Photopolymerization initiator composition and photopolymerizable composition

摘要

A photopolymerization initiator composition almost free from deactivation and capable of giving a photopolymerizable composition which is almost free from a decrease in the photopolymerization rate in a medium having a high viscosity and shows a high curing rate, containing (A) a sulfonium organoboron complex or oxosulfonium organoboron complex of the formula (1), <IMAGE> (B) a sensitizer having electron donating capability and electron acceptability in an excited state.