Process for the production of flame-resistant polyesters
AssigneeLurgi Zimmer GmbH
InventorHeinz-Dieter Schumann
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Abstract
The present invention comprises a process for the production of flame-resistant polyesters with at least 50 mol-% ethylene carboxylate units through esterification or ester interchange and co-polycondensation of at least one diol and a dicarboxylic acid or its dialkyl ester with a carboxyphosphinic acid, whereby the carboxyphosphinic acid, before being added to the co-polycondensation mixture, is dissolved in ethylene glycol of not more than 90.degree. C., and the acid number of this solution is standardized to 50 to 350 mg KOH/g of carboxyphosphinic acid by adding at least one basic alkali metal compound in the absence of oxygen, and said solution is added to the co-polycondensation mixture during the second half of the esterification or ester interchange reaction.
Claims6
A process for the production of flame-resistant polyesters comprising esterification or ester interchange and co-polycondensation of a reaction mixture of at least one diol and at least one dicarboxylic acid or its dialkyl ester with at least one carboxyphosphinic acid of the formula HOOC--R--P(O)(OH)R', wherein R and R' are independently C.sub.1-10 -alkyl or C.sub.6-10 -aryl, wherein a) the carboxyphosphinic acid, before being added to said reaction mixture, is dissolved in ethylene glycol of not more than 90.degree. C. to form a solution, b) the acid number of said solution is standardized to 50 to 350 mg KOH/g of carboxyphosphinic acid by adding at least one basic alkali metal compound to said solution in the absence of oxygen, and c) said solution with a standardized acid number is added to said reaction mixture during the second half of the esterification or ester interchange reaction.
Dependencies are inferred from the claim text.