PROTECTIVE COAT FOR OPTICAL RECORDING MEDIUM AND OPTICAL RECORDING MEDIUM

摘要

A protective coat for an optical recording medium, characterized in that it comprises one sheet of transparent film comprising a thermoplastic resin and exhibits a phase difference of 15 nm or less and K value of 40 nm or less both at a wavelength of 550 nm, a glass transition temperature of 120z< - (n>x< + n>y<)/2] x d where n>x<, n>y< and n>z< represent refractive indexes in the direction of x, y and z axes, respectively, of the transparent film and d is a thickness of the transparent film; an optical recording medium characterized in that it comprises a substrate and, formed thereon, an information recording layer and the above protective film, and the incidence of a light is carried out from the protective film side.