Ink-jet printing method
The present invention relates to [1] a pigment-containing water-based ink for ink-jet printing which is free of turbidity and excellent in capability of suppressing occurrence of image unevenness (MOTTLING) when printed on a low-water absorbing recording medium, said ink including at least one acetylene glycol (A) selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and the like, and a nonionic surfactant (B), a content of the component (A) in the water-based ink being not less than 1.0% by mass and not more than 3.0% by mass, and a mass ratio of the component (B) to the component (A) [(B)/(A)] being not less than 1 and not more than 3; and [2] an ink-jet printing method for printing images or characters on a low-water absorbing recording medium using said water-based ink for ink-jet printing.
1. An ink-jet printing method for printing images or characters on a recording medium using a water-based ink for ink-jet printing, wherein
the water-based ink comprises:
at least one acetylene glycol (A) selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and 2,5-dimethyl-3-hexyne-2,5-diol;
a nonionic surfactant (B);
a pigment; and
water, wherein
the nonionic surfactant (B) is a compound represented by the general formula (1):
RO-[(EO) m /(PO) n ]-H (1)
wherein R is a hydrocarbon group having not less than 12 and not more than 24 carbon, EO is ethyleneoxy group, PO is a propylene oxy group, m is a number of from 10 to 60, and n is a number 0;
a content of the component (A) in the water-based ink is not less than 1.0% by mass and not more than 3.0% by mass, and a mass ratio of the component (B) to the component (A) (B/A) is not less than 1 and not more than 3; and
the recording medium has a water absorption of not less than 0 g/m 2 and not more than 10 g/m 2 as measured in a pure water contact time of 100 ms.
2. The ink-jet printing method according to claim 1 , wherein a content of the nonionic surfactant (B) in the water-based ink is not less than 1.0% by mass and not more than 9.0% by mass.
3. The ink-jet printing method according to claim 1 , wherein the pigment contained in the water-based ink is in the form of a self-dispersible pigment, a dispersant-dispersed pigment or pigment-containing water-insoluble polymer particles.
4. The ink-jet printing method according to claim 1 , wherein the pigment contained in the water-based ink is in the form of a pigment-containing water-insoluble polymer particles.
5. The ink jet printing method according to claim 1 , wherein viscosity of the water-based ink for ink-jet printing as measured at 32° C. is not less than 2.0 mPa·s and not more than 12 mPa·s.
6. The ink-jet printing method according to claim 1 , wherein a surface tension of the water-based ink for ink-jet printing is not less than 25.0 mN/m and not more than 30.0 mN/m.
7. An image forming method comprising the steps of:
mounting a container filled with a pigment-containing water-based ink for ink-jet printing to an ink-jet printing apparatus equipped with an ink ejecting means; and
ejecting the ink onto a recording medium having a water absorption of not less than 0 g/m 2 and not more than 10 g/m 2 as measured in a pure water contact time of 100 ms to print images or characters thereon, wherein
the water-based ink comprises:
at least one acetylene glycol (A) selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and 2,5-dimethyl-3-hexyne-2,5-diol; and
a nonionic surfactant (B), wherein
the nonionic surfactant (B) is a compound represented by the general formula (1):
RO-[(EO) m /(PO) n ]-H (1)
wherein R is a hydrocarbon group having not less than 12 and not more than 24 carbon, EO is ethyleneoxy group, PO is a propylene oxy group, m is a number of from 10 to 60, and n is a number 0; and
a content of the component (A) in the water-based ink is not less than 1.0% by mass and not more than 3.0% by mass, and a ratio of the component (B) to the component (A) (B/A) is not less than 1 and not more than 3.
8. The image forming method according to claim 7 , wherein a content of the nonionic surfactant (B) in the water-based ink is not less than 1.0% by mass and not more than 9.0% by mass.
9. The image forming method according to claim 7 , wherein the pigment contained in the water-based ink is in the form of a self-dispersible pigment, a dispersant-dispersed pigment or pigment-containing water-insoluble polymer particles.
10. The image forming method according to claim 7 , wherein the pigment contained in the water-based ink is in the form of a pigment-containing water-insoluble polymer particles.
11. The image forming method according to claim 7 , wherein viscosity of the water-based ink for ink-jet printing as measured at 32° C. is not less than 2.0 mPa·s and not more than 12 mPa·s.
12. The image forming method according to claim 7 , wherein a surface tension of the water-based ink for ink-jet printing is not less than 25.0 mN/m and not more than 30.0 mN/m.