Silica powders for powder evacuated thermal insulating panel and method
US5376449A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1993 |
| Grant date | Dec 27, 1994 |
| Priority date | — |
| Expiry date | Jul 9, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2982
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2 /g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.