Inorganic microspheres
View Patent ↗This invention relates to inorganic microspheres having a relatively narrow particle size distribution, which may be prepared by spheridization of zeolite crystals. The microspheres are particularly useful for whitening polymer compositions and in other filler applications.
1. Substantially solid inorganic microspheres produced from crystals of a synthetic zeolite having a d 50 value from 1 to 50 microns.
2. The inorganic microspheres of claim 1 , having a size distribution ratio (d 90 −d 10 )/d 50 greater than 0.5.
3. The inorganic microspheres of claim 1 , having a size distribution ratio (d 90 −d 10 )/d 50 not greater than 2.
4. The inorganic microspheres of claim 1 , having a size distribution ratio (d 90 −d 10 )/d 50 from 0.5 to 2.
5. The inorganic microspheres of claim 1 , having a d 50 value from 3 to 10 microns and a size distribution ratio (d 90 −d 10 )/d 50 not greater than 1.5.
6. The inorganic microspheres of claim 1 , wherein said inorganic microspheres provide a Hunter L value of at least 80 when incorporated at a 20 weight percent level in a cured polyester composite.
7. The inorganic microspheres of claim 1 , wherein a portion of said inorganic microspheres are at least partially crystalline and a portion of said inorganic microspheres are fully amorphous or partially amorphous.
8. The inorganic microspheres of claim 1 , wherein the inorganic microspheres are an aluminosilicate having a molar ratio of SiO 2 :Al 2 O 3 of from 1:1 to 5:1.
9. The inorganic microspheres of claim 1 , having a true density of at least 1.7 g/cm 3 .
10. The inorganic microspheres of claim 1 , wherein said inorganic microspheres have been produced from crystals of a zeolite A.
11. The inorganic microspheres of claim 1 , wherein said inorganic microspheres are essentially free of agglomerates and/or non-spherical particles.
12. The inorganic microspheres of claim 1 , wherein said inorganic microspheres are comprised of greater than 25 weight % Al 2 O 3 .
13. The inorganic microspheres of claim 1 , wherein said inorganic microspheres are comprised of aluminosilicate.
14. The inorganic microspheres of claim 1 , wherein at least 95 wt % of the microspheres are measured to be spherical as determined by particle count using optical microscopy.
15. The inorganic microspheres of claim 1 , wherein the inorganic microspheres have a chemical composition corresponding to a) 17 to 27 weight % alkali metal oxide and/or alkaline earth metal oxide, b) 28 to 44 weight % Al 2 O 3 , and c) 33 to 51 weight % SiO 2 , the total of a+b+c being 90 to 100 weight %.
16. Substantially solid inorganic microspheres having a d 50 value from 1 to 50 microns and a size distribution ratio (d 90 −d 10 )/d 50 from 0.5 to 2, wherein said inorganic microspheres have been produced from crystals of a synthetic zeolite, provide a Hunter L value of at least 80 when incorporated at a 20 weight percent level in a cured polyester composite, and have a true density of at least 1.9 g/cm 3 and wherein a portion of said inorganic microspheres are at least partially crystalline and a portion of said inorganic microspheres are fully amorphous or partially amorphous.
17. Substantially solid inorganic microspheres having a d50 value from 3 to 10 microns and a size distribution ratio (d 90 −d 10 )/d 50 from 0.6 to 1.5, wherein said inorganic microspheres have been produced from crystals of a synthetic zeolite, provide a Hunter L value of at least 85 when incorporated at a 20 weight percent level in a cured polyester composite, are comprised of greater than 25 weight % Al 2 O 3 , and have a true density of at least 1.9 g/cm 3 and wherein a portion of said inorganic microspheres are at least partially crystalline and a portion of said inorganic microspheres are fully amorphous or partially amorphous.
18. A composition comprising at least one thermosettable resin or thermoplastic polymer and the inorganic microspheres of claim 1 .
19. A method of making a filled composition, said method comprising admixing the inorganic microspheres of claim 1 with at least one thermosettable resin or thermoplastic polymer.