Kyocera Document Solutions Inc.

Mita Industrial Co., Ltd.

Other

Kyocera Mita Corporation

Toru Takatsuna

Takashi Nagai

Kazushige Inoue

Seiji Kikushima

Yoshihisa Kuramae

Hiroko Higuchi

Yoshio Ozawa

Masami Tsujihiro

Yukihiro Mori

Ryotaro Komada

Hiroaki Moriyama

Sho Sumioka

Kouzou Teramoto

Hiroko Sugimoto

Hidekazu Tamura

Etsuro Nakagawa

Noriya Okamoto

A magnetic toner includes toner particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The toner mother particles contain a binder resin and a magnetic powder. The external additive includes resin particles as external additive particles. The resin particles have a blocking rate of no greater than 40% by mass. The resin particles have a number average primary particle diameter of at least 40 nm and no greater than 120 nm. A resin constituting the resin particles is a vinyl resin including repeating units represented by general formulas (1) and (2), and a repeating unit derived from a sulfo group-containing vinyl compound. The content of the repeating unit derived from the sulfo group-containing vinyl compound in the vinyl resin is at least 0.1 mol % and no greater than 3.5 mol % 

Magnetic toner

A developer includes a toner including toner particles and a carrier including carrier particles. The carrier particles each include a carrier core and a carrier coating layer covering the carrier core. The carrier coating layer contains a fluorine-containing resin. The toner particles each include a toner mother particle and resin particles located on a surface of the toner mother particle. The resin particles have a number average primary particle diameter of at least 70 nm and no greater than 200 nm. A dispersion obtained by dispersing 0.1 g of the resin particles in 100 mL of distilled water has an electrical conductivity of at least 2.5 &#x3bc;S/m and no greater than 6.0 &#x3bc;S/m. A degree of aggregation Yof the resin particles represented by expression (1) 'Y=100&#xd7;M/M' is at least 15% by mass and no greater than 40% by mass.

Developer, image forming apparatus, and image forming method

A positively chargeable electrostatic latent image developing toner includes a plurality of toner particles each including a toner mother particle and an external additive adhering to a surface of the toner mother particle. The external additive includes metal oxide particles and coat layers that are each disposed over a surface of a corresponding one of the metal oxide particles. The coat layers contain a nitrogen-containing resin. The metal oxide particles contain metal ions having an electronegativity of no greater than 11.

Positively chargeable electrostatic latent image developing toner

The present disclosure relates to an electrostatic latent image developing toner containing a toner particle including a toner core containing a binder resin and a shell layer coating a surface of the toner core. The shell layer contains a unit derived from a monomer of a thermosetting resin, and a unit derived from a thermoplastic resin. The thermosetting resin is one or more resins selected from the group of amino resins consisting of a melamine resin, a urea resin, and a glyoxal resin. The toner particle contains fine particles in an interfacial portion between the toner core and the shell layer, and the fine particles have a charge property opposite to that of the toner, or have a volume resistivity lower than both a volume resistivity of the binder resin and a volume resistivity of the shell layer.

Electrostatic latent image developing toner

In a positively chargeable toner, calcium carbonate fine particles having a certain average primary particle diameter are attached to the surface of toner base particles. The toner base particles contain at least a binder resin and a colorant. The calcium carbonate fine particles are ones which had been subjected to a surface treatment with a positively chargeable surface treating agent and a silicone oil. A mass ratio of the positively chargeable surface treating agent to the silicone oil attached to the surface of the calcium carbonate fine particles is set to be 7:3 to 3:7 in terms of the positively chargeable surface treating agent:the silicone oil.

Positively chargeable toner

A magnetic toner contains, as a magnetic powder, magnetic iron oxide having an octahedral particle shape and an average particle diameter of 0.21 &#x3bc;m or larger and containing 18% or more by weight of FeO. The magnetic toner is so prepared as to have a bulk density A (g/cm) and a magnetic powder content B (% by weight) that fulfill the formulae 0.8&#x2266;A/B&#xd7;100&#x2266;1.6 and 35&#x2266;B&#x2266;50. This alleviates the reddishness of images produced with the magnetic toner, and alleviates the disturbance of a thin toner layer on a developing sleeve and thus the fogging resulting therefrom.

Method for developing an electrostatic latent image

A developing apparatus has a developer supporting member with a surface roughness R in the range from 3.0 to 5.5 &mgr;m and a one-component developer T with a bulk density in the range from 0.35 to 0.55 g/ml, and an image is developed by forming a layer of the developer T on the developer supporting member . This makes it possible to form a thin toner layer stably despite changes in ambient conditions, and to prevent low image density and fogging. The absolute value of the amount of electric charge with which the developer T is charged is preferably in the range from 3.0 to 10.0 &mgr;C/g. The developer supporting member is made preferably of stainless steel.

Developing apparatus and image forming apparatus employing it

This invention provides an electrophotographic toner comprising the polyester resin being fixing resin and the electric charge control resin having the functional group that endows positively charging property to the toner, in which the polyester resin has an acid value of not more than 10 mgKOH/g and a hydroxyl value of not more than 40 mgKOH/g, and the functional group is present in 2 to 5 mol % in the electric charge control resin. This electrophotographic toner has stable positively charging property, so that good image is obtainable.

Electrophotographic toner and contact development method using the toner

There is disclosed a positive charging type electrophotographic toner comprising a fixing resin, and a colorant and an electric charge controlling material, which are contained in the fixing resin, the electric charge controlling material being an electric charge controlling resin comprising a polymer which is compatible with the fixing resin, a molecular-weight distribution of the polymer resembling a molecular-weight distribution of a weight-average molecular weight of not more than 20,000 in the molecular-weight distribution of the fixing resin, and a group corresponding to a quaternary ammonium salt being contained at the side chain of the polymer. This toner is superior in charging properties, fixing properties, offset resistance and strength, because a resin having a quaternary ammonium salt group is used as the electric charge controlling material.

Electrophotographic toner

The present invention provides a toner 1 for non-magnetic one-components developments to be used for a method for non-magnetic one-component contact type development, wherein an apparent density is not less than 0.32 g/cc and when supplying to a developing roller 2 immediately after the consumption at the black solid part, a charged amount is not less than 7 .mu.C/g at an absolute value. This toner is suitable for using in combination with an organic photoconductor and can prevent that a residual image of the black solid part is remained at the half tone part immediately after the development of the black solid part.

Growing community of inventors

Osaka, Japan

Toru Takatsuna