Showa Denko K.k.

Ricoh Company, Ltd.

Showa Denko Kabushiki Kaisha

Mitsuru Hasegawa

Atsushi Ohta

Tadashi Hiraiwa

Tetsuo Hatanaka

Seiji Ishii

Toshiaki Sakaida

Naoaki Ohishi

Iwao Hiramatsu

A method of producing a developing roller applicable to a developing device included in an image forming apparatus and capable of carrying a great amount of toner thereon by generating microfields. The surface of a conductive base is covered with a net constituting of conductive fibers and dielectric fibers woven together. The fibers are heated by a heater to melt with the result that conductive portions and dielectric portions appear on the surface of the developing roller.

Toner carrier and method of producing the same

An abrasive grain for use as a grinding material comprising alpha-alumina crystal particles substantially smaller than 0.5 microns, solidly dissolved with at least one of Ti, Mn, V, Ga, Zn and Rh, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 from 4.75892 to 4.76340 angstroms when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and an abrasive grain for a grinding material, comprising alpha-alumina crystal particles substantially less than 0.5 microns, solidly dissolved with at least one of Mg, Ni and Co, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 from 4.75930 to 4.76340 .ANG. when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and further, a grinding wheel and coated cloth manufactured from these abrasive grains.

Abrasive grain and manufacture for the same

An abrasive grain for use as a grinding material characterized by alpha-corundum crystal particles substantially smaller than 0.5 micron, solidly dissolved with at least one element out of Ti, Mn, V, Ga, Zn and Rh, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 at 4.75892 to 4.76340 angstrom when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and an abrasive grain for a grinding material, characterized by alpha-corundum crystal particles substantially less than 0.5 micron, solidly dissolved with at least one element out of Mg, Ni and Co, and with an a-axis length of the hexagonal unit cell of the alpha-Al.sub.2 O.sub.3 at 4.75930 to 4.76340 A when measured by a powder X-ray diffraction method, and a density of more than 90% of the theoretical value, and further, a grindstone and grinding cloth manufactured that these abrasive grains.

Abrasive grain and method for manufacturing the same

In the manufacture of a wiring board, or a heat discharge plates and the like in the field of the electronics, composite materials consisting of substrates and organic polymeric materials and epoxy resin, as well as ceramic materials such as alumina plates, have heretofore been used as substrates of printed wiring boards and heat sinks. These substrate materials, however, are defective in that, because of a low thermal conductivity and an insufficient heat radiation. A highly thermal conductive and electrical insulating substrate of the invention comprises a highly thermal conductive metal plate, such as aluminum, and a film formed thereon, said film being composed of a dispersion of metal oxide particles having a shape factor, of 1 to 1.4, and also, having a polyhedral shape including smooth surfaces in an adhesive organic polymer. The space factor is an average value of the long diameter/short diameter ratio of the metal oxide particles.

Highly thermal conductive and electrical insulating substrate

A method for preparing corundum particles by a hydrothermal process which comprises adding fine particles of corundum to a starting alumina hydrate, and subjecting the resulting mixture to a hydrothermal reaction or treatment, the alumina in the alumina hydrate being deposited on the surfaces of the fine corundum particles while suppressing formation of new corundum crystal nuclei.

Growing community of inventors

Shiojiri, Japan

Mitsuru Hasegawa