Patent ID: 7985785

Claim:
An ink composition comprising: (i) a sensitizing dye represented by the following wherein X represents S; n represents 1; R 1 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R 2 represents a halogen atom; (ii) at least one polymerization initiator selected from the group consisting of an α-aminoketone represented by the following wherein Ar represents a phenyl group substituted with —SR 13 or —N(R 7E )(R 8E ); R 13 represents a hydrogen atom or an alkyl group; R 7E and R 8E each independently represents a hydrogen atom, an alkyl group having from 1 to 12 carbon atoms, an alkyl group having from 2 to 4 carbon atoms, which is substituted with an alkoxy group having from 1 to 4 carbon atoms, or an alkenyl group having from 3 to 5 carbon atoms; R 1D and R 2D each independently represents an alkyl group having from 1 to 8 carbon atoms; R 1D and R 2D may be bonded to each other to form an alkylene group having from 2 to 9 carbon atoms; R 3D and R 4D each independently represents a hydrogen atom, an alkyl group having from 1 to 12 carbon atoms, an alkyl group having from 2 to 4 carbon atoms, which is substituted with an alkoxy group having from 1 to 4 carbon atoms, or an alkenyl group having from 3 to 5 carbon atoms; and R 3D and R 4D may be bonded to each other to form an alkylene group having from 3 to 7 carbon atoms, and the formed alkylene group may be one containing —O— or —N(R 12 )— in the alkylene chain thereof, wherein R 12 represents an alkyl group having from 1 to 4 carbon atoms and an acyl phosphine oxide represented by the following or wherein R 5D and R 6D each independently represents an aliphatic group, an aromatic group, an aliphatic oxy group, an aromatic oxy group or a heterocyclic group; and R 7D represents an aliphatic group, an aromatic group or a heterocyclic group; wherein R 8D and R 10D each independently represents an alkyl group, an aryl group or a heterocyclic group; and R 9D represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group or a heterocyclic group; and (iii) an ethylenically unsaturated bond-containing polymerizable compound; wherein said ink composition is curable by exposure to active radiation rays having an output of from 50 to 800 mJ/cm 2 .