Process for producing polycarbonate—point of addition of the chain terminator
AssigneeCovestro Intellectual Property GmbH & Co. KG
InventorsRolf Bachmann, Antonio Ortiz, Josef Bartholomei, Marten Voelker, Jan Heijl
Life of this patent
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Abstract
The present invention relates to a process for producing polycarbonate according to a phase boundary process, from at least one dihydroxydiaryl alkane, phosgene, at least one catalyst and at least one chain terminator, the process producing polycarbonate with a low proportion of oligomers and a low proportion of Di-chain terminator carbonate. The process according to the invention is characterized in that the chain terminator is added to the reaction system at a designated time.
Claims18
A process for producing polycarbonate by an interfacial process from at least one dihydroxydiarylalkane, phosgene, at least one catalyst, and at least one chain terminator, wherein
- (i) the at least one chain terminator is introduced into a reaction system comprising at least the at least one dihydroxydiarylalkane, the phosgene, and a reaction product R of the at least one dihydroxydiarylalkane and the phosgene at a point at which the reaction product R is a mixture of compounds and these compounds on average have a degree of polymerization of at least one unit and at most three units formed from the at least one dihydroxydiarylalkane by the reaction with the phosgene;
- and
- (ii) the process comprises the step of at least one addition of an aqueous alkali metal hydroxide solution, wherein the addition of the at least one chain terminator to the reaction system in process step (i) takes place prior to the first of the one or more additions of the aqueous alkali metal hydroxide solution.
Dependencies are inferred from the claim text.