Sharp Kabushiki Kaisha Corporation

Tatsuo Imafuku

Takahiro Bito

Toshihisa Ishida

Takeshi Satoh

Junichi Saito

Yasuharu Morinishi

Tadashi Nakamura

Hitoshi Nagahama

Yoshiaki Akazawa

Nobuyasu Honda

Yoshinori Urata

Satoshi Ogawa

Takeshi Ohkawa

Yuichiro Takesue

Eiji Tenjiku

Kazuki Takatsuka

Takeaki Ohuchi

Masaki Ueji

Akiko Tsujimoto

Tenjiku Eiji

Ohkawa Takeshi

The present invention provides a carrier for a two-component electrophotographic developer, comprising a core particle and a thermoset silicone resin layer coated thereon, wherein said layer comprises a charge control agent and is formed by heat-treatment at a temperature below the melting point of said charge control agent.

Carrier, two-component developer using the same, and image-forming apparatus using said developer

A toner comprising a small-particle diameter external additive having a number average particle diameter of 7 to 20 nm, a large-particle diameter external additive having a number average particle diameter of 40 to 80 nm and a toner particle having a volume average particle diameter of 4 to 7 &#x3bc;m, wherein the large-particle diameter external additive is stuck to the surface of the toner particles in a semi-embedded state and has a rate of liberation of 0.1% by weight or less from the surface of the toner particle.

Toner, two-component developer and image formation device

Provided is a developing toner for electrostatic latent images capable of coping with the size reduction of an image forming apparatus and decrease of the consumption amount, not shortening the working life of a photoreceptor, less causing paper jam, background fogging, etc., excellent in various characteristics required for the toner, and capable of forming images of good picture quality. The developing toner being used when images are formed to a recording material in an image forming apparatus comprising an image forming station, a recording material feeding station, an image fixing station and a controlling station, the developing toner for electrostatic latent images containing hydrophobic fluidizing particles deposited to the surface of coloring resin particles comprising a binder resin containing a polyester resin, a polyalkylene, a polyolefin dispersant and a non-oxidized polyethylene resin, and an inorganic pigment, and having time constant &#x3c4; of from 100 to 350 msec.

Developing toner for electrostatic latent images, imaging forming method and image forming apparatus

A toner for electrostatic image development, which contains toner particles in which not more than 13 percent by number of the toner particles have a particle diameter of smaller than 4 &#x3bc;m, not less than 20 percent by number of the toner particles have a particle diameter of 4 &#x3bc;m to 6 &#x3bc;m, and not more than 2.0 percent by volume of the toner particles have a particle diameter of 16 &#x3bc;m or greater. The toner particles have a volume average diameter of 4 &#x3bc;m to 9 &#x3bc;m, and at least an external additive is added to the toner particles.

Toner for electrostatic image development and image forming method using the same

In the two-component developer for use in electrophotography containing a toner and a carrier, said toner contains a magnetic powder as an external additive, said carrier is a resin coated magnetic carrier of 6.0 to 8.0 in true specific gravity, and the coating resin is a silicone based resin containing a crosslinking agent having phenyl groups and an aminosilane coupling agent. The crossliking agent in the coating resin for the carrier has phenyl groups in a content ratio of 0.2 to 15% by number.

Developer for use in electrophotography and method and apparatus for image formation

The present invention provides an electrophotographic developer which reduces toner contamination on the surface of a developer carrier even when a development effective range is narrowed and which is stabilized in an image quality in every environmental situation and has a long life and a low cost and an image-forming method using the same. In the present invention, used for the electrostatically charged-image holder described above having a radius of curvature of 18 mm or less in a development effective range is the electrophotographic developer which is a two-component developer comprising a toner comprising at least a binder and a colorant and a carrier which is coated with a resin and has a weight average particle diameter of 40 to 100 &#x3bc;m, wherein the above toner has a volume average particle diameter of 8 to 11.5 &#x3bc;m, and the toner particles having a diameter of 6.35 &#x3bc;m or less account for 20 number % or less.

Electrophotographic developer and image-forming method using the developer

An electrophotographic toner constituting a dual component is composed of toner base particles and fine inorganic particles having a volume mean diameter of 250 to 600 nm with a specific surface area of 0.25 to 0.5 m /g for serving as an abrasive, and is characterized in that 1.5 to 2 parts by weight of the abrasive is externally added to 100 parts by weight of the toner base particles and made to be deposited over the toner base particle surface. Also, the above electrophotographic toner is used for an electrophotographic apparatus which includes a photoreceptor cleaning device located above the level that passes through the center of the photoreceptor drum.

Electrophotographic toner and electrophotographic apparatus

A binder resin as the main component of the toner has a low molecular weight polypropylene as a separating agent, encapsulated therein. Using this binder a toner with the wax having a diameter of 0.3 .mu.m or less dispersed therein is produced. The wax is included 0.5 part to 5 parts by weight for 100 parts by weight of the binder resin. This limitation of the toner prevents the setoff phenomenon during the fixing process and at the same time prevents the filming phenomenon over the photoreceptor and achieves an improved fixing performance.

Toner for electrophotography and a production method thereof

In toner 1 containing a binder resin 2, wax particles 3 and a coloring agent, the wax particles 3 are designed so that the ratio of major axis/minor axis is set in the range of 1.4 to 4.0 and so that the major axis L is not more than 6.0 .mu.m. Moreover, the melt index of the binder resin ranges from 5.0 to 11.0, and the dielectric loss tangent (tan .delta.) is not more than 5.0. This arrangement prevents the wax particles 3 inside the toner 1 or at the toner 1 surface layer from exposing to or sticking out of the toner 1 surface, thereby making it possible to provide a superior offset-reducing property during the fixing process and electrophotographing toner that can reduce wax contamination on the surface of the toner-bearing body.

Toner used for electrophotography

A toner for electrophotography includes a binder resin as the main component and a coloring agent, wherein the binder resin contains a low molecular weight polypropylene as a separating agent, encapsulated therein; the acid value of the binder resin is adjusted equal to 1.0 (mgKOH/g) or below; and the coloring agent has a surface which is not oxidation treated and presents a pH of 7.0 or higher. Limiting the added amount and the diameter of encapsulated and dispersed polypropylene wax provides prevention against both the setoff and filming phenomena.

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Nara, Japan

Tatsuo Imafuku