Mita Industrial Co., Ltd.

Kyocera Document Solutions Inc.

Kyocera Mita Corporation

Naruo Yabe

Yoshitake Shimizu

Masahide Inoue

Tetsuya Nakano

Koichi Tsuyama

Teruaki Teratani

Takeo Mizobe

Seijiro Ishimaru

Mitsushi Kuroki

Ryota Kobayashi

Takeshi Arakawa

Masanori Sugahara

Akihiro Watanabe

Yoshihisa Kuramae

Yoshio Ozawa

Masami Tsujihiro

Toyotsune Inoue

Norio Kubo

Masahiko Kubo

Ryotaro Komada

Kazuo Fuji

Akira Nakakuma

Noriaki Tsubota

Kazuhisa Edahiro

Hiroshi Shimoyama

Kouzou Teramoto

Toshiro Okae

Takuya Kadota

Tsutomu Uezono

Kazuki Ono

Mikiko Tamori

Kouichi Tsuyama

Toshio Nishio

Seijirou Ishimaru

A toner includes toner particles. The toner particles each include a toner mother particle containing a binder resin and an external additive attached to a surface of the toner mother particle. The external additive includes fluorine-containing particles. The fluorine-containing particles include a fluorine atom at least in surface layers thereof. The amount of the fluorine-containing particles is at least 0.10 parts by mass and no greater than 0.50 parts by mass relative to 100 parts by mass of the toner mother particles. When ultrasonication is performed, a residual amount ratio of remaining fluorine-containing particles is at least 0% by mass and no greater than 20% by mass relative to the amount of the fluorine-containing particles attached to the toner mother particles before the ultrasonication.

Toner, image forming apparatus, and image formation method

A toner includes toner particles. The toner particles each include a toner mother particle and an external additive attached to the surface of the toner mother particle. The external additive includes specific external additive particles. The specific external additive particles have a number average primary particle diameter of at least 30 nm and no greater than 305 nm. The specific external additive particles include antimony-doped tin oxide particles or indium tin oxide particles. A ratio (M/(M+M)) of a mass (M) of an antimony atom to a total of the mass (M) of the antimony atom and a mass (M) of a tin atom in the antimony-doped tin oxide particles is at least 0.04 and no greater than 0.46.

Toner

A toner contains toner particles. The toner particles each include a toner mother particle containing a binder resin and an external additive attached to a surface of the toner mother particle. The external additive contains titanate compound particles doped with lanthanum and a group 5 element in the periodic table as external additive particles. The amount of the lanthanum is at least 1.50% by mass relative to the total mass of the titanate compound particles. The amount of the group 5 element in the periodic table is at least 0.01% by mass and no greater than 0.60% by mass relative to the total mass of the titanate compound particles.

An electrostatic latent image developing toner contains toner particles each including a toner core containing a binder resin, and a shell layer coating the surface of the tore core. The shell layer contains a unit derived from a monomer of a thermosetting resin, and a unit derived from a thermoplastic resin. The resin contained in the shell layer has a unit derived from one or more monomers of thermosetting resins selected from the group of amino resins consisting of a melamine resin, a urea resin, and a glyoxal resin.

Electrostatic latent image developing toner

A two-component developing agent retained on the periphery surface of a magnetic rollerand a development rollerare brought in contact with each other, the nonmagnetic toner in the two-component developing agent is electrostatically adhered to the periphery surface of the development roller, and the nonmagnetic toner on the development rolleris sprayed on the periphery surface of a photosensitive drum, thereby causing an image of an electrostatic latent image to appear on the photosensitive drumas a toner image. The two-component developing agent for an image forming device thus configured comprises a nonmagnetic toner comprising color particles, and a magnetic carrier, wherein the magnetic carrier has a resin coating layer on the magnetic particle surface, and the critical surface tension of this resin coating layer is 25 dyn/cm or less.

Two component developing agent

A two-component binder-type magnetic carrier for developing agent comprising a magnetic powder and a binder resin. The carrier particles contain dispersed therein a release agent of the type of a metal soap and have abrasive or collapsible surfaces. By using the developing agent which contains this carrier, the magnetic powder peels off the carrier particle surfaces maintaining a controlled particle diameter and amount. Therefore, the carrier particles possess fresh surfaces at all times, whereby the occurrence of spent toner is effectively prevented and the charging amount of the toner is stably maintained.

Magnetic carrier for electrophotographic developing agent

The developer in accordance with the present invention includes toner, and a carrier having a core material the surface of which is coated with a coating layer made of a polymer, the coating layer having a resistance value sufficient to minimize the counter electric charge remaining in the coating layer, and the toner having any of characteristic values required for preventing a counter electric charge remaining in the coating layer from being increased. The use of the developer of the present invention not only prevents the occurrence of so-called carrier scattering, to thereby prevent blanking, but also produces an image of high quality having a high initial image density.

Two-component developer

A two-component developer comprising a magnetic carrier having a carbon black-containing resin-coating layer and a toner composed of a carbon black-containing resin composition is disclosed. A styrene resin, an acrylic resin or a styrene-acrylic copolymer resin is selected as each of the carrier-coating resin and the toner-forming resin, and the carbon black content A in the carrier-coating layer and the carbon black content B in the toner-forming layer satisfy requirements represented by the following formulae: ##STR1## Namely, by adjusting the carbon black contents A and B within specific ranges relatively to each other, a two-component developer which is well-balanced between the frictional chargeability characteristic and the electric resistance is provided.

The present invention provides a magnetic brush developing method using a two-component developer, characterized in that the development is carried out under such conditions that at the position where the sliding contact of the magnetic brush with the surface of the photosensitive material drum terminates, the following requirement is satisfied:

Magnetic brush development process

A toner composition comprising a binder resin having dispersed therein additives including a colorant and a charge control agent, wherein said additives are present as agglomerates having an average sectional area of from 1.4 to 1.7 .mu.m.sup.2 in a section of toner particles, the total sectional area of the agglomerates in the section of toner particles ranging from 1.5 to 1.8%, or wherein said colorant and charge control agent are present as agglomerates having an average sectional area of from 1.4 to 1.7 .mu.m.sup.2 in a section of toner particles, and said composition has such rheological characteristics that a dissipation factor (tan .delta.) is from 0.95 to 1.25 when a storage elastic modulus (G') is 10.sup.4 dyne/cm.sup.2.

Toner composition

In an electrophotographic toner, by using as the binder resin a styrene/acrylic resin in which in the gel permeation chromatogram, a high molecular weight peak value appears in a molecular weight region higher than 1.times.10.sup.5, a low molecular weight peak value appears in a molecular weight region of from 2.times.10.sup.4 to 500, a minimum value appears halfways between the two peaks and the ratio (V/P) of the area of the valley to the peak area is lower than 0.3, the internal cohesive force of the binder resin for the toner can be prominently improved while maintaining the low-temperature fixing property and offset resistance at high levels, and pulverization of the toner and formation of the spent toner can be prevented during the developing operation and the durability of the toner can be improved.

Electrophotographic toner

The present invention provides an electrophotographic developer comprising (i) a toner containing a fixing resin in which the content of an acrylic component is limited to a predetermined range, or a toner of which surface dye density is limited to a predetermined range, and (ii) a carrier coated with a coating resin containing, as an acrylic component, dodecyl methacrylate or 2-hydroxyethyl acrylate. In the electrophotographic developer of the present invention, the electric charging characteristics are always stable.

Electrophotographic developer comprising resin coated carrier

The present invention provides an electrophotographic developer comprising (i) a toner containing, as a fixing resin, a styrene-acrylic copolymer presenting a gel permeation chromatogram showing a molecular-weight distribution in which the detection-starting molecular weight and the detection-ending molecular weight are respectively located in specific ranges, and (ii) a carrier coated with a coating resin which is a styrene-acrylic copolymer containing at least 2-hydroxyethyl acrylate. Even though repeatedly agitated in the developing device, the electrophotographic developer of the present invention is not deteriorated and assures good durability and long life-time.

Electrophotographic developer

A start developer is described which includes a toner and a carrier, present in a predetermined ratio. The carrier spent amount is adjusted so that it is not less than 0.010% in terms of the amount of carbon, as measured with a carbon analyzer. With this start developer, good quality images may be formed throughout the copying operation, from the initial image forming stage to the repeated image forming stage and through the stabilized image forming stage.

Start developer

A two-component developer for use in dry development of electrostatic charge pattern, comprising a mixture of magnetic carrier particles and electroscopic toner particles, characterized in that said magnetic carrier particles have a relaxation time B (msec) satisfying the equation 0&lt;B&lt;20 when they are situated in a dynamic state and said developer has a relaxation time A (msec) satisfying the equation: 0.35B+11&lt;A&lt;0.35B+14 when it is situated in a dynamic state.

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Kobe, Japan

Naruo Yabe