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Aromatic polyphosphonates and a process for their production

  • US 4,331,614 A
  • Filed: 06/18/1980
  • Issued: 05/25/1982
  • Est. Priority Date: 06/22/1979
  • Status: Expired due to Term
First Claim
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1. A thermoplastic branched aromatic polyphosphonate of a number average molecular weight of above 11,000 obtained by a transesterification process in which(A) from 99.25 to 99.975 mole parts of at least one diarylphosphonate and(B) from 0.025 to 0.75 mole parts of at least one triarylphosphate or at least one aromatic trihydroxy or tetrahydroxy compound or a mixture thereof with the sum of the mole parts of (A) and (B) being 100 and(C) from 93 to 97 mole parts of at least one aromatic dihydroxy compound are transesterified in the melt at 90°

  • C. to 340°

    C. in a oxygen-free gas atmosphere either at atmospheric pressure or under reduced pressure and in the presence of from 10-5 to 5×

    10-2 mole percent, based on 100 mole percent of aromatic dihydroxy compound, of at least one basic catalyst, with the volatile constituents in the esterification mixture being removed by distillation.

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