Patent ID: 7709547

Claim:
An ink composition comprising: a cationically polymerizable compound; a compound that generates an acid when irradiated with a radiation ray; and an onium salt compound that generates an organic acid compound having a basic nitrogen atom when irradiated with a radiation ray, the onium salt compound being represented by any one of the following Formulae (I), (II) and (III): wherein, in the Formulae (I), (II) and (III), R N represents a monovalent organic group including a basic nitrogen atom or a monovalent organic group including an ammonium group; R 1 to R 3 and R 5 to R 6 each independently represent an alkyl, cycloalkyl, aralkyl, or aryl group; R 4 represents an alkylene, cycloalkylene, or arylene group; X − represents CO—O − or SO 2 —O − ; and any two of R 1 to R 3 in Formula (I), any two of R 1 and R 3 in Formula (II), or R 5 and R 6 in Formula (III) may bond with each other to form a ring.