Photosensitive composition and lithographic printing plate precursor
A photosensitive composition comprising: a polymer obtained by polymerization of a monomer having a structure represented by the formula (I) as defined herein; a polymerizable compound having an unsaturated double bond; and a radical polymerization initiator selected from a hexaarylbiimidazole compound and a metallocene compound.
1 . A photosensitive composition comprising:
(i) a polymer obtained by polymerization of a monomer having a structure represented by the following formula (I):
wherein X 1 represents —OR 1 or —N(R 2 )(R 3 ), R a and R b each independently represents a hydrogen atom, a halogen atom, a cyano group or an organic group, and R 1 , R 2 and R 3 each independently represents an alkyl group which may have a substituent, or R a and R b or X 1 and R a or R b may be connected with each other to form a cyclic structure;
(ii) a polymerizable compound having an unsaturated double bond; and
(iii) a radical polymerization initiator selected from a hexaarylbiimidazole compound and a metallocene compound.
2 . The photosensitive composition as claimed in claim 1 , wherein the polymer (i) has a structure unit represented by the following formula (II) or (III):
wherein R 12 and R 13 each independently represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms, Y represents a functional group selected from —COOH, —COW 1 -L 1 -COOH and —SO 3 H in which W 1 represents an oxygen atom, a sulfur atom or —NH—, L 1 represents a divalent organic group, Z represents —CO—O—CH 2 —CH═CH 2 or —COW 2 -L 2 -O—CO—CR 14 ═CH 2 , W 2 represents an oxygen atom, a sulfur atom or —NH—, L 2 represents a divalent organic group, and R 14 represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms.
3 . The photosensitive composition as claimed in claim 1 , wherein the polymerizable compound (ii) has at least one ethylenically unsaturated double bond group.
4 . The photosensitive composition as claimed in claim 1 , wherein the polymerizable compound (ii) has at least two ethylenically unsaturated double bond groups.
5 . The photosensitive composition as claimed in claim 1 , wherein the radical polymerization initiator (iii) is a hexaarylbiimidazole compound.
6 . The photosensitive composition as claimed in claim 5 , wherein the hexaarylbiimidazole compound has chlorine atoms at o-position of aromatic rings of 2 and 2′ positions thereof.
7 . The photosensitive composition as claimed in claim 1 , further comprising a sensitizing dye.
8 . A lithographic printing plate precursor comprising a photosensitive layer containing the photosensitive composition as claimed in claim 1.