Process for production of polypropylene terephthalate

US5798433A · kind A · utility

Assignees

• Zimmer, Inc. · US
• Degussa AG · DE

Inventors

• Wolfgang Schmidt · Frankfurt, DE
• Ulrich Thiele · Bruchköbel, DE
• Stephanie Schauhoff · Frankfurt, DE
• Dahai Yu · Bad Orb, DE

Key dates

• Filing date: Oct 1, 1997
• Grant date: Aug 25, 1998
• Expiry date: Oct 1, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G63/82
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The present invention provides a method of synthesizing polypropylene terephthalate with no more than 5 ppm acrolein and no more than 3 ppm allyl alcohol. The method comprises direct esterification of terephthalic acid with 1,3-propanediol in the presence of 30 to 200 ppm titanium in the form of an inorganic esterification catalyst containing at least 50 mol % TiO.sub.2 precipitate, blocking the esterification catalyst after esterification by adding 10 to 100 ppm phosphorus in the form of a phosphorus-oxygen compound, and then performing precondensation and polycondensation in the presence of 100 to 300 ppm antimony in the form of a conventional antimony polycondensation catalyst and optional conventional coloring agent.