Ink, ink cartridge, and image recording method

1. An ink comprising:

(a) a pigment;

(b) resin particles;

(c) a surfactant;

(d) at least one water-soluble organic compound; and

(e) water,

wherein a total of the content of the at least one water-soluble organic compound is 35 mass % or less based on a total mass of the ink,

wherein the at least one water-soluble organic compound comprises at least a first water-soluble organic compound being liquid at 25° C. and having a surface tension at 25° C. of 40 mN/m or less, and the content of the first water-soluble organic compound is 5 mass % or less based on a total mass of the ink,

wherein the surfactant is a surfactant represented by the following general formula (1):

wherein R 1 to R 4 each independently represents an alkyl group having 1 to 3 carbon atoms, x and y each independently represent a numerical value of from 1 to 5, and m+n represents a numerical value of from 0 to 7,

wherein the content of the surfactant is 0.7 mass % or more based on a total mass of the ink,

wherein a mass ratio of the content (mass %) of the surfactant to a total of the content (mass %) of the pigment and the content (mass %) of the resin particles is from 0.03 to 0.25,

wherein the surface tension of the ink at 25° C. is from 25 mN/m to 35 mN/m, and

wherein the resin particles have an acid value of from 20 mg KOH/g to 150 mg KOH/g.

2. The ink according to claim 1 , wherein, in the general formula (1), m+n represents a numerical value of from 2 to 5.

3. The ink according to claim 1 , wherein the pigment is a self-dispersion pigment.

4. The ink according to claim 3 , wherein the self-dispersion pigment is a phosphonic acid-based self-dispersion pigment in which a phosphonic acid group is bonded directly or via another atomic group to a surface of particles of the pigment.

5. The ink according to claim 1 , wherein the pigment is a resin-dispersed pigment dispersed with a resin dispersant.

6. The ink according to claim 5 , wherein a mass ratio of the content (mass %) of the pigment to the content (mass %) of the resin dispersant is from 1.0 to 10.0.

7. An ink cartridge comprising:

an ink; and

an ink storage portion storing the ink,

wherein the ink is the ink according to claim 1 .

8. An image recording method comprising an ink-applying step of applying an ink to a recording medium,

wherein the ink is the ink according to claim 1 .

9. The image recording method according to claim 8 , further comprising a step of heating the recording medium provided with the ink, such that a surface temperature of the recording medium is 70° C. or higher.

10. The ink according to claim 1 , wherein the total of the content of the at least one water-soluble organic compound is 10 mass % or more to 30 mass % or less based on the total mass of the ink.

11. The ink according to claim 1 , wherein the total of the content of the at least one water-soluble organic compound is 10 mass % or more to 20 mass % or less based on the total mass of the ink.

12. The ink according to claim 1 , wherein the content of the first water-soluble organic compound is 0 mass % based on the total mass of the ink.

13. The ink according to claim 1 , wherein the content of the surfactant is 0.7 mass % or more to 3.0 mass % or less based on the total mass of the ink.

14. The ink according to claim 1 , wherein the mass ratio of the content (mass %) of the surfactant to the total of the content (mass %) of the pigment and the content (mass %) of the resin particles is 0.05 or more to 0.17 or less.

15. The image recording method according to claim 8 , wherein, in the ink-applying step, the ink is applied by a full-line type recording head.