Highly delaminated hexagonal boron nitride powders, process for making, and uses thereof

• US 20040076572A1
• Filed: 10/16/2003
• Published: 04/22/2004
• Est. Priority Date: 05/01/2000
• Status: Active Grant

• Current Assignee: Severine M. Laboure, Thomas M. Clere
• Original Assignee: Severine M. Laboure, Thomas M. Clere
• Inventors: Laboure, Severine M., Clere, Thomas M.
• Granted Patent: US 6,951,583 B2
• Time in Patent Office: Days
• US Class Current: 423/290
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/04 Particle-shaped making granules B29B9/00
• CPC Class Codes: C01B 21/064 with boron
• CPC Class Codes: C01B 21/0648 After-treatment, e.g. grinding, purification transformation of hexagonal into cubic or wurtzitic boron nitride C04B35/5831
• CPC Class Codes: C01P 2002/04 Compounds with a limited amount of crystallinty, e.g. as indicated by a crystallinity index
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/77 by unit-cell parameters, atom positions or structure diagrams
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: Y10T 428/2916 including boron or compound thereof [not as steel]
• CPC Class Codes: Y10T 428/2927 including structurally defined particulate matter
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

The present invention relates to a powder comprising boron nitride particles having an aspect ratio of from about 50 to about 300. The present invention also relates to a method of making delaminated boron nitride powder. This method involves providing boron nitride powder and milling the boron nitride powder in a mixture including a milling media and a milling liquid under conditions effective to produce delaminated boron nitride powder.

Claims

1. A powder comprising hexagonal boron nitride particles having an aspect ratio of from about 50 to about 300.

2. The powder according to claim 1, wherein the particles have a surface area of at least about 20 m²/g.

3. The powder according to claim 2, wherein the particles have a surface area of at least about 40 m²/g.

4. The powder according to claim 3, wherein the particles have a surface area of at least about 60 m²/g.

5. The powder according to claim 1, wherein the particles have a characteristic diameter greater than about 1 micron.

6. The powder according to claim 1, wherein the particles have a D₁₀ diameter of between about 1 μ

m and about 2.5 μ

m.

7. The powder according to claim 1, wherein the particles have a thickness of no more than about 50 nm.

8. The powder according to claim 1, wherein the powder has a crystallization index of at least 0.15.

9. The powder according to claim 1, wherein the powder comprises no more than about 500 ppm B₂O₃.

10. The powder according to claim 1, wherein the powder comprises at least about 0.5 wt % B₂O₃.

11. A method of making delaminated hexagonal boron nitride powder comprising:

providing hexagonal boron nitride powder, and

milling the hexagonal boron nitride powder in a milling mixture under conditions effective to produce delaminated hexagonal boron nitride powder having an aspect ratio of from about 50 to about 300.

12. The method according to claim 11, wherein said providing comprises high fire treating raw boron nitride powder.

13. The method according to claim 11, wherein the hexagonal boron nitride powder has a crystallization index of at least 0.15.

14. The method according to claim 11, wherein the hexagonal boron nitride powder is from about 5 wt % to about 30 wt % of the milling mixture.

15. The method according to claim 11, wherein the milling mixture comprises a milling media and a milling liquid.

16. The method according to claim 15, wherein the milling media is zirconia, steel balls, alumina, silicon nitride, silicon carbide, boron carbide, calcium oxide, or magnesium oxide.

17. The method according to claim 15, wherein the milling media has an average diameter of from about 1 mm to about 20 mm.

18. The method according to claim 15, wherein the milling liquid is any liquid in which B₂O₃ is soluble.

19. The method according to claim 15, wherein the milling liquid is water, methanol, ethanol, propanol, butanol, isomers of low molecular weight alcohols, acetone, or supercritical CO₂.

20. The method according to claim 15, wherein the milling liquid is from about 70 wt % to about 90 wt % of the milling mixture.

21. The method according to claim 11 further comprising;

adding a dispersant to the milling mixture.

22. The method according to claim 11 further comprising:

adding from about 1 wt % to about 20 wt % alcohol to the milling mixture.

23. The method according to claim 11, wherein the milling is carried out for about 8 hours to about 48 hours.

24. The method according to claim 11, wherein the milling temperature is no more than about 30°

C.

25. The method according to claim 11 further comprising:

dry milling the hexagonal boron nitride powder before or after said milling.