Corrugated paperboard

1. A corrugated paperboard comprising a corrugated medium and a lamination adhered together, with the lamination comprising (a) a liner, (b) a layer of a water resistant polymer which is also resistant to temperatures of at least 150° C. that are generated in a corrugating process, and (c) an extrusion layer which holds together the liner and the water resistant polymer layer and which resists delamination at the corrugating process temperatures, and wherein the extrusion layer comprises a multilayer arrangement that comprises (a) opposed outer layers of a highly adhesive polymer and (b) a middle layer of a blend of low cost high and lower melting point polymers.

2. The corrugated paperboard defined in claim 1 wherein the water resistant polymer layer is made from a polymer or a blend of polymers that is selected to minimise water absorption of the corrugated paperboard and to provide the corrugated paperboard with a glossy finish.

3. The corrugated paperboard defined in claim 2 wherein the water resistant polymer layer is made from a PET.

4. The corrugated paperboard defined in claim 1 wherein the extrusion layer comprises a colour.

5. The corrugated paperboard defined in claim 1 wherein the multilayer arrangement is formed by co-extruding the outer layers and the middle layers.

6. The corrugated paperboard defined in claim 1 wherein one or more than one layer of the multilayer arrangement comprises a colour.

7. The corrugated paperboard defined in claim 1 wherein at least the middle layer comprises a colour.

8. The corrugated paperboard defined in claim 1 wherein the outer layers of the extrusion layer are each between 1 and 10 um thick.

9. The corrugated paperboard defined in claim 1 wherein the high melting point polymer is a high density polymer.

10. The corrugated paperboard defined in claim 1 wherein the lower melting point polymer comprises a low density polymer.

11. The corrugated paperboard defined in claim 1 wherein the highly adhesive, polymer is an ethylene vinyl acetate, an acid modified ethylene acrylate, an anhydride modified ethylene acrylate, an anhydride modified ethylene vinyl acetate, an acid/acrylate modified ethylene vinyl acetate, an anhydride modified ethylene vinyl acetate, an anhydride modified low or high density polyethylene or an anhydride modified polypropylenes.

12. The corrugated paperboard defined in claim 1 wherein the water resistant polymer layer is reverse printed.

13. The corrugated paperboard defined in claim 1 wherein the water resistant polymer layer is printed on an outside surface of the lamination.

14. The corrugated paperboard defined in claim 1 where the water resistant polymer layer is metallised on either side of the layer.

15. A paperboard container made from the corrugated paperboard defined in claim 1 .

16. A paperboard container made from the corrugated paperboard defined in claim 15 which comprises inner wall panels spaced apart from outer wall panels.

17. A corrugated paperboard comprising a corrugated medium and a lamination adhered together, with the lamination comprising (a) a liner, (b) a layer of a water resistant polymer which is also resistant to temperatures of at least 150° C. that are generated in a corrugating process, and (c) an extrusion layer which holds together the liner and the water resistant polymer layer and which resists delamination at the corrugating process temperatures, wherein the extrusion layer comprises a blend of a highly adhesive polymer, a low cost high melting point polymer, a low cost lower melting point polymer and, optionally a colour, and wherein the extrusion layer comprises a concentration gradient so that two opposed outer surface regions of the extrusion layer have a higher concentration of the highly adhesive polymer than an inner region of the extrusion layer, and the inner region has higher concentrations of the low cost high melting point polymer and the low cost lower melting point polymer and the colour(if present) than the surface regions.

18. The corrugated paperboard defined in claim 17 wherein the water resistant polymer layer is made from a polymer or a blend of polymers that is selected to minimise water absorption of the corrugated paperboard and to provide the corrugated paperboard with a glossy finish.

19. The corrugated paperboard defined in claim 17 wherein the water resistant polymer layer is made from a PET.

20. The corrugated paperboard defined in claim 17 wherein the extrusion layer comprises a colour.

21. The corrugated paperboard defined in claim 17 where in the high melting point polymer is a high density polymer.

22. The corrugated paperboard defined in claim 17 wherein the lower melting point polymer comprises a low density polymer.

23. The corrugated paperboard defined in claim 17 wherein the highly adhesive polymer is an ethylene vinyl acetate, an acid modified ethylene acrylate, an anhydride modified ethylene acrylate, an anhydride modified ethylene vinyl acetate, an acid/acrylate, modified ethylene vinyl acetate, an anhydride modified ethylene vinyl acetate, an anhydride modified low or high density polyethylene or an anhydride modified polypropylenes.

24. The corrugated paperboard defined in claim 17 wherein the water resistant polymer layer is reverse printed.

25. The corrugated paperboard defined in claim 17 wherein the water resistant polymer layer is printed on an outside surface of the lamination.

26. The corrugated paperboard defined in claim 17 where the water resistant polymer layer is metallised on either side of the layer.

27. A paperboard container made from the corrugated paperboard defined in claim 17 .

28. A paperboard container made from the corrugated paperboard defined in claim 27 which comprises inner wall panels spaced apart from outer wall panels.