Ink, ink cartridge, and image recording method
An ink including a first pigment, a second pigment, and water. The first pigment satisfies condition 1, the second pigment satisfies condition 2, and the content (% by mass) of the first pigment relative to the content (% by mass) of the second pigment based on a total mass of the ink is 1.7 times or more to 8.0 times or less in terms of mass ratio. Condition 1: When, to a pigment dispersion liquid containing the first pigment, calcium chloride is added so as to give a predetermined concentration, the particle diameter increase rate of the solid content is 2.0 nm/second or more. Condition 2: When, to a pigment dispersion liquid containing the second pigment, hydrochloric acid is added so as to give a predetermined concentration, the particle diameter increase rate of the solid content is 0.5 nm/second or less.
1. An ink comprising:
(a) a first pigment;
(b) a second pigment; and
(c) water,
wherein the first pigment satisfies condition 1:
condition 1: when, to a first pigment dispersion liquid comprising the first pigment and water and having a content of the first pigment of 0.01% by mass, calcium chloride is added so as to give a concentration of 1.0 mM, a particle diameter increase rate of a solid content is 2.0 nm/second or more,
wherein the second pigment satisfies condition 2:
condition 2: when, to a second pigment dispersion liquid comprising the second pigment and water and having a content of the second pigment of 0.01% by mass, hydrochloric acid is added so as to give a concentration of 0.5 mM, a particle diameter increase rate of a solid content is 0.5 nm/second or less, and
wherein a content (% by mass) of the first pigment relative to a content (% by mass) of the second pigment based on a total mass of the ink is 1.7 times or more to 8.0 times or less in terms of mass ratio.
2. The ink according to claim 1 , wherein the first pigment is a phosphonic acid type self-dispersible pigment in which a phosphonic acid group is bonded to a particle surface of the pigment directly or through an additional atomic group.
3. The ink according to claim 1 , wherein the second pigment is a sulfonic acid type self-dispersible pigment in which a sulfonic acid group is bonded to a particle surface of the pigment directly or through an additional atomic group.
4. The ink according to claim 1 , wherein the second pigment is a resin-dispersed pigment dispersed by a resin having (i) a weight-average molecular weight of 3,000 or more to 15,000 or less and (ii) an acid value of 100 mg KOH/g or more.
5. The ink according to claim 1 , further comprising a surfactant having an HLB value of 11 or less, as determined by Griffin's method.
6. An ink cartridge comprising:
an ink; and
an ink storage portion storing the ink,
wherein the ink is the ink according to claim 1 .
7. An image recording method comprising:
an ink application step of applying an ink to a recording medium,
wherein the ink is the ink according to claim 1 .
8. The image recording method according to claim 7 , wherein the ink, in an amount of 5.0 mg/inch 2 or less per color, is applied to the recording medium in a single pass manner.
9. The ink according to claim 1 , wherein the content (% by mass) of the first pigment relative to the content (% by mass) of the second pigment based on a total mass of the ink is 2.0 times or more to 5.0 times or less in terms of mass ratio.
10. The ink according to claim 1 , wherein the content (% by mass) of the first pigment in the ink is 0.1% by mass or more to 10.0% by mass or less.
11. The ink according to claim 1 , wherein the content (% by mass) of the second pigment in the ink is 0.1% by mass or more to 10.0% by mass or less.
12. The ink according to claim 4 , wherein the resin has the acid value of 100 mg KOH/g or more to 200 mg KOH/g or less.