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; a barrier dispersion layer (3); a metallic and / or ceramic thin layer (4); and a sealing layer (5) comprising or consisting of a thermoplastic polymer. The invention also relates to a method for producing such a multilayer composite material.

Description

[0001] 65030 / 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 a 65030 / MB / -

[0007] Mondi AG, Marxergasse 4A, 1030 Vienna (AT) outer closure of the layer system and ensures in particular the sealing capability of the multi-layer composite material.

[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] In view of the aforementioned disadvantages, alternative materials and coatings have been developed that are intended to provide the necessary barrier properties and improve recyclability.

[0011] Multilayer composite materials are known that, instead of conventional aluminum foil, feature a thin metallic film in combination with two dispersion layers. Paper can again be used as the substrate. One such layer structure known from the prior art is: paper / / dispersion layer / / thin aluminum film / / dispersion layer.

[0012] The dispersion layers typically consist of compositions that are applied to the paper as an aqueous dispersion and then subjected to a drying and polymerization process. Compared to the systems described above, such layer systems exhibit improved recyclability; however, there is a risk of introducing some of the metal from the thin film into the paper recycling stream, thereby contaminating it with metallic particles. 65030 / MB / -

[0013] Mondi AG, Marxergasse 4A, 1030 Vienna (AT) contaminate. A further disadvantage is the lower mechanical strength of such materials. Under particularly high stress during intended use as packaging, the barrier properties may be impaired.

[0014] The aforementioned problems of the state of the art result in a conflict of objectives, which consists in particular in providing a packaging material that has good and consistent barrier properties and whose paper component is recyclable to an improved degree.

[0015] 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.

[0016] It has now been surprisingly found that these and other tasks can be solved in particular by providing a multi-layer composite material that combines a barrier dispersion layer and a thin film with thermoplastic layers.

[0017] In particular, the multilayer composite material described here comprises a paper base layer, a thermoplastic intermediate layer, a barrier dispersion layer, a metallic and / or ceramic thin film, and a thermoplastic sealing layer. The intermediate layer and the sealing layer are advantageously extruded layers.

[0018] The multilayer composite material can have at least four sublayers or consist of five sublayers. Optionally, the base layer and the sealing layer form the outer layers of the material.

[0019] It was found that the roughness of the sublayers significantly improves the properties of the multilayer composite material. 65030 / MB / -

[0020] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0021] Therefore, the base layer is smooth, particularly on at least one of its two sides. This smooth side advantageously forms the surface of the base layer on which the intermediate layer is arranged. The PPS roughness of the base layer on this side, according to ISO 8791-4, is particularly not more than 7 pm.

[0022] The intermediate layer applied to this smooth surface can be an extrusion-coated layer, with polyolefins being exemplary materials. These can be homo- and / or copolymers, and mixtures of different polymers are also conceivable.

[0023] It is advantageous to smooth the intermediate layer after the polymer material has been applied to the base layer. This can be achieved, in particular, by using a cooled smoothing roller. This results in a particularly smooth surface onto which a further layer of the multilayer composite material is subsequently applied.

[0024] This additional layer, applied to the intermediate layer, can be the barrier dispersion layer. It can be applied as a dispersion mixture. It is assumed that the exceptional smoothness of the resulting surface facilitates the homogeneous application of the dispersion mixture.

[0025] The barrier dispersion layer can be produced in a known manner and can comprise or consist of barrier materials known in the prior art. Typical barrier materials that may be included in the barrier dispersion layer are: PVOH; EVOH; acrylates; methacrylates; polyvinyl acetate;

[0026] Polyelectrolytes; clay minerals; graphene.

[0027] The thin film, which can be made of or comprise a metallic and / or ceramic material, can then be applied to the barrier dispersion layer. Suitable materials include, among others: aluminum; silicon dioxide;

[0028] aluminum oxide; Magnesium oxide. 65030 / MB / -

[0029] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0030] In the context of the composite materials described here, 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.

[0031] As an alternative to applying the barrier dispersion layer to the intermediate layer, it is possible to apply the thin film to the intermediate layer and then apply the barrier dispersion layer to the thin film.

[0032] Subsequently, a sealing layer can be applied to the barrier dispersion layer or thin film. This can be an extrusion-coated layer, with polyolefins being an example of suitable materials. These can be homo- and / or copolymers, and mixtures of different polymers are also conceivable.

[0033] 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.

[0034] 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.

[0035] The following basis weights can be specified: Intermediate layer - 3 g / m² 2 up to 10 g / m² 2 ; Barrier dispersion layer - 0.5 g / m² 2 up to 3 g / m² 2 ; 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.

[0036] The paper content by weight of the multilayer composite material described here is, if applicable, at least 80% by weight. 65030 / MB / -

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

[0038] 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”).

[0039] The invention may relate to a multilayer composite material comprising the following layers:

[0040] - a base layer comprising or consisting of paper,

[0041] - an intermediate layer comprising or consisting of a thermoplastic polymer,

[0042] - a barrier dispersion layer,

[0043] - a metallic and / or ceramic thin film and

[0044] - comprising or consisting of a sealing layer made of a thermoplastic polymer.

[0045] If necessary, the paper, particularly on the side in contact with the interlayer, is required to have a PPS roughness according to ISO 8791-4 of no more than 7 pm.

[0046] If applicable, it is provided, characterized in that the base layer 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.

[0047] If applicable, it is provided that the intermediate layer and / or the sealing layer are extruded layers.

[0048] If applicable, the barrier dispersion layer is provided to be formed from or comprise one or more of the following materials: PVOH; EVOH; Acrylates; Methacrylates; Polyvinyl acetate; Polyelectrolytes; Clay minerals; Graphene.

[0049] Optionally, the thin film may have a thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm. 65030 / MB / -

[0050] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0051] If applicable, the material of the thin film is selected from: aluminum; silicon oxide; aluminum oxide; magnesium oxide.

[0052] If applicable, the intermediate layer and / or the sealing layer is designed to have a basis weight of no more than 15 g / m². 2 , especially between 3 g / m² 2 and 10 g / m² 2 , exhibits.

[0053] If necessary, the barrier dispersion layer is designed to have a basis weight between 0.5 g / m². 2 and 3 g / m² 2 , based on the dry mass of the barrier dispersion layer material.

[0054] If necessary, the multi-layer composite material is designed to have a layer structure in the following order: base layer; intermediate layer; barrier dispersion layer; thin layer; sealing layer.

[0055] If necessary, the multi-layer composite material is designed to have a layer structure in the following order: base layer; intermediate layer; thin layer; barrier dispersion layer; sealing layer.

[0056] If necessary, the base layer and the sealing layer are intended to form outer layers of the multi-layer composite material.

[0057] If applicable, the intermediate layer and / or the sealing layer is provided for to be made of or comprise a thermoplastic polymer material.

[0058] 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.

[0059] If applicable, the multilayer composite material is intended to have the following layer structure, in particular in the order mentioned: 65030 / MB / -

[0060] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0061] - a base layer of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019,

[0062] - an extrusion-coated intermediate layer arranged on the base layer with a basis weight between 3 g / m² 2 and 10 g / m² 2 ,

[0063] - a barrier dispersion layer arranged at the intermediate layer with a basis weight between 0.5 g / m² 2 and 3 g / m² 2 based on the dry mass of the barrier dispersion layer material,

[0064] - a metallic and / or ceramic thin film arranged on the barrier dispersion layer, and

[0065] - an extrusion-coated sealing layer arranged on the thin film with a basis weight between 3 g / m² 2 and 10 g / m² 2 ,

[0066] If applicable, the multilayer composite material is intended to have the following layer structure, in particular in the order mentioned:

[0067] - a base layer of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019,

[0068] - an extrusion-coated intermediate layer arranged on the base layer with a basis weight between 3 g / m² 2 and 10 g / m² 2 ,

[0069] - a metallic and / or ceramic thin film arranged at the intermediate layer

[0070] - a barrier dispersion layer arranged on the thin film with a basis weight between 0.5 g / m² 2 and 3 g / m² 2 based on the dry mass of the barrier dispersion layer material,

[0071] - an extrusion-coated sealing layer arranged on the barrier dispersion layer with a basis weight between 3 g / m² 2 and 10 g / m² 2 .

[0072] The invention may also relate to a method for producing a multilayer composite material described herein, comprising the following steps:

[0073] - Providing the base layer,

[0074] - Extrusion of a thermoplastic polymer onto the base layer and smoothing of the extruded thermoplastic polymer using a cooled smoothing roller to form the intermediate layer,

[0075] - Dispersion coating of the intermediate layer with a barrier dispersion to form the barrier dispersion layer, 65030 / MB / -

[0076] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0077] - Coating the barrier dispersion layer with the metallic and / or ceramic thin film, and

[0078] - Extruding a thermoplastic polymer onto the thin film to form the sealing layer.

[0079] The procedure may include the following steps:

[0080] - Providing the base layer,

[0081] - Extrusion of a thermoplastic polymer onto the base layer and smoothing of the extruded thermoplastic polymer using a cooled smooth roller to form the intermediate layer,

[0082] - Coating the intermediate layer with the metallic and / or ceramic thin film,

[0083] - Dispersion coating of the thin film with a barrier dispersion to form the barrier dispersion layer, and

[0084] - Extruding a thermoplastic polymer onto the barrier dispersion layer to form the sealing layer.

[0085] If necessary, the smooth roller is designed to have a surface temperature of 15°C to 30°C.

[0086] If necessary, the surface of the smoothing roller is provided to have one or more of the following roughness parameters: mean roughness Ra not more than 0.05 pm;

[0087] Surface roughness depth Rz at most 0.3 pm, maximum surface roughness depth Rmax at most 0.5 pm.

[0088] Further features can be found in the patent claims, the description of the exemplary embodiments and the figure.

[0089] 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.

[0090] Figure 1 shows an exemplary cross-sectional view of a first embodiment of the multilayer composite material. The 65030 / MB / - are shown.

[0091] Mondi AG, Marxergasse 4A, 1030 Vienna (AT) different sub-layers, it should be noted that the representation of the layer thicknesses is not to scale.

[0092] The multilayer composite material shown in Fig. 1 has five layers and the layer sequence shown in Table 1.

[0093] Table 1: Layers of the multilayer composite material shown in Fig. 1

[0094] The typical water vapor permeability of the multilayer composite material according to this embodiment is approximately 0.55 g / m². 2 .d at 23°C and 85% rh. The typical oxygen permeability is approximately 0.45 cm. 3 / m 2 .d.bar at 23°C and 50% rH

[0095] The kraft paper of base layer 1 is particularly smooth on one side. It has a PPS roughness according to ISO 8791-4 of approximately 3.3 pm.

[0096] In the production of the composite material according to this embodiment, the smooth side of the kraft paper is extruded with polyethylene. Subsequently, it is smoothed with a smoothing roller that has a surface temperature of approximately 20°C and the following roughness parameters: average roughness Ra approximately 0.02 pm; roughness depth Rz approximately 0.1 pm; maximum roughness depth Rmax approximately 0.4 pm. This provides a smooth surface for the subsequent coating steps.

[0097] An aqueous dispersion is then applied to the surface of the intermediate layer 2, the water it contains is removed, and polymerization is carried out to form the barrier dispersion layer 3. 65030 / MB / -

[0098] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0099] Then the thin film 4 is applied to the surface of the barrier dispersion layer 3 by vapor deposition.

[0100] Finally, the surface of the thin film 4 is extruded with polyethylene to form the sealing layer.

[0101] In another embodiment, not described in detail here, the barrier dispersion layer 3 and the thin film 4 are reversed in their sequence. All other compositions and layer thicknesses are identical compared to the first embodiment described here.

Claims

65030 / 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, - a barrier dispersion layer (3), - a metallic and / or ceramic thin film (4) and - comprising or consisting of a sealing layer (5) made of a thermoplastic polymer.

2. Multilayer composite material according to claim 1, characterized in that the paper, in particular on the side in contact with the intermediate layer (2), has a PPS roughness according to ISO 8791-4 of at most 7 pm.

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

4. Multilayer composite material according to one of claims 1 to 3, characterized in that the intermediate layer (2) and / or the sealing layer (5) are extruded layers.

5. Multilayer composite material according to one of claims 1 to 4, characterized in that the barrier dispersion layer (3) is formed from or comprises one or more of the following materials: PVOH; EVOH; Acrylates; Methacrylates; Polyvinyl acetate; Polyelectrolytes; Clay minerals; Graphene.

6. Multilayer composite material according to one of claims 1 to 5, characterized in that the thin film (4) has a layer thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm, 65030 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) and / or that the material of the thin film (4) 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 intermediate layer (2) and / or the sealing layer (5) has a basis weight of at most 15 g / m². 2 , especially between 3 g / m² 2 and 10 g / m² 2 , exhibits.

8. Multilayer composite material according to one of claims 1 to 7, characterized in that the barrier dispersion layer (3) has an areal weight between 0.5 g / m² 2 and 3 g / m² 2 , based on the dry mass of the material of the barrier dispersion layer (3).

9. Multilayer composite material according to one of claims 1 to 8, characterized in that, - that the multilayer composite material has a layer structure in the following order: base layer (1); intermediate layer (2); barrier dispersion layer (3); thin film (4); sealing layer (5), or that the multilayer composite material has a layer structure in the following order: base layer (1); intermediate layer (2); thin film (4); barrier dispersion layer (3); sealing layer (5) and / or - that the base layer (1 ) and the sealing layer (5) form outer layers of the multilayer composite material.

10. Multilayer composite material according to one of claims 1 to 9, characterized in that the intermediate layer (2) and / or the sealing layer (5) are formed from or comprise a thermoplastic polymer material.

11. Multilayer composite material according to one of claims 1 to 10, 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. 65030 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 12. Multilayer composite material according to one of claims 1 to 11, characterized in that, - that the multilayer composite material has the following layer structure, in particular in the order mentioned: o a base layer (1 ) made of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019, o an extrusion-coated intermediate layer (2) arranged on the base layer (1) with a basis weight between 3 g / m² 2 and 10 g / m² 2 , o a barrier dispersion layer (3) arranged on the intermediate layer (2) with a basis weight between 0.5 g / m² 2 and 3 g / m² 2based on the dry mass of the barrier dispersion layer material (3), a metallic and / or ceramic thin film (4) arranged on the barrier dispersion layer (3), and an extrusion-coated sealing layer (5) arranged on the thin film (4) with a basis weight between 3 g / m² 2 and 10 g / m² 2 , - or that the multilayer composite material has the following layer structure, in particular in the order mentioned: o a base layer (1 ) made of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019, o an extrusion-coated intermediate layer (2) arranged on the base layer (1) with a basis weight between 3 g / m² 2 and 10 g / m² 2 , o a metallic and / or ceramic thin film (4) arranged on the intermediate layer (2) o a barrier dispersion layer (3) arranged on the thin film (4) with an areal weight between 0.5 g / m² 2 and 3 g / m²2 based on the dry mass of the barrier dispersion layer material (3), or an extrusion-coated sealing layer (5) arranged on the barrier dispersion layer (3) with a basis weight between 3 g / m² 2 and 10 g / m² 2 . 65030 / MB / - Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 13. Method for producing a multilayer composite material according to any one of claims 1 to 12, comprising the following steps: - Provisioning the base layer (1 ), - Extrusion of a thermoplastic polymer onto the base layer (1) and smoothing of the extruded thermoplastic polymer using a cooled smooth roller to form the intermediate layer (2), - Dispersion coating of the intermediate layer (2) with a barrier dispersion to form the barrier dispersion layer (3), - Coating the barrier dispersion layer (3) with the metallic and / or ceramic thin film (4), and - Extruding a thermoplastic polymer onto the thin film (4) to form the sealing layer (5) or comprising the following steps: - Provisioning the base layer (1 ), - Extrusion of a thermoplastic polymer onto the base layer (1) and smoothing of the extruded thermoplastic polymer using a cooled smoothing roller to form the intermediate layer (2), - Coating the intermediate layer (2) with the metallic and / or ceramic thin film (4), - Dispersion coating of the thin film (4) with a barrier dispersion to form the barrier dispersion layer (3), and - Extruding a thermoplastic polymer onto the barrier dispersion layer (3) to form the sealing layer (5).

14. Method according to claim 13, characterized in that the smoothing roller has a surface temperature of 15°C to 30°C, and / or that the surface of the smoothing roller has one or more of the following roughness parameters: mean roughness Ra at most 0.05 pm; roughness depth Rz at most 0.3 pm, maximum roughness depth Rmax at most 0.5 pm.

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