Packaging materials

Abstract

A compostable and environmentally sustainable multilayer packaging material comprising a paper layer (1) and barrier layers (3, 5) provided on one or both sides of the paper layer, The aforementioned barrier layer Polymer components selected from the group consisting of polyhydroxyalkanoate polymers or copolymers, proteins selected from milk-derived proteins, fungal-derived proteins or leguminous plant-derived proteins, polylactic acid, polybutylene succinate or polybutylene succinate copolymers, thermoplastic blends of starch and aliphatic polyesters, chitosan, carrageenan, pectin, alginates, lipids, and mixtures thereof, in an amount of 51-99% by weight, preferably 90-10% by weight, more preferably 95-98% by weight, as well as A filler selected from the group consisting of layered double hydroxides, nanocellulose, silicates, clay, preferably layered silicates, and mixtures thereof, in an amount of 49-1% by weight, preferably 1-10% by weight, more preferably 2-5% by weight. Includes, A multilayer packaging material whose weight percentage is based on 100 parts by weight of the total polymer component and filler.

Description

[Technical Field]

[0001] The present invention relates to a multilayer paper-based packaging material comprising a paper layer and at least one barrier coating layer, particularly for use in packaging confectionery products. [Background technology]

[0002] In food packaging, barrier coatings are necessary and widely used to preserve the sensory properties of food. Barrier properties in packaging materials, particularly flexible packaging materials for confectionery products, include low permeability to oxygen (O2) and water vapor, low permeability to volatile aromatic compounds, and low light transmittance. Specifically for packaging materials for confectionery products, an oxygen permeability (OTR) of 100 cc / m³ measured under conditions of 23°C and 40-50% relative humidity is required. 2 Less than 24 hours, or preferably 0.1 cc / m³ 2 • Less than 24 hours, and under conditions of water vapor transmission rate (WVTR) of 38°C and 90% relative humidity, 10 g / m² 2 Less than 24 hours, preferably 0.1 g / m 2 It is desirable to achieve less than 24 hours. (WVTR) should be 10 or less, preferably 0.1 g / m³ 2 • It is preferable that it be 24 hours or less.

[0003] Currently, solutions used to obtain the barrier properties required for confectionery packaging include lamination with metallized polyolefin films (PE, PP, PET) or the use of a barrier coating layer containing clay and polymer components.

[0004] However, paper-based packaging materials need to be environmentally sustainable, compostable, and / or easily recyclable. Furthermore, there is a need for packaging materials that possess the necessary barrier properties and environmental sustainability, as well as mechanical properties that enable use in modern high-speed packaging machinery such as flow pack / flow wrap machines and twist-wrap machines. Particularly desirable mechanical properties include tensile strength and puncture resistance, which can also be expressed as burst strength based on the T403 analytical method.

[0005] The object of the present invention is to provide a multilayer paper-based packaging material that meets the above requirements. [Overview of the project]

[0006] In view of the above objectives, the subject of the present invention is a multilayer packaging material as defined in the appended claims.

[0007] The dependent claims relate to preferred embodiments of the present invention.

[0008] Further features and advantages of the packaging material of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. The drawings are provided as non-limiting examples. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the arrangement of several embodiments (a) to (g) of the packaging material. Here, the surface layer of the multilayer structure has heat-sealing properties. [Figure 2] This is a schematic cross-sectional view showing the arrangements of several embodiments (a) to (g). Here, the multilayer structure includes a surface layer having cold sealing properties. [Figure 3] These are schematic cross-sectional views of several specific embodiments (a) to (e). [Figure 4] These are schematic cross-sectional views of several exemplary embodiments (a) to (e). [Modes for carrying out the invention]

[0010] The present invention relates to a packaging material having a multilayer structure, comprising a paper-like layer 1 that generally constitutes the core layer of the packaging material, and at least one barrier layer 3, 5 made of or obtained from sustainable materials and / or natural materials that are compostable and suitable for providing packaging that achieves a higher score in recyclability certification tests.

[0011] The term "paper layer" or "paper-based layer" refers to a layer primarily composed of cellulose fibers, including cardboard and corrugated cardboard.

[0012] In this specification, expressions relating to the use of materials “containing” cellulose or cellulose fibers, or materials “essentially consisting of cellulose or cellulose fibers,” do not preclude the presence of additives. For example, these may include additives of types conventionally used in papermaking, or functional additives used to obtain a barrier effect against gases or liquids, or to improve mechanical properties. For example, such terms include cases where the material contains 70–99.9% by weight of cellulose fibers on an anhydrous basis, preferably 90–99.9% by weight, and 0.1–30% by weight of additives on an anhydrous basis, preferably 0.1–10% by weight.

[0013] Suitable additives include starch, alkyl ketene dimers, resins, and inert fillers such as clay.

[0014] Regenerated cellulose fibers can be used, preferably those that are completely free of MOSH and MOAH.

[0015] Preferably, the paper-based layer 1 has a basis weight (weight) of 35 to 120 g / m². 2 The range is less than 120-400 g / m² and is flexible, and as a result, multilayer packaging materials are also flexible. However, the scope of the present invention is limited to paper-based layers of 120-400 g / m². 2 This also includes packaging materials that are sheets having a certain weight and are suitable for being molded by heat and pressure to provide molded packaging.

[0016] The barrier coating layer applied to one or both sides of the substrate is 51 to 99% by weight, preferably 90 to 10% by weight, more preferably 95 to 98% by weight, of a polyhydroxyalkanoate polymer (PHA) or copolymer, a milk-derived protein, or a protein material selected from plant-derived proteins such as leguminous plants or fungi, or gelatin, polylactic acid, polybutylene succinate or its copolymer, polybutylene succinate copolymer, polybutylene adipate terephthalate (PBAT), a thermoplastic blend of starch and aliphatic polyester, chitosan, carrageenan, pectin, alginate, lipid, polyacrylic polymer, polyurethane and mixtures thereof, and 49 to 1% by weight, preferably 1 to 10% by weight, more preferably 2 to 5% by weight, of a filler selected from the group consisting of layered double hydroxides, nanocellulose, silicates and clays, preferably layered silicates (or phyllosilicates), and mixtures thereof preferably contains The weight percentages are based on a total of 100 parts by weight of the polymer component and the filler

[0017] As used herein, the term "barrier layer" refers to a layer that provides a barrier against water vapor, oxygen, aroma, or carbon dioxide. Further, it may provide grease resistance or moisture resistance, and / or water absorption resistance. The barrier layer described herein has also been found to improve the mechanical properties of the material (e.g., tensile strength, tear strength, impact strength, or burst strength). In some embodiments, the disclosed barrier layer imparts to the packaging material the ability to retain deformation during twisting, cold forming properties, and thermoformability while maintaining the original material properties of the substrate.

[0018] In one embodiment of the present invention, the packaging material has barrier layers 3 on both sides of a paper layer, and the barrier layers are formed on the paper layer by extrusion coating or lamination (FIGS. 1(e), 1(f) and 1(g)).

[0019] In another embodiment, the barrier layer shown as 5 in the drawings is obtained by applying and drying a lacquer containing one or more of the aforementioned polymer components and the previously disclosed fillers in water or a solvent medium (Figures 1(a), 1(b), and 1(d)).

[0020] In one embodiment, the barrier layer 5 obtained from the lacquer is formed on both sides of the paper layer (Figure 1(c)).

[0021] In another embodiment, the multilayer structure may comprise a barrier coating layer 3 (extruded or laminated onto a paper layer) and a barrier layer 5 obtained from lacquer on the opposite side of the paper layer (Figure 1(d)).

[0022] In another embodiment, the multilayer structure may include the barrier layer 5 obtained from lacquer as described above, on top of the barrier layer 3 that is extruded coated or laminated to the paper layer (Figure 1(f)), or, if the barrier layer 3 is extruded coated or laminated on both sides of the paper layer, the barrier coating layer 5 obtained from lacquer may be placed on both extruded coated or laminated layers (Figure 1(g)).

[0023] The polymer components used in the barrier layer of the present invention include the following (biodegradable) materials: (a) Polyhydroxyalkanoate (PHA) polymers or copolymers, preferably medium-chain PHAs having 6 to 14 carbon atoms in monomer units, which are soft, elastomeric, and have a low melting point (typically 50 to 170°C, preferably 100 to 160°C). However, the term PHA also includes short-chain and long-chain PHAs and / or mixtures thereof.

[0024] Examples of poly(hydroxyalkanoate) polyesters usable within the scope of the present invention include, but are not limited to, poly(3-hydroxybutyrate) (3HB), poly(4-hydroxybutyrate) (4HB), and poly(3-hydroxyvaleric acid) (3HV). Particularly preferred are copolymers of hydroxybutyrate and hydroxyvaleric acid or hydroxyhexanoate, having a melting point of 120 to 160°C, and including poly(3-hydroxybutyrate-co-3-hydroxyvaleric acid) (PHBV), poly(hydroxybutyrate-co-hydroxyhexanoic acid) (PHBH), and poly(3-hydroxy-co-4-hydroxybutyrate). PHBH and PHBV are preferred.

[0025] The materials also include PHA blends containing PHA (preferably poly(3-hydroxybutyrate-co-4-hydroxybutyrate)), as well as biodegradable polymers selected from cellulose, starch or starch acetate, polylactic acid, and polycaprolactone.

[0026] (b) Polybutylene succinate (PBS) and its copolymers; preferred copolymers of PBS include: Examples include poly(1,4-butylene succinate-co-adipate), poly(1,4-butylene succinate-co-1,4-butylene azelate), poly(1,4-butylene succinate-co-1,4-butylene terephthalate), poly(1,4-butylene succinate-co-1,4-butylene sebaciate-co-1,4-butylene terephthalate), poly(1,4-butylene adipate-co-1,4-butylene succinate-co-1,4-butylene terephthalate), and poly(1,4-butylene azilate-co-1,4-butylene succinate-co-1,4-butylene terephthalate). Polyhydroxyalkanoate-polybutylene succinate copolymers are also included.

[0027] (c) Proteins selected from milk-derived or legume-derived proteins (such as peas and lentils), fungal-derived proteins, and gelatin; (d) Pectin, alginate, lipid. These can be used optionally in combination with the above proteinaceous substances and / or polysaccharides.

[0028] Suitable polymer components include: (e) Also included are polylactic acid, thermoplastic blends of starch and aliphatic polyesters, chitosan, and carrageenan.

[0029] The fillers used in the barrier coating layer of the present invention are selected from layered double hydroxides (LDH), nanocellulose, natural and synthetic layered silicates, and mixtures thereof. Preferred LDHs include hydrotalcite and hydrotalcite-like minerals.

[0030] Preferred nanocellulose materials include cellulose nanofibers (CNF), nanocrystalline cellulose (CNC), or bacterial nanocellulose (BNC). The term nanocellulose also includes nanocellulose in which the CH2OH groups are modified, for example, by esterification, amidation, or etherification.

[0031] Preferred layered silicates include montmorillonite bentonite, hectorite, smectite, and mica.

[0032] The fillers employed usually have the following characteristics: One direction: 1 - 40 μm The other direction: 1 nm - 2 μm Aspect ratio: 1.20 - 20,000 and have a particle size.

[0033] The barrier coating layer is usually applied in the range of 0.5 - 10 g / m by weight 2 , preferably 1 - 5 g / m 2 , more preferably 1 - 3 g / m 2 .

[0034] In a preferred embodiment of the present invention, the laminated or extruded coated barrier layer 3 is heat-sealable, in which case the polymer component is preferably polyhydroxyalkanoate (as described above), polybutylene succinate, polybutylene adipate terephthalate, or polylactic acid, in combination with a filler preferably selected from layered double hydroxides and nanocellulose.

[0035] Furthermore, in embodiments that enable obtaining a heat-sealable barrier layer which is the surface layer of a multilayer material, the polymer component is selected from the group consisting of protein materials, preferably milk, fungi, pea-derived proteins, and gelatin.

[0036] If the barrier layer is not heat-sealable, a heat-sealable layer (or heat-sealable layer) 7 obtained from a heat-sealable lacquer may be applied as an outer layer (Figure 1(c)). The polymer of the heat-sealable lacquer is the same as the low-melting-point polymer disclosed for the barrier layer, but this layer 7 does not contain fillers.

[0037] The multilayer packaging material may further include one or more primer layers (not shown) applied to one or both sides of the paper layer between the surface of the paper layer and the barrier coating layer. The primer layers may be used to improve the spreading and adhesion of the subsequent coating.

[0038] Primers for the present invention may be selected from the group consisting of acrylic acid copolymers, polyesters, polyhydroxyalkanoates, natural and chemically modified starches, xylan and chemically modified xylans, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, vinyl acetate, ethylene vinyl acetate, cellulose nitrate, silane, polyurethane, or combinations thereof.

[0039] If the multilayer packaging material of the present invention does not include a heat-sealable surface layer, a cold-sealable layer 9 may be optionally applied as a surface coating to a limited area of ​​the packaging material.

[0040] The cold-sealable layer (or cold-sealable layer) is typically prepared from latex or a non-allergenic latex suspension. Alternatively, aqueous acrylic or synthetic latex systems may be used. The cold-sealable layer may contain additives or pigments (e.g., 0.1–5% by weight relative to the resin).

[0041] Typically, the multilayer structure includes a surface printing layer 11, which is applied using conventional printing inks and conventional printing techniques such as offset printing and gravure printing.

[0042] The printed layer may be further coated with a protective varnish. The protective varnish is applied to protect the ink and coating from damage during the packaging's lifespan. Damage can occur due to moisture, solvents, mechanical stress, or abrasion. The protective varnish is applied using the same technique as the printing ink.

[0043] Protective varnishes typically contain a resin, additives / stabilizers / modifiers, and a solvent. Suitable solvents include water, ethanol, and ethyl acetate. The resin can be selected from nitrocellulose or other modified celluloses, acrylic polymers, and polyurethanes.

[0044] In particular, in embodiments in which the multilayer structure includes a cold-sealable surface layer, the release coating layer 13 may be applied to the surface of the multilayer structure opposite to the cold-sealable layer to cover the printed layer in order to impart release properties.

[0045] Release varnishes are applied to facilitate the unwinding of print reels and to prevent cold seals from adhering to other parts of the packaging structure. The release varnishes under consideration have the same components as protective varnishes but include additional lubricants or release agents. The lubricants or release agents may be selected from silicone-containing compounds, fatty acids or fatty acid esters, vegetable oils or other plant-derived oils, carnauba wax or other bio-based waxes, and paraffin waxes.

[0046] A preferred embodiment of the present invention is that the barrier layer is heat-sealable, and 50-85% by weight, preferably 50-70% by weight, of heat-sealable polyhydroalkanoate (PHA), 20-40% by weight of polybutylene succinate (PBS) or polylactic acid (PLA) or a mixture thereof, and The material comprises a multilayer packaging material containing 0.5 to 3% by weight of nanocellulose (preferably CNC) and optionally 9.5% by weight or less of conventional additives, with the total weight percentage being 100%.

[0047] In a more preferred embodiment, the barrier coating layer is heat-sealable and is laminated or extruded coated, the barrier layer is 50-60% by weight heat-sealable PHA, 20-30% by weight of PBS or PLA, or a mixture thereof, 0.5 to 10% by weight of dispersed layered double hydroxide, preferably hydrotalcite or a hydrotalcite-like mineral, and optionally, It contains 5 to 9.5% by weight of conventional additives, the sum of which is 100% by weight. In the above embodiment, PHA may be replaced with a protein-based material as described above.

[0048] Conventional additives refer to additives that have traditionally been included in the aforementioned plastic materials.

[0049] In a further embodiment of the present invention, the multilayer structure includes an extruded coating layer 15 made of a PHA polymer or copolymer, which is applied as a coating directly onto the paper layer to reduce the porosity of the paper (Figures 3(c) and 3(d)), or onto a barrier layer 3 or 5 (Figure 3(d)), or as a primer layer between the paper layer and the barrier layer 3 or 5 (Figure 3(e)). [Examples]

[0050] This multilayer packaging material is further disclosed by the following Examples 1-5 relating to flexible materials. (Examples 1 and 2) The multilayer structures of Examples 1 and 2 are shown in Figures 3(a) and 3(b), along with the weight of each layer. A PHA coating formulation containing CNC (or nanocellulose) is applied to a paper substrate (inner surface: Figure 3(a), outer surface: Figure 3(b)). The PHA is preferably PHBH, and the nanocellulose concentration in the PHA polymer is 2%.

[0051] A coating layer obtained from a heat-sealable lacquer containing biodegradable polyester (PHBH) is applied as the surface layer on the inner side.

[0052] (Example 3) The multilayer structure of Example 3 is shown in Figure 3(c) along with the weight of each layer. The structure and composition are the same as in Example 2, but the layer from the heat-sealable lacquer is replaced with a PHA 15 coating layer or laminated layer. The PHA layer improves barrier properties and reduces the porosity of the paper. To ensure heat sealability, the use of a heat-sealable PHA such as PHBH is preferred.

[0053] (Example 4) The multilayer structure of Example 4 is shown in Figure 3(d) along with the weight of each layer. The structure and composition are the same as in Example 3, but an additional extruded PHA layer is formed on top of the PHA and CNC barrier layers. This additional PHA layer protects the barrier layer, reduces peeling, improves resistance to breakage from slight bending, and increases resistance to flow in the packaging line.

[0054] (Example 5) The multilayer structure of Example 5 is shown in Figure 3(e) along with the weight of each layer. The structure and composition are the same as in Example 4, but a PHA extruded coating layer 15 was used as a primer between the paper layer 1 and the PHA and nanocellulose barrier layers, so its weight is 15 g / m². 2 From 5g / m 2 This makes it possible to reduce it to a certain extent.

[0055] The multilayer structures of Examples 1-5 had an oxygen permeability (OTR) of 0.5 cc / m³ measured at 23°C and 40-50% relative humidity. 2 • Water vapor transmission rate (WVTR) of 20 g / m² measured under conditions of less than 24 hours, 38°C, and 90% relative humidity. 2 It is possible to achieve this in less than 24 hours.

[0056] (Examples 6-10) Examples 6 to 10 shown in Figures 4(a) to 4(e) relate to multilayer structures corresponding to Examples 1 to 5, with paper layers of 120 to 400 g / m². 2 Because it is a sheet with a certain weight, it is suitable for molding packaging materials.

[0057] (Examples 6 and 7) WVTR: 50~15g / m 2 24 hours (38°C and 90% RH), OTR: 20~<10 cc / m 2 • 24 hours (measured at 23°C and 40-50% RH).

[0058] (Example 8) Water vapor transmission rate (WVTR): 25-10 g / m² under conditions of 38°C and 90% relative humidity. 2 24 hours, Oxygen permeability rate (OTR): 15-5 cc / m³ under conditions of 23°C and 40-50% relative humidity. 2 24 hours.

[0059] (Example 9) WVTR: 25-<10g / m² at 38℃ and 90%RH 2 24 hours, OTR: 10 to <1 cc / m³ at 23°C and 40-50% RH 2 24 hours.

[0060] (Example 10) WVTR: 25-<10 g / m² at 38°C and 90% RH 2 24 hours, OTR: 1 to <1 cc / m³ at 23°C and 40-50% RH 2 24 hours. [Explanation of symbols]

[0061] 1 … Paper layer (base material) 3. Extruded coating or laminated barrier layer on paper layer 1. 5. A barrier layer obtained by applying lacquer to cover the paper layer 1 or the barrier layer 3. 7. Any layer obtained by applying a heat-sealable lacquer. 9. Continuous or discontinuous cold-sealing layer (also indicated as CS in drawings) 11… Continuous or discontinuous printing layers 13... Any layer obtained from release varnish 15. Extruded coating layer made of PHA.

Claims

1. The device comprises a paper layer (1) and barrier layers (3, 5) provided on one or both sides of the paper layer. The aforementioned barrier layer 51 to 99% by weight, preferably 90 to 10% by weight, more preferably 95 to 98% by weight, of protein materials selected from polyhydroxyalkanoate polymers or copolymers, milk-derived proteins, fungal-derived proteins or leguminous plant-derived proteins, or polymer components selected from the group consisting of gelatin, polylactic acid, polybutylene succinate or polybutylene succinate copolymer, polybutylene adipate terephthalate, thermoplastic blends of starch and aliphatic polyesters, chitosan, carrageenan, pectin, alginates, lipids, and mixtures thereof, and A filler selected from the group consisting of layered double hydroxides, nanocellulose, silicates, and clay, preferably layered silicates, and mixtures thereof, in an amount of 49 to 1% by weight, preferably 1 to 10% by weight, more preferably 2 to 5% by weight. Includes, Multilayer packaging material, where the weight percentage is based on 100 parts by weight of the total polymer component and filler.

2. The multilayer packaging material according to claim 1, wherein the barrier layer (3) is extruded and coated or laminated onto the paper layer (1).

3. The multilayer packaging material according to claim 1 or 2, wherein the barrier layer is provided on both sides of the paper layer (1).

4. The multilayer packaging material according to claim 1, wherein the barrier layer (5) is obtained by applying and drying a lacquer containing the polymer component and filler in water or a solvent medium.

5. The multilayer packaging material according to claim 4, wherein the barrier layer (5) obtained from lacquer is provided on both sides of the paper layer (1).

6. The multilayer packaging material according to claim 1, wherein the paper layer (1) has a barrier layer (3) according to claim 2 on one side and a barrier layer (5) according to claim 4 on the other side.

7. The multilayer packaging material according to claim 3, comprising an additional barrier layer (5) according to claim 4 on one or both sides of a laminated or extruded barrier coating layer.

8. The multilayer packaging material according to claim 3 or 7, wherein the laminated or extruded coated barrier layer (3) is heat-sealable, and the polymer component is selected from the group consisting of polyhydroxyalkanoate polymers or copolymers, polybutylene succinate, polybutylene adipate terephthalate (PBAT), polylactic acid, and mixtures thereof, and the filler is selected from layered double hydroxides and nanocellulose.

9. The multilayer packaging material according to claim 3 or 7, wherein the laminated or extruded coated barrier layer (3) is heat-sealable, the polymer component is selected from the group consisting of protein materials selected from milk-derived, fungal-derived, and pea-derived proteins, gelatin, and mixtures thereof, and the filler is selected from the group consisting of hydrotalcite, nanocellulose, silicates, clay, and mixtures thereof.

10. The multilayer packaging material according to claim 8, wherein the barrier layer comprises 50 to 85% by weight, preferably 50 to 70% by weight, of polyhydroxyalkanoate (PHA), 20 to 40% by weight of polybutylene succinate (PBS) or polylactic acid and mixtures thereof, and 0.5 to 3% by weight of nanocellulose, preferably CNC, and optionally 9.5% by weight or less of conventional additives, the sum of the percentages being 100% by weight.

11. The multilayer packaging material according to claim 8, wherein the laminated or extruded coated barrier layer contains 50 to 60% by weight of polyhydroxyalkanoate (PHA), 20 to 30% by weight of polybutylene succinate (PBS) or polylactic acid and mixtures thereof, 0.5 to 10% by weight of dispersed hydrotalcite or hydrotalcite-like mineral, and optionally 5 to 9.5% by weight of conventional additives, the sum of the percentages being 100% by weight.

12. The multilayer packaging material according to any one of claims 1 to 11, further comprising a primer layer ((3), (5)) applied to one or both sides of the paper layer between the surface of the paper layer and the barrier coating layer.

13. A multilayer packaging material according to any one of claims 1 to 12, further comprising an external ink printing layer (11).

14. A multilayer packaging material according to any one of claims 1 to 13, comprising a heat-sealable layer (7) as a surface layer.

15. The multilayer packaging material according to claim 14, wherein the heat-sealable layer (7) comprises a polymer component selected from the group consisting of polyhydroxyalkanoate, polybutylene succinate, and polybutylene adipate terephthalate, and does not contain a filler.

16. A multilayer packaging material according to any one of claims 1 to 13, comprising a cold-sealable layer (9) prepared from a latex suspension as a surface layer, and optionally comprising additives or pigments.

17. The multilayer packaging material according to claim 16, comprising a coating of release varnish as a surface layer.

18. The aforementioned paper layer has a weight of 35 to 120 g / m². ２ The film is less than 120-400 g / m². ２ A multilayer packaging material according to any one of claims 1 to 17, which is a sheet of the same material.

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