Water-developable photosensitive composition for producing relief plates

A water-developable photosenstive composition for use in the preparation of relief printing plates, consisting essentially of:

• (A) about 30 to about 90% by weight of a copolymer comprising units of (i) an aliphatic conjugated diene monomer, (ii) an .alpha.,.beta.-ethylenically unsaturated carboxylic acid, and (iii) a polyfunctional vinyl monomer, the content of the aliphatic conjugated diene monomer (i), the .alpha.,.beta.-ethylenically unsaturated carboxylic acid (ii), and the polyfunctional vinyl monomer (iii) being respectively from about 5 to 95 mol %, from about 1 to 30 mol %, and from 0.1 to 10 mol % based on the combination of said monomeric components;
• (B) about 0.20 to 2.0 mol, based on 1 mol of the carboxyl groups in said copolymer (A), of a basic nitrogen atom-containing compound having a tertiary basic nitrogen atom;
• (C) about 5 to 70% by weight of an ethylenically unsaturated monomer;
• and
• (D) about 0.1 to 10% by weight of a photopolymerization initiator, the amounts of said copolymer (A), said ethylenically unsaturated monomer (C), and said photopolymerization initiator (D) being based on the total weight of said composition;
• said composition, upon application to a support and exposure to light, being developable in the unexposed areas solely with water to form a relief printing plate that is resistant to swelling with water-based inks.