Abstract: A large concentric co-extrusion die (1) is described having a plurality of annular or conical die mandrel layers (201-205). Each layer is formed between a pair of adjacent annular or conical die mandrels (101-106) defining between them a flow path for molten thermoplastics material from an inlet to an annular extrusion outlet (110) through which a thermoplastics tubular extrusion is formed in use. Extrusion takes place through the multiple annular layer outlets (301-305) to form a multi-layered product. At least one layer (203) of the annular or conical die mandrels has a plurality of molten material inlets arranged around the external circumference of the co-extrusion die with each inlet being connected to a feed channel (403) which has plural bifurcations (403.1, 403.2, 403.3) providing 2n subsidiary outlet feed channels (503) where n is the number of bifurcations. Each subsidiary outlet feed channel being connected to a corresponding helical outlet channel (703).

Abstract: The present invention provides a multilayered polymeric film with a luminous transmittance greater than 30% when measured using ASTM-D 1003-92, for covering an agricultural structure or greenhouse, wherein the film contains adjacent layers that have an average delamination strength of less than 250 g/15 mm when measured using ASTM D-1876. More particularly, the film is thus separated into two or more film layers which are inflated with gas to provide thermal insulation.

Abstract: A large concentric co-extrusion die (1) is described having a plurality of annular or conical die mandrel layers (201-205). Each layer is formed between a pair of adjacent annular or conical die mandrels (101-106) defining between them a flow path for molten thermoplastics material from an inlet to an annular extrusion outlet (110) through which a thermoplastics tubular extrusion is formed in use. Extrusion takes place through the multiple annular layer outlets (301-305) to form a multi-layered product. At least one layer (203) of the annular or conical die mandrels has a plurality of molten material inlets arranged around the external circumference of the co-extrusion die with each inlet being connected to a feed channel (403) which has plural bifurcations (403.1, 403.2, 403.3) providing 2n subsidiary outlet feed channels (503) where n is the number of bifurcations. Each subsidiary outlet feed channel being connected to a corresponding helical outlet channel (703).