GB416885A - Improvements in the manufacture and production of artificial compositions - Google Patents

Abstract

Artificial compositions are manufactured by treating with strong acids the saponification products of the mixed polymerization products obtainable by interpolymerizing acrylic acid esters and such vinyl esters as yield saponifiable polymerization products. When the saponification products are in the form of ammonium salts they may alternatively be subjected to a simple heat treatment, e.g. at 100--150 DEG C. in the absence of solvents. Suitable vinyl esters are the acetate, chloracetate, propionate, butyrate and stearate. Suitable acrylic acid esters are the alkyl esters, e.g. the methyl, ethyl and butyl esters, the cycloalkyl esters, e.g. the cyclohexyl ester, and the aralkyl esters, e.g. the benzyl ester. The esters are preferably used in equimolecular proportions, but either may be in excess. The saponification may be carried out in organic solvents, e.g. ethyl alcohol or, advantageously, in aqueous dispersion, and is effected by treating the polymerization products with aqueous acids and alkalies consecutively or with alkalies alone, at temperatures between room temperature and boiling point. Suitable strong acids for the subsequent treatment are sulphuric, hydrochloric, nitric, phosphoric, perchloric and trichloracetic acids. The products are suitable for the preparation of films, threads, coatings and dressings and may be worked up in a similar manner to celluloid, e.g. by hot pressing. In photographic films they may be employed as an intermediate layer between the nitrocellulose film and the layer of gelatine for increasing the electrical conductivity and preventing discharges. They may be worked up together with other substances of high molecular weight, e.g. with tragacanth, British gum, polyvinyl alcohol or starch to yield waterproof dressings or sizes, or with cellulose derivatives such as ammoniacal cupric oxide cellulose solution or cellulose xanthate to yield films or threads. In the latter case the alkaline solution of the saponification product may be added to an alkaline cellulose xanthate solution before its precipitation with acid. In examples: (1) an aqueous dispersion obtained by polymerization of an aqueous emulsion of vinyl acetate and acrylic acid methyl ester in the presence of emulsifying agents, e.g. a -hydroxyoctodecanesulphonic acid, and hydrogen peroxide, is saponified with caustic soda solution and then treated with dilute sulphuric acid ; the product may be pressed at 100--150 DEG C.; the aqueous alkaline solution of the saponification product may be mixed with a cellulose xanthate solution and the mixture coagulated in acid baths to produce films or threads; (2) the dispersion employed in (1) is saponified with aqueous ammonia and a highly viscous solution of the saponification product is inspissated and heated at 140 DEG C.ALSO:As sizes may be employed mixtures of tragacanth, British gum, polyvinyl alcohol or starch with the products obtained by the action of strong acids on the saponification products of the mixed polymerization products obtainable by interpolymerizing acrylic acid esters and such vinyl esters as yield saponifiable polymerization products, or by simple heat treatment when the saponification products are in the form of ammonium salts.