Multi layer tubing suitable for use in motor vehicles

摘要

A multi-layer tube (10) suitable for use on motor vehicles composed of a cylindrical wall having an outer surface, and an inner surface essentially parallel to the outer surface. The cylindrical wall has a first region (26) having an essentially uniform cross-sectional diameter and a second region (28) which has a cross-sectional diameter differing from the diameter of the first region (26). The second region (28) has at least one convolution or corrugation (30) contiguously adjacent to the cylindrical wall of the first region (26). The cylindrical wall is made up of a thick flexible outer layer (12) having an inner and an outer face, composed of an extrudable melt-processible thermoplastic; a thin intermediate bonding layer (16) bonded to the inner face of the thick outer layer (12), composed of an extrudable melt-processible thermoplastic capable of sufficiently permanent laminar adhesion to the outer layer to prevent delamination during the desired lifetime of the tubing; and an interior layer (14) composed of an extrudable melt-processable thermoplastic which is capable of sufficiently permanent laminar adhesion to the intermediate bonding layer (16) to prevent delamination of the tubing during the desired lifetime. The thermoplastic material in the interior layer has an elongation value at break of at least 150 % and an ability to withstand impacts of at least 2 ft-lbs below about -20 DEG C. The inner layer has a thickness less than the thickness of the outer layer.