Water-based ink, ink jet recording method, ink cartridge, recording unit, ink jet recording apparatus, and image forming method

An image forming method by ink jet recording on a plain paper using a black ink and at least one water-based color ink to form an image having a black image formed with the black ink that is adjacent to a color image formed with the color ink, the method comprising the steps of:

• scanning for applying the black ink to the plain paper to form a black image;
• and
• scanning for applying the color ink to a region where the black image has already been formed,
• wherein the black ink is a water-based black ink,
• wherein the water-based ink comprises water, a plurality of water-soluble organic solvents, and a water-insoluble coloring material,
• wherein the water-soluble organic solvents comprise at least one good solvent to the water-insoluble coloring material and a plurality of poor solvents to the water-insoluble coloring material,
• wherein a total amount A (% by mass) of the good solvent or good solvents in the ink and a total amount B (% by mass) of the poor solvents in the ink are in a ratio A:B of from 10:5 to 7:9 both inclusive,
• wherein at least one of the plurality of poor solvents is a water-soluble organic solvent selected from the group consisting of diethylene glycol, polyethylene glycol, and 2-pyrrolidone,
• wherein the water-insoluble coloring material is selected from the group consisting of a resin-dispersed pigment, a microencapsulated pigment, a self-dispersing pigment in which hydrophilic groups are bonded to a surface of pigment particles via another group of atoms, and a polymer-binding self-dispersing pigment, and
• wherein the water-soluble organic solvent showing the largest Ka value in the plain paper as determined by the Bristow method among the water-soluble organic solvents is a poor solvent.

An ink jet recording method comprising:

• a step of ejecting a water-based ink,
• wherein the water-based ink comprises water, a plurality of water-soluble organic solvents, and a water-insoluble coloring material,
• wherein the water-soluble organic solvents comprise at least one good solvent to the water-insoluble coloring material and a plurality of poor solvents to the water-insoluble coloring material,
• wherein a total amount A (% by mass) of the good solvent or good solvents in the ink and a total amount B (% by mass) of the poor solvents in the ink are in a ratio A:B of from 10:5 to 7:9 both inclusive,
• wherein at least one of the plurality of poor solvents is a water-soluble organic solvent selected from the group consisting of diethylene glycol, polyethylene glycol, and 2-pyrrolidone,
• wherein the water-insoluble coloring material is selected from the group consisting of a resin-dispersed pigment, a microencapsulated pigment, a self-dispersing pigment in which hydrophilic groups are bonded to a surface of pigment particles via another group of atoms, and a polymer-binding self-dispersing pigment,
• wherein the water-soluble organic solvent showing the largest Ka value as determined by the Bristow method among the water-soluble organic solvents is a poor solvent, and
• wherein a plain paper recording medium is used when carrying out the method.