Powdertech Co., Ltd.

Other

Tsuyoshi Itagoshi

Hiromichi Kobayashi

Yuji Sato

Toshio Honjo

Tomoyuki Suwa

Issei Shinmura

Takeshi Naito

Yasushige Nakamura

Yoshimichi Katagiri

Seijiro Ishimaru

Kazunori Takagi

Yasuhiko Kataoka

Norio Takei

A ferrite core material for a resin-filled type carrier, and a resin-filled type carrier which is used as an electrophotographic developer by mixing a toner, sufficiently secure the image density, have no carrier adhesion and can maintain high-quality images over a long period, and an electrophotographic developer using the carrier, are provided. A ferrite core material for a resin-filled type carrier characterized in a void fraction of 10 to 60%, a resin-filled type carrier filled in the carrier core material with a resin, and an electrophotographic developer composed of the resin-filled type carrier and a toner, are provided.

Ferrite core material for resin-filled type carrier, resin-filled type carrier, and electrophotographic developer using the carrier

A ferrite carrier for an electrophotographic developer having a compression breaking strength of 150 MPa or more, a rate of compressive change of 15.0% or more and a shape factor SF-1 of 100 to 125, a method for producing the same, and an electrophotographic developer containing the ferrite carrier.

Ferrite carrier for electrophotographic developer, method for producing the same, and electrophotographic developer

A carrier for an electrophotographic developer which is used as an electrophotographic developer in a mixture with a toner and which secures sufficiently the image density and can maintain high-quality images for a long period, and an electrophotographic developer using the carrier, are provided. A resin-filled ferrite carrier for electrophotographic developer obtained by filling, with a resin, avoid of a porous ferrite core whose void continues from the surface to reach the interior of the core, the carrier comprising a plurality of three-dimensional laminate structures in which resin layers and ferrite layers are alternately present, and an electrophotographic developer including the carrier and a toner, are employed.

Carrier for electrophotographic developer, and electrophotographic developer using the same

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 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 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

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 ferrite carrier for electrophotographic developers which is represented by formula:

Ferrite carrier for electrophotographic developer and

A method for regenerating a carrier coated with a silicone resin or a resin containing a silane coupling agent in an electrophotographic developer comprising the carrier and a toner, which comprises separating the developer into the carrier and the toner, immersing the separated carrier in an aqueous alkali solution, and stirring the mixture to remove the toner component adhered to the carrier surface and the coating resin.

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Kashiwa, Japan

Tsuyoshi Itagoshi