Column system process for polyester plants

US4254246A · kind A · utility

Assignee

• Davy International AG · DE

Inventors

• Ovidiu Dicoi · Offenbach am Main, DE
• Hans Wewer · Schöneck, DE

Key dates

• Filing date: Mar 26, 1979
• Grant date: Mar 3, 1981
• Expiry date: Mar 26, 1999

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S203/06
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A new process for use with continuously operated plants for the production of polyester polymers suitable for producing fibers, bottles and film, by reacting ethylene glycol and terephthalic acid in the presence of a catalyst so that the vapour by-products from the esterification, prepolycondensation and polycondensation stages are continuously rectified in two in-line columns yielding ethylene glycol of high purity (99.85%) which is returned to the process, waste water with 400 ppm ethylene glycol, and a heavy fraction containing oligomers, diethylene glycol, etc. Moreover, an improvement in the quality of the esterified product is attained as it contains less than 0.6% diethylene glycol without the use of diisopropylamine, a poisonous additive.