Patents by Inventor Kenkichi Muto

Kenkichi Muto 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).

  • Patent number: 5565298
    Abstract: A method of producing a toner for developing latent electrostatic images is disclosed, which comprises the steps of dispersing resin particles comprising a resin in an organic solvent in which the resin is not dissolved; dissolving a dye in the organic solvent before or after dispersing the resin particles in the organic solvent to prepare a dispersion in which the resin particles and the dye are contained, thereby dying the resin particles with the dye; and removing the organic solvent from the dispersion, wherein the ratio of the solubility [D.sub.1 ] of the dye in the organic solvent to the solubility [D.sub.2 ] of the dye in the resin of the resin particles, [D.sub.1 ]/[D.sub.2 ], is not more than 0.5.
    Type: Grant
    Filed: May 26, 1995
    Date of Patent: October 15, 1996
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshihiro Suguro, Masaki Takatsugi, Hiroshi Yamashita, Kenkichi Muto, Kazumi Ohtaki, Yoshikazu Kaneko, Takayuki Hoshina
  • Patent number: 5429901
    Abstract: A toner for use in electrostatic development is composed of toner particles, each toner particle being composed of a core particle containing a thermoplastic resin and a coloring agent; a releasing agent in the form of particles, which substantially cover the entire surface of the core particle; and a chargeable resin which covers at least part of the releasing agent.
    Type: Grant
    Filed: October 18, 1993
    Date of Patent: July 4, 1995
    Assignee: Ricoh Company, Ltd.
    Inventors: Kenkichi Muto, Yohichiro Watanabe, Akihiro Kotsugai
  • Patent number: 5418103
    Abstract: A toner prepared by allowing finely-divided particles of a vinyl resin having an alkali-reactive group to react with a fluorine-containing quaternary ammonium salt to obtain surface-modified finely-divided particles; mixing the surface-modified finely-divided particles and core particles composed of a resin and a coloring agent; and filming the above core particles with the finely-divided particles of the surface-modified vinyl resin with application of mechanical energy thereto.
    Type: Grant
    Filed: September 18, 1992
    Date of Patent: May 23, 1995
    Assignee: Ricoh Company, Ltd.
    Inventors: Kenkichi Muto, Hiroyuki Fushimi, Akihiro Kotsugai, Yoichiro Watanabe, Ian Harpur
  • Patent number: 5061766
    Abstract: A method of producing polymer particles having a particle size distribution of .+-.25% with respect to each average particle size in an amount of 95 wt. % or more, within the average particle sizes ranging from 1 .mu.m to 100 .mu.m, is disclosed, which comprises the steps of: (1) adding a polymer dispersion stabilizer in an amount of 0.1 to 10 wt. % to a hydrophilic organic liquid in which the polymer dispersion stabilizer is soluble; (2) adding thereto at least one vinyl monomer in an amount of not more than 50 times by weight the amount of the polymeric dispersion stabilizer, which monomer is soluble in the hydrophilic organic liquid, but a polymer synthesized from the monomer being swelled or substantially insoluble in the hydrophilic organic liquid; and (3) polymerizing the monomer under the condition that the amount of the vinyl monomer is 200 wt. % or less of the hydrophilic organic liquid.
    Type: Grant
    Filed: September 18, 1989
    Date of Patent: October 29, 1991
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Yamashita, Kenkichi Muto
  • Patent number: 4885350
    Abstract: A method of producing polymer particles having a particle size distribution of .+-.25% with respect to each average particle size in an amount of 95 wt. % or more, within the average particle sizes ranging from 1 .mu.m to 100 .mu.m, is disclosed, which comprises the steps of: (1) adding a polymer dispersion stabilizer in an amount of 0.1 to 10 wt. % to a hydrophilic organic liquid in which the polymeric dispersion stabilizer is soluble; (2) adding thereto at least one vinyl monomer in an amount of not more than 50 times by weight the amount of the polymeric dispersion stabilizer, which monomer is soluble in the hydrophilic organic liquid, but a polymer synthesized from the monomer being swelled or substantially insoluble in the hydrophilic organic liquid; and (3) polymerizing the monomer under the condition that the amount of the vinyl monomer is 200 wt. % or less of the hydrophilic organic liquid.
    Type: Grant
    Filed: August 24, 1987
    Date of Patent: December 5, 1989
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Yamashita, Kenkichi Muto
  • Patent number: 4620987
    Abstract: A surface treatment method for magnetic particles is disclosed, which comprises the steps of activating magnetic particles by application of heat thereto, treating the surface of the magnetic particles with a reactive silane coupling agent, bringing the treated magnetic particles into contact with at least one polymerizable vinyl-type monomer, polymerizing the monomer to form a polymer, and coating the surface of the magnetic particles with the polymer.
    Type: Grant
    Filed: May 25, 1984
    Date of Patent: November 4, 1986
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Yamashita, Kenkichi Muto