Extruded multiple plastic layer coating bonded to the outer surface of a

Abstract

A multi-layer tube having a metal tube having an outer surface and a zinc layer bonded to the metal tube outer surface. The zinc layer being selected from the group consisting of zinc plating, zinc nickel alloys, zinc cobalt alloys, zinc aluminum alloys, and mixtures thereof. A surface treatment layer is bonded to the zinc layer, wherein the surface treatment layer is selected from the group consisting of a zinc/aluminum/rare earth alloy, phosphate, chromate and mixtures thereof. A first polymeric layer is bonded to the surface treatment layer, wherein the first polymeric layer is selected from the group consisting of a thermoplastic elastomer, an ionomer, a nylon, a fluoropolymer, and mixtures thereof. A second polymeric layer is bonded to the first polymeric layer, wherein the second polymeric layer is selected from the group consisting of a nylon, a thermoplastic elastomer, a fluoropolymer, and mixtures thereof. The tube also has a continuous interior layer made of non-reactive material which is preferably made of a polymeric material which is substantially non-reactive in the presence of short chain alcohols. The process for manufacturing the multi-layer tubing of the present invention also includes the steps of positioning a length of non-reactive tubing into the interior of unsealed metal tube, sealing the metal tube with the non-reactive tubing contained within and extruding multiple layers of a melt-processible thermoplastic onto the external surface metal tube the external surface can be pretreated with at least a zinc based coating and a sealant coating on top of the zinc based coating.