Mita Industrial Co., Ltd.

Masatomi Funato

Nobuhiro Miyakawa

Yoshitake Shimizu

Yumiko Sano

Seijiro Ishimaru

Kazuya Nagao

Nobuaki Kawano

Hideaki Kawata

Koji Honda

Teruaki Higashiguti

Norio Kubo

Terumichi Asano

Teruaki Higashiguchi

Kiminori Umeda

The invention provides toner for a two-component type developer containing toner particles including a binder resin and magnetic powder dispersed in the binder resin. The binder resin in the toner is prepared from a composition including at least one of (1) a polymer having an anionic group and a wax grafted portion and (2) a mixture of a polymer having an anionic group and a polymer having a wax grafted portion. The magnetic powder is contained in the toner particles at a proportion ranging between 0.1 and 5 parts by weight per 100 parts by weight of the binder resin.

Toner for a two-component type developer

The invention provides toner for a two-component type developer containing toner particles including a binder resin and magnetic powder dispersed in the binder resin. The binder resin in the toner is made of a composition including a low molecular weight polymer and a high molecular weight polymer both having an anionic group. The magnetic powder is contained in the toner particles in the range of 0.1 to 5 parts by weight per 100 parts by weight of the binder resin.

A toner in which a small amount of magnetic powder is disposed in a resin medium for fixing which comprises a cationic polar group-containing copolymer resin or a resin composition. A distinguished feature resides in that the toner does not contain a charge control agent. The toner is positively charged and exhibits very good spent resistance. The toner further exhibits favorable electrophotographic properties such as transfer efficiency despite there is contained no charge control agent.

Toner for a two-component-type magnetic developing agent having

A negatively charged toner for a two-component-type magnetic developing agent, wherein a resin medium for fixing is a copolymer resin or a resin composition having anionic polar groups and contains a magnetic powder in an amount of from 0.1 to 5 parts by weight per 100 parts by weight of the resin medium, but contains no charge control agent. The toner without containing the charge control agent exhibits very excellent spent resistance.

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

A photosensitive material for electrophotography, which comprises an electroconductive substrate and a photosensitive layer formed on the substrate. The photosensitive layer comprising a charge transfer medium and a charge-generating pigment dispersed in the mediums. The photosensitive layer contains as the matrix resin a thermoplastic polyester consisting essentially of recurring units represented by the following general formula: ##STR1## wherein R.sup.1 stands for a phenylene group or an ethylene group, R.sup.2 stands for a group represented by the formula ##STR2## R.sup.3 stands for a direct bond or a divalent bridging atom or group, and the ring A may have a substituent not participating in the reaction. In another embodiment a photosensitive material for electrophotography includes an electroconductive substrate, a photoconductive organic pigment-containing, charge-generating layer formed on the substrate and a charge transfer layer formed on the charge-generating layer, wherein the charge transfer layer contains as the matrix resin the above-mentioned thermoplastic polyester. These thermoplastic polyesters provide improvements in adhesion to the substrate, surface hardness and abrasion resistance.

Photosensitive material for electrophotography

Disclosed is a photosensitive material for electrophotography comprising an organic polymeric photoconductive material and a thermoplastic polyester composed mainly of recurring units represented by the general formula ##STR1## wherein R.sup.1 represents a phenylene, ethylene or vinylene group, R.sup.2 represents a group of the formula ##STR2## R.sup.3 represents a direct bond or a divalent bridging atom or group, and the ring A may have a substituent inert to the polyester-forming reaction, provided that R.sup.1 and R.sup.2 are selected such that one of them contains an aromatic ring and the other does not.

Electrophotographic photosensitive material with polyester binder

Disclosed is a photosensitive material for electrophotography, which comprises a photosensitive layer containing a tetrakis-azo pigment represented by the following formula: ##STR1## wherein X.sub.1 stands for a lower alkyl group, a lower alkoxy group or a halogen atom, X.sub.2 and X.sub.3 stand for a lower alkyl group, a lower alkoxy group, a halogen atom or a hydrogen atom, and Y stands for a group represented by the following group: ##STR2## in which Z stands for an aromatic ring such as a benzene or naphthalene ring, a substitution product thereof, a hetero ring such as an indole, carbazole or benzofuran ring, or substitution product thereof, Ar.sub.1 stands for an aromatic ring such as a benzene or naphthalene ring, a substitution product thereof, a hetero ring such as a dibenzofuran ring, or a substitution product thereof, Ar.sub.2 and Ar.sub.3 stand for an aromatic ring such as a benzene or naphthalene ring or a substitution product thereof, R.sub.1 stands for a lower alkyl group, a carboxyl group or an ester thereof, and R.sub.2 and R.sub.3 stand for a hydrogen atom, a lower alkyl group, a phenyl group or a substitution product thereof.

Disclosed is an electrophotographic photosensitive material comprising a photosensitive layer containing a tris-azo pigment represented by the following formula: ##STR1## wherein the ring A.sub.1 and A.sub.2 may have a halogen atom, an alkyl group or alkoxy group as a substituent at the ortho-position to the azo group, Z stands for a benzene ring, naphthalene ring, indole ring, carbazole ring or benzofuran ring fused to the benzene ring B, and R stands for an unsubstituted or substituted phenyl, naphthyl or heterocyclic group. This photosensitive material has a high sensitivity to rays in a broad wavelength region and is excellent in the resistance in the printing operation.

Growing community of inventors

Osaka, Japan

Masatomi Funato