Electrophotographic development magnetic resin coated carrier
AssigneesMita Industrial Co., Ltd., TDK Corporation
InventorsKoichi Tsuyama, Hiroshi Harada
Life of this patent
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Abstract
Magnetic carrier for use in electrophotographic development takes the form of ferrite core particles each having a resinous coating. Ferrite core particles having a limited particle size distribution are coated with a resinous composition based on a copolymer consisting essentially of ethyl methacrylate, 15 to 25% by weight of styrene, up to 2% by weight of dodecyl methacrylate, and up to 2% by weight of 2-hydroxyethyl acrylate. The magnetic carrier particles have a resistance of 8.5.times.10.sup.7 to 2.2.times.10.sup.9 .OMEGA.. This carrier has a sharp distribution of electric charge and a quick rise of charging performance. The coating is tough enough to impart durability to the carrier.
Claims5
In magnetic carrier particles for use in electrophotographic development, each in the form of a ferrite core particle having a resinous coating on the surface thereof,
- the improvement wherein at least 90% by weight of said ferrite core particles have a saturation magnetization of 45 to 55 emu/g and a particle size of 74 to 149 .mu.m,
- said resinous coating has a copolymer composition comprising a major proportion of a copolymer of ethyl methacrylate and styrene having a styrene content of from 15 to 25% by weight of the copolymer, 0.1 to 2% by weight of dodecyl methacrylate, and 0.1 to 2% by weight of 2-hydroxyethyl acrylate, and
- the magnetic carrier particles have a resistance of 8.5.times.10.sup.7 to 220.times.10.sup.7 .OMEGA..
Dependencies are inferred from the claim text.