Co-extrusion is defined as the process in which two or more plastic materials are extruded through a single die. In this process, two or more orifices are arranged in such a manner that the conjoint merging and welding of the extrudates takes place and before chilling, a laminar structure forms. In co-extrusion, a separate extruder is used to fed every material to the die but the orifices can be arranged in such a manner that each extruder provides two or more plies of the same material.