| abstract |
An insulating magnetic toner useful as a one component developer for electro-photography consisting essentially of a ferro-magnetic material, a resin and a charge controlling agent. The preferred toner mixture has an average particle size in the range from about 7 to about 30 mu m and is substantially free of particles having a size smaller than 1 mu m. The toner is preferably prepared by mixing a ferromagnetic material, a resin and a charge controlling agent, heat kneading, cooling and then granulating the mixture to form fine particles, contacting the pacticles with a hot gas of a temperature higher than the toner softening point and lower than 500 DEG C to fuse particles smaller than about 1 mu m to larger particles, cooling and selecting the particles of an average particle size of about 7 to about 30 mu m. |