1. Field of the Invention
This invention relates to a white toner having stable triboelectric charging characteristics as a developer for use in electrophotography.
2. Description of the Prior Art
Image copying on colored paper using a white toner is known as a simmple method of obtaining a reversal image, i.e. a negative image, in electrophotography.
The white toner is obtained generally be dispersing a white pigment such as titanium dioxide in a fixing resin medium. With known white toners, however, it is difficult to obtain a uniform amount of triboelectric charge, and therefore, they have the disadvantage of causing various troubles such as the reduction of image density, background fog and image blurring. The difficulty of obtaining uniform triboelectric charge with known white toners is believed to be due to the hydroscopic nature of the white toners which leads to agglomeration in a developing device.