Patents by Inventor Hoi W. Yoo

Hoi W. Yoo 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 forming polyesters
    Patent number: 5286836
    Abstract: A process for forming polyesters that comprises the steps of esterifying a terephthalic acid and an ethylene glycol to produce an esterification product containing a bis (betahydroxyethyl) terephthalate, and continuously polycondensing the obtained esterification product to form a polyester. In both the esterifying step and the polycondensing step, a reaction catalyst consisting of a compound of antimony and a compound of titanium is used. The weight ratio of the compound of antimony to the compound of titanium is 0.01 to 100. The process of the present invention can considerably reduce both the esterification time and the polycondensation time and provides good color, reduced diethylene glycol content and reduced condensation of terminal carboxyl groups in the resulting polyesters.
    Type: Grant
    Filed: April 27, 1993
    Date of Patent: February 15, 1994
    Assignee: Korea Institute of Science and Technology
    Inventors: Sang S. Park, Hoi W. Yoo, Chung Y. Kim, Hyun N. Cho