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Patent Abstract
Patent number: 10139745
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Atsushi Nakamoto (Tokyo, JP), Makoto Fukatsu (Suntou-gun, JP), Manami Haraguchi (Yokohama, JP), Masayoshi Kato (Tokyo, JP), Kei Inoue (Yokohama, JP), Kazuyuki Sato (Yokohama, JP)

A toner according to the present disclosure maintains high transfer efficiency for the long term and obtains images which are not affected by toner base particles easily, which exhibit excellent charge stability, and which exhibit less fogging, wherein the toner is obtained by making inorganic fine particles and charge control particles, which satisfy specific conditions, present on the surfaces of toner base particles so as to satisfy a specific coverage relationship.

Process for producing toner
Patent number: 6207339
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Masayoshi Kato (Iruma, JP), Hitoshi Kanda (Yokohama, JP), Tatsuya Nakamura (Mishima, JP)

A process for producing a toner has the steps of, polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant, in an aqueous dispersion medium to form colored polymer particles, and thereafter washing the colored polymer particles, followed by dewatering to prepare wet colored polymer particles, subjecting the resultant wet colored polymer particles to substantial removal of the water held by the wet colored polymer particles, by means of a dryer making use of hot air to obtain toner particles, and drying the toner particles under reduced pressure by means of a vacuum dryer so that polymerizable monomers remaining in the toner particles come to be in a residue of 200 ppm or less.

Developer for developing electrostatic image, image forming method, electrophotographic apparatus, apparatus unit, and facsimile apparatus
Patent number: 5319424
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Koichi Tomiyama (Kawasaki, JP), Masayoshi Kato (Iruma, JP), Tsutomu Kukimoto (Yokohama, JP), Hiroshi Yusa (Yokohama, JP), Kiyoko Tsuchiya (Yokosuka, JP)

A developer for developing an electrostatic image has a toner, fine resin particles with a surface shape sphericity .psi. of from 0.90 to 0.50, and fine inorganic particles.

Magnetic developer for developing electrostatic images
Patent number: 5364720
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Akihiko Nakazawa (Kanagawa, JP), Masayoshi Kato (Iruma, JP), Manabu Ohno (Funabashi, JP), Nobuyuki Okubo (Yokohama, JP), Shunji Suzuki (Yokohama, JP)

A magnetic developer for developing electrostatic images is constituted by magnetic toner particles, each containing a binder resin having a melt viscosity of at most 5.0.times.10.sup.6 poise at C. and a magnetic material. The magnetic material is blended with a proportion (C) [wt. %] of inorganic fine particles based on the magnetic material to carry 0.2-5 wt. % of the inorganic fine particles secured to the magnetic material surface. The magnetic material has a specific surface area (A) [m.sup.2 /g] before securing of the inorganic fine particles and is provided with an increase in surface area (B) [m.sup.2 /g] by the securing of the inorganic fine particles; wherein the parameters A, B and C satisfy the following formulae (1) and (2): As a result, the magnetic developer is provided with an improved low-temperature fixability without causing problems accompanying the use of a low-temperature softening binder resin, such as deterioration of anti-offset characteristic, storage characteristic, developing characteristic.

Magnetic toner, magnetic developer, apparatus unit, image forming apparatus and facsimile apparatus
Patent number: 5424810
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Koichi Tomiyama (Kawasaki, JP), Hiroyuki Suematsu (Yokohama, JP), Masayoshi Kato (Iruma, JP), Hiroshi Yusa (Yokohama, JP), Takakuni Kobori (Kawasaki, JP)

A magnetic toner for electrophotography is composed from a binder resin and a silicon-containing magnetic iron oxide. The magnetic toner has a weigh-average particle size o at most 13.5 .mu.m and has a particle size distribution such that it contains o more than 50 wt, % of magnetic toner particles having a particle size of at least 12.7 .mu.m. The magnetic toner is able to show high developing performances because of richness in fine particles and is also provided with an improved environmental stability because the magnetic iron oxide used therein contains 0.5-4 wt, % silicon (based on total iron content) and has a specific silicon distribution such that the magnetic iron oxide has a total silicon content (A), a silicon content (B) dissolved together with the magnetic iron oxide when the magnetic iron oxide is dissolved up to 20 wt, % dissolution of iron, and a superficial silicon content (C), satisfying relations of B/A=44-84% and C/A=10-55%. The performances are enhanced if the magnetic toner is blended with additives such as inorganic fine powder or resin fine particles.