Patent ID: 8153215

Claim:
A tubular or pipe multilayer structure comprising at least one internal layer and an external layer, wherein the tubular or pipe multilayer structure has an opening at each end thereof, wherein the external layer is the outermost layer of the multilayer structure, wherein at least the internal layer is formed from a composition consisting of at least one thermoplastic polyamide and at least one impact-resistance modifier that is a polyolefin, the at least one impact-resistance modifier being present at a concentration by weight of between 10 and 50% of said composition, and in that at least the external layer is formed from a composition comprising as a polymer matrix a polyamide composition comprising: (i) a polyamide thermoplastic copolymer obtained by copolymerization of E-caprolactam, and a mixture of hexamethylenediamine with a diacid comprising at least 9 carbon atoms, the ratio by weight between the ε-caprolactam and the total amount of hexamethylenediamine and diacid being between 4 and 9, or (ii) a mixture of at least said thermoplastic polyamide copolymer (i) and at least one second thermoplastic polyamide or copolyamide obtained by polymerization of monomers comprising fewer than 9 carbon atoms, the content by weight of the second thermoplastic polyamide or copolyamide in the polymer matrix being between 0 and 80% by weight, wherein the at least one internal layer is in direct contact with the external layer.