Patents by Inventor Kei Tajima

Kei Tajima has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20140342892
    Abstract: A semiconductive roller having good semiconductivity as a charging roller or a developing roller is described. The semiconductive roller includes an oxide film having excellent characteristics as a protective film, and in particular, hardly causes an image defect of white stripes associated with tackiness in an image formed in a storage test in an environment of high temperature and high humidity. The semiconductive roller includes a semiconductive rubber composition formed by mixing a base polymer with a triazine crosslinker and a sulfur-based crosslinking component as a crosslinking component for crosslinking the base polymer, wherein the base polymer is a mixture of an epichlorohydrin rubber E and a diene rubber D having a mass ratio of E/D of 50/50 to 80/20. The semiconductive roller also has an oxide film formed on its outer peripheral surface by ultraviolet irradiation.
    Type: Application
    Filed: April 28, 2014
    Publication date: November 20, 2014
    Applicant: SUMITOMO RUBBER INDUSTRIES, LTD.
    Inventor: KEI TAJIMA
  • Patent number: 8882646
    Abstract: The semiconductive roller according to the present invention includes: a roller body having an outer peripheral surface made of a semiconductive rubber composition; and an oxide film covering the outer peripheral surface of the roller body, while the semiconductive rubber composition contains a base polymer and a crosslinking component for crosslinking the base polymer, the base polymer is a mixture of a bicopolymer E containing epichlorohydrin and nitrile-butadiene rubber N, the mass ratio E/N of the bicopolymer E and the nitrile-butadiene rubber N in the mixture is 50/50 to 80/20, and the crosslinking component includes a thiourea-based crosslinking component for crosslinking the bicopolymer E and a sulfur-based vulcanizing component for vulcanizing the nitrile-butadiene rubber N.
    Type: Grant
    Filed: March 15, 2011
    Date of Patent: November 11, 2014
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Kei Tajima, Kiyotaka Okuda, Takashi Marui
  • Publication number: 20140103262
    Abstract: The electrically conductive rubber composition contains a rubber component including an SBR, an epichlorohydrin rubber and a CR, and the proportion of the SBR is 40 to 80 parts by mass based on 100 parts by mass of the rubber component. The rubber composition further contains 1.0 to 1.5 parts by mass of a sulfur crosslinking agent, 0.2 to 0.6 parts by mass of a thiourea accelerating agent, 0.1 to 0.5 parts by mass of a thiuram accelerating agent, and 1.0 to 2.0 parts by mass of a thiazole accelerating agent based on 100 parts by mass of the rubber component.
    Type: Application
    Filed: July 11, 2013
    Publication date: April 17, 2014
    Inventors: Takashi Marui, Yoshihisa Mizumoto, Kei Tajima
  • Publication number: 20130288869
    Abstract: An electrically conductive roller is provided which has a stable roller resistance with little batch-to-batch variation in roller resistance and substantially without influence of environmental conditions and the like, and is unlikely to contaminate the photo receptor. The electrically conductive roller (1) includes a roller body (2) made of a crosslinking product of an electrically conductive rubber composition prepared by blending a potassium salt of an anion having a fluoro group and a sulfonyl group in its molecule and a crosslinking component in a base polymer which is a mixture containing an epichlorohydrin rubber E and a diene rubber N in a mass ratio E/N of 50/50 to 80/20, and an oxide film (6) formed in an outer peripheral surface (5) thereof by irradiation with ultraviolet radiation.
    Type: Application
    Filed: February 5, 2013
    Publication date: October 31, 2013
    Applicant: SUMITOMO RUBBER INDUSTRIES, LTD.
    Inventor: Kei TAJIMA
  • Patent number: 8277692
    Abstract: The semiconductive rubber composition according to the present invention contains: a rubber content containing at least copolymer rubber containing ethylene oxide as a copolymeric component and chloroprene rubber; and not less than 0.5 parts by mass and not more than 1.5 parts by mass of a thiourea-based vulcanization accelerator, not less than 0.5 parts by mass and not more than 1.5 parts by mass of a guanidine-based vulcanization accelerator and not less than 0.5 parts by mass and not more than 2.0 parts by mass of a peroxide-based crosslinking agent with respect to 100 parts by mass of the sum of the rubber content.
    Type: Grant
    Filed: February 4, 2010
    Date of Patent: October 2, 2012
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Takashi Marui, Yoshihisa Mizumoto, Kei Tajima, Noriaki Hitomi
  • Publication number: 20110281703
    Abstract: The semiconductive roller according to the present invention includes: a roller body having an outer peripheral surface made of a semiconductive rubber composition; and an oxide film covering the outer peripheral surface of the roller body, while the semiconductive rubber composition contains a base polymer and a crosslinking component for crosslinking the base polymer, the base polymer is a mixture of a bicopolymer E containing epichlorohydrin and nitrile-butadiene rubber N, the mass ratio E/N of the bicopolymer E and the nitrile-butadiene rubber N in the mixture is 50/50 to 80/20, and the crosslinking component includes a thiourea-based crosslinking component for crosslinking the bicopolymer E and a sulfur-based vulcanizing component for vulcanizing the nitrile-butadiene rubber N.
    Type: Application
    Filed: March 15, 2011
    Publication date: November 17, 2011
    Inventors: Kei Tajima, Kiyotaka Okuda, Takashi Marui
  • Publication number: 20100261002
    Abstract: A conductive member of a paper feed roller for use in an electrophotographic apparatus is provided which retains electrical conductivity in an adequate range, is effectively prevented from deteriorating in durability, and is reduced in the voltage dependence of electrical resistance and in resistance unevenness. This conductive member enables satisfactory print quality to be obtained over long. The conductive member comprises: a conductive elastic layer formed from one or more elastic materials selected from the group consisting of rubbers, resins, and thermoplastic elastomers; and a coating layer formed by applying a surface-treating liquid to the outer surface of the conductive elastic layer and then thermally curing the coating. The surface-treating liquid comprises: a medium containing, dispersed and/or dissolved therein, either a polyisocyanate compound or a combination of a polyol compound and an isocyanate compound; and carbon nanotubes dispersed in the medium.
    Type: Application
    Filed: October 27, 2008
    Publication date: October 14, 2010
    Applicant: SUMITOMO RUBBER INDUSTRIES, LTD.
    Inventors: Kei Tajima, Hideyuki Okuyama
  • Publication number: 20100200814
    Abstract: The semiconductive rubber composition according to the present invention contains: a rubber content containing at least copolymer rubber containing ethylene oxide as a copolymeric component and chloroprene rubber; and not less than 0.5 parts by mass and not more than 1.5 parts by mass of a thiourea-based vulcanization accelerator, not less than 0.5 parts by mass and not more than 1.5 parts by mass of a guanidine-based vulcanization accelerator and not less than 0.5 parts by mass and not more than 2.0 parts by mass of a peroxide-based crosslinking agent with respect to 100 parts by mass of the sum of the rubber content.
    Type: Application
    Filed: February 4, 2010
    Publication date: August 12, 2010
    Inventors: Takashi MARUI, Yoshihisa Mizumoto, Kei Tajima, Noriaki Hitomi
  • Patent number: 7744781
    Abstract: A conductive thermoplastic elastomer composition comprising a component (A) containing a thermoplastic resin or/and a thermoplastic elastomer; a component (B) comprising an ionic-conductive agent containing an ethylene oxide-propylene oxide copolymer or/and an ethylene oxide-propylene oxide-allyl glycidyl ether copolymer and a metal salt contained in the ethylene oxide-propylene oxide copolymer or/and the ethylene oxide-propylene oxide-allyl glycidyl ether copolymer; and a component (C) comprising an ethylene-acrylic ester-maleic anhydride copolymer.
    Type: Grant
    Filed: August 3, 2007
    Date of Patent: June 29, 2010
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Kei Tajima, Hideyuki Okuyama
  • Patent number: 7728060
    Abstract: A rubber component containing at least one of diene rubber and ethylene-propylene-diene rubber is dynamically crosslinked. Thereby the rubber component is dispersed in a mixture of a thermoplastic elastomer and a thermoplastic resin. An ethylene oxide-propylene oxide-allyl glycidyl ether and an anion-containing salt having fluoro groups and sulfonyl groups are added to the elastomer composition to obtain a conductive dynamically crosslinked thermoplastic elastomer composition. A mixture of the obtained conductive dynamically crosslinked thermoplastic elastomer composition and a micro-capsule composed of a polymer, having acrylic groups, which forms an outer shell thereof is molded to obtain a conductive roller having Shore A hardness specified in JIS K6253 not more than 40 measured at 23° C.
    Type: Grant
    Filed: August 23, 2007
    Date of Patent: June 1, 2010
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Akira Minagoshi, Kei Tajima
  • Publication number: 20080071028
    Abstract: A rubber component containing at least one of diene rubber and ethylene-propylene-diene rubber is dynamically crosslinked. Thereby the rubber component is dispersed in a mixture of a thermoplastic elastomer and a thermoplastic resin. An ethylene oxide-propylene oxide-allyl glycidyl ether and an anion-containing salt having fluoro groups and sulfonyl groups are added to the elastomer composition to obtain a conductive dynamically crosslinked thermoplastic elastomer composition. A mixture of the obtained conductive dynamically crosslinked thermoplastic elastomer composition and a micro-capsule composed of a polymer, having acrylic groups, which forms an outer shell thereof is molded to obtain a conductive roller having Shore A hardness specified in JIS K6253 not more than 40 measured at 23° C.
    Type: Application
    Filed: August 23, 2007
    Publication date: March 20, 2008
    Inventors: Akira Minagoshi, Kei Tajima
  • Publication number: 20080042108
    Abstract: A conductive thermoplastic elastomer composition comprising a component (A) containing a thermoplastic resin or/and a thermoplastic elastomer; a component (B) comprising an ionic-conductive agent containing an ethylene oxide-propylene oxide copolymer or/and an ethylene oxide-propylene oxide-allyl glycidyl ether copolymer and a metal salt contained in the ethylene oxide-propylene oxide copolymer or/and the ethylene oxide-propylene oxide-allyl glycidyl ether copolymer; and a component (C) comprising an ethylene-acrylic ester-maleic anhydride copolymer.
    Type: Application
    Filed: August 3, 2007
    Publication date: February 21, 2008
    Inventors: Kei Tajima, Hideyuki Okuyama
  • Patent number: 6572307
    Abstract: A fender for absorbing the impact of a vessel is provided, which is formed of rubber and fixed to a fixing surface of a dock and adapted to have an impact receiving plate secured to a distal end of a body of the fender. The fender comprises a first bumper member having an elongated hollow cylindrical body of a constant outside diameter and affixed to the impact receiving plate at one end, and a second bumper member connected at one end to an opposite end of the cylindrical body of the first bumper member. The second bumper member at the opposite end thereof is fixed to the fixing surface at a portion having a hollow conical body with its distal end being greater in outside diameter than its closest end, and the second bumper member buckling radially outwardly upon receiving a compressive force from the vessel thereby absorbing the impact of the vessel; and a shoulder formed along an outer periphery of a connection portion between the first and second bumper members.
    Type: Grant
    Filed: December 20, 2000
    Date of Patent: June 3, 2003
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Kei Tajima, Yasufumi Kozono, Akira Kamigoro
  • Publication number: 20010007236
    Abstract: A fender integrally made of a rubber material, including a first bumper member of a cylindrical shape and a second bumper member of a hollow conical shape, the fender further including at least one of:
    Type: Application
    Filed: December 20, 2000
    Publication date: July 12, 2001
    Inventors: Kei Tajima, Yasufumi Kozono, Akira Kamigoro
  • Patent number: 6187420
    Abstract: The present invention provides a novel fender, which has a sufficient shock absorbing action with respect to a ship and is capable of dispersing a compressive force given at the time when the ship comes alongside at the pier and reducing a friction force at the time given when the ship is moored at the pier. A fender of the present invention comprises a fender body 10, and a surface layer 12 with which at least an impact receiving surface of this fender body 10 is coated, wherein the surface layer 12 is made of a blended polymer of a crystalline polyolefin resin and a diene rubber and the proportion of the crystalline polyolefin resin in the blended polymer exceeds 50% by weight and not more than 85% by weight.
    Type: Grant
    Filed: July 23, 1998
    Date of Patent: February 13, 2001
    Assignee: Sumitomo Rubber Industries, Ltd.
    Inventors: Kei Tajima, Yoshihisa Mizumoto