Patent ID: 8722315

Claim:
A method of suppressing warping in an optical disc to changes in radial tilt of below 0.82 degrees, comprising providing an optical disc consisting essentially of a light reflection layer and a light transmission layer formed on a substrate, wherein recording and reading are performed by a blue laser beam through the light transmission layer; the light transmission layer is formed from a cured film of an ultraviolet-curable composition comprising: an epoxy acrylate resin obtained by reacting a half ester compound (A), which is obtained from a lactone-adduct of a hydroxyalkyl (meth)acrylate (a1) and a dibasic acid anhydride (a2), and an epoxy resin (B), and a compound represented by Formula (3): where R 7 represents a hydrogen atom, an alkyl group of 1 to 20 carbon atoms that may be substituted with a halogen atom, or an alkenyl group of 1 to 20 carbon atoms that may be substituted with a halogen atom, wherein the epoxy acrylate resin is 20% to 70% by weight relative to the total weight of the ultraviolet-curable composition; and a film thickness of the light transmission layer is from 50 to 150 μm.