Konica Corporation

Tomoyasu Umeno

Tatsuya Nagase

Meizo Shirose

Ryuji Kitani

Ken Ohmura

Shigenori Kouno

A carrier for developing an electrostatic latent image is disclosed. The carrier comprises a magnetite core and a resin coated on the magnetite core wherein the magnetite core contains FeO and Fe.sub.2 O.sub.3, the mole ratio of FeO/Fe.sub.2 O.sub.3 being 0.15/1.0 to 0.7/1.0, and the carrier contains a magnesium atom containing material at a surface of the carrier, magnesium atom content ratio at the surface being 1.5 to 5.0 (percent in the number of atoms). A developer for developing an electrostatic latent image using the carrier and a developing method using the carrier or the developer is also disclosed.

Carrier for developing electrostatic image, developer and developing

A carrier for a developer developing an electrostatic image is disclosed. The carrier contains magnesium from 2.0 to 25.0 by means of number of atoms by percent in surface portion. According to the invention excellent charge rising properties may be consistently exhibited for extended time periods, and neither toner scattering nor background deposits on images are caused.

Disclosed is a toner kit for an electrophotography, comprising a black toner and a first toner whose color is other than black, wherein said first toner has a first softening point T.sub.1, said first toner comprises a first releasing agent, a first intermolecular crosslinked polyester resin having a second softening point T.sub.2 of 100.degree. C. to 150.degree. C., obtained by a reaction of an alcohol having at least two hydroxyl group and an aromatic carboxylic acid having at least two carboxyl group and a processed pigment having a third softening point T.sub.3 of 100.degree. C. to 150.degree. C., said processed pigment comprising a pigment and a resin in which said pigment is dispersed, and said resin forms domain structure in said first polyester resin, and

Toner kit for electrophotography

A carrier of developer for developing an electrostatic image and a method for producing the carrier are disclosed. The carrier comprises core particles each having a resin layer covering the surface of said core particle. The resin layer is formed by dry process in which the core particles are stirred together with fine resin particles with no solvent for the resin to form the resin layer on the surface of each core particle. The fine resin particles comprise a homopolymer or a copolymer comprising a fluorinated acrylate repeating unit and are formed by emulsified polymerization carried out in the presence of a surfactant comprising an alkylbenzene sulfonic compound, and the residual amount of the surfactant in the fine resin particles is within the range of from 60 ppm to 10,000 ppm. The carrier is improved in adhesion between the surface of the core and the resin layer and satisfactory in friction electricity providing capability.

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Hachioji, Japan

Tomoyasu Umeno