Patent ID: 7410746

Claim:
A photoradical polymerization initiator comprising a compound (a) having only one naphthalimide structure-containing group represented by the following formula (2) in one molecule: wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 respectively represent a hydrogen atom or a substituent and may be bonded to each other to form a cyclic structure; the chemical structure Q is a hydrocarbon group selected from a straight-chain and/or branched and/or cyclic saturated or unsaturated alkyl group, aryl group and allyl group; and the hydrocarbon group Q may contain an atom other than carbon or hydrogen provided that he hydrocarbon group is directly bonded to nitrogen (N) via a carbon atom, wherein any one or more of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are not azo groups, and wherein the hydrocarbon group Q contains no cationic groups.