Patents by Inventor Toshiaki Takuma

Toshiaki Takuma 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).

  • Process for producing terephthalic acid suitable for use in direct polymerization
    Patent number: 4594449
    Abstract: A process for producing terephthalic acid suitable for use in direct polymerization, which comprises oxidizing p-xylene with molecular oxygen in an acetic acid solvent in the presence of a heavy metal compound and a bromine compound, wherein after a main reaction step of oxidizing at least 90 mole % of p-xylene fed has been performed,(1) a first purifying step of feeding a gas containing molecular oxygen to the oxidation reaction mixture obtained from the main reaction step in such a proportion that the concentration of oxygen in the off-gas becomes at least 0.5% by volume and smashing the oxidation reaction mixture at a temperature of 140.degree. to 230.degree. C. to decrease the average particle diameter of terephthalic acid by at least 20% from its average particle diameter before smashing, and(2) a second purifying step of feeding a gas containing molecular oxygen to the slurry from the first purifying step in such a proportion that the concentration of oxygen in the off-gas becomes 0.
    Type: Grant
    Filed: November 29, 1983
    Date of Patent: June 10, 1986
    Assignee: Kuraray Yuka Co., Ltd.
    Inventors: Toshiaki Takuma, Takayuki Tsumura, Takanori Tsugiya, Katsuya Murakami, Yasue Nakajima