Claims
- 1. An insulating composition in dry, free-flowing form and having low thermal conductivity, which comprises:
- a. 60 to 94 weight percent of a first siliceous material, being a particulate material having a silica content of at least 85 weight percent, a bulk density of 10 to 15 lb/ft.sup.3, an average particle size in the range of 50 to 100 microns, and a B.E.T. surface area of at least 175 m.sup.2 /g;
- b. 1 to 10 weight percent of a second siliceous material, being a particulate material having a silica content of at least 85 weight percent, a bulk density of 0.5 to 2.5 lb/ft.sup.3, average particle size of 1 to 10 microns, and a B.E.T. surface area of 80 to 150 m.sup.2 /g; and
- c. 5 to 30 weight percent of a particulate opacifier having its individual particle size essentially all in the range of 10 to 80 microns.
- 2. The composition of claim 1 wherein said first siliceous material is present as 65 to 85 weight percent of said composition.
- 3. The composition of claim 2 wherein said first siliceous material has an average particle size of 60 to 95 microns.
- 4. The composition of claim 3 wherein said first siliceous material has a bulk density of 12 to 13 lb/ft.sup.3.
- 5. The composition of claim 1 wherein said second siliceous material is present as 4 to 8 weight percent of said composition.
- 6. The composition of claim 5 wherein said second siliceous material has an average particle size of 1 to 5 microns.
- 7. The composition of claim 6 wherein said second siliceous material has a bulk density of 1.0 to 2.2 lb/ft.sup.3.
- 8. The composition of claim 1 wherein said opacifier is selected from the group consisting of titanium dioxide, zirconium oxide, and silicon.
- 9. The composition of claim 8 wherein said opacifier is present as 10 to 25 weight percent of said composition.
- 10. The composition of claim 1 further comprising 0.1 to 10 weight percent of a third siliceous material, being a finely divided particulate material having a silica content of at least 90%, a bulk density of 0.5 to 3.0 lb/ft.sup.3, an average particle size of 0.005 to 0.1 microns, and a B.E.T. surface area of at least 150 m.sup.2 /g.
- 11. The composition of claim 10 wherein said third siliceous material has a B.E.T. surface area of 175 to 225 m.sup.2 /g.
- 12. The composition of claim 10 wherein said third siliceous material has an average particle size of 0.010 to 0.015 microns.
- 13. The composition of claim 10 wherein said third siliceous material is present as 1 to 8 weight percent of the composition.
CROSS-REFERENCE TO RELATED APPLICATION
The application is a continuation-in-part of application Ser. No. 281,100, filed Aug. 16, 1972, and now abandoned.
US Referenced Citations (5)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
281100 |
Aug 1972 |
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