A MULTILAYER LIDDING FILM BASED ON POLYETHYLENE

Abstract

A lidding film comprising oriented polyethylene bonded to non-oriented polyethylene is disclosed. The oriented polyethylene may comprise a plurality of layers and the non-oriented polyethylene may comprise a plurality of layers, wherein the oriented polyethylene is bonded to the non-oriented polyethylene by extrusion coating or by a laminating adhesive. The oriented polyethylene comprises machine direction oriented polyethylene (MDO PE) or biaxially oriented polyethylene (BOPE). The lidding film may comprise from 1 to 15 wt. % of a polymer other than polyethylene, preferably the lidding film comprises no more than 5 wt. % of a polymer other than polyethylene. Also disclosed is a sealed container comprising a lidding film according to the invention and a polymer tray wherein the lidding film is heat sealed to the top edge of the polymer tray via the non-oriented polyethylene, thereby enclosing a product within a recess defined by the polymer tray. Also disclosed is a method of producing a lidding film.

Claims

1. A lidding film comprising a) oriented polyethylene bonded to b) non-oriented polyethylene, wherein a) the oriented polyethylene may comprise a plurality of layers and b) the non-oriented polyethylene may comprise a plurality of layers, and wherein a) the oriented polyethylene is bonded to b) the non-oriented polyethylene by extrusion coating or by c) a laminating adhesive.

2. A lidding film as claimed in claim 1, wherein the lidding film comprises from 1 to 15 wt. % of a polymer other than polyethylene, preferably wherein the lidding film comprises no more than 5 wt. % of a polymer other than polyethylene.

3. A lidding film as claimed in claim 1, wherein the oriented polyethylene comprises machine direction oriented polyethylene (MDO PE) or biaxially oriented polyethylene (BOPE).

4. A lidding film as claimed in claim 1, wherein the laminating adhesive comprises a solids based polyurethane adhesive or a solvent based polyurethane adhesive.

5. A lidding film as claimed in claim 1, wherein a) the oriented polyethylene has a first surface and a second surface, and wherein the lidding film comprises an ink applied to the first surface of a) the oriented polyethylene.

6. A lidding film as claimed in claim 5, wherein (i) the lidding film is bonded by extrusion coating and the ink is in contact with both the first surface of a) the oriented polyethylene and a surface of b) the non-oriented polyethylene; or (ii) the lidding film is bonded by c) a laminating adhesive, and c) the laminating adhesive is interfaced with the first surface of a) the oriented polyethylene such that the ink is in contact with c) the laminating adhesive.

7. A lidding film as claimed in claim 5, wherein (i) the lidding film is bonded by extrusion coating and the ink is not in contact with a surface of b) the non-oriented polyethylene; or (ii) the lidding film is bonded by c) a laminating adhesive, and c) the laminating adhesive is interfaced with the second surface of a) the MDO polyethylene such that the ink is not contact with c) the laminating adhesive.

8. A lidding film as claimed in claim 1, wherein the lidding film comprises a lacquer.

9. A lidding film as claimed in claim 1, wherein b) the non-oriented polyethylene comprises one or more additives, optionally selected from a gas barrier, a UV filter and an anti-fogging additive.

10. A lidding film as claimed in claim 9, wherein b) the non-oriented polyethylene comprises a gas barrier, and wherein the gas barrier comprises an ethylene-vinyl alcohol (EVOH) copolymer.

11. A lidding film as claimed in claim 10, wherein the gas barrier comprises EVOH interposed between tie layers, optionally wherein the tie layers comprise ethylene methacrylic acid.

12. A lidding film as claimed in claim 9, wherein b) the non-oriented polyethylene comprises a UV filter, and wherein the UV filter comprises a sorbitan ester.

13. A lidding film as claimed in claim 9, wherein b) the non-oriented polyethylene comprises an anti-fogging additive, and wherein the anti-fogging additive comprises a fluorescent whitening agent.

14. A lidding film as claimed in claim 1, wherein b) the non-oriented polyethylene comprises at least three layers: two layers of non-oriented polyethylene and a layer of pressure-sensitive adhesive interposed between the two non-oriented polyethylene layers.

15. A lidding film as claimed in claim 1, wherein a) the oriented polyethylene is coated with a gas barrier material, optionally wherein the gas barrier material comprises aluminium oxide or silicon oxide.

16. A lidding film as claimed in claim 1, wherein a) the oriented polyethylene comprises from 3 to 5 layers, and wherein each of the layers comprises oriented polyethylene.

17. A lidding film as claimed in claim 1, wherein b) the non-oriented polyethylene comprises from 5 to 11 layers, and wherein at least two of the layers comprise blown polyethylene.

18. A sealed container comprising: the lidding film as claimed in any preceding claim; a polymer tray having a top edge, the polymer tray defining a recess; wherein the lidding film is heat sealed to the top edge of the polymer tray via the non-oriented polyethylene, thereby enclosing a product within the recess.

19. A method of producing a lidding film as claimed in claim 1, said method comprising (i) bonding a) an oriented polyethylene to b) a non-oriented polyethylene by melting polyethylene and forming it into a thin film of b) non-oriented polyethylene, coating the thin film of b) non-oriented polyethylene onto a) oriented polyethylene, and pressing the b) non-oriented polyethylene onto the coated a) oriented polyethylene; or (ii) bonding a) an oriented polyethylene to b) a non-oriented polyethylene using c) a laminating adhesive.

20. A method of producing a lidding film as claimed in claim 19, wherein bonding a) the oriented polyethylene to b) the non-oriented polyethylene comprises heating a) the oriented polyethylene and/or b) the non-oriented polyethylene when a) the oriented polyethylene and b) the non-oriented polyethylene are in contact.

21. A method of producing a lidding film as claimed in claim 19, comprising coating a) the oriented polyethylene with a gas barrier material, optionally wherein the gas barrier material comprises aluminium oxide or silicon oxide.

Description

FIGURES

[0049] FIG. 1 is a cross-sectional view of a lidding film according to the present invention.

[0050] FIG. 2A is a cross-sectional view of a lidding film according to the present invention in which ink has been applied to a first surface of the oriented polyethylene, such that the ink is in contact with the laminating adhesive, according to a “reverse print” arrangement.

[0051] FIG. 2B is a cross-sectional view of an a lidding film according to the present invention in which ink has been applied to a first surface of the oriented polyethylene, such that the ink is not in contact with the laminating adhesive, according to a “surface print” arrangement.

[0052] FIG. 3 shows the lidding film heat sealed to a tray.

[0053] FIG. 1 shows a lidding film (1) comprising a) oriented polyethylene (2) bonded to b) non-oriented polyethylene (3) by c) laminating adhesive (4). The oriented polyethylene comprises a plurality of layers (2a) and b) the non-oriented polyethylene comprises a plurality of layers (3a, 3b, 5 and 6). In FIG. 1 the oriented polyethylene comprises 4 layers of oriented polyethylene (2a), 6 layers of non-oriented polyethylene (3a, 3b), a layer of a gas barrier (5) and two tie layers (6). One of the layers of non-oriented polyethylene (3b) is a UV filter/anti-fogging additive/non-oriented polyethylene layer. The numbers of layers and/or the combinations of additives may be varied depending on the intended application of the lidding film (1).

[0054] FIG. 2A shows a lidding film in which ink (8) has been applied to a first surface of a) the oriented polyethylene (2), such that the ink is in contact with the laminating adhesive (4), according to a “reverse print” arrangement. Please note that the ink (8) may or may not form a continuous layer.

[0055] FIG. 2B shows a lidding film in which ink (8) has been applied to a first surface of a) the oriented polyethylene (2), such that the ink (8) is not in contact with the laminating adhesive (4), according to a “surface print” arrangement. Please note that the ink (8) may or may not form a continuous layer. The “surface print” lidding film also includes a lacquer (9) to help prevent migration of the ink (8).

[0056] FIG. 3 shows the lidding film (1) of the present invention heat sealed to a tray (10). A food product such as meat or cheese may be enclosed within the lidding film (1) and tray (10).