Fluoropolymer composite tube and method of preparation

A method of preparing a multi-layered tube comprising the steps of:

• forming an inner tubular layer of a fluoropolymer substrate having an outer surface and an inner surface;
• chemically activating said outer surface of said fluoropolymer substrate by subjecting said surface to a charged, substantially non-inert gaseous atmosphere by electrically ionizing a gas which contacts said surface;
• and
• chemically bonding without an intervening adhesive layer an outer tubular layer of a polymer selected from the group consisting of amide urethane elastomers, chlorinated polyethylene, chlorosulfonated polyethylene, copolyether ester, epichlorohydrin, ethylene acrylic, fluoroelastomer, perfluoroelastomer, fluorosilicone, hydrogenated nitrile butyl, nitrile, polyacrylate, polyester urethane, polyether urethane, polysulfide, polyurethane, silicone, styrene butadiene, styrenic elastomer, ethylene/acrylic elastomer, and thermoplastic elastomers by applying said polymer to the chemically activated fluoropolymer substrate so as to form chemical bonds between the layers.

A method of preparing a tube comprising the steps of:

• continuously extruding a first tubular layer of a thermoplastic fluoropolymer from a first extrusion station, wherein said layer is a substrate having an outer surface and an inner surface;
• providing a plasma treatment station, said station being operative to create a plasma from ambient air at atmospheric pressure;
• using said station to create the plasma from ambient air at atmospheric pressure;
• continuously advancing said fluoropolymer substrate along a first portion of an extrusion line and through said plasma treatment station so that the entirety of the outer surface of said fluoropolymer substrate is contacted by said plasma so that said outer surface is chemically activated;
• continuously advancing said chemically activated substrate along a second portion of said extrusion line to a second extrusion station;
• and
• continuously extruding a second tubular layer of a non-fluorine-containing polymer selected from the group consisting of amide urethane elastomers, chlorinated polyethylene, chlorosulfonated polyethylene, copolyether ester, epichlorohydrin, ethylene acrylic, fluoroelastomer, perfluoroelastomer, fluorosilicone, hydrogenated nitrile butyl, nitrile, polyacrylate, polyester urethane, polyether urethane, polysulfide, polyurethane, silicone, styrene butadiene, styrenic elastomer, ethylene/acrylic elastomer, and thermoplastic elastomers onto said chemically activated substrate so as to form chemical bonds between the layers without an intervening adhesive layer.