As a vinyl monomer which can copolymerize with said acrylates, a vinyl ether monomer such as methylvinyl ether, ethylvinyl ether, n-propylvinyl ether, n-butylvinyl ether, isobutylvinyl ether and the like, styrene and styrene derivative(??-methlystyrene and the like), a vinyl monomer having a cyano group such as acrylonitrile methacrylonitrile and the like, a vinyl monomer having a isocyanate group