Patents by Inventor Hiroshi Aiga

Hiroshi Aiga 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).

  • Halogenated anthraquinone and their use as near infrared rays absorbing optical filters
    Patent number: 5342974
    Abstract: High-purity 1,4,5,8-tetraanilidoanthraquinones which are substituted at the p-position of at least one of four anilido benzene rings by a halogen atom are good near infrared rays absorbing filters and at prepared from high purity 1,4,5,8-tetrachloroanthraquinone by reaction with a correspondingly substituted aniline or mixture of anilines in the presence of a salt of an aliphatic carboxylic acid,. a benzyl alcohol derivative and copper ions as reaction catalyst.
    Type: Grant
    Filed: December 28, 1988
    Date of Patent: August 30, 1994
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Tsukasa Ohyama, Shizuo Kuroda, Keisuke Takuma, Hiroshi Aiga
  • Dichroic coloring agents for liquid crystal displays
    Patent number: 4883611
    Abstract: Dichroic coloring agents which have a blue to blue-violet hue and have not been used to date for liquid crystal displays are disclosed. These coloring agents are represented by the following formula: ##STR1## wherein X is S or NH; R.sub.1 is a hydrogen atom, halogen atom, alkyl group or alkoxy group; and R.sub.2 is a hydrogen atom, alkyl group, aryl group or aralkyl group.
    Type: Grant
    Filed: September 9, 1988
    Date of Patent: November 28, 1989
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Keisuke Takuma, Sizuo Kuroda, Tsukasa Oyama, Hiroshi Aiga
  • Dichroic azo dyestuffs and liquid crystal composition containing said dyestuffs
    Patent number: 4734218
    Abstract: Provided are novel dichroic azo dyestuffs, which contain skeletons represented by the following general formula: ##STR1## at one terminals of the long axes of the molecules of the azo dyestuffs, and liquid crystal compositions containing the dichroic azo dyestuffs in forms dissolved in liquid crystals. These dichroic azo dyestuffs have large dichroic ratios and high durability, and their compositions are employed as useful display devices.
    Type: Grant
    Filed: July 18, 1986
    Date of Patent: March 29, 1988
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Keisuke Takuma, Kimitoshi Kato, Hiroshi Aiga, Yasuyuki Yamada, Tsutomu Nishizawa
  • Process for producing dianthraquinone-N,N'-dihydrazine and its chlorination product
    Patent number: 4628091
    Abstract: A process for producing dianthraquinone-N,N'-dihydrazine or its chlorination product, which comprises condensing 1-aminoanthraquinone at an elevated temperature in the presence of 1,3-dimethyl-2-imidazolidinone using an oxidizing agent and an alkaline condensing agent, and subjecting the resulting condensation product to a treatment known per se.
    Type: Grant
    Filed: June 13, 1984
    Date of Patent: December 9, 1986
    Assignee: Mitsui Toatsu Chemicals, Inc.
    Inventors: Kimitoshi Kato, Hiroshi Aiga, Tamio Mikoda, Tunehiro Sakai
  • Dyestuff mixtures and process for dyeing polyester fiber therewith
    Patent number: 3955919
    Abstract: Mixtures of water-insoluble monoazo dyestuffs are disclosed together with the dyeing, padding or printing of polyester material therewith.The water-insoluble monoazo dyestuffs of the following general formula (A) ##SPC1##in which Y represents hydrogen, chlorine, bromine, methyl, ethyl, methoxy, ethoxy or cyano; R.sub.1 represents methoxy, ethoxy or phenoxy; R.sub.2 represents methyl or ethyl; R.sub.3 represents hydrogen, methyl, ethyl, cyanoethyl or allyl; and R.sub.4 represents methyl, ethyl, propyl, butyl, allyl or phenyl, are suitable for the production of inexpensive navy shades of good fastness to light, washing, perspiration, sublimation and heat setting; however, difficulties sometimes arise in the case of these dyestuffs.
    Type: Grant
    Filed: April 10, 1973
    Date of Patent: May 11, 1976
    Assignee: Mitsui Toatsu Chemicals, Incorporated
    Inventors: Fumio Fujii, Ken Mukai, Tetsuo Watanabe, Hiroshi Aiga