Thermal extractive gelation process
US4931414A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1988 |
| Grant date | Jun 5, 1990 |
| Priority date | — |
| Expiry date | Jun 10, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2982
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Solid, transparent, non-vitreous, microspheres (zirconia-silica) are formed by extractive gelation (extracting carboxylic acid away from zirconyl carboxylate) of a sol in liquid medium such as hot peanut oil. Zirconyl carboxylate precursor sol is prepared and added in droplet form to the liquid extractant (peanut oil) at an elevated temperature at which a carboxylic acid is liberated from the zirconyl carboxylate. The droplets remain in the extractant for sufficient time to form stable gel spheroids which are separated from the extractant and fired to convert them to durable spheroids useful as lens elements in retroreflective sheeting.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.