GB547632A - Improvements in or relating to photographic materials - Google Patents

Abstract

547,632. Photographic emulsions. KODAK, Ltd. March 3, 1941, No. 2879. Convention date, March 2, 1940. [Class 98 (ii)] A spreading-agent for incorporation in a sensitive emulsion or in any other predominantly aqueous solution of gelatine or other hydrophilic colloid to be applied to a photographic support comprises a mono-ester of sorbitol with an aliphatic acid containing from 8 to 18 carbon atoms or with an alicyclic acid. From 0.001 to 0.002 per cent of the ester by weight may be employed, and the ester may be dispersed in the aqueous colloid solution with the aid of a water-soluble dispersing agent such as sodium lauryl #-sulphobutyrate, sodium lauryl sulphonate, sodium # oleyl-amidoethylsulphonate, or sodium -laurylamidoethysulphate, of which 0.02-0.04 per cent by weight may be used. The ester may be sorbitol monolaurate, monomyristate, monooleate, monoricinoleate, mononaphthenate, monoabietate, or monohydroabietate, or the mono-ester of sorbitol with a mixture of the acids of coconut oil. The sensitive emulsion or other solution containing the ester may be applied to the support and set by chilling, and before drying, a predominantly aqueous solution of gelatine or other hydrophilic colloid may be applied over the layer produced. If more than one predominantly aqueous solution of gelatine or other hydrophilic colloid is applied to the support, any or all of the layers may contain the ester. The incorporation of the ester may also improve the ageing qualities of the emulsion, increase its speed, and reduce storage fog. The emulsions are also more readily wetted by the developing solutions. Other hydrophilic colloids referred to are water-soluble cellulose derivatives such as well-hydrolysed cellulose acetate, cellulose esters of lactic, glycollic, and other hydroxy-monocarboxylic acids and salts of cellulose esters of dicarboiylic acids such as phthalic acid; polyvinyl alcohol such as hydrolysed polyvinyl acetate; and water-soluble polyvinyl acetals. Specifications 531,579, 542,703, and 542,704 are referred to.