Abstract: Multilayer plastic pipes comprising a polyamide-based inner and outer layer, wherein the inner and outer layer are connected force-lockingly by means of at least one intermediate layer made of a mixture of a linear crystalline polyester and a polyamide, have improved stability to chemical agents and improved mechanical properties.

Abstract: A plastic pipe having improved resistance, inter alia, to methanol-containing fuels and improved mechanical properties comprising:(I) an outer layer made of a moulding compound based on polyamide,(II) an intermediate layer adjacent to the outer layer and made of a moulding compound based on a mixture of:(a) of from 95 to 99% by weight of a linear crystalline polyester, and(b) of from 1 to 5% by weight of a compound having at least two isocyanate groups,wherein the isocyanate groups originating from component (IIb) are present in the mixture of (IIa) and (IIb) in a concentration of from 0.03 to 0.

Abstract: Multilayer plastic pipe comprising at least one outer layer based on polyamide and at least one layer of a linear, crystalline polyester modified by means of an isocyanate mixture exhibits improved resistance, inter alia, to methanol-containing fuels and improved mechanical properties.

Abstract: A multilayer plastic pipe having improved barrier action against diffusion of the substance being transported, particularly methanol-containing fuels, dimensional stability, resistance to mechanical stress, and particularly improved adhesion between layers is provided comprising:(A) an inner layer and an outer layer, each of which comprise a polyamide-based molding composition, wherein the inner layer and outer layer may be the same or different, and (B) at least one intermediate layer comprisinga) 95 to 60% by weight of a linear, crystalline polyester andb) 5 to 40% by weight of a polymer containing reactive groups other than epoxide groups,wherein the reactive groups are contained in a concentration of from 4 to 95 mmol/kg based on the total amount of component (B); and wherein the layers are intimately bonded to one another.

Abstract: A plastic pipe having improved resistance to methanol-containing fuels and improved mechanical properties is provided. This is achieved by a multilayer plastic pipe consisting of at least one outer layer based on polyamide and at least one layer of a linear, crystalline polyester modified with isocyanates. With the aid of the invention it is possible to obtain plastic pipes having improved barrier properties against methanol-containing fuels and dimensional stability and mechanical load-bearing capacity.