Mita Industrial Co., Ltd.

Kyocera Mita Corporation

Hideaki Kawata

Nobuaki Kawano

Masatomi Funato

Koji Honda

Yoshiteru Hatase

Seijiro Ishimaru

Akinori Koyama

Tomohide Iida

Hidekazu Tamura

Kiminori Umeda

Fumie Kimura

The present invention provides a magnetic mono-component toner which can suppress a selection development on a latent image carrier and can maintain favorable image properties for a long period by using a toner having the coarse powder distribution (S) within a given range in a jumping developing method and an image forming method which uses the toner. In the toner used in the jumping developing method which develops an electrostatic latent image formed on a latent image carrier using a developer carrier, the toner includes toner particles which contain at least a binding resin and a magnetic powder, and the coarse powder distribution (S) of the toner particles satisfies a following formula (1).Coarse powder distribution ()=(50&#x2212;)/2&#x2267;17 (volume %/&#x3bc;m)&#x2003;&#x2003;(1)(wherein, A is a volume % of the coarse powder having particle sizes larger than Dbased on volume by 2 &#x3bc;m or more).

Magnetic mono-component toner for developing electrostatic latent image and image forming method

The present invention provides a magnetic mono-component toner which can suppress a selection development on a latent image carrier and can maintain favorable image properties for a long period by using a toner having the coarse powder distribution (S) within a given range in a jumping developing method and an image forming method which uses the toner. In the toner used in the jumping developing method which develops an electrostatic latent image formed on a latent image carrier using a developer carrier, the toner includes toner particles which contain at least a binding resin and a magnetic powder, and the coarse powder distribution (S) of the toner particles satisfies a following formula (1).Coarse powder distribution ()=(50&#x2212;)/2&#x2267;17(volume %/&#x3bc;m) &#x2003;&#x2003;(1)(wherein, A is a volume % of the coarse powder having particle sizes larger than Dbased on volume by 2 &#x3bc;m or more)

A carrier for use in development of an electrostatic latent image and an image forming apparatus using the carrier, with which a stable charging ability is maintained for a long period of time, and a high density image free from fog can be formed. The carrier has magnetic material particles coated with a coating resin. The coating resin is a thermoplastic resin, with a hardness of rank F to B in the terms of the pencil scratch test, and is present in an amount of 0.5 to 5 parts by weight to 100 parts by weight of the magnetic material particles.

Carrier for use in development of electrostatic latent image and image

A magnetic carrier for electrophotographic developing agent wherein the surfaces of the magnetic core particles are partly coated with a thermosetting resin and a small amount of a low-melting or low-softening thermoplastic resin or wax, and at least recessed portions of the core particles are filled with these coating materials. The magnetic carrier has an electric resistance that is maintained within a range that is suited for forming the image, and suppresses the occurrence of spent toner.

Magnetic carrier for electrophotographic developing agent and method of

An electrophotographic developer includes a toner and a carrier, in which the carrier is provided on the surface of a core material thereof with a resin coating layer. The coating layer is made of cured body of a methyl silicone resin containing not less than 70% by weight of T-units and a methylated melamine resin having a molecular weight of not less than 700. This developer is not lowered in flowability, generates no spent particles and presents stable electric charging characteristics. Accordingly, the developer of the present invention is suitably used where a toner is used containing no electric charge controlling agent.

Electrophotographic developer

A magnetic carrier for a two-component type developing agent used for the electrophotography, comprising resin-magnetic spherical particles which are formed by the polymerization of a monomer in which a magnetic powder is dispersed and which have a glass transition temperature of higher than 100.degree. C., the surfaces of said resin-magnetic spherical particles being coated with a surface-treated coating layer. Therefore, the surface-treated coating layer on the surfaces of the carriers can be heat-treated at 100.degree. C. or higher. The carrier therefore is light in weight, flowable, and exhibits excellent durability, resistance against the heat and stable electric characteristics irrespective of the passage of time.

Carrier for a developing agent

A specific silicone oil having a vicinal epoxy group is coated on a carrier for a developing or incorporated in a coating resin layer of a carrier for a developer. In this carrier, the spending phenomenon is prevented, the moisture resistance and flowability are improved, and a stable friction chargeability can be maintained for a long time and the durability is highly improved.

Carrier for developer

A resin-coated magnetic carrier for two-component developers which comprises magnetic particles and a resin coating formed on the individual magentic particles is described. The resin coating is made of a cured resin composition comprised of an alkylated melamine resin whose moelcular weight satisfies the followin inequality

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Osaka, Japan

Hideaki Kawata