Canon Kabushiki Kaisha

Yuichi Mizoo

Tadashi Dojo

Nene Shibayama

Yusuke Hasegawa

Takashige Kasuya

Katsuhisa Yamazaki

Satoshi Matsunaga

Takeshi Naka

Tsuneo Nakanishi

Masami Azuma

Yushi Mikuriya

Tomohisa Sano

Takaaki Kotaki

Tadashi Doujo

Junko Yoshikawa

Ryota Kashiwabara

In a magnetic toner having toner particles containing at least a binder resin and a magnetic material, the binder resin is chiefly composed of a resin having a polyester unit synthesized using as a catalyst a tin compound represented by the following Formula (1), and the magnetic material has a number-average particle diameter of form 0.1 &#x3bc;m to 0.3 &#x3bc;m:(RCOO)Sn&#x2003;&#x2003;Formula (1)wherein R represents an alkyl group having 5 to 15 carbon atoms. This magnetic toner can attain a stable image density without dependence on environment and enables formation of high-grade images over a long period of time without causing scratches of latent image bearing members.

Magnetic toner

In an image forming apparatus having at least an amorphous silicon photosensitive member, a magnetic toner developing means and a color developer developing means, the magnetic toner has a weight-average particle diameter (D) of from 4.0 &#x3bc;m to 10.0 &#x3bc;m and a ratio thereof to number-average particle diameter (D), D/D, of from 1.0 to 2.0, and the number of magnetic particles not passing through a mesh with an opening of 34 &#x3bc;m which are contained in the unit volume of the magnetic toner is from 3.5 to 105. This image forming apparatus can not easily cause faulty cleaning performance even in using the magnetic toner and the non-magnetic color toners in combination and has superior environmental stability and running stability even where toners made to have small particle diameter are used or process speed is high.

Image forming apparatus

A magnetic black toner comprising magnetic black toner particles containing at least a binder resin and a magnetic material. The toner has a weight-average particle diameter of from 5 &mgr;m to 12 &mgr;m, and the toner has, in its particles of 3 &mgr;m or more in diameter, at least 90% by number of particles with a circularity of 0.900 or more and has an average circularity of from 0.940 to 0.970. The magnetic material comprises iron oxide particles which have an average particle diameter of from 0.10 &mgr;m to 0.30 &mgr;m, contain titanium or a titanium compound in an amount of from 0.3% by weight to 1.5% by weight in terms of titanium, based on the total weight of the iron oxide particles, and have the ratio of the proportion of FeO to the total Fe content in 10% by weight from the particle surface, A %, to the proportion of FeO to the total Fe content in the remainder 90% by weight, B %, which satisfies the expression: 0.7&lE;A/B&lE;1.0. Also, an inorganic fine powder is externally added to the toner particle surfaces.

Magnetic black toner

A toner contains at least a bonding resin and a coloring agent, and has a weight mean particle size from 5 &mgr;m to 12 &mgr;m; not less than 90% by number of particles not less than 3 &mgr;m have a circularity &ldquo;a&rdquo; not less than 0.900; a cut ratio Z and a weight mean size X of the toner are related as: cut ratio Z&lE;5.3&times;X; and a relationship of particles Y having a circularity of not less than 0.950 and a weight mean size X is Y&gE;e &times;X where X is 5 to 12 &mgr;m.

Toner, process for producing toner image forming method and apparatus unit

A toner containing toner particles and an inorganic fine powder; the toner particles containing at least a binder resin, a colorant, a sulfur-containing resin, and a wax; the binder resin containing a hybrid resin component containing a vinyl type polymer unit and a polyester unit, and the sulfur-containing resin being a resin selected from the group consisting of sulfur-containing polymers and sulfur-containing copolymers

Toner, image forming method and process cartridge

A toner manufacturing method includes grinding and classification to produce a toner containing a binder resin and a colorant with a weight mean particle size of 5 microns to 12 microns and sharp particle density distribution. The toner has a specific circularity, relationship between cut ratio and weight mean size, and relationship between circularity and weight mean size as disclosed in the specification.

A toner has toner particles containing at least a binder resin, a colorant and a sulfur-containing compound selected from the group consisting of a sulfur-containing polymer and a sulfur-containing copolymer. The toner has a weight-average particle diameter of from 5 &mgr;m to 12 &mgr;m, and the toner has, in its particles of 3 &mgr;m or larger in diameter, at least 90% by number of particles with a circularity of 0.900 or higher, and has a specific relationship between the cut rate Z and the toner weight-average particle diameter X and a specific relationship between the number-based cumulative value Y of particles with a circularity of 0.950 or higher and the toner weight-average particle diameter X. Also disclosed are an image-forming method and a process cartridge which make use of the toner.

Toner, image-forming method and process cartridge

A toner for developing an electrostatic image has a binder resin, a colorant and a charge control agent. The binder resin has a polyester resin having an acid value of from 15 to 40 and a hydroxyl value of 45 or less. The toner has, in its molecular weight distribution as measured by gel permeation chromatography, tetrahydrofuran-soluble matter having a weight average molecular weight Mw of 100,000 or more, having a ratio of weight average molecular weight Mw to number average molecular weight Mn, Mw/Mn, of not less than 35, containing from 70% to 94% of a low-molecular weight region component having a molecular weight of less than 150,000, containing from 1% to 10% of a medium-molecular weight region component having a molecular weight of from 150,000 to 500,000, and containing from 5% to 25% of a high-molecular weight region component having a molecular weight of more than 500,000. The high-molecular weight region component is more than the medium-molecular weight region component.

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Ibaraki, Japan

Yuichi Mizoo