| 摘要 |
The viscosity of gelatin solutions is increased by incorporating therein (a) a copolymer derived from a monomer of the formula <FORM:0632174/IV (a)/1> wherein X is an acyloxy or carbalkoxy group, and maleic anhydride, maleic acid or a maleate or (b) a terpolymer derived from a monomer of the formula <FORM:0632174/IV (a)/2> wherein Y is hydrogen or methyl when X is a carbalkoxy group and Y is hydrogen when X is an acyloxy group, acrylic acid or an a -alkyl acrylic acid and maleic anhydride. The copolymer or terpolymer is after treated with water or an alcohol, e.g. methyl, ethyl, butyl, dodecyl, benzyl or cyclohexyl alcohol, at elevated temperature when maleic anhydride is used as a co-monomer. Alternatively the alkali metal salts of these resins may be used. Resins specified are copolymers of vinyl acetate or methyl acrylate and maleic anhydride, the sodium salts of copolymers of vinyl acetate and maleic acid or maleic acid monoethyl ester; terpolymers of vinyl acetate, methyl acrylate or methacrylate, acrylic acid or methacrylic acid and maleic anhydride. In examples, (6) a solution of vinyl acetate and maleic anhydride in acetone or dioxane containing benzoyl peroxide is heated under reflux and the resin precipitated by pouring into benzene or toluene. The resin is then boiled with water or dissolved in acetone or dioxane and refluxed with ethyl alcohol; (7) a terpolymer is similarly prepared from vinyl acetate, acrylic acid and maleic anhydride and boiled with water or refluxed with butyl alcohol. The resin may be incorporated with the gelatin solution or silver halide gelatin emulsion at any stage during their preparation. The modified gelatin solutions may be used as over-coatings or backing layers on photographic films, e.g. as filter or anti-halation layers containing dyes. |
