Ricoh Company, Ltd.

Yoshimichi Ishikawa

Atsushi Yamamoto

Takuya Kadota

Tsuyoshi Nozaki

Yoshihiro Mikuriya

Tomoharu Miki

Kazuoki Fuwa

Tomohiro Fukao

Katsunori Kurose

Chiyoshi Nozaki

Masahide Inoue

Mitsuyo Matsumoto

Hideaki Yasunaga

Masayuki Hagi

Hiroyuki Murakami

Minoru Nakamura

Hiroaki Kato

Yuta Takeuchi

Naoki Nakatake

Takayuki Nakamura

Hiroaki Katoh

Masashi Nagayama

Hiroyuki Kishida

Tetsumaru Fujita

Yuji Nagatomo

Shintaro Yamada

Manabu Hamada

Takeshi Yamashita

Keiichiro Juri

Saori Yamada

Yasuhide Matsuno

Shin Murayama

Tetsushi Sakuma

Hidekazu Shono

Masahiro Seki

Chieko Yamazaki

Tsuyoshi Nokaki

A carrier for forming an electrophotographic image is provided. The carrier includes a core particle comprising a manganese-based ferrite particle having an apparent density of from 2.0 to 2.2 g/cmand a magnetization of from 44 to 52 emu/g in a magnetic field of 500 Oe; and a coating layer coating a surface of the core particle. The coating layer contains a carbon black, an inorganic particle A, and an inorganic particle B. The inorganic particle A and the carbon black each have a concentration gradient in a thickness direction of the coating layer. A concentration of the inorganic particle A increases toward a surface of the coating layer, and a concentration of the carbon black decreases toward the surface of the coating layer.

Carrier, developer, method, and apparatus for forming electrophotographic image, and process cartridge

A toner is provided. The toner includes toner particles each including a binder resin and a release agent. From 20% to 80% by number of the toner particles satisfy the following formula (1) and (2):2/3&#x2264;&#x2264;1.5&#x2003;&#x2003;(1)1/3&#x2264;&#x2264;1.0&#x2003;&#x2003;(2)wherein Dv represents a volume average particle diameter of the toner particles; and T and R represent the longest cross-sectional diameters of each toner particle and the release agent contained therein, respectively, measured by observing cross-sections of the toner particles with scanning transmission electron microscope.

Toner, developing device, and process cartridge

A toner is provided. The toner includes a crystalline resin and a non-crystalline resin, and has a thermal property such that when the toner is heated after being firstly heated to 60&#xb0; C. followed by cooling in differential scanning calorimetry (DSC), the toner has a clear peak specific to melting of the crystalline resin at a temperature T1, and when the toner is heated after being firstly heated to 80&#xb0; C. followed by cooling in the differential scanning calorimetry (DSC), the toner does not have a clear peak specific to melting of the crystalline resin at a temperature not higher than the temperature T1.

Toner, and image forming method, process cartridge, and image forming apparatus using the toner

A toner is prepared by wet granulation methods, including a monoester wax having carbon atoms of from 36 to 46 on average as a release agent. The toner has a DSC endothermic energy amount (&#x394;H1) originating from the wax of from 10 to 12 mJ/mg and a DSC endothermic energy amount (&#x394;H2) originating from the wax of from 0.6 to 0.9 times as much as &#x394;H1 after a part of the wax is separated by hexane extraction from the toner. The hexane extraction includes mixing 1 g of the toner in 7 ml of n-hexane to prepare a mixture; stirring the mixture at 120 rpm for 1 min by a pot mill to prepare a dispersion; and subjecting the dispersion to suction filtration.

Toner

A toner including: toner particles each including a toner base particle and an external additive attached thereon, where the toner base particle includes a binder resin and a colorant, wherein the toner base particles each have protrusions on a surface thereof, an average of lengths of long sides of the protrusions is 0.10 &#x3bc;m or more but less than 0.50 &#x3bc;m, a standard deviation of the lengths of the long sides of the protrusions is 0.2 or less, a coverage rate of the protrusions on the surface of the toner base particle is 10% to 90%, and the external additive includes fine inorganic particles whose surfaces have been treated with an amino group-containing silane coupling agent.

Toner and image forming apparatus

An image forming apparatus is provided which includes an image bearer, a charger, an irradiator, a developing device to develop an electrostatic latent image on the image bearer with a toner to form a toner image, a transfer device to transfer the toner image onto a transfer medium, and a cleaner to remove toner particles remaining on the image bearer without being transferred. The toner includes a mother particle including a binder resin and a colorant and one or more external additives. At least one of the external additives includes primary particles having a number average particle diameter in the range of 0.05 to 0.30 &#x3bc;m. The cleaner includes an elastic body blade having a contact part with the image bearer. The contact part has a surface elastic modulus in the range of 15 to 25 N/mmand a surface friction coefficient in the range of 0.5 to 0.7.

Image forming apparatus and process cartridge

A toner including: a core particle containing at least a binder resin, a colorant and a releasing agent; and a shell on a surface of the core particle, wherein the toner gives a supernatant having a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is formed after 3 g of the toner is added to 40 g of ion-exchange water containing 0.5% by mass of sodium dodecyl sulfate, followed by stirring for 90 min and by irradiating with ultrasonic waves of 20 kHz and 80 W for 5 min, and a liquid containing the toner dispersed therein is centrifugated at 3,000 rpm for 5 min.

Latent electrostatic image developing toner

An electrostatic image developing toner including: toner base particles each including a binder resin and a colorant; and an external additive, wherein the toner base particles each have protrusions on a surface thereof, an average of lengths of long sides of the protrusions is 0.1 &#x3bc;m or more but less than 0.5 &#x3bc;m, a standard deviation of the lengths of the long sides of the protrusions is 0.2 or less, a coverage rate of the protrusions on the surface of each toner base particle is 10% to 90%, and the external additive includes an external additive (A) which is fine inorganic particles each containing silicone oil.

Electrostatic image developing toner, image forming apparatus, image forming method, and process cartridge

Image forming apparatus, image forming method and process cartridge

A developing roller, including: a shaft containing a metal; an elastic layer on a circumference of the shaft; and a surface layer on a circumferential surface of the elastic layer, wherein the surface layer contains: a polyurethane which is a reaction product between a fluoroethylene vinyl ether copolymer and an isocyanurate form of an isocyanate; and particles having an average primary particle diameter of 5 nm to 30 nm, and wherein the polyurethane has a peak intensity ratio of a NCO group to a hydroxyl group of 5.6 to 8.8 in an infrared absorption spectrum obtained by an attenuated total reflection method.

Developing roller, developing device, process cartridge, and image forming apparatus

To provide a toner comprising: a binder resin, a colorant, and a releasing agent, wherein the toner has a core shell structure, and wherein the core contains at least one resin selected from the group consisting of a hybrid resin and a polyester resin, where the hybrid resin is a resin in which a polyester resin and a vinyl resin are chemically bonded to each other, and the shell contains a resin prepared by polymerizing at least a styrene monomer and an ester monomer represented by the following General Formula (1): where, 'n' is 2 or 3, 'X' is any of 0 to 9, Ris a hydrogen atom, or an alkyl group, and Ris a hydrogen atom, an alkyl group, or a phenyl group.

Toner, image forming apparatus, and process cartridge

Disclosed is a non-magnetic toner for use in developing electrostatic toner image, wherein the toner is produced by a toner production method that includes: dispersing in an aqueous medium an organic dispersion liquid that comprises in an organic solvent a pigment, a binder resin and/or a binder resin precursor, and a releasing agent; removing the organic solvent to prepare a dispersion slurry in which toner particles are dispersed in the aqueous medium; heating the dispersion slurry to a temperature equal to or higher than the melting point of the releasing agent; and washing the toner particles.

Toner and method for producing the same, toner container, developer, image forming apparatus and process cartridge

A method for producing colored resin particles including: dissolving or dispersing at least binder resin and colorant in organic solvent to prepare oil phase; dissolving resin A and basic compound in aqueous medium to prepare aqueous phase, the resin A having solubility &#x3c;2.0 g/100 g water having temperature 25&#xb0; C. and pH 3.0 and solubility &#x2267;2.0 g/100 g water having temperature 25&#xb0; C. and pH 10.0; dispersing the oil phase in the aqueous phase to prepare core particle dispersion liquid; dispersing resin particles in aqueous medium to prepare resin particle dispersion liquid, and adding the resin particle dispersion liquid to the core particle dispersion liquid so that the resin particles are attached onto the core particles, to prepare dispersion liquid containing particles each having the core particle and the resin particles attached thereonto; removing the organic solvent from the dispersion liquid; washing the particles; and drying the particles.

Method for producing colored resin particles, colored resin particles, developer, image forming apparatus, image forming method, and process cartridge

A toner including: a core particle; and fine resin particles, the core particle containing at least a binder resin, a releasing agent and a colorant, wherein the toner is in shape of particles, and each toner particle has a sea-island structure having the core particle and island portions, which are convex portions formed from the fine resin particles on surface of the core particle, wherein the binder resin contains first and second resins, and the fine resin particles are made of third resin, wherein the first resin is crystalline resin, and the second and third resins are non-crystalline resin, wherein the second resin has glass transition temperature (Tg2) and the crystalline resin has melting point (Tc1) where Tg2 is higher than Tc1, and wherein the third resin has glass transition temperature (Tg3) and the toner has glass transition temperature (Tgt) wherein Tg3 is higher than Tgt.

Toner, developer and method for producing toner

An electrostatic image developing toner including: toner particles each containing binder resin and colorant; and an external additive supported on the toner particles, wherein the toner particles each have protrusions on surface thereof, average of lengths of long sides of the protrusions is 0.10 &#x3bc;m or more but less than 0.50 &#x3bc;m, standard deviation of the lengths of the long sides of the protrusions is 0.20 or less, coverage rate of the protrusions on the surface of each toner particle is 30% to 90%, the external additive includes at least two different particles including external additive (A) and one or more external additives (B), external additive (A) has longest average primary particle diameter among the external additives and charged to have the opposite polarity to the toner particles, and at least one of the external additives (B) is charged to have the same polarity as the toner particles.

Growing community of inventors

Itami, Japan

Yoshimichi Ishikawa