Multilayer composite material and method

Abstract

The invention relates to a multilayer composite material comprising the following layers: a base layer (1) comprising or consisting of paper; an intermediate layer (2) comprising or consisting of a thermoplastic polymer; and a barrier layer (3), the barrier layer (3) comprising or consisting of an oriented, in particular biaxially oriented, polymer film (4) and a metallic and / or ceramic thin layer (5) arranged on one or both sides of the oriented polymer film (4). The invention also relates to a method for producing a multilayer composite material.

Description

[0001] 65028 / MB / -

[0002] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0003] Multilayer composite material and process

[0004] The present invention relates to a multilayer composite material and a method as defined in particular by the features of the independent claims.

[0005] Multilayer composite materials are used, among other things, as packaging materials, according to the state of the art. A widespread example, particularly in the food and consumer goods industries, is a laminate typically composed of layers of paper, polyethylene, and aluminum. An exemplary layer structure known from the state of the art is paper / / PE / / aluminum / / PE. In such multilayer systems, aluminum foils with thicknesses in the range of a few millimeters are used, according to the state of the art. This structure offers excellent barrier properties against moisture, light, and oxygen, making it ideal for sensitive products.

[0006] The paper layer primarily serves as a support layer and provides the necessary mechanical stability. The first polyethylene (PE) layer bonds the paper to the aluminum layer. The aluminum layer provides the actual barrier properties and protects the packaged product from external influences such as light, oxygen, and moisture. The second polyethylene (PE) layer forms the outer layer of the system and, in particular, ensures the sealability of the multilayer composite material. 65028 / MB / -

[0007] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0008] Although such laminate structures exhibit excellent barrier properties, they usually present significant disadvantages with regard to recyclability. Separating plastic / metal and paper in the recycling process is very complex and often only feasible to a limited extent in industrial recycling processes. As a result, such packaging cannot usually be recycled in paper waste streams and is instead incinerated or landfilled, which represents a significant environmental burden and reduces the value of the waste streams.

[0009] Given the increasing global efforts to minimize the environmental impact of packaging materials and increase recycling rates, there is an urgent need for alternatives to these conventional, non-recyclable packaging materials.

[0010] This results in a conflict of objectives, which consists in particular of providing a packaging material that has good and consistent barrier properties and whose paper component is recyclable to an improved degree.

[0011] The present invention aims to at least partially resolve this conflict of objectives. In particular, the invention is intended to provide a multilayer composite material that can be used for packaging purposes and exhibits advantageous barrier properties combined with good recyclability.

[0012] It has now been surprisingly found that these and other tasks can be solved in particular by providing a multilayer composite material that has a barrier layer combining an oriented polymer material with a thin film.

[0013] In particular, the multilayer composite material described here has a base layer made of paper, an intermediate layer and a barrier layer, the barrier layer being in turn composed of at least two sublayers, namely 65028 / MB / -

[0014] Mondi AG, Marxergasse 4A, 1030 Vienna (AT) a oriented polymer film and a metallic and / or ceramic thin film. The intermediate layer comprises or consists of a thermoplastic polymer. Optionally, a sealing layer can be applied to the barrier layer.

[0015] The multilayer composite material can therefore have at least four sublayers or consist of four sublayers, or it can have at least five sublayers or consist of five sublayers. Optionally, the base layer and the oriented polymer film of the barrier layer form outer layers of the material, or optionally, the base layer and the sealing layer form outer layers of the material.

[0016] In particular, the barrier layer is extruded onto the base layer. Generally, the term "lamination" refers to a process in which two layers or webs of a material are bonded together via another layer of material, also known as a laminating agent. In the present case, this additional layer of material is formed by the intermediate layer, which, during the lamination process, creates the bond between the base layer and the barrier layer.

[0017] Lamination can be carried out by extrusion lamination, whereby a thermoplastic polymer material is extruded onto one of the two surfaces to be joined as a laminating agent, and the second surface is then applied to the laminating agent while it is still in a flowable state.

[0018] In the lamination process, one of the surfaces is typically provided by the base layer and the other by the barrier layer. The laminating agent typically forms the intermediate layer in the manufactured composite material.

[0019] If the barrier layer forms an outer layer of the multilayer composite material, it may be intended that the thin layer is in direct contact with the intermediate layer.

[0020] As already mentioned, the barrier layer comprises at least two sublayers: a polymer film and a thin film. 65028 / MB / -

[0021] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0022] The polymer film is, in particular, an oriented polymer film. The term "oriented polymer film" refers to a polymer film that is stretched in at least one direction. The polymer film used in the barrier layer can be stretched longitudinally or transversely (also referred to as monoaxially oriented or monoaxially stretched). However, it is preferred if the polymer film can be stretched in both the longitudinal and transverse directions (also referred to as biaxially oriented or biaxially stretched). Optionally, the polymer film is a biaxially oriented polypropylene film (BOPP film). Other exemplary polymers for the polymer film are: polyethylene terephthalate, polyethylene, polyamide, and polylactides.

[0023] The barrier layer consists of a polymer film, in particular a thin layer. This layer can be made of or comprise a metallic and / or ceramic material. Suitable materials include, among others: aluminum;

[0024] Silicon oxide; aluminum oxide; magnesium oxide.

[0025] In the context of the composite materials described here, or the materials of the barrier layer, a thin film refers in particular to a layer having a thickness of less than 1 pm, such as less than 500 nm, less than 200 nm, or less than 100 nm. Manufacturing processes for such thin films are known in the prior art, including, in particular, various vapor deposition processes.

[0026] Advantageously, the barrier layer, i.e. the composite consisting at least of the thin film and the oriented polymer film, is provided as an intermediate product in the production of the multilayer composite material described here, which is then laminated onto the base layer using the intermediate layer.

[0027] A sealing layer, typically comprising or consisting of a thermoplastic polymer, can optionally be applied to the barrier layer. The term "thermoplastic polymer" also includes thermoplastic oligomers, provided they are suitable for use as a sealing layer. 65028 / MB / -

[0028] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0029] If an additional sealing layer is provided, both the thin film and the oriented polymer film can be in direct contact with the intermediate layer.

[0030] Examples of materials suitable for the sealing layer include polyolefins. These can be homo- and / or copolymers, and mixtures of different polymers are also conceivable.

[0031] The material of the sealing layer can be the same as that of the intermediate layer, or the materials of these layers can differ from each other.

[0032] In order to ensure sufficient recyclability of the base layer material, it is preferred if all layers except the base layer, in particular the intermediate layer, the thin film, the barrier dispersion layer and the sealing layer, have the lowest possible layer thickness or the lowest possible basis weight.

[0033] The following basis weights or layer thicknesses of the individual layers can be specified: Intermediate layer - 2 g / m² 2 up to 8 g / m² 2 Barrier layer - maximum 20 pm; optional sealing layer - 3 g / m² 2 up to 10 g / m² 2. In general, the basis weights given here can be determined according to ISO 536:2019.

[0034] The mass-related paper content of the multilayer composite material described here is, if applicable, at least 80 wt.%.

[0035] Advantageously, the multi-layer composite material described here is recyclable according to the “Cepi Recyclability Laboratory Test Method”, version 2, October 2022 (full title: “Harmonised European laboratory test method to generate parameters enabling the assessment of the recyclability of paper and board products in standard paper and board recycling mills”).

[0036] The invention may relate to a multilayer composite material comprising the following layers: 65028 / MB / -

[0037] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0038] - a base layer comprising or consisting of paper,

[0039] - an intermediate layer comprising or consisting of a thermoplastic polymer, and

[0040] - a barrier layer,

[0041] Preferably, the barrier layer comprises or consists of an oriented, in particular a biaxially oriented, polymer film and a metallic and / or ceramic thin film arranged on one or both sides of the oriented polymer film.

[0042] If necessary, the intermediate layer is provided to be in direct contact with the base layer and with the thin layer of the barrier layer.

[0043] If necessary, it is provided that at least the base layer forms an outer layer of the multi-layer composite material.

[0044] Optionally, a sealing layer may be arranged on the barrier layer, which comprises or consists of at least one thermoplastic polymer.

[0045] If applicable, the multilayer composite material is provided to have a layer structure in the following order: base layer; intermediate layer; barrier layer, wherein the base layer and the oriented polymer film of the barrier layer form, in particular, outer layers of the multilayer composite material.

[0046] Optionally, the multilayer composite material may have a layer structure in the following order: base layer; intermediate layer; barrier layer; sealing layer, wherein the sealing layer is arranged on the oriented polymer film or on the thin film of the barrier layer, and wherein the base layer and the sealing layer in particular form outer layers of the multilayer composite material. 65028 / MB / -

[0047] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0048] If applicable, the multilayer composite material is designed to have a paper content of at least 80% by weight, based on the total mass of the multilayer composite material.

[0049] Optionally, the thin film of the barrier layer may have a thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm.

[0050] If applicable, the material of the thin barrier layer is selected from: aluminum; silicon dioxide; aluminum oxide; magnesium oxide.

[0051] If necessary, the barrier layer is provided for to have a thickness of no more than 20 pm, in particular between 2 pm and 15 pm.

[0052] If necessary, the base layer is to be made of paper with a basis weight between 40 g / m². 2 and 130 g / m² 2 is determined in accordance with ISO 536:2019.

[0053] If necessary, the intermediate layer is provided for to be a layer produced by lamination, in particular extrusion lamination.

[0054] If necessary, the base layer and the barrier layer are connected via the intermediate layer by lamination, in particular extrusion lamination.

[0055] If necessary, the intermediate layer is designed to have a basis weight between 2 g / m². 2 and 8 g / m² 2 , especially between 3 g / m² 2 and 6 g / m² 2 , exhibits.

[0056] If applicable, the polymer film of the barrier layer is provided for to comprise or consist of one or more of the following polymers: polyethylene terephthalate, polypropylene, polyethylene, polyamide, polylactide. 65028 / MB / -

[0057] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0058] If applicable, the multi-layer composite material is designed to have the following layer structure:

[0059] - a base layer of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019,

[0060] - an intermediate layer at the base layer with a basis weight between 3 g / m² 2 and 6 g / m² 2 ,

[0061] - a barrier layer, in particular extrusion-laminated, with a thickness between 4 pm and 15 pm, laminated to the base layer by means of the intermediate layer, consisting of an oriented polymer film comprising or consisting of a thermoplastic polymer and a metallic or ceramic thin film arranged thereon, wherein in particular the thin film is in direct contact with the intermediate layer.

[0062] If applicable, the multi-layer composite material is designed to have the following layer structure:

[0063] - a base layer of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019,

[0064] - an intermediate layer arranged at the base layer with a basis weight between 3 g / m² 2 and 6 g / m² 2 ,

[0065] - a barrier layer, in particular extrusion-laminated, with a thickness between 2 pm and 9 pm, laminated to the base layer by means of the intermediate layer, consisting of an oriented polymer film comprising or consisting of a thermoplastic polymer and a metallic or ceramic thin film arranged thereon,

[0066] - an extrusion-coated sealing layer arranged on the thin film or on the oriented polymer film of the barrier layer with a basis weight between 3 g / m² 2 and 10 g / m² 2 .

[0067] The invention may also relate to a method for producing a multilayer composite material described herein. 65028 / MB / -

[0068] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0069] The process may include the following steps:

[0070] - Provision of the base layer and the barrier layer,

[0071] - Extrusion lamination of the barrier layer onto the base layer using a thermoplastic polymer, so that the intermediate layer is formed between the base layer and the barrier layer.

[0072] The procedure may also include the following step:

[0073] - Extruding a polymer material onto the barrier layer to form a sealing layer, which is an outer layer of the multilayer composite material.

[0074] Further features can be found in the patent claims, the description of the exemplary embodiments and the figure.

[0075] The following section provides a detailed explanation of exemplary multilayer composite materials using embodiments. These embodiments are intended solely for illustrative purposes and do not limit the scope of protection defined by the patent claims.

[0076] They show:

[0077] Fig. 1 shows an exemplary representation of a first embodiment of the multilayer composite material in a sectional view; and

[0078] Fig. 2 shows an exemplary representation of a second embodiment of the multilayer composite material in a sectional view.

[0079] Fig. 1 shows an exemplary cross-sectional view of a first embodiment of the multilayer composite material. The different sublayers are shown, although it should be noted that the layer thicknesses are not to scale.

[0080] The multilayer composite material shown in Fig. 1 has four layers and the layer sequence specified in Table 1. 65028 / MB / -

[0081] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0082] Table 1: Layers of the multilayer composite material shown in Fig. 1

[0083] *biaxially oriented polypropylene

[0084] In the production of the composite material according to this embodiment, the barrier layer 3 is extruded onto the base layer 1 using the polyethylene of the intermediate layer. The thin film is in direct contact with the intermediate layer 2, so that the oriented polymer film 4 forms an outer layer of the composite material.

[0085] Barrier layer 3 is produced according to methods known in the prior art.

[0086] Fig. 2 shows an exemplary cross-sectional view of a second embodiment of the multilayer composite material. The different sublayers are shown, although it should be noted that the representation of the layer thicknesses is not to scale.

[0087] The multilayer composite material shown in Fig. 2 has five layers and the layer sequence specified in Table 2. 65028 / MB / -

[0088] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0089] Table 2: Layers of the multilayer composite material shown in Fig. 2

[0090] *biaxially oriented polypropylene

[0091] The composition and manufacturing process largely correspond to that of the first embodiment, with the difference that after the lamination of the barrier layer 3, a sealing layer 6 is extruded onto the barrier layer 3. This increases the sealing capacity of the material.

[0092] The typical water vapor permeability of the multilayer composite material according to this second embodiment is approximately 0.2 g / m². 2 .d at 23°C and 85% rh. The typical oxygen permeability is approximately 130 cm. 3 / m 2 .d.bar at 23°C and 50% rH

[0093] In another embodiment, not described in detail, the thin film 5 and the oriented polymer film 4 are reversed in their sequence, i.e., the oriented polymer film 4 is in direct contact with the intermediate layer 2. All other compositions and layer thicknesses are identical compared to the first embodiment described here.

Claims

65028 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) Patent claims 1. Multilayer composite material with the following layers: - a base layer (1) comprising or consisting of paper, - an intermediate layer (2) comprising or consisting of a thermoplastic polymer, and - a barrier layer (3), characterized in that the barrier layer (3) comprises or consists of an oriented, in particular a biaxially oriented, polymer film (4) and a metallic and / or ceramic thin film (5) arranged on one or both sides of the oriented polymer film (4).

2. Multilayer composite material according to claim 1, characterized in that the intermediate layer (2) is in direct contact with the base layer (1) and with the thin layer (5) of the barrier layer (3), - and / or wherein at least the base layer (1 ) forms an outer layer of the multilayer composite material.

3. Multilayer composite material according to claim 1 or 2, characterized in that a sealing layer (6) is further arranged on the barrier layer (3), which comprises or consists of at least one thermoplastic polymer.

4. Multilayer composite material according to one of claims 1 to 3, characterized in that, - that the multilayer composite material has a layer structure in the following order: base layer (1); intermediate layer (2); barrier layer (3), wherein the base layer (1) and the oriented polymer film (4) of the barrier layer (3) form, in particular, outer layers of the multilayer composite material, - or that the multilayer composite material has a layer structure in the following order: base layer (1); intermediate layer (2); barrier layer (3); sealing layer (6), wherein the sealing layer is arranged on the oriented polymer film (4) or on the thin film (5) of the barrier layer (3), and wherein 65028 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) the base layer (1 ) and the sealing layer (6) form, in particular, outer layers of the multilayer composite material.

5. Multilayer composite material according to one of claims 1 to 4, characterized in that the multilayer composite material has a paper content of at least 80 wt.%, based on the total mass of the multilayer composite material.

6. Multilayer composite material according to one of claims 1 to 5, characterized in that the thin film (5) of the barrier layer (3) has a layer thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm, and / or that the material of the thin film (5) of the barrier layer (3) is selected from: aluminum; silicon oxide; aluminum oxide; magnesium oxide.

7. Multilayer composite material according to one of claims 1 to 6, characterized in that the barrier layer (3) has a thickness of at most 20 pm, in particular between 2 pm and 15 pm.

8. Multilayer composite material according to one of claims 1 to 7, characterized in that the base layer (1 ) is made of paper with a basis weight between 40 g / m² 2 and 130 g / m² 2 is determined in accordance with ISO 536:2019.

9. Multilayer composite material according to one of claims 1 to 8, characterized in that the intermediate layer (2) is a layer produced by lamination, in particular extrusion lamination, and / or that the base layer (1 ) and the barrier layer (3) are connected via the intermediate layer (2) by lamination, in particular extrusion lamination.

10. Multilayer composite material according to one of claims 1 to 9, characterized in that the intermediate layer (2) has a basis weight between 2 g / m² 2 and 8 g / m² 2 , especially between 3 g / m² 2 and 6 g / m² 2 , exhibits. 65028 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 11. Multilayer composite material according to one of claims 1 to 10, characterized in that the polymer film (4) of the barrier layer (3) comprises or consists of one or more of the following polymers: polyethylene terephthalate, polypropylene, polyethylene, polyamide, polylactide.

12. Multilayer composite material according to one of claims 1 to 11, characterized in that the multilayer composite material has the following layer structure: - a base layer (1 ) of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019, - an intermediate layer (2) arranged on the base layer (1) with a basis weight between 3 g / m² 2 and 6 g / m² 2 , - a barrier layer (3) laminated to the base layer (1) by means of the intermediate layer (2), in particular extrusion-laminated, with a thickness between 4 pm and 15 pm, consisting of an oriented polymer film (4) comprising or consisting of a thermoplastic polymer and a metallic or ceramic thin film (5) arranged thereon, wherein in particular the thin film (5) is in direct contact with the intermediate layer (2).

13. Multilayer composite material according to one of claims 1 to 11, characterized in that the multilayer composite material has the following layer structure: - a base layer (1 ) of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019, - an intermediate layer (2) arranged on the base layer (1) with a basis weight between 3 g / m² 2 and 6 g / m² 2 , - a barrier layer (3) laminated to the base layer (1) by means of the intermediate layer (2), in particular extrusion-laminated, with a thickness between 2 pm and 9 pm, consisting of an oriented polymer film (4) comprising or consisting of a thermoplastic polymer and a metallic or ceramic thin film (5) arranged thereon, 65028 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) a thin film (5) or polymer film (4) oriented to the Barrier layer (3) arranged extrusion-coated sealing layer (6) with a basis weight between 3 g / m² 2 and 10 g / m² 2 14. Method for producing a multilayer composite material according to any one of claims 1 to 13, comprising the following steps: - Provision of the base layer (1) and the barrier layer (3), - Laminating, in particular extrusion lamination, of the barrier layer (3) onto the base layer (1) using a thermoplastic polymer, so that the intermediate layer (2) is formed between the base layer (1) and the barrier layer (3).

15. The method of claim 14, characterized in that the method further comprises the following step: - Extruding a polymer material onto the barrier layer (3) to form a sealing layer (6) which is an outer layer of the multilayer composite material.

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