Canon Kabushiki Kaisha

Miho Okazaki

Yoshihiro Ogawa

Takashige Kasuya

Yusuke Hasegawa

Tomohisa Sano

Junko Nishiyama

Kouji Nishikawa

Koji Nishikawa

Yoshitaka Suzumura

Tsutomu Onuma

Junko Hirata

The object of the present invention is to provide a magnetic toner enabling an image with high image density and excellent image reproducibility to be obtained, which is excellent in fluidity, charging stability, and charging uniformity, even for long-term use, and also enabling an image whose fogging, ghost, and scattering are suppressed to be obtained. The magnetic toner has at least a binder resin and a magnetic material, where, the magnetic material is an magnetic iron oxide whose dielectric breakdown voltage of the magnetic material is 160 to 1600 V/cm, and the dielectric loss tangent (tan &#x3b4;) of the magnetic toner at 100 kHz and 40&#xb0; C. is 2.0&#xd7;10to 1.0&#xd7;10.

Magnetic toner

Hydrophobic inorganic fine particles are provided which: does not cause melt adhesion of toner to a photosensitive member and contamination of a contact charging member; imparts excellent flowability, charging performance and durability to toner even after the toner is stored in a high-temperature, high-humidity environment over a long time period; and does not cause dripping of toner and contamination with the toner. The hydrophobic inorganic fine particles are obtained by subjecting inorganic fine particles to surface treatment with silicone oil and then with a silane compound and/or a silazane compound, or by subjecting inorganic fine particles to surface treatment with a silane compound and/or a silazane compound in the presence of silicone oil, and further subjecting the inorganic fine particles thus surface-treated to surface treatment with silicone oil.

Hydrophobic inorganic fine particles and toner

To provide a toner which has superior low-temperature fixing performance, high-temperature anti-offsetting properties and developing performance and may cause neither melt sticking of toner to photosensitive member nor turn-up of cleaning blade. The toner contains at least a binder resin, a colorant and a wax, and the wax is characterized by i) being an oxidized hydrocarbon wax, ii) having a hydroxyl value of from 5 mgKOH/g or more to 150 mgKOH/g or less, and iii) having, in molecular weight distribution measured by gel permeation chromatography of tetrahydrofuran-soluble matter, a main peak within the range of molecular weight of from 200 or more to 600 or less, and a component with a molecular weight of 700 or more in a content of 3% by mass or less.

Toner

A magnetic toner including at least: a binder resin; and a magnetic body, in which, when magnetization at a magnetic field strength of 397.9 kA/m and a coercive force of the magnetic toner are denoted by &#x3c3;s (Am/kg) and Hc (kA/m), respectively, a magnetic field strength at which the magnetic toner shows a magnetization value equal to 95% of &#x3c3;s is denoted by H95% (kA/m), and a number average particle size of the magnetic body is denoted by d (&#x3bc;m), H95%, Hc, and d satisfy the following expressions.151&#x3c;H95%&#x3c;200&#x2003;&#x2003;(1)7.1&#x3c;Hc&#x3c;12&#x2003;&#x2003;(2)40&#x3c;&#x3c;150&#x2003;&#x2003;(3)

The invention is to provide a toner excellent in fixing property, high-temperature offset resistance and blocking resistance, and having an excellent developing property. The invention provides a toner including at least a binder resin and a colorant, wherein: the binder resin contains a hybrid resin which contains a polyester-type resin unit by 50 mass % or more and in which a polyester-type resin component and a vinyl-type resin component are chemically bonded; the toner contains 3 to 50 mass % of a tetrahydrofuran-insoluble matter derived from the binder resin; the tetrahydrofuran-insoluble matter contains a hybrid resin; and a tetrahydrofuran-soluble matter, obtained by hydrolyzing the tetrahydrofuran-insoluble matter and separating by filtration, has, in a GPC-measured molecular weight distribution, a main peak within a molecular weight range of 50,000 to 500,000.

Toner with hybrid binder resin

An image forming method and related process cartridge, the method having the steps of controlling the layer thickness of a toner on a toner bearing member by means of a toner regulating blade, and developing with the toner an electrostatic latent image formed on an electrostatic latent image bearing member, the toner regulating blade has, at its part to be kept in touch with the toner bearing member, a specific ten-point average roughness Rz and a specific ratio (area of contact portion/area of non-contact portion) at a specific face pressure, and the toner has a specific average circularity and has a specific aerated bulk density. This image forming method and process cartridge promise superior developing performance in any environment, can keep sleeve negative ghost from occurring and can keep toner melt adhesion to toner regulating blade and toner melt adhesion to toner bearing member from occurring.

Growing community of inventors

Suntou-gun, Japan

Miho Okazaki