POLYVINYL ACETAL RESIN FOR HEAT-DEVELOPABLE PHOTOSENSITIVE MATERIAL, AND THE HEAT-DEVELOPABLE PHOTOSENSITIVE MATERIAL

PROBLEM TO BE SOLVED: To provide a binder resin for a heat-developable photosensitive material which will not cause fogging, faulty gradation or insufficient sensitivity with respect to image properties after coating, without deteriorating the storage stability of a coating solution and a heat-developable photosensitive material when used in the heat-developable photosensitive material, and to provide the heat-developable photosensitive material. SOLUTION: A polyvinyl acetal resin for a heat-developable photosensitive material used as the binder resin of a photosensitive layer of the heat-developable photosensitive material has a constitutional unit represented by Formula (1) (wherein R1represents a 6-18C aromatic ring or cyclic hydrocarbon), contains ≤25 mol% of residual acetyl groups and 17-35 mol% of residual hydroxyl groups, and has a polymerization degree of 200-3,000. COPYRIGHT: (C)2006,JPO&NCIPI