Copolymer, a photosensitive resin composition and the resin film containing the same

The copolymer of the present invention comprises a repeating unit derived from hydroxyphenyl (meth) acrylate, a repeating unit derived from an isocyanate group-containing unsaturated compounds is blocked. Repeating units derived from hydroxy phenyl (meth) acrylate, 30 mol% to 90 mol%, the repeating unit derived from blocked isocyanate group-containing unsaturated compound is preferably contained 10 mol% 70 mol%. The photosensitive resin composition containing the copolymer of the present invention, transparency, excellent heat discoloration resistance and electrical properties, coating properties, developability, has good curing property and storage stability.