Abstract: The present invention relates to a thermosensitive lithographic printing original plate comprising a substrate, a hydrophilic layer containing a hydrophilic binder polymer, and a microcapsuled oleophilic material which forms an image area by heating; the hydrophilic binder polymer having a three-dimensional cross-link and a functional group which chemically combines with the oleophilic material in the microcapsule when the microcapsule is decomposed, and the microcapsuled oleophilic material having a functional group which chemically combines with the hydrophilic binder polymer when the microcapsule is decomposed.The thermosensitive lithographic printing original plate of the present invention is excellent in printing durability and storage property and provides prints having clear images because the plate does not collect scumming. Further, development is not required in the platemaking process so that there are no problems with waste treatment and the like.

Abstract: A photosensitive resin composition for use in forming a relief structure, which comprises, in specific proportions, a liquid photosensitive resin component comprising a urethane prepolymer and an addition-polymerizable ethylenically unsaturated monomer; a photopolymerization initiator; a thermal polymerization inhibitor; and a specific unsaturated amine compound. The photosensitive resin composition exhibits excellent performances such that it does not suffer from tunnel phenomenon which is frequently observed in relief formation with respect to conventional photosensitive resin compositions, so that a photoresin relief structure made therefrom not only is characterized with a tunnel-free structure and excellent mechanical properties, but also exhibits excellent performances.

Abstract: 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.