Multi-layer flexible packaging material

Abstract

The present invention relates generally to the field of multi-layer flexible packaging materials. In particular, the present invention relates to multi-layer flexible packaging materials for packaging dry food, preferably confectionery.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates generally to the field of multi-layer flexible packaging materials. In particular, the present invention relates to multi-layer flexible packaging materials. The present invention further relates to the use of the multi-layer flexible packaging materials according to the present invention for packaging dry food.

[0002] [Background technology] Plastic packaging is often used in economic activities and in people's daily lives. It has several advantages, such as flexibility and light weight. Such light weight contributes to a reduction in the demand for material resources and, for example, fuel savings and CO2 reduction during transportation. The barrier properties of plastic packaging have a positive effect on extending the shelf life and therefore help to reduce food waste. The barrier properties also help to ensure food safety.

[0003] However, according to the European Strategy for Plastics in a Circular Economy recently published by the European Commission, around 25.8 million tonnes of plastic waste is generated in Europe every year, less than 30% of this waste is recovered for recycling, and as much as 150,000-500,000 tonnes of plastic waste enters the oceans every year.

[0004] There are great efforts in industry and commerce to ensure the reduction of plastic waste. Some supermarkets, for example, have replaced plastic bags with paper-based bags. However, replacing plastic with paper in food packaging is not an easy task. The change in packaging material must not compromise consumer safety. The packaging must not only serve to protect the food during distribution, storage and retail, but must also be robust enough to be handled by machines during the production process and such that the food product can be effectively presented.

[0005] There is therefore a need for renewable, effectively recycled, cost-effective materials with improved barrier properties, in particular paper-based packaging materials with improved barrier properties due to their ability to be partially or fully recycled as well as to be effectively recycled in existing, well-established paper recycling facilities.

[0006] WO 2000 / 076862 in this regard describes a laminate structure for packaging applications comprising a paper substrate and at least one polymer / nanoclay composite layer having a thickness in the range of 0.7 to 9 nanometers and comprising clay particles, applied to the paper substrate.

[0007] However, there is a need in the art to further improve the barrier properties of paper-based packaging materials.

[0008] In particular, in packaging for food products, good barrier properties are essential to maintain the safety and quality of the packaged food. Typically, such barrier properties include gas permeability, e.g., O2, CO2, and N2 permeability; vapor permeability, e.g., water vapor permeability; liquid permeability, e.g., water or oil permeability; aroma permeability; and light permeability.

[0009] Furthermore, against this background of recycling, there is the problem that packaging is not disposed of properly by consumers, i.e., it is littered. Such material may end up in the natural environment. Moreover, traditional confectionery packaging is small, the likelihood of accidental littering is high, and the plastic materials used may take several years to decompose.

[0010] The present invention therefore seeks to balance the issues of barrier properties and recyclability.

[0011] Any reference to a prior art document in this specification should not be taken as an admission that such prior art is well known or forms part of the common general knowledge in the art.

[0012] [Summary of the invention] The object of the present invention is to improve the current state of the art, in particular to provide a multi-layer flexible packaging material which offers improved barrier properties and which can be recycled, to provide the use of such a multi-layer flexible packaging material for packaging dry food products, or at least to provide a useful alternative to existing packaging solutions in the art.

[0013] The present invention provides the following from the outer surface to the inner surface: A paper layer having a basis weight of 40 to 120 g / m2; an optional hydrophilic layer having a basis weight of at least 1.5 g / m; a barrier layer comprising a metallized material, aluminum oxide or silicon oxide, or a mixture thereof, and having a thickness in the range of 20 to 300 nm; A polymer layer having a basis weight of 1.0 to 15.0 g / m2; The above problem has been solved by preparing a multi-layer flexible packaging material comprising:

[0014] The present invention provides Water Vapor Transmission Rate (WVTR) and Oxygen Transmission Rate (OTR) test results that meet the requirements for packaging of dry food ingredients, as well as providing recycling opportunities.

[0015] The object of the present invention is therefore achieved by the subject matter of the independent claims. The dependent claims develop the inventive concept further.

[0016] The present invention further provides the use of the multi-layer flexible packaging material according to the present invention for packaging dry food, preferably confectionery, preferably chocolate products, cereal and / or nut-based bars, and / or biscuit or wafer products.

[0017] As used herein, the words "comprises," "comprising," and similar words should not be construed in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to." [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of the present invention.

[0019] [Mode for carrying out the invention] The present invention provides the following from the outer surface to the inner surface: A paper layer having a basis weight of 40 to 120 g / m2; an optional hydrophilic layer having a basis weight of at least 1.5 g / m; a barrier layer comprising a metallized material, aluminum oxide or silicon oxide, or a mixture thereof, and having a thickness in the range of 20 to 300 nm; A polymer layer having a basis weight of 1.0 to 15.0 g / m2; wherein the polymer layer comprises at least one plastic polymer.

[0020] In another embodiment, the order of the barrier layer and polymer layer from the outer surface to the inner surface is reversed.

[0021] For the purposes of the present invention, a packaging material shall be considered flexible if it is a material that can be bent without breaking.Further, for example, such a flexible material may be a material that can be bent by hand without breaking.Preferably, the multi-layer flexible packaging material according to the present invention may have a basis weight of 140 g / m2 or less, more preferably 120 g / m2 or less, more preferably 100 g / m2 or less, and less than 90 g / m2 or 80 g / m2.

[0022] The packaging material of the present invention is paper-based. A person skilled in the art can select an appropriate paper layer based on, for example, the product to be packaged, especially its size and weight, the packaging process, the distribution channel, the requirements for image and communication, and whether the paper material is used as a primary, secondary or tertiary packaging.

[0023] In a preferred embodiment, the ink is applied to the outer surface of the paper layer, the outer layer of the paper is uncoated, the outer layer is surface sized, or the outer layer is pigment coated. These paper surface treatments may be performed by methods known in the art.

[0024] The present invention includes a barrier layer comprising a metallized material, aluminum oxide or silicon oxide, or a mixture thereof. In a preferred embodiment, the mixture comprises individual layers of the material.

[0025] The metallization layer may be applied to the polymer film by physical vapor deposition. For example, the metallization layer may be applied by a vacuum deposition process. An example of a vacuum deposition process is described in Thin Solid Films, Vol. 666, November 30, 2018, pp. 6-14. Vacuum deposition is an evaporation process in which a metal in a solid phase passes into a gas phase and then returns to a solid phase, gradually building up the film thickness. Coatings produced by vacuum deposition have the advantage of good abrasion resistance, impact strength and temperature strength, as well as the ability to be deposited on complex surfaces. In a preferred embodiment, the metallization deposits aluminum.

[0026] In a preferred embodiment, the combination of the polymer membrane and barrier layer has a total thickness of 5.0 to 12.0 microns, preferably 6.0 to 10.0 microns, preferably 7.0 to 9.5 microns, preferably 7.5 to 8.5 microns.

[0027] In the present invention, the deposition method of aluminum oxide film and silicon dioxide film is not limited.Silicon dioxide film can be produced by various methods such as sol-gel, liquid phase deposition, sputtering, chemical vapor deposition (CVD), thermal oxidation, plasma enhanced chemical vapor deposition (PECVD), atmospheric pressure plasma deposition, and physical vapor deposition (PVD).PVD is one of the most established vacuum deposition techniques.PVD includes vacuum deposition, ion plating, and sputtering deposition.These techniques allow for better control of film thickness and ensure that the deposited film has good adhesion performance.

[0028] In the present invention, the deposition method of the aluminum oxide film is not limited. In one embodiment, the aluminum oxide layer may be deposited by vacuum deposition.

[0029] Those skilled in the art can appropriately adjust the thickness of the barrier layer depending on, for example, the intended shelf life, the packaged product, and the total thickness of the packaging material. In the multi-layer flexible packaging material according to the present invention, the barrier layer may have a thickness in the range of, for example, 20 to 300 nm, 30 to 275 nm, or 50 to 200 nm.

[0030] The optical density range of the barrier layer may preferably be in the range of 1.4 to 3.8, more preferably 1.4 to 3.5, which corresponds to a thickness of 30 to 200 nanometers.

[0031] In a preferred embodiment, the polymer layer comprises a polyolefin or polyester. Preferably, the polymer layer comprises a polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyhydroxyalkanoate, polylactic acid, and copolymers thereof, and mixtures thereof. In a preferred embodiment, the polymer layer comprises polypropylene.

[0032] In a highly preferred embodiment, the polymer layer is oriented, for example biaxially oriented.

[0033] In a highly preferred embodiment, the polymer is an oriented polyolefin or oriented polyethylene terephthalate, preferably oriented polypropylene (OPP).

[0034] In a highly preferred embodiment, the polymer is an extruded layer.Suitable extrusion methods are known in the art.For example, an oriented film (e.g., OPP) can be obtained by calendering a layer of molten polymer to obtain a film, and processing the film to obtain molecular orientation.

[0035] In a preferred embodiment, the polymer layer is not produced by a dispersion coating technique.

[0036] By using a combination of features of the present invention, it is possible to achieve the necessary barrier properties combined with recyclability and the use of commercially available materials that do not require more complex manufacturing processes such as dispersion coating.

[0037] In a preferred embodiment, the paper layer has a basis weight of 40 to 120 g / m2, preferably 50 to 100 g / m2, more preferably 60 to 90 g / m2 or 50 to 80 g / m2.

[0038] In a preferred embodiment, the polymer layer has a basis weight in the range of 1.5 to 12.0 g / m2, preferably 3.0 to 10.0 g / m2, more preferably 4.0 to 8.0 g / m2. In a highly preferred embodiment, the upper limit is 8.0 g / m2.

[0039] In a preferred embodiment, the hydrophilic layer has a basis weight in the range of 1.5 to 10.0 g / m2, preferably 2.0 to 8.0 g / m2, more preferably 3.0 to 6.0 g / m2.

[0040] In a preferred embodiment, the total basis weight of the packaging is in the range of 42.5-140 g / m2, preferably 50-120 g / m2, more preferably 60-100 g / m2 or 60-90 g / m2.

[0041] In a preferred embodiment, the paper layer has a basis weight of 60 to 90 g / m2, The hydrophilic layer has a basis weight in the range of 1.5 to 6.0 g / m2, the barrier layer comprises a metallization material; and The polymer layer has a basis weight in the range of 1.0 to 8.0 g / m2.

[0042] In a preferred embodiment, the multi-layer flexible packaging material further comprises a lamination adhesive layer between the paper layer or the hydrophilic layer (if present) and the barrier layer, preferably the adhesive layer having a basis weight not exceeding 3.5 g / m2, preferably between 0.5 g / m2 and 3.5 g / m2.

[0043] Suitable laminating adhesives are known to those skilled in the art and may be selected accordingly. The laminating adhesive applied between the paper layer / the hydrophilic layer on the paper layer and the barrier layer may be polyurethane.

[0044] A typical polyurethane adhesive contains some type of polyol or mixture, and some type of isocyanate or mixture. Other extenders and alternative crosslinking chemistries may also be present.

[0045] The multi-layer flexible packaging material of the present invention may be a food product packaging material. The packaging material may be, for example, a primary packaging material, a secondary packaging material, or a tertiary packaging material. When the multi-layer flexible packaging material is a food product packaging material, the primary food product packaging material may be a food product packaging material that is in direct contact with the actual food product. The secondary food product packaging material may be a food product packaging material that serves to secure one or more food products contained in the primary package. The secondary packaging material is typically used when multiple food products are provided to the consumer in a single container. The tertiary food product packaging material may be a food product packaging material that serves to protect one or more food products contained in the primary package and / or the primary and secondary packages during transportation.

[0046] To utilize the laminate of the present invention as a commercial material to contain food products, the following features may preferably be present: The structure may be printed with the desired graphic artwork with a specific surface ink on a pigment coated or uncoated paper surface suitable for the process. A cold or heat seal may be applied using a specific pattern that registers over the polymer side to allow for flow wrapping applications. A release lacquer may be applied on the printed surface to ensure that the cold seal does not permanently adhere to the printed surface when rolled up for delivery to the packaging location. The structure may be used in horizontal or vertical flow wrap machines to package food products as required.

[0047] In a preferred embodiment the packaging is a primary packaging for a food product, preferably a confectionery food product, preferably a chocolate product, a cereal and / or a nut bar, and / or a biscuit or wafer product.

[0048] In a preferred embodiment, the hydrophilic layer may comprise or consist of starch, pigment-starch or pigment-latex blends. The ratio of the pore volume to the total volume of a paper material is called the porosity of the paper material. For the purposes of the present invention, a paper layer shall be considered non-porous if it has a porosity of less than 40%, such as less than 30% or less than 20%, if its Gurley air permeability is less than 20 mL / min (Tappi T547). Thus, in one embodiment of the present invention, the paper layer is a non-porous paper layer.

[0049] It may be preferred that the paper layer has a low surface roughness. For example, the paper layer may have a Bendsten roughness of less than 100 mL / min. Bendsten roughness can be determined according to ISO 8791-2:2013, which is incorporated herein by reference.

[0050] The barrier properties of packaging materials are well known to those skilled in the art.For example, when the packaging material is a packaging material for food products, such good barrier properties are essential to maintain the safety and quality of the packaged food.Typically, such barrier properties include gas permeability, such as the permeability of O2, CO2, and N2; vapor permeability, such as the permeability of water vapor; liquid permeability, such as the permeability of water or oil; aroma permeability; and light permeability.

[0051] To ensure that the barrier layer is adequately protected against abrasion, for example, the barrier layer may be protected with a protective layer. Suitable protective layers are well known to those skilled in the art and may be selected from the group consisting of acrylic copolymers, polyesters, polyhydroxyalkanoates, natural and chemically modified starches, xylans and chemically modified xylans, polyvinylidene dichlorides, polyvinyl alcohols, ethyl-vinyl alcohols, vinyl acetates, ethyl-vinyl acetates, cellulose nitrates, polyolefins, silanes, polyurethanes, or combinations thereof. The use of such a protective layer has the advantage that the aluminum layer is stabilized and adequately protected against undesirable influences, maintaining its integrity and thus its positive impact on the barrier properties of the multilayer flexible packaging material of the present invention.

[0052] Coating paper materials, such as paper packaging materials, with a sealing layer, for example with a polymer dispersion, is well known in the art, for example to improve the barrier properties of the paper materials.Examples are described, for example, in Kimpimaki T., Savolainen AV (1997) Barrier dispersion coating of paper and board.In: Brander J., Thorn I. (eds) Surface Application of Paper Chemicals.Springer, Dordrecht.coated, paper materials.

[0053] For consumer information and design purposes, an ink layer may be applied on top of the paper layer. Again, it may be preferred if a primer is applied between the paper layer and the ink layer. Suitable primers are known to those skilled in the art and may be, for example, a polyurethane primer.

[0054] To provide a high-quality finish to the outer surface of the multi-layer flexible packaging material according to the present invention, an overprint varnish (OPV) can be applied to the surface of the ink layer. OPVs are well known to those skilled in the art and can be selected, for example, according to the intended purpose of the packaging material of the present invention. For example, the OPV can be selected from the group consisting of conventional offset letterpress varnishes, acrylic varnishes, UV varnishes, and gravure varnishes, which are representative of water- or solvent-based polymer formulations.

[0055] Thus, the multi-layer flexible packaging material of the present invention may further comprise a primer applied to the paper layer, an ink layer applied to the primer on the paper layer, and an overprint varnish layer applied to the ink layer.

[0056] The multi-layer flexible packaging material according to the present invention can have any thickness suitable for the packaging material. Those skilled in the art can determine the appropriate thickness. Typically, however, the packaging material should be as thin as possible while ensuring the safety and shelf life of the food product, especially when the packaging material is intended for use in packaging food products. For example, the multi-layer flexible packaging material according to the present invention can have a total thickness in the range of about 30 to 150 μm, 40 to 120 μm, or 50 to 100 μm.

[0057] Those skilled in the art can appropriately select the basis weight or thickness of the individual components of the multi-layer flexible packaging material according to the present invention.

[0058] In a preferred embodiment, the plastic layer is manufactured by extrusion. In a preferred embodiment, the plastic layer is surface treated using a corona (air plasma) process.

[0059] In a preferred embodiment, the present invention comprises: extruding and preferably orienting or subsequently orienting the plastic layer; subjecting the plastic layer to a corona surface treatment; applying a barrier layer by physical vapor deposition; Optionally applying a hydrophilic layer to the paper layer, applying an adhesive layer onto the paper layer or onto the hydrophilic layer (if present); and laminating a metallized film to an adhesive layer; The present invention provides a method for producing the material of the present invention, comprising:

[0060] Extrusion, corona surface treatment, physical vapor deposition, application and lamination of the hydrophilic and adhesive layers may be carried out by methods described above and / or known in the art.

[0061] In a preferred embodiment of the present invention, the multi-layer flexible packaging material according to the present invention may be recyclable. For example, it may be recyclable in the paper and cardboard stream. During recycling, the metallized polymer layer is separated from the rest of the packaging. Typically, the metallized polymer is separated from the rest of the packaging material during recycling in a hydrapulper. The low level of plastic material, and potentially the selection of plastic material, aids in recycling. Thus, the multi-layer flexible packaging material according to the present invention may be recyclable as paper and / or carton.

[0062] Due to these excellent barrier properties, the multi-layer flexible packaging material according to the present invention can be used to package food products. For the purposes of the present invention, the term "food" shall mean any substance intended for human consumption, whether processed, semi-processed or raw, in accordance with the Codex Alimentarius, and includes beverages, chewing gum, and any substance used in the manufacture, preparation or processing of "food", but does not include substances used solely as cosmetics or tobacco or drugs.

[0063] Notably, due to the excellent barrier properties, the multi-layer flexible packaging material according to the present invention can be used to package dry food products. Dry food products include powders and granules, such as powders and granules that are reconstituted with milk or water. Dry food products may have a moisture content of, for example, 5% or less.

[0064] Thus, the multi-layer flexible packaging material according to the invention can be used to package dry food products.The subject matter of the invention also extends to the use of the multi-layer flexible packaging material according to the invention for packaging dry food products.

[0065] A person skilled in the art will understand that all features of the invention disclosed herein can be freely combined. In particular, features described with respect to the product of the invention can be combined with features described with respect to the method of the invention, and vice versa. Furthermore, features described with respect to different embodiments of the invention may be combined.

[0066] Although the invention has been described by way of example, it should be understood that variations and modifications can be made without departing from the scope of the invention as defined in the claims.

[0067] Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred to herein. EXAMPLES

[0068] The following constructs were prepared as follows: Example 1 1) Complete coverage of peel-off lacquers applied by gravure method 2) Gravure printing with two-color design 3) Uncoated bleached kraft paper 70gsm, 91 micron 4) One-component solvent-free laminating adhesive 3.5gsm 5) A vacuum deposited aluminum barrier layer with an OD (optical density) of 2.1 6) 8 micron OPP corona treated film (7.1gsm) 7) Cold seal adhesive applied in a pattern by gravure technique

[0069] Example 2 1) Complete coverage of peel-off lacquers applied by gravure method 2) Gravure printing with two-color design 3) 65gsm uncoated bleached kraft paper with a 10gsm hydrophilic layer containing starch, pigments and binder, total 75gsm / 95 microns 4) 3.5gsm one-component solvent-free laminating adhesive applied over the hydrophilic layer 5) A vacuum deposited aluminum barrier layer with an OD (optical density) of 2.1 6) 8 micron OPP corona treated film (7.1gsm) 7) Cold seal adhesive applied in a pattern by gravure technique

[0070] The following tests were performed on the materials indicated below. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6]

Claims

1. A multilayer flexible packaging material comprising, in order from an outer surface to an inner surface, a paper layer having a basis weight of 40 to 120 g / m2, an optional hydrophilic layer having a basis weight of at least 1.5 g / m2, a barrier layer containing a metallized material, aluminum oxide or silicon oxide, or a mixture thereof, and having a thickness in the range of 20 to 300 nm, a polymer layer having a basis weight of 1.0 to 15.0 g / m2, wherein the polymer layer contains at least one plastic polymer.

2. The multilayer flexible packaging material according to claim 1, wherein the barrier layer is metallized aluminum.

3. The multilayer flexible packaging material according to claim 1 or 2, wherein the polymer layer contains a polyolefin or a polyester.

4. The multilayer flexible packaging material according to claim 1 or 2, wherein the polymer layer contains a polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyhydroxyalkanoate, polylactic acid, and copolymers thereof, and mixtures thereof.

5. The multilayer flexible packaging material according to claim 1 or 2, wherein the polymer layer is oriented, preferably biaxially oriented.

6. The multilayer flexible packaging material according to claim 1 or 2, wherein the paper layer has a basis weight in the range of 50 to 90 g / m2.

7. The multilayer flexible packaging material according to claim 1 or 2, wherein the hydrophilic layer is present and contains a material selected from the group consisting of starch, pigments, and binders, or mixtures thereof.

8. The multilayer flexible packaging material according to claim 1 or 2, wherein the basis weight of the polymer layer is in the range of 1.5 to 8.0 g / m2.

9. The multilayer flexible packaging material according to claim 1 or 2, further comprising a laminate adhesive layer between the paper layer and the barrier layer, preferably, the adhesive layer having a basis weight not exceeding 3.5 g / m2.

10. The multilayer flexible packaging material according to claim 1 or 2, wherein the barrier layer has a thickness in the range of 30 to 200 nm.

11. The paper layer has a basis weight of 60 to 100 g / m2, the hydrophilic layer has a basis weight in the range of 1.5 to 10.0 g / m2, the barrier layer contains a metallized material, and the polymer layer has a basis weight in the range of 1.0 to 8.0 g / m2, The multilayer flexible packaging material according to claim 1 or 2.

12. The multilayer flexible packaging material according to claim 1 or 2, wherein the barrier layer is supplied by physical vapor deposition.

13. The multilayer flexible packaging material according to claim 1 or 2, wherein the plastic polymer is treated to increase surface energy.

14. The multilayer flexible packaging material according to claim 1 or 2, wherein the material further comprises a cold seal or a heat seal on the inner surface of the material.

15. Use of the multilayer flexible packaging material according to claim 1 for packaging dry food.

16. A dry food product packaged in the multilayer flexible packaging material according to claim 1.

17. The use according to claim 15 or the packaged dry food product according to claim 16, wherein the dry food product is a confectionery product.

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