DE102023103325A1 - Packaging layer material with paper layer and biodegradable polymer - Google Patents

Abstract

The present invention relates to a packaging layer material (10) comprising at least one paper layer (12) and a plurality of polymer layers (14, 16), wherein the plurality of polymer layers (14, 16) comprises a polyolefin dispersion layer (14) and a biopolymer layer arrangement (16) with at least one layer (18, 20, 22, 24, 26) made of a biopolymer.

Description

The present invention relates to a packaging layer material. The packaging layer material comprises at least one paper layer and a plurality of polymer layers. The present invention further relates to a method for producing such a packaging layer material.

Such packaging layer materials are generally used to produce thin-walled packaging, such as packaging bags, in particular 3- or 4-edge sealed bags, so-called “flow wraps”, which are also referred to as “flow packs”, container lids and the like. Such packaging layer materials can also be generally used as wrapping materials.

Currently, different, essentially contradictory requirements are placed on packaging layer materials: on the one hand, packaging layer materials should protect the packaged goods as well as possible from external influences. Barrier properties are desired that significantly reduce the migration of oxygen and/or water vapor or moisture through the packaging layer material. On the other hand, packaging layer materials should be as recyclable as possible in order to avoid environmental pollution from the use of packaging layer materials.

Paper as a fiber material layer with essentially organic fiber material is particularly advantageous for recycling, but has almost none of the barrier properties mentioned above. In the past, paper layers were therefore combined with metal layers, especially aluminum layers, in order to obtain a layer composite with sufficient barrier properties. The barrier properties against the migration of oxygen and water vapor were provided exclusively by the metal layer. Such layer composites are also referred to in the state of the art as "Met-Pap" or "Metpap" in order to give a short and catchy name to the composite of a metal layer and a paper layer.

The problem with the well-known Metpap packaging layer materials is again their unfavorable environmental impact, since on the one hand the production of a metal foil as a metal layer is energy-intensive and on the other hand Metpap packaging layer material is difficult or even impossible to recycle.

It is therefore an object of the present invention to provide a packaging layer material which can be produced cost-effectively and which is suitable for the production of closed packaging, such as packaging bags, flow packs, sachets, and the like, as well as packaging components, such as container lids and wrapping sheets, which has good recycling properties and which also has sufficient barrier properties for the packaging of foodstuffs.

The present invention solves this problem according to one product aspect by a packaging layer material which comprises a paper layer and a plurality of polymer layers, wherein the plurality of polymer layers comprises a polyolefin dispersion layer and a biopolymer layer arrangement with at least one layer made of a biopolymer.

The paper layer ensures good recyclability and, due to its organic fiber material, good environmental compatibility. In addition, paper is excellently printable and can be provided with product information and/or aesthetic decorations on at least one side in order to arouse the interest of consumers and to inform interested consumers about the packaged product, such as the product itself, the amount of product packaged, the origin of the product, its composition, its nutritional value and the like.

The paper layer is preferably a coated paper or a machine-smooth paper with a basis weight preferably in the range of 30 to 150 g/m ² . The paper layer can be a coated or uncoated paper layer. The paper layer is preferably a coated paper layer or is coated at least on the side on which, according to a preferred development of the invention, the polyolefin dispersion layer is applied, in order to provide the most homogeneous possible basis for the application of the polyolefin dispersion layer. A coating of the paper layer is not considered a separate layer in the sense of the present application, but is part of the paper layer.

The polyolefin dispersion layer can be simply applied to the paper layer as a dispersion layer and can form a water vapor or moisture barrier layer. Basically, polypropylene and polyethylene are suitable as polyolefins, with polyethylene being preferred. Polyethylene can be provided in different density classes, of which high-density polyethylene (HDPE) is preferred to achieve a good water vapor barrier. Polyethylene with a density in the range of 0.94 to 0.97 g/cm ³ is usually considered HDPE.

The biopolymer layer arrangement can provide additional functional layers on the packaging layer material. Any polymer that complies with EN 13432 , into the special EN 13432:2000 , is certified as compostable. It does not matter whether the compostability is compostability in private households or home composting (so-called "OK Compost HOME" certificate) or compostability in industrial processes in a composting process at a higher temperature level (so-called "OK Compost INDUSTRIAL" certificate). In any case, the biopolymer certified in this way is sufficiently biodegradable.

The biopolymer layer arrangement can have exactly one biopolymer layer or a plurality of biopolymer layers. The biopolymer layer arrangement has only layers made of biopolymers. In the case of a plurality of biopolymer layers in the biopolymer layer arrangement, the biopolymer layers can be made of the same biopolymer or of different biopolymers. To improve the ability of biopolymer layers of different biopolymers to be connected, the different biopolymers of immediately adjacent biopolymer layers are preferably compatible with one another.

Because of the good printability, the paper layer on a package made from the packaging layer material will often be located further out in relation to the packaging space surrounded by the packaging, i.e. closer to the outside environment, than the biopolymer layer arrangement. In order to keep moisture, which could migrate through the paper layer to the biopolymer layer arrangement, as far away from the biopolymer layer arrangement as possible, it is preferably provided that the polyolefin dispersion layer is arranged between the paper layer and the biopolymer layer arrangement.

In order to achieve the best possible environmental compatibility not only of the end product but also of the manufacturing process, the polyolefin dispersion layer is preferably formed from a water-based polyolefin dispersion.

Preferably, the polyolefin dispersion layer is designed such that it has a water vapor transmission rate of not more than 10 g/(m ² ·d), measured according to EN ISO 15106-2 with the following test conditions: 23 °C and 85 % relative humidity.

In order to achieve this maximum water vapor transmission rate, the polyolefin dispersion layer can be applied with a coating weight in the range of 1.5 to 5.5 g/m ^2. This applies in particular to a polyolefin dispersion layer with a double layer of polyolefin applied in dispersion. The polyolefin applied in dispersion is preferably polyethylene

The biopolymer layer arrangement preferably also contributes to the barrier effect of the entire packaging layer material. Since the polyolefin dispersion layer already forms a water vapor or moisture barrier layer of the packaging layer material, the biopolymer layer arrangement preferably forms an oxygen barrier layer. For this purpose, the biopolymer layer arrangement can preferably have a layer made of butenediol-vinyl alcohol copolymer.

Preferably, the layer of butenediol-vinyl alcohol copolymer has an oxygen transmission rate of not more than 0.5 cm ³ /(m ² ·d·bar), measured according to DIN53380-3 with the following test conditions: 23 °C and 50 % relative humidity.

The layer of butenediol-vinyl alcohol copolymer is preferably applied with a layer thickness in the range of 1 µm to 10 µm, particularly preferably extruded. In this way, the desired maximum oxygen transmission rate can be undercut.

As an additional functional layer, the biopolymer layer arrangement can have at least one further thermoplastic biopolymer layer. As a thermoplastic biopolymer layer, this can be extruded. This can also be formed from butenediol-vinyl alcohol copolymer, but preferably comprises a different biopolymer.

For example, the at least one further thermoplastic biopolymer layer can contribute to promoting adhesion between the layer made of butenediol-vinyl alcohol copolymer and the polyolefin dispersion layer. In this case, the biopolymer layer arrangement preferably has a first thermoplastic biopolymer layer between the polyolefin dispersion layer and the layer made of butenediol-vinyl alcohol copolymer.

Additionally or alternatively, the at least one thermoplastic biopolymer layer can serve to seal the connecting layer material with another polymer layer or the at least one thermoplastic biopolymer layer can shield the layer of butenediol-vinyl alcohol copolymer, specifically on the side of the layer of butenediol-vinyl alcohol copolymer facing away from the polyolefin dispersion layer. Preferably, the biopolymer layer arrangement can therefore have a second thermoplastic biopolymer layer such that the layer of butenediol-vinyl alcohol copolymer is arranged between the second thermoplastic biopolymer layer and the polyolefin dispersion layer.

The ordinal numbers “first” and “second” only indicate the order in which the thermoplastic biopolymer layer in the present application. In particular, the statement "second thermoplastic biopolymer layer" does not indicate that a "first thermoplastic biopolymer layer" must be present. Only the second thermoplastic biopolymer layer can be present.

As already explained, the second thermoplastic biopolymer layer can act as a sealing layer and form an outer layer with a free surface of the packaging layer material.

The first thermoplastic biopolymer layer can be provided with a layer weight in the range of 5 g/m ² and 20 g/m ² or with a layer thickness in the range of 6.2 µm to 24.8 µm. The second thermoplastic biopolymer layer can be provided with a layer weight in the range of 5 g/m ² and 20 g/m ² or with a layer thickness in the range of 6.2 µm to 24.8 µm. The first and second thermoplastic biopolymer layers preferably differ in their layer thickness by no more than 10% relative to the thicker of the two layers. The first and second thermoplastic biopolymer layers are particularly preferably the same thickness.

To improve the stability of the biopolymer layer arrangement, an adhesion promoter layer made of biodegradable material can be arranged between the first thermoplastic biopolymer layer and the layer made of butenediol-vinyl alcohol copolymer and/or between the second thermoplastic biopolymer layer and the layer made of butenediol-vinyl alcohol copolymer. The adhesion promoter layer can, for example, be made of biodegradable material or at least comprise biodegradable material. The at least one adhesion promoter layer can be provided with a layer weight in the range of 1 g/m ² and 10 g/m ² or with a layer thickness in the range of 1.24 µm to 10.24 µm. The adhesion promoter layers are also made of a biopolymer according to the above definition.

In principle, the first and second thermoplastic biopolymer layers can be made from different biopolymers. In terms of manufacturing technology, it is easier and therefore preferred for the first and second thermoplastic biopolymer layers to be made from the same biopolymer material. The first and second biopolymer layers can then be coextruded from one and the same extruder feed with two extruder nozzles. The at least one further thermoplastic biopolymer layer, i.e. the first and/or second thermoplastic biopolymer layer, can comprise at least one of the following materials or be made from them: polybutylene succinate co-adipate, polybutylene succinate, polylactic acid.

The biopolymer layer arrangement can be constructed symmetrically with respect to a middle layer arrangement, which facilitates its arrangement in packaging layer material and avoids possible arrangement errors. In addition, the biopolymer layer arrangement can be coextruded particularly easily as a symmetrical layer arrangement in the extrusion process and applied to another layer, usually to the polyolefin dispersion layer. For manufacturing reasons, the biopolymer layer arrangement preferably has an odd number of biopolymer layers. The middle layer is preferably the above-mentioned layer made of butenediol-vinyl alcohol copolymer.

According to a preferred development of the present invention, an above-mentioned adhesion promoter layer made of biodegradable polymer material is arranged on both sides of the middle layer and a further thermoplastic biopolymer layer is arranged on each side of the adhesion promoter layers facing away from the middle layer.

In principle, it should not be ruled out that at least one further layer is arranged between the paper layer and the polyolefin dispersion layer. However, in order to keep the number of layers of the packaging layer material as low as possible, the polyolefin dispersion layer is preferably arranged directly on the paper layer.

More preferably, the biopolymer layer arrangement is arranged directly on the polyolefin dispersion layer.

Preferably, the packaging layer material is free of metal foils and free of vacuum-deposited coatings, such as metallic coatings or metal oxide coatings. This advantageously means that there are no layers or coatings that make recycling the packaging layer material more difficult.

1. a.) Bereitstellen einer Papierlage,
2. b.) Auftragen einer wasserbasierten Polyolefindispersion auf die Papierlage und dadurch Bildung einer Polyolefin-Dispersionslage,
3. c.) Extrusion einer Biopolymer-Lagenanordnung auf die Polyolefin-Dispersionslage.

With the above description of the advantageous packaging layer material according to the present application, process aspects for producing the packaging layer material have already been disclosed. The above-mentioned object is also achieved according to a process aspect by a process for producing a packaging layer material as described and further developed above. The process comprises the following steps:

1. a.) Providing a paper layer,
2. b.) Applying a water-based polyolefin dispersion to the paper layer and thereby forming a polyolefin dispersion layer,
3. c.) Extrusion of a biopolymer layer arrangement onto the polyolefin dispersion layer.

Preferably, the biopolymer layer arrangement is applied as a multi-layer arrangement in a single extrusion step, so that laminating operations such as those required for Metpap packaging material layers can be omitted. In addition, there is no waiting time for any layers to harden. After the biopolymer layer arrangement has been extruded, the packaging layer material thus formed can be processed immediately.

In principle, another biodegradable fiber material layer can be used instead of a paper layer, such as a layer of cardboard to create more rigid packaging.

• 1 eine grobschematische Querschnittsansicht durch ein Verpackungslagenmaterial der vorliegenden Erfindung, und
• 2 eine grobschematische Ansicht einer mit dem Verpackungslagenmaterial von 1 gebildeten Verpackung.

The present invention will be explained in more detail below with reference to the accompanying drawing. It shows:

• 1 a roughly schematic cross-sectional view through a packaging layer material of the present invention, and
• 2 a rough schematic view of a packaging layer material from 1 formed packaging.

The representations in the 1 and 2 are not to scale.

In 1 is a roughly schematic cross-section through an embodiment of a packaging layer material of the present invention and is designated by reference numeral 10. The 1 Exposed surface 10a of the packaging layer material 10 preferably forms an outer side of a package made from the packaging layer material 10, such as the package 80 of 2 . The exposed surface 10b of the packaging layer material 10 accordingly preferably forms an inner side of a packaging formed from the packaging layer material 10.

The packaging layer material 10 comprises, as a substrate layer, a paper layer 12 with a basis weight of, for example, 60 g/m ² . The paper layer 12 is made of coated paper in order to advantageously provide smooth surfaces 12a and 12b.

On the 1 A print job 11 made of printing inks, indicated only by dashed lines, can be applied to the surface 12a shown as an exposed surface, for example in four-color printing. Any print job 11 can be shielded from external influences by a protective varnish 13, also indicated only by dashed lines, so that the print job 11 is arranged between the protective varnish 13 and the paper layer 12. In this case, an exposed surface 13a of the protective varnish 13 facing away from the paper layer 12 forms the outside of the packaging layer material 10.

A water-based polyolefin dispersion is applied to the surface 12b of the paper layer 12, which forms a polyolefin dispersion layer 14 when dried. In the preferred embodiment, the polyolefin dispersion layer 14 is made of the polyolefin polyethylene. In the embodiment shown, the polyolefin dispersion layer 14 has an application weight of 4 g/m ² . The polyolefin dispersion layer 14 forms a water vapor barrier layer of the packaging layer material 10. The water vapor transmission rate through the polyolefin dispersion layer 14 is 10 g/(m ² ·d) or less, measured according to EN ISO 15106-2 with the following test conditions: 23 °C and 85 % relative humidity.

A biopolymer layer arrangement 16 is applied to the side of the polyolefin dispersion layer 14 facing away from the paper layer 12, which in the example shown comprises exactly 5 layers, each made from a biopolymer. Biopolymers are the polymers mentioned in the introduction to the description that are certified as compostable in at least one composting process from the home composting process and the industrial composting process in accordance with the standard specified there.

The central layer of the biopolymer layer arrangement 16 is a layer 18 made of butenediol-vinyl alcohol copolymer. The layer 18 has a layer thickness of 5 µm. It has an oxygen transmission rate of 0.5 cm ³ /(m ² d bar) or less, measured according to DIN 53380-3 with the following test conditions: 23 °C and 50% relative humidity. The layer 18 therefore serves as an oxygen barrier layer in the packaging layer material 10.

An adhesion promoter layer 20 or 22 made of biopolymer is applied to both sides of the layer 18. The adhesion promoter layers 20 and 22, which are preferably made of identical material, each have a layer weight of 5 g/m ² or a layer thickness of 6.2 µm.

Adjoining the adhesion promoter layer 20 is a first thermoplastic biopolymer layer 24, which itself acts as an adhesion promoter layer towards the polyolefin dispersion layer 14. The first thermoplastic biopolymer layer 24 can be formed, for example, from polybutylene succinate-adipate copolymer or at least comprise such a copolymer. For example, the first thermoplastic biopolymer layer 24 can be formed from a blend of polybutylene succinate-adipate copolymer and polybutylene succinate.

In the illustrated embodiment, the first thermoplastic biopolymer layer 24 has a layer thickness of 12.4 µm.

The adhesion promoter layer 22 connects the central layer 18 to a second thermoplastic biopolymer layer 26, which in this case serves as a sealing layer. Its exposed surface 26b therefore forms the exposed surface 10b of the packaging layer material 10.

In the present embodiment, the second thermoplastic biopolymer layer 26 is identical to the first thermoplastic biopolymer layer 24, which is why reference is made to the above information on the first thermoplastic biopolymer layer 24 for a further description of the second thermoplastic biopolymer layer 26.

The biopolymer layer arrangement 16 is formed symmetrically with respect to the layer 18 made of butenediol-vinyl alcohol copolymer as the middle layer. The layers 18, 20, 22, 24 and 26 are preferably co-extruded.

In 2 a four-edge sealed bag is shown as a packaging 80 formed from the packaging layer material 10 merely by way of example. Two rectangular blanks made of packaging layer material 10 rest against one another with their inner sides 26b and 10b in the edge region 82 and are materially bonded to one another by thermal sealing.

The edge region 82 surrounds a receiving space 84 of the packaging 80, in which a packaged product 86 is received. Apart from the edge region 82, the receiving space 84 is delimited by the two blanks of the packaging layer material 10 which are sealed together.

The surface 10a of the packaging layer material 10 of 1 forms the outside of the packaging 80.

Due to the materials used, the packaging 80 is not only suitable for packaging food, because the packaging layer material 10 of the packaging 80 as a whole has a water vapor transmission rate of 5 g/(m ² ·d) or less, measured according to EN ISO 15106-2 with the following test conditions: 23 °C and 85 % relative humidity and an oxygen transmission rate of 0.5 cm ³ /(m ² ·d·bar) or less, measured according to DIN53380-3 with the following test conditions: 23 °C and 50 % relative humidity.

To prevent premature oxidation of food components or softening or decay due to moisture absorption, packaging materials are suitable for food contact if they have a water vapor transmission rate of 5 g/(m ² ·d) or less, measured according to EN ISO 15106-2 with the following test conditions: 23 °C and 85 % relative humidity, and an oxygen transmission rate of 0.5 cm ³ /(m ² ·d·bar) or less, measured according to DIN53380-3 with the following test conditions: 23 °C and 50 % relative humidity.

In addition, the materials used allow the packaging 80 to be recycled or easily disposed of after use.

The packaging is free of metal foils and vapor-deposited layers of metal or a metal compound, such as a metal oxide. This makes the packaging 80 cost-effective to produce.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited non-patent literature

• EN 13432 [0011]
• EN 13432:2000 [0011]
• DIN EN ISO 15106-2 [0015, 0041, 0053, 0054]
• DIN 53380-3 [0018, 0053, 0054]

Claims (15)

Packaging layer material (10) comprising at least one paper layer (12) and a plurality of polymer layers (14, 16), wherein the plurality of polymer layers (14, 16) comprises a polyolefin dispersion layer (14) and a biopolymer layer arrangement (16) with at least one layer (18, 20, 22, 24, 26) made of a biopolymer. Packaging layer material (10) according to Claim 1 , characterized in that the polyolefin dispersion layer (14) is arranged between the paper layer (12) and the biopolymer layer arrangement (16). Packaging layer material (10) according to Claim 1 or 2 , characterized in that the polyolefin dispersion layer (14) is formed from a polyolefin dispersion. Packaging layer material (10) according to one of the preceding claims, characterized in that the polyolefin dispersion layer (14) is applied with an application weight in the range of 15.5 to 5.5 g/m ² . Packaging layer material (10) according to one of the preceding claims, characterized in that the biopolymer layer arrangement (16) comprises a layer (18) of butenediol-vinyl alcohol copolymer. Packaging layer material (10) according to one of the preceding claims, characterized in that the biopolymer layer arrangement (16) has at least one further thermoplastic biopolymer layer (24, 26). Packaging layer material (10) according to Claim 6 , characterized in that the biopolymer layer arrangement (16) has a first thermoplastic biopolymer layer (24) between the polyolefin dispersion layer (14) and the layer (18) of butenediol-vinyl alcohol copolymer. Packaging layer material (10) according to Claim 6 or 7 , characterized in that the biopolymer layer arrangement (16) has a second thermoplastic biopolymer layer (26) such that the layer (18) of butenediol-vinyl alcohol copolymer is arranged between the second thermoplastic biopolymer layer (26) and the polyolefin dispersion layer (14). Packaging layer material (10) according to Claim 8 , characterized in that the second thermoplastic biopolymer layer (26) forms an outer layer with a free surface (26b) as a sealing layer. Packaging layer material (10) according to one of the Claims 7 until 9 , characterized in that an adhesion promoter layer (20, 22) made of biodegradable material is arranged between the first thermoplastic biopolymer layer (24) and the layer (18) made of butenediol-vinyl alcohol copolymer and/or between the second thermoplastic biopolymer layer (26) and the layer (18) made of butenediol-vinyl alcohol copolymer. Packaging layer material (10) according to one of the Claims 7 until 10 , characterized in that the first and second thermoplastic biopolymer layers (24, 26) are formed from the same biopolymer material. Packaging layer material (10) according to one of the Claims 7 until 10 , characterized in that the at least one further thermoplastic biopolymer layer (24, 26) comprises at least one of the following materials or is formed from at least one of the following materials: polybutylene succinate co-adipate, polybutylene succinate, polylactic acid. Packaging layer material (10) according to one of the preceding claims, characterized in that the biopolymer layer arrangement (16) is constructed symmetrically with respect to a middle layer arrangement (18). Packaging layer material (10) according to one of the preceding claims, characterized in that the polyolefin dispersion layer (14) is arranged directly on the paper layer (12) and that the biopolymer layer arrangement (16) is arranged directly on the polyolefin dispersion layer (14). Method for producing a packaging layer material (10) according to one of the preceding claims, comprising the following steps: a.) providing a paper layer (12), b.) applying a water-based polyolefin dispersion to the paper layer and thereby forming a polyolefin dispersion layer (14), c.) extruding a biopolymer layer arrangement (16) onto the polyolefin dispersion layer (14).

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