Ricoh Company, Ltd.

Keiji Makabe

Masahide Yamada

Yukiko Nakajima

Daiki Yamashita

Yoshitaka Yamauchi

Yoshihiro Moriya

Taichi Nemoto

Suzuka Amemori

Akiyoshi Sabu

Tsuneyasu Nagatomo

Shinya Nakayama

Kohsuke Satoh

Atsushi Yamamoto

Daichi Hisakuni

Toyoshi Sawada

Kenji Yoneda

Hiroshi Yamashita

Minoru Masuda

Tsuyoshi Sugimoto

Yoshihiro Norikane

Satoyuki Sekiguchi

Yasutada Shitara

Junichi Watanabe

Hideyuki Santo

Daisuke Asahina

Tatsuya Morita

Akinori Saito

Kazumi Suzuki

Kousuke Suzuki

Yohichiroh Watanabe

Shingo Sakashita

Yuka Mizoguchi

Kohsuke Nagata

Susumu Chiba

Yohichi Kitagawa

Shintaro Akiyama

Watanabe Yohichiroh

An image forming apparatus is provided that includes: an image bearer; a charger; an irradiator; a developing device containing a toner; and a transfer device. The image bearer has a Martens hardness of from 185 to 250 N/m. The toner satisfies a relation 0.13&#x2264;X/Dn&#x2264;0.16, where X [&#x3bc;m] represents an average value of an amount of deformation of the toner by micro-indentation at when a load reaches 3.00&#xd7;10N at a loading rate of 3.0&#xd7;10N/sec under an environment of 32 degrees C. and 40% RH, and Dn [&#x3bc;m] represents a number average particle diameter of the toner. The toner contains an external additive comprising silica particles and particles composed mainly of strontium titanate. The particles composed mainly of strontium titanate further contain a third element M selected from the group consisting of La, Mg, Ca, Sn, and Si.

Image forming apparatus and image forming method

A toner including toner particles, each toner particle including a toner base particle, and inorganic particles, wherein the inorganic particles include particles of a fluorine-containing aluminium compound, and a liberation ratio of the inorganic particles is 10% or greater but 60% or less.

Toner, toner stored unit, developer, developer stored unit, and image forming apparatus

A toner including toner base particles each including a binder resin and a colorant, and external additive, wherein the toner satisfies conditions (a), (b), and (c) below:

Toner, image forming apparatus, image forming method, and process cartridge

A toner is provided. The toner includes toner particles each including a mother particle and external additive particles covering the mother particle. In a SEM image of the toner, toner particles having a ratio Sd/St of from 5% to 50% are present at a frequency of 15% or more, where Sd representing an area of a largest recessed portion D of each toner particle and St representing whole area of the toner particle, Sd and St determined from the SEM image magnified and binarized to discriminate recessed portions and projected portions of the toner particle from each other. An external additive coverage rate Ca at the largest recessed portion D is from 30% to 100%.

Toner, developer, toner storage unit, and image forming apparatus

A toner includes a binder resin including a copolymer resin containing structural units derived from crystalline and non-crystalline resins, respectively. Spin-spin relaxation time (t50) of the toner at 50&#xb0; C. measured by pulse NMR is &#x2266;0.05 msec., spin-spin relaxation time (t130) at 130&#xb0; C. when warmed from 50&#xb0; C. to 130&#xb0; C. is &#x3e;15 msec., and spin-spin relaxation time (t'70) at 70&#xb0; C. when cooled from 130&#xb0; C. to 70&#xb0; C. is &#x2266;1.00 msec. A binarized image obtained by binarizing a phase image of the toner observed by a tapping mode AFM based on intermediate value between maximum and minimum phase difference values in the phase image includes first phase difference images constituted by large phase-difference portions and a second phase difference image constituted by a small phase-difference portion. The first phase difference images are dispersed in the second phase difference image. The dispersion diameter of the first phase difference images is 150 nm or less.

Toner, developer, image forming apparatus, and image forming method

A toner includes a base particle; and an external additive covering the base particle. The toner includes a tetrahydrofuran (THF)-insoluble component having a glass transition temperature determined from a DSC curve when heated for the second time of from &#x2212;50&#xb0; C. to 10&#xb0; C. and an average circularity not greater than 0.98, and satisfies the following relation:&#x2212;0.025&#xd7;&#x2266;1.80

Toner, developer, image forming apparatus, and process cartridge

A toner includes a base particle comprising a crystalline polyester resin; and an external additive which is a group of silica particles having a number-average particle diameter of from 0.01 &#x3bc;m to 0.11 &#x3bc;m on the surface of the toner. A number ratio of the silica particles having a circularity not less than 0.8 is 20% or more in the total number of the silica particles.

Toner, developer, and image forming apparatus

A toner is provided. The toner includes a crosslinked polyester resin, and a block copolymer. The crosslinked polyester resin includes a diol component, which includes an aliphatic diol component having 3 to 10 carbon atoms in an amount of 50% by mole, and a crosslinked component, which is at least one of a crosslinked component of an aliphatic alcohol having three or more valences and a crosslinked component of an aliphatic acid having three or more valences, and the block copolymer includes a crystalline segment (a) and a non-crystalline segment (b). The toner has a first glass transition temperature (Tgst) of from 20&#xb0; C. to 50&#xb0; C., which is determined by subjecting the toner to differential scanning calorimetry (DSC) and measuring a glass transition temperature in a first temperature rising process in the differential scanning calorimetry (DSC).

Toner for image formation, and developer and image forming apparatus using the toner

Toner contains a binder resin containing a crystalline resin having a urethane and/or urea bonding; and a colorant, wherein in a diffraction spectrum of the toner as measured by an X-ray diffraction instrument, a ratio {C/(C+A)} of an integral intensity C of the spectrum derived from the crystalline structure to an integral intensity A of the spectrum derived from the non-crystalline structure is 0.12 or greater, wherein the toner satisfies the following relation 1: T1&#x2212;T2&#x2266;30&#xb0; C. (Relation 1), where T1 represents the maximum endothermic peak in the first temperature rising from 0&#xb0; C. to 100&#xb0; C. at the temperature rising rate of 10&#xb0; C./min and T2 represents the maximum exothermic peak in the first temperature falling from 100&#xb0; C. to 0&#xb0; C. at the temperature falling rate of 10&#xb0; C./min as T1 and T2 are measured by diffraction scanning calorimetry (DSC).

Toner, development agent, image forming apparatus, and process cartridge

An electrophotographic toner including: a binder resin, wherein the binder resin has one glass transition temperature Tg and the glass transition temperature Tg of the binder resin is within 25&#xb0; C. to 65&#xb0; C. as measured in second heating with a differential scanning calorimeter at a heating rate of 5&#xb0; C./min, and wherein a phase image of the binder resin obtained with an atomic force microscope (AFM) of tapping mode contains first phase difference regions and a second phase difference region such that the first phase difference regions are dispersed in the second phase difference region, where the first phase difference regions correspond to greater phase difference regions and the second phase difference region corresponds to a smaller phase difference region when an intermediate value between a maximum value and a minimum value of the phase differences is used as a threshold.

Electrophotographic toner, developer containing the toner, and image forming apparatus

A resin for toner contains a polyhydroxycarboxylic acid skeleton and a rigid skeleton.

Resin for toner, toner using the resin, and development agent using the toner

A resin for use in toner is provided. The resin comprises an oligomer segment and a soft segment. The oligomer segment comprises a polyhydroxycarboxylic skeleton and an aromatic diol skeleton.

Resin for use in toner, toner using the resin, developer using the toner, image forming apparatus and method using the toner, and method of manufacturing resin

A toner including a binder resin having a glass transition temperature (Tg) observed at least at one point from 25 to 65&#xb0; C. in a differential scanning calorimeter at a rate of temperature increase of 5&#xb0; C./min, wherein the toner has a structure in which a structure appearing as a high phase difference image is dispersed in a structure appearing as a low phase difference image in a two-dimensional phase difference image observed by tapping mode AFM, and an X-ray diffraction chart in which a peak originated from an crystalline resin is observed in a range of a diffraction angle 2&#x3b8; of from 20 to 25&#xb0;, and wherein a ratio (I1/I2) of an intensity of the peak originated from an crystalline resin to an intensity (I2) of a halo originated from an amorphous composition is from 0.2 to 1.

Toner and developer

The toner includes a pigment; and a block copolymer having a polyester block A including a residual group of a hydroxycarboxylic acid, and a polyester block B including an anionic group. When cross-section of the block copolymer is observed by a tapping mode atomic force microscope to obtain a phase image of the cross-section, the polyester block B, which has relatively large phase delay, is dispersed as domains having an average size of from 20 nm to 100 nm in a domain of the polyester block A, which has relatively small phase delay. The block copolymer has a first glass transition temperature of from &#x2212;20&#xb0; C. to 20&#xb0; C., and a second glass transition temperature of from 35&#xb0; C. to 65&#xb0; C. when the first and second glass transition temperatures are determined from a thermogram obtained by subjecting the block copolymer to differential scanning calorimetry (DSC) at a temperature rising speed of 5&#xb0; C./min.

Toner, developer including the toner, image forming apparatus using the toner, and block copolymer

A developer, including a toner including a binder resin comprising a crystalline resin; and a colorant, and a resin carrier comprising a resin; a magnetic particulate material having a magnetic anisotropy, dispersed in the resin, and having a saturated magnetization of from 16 to 30 emu/g, a coercive force of from 15 to 40 kA/m and an average particle diameter not less than 15 &#x3bc;m and less than 100 &#x3bc;m.

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Shizuoka, Japan

Keiji Makabe