Spherical particles of titanium dioxide coated with a uniform layer of iron oxides having a narrow size distribution, and process for preparing the same
US4675251A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 1986 |
| Grant date | Jun 23, 1987 |
| Priority date | — |
| Expiry date | Feb 18, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2993
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Spherical particles having sizes below 1 .mu.m, or at maximum of 3.04 .mu.m, a narrow size size distribution consisting, or consisting essentially, of TiO.sub.2 coated by a uniform layer having a thickness up to 400 .ANG. consisting essentially .alpha.-, or .gamma.-Fe.sub.2 O.sub.3, or magnetite, or mixtures thereof, said particles being prepared by a process consisting, or consisting essentially, in the precipitation of the oxide from Fe (III) salt solutions on the surface of solid pre-formed TiO.sub.2 particles having a narrow size distribution and a number average diameter below 1 .mu.m or .ltoreq.3 .mu.m, the Fe (III) concentration being .ltoreq.40% by weight calculated on TiO.sub.2, the pH of the suspension ranging from 1.0 to 2.8, extremes excluded, by heating the suspensions to temperatures of from 80.degree. to 100.degree. C., and by aging them under such conditions for at least 30 minutes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.