Process for producing pigment dispersion

Claim 2

An ink composition produced by a process comprising the steps of: dispersing a pigment that is suitable as a colorant for the ink composition in a solvent to prepare a stock pigment dispersion; subjecting the stock pigment dispersion to crossflow membrane filtration to recover a liquid, which is passed through a filtration membrane, or a liquid, which is not passed through the filtration membrane, as a pigment dispersion, and mixing the pigment dispersion with water and, optionally other components to form the ink composition.

Claim 3

The composition according to claim 1 , wherein the membrane filtration is microfiltration or ultrafiltration.

Claim 4

The composition according to claim 1 , wherein the membrane used in the membrane filtration has an average pore diameter of 1 nm to 1 μm.

Claim 5

The composition according to claim 1 , wherein the pigment is dispersed with the aid of a polymeric dispersant or a surfactant.

Claim 6

A process for producing a dispersion of a pigment having a regulated average particle diameter, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: dispersing the pigment in a solvent to prepare a stock pigment dispersion; subjecting the stock pigment dispersion to first-stage crossflow membrane filtration to recover a liquid, which is passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is not passed through a second filtration membrane, as a pigment dispersion, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being larger than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 7

A process for producing a dispersion of a pigment having a regulated average particle diameter, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: dispersing the pigment in a solvent to prepare a stock pigment dispersion; subjecting the stock pigment dispersion to first-stage crossflow membrane filtration to recover a liquid, which is passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is not passed through a second filtration membrane, as a pigment dispersion, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being larger than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 8

The process according to claim 5 , wherein each of the first and second-stage membrane filtrations is microfiltration or ultrafiltration.

Claim 9

The process according to claim 5 , wherein the average pore diameter of the membrane used in the first-stage crossflow membrane filtration is 0.05 to 1 μm, and the average pore diameter of the membrane used in the second-stage crossflow membrane filtration is 0.001 to 0.1μm.

Claim 10

The process according to claim 5 , wherein the pigment is dispersed with the aid of a polymeric dispersant or a surfactant.

Claim 11

The process according to claim 5 , wherein the average particle diameter of the pigment has been regulated so as to fall within the range of 10 to 300 nm.

Claim 12

An ink composition comprising the pigment dispersion produced by the process according to claim 5 .

Claim 13

A process for producing a dispersion of a pigment having a regulated average particle diameter, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: dispersing the pigment in a solvent to prepare a stock pigment dispersion; subjecting the stock pigment dispersion to first-stage crossflow membrane filtration to recover a liquid, which is not passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is passed through a second filtration membrane, as a pigment dispersion, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being smaller than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 14

A process for producing a dispersion of a pigment having a regulated average particle diameter, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: dispersing the pigment in a solvent to prepare a stock pigment dispersion; subjecting the stock pigment dispersion to first-stage crossflow membrane filtration to recover a liquid, which is not passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is passed through a second filtration membrane, as a pigment dispersion, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being smaller than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 15

The process according to claim 11 , wherein the average pore diameter of the membrane used in the first-stage crossflow membrane filtration is 0.001 to 0.1 μm, and the average pore diameter of the membrane used in the second-stage crossflow membrane filtration is 0.05 to 1 μm.

Claim 16

An ink composition comprising the pigment dispersion produced by the process according to claim 11 .

Claim 17

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; and subjecting the stock ink to crossflow membrane filtration to recover a liquid, which is passed through a filtration membrane, or a liquid, which is not passed through the filtration membrane, as an ink composition.

Claim 18

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; and subjecting the stock ink to crossflow membrane filtration to recover a liquid, which is passed through a filtration membrane, or a liquid, which is not passed through the filtration membrane, as an ink composition.

Claim 19

The process according to claim 14 , wherein the membrane filtration is microfiltration or ultrafiltration.

Claim 20

The process according to claim 14 , wherein the membrane used in the membrane filtration has an average pore diameter of 1 nm to 1 μm.

Claim 21

The process according to claim 14 , wherein the dispersant is a polymeric dispersant or a surfactant.

Claim 22

An ink composition produced by the process according to claim 7 .

Claim 23

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; subjecting the stock ink to first-stage crossflow membrane filtration to recover a liquid which is passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is not passed through a second filtration membrane, as an ink composition, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being larger than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 24

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; subjecting the stock ink to first-stage crossflow membrane filtration to recover a liquid which is passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is not passed through a second filtration membrane, as an ink composition, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being larger than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 25

The process according to claim 19 , wherein the average pore diameter of the membrane used in the first-stage crossflow membrane filtration is 0.05 to 1 μm, and the average pore diameter of the membrane used in the second-stage crossflow membrane filtration is 0.001 to 0.1 μm.

Claim 26

The process according to claim 19 , wherein the average particle diameter of the pigment has been regulated so as to fall within the range of 10 to 300 nm.

Claim 27

The process according to claim 19 , wherein the dispersant is a polymeric dispersant or a surfactant.

Claim 28

An ink composition produced by the process according to claim 19 .

Claim 29

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; subjecting the stock ink to first-stage crossflow membrane filtration to recover a liquid which is not passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is passed through a second filtration membrane, as an ink composition, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being smaller than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 30

A process for producing an ink composition comprising at least a pigment, a dispersant, and a water-soluble organic solvent, said pigment being suitable as a colorant in an ink composition, said process comprising the steps of: preparing a stock ink comprising at least a pigment, a dispersant, and a water-soluble organic solvent; subjecting the stock ink to first-stage crossflow membrane filtration to recover a liquid which is not passed through a first filtration membrane; and subjecting said liquid to second-stage crossflow membrane filtration to recover a liquid, which is passed through a second filtration membrane, as an ink composition, the average pore diameter of the first membrane used in the first-stage crossflow membrane filtration being smaller than the average pore diameter of the second membrane used in the second-stage crossflow membrane filtration.

Claim 31

The process according to claim 19 , wherein each of the first-stage and second-stage membrane filtrations is microfiltration or ultrafiltration.

Claim 32

The process according to claim 24 , wherein the average pore diameter of the membrane used in the first-stage crossflow membrane filtration is 0.001 to 0.1 μm, and the average pore diameter of the membrane used in the second-stage crossflow membrane filtration is 0.05 to 1 μm.

Claim 33

An ink composition produced by the process according to claim 15 .

Claim 34

A method for ink jet printing comprising (a) providing the ink composition of claim 1 ; (b) ejecting droplets of the ink composition onto a recording medium to produce an image thereon.

Claim 35

A method for ink jet printing comprising (a) providing the ink composition of claim 13 ; (b) ejecting droplets of the ink composition onto a recording medium to produce an image thereon.

Claim 36

A method for ink jet printing comprising (a) providing the ink composition of claim 18 ; (b) ejecting droplets of the ink composition onto a recording medium to produce an image thereon.

Claim 37

A method for ink jet printing comprising (a) providing the ink composition of claim 23 ; (b) ejecting droplets of the ink composition onto a recording medium to produce an image thereon.