US3034928A - Cellulosic material resistant to mustard gas penetration - Google Patents

Description

This invention relates to the treatment of fabrics and clothing for protection against the action of mustard gas and similar vesicants.

It is known that N-chloroamides, in particular the compounds referred to herein as tertiary N-chloroureas, are of value for protecting fabrics against penetration by vesicants of the type of mustard gas (beta,beta'-dichlorodiethylsulfide). However, a serious disadvantage of the N-chloroamides is their tenderizing eifect on fabrics, particularly of the cellulosic type, with the result that the fabric eventually becomes weak and unsuitable for use in clothing. Another disadvantage is that the N-chloroamides, particularly the N-chloroureas, are somewhat unstable and undergo decomposition with loss of chlorine with the result that, after varying periods of time on the fabric, they lose their efficiency. These problems are particularly serious under conditions of high temperature and high humidity such as generally prevail in tropical and equatorial regions. 1

An object of this invention is the provision of a process for giving fabrics, particularly fabrics permeable to air such as cellulosic materials, protection against penetration of vesicant vapors while at the same time preventing or retarding deterioration of the fabric. A further object is the manufacture of new and useful products comprising cellulosic material which has been treated with an antivesicant agent and a stabilizer against fabric deterioration, and which is permeable to air after said treatment. Other objects will appear hereinafter.

These objects are accomplished, in accordance with the invention, by treating a fabric with an N-chlorocarbonamide and a salt of a polymeric carboxylic acid.

The invention is illustrated by the following examples, in which parts are by weight.

Example I Arnzen cloth is dipped in a 5% aqueous solution of the sodium salt of a 1:1 styrene/maleic anhydride interpolymer, wrung out, then dipped in a 5% aqueous solution of zinc chloride to precipitate the Zinc salt of the polymer into the fabric. ter rinsing and drying at 70 C., the cloth is impregnated with a solution of 8.5% of N,N-di(2,4,6-trichlorophenyl)-N,N' di chlorourea and 6.5% of chloroparafiin in tetrachloroethane at 70 C., the chloroparaiiin serving as a binder for the chlorourea. The impregnated fabric resists the passage of mustard gas vapor and is found to have lost none of its tensile strength after 48 hours at 70 C. and 100% relative humidity, whereas a control fabric impregnated similarly except for the omission of the pretreatment loses all tensile strength under the same test conditions.

The preparation of interpolymers of the kind mentioned in the foregoing example is described in United States Patents 1,976,679 and 2,047,398.

Example II Thirty (30) parts of N,N'-(2,4,6-trichlorophenyl)- N,N'-dichlorourea is dry blended with 3 parts of a 75/25 sodium polymethacrylate/polymethylmethacrylate interpolymer and 0.6 part of technical sodium dodecyl sulfate. Thirty (30) parts of the above mixture is stirred with 120 parts of water until a uniform paste is obtained. all of which is impregnated into one square yard of olivehtates Patent 3,3432% Patented May E5, 1962 drab muslin. There is obtained a mustard gas-resistant fabric of good appearance which, upon being subjected to a temperature of 115 F. at relative humidity for 56 days, retains 61% of its original chlorine and 56% of its original tensile strength. A control treatment without the sodium polymethacrylate/polymethyl methacrylate interpolyrner gives a fabric which loses practically all tensile strength under the same conditions.

Example III The above example is repeated except that 10 parts of zinc oxide is added to the treating composition. The impregnated fabric upon being subjected to the same testing conditions, shows the same tensile strength retention, but the percent chlorine retained is 76%.

Example IV A /2 x 1 yard swatch of herringbone twill is soaked in a solution of 5.8 parts of sodium cellulose glycolate of medium viscosity in 290 parts of water, wrung to a weight pick-up and dried at 76 C. for 15 minutes. The fabric is then dipped at 60-65 in 500 parts of a solution prepared by dissolving 85 parts of N,N-(2,4,6- trichlorophenyl)-N,N-dichlorourea and 64 parts of chloroparaffinin 850 parts of tetrachloroethane, wrung on a rubber roll wringer to wet weight and dried 15 minutes at 76 C. Upon subjecting the treated fabric to a temperature of 70 C. and 100% relativehumidity for 48 hours, it is found to have retained 46% of its initial chlorine content and 35% of its initial tensile strength. Under the same conditions, a control fabric similarly impregnated with the exception that the pretreatment was omitted retains only 7% of its original chlorine content and 1% of its original tensile strength.

In the above examples, the percent chlorine retained refers to the residual amount of active, or titratable chlorine as measured by the amount of iodine liberated from potassium iodide. A known area of fabric is extracted with a tetrachloroethane-acetic acid mixture (3:2 by volume), excess potassium iodide solution is added, and the iodine liberated is titrated with standard sodium thiosulfate solution. The percent tensile retained is the ratio of the tensile strength of the fabric after aging un der simulated tropical conditions to the tensile strength of the original fabric before impregnation, measured by the standard A.S.T.M. Grab tensile test.

The stabilizers suitable for the purpose of this invention are salts of polymeric polycarboxylic acids, the term polymeric having here its accepted connotation of high molecular weight, i.e. macromolecular, materials (see, for example, Gilmans Organic Chemistry, Second Edition, vol I, pages 10, 702, and 739). The polymeric car boxylic acids contain recurring structural units each containing at least one carboxylic acid group. Salts of the polymeric carboxylic acids with any metal are suitable, but the preferred salts are the alkali and alkaline earth metal salts, especially the former. Further examples of suitable agents are potassium polyacrylate, the sodium salt of polyvinyl alcohol glycolic acid ether, the sodium salts of vinyl acetate/maleic anhydride interpolymers, etc.

The salt may be applied to the fabric together with the N-chloroamide, e.g. as an aqueous solution in which the N-chloroamide is suspended or emulsified. However, the best results are achieved when the polymeric acid salt is used in a pretreatment operation.

The polymeric acid salt is most conveniently applied to the fabric in the form of an aqueous solution, hence the alkali salts, which are Water-soluble, are preferred. If desired, however, the fabric may be first treated with a solution of an alkali salt of a polymeric carboxylic acid or of the free acid, then with a water-soluble inorganic acid salt of another metal so as to precipitate the polymeric acid salt of the other metal on the fabric.

The invention has been illustrated With particular reference to N,N-(2,4,6-trichlorophenyl)-N,N-dichlorourea as the anti'vesicant agent. However, any N-chlorocarbonamide is suitable, including N-dichlorotrichloroacetamide, N-dichlorobenzamide etc. A preferred group is that of the tertiary N-chloroureas, i.e., compounds having the urea nucleus NCON in which the nitrogens are joined only to chlorine and carbon free from hydrogen. Examples of this group are N,N-di-(2,6-dimethylphenyl)-N,N'-dichlorourea; 1,3,4-,6-tetrachloro-3a,- 6a, dimethylglycoluril; -methyl-5-isobutyl1,3-dichlorohydantoin; N,N'-dichloro-5,5-dimethyl hydantoin, etc.

The chloroamide may be applied to the fabric as a solution in a volatile organic solvent non-reactive therewith. Suitable solvents include the chlorinated hydrocarbons such as tetrachloroethane, tetrachloroethylene, ethylene dichloride, chloroform, chlorobenzene, or the ethers such as dioxane and glycol dimethyl ether. It may also be applied as an aqueous dispersion, using a suitable dispersing agent such as polyvinyl alcohol, partially hydrolyzed polyvinyl acetates, polyethylene oxides, sultonated alkylbenzenes, sulfonated naphthalene-formaldehyde condensation products, hydrolyzed reaction products of mineral oils with chlorine and sulfur dioxide, or sulfated long chain alcohols.

A binder for the chloroamide is often desirable, though not essential. For this purpose can be used any substantially non-volatile, usually water-insoluble material nonreactive toward the chloroamide. The binder is preferably a highly viscous liquid or semi-solid at room temperature. Suitable binders are chlorinated paraifin wax (40-45% chlorine), methyl cellulose, polyisobutylene, mineral oil etc.

The fabric-treating compositions may comprise, in addition to the polymeric carboxylic acid salt, other agents capable of retarding fabric deterioration and chloroamide decomposition. Among these, zinc oxide and calcium carbonate are particularly useful. The fabric-treating compositions may also contain other materials such as pigments, dyes, water-repellents, etc.

While the polymeric carboxylic acid salts are particularly useful for the treatment of cellulosic textile fibers and fabrics to prevent or retard their loss of strength and to minimize the loss of active chlorine from the N-chloroamide in contact with the fabric, they may also be applied with beneficial results to any other cellulosic fabric or web, such as paper, or to other cellulosic materials such as regenerated cellulose fibers or films, cotton, wooden surfaces and the like. From such treated materials, after subsequent treatment with an N-chloroamide may be made such articles as antiseptic bandages, wall paper, and coverings for any surface where slow, controlled liberation of chlorine is desired.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. Cellulosic material which is resistant to penetration by mustard gas and which contains an N-chlorocarbonamide and an alkali metal salt of a polymeric carboxylic acid selected from the group consisting of styrene/rnaleic anhydride interpolymer, polymethacrylic acid/polymethylmethacrylate interpolymer, cellulose glycolic acid, polyac'rylic acid, polyvinyl alcohol glycolic acid ether, and vinyl acetate/maleic anhydride interpolymer.

2. The cellulosic material set forth in claim 1 in which said salt is the sodium salt of a 1:1 styrene/maleic anhydride interpolymer.

3. The cellulosic material set forth in claim 1 in which said salt is sodium polymethacrylate/polymethylmethacrylate interpolymer.

4. The cellulosic material set forth in claim 1 in which said salt is sodium cellulose glycolate.

5. The cellulosic material set forth in claim 1 in which said N-chlorocarbonamide is N,N-di(2,4,6-trichlorophenyl -N,N-di-chlorourea.

6. Clothing which is resistant to penetration by mustard gas and which contains an N-chlorocarbonamide and an alkali metal salt of a polymeric carboxylic acid selected from the group consisting of styrene/maleic anhydride interpolymer, polymethacrylic acid/polymetbylmethacrylate interpolymer, cellulose glycolic acid, polyacrylic acid, polyvinyl alcohol glycolic acid ether, and vinyl acetate/- maleic anhydride interpolymer.

7. A process for obtaining cellulosic material resistant to penetration by mustard gas, said process comprising treating the cellulosic material with an N-chlorocarbonamide and an alkali metal salt of a polymeric carboxylic acid selected from the group consisting of styrene/maleic anhydride interpolymer, polymethacrylic acid/polymethylmethacrylate interpolymer, cellulose glycolic acid, polyacrylic acid, polyvinyl alcohol glycolic acid ether, and vinyl acetate/maleic anhydride interpolymer.

8. A cellulosic vesicant-resistant, permeable fabric which contains a tertiary N-chlorourea and a metal salt of an interpolymer of styrene and maleic anhydride.

References Cited in the file of this patent UNITED STATES PATENTS 2,173,781 Gibello Sept. 19, 1939 FOREIGN PATENTS 486,162 Great Britain May 31, 1938 OTHER REFERENCES Technical Abstracts, vol. III of 1944, page 737,

Claims (1)

1. CELLULOSIC MATERIAL WHICH IS RESISTANT TO PENETRATION BY MUSTARD GAS AND WHICH CONTAINS AN N-CHLOROCARBONAMIDE AND AN ALKALI METAL SALT OF A POLYMERIC CARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF STYRENE/MALEIC ANHYDRIDE INTERPOLYMER, POLYMETHACRYLIC ACID/POLYMETHYLETHACRYLATE INTERPOLYMER, CELLULOSE GLYCOLIC ACID, POLYACRYLIC ACID, POLYVINYL ALCOHOL GLYCOLIC ACID ETHER, AND VINYL ACETATE/MALEIC ANHYDRIDE INTERPOLYMER.