Lithographic printing plate precursor

1 . A lithographic printing plate precursor comprising; a support; and a photosensitive layer containing (A) a sensitizing dye represented by the following formula (I), (B) a polymerization initiator, (C) a polymerizable compound, and (D) a binder polymer having a crosslinkable group,

wherein R 1 , R 2 and R 3 each independently represents a halogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, an —NR 4 R 5 group or an —OR 6 group; R 4 , R 5 and R 6 each independently represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent or an aralkyl group which may have a substituent; and k, m and n each independently represents 0 or an integer of 1 to 5.

2 . The lithographic printing plate precursor as claimed in claim 1 , wherein k, m and n in the formula (I) each independently represents 0 or 1.

3 . The lithographic printing plate precursor as claimed in claim 1 , wherein at least one of R 1 , R 2 and R 3 in the formula (I) represents the —NR 4 R 5 group.

4 . The lithographic printing plate precursor as claimed in claim 1 , wherein the binder polymer (D) is a (meth)acrylic copolymer having a crosslinkable group in a side chain or a polyurethane resin having a crosslinkable group in a side chain.

5 . The lithographic printing plate precursor as claimed in claim 1 , wherein the photosensitive layer further contains (E) a chain transfer agent.

6 . The lithographic printing plate precursor as claimed in claim 5 , wherein the chain transfer agent (E) is a thiol compound represented by the following formula (II):

wherein R represents an alkyl group which may have a substituent or an aryl group which may have a substituent; and A represents an atomic group necessary for forming a 5-membered or 6-membered hetero ring containing a carbon atom together with the N═C—N linkage, and A may have a substituent.

7 . The lithographic printing plate precursor as claimed in claim 1 , wherein the polymerization initiator (B) is a hexaarylbiimidazole compound or a metallocene compound.

8 . The lithographic printing plate precursor as claimed in claim 1 , which further comprises a protective layer so that the support the photosensitive layer and the protective layer are provided in this order.

9 . A plate-making method of a lithographic printing plate precursor, comprising: imagewise exposing the lithographic printing plate precursor as claimed in claim 1 with a laser beam having a wavelength of from 350 to 600 nm, and processing the exposed lithographic printing plate precursor with a developer.

10 . The plate-making method as claimed in claim 9 , wherein the developer contains a nonionic surfactant having a polyoxyalkylene ether group.