Ricoh Company, Ltd.

Rocoh Company, Ltd.

Kimitoshi Yamaguchi

Hitoshi Iwatsuki

Koichi Sakata

Toyoaki Tano

Minoru Masuda

Akihiro Kotsugai

Naoki Imahashi

Shigenori Yaguchi

Toyoshi Sawada

Yutaka Takahashi

Hiroshi Tohmatsu

Saori Yamada

Mariko Takii

Hiroaki Takahashi

Hisashi Nakajima

Masashi Nagayama

Hiroyuki Kishida

Toshiki Nanya

Hiromitsu Kawase

Masami Tomita

Satoru Inoue

Mitsuo Aoki

Chiaki Uematsu

Makoto Ookawara

Mitsuru Uchida

Masahide Yamashita

Kousuke Suzuki

Kazuhiko Umemura

Hiroshi Ikuno

Kazuo Tsubuko

Motoharu Tanaka

Hachiro Tosaka

Motoi Orihara

Toshihiko Takahashi

Yoichiro Watanabe

Yoshihiro Nomura

A carrier for use in a two component developer for developing an electrostatic latent image is provided. The carrier includes a particulate core material; and a cover layer located on a surface of the core material and including a silicone resin and barium sulfate. The cover layer includes Ba and Si at an atomic ratio of from 0.01 to 0.08 as determined by X-ray photoelectron spectroscopy.

Carrier, developer using the carrier, and developing device, image forming method, image forming apparatus and process cartridge using the developer

The developing method includes developing an electrostatic latent image on an image bearing member with a two-component developer including a toner and a carrier and born on at least one developer bearing member, whose surface moves at a linear speed of from 300 mm/sec to 2,000 mm/sec. The carrier includes a particulate core material; and a cover layer located on a surface of the core material and including a crosslinked material obtained by crosslinking a resin including a first unit having a specific tris(trialkylsiloxy) silyl group and a second unit having a specific alkoxysilyl group having a crosslinking ability. Each of the first unit and the second unit is included in the resin in a molar ratio of from 0.1 to 0.9 based on all the units included in the resin.

Developing method and image forming method

A carrier for developing an electrostatic latent image, including a particulate core material having a magnetism having developed spontaneous magnetization; and a covering layer comprising an electroconductive material, covering the surface of the particulate core material, wherein the carrier has an electrical resistivity Log R [&#x3a9;cm] of from 8.0 to 12.0 when measured by a method, including filling the carrier in a cell containing a pair of facing electrodes, each having a surface area of 2&#xd7;4 [cm] with a gap of 2 [mm] therebetween; and applying a DC voltage of 1,000 [V] therebetween to measure a DC resistivity, and a weight-average particle diameter (Dw) of from 25 to 45 &#x3bc;m.

Carrier for electrostatic latent image developer, electrostatic latent image developer formed of carrier and toner, and process cartridge using the developer

The present invention is to provide a carrier and a developer, which have fewer occurrences of carrier adhesion and background smear, excellent granularity and longer durability. The carrier comprises the core material particles having magnetism and resin coating layer covering the core material particles, and wherein the weight average particle diameters is in the range of 22 m to 32 m, the proportion of the weight average particle diameters relative to the number average particle diameter is in the range of 1.00 to 1.20, the content of particles having a diameter of 20 m or smaller is 7% by mass, the content of carrier particles having a diameter of 36 m or smaller is in the range of 90% by mass to 100% by mass, and the proportion of the particle density of the core material particles is in the range of 85% to 100% of the true density of the core material particles.

Carrier, developer, image forming method and process cartridge

An object of the present invention is to provide a carrier containing core material particles having magnetism and a coating layer on the surfaces of the core material particles, wherein the core material particles have a magnetization at a magnetic field of 1,000 Oersted of 40 emu/g to 100 emu/g, and the carrier has a weight average particle diameter of 20 &#x3bc;m to 45 &#x3bc;m, a resistance (Log R) of 11 &#x3a9;&#xb7;cm to 17 &#x3a9;&#xb7;cm and a relaxation time &#x3c4; of 150 seconds to 800 seconds.

Carrier, developer and electrophotographic developing method and image forming method

A latent electrostatic image developing carrier including: core particles each having magnetism; and a coating layer covering each of the core particles, wherein the latent electrostatic image developing carrier has a shape factor SF-2 of 115 to 150 and has a bulk density of 1.8 g/cmto 2.4 g/cm, wherein the core particles have a shape factor SF-2 of 120 to 160 and have an arithmetic mean surface roughness Ra of 0.5 &#x3bc;m to 1.0 &#x3bc;m, and wherein the coating layer contains a resin and a filler and an amount of the filler contained in the coating layer is 50 parts by mass to 500 parts by mass per 100 parts by mass of the resin contained in the coating layer.

Latent electrostatic image developing carrier, process cartridge and image forming apparatus

A carrier including a magnetic core particle and a resin layer covering a surface of the magnetic core particle. The magnetic core particle is a ferrite particle including strontium in an amount of 0.005 to 3% by mass, measured by fluorescent X-ray spectroscopy. The resin layer comprises a resin obtained by heating a copolymer comprising a silicon-containing unit A and another silicon-containing specific unit B.

Carrier, developer, method of manufacturing carrier, developer container, image forming method, process cartridge, image forming apparatus, and supplemental developer

A contact developing method including supplying a two-component developer to an electrostatic latent image on a rotating image bearing member by rotating a developing sleeve and a rotatable magnet having multiple magnetic poles provided inside the developing sleeve, to develop the electrostatic latent image into a toner image. The developing sleeve and the image bearing member rotate in the same direction while facing each other. The two-component developer comprises a non-magnetic toner and a carrier. The carrier comprises a magnetic core particle and a resin layer covering the magnetic core particle. The resin layer comprises a conductive particle and a resin. The conductive particle comprises an alumina-based material and a conductive layer covering the alumina-based material. The resin is obtained by heating a copolymer comprising a monomer A unit and a monomer B unit.

Contact developing method, image forming apparatus, and process cartridge

A carrier for developing electrostatic latent image, including a core material; and a coated layer covering the core material, including a binder resin and a particulate material, wherein the core material is exposed on the surface of the carrier at an areal ratio of from 0.1 to 5.0% and has the largest exposed part having an areal ratio not greater than 0.03%, and wherein the coated layer comprises the particulate material in an amount of from 100 to 500 parts by weight per 100 parts by weight of the binder resin.

Carrier for developing electrostatic latent image and developer

The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the particulate magnetic core material and including a crosslinked material. The crosslinked material is formed by hydrolyzing a copolymer including at least a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure to form a material having a silanol group, and subjecting the material having a silanol group to a condensation reaction using an organic zirconium-containing catalyst.

Carrier, method for preparing the carrier, developer using the carrier, developer container, and image forming method and apparatus and process cartridge using the developer

A carrier comprising a magnetic core particle having a shape factor SF-2 of 130 to 160 and a resin layer covering a surface of the magnetic core particle. The resin layer comprises a conductive particle and a resin obtained by heating a copolymer comprising a silicon-containing A unit and another silicon-containing B unit.

Carrier for developing electrostatic latent image, and two-component developer, supplemental developer, image forming apparatus, process cartridge, and image forming method using the carrier

A latent electrostatic image developing carrier including a carrier core material, and a coating layer containing a resin and provided on a surface of the carrier core material, wherein the coating layer includes a particulate material containing at least first fine conductive particles and second fine conductive particles, and wherein the first fine conductive particles and the second fine conductive particles satisfy the relationships expressed by Expressions 1 and 2, 3&#x2266;D1/D2&#x2266;15 . . . Expression 1, where D1 denotes a dispersed particle diameter of the first fine conductive particles and D2 denotes a dispersed particle diameter of the second fine conductive particles, and &#x2212;7E&#x2266;R1&#xd7;R2&#x2266;8E . . . Expression 2, where R1 denotes a powder specific resistance of the first fine conductive particles and R2 denotes a powder specific resistance of the second fine conductive particles.

Latent electrostatic image developing carrier, two-component developer and image forming method

A carrier, including a magnetic particulate core material and a resin layer on the core material, wherein the resin layer includes a resin obtained by heat treatment of a copolymer including a site derived from a monomer component having the following formula (1) and a site derived from a monomer component having the following formula (2), and includes a cross-linked material obtained by hydrolysis of the copolymer to produce a silanol group and condensation using an organotitanium compound: wherein Rrepresents a hydrogen atom or a methyl group; m represents an alkylene group having 1 to 8 carbon atoms; Rrepresents an alkyl group having 1 to 4 carbon atoms; Rrepresents an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; X represents 10 to 90 mol %; and Y represents 10 to 90 mol %.

Carrier for two-component developer

The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the core material and including a crosslinked material and barium sulfate. The cover layer is formed by applying a coating medium including barium sulfate, a copolymer including a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure having a crosslinking ability, and a condensation reaction catalyst, heating the applied medium to a temperature of from 100&#xb0; C. to 230&#xb0; C. so that the copolymer is hydrolyzed to produce a material having a silanol group, and the material and the catalyst are subjected to a condensation reaction to form the crosslinked material.

Carrier, method for preparing the carrier, developer using the carrier, developer container, and image forming method and process cartridge using the developer

The present invention provides a carrier which includes core material particles, and a coating layer on surfaces of the core material particles, wherein the coating layer contains a crosslinked product which is obtained by condensation of a silicone resin with an organic zirconium catalyst, the silicone resin having at least one of a silanol group and a functional group capable of generating a silanol group by means of hydrolysis.

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Shizuoka, Japan

Kimitoshi Yamaguchi