Abstract: A double-walled tube assembly has an elongate inner tube of thermoplastic resin, and an elongate extruded outer tube of thermoplastic resin including a plurality of ribs having a constant height longitudinally of the outer tube and extending over the entire length of the outer tube, the ribs projecting toward the center of the outer tube. The ribs have distal ends fused to the outer perpiheral surface of the inner tube over the entire length of the inner and outer tubes. The rib width is from 0.5 to 1.5 mm. To continuously manufacture the double-walled tube assembly, the pre-molded inner tube is fed to an extrusion molding machine having a cross-head die, and thermoplastic resin is extruded from the cross-head die into an elongate outer tube around the inner tube.

Abstract: A resin composition of a saponified product of an ethylenic copolymer, which comprises 100 parts by weight of a saponified product of a copolymer of ethylene and vinyl acetate having 5 to 50 mol % of recurring units of --CH.sub.2 --CH.sub.2 -- based on the ethylene monomer and also having a saponification degree of about 80% or more and 5 to 150 parts by weight of a polyamide having a relative viscosity of 2.1 to 3.5 and being subjected to terminal end modification leaving carboxylic end groups of 3.times.10.sup.-5 equivalent/g or less.The resin composition of the present invention has the gas barrier property, rigidity and heat resistance, and also is improved in pinhole resistance or impact resistance, and therefore it can be suitably used as packaging materials or functional parts.

Abstract: Disclosed is a polyamide composition comprising a polyamide and, incorporated therein, 0.01 to 20% by weight, based on the composition, of imidazole.This composition may further comprise electrically conductive carbon black in an amount of 5 to 50% by weight based on the composition.This polyamide composition is excellent in the fluidity as the melt and a shaped article prepared from this polyamide composition is excellent in the softness.