Black magnetic iron oxide particles having high breakdown voltage
US7572505B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 2007 |
| Grant date | Aug 11, 2009 |
| Priority date | — |
| Expiry date | Apr 19, 2027 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2993
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention relates to black magnetic iron oxide particles comprising core particles and a surface layer formed on a surface of the respective core particles which is made of a compound of at least one alkali earth metal element selected from the group consisting of Mg, Ca, Sr and Ba and an aluminum element, in which a content of the at least one alkali earth metal element present in the surface layer is from 100 ppm to 1000 ppm on the basis of a whole weight of the black magnetic iron oxide particles; a content of the aluminum element present in the surface layer is from 1000 ppm to 20000 ppm on the basis of a whole weight of the black magnetic iron oxide particles; a ratio [A/B] of the content [A (ppm)] of the aluminum element to the content [B (ppm)] of the at least one alkali earth metal element present in the surface layer is from 1 to 100; and a molded product comprising said black magnetic iron oxide particles has a breakdown voltage of not less than 400 V/cm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.