On-press development type lithographic printing plate precursor,method of preparing lithographic printing plate, and lithographic printing method

An on-press development type lithographic printing plate precursor, comprising, in the following order:

• a support;
• an image-recording layer;
• and
• an outermost layer,
• wherein the image-recording layer comprises an infrared absorber, an electron-accepting polymerization initiator, and a polymerizable compound,
• LUMO of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.45 eV or more,
• the outermost layer comprises a discoloring compound, and
• the infrared absorber comprises a compound represented by Formula 1,
• in Formula 1, R1 and R2 each independently represent a hydrogen atom or an alkyl group, R1 and R2 may be linked to each other to form a ring, R3 to R6 each independently represent a hydrogen atom or an alkyl group, R7 and R8 each independently represent an alkyl group or an aryl group, Y1 and Y2 each independently represent an oxygen atom, a sulfur atom, —NR0—, or a dialkylmethylene group, R0 represents a hydrogen atom, an alkyl group, or an aryl group, Ar1 and Ar2 each independently represent a group forming a benzene ring or a naphthalene ring which may have a group represented by Formula 2 that will be described later, at least one of Ar1 or Ar2 comprises a bromine atom, A1 represents —NR9R10, —X1-L1, or a group represented by Formula 2 that will be described later, R9 and R10 each independently represent an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group, X1 represents an oxygen atom or a sulfur atom, L1 represents a hydrocarbon group, a heteroaryl group, or a group that undergoes bond cleavage from X1 by heat or exposure to infrared, Za represents a counterion that neutralizes charge, and at least one of Ar1 or Ar2 has a group represented by Formula 2,
• —X Formula 2
• in Formula 2, X represents a halogen atom, —C(═O)—X2—R11, —C(═O)—NR12R13, —O—C(═O)—R14, —CN, —SO2NR15R16, or a perfluoroalkyl group, X2 represents a single bond or an oxygen atom, R11 and R14 each independently represent an alkyl group or an aryl group, and R12, R13, R15, and R16 each independently represent a hydrogen atom, an alkyl group, or an aryl group.