Modular extrusion head, method, intermediate product and final product

Abstract From the Canadian patent

A modular extrusion head is disclosed including a plurality of cross head die modules, each including a flow path for a single resin. Molten resin layers are flowed from the modules onto a stepped mandrel and then along the mandrel and out an extrusion die to form a multi-layer parison. The layers are thin with a uniform thickness and hole free. The modules are temperature zoned to permit flowing of a low temperature resin to and along the mandrel in contact with a high temperature resin without impairing the properties of the low temperature resin.