Boron nitride particles of spherical geometry and process of making
View Patent ↗A low viscosity filler boron nitride agglomerate particles having a generally spherical shape bound together by an organic binder and to a process for producing a BN powder composition of spherically shaped boron nitride agglomerated particles having a treated surface layer which controls its viscosity.
1. A spherical boron nitride powder consisting essentially of spherical agglomerates of non-spherical shaped boron nitride particles, where the agglomerates have an average agglomerate size of from about 1 micron to about 275 microns.
2. The spherical boron nitride powder of claim 1 , wherein the spherical agglomerates are spherical agglomerates of boron nitride platelets.
3. The spherical boron nitride powder of claim 1 , wherein the agglomerates have an average agglomerate size of 3 microns to about 150 microns.
4. The spherical boron nitride powder of claim 1 , wherein a majority of the spherical agglomerates have a minimum diameter of 1 micron or greater.
5. The spherical boron nitride powder of claim 4 , wherein about 98% of the agglomerates have a minimum diameter of 1 micron or greater.
6. The spherical boron nitride powder of claim 1 , wherein a majority of the spherical agglomerates have a minimum diameter of 5 microns or greater.
7. The spherical boron nitride particles of claim 1 , wherein a majority of the spherical agglomerates have a diameter of from 1 to about 275 microns.
8. A boron nitride powder comprising agglomerated particles of spherical geometry, wherein said spherical agglomerate particles have an average particle size of about 1 to 275 microns in diameter, wherein the particles have a surface layer comprising an organic binder and/or decomposition product thereof, wherein the decomposition product comprises an oxide or a hydroxide, wherein the organic binder is selected from the group consisting of a polyacrylate, a polyvinyl, an acetate, an acrylic, an acrylamide, or a combination of two or more thereof, and wherein the spherical agglomerates particles are prepared by (a) spray drying an aqueous slurry of non-spherical shaped boron nitride particles with a binder, and (b) sintering the spherical boron nitride particles.
9. The boron nitride powder of claim 8 , wherein the non-spherical shaped boron nitride particles comprise platelet boron nitride particles.
10. The boron nitride powder of claim 8 , wherein the spherical agglomerates have an average particle size of about 3 to about 150 microns.
11. The boron nitride powder of claim 8 , wherein a majority of the agglomerate particles have a minimum diameter of about 1 micron or greater.
12. The boron nitride powder of claim 11 , wherein from a majority up to about 98% of the agglomerated particles have minimum diameter of about 1 micron or greater.
13. The boron nitride powder of claim 8 , wherein a majority of the agglomerated particles have a minimum diameter of about 5 micron or greater.
14. The boron nitride powder of claim 8 , wherein a majority of the agglomerated particles have a minimum diameter of about 1 micron or greater and a maximum diameter of about 275 microns.
15. The boron nitride powder of claim 8 , wherein the organic binder is a polyacrylate.
16. The boron nitride powder of claim 8 , wherein the organic binder is a polyvinyl.
17. The boron nitride powder of claim 16 , wherein the polyvinyl is selected from the group consisting of polyvinyl butyral, polyvinyl alcohol, or a combination thereof.
18. The boron nitride powder of claim 17 , wherein the polyvinyl is polyvinyl alcohol.
19. The boron nitride powder of claim 8 , wherein the organic binder is styrene or a styrene/acrylic copolymer.