Ferrite Containing Magnetic Carrier Patents (Class 430/111.31)
  • Patent number: 10564561
    Abstract: An object of the present invention is to provide a ferrite carrier core material for an electrophotographic developer having desired resistance properties and charging properties with small environmental variation of resistivity and charge amount while maintaining the advantages of ferrite carriers, a ferrite carrier for an electrophotographic developer, an electrophotographic developer using the ferrite carrier, and a method for manufacturing the ferrite carrier core material for an electrophotographic developer. In order to solve the problem, a ferrite carrier core material comprising ferrite particles containing 15 mass % or more and 25 mass % or less of Mn, 0.5 mass % or more and 5.0 mass % or less of Mg, 0.05 mass % or more and 4.0 mass % of Sr, and 45 mass % or more and 55 mass % or less of Fe, with Zr localized in the surface thereof is used.
    Type: Grant
    Filed: March 29, 2017
    Date of Patent: February 18, 2020
    Assignee: POWDERTECH CO., LTD.
    Inventors: Takao Sugiura, Kazutaka Ishii, Koji Aga
  • Patent number: 10548822
    Abstract: A beauty care method has a step of applying an aqueous pack agent 1 containing water, a magnetic powder 11, a thickener and a charged iontophoretic component 13 to the skin 2; a step of applying magnetic force to the magnetic powder 11 in the aqueous pack agent 1 applied to the skin 2 to attract and remove the magnetic powder 11 from the skin surface 21 by the magnetic force while leaving an aqueous solution 12 of the iontophoretic component on the skin surface 21; and a step of applying an iontophoretic current to the skin 2 with the aqueous solution 12 left to allow the iontophoretic component 13 to infiltrate into the skin.
    Type: Grant
    Filed: November 4, 2014
    Date of Patent: February 4, 2020
    Assignee: MTG Co., Ltd.
    Inventor: Tsuyoshi Matsushita
  • Patent number: 10088764
    Abstract: A carrier core material includes, a main component, a material represented by a composition formula MnXMYFe3?(X+Y)O4 (where M is selected from Mg, Ti, Cu, Zn and Ni, 0<X, 0?Y, 0<X+Y<1), in which 0.1 to 1.0 mol % of at least one of Sr element and Ca element is contained as the total amount by conversion to SrO or CaO and in which the frequency of a grain whose length RSm is equal or more than 8.0 ?m among grains appearing on the surface of particles of the carrier core material is equal to or less than 2.0 number percent. In this way, the degradation of a carrier caused by long-term use such as the separation of a coating resin is significantly reduced, stable charging performance is maintained and the cracking or chipping of the particles is reduced.
    Type: Grant
    Filed: March 22, 2016
    Date of Patent: October 2, 2018
    Assignees: DOWA ELECTRONICS MATERIALS CO., LTD., DOWA IP CREATION CO., LTD.
    Inventors: Yuto Kamai, Takeshi Kawauchi
  • Patent number: 9841702
    Abstract: A method for providing a developer mix having tribocharge uniformity across varying temperature and humidity conditions is provided. Tribocharge uniformity is achieved in the developer mix by performing the step of treating the surface of the polymer coated magnetic carrier particles with hydrophobized titania surface additives before the polymer coated magnetic carrier particles are mixed with the toner particles. The surface treatment with the hydrophobized titania surface additives can be either a spherical, disk, or spindle shaped.
    Type: Grant
    Filed: December 2, 2016
    Date of Patent: December 12, 2017
    Assignee: LEXMARK INTERNATIONAL, INC.
    Inventors: Kasturi Rangan Srinivasan, Michael Anthony Blassingame
  • Patent number: 9835967
    Abstract: A developer mix used in a dual component development (DCD) system is a mixture of toner particles and magnetic carrier particles, wherein the magnetic carrier particle is surface treated with a hydrophobized titania particle. The surface treatment with a hydrophobized titania particle may be selected from either a spherical, disk, or spindle shaped. Tribocharge of the toner and the toner charge stability across cartridge life or environments may be suitably modified by selecting a preferred size and shape of the hydrophobized titania.
    Type: Grant
    Filed: December 2, 2016
    Date of Patent: December 5, 2017
    Assignee: LEXMARK INTERNATIONAL, INC.
    Inventors: Kasturi Rangan Srinivasan, Michael Anthony Blassingame
  • Patent number: 9588453
    Abstract: There is provided a resin-filled ferrite carrier for an electrophotographic developer, in which a void of a porous ferrite particle used as a ferrite carrier core material is filled with silicone resin, wherein a true specific gravity (Y) of the porous ferrite particle filled with the silicone resin and a Si/Fe value (X) measured by fluorescent X-ray elemental analysis satisfy the following inequality (1): ?350X?Y?4.83??100X??(1).
    Type: Grant
    Filed: March 30, 2015
    Date of Patent: March 7, 2017
    Assignee: POWDERTECH CO., LTD.
    Inventors: Hiroki Sawamoto, Takao Sugiura
  • Patent number: 9372426
    Abstract: It is an object of the present invention to provide a ferrite particle having a low apparent density, and being capable of maintaining various properties thereof in controllable states and filling a fixed volume in a small weight thereof, a ferrite carrier core material and a ferrite carrier for an electrophotographic developer using the ferrite particle, and the like. In order to achieve the object, there are employed the ferrite particle having a porous structure in the interior thereof and an outer shell structure on the outer periphery thereof, the ferrite carrier core material and the ferrite carrier for an electrophotographic developer using the ferrite particle, and an electrophotographic developer using the ferrite carrier.
    Type: Grant
    Filed: January 16, 2015
    Date of Patent: June 21, 2016
    Assignee: POWDERTECH CO., LTD.
    Inventor: Koji Aga
  • Patent number: 9164411
    Abstract: There is provided a carrier core material for electrophotographic developer containing a soft ferrite, expressed by (MgXMn1?X)Fe2O4 (wherein X is in a range of 0.1?X<1.), wherein an analysis value of P on the surface of the carrier core material is 0.1 mass % or more, an analysis value of Mg is 2 mass % or more, a content of Mg on the surface of the carrier core material is 2 mass % or more by EDS, and when the content of Mg in the carrier core material is expressed by M1, and the analysis value of Mg on the surface of the carrier core material by EDS is expressed by M2, a value of M2/M1 exceeds 1.0.
    Type: Grant
    Filed: June 28, 2010
    Date of Patent: October 20, 2015
    Assignees: DOWA ELECTRONICS MATERIALS CO., LTD., DOWA IP CREATION CO., LTD.
    Inventors: Masahiro Nakamura, Takeshi Kawauchi, Toshiya Kitamura
  • Patent number: 9034552
    Abstract: The carrier core particles for electrophotographic developer have a volume size distribution with a median particle size ranging from 30 ?m to 40 ?m, the ratio of the carrier core particles having a diameter of 22 ?m or lower in the volume size distribution is from 1.0% to 2.0%, the ratio of the carrier core particles having a diameter of 22 ?m or lower in a number size distribution is 10% or lower, and the magnetization of the carrier core particles in an external magnetic field of 1000 Oe is from 50 emu/g to 75 emu/g.
    Type: Grant
    Filed: March 1, 2012
    Date of Patent: May 19, 2015
    Assignees: DOWA ELECTRONICS MATERIALS CO., LTD., DOWA IP CREATION CO., LTD.
    Inventors: Tomohide Iida, Tomoya Yamada, Takashi Fujiwara
  • Patent number: 9034551
    Abstract: Provided is a two-component developer containing: a magnetic carrier obtained by coating a magnetic core with a resin; and toner, in which: the magnetic core contains at least a ferrite component and at least one kind of an oxide selected from the group consisting of SiO2 and Al2O3; the content of the oxide is 4.0 mass % or more and 40.0 mass % or less with respect to the magnetic core; the magnetic core has a specific resistance of 5.0×104 ?·cm or more and 5.0×108 ?·cm or less at the time of the application of 1,000 V/cm; the magnetic carrier has an intensity of magnetization in 79.6 kA/m of 40.0 Am2/kg or more and 65.0 Am2/kg or less, and a residual magnetization after the application of an external magnetic field of 79.6 kA/m of 3.0 Am2/kg or less; and the toner has a weight-average particle diameter (D4) of 3.0 ?m or more and 10.0 ?m or less and an average circularity of 0.940 or more and 0.990 or less.
    Type: Grant
    Filed: March 10, 2009
    Date of Patent: May 19, 2015
    Assignee: CANON KABUSHIKI KAISHA
    Inventors: Tomoko Endo, Koh Ishigami, Naoki Okamoto, Yoshinobu Baba
  • Patent number: 9029060
    Abstract: A carrier for electrostatic latent image developing is composed of carrier core containing a binder resin and magnetic material particles, and a shell layer that covers the carrier core. The binder has an acid value of at least a predetermined value, and contains a resin having a carboxyl group. The shell layer is composed of a resin selected from melamine resin and urea resin.
    Type: Grant
    Filed: September 25, 2013
    Date of Patent: May 12, 2015
    Assignee: KYOCERA Document Solutions Inc.
    Inventors: Masami Tujihiro, Yoshio Ozawa
  • Patent number: 8945805
    Abstract: The present invention provides an image of high image quality by using a magnetic carrier coated with a novel coating resin composition. Further, the present invention stably provides a good image which is hardly influenced by environmental fluctuation and long-term use and has a superior stability of a charging amount when left to stand especially under high temperature and high humidity environments. The present invention also provides a magnetic carrier characterized in that a carrier core surface is coated with a copolymer containing at least, as copolymerization components, an acrylic monomer having a specific structure and an acrylic macromonomer having a specific structure.
    Type: Grant
    Filed: February 26, 2009
    Date of Patent: February 3, 2015
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yoshinobu Baba, Koh Ishigami, Naoki Okamoto, Tomoko Endo
  • Patent number: 8883388
    Abstract: A carrier core particle for an electrophotographic developer including a core composition expressed by a general formula: (MnxMgyCaz) FeWO4+V (x+y+z+w=3, ?0.003<v) as a main ingredient, wherein 0.05?y?0.35 and 0.005?z?0.024.
    Type: Grant
    Filed: July 26, 2011
    Date of Patent: November 11, 2014
    Assignees: Dowa Electronics Materials Co., Ltd., Dowa IP Creation Co., Ltd.
    Inventors: Takeshi Kawauchi, Yukihiro Matsuda
  • Patent number: 8865386
    Abstract: A carrier core particle for an electrophotographic developer includes a core composition expressed by a general formula: MnxFe3?xO4+y (0<x?1, 0<y) as a main ingredient, 0.1 wt % or more of Si, and 0.03 wt % or more of at least one metal element selected from the group consisting of Ca, Sr and Mg.
    Type: Grant
    Filed: March 29, 2011
    Date of Patent: October 21, 2014
    Assignees: Dowa Electronics Materials Co., Ltd., Dowa IP Creation Co., Ltd.
    Inventors: Takeshi Kawauchi, Sho Ogawa
  • Publication number: 20140242511
    Abstract: Provided is a method for manufacturing carrier core particles for electrophotographic developer capable of stably maintaining high chargeability over a long time. The method for manufacturing carrier core particles includes a granulation step of granulating a mixture of raw materials containing manganese, iron, strontium, and calcium and a firing step of firing the mixture granulated in the granulation step. The firing step includes a heating process of heating the granular mixture with an increase in temperature to a predetermined degree and a cooling process of cooling the granular mixture, after the heating process, in an atmosphere with an oxygen concentration ranging from 5000 ppm to 20000 ppm. The molar ratio of the sum of strontium and calcium to the sum of the manganese, iron, strontium, and calcium is 0.0026 to 0.013.
    Type: Application
    Filed: February 20, 2014
    Publication date: August 28, 2014
    Applicants: DOWA IP CREATION CO., LTD., DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Takeshi KAWAUCHI, SHO OGAWA, HARUKA SEKI
  • Patent number: 8802343
    Abstract: A carrier for developing an electrostatic charge image comprising a core material and a coating resin layer that covers the core material, wherein the core material is a ferrite particle having a Brunauer-Emmitt-Teller (BET) specific surface area of from about 0.12 m2/g to about 0.20 m2/g, and having a fluidity of from about 26 sec/50 g to about 30 sec/50 g.
    Type: Grant
    Filed: March 4, 2011
    Date of Patent: August 12, 2014
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Yosuke Tsurumi, Norihito Fukushima, Yasuaki Hashimoto, Shintaro Anno
  • Patent number: 8709695
    Abstract: A carrier for developing an electrostatic charge image includes a core containing a magnetic material and a coating layer, in which the coating layer includes porous carbon having a volume average particle size of from 0.5 ?m to 2 ?m and a BET specific surface area of from 1 m2/g to 5 m2/g, and a resin.
    Type: Grant
    Filed: July 20, 2012
    Date of Patent: April 29, 2014
    Assignee: Fuji Xerox Co., Ltd.
    Inventor: Yasushige Nakamura
  • Patent number: 8673529
    Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical composite particles comprising spherical composite core particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin and having an average particle diameter of 1 to 100 ?m, and a melamine resin coating layer formed on the respective core particles, wherein a ratio of R100 to R300 (R100/R300) in which R100 is an electric resistance value as measured when applying a voltage of 100 V to the magnetic carrier; and R300 is an electric resistance value as measured when applying a voltage of 300 V to the magnetic carrier, is controlled to lie within the range of 1 to 50.
    Type: Grant
    Filed: June 15, 2010
    Date of Patent: March 18, 2014
    Assignee: Toda Kogyo Corporation
    Inventors: Kaori Kinoshita, Shinji Uemoto, Eiichi Kurita
  • Patent number: 8652735
    Abstract: A carrier including a magnetic core particle and a resin layer covering a surface of the magnetic core particle. The magnetic core particle is a ferrite particle including strontium in an amount of 0.005 to 3% by mass, measured by fluorescent X-ray spectroscopy. The resin layer comprises a resin obtained by heating a copolymer comprising a silicon-containing unit A and another silicon-containing specific unit B.
    Type: Grant
    Filed: August 19, 2011
    Date of Patent: February 18, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Koichi Sakata, Shigenori Yaguchi, Toyoshi Sawada, Kimitoshi Yamaguchi, Hitoshi Iwatsuki, Hiroshi Tohmatsu, Hiroyuki Kishida, Toyoaki Tano, Mariko Takii
  • Publication number: 20140030650
    Abstract: A magnetic carrier having a resin-containing ferrite particles each containing a porous ferrite core and a resin in pores of the porous ferrite core, wherein the porous ferrite core has a particular pore diameter corresponding to the maximum logarithmic differential pore volume in a pore diameter range from at least 0.10 ?m to not more than 3.00 ?m, the resistivity of the porous ferrite core is in a particular range, and the porous ferrite core contains an oxide of Mg in a particular amount and contains a particular amount of a oxide of at least one metal selected from the group consisting of Mn, Sr, and Ca.
    Type: Application
    Filed: May 24, 2013
    Publication date: January 30, 2014
    Applicant: CANON KABUSHIKI KAISHA
    Inventors: Nozomu Komatsu, Kentaro Kamae, Koh Ishigami, Yoshinobu Baba
  • Publication number: 20140017606
    Abstract: A material expressed as a composition formula MXFe3-XO4 (where M is at least one of Mg and Mn, and 0?X?1) is a main component, and as a total amount, 0.1 to 2.5 weight percent of at least one of a Sr element and a Ca element is contained. Here, when ferrite particles are used as a carrier, in terms of obtaining a higher image density, the fluidity of the ferrite particles magnetized under a magnetic field of 1000/(4?) kA/m (1000 oersteds) is preferably 40 seconds or more. The residual magnetization ?r is preferably 3 Am2/kg or more.
    Type: Application
    Filed: March 19, 2012
    Publication date: January 16, 2014
    Applicants: DOWA IP CREATION CO., LTD, DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Tomoya Yamada, Tomohide Iida
  • Patent number: 8617781
    Abstract: The carrier core particles 11 for electrophotographic developer contain lithium as a core composition. When the carrier core particles 11 are immersed in pure water at a weight ratio of 1 part core particles 11 to 10 parts pure water and shaken, the amount of lithium that leaches out to the pure water is 0.10 ppm or lower.
    Type: Grant
    Filed: January 25, 2011
    Date of Patent: December 31, 2013
    Assignees: Dowa Electronics Materials Co., Ltd., Dowa IP Creation Co., Ltd.
    Inventor: Takeshi Kawauchi
  • Patent number: 8535867
    Abstract: There is provided a ferrite core material for an electrophotographic developer, the ferrite core material having a ferrite particle composition represented by the formula (1) shown below, containing SrO replacing a part of (MnO) and/or (MgO) in the formula (1) shown below, and having a Cl concentration of 0.1 to 100 ppm, as measured by an elution method of the ferrite core material: (MnO)x(MgO)y(Fe2O3)z??(1) wherein x=35 to 45 mol %, y=5 to 15 mol %, z=40 to 60 mol %, and x+y+z=100 mol %.
    Type: Grant
    Filed: February 3, 2011
    Date of Patent: September 17, 2013
    Assignee: Powdertech Co., Ltd.
    Inventors: Tomoyuki Suwa, Toru Iwata, Koji Aga
  • Patent number: 8518626
    Abstract: The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the particulate magnetic core material and including a crosslinked material. The crosslinked material is formed by hydrolyzing a copolymer including at least a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure to form a material having a silanol group, and subjecting the material having a silanol group to a condensation reaction using an organic zirconium-containing catalyst.
    Type: Grant
    Filed: March 1, 2011
    Date of Patent: August 27, 2013
    Assignee: Ricoh Company, Limited
    Inventors: Saori Yamada, Minoru Masuda, Hisashi Nakajima, Kimitoshi Yamaguchi, Koichi Sakata, Hitoshi Iwatsuki, Yutaka Takahashi, Toyoaki Tano, Mariko Takii
  • Patent number: 8512928
    Abstract: A carrier comprising a magnetic core particle having a shape factor SF-2 of 130 to 160 and a resin layer covering a surface of the magnetic core particle. The resin layer comprises a conductive particle and a resin obtained by heating a copolymer comprising a silicon-containing A unit and another silicon-containing B unit.
    Type: Grant
    Filed: September 6, 2011
    Date of Patent: August 20, 2013
    Assignee: Rocoh Company, Ltd.
    Inventors: Hiroyuki Kishida, Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Koichi Sakata, Hitoshi Iwatsuki, Toyoaki Tano, Mariko Takii
  • Patent number: 8481239
    Abstract: A carrier, including a magnetic particulate core material and a resin layer on the core material, wherein the resin layer includes a resin obtained by heat treatment of a copolymer including a site derived from a monomer component having the following formula (1) and a site derived from a monomer component having the following formula (2), and includes a cross-linked material obtained by hydrolysis of the copolymer to produce a silanol group and condensation using an organotitanium compound: wherein R1 represents a hydrogen atom or a methyl group; m represents an alkylene group having 1 to 8 carbon atoms; R2 represents an alkyl group having 1 to 4 carbon atoms; R3 represents an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; X represents 10 to 90 mol %; and Y represents 10 to 90 mol %.
    Type: Grant
    Filed: October 1, 2010
    Date of Patent: July 9, 2013
    Assignee: Ricoh Company Limited
    Inventors: Hisashi Nakajima, Kimitoshi Yamaguchi, Minoru Masuda, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki, Saori Yamada, Toyoaki Tano
  • Patent number: 8475988
    Abstract: Disclosed are a resin-filled ferrite carrier core material for an electrophotographic developer, including a porous ferrite particle, wherein the composition of the porous ferrite particle is represented by the following formula (1), and part of (MgO) and/or (Fe2O3) in the following formula (1) is replaced with SrO; a ferrite carrier obtained by filling a resin in the voids of the ferrite carrier core material; and an electrophotographic developer using the ferrite carrier: ( MgO ) ? x ? ( Fe 2 ? O 3 ) ? y ? ( x = 10 ? ? mol ? ? % ? ? or ? ? more ? ? and ? ? less ? ? than ? ? 25 ? ? mol ? ? % y = exceeding ? ? 75 ? ? mol ? ? % ? ? and ? ? 90 ? ? mol ? ? % ? ? or ? ? less x + y = 100 ? ? mol ? ? % ) .
    Type: Grant
    Filed: February 2, 2011
    Date of Patent: July 2, 2013
    Assignee: Powdertech Co., Ltd.
    Inventors: Takao Sugiura, Takashi Hikichi, Hiromichi Kobayashi
  • Patent number: 8475989
    Abstract: The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the core material and including a crosslinked material and barium sulfate. The cover layer is formed by applying a coating medium including barium sulfate, a copolymer including a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure having a crosslinking ability, and a condensation reaction catalyst, heating the applied medium to a temperature of from 100° C. to 230° C. so that the copolymer is hydrolyzed to produce a material having a silanol group, and the material and the catalyst are subjected to a condensation reaction to form the crosslinked material.
    Type: Grant
    Filed: October 4, 2010
    Date of Patent: July 2, 2013
    Assignee: Ricoh Company, Limited
    Inventors: Yutaka Takahashi, Minoru Masuda, Kimitoshi Yamaguchi, Hisashi Nakajima, Koichi Sakata, Hitoshi Iwatsuki, Saori Yamada, Toyoaki Tano, Mariko Takii
  • Patent number: 8465898
    Abstract: There are provided a ferrite carrier core material for an electrophotographic developer, which contain 10 to 30% by weight of Mn, 1.0 to 3.0% by weight of Mg, 0.3 to 1.5% by weight of Ti and 40 to 60% by weight of Fe, a ferrite carrier for an electrophotographic developer obtained by coating the ferrite core material, and an electrophotographic developer using the ferrite carrier.
    Type: Grant
    Filed: June 16, 2011
    Date of Patent: June 18, 2013
    Assignee: Powdertech Co., Ltd.
    Inventors: Toru Iwata, Koji Aga
  • Patent number: 8435712
    Abstract: The use of electrographic printing to prepare prints which have a desired tactile feel or raised information in a controlled manner by utilizing a developer having toner particle size larger than 50 microns volume average diameter and carrier particles larger than the toner particle size such that the volume average distribution overlap between the toner distribution curve and carrier particle distribution curve is less than 35% and the carrier and toner particles have a volume average diameter size differential equal to or greater than 5 microns or the ratio of carrier-to-toner volume average diameter exceeds 1.25.
    Type: Grant
    Filed: May 21, 2008
    Date of Patent: May 7, 2013
    Assignee: Eastman Kodak Company
    Inventors: Dinesh Tyagi, Patrick M. Lambert, Mark C. Zaretsky, Thomas N. Tombs
  • Patent number: 8431312
    Abstract: The present invention provides a carrier which includes core material particles, and a coating layer on surfaces of the core material particles, wherein the coating layer contains a crosslinked product which is obtained by condensation of a silicone resin with an organic zirconium catalyst, the silicone resin having at least one of a silanol group and a functional group capable of generating a silanol group by means of hydrolysis.
    Type: Grant
    Filed: November 10, 2009
    Date of Patent: April 30, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Minoru Masuda, Kimitoshi Yamaguchi, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki
  • Patent number: 8431311
    Abstract: A resin-filled carrier for an electrophotographic developer obtained by filling resin into voids of a porous ferrite core material, wherein the porous ferrite core material has a pore volume of 0.055 to 0.16 mL/g and a peak pore size of 0.20 to 0.7 ?m, and an electrophotographic developer using this resin-filled carrier.
    Type: Grant
    Filed: December 23, 2008
    Date of Patent: April 30, 2013
    Assignee: Powdertech Co., Ltd.
    Inventors: Takao Sugiura, Takeshi Gondo, Hiromichi Kobayashi
  • Patent number: 8367293
    Abstract: A method for producing a carrier, including a step of periodically forming and discharging liquid droplets of a carrier core composition liquid from a plurality of nozzles formed in a thin film, using a liquid droplet forming unit having the thin film and a ring-shaped vibration generating unit disposed in a deformable area of the thin film so as to be along a circumference of the area and to vibrate the thin film, a step of forming carrier core particles by solidifying the discharged liquid droplets, and a step of coating the carrier core particles with a resin layer.
    Type: Grant
    Filed: December 18, 2008
    Date of Patent: February 5, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Shinji Ohtani, Ryota Inoue, Yoshihiro Norikane
  • Patent number: 8343453
    Abstract: To provide a carrier for two-component electrophotographic developer not only having excellent fluidity but also having proper surface irregularities necessary for imparting electric charge, without generating cracks/chipping of particles even under an influence of stirring stress over a long period of time. A particle surface has raised parts of striped pattern extending almost continuously in a plurality of directions while being superposed on one another, with a surface formed with raised parts of striped pattern occupying 80% or more of the whole surface of a particle. Depths of grooves between the adjacent raised parts are 0.05 ?m or more and 0.2 ?m or less, average surface roughness Ra is 0.1 ?m or more and 0.3 ?m or less, roundness is 0.90 or more, and average particle size is 15 ?m or more and 100 ?m or less, and a carrier core material thus constituted is coated with resin. Thus, the carrier for two-component electrophotographic developer is prepared.
    Type: Grant
    Filed: March 26, 2008
    Date of Patent: January 1, 2013
    Assignees: Dowa Electronics Materials Co., Ltd., Dowa IP Creation Co., Ltd.
    Inventors: Tomoya Yamada, Isao Fujita, Yoshiaki Aiki
  • Patent number: 8338067
    Abstract: An electrostatic image developer is provided, the electrostatic image developer including: a carrier for an electrostatic image developer, the carrier including a core particle which has a plurality of projections on a surface of the core particle; and electrostatic image developing toners, wherein the electrostatic image developer satisfies following relationships of formulae (1) and (2): 0.5t<H??(1) 21/2t<L<5t??(2) wherein t represents a volume average particle diameter (?m) of the toners; H represents an average height difference (?m) in the recesses and projections of the core particle; and L represents an average distance (?m) between the projections.
    Type: Grant
    Filed: March 26, 2010
    Date of Patent: December 25, 2012
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Susumu Yoshino, Hideo Maehata, Satoshi Hiraoka
  • Patent number: 8298742
    Abstract: In a method for coating electrophotographic carrier core surfaces with a resin composition by rotating a rotator having a plurality of agitating blades on its surface in a casing; a coating treatment material that is introduced to a space defined between the rotator and the casing is in a packing of from 50% to 98% by volume; at the time of coating treatment, the electrophotographic carrier core surfaces are coat-treated with the resin composition while being put forward and put backward; and the electrophotographic carrier cores and the resin composition are, at the time of coating treatment, temperature-controlled at a specific temperature T (° C.) or below. This method enables the electrophotographic carrier core surfaces to be more uniformly coated with a coating resin.
    Type: Grant
    Filed: December 18, 2008
    Date of Patent: October 30, 2012
    Assignee: Canon Kabushiki Kaisha
    Inventors: Naoki Okamoto, Yoshinobu Baba, Koh Ishigami, Tomoko Endo
  • Patent number: 8263302
    Abstract: A carrier for electrophotographic developer, including a core material; and a layer comprising a binder resin, located overlying the core material, wherein the binder resin includes a segment including one or more polymerizable vinyl monomers as a structural unit; and another segment including a partial cleavage structure of polyhedral oligomeric silsesquioxane and/or another partial cleavage structure of polyhedral oligomeric silsesquioxane as a structural unit.
    Type: Grant
    Filed: September 8, 2009
    Date of Patent: September 11, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshihiro Moriya, Akihiro Kotsugai, Toyoshi Sawada, Ryota Inoue, Akiyoshi Sabu, Shingo Sakashita
  • Patent number: 8257896
    Abstract: A carrier which is capable of avoiding excess blocking of the carrier particles at the time of forming a covering layer and is excellent in durability, a developer containing the carrier, and a developer container containing the developer, as well as an image forming method and a process cartridge which use the developer are provided. A carrier including at least a core material particle and a covering layer, a surface of the core material particle being covered with the covering layer, wherein the covering layer contains a condensate which is obtained by condensation of a silicone resin having at least one of a silanol group and a functional group which can be converted to the silanol group by hydrolysis, using a titanium diisopropoxy bis(ethylaceto-acetate) catalyst.
    Type: Grant
    Filed: March 10, 2010
    Date of Patent: September 4, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Minoru Masuda, Kimitoshi Yamaguchi, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki, Toyoaki Tano
  • Patent number: 8211610
    Abstract: The carrier includes a particulate core material having magnetism; and a resin layer located on the surface of the particulate core material. The resin layer is prepared by forming a layer including a copolymer, which includes a unit (A) having a specific acrylic siloxane structure, a unit (B) having a specific acrylic silicone structure having a crosslinking ability, and a unit (C) having a specific acrylic structure in a specific ratio, on the particulate core material, and then subjecting the layer to a heat treatment to crosslink the layer.
    Type: Grant
    Filed: March 1, 2010
    Date of Patent: July 3, 2012
    Assignee: Ricoh Company Limited
    Inventors: Kimitoshi Yamaguchi, Minoru Masuda, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki, Toyoaki Tano
  • Patent number: 8187781
    Abstract: Employed are a resin-filled ferrite carrier for an electrophotographic developer filled with a resin in voids of a porous ferrite core material, wherein the resin filled in the voids is a silicone resin which has a softening point of 40° C. or above and is cured at or above such softening point, and the filled amount is 7 to 30 parts by weight based on 100 parts by weight of the core material, a method for producing thereof band an electrophotographic developer using this ferrite carrier.
    Type: Grant
    Filed: March 4, 2008
    Date of Patent: May 29, 2012
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Takao Sugiura
  • Patent number: 8153342
    Abstract: A developer including a toner and a carrier, wherein the carrier is a ferrite carrier coated with a silicone resin and the following relationships are satisfied: log(?Q(t)/Q?)=?kobt ?Q(t)=Q??Q(t) ?2.5 ?log(kob)??1 wherein Q(t) is a charge quantity (?C/g) of the developer after t sec which is a stirring time of the toner and the carrier; Q? is a saturated charge quantity (?C/g) of the developer; and kob is a chargeable speed of the developer.
    Type: Grant
    Filed: September 17, 2007
    Date of Patent: April 10, 2012
    Assignee: Ricoh Company, Ltd.
    Inventor: Akira Izutani
  • Patent number: 8148041
    Abstract: An objective is to provide a carrier exhibiting stable charge providing ability in which sufficient charge can be provided to toner having a small particle diameter, and no image contamination such as fog caused by toner scattering via lack of electrification is generated. Another objective is to provide a carrier capable of maintaining a charging level of no interference for image formation even under the image forming condition at which a charging level for printing a number of prints continuously is difficult to be maintained. Disclosed is a carrier comprising a core particle made of ferrite possessing Mg and coated thereon, a resin, wherein the core particle has a ratio of the number of irregular-shaped core particles of at most 5%, based on the total number of core particles, and a surface of the core particle has grains having a maximum grain diameter of 2-5 ?m.
    Type: Grant
    Filed: January 24, 2011
    Date of Patent: April 3, 2012
    Assignee: Konica Minolta Business Technologies, Inc.
    Inventors: Makoto Kobayashi, Yoshiaki Kobayashi, Yoshiyasu Matsumoto
  • Patent number: 8142972
    Abstract: Provided is a developer for replenishment capable of forming a high-quality image even upon duration. The developer for replenishment includes at least a toner and a magnetic carrier, and in the developer for replenishment, 1 part by mass of the magnetic carrier is blended with 2 to 50 parts by mass of the toner, and the magnetic carrier contains a ferrite core and a resin component, has a true specific gravity of 2.5 to 4.2 g/cm3, has a 50% particle diameter on a volume basis (D50) of 15 to 70 ?m, and has an average circularity of 0.850 to 0.950, the average circularity having a coefficient of variation of 1.0 to 10.0%.
    Type: Grant
    Filed: December 5, 2006
    Date of Patent: March 27, 2012
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yojiro Hotta, Kazuo Terauchi, Kunihiko Nakamura, Hiroyuki Fujikawa, Yoshinobu Baba, Takayuki Itakura, Hirohide Tanikawa
  • Patent number: 8092971
    Abstract: An object of the present invention is to provide a resin-coated ferrite carrier comprising a carrier core material having a small particle size, a high sphericity and surface uniformity, and a low standard deviation, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated ferrite carrier and having a high image quality and excellent durability. For achieving the above object, there is provided a resin-coated carrier for an electrophotographic developer characterized by comprising spherical ferrite particles having an average particle size of 20 to 50 ?m, a surface uniformity of 90% or more, an average sphericity of 1 to 1.3 and a sphericity standard deviation of 0.15 or less, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated carrier.
    Type: Grant
    Filed: November 25, 2004
    Date of Patent: January 10, 2012
    Assignee: Powdertech Co., Ltd.
    Inventors: Kanao Kayamoto, Hironori Hojo, Toshio Honjo
  • Publication number: 20120003579
    Abstract: There are provided a ferrite carrier core material for an electrophotographic developer, which contain 10 to 30% by weight of Mn, 1.0 to 3.0% by weight of Mg, 0.3 to 1.5% by weight of Ti and 40 to 60% by weight of Fe, a ferrite carrier for an electrophotographic developer obtained by coating the ferrite core material, and an electrophotographic developer using the ferrite carrier.
    Type: Application
    Filed: June 16, 2011
    Publication date: January 5, 2012
    Applicant: Powdertech Co., Ltd.
    Inventors: Toru Iwata, Koji Aga
  • Patent number: 8043781
    Abstract: A toner comprising a small-particle diameter external additive having a number average particle diameter of 7 to 20 nm, a large-particle diameter external additive having a number average particle diameter of 40 to 80 nm and a toner particle having a volume average particle diameter of 4 to 7 ?m, wherein the large-particle diameter external additive is stuck to the surface of the toner particles in a semi-embedded state and has a rate of liberation of 0.1% by weight or less from the surface of the toner particle.
    Type: Grant
    Filed: August 1, 2008
    Date of Patent: October 25, 2011
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Tatsuo Imafuku, Takahiro Bito, Takeshi Satoh
  • Patent number: 8039190
    Abstract: A carrier core material for an electrophotographic developer including Li ferrite, maghemite, and Fe3O4, wherein a part thereof is substituted with Mn, Li content is 1 to 2.5% by weight, Mn content is 2 to 7.5% by weight, and silicon content is 25 to 10,000 ppm, the following equation (1) is satisfied when respective integrated strengths of spinel crystal structure (110), (210), (211), and (311) faces in X-ray diffraction are respectively I110, I210, I211, and I311, a resistivity R50 of 50 V across a 6.5 mm gap is 5×107 to 7×108?, and a resistivity R1000 of 1,000 V across a 6.5 mm gap is 1×107 to 8×108?. 2<100×(I110+I210+I211)/I311<14??(1).
    Type: Grant
    Filed: March 6, 2009
    Date of Patent: October 18, 2011
    Assignees: Mitsui Mining & Smelting Co., Ltd., Powdertech Co., Ltd.
    Inventors: Yasunori Tabira, Koji Aga, Tomoyuki Suwa
  • Patent number: 8026033
    Abstract: Disclosed are a ferrite carrier for electrophotographic developer and an electrophotographic developer using the ferrite carrier, wherein: the ferrite carrier is a composite ferrite composed of Li and Mg; when the composition of the ferrite is calculated as a mixture of a Li ferrite having a stoichiometric composition and a Mg ferrite having a stoichiometric composition, the excessive amount of Fe2O3 is less than 5 mol %, or the total excessive amount of Li2O and MgO is less than 1 mol %; the content of the elements other than Li, Mg, Fe and O is 2 % by weight or less; and further, the content of Mn in terms of element is 1000 to 9000 ppm.
    Type: Grant
    Filed: January 16, 2008
    Date of Patent: September 27, 2011
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Takao Sugiura, Kanao Kayamoto
  • Publication number: 20110212399
    Abstract: There is provided a ferrite core material for an electrophotographic developer, the ferrite core material having a ferrite particle composition represented by the formula (1) shown below, containing SrO replacing a part of (MnO) and/or (MgO) in the formula (1) shown below, and having a Cl concentration of 0.1 to 100 ppm, as measured by an elution method of the ferrite core material: (MnO)x(MgO)y(Fe2O3)z ??(1) wherein x=35 to 45 mol %, y=5 to 15 mol %, z=40 to 60 mol %, and x+y+z=100 mol %.
    Type: Application
    Filed: February 3, 2011
    Publication date: September 1, 2011
    Applicant: POWDERTECH CO., LTD.
    Inventors: Tomoyuki SUWA, Toru IWATA, Koji AGA
  • Publication number: 20110183253
    Abstract: A core material of a ferrite carrier for an electrophotographic developer, the core material being composed of a ferrite particle containing at least one or more temperature compensation-type dielectric components selected from Mg2TiO4, MgTiO3 and MgTi2O4, a ferrite carrier for an electrophotographic developer, the ferrite carrier being prepared by coating a surface of the carrier core material with a resin, and an electrophotographic developer using the ferrite carrier.
    Type: Application
    Filed: December 8, 2010
    Publication date: July 28, 2011
    Applicant: POWDERTECH CO., LTD.
    Inventors: Koji AGA, Toru IWATA