Liquid electrophotographic ink composition

Patent metadata

Field	Value
Publication number	US-9983498-B2
Application number	US-201415329079-A
Country	US
Kind code	B2
Filing date	Jul 29, 2014
Priority date	Jul 29, 2014
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A method for coating pigment particles is provided, the method comprising heating a polymer resin in a carrier fluid to dissolve the polymer resin; suspending in the carrier fluid white pigment particles to be coated; and cooling the carrier fluid at a rate of 2° C./hr or less to effect precipitation of the polymer resin from the carrier fluid such that a coating of the resin is formed on the pigment particles, thereby producing the white liquid electrophotographic ink composition.

First claim

The invention claimed is:

1. A method of producing a white liquid electrophotographic ink composition, the method comprising:
heating a polymer resin in a carrier fluid to dissolve the polymer resin;
suspending in the carrier fluid white pigment particles to be coated; and
cooling the carrier fluid at a rate of 2° C./hr or less to effect precipitation of the polymer resin from the carrier fluid such that a coating of the resin is formed on the pigment particles, thereby producing the white liquid electrophotographic ink composition.

2. The method according to claim 1 , wherein the carrier fluid is or comprises an isoparaffinic carrier fluid.

3. The method according to claim 1 , wherein the carrier fluid is heated to at least 100° C. to dissolve the polymer resin.

4. The method according to claim 1 , wherein the white pigment particle is or comprises titanium dioxide.

5. The method according to claim 1 , wherein the polymer resin comprises a polymer having acidic side groups.

6. The method according to claim 1 , wherein the polymer resin comprises a copolymer of an alkylene monomer and a monomer selected from the group consisting of acrylic acid and methacrylic acid.

7. The method according to claim 6 , wherein the alkylene monomer is selected from the group consisting of ethylene and propylene.

8. The method according to claim 1 , further comprising grinding the polymer resin coated white pigment particles.

9. The method according to claim 1 , further comprising adding a charge director:
to the carrier liquid before precipitation of the polymer resin; or
to the carrier liquid during precipitation of the polymer resin; or
to the carrier liquid after precipitation of the polymer resin.

10. A liquid electrophotographic ink composition comprising coated pigment particles and having a particle conductivity of less than 100 pmho/cm producible in accordance with a method comprising:
heating a polymer resin in a carrier fluid to dissolve the polymer resin;
suspending in the carrier fluid white pigment particles to be coated; and
cooling the carrier fluid at a rate of 2° C./hr or less to effect precipitation of the polymer resin from the carrier fluid such that a coating of the resin is formed on the pigment particles, thereby producing the white liquid electrophotographic ink composition.

11. A white liquid electrophotographic ink composition, the composition comprising:
a carrier fluid; and
white pigment particles having a polymer resin coating thereon, wherein the polymer resin comprises a copolymer of an alkylene monomer and acrylic acid; and wherein the white liquid electrophotographic ink composition has a particle conductivity of less than 100 pmho/cm.

12. The white liquid electrophotographic ink composition according to claim 11 , wherein the white pigment particle is or comprises titanium dioxide.

13. The white liquid electrophotographic ink composition according to claim 11 , wherein the white pigment particle comprises surface modifying groups to increase hydrophobicity.

14. The white liquid electrophotographic ink composition according to claim 11 , wherein the polymer resin comprises blend of i) the copolymer of the alkylene monomer and acrylic acid, wherein the alkylene monomer is ethylene, and ii) a copolymer of ethylene and methacrylic acid.

15. The white liquid electrophotographic ink composition according to claim 11 , wherein the carrier fluid is or comprises an isoparaffinic carrier fluid.

16. The white liquid electrophotographic ink composition according to claim 11 , further comprising a charge director.

17. The white liquid electrophotographic ink composition according to claim 11 , wherein the alkylene monomer is selected from the group consisting of ethylene and propylene.

Assignees

• Hp Indigo Bv

Inventors

• Mann Adi
• Handel Eyal
• Teishev Albert
• Klein Marc
• Kaploun Vladislav

Classifications

• C09C1/3676

  Treatment with macro-molecular organic compounds · CPC title

• G03G9/125 Primary

  characterised by the liquid · CPC title

• G03G9/122

  characterised by the colouring agents · CPC title

• G03G9/131

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C09D11/037

  characterised by the pigment · CPC title