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Polybutylene terephthalate

  • US 4,014,858 A
  • Filed: 05/12/1975
  • Issued: 03/29/1977
  • Est. Priority Date: 05/12/1975
  • Status: Expired due to Term
First Claim
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1. The process of carrying out a first stage polyesterification which comprises reacting a polyhydric alcohol and a polycarboxylic acid compound in a concentration of 1.1 to 4 hydroxyl equivalents per carboxyl equivalent under polyesterification conditions at about 180°

  • to 250°

    C. in the presence of a catalytic concentration of a tetravalent tin compound having one organo to tin linkage, per tin atom wherein 1,4-butane diol provides from 75 to 100 equivalent percent of the hydroxyl groups of the polyhydric alcohol compound, a terephthalic acid compound provides from 75 to 100 equivalent percent of the carboxyl groups of the polycarboxylic acid compound and at least 50 percent of the carboxyl equivalents are provided by terephthalic acid.

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