial elimination of the same, leaving the cellulose hydrate of spongy texture.

Therefore, an object and effect of my invention is to provide a method and means for commercially producing viscose silk filaments without occluding free sulphur or its derivatives therein and to thus strengthen the coagulated cellulose hydrate filament by the elimination of pores and pits as aforesaid, and it is the attainment of that result which permits the formation of filaments, in accordance with this invention, as fine as natural silk filaments.

I have discovered that the desirable results aforesaid are attainable by subjecting viscose to the action of P0 ions. Such ions have a beneficial effect if added to or formed in the viscose, or in any bath in which vis cose may be coagulated, or in a fluid distinct from either the viscose or the coagulating medium, and in the latter case, may be either alone or in association with other matter affecting the viscose complex. For instance, the impure cellulose hydrate roduct of coagulation of viscose may be su jec-ted to P0 ions in a fluid containing dyeing material or detergent material.

PO ions have the apparent effect of preventing the formation of sulphur or its derivatives in insoluble form, and thus render the coagulated products ractically selfcleansing. However, if P 4 ions be added to or formed in the viscose before coagulating the same in the form of filaments, they have the effect of accelerating the regressive aging of the viscose which 1s manifested by progressive increment in viscosity of the viscose which may or not be desirable in accordance with the process of coagulation to which the viscose is to be subjected. However, in the form of my invention herein contemplated, I prefer to subject the viscose to the action of PO, ions in a bath in which the viscose is presented in the form of filaments; so that the aforesaid a 'ng effect of the P0 ions upon the uncoagu ated mass of viscose is avoided, but the viscose filament is beneficially affected by the P0 ions immediately upon introduction to such bath, and thus immediately strengthened to withstand the stresses to which it is subjected, in its pro ion through and from the bath. The P 4 ions may be added to or produced in such bath in any convenient form or manner. However, tri-sodium phosphate (Na POQ is a cheap vehicle for such ions and is further preferable because it may be conveniently used in aqueous solution.

In the form of my invention herein claimed; the vicose filament is subjected to a preliminary coagulating medium which is an acid salt. For instance, an aqueous solution containing sodium bi-sulphite (NaHSO,,) and salammoniac (ammonium chloride NILCL), and containing twenty-five per cent of the former and ten per cent of the latter. Such a bath promptly coagulates the viscose to an impure cellulose hydrate complex sufliciently coherent to be mechanically drawn through and from such bath over a roller. However, in the absence of P0 ions, such coagulated product contains the objectionable free sulphur and its derivatives above contemplated.

However, such complexes are rendered soluble and eliminated from the filament by subsequent subjection of the latter to the action of the bath containing PO, ions; which may be merely water containing three er cent orless of tri-sodium phosphate. I d that the presence of even a fraction of one per cent of PO, ions in such a bath has the advantageous results above contemplated, in the elimination of insoluble derivatives in or upon the filaments projected therein.

Filaments thus coagulated in accordance with my invention may require no subsequent treatment other than rinsing with water, as they are practically self-cleansing, in such PO ion bath, and emerge therefrom of substantially uniform homogeneous structure and with smooth surfaces. When such filaments are dried, preferably under tension, they have unusually high luster, strength in the appended claims.

I claim:

1. The method of manufacturin artificial silk filaments from viscose whic consists in coagulating viscose by pro ecting a fine filament thereof into a soft coagulating medium and thence into an ,aqueous solution containing PO, ions.

2. The method of manufacfiirin artificial silkfilaments from viscose which consists in coagulating viscose by projecting a fine filament thereof into a salt coagulating medium and thence into an aqueous solution containing PO, ions associated with other ions capable of afl'ecting such 00- agulation.

3. The method of manufacturin artificial silk filaments from viscose which consists in coagulating viscose by projecting a fine filament thereof into a salt coagulating medium and thence into an aqueous solution containing PO, ions, resultant from inclusion of tri-sodium phosphate (Na PO in such solution.

4. The method of manufacturin artificial silk filaments from viscose which consists in coagulating viscose by projecting a fine filament thereof into a salt coagulating medium and thence into an aqueous solution containing PO, ions, resultant from inclusion of tri-sodium phosphate (Na,PO,) in such solution, with another solute capable of afl'ectin such coa lation.

5. The metho of manu actuiing artificial silk from viscose which consists in projecting a filament of the latter into an aqueous solution containing sodium bi-sulphite (NaHsO and thence into an aqueous solution in which tri-sodium phosphate (Na,PO,) has been dissolved.

6. The method of manufacturing artificial silk which consists in projecting a filament of viscose (thiocarbonate) through an orifice less than .025 millimeter in diameter, into a salt coa lating bath, retaining said filament in said bath until partly coagulated, and thence projecting said filament into a bath containing PO ions.

7. The method of manufacturing artificial silk filaments from viscose by projecting a fine filament thereof into an acid salt coagulating medium comprising an aqueous solution containing twent -five percent of sodium bi-sulphite (NaH 0,) and ten ercent of ammonium chloride (NH retaining said filament in said coa ulating medium until partly coagulated, an thence projecting said filament into a bath containing PO ions.

8. The method of manufacturing artificial silk filaments from viscose by project ing a fine filament thereof into an acid salt coagulating medium comprising an aqueous solution containing twenty-five percent of sodium bi-sulphite (NaHSO and ten percent of ammonium chloride (NH CL); re-

taining said filament in said ooa medium until artly coagulate], an: thence projecting sai filament into a bath containing PO ions derived from aqueous solution of tri-sodium phosphate (Na POJ.

In testimony whereof, I have hereunto signed my name at Burlington, New Jersey, this 20th day of May, 1925.

WILLIAM MENDEL.

lating 10 projecting said filament into a bath containing PO ions.

8. The method of manufacturing artificial silk filaments from viscose by projecting a fine filament thereof into an acid salt coagulating medium comprising an aqueous solution containing twenty-live percent of sodium bi-sulphite (NaHSO and ten percent of ammonium chloride (NH CL); re-

taining said filament in said coa lating 10 medium until artly coagulated, am thence projecting sai filament into a bath containing PO ions derived from aqueous solution of tri-sodium phos hate (Na PO In testimony Whereo I have hereunto signed my name at Burlington, New Jersey, this 20th day of Ma 1925.

W LLIAM MENDEL.

Certificate of Correction. It is hereby certified that in Letters Patent No. 1,580,843, fainted April 13, 1926,

GI'SG upon the a plication of William Mendel, of Beverly e Manufacture of Artificial Silk from ment in New for an improve- Viscose,

errors a pear in the printed specification requiring correction as follows: Page 1i line 21, or the word its read it; page 2, line 79, claim 1, for the word soft rea salt; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiiee.

Signed and sealed this 4th day of May, A. D. 1926.

' M. J. MOORE Acting Commissioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,580 843, gninted April 13, 1926, upon the a Fplication of William Mendel, of Beverly Iiew Jersey, for an improvement in he Manufacture of Artificial Silk from Viscose, errors a pear in the printed specification requiring correction as follows: Page 1, line 21, or the word its read it; page 2, line 79, claim 1, for the word soft read salt; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiioe.

Slgned and sealed this 4th day of May, A. D. 1926.

[sun] v M. J. MOORE,

Acting C'mwmiasz'oner of Patents.