| 摘要 |
A polyurethane resin composition for casting is provided which for use as a molding material for optical lenses, resistance to discoloration and durability are excellent and the pot life is long enough take time for casting process. It comprises a polyisocyanate, a polyhydroxy compound and an aromatic polyamine. The aliphatic polyisocyanate is 4,4'-methylene-bis(cyclohexyl isocyanate) or isophorone diisocyanate, the polyhydroxy compound is a polyether diol or polyester diol having an average molecular weight of 700-1200 or their mixture, and the aromatic polyamine is 4,4'-methylene-bis(2-chloroaniline).
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