Recyclable multilayer liner

Abstract

The invention relates to a recyclable multilayer liner (1) for use in containers for transporting liquids, comprising an outer polyethylene-based layer (2), an inner polyethylene based layer (8), a barrier layer (5) centrally located, serving as a gas barrier and two protective layers (4, 6) wherein at least two layers (3, 4, 6, 7) are symmetrically sandwiching the barrier layer (5), wherein the protective layers (4, 6) are configured to protect the barrier layer (5) mechanically and prevent it from swelling in the presence of moisture, maintaining its gas barrier properties. The protective layers (4, 6) are (PE) polyethylene based.

Description

[0001] RKW V689

[0002] Recyclable multilayer liner

[0003] Description

[0004] The invention relates to a recyclable multilayer liner for use in containers for transporting liquids, comprising an outer polyethylene-based layer, an inner polyethylene based layer, a barrier layer centrally located, serving as a gas barrier and wherein at least two layers are symmetrically sandwiching the barrier layer, wherein the protective layers are configured to protect the barrier layer mechanically and prevent it from swelling in the presence of moisture, maintaining its gas barrier properties.

[0005] Liners, also known as inliners or bag-in-box systems, are flexible inner bags that are used in intermediate bulk containers (IBCs) to protect the container from direct contact with the contents. Their use offers numerous advantages, particularly in industries with high hygiene requirements or when it comes to preventing contamination and soiling. One of the main advantages is that liners form an effective barrier between the IBC and the contents. This prevents the contents from coming into contact with the container, which significantly reduces the risk of contamination. This is particularly important in the food and pharmaceutical industries, where the purity and safety of the products must be guaranteed.

[0006] Liners also help to reduce material and transport costs as they are lightweight and flexible. They take up little space before filling and are often more cost- effective compared to rigid containers or packaging. In addition, empty IBCs can be quickly reused after the liner has been disposed of without any additional cleaning work. Another important aspect is that liners can be customised for different filling goods. There are different designs, materials and sizes that are specially tailored to the requirements of the respective filling goods, whether for liquids, powders or even hazardous substances. RKW V689

[0007] 2

[0008] In the chemical industry, liners also prevent reactions between the filling product and the walls of the container, which protects both the product and the IBC. This means that particularly aggressive or sensitive chemicals can be transported and stored safely. In the food industry, liners are often used for the storage and transport of liquids such as sauces, oils or fruit juices, as well as for dry products such as powders or granulates.

[0009] Another advantage of using liners is the considerable reduction in cleaning effort. As the contents are filled directly into the liner, the IBC itself remains clean. After use, the liner is disposed of and the container can be immediately prepared for the next use without any time-consuming cleaning. This not only saves time, but also costs. Liners also offer additional protection for sensitive products. Certain filling goods, such as liquids or powders, react sensitively to moisture, oxygen or light. Special liners with barrier properties can be used to protect the product from these influences and extend its shelf life.

[0010] The structure of liners with barrier properties is usually multi-layered to ensure a combination of mechanical stability and effective barrier effect. The innermost layer, which is in direct contact with the product, is often made of food-safe or chemical-resistant polyethylene. This material is inert and prevents interaction with the product. Polypropylene is also used for liners for sensitive liquids or chemicals, as it offers high chemical resistance and stability.

[0011] WO 2006 / 063208 A2 Compositions and packaging films are provided having a multilayer oxygen barrier comprising an EVOH copolymer layer in contact with at least one polyamide layer. The EVOH copolymer compositions preferably comprise about 44mol%, or less of ethylene. Multilayer packaging films can optionally include an exterior layer comprising heat resistant materials such as polyester or polyamide. The multilayer oxygen barriers described herein can provide high shrink films with desirably high oxygen barrier properties. The RKW V689

[0012] 3 oxygen barriers can be used in making heat-shrinkable films and food packages having desirable high levels of free shrink.

[0013] WO 2006 / 128589 A1 Barrier film for use in packaging, particularly for the packaging of foods and tobacco, in the form of a multi-layer film based on a biaxially oriented polyolefin film having at least one coextruded functional layer or barrier based on ethylene-vinyl alcohol copolymers (EVOH), which is produced by simultaneous drawing of a coextruded multi-layer primary film at temperatures of 145°C and below, the ethylene content of the EVOH being below 40 mol% and the thickness of the EVOH layer being less than 5 pm, in particular less than 2 pm, thereby producing values for the oxy en permeability at 23 C and 75% relative humidity (OTR; ASTM 3985) of better than 10 cm3 / m2dbar, preferably better than 5 cm f / m2dbar.

[0014] The WO 2017 / 162335 A1 relates to a rigid plastic liner made of thermoplastics for a pallet container or a similar large-volume container for storing and transporting liquid or fluid goods, having a flexible inner lining made of a thin-walled plastic or composite film inserted into the rigid plastic liner. For filling and emptying the container through the bottom thereof, the thin-walled inner lining has at least one bottom filling and emptying pipe permanently welded at the front into a corresponding bottom filling and emptying pipe of the rigid plastic liner. For filling the container through the top and emptying it through the bottom, the rigid plastic liner and the thin-walled inner lining can also be provided each with a top filling pipe, and then the top filling pipe of the thin-walled inner lining is likewise permanently welded into the filling pipe of the rigid plastic liner. Through application of a vacuum, the thin-walled inner lining inserted into the rigid plastic liner lies in the mounted end state over its entire surface against the inner surface of the rigid plastic liner, and is immovably fixed as if by glue to the inner surface, in particular to the head of the liner, both in the empty, non-filed state and in the filled state of the rigid plastic liner. RKW V689

[0015] 4

[0016] The middle layer of a barrier liner can be made of EVOH, which provides an excellent barrier against oxygen and other gases. EVOH is often used to protect products that can be oxidised or spoiled by oxygen, such as food or certain chemical products.

[0017] In some cases, an aluminium layer or aluminium composite can also be integrated, which acts as a strong light and gas barrier. Such metallised layers are used to create a virtually impenetrable barrier against oxygen and moisture. They are particularly important when it comes to protecting light-sensitive or highly reactive products.

[0018] The centre barrier layer of a liner is often protected with layers of polyamide (PA). The polyamide offers high mechanical strength and resistance to abrasion or punctures. Polyamide improves the resistance of the liner during transport and handling and protects the middle barrier layer from moisture and water vapour, which could negatively affect the barrier properties.

[0019] The recyclability of liners with barrier properties cannot be realised industrially due to their complex material structure. These liners often consist of several layers of different plastics, such as PE, PP, PA and EVOH, whose complex material structure provides an effective barrier against gases and moisture. However, it is precisely this multi-layer structure that makes recycling considerably more difficult, as the individual materials can only be separated from each other with difficulty. Recycling plants are usually designed to process singleorigin plastics, which is why composite materials are either only recycled as mixed plastic of inferior quality or not recycled at all.

[0020] As part of its strategy to promote the circular economy, the EU is pursuing ambitious goals that also relate to the recyclability of packaging such as liners. The Packaging Directive 94 / 62 / EC, which stipulates that packaging must be designed in such a way that it can be easily recycled, forms an important basis. RKW V689

[0021] 5

[0022] As part of the European Green Deal and the Circular Economy Action Plan, the EU has formulated the target that all packaging placed on the market in the EU should be either reusable or fully recyclable by 2030.

[0023] By 2025, at least 65% of all packaging waste is to be recycled, with a quota of at least 50% to be achieved for plastics, of which liners are often made. By 2030, this figure is to rise to 55% for plastic packaging.

[0024] With the new Packaging and Packaging Waste Regulation, which will replace the current Packaging Directive, the EU is also planning to introduce stricter requirements for recyclability. Packaging, including liners, is to be designed in such a way that it can be recycled easily and efficiently right from the design phase. As a rule, packaging is considered to be unmixed if it contains a maximum of five per cent foreign material. In many cases, these small quantities can be removed or tolerated during the recycling process without significantly impairing the quality of the recycled material.

[0025] The task is to provide a recyclable liner that nevertheless has the mechanical properties and barrier properties of previously known non-recyclable liners in order to fulfil the future requirements of the Plastics Pact 2025. The liner is to be designed to be fully recyclable. The liner should also be suitable for filling with food and chemicals. Furthermore, the liner should be cost-effective to manufacture.

[0026] According to the invention, this task is ensured by a recyclable liner, a method and a use according to the subsidiary main claims. Preferred variants can be found in the sub-claims, the description, the embodiment example and the drawings.

[0027] According to the invention, the protective layers are (PE) polyethylene based. RKW V689

[0028] 6

[0029] In one variant of the invention, at least one intermediate layer is separated from the barrier layer by a protective layer.

[0030] The protective layers, for example, are immediately adjacent to the barrier layer.

[0031] For example, at least two of the sandwiching layers, respectively the protective layers and / or the intermediate layers comprising a specific polyethylene material containing at least 5 wt.-% of a masterbatch additive.

[0032] In one variant of the invention, the masterbatch contains at least 30 wt.-% particles that create a tortuous path for gas and moisture molecules, thereby significantly enhancing the barrier properties of the protective layers to achieve an oxygen permeability of the liner of less than 10 cm3 / m2d bar according to ASTM D3985.

[0033] For example, at least two of the protective layers and / or the intermediate layers comprising a specific polyethylene material containing of more than 7.5 wt.-%, preferably of more than 10 wt.-%, in particular of more than 15 wt.-% and less of 40 wt.-%, preferably of less than 30 wt.-%, in particular of less than 25 wt.-% of a masterbatch additive.

[0034] In one variant of the invention, only the protective layers comprising a specific polyethylene material containing at least 5 wt.-% of a masterbatch additive.

[0035] In another variant of the invention, only the intermediate layers comprising a specific polyethylene material containing at least 5 wt.-% of a masterbatch additive. RKW V689

[0036] 7

[0037] In a third variant of the invention, the protective layers and the intermediate layers comprising a specific polyethylene material containing at least 5 wt.-% of a masterbatch additive.

[0038] For example, the protective layers and the intermediate layers comprising the same content of a masterbatch.

[0039] In another variant of the invention, the protective layers and the intermediate layers comprising different contents of the masterbatch.

[0040] In order for a liner to fulfil its task, it must have a certain oxygen impermeability. This is the only way to ensure the adequately protected transport of sensitive liquids or impermeability to chemicals.

[0041] For example, the liner has an oxygen permeability of less than 8 cm3 / m2d bar, preferably less than 6 cm3 / m2d bar, in particular less than 4 cm3 / m2d bar at 23°C and 50 % relative humidity in accordance with ASTM D3985.

[0042] The multi-layer liner is essentially free of polyamide (PA) and consists mainly of polyethylene (PE), which makes it recyclable according to EU standards, whereby the proportion of foreign polymers, including the barrier layer, which preferably consists of EVOH, does not exceed 5% of the total weight of the liner, thus ensuring the recyclability of the liner according to EU directives.

[0043] The polyamide-free design of the liner can be achieved, for example, by selecting a special polyethylene for the protective layer in combination with a very favourable masterbatch.

[0044] The masterbatch can consists of a polyethylene carrier material and an active ingredient preferably a nanoclay, which is composed of layered silicates, such as montmorillonite. RKW V689

[0045] 8

[0046] The physical effect achieved when the beneficial masterbatch is incorporated into the polyethylene protective layer is mainly based on the creation of a tortuous path for the molecules of water vapour and gases.

[0047] Nanoclay is a special form of clay that consists of tiny particles on a nanoscale. These fine clay minerals, which either occur naturally or are produced synthetically, are characterised by a special layered structure. They usually consist of layered silicates in which ultra-thin layers of silicon and aluminium silicates alternate. Due to this structure, nanoclays offer an extremely large surface area, which accounts for their special properties.

[0048] One of the most common forms of nanoclay is montmorillonite, which consists of finely structured layered silicates, but kaolinite is also a common variant. Nanoclays have outstanding mechanical properties that make them a valuable material reinforcer. Thanks to their nanostructure, they can significantly improve the mechanical strength, heat resistance and stability of plastics. They also act very favourably as barriers against gases and liquids by reducing their permeability.

[0049] The nanoclay particles act as physical barriers for gas or water molecules that want to diffuse through the polymer. Without the nanoclay particles, gas molecules can pass through the amorphous areas of the polyethylene relatively easily. However, when nanoclay is introduced into the polyethylene layer, the gas molecules have to travel a much longer, complicated path around these particles, which significantly slows down the diffusion process

[0050] For example, the size of the particles ranges from 1 to 100 nm. These particles have an extremely high surface area and are often a few nanometres to micrometres in size. Nanoclay is evenly distributed in the polyethylene layer through the manufacturing process. RKW V689

[0051] 9

[0052] In one variant of the invention, the particles are typically composed of aluminosilicates.

[0053] For example, the masterbatch has a density of more than 0.94 g / cm3and less than 1.05 g / cm3. In the masterbatch, these nanoclays and layered silicates are processed in such a way that they are optimally dispersed in the polyethylene layer. The nanoclay particles are able to change the physical properties of the material without affecting the flexibility or processability of the film.

[0054] In one special variant of the invention, the masterbatch has a density of more than 0.94 g / cm3and less than 0.96 g / cm3.

[0055] In one variant of the invention, the PE of the protective layer has a density of more than 0.925 g / cm3and less than 0.930 g / cm3.

[0056] For example, the thickness of the protective layers is more than 5 pm and less than 20 pm.

[0057] The molecular weight distribution (MWD) describes the distribution of molecular weights or chain lengths of molecules in a sample, especially in polymers. Since polymers consist of chains with varying lengths, they do not have a uniform molecular mass, but a range of masses. The molecular weight distribution indicates how these masses are distributed in the sample. A measure of the width of the molecular weight distribution, defined as the polydispersity index (PDI).

[0058] A PDI value of 1 means that all molecules have the same mass (monodisperse), while larger values indicate a broad distribution (polydisperse). The molecular weight distribution influences the properties of polymers, such as viscosity, melting point, mechanical strength and solubility. Polymers with a narrow distribution (small PDI) often show a more uniform behaviour, while polymers with RKW V689

[0059] 10 a broad distribution (high PDI) can have more complex properties. Methods such as gel permeation chromatography (GPC) or light scattering are used to measure the molecular weight distribution in polymers.

[0060] In one variant of the invention, the PE of the protective layer has a molecular weight distribution (PDI) according to ISO 16014 of less than 2.

[0061] Short-chain branching (SCB) refers to the presence of short side chains in the main chain of a polymer, typically in polyolefins such as polyethylene or polypropylene. These side chains often consist of a few carbon atoms (e.g. methyl, ethyl or butyl groups) and are formed by incomplete polymerization processes, such as those that occur in the production of low-density polyethylene (LDPE) or certain copolymers.

[0062] SCB reduces the density of the polymer as the branches prevent the molecular chains from packing tightly together. The short branches reduce the ability of the polymer to form ordered, crystalline structures, which can lead to a semicrystalline or amorphous material. The presence of SCB affects the flexibility, strength and toughness of the polymer. Polymers with more SCB usually have a lower melting point.

[0063] For example, the PE of the protective layer has a short-chain branching (SCB) of 5 - 20 SCB per 1000 carbon atoms.

[0064] Elongation at Break is a mechanical parameter that describes the ability of a material to stretch before it tears under load. It is specified as a percentage change in length in relation to the original length of the material. Materials with a high elongation at break can stretch considerably without breaking, which indicates high ductility or elasticity. RKW V689

[0065] 11

[0066] In one variant of the invention, the PE of the protective layer has an elongation at break according to ISO 527-1 of more than 400 %, preferably more than 550 %, in particular more than 700 %.

[0067] All these special properties of the PE of the PE-based protective layer realise a protective layer that comes very close to the mechanical properties and barrier properties of a polyamide, whereby an otherwise conventional barrier layer can be replaced by this special PE-based protective layer.

[0068] As a result, the protective layer can protect the barrier layer from mechanical impact, but also especially from the impact of water vapour, which could impair and reduce the oxygen barrier of the EVOH.

[0069] In addition, the embodiment of the liner according to the invention is the first to realise a variant that is also considered recyclable according to the new requirements of the European Union and which also proves itself in the practical implementation of recycling by completely replacing the polyamide with advantageous mechanical properties and barrier properties.

[0070] The special physical parameters of the liner are achieved through the selection and combination of suitable raw materials, whereby the structure of the liner in particular plays a decisive role in achieving the properties.

[0071] The water vapor permeability of dry or moisture-sensitive goods is determined in accordance with DIN 53116 or ASTM D6701-01 using a gravimetric measurement method. A test container filled with a desiccant is sealed with a sample of foil and exposed to a defined test climate. The amount of water permeating through the sample is determined by weighing. A quantity of water in a range of 1 - 200 g / (m2■ d) can be detected. The detection limit is also dependent on the composition and thickness of the sample. RKW V689

[0072] 12

[0073] For example, the recyclable multilayer liner has a water vapour permeability of less than 10 g / m2in 24 h according to ASTM D6701-01.

[0074] In a variant of the invention, the recyclable multilayer liner has a water vapor permeability of less than 8 g / m2, preferably less than 6 g / m2, in particular less than 4 g / m2in 24 h according to ASTM D6701-01. This protects liquids and chemicals that are transported and stored in containers, even for longer periods of time.

[0075] For example, the liner has a puncture resistance energy according to JAS P1019 of more than 10 mJ.

[0076] The puncture resistance is determined in accordance with JAS P1019, whereby a test sample of the recyclable multilayer liner is clamped in a sample holder. The clamping device is designed so that the inside diameter is 10 mm. A probe with a rounded tip pierces the test sample at a constant speed. The force and elongation required for piercing are determined.

[0077] For example, the recyclable multilayer liner has a puncture resistance according to JAS P1019 of more than 15 mJ, preferably more than 20 mJ, in particular more than 25 mJ. As a result, the liner also withstands the demands of filling extremely well.

[0078] The recyclable multilayer liner has a tear resistance in MD according to ASTM 1922 of more than 350 kN / m, preferably more than 400 kN / m, in particular more than 450 kN / m. This makes the container liner particularly tear-resistant during the filling process as well as during transport and storage.

[0079] The recyclable multilayer liner has a tear resistance in CD according to ASTM 1922 of more than 300 kN / m, preferably more than 350 kN / m, in particular more than 400 kN / m RKW V689

[0080] 13

[0081] The recyclable multilayer liner has a Spencer puncture Energy according to ASTM3420 of more than 2000 mJ, preferably more than 2350 mJ, in particular more than 2700 mJ. The special structure and the specially selected raw materials produce a film for liners that can withstand the enormous mechanical stresses that occur when filling or plugging the container.

[0082] The Elmendorf test according to DIN 53128 determines the average force in grams or mN required to tear a sample after the tearing process has been initiated. During the test, one or more layers of the film are torn with a pendulum over a defined distance. The force applied during tearing is measured by the loss of potential energy of the pendulum.

[0083] In one variant of the invention, the recyclable multilayer liner has a tensile strength in the machine direction according to Elmendorf DIN 53128 of more than 10 — , preferably more than 15 — , in particular more than 20 — . This means that |im |im |im the liner is optimally prepared for the challenge during the filling process and effectively prevents the liner from traveling.

[0084] The thickness of the liner was measured in accordance with DIN 53370 and specified as an average value. For example, the liner has a thickness of less than 140 pm and more than 40 pm.

[0085] For example, the recyclable multilayer liner has a thickness of less than 135 pm, preferably less than 125 pm, in particular less than 115 pm.

[0086] In a particularly advantageous variant of the invention, the thickness of the recyclable multilayer liner is 100 pm. RKW

[0087] V689

[0088] 14

[0089] By reducing the thickness of the liner while retaining its excellent mechanical properties, the requirements of the EU Plastics Pact in particular can be met. The volume of the liner is significantly reduced, although the same amount of liner can be used.

[0090] For example, the recyclable multilayer liner has a seven-layer structure. The liner has an outer and an inner layer, each of which is followed by an intermediate layer. The intermediate layer is adjoined by a protective layer that encloses the barrier layer.

[0091] For example, at least one intermediate layer is arranged between the outer layer and the protective layer.

[0092] In one variant of the invention, at least one intermediate layer is arranged between the inner layer and the protective layer.

[0093] In a further variant, the recyclable multilayer liner is designed with five layers, whereby, in contrast to the seven-layer variant, no intermediate layer is considered.

[0094] A version with nine layers is also conceivable.

[0095] In one variant of the invention, the barrier layer is formed from an EVOH.

[0096] For example, the thickness of the barrier layers is more than 3 pm and less than 15 pm. This means that the barrier layer is particularly thin and saves material, while still having excellent barrier properties.

[0097] In addition, the proportion of the barrier layer is less than 5 % by weight of the recyclable multilayer liner and therefore fully complies with the European Union's specifications for the recyclability of plastic films. RKW V689

[0098] 15

[0099] For example, the EVOH of the barrier layer has a density according to ISO 1183- 1 of more than 0.90 g / cm3, preferably more than 0.91 g / cm3and / or less than 0.94 g / cm3, preferably less than 0.93 g / cm3.

[0100] For example, the EVOH has an oxygen permeability of less than 5 cm3 / m2d bar, preferably less than 3 cm3 / m2d bar, in particular less than 2 cm3 / m2d bar at 23°C and 50 % relative humidity in accordance with ASTM D3985.

[0101] The production of LLDPE is initiated by transition metal catalysts, in particular Ziegler or Philips type catalysts. The actual polymerization process can be carried out either in the solution phase or in gas phase reactors. As a rule, octene is the comonomer in the solution phase, while butene and hexene are copolymerized with ethylene in a gas phase reactor. LLDPE has a higher tensile strength and a higher impact and puncture resistance than LDPE. It is very flexible and expands under load. It can be used to produce thinner films that have better resistance to stress cracking. It has good resistance to chemicals. It has good electrical properties. However, it is not as easy to process as LDPE, has a lower gloss and a narrower range for heat sealing.

[0102] For example, the intermediate layer comprises least 60 % by weight of an LDPE and this ensures enormous tear resistance.

[0103] In one variant of the invention, the proportion of LDPE in the intermediate layer is more than 70 % by weight and less than 90 % by weight.

[0104] The flow behavior of polyolefins is described using the melt flow rate respectively the MFI according to ISO 1133-1 , usually at a temperature of 190 °C for polyethylene and 230 °C for polypropylene at a load of 2.16 kg, 5 kg or 21 .6 kg. A higher melt flow index correlates with a lower average molecular weight of the polymer. At the same time, the higher the melt index of a polymer, the lower the RKW V689

[0105] 16 melt viscosity, which is advantageous for a high output of the extrusion system. On the other hand, polymers with a high molecular weight, i.e. a low melt index, are advantageous in terms of mechanical stability, in particular tensile strength or toughness.

[0106] For example, the intermediate layer has a proportion of LDPE which density according to ISO 1183-1 is more than 0.917 g / cm3and is less than 0.919 g / cm3, and which MFI (at 190 °C at 5 kg) according to ISO 1133-1 is more than 0.9 g / 10 min and is less than 1 .1 g / 10 min.

[0107] In one variant of the invention, the thickness of the intermediate layers is more than 5 pm and less than 20 pm.

[0108] For example, the outer layer and / or the inner layer has a proportion of mLDPE which density according to ISO 1183-1 is more than 0.910 g / cm3and is less than 0.914 g / cm3, and which MFI (at 190 °C at 5 kg) according to ISO 1133-1 is more than 0.9 g / 10 min and is less than 1.1 g / 10 min.

[0109] By way of example, the proportion of mLDPE in the outer layer and / or the inner layer is more than 55 % by weight and less than 80 % by weight. The proportion of mLDPE in the outer layer and / or the inner layer advantageously increases the stability of the silage tube.

[0110] In one variant of the invention, the thickness of the outer layer and / or the inner layer is more than 5 pm and less than 20 pm.

[0111] According to the invention, a liner is produced by a process in which an outer layer and an inner layer of polyethylene, one barrier layer whereby the barrier layer being a EVOH with a thickness of less than 15 pm, two protective layers symmetrically sandwiching the barrier layer are produced by coextrusion, wherein the protective layers are extruded with a masterbatch that create a RKW

[0112] V689

[0113] 17 tortuous path for gas and moisture molecules, thereby significantly enhancing the barrier properties of the protective layers to achieve an oxygen permeability of the liner of less than 30 cm3 / m2d bar according to ASTM D3985.

[0114] According to the invention, the liner is used for lining a container for the transport of liquids.

[0115] This provides a liner which, with high oxygen-tightness and flexible behaviour, simultaneously has a high tear resistance, so that undesired bursting or tearing is prevented and at the same time only a relatively low thickness of the liner is required, so that the liner according to the invention is relatively light. By using the PE-based protective layer in combination with the masterbatch, the liner can be made particularly cost-effective and yet recyclable.

[0116] Further advantages and features of the invention are apparent from the description of an embodiment example with reference to drawings and from the drawings themselves.

[0117] In this connection

[0118] Fig. 1 a schematic representation of the recyclable multilayer liner.

[0119] Fig. 1 shows a liner 1 with seven layers for use in containers for transporting liquids.

[0120] In this embodiment, the outer layer 2 and the inner layer 8 are made of a proportion of mLDPE, whereas the outer layer 2 and the inner layer 8 comprise 80 % by weight of an mLDPE with a melting temperature of 113 °C and whereas MFI of the mLDPE is 0.45. RKW

[0121] V689

[0122] 18

[0123] The intermediate layers 3 and 7 are made of a proportion of LDPE, whereas the connecting layers 3 and 7 comprise 80 % by weight of an LDPE with a melting temperature of 116 °C and whereas MFI of the LDPE is 0.27. The protective layers 4 and 6 are made of a proportion of LDPE, whereas the protective layers 4 and 6 comprise 85 % by weight of an LDPE with a melting temperature of 116 °C and whereas MFI of the LDPE is 0.27. The protective layers 4 and 6 also contain a proportion of 15 % by weight of a gas barrier masterbatch with nanoclays. The protective layers 4 and 6 achieve an oxygen permeability of the liner 1 of less than 10 cm3 / m2d bar according to ASTM D3985.

[0124] The barrier layer 5 is made of an EVOH, whereby the melting point of the EVOH is 185 °C.

Claims

RKWV689Recyclable multilayer linerClaims1 . A recyclable multilayer liner (1 ) for use in containers for transporting liquids, comprising:- an outer polyethylene-based layer (2),- an inner polyethylene-based layer (8),- a barrier layer (5) centrally located, serving as a gas barrier,- two protective layers (4, 6)- wherein at least two layers (3, 4, 6, 7) are symmetrically sandwiching the barrier layer (5),- wherein the protective layers (4, 6) are configured to protect the barrier layer (5) mechanically and prevent it from swelling in the presence of moisture, maintaining its gas barrier properties, characterized in that the protective layers (4, 6) are (PE) polyethylene based.

2. Liner according to claim 1 , characterized in that at least one intermediate layer (3, 7) is separated from the barrier layer (5) by a protective layer (4, 6).

3. Liner according to claim 1 or 2, characterized in that the protective layers (4, 6) are immediately adjacent to the barrier layer (5).RKW V68924. Liner according to at least one of the proceeding claims, characterized in that at least two of the sandwiching layers (3, 4, 6, 7) comprise a specific polyethylene material containing at least 5 wt.-% of a masterbatch additive, wherein the masterbatch contains at least 30 wt.-% particles that create a tortuous path for gas and moisture molecules, thereby significantly enhancing the barrier properties to achieve an oxygen permeability of the liner (1 ) of less than 10 cm3 / m2d bar according to ASTM D3985.

5. Liner according to at least one of the proceeding claims, characterized in that the multilayer liner (1 ) being substantially free of polyamide (PA) and consists primarily of polyethylene (PE), making it recyclable according to EU standards wherein the amount of foreign polymers, including the barrier layer (5) preferably made of EVOH, does not exceed 5 % of the total weight of the liner (1 ), ensuring the recyclability of the liner (1) according to EU guidelines.

6. Liner according to at least one of the proceeding claims, characterized in that the size of the particles ranges from 1 to 100 nm.

7. Liner according to at least one of the proceeding claims, characterized in that the liner (1 ) has a water vapour permeability of less than 10 g / m2in 24 h according to ASTM D6701-01.RKWV68938. Liner according to at least one of the proceeding claims, characterized in that the liner has a puncture resistance energy according to JAS P1019 of more than 10 mJ.

9. Liner according to at least one of the proceeding claims, characterized in that the liner (1) has a tear resistance in MD according to ASTM 1922 of more than 300 kN / m.

10. Liner according to at least one of the proceeding claims, characterized in that the PE of the protective layer (4, 6) has a density of more than 0.925 g / cm3and less than 0.930 g / cm3.11 . Liner according to at least one of the proceeding claims, characterized in that the masterbatch has a density of more than 0.94 g / cm3and less than 1 ,05 g / cm3.

12. Liner according to at least one of the proceeding claims, characterized in that the PE of the protective layer (4, 6) has a molecular weight distribution (PDI) according to ISO 16014 of less than 2.

13. Liner according to at least one of the proceeding claims, characterized in that the PE of the protective layer (4, 6) has a short-chain branching (SCB) of 5 - 20 SCB per 1000 carbon atoms.RKWV689414. Liner according to at least one of the proceeding claims, characterized in that the PE of the protective layer (4, 6) has an elongation at break according to ISO 527-1 of more than 400 %, preferably more than 550 %, in particular more than 700 %.

15. Liner according to at least one of the proceeding claims, characterized in that the liner (1 ) has a tensile strength in the machine direction and / or cross machine direction according to Elmendorf DIN 53128 of more than 10 — , preferably more than 15 — |im , in particular more than 20 — |im .

16. Liner according to at least one of the proceeding claims, characterized in that the liner (1) a thickness of less than 140 pm and more than 40 pm.RKWV689517. Process for the manufacture of a Liner (1 ) comprising the following steps: extrusion of an outer layer (2) and an inner layer (8) of a polyethylene, co-extrusion of one barrier layer (5), whereby the barrier layer (5) being a EVOH with a thickness of less than 10 pm, two protective layers (4, 6) symmetrically sandwiching the barrier layer (5), characterized in that that the protective layers (4, 6) are extruded with a masterbatch that create a tortuous path for gas and moisture molecules, thereby significantly enhancing the barrier properties of the protective layers (4, 6) to achieve an oxygen permeability of the liner of less than 10 cm3 / m2d bar according to ASTM D398518. Use of a Liner (1 ) according to any one of claims 1 to 16 lining a container that is used for the transport of liquids.

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