Ricoh Company, Ltd.

Tomomi Tamura

Satoshi Mochizuki

Minoru Masuda

Hideki Sugiura

Yasuo Asahina

Kazuhiko Umemura

Hiroaki Matsuda

Tatsuya Niimi

Shinichiro Yagi

Naohito Shimota

Kohsuke Suzuki

Masahide Yamashita

Kousuke Suzuki

Yasuaki Iwamoto

Tomio Kondou

Takayuki Koike

A developer for developing an electrostatic latent image, including a carrier which includes core particles, and a surface layer surrounding each of the core particles and containing an acrylic resin binder; and a toner which includes toner particles and an external additive of inorganic or organic fine particles present on each of the toner particles. Each of the toner particles comprises a colorant, a matrix of a first resin, and a plurality of domains of a second resin dispersed in the matrix and containing a wax. The first resin is substantially free of tetrahydrofuran insoluble matters and has a weight average molecular weight of 3,000 to 90,000.

Developer for developing electrostatic latent image and image forming apparatus

The toner for developing a latent electrostatic image to form an image contains a binder resin and 2% by weight to 15% by weight of a coloring agent. The coverage of the toner with the coloring agent on a surface of the toner is 1.5% by atom to 15% by atom. The toner prevents scatterings and toner deposition on the background of images and provides high quality images even after printing several tens of sheets at high temperature and in high humidity.

Toner for developing a latent electrostatic image, developer using the same, full-color toner kit using the same, image-forming apparatus using the same, image-forming process cartridge using the same and image-forming process using the same

An image formation apparatus develops an electrostatic latent image with a two-component developer consisting of magnetic carriers and toners by using a development apparatus and a latent image supporter including a filler in an outermost layer thereof, the development apparatus having a developer supporter, which has an internally fixed magnetic body and rotates while supporting a developer on a surface thereof, and a developer quantity controller controlling a quantity of the developer which is supported by the developer supporter facing the magnetic body and controlling a height of magnetic brushes and consisting of materials having rigidity or rigidity and magnetic properties, wherein a ratio (Gp/Gd) of a development gap to a doctor gap between the developer supporter and the controller is from 0.7 to 1.0, and a weight-averaged particle diameter of a developer carrier is from 20 to 60 &#x3bc;m.

Image formation apparatus using a dry two-component developer for development

A method for forming an electrophotographic image and a device for forming an image on a transfer material by the steps for charging, exposing, developing and transferring, and recovering the toner remained untransferred in the step for cleaning by recovering, wherein the toner used in the step for developing has a total surface area ratio Z of additive, which is calculated by Z=(Ht&#xb7;Wt)/(H&#xb7;W), satisfies 0.5&#x2266;Z&#x2266;1.5, the electrophotographic photoconductor used comprises at least a photosensitive layer and a filler-containing protective layer provided on a conductive support in that order, and the angle of repose of the toner to the protective layer surface of the electrophotographic photoconductor is 30&#xb0; or less.

Method for forming electrophotographic image and electrographic device

A carrier for electrophotographic developer comprising carrier particles, each carrier particle having at least one surface-coating layer by resin material, wherein the surface-coating layer containing an acrylic resin and a silicone resin, the acrylic resin is in an amount ranging 10 to 90 wt. % based on the total amount of resin coating ingredients. The carrier shows no accumulation of toner-spents, therefore can obtain a stable electric charge, and has no layer scraping in binder resin layer, therefore can obtain a stable electric resistance, hence occurs no deterioration of images reproduced, by using acrylic resin having high anti-abrasive and high surface energy, whereas it has strong adhesiveness and high fragility, in combination use of silicone resin having poor anti-abrasive and small adhesiveness but has low fragility, thus is hard to cause a toner spent and hard to integrate the spent constituents due to its low surface energy.

Carrier for electrophotography and developer using the same

A toner for electrostatic image development in which the weight concentration of polar-solvent-soluble material is 1000 &mgr;g/g or less, based on the toner, and an image forming method comprising a step of forming a toner image by developing a latent electrostatic image by using the toner for electrostatic image development.

Toner for electrostatic image development and image forming method and apparatus using the toner

A toner including a binder resin, a colorant, and a product of an iron compound containing an aromatic hydroxylcarboxylic acid as a ligand and represented by the formula (I) described in the specification, wherein the product has such a characteristic that a filtrate obtained by filtering a dispersion of 10 g of the product dispersed in 200 ml of purified water provides an electric conductivity of not greater than 600 &mgr;S/cm.

Negatively chargeable toner

An image formation apparatus develops an electrostatic latent image with a two-component developer consisting of magnetic carriers and toners by using a development apparatus and a latent image supporter including a filler in an outermost layer thereof, the development apparatus having a developer supporter, which has an internally fixed magnetic body and rotates while supporting a developer on a surface thereof, and a developer quantity controller controlling a quantity of the developer which is supported by the developer supporter facing the magnetic body and controlling a height of magnetic brushes and consisting of materials having rigidity or rigidity and magnetic properties, wherein a ratio (Gp/Gd) of a development gap to a doctor gap between the developer supporter and the controller is from 0.7 to 1.0, and a weight-averaged particle diameter of a developer carrier is from 20 to 60 &mgr;m.

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Shizuoka, Japan

Tomomi Tamura