Mita Industrial Co., Ltd.

Hidenori Asada

Takeshi Arakawa

Nobuyuki Tsuji

Hiroshi Komata

Shigeki Yamada

Takahiko Kimura

Masami Tsujihiro

Nobuhiro Hirano

Masahide Inoue

Koichi Tsuyama

Masanori Fujii

Kiminori Umeda

Toshiaki Akiyama

Atsushi Yamaguchi

Takuya Kadota

Shunsuke Ogami

Akemi Uchizono

Disclosed is a toner comprising a fixing resin, a colorant, a releasant made of a polyolefin having a melting point of not more than 120.degree. C., preferably 60 to 120.degree. C. and a compatibilizing agent for the fixing resin and the releasant, wherein a glass transition temperature Tg of the toner is from 53 to 63.degree. C. and the releasant having a particle diameter of 0.2 to 1.5 .mu.m is dispersed in the fixing resin. This toner is superior in blocking resistance, filming resistance and the like and is capable of fixing at a low temperature and, therefore, this toner is useful as a toner for image forming apparatus utilizing an electrophotographic process.

Toner

The present invention provides an electrophotographic toner containing, as a fixing resin, a styrene-acrylic copolymer in which styrene content, molecular-weight distribution and acid value are specified. The electrophotographic toner of the present invention is improved in heat resistance by raising the glass transition temperature of the fixing resin, while assuring excellent low-temperature fixing properties and resistance to off-set.

Electrophotographic toner

The present invention provides an electrophotographic toner having rheology characteristics, under the conditions of measuring frequency of 1 Hz and measuring distortion of 1 degree, such that:

Electrophotographic toner having improved low temperature fixing

The present invention provides an electrophotographic toner containing, as a fixing resin, a styrene-acrylic copolymer in which styrene content and molecular-weight distribution are specified, and which contains a specific high-molecular-weight component. The electrophotographic toner of the present invention is improved in bending resistance while assuring excellent low-temperature fixing properties, resistance to off-set and heat resistance.

Disclosed is a one-component magnetic developer for the electrophotography, which comprises one-component magnetic toner particles and at least one fine particulate additive selected from the group consisting of hydrophobic silica, hydrophilic silica and alumina, wherein the one-component magnetic toner particles have a sphericity degree (DS), defined by the following formula, of 70 to 90%, and a specific surface area of 1.4 to 2.0 m.sup.2 /g:

Magnetic developer for electrophotography

Disclosed is a toner for the electrophotography, which comprises as a main component a styrene/acrylic copolymer having at least two molecular weight distribution peaks, the molecular weight (Mw) of the peak on the lowest molecular weight side being lower than 13000, wherein the toner contains a charge controlling agent dispersed therein at a concentration of at least 0.3% by weight and the charge controlling agent has such a particle size distribution that the area ratio of particles having a particle size larger than 2.5 .mu.m is at least 80% based on the section of the toner. If this toner is used, the fixing-possible temperature can be broadened while increasing the fixing ratio without reduction of the performances of the toner.

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Hirakata, Japan

Hidenori Asada