Metallic pipe having a hydrolysis-resistant layer of a polyamide moulding composition
摘要:
A metallic pipe for contact with a hydrolyzing medium provides longer operating times and improved high temperature resistance. The pipe contains a layer of a polyamide moulding composition containing at least 50% by weight of polyamide content containing: I) 60 to 98 parts by weight of a polyamide which contains 10 to 70 meq/kg of a terminal carboxy group and has a relative solution viscosity ηrel of at least 1.90, and II) 2 to 40 parts by weight of a polyamine-polyamide graft copolymer produced from: a) 0.5 to 25% by weight, based on the entire monomer mixture, of a polyamine having at least 4 nitrogen atoms, and b) 75 to 99.5% by weight, based on the entire monomer mixture, of polyamide-forming monomers selected from lactams, ω-aminocarboxylic acids and/or equimolar combinations of diamine and dicarboxylic acid, with the proviso that the amino group concentration of the graft copolymer is in the range from 100 to 2500 meq/kg, wherein the sum of the parts by weight of I) and II) is 100.
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