Process for producing polytrimethylene terephthalate (PTT)

US6800718B1 · kind B1 · utility

Assignees

• Zimmer, Inc. · US
• SHELL OIL COMPNY · US

Inventors

• Fritz Wilhelm · Karben, DE
• Eckhard Seidel · Frankfurt, DE
• Hans Reitz · Rosbach, DE
• Ulrich Thiele · Bruchköbel, DE
• Klaus Mackensen · Frankfurt am Main, DE
• Donald R. Kelsey · Brookshire, US
• Robert Lawrence Blackbourn · Houston, US
• Robert Stephen Tomaskovic · Richmond, US

Key dates

• Filing date: Jul 31, 2002
• Grant date: Oct 5, 2004
• Expiry date: Jul 31, 2022

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G63/183
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Process of producing polytrimethylene terephthalate (PTT) by esterification of terephthalic acid (TPA) with trimethylene glycol (TMG) in the presence of a catalytic, titanium compound, precondensation and polycondensation. The esterification is effected in at least two stages, where in the first stage a molar ratio of TMG to TPA of 1.25 to 2.5, a content of titanium of 0 to 40 ppm, a temperature of 245 to 260° C. as well as a pressure of 1 to 3.5 bar are adjusted. In the at least one subsequent stage a content of titanium is adjusted which is higher than in the initial stage by 35 to 110 ppm. For generating the vacuum in the polycondensation and in the precondensation, there are used vapor jet pumps operated with TMG vapor.