The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 07, 1993
Filed:
Aug. 12, 1991
Chung Y Kim, Seoul, KR;
Hyun N Cho, Seoul, KR;
Korea Institute of Science and Technology, Seoul, KR;
Abstract
A method for forming polyesters (polyethylene terephthalate, PET) having a high degree of polymerization with improved color and lower diethylene glycol (DEG) content in a shorter period of time than in known methods. The method according to the invention comprises forming oligomers from ethylene glycol and terephthalic acid by esterification, forming prepolymers having a degree of polymerization ranging from 10 to 50 by polycondensing the resulting oligomers for an optimum time, forming polyesters by polycondensing the oligomers and the prepolymers in a weight ratio ranging from 1:0.1 to 1:90, thereby providing polyesters of improved color and low DEG content in a short time.