Patent GB-600039-A (GB)
Title: Photographic elements containing hydrophilic colloid layers
IPC: G03C1/76
Filed: 1945-08-24
Abstract: Photographic material includes an inter layer which contains a hydrophilic colourless acetal of polyvinyl alcohol with an aldehyde containing one or more carboxylic and/or sulphonic acid groups or which contains a hydrophilic salt of such an acetal, the acetal being free from colour-forming groups.  The acetals may be neutralized with an alkali metal hydroxide, ammonia, or an amine, and may be formed from partially or completely hydrolysed polyvinyl esters or hydrolysed interpolymers of vinyl esters with one, or less than one, equivalent of a terminally unsaturated interpolymerisable organic compound.  In particular, the acetals may be formed from (a) high molecular weight polyvinyl alcohol; (b) medium molecular weight polyvinyl alcohol substituted on 40 to 60 per cent of the hydroxyl groups with acetate, propionate, acetal, propional, or butyral groups; (c) 75 to 100 per cent hydrolysed interpolymers of vinyl acetate with 0.05 to 0.5 mol equivalents of terminally unsaturated mono-olefines (e.g. ethylene); or (d) completely hydrolysed interpolymers of vinyl acetate with a minor portion of polymerisable vinyl or vinylidene compounds (e.g. vinyl chloride, vinyl cyanide, or alkyl methacrylates such as methyl or ethyl methacrylate).  From 5 to 20 per cent of the hydroxyl groups may be acetalized.  The aldehyde acids may be aliphatic, aromatic, or mixed aliphaticaromatic. Acetals are prepared (a) by heating together completely hydrolysed ethylene/vinyl acetate interpolymer, benzaldehyde-o-sulphonic acid, glacial acetic acid, and phosphoric acid, and precipitating with acetone; (b) by heating together completely hydrolysed polyvinyl acetate, phthalaldehydic acid, glacial acetic acid, and phosphoric acid, and precipitating with methanol; (c) by heating together 76 to 79 per cent hydrolysed polyvinyl acetate, glyoxylic acid, dioxane, and phosphoric acid, and (d) by heating together acid hydrolysed vinyl chloride/vinyl acetate interpolymer, benzaldehyde-o-sulphonic acid, dioxane, and phosphonic acid, and precipitating with methanol. Acetals may also be formed from aliphatic sulphoaldehydes of the formula HSO3(CH2)nCHO, where n is 2 to 10 (e.g. b -sulphopropionaldehyde); aliphatic carboxyaldehydes of the formula HOOC(CH2)nCHO, where n is 2 to 10 (e.g. b -formylpropionic acid); benzaldehyde-p-sulphonic acid; terephthalaldehydic acid; p-(b -formylethyl)-benzoic acid; and o-carboxymethoxybenzaldehyde; and from 50 per cent or more hydrolysed polyvinyl acetate and propionate; 50 per cent or less substituted polyvinyl acetal, propional, and butyral; hydroysed ethylene/vinyl acetate interpolymers; and hydrolysed vinyl halide (e.g. chloride)/vinyl acetate interpolymers. Solvents specified are methanol, ethanol, propanol, n-butanol, methyl and ethyl acetate, cyclohexane, benzene, acetone, methyl ethyl ketone, diethyl ketone, methylene chloride, chloroform, carbon tetrachloride, and trichlorethylene.  Small amounts of high boiling solvents (e.g. dimethylformamide, ethylene glycol, diacetone alcohol, 2-ethoxyethanol, and cyclohexanone) and of water may be added. Gelatin, cellulose derivatives, polyamides, and vinyl and vinylidene polymers may be incorporated in the coating solutions.  Small amounts of the acetals may be added to colloid coating solutions (e.g. of gelatin, polyvinyl alcohol, partially hydrolysed polyvinyl acetate, hydrolysed polyvinyl chloride/acetate interpolymer, hydrolysed interpolymers of vinyl acetate with unsaturated compounds (e.g. maleic anhydride and acrylic acid esters), hydrophilic partially substituted polyvinyl esters and acetals, low substituted cellulose esters of saturated aliphatic monocarboxylic acids of 2 to 4 carbon atoms, low substituted cellulose esters (e.g. methyl and ethyl cellulose), casein, albumen, gum arabic, agar-agar, and polyglycuronic acid. The acetals may contain silver or antihalation dyes. Specifications 535,341 and 600,023 are referred to.