Zirconia sol, process of making and composite material

• US 6,376,590 B2
• Filed: 10/28/1999
• Issued: 04/23/2002
• Est. Priority Date: 10/28/1999
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Chien, Bert T., Kolb, Brant U.
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US09/428,374
• Publication Number:
  US 20020004544A1
• Time in Patent Office: 908 Days
• Field of Search: 516/90, 106/287.19, 106/450, 423/608, 524/413, 501/12, 522/81, 523/117
• US Class Current: 524/413
• CPC Class Codes: B01J 13/0008 Sols of inorganic materials in water
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 25/02 Oxides
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C08K 2003/2244 of zirconium
• CPC Class Codes: C08K 3/22 of metals

Abstract

A zirconia sol comprising an aqueous phase having dispersed therein a plurality of single crystal zirconia particles having an average primary particle size less than about 20 nm. The zirconia sols are substantially non associated having a dispersion index ranging from about 1-3 and are highly crystalline exhibiting a crystallinity index of about 0.65 or greater. Of the crystalline phase, about 70% or greater exists in combined cubic and tetragonal crystal lattice structures without a crystal phase stabilizer. Also described is a hydrothermal method of making zirconia sols having substantially non-associated zirconia particles and composite materials made from the zirconia sols.

Claims

1. A zirconia sol comprising:

an aqueous phase having dispersed therein a plurality of substantially non-associated single crystal zirconia particles having an average primary particle size about 20 nm or less and a dispersion index ranging from about 1-3, wherein the zirconia particles have a crystallinity index of about 0.65 or greater and about 70% or greater combined cubic and tetragonal crystal lattice structure in the absence of an effective amount of a crystal phase stabilizer.

2. The zirconia sol of claim 1, wherein the zirconia sol has an optical transmission of about 70% or greater at about 1.28 wt. % ZrO₂.

3. The zirconia sol of claim 1, wherein the zirconia sol has an optical transmission of about 20% or greater at about 10 wt. % ZrO₂.

4. The zirconia sol of claim 1, wherein the dispersion index ranges from about 1-2.5.

5. The zirconia sol of claim 1, wherein the dispersion index ranges from about 1-2.

6. The zirconia sol of claim 1, wherein the zirconia particles have an average primary particle size ranging from about 7-20 nm.

7. The zirconia sol of claim 1, wherein the zirconia particles have about 75% or greater combined cubic and tetragonal crystal lattice structure.

8. The zirconia sol of claim 1, wherein the zirconia particles have about 85% or greater combined cubic and tetragonal crystal lattice structure.

9. The zirconia sol of claim 1, wherein the zirconia particles comprise less than about 1 wt. % of a crystal phase stabilizer.

10. The zirconia sol of claim 1, wherein the pH of the sol is less than about 7.

11. The zirconia sol of claim 1, wherein the pH of the sol ranges from about 1-4.5.

12. The zirconia sol of claim 1, wherein the zirconia particles each have an outer surface and wherein a plurality of polyether carboxylic acid molecules are adsorbed onto the outer surface.

13. The zirconia sol of claim 12, wherein the polyether carboxylic acid has the general formula:

14. The zirconia sol of claim 13, wherein the polyether carboxylic acid is selected from the group consisting of 2-[2-(2-methoxyethoxy)ethoxy] acetic acid and 2-(2-methoxyethoxy) acetic acid.

15. The zirconia sol of claim 1 further including a polyether carboxylic acid wherein at least a portion of the polyether carboxylic acid is adsorbed onto the zirconia particles.

16. The zirconia sol of claim 1, wherein the aqueous phase comprises a mixture of water and at least one carboxylic acid.

17. The zirconia sol of claim 1, wherein the zirconia particles have a cube-like shape.

18. A process for preparing a zirconia sol comprising the steps of:

(a) providing an aqueous solution comprising a polyether acid zirconium salt; and

(b) hydrolyzing the aqueous solution of the polyether acid zirconium salt by heating the solution at a temperature and a pressure sufficient to convert the polyether acid zirconium salt into crystalline zirconia particles.

19. The process for preparing a zirconia sol of claim 18, wherein step (a) comprises:

(A) reacting an aqueous solution or sol of a zirconium salt with a polyether carboxylic acid to form an aqueous solution comprising a polyether acid zirconium salt and a free acid; and

(B) optionally, removing at least a portion of the free acid.

20. The process for preparing a zirconia sol of claim 19, wherein step (B) comprises:

(1) drying the aqueous solution of the polyether acid zirconium salt; and

(2) dispersing the dried acid polyether acid zirconium salt in water to form an aqueous solution.

21. The process for preparing a zirconia sol of claim 19, wherein the polyether carboxylic acid has the general formula:

22. The process for preparing a zirconia sol of claim 19, wherein the polyether carboxylic acid is selected from the group consisting of 2-[2-(2-methoxyethoxy)ethoxy] acetic acid and 2-(2-methoxyethoxy) acetic acid.

23. The process for preparing a zirconia sol of claim 19, wherein the zirconium salt has the general formula:

24. The process for preparing a zirconia sol of claim 19, wherein the zirconium salt is zirconium acetate.

25. The process for preparing a zirconia sol of claim 18, wherein the temperature ranges from about 140-250°

C.

26. The process for preparing a zirconia sol of claim 18, wherein the pressure ranges from about 1-30 bars.

27. A zirconia sol prepared according to the process of claim 18.

28. A zirconia sol prepared according to the process of claim 18, said zirconia sol comprising:

an aqueous phase having dispersed therein a plurality of substantially non-associated single crystal zirconia particles having an average primary particle size about 20 nm or less and a dispersion index ranging from about 1-3, wherein the zirconia particles have a crystallinity index of about 0.65 or greater and about 70% or greater combined cubic and tetragonal crystal lattice structure in the absence of an effective amount of a crystal phase stabilizer.

29. A composite material comprising:

an organic matrix material having dispersed therein a plurality of single crystal zirconia particles having an average primary particle size less than about 20 nm and having a dispersion index ranging from about 1-3, wherein the zirconia particles have a crystallinity index of about 0.65 or greater and about 70% or greater combined cubic and tetragonal crystal lattice structure in the absence of an effective amount of a crystal phase stabilizer.

30. The composite material of claim 29 having an index of refraction of about 1.6 or greater.

31. The composite material o f claim 29 having an index of refraction of about 1.75 or greater.

32. The composite material of claim 29, wherein the organic matrix material is a monomer, oligomer, polymer or a mixture thereof.

33. The composite material of claim 29, wherein the organic matrix material is selected from the group consisting of acrylates, methacrylates, epoxies, styrenes and mixtures thereof.

34. The composite material of claim 29, wherein the organic matrix material is selected from the group consisting of polyolefms, polyesters, polyurethanes, polymethylmethacrylates, polystyrenes, polycarbonates, polyimides and mixtures thereof.