Ricoh Company, Ltd.

Kohsuke Suzuki

Satoshi Mochizuki

Masahide Yamashita

Yasuo Asahina

Tomio Kondou

Minoru Masuda

Hideki Sugiura

Kazuhiko Umemura

Tomomi Tamura

Yohichiroh Watanabe

Tomomi Suzuki

Keiko Shiraishi

Noboru Kuroda

Hiroshi Yamashita

Hitoshi Iwatsuki

Shinichiro Yagi

Shinichi Kuramoto

Kumi Hasegawa

Masato Igarashi

Takayuki Koike

Nobutaka Kinoshita

Tomio Kondoh

A carrier containing a core material and a resin coating layer located overlying the surface of the core material. The resin coating layer contains resin and electroconductive particles having an oil absorption amount of from 10 to 300 ml/100 g. The electroconductive particle contains a base material particle and an electroconductive coating layer located overlying the surface of the base material particle. The electroconductive coating layer contains an underlayer containing tin dioxide and an upper layer containing indium oxide and tin dioxide, located overlying the underlayer.

Carrier, developer, image forming method and process cartridge for electrostatic image development

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

A carrier including a magnetic core material and a layer located on a surface of the magnetic core material, wherein the carrier satisfies the following relationships (1) to (3): 0.90&#x2266;(&#x3c3;a/&#x3c3;b)&#x3c;1.00 (1); 200&#x2266;(&#x3c3;b&#xb7;&#x3c1;c)&#x2266;400 (2); 10&#x2266;(&#x3c3;b/&#x3c1;c)&#x2266;20 (3), wherein &#x3c3;b represents a magnetization of the carrier at 1,000 Oe, &#x3c3;a represents a magnetization of the carrier after frictionized with a cylindrical sleeve under a specific condition and &#x3c1;c represents a true specific gravity of the carrier, wherein the carrier has a weight-average particle diameter of about 25 to about 65 &#x3bc;m and includes carrier particles having a weight-average particle diameter not greater than about 12 &#x3bc;m in an amount of not greater than about 0.3% by weight, wherein a ratio between the weight-average particle diameter and a number-average particle diameter of the carrier is about 1 to about 1.3, and wherein an electric resistance is from about 1.0&#xd7;10to about 1.0&#xd7;10&#x3a9;&#xb7;cm when an AC voltage represented by the following formula (4) is applied at a frequency of 1,000 Hz to a magnetic brush of the carrier is formed between parallel plate electrodes having a gap of d mm such that magnetic brush has a space occupancy of 40%: E(V)=250&#xd7;d (4), wherein d is 0.40&#xb1;0.05 mm and E is a peak voltage.

Carrier, developer including the carrier, and image forming apparatus using the developer

Carrier, developer including the carrier and image forming apparatus using the developer

A carrier including a manganese ferrite core material having a layer on its surface such that 0.1&#x2266;K&#x2266;30, where K=(S/M)&#xd7;100, S and M represent the standard deviation and average of M(M+M), respectively, M ranging from 0.05 to 0.45, and Mand Mrepresent the content of iron and manganese, respectively, in a carrier particle. The carrier has a magnetization ranging from 45 to 75 emu/g at 1,000 Oe, a mass-averaged particle diameter, D, ranging from 25 to 65 &#x3bc;m and carrier particles having a particle diameter not greater than 12 &#x3bc;m are included in an amount not greater than 0.3% by weight, and a ratio, DD, ranging from 1 to 1.3, where Dis a number-averaged particle diameter of the carrier.

Carrier, developer, image forming apparatus and process cartridge

A dry toner for developing electrostatic images, including a colorant and a binder resin which comprises a copolymer resin having (A) a polyol resin moiety having a main chain of polyoxyalkylene and obtained by reaction of (a) an epoxy resin, (b) a dihydric phenol, and (c) an alkylene oxide adduct of a dihydric phenol or a glycidyl ether thereof; and (B) a polyester resin moiety obtained by reacting an alkylene oxide adduct of a dihydric phenol or a glycidyl ether thereof with a polycarboxylic acid, wherein the weight ratio of the epoxy resin of the polyol resin moiety (A) to the polyester resin moiety (B) is 95:5 to 60:40, wherein the epoxy resin includes at least two kinds of bisphenol epoxy resins having different number-average molecular weights, and wherein the binder resin has an acid value of not greater than 5.

Dry toner for developing electrostatic images

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

A carrier for electrophotographic developer, including a core material and a resin layer formed on the surface of the core material, wherein the resin layer has a plastic deformation degree not less than 0.5 &mgr;m and an elastic deformation degree not less than 0.5 &mgr;m. The resin layer is preferably prepared by crosslinking a mixture including an acrylic resin having a reactive hydroxyl group and at least one of a perfectly-alkylated melamine compound and a perfectly-alkylated guanamine compound.

Carrier for electrophotographic developer, method for manufacturing the carrier, and coating liquid for the method

An electrophotographic toner including a colorant and a binder resin including at least a styrene resin, wherein the toner further includes one or more styrene oligomers in an amount not greater than 100 ppm. An electrophotographic image forming method is also disclosed in which an electrostatic latent image formed on an image bearing member is developed with the toner.

Electrophotographic toner and image forming method using the toner

A multi-color toner set includes a plurality of color toners with different colors, each color toner including toner particles, each toner particle including a binder resin, a pigment and a releasing agent, at least part of the releasing agent being present in the form of domains in the binder resin, with a difference between a maximum content and a minimum content of the releasing agent in the form of domains in the binder resin in each of the color toners being in a range of 20% or less. Multi-color images can be formed, using this multi-color toner set.

Multi-color toner set and method of forming multi-color images, using the multi-color toner set

A toner for developing electrostatic latent images which includes at least a binder resin, a colorant and a releasing agent, wherein the releasing agent includes a particulate material capable of absorbing the releasing agent. The particulate material preferably has an absorption rate not less than about 10% by weight in a combination with the releasing agent.

Growing community of inventors

Numazu, Japan

Kohsuke Suzuki