PURPOSE: To obtain the subject lightweight, low-discolored polymer with high refractive index by incorporating specific compound(s) in a composition containing a sulfur-contg. (meth)acrylate-based monomer followed by radical polymerization.
CONSTITUTION: A (meth)acrylate-based monomer containing in the molecule sulfur (pref. thiolmethacrylate group-contg. monomer) is incorporated with (B) 0.1-7wt.% (based on the whole composition) of at least one compound selected from radical chain transfer-natured compounds and radical-trapping compounds (pref. mercapto group-contg. compound) (esp. pref. 1-5wt.% of mercaptan-based compound(s) and 0.1-1wt.% of phenolic OH-contg. compound(s)), (C) as necessary, ≤50wt.% of another radical-polymerizable monomer (e.g. divinylbenzene), and (D) a photopolymerization initiator such as benzophenone-based compound or a thermal polymerization initiator such as peroxide-based compound. The resulting composition is then subjected to radical polymerization to give the objective lightweight, low-discolored polymer with high refractive index.
BABA SETSUO
OKA KOICHIRO
