Film

Abstract

The present invention provides a uniaxially oriented multilayer film comprising at least a sealing layer, a core layer and an outer layer wherein at least one of the layers, preferably the sealing layer, comprises a metallocene catalyzed multimodal polyethylene terpolymer having a density in the range of 910 kg / m3 to 916 kg / m3 and an MFR2 (190 DEG C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min.

Description

[0001] The present invention relates to a uniaxially oriented film having beneficial mechanical and processing properties. In particular, the present invention relates to a uniaxially oriented film wherein at least one layer comprises a metallocene-catalyzed multimodal polyethylene terpolymer. The present invention also relates to the use of a metallocene-catalyzed multimodal polyethylene terpolymer in the production of a uniaxially oriented film. Background Art

[0002] Polymer films are widely used in packaging. These films must clearly protect the package contents from damage and environmental influences.

[0003] Polyethylene films are widely used in packaging due to their excellent cost-performance ratio. However, due to the increasing demand for films, multi-layer packaging using different types of polymers is often adopted. Although these materials can provide attractive properties, such materials are difficult to recycle. Therefore, pure materials are preferred. In this case, packaging using 'single material' is widely popular. However, this places higher requirements on the performance of the material itself.

[0004] Therefore, there is a need to produce multilayer films that provide opportunities for convenient recycling while having an attractive balance of properties, for example, multilayer materials with balanced sealability, rigidity and toughness are highly desirable.

[0005] To solve this problem, machine direction oriented polyethylene (MDO PE) or biaxially oriented polyethylene film (BOPE) can be used instead of PET film, which is often used due to its attractive properties. HDPE is a good alternative to PET in terms of stiffness and heat resistance. The resulting material contains only polyethylene and is therefore fully mechanically recyclable.

[0006] WO 2019 / 108326 describes a multilayer film comprising a machine direction oriented (MDO) substrate and a sealant, wherein the substrate has at least three layers. The core layer is described as comprising two polyethylenes, and at least one other layer comprises a third polyethylene.

[0007] WO 2018 / 071250 relates to machine direction oriented polymer films, wherein at least one layer comprises an ethylene-based polymer having a specific set of properties.

[0008] The present inventors have surprisingly found that a uniaxially oriented film comprising outer layers, a core layer and a sealant layer, wherein at least one of these layers comprises a specific type of multimodal polyethylene terpolymer, has a good balance of mechanical, optical and sealant properties. Summary of the invention

[0009] From one aspect, the present invention provides a uniaxially oriented multilayer film comprising at least a seal layer, a core layer and an outer layer, wherein at least one of the layers comprises a density of 910 kg / m3 Up to 916kg / m 3 and a metallocene-catalyzed multimodal polyethylene terpolymer having an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min.

[0010] Viewed from another aspect the invention provides an article, preferably a packaging article, comprising a uniaxially oriented film as hereinbefore defined.

[0011] From another aspect, the present invention provides a density of 910kg / m 3 Up to 916kg / m 3 and MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min in the production of a uniaxially oriented film as defined above.

[0012] Detailed description

[0013] definition

[0014] When the term "comprising" is used in the present description and claims, it does not exclude other not specifically stated elements of major or minor functional importance. For the purposes of the present invention, the term "consisting of" is regarded as a preferred embodiment of the term "comprising of". If hereinafter a group is defined as comprising at least a certain number of embodiments, this should also be understood to disclose a group that preferably consists of only these embodiments.

[0015] Whenever the terms "including" or "having" are used, these terms are intended to be equivalent to "comprising" as defined above.

[0016] When referring to a singular noun, using an indefinite or definite article, for example "a", "an" or "the", this includes a plural of that noun unless something else is specifically stated.

[0017] A metallocene-catalysed multimodal polyethylene terpolymer is defined in the present invention as a multimodal polyethylene terpolymer produced in the presence of a metallocene catalyst.

[0018] The term "multimodal" herein means that the ethylene polymer component and preferably the ethylene polymer fractions (A-1) and (A-2) are multimodal in terms of melt flow rate (MFR), i.e. the ethylene polymer components and / or fractions (A-1) and (A-2) have different MFR values. The multimodal polyethylene terpolymer may have further multimodality in terms of one or more other properties between the ethylene polymer components and between fractions (A-1) and (A-2), as described below.

[0019] The multimodal polyethylene terpolymer of the invention as defined above, below or in the claims is herein also referred to as "multimodal PE" or "multimodal terpolymer" for short.

[0020] The following preferred embodiments, properties and subgroups of the multimodal PE and its ethylene polymer components (A) and (B), as well as preferred ethylene polymer fractions (A-1) and (A-2) and the inventive films, including preferred ranges thereof, are independently generalizable such that they can be used in any order or combination to further define preferred embodiments of the multimodal PE and the inventive articles.

[0021] Metallocene-catalyzed multimodal polyethylene terpolymers

[0022] It has been found that the multimodal polyethylene terpolymer according to the invention provides an improved material for uniaxially oriented film applications combining very good sealing properties and mechanical properties (eg in terms of tensile modulus) with excellent optical properties (eg in terms of haze).

[0023] The polymer of the present invention is a multimodal polyethylene terpolymer. An ethylene terpolymer refers to a polymer derived mostly by weight from ethylene monomer units (i.e. at least 50 wt% ethylene relative to the total weight of the copolymer). The comonomer contribution is preferably at most 20 wt%, more preferably 5 to 18 wt%, e.g. 7 to 15 wt%, relative to the total weight of the copolymer.

[0024] The term "terpolymer" will be understood to mean that the polymer contains two comonomers in addition to ethylene. The other copolymerizable monomers are preferably C3-12, especially C3-10 alpha-olefin comonomers, especially mono- or polyethylenically unsaturated comonomers, especially C3-10 alpha-olefins, such as propylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. Particular preference is given to using two comonomers selected from 1-hexene, 1-octene and 1-butene, especially 1-hexene and 1-butene.

[0025] The polymer of the present invention is multimodal and therefore comprises at least two components. The polymer is preferably bimodal. The polymer of the present invention most preferably comprises

[0026] (A) a lower molecular weight ethylene copolymer component, and

[0027] (B) Higher molecular weight ethylene copolymer component.

[0028] The polyethylene terpolymer of the present invention is multimodal. Usually, a polyethylene composition comprising at least two polyethylene fractions, which are produced under different polymerization conditions, resulting in different (weight average) molecular weights and molecular weight distributions of the fractions, is called "multimodal". Thus, in this sense, the composition of the present invention is a multimodal polyethylene. The prefix "multi" is related to the number of different polymer fractions that make up the composition. The polyethylene may also be multimodal with respect to the comonomer content.

[0029] The form of the molecular weight distribution curve of such a multimodal polyethylene, ie a plot of the polymer weight fractions as a function of their molecular weight, will show two or more maxima, or at least will be significantly broadened compared to the curves for the individual fractions.

[0030] For example, if a polymer is produced in a continuous multi-stage process utilizing reactors in series and using different conditions in each reactor, the polymer fractions produced in the different reactors will each have different molecular weight distributions and weight average molecular weights. When a molecular weight distribution curve for such a polymer is recorded, the individual curves for these fractions are superimposed on the molecular weight distribution curve for the total resulting polymer product, typically resulting in a curve having two or more distinct maxima.

[0031] The MFR2 of the terpolymer of the present invention is 0.1 g / 10min to 2.5 g / 10min. The preferred range of MFR2 is 0.5 g / 10min to 2.0 g / 10min, such as 0.8 g / 10min to 1.5 g / 10min.

[0032] The MFR of the terpolymer of the present invention is 21 It is 15 g / 10 min to 80 g / 10 min, for example 20 g / 10 min to 70 g / 10 min, most preferably 25 g / 10 min to 60 g / 10 min.

[0033] The MFR of the terpolymer of the present invention is 21 The flow rate ratio (FRR) of MFR2 is preferably at least 15.0, such as at least 20.0, more preferably at least 25.0. In addition, the MFR 21 The flow rate ratio (FRR) of MFR / MFR2 is preferably at most 70.0, such as at most 55.0, more preferably at most 40.0.

[0034] According to ISO1183, the density of the terpolymer is 910kg / m 3 Up to 916kg / m3 Therefore, the terpolymer of the present invention is generally considered to be a linear low density polyethylene (LLDPE). Preferably, the density of the polymer is 911 kg / m 3 Up to 915kg / m 3 or more, more preferably 912kg / m 3 Up to 915kg / m 3 , for example 913kg / m 3 .

[0035] The terpolymer of the present invention is multimodal and thus comprises at least a lower molecular weight component (A) and a higher molecular weight component (B). In a particularly preferred embodiment, the terpolymer consists of components (A) and (B). The weight ratio of component (A) to component (B) in the composition is in the range of 30:70 to 70:30, more preferably 35:65 to 65:35, most preferably 40:60 to 60:40. In some embodiments, the ratio may be 35 wt% to 50 wt% of component (A) and 50 wt% to 65 wt% of component (B), for example 40 wt% to 50 wt% of component (A) and 50 wt% to 60 wt% of component (B), wherein the wt% values ​​are relative to the total weight of the multimodal polyethylene terpolymer.

[0036] In a particularly preferred embodiment, the wt % values ​​of components (A) and (B) add up to 100%.

[0037] Each of component (A) and component (B) is an ethylene copolymer. The term "ethylene copolymer" is as defined above.

[0038] The MFR2 (190°C, 2.16 kg, ISO 1133) of the lower molecular weight component (A) is typically 2.0 to 300 g / 10 min, preferably 2.0 to 200 g / 10 min, more preferably 2.8 to 150 g / 10 min, even more preferably 3.0 to 100 g / 10 min, e.g. 3.2 to 40 g / 10 min.

[0039] The density of component (A) is usually 915 kg / m 3 Up to 975kg / m 3 , preferably 920kg / m 3 Up to 960kg / m 3 , more preferably 930kg / m 3 Up to 950kg / m 3 , for example 933kg / m 3 Up to 942kg / m3 .

[0040] Component (A) is an ethylene copolymer. Preferred ethylene copolymers use α-olefins (e.g., C3-12 α-olefins) as comonomers. Examples of suitable α-olefins include 1-butene, 1-hexene, and 1-octene. 1-Butene is a particularly preferred comonomer.

[0041] The MFR2 of the higher molecular weight component (B) is typically 0.001 g / 10min to 1.5 g / 10min, preferably 0.01 g / 10min to 1.5 g / 10min, more preferably 0.05 g / 10min to 1.5 g / 10min, even more preferably 0.1 g / 10min to 1.2 g / 10min, e.g. 0.2 g / 10min to 1.0 g / 10min.

[0042] The density of component (B) is usually 880 kg / m 3 Up to 910kg / m 3 , preferably 885kg / m 3 Up to 905kg / m 3 , for example 890kg / m 3 Up to 900kg / m 3 .

[0043] Component (B) is a copolymer. Preferred ethylene copolymers use α-olefins (e.g., C3-12 α-olefins) as comonomers. Examples of suitable α-olefins include 1-butene, 1-hexene, and 1-octene. 1-Hexene is a particularly preferred comonomer.

[0044] In a particularly preferred embodiment, the terpolymer of the invention comprises, preferably consists of:

[0045] (i) 30.0 wt% to 70.0 wt% of an ethylene-1-butene polymer component (A), and

[0046] (ii) 70.0 wt% to 30.0 wt% of an ethylene-1-hexene polymer component (B).

[0047] The amounts of (A) and (B) preferably total 100.0 wt%.

[0048] In one embodiment of the present invention, the ethylene-1-butene polymer component (A) consists of ethylene polymer parts (A-1) and (A-2). In the case where the ethylene-1-butene polymer component (A) consists of ethylene polymer parts (A-1) and (A-2), the MFR2 of the ethylene polymer parts (A-1) and (A-2) may be different from each other.

[0049] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer portion (A-1) is generally in the range of 1.0 g / 10 min to 300 g / 10 min, preferably 1.0 g / 10 min to 200 g / 10 min, more preferably 1.5 g / 10 min to 150 g / 10 min, even more preferably 2.0 g / 10 min to 100 g / 10 min, particularly preferably 2.5 g / 10 min to 80 g / 10 min, for example 3.0 g / 10 min to 40 g / 10 min.

[0050] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer portion (A-2) may be in the range of 1.0 g / 10 min to 300 g / 10 min, preferably 3.0 g / 10 min to 40.0 g / 10 min, more preferably 3.2 g / 10 min to 30.0 g / 10 min, even more preferably 3.5 g / 10 min to 20.0 g / 10 min and most preferably 3.5 g / 10 min to 10.0 g / 10 min.

[0051] The MFR2 of the ethylene polymer components (A) and (B) are different from each other.

[0052] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer component (A) is preferably in the range of 2.0 g / 10min to 300 g / 10min, preferably 2.0 g / 10min to 200 g / 10min, more preferably 2.8 g / 10min to 150 g / 10min, even more preferably 3.0 g / 10min to 100 g / 10min, for example 3.2 g / 10min to 40 g / 10min.

[0053] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer component (B) is preferably in the range of 0.001 g / 10min to 1.5 g / 10min, preferably 0.01 g / 10min to 1.5 g / 10min, more preferably 0.05 g / 10min to 1.5 g / 10min, even more preferably 0.1 g / 10min to 1.2 g / 10min, for example 0.2 g / 10min to 1.0 g / 10min.

[0054] In one embodiment of the present invention, it is preferred that the ratio of the MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene-1-butene polymer component (A) to the MFR2 (190°C, 2.16 kg, ISO 1133) of the final multimodal terpolymer is from at least 2.5 to 300, preferably from 3.0 to 150, more preferably from 3.5 to 100.

[0055] Naturally, besides the multimodality with respect to, i.e. the difference between, the MFR2 of the ethylene polymer components (A) and (B), the multimodal PE of the present invention may also be multimodal, e.g. with respect to one or both of the other two properties:

[0056] Multimodality is about the difference between

[0057] - the comonomer content present in the ethylene polymer components (A) and (B); and / or

[0058] - the density of the ethylene polymer components (A) and (B).

[0059] Preferably, the multimodal terpolymer is further multimodal with respect to the comonomer content of the ethylene polymer components (A) and (B).

[0060] The comonomer content of components (A) and (B) can be measured, or, in the preferred case, one component is first produced and then the other component is produced in the presence of the first produced component in a so-called multi-stage process, then the comonomer content of the first produced component (e.g. component (A)) can be measured and the comonomer content of the other component (e.g. component (B)) can be calculated according to the following formula:

[0061] Comonomer content in component B (wt%) = (comonomer content in final product (wt%) - (weight fraction of component A * comonomer content in component A (wt%)) / (weight fraction of component B)

[0062] The total amount of 1-butene is preferably in the range of 0.1 to 4.0 wt%, more preferably 0.1 to 1.0 wt%, even more preferably 0.2 to 0.8 wt%, such as 0.3 to 0.6 wt%, based on the multimodal terpolymer.

[0063] The total amount of 1-hexene based on the multimodal terpolymer is preferably in the range of 2.0 to 20.0 wt%, preferably 4.0 to 18.0 wt%, more preferably 6.0 to 15.0 wt%.

[0064] The total amount (wt%) of 1-butene present in the ethylene-1-butene polymer component (A) is generally 0.1 to 10 wt%, preferably 0.5 to 5.0 wt%, more preferably 0.8 to 4.0 wt%, even more preferably 1.0 to 3.0 wt%, for example 1.0 to 2.0 wt%, based on the ethylene-1-butene polymer component (A).

[0065] The total amount (wt%) of 1-hexene present in the ethylene-1-hexene polymer component (B) is generally 15.0 to 25.0 wt%, preferably 16.0 to 22.0 wt%, more preferably 17.0 to 20.0 wt%, based on the ethylene-1-hexene polymer component (B).

[0066] Even more preferably, the multimodal terpolymer of the present invention is further multimodal with respect to the difference in density between ethylene copolymer component (A) and ethylene copolymer component (B). Preferably, the density of ethylene copolymer component (A) is different from, preferably higher than, the density of ethylene copolymer component (B).

[0067] The density of the ethylene copolymer component (A) is usually 915 kg / m 3 Up to 975kg / m 3 In the range of 920kg / m 3 Up to 960kg / m 3 , more preferably 930kg / m 3 Up to 950kg / m 3 , for example 933kg / m 3 Up to 942kg / m 3 , and / or the density of the ethylene polymer component (B) is usually 880 kg / m 3 Up to 910kg / m 3 In the range of 885kg / m 3 Up to 905kg / m 3 , for example 890kg / m 3 Up to 900kg / m 3 .

[0068] The density of the polymer part (A-1) is usually 920 kg / m 3 Up to 960kg / m 3 In the range of 925kg / m 3 Up to 955kg / m 3 , more preferably 930kg / m 3 Up to 950kg / m 3 , for example 935kg / m 3 Up to 945kg / m 3 .

[0069] The density of the polymer part (A-2) is preferably 930 kg / m 3 Up to 950kg / m 3 In the range of 935kg / m 3 Up to 945kg / m 3 .

[0070] Within the scope of the present invention, the first and second ethylene polymer parts (A-1 and A-2) of the ethylene polymer component (A) may be present in a weight ratio of 4:1 to up to 1:4, for example 3:1 to 1:3, or 2:1 to 1:2, or 1:1.

[0071] The ethylene polymer component (A) is present in an amount of 30.0 to 70.0 wt%, preferably 32.0 to 55.0 wt%, even more preferably 34.0 to 45.0 wt%, based on the multimodal terpolymer.

[0072] Thus, the ethylene polymer component (B) is present in an amount of 70.0 to 30.0 wt%, preferably 68.0 to 45.0 wt%, more preferably 66.0 to 55.0 wt%, based on the multimodal terpolymer.

[0073] Preparation of multimodal ethylene terpolymers catalyzed by metallocene

[0074] The metallocene-catalyzed multimodal terpolymers may be produced in a two-stage process, preferably comprising a slurry reactor (loop reactor), wherein the slurry (loop) reactor is connected in series with a gas phase reactor (GPR), wherein the low molecular weight polymer component is produced in the loop reactor and the high molecular weight polymer component is produced in the GPR in the presence of the low molecular weight polymer component to produce the multimodal terpolymer.

[0075] In case the ethylene component (A) of the multimodal terpolymer consists of ethylene polymer fractions (A-1) and (A-2), the multimodal terpolymer may be produced in a three stage process, preferably comprising a first slurry reactor (loop reactor 1), wherein the first slurry loop reactor is connected in series with a further slurry reactor (loop reactor 2), such that the first ethylene polymer fraction (A-1) produced in loop reactor 1 is fed to loop reactor 2, wherein the second ethylene polymer fraction (A-2) is produced in the presence of the first fraction (A-1). The loop reactor 2 is thereby connected in series with a gas phase reactor (GPR), such that the first ethylene copolymer fraction (A) leaving the second slurry reactor is fed to the GPR to produce a trimodal polyethylene copolymer. In this case, the reaction conditions in the two slurry reactors are selected such that products of different MFR and / or density are produced in the two slurry reactors.

[0076] Such processes are described inter alia in WO 2016 / 198273, WO 2021009189, WO 2021009190, WO 2021009191 and WO 2021009192. Full details of how to prepare suitable metallocene-catalyzed multimodal copolymers can be found in these references.

[0077] A suitable method is the Borstar PE method or the Borstar PE 3G method.

[0078] Therefore, the metallocene-catalyzed multimodal terpolymer according to the present invention is preferably prepared in a loop-loop gas cascade. This polymerization step may be preceded by a prepolymerization step. The purpose of the prepolymerization is to polymerize a small amount of polymer onto the catalyst at low temperature and / or low monomer concentration. By prepolymerization, the performance of the catalyst in the slurry can be improved and / or the properties of the final polymer can be changed. The prepolymerization step is preferably carried out in a slurry and the amount of polymer produced in the optional prepolymerization step is counted towards the amount (wt%) of the ethylene polymer component (A).

[0079] When there is a prepolymerization step, the catalyst components are preferably all introduced into the prepolymerization step. However, when the solid catalyst components and the cocatalyst can be fed separately, only a portion of the cocatalyst can be introduced into the prepolymerization stage, and the remainder into the subsequent polymerization stage. Also in this case, it is necessary to introduce so much cocatalyst into the prepolymerization stage in order to obtain a sufficient polymerization reaction therein.

[0080] It is understood that within the scope of the present invention the amount of polymer produced in the prepolymerisation is within 1 to 5 wt% relative to the final metallocene catalysed multimodal terpolymer. This can be counted as part of the first ethylene copolymer component (A).

[0081] catalyst

[0082] The metallocene-catalyzed multimodal terpolymer of the present invention is prepared using a metallocene catalyst. The metallocene catalyst comprises a metallocene complex and a cocatalyst. The metallocene compound or complex is also referred to herein as an organometallic compound (C).

[0083] The organometallic compound (C) comprises a transition metal (M) from Groups 3 to 10 of the Periodic Table of Elements (IUPAC 2007) or from the actinides or lanthanides.

[0084] According to the present invention, the term "organometallic compound (C)" includes any metallocene or non-metallocene compound of a transition metal, which carries at least one organic (coordinating) ligand and exhibits catalytic activity alone or together with a cocatalyst. Transition metal compounds are well known in the art, and the present invention encompasses compounds of metals of Groups 3 to 10, e.g. Groups 3 to 7 or Groups 3 to 6, e.g. Groups 4 to 6, of the Periodic Table of the Elements (IUPAC 2007), as well as compounds of lanthanides or actinides.

[0085] In one embodiment, the organometallic compound (C) has the following formula (I):

[0086]

[0087] Wherein each X is independently a halogen atom, C 1-6 Alkyl, C 1-6 alkoxy, phenyl or benzyl;

[0088] Each Het is independently a monocyclic heteroaromatic group containing at least one heteroatom selected from O or S;

[0089] L is -R'2Si-, wherein each R' is independently C 1-20 A hydrocarbon group or a C substituted alkoxy group having 1 to 10 carbon atoms 1-10 alkyl;

[0090] M is Ti, Zr or Hf;

[0091] Each R 1 Same or different, C 1-6 Alkyl or C 1-6 Alkoxy;

[0092] Each n is 1 to 2;

[0093] Each R 2 Same or different, C 1-6 Alkyl, C 1-6 Alkoxy or -Si(R)3 group;

[0094] Each R is C 1-10 Alkyl or optionally 1 to 3 C 1-6 Alkyl-substituted phenyl; and

[0095] Each p is from 0 to 1.

[0096] Preferably, the compound of formula (I) has the following structure:

[0097]

[0098] Wherein each X is independently a halogen atom, C 1-6 Alkyl, C 1-6 alkoxy, phenyl or benzyl;

[0099] L is Me2Si-;

[0100] Each R 1 Same or different, C 1-6 an alkyl group, such as methyl or tert-butyl;

[0101] Each n is 1 to 2;

[0102] R 2 is -Si(R)3 alkyl; each p is 1;

[0103] Each R is C1-6 Alkyl or phenyl.

[0104] Highly preferred complexes of formula (I) are

[0105]

[0106] Most preferably, the complex dimethylsilanediylbis[2-(5-trimethylsilylfuran-2-yl)-4,5-dimethylcyclopentadien-1-yl]zirconium dichloride is used.

[0107] More preferably, the high molecular weight and low molecular weight components of the multimodal terpolymer are produced using, ie in the presence of, the same metallocene catalyst.

[0108] To form the catalyst, a cocatalyst known in the art, also called an activator, is used. Cocatalysts containing Al or B are well known and can also be used here. Preferably, an aluminoxane (e.g. methylaluminoxane) or a boron-based cocatalyst (e.g. borates) is used.

[0109] In contrast to Ziegler Natta catalysis, polyethylene copolymers prepared using single-site catalysis have characteristics that distinguish them from Ziegler Natta materials. In particular, the comonomer distribution is more uniform. This can be shown using TREF or Crystaf techniques. Catalyst residues can also indicate the catalyst used. For example, Ziegler Natta catalysts do not contain Zr or Hf Group (IV) metals.

[0110] The metallocene-catalyzed multimodal ethylene terpolymer may contain other polymer components and optional additives and / or fillers. In case the metallocene-catalyzed multimodal terpolymer contains an additional polymer component, the amount of the additional polymer component typically varies between 3.0 and 20.0 wt%, based on the combined amount of the metallocene-catalyzed multimodal terpolymer and the other polymer components.

[0111] Optional additives and fillers and the amounts used are conventional in the field of film applications. Examples of such additives are, inter alia, antioxidants, processing stabilizers, UV stabilizers, pigments, fillers, antistatic additives, antiblocking agents, nucleating agents, acid scavengers and polymer processing aids (PPAs).

[0112] It is to be understood in the present context that any additive and / or filler may optionally be added to a so-called masterbatch comprising the respective additive and a carrier polymer. In this case, the carrier polymer is not included in the polymer component of the metallocene-catalyzed multimodal terpolymer but is included in the amount of the respective additive based on the total amount (100 wt%) of the polymer composition.

[0113] membrane

[0114] The film of the present invention is a uniaxially oriented film. Preferably, the film is oriented in the machine direction. The uniaxially oriented film of the present invention may have a thickness in the range of 5.0 μm to 100 μm, for example 10.0 μm to 75.0 μm, such as 15.0 μm to 50 μm or 20.0 μm to 40.0 μm.

[0115] The uniaxially oriented films of the present invention exhibit good optical properties in terms of haze transparency when measured according to ASTM D1003. The haze is typically 12.0% or less, such as 11.0 or 10.0% or less. The haze may be in the range of 2.0 to 12.0, preferably 5.0 to 11.0, more preferably 7.0 to 10.0. The haze is measured on a 20 μm film.

[0116] Furthermore, preferably, the tensile modulus (TM) of the film measured in the machine direction (MD) on a 20 μm film according to ISO 527-3 is 800 to 4000 MPa, more preferably in the range of 1100 to 3000 MPa, still more preferably in the range of 1200 to 2000 MPa.

[0117] The uniaxially oriented film preferably has a seal initiation temperature (SIT) of less than 115° C., more preferably less than 110° C. Ideally, the SIT will be at least 80° C., preferably at least 90° C.

[0118] The multilayer film of the present invention comprises at least a seal layer, a core layer and an outer layer, wherein at least one of the layers comprises a metallocene-catalyzed multimodal polyethylene terpolymer as described above. Thus, the film of the present invention comprises at least three layers, however the film may comprise more than three layers, for example 4 or 5 layers. When there are more than three layers, the additional layers are typically tie layers.

[0119] Preferably, the metallocene-catalyzed multimodal polyethylene terpolymer forms the sealing layer. In one embodiment of the invention, the sealing layer consists essentially of the multimodal terpolymer. The term "consisting essentially of" means that the polymer of the present invention is the only "non-additive" polyolefin present. However, it should be understood that such a polymer may contain standard polymer additives, some of which may be loaded on the polyolefin (so-called masterbatch well known in the art). The term "consisting essentially of" does not exclude the presence of such loaded additives.

[0120] Preferably, the sealant layer of the multilayer film of the invention comprises from 1.0 to 100 wt% of the multimodal terpolymer. In preferred alternatives, the sealant layer film may comprise at least 30.0 wt%, or at least 50.0 wt% or at least 70.0 wt% of the multimodal terpolymer. It is further preferred that such a layer comprises the multimodal terpolymer in the range of 30.0 to 99.0 wt%, for example 50.0 to 98.0 wt% or 70.0 to 90.0 wt%, relative to the total weight of the layer.

[0121] The outer layer of the multilayer film of the present invention preferably comprises a density of 945 kg / m 3 Up to 975kg / m 3 and a polyethylene having an MFR2 (190°C, 2.16 kg, ISO 1133) of 0.1 to 4.0 g / 10 min. The polyethylene in the outer layer may therefore be considered a high density polyethylene (HDPE) and may be a homopolymer or a copolymer, but is preferably an ethylene copolymer.

[0122] The other copolymerizable monomers or monomers are preferably C3-12, especially C3-10 alpha-olefin comonomers, especially mono- or polyethylenically unsaturated comonomers, especially C3-10 alpha-olefins such as propylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. Particularly preferably, 1-hexene, 1-octene and 1-butene or mixtures thereof, especially 1-hexene and 1-butene, are used. Ideally, only one comonomer is present.

[0123] The polyethylene in the outer layer may be unimodal or multimodal. Ideally, it is multimodal, thus comprising at least two components. It is preferably bimodal. The polyethylene in the outer layer most preferably comprises

[0124] (A) a lower molecular weight ethylene homopolymer component, and

[0125] (B) Higher molecular weight ethylene copolymer component.

[0126] The MFR2 of the polyethylene in the outer layer is typically from 0.2 g / 10min to 4.0 g / 10min. A preferred range of MFR2 is from 0.3 g / 10min to 2.5 g / 10min, such as from 0.5 g / 10min to 1.5 g / 10min.

[0127] The density of the polyethylene in the outer layer is usually 945kg / m 3 Up to 975kg / m 3 Preferably, the density of HDPE is 950 kg / m 3 Up to 965kg / m 3 , more preferably 953kg / m 3 Up to 963kg / m3 , for example 954kg / m 3 Up to 960kg / m 3 .

[0128] The molecular weight distribution (MWD) of the polyethylene in the outer layer may be in the range of 5-25, preferably 7-30, such as 10-20.

[0129] The polyethylene in the outer layer may be prepared in the presence of any suitable polymerization catalyst, such as a Ziegler-Natta or metallocene catalyst.

[0130] The core layer of the multilayer film of the present invention preferably comprises a density of 925 kg / m 3 Up to 945kg / m 3 Polyethylene having an MFR5 (190° C., 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min.

[0131] The MFR5 of the polyethylene in the core layer is typically from 0.1 g / 10min to 1.5 g / 10min. A preferred range of MFR5 is from 0.2 g / 10min to 1.2 g / 10min, such as from 0.5 g / 10min to 1.0 g / 10min.

[0132] The density of polyethylene in the core layer is usually 925kg / m 3 Up to 945kg / m 3 Preferably, the density of polyethylene is 927 kg / m 3 Up to 941kg / m 3 , more preferably 929kg / m 3 Up to 937kg / m 3 , even more preferably 929 kg / m 3 Up to 933kg / m 3 .

[0133] In one embodiment, the core layer (C) comprises bimodal ethylene / 1-butene / C6-C 12 α-olefin terpolymer.

[0134] Suitable terpolymers may comprise

[0135] (A-1) a low molecular weight homopolymer of ethylene, and

[0136] (A-2) Ethylene, 1-butene and C6-C 12 A high molecular weight terpolymer of an alpha-olefin, or

[0137] (B-1) Ethylene and 1-butene or C6-C 12 A low molecular weight copolymer of an alpha olefin, and

[0138] (B-2) high molecular weight copolymers of ethylene and 1-butene, if the low molecular weight polymer of (B-1) is ethylene and C6-C 12 Copolymers of alpha olefins, or ethylene, 1-butene and C6-C 12 Terpolymer of alpha olefins.

[0139] Therefore, if the low molecular weight polymer is ethylene and C6-C 12 The α-olefin copolymer or terpolymer comprises a high molecular weight component corresponding to the ethylene terpolymer of the higher α-olefin comonomer and a low molecular weight component corresponding to the ethylene homopolymer or a low molecular weight component corresponding to the ethylene copolymer and the high molecular weight ethylene-butene copolymer.

[0140] Preferably, the higher α-olefin comonomer is a C6-C8 olefin selected from 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. 12 of α-olefins.

[0141] More preferably, the polyethylene in the core layer is formed from ethylene homopolymer and ethylene butene / hexene terpolymer.

[0142] Such bimodal polymers can be prepared, for example, by two-stage polymerization or by using two different polymerization catalysts in one-stage polymerization. Dual-site catalysts can also be used. It is important to ensure that the higher and lower molecular weight components are intimately mixed before extrusion to form a film. This is most advantageously achieved by using a multistage process or dual-site, but can also be achieved by blending.

[0143] To maximize homogeneity, particularly when a blend is used, the multimodal polyethylene used in the core layer is preferably extruded prior to extrusion to form the film of the invention. This pre-extrusion step ensures that the higher molecular weight component will be evenly distributed in the core layer and minimizes the likelihood of gel formation in the film.

[0144] Preferably, the multimodal polyethylene is produced in a multistage polymerization using the same catalyst, such as a metallocene catalyst or preferably a Ziegler-Natta catalyst. Thus, two slurry reactors or two gas phase reactors may be used. However, preferably, the multimodal polyethylene is prepared using a slurry polymerization in a loop reactor followed by a gas phase polymerization in a gas phase reactor.

[0145] The loop reactor - gas phase reactor system is sold as the BORSTAR reactor system by Borealis A / S of Denmark.Thus, the multimodal polyethylene in the core layer is preferably formed in a two stage process comprising a first slurry loop polymerisation followed by a gas phase polymerisation in the presence of a Ziegler-Natta catalyst.

[0146] The conditions used in this method are well known. For slurry reactors, the reaction temperature is usually in the range of 60 to 110° C. (e.g. 85 to 110° C.), the reactor pressure is usually in the range of 5 to 80 bar (e.g. 50 to 65 bar), and the residence time is usually in the range of 0.3 to 5 hours (e.g. 0.5 to 2 hours). The diluent used is usually an aliphatic hydrocarbon with a boiling point in the range of -70 to +100° C. In such a reactor, if desired, the polymerization can be carried out under supercritical conditions. Slurry polymerization can also be carried out in bulk, wherein the reaction medium is formed by the monomers to be polymerized.

[0147] For gas phase reactors, the reaction temperature used is usually 60 to 115° C. (e.g. 70 to 110° C.), the reactor pressure is usually 10 to 25 bar, and the residence time is usually 1 hour to 8 hours. The gas used is usually a non-reactive gas such as nitrogen, or a low boiling hydrocarbon such as propane and a monomer (e.g. ethylene).

[0148] Preferably, the low molecular weight polymer fraction is produced in a continuously operated loop reactor in which ethylene is polymerized in the presence of a polymerization catalyst as described above and a chain transfer agent such as hydrogen.The diluent is typically an inert aliphatic hydrocarbon, preferably isobutane or propane.

[0149] The same catalyst can then be used to form the high molecular weight component in a gas phase reactor.

[0150] The bimodal terpolymer in one embodiment comprises a low molecular weight portion (LMW) of an ethylene homopolymer and ethylene, 1-butene and C6-C 12 The high molecular weight portion (HMW) of the terpolymer of α-olefins, in another embodiment, comprises ethylene and 1-butene or C6-C 12 The low molecular weight fraction (LMW) of the copolymer of α-olefins and the high molecular weight fraction of the copolymer of ethylene and 1-butene, if the low molecular weight polymer is ethylene and C6-C 12 α-olefin copolymers, or ethylene, 1-butene and C6-C 12 Terpolymer of alpha-olefins.

[0151] The expression "ethylene homopolymer" as used herein refers to a polyethylene consisting essentially of, ie at least 98 wt%, preferably at least 99 wt%, more preferably at least 99.5 wt%, most preferably at least 99.8 wt%, ethylene.

[0152] As mentioned above, the higher α-olefin comonomer is preferably a C6-C8 olefin selected from the group consisting of 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. 12 of α-olefins.

[0153] More preferably, 1-hexene or 1-octene, most preferably 1-hexene is used as the second comonomer in addition to 1-butene.

[0154] Such bimodal terpolymers are known in the prior art and are described, for example, in WO 03 / 066698 or WO 2008 / 034630.

[0155] Thus, suitable terpolymers for the core layer may comprise:

[0156] a) In a first embodiment, an ethylene homopolymer or ethylene and 1-butene or a C6-C 12 The low molecular weight fraction (LMW) of the binary copolymer of ethylene and 1-butene and the high molecular weight fraction (HMW) of the binary copolymer of ethylene and 1-butene, if the low molecular weight polymer of a) is ethylene and C6-C 12 A binary copolymer of α-olefins, or ethylene, 1-butene and C6-C 12 Terpolymer of alpha-olefins.

[0157] Preferably, the bimodal terpolymer according to this first embodiment comprises:

[0158] The low molecular weight fraction (LMW) of ethylene homopolymer or copolymer of ethylene and 1-butene and ethylene, 1-butene and C6-C 12 The high molecular weight portion (HMW) of the terpolymer of α-olefins.

[0159] The weight average molecular weight of the bimodal terpolymer according to the first embodiment is preferably between 80,000 and 400,000 g / mol, more preferably between 100,000 and 300,000 g / mol. The weight average molecular weight of the low molecular weight polymer fraction is preferably between 4,500 and 55,000 g / mol, more preferably between 5,000 and 50,000 g / mol, and the weight average molecular weight of the high molecular weight polymer is preferably between 150,000 and 1,000,000 g / mol, more preferably between 200,000 and 800,000 g / mol.

[0160] The molecular weight distribution of a polymer is further characterized by its melt flow rate (MFR) at 190°C according to ISO 1133. The melt flow rate depends primarily on the average molecular weight. This is because long, well-filled molecules give the material a lower flow tendency than short, less-filled molecules.

[0161] An increase in molecular weight means a decrease in the MFR value. The melt flow rate is measured in g / 10 min of polymer discharged under specified temperature and pressure conditions and is a measure of the viscosity of the polymer, which for each type of polymer is mainly affected by its molecular weight distribution, but also by its degree of branching, etc. The melt flow rate measured under a load of 2.16 kg (ISO 1133) is denoted as MFR2. Correspondingly, the melt flow rate measured with 21.6 kg is denoted as MFR 21 .

[0162] The melt flow rate MFR of the final bimodal terpolymer according to the first embodiment 21 It is preferably 7 g / 10 min to 60 g / 10 min, more preferably 10 g / 10 min to 50 g / 10 min, most preferably 15 g / 10 min to 45 g / 10 min.

[0163] The melt index MFR2 of the low molecular weight polymer is preferably 200 to 800 g / 10 min, more preferably 300 to 600 g / 10 min.

[0164] The density of the final bimodal terpolymer according to the first embodiment is typically 925 kg / m 3 Up to 945kg / m 3 Preferably, the density of polyethylene is 927 kg / m 3 Up to 941kg / m 3 , more preferably 929kg / m 3 Up to 937kg / m 3 , even more preferably 929 kg / m 3 Up to 933kg / m 3 .

[0165] The density of the low molecular weight polymer is preferably 940 kg / m 3 Up to 980kg / m 3 , more preferably 945kg / m 3 Up to 975kg / m 3 .

[0166] The amount of low molecular weight copolymer in the bimodal terpolymer is in the range of 30 to 60 wt%, preferably 35 to 50 wt%, most preferably 38 to 45 wt%.

[0167] The total comonomer content in the bimodal terpolymer according to the first embodiment is from 1 to 7 wt.-%, preferably from 2 to 6 wt.-%, and in the low molecular weight polymer the comonomer content is from 0 to 2.5 wt.-%, preferably from 0 to 2 wt.-%. In the high molecular weight polymer the comonomer content is from 2.5 to 11 wt.-%, preferably from 3 to 10 wt.-%.

[0168] Furthermore, the molecular weight of the high molecular weight copolymer fraction should be such that when the low molecular weight copolymer fraction has the melt index and density specified above, the final bimodal terpolymer has the above melt index and density.

[0169] b) In a second embodiment, low molecular weight homopolymers of ethylene and ethylene, 1-butene and C6-C 12 A high molecular weight trimer of alpha-olefins.

[0170] The weight average molecular weight of the bimodal terpolymer according to the second embodiment is from 100000 g / mol to 500000 g / mol, preferably from 200000 g / mol to 400000 g / mol. The weight average molecular weight of the low molecular weight polymer fraction is preferably from 4500 g / mol to 55000 g / mol, more preferably from 5000 g / mol to 50000 g / mol, and the weight average molecular weight of the high molecular weight polymer is preferably from 200000 g / mol to 1000000 g / mol, more preferably from 300000 g / mol to 800000 g / mol.

[0171] The melt flow rate MFR of the final bimodal terpolymer according to the second embodiment 21 It is preferably 2 g / 10 min to 35 g / 10 min, more preferably 3 g / 10 min to 30 g / 10 min. The melt index MFR2 of the low molecular weight polymer is preferably 300 g / 10 min to 1200 g / 10 min, more preferably 300 g / 10 min to 600 g / 10 min.

[0172] The density of the final bimodal terpolymer according to the second embodiment is preferably 935 kg / m 3 Up to 970kg / m 3 , more preferably 940kg / m 3 Up to 965kg / m 3 The density of the low molecular weight polymer is preferably 970 kg / m 3 Up to 980kg / m 3 , more preferably 972kg / m 3 Up to 978kg / m 3 , the most preferred is 975kg / m 3 .

[0173] The amount of low molecular weight copolymer in the bimodal terpolymer is in the range of 30 to 60 wt%, more preferably 35 to 50 wt%, most preferably 38 to 45 wt%.

[0174] The total comonomer content in the total polymer is from 0.3 to 3.0% by weight, preferably from 0.5 to 2.5% by weight, and in the high molecular weight polymer the comonomer content is from 0.5 to 3.5% by weight, preferably from 0.7 to 3.0% by weight.

[0175] Furthermore, the molecular weight of the high molecular weight copolymer fraction should be such that when the low molecular weight copolymer fraction has the melt index and density specified above, the final bimodal terpolymer has the above melt index and density.

[0176] c) In a third embodiment, ethylene and 1-butene or C6-C 12 The low molecular weight fraction (LMW) of the binary copolymer of α-olefin and the high molecular weight fraction (HMW) of the binary copolymer of ethylene and 1-butene, if the low molecular weight polymer is ethylene and C6-C 12 A binary copolymer of α-olefins, or ethylene, 1-butene and C6-C 12 Terpolymer of alpha-olefins.

[0177] The weight average molecular weight of the bimodal terpolymer according to the third embodiment is from 110000 g / mol to 210000 g / mol, preferably from 120000 g / mol to 200000 g / mol. The weight average molecular weight of the low molecular weight polymer fraction is preferably from 25000 g / mol to 110000 g / mol, more preferably from 30000 g / mol to 100000 g / mol, and the weight average molecular weight of the high molecular weight polymer is preferably from 100000 g / mol to 400000 g / mol, more preferably from 150000 g / mol to 370000 g / mol.

[0178] The melt flow rate MFR of the final bimodal terpolymer according to the third embodiment 21 It is preferably 15 to 80 g / 10 min, more preferably 20 to 70 g / 10 min. The melt index MFR2 of the low molecular weight polymer is preferably 1 to 50 g / 10 min, more preferably 2 to 20 g / 10 min.

[0179] The density of the final bimodal terpolymer according to the third embodiment is preferably 900 kg / m 3 Up to 935kg / m 3 , more preferably 915kg / m 3 Up to 930kg / m 3 , especially 920kg / m 3 Up to 925kg / m 3 The density of the low molecular weight polymer is preferably 925 kg / m 3 Up to 950kg / m3 , more preferably 930kg / m 3 Up to 940kg / m 3 .

[0180] The amount of low molecular weight copolymer in the bimodal terpolymer according to the third embodiment is in the range of 30 to 60 wt%, more preferably 35 to 50 wt%, most preferably 38 to 45 wt%.

[0181] According to a third embodiment, the total comonomer content in the total polymer is from 1 to 7% by weight, preferably from 2 to 6% by weight, and in the low molecular weight polymer, the comonomer content is from 0.5 to 3.5% by weight, preferably from 1 to 3% by weight. In the high molecular weight polymer, the comonomer content is from 3.5 to 10.5% by weight, preferably from 4 to 10% by weight.

[0182] Furthermore, the molecular weight of the high molecular weight copolymer fraction should be such that when the low molecular weight copolymer fraction has the melt index and density specified above, the final bimodal terpolymer has the above melt index and density.

[0183] In an alternative embodiment, the core layer may comprise a trimodal ethylene polymer comprising:

[0184] i) 10 to 30 wt% of a first ethylene homopolymer (PE1);

[0185] ii) 15 to 35 wt% of a second ethylene homopolymer (PE2) having an MFR2 at least 50 g / 10 min higher than the MFR2 of component i); and

[0186] iii) 45 to 65 wt% of a third ethylene copolymer (PE3) having at least one α-olefin comonomer.

[0187] The α-olefin in PE3 is preferably an α-olefin of 4 to 8 carbon atoms or a mixture thereof. In particular, 1-butene, 1-hexene and 1-octene and mixtures thereof are preferred α-olefins, with 1-butene and 1-hexene being particularly preferred.

[0188] If present, any further tie layer may comprise a polyethylene as defined above for the core layer, or a mixture of more than one of the polyethylenes defined for the core layer, or a mixture of a polyethylene defined for the core layer and a polyethylene defined for the outer layer.

[0189] If other polymers are present in any layer in addition to those polymers described above, it is preferred that any other polymer is polyethylene. Therefore, in a preferred embodiment, the uniaxially oriented film of the present invention is characterized by not containing any polymer other than polyethylene. Suitable polyethylenes that can be mixed include HDPE, MDPE, LLDPE, LDPE and ethylene-based plastomers and elastomers.

[0190] The uniaxially oriented film of the present invention may contain commonly used polymer additives, such as slip agents, UV stabilizers, pigments, antioxidants, nucleating agents, etc. These additives may be loaded on the carrier polymer in the form of a masterbatch.

[0191] For the avoidance of doubt, it is envisaged that even when each film layer is "consisting" of a specific polymer as defined above, conventional polymer additives (e.g. as described above) may be present. Thus, the term "consisting of" is not intended to exclude the presence of polymer additives. However, it excludes the presence of other polymer components used for blending. However, this is not excluded if a carrier polymer is used as part of a masterbatch. The article may not contain any other mixed polymers, but may still contain a small amount of the carrier polymer used for the masterbatch.

[0192] The outer layer, seal layer and core layer may all be of the same thickness, or alternatively, the core layer may be thicker than each of the seal layer and the outer layer. A convenient film comprises a seal layer and an outer layer, each forming 10 to 35%, preferably 15 to 30%, of the total thickness of the three-layer film, with the core layer forming the remaining thickness, e.g. 30 to 80%, preferably 40 to 70% of the total thickness of the three-layer film. The multilayer film of the invention may be symmetrical (the outer layer and seal layer have the same thickness) or asymmetrical (the outer layer and seal layer have different thicknesses).

[0193] The three-layer structure according to the present invention can be prepared by any conventional film extrusion procedure known in the art, including cast film and blown film extrusion. Preferably, the three-layer film is formed by blown film extrusion, more preferably by coextrusion methods, which are in principle known and available to ordinary technicians.

[0194] A typical method for preparing a three-layer structure according to the present invention is an extrusion method through an angle die, followed by blowing into a tubular film by forming bubbles that burst between rollers after solidification. The film can then be slid, cut or converted as required, for example by using a gazette head. Conventional film production techniques can be used in this regard. Typically, the core layer mixture and the mixture for the interlayer are coextruded at a temperature of 160 to 240° C. and cooled by blowing in a gas (usually air) at a temperature of 10 to 50° C. to provide a frost line height of 1 or 2 to 8 times the diameter of the dye. The blow-up ratio should generally be in the range of 1.5 to 4, for example 2 to 4, preferably 2.5 to 3.

[0195] If desired, any of the three layers of the three-layer structure of the present invention may contain conventional additives, such as stabilizers, processing aids, colorants, anti-blocking agents, slip agents, etc., in amounts that do not impair the desired functions of the three-layer structure. Typically, the total amount of additives in the layer is 7 wt% or less, preferably 5 wt% or less, and more preferably 3 wt% or less, based on the weight of the layer. In an embodiment, the layer may be completely free of any additives.

[0196] The three-layer structure identified in the present invention surprisingly exhibits an excellent balance of processability and stiffness as well as improved toughness.

[0197] The multilayer films of the present invention are preferably asymmetric, ie wherein the outer layer and the sealing layer are different.

[0198] The method for preparing the uniaxially oriented multilayer film of the present invention comprises at least the following steps: forming a layered film structure and stretching the obtained multilayer film in the machine direction, usually at a stretch ratio of at least 1:3. For the first step of the preparation method, the layered structure of the film of the present invention can be prepared by any conventional film forming method, including extrusion procedures, such as cast film or blown film extrusion. The multilayer film is ideally a blown film and is therefore preferably prepared by blown film extrusion.

[0199] Particularly preferably, the multilayer film of the present invention is formed by blown film extrusion, more preferably by a blown film coextrusion process. Typically, the composition providing the core layer, the seal layer and the outer layer will be blown (co)extruded at a temperature of 160 to 240°C and cooled by blowing in a gas (usually air) at a temperature of 10 to 50°C to provide a frost line height of 1 or 2 to 8 times the die diameter. The blow-up ratio should generally be in the range of 1.2 to 6, preferably 1.5 to 4.

[0200] The obtained, preferably coextruded, multilayer film is subjected to a subsequent stretching step, wherein the multilayer film is stretched in the machine direction. Stretching can be carried out by any conventional technique using any conventional stretching equipment well known to those skilled in the art. For example, the film can be coextruded to first form bubbles, which are then, if necessary, broken and cooled, and the obtained tubular film is stretched on the line. Stretching is preferably carried out at a temperature in the range of 70 to 90° C., for example about 80° C. Any conventional stretching rate can be used, for example 2 to 40% / second.

[0201] Preferably, the film is stretched only in MD. The effect of stretching in only one direction is to make the film uniaxially oriented. The film is stretched to at least 3 times, preferably 3 to 10 times, of its original length in the machine direction. This is expressed as a stretch ratio of at least 1:3 in this article, i.e., "1" represents the original length of the film, and "3" represents that it has been stretched to 3 times of the original length. The preferred film of the present invention is stretched with a stretch ratio of at least 1:4, more preferably 1:5 to 1:8, for example 1:5 to 1:7. The effect of stretching (or traction) is that the thickness of the film is similarly reduced. Therefore, a stretch ratio of at least 1:3 preferably also means that the thickness of the film is at least three times less than the original thickness. Blow extrusion and stretching techniques are well known in the art, such as in EP-A-299750.

[0202] The steps of the film preparation method of the present invention are known and can be carried out in a film production line in a manner known in the art. Such film lines are commercially available. The final uniaxially oriented MD film can be further processed, for example laminated on a substrate. However, preferably, the film is used in non-laminated film applications.

[0203] The films of the present invention have a wide range of applications but are of particular interest in packaging.

[0204] Thus, viewed from another aspect, the invention provides an article, preferably a packaging article, comprising a uniaxially oriented multilayer film as hereinbefore defined.

[0205] The further optional layers are naturally chosen so that they do not adversely affect the inventive effect achieved with the three-layer structure according to the invention.Thus, depending on the desired end application, it is also possible to produce 5-layer or even 7-layer films using the three-layer structure of the invention.

[0206] However, the three-layer structure according to the present invention is preferably used as it is without being laminated to any other film material.

[0207] The uniaxially oriented films of the invention can be used for producing packaging articles such as bags, pouches, labels or lids, or other technical applications such as banknotes. The uniaxially oriented films of the invention are preferably used in applications related to food packaging.

[0208] The present invention will be further described in detail below by way of examples:

[0209] Unless otherwise defined, the following term definitions and determination methods apply to the above general description of the invention as well as the following examples.

[0210] Determination method

[0211] Melt flow rate (MFR)

[0212] Melt flow rate is according to ISO 1133 at 190 ° C and 2.16 kg (MFR2) or 5.0 kg (MFR5) or 21.6 kg (MFR 21 ) measured under load.

[0213] Calculate the MFR2 of components (A) and (B)

[0214] logA=x·logB+(1-x)·logC

[0215]

[0216] B = MFR2 of component (A)

[0217] C = MFR2 of component (B)

[0218] A = Final MFR2 of the multimodal polyethylene copolymer (P) (blend)

[0219] X = weight fraction of component (A)

[0220] Flow rate ratio (FRR21 / 2)

[0221] FRR is determined as MFR 21 and MFR2.

[0222] GPC

[0223] The average molecular weights (Mz, Mw and Mn), the molecular weight distribution (MWD) and their breadth, described by the polydispersity index, PDI = Mw / Mn (wherein Mn is the number average molecular weight and Mw is the weight average molecular weight), are determined by gel permeation chromatography (GPC) according to ISO 16014-1:2003, ISO 16014-2:2003, ISO 16014-4:2003 and ASTM D 6474-12 using the following formula:

[0224]

[0225] For a constant elution volume interval ΔV i , where A i and M i and elution volume V iThe associated chromatographic peak slice area and the polyolefin molecular weight (MW), where N is equal to the number of data points between the upper and lower integration limits obtained from the chromatogram.

[0226] A high temperature GPC instrument was used, equipped with an infrared (IR) detector (IR4 or IR5 from PolymerChar (Valencia, Spain), equipped with 3 Agilent-PLgel Olexis columns and 1 Agilent-PLgel Olexis Guard column. As solvent and mobile phase, 1,2,4-trichlorobenzene (TCB) stabilized with 250 mg / L of 2,6-di-tert-butyl-4-methylphenol was used. The chromatographic system was operated at 160°C and a constant flow rate of 1 mL / min. 200 μL of sample solution was injected for each analysis. Data collection was performed using Agilent Cirrus software version 3.3 or PolymerChar GPC-IR control software.

[0227] The column set was calibrated using universal calibration (according to ISO 16014-2:2003) and 19 narrow MWD polystyrene (PS) standards in the range of 0,5 kg / mol to 11 500 kg / mol. The PS standards were dissolved at room temperature for several hours. The conversion of polystyrene peak molecular weight to polyolefin molecular weight was done by using the Mark Houwink equation and the following Mark Houwink constants:

[0228] K PS =19x10 -3 mL / g,α PS =0.655

[0229] K PE =39x10 -3 mL / g,α PE =0.725

[0230] K PP =19x10 -3 mL / g,α PP =0.725

[0231] A third-order polynomial fit was used to fit the calibration data.

[0232] All samples were prepared in the concentration range of 0.5 mg / mL to 1 mg / mL and were heated at 160 °C with continuous gentle shaking for 2.5 h to dissolve PP or 3 h to dissolve PE.

[0233] Comonomer content

[0234] Quantitative analysis of microstructure by NMR spectroscopy

[0235] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

[0236] Quantification 13 C{ 1 H} NMR spectra were recorded in the molten state using a Bruker Advance III 500 NMR spectrometer at 500.13 MHz and 125.76 MHz, respectively. 1 H and 13 C. All spectra were taken using 13 A C-optimized 7 mm magic angle spinning (MAS) probe was recorded at 150 °C, with nitrogen used for all pneumatics. Approximately 200 mg of material was loaded into a 7 mm outer diameter zirconium oxide MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. {klimke06, Parkinson07, Castignolles09} standard single pulse excitation was employed using a NOE with short recycle delay {pollard04, klimke06} and an RS-HEPT decoupling scheme {fillip05, griffin07}. A total of 1024 (1k) transients were acquired for each spectrum.

[0237] Quantitative 13 C{ 1 H} NMR spectra were processed, integrated, and relevant quantitative properties determined from the integration. All chemical shifts were internally referenced to the bulk methylene signal (+) at 30.00 ppm.

[0238] The amount of ethylene was quantified using a methylene (+) site integration of 30.00 ppm (accounting for the number of reported sites per monomer):

[0239] E=I δ+ / 2

[0240] Correction for the presence of independent comonomers is made based on the amount of independent comonomer present: Etotal = E + (3*B + 2*H) / 2

[0241] wherein B and H are defined with respect to their respective comonomers. If there is a correction for the incorporation of continuous and non-continuous comonomers, it is done in a similar manner.

[0242] Characteristic signals corresponding to 1-butene incorporation were observed, and the comonomer fraction was calculated as the fraction of 1-butene in the polymer relative to all monomers in the polymer:

[0243] fBtotal=(Btotal / (Etotal+Btotal+Htotal)

[0244] The amount of 1-butene isolated in the EEBEE sequence was quantified using a *B2 site integral of 38.3 ppm (accounting for the number of reported sites per comonomer):

[0245] B=I *B2

[0246] The amount of 1-butene continuously incorporated into the EEBBEE sequence was quantified using a B2B2 site integral of 39.4 ppm (accounting for the number of reported sites per comonomer):

[0247] BB=2*IααB2B2

[0248] The amount of 1-butene non-continuously incorporated into the EEBEBEE sequence was quantified using a B2B2 site integral of 24.7 ppm (accounting for the number of reported sites per comonomer):

[0249] BEB=2*IββB2B2

[0250] Since the *B2 and *B2B2 sites of isolated (EEBEE) and discontinuously incorporated (EEBEBEE) 1-butene, respectively, overlap, the total isolated 1-butene incorporation amount was corrected based on the discontinuous 1-butene incorporation amount:

[0251] B=I *B2 -2*I ββB2B2

[0252] The total 1-butene content is calculated as the sum of separated, continuously and discontinuously incorporated 1-butene:

[0253] Btotal=B+BB+BEB

[0254] The total mole fraction of 1-butene in the polymer is then calculated:

[0255] fB=(Btotal / (Etotal+Btotal+Htotal)

[0256] Characteristic signals corresponding to 1-hexene incorporation were observed, and the comonomer fraction was calculated as the fraction of 1-hexene in the polymer relative to all monomers in the polymer:

[0257] fHtotal=(Htotal / (Etotal+Btotal+Htotal)

[0258] The incorporation of isolated 1-hexene into the EEHEE sequence was quantified using a *B4 site integral of 39.9 ppm (accounting for the number of reported sites per comonomer):

[0259] H=I *B4

[0260] The continuous incorporation of 1-hexene in the EEHHEE sequence was quantified using a B4B4 site integral of 40.5 ppm (accounting for the number of reported sites per comonomer):

[0261] HH=2*IααB4B4

[0262] The non-continuous incorporation of 1-hexene in the EEHEHEE sequence was quantified using the integral of the B4B4 sites at 24.7 ppm (accounting for the number of reported sites per comonomer):

[0263] HEH=2*IββB4B4

[0264] The total mole fraction of 1-hexene in the polymer is then calculated:

[0265] fH=(Htotal / (Etotal+Btotal+Htotal)

[0266] The mole percentage of comonomer incorporation is calculated from the mole fraction:

[0267] B[mol%]=100*fB

[0268] H[mol%]=100*fH

[0269] The weight percent of comonomer incorporation is calculated from the mole fraction:

[0270] B[wt%]=100*(fB*56.11) / ((fB*56.11)+(fH*84.16)+((1-(fB+fH))*28.05))

[0271] H[wt%]=100*(fH*84.16) / ((fB*56.11)+(fH*84.16)+((1-(fB+fH))*28.05))

[0272] References:

[0273] Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.

[0274] Parkinson, M., Klimke, K., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128.

[0275] Pollard,M.,Klimke,K.,Graf,R.,Spiess,HW,Wilhelm,M.,Sperber,O.,Piel,C.,Kaminsky,W.,Macromolecules 2004;37:813.

[0276] Filip,X.,Tripon,C.,Filip,C.,J.Mag.Resn.2005,176,239

[0277] Griffin,JM,Tripon,C.,Samoson,A.,Filip,C.,and Brown,SP,Mag.Res.inChem.2007 45,S1,S198.

[0278] Castignolles,P.,Graf,R.,Parkinson,M.,Wilhelm,M.,Gaborieau,M.,Polymer50(2009)2373.

[0279] Busico,V.,Cipullo,R.,Prog.Polym.Sci.26(2001)443.

[0280] Busico,V.,Cipullo,R.,Monaco,G.,Vacatello,M.,Segre,AL,Macromoleucles30(1997)6251.

[0281] Zhou,Z.,Kuemmerle,R.,Qiu,X.,Redwine,D.,Cong,R.,Taha,A.,Baugh,D.Winniford,B.,J.Mag.Reson.187(2007)225.

[0282] Busico,V.,Carbonniere,P.,Cipullo,R.,Pellecchia,R.,Severn,J.,Talarico,G.,Macromol.Rapid Commun.2007,28,1128.

[0283] Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem.Rev.2000,100,1253.pdf

[0284] Density was measured according to ISO 1183 and ISO 1872-2 for sample preparation.

[0285] The density of the intermediate fraction produced in the presence of the preceding polymer fraction is calculated as follows:

[0286] ρ n =Σ(x i *ρ i ) n

[0287] where xi is the mass fraction (not mole fraction) of component i in the mixture, and ρ i is the density of component i in the mixture, ρ n is the density of the mixture.

[0288] Tensile modulus, tensile strength and elongation

[0289] Tensile modulus, tensile strength and elongation were measured in the machine direction and / or transverse direction according to ISO 527-3 on film samples prepared as described in Film Sample Preparation, with a film thickness of 20 μm and a cross head speed of 1 mm / min for modulus. For tensile strength and elongation, a cross head speed of 200 mm / min was used.

[0290] Haze and Clarity Haze and clarity, as a measure of the optical appearance of the film, were determined according to ASTM D1003 on film samples having a thickness of 20 μm.

[0291] Dart Drop Intensity (DDI): Impact resistance measured by the free-falling dart method

[0292] DDI was measured according to ISO 7765-1:1988 / Method A from films produced as shown below. This test method covers the determination of the energy to cause failure of a film under specified impact conditions of a free-falling dart from a specified height which would cause 50% of the test specimens to fail (Step Method A). Uniform missile mass increments were used during the test and after each sample test, the missile weight was reduced or increased by uniform increments depending on the result observed for the sample (failure or no failure).

[0293] Standard conditions:

[0294] Conditioning time: >96 hours

[0295] Test temperature: 23℃

[0296] Dart head material: phenolic resin

[0297] Dart diameter: 38mm

[0298] Drop height: 660mm

[0299] Sealing initiation temperature This method determines the sealing temperature range (sealing range) of polyethylene films, in particular blown films or cast films. The sealing temperature range is the temperature range over which the film can be sealed according to the conditions given below.

[0300] The lower limit (heat seal initiation temperature (SIT)) is the sealing temperature at which a seal strength of 5 N is achieved. The upper limit (seal end temperature (SET)) is reached when the film adheres to the sealing device.

[0301] The measurements were carried out according to a slightly modified ASTM F1921-12, where the test parameters sealing pressure, delay time and clamp separation rate have been modified. The force / temperature curve was continued until thermal failure of the film. The sealing range was determined on a J&B 4000 Universal Sealer using films produced as shown below, with an oriented film thickness of 20 μm and the following further parameters:

[0302] Conditioning time: >96 hours

[0303] Sample width: 25mm

[0304] Sealing pressure: 0.4N / mm 2 (PE)

[0305] Sealing time: 1 second

[0306] Delay time: 30 seconds

[0307] Sealing jaw size: 50×5mm

[0308] Sealing claw shape: flat

[0309] Sealing jaw coating: Niptef

[0310] Sealing temperature: ambient temperature to 240°C

[0311] Sealing temperature interval: 5°C

[0312] Starting temperature: 50℃

[0313] Clamp separation rate: 42mm / sec Example

[0314] Material:

[0315] LLDPE1: MFR5 is 0.9g / 10min, density is 931kg / m 3 FX1001, which is commercially available from Borealis.

[0316] HDPE1: density is 960kg / m 3, FB5600 having a MFR of 0.7 g / 10 min, which is commercially available from Borouge.

[0317] LLDPE2: MFR2 is 1g / 10min, density is 917.6kg / m 3 mLLDPE, which was produced using the polymerization parameters in Table 1.

[0318] LLDPE3: MFR2 is 1.3g / 10min, density is 912.7kg / m 3 mLLDPE, which was produced using the polymerization parameters in Table 1.

[0319] Table 1 shows typical polymerization parameters and final polymer properties of LLDPE2 and LLDPE3.

[0320] Table 1

[0321]

[0322]

[0323]

[0324] Membrane preparation

[0325] The 5-layer films before MDO were produced in the Alpine 7-layer line. They all had a starting film thickness of 120 μm, the melt temperature was fixed at 210 °C, and the BUR was 1:3. The details are as follows:

[0326] CE1:

[0327] Layer 1 – HDPE1, 12 μm;

[0328] Layer 2 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0329] Layer 3 - LLDPE1, 48 μm;

[0330] Layer 4 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0331] Layer 5 - LLDPE2, 12 μm

[0332] IE1:

[0333] Layer 1 – HDPE1, 12 μm;

[0334] Layer 2 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0335] Layer 3 - LLDPE1, 48 μm;

[0336] Layer 4 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0337] Layer 5 – LLDPE3, 12 μm

[0338] IE2:

[0339] Layer 1 – HDPE1, 12 μm;

[0340] Layer 2 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0341] Layer 3 - LLDPE1, 36 μm;

[0342] Layer 4 - 80% LLDPE1 + 20% HDPE1, 24 μm;

[0343] Layer 5 – LLDPE3, 24 μm

[0344] MDO was performed on a lab-scale Alpine MDO 20 machine at a ratio of 1:6 with a stretching roll temperature of 107 °C. Therefore, the total thickness of the final film was 20 μm. The properties of CE and IEs on MDO are shown in Table 2. It can be seen that IEs have a much lower SIT, while mechanical and optical remain at a good level.

[0345] Table 2

[0346]

[0347]

Claims

1. A uniaxially oriented multilayer film comprising at least a sealing layer, a core layer and an outer layer, wherein at least one of the layers, preferably the sealing layer, comprises a density of 910 kg / m 3 Up to 916kg / m 3 and a metallocene-catalyzed multimodal polyethylene terpolymer having an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min.

2. The uniaxially oriented film of claim 1, wherein the film is oriented in a machine direction.

3. The uniaxially oriented film according to claim 1 or 2, wherein the film is an asymmetric film, wherein the outer layer and the sealing layer have different thicknesses.

4. A uniaxially oriented film according to any one of claims 1 to 3, wherein the multimodal polyethylene terpolymer is a terpolymer of ethylene, butene and hexene.

5. The uniaxially oriented film according to claim 4, wherein the terpolymer comprises, preferably consists of: (i) 30.0 wt% to 70.0 wt% of an ethylene-1-butene polymer component, and (ii) 70.0 wt% to 30.0 wt% of an ethylene-1-hexene polymer component.

6. A uniaxially oriented film according to any one of claims 1 to 5, wherein the sealing layer comprises at least 50.0 wt%, preferably at least 70.0 wt% of the multimodal polyethylene terpolymer, relative to the total weight of the layer.

7. The uniaxially oriented film according to any one of claims 1 to 6, wherein the film comprises 3, 4 or 5 layers.

8. The uniaxially oriented film according to any one of claims 1 to 7, further comprising one or more tie layers.

9. The uniaxially oriented film according to any one of claims 1 to 8, wherein the outer layer comprises a density of 945 kg / m 3 Up to 975kg / m 3 Polyethylene having an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 4.0 g / 10 min.

10. The uniaxially oriented film according to any one of claims 1 to 9, wherein the core layer comprises a carbon fiber having a density of 925 kg / m 3 Up to 945kg / m 3 Polyethylene having an MFR5 (190° C., 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min.

11. The uniaxially oriented film according to any one of claims 1 to 10, wherein the film has a tensile modulus (TM) in the machine direction (MD) of 800 to 4000 MPa, measured on a 20 μm film according to ISO 527-3. 12 . The biaxially oriented film according to claim 1 , wherein the haze of the film is 12% or less as measured according to ASTM D1003 on a film sample having a thickness of 20 μm.

13. The uniaxially oriented film of any one of claims 1 to 12, wherein the film has a seal initiation temperature (SIT) of less than 115°C.

14. The uniaxially oriented film according to any one of claims 1 to 13, wherein the film is a blown film prior to stretching.

15. An article, preferably a packaging article, comprising the uniaxially oriented film according to any one of claims 1 to 14.

16. Density is 910kg / m 3 Up to 916kg / m 3 Use of a metallocene-catalyzed multimodal polyethylene terpolymer having an MFR (190°C, 2.16 kg, ISO 1133) in the range of 0.1 g / 10 min to 2.5 g / 10 min in the production of a uniaxially oriented film according to any one of claims 1 to 14.

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