Ink composition, inkjet recording method, printed material, process for producing lithographic printing plate, and lithographic printing plate

1 . An ink composition comprising:

a cationically polymerizable compound (a);

a compound (b) that generates an acid when exposed to radiation; and

a compound (c) that generates a compound having a basic nitrogen atom when exposed to radiation.

2 . The ink composition according to claim 1 , wherein the compound (c) that generates a compound having a basic nitrogen atom when exposed to radiation is at least one selected from the group consisting of compounds represented by Formulae (I) to (IX) below;

(in Formulae (I) to (IX), R 1 , R 2 , R 16 , R 17 , R 18 , R 19 , and R 20 independently denote a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, R 3 , R 8 , R 21 , and R 22 independently denote a hydrogen atom, an alkyl group, or an aryl group, R 4 , R 5 , and R 6 independently denote a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, an —NO 2 group, or an —OR 7 group, R 7 denotes an alkyl group, R 9 , R 10 , R 11 , R 23 , R 24 , and R 25 independently denote a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, or an —OR 7 group, R 12 and R 13 independently denote an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, an acyl group, or a —CN group, R 14 denotes an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, or an —N(R 1 )(R 2 ) group, R 15 denotes an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, Ar 1 and Ar 2 denote aryl groups, Z denotes an atomic group that, together with an imide group in Formula (III), forms a monocyclic or polycyclic aliphatic ring, aromatic ring, or hetero ring, Y denotes an NH group, a sulfur atom, or an oxygen atom, X − denotes a monovalent or polyvalent anion and, furthermore, R 1 and R 2 in Formulae (I) to (IV), two of R 4 to R 6 in Formulae (I) and (II), two of R 9 to R 11 in Formula (IV), R 12 and R 13 in Formula (V), R 16 and R 17 in Formula (VI), two of R 18 to R 20 in Formulae (VII) to (IX), Ar 1 and R 21 in Formula (VII), and two of R 23 to R 25 in Formula (VII) may be bonded together to form an aliphatic ring, an aromatic ring, or a hetero ring).

3 . The ink composition according to claim 1 , wherein the efficiency of the compound (b) in generating an acid when exposed to radiation is higher than the efficiency of the compound (c) in generating a compound having a basic nitrogen atom when exposed to radiation.

4 . The ink composition according to claim 1 , wherein it further comprises a colorant (d).

5 . The ink composition according to claim 4 , wherein the colorant (d) is a pigment or an oil-soluble dye.

6 . The ink composition according to claim 1 , wherein it is for inkjet use.

7 . An inkjet recording method comprising:

a step (a) of discharging an ink composition onto a recording medium; and

a step (b) of irradiating the discharged ink composition with radiation so as to cure the ink composition,

the ink composition being the ink composition according to claim 1 .

8 . A printed material recorded by the inkjet recording method according to claim 7 .

9 . A process for producing a lithographic printing plate, the process comprising:

a step (a) of discharging the ink composition according to claim 1 onto a hydrophilic support; and

a step (b) of irradiating the discharged ink composition with radiation so as to cure the ink composition, thus forming a hydrophobic image on the hydrophilic support by curing the ink composition.

10 . A lithographic printing plate produce by the lithographic printing plate production process according to claim 9.