Preparation of thermoplastic polyesters having a low content of terminal carboxyl groups
AssigneeBASF SE
InventorPeter Braune
Life of this patent
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Abstract
Thermoplastic polyesters are prepared by polycondensation of dihydroxy compounds with dicarboxylic acids or their esters or ester-forming derivatives by a process in which an alkali metal compound or an alkaline earth metal compound is added in an amount of less than 1 mmol, calculated as alkali metal or alkaline earth metal, per kg of polyester.
Claims6
A process for the production of thermoplastic polyesters which process consists essentially of polycondensing dihydroxy compounds with dicarboxylic acids or their esters or ester-forming derivatives in the presence of an alkali metal compound or an alkaline earth metal compound in an amount of less than 1 mmol, calculated as alkali metal or alkaline earth metal, per kg of polyester.
In a process for the preparation of a thermoplastic polyester from dimethyl terephthalate and 1,4-butanediol by a transesterification/polycondensation process, the improvement which comprises:
- adding to the reaction mixture along with the dimethyl terephthalate and 1,4-butanediol from 0.1 to 0.9 mmol of sodium methylate.
Dependencies are inferred from the claim text.