Method of hardening gelatin

摘要

A method of hardening gelatin is described comprising treating gelatin with a compound of the formula (I) <IMAGE> (I) wherein R1 and R2 can each represent a monovalent group including a carbon atom or a nitrogen atom forming a bond together with the nitrogen atom N forming an acid ester in the formula (I); or R1 and R2 together can form a heterocyclic ring together with said nitrogen atom N, and n is 1 or 2; and when n is 1, X is <IMAGE> and Y is an alkyl group, an aryl group or an aralkyl group; and when n is 2, X is <IMAGE>