| abstract |
A composition comprising (a) 30 to 95% by weight of a compound having, in one molecule, one or more structures represented by the following formula (1): <CHEM> wherein R<1> is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, R<2>, R<3> and R<4> are each hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, Y is O, S, Se or Te, m is an integer of 1 to 5 and n is an integer of 0 to 5; (b) 1 to 40% by weight of a compound having at least one group selected from the group consisting of isocyanate group and isothiocyanate group in one molecule; and (c) 1 to 50% by weight of a compound having at least one mercapto group in one molecule. A resin produced by curing the composition by polymerization has an excellent impact resistance and optical properties, and is suitable as an optical material. |