Sharp Kabushiki Kaisha Corporation

Toshihiko Murakami

Tadashi Nakamura

Hitoshi Nagahama

Yoshiaki Akazawa

Katsuaki Sumida

Junichi Saito

Yasuharu Morinishi

Satoshi Ogawa

Toshihisa Ishida

Tadayuki Sawai

Katsuru Matsumoto

Hirofumi Sakita

Yuichiro Takesue

Sayaka Fujita

Eiji Tenjiku

Kanshiro Okamoto

Takeaki Ohuchi

Takeaki Ouchi

Tatuo Imafuku

The master comprises a polyester resin as a binder resin and a carbon black as a colorant having a primary particle size of 10 nm to 100 nm, is blended with 30 to 60 parts by weight of the carbon black, has a lightness L* of 20 or more; and the reflectance A at 400 nm thereof and the reflectance B at 700 nm thereof fall within the range satisfying the relation given by the following formula [1]:0.5&#x3c;&#x3c;5[1] The carbon black in the toner can be made to be present stably in the conditions such that the carbon black has a small primary particle size and is homogeneously dispersed.

Master batch and toner for use in electrophotography

A toner for developing electrostatic latent images comprises: a colorant; a polyester resin; a negative charge controlling agent comprised of a chromium complex compound; and a positive charge controlling agent, wherein the polyester resin has an acid value Z of 15 to 33 mgKOH/g, a hydroxyl value Y of 4 to 17 mgKOH/g and a number-average molecular weight (Mn) of 5200-7000.

Toner for developing electrostatic latent images, method for forming images and apparatus for forming images

The present invention provides a toner which does not cause problems on generation of an offensive odor and a stain on a surface of a cooling unit and which is excellent in an offset resistance, a low temperature fixability and an environmental dependency. In the toner for developing an electrostatic latent image comprising a polyester resin as a principal component which is formed by reacting dicarboxylic acids of a polybasic acid with diols of a polyhydric alcohol, dimethyl phthalate remaining in the polyester resin described above without reacting has a content of 0.1 % by weight or less.

Toner for developing electrostatic latent image

A toner for developing electrostatic latent images comprises a polyester resin and an electric charge controlling agent containing a chromium complex compound, wherein the polyester resin has an acid value Z of 15 to 30 (15<Z&lE;30) mgKOH/g and a hydroxyl value Y of 4 to 17 (4&lE;Y&lE;17) mgKOH/g.

Toner for developing electrostatic latent images and image-forming apparatus

An electrophotographic toner is made up of toner particles composed of irregularly-shaped core particles made chiefly of binder resin, and surface-modifying fine particles which are first dispersed over and attached to the surface of the core particles, and then affixed or formed into a film thereon. The BET specific surface area, based on N.sub.2 adsorption, of the toner particles is less than 0.64 times the BET specific surface area of the core particles and surface-modifying fine particles combined together. Further, this value is 1.07 times the BET specific surface area of hypothetical toner particles which are perfect spheres. Consequently, the toner is not prone to problems such as filming, toner scattering, and fogging which are caused by peeling, separation, etc. of the surface-modifying fine particles, nor to poor cleaning due to spherical toner particles. Further, since the toner is manufactured with a quantitative grasp of the state of modification of the surface of the core particles by the surface-modifying fine particles, it is a toner in a stable state.

Electrophotographic toner and method of manufacturing same

An image forming device includes an optical system for forming an electrostatic latent image on a photosensitive body by exposure of an original in light, a development system for developing the electrostatic latent image, and a control system for controlling the optical system and the development system. The control system detects the concentration of a toner in a developing agent tank, calculating a difference between the detected toner concentration and a predetermined toner concentration, replenishing the toner to the developing agent tank until the detected toner concentration makes a recovery to the predetermined toner concentration, clocking a time period for the recovery and controlling at least one of the amount of the exposure light and the amount of the toner adhering to a photosensitive body based on the clocked time period for the recovery.

Image forming apparatus having a toner concentration controlling

The extra-fine toner arising in the toner producing process, is returned to the mixing step where it is mixed again with the binder resin and the coloring agent, and the compound is sent out to the kneading step. In this procedure, the particle size of the binder resin is set in accordance with the particle size and blending amount of the extra-fine toner, the kind of the binder resin, etc. By using the binder resin having the thus determined particle size, the amount of the binder to be fed into the mixer or the amount of the compound ejected from the mixer are maintained uniform. Further, when the extra-fine toner is mixed with the starting materials, the blending ratio of the extra-fine toner to the starting material is set between 5 wt. % and 10 wt. %, and the blending ratios of the charge control agent and the coloring agent are set equal to those of the normal process where no recycled toner is added.

Toner producing method using recycled extra-fine toner particles

A method for preparing an electrophotographic printing-use developer by mixing components of toner material, fusing and kneading the toner material, and then crushing and classifying the toner material, includes the step of arranging carbon black which is one of the components of the toner material to contain water before the mixing step. This arrangement permits even dispersion of water in the mixture of the components, prevents the flowability of the mixture from being lowered, and achieves stable kneading. Therefore, improved dispersion of the components is achieved. Since water adsorption is stable, water-treated carbon showing reduced water segregation is obtained. Consequently, high quality less foggy images with high resolution are obtained.

Method for preparing developer for use in electrophotographic printing

The electrostatic charge image-developing toner contains a colorant, a binder resin, and polyethylene having a melt viscosity of 22000 to 26800 mPa.multidot.s at 140.degree. C. This electrostatic charge image-developing toner prevents an offset phenomenon on the surface of a fixing roller, and does not adhere to and fuse on a photoreceptor drum to cause no stripy and dotwise stain on a reproduced image, that is, preventing a so-called filming phenomenon. The toner also prevents an offset phenomenon on the photoreceptor drum.

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Kashiba, Japan

Toshihiko Murakami