Mitsubishi Chemical Corporation

Masakazu Sugihara

Teruyuki Mitsumori

Hiroaki Takamura

Kozo Ishio

Shiro Yasutomi

Shiho Sano

Yumi Hirabaru

Masaya Oota

Takeshi Oowada

Teruki Senokuti

Teruki Senokuchi

Masaya Ota

Takuya Nishikiori

Yuzo Kaneko

Takeshi Owada

A method of forming an image including an electrophotographic photoreceptor and a toner, wherein a photosensitive layer in the electrophotographic photoreceptor includes an undercoat layer including metal oxide particles, a charge generation layer including hydroxygallium phthalocyanine, and a charge transport layer, and the toner contains toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 &#x3bc;m to 7.0 &#x3bc;m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m satisfies&#x2014;0.0517EXP(22.4/Dv50)&#x2266;Dns&#x2266;0.233EXP(17.3/Dv50) where Dv50 is the volume median diameter (&#x3bc;m) of the toner, and Dns is the percentage in number of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m.

Method of image forming with a photoreceptor and toner

An object of the invention is to provide a toner which is effective in improving image quality while inhibiting white-background fouling, residual-image phenomenon (ghost), blurring (suitability for solid printing), and the like that occur depending on the proportion of a fine powder having a particle diameter not larger than a specific value, and which has satisfactory removability in cleaning, mitigates problems concerning fouling, etc. in long-term use even on a high-speed printer, and attains excellent image stability. Another object is to provide an image-forming apparatus and a toner cartridge each employing the toner. The invention provides a toner for electrostatic-image development satisfying all of the following (1) to (4) or a toner for electrostatic-image development which is a toner containing a charge control agent and satisfying all of the following (5) to (7). The invention further provides an image-forming apparatus and a toner cartridge each employing the toner. (1) To have a volume-median diameter (Dv50) of from 4.0 &#x3bc;m to 7.5 &#x3bc;m. (2) To have an average degree of circularity of 0.93 or higher. (3) A volume-median diameter (Dv50) of the toner and population number % of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m (Dns) in the toner satisfy the relationship Dns&#x2266;0.233 EXP(17.3/Dv50). (4) To have a coefficient of variation in number of 24.0% or lower. (5) To have a volume-median diameter (Dv50) of from 4.0 &#x3bc;m to 7.5 &#x3bc;m. (6) A volume-median diameter (Dv50) of the toner and population number % of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m (Dns) in the toner satisfy the relationship Dns&#x2266;0.233 EXP(17.3/Dv50). (7) When the charge control agent on the toner surface is cleaned, the resultant depressions have an average diameter of 500 nm or smaller.

Toners for electrostatic-image development, cartridge employing toner for electrostatic-image development, and image-forming apparatus

A method of forming an image on a substrate with an electrophotographic photoreceptor and a toner, a photosensitive layer of the electrophotographic photoreceptor contains a resin having a structural unit represented by the following formula (A) the toner containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 &#x3bc;m to 7.0 &#x3bc;m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m satisfies following formula (1)&#x2266;0.233EXP(17.3/50)&#x2003;&#x2003;(1).

Image forming apparatus

An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 &#x3bc;m to 7.0 &#x3bc;m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m satisfies the following formula (1):&#x2266;0.233 EXP(17.3/50)&#x2003;&#x2003;(1).

To provide an image forming apparatus which is able to improve image quality while suppressing soiling of image white parts, scattering in the apparatus, streaks, fading, etc. due to non-uniformity in the particle size distribution of a toner or mismatching between a toner and a photoreceptor, and which has good cleaning properties, and even when a high speed printing machine is used, is able to reduce a problem of soiling, etc. in long-term use and provide excellent image stability. An image forming apparatus comprising an electrophotographic photoreceptor having a photosensitive layer on an electroconductive substrate, and a toner for developing an electrostatic charge image, wherein the photosensitive layer of the electrophotographic photoreceptor contains a phthalocyanine obtained via an acid paste step; the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 &#x3bc;m to 7.0 &#x3bc;m; and the relationship between the volume median diameter (Dv50) and the percentage in number (Dns) of toner particles having a particle diameter of from 2.00 &#x3bc;m to 3.56 &#x3bc;m satisfies the following formula (1):&#x2266;0.233 EXP(17.3/50)&#x2003;&#x2003;(1).

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Joetsu, Japan

Masakazu Sugihara