Multilayer composite material and process

Abstract

The invention relates to a multilayer composite material having the following layers: a base layer (1) comprising or consisting of paper; a dispersion layer (2); a metallic and / or ceramic thin layer (3); and a sealing layer (4) comprising or consisting of a thermoplastic polymer, wherein the sealing layer (4) is an extruded layer and has a basis weight of less than 8.0 g / m2, optionally at most 7.5 g / m2, in particular at most 7.0 g / m2. The invention also relates to the use of the multilayer composite material and to a process for production thereof.

Description

[0001] 65029 / MB / VH

[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 65029 / MB / VH

[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, improve recyclability and offer good sealing properties.

[0011] Multilayer composite materials are known that, instead of conventional aluminum foil, feature a thin metallic film in combination with two polymer layers. Paper can be used as the substrate. One such layer structure known from the prior art is: paper / / polymer pre-coating / / thin aluminum film / / dispersion sealing 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 reduced thickness and improved recyclability; however, the lower mechanical seal strength of the 65029 / MB / VH is a disadvantage.

[0013] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0014] Dispersion sealing layers have a significant disadvantage. Furthermore, the production of dispersion layers typically involves a narrow temperature range that results in a continuous layer, making the material recyclable.

[0015] The aforementioned problems of the prior art result in a conflict of objectives, which consists in particular of providing a packaging material that exhibits good sealability, reproducible and good recyclability, and a lower content of non-paper components. This packaging material should also be suitable for the production of bags with stand-up bottoms and / or side gussets.

[0016] The object of the present invention is to at least partially resolve this conflict of objectives. In particular, the material usage for the non-paper components of a multilayer composite material should be kept as low as possible without impairing the barrier and sealing properties of the material. A further object of the invention may be to provide a multilayer composite material that is suitable for the aforementioned packaging purposes and exhibits advantageous barrier properties as well as good recyclability.

[0017] It was surprisingly found that these and other tasks can be solved, in particular, by providing a multilayer composite material combining a dispersion layer and a thin film with an extruded sealing layer. Specifically, the sealing layer has a basis weight of less than 8.0 g / m². 2 exhibits.

[0018] The described multilayer composite material comprises, in particular, a base layer of paper, preferably kraft paper, a dispersion layer, a metallic / ceramic thin film, and a sealing layer. Advantageously, the layer structure of the multilayer composite material is in the order mentioned here. The sealing layer is advantageously an extruded layer comprising or consisting of a thermoplastic polymer. 65029 / MB / VH

[0019] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0020] It should be noted that, in connection with the present disclosure, the term "thermoplastic polymer" also includes thermoplastic oligomers, provided they are suitable for use as a sealing layer.

[0021] The multilayer composite material can therefore have at least four sublayers or consist of four sublayers. Optionally, the base layer and the sealing layer form the outer layers of the material. The paper base layer may have a basis weight of 40 g / m². 2 and 130 g / m² 2 determined according to ISO 536:2019.

[0022] In particular, the sealing layer has a basis weight of less than 8.0 g / m². 2 , possibly at most 7.5 g / m² 2 , in particular a maximum of 7.0 g / m³ 2 , on.

[0023] If necessary, the sealing layer can have a basis weight of no more than 6.5 g / m². 2 , at most 6.0 g / m² 2 or at most 5.5 g / m² 2 exhibit.

[0024] In particular, the sealing layer has a basis weight of 3.0 g / m². 2 up to 7.0 g / m² 2 on, possibly between 3.0 g / m² 2 and 6.0 g / m² 2If necessary, the sealing layer has a basis weight of at least 1.0 g / m². 2 , at least 2.0 g / m² 2 or at least 3.0 g / m² 2 The sealing layer may have a basis weight of approximately 3.0 g / m². 2 The sealing layer may have a basis weight of approximately 4.0 g / m². 2 The sealing layer may have a basis weight of approximately 5.0 g / m². 2 The sealing layer may have a basis weight of approximately 6.0 g / m². 2 on.

[0025] The sealing layer can, for example, comprise or consist of polyolefins. These can be homo- and / or copolymers, and mixtures of different polymers are also conceivable. The sealing layer can also comprise or consist of polyethylene.

[0026] The dispersion layer, which is arranged in particular between the base layer and the thin film, can be produced by dispersion polymerization according to methods known in the art. 65029 / MB / VH

[0027] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0028] The paper content of the multilayer composite material can be at least 80 wt.%, based on the total mass of the multilayer composite material.

[0029] Thus, a basis weight of 0.5 g / m² can be used for the dispersion layer. 2 and 3 g / m² 2 The basis weight can be determined according to ISO 536:2019.

[0030] The 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; polyelectrolytes; clay minerals; graphene.

[0031] The thin film, which can be made of or comprise a metallic and / or ceramic material, can then be applied to the dispersion layer. Suitable materials include, among others: aluminum; silicon dioxide; aluminum oxide; magnesium oxide.

[0032] 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.

[0033] The dispersion layer is preferably in direct contact with the base layer and the thin film. The sealing layer is preferably in direct contact with the thin film.

[0034] Advantageously, the multilayer 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"). 65029 / MB / VH

[0035] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

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

[0037] - a base layer comprising or consisting of paper,

[0038] - a dispersion layer,

[0039] - a metallic and / or ceramic thin film, and

[0040] - a sealing layer comprising or consisting of a thermoplastic polymer, characterized in that the sealing layer is an extruded layer and has a basis weight of less than 8.0 g / m² 2 , possibly at most 7.5 g / m² 2 , in particular a maximum of 7.0 g / m³ 2 , exhibits.

[0041] If necessary, the thin film is intended to be in direct contact with the dispersion layer and the sealing layer.

[0042] If necessary, the sealing layer is designed to have a basis weight of 3.0 g / m². 2 up to 7.0 g / m² 2 , possibly between 3.0 g / m² 2 and 6.0 g / m² 2 , exhibits.

[0043] If necessary, the sealing layer is provided for to comprise or consist of polyethylene.

[0044] Optionally, the dispersion layer is intended to be in direct contact with the base layer and the thin film. Optionally, or alternatively, the base layer is intended to form an outer layer of the multilayer composite material.

[0045] If applicable, the multilayer composite material is designed to have a layer structure in the following order: base layer; dispersion layer; thin film; sealing layer, wherein the base layer and the sealing layer in particular form outer layers of the multilayer composite material.

[0046] Where 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. 65029 / MB / VH

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

[0048] If applicable, the thin film is provided to have a layer thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm.

[0049] If applicable, the material of the thin film is selected from: aluminum; silicon oxide; aluminum oxide; magnesium oxide.

[0050] 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.

[0051] If applicable, the dispersion layer is provided for to be formed from or comprise one or more of the following materials: PVOH, EVOH, acrylates, methacrylates, polyvinyl acetate, polyelectrolytes, clay minerals, graphene.

[0052] If necessary, the dispersion layer is designed to have a basis weight between 0.5 g / m². 2 and 3 g / m² 2exhibits, relative to the dry weight of the dispersion layer.

[0053] If applicable, the multi-layer composite material is designed to have the following layer structure:

[0054] - a base layer of paper with a basis weight between 40 and 130 g / m² 2 according to ISO 536:2019,

[0055] - a dispersion layer arranged on the base layer with a basis weight between 0.5 g / m² 2 and 3.0 g / m² 2 ,

[0056] - a metallic and / or ceramic thin film arranged on the dispersion layer with a layer thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm,

[0057] - an extrusion-coated sealing layer arranged on the thin film with a basis weight between 4.0 and 6.0 g / m² 2 , in particular about 4.0 g / m² 2 .

[0058] The invention may also relate to a method for producing a multilayer composite material described herein. 65029 / MB / VH

[0059] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0060] The process may include the following steps:

[0061] - Providing the base layer,

[0062] - Dispersion coating of the base layer to form the dispersion layer,

[0063] - Coating the dispersion layer with the metallic and / or ceramic thin film, and

[0064] - Extruding a thermoplastic polymer onto the thin film to form the sealing layer.

[0065] The invention may also relate to the use of a multilayer composite material described herein.

[0066] The multi-layer composite material can be used as packaging material, especially for liquid, pasty or dry products, for example for food or cosmetics.

[0067] An exemplary multilayer composite material according to the present disclosure is explained in detail below using an embodiment as an example. This embodiment is intended solely for illustrative purposes and does not limit the scope of protection defined by the claims.

[0068] Example 1

[0069] Figure 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.

[0070] The multilayer composite material shown in Fig. 1 has four layers and the layer sequence specified in Table 1. 65029 / MB / VH

[0071] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0072] Table 1: Layers of the multilayer composite material shown in Fig. 1

[0073] In the production of the multilayer composite material, the dispersion layer 2 is applied to the base layer 1 using PVOH. In this embodiment, the base layer 1 forms an outer layer. After drying and completion of the polymerization process, the thin film 3 is applied to the dispersion layer 2. The thin film is applied, for example, by vapor deposition.

[0074] Furthermore, the surface of the thin film 3 is extruded with polyethylene to form the sealing layer 4. The sealing layer 4 is also an outer layer.

[0075] The typical water vapor permeability of the multilayer composite material according to this embodiment is approximately 0.4 g / m². 2 .d at 23°C and 85% rH. Water vapor permeability is determined according to ASTM F 1249, if necessary. Typical oxygen permeability is approximately 1.8 cm. 3 / m 2 .d.bar at 23°C and 50% rh. Oxygen permeability is determined according to ASTM 1927 if necessary.

[0076] The seal strength of the multilayer composite material according to the exemplary embodiment at 120°C is approximately 6.6 N / 15 mm. The seal strength is determined according to the T-peel test of DIN 55529:2012, whereby the pressure during the sealing process is 2 bar for 1 see. 65029 / MB / VH Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0077] Comparative example

[0078] In a comparative example based on the state of the art, a multilayer composite material with five layers is described. The sequence of the layers is shown in Table 2.

[0079] Table 2: Layers of the multilayer composite material of the comparison example

[0080] The multilayer composite material is produced in a similar manner to the multilayer composite material of Example 1. In contrast to Example 1, after the thin film has been applied, a second dispersion layer is applied to the second, uncoated side of the thin film.

[0081] After drying and polymerization of the second dispersion layer, the surface of the second dispersion layer is extruded with polyethylene to form the sealing layer. The sealing layer is an outer layer.

[0082] The sealing strength of the multilayer composite material according to comparative example 1 at 120°C is approximately 5.9 N / 15 mm. The sealing strength is determined according to the T-peel test of DIN 55529:2012, whereby the pressure during the sealing process is 2 bar for 1 see.

[0083] Therefore, the sealing strength of the multilayer composite material of example 1, which comprises only one dispersion layer, is higher than that of the multilayer composite material of comparison example 1.

Claims

65029 / MB / VH 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, - a dispersion layer (2), - a metallic and / or ceramic thin film (3), and - a sealing layer (4) comprising or consisting of a thermoplastic polymer, characterized in that the sealing layer (4) is an extruded layer and has a basis weight of less than 8.0 g / m² 2 , possibly at most 7.5 g / m² 2 , in particular a maximum of 7.0 g / m³ 2 , exhibits.

2. Multilayer composite material according to claim 1, characterized in that the thin layer (3) is in direct contact with the dispersion layer (2) and with the sealing layer (4).

3. Multilayer composite material according to claim 1 or 2, characterized in that the sealing layer (4) has a basis weight of 3.0 g / m² 2 up to 7.0 g / m² 2 , possibly between 3.0 g / m² 2 and 6.0 g / m² 2 , exhibits.

4. Multilayer composite material according to one of claims 1 to 3, characterized in that the sealing layer (4) comprises or consists of polyethylene.

5. Multilayer composite material according to one of claims 1 to 4, characterized in that, - that the dispersion layer (2) is in direct contact with the base layer (1) and with the thin film (3), - and / or that the base layer (1) forms an outer layer of the multilayer composite material. 65029 / MB / VH Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 6. Multilayer composite material according to one of claims 1 to 5, characterized in that the multilayer composite material has a layer structure in the following order: base layer (1); dispersion layer (2); thin film (3); sealing layer (4), wherein the base layer (1) and the sealing layer (4) are in particular outer layers of the multilayer composite material.

7. Multilayer composite material according to one of claims 1 to 6, 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.

8. Multilayer composite material according to one of claims 1 to 7, characterized in that the thin film (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 (3) is selected from: aluminum; silicon oxide; aluminum oxide; magnesium oxide.

9. Multilayer composite material according to one of claims 1 to 8, 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.

10. Multilayer composite material according to one of claims 1 to 9, characterized in that the dispersion layer (2) is formed from or comprises one or more of the following materials: PVOH, EVOH, acrylates, methacrylates, polyvinyl acetate, polyelectrolytes, clay minerals, graphene.

11. Multilayer composite material according to one of claims 1 to 10, characterized in that the dispersion layer (2) has a basis weight between 0.5 g / m² 2 and 3.0 g / m² 2 exhibits, based on the dry weight of the dispersion layer (2). 65029 / MB / VH Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 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, - a dispersion layer (2) arranged on the base layer (1) with a basis weight between 0.5 g / m² 2 and 3.0 g / m² 2 , - a metallic and / or ceramic thin film (3) arranged on the dispersion layer (2) with a layer thickness of less than 500 nm, in particular less than 200 nm, preferably less than 100 nm, - an extrusion-coated sealing layer (4) arranged on the thin film (3) with a basis weight between 4.0 and 6.0 g / m² 2 , in particular about 4.0 g / m² 2 .

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 ), - Dispersion coating of the base layer (1 ) to form the dispersion layer (2), - Coating the dispersion layer (2) with the metallic and / or ceramic thin film (3), and - Extruding a thermoplastic polymer onto the thin film (3) to form the sealing layer (4).

14. Use of a multilayer composite material according to any one of claims 1 to 12, as packaging material, in particular for liquid, pasty or dry products, for example for food or cosmetics.

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