Film for silage packaging

Abstract

The present invention relates to a multi-layer cast film comprising at least five layers, being: (a) a first outer layer; (b) a first intermediate layer (c) a core layer; (d) a second intermediate layer; and (e) a second outer layer; wherein the layers are present in this order; wherein the layer (a) comprises an ethylene-based polymer A having a density of ≤ 890 kg / m3, preferably of ≥ 850 and ≤ 890 kg / m3, as determined in accordance with ASTM D792 (2013), and a melt mass-flow rate of ≥ 3.0 and ≤ 8.0 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 190°C and 2.16 kg load; wherein the layers (b) and (d) both comprise an ethylene-based polymer B having a density of ≥ 910 and ≤ 930 kg / m3 and a melt mass-flow rate at 190°C / 2.16 kg of ≥ 0.5 and ≤ 2.0 g / 10 min; and wherein the layer (e) comprises an ethylene-based polymer F having a density of ≥ 945 and ≤ 970 kg / m3 and a melt mass-flow rate of ≥ 5.0 and ≤ 10.0 g / 10 min, at 2.16 kg / 190°C. Such film provides a desirable balance of good cling force, unwind force, peel off force and puncture resistance.

Description

24POLYOQ85-WO-ORD 1Film for silage packaging.

[0001] The present invention relates to a film for silage packaging.

[0002] In the realm of agricultural preservation, polyethylene films have emerged as a pivotal player in the silage packaging industry. These films, meticulously engineered from linear low- density polyethylene (LLDPE), high-density polyethylene (HDPE) or low-density polyethylene (LDPE) polymers, possess a unique set of properties that make them indispensable for optimizing the conservation and longevity of silage.

[0003] A function of polyethylene films in silage packaging is to create an airtight seal, thereby minimizing the entry of atmospheric oxygen into the silage mass. Oxygen, a notorious enemy of silage, facilitates the growth of spoilage microorganisms, which can drastically decrease the nutritional value and palatability of the silage. By obstructing oxygen intrusion, polyethylene films contribute significantly to maintaining the desired anaerobic conditions within the silage.

[0004] Additionally, these films offer remarkable resistance to UV radiation and water penetration. UV radiation can cause polymer degradation and thus compromise the film's integrity, leading to potential leaks and premature aging. Water penetration can dilute the silage, potentially leading to clumping and uneven feeding. Polyethylene films effectively shield the silage from these external factors, ensuring optimal preservation conditions.

[0005] Furthermore, their flexibility, strength, and adaptability to various silage densities and volumes make polyethylene films a versatile and cost-effective solution for silage packaging. The films can be manufactured in various thicknesses and sizes, catering to the specific needs of different agricultural operations.

[0006] Accordingly, the use of polyethylene films in silage packaging provides an airtight seal, resistance to UV radiation and water penetration, and adaptability to different silage densities and volumes, all of which are crucial factors in preserving the quality and nutritional value of silage for livestock feed.

[0007] Polyethylene films for silage packaging, herein also referred to as silage films, may be produced by cast film production technology. Polyethylene film production by casting is a24POLYOQ85-WO-ORD 2 manufacturing process that involves the melting and spreading of polyethylene resin onto a chill roll to form a thin, uniform layer. The molten polyethylene is extruded from a die, which is adjusted to control the film's thickness and width. As the film cools and solidifies on the chill roll, it is then wound up onto spools for further processing or shipping.

[0008] Cast polyethylene film has several advantages. Cast film has a smooth surface, which contributes to print quality for labels and other graphics. Additionally, the casting process allows for the production of films with a wide range of thicknesses, which can be tailored to specific applications. Cast films have excellent mechanical properties, including high tensile strength, tear resistance, and flexibility.

[0009] Polyethylene silage films typically are produced as multi-layer films. In cast extrusion of such films, an arrangement of the film casting die head and multiple extruders may be positioned such that a multi-layer film is co-extruded, wherein the composition and thickness of each layer can be specifically tailored to contribute to the function of the produced film. Typically, such multi-layer films comprise at least a core layer and two outer layers. In silage film, one such outer layer will be a cling layer, and the other outer layer a release layer.

[0010] A cling layer in a cast polyethylene film is a critical component, especially for wrapping applications. Its primary function is to enhance the film's adhesion to various surfaces, ensuring a strong, secure bond. The cling layer uses the principles of surface energy and Van der Waals forces to create a strong attraction between the film and the surface it's being wrapped around. This property is essential in maintaining the integrity and shape of the wrapped product, preventing unwanted air or moisture intrusion, and ensuring the longevity of the packaging.

[0011] A release layer in a cast polyethylene film serves to prevent the film from unwanted sticking to itself or other surfaces. Functions of the release layer include easy unwinding, enabling easy removal of the film from the rolls in which they are produced during the wrapping process of the silage, allowing for fast packaging whilst at the same time minimizing tearing of the film during the packaging process; surface protection of the film; and controlled adhesion, in applications where the film needs to be removed and reapplied, avoiding tearing of the film.

[0012] It is a continued desire in development of film for silage packaging to provide for a cast film having a desirable balance of cling and release properties. In addition, there is a desire for such film to contain only polyolefin materials as polymer materials. Notable advantages of such24POLYOQ85-WO-ORD 3 single-material films pertain to recyclability and sustainability aspects, since films made solely of polyolefins can be more easily recycled, as they avoid the complexity of separating different polymer types, which in particular in the case of multi-layer films is practically undoable. It also results in less contamination in the recycling streams, allowing for higher quality of recycled materials. Additionally, production of films comprising only polyolefins as polymer material contributes to more simplified manufacturing. An example of such single-material polyolefin films are polyethylene / polypropylene films, such as for example polyethylene / polypropylene films comprising up to 20 wt% of polypropylene. In the context of the present invention, polyolefins may for example be ethylene-based polymers and propylene-based polymers.

[0013] The above has now been achieved according to the present invention by a multi-layer cast film comprising at least five layers, being:(a) a first outer layer;(b) a first intermediate layer(c) a core layer;(d) a second intermediate layer; and(e) a second outer layer; wherein the layers are present in this order; wherein the layer (a) comprises an ethylene-based polymer A having a density of < 890 kg / m3, preferably of > 850 and < 890 kg / m3, as determined in accordance with ASTM D792 (2013), and a melt mass-flow rate of > 3.0 and < 8.0 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 190°C and 2.16 kg load; wherein the layers (b) and (d) both comprise an ethylene-based polymer B having a density of > 910 and < 930 kg / m3and a melt mass-flow rate at 190°C / 2.16 kg of > 0.5 and < 2.0 g / 10 min; and wherein the layer (e) comprises an ethylene-based polymer F having a density of > 945 and < 970 kg / m3and a melt mass-flow rate of > 5.0 and < 10.0 g / 10 min, at 2.16 kg / 190°C.

[0014] Such film provides a desirable balance of good cling force, unwind force, peel off force and puncture resistance.24POLYOQ85-WO-ORD 4

[0015] The layer (a) may for example comprise > 90.0 wt% of the polymer A, preferably > 95.0 wt%, with regard to the total weight of the layer (a).

[0016] The layer (e) may for example comprise > 10.0 and < 60.0 wt%, preferably > 30.0 and < 60.0 wt%, with regard to the total weight of the layer (e), of the polymer F. The polymer F may be a high-density polyethylene (HDPE).

[0017] The layer (e) may for example comprise an ethylene-based polymer D, wherein the polymer D is a low-density polyethylene (LDPE) having a density of > 915 and < 930 kg / m3and a melt mass-flow rate of > 0.5 and < 5.0 g / 10 min, preferably of > 1.0 and < 3.0 g / 10 min.

[0018] The layer (c) may for example comprise the ethylene-based polymer B and / or a polypropylene polymer C. Preferably, the layer (c) comprises the polypropylene polymer C, more preferably the layer (c) comprises > 80 wt%, even more preferably > 90 wt%, of the polypropylene polymer C, with regard to the total weight of the layer (c).

[0019] The layer (a) may for example comprise an ethylene-based polymer E having a density of > 910 and < 930 kg / m3and a melt mass-flow rate at 190°C / 2.16 kg of > 1.5 and < 5.0 g / 10 min, preferably of > 2.1 and < 5.0 g / 10 min.

[0020] It is preferred that the layer (a) comprises > 90.0 wt% of the polymer A, preferably > 95.0 wt%, with regard to the total weight of the layer (a) and the layer (e) comprises > 10.0 and < 60.0 wt%, preferably > 30.0 and < 60.0 wt%, with regard to the total weight of the layer (e), of the polymer F. Such film exhibits a particular desirable balance of good cling force, unwind force, peel off force and puncture resistance. In particular, it is preferred that the layer (e) comprises > 30.0 and < 60.0 wt% of the polymer F.

[0021] The polymer A may for example be a copolymer of ethylene and a comonomer selected from 1-butene, 1-hexene and 1-octene, preferably wherein the polymer A comprises > 20.0 and < 45.0 wt% of moieties derived from the comonomer, more preferably > 25.0 wt% and < 40.0 wt%, even more preferably > 30.0 and < 40.0 wt%; more preferably, wherein the polymer A is a copolymer of ethylene and 1-octene, preferably comprising >20.0 and < 45.0 wt% of moieties derived from 1-octene, more preferably >25.0 and < 40.0 wt%, even more preferably > 30.0 and < 40.0 wt%.24POLY0085-WO-ORD 5

[0022] The polymer A may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature < 30.0°C of > 80.0 wt%, preferably > 90.0 wt%, more preferably > 95.0 wt%, with regard to the total weight of the polymer.

[0023] The polymer A may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 30.0°C and < 94°C of < 10.0 wt%, preferably < 5.0 wt%, more preferably < 2.0 wt%, with regard to the total weight of the polymer.

[0024] The polymer A may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 94.0°C of < 1.0 wt%, preferably < 0.5 wt%, more preferably < 0.1 wt%, with regard to the total weight of the polymer.

[0025] The polymer A may for example have a short-chain branching ratio (SCBR) of > 0.60 and < 1.20, preferably > 0.70 and < 1.00, more preferably > 0.70 and < 0.90, wherein SCBR is defined as:wherein SCB500 is the quantity of short chain branches (SCB) of the polyethylene at Mw=500,000 g / mol and SCB10 is the quantity of short chain branches of the polyethylene at Mw=10,000 g / mol, wherein the SCB quantity is determined via GPC-IR and expressed as the number of branches per 1000 carbon atoms ( / 1000C).

[0026] The polymer A may for example have a weight-average molecular weight (Mw) of > 50 and < 150 kg / mol, preferably of > 50 and < 120 kg / mol, more preferably of > 50 and < 100 kg / mol, even more preferably of > 60 and < 90 kg. mol. The polymer A may for example have a number-average molecular weight (Mn) of > 20 and < 50 kg / mol, preferably > 25 and < 40 kg / mol. The polymer A may for example have a z-average molecular weight (Mz) of > 150 and < 250 kg / mol, preferably of > 150 and < 200 kg / mol. The polymer A may for example have a molecular weight distribution Mw / Mnof > 2.0 and < 5.0, preferably > 2.0 and < 3.5, more preferably > 2.0 and < 3.0, even more preferably of > 2.5 and < 3.0.

[0027] The weight-average molecular weight, the number-average molecular weight and the z- average molecular weight may be determined in accordance with ASTM D6474 (2012).24POLYOQ85-WO-ORD 6

[0028] The polymer A may for example have a density of > 860 and < 880 kg / m3, preferably of > 870 and < 880 kg / m3, as determined in accordance with ASTM D792 (2013). The polymer A may for example have a melt mass-flow rate of > 4.0 and < 6.0 g / 10 min, preferably of > 4.5 and < 5.5 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 190°C and 2.16 kg load.

[0029] The polymer B may for example be a copolymer of ethylene and a comonomer selected from 1 -butene, 1 -hexene and 1 -octene, preferably wherein the polymer B comprises < 15 wt% of moieties derived from the comonomer, more preferably > 5.0 and < 15.0 wt%, even more preferably > 5.0 and < 10.0 wt%; more preferably, wherein the polymer B is a copolymer of ethylene and 1-hexene, preferably comprising < 15.0 wt% of moieties derived from 1-hexene, more preferably > 5.0 and < 15.0 wt%, even more preferably > 5.0 and < 10.0 wt%.

[0030] The polymer B may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature < 30.0°C of < 10.0 wt%, with regard to the total weight of the polymer, preferably < 5.0 wt%, more preferably > 1.0 and < 5.0 wt%.

[0031] The polymer B may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 30.0°C and < 94°C of > 50.0 and < 80.0 wt%, with regard to the total weight of the polymer, preferably > 55.0 and < 75.0 wt%, more preferably > 60.0 and < 75.0 wt%.

[0032] The polymer B may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 94.0°C of > 5.0 wt% and < 40.0 wt%, with regard to the total weight of the polymer, preferably > 15.0 and < 40.0 wt%, more preferably > 20.0 and < 40.0 wt%.

[0033] The polymer B may for example have a weight-average molecular weight (Mw) of > 50 and < 150 kg / mol, preferably > 100 and < 150 kg / mol. The polymer B may for example have a number-average molecular weight (Mn) of > 20 and < 50 kg / mol, preferably > 25 and < 40 kg / mol. The polymer B may for example have an Mzof > 200 and < 450 kg / mol, preferably of > 250 and < 400 kg / mol, more preferably of > 300 and < 400 kg / mol. The polymer B may for24POLYOQ85-WO-ORD 7 example have a molecular weight distribution Mw / Mnof > 2.0 and < 5.0, preferably > 2.5 and < 4.0, more preferably > 3.0 and < 4.0, even more preferably of > 3.5 and < 4.0.

[0034] The polymer B may for example have a density of > 915 and < 925 kg / m3, preferably of > 915 and < 920 kg / m3, more preferably of > 916 and < 919 kg / m3, as determined in accordance with ASTM D792 (2013). The polymer B may for example have a melt mass-flow rate of > 0.5 and < 1.5 g / 10 min, preferably of > 0.7 and < 1.2 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 190°C and 2.16 kg load.

[0035] The polymer C may for example be a random polypropylene copolymer. The polymer C may for example have a melt mass-flow rate of > 5.0 and < 25.0 g / 10 min, preferably of > 5.0 and < 15.0 g / 10 min, more preferably of > 5.0 and < 10.0 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 230°C and 2.16 kg load. The polymer C may for example have a melt mass-flow rate of > 2.0 and < 5.0, as determined at 190°C at 2.16 kg load.

[0036] The polymer C may for example be a copolymer comprising moieties derived from propylene and moieties derived from one or more comonomers selected from ethylene, 1- butene, 1-hexene, and 1-octene. For example, the polymer C may comprise > 80.0 wt% of moieties derived from propylene and < 20.0 wt% of moieties derived from the one or more comonomers, with regard to the total weight of the polymer C, preferably > 90.0 wt% of moieties derived from propylene and < 10.0 wt% of moieties derived from the one or more comonomers, more preferably > 95.0 wt% of moieties derived from propylene and < 5.0 wt% of moieties derived from the one or more comonomers, even more preferably > 95.0 and < 99.0 wt% of moieties derived from propylene and >1 .0 and < 5.0 wt% of moieties derived from the one or more comonomers.

[0037] For example, the polymer C may be a copolymer comprising moieties derived from propylene and moieties derived from ethylene. For example, the polymer C may comprise > 80.0 wt% of moieties derived from propylene and < 20.0 wt% of moieties derived from ethylene, with regard to the total weight of the polymer C, preferably > 90.0 wt% of moieties derived from propylene and < 10.0 wt% of moieties derived from ethylene, more preferably > 95.0 wt% of moieties derived from propylene and < 5.0 wt% of moieties derived from ethylene, even more preferably > 95.0 and < 99.0 wt% of moieties derived from propylene and >1.0 and < 5.0 wt% of moieties derived from ethylene.24POLYOQ85-WO-ORD 8

[0038] The polymer C may for example have a weight-average molecular weight (Mw) of > 150 and < 350 kg / mol, preferably > 150 and < 300 kg / mol, more preferably of > 200 and < 300 kg / mol. The polymer C may for example have a number-average molecular weight (Mn) of > 30 and < 100 kg / mol, preferably > 40 and < 75 kg / mol, more preferably of > 50 and < 70 kg / mol. The polymer C may for example have an Mzof > 300 and < 750 kg / mol, preferably of > 400 and< 600 kg / mol, more preferably of > 500 and < 600 kg / mol. The polymer C may for example have a molecular weight distribution Mw / Mnof > 2.0 and < 6.0, preferably > 3.0 and < 5.0, more preferably > 4.0 and < 5.0.

[0039] The polymer E may for example be a copolymer of ethylene and a comonomer selected from 1 -butene, 1 -hexene and 1 -octene, preferably the polymer E is a copolymer of ethylene and 1-butene.

[0040] The polymer E may for example have a weight-average molecular weight (Mw) of > 50 and < 150 kg / mol, preferably > 75 and < 125 kg / mol. The polymer E may for example have a number-average molecular weight (Mn) of > 10 and < 50 kg / mol, preferably of > 15 and < 25 kg / mol. The polymer E may for example have an Mzof > 250 and < 500 kg / mol, preferable of > 300 and < 500 kg / mol, more preferably of > 400 and < 500 kg / mol. The polymer E may for example have a molecular weight distribution Mw / Mnof > 3.5 and < 10.0, preferably of > 4.0 and< 7.5, more preferably of > 4.0 and < 6.0.

[0041] The polymer E may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature < 30.0°C of < 15.0 wt%, with regard to the total weight of the polymer, preferably > 5.0 and < 15.0 wt%, more preferably > 7.5 and < 12.5 wt%.

[0042] The polymer E may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 30.0°C and < 94°C of > 50.0 and < 80.0 wt%, with regard to the total weight of the polymer, preferably > 60.0 and < 75.0 wt%, more preferably > 65.0 and < 75.0 wt%.

[0043] The polymer E may for example have a fraction of material that is eluted in analytical temperature rising elution fractionation (a-TREF) at a temperature > 94.0°C of > 10.0 wt% and < 40.0 wt%, with regard to the total weight of the polymer, preferably > 15.0 and < 30.0 wt%, more preferably > 15.0 and < 25.0 wt%.24POLYOQ85-WO-ORD 9

[0044] The polymer F may be a homopolymer or a copolymer of ethylene and 1 -butene or 1- hexene, for example wherein the polymer F may comprise < 10.0 wt% of polymer moieties derived from 1-butene or 1-hexene, preferably < 5.0 wt%, more preferably < 3.0 wt%. The polymer F may for example have an Mw / Mnof > 5.0 and < 20.0, preferably of > 5.0 and < 15.0, more preferably of > 5.0 and < 10.0. The polymer F may for example have an Mnof > 5.0 and < 30.0 kg / mol, preferably > 5.0 and < 20.0 kg / mol. The polymer F may for example have an Mwof > 50.0 and < 100.0 kg / mol, preferably of >60.0 and < 90.0 kg / mol. The polymer F may for example have an Mzof > 200 and < 500 kg / mol, preferably of > 250 and < 400 kg / mol, more preferably of > 250 and < 350 kg / mol. The polymer F may for example have a monomodal molecular weight distribution.

[0045] The polymer F may for example have a density of > 950 and < 970 kg / m3, preferably of > 955 and < 970 kg / m3, more preferably of > 960 and < 970 kg / m3.

[0046] The film according to the invention may for example have a thickness of > 5 and < 250 pm, preferably of > 10 and < 200 pm, more preferably of > 10 and < 100 pm.

[0047] In the film, the layer (a) may for example account for > 5.0 and < 15.0 wt%, with regard to the total weight of the film. The layer (b) may for example account for > 20.0 and < 40.0 wt%. The layer (c) may for example account for > 5.0 and < 25.0 wt%. The layer (d) may for example account for > 20.0 and < 40.0 wt%. The layer (e) may for example account for > 5.0 and < 15.0 wt%.

[0048] In an embodiment, the invention relates to a film wherein in the film;• the layer (a) accounts for > 5.0 and < 15.0 wt%; and / or• the layer (b) accounts for > 20.0 and < 40.0 wt%; and / or• the layer (c) accounts for > 5.0 and < 25.0 wt%, preferably > 5.0 and < 15.0 wt%,; and / or• the layer (d) accounts for > 20.0 and < 40.0 wt%; and / or• the layer (e) accounts for > 5.0 and < 15.0 wt%; each with regard to the total weight of the film.

[0049] In an embodiment, the invention relates to a film wherein in the film, the layer (c) accounts for > 5.0 and < 25.0 wt%, preferably > 5.0 and < 15.0 wt%, with regard to the total24POLY0085-WO-ORD 10 weight of the film, wherein the layer (c) comprises the polypropylene polymer C, more preferably the layer (c) comprises > 80 wt%, even more preferably > 90 wt%, of the polypropylene polymer C, with regard to the total weight of the layer (c).

[0050] The invention also relates to a package comprising goods, wherein the goods are wrapped with the film according to the invention to form the package. Such goods may for example be bulk goods. For example, the package may comprise silage.

[0051] In a certain embodiment, the invention also relates to the use of the film of the invention to improve the puncture resistance and / or the cling force and / or the unwind force and / or the peel-off strength of a silage package.

[0052] It is preferred that the film according to the present invention does not comprise polyisobutylene.

[0053] It is preferred that the film according to the present invention comprises as polymer materials only ethylene-based polymers and / or propylene-based polymers. In the context of the present invention, ethylene-based polymers are to be understood to be polymers of which the majority of polymer moieties, defined as the weight fraction of the polymer accounted for by such moieties, are derived from ethylene, and propylene-based polymers are to be understood to be polymers of which the majority of polymer moieties are derived from propylene.

[0054] It is preferred that the film of the present invention comprises at least 90 wt% of ethylene-based polymers and / or propylene-based polymers, with regard to the total weight of the film. More preferably, the film consists of ethylene-based polymers and / or propylene-based polymers, and non-polymeric film additives.

[0055] According to the invention, analytical temperature rising elution fractionation, also referred to as a-TREF, may be carried out using a Polymer Char Crystaf-TREF 300 equipped with stainless steel columns having a length of 15 cm and an internal diameter of 7.8 mm, with a solution containing 4 mg / ml of sample prepared in 1,2-dichlorobenzene stabilised with 1 g / l Topanol CA (1 ,1 ,3-tri(3-tert-butyl-4-hydroxy-6-methylphenyl)butane) and 1 g / l Irgafos 168 (tri(2,4-di-tert-butylphenyl) phosphite) at a temperature of 150°C for 1 hour. The solution may be further stabilised for 45 minutes at 95°C under continuous stirring at 200 rpm before analyses. For analyses, the solution was crystallised from 95°C to 30°C using a cooling rate of 0.1°C / min.24PGLY0085-WG-ORD 11Elution may be performed with a heating rate of 1°C / min from 30°C to 140°C. The set-up may be cleaned at 150°C. The sample injection volume may be 300 pl, and the pump flow rate during elution 0.5 ml / min. The volume between the column and the detector may be 313 pl. The fraction that is eluted at a temperature of <30.0°C may in the context of the present invention be calculated by subtracting the sum of the fraction eluted >30.0°C from 100%, thus the total of the fraction eluted < 30.0°C, and the fraction eluted >30.0°C to add up to 100.0 wt%.

[0056] Particularly, a-TREF may be carried out using a Polymer Char Crystaf-TREF 300 using a solution containing 4 mg / ml of the polymer in 1,2-dichlorobenzene, wherein the solution is stabilised with 1 g / l 1,1,3-tri(3-tert-butyl-4-hydroxy-6-methylphenyl)butane and 1 g / l tri(2,4-di- tert-butylphenyl) phosphite) at a temperature of 150°C for 1 hour, and further stabilised for 45 minutes at 95°C under continuous stirring at 200 rpm, wherein the prior to analyses the solution is crystallised from 95°C to 30°C using a cooling rate of 0.1°C / min, and elution is performed at a heating rate of 1°C / min from 30°C to 140°C, and wherein the equipment has been cleaned at 150°C.

[0057] In the context of the present invention, the SCB quantity is determined via infrareddetection gel permeation chromatography (GPC-IR). GPC-IR analysis may for example be performed using a chromatographer, such as a Polymer Char GPC-IR system, equipped with three columns of internal diameter 7.5 mm and 300 mm length, packed with of particles of 13 pm average particle size, such as Polymer Laboratories 13pm PLgel Olexis, operating at 160°C, equipped with an MCT IR detector, wherein 1 ,2,4-trichlorobenzene stabilised with 1 g / l butylhydroxytoluene may be used as eluent at a flow rate of 1 ml / min, with a sample concentration of 0.7 mg / ml and an injection volume of 200 pl, with molar mass being determined based on the universal GPC principle using a calibration made with PE narrow and broad standards in the range of 0.5-2800 kg / mol, Mw / Mn - 4 to 15 in combination with known Mark Houwink constants of PE-calibrant alfa = 0.725 and log K = -3.721. Short chain branching content was determined via IR determination of the intensity ratio of CH3(ICHS) to CH2(ICH2) coupled with a calibration curve. The calibration curve is a plot of SCB content (XSCB) as a function of the intensity ratio of ICH3 / ICH2. TO obtain a calibration curve, a group of polyethylene resins (no less than 5) (SCB Standards) were used. All these SCB Standards have known SCB levels and flat SCBD profiles. Using SCB calibration curves thus established, profiles of short chain branching distribution across the molecular weight distribution can be obtained for resins fractionated by the IR5-GPC system under exactly the same chromatographic conditions as for24POLY0085-WO-ORD 12 these SCB standards. A relationship between the intensity ratio and the elution volume is converted into SCB distribution as a function of MWD using a predetermined SCB calibration curve (i.e., intensity ratio of ICH3 / ICH2 VS. SCB content) and MW calibration curve (i.e., molecular weight vs. elution time) to convert the intensity ratio of ICH3 / ICH2 and the elution time into SCB content and the molecular weight, respectively.

[0058] The invention will now be illustrated by the following non-limiting examples.

[0059] In the context of the present invention, the below materials were used in the experiments.Table 1 : Materials used.24POLYOQ85-WO-ORD 13In table 1 , MFR2 is the melt mass-flow rate as determined according to ASTM D1238-13 at a temperature of 190°C and a load of 2.16 kg, except for the polypropylene, wherein as indicated the MFR2 was determined at 230°C and a load of 2.16 kg, as per polypropylene specifications.

[0060] Using the materials as listed in table 1 above, a number of 5-layer coextruded cast films were produced according to the formulations specified in table 2 below.Table 2: Film formulations4POLYOQ85-WO-ORD 1424POLY0085-WO-ORD 15

[0061] In table 2, WL is weight of the layer, in wt% with regard to the total weight of the film, and WM the weight% of the indicated material, with regard to the total composition of the particular layer.

[0062] Films according to the above formulations were produced on an SML 5-layer MiniCast line with an effective width of 1.5m. The SML MiniCast was equipped with four extruders creating an output up to 1 ,050 kg / h with up to 5 layers. The used extruders were: A: Diameter 090mm L / D-ratio 33, B / C / D: Diameter 060mm L / D-ratio 28. The used selector plug to determine the layer order was such that extruder B supplied the layer 1 , extruder A supplied the layers 2 and 4, extruder D supplied the layer 3, and extruder C supplied the layer 5. The line was equipped with a 1.5m die, manufactured by Cloeren Dies, USA. The chill roll had a diameter of 1.2 meters. The line was equipped with an edge trim refeeding system. The films were produced having a thickness of 25 pm on this line at a line speed of 300 m / min, at an output of approximately 900 kg / h. The film was produced at a temperature of about 280°C.

[0063] Of the films that were produced as above, properties were tested as indicated below.

[0064] The above tests were performed using an ESTL FTP-750 testing machine. The cling force is expressed in N / mm2; the unwind force is expressed in N; the puncture force is expressed in N; the ultimate tension force is expressed in N / 25 mm; the peel off force was determined using films of 100% strain and 200% strain, in N / 25 mm; the tear force is expressed in N / mm.

Claims

24POLYOQ85-WO-ORD 16Claims1. Multi-layer cast film comprising at least five layers, being:(a) a first outer layer;(b) a first intermediate layer(c) a core layer;(d) a second intermediate layer; and(e) a second outer layer; wherein the layers are present in this order; wherein the layer (a) comprises an ethylene-based polymer A having a density of < 890 kg / m3, preferably of > 850 and < 890 kg / m3, as determined in accordance with ASTM D792 (2013), and a melt mass-flow rate of > 3.0 and < 8.0 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 190°C and 2.16 kg load; wherein the layers (b) and (d) both comprise an ethylene-based polymer B having a density of > 910 and < 930 kg / m3and a melt mass-flow rate at 190°C / 2.16 kg of > 0.5 and < 2.0 g / 10 min; and wherein the layer (e) comprises an ethylene-based polymer F having a density of > 945 and < 970 kg / m3and a melt mass-flow rate of > 5.0 and < 10.0 g / 10 min, at 2.16 kg / 190°C.

2. Film according to claim 1 , wherein the layer (a) comprises > 90.0 wt% of the polymer A, preferably > 95.0 wt%, with regard to the total weight of the layer (a).

3. Film according to any one of claims 1-2, wherein the layer (e) comprises > 10.0 and < 60.0 wt%, preferably > 30.0 and < 60.0 wt%, with regard to the total weight of the layer (e), of the polymer F.

4. Film according to any one of claims 1-3, wherein the layer (e) comprises an ethylenebased polymer D, wherein the polymer D is a low-density polyethylene (LDPE) having a24POLYOQ85-WO-ORD 17 density of > 915 and < 930 kg / m3and a melt mass-flow rate of > 0.5 and < 5.0 g / 10 min, preferably of > 1.0 and < 3.0 g / 10 min.

5. Film according to any one of claims 1-4, wherein the layer (c) comprises the ethylenebased polymer B and / or a polypropylene polymer C.

6. Film according to any one of claims 1-5, wherein the layer (a) comprises an ethylenebased polymer E having a density of > 910 and < 930 kg / m3and a melt mass-flow rate at 190°C / 2.16 kg of > 1.5 and < 5.0 g / 10 min, preferably of > 2.1 and < 5.0 g / 10 min.

7. Film according to any one of claims 1-6, wherein the polymer A is a copolymer of ethylene and a comonomer selected from 1 -butene, 1 -copolymer of ethylene and a comonomer selected from 1-butene, 1-hexene and 1-octene, preferably wherein the polymer A comprises > 20.0 and < 45.0 wt% of moieties derived from the comonomer, more preferably > 25.0 wt% and < 40.0 wt%, even more preferably > 30.0 and < 40.0 wt%; more preferably, wherein the polymer A is a copolymer of ethylene and 1-octene, preferably comprising >20.0 and < 45.0 wt% of moieties derived from 1-octene, more preferably >25.0 and < 40.0 wt%, even more preferably > 30.0 and < 40.0 wt%.

8. Film according to any one of claims 1-7, wherein the polymer B is a copolymer of ethylene and a comonomer selected from 1-butene, 1-hexene and 1-octene, preferably wherein the polymer B comprises < 15 wt% of moieties derived from the comonomer, more preferably > 5.0 and < 15.0 wt%, even more preferably > 5.0 and < 10.0 wt%; more preferably, wherein the polymer B is a copolymer of ethylene and 1-hexene, preferably comprising < 15.0 wt% of moieties derived from 1-hexene, more preferably > 5.0 and < 15.0 wt%, even more preferably > 5.0 and < 10.0 wt%.

9. Film according to any one of claims 1-8, wherein the polymer C is a random polypropylene copolymer, and / or wherein the polymer C has melt mass-flow rate of > 5.0 and < 25.0 g / 10 min, preferably of > 5.0 and < 15.0 g / 10 min, more preferably of > 5.0 and < 10.0 g / 10 min, as determined in accordance with ASTM D1238 (2013) at 230°C and 2.16 kg load.

10. Film according to any one of claim 1-9, wherein the polymer E is a copolymer of ethylene and a comonomer selected from 1-butene, 1-hexene and 1-octene, preferably wherein the polymer E is a copolymer of ethylene and 1-butene.24POLYOQ85-WO-ORD 1811. Film according to any one of claims 1-10, wherein• the polymer F has an Mw / Mnof > 5.0 and < 20.0, preferably of > 5.0 and < 15.0, more preferably of > 5.0 and < 10.0, and / or• the polymer F is a homopolymer or a copolymer of ethylene and 1-butene or 1- hexene, preferably wherein the polymer F may comprises < 10.0 wt% of polymer moieties derived from 1-butene or 1 -hexene, more preferably < 5.0 wt%, even more preferably < 3.0 wt%.

12. Film according to any one of claims 1-11 , wherein the film has a thickness of > 5 and < 250 pm, preferably of > 10 and < 200 pm, more preferably of > 10 and < 100 pm.

13. Film according to any one of claims 1-12 wherein in the film;• the layer (a) accounts for > 5.0 and < 15.0 wt%; and / or• the layer (b) accounts for > 20.0 and < 40.0 wt%; and / or• the layer (c) accounts for > 5.0 and < 25.0 wt%; and / or• the layer (d) accounts for > 20.0 and < 40.0 wt%; and / or• the layer (e) accounts for > 5.0 and < 15.0 wt%; each with regard to the total weight of the film.

14. Package comprising goods, wherein the goods are wrapped with the film according to any one of the claims 1-13 to form the package, preferably wherein the package comprises silage.

15. Use of the film according to any one of the claims 1-13 to improve the puncture resistance and / or the cling force and / or the unwind force and / or the peel-off strength of a silage package.

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