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Method for stably producing an aromatic polycarbonate

  • US 7,563,858 B2
  • Filed: 06/14/2005
  • Issued: 07/21/2009
  • Est. Priority Date: 06/14/2004
  • Status: Active Grant
First Claim
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1. A method for producing an aromatic polycarbonate, which comprises continuously reacting an aromatic dihydroxy compound with a diaryl carbonate in a closed, reactor-pipeline system,said closed, reactor-pipeline system comprising:

  • a plurality of reactors which are liquid-tightly connected through a pipeline toward an outlet for a final aromatic polycarbonate product, said pipeline comprising one or more pipes, wherein said plurality of reactors include at least two reactors connected in series, andat least one filter secured in the pipe or pipes of said reactor-pipeline system,said method further comprising;

    a step of simultaneously or separately taking out the or each filter clogged with foreign matter to the outside of said reactor-pipeline system,a step of subjecting the or each filter to washing in the outside of said reactor-pipeline system, anda step of returning of the resultant washed filter into the inside of the pipe or pipes of said reactor-pipeline system,wherein said washing is performed with the below-mentioned washing agents used in the following order;

    an aqueous solution of a basic compound with a pH value of from 7.5 to 10,an aromatic monohydroxy compound, anda molten mixture of an aromatic dihydroxy compound and a diaryl carbonate, said molten mixture containing a basic compound in an amount of from 1 to 10,000 ppb.

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