RECYCLABLE FILM WITH BARRIER LAYER

Abstract

A multilayer, monoaxially stretched, recyclable film (1) for a laminate (7). The film (1) has outer layers (3) and at least one inner barrier layer (6), with a tie layer (5) arranged between each of these. At least one further, functional intermediate layer (4) is arranged between each of the outer layers (3) and the barrier layer (6).

Claims

1. A multilayer, monoaxially stretched, recyclable film (1) for a laminate (7), the film (1) comprising: outer layers (3) and at least one inner barrier layer (6), and a tie layer (5) being arranged between the outer layers (3) and the at least one inner barrier layer (6); and at least one further functional intermediate layer (4) being arranged between the outer layers (3) and the at least one inner barrier layer (6).

2. The film according to claim 1, wherein the outer layers (3) have a density which is a factor higher than the at least one functional intermediate layer, the value of the factor being more than 1.002and less than 1.20.

3. The film according to claim 1, wherein a density of the outer layers (3) has a value of more than 0.941 g/cm.sup.3.

4. The film according to claim 1, wherein a density of the at least one functional intermediate layer (4) has a value of more than 0.91 g/cm.sup.3 and of less than 0.940 g/cm.sup.3.

5. The film according to claim 1, wherein the at least one functional intermediate layer (4) comprise a bimodal polyethylene, wherein the bimodal polyethylene is a terpolymer, and further wherein the terpolymer is a bimodal ethylene/1-butene/C6-C12-alpha-olefin terpolymer.

6. The film according to claim 1, wherein a density of the the layer (5) has a value of less than 0.915 g/cm.sup.3.

7. The film according to claim 1, wherein the barrier layer (6) is formed as an ethylene-vinyl alcohol copolymer layer.

8. The film according to claim 1, wherein the tie layer (5) comprises a maleic anhydride modified polyethylene and a polyethylene, wherein a density of the tie layer (5) is more than 0.880g/cm.sup.3, preferably more than 0.900 g/cm.sup.3 and is less than 0.940 g/cm.sup.3 and has a melt flow rate (at 190 C. at 2.16 kg) according to ASTM D 1238 that is more than 0.1 g/10 min and is less than 5.0 g/10 min.

9. The film according to claim 1, wherein a melt flow rate (at 190 C. at 2.16 kg) according to ASTM D 1238 of the tie layer (5) is similar to a melt flow rate of the functional intermediate layer (4), wherein the melt flow rates of the tie layer (5) and the functional intermediate layer (4) differ by a factor of less than 1.5.

10. The film according to claim 1, wherein the film (1) has a gloss according to DIN EN ISO 2813 of less than 7%.

11. The film according to claim 1, wherein the film (1) has an oxygen transmission rate of less than 10 cm.sup.3/m.sup.3-day-bar, measured at 23 C. and 0% rH.

12. The film according to claim 1, wherein the film (1) has a water vapour transmission rate of less than 50 g/m.sup.2 in 24 h according to ASTM D6701-01.

13. The film according to claim 1, wherein the film (1) is stretched monoaxially in a machine direction by more than a factor of 2.0 and is stretched in the machine direction by less than a factor of 7.0.

14. The film according to claim 1, wherein an imprint (2) is arranged directly on an outermost one of the outer layers (3) of the film (1).

15. The film according to claim 1, wherein the film (1) has a thickness of less than 60 m, and more than 5 m.

16. The film according to claim 1, wherein a density of the film (1) is less than 0.99 g/cm.sup.3, and iis more than 0.60 g/cm.sup.3.

17. The film according to claim 1, wherein the multilayer structure of the film (1) is symmetrical.

18. The film according to claim 1, wherein the film (1) has at least one additional, outer layer (9) which is formed from an ethylene-vinyl alcohol copolymer layer (EVOH) or from polyamide (PA).

19. The film according to claim 1, further comprising at least one further outer layer for producing a mattness which has no fillers, the film (1) thereby having a haze value according to ASTM D1003 of more than 65%.

20. The film according to claim 1, wherein at least one outer layer (3) has a proportion of polypropylene, the proportion being more than 5% by weight and less than 50% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Further advantages and features of the invention are apparent from the description of an embodiment example with reference to drawings and from the drawings themselves. It shows

[0075] FIG. 1 shows a schematic structure of the laminate according to

[0076] the invention,

[0077] FIG. 2 a schematic structure of the laminate with an imprint in reverse printing design.

DETAILED DESCRIPTION

[0078] FIG. 1 shows a schematic structure of the laminate 7, which is formed from the film 1 and the layer 8. An imprint 2 is arranged directly on an outer layer 3 of the film 1. The imprint 2 is used to label the item to be packaged and for visual recognition as well as to support the brand image of the item brand.

[0079] In this embodiment, the film 1 is designed with nine layers in a symmetrical structure. The innermost layer is designed as a barrier layer 6 and consists of an ethylene-vinyl alcohol copolymer. The properties of the inner barrier layer 6 realise a film 1 with an oxygen transmission rate of less than 2 cm.sup.3/m.sup.3-day-bar, measured at 23 C. and 0% rH. In addition, the film 1 is virtually impermeable to water vapour due to the inner barrier layer 6 with a water vapour transmission rate of less than 5 g/m.sup.2 in 24 h according to ASTM D6701-01. The thickness of the barrier layer 6 in this embodiment is approx. 14 m before stretching.

[0080] The barrier layer 6 is surrounded by a tie layer 5 consisting of an LLDPE with a density of 0.910 g/cm.sup.3 and a melt flow rate (at 190 C. at 2.16 kg) of 2.5 g/10min according to ASTM D 1238. In this embodiment, the tie layer 5 is formed with a polyethylene grafted with maleic anhydride in order to realise an adhesion between the other polyethylene-based layers and the EVOH-based barrier layer 6. In this embodiment, the thickness of the tie layer 5 is approx. 8.5 m before stretching.

[0081] Two functional intermediate layers 4 are arranged between the outer layers 3 and the tie layers 5, which realise the toughness despite the enormous stiffness of the film 1. The intermediate layers 4 consist entirely of a polyethylene whose density is 0.937 g/cm.sup.3 and whose melt flow rate (at 190 C. at 5 kg) is 2 g/10min according to ISO 1133. In this embodiment, the thickness of a functional intermediate layer 4 is approx. 14 m before stretching.

[0082] The two outer layers 3 of the film 1 consist of an HDPE in addition to a proportion of additives. In the embodiment shown, the proportion of HDPE is 98% by weight and its density is 0.946 g/cm.sup.3 and its melt flow rate (at 190 C. at 5 kg) is 1.6g/10 min in accordance with ISO 1133.

[0083] In this embodiment, the layer thickness of the outer layers 3 before stretching is 15-17 m, whereby the outer layer 3, which is arranged towards the imprint 2, is slightly thicker.

[0084] The nine-layer film 1 has a thickness of 120.5 m after blow extrusion. After monoaxial stretching by a factor of 4.82, the thickness is 25 m, with a density of 0.95 g/cm.sup.3. Layer 8 is formed from an LDPE.

[0085] FIG. 2 shows a further schematic structure of the laminate 7, which is formed from the film 1 and the layer 8. The film 1 and the layer 8 correspond to the illustration and description of FIG. 1. The print 2 is arranged directly on an outer layer 3 between the film 1 and the layer 8 and is applied using a reverse printing process.

[0086] In the embodiment shown in FIG. 2, the higher density polyethylene of the outer layers 3 and the outer intermediate layers 4 is designed as an HDPE whose density is 0.962 g/cm.sup.3 and whose melt flow rate (at 190 C. at 2.16 kg) is 0.85 g/10min according to ASTM 1238.

[0087] In addition, the film 1 has an optional outer layer 9, which is made of an ethylene-vinyl alcohol copolymer layer (EVOH). The imprint 2 adheres better to the additional outer layer 9 due to the higher polarity. In the embodiment shown, the thickness of the outer layer 9 after stretching is 4 m and is formed from a SoarnoLT from Mitsubishi Chemicals.