| 摘要 |
PROBLEM TO BE SOLVED: To provide a radiation-curable resin composition for an optical member having a moderate viscosity before curing and capable of forming a cured object, after curing, having a high refractive index, excellent in adhesion to various plastic substrates, having such a moderate hardness as to infrequently distort a surface relief structure such as a fresnel lens, and less liable to yellow. SOLUTION: The composition comprises (A) 5-70 mass% of urethane (meth)acrylate which is a reaction product of (a) a hydroxyl group-containing (meth)acrylate, (b) a polyisocyanate having an aromatic ring structure, (c) a polyol and (d) a 1-4C alcohol having no polymerizable unsaturated group, wherein (meth)acryloyl groups are present at 40-85 mol% of molecular terminals as an average in the reaction product, (B) 1-30 mass% of a (meth)acrylate compound represented by the formula: CH<SB>2</SB>=C(R)COO-C<SB>n</SB>H<SB>2n+1</SB>(where R is H or methyl and n is an integer of 4-12), and (C) 10-80 mass% of an ethylenically unsaturated group-containing compound other than the components (A) and (B). COPYRIGHT: (C)2007,JPO&INPIT
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