| abstract |
A polyurethane resin composition for casting isnprovided which for use as a molding material for opticalnlenses, resistance to discoloration and durability arenexcellent and the pot life is long enough take time forncasting process. It comprises a polyisocyanate, anpolyhydroxy compound and an aromatic polyamine. Thenaliphatic polyisocyanate is 4,4'-methylene-bis(cyclohexylnisocyanate) or isophorone diisocyanate, the polyhydroxyncompound is a polyether diol or polyester diol having annaverage molecular weight of 700-1200 or their mixture,nand the aromatic polyamine is 4,4'-methylene-bis(2-chloroaniline). |