PURPOSE: To prevent defects of a coating layer and to retain humidity resistance for a long term by forming a coating layer composed essentially of a titanium type coupling agent, a surfactant, and a resin on the surface of the core material of an inorg. carrier.
CONSTITUTION: A coating layer composed essentially of a titanium type coupling agent and a resin is formed on the surface of an inorg. carrier core material. The carrier core materials have particle diameters of 30W1,000μm, and the ones which have been so far used as the carrier core materials, e.g., an inorg. material, such as sand or glass, a metal, such as Co, Fe, Cu, Ni, Zn, or Al, or alloy or oxide or compd. of them, such as brass or ferrite, can be used. As the surfactant, all the general surfactants having a hydrophilic group and a hydrophobic group in the molecule can be used. The coupling agent, the surfactant, and the coating resin need to be mixed in the range of appropriate proportions, and when the surfactant is used too much, fluidity as a developer is lowered, and conveyability is also deteriorated. A preferable amt. of the coupling agent is 0.1W10wt%, and that of the surfactant is 0.01W5wt%.
NAGAI TATSUROU
SUZUKI SHINICHI
