Canon Kabushiki Kaisha

Kaori Hiratsuka

Katsuhisa Yamazaki

Tsutomu Onuma

Nobuyuki Okubo

Takashige Kasuya

Hirohide Tanikawa

Tsuneo Nakanishi

Yoshihiro Ogawa

Tsuyoshi Takiguchi

Kimihiro Yoshimura

Yosuke Morikawa

Michihisa Magome

Tatsuhiko Chiba

Keiji Komoto

Takeshi Kaburagi

Hydrophobic inorganic fine particles characterized by being a mixture of at least small-particle-diameter inorganic fine particles having an average primary particle diameter of 5 to 25 nm and having a maximum peak particle diameter of 20 nm or less and large-particle-diameter inorganic fine particles having an average primary particle diameter which is 1.5 to 100 times the average primary particle diameter of the small-particle-diameter inorganic fine particles; the mixture being a mixture having been treated in the same treating tank to subject both the small-particle-diameter inorganic fine particles and large-particle-diameter inorganic fine particles simultaneously to hydrophobic treatment.

Hydrophobic inorganic fine particles, hydrophobic inorganic fine particles production process, and toner

A toner exhibits excellent image characteristics, and also has an excellent charging property even if the toner is used in a cleaning-simultaneous-with-developing system having a direct injection charging mechanism. The toner includes toner particles and non-magnetic metallic-compound fine particles. The weight average particle diameter of the toner is 3.0 &#x3bc;m to 12.0 &#x3bc;m. The metallic-compound fine particles are conductive metallic-compound fine particles having a specific surface area (cm/cm) of 5&#xd7;10to 100&#xd7;10; a medium diameter (D) of 0.4 &#x3bc;m to 4.0 &#x3bc;m with respect to a volume-based particle diameter distribution, the medium diameter (D) being smaller than the weight average particle diameter of the toner; and a 90% particle diameter Dof 6.0 &#x3bc;m or less with respect to a volume-based particle diameter.

Toner, method for forming image using the toner, and process cartridge

A developer capable of providing an excellent image without causing a charging failure even after a long-term and repeated use contains a toner particle having a binder resin and a colorant, an inorganic fine particle, and a conductive fine particle, in which a volume average particle diameter Da of the conductive fine particle and an number average primary particle diameter Db of the inorganic fine particle satisfy the expression (1) below, and a rate of liberation 'a' of the conductive fine particle from the toner particle is 40 to 95% and a rate of liberation 'b' of the inorganic fine particle from the toner particle is 0.1 to 5%Da&#x2267;10Db. &#x2003;&#x2003;(1)

Developer

To provide a method for forming images in which the image bearing member and the toner carrying member are arranged with a gap of 100 &#x3bc;m to 250 &#x3bc;m, and the equation (1) and equation (2) are satisfied. (1) 22&#x2266;(the frequency of the alternating current component of the alternating electric field/the peripheral speed of the toner carrying member)&#xd7;the maximum electric field intensity at the time of developing&#x2266;1.20. (2) 8&#x2266;(the frequency of the alternating current component of the alternating electric field/the peripheral speed of toner carrying member)&#xd7;(the fluidity index of Carr/the floodability index of Carr)&#x2266;50. According to the method for forming images of the present invention, it is possible to obtain a high quality image without generating fog and light shielding while attaining a uniform halftone with a high image density even over long-term.

Method for forming image

A process cartridge which is detachably mountable to a main body of an image-forming apparatus has a photosensitive member, a magnetic toner-holding section provided with a magnetic toner-carrying member which transports the toner to a developing zone, and a residual magnetic toner detector capable of detecting residual toner by a change in electrostatic capacity which is caused between electrodes provided inside the magnetic toner-holding section. The magnetic toner contains at least a binder resin and a colorant, having a weight-average particle diameter of from 6.5 &mgr;m to 15.0 &mgr;m, and having a Carr's floodability index of more than 80.

Process cartridge

In a toner production process having at least a kneading step, a pulverization step using a mechanical grinding machine, and a classification step, the grinding means comprises a mechanical grinding machine having at least a rotor which is a rotator attached to the center rotating shaft and a stator which is provided around the rotor, keeping a constant gap between the stator and the rotor surface, the grinding machine being so constructed that a circular space formed by keeping the gap stands airtight, and the surface of at least one of the rotor and the stator is coated by the plating of a chromium alloy containing at least chromium carbide.

Toner production process

A magnetic toner is formed of magnetic toner particles each comprising at least a binder resin and a magnetic iron oxide. The magnetic toner is provided with improved developing performances by realizing an appropriate surface-exposure state of the magnetic iron oxide, which is represented by a wettability characteristic in methanol/water mixture liquids of the magnetic toner such that it shows a transmittance of 80% for light at a wavelength of 780 nm at a methanol concentration in a range of 65-75% and a transmittance of 20% at a methanol concentration in a range of 66-76%.

Magnetic toner and process cartridge

A dry magnetic toner is formed of magnetic toner particles comprising a binder resin and magnetic iron oxide particles. The magnetic toner is provided with excellent developing performances and transferability by controlling the presence of isolated iron-containing particles and containing a high percentage of spherical particles, the amount of which is controlled relative to the weight-average particle size of the magnetic toner and a content of particles of 3 &mgr;m or below in the magnetic toner.

Dry toner, image forming method and process cartridge

A toner is principally constituted by a binder resin, a colorant and a hydrocarbon wax. The hydrocarbon wax has a hydroxyl value (Hv) of 5-150 mgKOH/g and an ester value (Ev) of 1-50 mgKOH/g satisfying Hv>Ev. Further, the toner has a tetrahydrofuran-soluble content providing a gel-permeation chromatogram showing at least one peak in a molecular weight region of 3&times;10 to 5&times;10 and at least one peak or shoulder in a molecular weight region of 1&times;10 to 1&times;10 .

Toner having hydrocarbon wax with specific ester value and hydroxyl value

A toner having a stable chargeability in various environments, a stable fixability over a wide temperature range and a resistance to sticking on an image-bearing member, is formed of a binder resin, a colorant and an azo iron compound as a charge control agent. The azo iron compound is formed from a monoazo compound having at least one alkyl group and two hydroxyl groups capable of bonding with an iron atom. The toner has a tetrahydrofuran-soluble content providing a gel-permeation chromatogram showing at least one peak in a molecular weight region of 3&times;10 to 5&times;10 and at least one peak or shoulder in a molecular weight region of above 5&times;10 and at most 1&times;10 .

Growing community of inventors

Shizuoka, Japan

Kaori Hiratsuka