Ultraviolet curable composition for optical disc and optical disc

An ultraviolet curable composition for an optical disc, the ultraviolet curable composition being used for a light transmitting layer of an optical disc in which at least a light reflecting layer and the light transmitting layer are stacked on a substrate, and information is reproduced by making a laser beam be incident on the optical disc from a side of the light transmitting layer, the ultraviolet curable composition comprising:

• a radical polymerizable compound and a polymerization initiator, the radical polymerizable compound including a (meth)acrylate compound (a) that does not intramolecularly have a cyclic moiety and has a functionality of three or more and a monofunctional (meth)acrylate compound (b) that forms a homopolymer having a glass transition temperature of 20° C. or less,
• wherein a cured film of the ultraviolet curable composition has a glass transition temperature of 50° C. or less,
• wherein a loss modulus (E″) at 60° C. in a dynamic viscoelastic spectrum of the cured film of the ultraviolet curable composition measured at a frequency of 3.5 Hz is 10 MPa or less,
• wherein a loss tangent (tan δ) at 60° C. in the dynamic viscoelastic spectrum of the cured film of the ultraviolet curable composition measured at a frequency of 3.5 Hz is 0.25 or less, and
• wherein an elastic modulus (25° C.) 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 1,500 MPa or less.