US2072809A - Cellulosic spinning solution - Google Patents

Description

mama M. 2, 19 1 UNITED STATES PATENT OFFICE North American Rayon Corporation, New York, N. Y., a corporation of Delaware No Drawing.

8 Claims.

The present invention relates to a process of producing artificial silk of cellulosic origin having bactericidal properties, especially when being contacted by vapors or liquid substances.

The primary obiect of this invention relates to the production of antiseptic, cellulosic filaments and yarns containing one or more colloidal metals in combination with one or more dissimilar, colloidal metal salts.

10 Another object of my invention has to do with a process of increasing the bactericidal powers of colloidal metals and colloid metal compounds by irradiating them with ultra-violet rays prior to their incorporation into cellulosic spinning sou lutions.

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

I am well aware that it has, heretofore, been proposed to use colloidal metals as disinfectants (vide Rideal, "Disinfection and Sterilization, 1921, pages 206-9), and to impregnate textile fibers with metallic salts and colloidal hydroxides (vide U. 8. Patents Nos. 22,362, 1,482,416,

25 1,536,254, and 71,717,483) to prevent fungous growth thereon.

However, I have found by experimentation that a colloidal metal or a colloidal metal compound does not have a sumcient sterilizing power after so being imbedded into cellulosic flbers. After a thorough investigation of the effect of colloidal metals as well as colloidal metal compounds upon non-pathogenic and pathogenic microorganisms, such as bacteria and molds, I have found that the 35 bactericidal effect of the aforementioned substances can be substantially increased and accelerated by distributing a combination of colloidal metals and colloidal metal compounds in a spinning solution or illament of cellulosic origin.

In order to increase and/or accelerate the bactericidal properties of colloidal metals and metal compounds, it is necessary to-select at least one metal in combination with a metal compound to 45 form a bactericidal agent, i. e., disinfectant. Thus, I may combine, for example, copper with euprous oxide or sulfide, cupric selenide with cuprous oxide, etc. I may also combine an electro-positive element chosen from the lighter metsis of the second and third periodic groups and Application October 20, 1934 Serial No. 749,271

an electro-negative electrode element chosen from the oxygen family in the sixth periodic group, for example, magnesium as the electropositive electrode element and a selenide of a. copper alloy as the electro-negative electrode element all of these elements being colloidally dispersed.

When microorganisms, such as bacteria, molds. etc., are distributed in a liquid phase and subsequently a solid phase, such as acolloidal metal 10 added thereto, they are killed after a while and the liquid phase becomes sterile. The time consumed to paralyze the protoplasma of microorganisms depends naturally upon the species of microorganisms treated, the chemical composition and temperature of the nutritive solution and the amounts and chemical properties of the colloidal metals and metal compounds used as disinfectants. The physico-chemical principles underlying this sterilization are unknown. although the theory has been advanced that the colloidal metal particles become adsorbed to the membranes of the microorganisms and in turn prevent proper assimilation of nutritive substances. Other investigators have claimed that invisible rays are emitted by the colloidal particles which paralyze protoplasma. I have been unable to definitely find the cause why cells of microorganisms are much more rapidly killed in the presence of a colloidal metal and a dissimilar colloidal metal compound. Whether or not this theory is correct, I have definitely found that microorganisms are much more rapidly killed by disinfectants comprising one or more disslmilar metals in combination with one or a pinrality of colloidal metal compounds, than by a single colloidal metal, two or more colloidal metals unable to set up a potential diflerence, a single colloidal metal salt or a plurality of colloidal 40 metal salts unable to set up a potential difference. Table I depicts the results obtained by using various colloidal substances, in accordance with the present invention, to sterilize aqueous stupensions of Bacillus coli. To obtain'comparable resuits, aqueous suspensions of Bacillus coli were prepared by inoculating it into sterile water. Subsequently equal amounts of this bacterial suspension were transferred by means of a platimnn loup into test tubes containing identical quantities so Table! Beau colt M I loci broth-gelatin at 37.5 C.

One loop of bacterial suspension inoculated into every test tube containing 10 cc. of gelatine. 0.1 g. of disinfectant in 1 cc. of distilled water and 0.01 g. gelatine as protective colloid.

Tim. of treatment in minutes xxx xxx

xxx

com dkinloctants equal amounts of each ingredbnt were used to make up 0.1 g. of disinfectant, for example 0.05 g. copper plus 0.15 g. wprous oxide, etc.

I have, furthermore, found that colloidal metals and metal salts, irradiated with ultra-violet rays, prior to being used as disinfectants, have a greater bactericidal power than non-irradiated ones. Although ultra-violet rays stimulate the aforementioned colloidal disinfectants to a higher degree than day light, it is to be noted that a prolonged irradiation fails to increase the bactericidal eil'ect of a disinfectant beyond a fixed limit. This limit varies for each metal, metal salt and compositions thereof and must be determined by experiment, in other words, each colloidal agent has a definite optimum time of irradiation. Over-exposure to ultra-violet rays does not deleteriously efiect the colloidal disinfectants, but it should be avoided for reasons of economy. I am unable to define the complex reactions which evidently take place in such irradiated dispersions, but I have definitely found that the agents, cited above, substantially increase their bactericidal power after being irradiated. This stimulation by means of irradiation is so pronounced that even the walls of glass flasks in which they are kept acquire bactericidal properties. When, for example, all colloidal metals and/or colloidal metal salts are removed from such a flask by rinsing and the same fllled with a suspension of virulent bacteria, they will be killed after standing for some time. This experiment can be repeated several times, the glass walls acting as disinfectants in the absence of colloidal particles, at least I have been unable to detect with the microscope any particle adsorbed to the glass walls of such flasks. Although I am unable to explain this phenomena, a marked increase of the bactericidal power of my agents is obtained by pro-irradiation. Table II depicts some results obtained by this method.

Table II Eflcct of irradiation All dispersions were irradiated with ultra-violet rays in open glass dishes rior to being used as disinfectants. After inoculation he tubes were kept in a dark incubator (see Table 1).

Similar results were obtained with spores of mucor and oidium species, although they are more resistant to destruction. After standing in the dark for 14 days the irradiated colloidal disinfectants were again compared with the nonirradiated ones. The pre-irradiated disinfectants had retained a higher sterilizing power than the non-irradiated ones. It is to be noted, however, that the stimulation, obtained by pro-irradiation, slowly abates on standing, and that it may be revived by a second irradiation, etc. I

The colloidal dispersions may be prepared by well known processes to form suitable disinfectants. The metals may be dispersed by electrical means and. held in aqueous suspension by adding thereto suitable protective colloids, such asgelatine, agar, gums, alginates, casein, soluble silicates, protalbic acid, etc, Colloidal metals may also be formed by chemical precipitation in aqueous solutions. Subsequently the byproducts may be removed by dialysis, the colloidal particles suspended in water and protective colloids added thereto as stabilising agents. Colloidal salts may be prepared by grinding, for example, oxides, hydroxides, sulfides, etc., in pebble or colloid mills to microscopic fineness. They may also be formed by chemical reaction and purified by dialysis.

Colloidal copper, for example, may be prepared in the following manner. A 20% aqueous solution of copper sulphate, containing about 10 to 20% saccharose is boiled for a few minutes and subsequently diluted with an equal amount of dis tilled water, this comprising solution No. 1. Solution No. 2 consists of a 14% aqueous solution of sodium or potassium hydroxide. Solution No. 3 is prepared by adjusting sulphuric acid that 1 solution. Solution No. 4 is obtained by dissolving approximately 5 g. of gelatlne in ccs. of distilled water. After having prepared solutionsl to 4, 10 cos. of solution No. 1 are mixed with 40 cos. of solution No. 4 and the mixture boiled on a water bath for a. few minutes. About 5 to 6 cos. of solution No. 2 are added to the hot mixture to precipitate colloidal cuprous hydroxide. This cuprous oxide may be purified by dialysis'and used in combination with colloidal metals according to my invention. To form colloidal copper from cuprous hydroxide, the solution is again boiled and subsequently about 3 cos. of solution No. 3 added. Red colloidal copper is spontane cc. thereof corresponds to 2 cos. of the hydroxide 60 vinyl alcohol.

ously precipitated'which is purified by dialysis. The colloidal copper dispersion tends to coagulate on prolonged standing, but it may be stabilized by a small addition of alcoholic potassium citrate solution, etc. Instead of using sulphuric acid to form colloidal copper, any acid may be employed in which colloidal copper is insoluble. Such colloidal metals may be also prepared by reducing water-soluble metal salts with aldehydes, p-aminophenol, etc., 1 g. of gold chloride, for example, is dissolved in a few cos. of distilled water and added to 500 cos. of a 10% aqueous solution of After addition of a mixture of 40 cos. of formaldehyde and 40 cos. of n-sodium carbonate solution, colloidal gold is precipitated which may be purified by dialysis. Instead of vinyl alcohol, other protective colloids may be used. Ammonia added to water-soluble chromium chloride, for example, in the presence of vinyl alcohol results in the formation of colloidal chromium hydroxide. In a. similar manner other colloidal metal hydroxides may be formed. Colloidal metals and metal compounds may be also prepared in the following manner. 10 g. of silver nitrate is mixed with 100 g. of cholesterine or phytosterine and the mixture heated to about 250 C. until a silver mirror appears on the surface of the composition. The composition containing colloidal silver may be dissolved in oils, such as olive oil, Turkey red oil, etc. When lead peroxide is treated in this manner in the presence of silver nitrate, a mixture of colloidal lead and silver is obtained which. may be dissolved in oils. By melting, for example, cobalt nitrate with uranyl nitrate in cholesterine, colloidal cobalt oxide and uranyl oxide is obtained, which may be taken up in chloroform or oils. When such metal organosols are incorporated into cellulosic spinning solutions, bactericidal filaments are obtained which are simultaneously delustered.

Example This invention is naturally not limited to the production of filaments or yarns, but also antiseptic ribbons, sheets and the like may be formed from the spinning solutions. In this manner it is possible to produce sterile sausage casings, wrapping materials, filter cloths, etc.

I wish to point out that the above example is merely illustrative, and I do not wish to be limto the use of all of these substances and noothers, nor the exact proportions and concentrations, set forth above, as the omission of some ingredients or a slight variation of proportions will not adversely aflect the final products, although it may somewhat vary the relative characteristics of such products, resulting from such variations. The expression colloidal metal salts in the specification as well as in the claims means: metal salts which are substantially insoluble in cellulosic spinning solutions, which are, thus, dispersable therein and which are able to set up a more or less large potential difierence with a dissimilar, colloidal metal in the presence of minute quantities of electrolytes. Modifications may be made in details of the meth'od and the product without departing from the spirit and scope of my invention, as defined by the appended claims.

I claim:

l. A spinning solution for the manufacture of products having bactericidal properties comprising a cellulosic spinning solution of the group consisting of viscose, cuprammonium cellulose, cellulose esters and cellulose ethers, a colloidal metal and a dissimilar colloidal metal salt dispersed therein, said metal salt being able to set up a potential difference in the presence of a colloidal metal and an electrolyte, and said metal and metal salt being chemically inert to said spinning solution.

2. A spinning solution for the manufacture of products having bactericidal properties comprising a cellulosic spinning solution of the group consisting of viscose, cuprammonium cellulose, cellulose esters and cellulose ethers, a colloidal metal and a dissimilar metal salt, said metal and metal salt being pre-irradiated with ultra-violet rays and able to set up a potential difference in the presence of an electrolyte, and said metal and metal salt being chemically inert to said spinning solution.

3. Aspinning solution for the manufacture of products having bactericidal properties comprising a viscose spinning solution, a colloidal metal and a dissimilar colloidal metal salt, said metal salt being able to set up a potential difierence in the presence of a colloidal metal and an electrolyte, and said metal and metal salt being chemically inert to said spinning solution.

' 4. A spinning solution for the manufacture of products having bactericidal properties comprising a viscose spinning solution, a colloidal metal and a dissimilar colloidal metal salt, said metal salt being pro-irradiated with ultra-violet rays and able to set up apotential-difference in the presence of a colloidal metal and an electrolyte, and said metal and metal salt being chemically inert to said spinning solution.

5. A bactericidal cellulosic product of the group consisting of viscose, cuprammonium cellulose, cellulose esters and cellulose ethers containing a colloidal metal and a dissimilar colloidal metal salt uniformly dispersed therein.

6. A bactericidal cellulosic product of the group consisting of viscose, cuprammonium cellulose, cellulose esters and cellulose ethers containing a colloidal metal and a dissimilar colloidal metal salt uniformly dispersed therein, said metal and metal salt being pr-irradiated with ultra-violet rays.

7. A bactericidal viscose product containing a colloidal metal and a dissimilar colloidal metal salt uniformly dispersed therein.

8. A bactericidal viscose product containing a colloidal metal and a dissimilar colloidal metal salt uniformly dispersed therein, said metal and metal salt being pre-irradiated with ultra-violet rays.

RUDOLPH S. BLEY.