Oxime ester compound and photopolymerization initiator containing the same

An oxime ester compound represented by general formula (I):

• wherein R1, R2, and R3 each independently represent R11, OR11, COR11, SR11, CONR12R13, or CN;
• R11, R12, and R13 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms, in which the alkyl group, aryl group, arylalkyl group, and heterocyclic group may have their hydrogen atom substituted with OR21, COR21, SR21, NR22R23, CONR22R23, —NR22—OR23, —NCOR22—OCOR23, —C(═N—OR21)—R22, —C(═N—OCOR21)—R22, CN, a halogen atom, —CR21═CR22R23, —CO—CR21═CR22R23, a carboxyl group, or an epoxy group;
• R21, R22, and R23 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms;
• the methylene units of the alkylene moiety of the substituents represented by R11, R12, R13, R21, R22, and R23 may be interrupted by an unsaturated linkage, an ether linkage, a thioether linkage, an ester linkage, a thioester linkage, an amide linkage, or a urethane linkage at 1 to 5 sites thereof;
• the alkyl moiety of the substituents represented by R11, R12, R13, R21, R22, and R23 may be branched or cyclic;
• an alkyl terminal of the substituents represented by R11, R12, R13, R21, R22, and R23 may have an unsaturated bond;
• R12 and R13, and R22 and R23 may be connected to each other form a ring;
• R3 may be taken together with a neighboring benzene ring;
• R4 and R5 each independently represent R11, OR11, SR11, COR11, CONR12, R13, NR12COR11, OCOR11, COOR11, SCOR11, OCSR11, COSR11, CSOR11, CN, a halogen atom, or a hydroxyl group;
• and a and b each independently represent 0 to 3.