Modified pigments and methods for making and using the same

• US 7,927,416 B2
• Filed: 10/31/2007
• Issued: 04/19/2011
• 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: Srouji, Gabe, Ulrich, Mark, Kane, John P., Ouellette, Daniel A., Sujeeth, Puthalath K.
• Primary Examiner(s): Green; Anthony J
• Application Number:
  US11/933,116
• Publication Number:
  US 20080115695A1
• Time in Patent Office: 1,266 Days
• Field of Search: 106/476, 106/493, 106/494, 106/410, 106/411, 106/412, 106/413, 106/473, 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; and

subsequently oxidizing the pigment to produce a modified pigment.

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

3. The method of claim 1, wherein the pigment comprises at least one of carbon black, pigment red 122, pigment yellow 74, pigment yellow 97, pigment yellow 138, pigment yellow 155, pigment blue 15:

1, pigment blue 15;

3, solvent blue 67, solvent yellow 33, and combinations thereof.

4. The method of claim 1, wherein the pigment comprises carbon black.

5. The method of claim 1, wherein the pigment comprises at least one of pigment red 122, pigment blue 15:

1, pigment blue 15;

3 and solvent yellow 33.

6. The method of claim 4, wherein the average primary particle size of the pigment is less than about 30 nm.

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

8. 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.

9. The method of claim 8, wherein the acid to pigment ratio during sulfonation is at least about 4:

1 (wt/wt).

10. The method of claim 8, wherein the strength of the acid is about 85% to about 104% (weight of sulfuric acid/total weight).

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

C. to about 160°

C.

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

13. The method of claim 12, wherein the proportion by weight of hypohalite salt to pigment is about 1:

20 to about 1;

1.

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

15. The method of claim 1, wherein the sulfonation and the oxidation attach surface modifying groups to a surface of the pigment, and the surface modifying groups are associated with charge-balancing counterions, and further comprising at least partially substituting the counterions of the modified pigment with at least one of alkali metals, alkaline earth metals, NR₁R₂R₃H⁺, and combinations thereof, where R₁, R₂ and R₃ are independently H or C₁-C₅ alkyl groups that are substituted or unsubstituted.

16. The method of claim 1, wherein the sulfonation and the oxidation attach surface modifying groups to a surface of the pigment, and the surface modifying groups are associated with charge-balancing counterions, further comprising at least partially substituting the counterions of the modified pigment with at least one of K⁺, Li⁺, NH₄⁺, monoethanolammonium, triethanolammonium, tetramethylammonium, tetrabutylammonium, and combinations thereof.

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

18. The method of claim 17, further comprising concentrating the dispersion to at least about 8% solids.

19. The method of claim 1, 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.

20. The method of claim 4, wherein the modified pigment as an aqueous dispersion takes up about 1.4 to about 1.7 mMoles of HCl when titrated with 2.0 N HCl.

21. The method of claim 4, wherein the pigment undergoes three weight loss regions from about 100°

C. to about 800°

C. during thermal gravimetric analysis where the total weight loss over the three regions is equivalent to at least 3,500 μ

Moles CO₂/g carbon.

22. A modified pigment comprising:

a pigment having a surface;

sulfonic acid surface modifying groups attached to the surface of the pigment;

carboxyl surface modifying groups attached to the surface of the pigment; and

charge-balancing counterions associated with the surface modifying groups,

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.

23. The modified pigment of claim 22, wherein the pigment is self-dispersing.

24. The modified pigment of claim 22, wherein the charge-balancing counterions comprise at least one of alkali metals, alkaline earth metals, NR₁R₂R₃H⁺, and combinations thereof, where R₁, R₂ and R₃ are independently H or C₁-C₅ alkyl groups that are substituted or unsubstituted.

25. The modified pigment of claim 22, wherein the charge-balancing counterions comprise at least one of K⁺, Li⁺, NH₄⁺, monoethanolammonium, triethanolammonium, tetramethylammonium, tetrabutylammonium, and combinations thereof.

26. The modified pigment of claim 22, wherein the modified pigment as an aqueous dispersion takes up about 0.1 to about 1.7 mMoles of HCl when titrated with 2.0 N HCl.

27. The modified pigment of claim 22, wherein the pigment comprises carbon black.

28. A dispersion comprising:

a self-dispersing pigment comprising 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; and

water.

29. The dispersion of claim 28, wherein the pigment further comprises sulfonic acid surface modifying groups, carboxyl surface modifying groups, and charge-balancing counterions associated with the surface modifying groups, wherein the charge-balancing counterions comprise at least one of alkali metals, alkaline earth metals, NR₁R₂R₃H⁺, and combinations thereof, where R₁, R₂ and R₃ are independently H or C₁-C₅ alkyl groups that are substituted or unsubstituted.

30. The dispersion of claim 28, wherein the pigment further comprises sulfonic acid surface modifying groups, carboxyl surface modifying groups, and charge-balancing counterions associated with the surface modifying groups, wherein the charge-balancing counterions comprise at least one of K⁺, Li⁺, NH₄⁺, monoethanolammonium, triethanolammonium, tetramethylammonium, tetrabutylammonium, and combinations thereof.

31. The dispersion of claim 28, wherein the self-dispersing pigment takes up about 0.1 to about 1.7 mMoles of HCl when titrated with 2.0 N HCl.

32. The dispersion of claim 28, 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.

33. The dispersion of claim 32, wherein the dispersion will undergo less than 10% change for at least 3 weeks.

34. The dispersion of claim 32, wherein the dispersion will undergo less than 10% change in viscosity when stored at 70°

C. for at least four weeks.

35. The dispersion of claim 32, wherein the dispersion will undergo less than 10% change in surface tension.