Patent ID: 8703264

Claim:
An optical disc in which at least a light reflecting layer and a light transmitting layer that includes a cured film of an ultraviolet curable composition are stacked on a substrate, and information is reproduced by making a blue laser beam be incident on the optical disc from a side of the light transmitting layer, wherein the elastic modulus at 25° C. as measured by indenting a Vickers indenter having a vertex angle of 136° under a load of 100 mN into a surface of the cured film of the ultraviolet curable composition is 1500 MPa or less; the loss modulus (E″) at 60° C. in a dynamic viscoelastic spectrum of the cured film measured at a frequency of 3.5 Hz is 10 MPa or less; the loss tangent (tan δ) at 60° C. in the dynamic viscoelastic spectrum of the cured film measured at a frequency of 3.5 Hz is 0.25 or less; and the cured film has a glass transition temperature of 50° C. or less, and wherein the ultraviolet curable composition contains, as a (meth)acrylate oligomer, an epoxy (meth)acrylate represented by the formula (1) wherein in the formula (1), R 1 s each independently represent a hydrogen atom or a methyl group; A 1 is a group represented by the formula (2) wherein in the formula (2), E 1 s each independently represent a divalent group represented by SO 2 —, —CH(CH 3 )—, or —C(CH 3 ) 2 —, and n 1 represents an integer of 0 to 8, and B 1 is one or more groups selected from the group consisting of formulae (3) to (5) wherein in the formulae (3) to (5), J 1 to J 3 represent a divalent aromatic hydrocarbon group or a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms; L 1 represents a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms or a divalent group represented by —(RO) q —R— where R represents an alkylene group having 2 to 8 carbon atoms and q represents an integer of 1 to 10; L 2 represents an alkyl diol residue or a polyether diol residue, each of which has a number-average molecular weight of 250 to 10,000; L 3 and L 4 each independently represent a divalent aliphatic hydrocarbon group having 2 to 10 carbon atoms; and m 1 , m 2 , and m 3 each independently represent an integer of 1 to 20, and wherein the ultraviolet curable composition contains at least one of ethylene-oxide-modified bisphenol A di(meth)acrylate or propylene-oxide-modified bisphenol A di(meth)acrylate.