Patents by Inventor Nien-Hsi Chang

Nien-Hsi Chang 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).

  • Preparation of polyesters from terephthalic acid
    Patent number: 4780527
    Abstract: Poly(butylene terephthalate) is prepared in a two-stage process wherein terephthalic acid and 1,4-butanediol are esterified in the presence of a catalytic amount of a catalyst having an organo-metallic component which is an organo-titanate compound, an organo-tin compound or a combination thereof and a salt component which is an organic acid salt or an inorganic salt. In a second step, the esterification product is subject to polycondensation. By following the foregoing procedure, the formation of tetrahydrofuran is significantly suppressed and the percent conversion of esterification products increased.
    Type: Grant
    Filed: May 6, 1987
    Date of Patent: October 25, 1988
    Assignee: Industrial Technology Research Institute
    Inventors: Shen-Nan Tong, Mei-Sui Chen, Wu-Bin Yuo, Nien-Hsi Chang