Ink composition, method for producing the same, and image-forming method

1. An ink composition comprising:

water;

particles that each include a polymer having at least one of a urethane bond or a urea bond, and each have a polymerizable group; and

a combination of a polymerization inhibitor A1 that is at least one selected from the group consisting of quinone compounds, nitroso compounds, and N-oxyl compounds, and a polymerization inhibitor A2 that is at least one selected from the group consisting of phenol compounds, or

a combination of a polymerization inhibitor B1 that is at least one selected from the group consisting of phenol compounds having a solubility of 1.0 g/100 mL or more in water at 25° C., and a polymerization inhibitor B2 that is at least one selected from the group consisting of phenol compounds having a solubility of less than 1.0 g/100 mL in water at 25° C.

2. The ink composition according to claim 1 ,

wherein the polymerization inhibitor A1 is at least one selected from the group consisting of compounds (A1-1) below, compounds (A1-2) below, salts of the compounds (A1-2) below, and compounds (A1-3) below,

wherein the polymerization inhibitor A2 is at least one selected from the group consisting of compounds (A2-1) below,

wherein the polymerization inhibitor B1 is at least one selected from the group consisting of compounds (B1-1) below, and

wherein the polymerization inhibitor B2 is at least one selected from the group consisting of compounds (B2-1) below,

wherein, in the compounds (A1-1), the compounds (A1-2), the compounds (A1-3), and the compounds (A2-1), R a1 to R a17 each independently represent a hydrogen atom, a chlorine atom, a hydroxy group, an alkyl group that has 1 to 12 carbon atoms and may have a cyclic structure, an alkoxy group that has 1 to 12 carbon atoms and may have a cyclic structure, or an aryl group having 6 to 12 carbon atoms,

wherein, in the compounds (A1-1), R a1 and R a2 may be linked together with each other to form a ring, and R a3 and R a4 may be linked together with each other to form a ring,

wherein, in the compounds (A1-2), R a5 and R a6 may be linked together with each other to form a ring,

wherein, in the compounds (A1-3), R a7 , R a8 , or R a9 may be linked together with R a10 , R a11 , or R a12 each other to form a ring,

wherein, in the compounds (A2-1), R a13 and R a14 may be linked together with each other to form a ring, R a14 and R a15 may be linked together with each other to form a ring, R a15 and R a16 may be linked together with each other to form a ring, and R a16 and R a17 may be linked together with each other to form a ring,

wherein, in the compounds (B1-1) and the compounds (B2-1), R b1 to R b4 and R b6 to R b8 each independently represent a hydrogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms,

wherein, in the compounds (B1-1), R b5 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and

wherein, in the compounds (B1-1), R b1 and R b2 may be linked together with each other to form a ring, R b3 and R b4 may be linked together with each other to form a ring, R b4 and R b5 may be linked together with each other to form a ring, and R b2 and R b5 may be linked together with each other to form a ring.

3. The ink composition according to claim 1 ,

wherein, in a case of comprising the combination of the polymerization inhibitor A1 and the polymerization inhibitor A2, a content ratio of the polymerization inhibitor A2 with respect to the polymerization inhibitor A1 is from 10 to 100 in terms of mass, or

wherein, in a case of comprising the combination of the polymerization inhibitor B1 and the polymerization inhibitor B2, a content ratio of the polymerization inhibitor B2 with respect to the polymerization inhibitor B1 is from 10 to 100 in terms of mass.

4. The ink composition according to claim 1 , comprising the combination of the polymerization inhibitor A1 and the polymerization inhibitor A2.

5. The ink composition according to claim 4 ,

wherein the polymerization inhibitor A1 has a solubility of 1.0 g/100 mL or more in water at 25° C., and/or

wherein the polymerization inhibitor A2 has a solubility of less than 1.0 g/100 mL in water at 25° C.

6. The ink composition according to claim 4 ,

wherein the polymerization inhibitor A1 is at least one selected from the group consisting of p-benzoquinone and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, and

wherein the polymerization inhibitor A2 is at least one selected from the group consisting of hydroquinone, p-methoxyphenol, and 3,5-di-tert-butyl-4-hydroxytoluene.

7. A method for producing the ink composition according to claim 1 , the method comprising:

mixing and emulsifying an oil-phase component and an aqueous-phase component including water, to form the particles,

wherein the oil-phase component is (i) an oil-phase component including an organic solvent, the polymer, the polymerization inhibitor A1, the polymerization inhibitor A2, and a polymerizable compound, (ii) an oil-phase component including an organic solvent, a tri- or higher functional isocyanate compound, the polymerization inhibitor A1, the polymerization inhibitor A2, and a polymerizable compound, (iii) an oil-phase component including an organic solvent, the polymer, the polymerization inhibitor B1, the polymerization inhibitor B2, and a polymerizable compound, or (iv) an oil-phase component including an organic solvent, a tri- or higher functional isocyanate compound, the polymerization inhibitor B1, the polymerization inhibitor B2, and a polymerizable compound.

8. An image-forming method comprising:

applying the ink composition according to claim 1 onto a substrate; and

curing the ink composition applied onto the substrate.