| 摘要 |
An optical recording medium protecting film which is a protecting film comprising a single transparent film made of a thermoplastic resin, having a retardation of no greater than 15 nm at a wavelength of 550 nm and a K value of no greater than 40 nm at 550 nm, having a glass transition temperature of 120 DEG C or higher and a water absorption of no greater than 1 wt%. <DF NUM="(1)"><FENCE TYPE=BAR>R(550)</FENCE>≤15 nm </DF> <DF NUM="(2)"><FENCE TYPE=BAR>K(550)</FENCE>≤40 nm </DF> (the K value being calculated by K = Änz - (nx + ny)/2Ü x d äwhere nx, ny and nz are the three-dimensional refractive indexes of the transparent film in the x-axis, y-axis and z-axis directions, respectively, and d is the thickness of the transparent filmü). Also, an optical recording medium having a data recording layer and the above-mentioned protecting film on a substrate, wherein light is incident from the protecting film side. <IMAGE> |
