Method of making laminates of thermoplastic polymers by a single-channel coextrusion process and melt injector block for use therein

Claim 1

A melt injector block for use in a single channel coextrusion process which comprises a primary channel for a primary stream of molten thermoplastic polymer, one or more secondary channels for one or more secondary streams of molten thermoplastic polymer, and a unified channel for a composite stream, characterised in that at the or each confluence where a secondary channel enters the primary channel the melt injector block also contains guides which commence in the primary channel and continue past the confluence into the unified channel and the primary channel enters the secondary channel between the guides.

Claim 11

A method of making a laminate of thermoplastics materials comprising the steps of: (a) joining in a tube one primary laminaflow stream of molten thermoplastic resin and at least one secondary lamina-flow stream of molten thermoplastic resin to obtain a composite lamina-flow stream of molten thermoplastic resin which has a sharply defined principle juncture or sharply defined principle junctures between the components of the composite stream; (b) passing said composite stream into the manifold of a sheeting extrusion die, the principle juncture plane being parallel to the principle direction of flow of the resin as it passes from the manifold and takes on the shape of sheeting; (c) extruding the composite stream under conditions of lamina-flow whereby a laminate is produced having the edges thereof consisting of thermoplastic resin from the primary extruder; (d) subjecting the laminate to sideways draw in a stenter; and (e) cutting off the edges of said laminate as edge trim, said edge trim consisting at least substantially of thermoplastic resin from the primary extruder; characterised in that at the or each confluence where the or each secondary stream joins the primary stream the or each secondary stream is confined between guides and flows in contact with the primary stream until the velocities match whereby the width of the secondary stream is determined by the distance between the guides.

Claim 12

A method of making a laminate of thermoplastics materials comprising the steps of: (a) joining in a tube one primary laminaflow stream of molten thermoplastic resin and at least one secondary lamina-flow stream of molten thermoplastic resin to obtain a composite lamina-flow stream of molten thermoplastic resin which has a sharply defined principle juncture or sharply defined principle junctures between the components of the composite stream; (b) passing said composite stream into the manifold of a sheeting extrusion die, the principle juncture plane being parallel to the principle direction of flow of the resin as it passes from the manifold and takes on the shape of sheeting; (c) extruding the composite stream under conditions of lamina-flow whereby a laminate is produced having the edges thereof consisting of thermoplastic resin from the primary extruder; (d) subjecting the laminate to sideways draw in a stenter; and (e) cutting off the edges of said laminate as edge trim, said edge trim consisting at least substantially of thermoplastic resin from the primary extruder; characterised in that at the or each confluence where the or each secondary stream joins the primary stream the or each secondary stream is confined between guides and flows in contact with the primary stream until the velocities match whereby the width of the secondary stream is determined by the distance between the guides.