US2341509A - Viscose solution - Google Patents

Description

PatentedFeb. 15, 1944 D 2,341,509 VISQOSE SOLUTION Rudolph S. Bley, lVIilllgan College, Team, assignor to North American Rayon Corporation, New York, N. Y.. a corporation of Delaware No Drawing. Original application November 6,

1937, Serial No. 173,111. Divided and this application May 24, 1940, Serial No. 336,964

' Claims. (01. 106-164) This is a division of my application Serial No. 173,111 filed November 6, 1937, for "Viscose sponge."

The present invention relates to a process of producing viscose sponges by regenerating the cellulose 01 viscose solutions in a porous form.

One object of my invention is to provide for a process of producing a viscose sponge by dispersing a gas-forming substance in a viscose solution to form a composition which is subsequently expanded by means of gas bubbles evolved therein.-

Another object of this invention is to provide for a process of producing a viscose sponge by dispersing at least one substance selected from the group consisting of metals, metal alloys and metal carbides in a viscose solution 'and subsequently expanding and setting the dispersion with or without application of heat in a container, said substance or substances being able to react with the alkali of said viscose solution with the formation of an inert gas.

A further object of my invention is to provide for a process of producing self-sterilizing viscose sponges which contain or are devoid of added fibers.

Other objects of this invention will become apparent to those skilled in the art from a study of the following specification.

I am well aware that viscose sponges have, heretofore, been produced by expanding viscose solutions with carbon dioxide or by incorporating soluble crystals and the like into viscose solutions,

etc. (Vide U. S. Patent No. 1,142,610 to Pum; U. S. Patent No. 1,611,056 to Mostny; U. S. Patent No. 1,909,629 to Pfannenstiel; U. S. Patent No. 1,974,-

i 393 to Mostny; U. S. Patent No. 2,011,160 to Plepp; U. S. Patent No. 2.026,177 to Johannes; U. S. Patent No. 2,043,564 to Vautier et al.; etc.)

By extensive experimentation. I have foundvided magnesium is especially suitable for the production of viscose sponges, since it generates hydrogen only at higher temperatures in the presence of alkalis. This slow gas evolution leads to viscose sponges having small pores of even size.

In order to slow down the gas evolution of some metals, and thus to control the expansion of viscose solutions, it is preferable to use them in the form of alloys. Alloys of magnesium with antimony, bismuth, cadmium, calcium, lead, mercury,

' which regenerated cellulose is not decomposed.

These metals and metal alloys may be replaced by metal carbides, such as boron carbide, calciumcarbide, aluminum carbide, lithium carbide, mang'anese carbide, sodium carbide, strontium carbide, barium carbide, etc., i. e., by any metal carbide which is decomposed by alkali with the formation of acetylene. pound which generates hydrogen gas in the form of fine bubbles is for example dicyan-diamid, and thus this compound is very suitable for the production of viscose sponges from viscose solutions. Instead of using one metal, I may use a combination of gas-generating metals or combinations of metals, metal alloys, metal carbides, etc. Thus, I may combine a finely divided aluminum powder with a fine magnesium powder and subsequently ,disperse this mixture in a viscose solution, etc. I may also disperse a metal, an alloy one metal carbide together with a bactericidal metal, such as gold, silver, copper, etc. and

introduce this dispersion into a viscose solution to form after expansion and setting self-sterilizing viscose sponges. Bactericidal metals are colloidal metals which are not attacked by viscose solutions with the formation of gases. These metals are added in very small quantities to the viscose solution to avoid the formation of abrasive viscose sponges. They may be pre-irradiated with ultra-violet rays to increase their bactericidal effect. In other words, I may use all bactericidal metals as well as combinations thereof with other bactericidal agents set forth in my U. S. Patents Nos. 2,072,808 and 2,072,809,

granted March 2, 1937.

Since viscose sponges have proven to be rather weak, I prefer to add fibers, such as hemp, cellulose, hair, etc., to the viscose solutions to impart more strength and durability to the sponges produced therefrom in accordance with my present invention. Although the gas-generating metals may be added first to the viscose solutions before admixing therewith a suitable amount of fibers, I prefer to mix the fibers first with the viscose solution and then to disperse the metal, metal alloy or metal carbid therein to prevent spontaneous gas-evolution. In this manner the fibers appear to act as retarding agents with the result that sponges of small and even pore size are formed. Instead of introducing the gas-8e11- A non-metallic comtainers.

crating substance in a dry form into the viscose solution, I prefer to grind it in an anion-active or a cation-active wetting agent to form a more or less viscous dispersion which subsequently is introduced into the Viscose solution. Besides producing a more even distribution of the gas-gencrating substance in the viscose solution, these wetting agents, such as sulphonated oils, high molecular amines, etc., serve as retarding agents due to the fact that the alkali must first remove the oil film from the gas-generating substance before it is able to attack the same with the evolution of a gas in the form of fine bubbles. Any commercial emulsifying agent ma be used for this purpose such as Avirol, Gardinol, sulphonated vegetable oils, quaternary ammonium bases and salts having a long fat 'chain, etc.

The amounts of these gas-forming substances used in combination with a viscose solution may be varied within wide limits without detrimentaliy affecting the durability of the finished sponge, although I have found an addition of about 0.1 to 0.5% by weight to give excellent results. Since aluminum, for example, is a trivalent element it will generate more hydrogen than magnesium which is divalent, and in order to obtain the identical expansion of the viscose solution the amount of aluminum must be replaced by stoichiometric amounts of other gasforming substances. By varying the amount of gas-generating substance in a given amount of a viscose Or a fibrous viscose composition, it is possible to obtain viscose sponges having any degree of porosity. The viscose solution may be a conventional spinning solution containing about 7% of cellulose by weight, although I do not wish to be limited to the use of this particuiar viscose solution, since it may contain more or less cellulose. lution of conventional maturity, I may make use of underripe or overripe viscose solutions, the latter being waste viscose solutions unsuitable for the spinning of rayon.

Any type of natural and synthetic fiber, such as cotton, hair, hemp, cellulose waste, rayon waste, asbestos, etc., may be admixed with the viscose solutions to impart strength, durability or other properties to the finished sponges. The fibrous or non-fibrous viscose compositions are placed in containers and expanded therein with or without application of heat. These containers may be provided with orifices to allow introduction of steam, hot water, acid or salt solutions or acid vapors to accomplish and/or accelerate the regeneration of the cellulose contained in the viscose solution. After expanding and setting the viscose solutions or compositions, the viscose sponges may be removed from the containers and washed to remove all decomposition products contained therein. The expansion of the viscose solutions in the containers may be accelerated by evacuating the same, and it may be retarded by applying pressure to the containers. Before dispersing the gas-forming substance or substances in the viscose solution or composition the latter may be cooled to reduce the speed of evolution of as bubbles therein before placing it in the con- Example About 100 grams of a 7-20% viscose solution are intimately mixed with about 10 grams of a fiber, such as cotton, hemp, flax, etc. Subsequently about 0.1 to 0.5 gram of a finely divided aluminum powder, preferably ground in a wetting agent, are dispersed in this mixture.

Instead of using a viscose so-- This mixture is subsequently treated in a container for about an hour with steam at a pressure of about 5 atmospheres. The resultant sponge is thoroughly washed with water, bleached and dyed as required. A stoichiometric amount of another gas-forming substance may replace aluminum in this mixture. Finely divided refractory materials, such as titanium dioxide, etc., may be added to the composition before expanding it in the container to form abrasive sponges. To prevent decomposition of the sponges by bacteria and molds, bactericidal metals, etc., may be dispersed in the viscose solution or composition. The perforated container may be boiled in acid or salt solutions to regenerate the cellulose contained in the viscose solution in a porous form.

Although this example will serve to illustrate the invention, I wish to emphasize that I do not desire to be limited to the process set forth therein since it may be varied within wide limits without detrimentally affecting the final products resulting from such variations. Modifications of this process will readily be recognized by those skilled in the art, and I desire to include all such modifications and variations coming within the scope of the appended claims.

I claim:

1. A viscose solution for the manufacture of viscose sponges containing a finely divided substance selected from the group consisting of metals, metal alloys and metal carbides in a sufiicient amount to form upon the regeneration thereof a porous sponge of regenerated cellulose, said substance being capable of evolving a gas by chemical interaction with said viscose solution and being dispersed in a wetting agent to retard the evolution of said gas in said viscose solution.

2. A viscose solution for the manufacture of viscose sponges containing a finely divided metal in a sufiicient amount to form upon the regeneration thereof a porous sponge of regenerated cellulose, said metal being capable of evolving a gas by chemical interaction with said viscose solution and being dispersed in a wetting agent to retard the evolution of said gas in said viscose solution.

3. A viscose solution for the manufacture of viscose sponges containing a finely divided metal alloy in a suflicient amount to form upon the regeneration thereof a porous sponge of regenerated cellulose, said metal alloy being capable of evolving a gas by chemical interaction with said viscose solution and being dispersed in a wetting agent to retard the evolution of said gas in said viscose solution.

4. A viscose solution for the manufacture of viscose sponges containing a finely divided metal carbide in a sufficient amount to form upon the regeneration thereof a porous sponge of regenerated cellulose, said metal carbide being capable of evolving a gas by chemical interaction with said viscose solution and being dispersed in a wetting agent to retard the evolution of said gas in said viscose solution.

5. A viscose solution for the manufacture of viscose sponges containing finely divided magnesium metal in a sufiicient amount to form upon the regeneration thereof a porous sponge of regenerated cellulose said metal being dispersed in a wetting agent to retard the evolution of gas in said viscose solution.

RUDOLPH S. BLEY.

M CERTIFICATE (1F CORRECTION. Patent No. 2,5L 1,5o9. February 15, 191 1;.

RUDOLPH s. BLEY.

It is hereby certified that error appears in the printed specification of the above nu mbered patent requiring correction as follows: Page 1, second coluum, line 15, strike out the words and comma "boron carbide,''; and that the said Letters Patent should be read with this correction therein that the same y c nform to the record of the case in the Patent Office.

Signed and sealed this 16th di ly of May, A. D. 19%.

Leslie Frazer (Seal) Acting Commissioner of Patents.