Multilayer composite material and method

Abstract

The invention relates to a multilayer composite material comprising the following layers: a base layer comprising or consisting of paper; and a sealing layer comprising or consisting of a thermoplastic polymer, the sealing layer being an extruded layer and having a weight per unit area 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 method for producing same.

Description

[0001] 65025 / 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 current technological standards. A specific example is polymer-coated papers, which, for instance, have a paper / PE layer structure. Such multilayer composite materials typically exhibit good grease and / or water resistance. Furthermore, the outer polymer layer ensures the material's sealability.

[0006] Although such laminate structures exhibit good barrier and sealing properties, they usually present significant disadvantages with regard to recyclability. Separating plastic 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. 65025 / MB

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

[0008] Given the increasing global efforts to minimize the environmental impact of packaging materials and increase recycling rates, there is an urgent need for more advanced packaging.

[0009] These materials should provide the necessary barrier properties, improve recyclability, and exhibit good sealing properties. One object of the present invention can therefore be seen as at least partially meeting this need.

[0010] In particular, the use of materials for the non-paper components of a multi-layer composite material should be kept as low as possible without impairing the barrier and sealing properties of the material.

[0011] It was surprisingly found that these and other tasks can be solved, in particular, by providing a multilayer composite material combining a paper layer with an extruded sealing layer. Specifically, the sealing layer has a basis weight of less than 8.0 g / m². 2 exhibits.

[0012] The described multilayer composite material comprises, in particular, a base layer made of paper, preferably kraft paper, and a sealing layer. Advantageously, the multilayer composite material is two-layered. The sealing layer is advantageously an extruded layer comprising or consisting of a thermoplastic polymer.

[0013] 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.

[0014] The multilayer composite material can therefore have at least two sublayers or consist of two sublayers. Optionally, the base layer and the sealing layer form outer layers of the material. Optionally, the base layer and the sealing layer are in direct contact with each other. The base layer is made of 65025 / MB.

[0015] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0016] Paper may have a basis weight between 25 g / m² 2 and 130 g / m² 2 determined according to ISO 536:2019.

[0017] 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.

[0018] 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.

[0019] 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 2 If 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 2The 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.

[0020] The sealing layer can, for example, comprise or consist of polyolefins. These can be homopolymers and / or copolymers, and mixtures of different polymers are also conceivable. The sealing layer can comprise or consist of polyethylene. The polyethylene can be a polyethylene homopolymer. The polyethylene can also be a polyethylene copolymer.

[0021] The sealing layer can be made of polyethylene with a density of less than 0.95 g / cm³. 3 , possibly less than 0.93 g / cm³ 3 , comprise or consist of.

[0022] The sealing layer may comprise or consist of polyethylene with a melt flow index (MFI) between 5 g / 10 min and 20 g / 10 min, the melt flow index being determined in accordance with ISO 1133-1:2022. In particular, the melt flow index may be determined at 190°C and 2.16 kg. 65025 / MB Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0023] The paper content of the multilayer composite material can be at least 80 wt.%, at least 90 wt.% or at least 95 wt.%, based on the total mass of the multilayer composite material.

[0024] The base layer, also known as the paper layer, may include or consist of kraft paper. Specific examples of papers suitable for use as a base layer are papers, particularly kraft papers, in the Machine Finished (MF; also known as "machine-finished paper"), Machine Glazed (MG; also known as "one-sided glazed paper"), or Semi Extensible (SE) grades. SE grade paper typically has a machine-directed extensibility of between 3.5% and 6%, determined according to ISO 1924-3:2005, and is not subjected to any surface treatment, such as calendering. SE grade paper may also be referred to as Semi Clupak paper.

[0025] The sealing layer is preferably in direct contact with the paper.

[0026] 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”).

[0027] The invention may relate to a multi-layer composite material comprising the following layers: a base layer comprising or consisting of paper, in particular kraft paper; and a sealing layer comprising or consisting of a thermoplastic polymer.

[0028] Preferably, the sealing layer is an extruded layer with 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.

[0029] 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. 65025 / MB

[0030] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0031] If applicable, the sealing layer may comprise or consist of polyethylene, in particular a polyethylene homopolymer or a polyethylene copolymer.

[0032] If applicable, the thermoplastic polymer of the sealing layer is provided to have a melt flow index of between 5 g / 10 min and 20 g / 10 min, the melt flow index being determined in accordance with ISO 1133-1 :2022 at 190°C and 2.16 kg.

[0033] If applicable, the paper of the base layer is specified as a machine finished kraft paper, a machine glazed kraft paper or a semi extensible kraft paper.

[0034] If necessary, the multi-layer composite material is designed to consist of the base layer and the sealing layer.

[0035] If applicable, the multilayer composite material is provided for to have a paper content of at least 80 wt.%, optionally at least 90 wt.%, in particular at least 95 wt.%, based on the total mass of the multilayer composite material.

[0036] If necessary, the base layer is to be made of paper with a basis weight between 25 g / m². 2 and 130 g / m² 2 is determined in accordance with ISO 536:2019.

[0037] The invention may relate to a method for producing a multilayer composite material as described herein, comprising the following steps: providing the base layer; extruding a thermoplastic polymer onto the base layer to form the sealing layer.

[0038] The invention may relate to the use of a multilayer composite material as described herein as packaging material, particularly for liquid, pasty, or dry products, for example, food or cosmetics. 65025 / MB

[0039] Mondi AG, Marxergasse 4A, 1030 Vienna (AT)

[0040] 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.

[0041] The multilayer composite material according to this embodiment is two-layered and has the following layer sequence: base layer made of paper - sealing layer made of polyethylene. In this embodiment, the base layer and the sealing layer form the outer layers of the multilayer composite material.

[0042] In the production of the composite material, a surface of the base layer is extruded to form the sealing layer.

[0043] In this embodiment, the base layer is a white kraft paper with a basis weight of approximately 80 g / m². 2 , determined according to ISO 536:2019 and with a machine-directed elongation of approximately 7.0%, determined according to ISO 1924-3:2005. It is a machine-finished kraft paper.

[0044] The sealing layer material is a polyethylene copolymer with a melt flow index of approximately 7.5 g / 10 min determined at 190°C and 2.16 kg according to ISO 1133-1:2022. The density of this polymer is approximately 0.921 g / cm³. 3 and the melting point is approximately 108°C.

[0045] The sealing layer is applied in a quantity of approximately 4.0 g / m². 2 extruded onto the base layer.

[0046] The resulting multi-layer composite material thus has a paper content of approximately 95% by weight.

Claims

65025 / MB Mondi AG, Marxergasse 4A, 1030 Vienna (AT) Claims 1. Multilayer composite material with the following layers: - a base layer comprising or consisting of paper, especially kraft paper, and - 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.

2. Multilayer composite material according to claim 1, characterized in that the sealing layer 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.

3. Multilayer composite material according to claim 1 or 2, characterized in that the sealing layer comprises or consists of polyethylene, in particular a polyethylene homopolymer or a polyethylene copolymer.

4. Multilayer composite material according to one of claims 1 to 3, characterized in that the thermoplastic polymer of the sealing layer has a melt flow index of between 5 g / 10 min and 20 g / 10 min, wherein the melt flow index is determined according to ISO 1133-1 :2022 at 190°C and 2.16 kg.

5. Multilayer composite material according to one of claims 1 to 3, characterized in that the paper of the base layer is a machine finished kraft paper, a machine glazed kraft paper or a semi extensible kraft paper.

6. Multilayer composite material according to one of claims 1 to 5, characterized in that the multilayer composite material consists of the base layer and the sealing layer. 65025 / MB Mondi AG, Marxergasse 4A, 1030 Vienna (AT) 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.%, optionally at least 90 wt.%, in particular at least 95 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 base layer is made of paper with a basis weight between 25 g / m² 2 and 130 g / m² 2 is determined in accordance with ISO 536:2019.

9. Method for producing a multilayer composite material according to any one of claims 1 to 8, comprising the following steps: - Providing the base layer, - Extruding a thermoplastic polymer onto the base layer to form the sealing layer.

10. Use of a multilayer composite material according to any one of claims 1 to 8, as packaging material, in particular for liquid, pasty or dry products, for example for food or cosmetics.