Modified pigments and methods for making and using the same

• US 8,147,608 B2
• Filed: 03/08/2011
• Issued: 04/03/2012
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Sensient Colors, LLC (Sensient Technologies Corporation)
• Original Assignee: Sensient Colors, LLC (Sensient Technologies Corporation)
• Inventors: Sujeeth, Puthalath K., Ulrich, Mark, Kane, John P., Ouellette, Daniel A., Srouji, Gabe
• Primary Examiner(s): Green, Anthony J
• Application Number:
  US13/042,803
• Publication Number:
  US 20110239903A1
• Time in Patent Office: 392 Days
• Field of Search: 106/410, 106/411, 106/412, 106/413, 106/473, 106/476, 106/493, 106/494, 106/495, 106/496, 106/497, 106/498, 106/499
• US Class Current: 106/493
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01P 2002/70 defined by measured X-ray, neutron or electron diffraction data
• CPC Class Codes: C01P 2002/88 by thermal analysis data, e.g. TGA, DTA, DSC
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/22 Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
• CPC Class Codes: C08K 3/013 Fillers, pigments or reinforcing additives
• CPC Class Codes: C08K 3/04 Carbon
• CPC Class Codes: C08K 9/02 Ingredients treated with inorganic substances
• CPC Class Codes: C08K 9/04 Ingredients treated with organic substances treated with macromolecular compounds C08K9/08
• CPC Class Codes: C09C 1/56 Treatment of carbon black ; Purification
• CPC Class Codes: C09C 1/565 comprising an oxidative treatment with oxygen, ozone or oxygenated compounds, e.g. when such treatment occurs in a region of the furnace next to the carbon black generating reaction zone
• CPC Class Codes: C09D 11/322 Pigment inks
• CPC Class Codes: C09D 7/41 Organic pigments; Organic dyes
• CPC Class Codes: C09D 7/62 modified by treatment with other compounds

Abstract

A method of producing a modified pigment by sulfonating a pigment and subsequently oxidizing the pigment. The modified pigment may have sulfonic acid and carboxyl surface modifying groups attached to the surface of the pigment. Charge balancing counterions such as alkali metals, alkaline earth metals and NR₁R₂R₃H⁺, where R₁, R₂ and R₃ are independently H or C₁-C₅ alkyl groups, may be associated with the surface modifying groups. The modified pigment is combined with water to produce a dispersion that can be used in such applications as coatings, paints, papers, adhesives, latexes, toners, textiles, fibers, plastics and inks.

Claims

1. A method of modifying a pigment, the method comprising:

sulfonating a pigment comprising at least one of an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, a thioindigo pigment, a triphenylmethane lake pigment, an oxazine lake pigment, and a carbon black comprising an aggregate of carbon black particles; and

subsequently oxidizing the pigment to produce a modified pigment.

2. The method of claim 1, wherein the modified pigment is a self-dispersing pigment.

3. The method of claim 1, wherein the pigment comprises the carbon black, and the size of the aggregate of carbon black is less than about 200 nm.

4. The method of claim 1, wherein the surface area of the pigment is greater than about 100 m²/g.

5. The method of claim 1, wherein sulfonation is carried out with an acid comprising at least one of sulfuric acid, oleum, and a combination thereof.

6. The method of claim 1, wherein the sulfonation is carried out at a temperature of about 25°

C. to about 160°

C.

7. The method of claim 1, wherein oxidation is carried out with a hypohalite salt.

8. The method of claim 1, further comprising milling the pigment before oxidation, during oxidation, after oxidation, or any combination thereof.

9. The method of claim 1, wherein the modified pigment is obtained as an aqueous pigment dispersion.

10. The method of claim 9, further comprising concentrating the dispersion to at least about 8% solids.

11. A modified pigment comprising:

a pigment having a surface, wherein the pigment is selected from the group consisting of an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, a thioindigo pigment, a triphenylmethane lake pigment, an oxazine lake pigment, and a carbon black comprising an aggregate of carbon black particles;

a sulfonic acid surface modifying group attached to the surface of the pigment;

a carboxyl surface modifying group attached to the surface of the pigment; and

a charge-balancing counterion associated with the surface modifying group comprising at least one of an alkali metal, an alkaline earth metal, a NR₁R₂R₃H⁺, and combinations thereof, where R₁, R₂ and R₃ are independently H or C₁-C₅ alkyl groups that are substituted or unsubstituted, K⁺, Li⁺, NH₄⁺, monoethanolammonium, triethanolammonium, tetramethylammonium, tetrabutylammonium, and combinations thereof,

wherein the modified pigment comprises about 0.02 to about 1.0 mMoles of S and about 0.2 to about 2.0 mMoles of active hydrogen per gram of pigment.

12. The modified pigment of claim 11, wherein the pigment is self-dispersing.

13. The modified pigment of claim 11, wherein the pigment comprises the carbon black, and the size of the aggregate of carbon black is less than about 200 nm.

14. The modified pigment of claim 11, further comprising a lactone group, a phenolic group, a quinone group, and combinations thereof attached to the surface of the pigment.

15. An aqueous dispersion comprising the modified pigment of claim 12.

16. The dispersion of claim 15, wherein the modified pigment takes up about 0.1 to about 1.7 mMoles of HCl when titrated with 2.0 N HCl.

17. The dispersion of claim 15, wherein the dispersion will undergo less than 10% change in at least one of mean particle size, viscosity, surface tension, and pH when stored at 70°

C. for at least two weeks.

18. A method of modifying a pigment, the method comprising:

sulfonating a pigment with at least one of sulfonic acid, oleum, and a combination thereof; and

subsequently oxidizing the pigment with a hypohalite salt.

19. The method of claim 18, wherein the modified pigment is a self-dispersing pigment.

20. The method of claim 18, wherein the surface area of the pigment is greater than about 100 m²/g.

21. The method of claim 18, wherein the sulfonation is carried out at a temperature of about 25°

C. to about 160°

C.

22. The method of claim 18, further comprising milling the pigment before oxidation, during oxidation, after oxidation, or any combination thereof.