Actinic radiation-curable ink-jet ink and image formation method

Abstract

Disclosed herein are an active energy ray-curable ink-jet ink that is excellent in ejection stability and does not undergo a local thermal polymerization reaction, and an image forming method using the same. The active energy ray-curable ink-jet ink is an actinic radiation-curable ink-jet ink that undergoes temperature-dependent reversible sol-gel phase transition, comprising a photopolymerizable compound, a photoinitiator, and a gelling agent, wherein the photopolymerizable compound comprises one or more combinations of: a compound A that has n (n is an integer of 2 or more) (meth)acrylate ester units, is represented by the following formula, and has a molecular weight in a range of 280 to 1500; and a compound B that has n−1 (meth)acrylate ester units and a hydroxyl group, is represented by the following formula, and has a molecular weight in a range of 280 to 1500, (wherein n is an integer of 2 or more, R is an n-valent branched or unbranched linear or cyclic hydrocarbon group that optionally contains an oxygen atom or a nitrogen atom, and n and R in both the compounds A and B are the same integer and the same structure, respectively), in at least one of the combinations of the compound A and the compound B, an amount of the compound B contained is 5 to 15 mass % of a total mass of the compound A as a counterpart of the compound B, an amount of the gelling agent contained is 0.5 to 7.0 mass % of a total mass of the ink, and a gelling temperature of the ink is 50° C. or more.