MULTI-LAYER PACKAGING MATERIAL, A PACKAGE AND A METHOD FOR MANUFACTURING A MUTI-LAYER PACKAGING MATERIAL

Abstract

The disclosure refers to a multi-layer packaging material comprising, from its outermost side to its innermost side, the following layers: a cellulose-based material layer having a grammage from 40 to 120 g/m.sup.2; a tie coating layer, the tie coating layer comprising a polymeric binder; an intermediate polymeric coating layer, the intermediate polymeric coating layer comprising a polyvinyl alcohol (PVA) polymer; a vacuum deposited metallization layer; and an inner polymeric coating layer, the inner polymeric coating layer comprising a material selected from a group comprising acrylic copolymers, polyesters, polyurethanes, polyester copolymers, polyurethane copolymers, vinyl acetates copolymers, chloride copolymers and any combination thereof.

Claims

1. A multi-layer packaging material comprising from, its outermost side to its innermost side, the following layers: a cellulose-based material layer having a grammage from 40 to 120 g/m.sup.2; a tie coating layer, the tie coating layer comprising a polymeric binder; an intermediate polymeric coating layer, the intermediate polymeric coating layer comprising a polyvinyl alcohol (PVA) polymer; a vacuum deposited metallization layer; and an inner polymeric coating layer, the inner polymeric layer comprising a polymer selected from: acrylic copolymers; polyesters; polyurethanes; polyester copolymers; polyurethane copolymers; vinyl acetate copolymers; vinyl chloride copolymers; and combinations thereof.

2. The multi-layer packaging material according to claim 1, wherein the tie coating layer comprises a polymeric binder selected from: a mixture of elastomeric polyurethane and nitrocellulose; a sulfopolyester; polyethylenimine (PEI); an acrylic polymer and combinations thereof.

3. The multi-layer packaging material according to claim 1, wherein the polyvinyl alcohol polymer of the intermediate polymeric coating layer is selected from: unmodified polyvinyl alcohol (PVA); ethylene vinyl alcohol (EVOH) copolymer; butanediol vinyl alcohol (BVOH) copolymer; and combinations thereof.

4. The multi-layer packaging material according to claim 1, comprising from one to three intermediate polymeric coating layers of polyvinyl alcohol polymer, preferably two, and more preferably three intermediate polymeric coating layers of polyvinyl alcohol polymer.

5. The multi-layer packaging material according to claim 1, comprising a primer coating layer between the cellulose-based material layer and the tie coating layer, the primer coating layer comprising a material selected from: heat-saleable acrylic emulsions; acrylic copolymers optionally comprising mineral fillings; polyesters; sulphopolyesters; vinyl acetate copolymers: vinyl chloride polymers; and combinations thereof.

6. The multi-layer packaging material according to claim 1, wherein the vacuum deposited metallization layer comprises aluminum, aluminum oxide and/or silicon oxide.

7. The multi-layer packaging material according to claim 1, wherein the vacuum deposited metallization layer has a thickness from 20 to 80 nm, and preferably from 30 to 60 nm.

8. The multi-layer packaging material according to claim 1, wherein the inner polymeric coating layer is obtainable from a polymeric dispersion, in particular is obtainable from a solvent-based and/or water-based polymeric dispersion.

9. The multi-layer packaging material according to claim 1, comprising one or two inner polymeric coating layers, preferably two inner polymeric coating layers.

10. The multi-layer packaging material according to claim 9, wherein: when there is one inner polymeric coating layer, the inner polymeric layer comprises a polymer selected from acrylic copolymers, and when there are two inner polymeric coating layers, a first layer comprises a polymer selected from acrylic copolymers and a second layer comprises a polymer selected from: polyesters; polyurethanes; polyester copolymers; polyurethane copolymers; vinyl acetate copolymers; chloride copolymers; and combinations thereof.

11. The multi-layer packaging material according to claim 1, wherein the surface of the cellulose-based material layer on which the tie coating layer is deposited has a Parker Print Surf (PPS) roughness value from 0.9 to 2.3 m.

12. The multi-layer packaging material according to claim 1, wherein the surface of the cellulose-based material layer opposite to the surface on which the tie coating layer is deposited has a PPS roughness value from 0.9 to 4.5 m.

13. The multi-layer packaging material according to claim 1, wherein the surface of the cellulose-based material layer on which the tie coating layer and is deposited has a COBB index from 2 to 20 g/m.sup.2, preferably from 2 to 6 g/m.sup.2.

14. A package for products comprising the multi-layer packaging material according to claim 1.

15. A method for manufacturing a mufti-layer packaging material, the method comprising the steps of: providing a cellulose-based material layer having a grammage from 40 to 120 g/m.sup.2; depositing, by a dispersion coating technique, a tie coating layer onto the cellulose-based material layer, the tie coating layer comprising a polymeric binder; depositing, by a dispersion coating technique, an intermediate polymeric coating layer onto the tie layer, the intermediate polymeric coating layer comprising a polyvinyl alcohol (PVA) polymer; depositing, by a vacuum deposition technique, a metallization layer onto the intermediate polymeric coating layer; and depositing, by a dispersion coating technique, an inner polymeric coating layer onto the metallization layer, the inner polymeric coating layer comprising a polymer selected from: acrylic copolymers; polyesters; polyurethanes; polyester copolymers; polyurethane copolymers; vinyl acetate copolymers; chloride copolymers; and combinations thereof.

16. The multi-layer packaging material according to claim 1, wherein the intermediate polymeric coating layer is present in an amount from 1 to 3.75 g/m.sup.2, preferably, between 1 to 3 g/m.sup.2.

17. The multi-layer packaging material according to claim 1, wherein the tie coating layer is present in an amount from 0.5 and 4 g/m.sup.2.

18. The multi-layer packaging material according to claim 1, wherein the inner polymeric coating layer is present in an amount from 1 to 4.5 g/m.sup.2.

19. A multi-layer packaging material comprising from, its outermost side to its innermost side, the following layers: a cellulose-based material layer having a grammage from 40 to 120 g/m.sup.2; a tie coating layer, the tie coating layer comprising a polymeric binder selected from: a mixture of elastomeric polyurethane and nitrocellulose; a sulfopolyester; polyethylenimine (PEI); an acrylic polymer and combinations thereof; an intermediate polymeric coating layer, the intermediate polymeric coating layer comprising a polyvinyl alcohol (PVA) polymer; a vacuum deposited metallization layer; and an inner polymeric coating layer, the inner polymeric layer comprising a polymer selected from: acrylic copolymers; polyesters; polyurethanes; polyester copolymers; polyurethane copolymers; vinyl acetate copolymers; vinyl chloride copolymers; and combinations thereof.

20. The multi-layer packaging material according to claim 19, comprising: three intermediate polymeric coating layers, and two inner polymeric coating layers, wherein a first layer comprises a polymer selected from acrylic copolymers and a second layer comprises a polymer selected from: polyesters; polyurethanes; polyester copolymers; polyurethane copolymers; vinyl acetate copolymers; chloride copolymers; and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] To complete the description and in order to provide for a better understanding of the disclosure, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an example of the disclosure, which should not be interpreted as restricting the scope of the disclosure, but just as an example of how the disclosure can be carried out.

[0055] The drawings comprise the following figures:

[0056] FIG. 1 shows a schematic representation of a multi-layer packaging material, according to an embodiment of the disclosure.

[0057] FIG. 2 shows a schematic representation of the multi-layer packaging material of FIG. 1 but including three intermediate polymeric coating layers, according to another embodiment of the disclosure.

[0058] FIG. 3 shows a schematic representation of the multi-layer packaging material of FIG. 2 but including two inner polymeric coating layers, according to another embodiment of the disclosure.

[0059] FIG. 4 shows a schematic representation of the multi-layer packaging material of FIG. 3 but including a primer coating layer, according to another embodiment of the disclosure.

[0060] FIG. 5 shows a flow diagram of a method for manufacturing the multi-layer packaging material, according to an embodiment of the disclosure.

DESCRIPTION OF EXAMPLES

[0061] FIG. 1 shows a schematic representation of a multi-layer packaging material 100, according to an embodiment of the disclosure. It should be understood that the multi-layer packaging material 100 depicted in FIG. 1 may include additional materials and/or components and that some of the materials and/or components described herein may be removed and/or modified without departing from a scope of the multi-layer packaging material 100.

[0062] The multi-layer packaging material 100 comprises a cellulose-based material layer 101, for example, a paper-based layer, having a grammage of, e.g., 40 g/m2. This paper-based layer 101 provides a good balance between strength and flexibility and may comprise a latex-based coating layer (not shown in this figure) on both of its surfaces. The latex-based coating of the inner surface of the paper-based layer (the surface on which the subsequent tie coating layer is to be deposited) has a greater amount of latex than the outer surface (printing surface of the paper-based layer). These latex-based layers improve the smoothness and flexibility of both surfaces. The paper-based layer also may have a tensile strength 7.5 Kg/15 mm.

[0063] The inner surface of the paper-based material 101 layer has a PPS roughness value of 1.5 m and a COBB index of 3.5 g/m2 and the outer surface of the paper-based layer 101 has a PPS roughness value of 2.3 m.

[0064] There may be a printing coating layer (not shown in this figure) on top of the outer surface of the paper-based layer 101. An overprint varnish coating layer (not shown in this figure) may be also deposited on top of the printing coating layer to protect it.

[0065] The multi-layer packaging material 100 comprises one tie coating layer 102 made of elastomeric polyurethane combined with nitrocellulose. The elastomeric polyurethane combined with nitrocellulose is a polymeric binder that improves the adherence of the subsequent intermediate polymeric coating layer 103 to the paper-based layer 101 and protects it from vapor and moisture that could pass through the paper-based layer 101 from the outside (i.e., from the printing surface of the paper-based layer 101 towards the vacuum deposited metallization layer 104) affecting and degrading the barrier properties (e.g., increasing the OTR and/or the WVTR) of the intermediate polymeric coating layer 103. The elastomeric polyurethane combined with nitrocellulose also provides a high flexibility and mechanical resistance to the multi-layer packaging material 100.

[0066] The one single intermediate polymeric coating layer 103 is made of a polyvinyl alcohol (PVA) polymer. Examples of these PVA polymers are, e.g., PVA copolymers such as Kuraray Exceval, Kuraray Poval or Michem Flex B1002 or Nichigo G-Polymer, among many other possible PVA polymers. This single intermediate polymeric coating layer 103 may have been deposited in a range from 1 to 2.5 g/m2, preferably 1 g/m2, to ensure a regular and homogenous thickness of the layer.

[0067] The multi-layer packaging material 100 further comprises a vacuum deposited metallization layer of aluminum with a thickness of 40 nm. In this case, the vacuum deposited aluminum layer may be passivated with a layer of aluminum oxide of about 10-15 nm that is deposited over said aluminum layer and protects it from corrosion. Aluminum, in contact with air, may naturally become passivated, thus generating his aluminum oxide coating.

[0068] The multi-layer packaging material 100 also comprises one single inner polymeric coating 105 layer made of an acrylic copolymer (e.g., Carbobond 3005 or Rhobarrv 135) or a combination of more than one acrylic copolymer. Examples of these acrylic copolymers may be ethyl acrylate copolymer, ethylene acrylic acid copolymer or methyl acrylate copolymer, among many others. Acrylic copolymers adhere properly to the vacuum deposited metallization layer 104 and provide flexibility and easy film formation at not very high temperatures. Avoiding these high temperatures during the deposition of the inner polymeric coating layer 105 avoids damaging the vacuum deposited metallization layer 104 that may degrade its barrier properties.

[0069] The multi-layer packaging material 100 of FIG. 1 presents the following oxygen and moisture barriers:

TABLE-US-00001 OTR WVTR 25 cm.sup.3/m.sup.2/day (23 C., 50% RH) 16 g/m.sup.2/day (38 C., 90% RH)

[0070] The OTR has been measured at a temperature of 23 C. and with a relative humidity of 50%, while the WVTR has been measure at a temperature of 38 C. and with a relative humidity (RH) of 90%. Thus, the multi-layer packaging material herein disclosed presents improved OTR and WVTR values than those provided by other multi-layer packaging materials of the state of the art.

[0071] FIG. 2 shows a schematic representation of the multi-layer packaging material 100 of FIG. 1 but including three intermediate polymeric coating layers 103 instead one single intermediate polymeric coating layer 103, according to another embodiment of the disclosure. These three intermediate polymeric coating layers 103 may have the same thickness or a different thickness. For example, each of these layers may have been deposited in an amount of 1 g/m2. By depositing 3 layers of PVA polymer 103 (e.g., PVA copolymers) on top of the tie coating layer 102 the number of pin holes in the paper-based layer 101 is significantly reduced increasing its smoothness. Besides, the surface planarization and barrier properties are improved since the first PVA polymer layer 103a provides surface planarization, the second PVA polymer layer increases planarization and provides oxygen barrier, and the third PVA polymer layer increases surface planarization and oxygen and moisture barriers. Additionally, since it is required less amount of PVA polymer for depositing three thinner PVA polymer layers than to depositing one single thicker PVA polymer layer in order to reach the required surface planarization and the required barrier properties, a significant amount of PVA polymer is saved with the corresponding economic saving. Finally, PVA polymer often comprise a low content of dry solids, which makes them easier to be applied as a thinner layer, on top of another coating, rather than as a thick layer deposited on top of the cellulose-based material layer itself.

[0072] The multi-layer packaging material 100 of FIG. 2 presents the following oxygen and moisture barriers:

TABLE-US-00002 OTR WVTR 0.6 cm.sup.3/m.sup.2/day (23 C., 50% RH) 1.8 g/m.sup.2/day (38 C., 90% RH)

[0073] The OTR has been measured at a temperature of 23 C. and with a relative humidity of 50%, while the WVTR has been measure at a temperature of 38 C. and with a relative humidity (RH) of 90%. Thus, the multi-layer packaging material herein disclosed presents improved OTR and WVTR values than those provided by other multi-layer packaging materials of the state of the art.

[0074] FIG. 3 shows a schematic representation of a multi-layer packaging material 100 of FIG. 2 but including two inner polymeric coating layers 105, according to another embodiment of the disclosure.

[0075] In such embodiment, these two inner polymeric coating layers 105 are combined such that each layer is made of at least one material of the following list: acrylic copolymers, polyesters, polyurethanes, polyester copolymers, polyurethane copolymers, vinyl acetates copolymers and chloride copolymers. In this particular embodiment, the first layer 105a is preferably made of an acrylic copolymer, a polyester, a combination of acrylic copolymers or a combination of polyesters that, as previously mentioned, present a good adherence to the vacuum deposited metallization layer 104 but may present some tendency to generate blocking. To minimize the problem of blocking, the second layer 105b may preferably be obtainable from a solvent-based dispersion, such as solvent-based dispersions of an acrylic copolymer, a polyester, a combination of acrylic copolymers or a combination of polyesters, among other materials. In some other examples, the first layer 105a may be of a polyester or a combination of polyesters while the second layer 105b may be of a chloride copolymer or a combination of chloride copolymers. Other combinations from the mentioned list could be possible. For example, the first layer may have been deposited in an amount from 1 to 3.5 g/m2, preferably about 2.5 g/m2, and the second layer may have been deposited in an amount from 0.5 to 2 g/m2, preferably about 1 g/m2.

[0076] The multi-layer packaging material 100 of FIG. 3 presents the following oxygen and moisture barriers:

TABLE-US-00003 OTR WVTR 0.6 cm.sup.3/m.sup.2/day (23 C., 50% RH) 2 g/m.sup.2/day (38 C., 90% RH)

[0077] The OTR has been measured at a temperature of 23 C. and with a relative humidity of 50%, while the WVTR has been measure at a temperature of 38 C. and with a relative humidity (RH) of 90%. Thus, the multi-layer packaging material herein disclosed presents improved OTR and WVTR values than those provided by other multi-layer packaging materials of the state of the art.

[0078] FIG. 4 shows a schematic representation of the multi-layer packaging material 100 of FIG. 3 but including a primer coating layer 106, according to another embodiment of the disclosure. This primer coating layer may be made of an acrylic copolymer with mineral fillings.

[0079] The primer coating layer 106 is located between the paper-based layer 101 and the tie coating layer 102 and it is made of an acrylic copolymer such as Carbobond 3005F that is a formaldehyde acrylic copolymer, an acrylic emulsion such as Carboset GA7424 that is an acrylic copolymer emulsion, among many others. Alternatively, this primer coating layer 106 may be made of other materials such as acrylic copolymers with mineral fillings, acrylic copolymers without mineral fillings, polyesters, sulfopolyesters, vinyl acetate copolymers, vinyl chloride and vinyl acetate copolymers and any combination thereof or any combination of the cited materials with an acrylic emulsions or acrylic copolymers.

[0080] The multi-layer packaging material 100 of FIG. 4 presents the following oxygen and moisture barriers:

TABLE-US-00004 OTR WVTR 0.5 cm.sup.3/m.sup.2/day (23 C., 50% RH) 4 g/m.sup.2/day (38 C., 90% RH)

[0081] The OTR has been measured at a temperature of 23 C. and with a relative humidity of 50%, while the WVTR has been measure at a temperature of 38 C. and with a relative humidity (RH) of 90%. Thus, the multi-layer packaging material herein disclosed presents improved OTR and WVTR values than those provided by other multi-layer packaging materials of the state of the art.

[0082] FIG. 5 shows a flow diagram of a method 200 for manufacturing the multi-layer packaging material, according to an embodiment of the disclosure.

[0083] At step 201 of the method 200, a cellulose-based material layer, for example, a paper-based layer, having a grammage comprised in the range from 40 to 120 g/m2, preferably in the range from 50 to 110 g/m2, and more preferably in the range from 60 to 90 g/m2, is provided. This cellulose-based material layer will be selected so as to balance the mechanical resistance (tensile strength, elasticity, flexibility, etc.) and surface properties of the layer.

[0084] At step 202 of the method 200, a tie coating layer is deposited, by a dispersion coating technique, onto the cellulose-based material layer. This tie coating layer comprises a polymeric binder. Preferably there will be one single tie coating layer although in some implementations there may be more than one tie coating layer to improve the adherence of the intermediate polymeric coating layers to the cellulose-based material layer.

[0085] At step 203 of the method 200, an intermediate polymeric coating layer is deposited by a dispersion coating technique, onto the tie coating layer. The intermediate polymeric coating layer comprises a polyvinyl alcohol (PVA) polymer (e.g., a PVA copolymer). Preferably, three intermediate polymeric coating layers will be deposited onto the tie coating layer.

[0086] At step 204 of the method 200, a metallization layer is deposited, by a vacuum deposition technique, onto the intermediate polymeric coating layer. This metallization layer will be preferably made of aluminum, aluminum oxide and/or silicon oxide. For example, the vacuum deposition technique may be a physical vapor deposition process.

[0087] At step 205 of the method 200, an inner polymeric coating layer is deposited, by a dispersion coating technique, onto the metallization layer, the inner polymeric coating layer comprising a material selected from a group comprising acrylic copolymers, polyesters, polyurethanes, polyester copolymers, polyurethane copolymers, vinyl acetates copolymers, chloride copolymers and any combination thereof. Preferably, the inner polymeric coating layer will be made of a solvent-based material to avoid blocking.

[0088] In some embodiments, a primer coating layer is deposited, by a dispersion coating technique, between the cellulose-based material layer and the tie coating layer. The primer coating layer may be made of a material selected from a group comprising: acrylic polymers (e.g., obtainable from acrylic emulsions), optionally comprising mineral fillings; polyesters; sulfopolyesters; vinyl acetate copolymers; vinyl chloride; and combinations thereof. The primer coating layer improves the planarization by smoothening the inner surface of the cellulose-based material layer and filling some of its porous. It also provides barrier properties to moisture and oils.

[0089] The tie coating layer, the primer layer, the intermediate polymeric coating layer and the inner polymeric coating layer are preferably deposited using dispersion coating techniques such as, e.g., forward and reverse gravure coating, bar coating and curtain coating, amongothers. In some embodiments, all these layers are deposited using the same dispersion coating technique, while in some other embodiments, they may be deposited using different dispersion coating techniques. Thanks to the use of polymer dispersion coating, the overall thickness of polymer material in the whole multi-layer packaging material is low when compared to the thickness of cellulose-based material layer. Thus, the low thickness of the dispersion coating of polymer avoids high cohesion and high adhesion of the polymer to the cellulose, and therefore makes it possible for the multi-layer packaging material to be recycled using conventional recycling paper techniques.

[0090] The overall thickness of the multi-layer packaging material herein may be adjusted by a person skilled in the art based on the intended purpose of the packaging material.

[0091] The multi-layer packaging material herein disclosed may have any thickness suitable for packaging materials. A person skilled in the art will be able to determine an appropriate thickness. Typically, however, if the packaging material is intended for use in packaging food products, the packaging material should be as thin as possible, while still ensuring safety and shelf life of the food product. For example, for food packaging it may have an overall thickness in the range of about 35 to 110 m.