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AssigneeMita Industrial Co., Ltd.
InventorsNoriaki Tsubota, Masahiko Kubo, Kazuo Fuji, Akihiro Watanabe, Yoshihisa Kuramae
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The electrophotographic toner for negative charging according to the present invention is characterized in that an acrylamide copolymer-containing sulfonic acid group is used as a charge-controlling agent for negative charging and a quaternary ammonium salt having an oxyacid anion is used as a charge-controlling assistant in combination with the charge-controlling agent. This quaternary ammonium salt used as the assistant is incompatible with a fixing resin but dispersible therein. Therefore, the toner of the present invention provides a sharp distribution of the charge quantity, and formation of a highly charged toner having no contribution to development or a lowly charged toner causing scattering of the toner can be effectively prevented.
An electrophotographic toner for negative charging, comprising a fixing resin, a colorant, a charge-controlling agent for negative charging, and a charge-controlling assistant, wherein the charge controlling agent for negative charging is a copolymer of an acrylamide monomer represented by the following formula (1)
Dependencies are inferred from the claim text.