FILM COMPOSITE, FILM PACKAGING, AND METHOD FOR THE PRODUCTION OF A FILM COMPOSITE

Abstract

A film composite for film packaging, having a cover film composed of a polyolefin and a barrier layer, wherein the cover film has an imprinting, at least in part, on a side that faces the barrier layer. An equalization layer is arranged between the cover film and the barrier layer, which layer borders, at least in part, on the imprinting, wherein the equalization layer is formed from a hardened material on the basis of polyurethane.

Claims

1. A film composite for film packaging, comprising a cover film composed of a polyolefin, a barrier layer, and an equalization layer arranged between the cover film and the barrier layer, wherein the cover film has an imprinting, at least in part, on a side that faces the barrier layer, wherein the equalization layer borders, at least in part, on the imprinting, and wherein the equalization layer is formed from a hardened material on the basis of polyurethane.

2. The film composite according to claim 1, wherein the barrier layer is formed on the basis of polyurethane.

3. The film composite according to claim 1, wherein the barrier layer follows the equalization layer directly or with the inclusion of an adhesion-imparting layer.

4. The film composite according to claim 1, wherein the hardened material is a polyurethane varnish.

5. The film composite according to claim 1, wherein the proportion of polyolefin, with reference to the total film composite, amounts to more than 90 wt.-%.

6. The film composite according to claim 1, wherein solid particles are arranged in the equalization layer.

7. The film composite according to claim 6, wherein the proportion of the solid particles in the equalization layer amounts to between 5 and 50 vol.-%.

8. The film composite according to claim 6, wherein the solid particles have an average diameter between 150 and 800 nm.

9. The film composite according to claim 6, wherein the solid particles are titanium dioxide particles, at least in part.

10. The film composite according to claim 1, wherein the imprinting does not extend over the full area of the cover film, and wherein the equalization layer encloses the imprinting in such a manner that the equalization layer forms an essentially level surface on the side bordering on the barrier layer.

11. The film composite according to claim 1, wherein the barrier layer has a thickness between 0.5 g/m.sup.2 and 2.5 g/m.sup.2.

12. The film composite according to claim 1, wherein the equalization layer (4) has a thickness between 0.5 g/m.sup.2 and 2.5 g/m.sup.2.

13. The film composite according to claim 1, wherein the barrier layer has a proportion of polyethylenimine (PEI).

14. The film composite according to claim 13, wherein the proportion of polyethylenimine in the barrier layer amounts to between 0.5 and 1.5 wt.-%.

15. The film composite according to claim 1, wherein the cover film is formed from a polyethylene.

16. The film composite according to claim 1, wherein the cover film is connected with a carrier film, in particular with a multi-layer carrier film, by way of a lamination layer.

17. The film composite according to claim 16, wherein the lamination layer borders directly on the barrier layer.

18. The film composite according to claim 17, wherein the carrier film is formed from a polyolefin, in particular from a polyethylene.

19. A film packaging composed of a film composite according to claim 1, wherein the film composite delimits a packaging interior in such a manner that the cover film forms an outside.

20. A method for the production of a film composite according to claim 1, comprising the steps of: providing the cover film; imprinting the cover film at least in part; coating the cover film with a hardenable material, so as to form the equalization layer on the at least partially imprinted side, which material has at least a proportion of polyurethane; and after hardening, coating the equalization layer with a material for forming the barrier layer.

21. The method according to claim 20, wherein the material for forming the barrier layer is formed from a liquid solvent and a proportion of polyvinyl alcohol in solid form.

22. The method according to claim 20, wherein the hardenable material of the equalization layer is smoothed after being applied.

23. The method according to claim 20, wherein the cover film is connected with a carrier film, with the inclusion of a lamination layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0049] In the drawings,

[0050] FIG. 1 shows a film packaging in the form of a side-fold bag for animal feed; and

[0051] FIG. 2 shows a film composite according to the invention, for forming the film packaging according to FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0052] FIG. 1 shows a flexible film packaging 1 in the form of a side-fold bag having two front walls and two side folds arranged between the front walls. The film packaging 1 is formed from a film composite, wherein a cover film 2 forms the outside of the film packaging 1. Furthermore, an imprinting 3 is visible from the outside, which was applied to a side of the cover film 2 that faces the packaging interior of the film packaging 1, and which is visible due to the transparent configuration of the cover film 2. The film packaging 1 is suitable, in particular, for holding packaged goods in piece form, in particular animal feed, wherein the film composite has barrier properties that effectively prevent, in particular, fat migration from the packaging interior to the outside. This barrier effect is produced by means of the structure of the film composite as shown in FIG. 2.

[0053] The structure of the film composite is shown in greater detail in FIG. 2, wherein the materials used as well as the layer thicknesses or weights per surface area of the individual layers can be found in the following table.

TABLE-US-00001 Layer thickness (weight per surface Layer area) Composition Cover film (2) 30 μm (28.5 g/m.sup.2) HDPE Imprinting (3) (2.0 g/m.sup.2) Nitrocellulose varnish Equalization layer (4) (1.0 g/m.sup.2) Two-component PU varnish + TiO.sub.2 particles Barrier layer (5) (1.0 g/m.sup.2) 66% low-molecular-weight PVOH, 33% high-molecular- weight PVOH, 1% PEI Lamination layer (6) (2.0 g/m.sup.2) PU adhesive Carrier film (7) 140 μm (129 g/m.sup.2)   40 μm MDPE/LDPE/LLDPE 40 μm MDPE/LDPE/LLDPE 60 μm LDPE/LLDPE/VLDPE Total: 164.5 g/m.sup.2

[0054] The cover film 2 is an oriented polyethylene film composed of a high-density polyethylene (HDPE). As already explained above, the cover film 2 has an imprinting 3, which, however, does not represent a full-area coating of the cover film 2, but rather is arranged only in discrete sections on one side of the cover film 2. The imprinting 3 therefore leads to a certain unevenness of the film 2, which makes it difficult to apply a thin barrier layer 5. The barrier layer 5 is formed on the basis of polyvinyl alcohol (PVOH) and is applied during the course of production, in the form of a liquid solvent. In the hardened state, it has a weight per surface area of only 1 g/m.sup.2. As a result, this barrier layer 5 is not suitable for equalizing the uneven areas due to the imprinting 3 to such an extent that a continuous barrier layer 5 would be formed. Accordingly, the barrier effect would not exist for the entire film packaging 1.

[0055] For this reason, an equalization layer 4 is provided, which evens out the uneven areas caused by the imprinting 3, and makes it possible to apply a continuous barrier layer 5.

[0056] The equalization layer 4 is a layer on the basis of polyurethane (PU), which is applied to the coating 3 and to the cover film 2 during the course of production, in the form of a two-component polyurethane varnish. The equalization layer 4 furthermore has solid particles, which contribute to equalizing the uneven areas, on the one hand, and reduce the amount of polyurethane required, and, on the other hand, also develop a certain barrier effect, since then fat can migrate only through the interstices between the individual solid particles. Even though the presence of the solid particles additionally improves the barrier effect, however, the equalization layers 4 can also be formed solely from a layer on the basis of polyurethane that hardens. Both the equalization layer and the barrier layer are present at a weight per surface area of 1 g/m.sup.2.

[0057] The cover film 2 coated in this manner is then connected with a carrier film 7, which borders on the packaging interior of the film packaging 1, by way of a lamination layer 6 composed of a polyurethane adhesive. The carrier film 7 is a three-layer co-extruded film composed of a polyethylene, wherein the individual layers 7a, 7b, 7c differ from one another both with regard to the polyethylene used and with regard to the layer thickness. In this connection, it should be pointed out that the drawing merely represents a schematic structure, and that the individual layer thicknesses and materials can be found in the table shown above. In particular, the layer 7c, which borders directly on the packaging interior, is formed from a layer having a low sealing temperature, so that the film packaging 1 can be closed in a simple manner, by means of a heat-sealing seam.

[0058] On the basis of the table shown above, it can also be seen that the weight per surface area of the entire film packaging is 163.5 g/m.sup.2. In this regard, both the cover film 2 and the carrier film 7 are formed from a polyethylene (PE) and thereby can be recycled together, in a simple manner. In deviation from this, the imprinting 3, the equalization layer 4, the barrier layer 5, and also the lamination layer 6 represent layers that are formed from a different polymer, wherein the proportion of the different polymers, with reference to the total film composite, lies at approximately 3.6%.

[0059] Depending on the recycling technology used, the PVOH barrier layer 5 can be removed from the film composite, so that the recyclability is further improved.

[0060] In the following table, a comparison example is shown, which uses ethylene vinyl alcohol copolymer (EVOH) as a barrier layer 5 instead of polyvinyl alcohol. Such layers composed of EVOH are usually incorporated in the form of a co-extrusion film, wherein the co-extrusion film is subsequently connected with an imprinted cover film 2 by way of a lamination layer 6. In order to allow co-extrusion of the ethylene vinyl alcohol copolymer layer, adhesion-imparting layers are furthermore provided, by means of which the proportion of other polymers is further increased. In total, this proportion is 11%, according to the example shown, and thereby clearly higher than is the case according to the present invention. In addition, there is the fact that the layer composed of EVOH can be removed from the other layers only with difficulty, due to the co-extrusion. This applies equally also to the adhesion-imparting layers, so that a clear advantage with regard to recyclability results from the use of polyvinyl alcohol according to the present invention.

TABLE-US-00002 Layer thickness (weight per surface Layer area) Composition Cover film (2) 30 μm (28.5 g/m.sup.2) HDPE Imprinting (3) (2.0 g/m.sup.2) Nitrocellulose varnish White background (1.0 g/m.sup.2) Two-component PU varnish + TiO.sub.2 particles Lamination layer (6) (2.0 g/m.sup.2) PU adhesive Carrier film (7) 140 μm (130.5 g/m.sup.2) 60 μm LDPE/LLDPE/MDPE) 5 μm adhesion-imparting agent 5 μm EVOH 5 μm adhesion-imparting agent 65 μm LDPE/LLDPE/VLDPE) Total: 164.0 g/m.sup.2

[0061] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.