Canon Kabushiki Kaisha

Eriko Yanase

Michihisa Magome

Takashi Matsui

Tomohisa Sano

Shuichi Hiroko

Tadashi Dojo

Akira Sakakibara

Tatsuhiko Chiba

Takeshi Kaburagi

Tatsuya Nakamura

Akira Hashimoto

Keiji Komoto

Tsuyoshi Takiguchi

Atsushi Tani

Masayoshi Shimamura

Yoshitaka Suzumura

Satoshi Otake

Minoru Ito

Kazunori Saiki

Nene Dojo

Yusutaka Akashi

An image-forming method is provided which can provide stable image density irrespective of use environments and does not cause image defects such as fogging, tailing, or transfer voids, even when being applied to a developing sleeve with a reduced diameter. In the image-forming method, a latent image bearing member and a toner bearing member bearing a magnetic toner on its surface and having inside a unit for generating a magnetic field are placed with a predetermined interval, and an alternating field is applied between the latent image bearing member and the toner bearing member, and an electrostatic latent image borne by the latent image bearing member is developed with the magnetic toner. The toner bearing member has a specific diameter, and the magnetic toner has a specific circularity and a specific compressibility. The total energy of the toner measured with a powder flowability measuring apparatus satisfies a specific value.

Image-forming method, magnetic toner, and process unit

To solve a thin image density and sweeping occurring when a toner carrying member having a small diameter is used, provided is an image-forming method including: a charging step; an electrostatic latent image-forming step; a developing step; a transferring step; and a fixing step, in which a magnetic toner to be used in the method has a specific weight average particle diameter (D4); the magnetic toner has a specific intensity of magnetization in a specific magnetic field; and a surface free energy of a surface of the magnetic toner and a surface free energy of a surface of a toner carrying member to be used in the method satisfy specific relationships.

Magnetic toner and image-forming method

In a magnetic toner which has magnetic toner base particles containing at least a binder resin and a magnetic material, and an inorganic fine powder, (i) the magnetic toner has an average circularity of from 0.950 or more to 1.000 or less, (ii) the magnetic toner has a compressibility of 30 or less, and (iii) the magnetic toner contains boron nitride particles having a median diameter (D50) of from 0.5 &#x3bc;m or more to 8.0 &#x3bc;m or less, as the inorganic fine powder in an amount of from 0.05 part by mass or more to 1.00 part by mass or less based on 100 parts by mass of the magnetic toner base particles. This provides a magnetic toner with which stable image density can be achieved without regard to service environment and which do not cause any image defects such as fog.

Magnetic toner

In a toner containing at least a binder resin, a colorant, an ester compound and a low-melting material, the ester compound is an ester of dipentaerythritol with a carboxylic acid having 18 or more to 25 or less carbon atoms, and, where the melting point of the ester compound is represented by Tm(&#xb0; C.) and the melting point of the low-melting material is represented by Tm(&#xb0; C.), the toner satisfies the relationship of:+5.

Toner

A magnetic toner is disclosed including magnetic toner particles containing at least a binder resin and a magnetic powder. The magnetic powder contains a specific amount of phosphorus elements, and a specific amount of silicon elements, based on the iron element, with the ratio of the phosphorous element to the silicon elements being in a specific range, and has a specific volume-average particle diameter, a specific saturation magnetization in a specific magnetic field, and a specific residual magnetization. The magnetic toner can realize high image density and reduce fog and spots around line images regardless of environmental variation, and is superior in durability, and besides, can achieve small toner consumption.

An object of the present invention is to provide a toner excellent in durability and storage stability, and having good fixing performance in a wide fixing temperature region even at a high process speed. According to the present invention, there is provided a toner containing: a binder resin; a colorant; and a polyester resin, in which: I) the polyester resin contains at least, as a main component, polyester obtained by subjecting a monomer composition containing an alcohol selected from aliphatic diols each having 2 to 22 carbon atoms and a carboxylic acid selected from aliphatic dicarboxylic acids each having 2 to 22 carbon atoms to a polycondensation reaction; and II) a region having a lamellar structure is present at a surface layer of the toner.

To provide a magnetic toner which has superior low-temperature fixing performance and pressure roller anti-staining properties even in various forms of use, has been kept from image defects such as image non-uniformity even during long-time image reproduction and can achieve high-level image quality. In a magnetic toner having toner particles containing at least a binder resin and a magnetic material, the activation energy Ea (kJ/mol) that is determined from a shift factor aTin a master curve of the toner, prepared when 120&#xb0; C. is set as reference temperature, and the activation energy Eb (kJ/mol) that is determined from a shift factor aTin a master curve of the toner, prepared when 150&#xb0; C. is set as reference temperature, satisfy Expression (1), and the Ea is 110 kJ/mol or less:1.00&#x2266;Ea/Eb&#x3c;1.20&#x2003;&#x2003;(1).

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

A magnetic toner is provided having at last a binder resin and a magnetic material and having a weight-average particle diameter of 3 &#x3bc;m to 10 &#x3bc;m. The magnetic material has been surface-treated with a low-softening substance (A), and has a compressibility of 35 or more which can be calculated according to a specific expression. The softening point of the magnetic toner is from 40&#xb0; C. to 85&#xb0; C. in measurement by a flow tester. The magnetic toner has a resin component containing 1% to 60% by weight of a tetrahydrofuran-insoluble matter. This magnetic toner is superior in low-temperature fixing performance and has good fixing performance in a broad fixing range.

Magnetic toner, and image forming method

A developing method is provided in which a developer is carried on a developer carrying member, a thin layer of the developer is formed thereon and a latent image on a latent image bearing member is developed with a developer. The developer is composed of magnetic toner particles containing a binder resin and a magnetic powder. The magnetic powder has a saturation magnetization of 67.0 Am/kg to 75.0 Am/kg in a magnetic field of 79.6 kA/m (1,000 oersteds) and has a residual magnetization of 4.5 Am/kg or less. In the surface profile of the conductive resin coat layer of the developer carrying member, the relationship 1.00&#x2266;S/A&#x2266;1.65 is satisfied where S is a surface area of regions zoned by an area A of microscopic unevenness regions from which parts exceeding a reference plane by 0.5&#xd7;r (r: weight average particle diameter (&#x3bc;m) of a toner used) or more have been excluded.

Developing method and developing assembly

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.

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.

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Suntou-gun, Japan

Eriko Yanase