Polyamides having improved color and processibility and process for manufacturing

  • US 6,191,251 B1
  • Filed: 12/22/1994
  • Issued: 02/20/2001
  • Est. Priority Date: 02/18/1993
  • Status: Expired due to Term
First Claim
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1. A process for reducing the initial yellowness and improving the color stability of a polyamide composition by using a phosphorus compound while preventing the polyamide from increasing significantly in molecular weight during subsequent processing by deactivating the catalytic effect of the phosphorus compound, comprising the steps ofpreparing a polyamide composition from an amino acid or a diamine and a diacid, comprising polymerizing at least one polyamide-forming reactant in the presence of, or introducing into a polyamide melt, (a) a phosphorus compound which does not have a direct carbon-phosphorus bond selected from the group consisting of (1) phosphorous acids, (2) phosphorous acid salts selected from the group consisting of phosphorous acid salts of Groups IA and IIA, manganese, zinc, aluminum, ammonia, and alkyl and cycloalkyl amines and diamines, and (3) phosphorous organic esters which undergo hydrolysis in the presence of water to form inorganic phosphorous acids or salts;

  • and (b) a Group IA base selected from hydroxides, oxides, carbonates, bicarbonates, alkoxides, and hydrides, wherein the phosphorus compound is added in an amount sufficient to yield a phosphorus concentration ranging from 0.097 mol to 0.944 mols phosphorus per million grams polyamide, and the base is added in an amount sufficient to yield a base concentration ranging from 1.785 mols to 33.325 mols base per million grams polyamide, wherein the molar ratio of base to phosphorus is at least 5.3.

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