Back to results
US 5,854,377 AGranted
Continuous preparation of thermoplastic polyesters
AssigneeBASF SE
InventorPeter Braune
Life of this patent
Estimating the term…
Abstract
A process for the continuous preparation of thermoplastic polyesters by a) a first step of (trans)esterifying a dicarboxylic acid or its esters or ester-forming derivatives with a molar excess of a dihydroxy compound, b) a second step of precondensing the (trans)esterification product of a), and c) a third step of polycondensing the product of b) comprises carrying out step a) and/or step b) of the process in two or more temperature zones.
Claims7
A process for the continuous preparation of thermoplastic polyesters by
- a) (trans)esterification of a dicarboxylic acid or its esters or ester-forming derivatives with a molar excess of a dihydroxy compound,
- b) precondensation of the (trans)esterification product of a), and
- c) polycondensation of the product of b), wherein
- i) the (trans)esterification is carried out in two or more temperature zones and under substantially identical pressure conditions, the temperature of a subsequent temperature zone being 1.degree.-40.degree. C. higher than the temperature of the preceding zone, and
- ii) the precondensation reaction is carried out in two or more temperature zones, the temperature of a subsequent temperature zone being 1.degree.-40.degree. C. higher than the temperature of the preceding zone.
2 more elements
Dependencies are inferred from the claim text.