Mitsui Toatsu Chemicals, Incorporated

Hiroshi Taniwaki

Masaaki Shin

Akio Fujiwara

An electrophotographic toner, which can exhibit good fixation in high-speed copying and is not affected by an environment such as high humidity, is provided by containing, as a principal component thereof, a resin blend composed of (a) 40-90 wt. % of a vinyl copolymer (I) formed of 70-97 wt. % of an aromatic vinyl monomer, 3-30 wt. % of an alkyl fumarate which is an C.sub.1-8 monoalkyl or dialkyl ester and 0-5 wt. % of an acid monomer and having a number average molecular weight of 2,000-15,000 and (b) 10-60 wt. % of a vinyl polymer (II) having a number average molecular weight of 20,000-500,000.

Electrophotographic toner for high speed electrophotography

An electrophotographic toner, which can exhibit good fixation in high-speed copying and is not affected by an environment such as high humidity, is provided by containing, as a principal component thereof, a resin blend composed of (a) 40-90 wt. % of a vinyl copolymer (I) formed of 70-97 wt. % of an aromatic vinyl monomer, 3-30 wt. % of an alkyl fumarate which is a C.sub.1-8 monoalkyl or dialkyl ester and 0-5 wt. % of an acid monomer and having a number average molecular weight of 2,000-15,000 and (b) 10-60 wt. % of a vinyl polymer (II) having a number average molecular weight of 20,000-500,000.

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Yokohama, Japan

Hiroshi Taniwaki