Powdertech Co., Ltd.

Other

Mitsui Minings & Melting Co., Ltd.

Minolta Camera Kabushiki Kaisha

Yuji Sato

Hiromichi Kobayashi

Toshio Honjo

Tsuyoshi Itagoshi

Kanao Kayamoto

Issei Shinmura

Masahiro Ogata

Kazunori Takagi

Yoichi Kamikoriyama

Kenji Suzuoka

Kazuya Kinoshita

Takeshi Gondo

Takeshi Naito

Takashi Nakashima

Takashi Hikichi

Yasuhiko Kataoka

Toshiyuki Fukumoto

Kouichi Shimizu

Norio Takei

Yasushige Nakamura

Yoshimichi Katagiri

Ichiro Demizu

Tetsuya Uemura

Seijiro Ishimaru

Yukio Tanigami

Yuji Shintani

Etsuaki Urano

Shinobu Nakasawa

Shinichi Matsuda

Osamu Doi

Kazuhiro Itadaki

Miyoko Ito

Nobutaka Torii

Yoshifumi Imamura

A carrier core material containing at least one metal oxide (MO) having a melting point of not higher than 1000&#xb0; C. and at least one metal oxide (MO) having a melting point of not lower than 1800&#xb0; C., wherein the metal (M) for constituting the metal oxide (MO) has an electrical resistivity of not less than 10&#x3a9;&#xb7;cm. Also disclosed is a two-component developing agent comprising a coated carrier, which comprises the carrier core material coated with a resin, and toner particles. Further disclosed is an image forming method comprising developing an electrostatic latent image formed on a photosensitive member with the two-component developing agent using an alternating electric field. The carrier core material and the coated carrier have high magnetization and are free from occurrence of leakage of electric charge over a wide range of electric field from low electric field to high electric field. According to the two-component developing agent, an excellent image can be formed.

Carrier core material, coated carrier, and two-component developing agent for electrophotography

A carrier for electrophotographic developer comprises a resin carrier core comprising a binder resin and magnetic powder dispersed in the binder resin, and a coating layer comprising a coating resin on a surface of the core, the binder resin being a silicone resin obtained by curing of a polysiloxane compound (A) having an epoxy group and a polysiloxane compound (B) having a group capable of reacting with the epoxy group, due to a ring-opening addition reaction; the binder resin containing a functional group which is an epoxy group and/or a group capable of reacting with an epoxy group; the coating resin containing a functional group capable of reacting with the functional group of the binder resin; the functional group of the coating resin and the function group of the binder resin forming a chemical bond.

Carrier for electrophotographic developer and two-component electrophotographic developer

Provided are a carrier for electrophotography developers prepared by generating a slight amount of byproducts such as water, alcohol, etc, which carrier is free from release of a magnetic powder, has excellent mechanical strength and durability, and good environmental stability, and further can restrain occurrence of toner spent condition and has favorable fluidity and excellent capability of imparting charging to a toner, a two-component developer comprising the carrier and a method for forming an image using the developer. The carrier for electrophotography developers comprises a magnetic powder dispersed binder resin, the binder resin material comprises (A) a polysiloxane compound having an epoxy group as a functional group and (B) a polysiloxane compound having a group capable of ring-opening addition reaction with the epoxy group of the polysiloxane compound (A), and the binder resin is a silicone resin prepared by curing with ring-opening addition reaction of the epoxy resin. The developer comprises the carrier for electrophotography developers and the toner particle. The method for forming an image comprises developing a static latent image by the developer with an alternating electric field.

Carrier for electrophotography developers, developer prepared by using the carrier and method for forming image

A carrier core material for an electrophotographic developing agent, which comprises 100 parts by weight of a ferrite component represented by a formula (A) and 0.1 to 5.0 parts by weight of ZrOthat is present in the ferrite component without forming a solid solution, and which has a magnetization, at 1000(10/4&#x3c0;&#xb7;A/m), of 65 to 85 Am/kg and an electrical resistance, at an applied voltage of 1000 V, of 10to 10&#x3a9;.(MnO)(MgO)(FeO)&#x2003;&#x2003;(A)wherein x, y and z are each expressed in % by mol and are numbers satisfying the conditions of 40&#x2266;x&#x2266;60, 0.1&#x2266;y&#x2266;10 and x+y+z=100. Also disclosed is a two-component developing agent comprising a coated carrier, which is obtained by coating the above carrier core material with a resin, and toner particles. Further disclosed is an image forming method comprising developing an electrostatic latent image formed by the use of an alternating electric field, with the two-component developing agent. The carrier core material and the coated carrier have high magnetization and high resistance. According to the two-component developing agent of the invention, an excellent image can be formed.

Carrier core material, coated carrier, two-component developing agent for electrophotography, and image forming method

A resin-coated carrier for an electrophotographic developer and a process of producing the carrier. The carrier comprises a ferrite core mainly comprising iron oxide, primarily having a spinel structure, and having a volume average particle size of 20 to 45 &#x3bc;m and a resin coat, wherein the carrier has a magnetization of 65 to 80 emu/g in a magnetic field of 1 KOe, the core has an electric current value of 50 to 150 &#x3bc;A and a surface smoothness uniformity of 75% or higher, and the amount of the resin coat is 0.1 to 5.0% by weight based on the core.

Carrier for electrophotographic developer and process of producing the same

A dry two-component developer for electrophotography comprising a carrier particle and a toner particle, wherein a toner water adsorption ratio (T) obtained by a following equation (1) for the toner particle ranges from 1.0 to 7.0 and a carrier water adsorption ratio (C) obtained by a following equation (2) is 20.0 or less, and a water adsorption ratio (T/C) expressed in a following equation (3) representing a relationship between the toner water adsorption ratio (T) and the carrier water adsorption ratio (C) is 5.0 or less;

Dry two-component type developer for electrophotography

A resin-coated carrier to be mixed with a polymer toner obtained by suspension polymerization or emulsion polymerization to provide an electrophotographic developer, which exposes 2 to 20% of the surface area of the core thereof, the average exposed area ratio per exposed part of the core being 0.03% or less.

Carrier for electrophotographic developer and developer containing the same

A carrier for an electrophotographic developer comprising spherical magnetic core particles which have a volume average particle size of 25 to 45 &mgr;m, an average void size of 10 to 20 &mgr;m, a volume based particle size distribution having less than 1% of 22 &mgr;m or smaller particles, a magnetization of 67 to 88 emu/g in a magnetic field of 1 kOe, and a difference of 10 emu/g or smaller in magnetization in a magnetic field of 1 kOe between scattered particles and remaining particles.

Carrier for electrophotographic developer and electrophotographic developer containing the same

There is disclosed a two-component developing agent for use in an mage formation based on electrophotography, which has high developability even at a high speed printing and good developability in the case of the image formation for a long period of time. The two-component developing agent includes a carrier comprising a magnetic particle and an insulating toner. A surface of the magnetic particle is coated with at least a resin. A mean particle size of the magnetic particle is between 30 and 90 &mgr;m and an aggregation degree of said carrier is between 2 and 15%.

Two component developing agent and an image forming apparatus by use of the same

A carrier for an electrophotographic developer which comprises a carrier core and a resin coat having a conducting agent dispersed therein, the resin coat having an inner layer on the carrier core side and an outer layer coating the inner layer, wherein the inner layer contains 7 to 20% by weight of a conducting agent based on the resinous solid content of the inner layer, the outer layer contains 3 to 15% by weight of a conducting agent based on the resinous solid content of the outer layer, and the conducting agent content of the inner layer is greater than that of the outer layer.

A carrier for an electrophotographic developer which is coated with an insulating resin containing a white conducting agent, wherein the white conducting agent includes spherical to lumpy particles of TiO,ZnO,or SnO,having two or more average particle sizes, the particles having thereon a 5 to 50 &angst; thick conducting layer of SnO,having a group V metal or phosphorus in solid solution therein.

A carrier for an electrophotographic developer comprising a carrier core coated with a silicone resin containing a quaternary ammonium salt as a catalyst.

Carrier for electrophotographic development and electrophotographic

A carrier for an electrophotographic developer comprising a carrier core coated with a silicone resin containing a crosslinking agent having a phenyl group.

A ferrite carrier for electrophotographic developers which is represented by formula:

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Kashiwa, Japan

Yuji Sato