Actinic radiation-curable inkjet ink and image forming method

1. An actinic radiation-curable inkjet ink, comprising a photocurable compound, a polymerization initiator, a fluorescent brightener, an antioxidant, and a gelling agent,

wherein the fluorescent brightener is a compound represented by the following general formula (1):

wherein R 1 to R 8 each independently represent a hydrogen atom or an alkyl group, adjacent substituents of R 1 to R 8 optionally forming a ring, and A represents a linking group represented by any one of the following formulas (2) to (5):

wherein each * represents a bonding position of A of each formula;

the antioxidant is a phenol-based antioxidant; and

the photocurable compound contains a (meth)acrylate having two or more (meth)acryloyl groups in an amount of 80 mass % or more with respect to a total mass of the photocurable compound.

2. The actinic radiation-curable inkjet ink according to claim 1 , wherein a content of the fluorescent brightener is 0.01 mass % or more and 0.5 mass % or less with respect to a total mass of the actinic radiation-curable inkjet ink.

3. The actinic radiation-curable inkjet ink according to claim 1 , wherein a content of the antioxidant is 0.1 mass % or more and 1.0 mass % or less with respect to a total mass of the actinic radiation-curable inkjet ink.

4. The actinic radiation-curable inkjet ink according to claim 1 , wherein the antioxidant is a polyfunctional phenol-based antioxidant.

5. The actinic radiation-curable inkjet ink according to claim 4 , wherein the antioxidant is a compound represented by the following general formula (6):

wherein R 9 and R 10 each independently represent an alkyl group having 1 or more and 4 or less carbon atoms, n represents an integer of 2 to 4, and L represents an alkyl group having 1 or more and 10 or less carbon atoms.

6. The actinic radiation-curable inkjet ink according to claim 1 ,

wherein the gelling agent contains a compound represented by the following general formula (G1) or a compound represented by the following general formula (G2):

R 11 —CO—R 12   General Formula (G1):

R 13 —COO—R 14   General formula (G2):

wherein R 11 and R 12 each independently represent a straight chain hydrocarbon group having 9 or more and 25 or less carbon atoms.

7. The actinic radiation-curable inkjet ink according to claim 1 , further comprising a colorant.

8. An image forming method, comprising:

discharging a droplet of the actinic radiation-curable inkjet ink according to claim 1 from a nozzle of an inkjet head and causing the droplet to land on a substrate; and

curing the actinic radiation-curable inkjet ink by irradiating, with actinic radiation, the droplet of the actinic radiation-curable inkjet ink landed on the substrate.