Patent ID: 7160667

Claim:
A positive image forming material comprising, on a substrate, a positive image forming layer which includes at least (A) a novolac type phenolic resin containing phenol as a structural unit, (B) a photo-thermal converting agent, and (C) an onium salt represented by the following formula (1-2-A): R A —SO 3 − M + Formula (1-2-A) wherein, in formula (1-2-A), − R A represents a substituent including at least one substituent that has an alkali dissociative proton and M + represents a sulfonium ion, wherein the positive image forming material does not include a crosslinking agent and wherein the photo-thermal converting agent is represented by the following formula (a): wherein in formula (a), R 1 and R 2 each independently represent an alkyl group having 1 to 12 carbon atoms, and the alkyl group may have a substituent selected from an alkoxy group, an aryl group, an amide group, an alkoxycarbonyl group, a hydroxyl group, a sulfo group or a carboxyl group; Y 1 and Y 2 each independently represent an oxygen atom, a sulfur atom, a selenium atom, a dialkylmethylene group or a —CH═CH—; Ar 1 and Ar 2 each independently represent an aromatic hydrocarbon group and may have a substituent selected from an alkyl group, an alkoxy group, a halogen atom, or an alkoxy carbonyl group; in Ar 1 , the carbon atom adjacent to Y 1 and a carbon atom adjacent to said carbon atom may belong to another ring that is condensed with Ar 1 ; in Ar 2 , the carbon atom adjacent to Y 2 and a carbon atom adjacent to said carbon atom may be members of another ring that is condensed with Ar 2 ; X represents a counter ion necessary for neutralizing an electric charge, which is not required when the cation moiety of the formula (a) has an anionic substituent; and Q represents a polymethine group selected from a pentamethine group, a heptamethine group or a nonamethine group comprising, in the methine chain thereof, three consecutive carbon atoms that are members of a cyclohexene ring or a cyclopentene ring.