| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk excellent in signal reproduction with little deformation of a light transmission layer against a load over a long period of time, and to provide an ultraviolet curable composition to be used for the light transmission layer. <P>SOLUTION: The optical disk has a light transmission layer in which an elastic modulus (25°C) obtained by indenting it with a load of 100 mN using a Vickers indentor with an angle of 136° between edges is 2000 MPa or more, and a plastic deformation ratio when it is held with a load of 100 mN for 60 seconds is 25% or less. The light transmission layer that does not deform easily can be achieved by the use of cured film with high indention elastic modulus and low deformation ratio when a predetermined load is applied for a predetermined time period, thereby achieving an optical disk which is excellent in signal reproduction and reliable over a long period of time, and of which light transmission layer does not deform greatly even against a load over a long period of time. <P>COPYRIGHT: (C)2010,JPO&INPIT |
