Mita Industrial Co., Ltd.

Sharp Kabushiki Kaisha Corporation

Nobuyasu Honda

Toshimitsu Ikeda

Toshiro Yamakawa

Masahiko Kubo

Toshihisa Ishida

Toshikazu Matsui

Akira Fushida

Tetsuya Nakano

Takahiro Bito

Masanori Fujii

Tatsuo Imafuku

Yoshinori Urata

Tadashi Nakamura

Yoshiaki Akazawa

Koji Kuramashi

Yasushi Kamezaki

Takashi Nagai

Yasuharu Morinishi

Takashi Teshima

Hideo Fukuda

Nobuyuki Tsuji

Tomohide Iida

Toshiaki Akiyama

Akira Horiuchi

Asao Toda

Kenji Takahashi

Minoru Nakao

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

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.

Toner for electrophotography

The present invention provides a method for impression development which comprises forming a thin layer of a toner on a surface of a developing roller with a plate-like rigid member, and developing an electrostatic latent image formed on a photoconductor by contacting the thin layer with the electrostatic latent image. The toner comprises toner particles, and prescribed amount of inorganic fine particles (mean particle diameter of 0.1 to 1.0 .mu.m on the volume basis), and/or comprises toner particles which have prescribed distribution of the odd-shape degree of the toner particle (mean value of the odd-shape degree and the proportion of the number of toner particles having the odd-shape degree of not more than 0.2). According to the method for impression development, it becomes possible to form an image having no failures and good image quality.

Method for impression development

Disclosed is a development device comprising a development sleeve of a non-magnetic material, a magnet having a plurality of magnetic poles and fixed within the sleeve, a mechanism for rotating the sleeve, a mechanism for agitating a developer composed of a magnetic carrier and a chargeable toner and supplying it to the sleeve, a mechanism for adjusting a magnetic brush formed on the sleeve to a predetermined brush length and supplying it to a development zone, and a mechanism for scraping off the magnetic brush which has gone past the development zone from the sleeve, said magnetic poles consisting of a main pole for development corresponding to the development zone and poles for conveying corresponding to a conveying zone ranging from the position of supplying the developer to the position of cutting the magnetic brush, said magnetic carrier being a ferrite carrier, and each said conveying magnetic pole having a magnetic flux density 50 to 86% of that of the main pole for development.

Developing device

Disclosed is a negatively chargeable blue toner comprising a fixing resin binder and an indanthrone dye as a coloring and charge controlling agent. The indanthrone dye as the coloring and charge controlling agent may be used advantageously not only singly but also in combination with a halogen-substituted copper phthalocyanine pigment.

Negatively chargeable blue toner comprising indanthrone dye

A charged image on a photosensitive layer is developed with a toner containing a releasing agent and a hydroxycarboxylic acid complex salt to form a toner image. The toner image is then transferred to a receptor sheet and fixed to it. The use of a toner containing a specific hydroxycarboxylic acid complex salt brings about a marked advantage of widening a non-offset region to a higher temperature without impairing the antiblocking property, flowability and heat resistance of the toner.

Method for preventing offset in electrophotography

Disclosed is a magnetic brush development method comprising supplying a two-component type developer comprising a mixture of magnetic carrier particles with toner particles chargeable by friction with the magnetic carrier particles onto a developing sleeve consisting of a non-magnetic sleeve having a magnet installed therein to form a magnetic brush of the developer, and bringing the magnetic brush in sliding contact with the surface of a photosensitive material having an electrostatic latent image formed thereon in the state where a bias voltage is applied between the photosensitive material and the sleeve, whereby a toner image corresponding to the electrostatic latent image is formed, wherein the two-component type developer comprises a ferrite carrier and electroscopic toner particles at a weight ratio of from 4/1 to 20/1.

Magnetic brush development method

Disclosed is a pressure-fixing toner for the electrophotography, which comprises electroscopic particles having an indeterminate shape and comprising as a pressure-fixing binder component a composite binder component comprising a wax component and a resin component composed mainly of a styrene-acrylic copolymer at a weight ratio of from 54/46 to 20/80, wherein the wax component is present in the form of spherical particles having a particle size smaller than 10 microns in a continuous phase of the resin component.

Pressure-fixing toner for electrophotography and process for preparation

Disclosed is a method for developing electrostatic latent images, which comprises frictionally contacting the surface of a substrate having an electrostatic latent image formed thereon with a magnetic brush of a developer formed on a developer-delivering sleeve having a magnet disposed therein, wherein a magnetic brush is formed on the sleeve with an earing promoting component comprising sintered ferrite particles having a particle size of 20 to 100 microns and a developer component comprising particles of a dispersion of a magnetic powder in a binder medium having a particle size of 5 to 50 microns.

Method for developing electrostatic latent images

Disclosed is a magnetic toner having an improved humidity dependency, which comprises as main ingredients a magnetic material composed of magnetite and a binder medium, wherein the water-soluble component content in the magnetite is lower than 0.15% by weight and the water content of the magnetite at a temperature of 20.degree. C. and a relative humidity of 60% is lower than 0.3% by weight. If this magnetic toner is used for developing an electrostatically charged image, a sharp and clear copy having a high image density with no fogging can be obtained even under a high humidity condition.

Magnetic toner having improved humidity dependency

Disclosed is a method of developing an electrostatic image by bringing an electrostatic image-carrying surface of a substrate into sliding contact with a magnetic brush of a developer formed on a developer-feeding sleeve having a magnet arranged in the interior thereof, wherein the magnetic brush is formed from an earing-promoting component comprising particles of a dispersion of a powder of a magnetic material in a resin, which have a relatively large diameter of 70 to 300 microns, and a developer component comprising particles of a dispersion of a powder of a magnetic material in a binder medium, which have a relatively small diameter of 5 to 50 microns.

Method of developing electrostatic image with magnetic brush ear promoter

Disclosed is a dry developer for an electrostatic image, which comprises molded particles of a dispersion of a binder medium, a wax and a pigment, wherein a combination or partial reaction product of (A) a copolymer of an olefin with a polar group-containing, ethylenically unsaturated monomer and (B) a metal alkoxide of aluminum or titanium is incorporated as a crosslinking agent into said molded particles. In this dry developer, the mutual dispersibility of the respective developer components is highly improved, and the developer particles are uniform and homogeneous in the composition. This dry developer for an electrostatic image is prepared by a process which comprises kneading a mixture of a binder resin, a wax and a pigment at a temperature higher than the softening points of the binder resin and wax and molding the kneaded composition into fine particles, wherein prior to, simultaneously with or after addition of the pigment, a combination or partial reaction product of (A) a copolymer of an olefin with a polar group-containing, ethylenically unsaturated monomer and (B) a metal alkoxide of aluminum or titanium is incorporated into the binder resin and wax and the composition is reacted in the molten state.

Dry developer for electrostatic image with Al or Ti alkoxide

A composite magnetic developer having a self-friction-chargeability is in the form of fixable magnetic particles having a particle size of 5 to 30 microns and comprising a finely divided magnetic material dispersed in a binder medium which shows an adhesiveness under application of heat and pressure, in which the fixable magnetic particles contain fine particles of a magnetic material embedded in the surface of the fixable magnetic particles in an amount of 1 to 10% by weight based on the fixable magnetic particles and fine particles of a magnetic material adhering to the surface of the fixable magnetic particles without being embedded therein in an amount of 1 to 20% by weight based on the fixable magnetic particles. This developer provides a sharp and clear transfer image having a high density without fogging or edge effects on a transfer sheet having a low electric resistance such as a plain paper. When this developer is used for development of electrostatic latent images, any particular charging operation need not be performed and any carrier need not be used. Even if this developer is used repeatedly for the copying operation, the composition is not substantially changed and good developing characteristics are retained.

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Tenri, Japan

Nobuyasu Honda