Powdertech Co., Ltd.

Panasonic Corporation

Tetsuya Uemura

Hiroki Sawamoto

Makoto Ishikawa

Toshio Honjo

Aya Sakuta

Yuji Sato

Hiromichi Kobayashi

Yasuhito Yuasa

Takao Sugiura

Kanao Kayamoto

Takeshi Naito

Masashi Aoki

Hajime Akiba

Yasuhiko Kataoka

Yuzuru Yamasaki

Kiminori Umeda

Tsuyoshi Itagoshi

Shinichi Matsuda

Tomoaki Kobayashi

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite-type crystal represented by a composition formula of RZrO3 (wherein R is an alkaline earth metal element), and a Mg content of 0.45 mass % or less. The present invention also relates to a carrier core material for an electrophotographic developer, containing the ferrite particle; a carrier for an electrophotographic developer, containing the ferrite particle and a resin coating layer provided on a surface of the ferrite particle; and an electrophotographic developer containing the carrier for an electrophotographic developer and a toner.

Ferrite particle, carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO(provided that R represents an alkaline earth metal element), having a surface roughness Rz of 0.8 μm or more and 3.5 μm or less, and having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula 0.15×Rz≤Rzσ≤0.60×Rz. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

Ferrite particles, electrophotographic developer carrier core material, electrophotographic developer carrier, and electrophotographic developer

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO(provided that R represents an alkaline earth metal element), having a surface roughness Rz of 2.0 μm or more and 4.5 μm or less, and satisfying the following formulas: 6.5≤log H≤8.5 and 0.80≤log H/log H≤1.00. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

The present invention provides: a ferrite particle containing a crystal phase component containing a perovskite crystal represented by the compositional formula RZrO(where R is an alkaline earth metal element); and an electrophotographic developer carrier core material, an electrophotographic developer carrier, and an electrophotographic developer containing the ferrite particles.

The present invention relates to a ferrite particle, containing a crystal phase component containing a perovskite crystal represented by the compositional formula: RZrO(provided that R represents an alkaline earth metal element), and having an apparent density in a range represented by the following formula:1.90≤≤2.45provided that Y in the formula is the apparent density (g/cm) of the ferrite particle.

The present invention relates to a carrier including: a magnetic core material; and a resin coating layer coating a surface of the magnetic core material, in which the resin coating layer contains a binder resin, and fluorine element-containing resin particles dispersed in the binder resin, the resin coating layer has a coefficient of variation of a film thickness of 25% or less, and the resin coating layer has an average value of the number of the fluorine element-containing resin particles being 3 particles/μmor more and 350 particles/μmor less per unit area in a cross section of the resin coating layer, and has a coefficient of variation thereof being 20% or less.

Carrier, xerographic developer, and carrier production method

The present invention provides: a ferrite carrier core material for an electrophotographic developer, the material having a mesh passing amount of 3 wt % or less as indicated by the ratio of the weight of particles passing through a 16 &#x3bc;m-mesh to the weight of whole particles constituting a powder, and having a particle strength index of 2 wt % or less as indicated by a difference between the mesh passing amounts before and after crushing; a ferrite carrier which is for an electrophotographic developer and in which the surface of the ferrite carrier core material is coated with a resin; and an electrophotographic developer which includes the ferrite carrier and a toner.

Ferrite carrier core material for electrophotographic developer, ferrite carrier, manufacturing method thereof, and electrophotographic developer using said ferrite

Provided are a ferrite carrier core material for an electrophotographic developer having a full length Lof grain boundary and a circumference length Lof the core material in a cross-section of the core material, and satisfying a relationship of 2&#x2264;L/L&#x2264;9; a carrier for an electrophotographic developer including the ferrite carrier core material and a coating layer containing a resin provided on a surface of the ferrite carrier core material; and an electrophotographic developer including the carrier and a toner.

Ferrite carrier core material for electrophotographic developer, carrier for electrophotographic developer, and developer

To provide a magnetic core material and carrier for electrophotographic developer, which have small environmental dependence of the electric resistance, can suppress the carrier scattering, and can stably provide good images; a developer contains the carrier; and methods for producing them. The magnetic core material satisfying a value of Formula (1): a+b&#xd7;10+c+d+e+f, being from 20 to 150, when a fluoride ion amount is denoted by a (ppm), a chloride ion amount is denoted by b (ppm), a bromide ion amount is denoted by c (ppm), a nitrite ion amount is denoted by d (ppm), a nitrate ion amount is denoted by e (ppm), and a sulfate ion amount is denoted by f (ppm), which are measured by a combustion ion chromatography method.

Magnetic core material for electrophotographic developer, carrier for electrophotographic developer, developer, method for producing magnetic core material for electrophotographic developer, method for producing carrier for electrophotographic developer, and method for producing developer

There is provided a carrier including a magnetic core material having a surface coated with a surfactant-containing resin mixture of an elemental fluorine-containing resin and a polyimide resin. The carrier has an elution amount of an eluted material into water in an elution test ranging from 180 ppm to 3,500 ppm.

Carrier, electrophotographic developer and production method of carrier

A magnetic core material for electrophotographic developer, satisfying a value of Expression (1): a+b&#xd7;10+c+d+e+f, being from 200 to 1,400, when an amount of fluorine ion is denoted by a (ppm), an amount of chlorine ion is denoted by b (ppm), an amount of bromide ion is denoted by c (ppm), an amount of nitrite ion is denoted by d (ppm), an amount of nitrate ion is denoted by e (ppm), and an amount of sulfate ion is denoted by f (ppm), which are measured by combustion ion chromatography; and having a pore volume of from 30 to 100 mm/g.

Magnetic core material for electrophotographic developer, carrier for electrophotographic developer, and developer

Provided are a magnetic core material for electrophotographic developer and a carrier for electrophotographic developer, which are excellent in charge characteristics and strength and with which a satisfactory image free from defects can be obtained, and a developer containing the carrier. A magnetic core material for electrophotographic developer, having a sulfur component content of from 50 to 700 ppm in terms of a sulfate ion and a BET specific surface area of from 0.06 to 0.25 m/g.

Provided are a magnetic core material for electrophotographic developer and a carrier for electrophotographic developer, which are excellent in charging characteristics and strength with low specific gravity and with which a satisfactory image free of defects can be obtained, and a developer containing the carrier. A magnetic core material for electrophotographic developer, having a sulfur component content of from 60 to 800 ppm in terms of a sulfate ion and a pore volume of from 30 to 100 mm/g.

A magnetic core material for electrophotographic developer, satisfying a value of Expression (1): a+b&#xd7;10+c+d+e+f, being from 300 to 1,300, when an amount of fluorine ion is denoted by a (ppm), an amount of chlorine ion is denoted by b (ppm), an amount of bromide ion is denoted by c (ppm), an amount of nitrite ion is denoted by d (ppm), an amount of nitrate ion is denoted by e (ppm), and an amount of sulfate ion is denoted by f (ppm), which are measured by combustion ion chromatography, and having a BET specific surface area being from 0.06 to 0.25 m/g.

An object of the present invention is to provide a carrier low in specific gravity and less in both environmental fluctuation and change of the charge amount after aging, an electrophotographic developer using the carrier, and a method of manufacturing the carrier. To achieve the object, the carrier is manufactured by coating a core material composed of a magnetic component and a non-magnetic component with a resin, and the carrier is characterized in that water content is 200 ppm or less and cyclic siloxane content is 100 ppb or less. Further, an electrophotographic developer containing the carrier is provided.

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Kashiwa, Japan

Tetsuya Uemura