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Method for preparing a polycarbonate oligomer mixture at low temperature for manufacturing polycarbonate

  • US 7,041,775 B2
  • Filed: 04/21/2004
  • Issued: 05/09/2006
  • Est. Priority Date: 04/20/2004
  • Status: Expired due to Fees
First Claim
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1. A method of preparing a polycarbonate oligomer mixture comprising the steps of:

  • (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises,i. a melted activated diaryl carbonate composition, andii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers,(b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system,(c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and(d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture.

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