Canon Kabushiki Kaisha

Canon Kabusbiki Kaisha

Tatsuhiko Chiba

Tatsuya Nakamura

Takashige Kasuya

Makoto Kanbayashi

Michihisa Magome

Keiji Komoto

Takayuki Nagatsuka

Kohji Inaba

Akira Hashimoto

Takeshi Kaburagi

Tsuyoshi Takiguchi

Koji Inaba

Tsutomu Kukimoto

Hiroaki Kawakami

Eriko Yanase

Kazuyuki Miyano

Kengo Hayase

Takao Ishiyama

Takeshi Menjo

Shinya Yachi

Yuji Moriki

Kazuo Yoshinaga

Kenji Okado

Atsuyoshi Abe

Masanori Ito

Ryoichi Fujita

Satoshi Yasuda

Koichi Tomiyama

Satoshi Handa

Masuo Yamazaki

Noboru Kashimura

Ichiro Ohsaki

Kaori Hiratsuka

Kiyokazu Suzuki

Makoto Kanabayashi

The present invention provides a magnetic toner which is hardly influenced by an environment, and with which an image with high quality and excellent resolution can be stably even under low humidity. In the magnetic toner of present invention:

Magnetic toner and method of manufacturing magnetic toner

In an image forming system, an image-bearing member having a photoconductor layer comprising an Si-based non-single crystal material is charged at a relatively low potential of 250 to 600 volts by a contact charging member in the presence of electroconductive fine powder. An electrostatic latent image formed on the image-bearing member is developed with a magnetic toner which includes magnetic toner particles comprising at least a binder resin and a magnetic iron oxide, and inorganic fine powder and electroconductive fine powder present at the surface of the magnetic toner particles. The magnetic toner has a weight-average particle size of 3-10 &#x3bc;m and an average circularity of 0.950 to 0.995, and contains 0.05 to 3.00% of isolated iron-containing particles.

Image forming method and apparatus

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 magnetic toner exhibiting stable performances under various environmental conditions is formed of toner particles each comprising at least a binder resin and iron oxide dispersed therein. Relative to the dry specific gravity (A) of the magnetic toner, the magnetic toner is characterized by a specific gravity distribution of toner particle fractions obtainable through wet sedimentation and including: at most 15 wt. % of a fraction having a specific gravity of above (A)&times;1.000 and at most (A)&times;1.025, 0.1-20 wt. % of a fraction having a specific gravity of above (A)&times;0.975 and at most (A)&times;1.000, at least 30 wt. % of a fraction having a specific gravity of above (A)&times;0.950 and at most (A)&times;0.975, 0.1-20 wt. % of a fraction having a specific gravity of above (A)&times;0.925 and at most (A)&times;0.950, and at most 15 wt. % of a fraction having a specific gravity of above (A)&times;0.900 and at most (A)&times;0.925.

Magnetic toner

A magnetic toner is formed of magnetic toner particles each comprising a binder resin, an iron oxide, a sulfur-containing polymer, and inorganic fine powder blended with the magnetic toner particles, the toner having a weight-average particle size (D4) of 3-10 &mgr;m, and either (a) an average circularity of at least 0.970, and a magnetization of 10-50 Am /kg (emu/g) at a magnetic field of 79.6 kA/m (1000 oersted), or (b) toner particles which retain carbon in an amount of A and iron in an amount of B at surfaces thereof, satisfying: B/A<0.001, and containing at least 50% by number of magnetic toner particles of D/C&lE;0.02, wherein C represents a particle projection area-equivalent circle diameter and D represents a minimum distance between a surface of the magnetic toner particle and iron oxide particles contained therein.

A dry toner has toner particles containing at least a binder resin, a colorant and a wax component and an external additive. The binder resin contains a component derived from a monomer selected from butadiene, isoprene and chloroprene. The toner has a main Tg from 40&deg; C. to 70&deg; C. When specific surface area measured by the BET method in an environment of 23&deg; C. atmospheric temperature and 65% relative humidity is represented by A (m /g) and specific surface area measured by the BET method in an environment of 50&deg; C. atmospheric temperature and 3% relative humidity is represented by B (m /g), the toner satisfies the following relationship: 0.8&lE;A&lE;4.0, 0.80&lE;(B/A)&lE;1.05. The toner has a circle-corresponding number-average particle diameter D1 from 2 to 10 &mgr;m, an average circularity from 0.950 to 0.995 and a circularity standard deviation less than 0.040. The toner has a main-peak molecular weight from 2,000 to 100,000 and contains a THF-insoluble matter from 5 to 60% by weight.

Dry toner, dry toner production process, and image forming method

A magnetic toner comprising magnetic toner particles containing at least a binder resin, a magnetic material containing a magnetic iron oxide, and a release agent. The magnetic toner has a weight-average particle diameter of from 3 &mgr;m to 10 &mgr;m, a magnetization intensity (saturation magnetization) of from 10 Am /kg to 50 Am /kg (emu/g) under application of a magnetic field of 79.6 kA/m (1,000 oersteds), an average circularity of 0.970 or more, a ratio of weight-average particle diameter to number-average particle diameter, of 1.40 or less, iron and an iron compound which stand liberated from the magnetic toner particles at a liberation percentage of from 0.05% to 3.00%, and a resin component having a tetrahydrofuran-insoluble matter in an amount of from 3% by weight to 60% by weight. Also disclosed is an image-forming method making use of the magnetic toner.

Magnetic toner and image-forming method making use of the same

Image forming method

A magnetic toner includes: magnetic toner particles each comprising at least a binder resin and magnetic toner, and inorganic fine powder. The magnetic toner has an average circularity of at least 0.970, and a magnetization of 10-50 Am /kg at a magnetic field of 79.6 kA/m. The magnetic powder comprises at least magnetic iron oxide. The magnetic toner particles retain carbon in an amount of A and iron in an amount of B at surfaces thereof as measured by X-ray photoelectron spectroscopy, satisfying: B/A<0.001. The binder resin comprises a resin formed by polymerization of a monomer comprising at least styrene monomer. The magnetic toner has a residual styrene monomer content of less than 300 ppm, and contains at least 50% by number of toner particles satisfying a relationship of: D/C&lE;0.02, wherein C represents a volume-average particle size of the magnetic toner, and D represents a minimum distance between the surface of a magnetic toner particle and magnetic powder particles contained in the magnetic toner particle. Owing to the above features, the magnetic toner can exhibit good electrohotographic performances, including excellent chargeability and little transfer-residual toner, even in a cleanerless-mode image forming system.

Magnetic toner, process for production thereof, and image forming method, apparatus and process cartridge using the toner

A toner is formed of toner particles each comprising a binder resin and iron oxide particles dispersed therein. The toner particles are characterized by uniform but non-surface-exposed dispersion of the iron oxide particles within the toner particles as represented by (i) a carbon content (A) and an iron content (B) giving a ratio B/A<0.001 at surfaces of the toner particles as measured by X-ray photoelectron spectroscopy, (ii) an average circularity of at least 0.970, and (iii) at least 50% by number of toner particles satisfying D/C&lE;0.02, wherein C denotes a projection area-equivalent circular diameter of each toner particle and D denotes a minimum distance of iron oxide particles from a surface of the toner particle, based on a sectional view of the toner particle as observed through a transmission electron microscope (TEM).

Toner and image forming method

A toner has toner particles and an external additive. The toner particles have a weight-average particle diameter of from 4 &mgr;m to 9 &mgr;m. The external additive has (i) first, small-particle-diameter hydrophobic fine silica particles (A) having a BET specific surface area of from 100 m,/g to 350 m,/g, having been treated with a silane, (ii) second, large-particle-diameter hydrophobic fine silica particles (B) having a BET specific surface area of from 15 m,/g to 80 m,/g, having been treated with a silicone oil, and (iii) fine alumina particles (C) having a BET specific surface area of from 50 m,/g to 150 m,/g.

Toner, image forming method, and apparatus unit

A yellow toner suitable for electrophotography is formed by dispersing a yellow colorant mixture in a binder resin. The yellow colorant mixture is formed of at least a pigment of formula (1) or (2) below, and a dye of formula (3) below:

Yellow toner, process for producing the tower and image forming method using the toner

An electrophotographic toner is formed of toner particles each comprising at least a binder resin, a colorant and a release agent, and a low-crystalline aromatic metal compound present at surfaces of the toner particles. The toner has an average circularity of at least 0.955, and the low-crystalline aromatic metal compound has an X-ray diffraction characteristic free from peaks exhibiting a measurement intensity of at least 10000 cps and a half-value half-width of at most 0.3 deg. in a range of measurement angles 2&thgr; of 6 to 40 deg. Because of the low crystallinity, the aromatic metal compound is uniformly applied onto the toner particle surfaces to stabilize the chargeability and transferability of the toner.

A magenta toner for developing an electrostatic image is formed of magenta toner particles containing at least a binder resin and a magenta pigment. The magenta pigment is a solid solution pigment comprising C.I. Pigment Red 122, C.I. Pigment Red 202 and C.I. Pigment Violet 19. The magenta toner particles are preferably formed by suspension polymerization of a polymerizable monomer mixture including a polymerizable monomer and the solid solution pigment in an aqueous medium.

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Kamakura, Japan

Tatsuhiko Chiba