Aqueous ink for inkjet recording

1. An aqueous ink for inkjet recording comprising:

water;

pigment;

a water-soluble organic solvent incorporated at a content of not less than 30% by weight;

a surfactant formed of at least one selected from the group consisting of acetylene glycol-based surfactant and a fluorinated surfactant; and

3-methoxy-3-methyl-1-butanol;

wherein at least a part of the water-soluble organic solvent is glycerin.

2. The aqueous ink according to claim 1 , wherein the pigment has an average particle diameter ranging from 1 to 300 nm.

3. The aqueous ink according to claim 1 , wherein the pigment has an average particle diameter ranging from 10 to 200 nm.

4. The aqueous ink according to claim 1 , wherein the pigment is bonded, on the surface thereof, with at least one kind of functional group selected from the group consisting of carbonyl group, carboxylic group, hydroxyl group and sulfone group or salts thereof.

5. The aqueous ink according to claim 1 , wherein the pigment is contained at a concentration of solid matters of 3-20% by weight.

6. The aqueous ink according to claim 1 , wherein the water-soluble organic solvent is contained at a content of not more than 60% based on a total weight of the ink.

7. The aqueous ink according to claim 1 , wherein the water-soluble organic solvent is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl imidazolidinone, ε-caprolactam, monoethanol amine, diethanol amine, triethanol amine, monoethyl amine, diethyl amine, triethyl amine, dimethyl sulfoxide, sulfolane, thiodiethanol, propylene carbonate, ethylene carbonate and γ-butyrolactone.

8. The aqueous ink according to claim 1 , wherein at least 10% by weight of the water-soluble organic solvent is glycerin.

9. The aqueous ink according to claim 1 , wherein the surfactant is contained at a content ranging from 0.05% to 1.0% based on a total weight of the ink.

10. The aqueous ink according to claim 1 , wherein the acetylene glycol-based surfactant is selected from the group consisting of 2,4,7,9-tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octine-3,6-diol, 3,5-dimethyl-1-hexine-3-ol.

11. The aqueous ink according to claim 1 , wherein the fluorinated surfactant is selected from the group consisting of perfluoroalkyl ethylene oxide adducts, perfluoroalkyl amine oxide, perfluoroalkyl carboxylate and perfluoroalkyl sulfonate.

12. The aqueous ink according to claim 1 , wherein the surfactant is a fluorinated surfactant.

13. The aqueous ink according to claim 1 , wherein the ink has a viscosity of not higher than 50 mPa·s at 25°C.

14. The aqueous ink according to claim 1 , wherein the ink has a viscosity of 5-50 mPa·s at 25°C.

15. The aqueous ink according to claim 1 , further comprising salts.

16. The aqueous ink according to claim 15 , wherein the salts are selected from the group consisting of polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurylate and polyoxyethylene alkyl ether sulfate.

17. The aqueous ink according to claim 1 , further comprising a nonionic surfactant.

18. The aqueous ink according to claim 17 , wherein the nonionic surfactant is selected from the group consisting of polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine and polyoxyethylene alkyl amide.

19. The aqueous ink according to claim 1 , wherein the 3-methoxy-3-methyl-1-butanol is contained therein at a content ranging from 0.5% to 20% based on a total weight of the ink.