Barrier laminate

Abstract

A barrier laminate comprising a substrate layer (1), a connection layer (2) comprising an electrospun fiber network, and a non-fiber-based sealing layer (3), adjacent to the connection layer (2) and facing the outside of the laminate.

Description

[0001] BARRIER LAMINATE

[0002] The present invention relates to a barrier laminate. The invention further relates to a packaging product comprising the barrier laminate. The invention further relates to a method to manufacture the barrier laminate.

[0003] Background of the invention

[0004] Consumer goods, such for example food products including frozen confectionary, liquid and dry bouillon, soup, sauce products; savoury snack products, instant meals, but also soap bars, laundry detergent, etc, are typically packaged before they are used by the consumer. Besides marketing purposes, depending on the consumer product, the packaging provides structure to the product and / or keeps it in place, and protects the product against external influences that may affect the quality, including light, water, and air, which results in the presence of several barrier materials that are included in a packaging material, depending on the product need. In addition, the consumer product itself may affect the packaging material, because of for example ingredients like water, fat, salts, corrosive alkaloids etc., and the packaging material typically may need to be resistant against such influences to ensure proper protection of the packaged product. For this reason, packaging materials for consumer products typically are laminates of different materials, such as different polymer materials (plastics), and metal, such as aluminum.

[0005] With increasing emphasis on environmentally friendlier packaging materials, the use of non- petroleum-based substrate layers, such as paper, which function e.g. as a structural base of a barrier laminate, gained interest. The substrate layer, such as paper, obviously is typically thin, to allow high flexibility, for example during packaging processes and in packaging lines. In the case of paper, paper provides to a certain extent texture to a packaged consumer product, its barrier properties for external influences such as water are limited, and it can be easily damaged upon contact with fat or water from the packaged consumer product. In the art, laminates comprising paper and petroleum-based polymers are found as a solution to provide barrier properties to the paper material.

[0006] Barrier laminates can be used for example to produce flexible packaging, such as pouches or doy packs. To do this, the barrier laminate is typically folded and sealed on itself to form a baglike structure. Alternatively, individual pieces of barrier laminate can be sealed to each other, result in a bag-like structure, such as a pouch or a doy pack. After filling of the packaging, the packaging may be closed in a procedure that involves a further sealing step. To enable such sealing steps during manufacturing of the packaging and closing thereof, barrier laminates comprise a sealing layer. This is a layer in the barrier laminate that connects to another layer upon pressure or heat, most preferably upon applying heat.

[0007] It was realized, that the one of the complications observed in the context of petroleum-free barrier laminates was the integrity of the seals in a packaging produced from the flexible barrier laminate. For optimal protection of the consumer product, the sealed areas in a packaging, typically located at the borders of the packaging, should not open or leak during storage and transport. In particular when the substrate layer in the laminate is paper-based, integrity of seals is a challenge but of paramount importance.

[0008] EP 3907078 A relates to a biodegradable packaging comprising a low-cost, tear-resistant thermoformable structural layer and optionally a self-adhesive gas and vapor barrier layer, a self- adhesive active layer and / or a layer for direct contact with the product, all being based on biodegradable polymers.

[0009] A need therefore was recognized for a flexible barrier laminate, as much as possible and more preferably, completely free from petroleum-based layers, and which comprises a substrate layer and a sealing layer, which laminate allows for manufacturing of packaging products for consumer products, and which provides proper integrity during use (transport and storage) and tight connection of the sealing layer to the substate layer.

[0010] Summary of the invention

[0011] Surprisingly, this objective could be met by the present invention, which relates in a first aspect to a barrier laminate comprising:

[0012] • A substrate layer (1),

[0013] • A connection layer (2) comprises an electrospun fiber network,

[0014] • A non-fiber-based sealing layer (3), adjacent to the connection layer (2) and facing the outside of the laminate, wherein the connection layer (2) has a thickness of from 1 to 30 micrometer, preferably of from 5 to 10 micrometer, wherein the sealing layer (3) preferably has a thickness of from 5 to 65 pm, more preferably from 20 to 60 pm, more preferably from 20 to 50 pm, more preferably from 30 to 45 pm, and most preferably from 30 to 40 pm and wherein none of the substrate layer (1), connection layer (2) and sealing layer (3) comprises petroleum-sourced material.

[0015] In a second aspect, the present invention relates to a process to provide a packaging laminate according to the invention, the process comprising the steps of: a) Providing a substrate layer (1). b) Depositing fibers using electrospinning to form a fiber network, c) Applying a sealing layer (3) over the fiber network, d) Laminating the substrate layer, the deposited fiber network and sealing layer, to result in a barrier laminate according to the invention.

[0016] In a third aspect, the present invention relates to a packaging product to package a consumer product, the packaging product comprising the barrier laminate according to the invention. Preferably, the packaging product is a wrapper or sachet.

[0017] In a fourth aspect, the invention relates to a method to manufacture a packaging product of the third aspect of the invention.

[0018] In a fifth aspect, the present invention relates to the use of an electrospun fiber layer, positioned between a substrate layer and a sealing layer to enhance the connection between the substrate layer and the sealing layer, wherein the resulting barrier laminate is according to the present invention.

[0019] Barrier laminates comprising a substrate and an electrospun layer have been described in the art. Also, barrier laminates comprising a sealing layer are known. The inventors are not aware of any barrier laminate that comprises a sealing layer, and wherein enhanced inter-layer adhesion has been recognized after introducing an connection layer that was electrospun.

[0020] Description of the Drawing

[0021] Figure 1 shows a schematic diagram of the process of electrospinning of fibres.

[0022] Detailed description

[0023] The barrier laminate of the present invention comprises three layers. It includes a substrate layer (1), a non-fiber-based sealing layer (3), and a connection layer (2) comprising a fiber network, positioned between the substrate layer and the sealing layer. It was found that the connection layer being electrospun resulted in significantly enhanced inter layer sealing properties, wherein the thickness of the individual layers is of relevance. The advantage achieved in this manner is to provide a barrier laminate with reduced risk for detachment of the individual layers forming the barrier laminate. Detachment of layers in a barrier laminate may in particularly form a risk in cellulose fiber-based barrier laminates, in particular when the barrier laminate is used in packaging products containing e.g. consumer goods and therefore exposed to forces e.g. during cutting the material or tearing it during opening of such packaging products. It further allows the barrier laminate to not rely on further barrier laminate materials that are sourced from petroleum. Such materials are preferably absent from the substrate layer, connection layer and sealing layer and more preferably are absent from the barrier laminate.

[0024] The barrier laminate is flexible. It can typically be easily bended without damaging the integrity. The laminate is not rigid. The barrier laminate is typically a laminate comprising from 3 to 7, preferably 3 to 6, more preferably 4 to 6 layers, most preferably 5 or 6 layers. It is preferred, that the barrier laminate consists of 3 layers at the side of barrier laminate where the sealing layer (3) is located (typically facing the packaged product when in use), being the substrate layer (1), the connection layer (2) and the sealing layer (3). At the other side of the substrate layer (typically facing the outside world when in use) can preferably be one or two other layers deposited, such as an ink layer (4) and an over varnish layer (5).

[0025] Substrate layer

[0026] The barrier laminate comprises a substrate layer (1). The substrate layer preferably is a cellulose fiber based layer. More preferably, the substrate layer is paper-based or cardboard based, most preferably paper based and most preferably is paper. The flexible barrier laminate comprises preferably a total of one, or a total of two, but preferably a total of one layer of paper. Paper typically comprises cellulose fibers.

[0027] The cellulose fiber-based layer preferably comprises paper, or more preferably is paper with a grammage of between 40 and 100 gram / m2, preferably of 50 to 90 gram / m2, even more preferably from 50 to 80 gram / m2and most preferably of 50 to 70 gram / m2. This provides suitable rigidity to the final packaging product to contain a consumer product, such as for example a wrapper or sachet, whereas it can be suitably transported in a packaging line, e.g. over rollers.

[0028] In view of the aim of providing a barrier laminate with less impact on the environment, it may be preferred, that paper is present in an amount of more than 80 wt%, more preferably more than 85 wt%, based on the total weight of the barrier laminate. Preferably paper fibers constitute more than 80 wt%, more preferably more than 85 wt%, based on the total weight of the barrier laminate. It may be preferred, that the amount of total polymer, for example the amount of plastic, is below 20 wt%, preferably below 15 wt%, based on the weight of the barrier laminate. It can be for example from 9 to 20 wt%, more preferred from 11 to 15 wt%. A paper content of more than 80 wt% is typically considered to meet the criteria for recyclability in many countries.

[0029] Alternatively, the barrier layer can be polymer-based. Polymers are not petroleum sourced polymers. Apart from environmental impact, several petroleum-sourced polymers result in a substrate layer that is brittle or rigid, e.g. polypropylene or polyethylene terephthalate, and found less suitable for purposes of a providing a flexible barrier laminate. Suitable polymers that could be used for the substrate layer are preferably selected from the group consisting of polyhydroxyalkanoate (PHA), polyvinyl alcohol, polylactic acid and mixtures thereof. Most preferred from this group are PHA based substrate layers. They are not sourced from petroleum sources (different from polyvinyl alcohol, and compost relatively easily (different from polylactic acid which cannot be home-composted). PHA preferably comprises poly(3-hydroxybutyrate-co- 3-hydroxyvalerate) (PHBV), or poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH). In the case the substrate layer is polymer-based, it is preferred that it comprises poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV), or poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), more preferably is poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), or poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH). A cellulose fiber-based, preferably a paperbased, substrate layer is however more preferred than a polymer-based substrate layer and preferably the substrate layer is a cellulose fiber based, preferably a paper-based, substrate layer.

[0030] Connection layer

[0031] A connection layer (2) is present between the substrate layer and the sealing layer (3). The connection layer is preferably directly deposited on the substrate layer (1). It is preferred, that the connection layer (2) is the only barrier layer, which is present at the side of the substrate layer (1) where the connection layer is applied. Preferably the connection layer and the sealing layers are the only layers at the side of the substrate layer where the connection layer is present. Preferably there is only one connection layer comprising a fiber network. It may be preferred, that no further barrier layer is present at the side of the substrate layer where the sealing layer (3) is not positioned (i.e. the environment facing side).

[0032] The connection layer comprises a fiber network. The fiber network is electrospun. The fibers in the fiber network preferably have a diameter (shortest dimension) of between 250 and 1000 nm, more preferably of between 300 and 700 nm and most preferably of between 300 and 500 nm. Fiber diameter can be checked, for example, by microscopy, such as (electron) microscopy, as known in the art.

[0033] The connection layer preferably has a density of from 1 to 30 g / m2, preferably from 2 to 20 g / m2, even more preferably from 2 to 12 g / m2. A density from 10 to 20 g / m2may be preferred. The thickness of the connection layer is from 1 to 18 micrometers, preferably 4 to 15, and more preferably from 5 to 10 micrometers. Such width can conveniently be checked with methods common in the art, as known to the skilled person, such as microscopy, or caliper.

[0034] The materials in the connection layer preferably are not petroleum-sourced. The barrier layer may comprise filler particles, e.g. to improve barrier properties. The connection layer preferably comprises one or more materials selected from the group consisting of polyhydroxyalkanoates (PHA), fibroin proteins, pro-lamines, chitin polysaccharides, phenolic polymers, and mixtures thereof. Preferred polyhydroxyalkanoates in the context of the invention are selected from the group consisting of polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and mixtures thereof. A preferred fibroin protein in the context of the invention is silk. A preferred pro-lamine in the context of the invention is zein. A preferred chitin polysaccharide in the context of the invention is chitin from shellfish and chitin from mushrooms. A preferred phenolic polymer in the context of the invention is lignin. More preferably, the connection layer comprises PHA, fibroin protein or prolamine. Even more preferably, the connection layer comprises one or more selected from the group consisting of polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), silk, zein and mixtures thereof. PHB may result in relatively higher layer thickness, which may not be preferred. It could be preferred that no PHB layer is present. Most preferably, the connection layer comprises one or more selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), silk, zein and mixtures thereof.

[0035] Electrospinning

[0036] The connection layer typically is an electrospun layer of deposited fibers. Electrospinning is a known deposition technique to deposit fibers on a substrate. It is generally used in pharmaceutical applications, e.g. to manufacture filters. General deposition techniques involve heating of the material to be deposited, e.g. to melt it. It was found, that in the context of the present invention, several non-petroleum sourced, natural, materials cannot be melted and accordingly are hard to deposit, and could be deposited using electrospinning, in the form of fibers. In this manner, barrier laminates can be produced with enhanced inter layer seal strength, while allowing the barrier laminate to be biodegradable. In the context of cellulose fiber-based, in particular paper-based, barrier laminates, electrospinning allows for deposition of the materials without negatively affecting the quality of the cellulose-based fiber layer: Whereas traditionally coatings are applied to a substrate using dispersion coating, which may wilt the substrate when absorbing the solvents used in dispersion coating, and which may damage the cellulose fiber-based substrate, during electrospinning, fiber are deposited while any solvent evaporates in the deposition process, leaving the substrate unaffected.

[0037] Electrospinning is a fiber manufacture technique which is known in the art, which produces nonwoven fiber mats. This technique utilises electric charge to draw a charged jet of polymer solution, and deposit a dry fibre on a negatively charged collector. Polymers such as polyhydroxyalkanoates (PHA), and proteins such as silk fibroin and zein protein can be electrospun. These polymers are dissolved in a solvent and loaded into a syringe, and when electrospun, the solvent evaporates leaving behind a dry fiber. The process is essentially depicted in Figure 1. The electrospinning parameters can be adjusted, as known in the art, including the distance to the collector, the voltage and the flow rate, which will allow adjustment of the fiber diameter. In the context of the present invention, a diameter of between 250 and 1000 nm, but in particular, preferably 300-700 microns, proved optimal, in particular in the context of a cellulose- fiber based, preferably paper-based substrate layer, since this diameter resulted in optimal barrier properties to accommodate for the inherent pores present in this substrate material.

[0038] Also, the thickness of the connection layer can be adjusted by increasing the spinning time of the fibres, allowing a higher fibre density to be deposited and is preferably not too thin, but also not too thick. A preferred deposition thickness of the fiber layer is between 10 and 55 microns, preferably of between 15 and 25 microns. This is not necessarily the thickness as observed in the final packaging laminate of the present invention, since a third layer will be deposited on this electrospun connection layer, which preferably involves compression, and results in the final thickness of the connection layer as mentioned earlier herein. In the context of the invention, a ‘random’ orientation of the fibres upon deposition is preferred (e.g. vs. an ’aligned’ deposition), for optimal seal effect.

[0039] The process of electrospinning will be further elaborated when describing the manufacturing method of the invention. Sealing

[0040] The barrier laminate comprises a sealing layer. The sealing layer is preferably a heat seal layer. The heat seal layer is preferably a layer that is not made from petroleum-sourced material.

[0041] Preferably, the sealing layer (3) comprises a material selected from the group consisting of polyhydroxyalkanoates (PHA), heat-sealable cellulose, polymers from biomass, and protein films. Preferably, the sealing layer comprises PHA, more preferably is PHA.

[0042] The PHA preferably is selected from the group consisting of preferably polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3- hydroxy hexanoate) (PHBH), and mixtures thereof. Heat-sealable cellulose is known in the art and can preferably be regenerated cellulose (e.g. Natureflex™). Polymers from biomass used for heat sealing are known in the art and preferably comprise polysaccharide, such as chitosan, starch or mixtures thereof, preferably starch or starch-based coating. Protein used for heat sealing purposes preferably comprises zein protein. It is preferred, that the sealing layer comprises, preferably consists of, a material selected from the group consisting of preferably polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), regenerated cellulose, polysaccharide, such as chitosan or starch, zein and mixtures thereof. More preferably, the sealing layer comprises, even more preferably consists of a material selected from the group consisting of polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and mixtures thereof. Even more preferably, the sealing layer comprises, more preferably consists of one or more of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and mixtures thereof.

[0043] The sealing layer preferably has a thickness of from 5 to 65 pm, preferably from 20 to 60 micrometer, more preferably from 20 to 50 pm, more preferably from 30 to 45 micrometer, most preferably from 30 to 40 pm. The density of the sealing layer preferably is from 10 to 50 g / cm2, preferably from 20 to 50 g / cm2, most preferably from 30 to 40 g / cm2.

[0044] The sealing layer (3) is in direct connection with the connection layer (2). Additional layers

[0045] It is preferred, that the substrate layer (1) is in direct contact with the connection layer (2), and the latter is preferably directly deposited on the substrate layer, for optimal sealing strength. Alternatively, it could be preferred that a pre-coat layer is present between the substrate layer (1) and the connection layer (2), but this is not required. If present, the precoat layer is preferably from a material that is not petroleum-sourced. A preferred precoat layer could be selected from the group consisting of starch, zein, protein, cellulose, clay and mixtures thereof. A clay-based precoat layer is most preferred. A precoat layer may preferably have a thickness of between 1 and 5 gsm, preferable 1.5 to 4 gsm. The pre-coat can suitably be applied using dispersion or extrusion coating, as known to the skilled person. It may be preferred, that no pre-coat layer is present between the substrate layer and the barrier layer, e.g. for a more optimal result.

[0046] Apart from the substrate layer, the connection layer and the sealing layer the barrier laminate of the present invention may further comprise an ink layer (4). The barrier laminate is used to protect a consumer product (7). In this respect, it also provides a communication function to the consumers who will buy the consumer products, typically via information printed on the substrate, e.g. paper, including information regarding ingredients, appealing artwork and advertisement etc. The barrier laminate therefore preferably comprises a layer of ink (4). This layer of ink is preferably connected to the substrate layer (1). It may be preferred that there is a primer applied between paper layer and ink layer. Appropriate primers are known to the person skilled in the art. It may be preferred, that the primer is non-petroleum based. The layer of ink is preferably in direct connection with the substrate layer (1) and typically faces the outside of the barrier laminate (e.g. when applied in a consumer packaging), i.e. the site opposite to the site of the barrier laminate that will be in contact with the consumer product to be packaged. I.e. typically, opposite of the side of the paper where the sealing layer (3) is located.

[0047] For example, to protect the ink layer, the barrier laminate preferably comprises a protection layer (5) on top of the ink layer. The protection layer is typically facing the outside world. It is typically located opposite to the product-facing site of the laminate (e.g. when applied in a consumer packaging) and opposite to the side of the laminate where the sealing layer is located. The protection layer (5) may be an over-print varnish (OPV), OPVs are well-known to the person skilled in the art and the chosen varnish depends on the intended use of the barrier laminate of the present invention. For example, the OPV may be selected from the group consisting of conventional offset letterpress varnishes, acrylic varnishes, UV varnishes, and gravure varnishes. OPVs can be water-based polymer formulations or solvent-based polymer formulations. The protection layer (5) typically is deposited directly on the ink layer (4), It is preferably in direct contact with the ink layer. The protection layer faces an outside of the barrier laminate, typically the site opposite to the site that is intended to face or faces the consumer product to be packaged, i.e. typically opposite of the side of the paper where the sealing layer is located. The ink layer and the protection layer (e.g. OPV) do not count as ‘barrier layer’ in the meaning used in this description.

[0048] The thickness of the protection layer (5), is preferably between 0.5 and 3 microns, preferably of between 1 and 2 microns.

[0049] It is preferred, that at the ‘product side’, i.e. the side where the sealing layer is located, a total of three layers is present, including the substrate layer. Accordingly, preferably no further layer is present between the sealing layer and the substrate layer, apart from the connection layer. Preferably, no further layer, is present on top of the sealing layer (3). It may be preferred that only one barrier layer, i.e. the barrier layer comprising, preferably consisting of the electrospun fibers, is present in the barrier laminate of the invention. Preferably no second or further barrier layer is present on the side of the substrate layer that faces the environment (5), i.e. the side opposite to that where the barrier layer (2) is present. Preferably, no metal layer or metal oxide layer is present in the barrier laminate. It may be preferred that no plasma treatment is present of any of the materials used in the barrier laminate.

[0050] Packaging product and packaged consumer product

[0051] In a further aspect, the invention relates to a flexible packaging product for packaging a consumer product, the packaging product comprising the flexible barrier laminate of the invention. The packaging product comprises flexible barrier laminate of the invention that has been sealed, wherein the pieces of barrier laminate have been sealed together, or wherein a piece of barrier laminate has been folded and sealed together, wherein respective sealing layers (3) are facing each other. Typically, the borders of the resulting packaging product, such as a sachet orwrapper, are sealed together, as the skilled person understands. Sealing is preferably carried out by heat sealing.

[0052] The packaging product may be in the form of a flow-wrap, pillow bag, gusseted bag, stand-up pouch, diaper bag, tetrahedral bag, quattro seal bag or sachet. The packaging product may contain a consumer product. Typical consumer products that can be packaged using packaging products with flexible barrier laminate of the invention are preferably selected from the group consisting of frozen confectionary, bouillon, soup, sauces, coffee, tea, supplements, vitamins, electrolyte powders, laundry detergents, skin cleansing products, skin care products and haircare products. In particular, it is preferred that the packaging product is a sachet or a wrapper. A wrapper can be used for example to wrap a soap bar, a frozen confectionary product or a condiment like a bouillon or seasoning concentrate.

[0053] The invention further relates to a packaged consumer product, wherein the consumer product is packaged in a packaging product comprising the flexible barrier laminate of the invention.

[0054] Method of manufacturing

[0055] In a further aspect, the present invention relates to a method to manufacture the barrier laminate of the present invention. The process comprises the steps of: a) Providing a substrate layer (1). b) Depositing fibers using electrospinning, to form a fiber network, c) Applying a sealing layer (3) over the fiber network, d) Laminating the deposited fiber network and sealing layer, to result in a barrier laminate according to the invention.

[0056] Preferences as described in the context of the first aspect of the invention, apply to the second and other aspects of the invention, mutatis mutandis.

[0057] The barrier laminate can be produced in a conventional electro spinning apparatus, such as for example the EF500 electrospinning system from Ske Research Equipment. In step a) of the process of the invention, a substrate layer is provided. With reference to Figure 1 , a substrate layer as described above in relation to the first aspect of the invention, is typically positioned on the collector, like a collection plate, of the apparatus, which is typically negatively charged. It can be advantageous, that low air pressure (a “vacuum”) is applied under the substrate layer, for optimal result. The material to be spun, like polymer or protein, is dissolved in a solvent. The solvent is then loaded in the apparatus, e.g. in a syringe.

[0058] The materials described in the first aspect of the invention are spun to form a fiber network, which forms a layer, typically on top of the substrate layer. Solvents to dissolve the materials such as polymers to be spun are known in the art. For example, polyhydroxyalkanoates, like PHBV or PHBH) are preferably dissolved in a mixture of 1 ,1 ,1 ,3,3,3-Hexafluoro-2-propanol (HFIP), DMSO and water (8:1 :1), wherein the PHA is suitably dissolved at preferably 50 °C under stirring, e.g. overnight, after which dimethyl sulfoxide and water are added at RT under stirring. Zein dissolves at RT in ethanol / DI water (80% / 20%), under stirring. Fibroin, like silk fibroin, dissolves in formic acid.

[0059] The solution comprising the material to form fibers (polymer, polysaccharide, protein) is transported to a charged jet with typically a Taylor cone. Electric charge draws the charged jet with polymer solution and deposits fiber on the collector. In this manner non-woven fiber mats results and are deposited on the substrate layer. The fibers can be deposited using a needle based electrospinning system, or (preferably) a needleless electrospinning system.

[0060] As known in the art, the diameter of the fibers can be suitably adjusted by altering the electrospinning parameters including voltage, flow rate, distance to the collector and the speed of collector rotation. The thickness of the resulting fiber mat can be adjusted by increasing the fibre deposition time to collect a thicker mat, the longer the fibres spin, the higher the fibre density is deposited.

[0061] The fiber network deposited in step b) of the process, has preferably a thickness of between 10 and 60 microns, preferably of between 12 and 35 microns. A mat of PHA, in particular of PHB, PHBV or PHBH, preferably PHBV or PHBH, preferably is deposited to a thickness of between 10 and 30 microns, preferably of between 15 and 25 microns. A mat of fibroin, e.g. silk fibroin, is preferably deposited to a thickness of between 10 and 30 microns, preferably of between 15 and 20 microns. A mat of pro-lamines, preferably zein, is preferably deposited to a thickness of between 10 and 30 microns, preferably of between 10 and 15 microns. A mat of polysaccharides, preferably chitin polysaccharides, including chitosan, is preferably deposited to a thickness of between 10 and 60 microns, preferably of between 12 and 35 microns. A mat of phenolic polymers (e.g lignin), is preferably deposited to a thickness of between 10 and 60 microns, preferably of between 12 and 35 microns.

[0062] In a preferred situation, the electrospinning in step b) involves electro spinning, preferably electro- blow-spinning. Electro-blow spinning is a technique as such known in the art. In the present context, it has the advantage, that the throughput is enhanced compared to traditional electrospinning. The fiber coating can be deposited at higher speed and more fibers can be deposited in a shorter period of time.

[0063] It may be preferred, that at least two materials are electrospun at the same time in step b). For example, it may be preferred, to spin a mixture of silk and PHBV. It was found, that a mixture of silk and PHBV proved to be optimal for reducing the laminate water vapour permeability. In step c) of the process, a sealing layer is applied over the connection layer. The sealing layer faces the outside of the laminate, i.e. no further layer is deposited over it. When the barrier laminate is applied in a packaging product, typically the sealing layer faces the inside of the packaging product, i.e. the product-facing side of the packaging product.

[0064] During step c) or after application of the sealing layer in step c) a lamination step d) is carried out. In the lamination step, the composite resulting after step c) and typically comprising the substrate layer, the connection layer and the sealing layer is laminated to form a barrier laminate.

[0065] Lamination typically involves applying pressure and a heat treatment. Lamination is preferably carried out in a heat laminator.

[0066] Pressure is preferably applied to the sealing layer. The sealing layer is typically positioned on top of the connection layer in this situation. Pressure is applied preferably when the connection layer has not been cooled down completely, preferably when the connection layer is still hot, ensuring it still in the melting phase to ensure tackiness to encourage the sealing layer to adhere. The pressure is suitably applied via a hot press. Pressure is suitably applied with a force of between 1 and 10 tonnes, preferably of between 3 and 5 tonnes. Pressure application results in the compression of the connection layer. It is preferred, that pressure is applied to result in a density of the connection layer of from 1 to 50 g / m2, preferably 1 to 30 g / m2, preferably from 5 to 15 g / m2. The resulting thickness of the connection layer is preferably of from 1 to 30 micrometers, preferably 4 to 15, and more preferably from 5 to 10 micrometers. Pressure is preferably applied under heating, preferably at a temperature of between 140 and 160 °C Heat is typically applied by the pressure plates within the hot press. Heat is preferably applied to both the top and bottom of the laminate structure.

[0067] In the case an ink layer (4) is applied as part of the barrier laminate, it is typically applied after step c), preferably to the substrate layer, as described earlier. A protection layer (5) may be applied over the ink layer, after application thereof.

[0068] Accordingly, the present invention further relates to a barrier laminate manufactured by the process of the invention. The invention further relates to a method to manufacture a packaging product according to the invention, the method comprising the steps of: a) Providing a substrate layer (1). b) Depositing fibers using electrospinning, to form a fiber network, c) Applying a sealing layer (3) over the fiber network, d) Laminating the resulting composite comprising the substrate layer, fiber network and sealing layer, to form a barrier laminate; e) Forming a packaging product comprising the barrier laminate; f) Sealing the barrier laminate by connecting parts of the barrier laminate wherein the respective sealing layers become sealed together; to form a packaging product.

[0069] It is preferred, that the method further comprises the step of filling the packaging product resulting from step e) with consumer product.

[0070] Sealing in step f) is typically carried out using heat sealing. The sealing conditions used are preferably in a temperature range of 120-200 °C. Typically, pressure is applied during the sealing step, preferably at a pressure range of 2 to 4 bar. The sealing time is preferably 0.2 to 1 seconds.

[0071] Use

[0072] Using an electrospun connection layer located between a substrate layer and a sealing layer in a barrier laminate, it was surprisingly found that the inter-layer seal strength significantly increased. In this way, the sealing layer is reliably secured to the substrate layer, such as a paper layer, and doesn’t peel away during use while holding a product, an ensure structural integrity and prevent the packaging product to burst or fail.

[0073] In this respect, it may be preferred, that the barrier laminate has a Water Vapour Transmission Rate at 23°C 50 %RH of below 20 g / m2 / day and more preferably below 10 g / m2 / day, and even more preferably below 5 g / m2 / day. Maximum inter-layer adhesion strength may preferably range between 1 and 5 N, more preferably between 1.25 and 4 N.

[0074] Accordingly, the invention relates to the use of an electrospun connection layer in a barrier laminate according to the invention, wherein the connection layer is deposited between a substrate layer and sealing layer, to enhance the inter-layer adhesion force. More in particular, the invention relates to the use of an electrospun fiber network in a connection layer in a flexible barrier laminate to enhance the inter-layer adhesion force, wherein the connection layer is deposited between a substrate layer and sealing layer. wherein the barrier laminate comprises:

[0075] • A substrate layer (1),

[0076] • A connection layer (2) comprising an electrospun fiber network,

[0077] • A non-fiber-based sealing layer (3), adjacent to the further layer (2) and facing the outside of the laminate, wherein the connection layer (2) has a thickness of from 1 to 30 micrometer, preferably of from 5 to 10 micrometer, wherein the sealing layer (3) preferably has a thickness of from 5 to 65 pm, preferably from 20 to 60 micrometer, more preferably from 20 to 50 pm, more preferably from 30 to 45 micrometer, most preferably from 30 to 40 pm and wherein preferably none of the substrate layer (1), further layer (2) and sealing layer (3) comprises petroleum-sourced material.

[0078] Preferably, none of the substrate layer, connection layer and sealing layer comprises petroleum- sourced material. Preferably the barrier laminate except for an optional protection layer (5), optional ink primer, optional ink layer, and optional precoating between the substrate and the connection layer, is free from petroleum-sourced material, and even more preferably, the barrier laminate except for an optional protection layer (5) and optional ink primer and optional ink layer (4) is free from petroleum-sourced material, and most preferably the barrier laminate is free from petroleum-sourced material.

[0079] The invention is now exemplified by the following, non-limiting examples.

[0080] Examples

[0081] Example 1

[0082] Paper-based flexible packaging materials according to the invention were prepared using the following process.

[0083] The fibre materials were solubilized using the parameters below:

[0084] Silk fibroin: Silk fibroin protein was solubilized in pure formic acid to obtain films, which were then solubilized at 8% w / v in formic acid under mechanical stirring for 20 minutes at room temperature. Zein: Zein was dissolved at room temperature in 80% v / v Ethanol 20% DI water under mechanical stirring for 1 hour. The end concentration of zein protein in the resulting solution was 29 wt%.

[0085] PHBV: Dissolution of the polymer was carried out in 1 ,1 ,1 ,3,3,3-Hexafluoro-2-propanol (HFIP) at 50°C under magnetic stirring overnight. In the morning, the solution was removed from the heat source and brought back to room temperature. A dimethyl sulfoxide (DMSO) + DI Water mixture (1 :1 , v / v) was added under magnetic stirring for 20 minutes, to result in a HFIP: DMSO: H2O mixture of 8:1 :1 and a final concentration of 7.5 wt% PHBV in the solvent. The solution is then ready to electrospin.

[0086] Paper sheets with grammages of 65, 78 and 90 gsm were introduced onto a collector with 210 mm x 297 mm dimensions. No vacuum was applied.

[0087] Four different electrospun fibre coatings were prepared. The solution chamber was loaded with the dissolved polymer, and a voltage was applied to the spinneret, from which the polymer is deposited. The difference in charge caused the polymer solution to create fibres, which project onto the paper on the collector. The solvent carrier for the polymer evaporates whilst the fibre travels to the collector. When the target fibre mat thickness was achieved, the coated paper is removed from the electrospinning rig. The target mat thickness was set to 20 pm prior to compression with heat.

[0088] Electrospinning parameters:

[0089] Using electrospinning fibres were obtained with diameters within a consistent range and deposition with ‘random’ (vs. ‘aligned’) fibre orientation. Spray droplets and other artefacts were absent. To this effect, the polymer concentration, the distance to the collector, the voltage and the spinneret rotation speed / flow rate of the polymer and the collector rotation speed were as indicated in Table 1.

[0090] Table 1 : Electrospinning parameters for polymer / protein fibres optimized to produce stable and uniform fibres, on a needleless electrospinning system.

[0091] Fibres spun at the above conditions had the following properties, indicated in table 2:

[0092] Table 2: Fibre properties of polymers / proteins spun onto paper.

[0093] A sealing layer of PHBH (not electrospun) is applied on the barrier layer. Consequently, substrate layer, the sealing layer and connection layer are laminated together using a Manual Hydraulic press and the conditions as indicated in table 3.

[0094] Table 3. Lamination conditions for producing the 3-ply laminates for further characterization. Lamination of the barrier laminate resulted in a barrier laminate with the specifications indicated in Table 4. samples after application of the lamination step which included compression.

[0095] *= PHBV in C.E. A is not electrospun, this is dispersion coated as a comparative example.

[0096] **= silk fibroin and PHBV were concomitantly applied by electrospinning in layers on top of one another Water vapour transmission rate (WVTR) measurements recorded at 23 °C 50 %RH were conducted using a MOCON AQUATRAN 3 WVTR Analyser following ASTM F3288-18 standards using a Coulometric P2O5 Sensor.

[0097] Inter layer adhesion measurements were performed at ambient conditions following ASTM F88, using an Instron.

[0098] WVTR:

[0099] Table 5: WVTR of 3 ply laminates at 23 °C 50 %RH

[0100] All structures of the invention show acceptable results at 23 °C 50 %RH. Example 3 has the highest WVTR reduction below an optimal value of 5 g / m2 / day.

[0101] Inter-layer Adhesion strength:

[0102] Table 6: Inter-layer adhesion strength

[0103] All examples 1-3 show an improved inter-layer adhesion force, when compared to the situation wherein the connection layer is not applied via electrospinning (Comparative Example A).

[0104] Example 2

[0105] An example of a barrier laminate according to the invention has been depicted below.

[0106] This proposed structure is the final construct that would be entered into a flexible sachet line for product manufacture. Here, the construct would be subject to another heating step to seal the exterior edges of the sachet prior to product filling. The sealing conditions used are preferably in a temperature range of 120-200 °C, a pressure range of 2-4 bar, and a time range of 0.5-1 seconds. The sealing layer (3) in this construct would form a seal around the product (6) and contain it.

Claims

Claims1. Flexible barrier laminate comprising:• A substrate layer (1), wherein the substrate layer is paper-based or cardboardbased,• A connection layer (2) comprises an electrospun fiber network,• A non-fiber-based sealing layer (3), adjacent to the connection layer (2) and facing the outside of the laminate, wherein the connection layer (2) has a thickness of from 1 to 30 micrometer, preferably of from 5 to 10 micrometer, wherein the sealing layer (3) preferably has a thickness of from 5 to 65 pm, preferably from 20 to 60 micrometer, more preferably from 20 to 50 pm, more preferably from 30 to 45 micrometer, most preferably from 30 to 40 pm. wherein preferably none of the substrate layer (1), connection layer (2) and sealing layer (3) comprises petroleum-sourced material.

2. Barrier laminate according to anyone of the preceding claims, wherein the density of the connection layer (2) is from 5 to 50 g / m2, preferably 5 to 30 g / m2, preferably from 10 to 20 g / m2.

3. Barrier laminate according to any one of the preceding claims, wherein the substrate layer is paper or cardboard.

4. Barrier laminate according to any one of the preceding claims, wherein the fibers in the fiber network of the connection layer (2) have a diameter of between 250 and 1000 nm, preferably of between 300 and 700 nm, and most preferably of 300 and 500 nm.

5. Barrier laminate according to any one of the preceding claims, wherein the connection layer (2) is not petroleum based and comprises one or more materials selected from the group consisting of polyhydroxyalkanoates, fibroin proteins, pro-lamines, chitin polysaccharides, phenolic polymers, and mixtures thereof.

6. Barrier laminate according to claim 5, wherein the connection layer consists of one or more materials selected from the group consisting of polyhydroxyalkanoates, fibroin proteins, prolamines, chitin polysaccharides, phenolic polymers, and mixtures thereof.

7. Barrier laminate according to claim 5 or 6, wherein the polyhydroxyalkanoates are selected from polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), wherein fibroin protein is silk protein, wherein pro-lamine is zein, wherein chitin polysaccharide is chitosan, and wherein phenolic polymer is lignin.

8. Barrier laminate according to any one of the preceding claims, wherein a pre-coat layer (3) is present between the substrate layer (1) and the connection layer (2), preferably based on clay.

9. Barrier laminate according to any one of the preceding claims, wherein the sealing layer (3) comprises polyhydroxyalkanoates (PHA), preferably polyhydroxybutyrate (PHB), poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), or poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) (PHBH), heat sealable cellulose or polymers from biomass and proteins and lipid films.

10. Barrier laminate according to any one of claims 1 to 8, wherein the sealing layer (3) comprises a compound selected from the group consisting of polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) (PHBH), heat sealable cellulose, polysaccharides, starch, zein protein, lipid films, chitosan and mixtures thereof.

11. Barrier laminate according to any one of the preceding claims, wherein there is only one layer comprising electrospun fibers present.

12. Process to provide a packaging laminate according to anyone of the preceding claims, the process comprising the steps of: a) Providing a substrate layer (1), wherein the substrate layer is paper-based or cardboard-based, b) Depositing fibers using electrospinning, to form a fiber network, c) Applying a sealing layer (3) over the fiber network, d) Laminating the composite comprising the substrate layer, the fiber network and sealing layer, to result in a barrier laminate according to any of the claims 1 to 11.

13. Process according to any one of claims 11 to 12, wherein at least two materials are electrospun at the same time in step b).

14. Flexible packaging product to package a consumer product, the packaging product comprising the barrier laminate according to anyone of the claim 1 to 11 , wherein the barrier laminate has been sealed wherein pieces of the barrier laminate have been sealed together or wherein a piece of barrier laminate has been folded and sealed together, wherein respective sealing layers (3) are facing each other, preferably wherein the packaging product is a wrapper or sachet.

15. Use of an electrospun fiber network in a connection layer in a flexible barrier laminate to enhance the inter-layer adhesion force, wherein the connection layer is deposited between a substrate layer and sealing layer, wherein the barrier laminate comprises:• A substrate layer (1), wherein the substrate layer is paper-based or cardboardbased,• A connection layer (2) comprising an electrospun fiber network,• A non-fiber-based sealing layer (3), adjacent to the further layer (2) and facing the outside of the laminate, wherein the connection layer (2) has a thickness of from 1 to 30 micrometer, preferably of from 5 to 10 micrometer, wherein the sealing layer (3) preferably has a thickness of from 5 to 65 pm, preferably from 20 to 60 micrometer, more preferably from 20 to 50 pm, more preferably from 30 to 45 micrometer, most preferably from 30 to 40 pm and wherein preferably none of the substrate layer (1), further layer (2) and sealing layer (3) comprises petroleum-sourced material.

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