Magnetic actuated-milled pigment dispersions and process for making thereof

• US 10,066,115 B2
• Filed: 11/14/2016
• Issued: 09/04/2018
• Est. Priority Date: 07/10/2014
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Zhou, Ke, Lee, Frank Ping Hay, Latchman, Harry, Wang, Yulin, Gardner, Sandra J.
• Primary Examiner(s): ABU ALI, SHUANGYI
• Application Number:
  US15/351,116
• Publication Number:
  US 20170066942A1
• Time in Patent Office: 659 Days
• CPC Class Codes: B02C 17/005 the charge being turned over by magnetic forces
• CPC Class Codes: C09D 17/001 in aqueous medium C09D17/003, C09D17/004 take precedence
• CPC Class Codes: C09D 17/003 containing an organic pigment process features in the making of dye stuff preparations C09B67/00

Abstract

The disclosure provides pigment dispersions having an average particle size of from about 10 nm to about 500 nm prepared by employing a magnetic actuated milling process and system. In embodiments, the pigment dispersions have an average particle size of less than 100 nm.

Claims

1. A method for producing a milled pigment dispersed in aqueous media, the method comprising:

mixing a pigment with water for a period of time sufficient to produce an aqueous pigment dispersion;

adding magnetic particles and non-magnetic abrasive particles to the pigment dispersion, thereby producing a pigment dispersion containing magnetic particles and non-magnetic abrasive particles, wherein the magnetic particles have a diameter of 5 nm to 1000 nm, and further wherein the non-magnetic abrasive particles are selected from the group consisting of ferric oxide, aluminum oxide, or mixtures thereof and have a diameter of 5 nm to 1000 nm;

applying a constant magnetic field to the pigment dispersion containing magnetic particles and non-magnetic abrasive particles, at a magnetic field strength effective for causing the magnetic particles to move relative to the pigment and non-magnetic abrasive particles, which in turn causes the pigment to be milled by the non-magnetic abrasive particles, thereby producing a pigment dispersion comprising a milled pigment having an average particle size of 10 nm to 500 nm dispersed in aqueous media.

2. The method of claim 1, wherein the magnetic field strength is 10 Gauss to 50,000 Gauss.

3. The method of claim 1, wherein the magnetic field is applied through one or more electromagnets, or a permanent magnet.

4. The method of claim 1, wherein the magnetic field is stationary or moving.

5. The method of claim 1, wherein the magnetic particles are selected from the group consisting of a paramagnetic material, ferromagnetic material, antiferromagnetic material and mixtures thereof.

6. The method of claim 1, wherein the non-magnetic abrasive particles have a nano indentation hardness value of 5 to 50 GPa.

7. The method of claim 1, wherein the non-magnetic abrasive particles are selected from the group consisting of aluminum oxide, SiC, cerium oxide, zirconium oxide, ferric oxide, bauxite, cubic zirconia powder, diamond powder, and mixtures thereof.

8. The method of claim 1, wherein the weight ratio of magnetic particles to non-magnetic abrasive particles is in a range of from about 0.5:

10 to about 10;

0.5.

9. The method of claim 1, wherein the volume ratio of the magnetic particles and non-magnetic abrasive particles to the pigment is in a range of from about 0.5:

10 to about 10;

0.5.

10. The method of claim 1, wherein the weight of the milled pigment is from about 1 to about 50% by weight of the pigment dispersion.

11. The method of claim 1, wherein the milled pigment has an average particle size of 10 nm to 100 nm dispersed in aqueous media.

12. The method of claim 1, wherein the duration of the process is from about 0.01 to about 5000 hours.

13. A method for producing a milled pigment dispersed in aqueous media, the method comprising:

mixing a pigment with water for a period of time sufficient to produce an aqueous pigment dispersion;

adding magnetic particles and non-magnetic abrasive particles to the pigment dispersion, thereby producing a pigment dispersion containing magnetic particles and non-magnetic abrasive particles, wherein the magnetic particles have a diameter of 5 nm to 1000 nm, and further wherein the non-magnetic abrasive particles are selected from the group consisting of ferric oxide, aluminum oxide, or mixtures thereof and have a diameter of 5 nm to 1000 nm;

agitating the pigment dispersion containing magnetic particles and non-magnetic abrasive particles while applying a constant magnetic field to the pigment dispersion containing magnetic particles and non-magnetic abrasive particles, at a magnetic field strength effective for causing the magnetic particles to remain substantially stationary while the pigment is milled by the non-magnetic abrasive particles, thereby producing a pigment dispersion comprising a milled pigment having an average particle size of 10 nm to 500 nm dispersed in aqueous media.

14. The method of claim 13, wherein the rate of the agitation is in the range of from about 50 to about 20,000 rpm.

15. The method of claim 13, wherein the agitation occurs during parts of or during the entire process.

16. The method of claim 13, wherein the milled pigment has an average particle size of 10 nm to 100 nm dispersed in aqueous media.

17. A method for producing a milled pigment dispersed in aqueous media, the method comprising:

mixing a pigment with water for a period of time sufficient to produce an aqueous pigment dispersion;

adding magnetic particles and non-magnetic abrasive particles to the pigment dispersion, thereby producing a pigment dispersion containing magnetic particles and non-magnetic abrasive particles, wherein the magnetic particles have a diameter of 5 nm to 1000 nm, and further wherein the non-magnetic abrasive particles have a diameter of 5 nm to 1000 nm;

agitating the pigment dispersion containing magnetic particles and non-magnetic abrasive particles while applying a constant magnetic field to the pigment dispersion containing magnetic particles and non-magnetic abrasive particles, at a magnetic field strength effective for causing the magnetic particles to remain substantially stationary while the pigment is milled by the non-magnetic abrasive particles, thereby producing a pigment dispersion comprising a milled pigment having an average particle size of 10 nm to 100 nm dispersed in aqueous media;

wherein the non-magnetic abrasive comprises ferric oxide, aluminum oxide, or mixtures thereof; and

the magnetic field has a strength of from 200 Gauss to 50,000 Gauss.