Polyethylene copolymer for a film layer

Abstract

The present invention relates to a metallocene catalysed multimodal polyethylene copolymer (P), the use of the multimodal copolymer of ethylene (P) in film applications and a film comprising the polymer composition of the invention.

Description

TECHNICAL FIELD

[0001] The present invention relates to a metallocene catalysed multimodal polyethylene copolymer (P), the use of the multimodal polyethylene copolymer (P) in film applications and a film comprising the polymer composition of the invention. BACKGROUND

[0002] Monomodal polyethylene (PE) polymers, such as SSC products, are commonly used in film applications. Monomodal PE polymers have, for example, good optical properties (such as low haze), but, for example, the melt processing of such polymers is not satisfactory from a production point of view and can also lead to quality problems of the final product. Multimodal PE polymers having two or more different polymer components are easier to process, but, for example, the melt homogenization of the multimodal PE can be problematic, leading to a non-uniform final product, which is evidenced, for example, by a high gel content of the final product.

[0003] It is well known in the field of polyolefin production, particularly in the polymerization processes for producing bimodal or multimodal compositions, that the particle size of the polymer powder leaving the last reactor is a key feature.

[0004] In the case of the production of multimodal polyethylene in at least two reactors, it is often found that the largest particles discharged from the final polymerization reactor consist mainly of polymer produced in the reactor producing the highest molecular weight fraction (for example, this is usually the second reactor in a bimodal reaction). One problem with particles that are particularly large is that they can require more time than the residence time of the extruder for complete compounding in the extruder; thus, they exit the extruder as inhomogeneities in the compounded product, which can lead to gels or white spots.

[0005] Multimodal polyethylene is intrinsically difficult to homogenize due to the large difference in viscosity and the large difference in particle size of the various reactor powder particles. Particularly in sequential polymerization processes, the high molecular weight and high viscosity powder particles are typically significantly larger than the low molecular weight particles.

[0006] Furthermore, such large particles can also be the result of agglomeration.

[0007] Multimodal mLLDPE is known in the art.

[0008] WO 2021 / 009189 A, WO 2021 / 009190 A and WO 2021 / 009191 A of Borealis disclose a process for the production of a multimodal PE polymer in the presence of a metallocene complex based silica supported metallocene catalyst (bis(1-methyl-3-n-butylcyclopentadienyl)zirconium(IV) dichloride) in two loop reactors and one gas phase reactor.

[0009] The total density of the polymer produced in the examples was 938 or 939 kg / m 3 The MFR2(190°C, 2.16 kg, ISO 1133) of the polymer component produced in the first loop reactor was about 22 or 23 g / 10 min. The MFR2(190°C, 2.16 kg, ISO 1133) of the polymer component after the second loop reactor was not more than 31 g / 10 min.

[0010] WO 2021 / 009192 A also discloses such a process. The polymer produced in the examples has an even higher density of 951 kg / m 3 The MFR2(190°C, 2.16 kg, ISO 1133) of the polymer component produced in the first loop reactor was 32 g / 10 min. The MFR2(190°C, 2.16 kg, ISO 1133) of the polymer component after the second loop reactor was not more than 22 g / 10 min.

[0011] None of these patent applications describe the particle size distribution of the polymer powder leaving the gas phase reactor.

[0012] There is an ongoing need to find multimodal PE polymers which have a lower tendency to agglomerate in powder form and / or a lower amount of very large polymer particles, as these cause problems, in particular in the final product or in the polymerization process due to equipment blockage.

[0013] It is therefore an object of the present invention to provide a multimodal polyethylene composition which has an improved uniformity directly after its production, a lower tendency to agglomerate in powder form and / or a reduced amount of very large particles (i.e. particles having a particle size of more than 710 pm) in the polymer powder. SUMMARY

[0014] The present invention therefore relates to a metallocene catalyzed multimodal polyethylene copolymer (P) in powder form consisting of (i) 30.0 to 70.0 wt% of an ethylene polymer component (A), and (ii) 70.0 to 30.0 wt% of an ethylene polymer component (B),

[0015] wherein the ethylene polymer component (A) has

[0016] a density in the range of 925 to 960 kg / m 3 of 951 kg / m

[0017] an MFR2(190°C, 2.16 kg, ISO 1133) in the range of 10.0 to 300.0 g / 10 min,

[0018] wherein the ethylene polymer component (A) consists of ethylene polymer fractions (A-1 ) and (A-2),

[0019] The ethylene polymer component (B) has

[0020] a density in the range of 880 to 915 kg / m 3 ,

[0021] an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.001 to 1.0 g / 10 min, wherein the multimodal polyethylene copolymer (P) has

[0022] a density in the range of 905 to 916 kg / m 3 ,

[0023] an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 0.1 to 3.0 g / 10 min,

[0024] a ratio of MFR 21 (190°C, 21.6 kg, ISO 1133) to MFR2 (190°C, 2.16 kg, ISO 1133) (MFR 21 / MFR2) in the range of 33.0 to 80.0, and

[0025] a ratio of MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer component (A) to MFR2 (190°C, 2.16 kg, ISO 1133) of the multimodal polyethylene copolymer (P) (MFR2(A) / MFR2(P)) in the range of 7.5 to 200.0.

[0026] In one embodiment of the present application, the ethylene polymer component (A) of the metallocene-catalyzed multimodal polyethylene copolymer (P) consists of ethylene polymer fractions (A-1 ) and (A-2), wherein the fractions (A-1 ) and (A-2) have a density in the range of 925 to 960 kg / m 3 , an MFR2 (190°C, 2.16 kg, ISO 1133) in the range of 10.0 to 300 g / 10 min and wherein the density and / or the MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer fractions (A-1 ) and (A-2) can be the same or can be different.

[0027] Surprisingly, the multimodal polyethylene copolymer (P) of the present application in powder form (i.e. directly taken out of the reactor after the final polymerization step) has less particles having a particle size of more than 710 pm.

[0028] Definitions

[0029] Where the term "comprising" or "including" is used in the specification, it is taken to mean one or more entities in addition to those explicitly stated. For the avoidance of doubt, the term "consisting essentially of shall be considered to be a preferred embodiment of the term "comprising" or "including". If a group is defined in the following text as comprising at least a certain number of embodiments, this is also to be understood as disclosing a group which preferably consists only of these embodiments.

[0030] Whenever the terms "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above.

[0031] Whenever a singular noun is used with an indefinite or definite article, such as "a", "an" or "the", this includes the plural of the noun, unless otherwise specified.

[0032] The metallocene-catalysed multimodal polyethylene copolymer is defined in the present invention as a multimodal polyethylene copolymer (P) which is produced in the presence of a metallocene catalyst.

[0033] In the context of the multimodal polyethylene copolymer (P), the term "multimodal" refers herein to the multimodality of the melt flow rate (MFR) of the ethylene polymer components (A) and (B) and of the ethylene polymer fractions (A-1) and (A-2), i.e. the ethylene polymer components (A) and (B) and the fractions (A-1) and (A-2) have different MFR values. As described below, the multimodal polyethylene copolymer (P) can further have multimodality with respect to one or more other properties between the ethylene polymer components (A) and (B) and between the fractions (A-1) and (A-2).

[0034] The multimodal polyethylene copolymer (P) of the present invention as defined above, below or in the claims is also referred to herein simply as "multimodal PE" or "multimodal copolymer (P)".

[0035] The multimodal polyethylene copolymer (P) of the present invention as defined above, below or in the claims is the polymer which is withdrawn from the reactor after the final polymerisation step and is thus in powder form (before granulation).

[0036] The multimodal polyethylene copolymer (P) in powder form can further be combined with additives, followed by granulation, to obtain the multimodal polyethylene copolymer (P') in pellet form.

[0037] The preferred embodiments, properties, and subgroups of the following multimodal PE and its ethylene polymer components (A) and (B) and ethylene polymer portions (A-1) and (A-2), as well as the membranes of the present invention including their preferred ranges, are independently generalizable such that they can be used in any order or combination to further define the preferred embodiments of the multimodal PE and articles of the present invention.

[0038] Multimodal PE as well as ethylene polymer components (A) and (B) and ethylene polymer fractions (A-1) and (A-2)

[0039] The multimodal polyethylene copolymer (P) produced by metallocene is referred to herein as "multimodal" because the ethylene polymer component (A) includes ethylene polymer portions (A-1) and (A-2), and the ethylene polymer component (B) has been produced under different polymerization conditions, resulting in different melt flow rates (MFRs, e.g., MFR2). That is, multimodal PE is multimodal at least with respect to the difference in MFRs between the ethylene polymer components (A) and (B).

[0040] The multimodal polyethylene copolymer (P) produced by metallocene consists of (i) 30.0 to 70.0 wt% of ethylene-1-butene polymer component (A) and (ii) 70.0 to 30.0 wt% of ethylene-1-hexene polymer component (B).

[0041] The total amount of (A) and (B) is 100.0 wt%.

[0042] The ethylene polymer component (A) consists of ethylene polymer portions (A-1) and (A-2).

[0043] The ethylene polymer component (A) and the ethylene polymer (B) are preferably copolymers of ethylene and a comonomer selected from C4 to C12 α-olefins, more preferably C4 to C8 α-olefins, and still more preferably C4 to C6 α-olefins.

[0044] Preferably, the comonomer of ethylene polymer component (A) is different from the comonomer of ethylene polymer component (B).

[0045] Therefore, in one embodiment of the present invention, the ethylene polymer component (A) is an ethylene-1-butene polymer and the ethylene polymer component (B) is an ethylene-1-hexene polymer.

[0046] The MFR2 of the ethylene polymer portions (A-1) and (A-2) may be different from each other or may be the same.

[0047] The MFR2(190 °C, 2.16 kg, ISO 1133) of the ethylene polymer fractions (A-1) and (A-2) is in the range of 10.0 to 300.0 g / 10 min, preferably 15.0 to 250.0 g / 10 min, more preferably 20.0 to 200.0 g / 10 min, even more preferably 25.0 to 150.0 g / 10 min, still more preferably 30.0 to 100.0 g / 10 min.

[0048] The MFR2of the ethylene polymer fractions (A) and (B) differ from each other.

[0049] The MFR2(190 °C, 2.16 kg, ISO 1133) of the ethylene polymer fraction (A) is in the range of 10.0 to 300.0 g / 10 min, preferably 20.0 to 250.0 g / 10 min, more preferably 30.0 to 200.0 g / 10 min, even more preferably 35.0 to 100.0 g / 10 min.

[0050] The MFR2(190 °C, 2.16 kg, ISO 1133) of the ethylene polymer fraction (B) is in the range of 0.001 to 1.0 g / 10 min, preferably 0.002 to 0.9 g / 10 min, more preferably 0.003 to 0.8 g / 10 min, even more preferably 0.005 to 0.7 g / 10 min, still more preferably 0.01 to 0.5 g / 10 min.

[0051] The MFR2(190 °C, 2.16 kg, ISO 1133) of the multimodal copolymer (P) is in the range of 0.1 to 3.0 g / 10 min, preferably 0.2 to 2.5 g / 10 min, more preferably 0.4 to 2.0 g / 10 min, even more preferably 0.5 to 1.8 g / 10 min.

[0052] The MFR 21 (190 °C, 21.6 kg, ISO 1133) to the MFR2(190 °C, 2.16 kg, ISO 1133) ratio (MFR 21 / MFR2) is in the range of 33.0 to 80.0, preferably 34.0 to 60.0, more preferably 35.0 to 45.0.

[0053] Furthermore, the ratio of the MFR2(190 °C, 2.16 kg, ISO 1133) of the ethylene polymer fraction (A), preferably of the ethylene-1 -butene polymer fraction (A), to the MFR2(190 °C, 2.16 kg, ISO 1133) of the final multimodal copolymer (P) is at least 7.5 to 200.0, preferably 15.0 to 150.0, more preferably 20.0 to 100.0, still more preferably 25.0 to 50.0.

[0054] Of course, in addition to the multimodality with respect to the MFR2of the ethylene polymer components (A) and (B), i.e. the difference between them, the multimodal PE of the present application can also be multimodal with respect to, for example, one or both of two other properties:

[0055] - the type and / or content of comonomer present in the ethylene polymer components (A) and (B); and / or

[0056] - the density of the ethylene polymer components (A) and (B).

[0057] Preferably, the multimodal polymer (P) is further multimodal with respect to the type of comonomer of the ethylene polymer components (A) and (B).

[0058] As mentioned above, in a preferred embodiment of the present application, the ethylene polymer component (A) is an ethylene-1 -butene polymer and the ethylene polymer component (B) is an ethylene-1 -hexene polymer.

[0059] The type of comonomer of the polymer fractions (A-1 ) and (A-2) is the same, thus it is preferred that both fractions have 1 -butene as comonomer.

[0060] Even more preferably, the multimodal polymer (P) of the present application is further multimodal with respect to the difference in density between the ethylene polymer component (A) and the ethylene polymer component (B). Preferably, the density of the ethylene polymer component (A) is different, preferably higher, than the density of the ethylene polymer component (B).

[0061] The density of the ethylene polymer component (A) is in the range of 925 to 960 kg / m3, preferably 930 to 950 kg / m3, more preferably 935 to 950 kg / m3, and / or the density of the ethylene polymer component (B) is in the range of 880 to 915 kg / m3, preferably 885 to 910 kg / m3, even more preferably 890 to 905 kg / m3. 3 3 3 3 3 3

[0062] The density of the polymer fractions (A-1 ) and (A-2) is in the range of 925 to 960 kg / m3, preferably 928 to 955 kg / m3, more preferably 930 to 950 kg / m3, most preferably 935 to 945 kg / m3. 3 3 3 3

[0063] ​​​​​​​​​​The densities of the polymer fractions (A-1) and (A-2) can be the same or can differ from each other.

[0064] The metallocene-catalyzed multimodal copolymer (P) is preferably a linear low density polyethylene (LLDPE), which has the well-known meaning.

[0065] The density of the multimodal copolymer (P) is in the range of 905 to 916 kg / m3 3 , preferably 908.0 to 915 kg / m3 3 , more preferably 910.0 to 915.0 kg / m3 3 .

[0066] It is more preferred that the multimodal copolymer (P) is multimodal at least with respect to the MFR2, the type of comonomer (i.e. there is a difference between them) and with respect to the density (i.e. there is a difference) of the ethylene polymer fractions (A) and (B), as defined above, below or in the claims, including any preferred ranges or embodiments of the polymer composition.

[0067] Within the scope of the present application, the first and second ethylene polymer fractions (A-1 and A-2) of the ethylene polymer fraction (A) are present in a weight ratio of 4:1 to 1 :4, for example 3:1 to 1 :3, or 2:1 to 1 :2, or 1 :1.

[0068] The ethylene polymer fraction (A) is present in an amount of 30.0 to 70.0 wt%, preferably in an amount of 32.0 to 55.0 wt%, even more preferably in an amount of 34.0 to 45.0 wt%, based on the multimodal copolymer (P).

[0069] Thus, the ethylene polymer fraction (B) is present in an amount of 70.0 to 30.0 wt%, preferably in an amount of 68.0 to 45.0 wt%, more preferably in an amount of 66.0 to 55.0 wt%, based on the multimodal copolymer (P).

[0070] The metallocene-catalyzed multimodal copolymer (P) is in powder form, as it is directly withdrawn from the reactor after the final polymerization step.

[0071] The multimodal copolymer (P) has less particles having a particle size of more than 710 pm, i.e. the amount of particles having a particle size of more than 710 pm is below 6.0 wt%, preferably in the range of 0.1 to 5.0 wt%, more preferably in the range of 0.3 to 4.0 wt%, even more preferably in the range of 0.5 to 3.0 wt%, still more preferably in the range of 0.5 to 2.0 wt%, based on the total amount of particles.

[0072] The particle size is determined according to ASTM 1921 by sieve analysis.

[0073] In one embodiment of the present application the multimodal copolymer (P) preferably has a span of the particle size distribution of the polymer particles below 1.40, more preferably below 1.30, most preferably below 1.15. Suitably the lower limit of the particle size distribution is 0.5.

[0074] Particle size distribution (PSD) defined by SPAN: Span = (D90 - D10) / D50 determined by laser diffraction measurement with a Coulter LS200 according to ISO 13320.

[0075] The multimodal copolymer (P) can be produced with a three-stage process, which preferably comprises a first slurry reactor (loop reactor 1), wherein this first slurry loop reactor is connected in series to another slurry reactor (loop reactor 2), so that a first ethylene polymer fraction (A-1) produced in loop reactor 1 is fed into loop reactor 2, in which a second ethylene polymer fraction (A-2) is produced in the presence of the first fraction (A-1). Thus, loop reactor 2 is connected in series to a gas phase reactor (GPR), so that the first ethylene polymer component (A) leaving the second slurry reactor is fed to the GPR to produce a tri-modal polyethylene copolymer. In this case, the reaction conditions in the two slurry reactors are chosen so that products differing in MFR and / or density are produced in the two slurry reactors.

[0076] Such a process is described inter alia in WO 2016 / 198273, WO 2021009189, WO 2021009190, WO 2021009191 and WO 2021009192. All details on how to make suitable metallocene-catalyzed multimodal copolymers (P) can be found in these references.

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

[0078] Thus, the metallocene-catalyzed multimodal copolymer (P) according to the present application is preferably produced in a loop-loop-gas phase cascade. Such a polymerization step can 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 and / or the properties of the final polymer can be improved. This prepolymerization step is preferably carried out in the slurry and the amount of polymer produced in the optional prepolymerization step is counted as the amount (wt%) of the ethylene polymer component (A).

[0079] When a prepolymerization step is present, the catalyst components are preferably introduced in their entirety into the prepolymerization step. However, when the solid catalyst components and the co-catalyst can be fed separately, it is possible that only a part of the co-catalyst is introduced into the prepolymerization stage, while the remainder is introduced into the subsequent polymerization stage. Furthermore, in this case, it is necessary to introduce so much co-catalyst in the prepolymerization stage in order to obtain a sufficient polymerization reaction therein.

[0080] It will be appreciated that within the scope of the present application, the amount of polymer produced in the prepolymerization is within 1 to 5 wt% relative to the final metallocene-catalyzed multimodal copolymer (P). This can be counted as part of the first ethylene polymer component (A).

[0081] Catalyst

[0082] The metallocene-catalyzed multimodal copolymer (P) used in the process of the present application is prepared using a metallocene catalyst. The metallocene catalyst comprises a metallocene complex and a co-catalyst. The metallocene compound or complex is also referred to herein as the organometallic compound (C).

[0083] The organometallic compound (C) comprises a transition metal (M) of Group 3 to 10 or an actinide or lanthanide element of the Periodic Table (IUPAC 2007).

[0084] According to the present application, the term “organometallic compound (C)” includes any metallocene or non-metallocene compound of a transition metal, which carries at least one organic (coordination) ligand and exhibits catalytic activity alone or together with a co-catalyst. Transition metal compounds are well known in the art and the present application encompasses compounds from Groups 3 to 10, for example Groups 3 to 7, or Groups 3 to 6, for example Groups 4 to 6, of the Periodic Table (IUPAC 2007), as well as compounds of lanthanide or actinide metals.

[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 radical containing at least one heteroatom selected from O or S;

[0089] L is -R’2Si-, wherein each R’ is independently C 1-20 -hydrocarbyl or C 1-10 -alkyl;

[0090] M is Ti, Zr or Hf;

[0091] each R 1 is C 1-6 -alkyl or C 1-6 -alkoxy;

[0092] each n is 1 to 2;

[0093] each R 2 is C 1-6 -alkyl, C 1-6 -alkoxy or a -Si(R)3group;

[0094] each R is C 1-6 -alkyl or phenyl; and 1-10 -alkyl or phenyl; and

[0095] each p is 0 to 1.

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

[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 is C 1-6 -alkyl, for example methyl or tert-butyl;

[0101] each n is 1 to 2;

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

[0103] each R is C 1-6 -alkyl or phenyl.

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

[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 ethylene polymer components (A) and (B) of the multimodal copolymer (P) are prepared using the same metallocene catalyst, i.e. in the presence of the same metallocene catalyst.

[0108] For the formation of the catalyst, a co-catalyst, also called activator, is used, which is well known in the art. Co-catalysts comprising Al or B are well known and can be used here. Preferably, an aluminoxane (e.g. MAO) or a boron-based co-catalyst (e.g. borate) is used.

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

[0110] After the last reactor of the polymerization process, i.e. after the gas phase reactor, the metallocene-catalyzed multimodal copolymer (P) is collected in powder form, which can be combined with further polymer components and / or additives and / or fillers, followed by granulation, to obtain the multimodal copolymer (P) in the form of granules.

[0111] In case the metallocene-catalyzed multimodal copolymer (P) is compounded with further polymer components, the amount of the further polymer components typically varies between 3.0 and 20.0 wt%, based on the total amount of the metallocene-catalyzed multimodal copolymer (P) and the further polymer components.

[0112] The optional additives and fillers and their amounts are conventional in the field of film applications. Examples of such additives are, inter alia, antioxidants, process stabilizers, UV stabilizers, pigments, fillers, antistatic additives, antiblocking agents, nucleating agents, acid scavengers, and polymer processing aids (PPA).

[0113] It is to be understood here that any additive and / or filler can optionally be added in a so-called masterbatch, which comprises the respective additive and a carrier polymer. In this case, the carrier polymer is not calculated in the polymer components of the metallocene-catalyzed multimodal copolymer (P), but in the amount of the respective additive, based on the total amount of the polymer composition (100 wt%).

[0114] The multimodal copolymer (P’) in the form of granules can be used for the manufacture of films.

[0115] Film of the present invention

[0116] The film of the present application comprises at least one layer comprising a metallocene-catalysed multimodal copolymer (P') in the form of pellets. The film can be a monolayer film comprising the metallocene-catalysed multimodal copolymer (P') or a multilayer film wherein at least one layer comprises the metallocene-catalysed multimodal copolymer (P'). The terms "monolayer film" and "multilayer film" have well known meanings in the art.

[0117] The layer(s) of the monolayer or multilayer film of the present application can consist of the metallocene-catalysed multimodal copolymer (P') alone or of a blend of the metallocene-catalysed multimodal copolymer (P') with other polymers. In the case of a blend, any other polymer is different from the metallocene-catalysed multimodal copolymer (P') and is preferably a polyolefin. Part of the above mentioned additives, such as processing aids, can be optionally added to the metallocene-catalysed multimodal copolymer (P) during the film production process.

[0118] Preferably, the at least one layer of the present application comprises at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, still more preferably at least 80 wt% of the metallocene-catalysed multimodal copolymer (P') of the present application. Most preferably, the at least one layer of the film of the present application consists of the metallocene-catalysed multimodal copolymer (P').

[0119] Thus, the film of the present application can comprise a single layer (i.e. a monolayer) or can be multilayered. Multilayer films generally and preferably comprise at least 3 layers.

[0120] The film is preferably produced by any conventional film extrusion process known in the art, including cast film and blown film extrusion. Most preferably, the film is a blown or cast film, especially a blown film. For example, blown films are produced by extrusion through an annular die and blown into a tubular film by a bubble which is broken between nip rollers after solidification. The film can then be slit, cut or converted (e.g. folded) as required. Conventional film production techniques can be used in this regard. If the preferred blown or cast film is a multilayer film, then the layers are generally co-extruded. The skilled person will know suitable extrusion conditions.

[0121] The film according to the present application can be subjected to post-treatment processes, such as surface modification, lamination or orientation processes, etc. Such orientation processes can be mono-axial (MDO) or biaxial orientation, with mono-axial orientation being preferred.

[0122] In another preferred embodiment, the film is unoriented.

[0123] The resulting films can have any thickness conventional in the art. The thickness of the film is not critical and depends on the end use. Thus, the films can have a thickness of, for example, 300 pm or less, typically from 6 to 200 pm, preferably from 10 to 180 pm, for example from 20 to 150 pm or from 20 to 120 pm. If desired, the polymers of the present application enable thicknesses of less than 100 pm, for example less than 50 pm. Films of the present application can also be produced with thicknesses even less than 20 pm, while maintaining good mechanical properties.

[0124] Furthermore, the present application also relates to the use of the articles of the present application as packaging material, in particular as packaging material for food and / or medical products.

[0125] The present application will be further described with reference to the following non-limiting examples. DETAILED DESCRIPTION

[0126] Method of determination

[0127] Unless otherwise stated in the description or experimental section, the following methods were used for the determination of the properties of the polymers (including parts and components thereof) and / or any sample preparations thereof as described in the main text or experimental section.

[0128] Melt flow rate

[0129] The melt flow rate (MFR) was determined according to ISO 1133, expressed in g / 10 min. The MFR of the polyethylene was determined at 190 °C. The MFR can be determined at different loads, for example 2.16 kg (MFR2), 5 kg (MFR5) or 21.6 kg (MFR21). 21 ).

[0130] Calculation of MFR2 of component B and part (A-2)

[0131] log A = x • log B + (1 - x) • log C

[0132]

[0133] For component B:

[0134] B = MFR2 of component (A)

[0135] C = MFR2 of component (B)

[0136] A = final MFR2 (mix) of the multimodal polyethylene copolymer (P)

[0137] X = weight fraction of component (A)

[0138] For part (A-2):

[0139] B = MFR2 of the first fraction (A-1)

[0140] C = MFR2 of the second fraction (A-2)

[0141] A = final MFR2 (mix) of the cyclic polymer (= component (A))

[0142] X = weight fraction of the 1st fraction (A-1)

[0143] Density

[0144] The density of the polymer is determined according to ASTM; D792, method B (equilibrium density at 23°C) on compression moulded test specimens prepared according to EN ISO 1872-2, in kg / m 3 .

[0145] Particle size

[0146] The sieve analysis is performed according to ASTM 1921. The sieve analysis involves a nested column of sieves with wire mesh, the dimensions of which are as follows: > 20 pm, > 32 pm, > 63 pm, > 100 pm, > 125 pm, > 160 pm, > 200 pm, > 250 pm, > 315 pm, > 400 pm, > 500 pm, > 710 pm, > 1 mm, > 1.4 mm, > 2 mm, > 2.8 mm, > 4 mm.

[0147] The sample is poured into the top sieve with the largest mesh.

[0148] The openings of each lower sieve in the column are smaller than the openings of the upper sieves (see dimensions above). The bottom is a receptacle. The column is placed in a mechanical shaker. The shaker shakes the column. After the shaking is complete, the material on each sieve is weighed. The weight of the sample of each sieve is then divided by the total weight to obtain the percentage retained on each sieve.

[0149] Particle size distribution

[0150] Determined by Coulter LS 200 laser diffraction measurements

[0151] Particle size and particle size distribution are measures of the size of particles. D values (D10 (or d10), D50 (or d50), and D90 (or d90)) represent the intercepts of 10%, 50%, and 90% of the cumulative mass of the sample. The D values can be thought of as the diameter of a sphere that would divide the mass of the sample into a particular percentage when the particles are arranged in order of increasing mass. For example, D10 refers to the diameter at which 10% of the sample mass consists of particles with a diameter smaller than this value. D50 refers to the particle diameter at which 50% of the sample mass is smaller than this value and 50% of the sample mass is larger than this value. D90 is the diameter at which 90% of the sample mass consists of particles with a diameter smaller than this value. The D50 value is also referred to as the median particle size. Volume D values are obtained based on the volume distribution according to laser diffraction measurements according to ISO 13320.

[0152] The distribution width or span of the particle size distribution is calculated from the D values D10, D50, and D90 according to the following formula: Span = (D90 - D10) / D50

[0153] Unless otherwise specifically defined, percentage numbers used hereinafter refer to weight percentages.

[0154] Experimental section

[0155] Cat. Example: Catalyst (CAT1) preparation of IE1 and CE1

[0156] Loading of SiO2:

[0157] From the feed tank, 10 kg of silica (PQ Corporation ES757, calcined at 600 °C) was added and inertized in the reactor until the O2 level reached below 2 ppm.

[0158] Preparation of MAO / tol / MC:

[0159] From the metal cylinder, 477 g of metallocene rac- dimethylsilanediyl bis{2-(5-(trimethylsilyl)furan-2-yl)-4,5- dimethylcyclopentadien-1-yl}zirconium dichloride was added and rinsed with 4 kg of toluene (total amount of toluene 8.0 kg). The reactor stirring speed was changed to 95 rpm for MC feeding, back to 200 rpm and continued for 3 h reaction time. After the reaction time, the MAO / tol / MC solution was transferred to the feed container.

[0160] Preparation of catalyst:

[0161] The reactor temperature was set to 10 °C (oil circulation temperature) and stirred at a speed of 40 rpm to add the MAO / tol / MC. The MAO / tol / MC solution was added over 205 min (target 22.5 kg, actual 22.2 kg) and then the stirring time was 60 min (oil circulation temperature set to 25 °C). After stirring, the “dry mixture” was stabilized for 12 h at 25 °C (oil circulation temperature) with a stirring speed of 0 rpm. The reactor was turned 20° (back and forth) and stirred for several rounds per hour at a speed of 5 rpm.

[0162] After stabilization, the catalyst was dried at 60 °C (oil circulation temperature) under a nitrogen flow of 2 kg / h for 2 hours, followed by drying under vacuum for 13 hours (same nitrogen flow with stirring at 5 rpm). The dried catalyst was sampled and the HC content was measured in the glovebox using a Sartorius moisture analyzer (model MA45) using thermogravimetry. The target HC level was < 2% (actual 1.3%).

[0163] Polymerization: Inventive example: Inventive multimodal polyethylene copolymer (P) with 1-butene and 1-hexene comonomer

[0164] The Borstar pilot plant was equipped with a three reactor setup (Loop 1 - Loop 2 - GPR 1) and a prepolymerization loop reactor.

[0165] The inventive multimodal copolymer (P) of Example 1 (IE1) and the inventive multimodal copolymer (P) of Comparative Example (CE1) were produced by using the polymerization conditions given in Table 1.

[0166] Table 1: Polymerization conditions

[0167]

[0168]

[0169] The polymer powder received after the gas phase reactor was subjected to the respective analyses, the results of which are shown in Table 2.

[0170] Table 2: Material properties of the inventive multimodal copolymer (P) and the comparative copolymer in powder form

[0171] Materials CE1 IE1 MFR2(g / 10 min) (final) 1.0 1.3 MFR 21 (g / 10 min) 32.8 47.1 MFR 21 / MFR2]]> 32.5 37.4 MFR2(A) / MFR2(P) 6.8 34.1 Density (kg / m 3 )]]> 912 914 Particle size > 710 μm (wt%) 6.93 1.03 D90 (μm) 966.8 693.6 D10 (μm) 257.0 259.4 D50 (μm) 492.1 427.8 SPAN D90-D10 / D50 1.44 1.01

[0172] The particle size distribution of IE1 and CE1 obtained by sieving is shown in Figure 1 From the graph it can be seen that the PSD curve of CE1 has a tail, while IE1 does not.

[0173] The morphology (optical microscopy) of the CE1 powder (710 pm sieve) is shown in Figure 2, from which it can be seen that the "large particles" are not really grown-up powder, but agglomerates.

[0174] In contrast, Figure 3 shows the morphology of the IE1 powder (710 pm sieve).

[0175] The improvement in particle size and PSD is attributed to the specific design of the multimodal copolymer (P) of the present application.

Claims

1. A metallocene catalysed multimodal polyethylene copolymer (P) in powder form consisting of: (i) 30.0 to 70.0 wt% of an ethylene polymer component (A), and (ii) 70.0 to 30.0 wt% of an ethylene polymer component (B), wherein the ethylene polymer component (A) has a density in the range of 925 to 960 kg / m 3 a density in the range of 925 to 960 kg / m an MFR2 determined according to ISO 1133 at a load of 2.16 kg at 190 °C in the range of 10.0 to 300.0 g / 10 min, wherein the ethylene polymer component (A) consists of ethylene polymer fractions (A-1) and (A-2), the ethylene polymer component (B) has a density in the range of 880 to 915 kg / m 3 of the range of 880 to 915 kg / m an MFR2 determined according to ISO 1133 at a load of 2.16 kg at 190 °C in the range of 0.001 to 1.0 g / 10 min, wherein the multimodal polyethylene copolymer (P) has Between 905 and 916 kg / m 3 Density within a certain range an MFR2 determined according to ISO 1133 at a load of 2.16 kg at 190 °C in the range of 0.1 to 3.0 g / 10 min, MFR determined according to ISO 1133 at 190 °C under a load of 21.6 kg in the range of 33.0 to 80.0 21 ratio of the MFR determined according to ISO 1133 at 190 °C under a load of 2.16 kg, MFR 21 MFR2, and a ratio of the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C to the MFR2 of the multimodal polyethylene copolymer (P) determined according to ISO 1133 at a load of 2.16 kg at 190 °C, MFR2(A) / MFR2(P), in the range of 7.5 to 200.

0.

2. The metallocene-catalyzed multimodal polyethylene copolymer (P) according to claim 1, wherein portions (A-1) and (A-2) have a density of 925 to 960 kg / m³. 3 Within the range of 10.0 to 300 g / 10 min, the MFR2 measured at 190 °C under a load of 2.16 kg according to the method of ISO 1133 is in the range of 10.0 to 300 g / 10 min, and the densities of the ethylene polymer portions (A-1) and (A-2) and / or the MFR2 measured at 190 °C under a load of 2.16 kg according to the method of ISO 1133 are the same or different.

3. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the ethylene polymer component (A) and ethylene polymer (B) are copolymers of ethylene and a comonomer selected from C4 to C12 alpha-olefins. 12 alpha-olefins.

4. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 3, wherein the ethylene polymer component (A) and ethylene polymer (B) are copolymers of ethylene and a comonomer selected from C4 to C8 alpha-olefins.

5. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 3, wherein the ethylene polymer component (A) and ethylene polymer (B) are copolymers of ethylene and a comonomer selected from C4 to C6 alpha-olefins.

6. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 3, wherein the comonomer of the ethylene polymer component (A) is different from the comonomer of the ethylene polymer component (B).

7. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 3, wherein the ethylene polymer component (A) is an ethylene-1-butene polymer and the ethylene polymer component (B) is an ethylene-1-hexene polymer.

8. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein - the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 20.0 to 250.0 g / 10 min, and - the MFR2 of the ethylene polymer component (B) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 0.002 to 0.9 g / 10 min.

9. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 8, wherein the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 30.0 to 200.0 g / 10 min.

10. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 8, wherein the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 35.0 to 100.0 g / 10 min.

11. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 8, wherein the MFR2 of the ethylene polymer component (B) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 0.003 to 0.8 g / 10 min.

12. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 8, wherein the MFR2 of the ethylene polymer component (B) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 0.005 to 0.7 g / 10 min.

13. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the MFR 21 ratio of the MFR2determined according to the method of ISO 1133 at a load of 2.16 kg at 190 °C, MFR 21 / MFR2is in the range of 34.0 to 60.

0.

14. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 13, wherein the MFR 21 ratio of the MFR2 determined according to the method of ISO 1133 at a load of 2.16 kg at 190 °C, MFR 21 / MFR2, is in the range of 35.0 to 45.

0.

15. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the ratio of the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C to the MFR2 of the final multimodal polyethylene copolymer (P) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 15.0 to 150.

0.

16. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 15, wherein the ratio of the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C to the MFR2 of the final multimodal polyethylene copolymer (P) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 20.0 to 100.

0.

17. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 15, wherein the ratio of the MFR2 of the ethylene polymer component (A) determined according to ISO 1133 at a load of 2.16 kg at 190 °C to the MFR2 of the final multimodal polyethylene copolymer (P) determined according to ISO 1133 at a load of 2.16 kg at 190 °C is in the range of 25 to 50.

18. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the ethylene polymer component (A) is present in an amount of 32.0 to 55.0 wt.-% based on the multimodal polyethylene copolymer (P), and the ethylene polymer component (B) is present in an amount of 68.0 to 45.0 wt.-% based on the multimodal polyethylene copolymer (P).

19. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the ethylene polymer component (A) is present in an amount of 35.0 to 55.0 wt.-% based on the multimodal polyethylene copolymer (P), and the ethylene polymer component (B) is present in an amount of 65.0 to 45.0 wt.-% based on the multimodal polyethylene copolymer (P).

19. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 18, wherein the ethylene polymer component (A) is present in an amount of 34.0 to 45.0 wt% based on the multimodal polyethylene copolymer (P).

20. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 18, wherein the ethylene polymer component (B) is present in an amount of 66.0 to 55.0 wt% based on the multimodal polyethylene copolymer (P).

21. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the multimodal polyethylene copolymer (P) is produced in the presence of a metallocene complex of formula (I): (I) each Het is independently a monocyclic heteroaromatic radical containing at least one heteroatom selected from O or S; wherein each X is independently a halogen atom, C 1-6 - alkyl, C 1-6 - alkoxy, phenyl or benzyl; M is Ti, Zr or Hf; L is -R'2Si-, wherein each R' is independently C 1-20 - a hydrocarbon group or C 1-10 - an alkyl group; each n is 1 to 2; Each R 1 Same or different, is C 1-6 -alkyl or C 1-6 -alkoxy group; 22. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the amount of particles having a particle size greater than 710 pm, determined according to ASTM 1921 by sieve analysis, is below 6.0 wt% based on the total amount of particles. Each R 2 Same or different, is C 1-6 -alkyl, C 1-6 -alkoxy or -Si(R)3 group; each R is optionally substituted with 1 to 3 C 1-6 - alkyl substituted C 1-10 - alkyl or phenyl; and each p is 0 to 1.

23. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 22, wherein the amount of particles having a particle size greater than 710 pm, determined according to ASTM 1921 by sieve analysis, is 0.1 to 5.0 wt% based on the total amount of particles.

24. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 22, wherein the amount of particles having a particle size greater than 710 pm, determined according to ASTM 1921 by sieve analysis, is 0.3 to 4.0 wt% based on the total amount of particles.

25. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 22, wherein the amount of particles having a particle size greater than 710 pm, determined according to ASTM 1921 by sieve analysis, is 0.5 to 3.0 wt% based on the total amount of particles.

26. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 22, wherein the amount of particles having a particle size greater than 710 pm, determined according to ASTM 1921 by sieve analysis, is 0.5 to 2.0 wt% based on the total amount of particles.

27. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the particle size distribution (PSD) defined by SPAN: D90-D10 / D50 is below 1.40, wherein the particle size distribution (PSD) defined by SPAN is determined according to ISO 13320 by laser diffraction measurements with a Coulter LS200.

28. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 27, wherein the particle size distribution (PSD) defined by SPAN: D90-D10 / D50 is below 1.30, wherein the particle size distribution (PSD) defined by SPAN is determined according to ISO 13320 by laser diffraction measurements with a Coulter LS200. ​ 29. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 27, wherein the particle size distribution (PSD) defined by SPAN: D90-D10 / D50 is below 1.15, wherein the particle size distribution (PSD) defined by SPAN is determined by laser diffraction measurement according to ISO 13320 by a Coulter LS200.

30. The metallocene catalysed multimodal polyethylene copolymer (P) according to claim 1 or 2, wherein the metallocene catalysed multimodal polyethylene copolymer (P) in powder form is combined with further polymer components and / or additives and / or fillers, followed by pelletization, to produce the multimodal copolymer (P’) in pellet form.

31. A film comprising the metallocene catalysed multimodal copolymer (P’) according to claim 30.

32. The film according to claim 31, wherein the film comprises at least one layer comprising the metallocene catalysed multimodal copolymer (P’), wherein the at least one layer of the film comprises at least 50 wt% of the metallocene catalysed multimodal copolymer (P’).

33. The film according to claim 32, wherein the film comprises at least one layer comprising the metallocene catalysed multimodal copolymer (P’), wherein the at least one layer of the film comprises at least 60 wt% of the metallocene catalysed multimodal copolymer (P’).

34. The film according to claim 32, wherein the film comprises at least one layer comprising the metallocene catalysed multimodal copolymer (P’), wherein the at least one layer of the film comprises at least 70 wt% of the metallocene catalysed multimodal copolymer (P’).

35. The film according to claim 32, wherein the film comprises at least one layer comprising the metallocene catalysed multimodal copolymer (P’), wherein the at least one layer of the film comprises at least 80 wt% of the metallocene catalysed multimodal copolymer (P’).

36. Use of the film according to any one of claims 31 to 35 as a packaging material.

37. Use of the film according to any one of claims 31 to 35 as a packaging material for food and / or medical products.

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