Urethane photosensitive resinous composition

Abstract

A urethane photosensitive resinous composition composition comprising (a) at least one urethane prepolymer having in the middle of the molecule thereof at least two polyol compound monomer units linked through a diisocyanate compound monomer unit, and having only in the terminals of the molecule thereof at least 1.6 carboxyl groups on the average per molecule and acrylic residues with a vinyl group, each one of said acrylic residues being substantially present in each terminal of the molecule of said at least one urethane prepolymer, (b) at least one ethylenically unsaturated compound, and (c) at least one photopolymerization initiator. If desired, the urethane photosensitive resinous composition may further comprise at least one heat polymerization inhibitor. The photosensitive resinous composition of the present invention, in the process of producing printing plates, is good in developability with aqueous developers and capable of becoming sufficient in mechanical strength upon post exposure to even a small amount of light even in the presence of air, and can provide letterpress printing plates that are substantially free of surface tack and have high resistances to water or moisture and to abrasion and wear and, hence, long printing durability.

Dependencies are inferred from the claim text.