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US 7,071,283 B2Granted
Reactive rectification
AssigneeBayer MaterialScience AG
InventorsGerald John, Edmund Dikow, Christine Mendoza-Frohn, Georg Ronge, Rolf Bachmann, Lutz Gottschalk, Michael Prein
Life of this patent
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Abstract
The invention relates to a method for producing polycarbonate according to the method for the transesterification of molten mass whereby bis-(hydroxyaryl) compounds (bisphenols) and diaryl carbonates are reacted by means of reactive rectification.
Claims2
A process for producing polycarbonate comprising:
- (i) forming in a pre-reaction unit a mixture containing a bis(hydroxyaryl) compound and a diaryl carbonate,
- (ii) introducing said mixture through the top of a reactive rectification column under condition calculated to bring about a reaction of said bis(hydroxyaryl) compound with said diaryl carbonate to yield hydroxyaryl,
- (iii) eliminating the hydroxyaryl obtained in (ii) and
- (iv) introducing diaryl carbonate in vapor form at the bottom of said reactive rectification column countercurrent to the pre-reaction mixture.
1 more element
Dependencies are inferred from the claim text.