Patent attributes
Provided is a surface-modified metal oxide powder obtained by treating a surface of a metal oxide powder, wherein a ratio (A/B) of an initial triboelectrostatic charge amount (A) at a time of one minute after dispersion of the surface-modified metal oxide powder into a ferrite carrier to a triboelectrostatic charge amount (B) after a lapse of 30 additional minutes is from 1.0 to 2.0, and the triboelectrostatic charge amount (B) is from −300 to +300 μC/g. The surface-modified metal oxide powder has a weaker charging property and a better stability over time of a triboelectrostatic charge amount than a conventional one; and thus, when this powder is used as an external additive, various properties including flowability and electrical charging can be stabilized, and in addition, problems such as fogging and image deterioration can be drastically remedied without significantly deteriorating characteristics as a developer and the like.
