Asahi Kasei Kogyo Kabushiki Kaisha

Kazuhito Miyoshi

Tadashi Kawamoto

Gensho Takahashi

Kiichi Iida

Yoneharu Tanaka

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.

Urethane photosensitive resinous composition

A novel method of removing surface tack of a cured free radical polymerized resin composition which comprises impregnating the surface layer of the cured free radical polymerized resin composition with a specific organic carbonyl compound and irradiating the impregnated layer of the cured resin composition with specific actinic rays. The method of the present invention is applicable for effectively removing surface tack of cured photopolymerized or heat-polymerized resin compositions, especially photopolymer type printing plates manufactured therefrom.

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Fuji, Japan

Kazuhito Miyoshi