Patents by Inventor Takaaki Kohtaki

Takaaki Kohtaki 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: 5439770
    Abstract: A toner for developing an electrostatic image is constituted by at least a binder resin and a charge control agent. The binder resin has an acid value of 5-50. The charge control agent comprises an iron complex represented by the following formula: ##STR1## wherein X.sub.1 and X.sub.2 independently denote hydrogen atom, lower alkyl group, lower alkoxy group, nitro group or halogen atom; m and m' denote an integer of 1-3; R.sub.1 and R.sub.3 independently denote hydrogen atom, C.sub.1-18 alkyl or alkenyl, sufonamide, mesyl, sulfonic acid group, carboxy ester group, hydroxy, C.sub.1-18 alkoxy, acetylamino, benzoylamino or halogen atom; n and n' denote an integer of 1-3; R.sub.2 and R.sub.4 denote hydrogen atom or nitro group; and A.sup.+ denotes hydrogen ion, sodium ion, potassium ion or ammonium ion. The toner has a weight-average particle size (D.sub.4) of 4-9 .mu.m and including toner particles having a particle size of 5 .mu.m or smaller at 3-90% by number, toner particles having a particle size of 6.35-10.
    Type: Grant
    Filed: April 15, 1994
    Date of Patent: August 8, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Masaaki Taya, Takaaki Kohtaki, Makoto Unno, Tadashi Doujo
  • Patent number: 5391450
    Abstract: A novel method for heat-pressure fixing color toner images in which:(1) a toner produced by suspension polymerization and containing a wax of a certain molecular weight and a certain melting point in a certain amount, wherein the wax is enclosed in each particle by a vinyl resin, and THF soluble matters having specific molecular weight distribution and is used in conjunction with(2) a fixing means comprising a fixing roller and a pressure roller in mutual pressure contact, through which the transfer medium comes out in the direction inclined toward the pressure roller, and wherein the surface of the fixing roller comprises a fluorine-containing material.
    Type: Grant
    Filed: April 22, 1994
    Date of Patent: February 21, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takayuki Nagatsuka, Tatsuya Nakamura, Hiromi Mori, Takaaki Kohtaki
  • Patent number: 5346792
    Abstract: A color toner is constituted to form a polyester binder resin and a colorant. The polyester resin is obtained from a monomer mixture including, at least: 25-35 mol. % of a dibasic aromatic acid component (a) selected from isophthalic acid, terephthalic acid and derivatives thereof; 2-4 mol. % of a tribasic aromatic acid component (b) selected from trimellitic acid and derivatives thereof; 12-18 mol. % of a dibasic acid component (c) selected from dodecenylsuccinic acid, octylsuccinic acid, and anhydrides thereof; and 45-60 mol. % of an etherified diphenol component (d) obtained by propoxidation or/and epoxidation, each percentage being based on a total of the monomers. The polyester resin is characterized by having a hydroxyl value of 10-20, a weight-average molecular weight (Mw) of 13,000-20,000, a number-average molecular weight (Mn) of 5,000-8,000, and an Mw/Mn ratio of 2-3.5.
    Type: Grant
    Filed: June 8, 1992
    Date of Patent: September 13, 1994
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroyuki Kobayashi, Takaaki Kohtaki
  • Patent number: 5250382
    Abstract: A toner for developing an electrostatic image has toner particles containing i) a binder resin comprising a resin composition with a domain-matrix structure and ii) a colorant.The resin composition with a domain-matrix a structure is comprised of a resin P1 that forms domain particles and a resin P2 that forms a matrix. The resin P1 has a glass transition temperature Tg1 of from 0.degree. C. to 60.degree. C., and the resin P2 has a glass transition temperature Tg2 of from 40.degree. C. to 90.degree. C. The glass transition temperature Tg2 of the resin P2 is at least 5.degree. C. higher than the glass transition temperature Tg1 of the resin P1, and the domain particles having an average particle diameter of not larger than 5 .mu.m.
    Type: Grant
    Filed: December 26, 1991
    Date of Patent: October 5, 1993
    Assignee: Canon Kabushiki Kaisha
    Inventors: Minoru Shimojo, Takaaki Kohtaki, Tsuyoshi Takiguchi
  • Patent number: 5102761
    Abstract: A color toner for developing an electrostatic latent image, which includes a binder resin, a xanthene-type dye and a compound containing a phenolic --OH (hydroxyl) group.
    Type: Grant
    Filed: May 1, 1990
    Date of Patent: April 7, 1992
    Assignee: Canon Kabushiki Kaisha
    Inventors: Ichiro Ohsaki, Takaaki Kohtaki, Yuko Sato, Hiroyuki Kobayashi, Toshiyuki Ugai
  • Patent number: 4904562
    Abstract: An encapsulated toner for electrophotography is produced through a process, comprising: preparing a solution of a shell material resin set to an acidic (or basic) pH region; dispersing solid core particles in the solution to form a dispersion; changing the pH of the dispersion to a pH region, which is preferably a basic (or acidic) pH region, where the shell material resin is precipitated from the dispersion; and coating the solid core particles with the precipitated shell material resin. The shell material is preferably a proton-attracting basic (or dissociative acidic) vinyl-type copolymer and is dissolved in a pH-adjusted aqueous medium comprising water and a polar solvent, such as a lower alcohol. Thus, an encapsulated toner with excellent triboelectric chargeability and environmental characteristic is prepared without coalescence of capsules or formation of free shells.
    Type: Grant
    Filed: September 23, 1987
    Date of Patent: February 27, 1990
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroshi Yusa, Takaaki Kohtaki, Masuo Yamazaki, Yasutaka Akashi
  • Patent number: 4510293
    Abstract: A process for catalytically hydrogenating a carbon-carbon double bond of a conjugated diene polymer by introducing hydrogen in the solution of said polymer, characterized in that a palladium salt of a carboxylic acid is used as a catalyst.
    Type: Grant
    Filed: December 13, 1983
    Date of Patent: April 9, 1985
    Assignee: Nippon Zenn Co. Ltd.
    Inventors: Yoichiro Kubo, Takaaki Kohtaki, Kiyomori Oura