Polyethylene copolymer composition for a film layer

Abstract

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

Description

Technical Field

[0001] This invention relates to compositions comprising a specific metallocene-catalyzed multimodal polyethylene copolymer (P) and polyethylene wax, the use of such compositions in membrane applications, and membranes comprising the compositions of this invention. Background Technology

[0002] Due to its excellent cost-effectiveness, state-of-the-art mLLDPE (metallocene-catalyzed linear low-density polyethylene) is widely used in everyday life, such as in packaging. One significant drawback is its narrow molecular weight distribution, resulting in low shear thinning, which leads to membrane conversion problems, thus limiting production capacity.

[0003] Furthermore, higher production volumes in the plastics processing industry are further limited by melt flow instability, which alters the appearance and properties of the final product and has economic and environmental consequences. An important parameter here is the critical shear rate [s]. -1 (CSR), at which point the melt flow becomes unstable.

[0004] Processing instability is affected by the polymer molecular structure and the presence of special additives.

[0005] Ideally, the critical shear rate (CSR) should be as high as possible to improve the processing of polymer melts.

[0006] A common solution to improve the processability of polymer melts is the addition of so-called processing aids. Polymer processing aids (PPAs) are typically used to reduce melt fracture in polymers, particularly linear polyethylene. Melt fracture is a flow instability that begins with surface roughening (sharkskin) and can lead to severe polymer deformation at high outputs. PPAs help extend the critical shear rate at which melt fracture occurs, thereby enabling higher linear velocities.

[0007] Unfortunately, most suitable processing aids are fluoropolymers, due to concerns about their fluorine content in terms of human and environmental health.

[0008] As mentioned above, processability is also affected by molecular structure. Multimodal PE polymers with two or more different polymer components are known to be easier to process, but for example, the homogenization of the melt of multimodal PE can lead to non-uniform final products, such as high gel content in the final product.

[0009] Multimodal PE polymers are known in the art.

[0010] Borealis discloses methods for preparing multi-peaked PE polymers in two loop reactors and one gas-phase reactor in the presence of a metallocene catalyst supported on silica based on the metallocene complex bis(1-methyl-3-n-butylcyclopentadienyl)zirconium dichloride (IV).

[0011] The total density of the polymer produced in the example is 938 or 939 kg / m³. 3 The MFR2 (190°C, 2.16 kg, ISO 1133) of the polymer component produced in the first loop reactor is approximately 22 or 23 g / 10 min.

[0012] There is no mention whatsoever of the membrane's properties, such as impact strength (dart impact, DDI) and processing parameters (such as critical shear rate).

[0013] WO 2021009192 also discloses such a method. The polymer produced in the example has a higher density of 951 kg / m³. 3 The MFR2 (190℃, 2.16kg, ISO 1133) of the polymer component produced in the first loop was 32g / 10min.

[0014] There is no mention whatsoever of the membrane's properties, such as impact strength (dart impact, DDI) and processing parameters (such as critical shear rate).

[0015] The aim is to maximize the processability of the multimodal PE polymer, which exhibits improved melt flow stability as expressed by the high critical shear rate (CSR). It goes without saying that any manipulation of the polymer properties to improve processability should not compromise the properties of the final film.

[0016] In addition, such multi-peaked PE polymers should have a low coefficient of friction (CoF), and the films made from them should have improved mechanical properties.

[0017] Although it is known in principle that polyethylene wax can be used as a processing aid for polyolefins, improved solutions are still needed to simultaneously improve processability, enhance mechanical properties, and reduce the coefficient of friction (CoF) of the resulting blends.

[0018] The inventors have now discovered that blends of metallocene-catalyzed multimodal polyethylene copolymers (P) with polyethylene waxes, made with specific metallocene catalysts and featuring specific polymer designs, exhibit improved processability, which can be seen in terms of higher possible critical shear rates (CSR).

[0019] Such blends additionally have a lower coefficient of friction (COF).

[0020] Membranes made from such blends additionally have improved impact strength, i.e., higher DDI. Summary of the Invention

[0021] The present invention therefore relates to a polyethylene polymer composition comprising the following:

[0022] (1) 97.0 to 99.9 wt% metallocene-catalyzed multimodal polyethylene copolymer (P), composed of the following

[0023] (i) 30.0 to 60.0 wt% of ethylene polymer component (A), and

[0024] (ii) 40.0 to 70.0 wt% of ethylene polymer component (B),

[0025] The ethylene polymer component (A) has

[0026] Between 920 and 980 kg / m 3 Density within a certain range

[0027] MFR2 (190℃, 2.16kg, ISO 1133) in the range of 2.0 to 250.0 g / 10min.

[0028] The ethylene polymer component (B) has

[0029] Between 880 and 970 kg / m 3 Density within a certain range

[0030] MFR2 (190℃, 2.16kg, ISO 1133) in the range of 0.01 to 1.0 g / 10 min.

[0031] The multimodal polyethylene copolymer (P) has

[0032] Between 910 and 970 kg / m 3 Density within a certain range

[0033] MFR2 (190℃, 2.16kg, ISO 1133) in the range of 0.1 to 3.0 g / 10 min, and

[0034] MFR in the range of 22 to 50 21 The ratio of (190℃, 21.6kg, ISO 1133) to MFR2 (190℃, 2.16kg, ISO 1133) (MFR 21 / MFR2),

[0035] (2) 0.1 to 3.0 wt% of polyethylene wax, wherein components (1) and (2) together comprise up to 100.0 wt%.

[0036] 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.

[0037] In another embodiment of the invention, the ethylene polymer component (A) of the metallocene-catalyzed multimodal polyethylene copolymer (P) comprises an ethylene polymer portion (A-1) and an ethylene polymer portion (A-2), wherein portions (A-1) and (A-2) have densities ranging from 920 to 980 kg / m³. 3 MFR2 (190℃, 2.16kg, ISO 1133) ranges from 2.0 to 40 g / 10min, wherein the density of the ethylene polymer portions (A-1) and (A-2) can be the same as or different from that of MFR2 (190℃, 2.16kg, ISO 1133).

[0038] Surprisingly, the blends of the present invention provide the membrane with improved mechanical properties, such as higher dart impact strength and lower coefficient of friction (CoF). Detailed Implementation

[0039] definition

[0040] When the term "comprising / including" is used in this specification and claims, it does not exclude other unspecified elements of primary or secondary functional importance. For the purposes of this invention, the term "consisting of..." is considered a preferred embodiment of the term "comprising / including". If a group is defined below as including at least a certain number of embodiments, this should also be understood as a disclosed group, which preferably consists only of these embodiments.

[0041] Whenever the terms “including” or “having” are used, these terms mean equivalent to “include / comprise” as defined above.

[0042] When referring to a singular noun, use the indefinite or definite article, such as "a", "an", or "the / that", unless otherwise specified, this includes the plural form of the noun.

[0043] In this invention, a metallocene-catalyzed multimodal polyethylene copolymer is defined as a multimodal polyethylene copolymer (P), which is produced in the presence of a metallocene catalyst.

[0044] In the context of multimodal polyethylene copolymers (P), the term "multimodal" herein refers to multimodality in relation to the melt flow rate (MFR) of the ethylene polymer components (A) and (B), i.e., the ethylene polymer components (A) and (B) have different MFR values. As described below, multimodal polyethylene copolymers (P) may further possess multimodality in relation to one or more other properties between the ethylene polymer components (A) and (B).

[0045] 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)".

[0046] Polyethylene wax is essentially a low molecular weight polymer of ethylene, produced through ethylene polymerization, i.e., low molecular weight polyethylene composed of ethylene monomer chains. Polyethylene waxes are classified into several different categories based on their preparation method, density, size, and state. Due to its low molecular weight, polyethylene wax possesses wax-like physical properties, including characteristics such as low viscosity, high hardness (brittleness), and a relatively high melting point.

[0047] The following preferred embodiments, properties, and subgroups of multimodal PE and its ethylene polymer components (A) and (B), as well as its ethylene polymer portions (A-1) and (A-2), and the membranes of the present invention including the preferred range, 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.

[0048] Multimodal PE as well as ethylene polymer components (A) and (B) and ethylene polymer fractions (A-1) and (A-2)

[0049] The multimodal polyethylene copolymer (P) produced by metallocene is referred to herein as "multimodal" because the ethylene polymer component (A), optionally including ethylene polymer portions (A-1) and (A-2), and the ethylene polymer component (B) have been produced under different polymerization conditions, resulting in different melt flow rates (MFR, e.g., MFR2). That is, multimodal PE is multimodal at least with respect to the difference in MFR2 between the ethylene polymer components (A) and (B).

[0050] The multimodal polyethylene copolymer (P) produced by metallocene consists of (i) 30.0 to 60.0 wt% of ethylene polymer component (A) and (ii) 40.0 to 70.0 wt% of ethylene polymer component (B).

[0051] The total amount of (A) and (B) is 100.0 wt%.

[0052] In an embodiment of the present invention, the ethylene polymer component (A) is composed of ethylene polymer portions (A-1) and (A-2).

[0053] The ethylene polymer component (A) and the ethylene polymer (B) are preferably copolymers of ethylene with comonomers selected from C4 to C6. 12 α-olefins, more preferably C4 to C8 α-olefins, and still more preferably C4 to C6 α-olefins.

[0054] Preferably, the comonomer of ethylene polymer component (A) is different from the comonomer of ethylene polymer component (B).

[0055] In an embodiment of the invention, the ethylene polymer component (A) is therefore an ethylene-1-butene polymer, while the ethylene polymer component (B) is an ethylene-1-hexene polymer.

[0056] When the ethylene-1-butene polymer component (A) is composed of ethylene polymer portions (A-1) and (A-2), the MFR2 of the ethylene polymer portions (A-1) and (A-2) may be different from each other or may be the same.

[0057] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer portions (A-1) and (A-2) is in the range of 2.0 to 250.0 g / 10 min, preferably 2.5 to 100.0 g / 10 min, more preferably 3.0 to 30.0 g / 10 min, and even more preferably 3.5 to 10.0 g / 10 min.

[0058] The MFR2 of ethylene polymer components (A) and (B) are different from each other.

[0059] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer component (A) is in the range of 2.0 to 250 g / 10 min, preferably 2.5 to 100.0 g / 10 min, more preferably 3.0 to 30.0 g / 10 min, and even more preferably 3.5 to 10.0 g / 10 min.

[0060] The MFR2 (190°C, 2.16 kg, ISO 1133) of the ethylene polymer component (B) is in the range of 0.01 to 1.0 g / 10 min, preferably 0.05 to 0.9 g / 10 min, more preferably 0.08 to 0.8 g / 10 min, and even more preferably 0.1 to 0.7 g / 10 min.

[0061] 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 0.3 to 2.0 g / 10 min, and even more preferably 0.5 to 1.8.

[0062] MFR of multimodal copolymer (P) 21 The ratio of (190℃, 21.6kg, ISO 1133) to MFR2 (190℃, 2.16kg, ISO 1133) (MFR 21 The MFR2 range is 22 to 50, preferably 25 to 40, and more preferably 26 to 35.

[0063] In one embodiment of the invention, the preferred component is the ethylene polymer component (A), and 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 copolymer (P) is at least 1.6 to 40.0, preferably 2.0 to 30.0, more preferably 2.5 to 20.0, and even more preferably 3.0 to 10.0.

[0064] Of course, in addition to the multimodality of the MFR2 (i.e., the difference between them) of the ethylene polymer components (A) and (B), the multimodal PE of the present invention can also be multimodal, for example, with respect to one or both of two other properties:

[0065] Multimodality in terms of the differences between the following:

[0066] - The type and / or content of comonomers present in ethylene polymer components (A) and (B); and / or

[0067] -Density of ethylene polymer components (A) and (B).

[0068] Preferably, the multimodal polymer (P) is further multimodal in relation to the comonomer types of the ethylene polymer components (A) and (B).

[0069] As described above, in a preferred 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.

[0070] The polymer portions (A-1) and (A-2) have the same type of comonomer, so it is preferred that both portions have 1-butene as a comonomer.

[0071] Even more preferably, the density difference between the multimodal polymer (P) of the present invention and the ethylene polymer component (A) and ethylene polymer component (B) is further multimodal. Preferably, the density of the ethylene polymer component (A) is different, and preferably higher than the density of the ethylene polymer component (B).

[0072] The density range of the ethylene polymer component (A) is 920 to 980 kg / m³. 3Preferred weight is 925 to 960 kg / m³. 3 More preferably, it is 930 to 945 kg / m 3 The density range of the ethylene polymer component (B) is 880 to 970 kg / m³. 3 The preferred value is 885 to 940 kg / m³. 3 More preferably, it is 890 to 915 kg / m 3 .

[0073] The polymer portions (A-1) and (A-2) have densities ranging from 920 to 980 kg / m³. 3 Preferred weight is 925 to 960 kg / m³. 3 More preferably 930 to 950 kg / m 3 The optimal value is 935 to 945 kg / m³. 3 Within the range.

[0074] The densities of the ethylene polymer portions (A-1) and (A-2) may be the same or different from each other.

[0075] Metallocene-catalyzed multimodal copolymers (P) are preferably linear low-density polyethylene (LLDPE), which has well-known implications.

[0076] The density of the multimodal copolymer (P) is between 910 and 970 kg / m³. 3 Preferably, the concentration is 912.0 to 950.0 kg / m³. 3 More preferably 915.0 to 930.0, still more preferably 916 to 925 kg / m 3 Within the range.

[0077] More preferably, the multimodal copolymer (P) is multimodal at least in terms of the MFR2, comonomer type and / or content, and density of the ethylene polymer components (A) and (B), i.e., it has differences, as defined above, below, or in the claims, including any preferred range or embodiment of the polymer composition.

[0078] Within the scope of this invention, the first and second ethylene polymer portions (A-1 and A-2) of the ethylene polymer component (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.

[0079] Based on the multi-peak polymer (P), the ethylene polymer component (A) is present in an amount of 35.0 to 50.0 wt%, preferably in an amount of 36.0 to 48.0 wt%, and even more preferably in an amount of 38.0 to 45.0 wt%.

[0080] Therefore, based on the multi-peak polymer (P), the ethylene polymer component (B) is present in an amount of 50.0 to 65.0% wt%, preferably in an amount of 52.0 to 64.0 wt%, and more preferably in an amount of 55.0 to 62.0 wt%.

[0081] Metallocene-catalyzed multimodal copolymers (P) can be produced in a two-stage process, preferably comprising a slurry reactor (loop reactor) connected in series with a gas phase reactor (GPR), wherein an ethylene polymer component (A) is produced in the loop reactor and an ethylene polymer component (B) is produced in the GPR in the presence of the ethylene polymer component (A) to produce the multimodal copolymer (P).

[0082] When the ethylene component (A) of a multimodal copolymer (P) consists of ethylene polymer portions (A-1) and (A-2), the multimodal copolymer (P) can be produced using a three-stage process. This process preferably includes a first slurry reactor (loop reactor 1), which is connected in series with another slurry reactor (loop reactor 2). The first ethylene polymer portion (A-1) produced in loop reactor 1 is fed into loop reactor 2, where the second ethylene polymer portion (A-2) is produced in the presence of the first portion (A-1). Therefore, loop reactor 2 is connected in series with a gas-phase reactor (GPR), so that the first ethylene polymer component (A) exiting the second slurry reactor is fed into the GPR to produce a trimodal polyethylene copolymer. In this case, the reaction conditions in the two slurry reactors are selected such that products with different MFRs and / or densities are produced in the two slurry reactors.

[0083] This method is described in particular in WO 2016 / 198273, WO 2021009189, WO 2021009190, WO 2021009191 and WO 2021009192. Full details on how to prepare suitable metallocene-catalyzed multimodal copolymers (P) can be found in these references.

[0084] The appropriate process is the Borstar PE process or the Borstar PE 3G process.

[0085] Therefore, the metallocene-catalyzed multimodal copolymer (P) according to the invention is preferably produced in a loop-loop-gas phase cascade. A prepolymerization step may precede such a polymerization step. The purpose of prepolymerization is to polymerize a small amount of polymer onto the catalyst at low temperatures and / or low monomer concentrations. Prepolymerization can improve the performance of the catalyst in the slurry and / or alter the properties of the final polymer. This prepolymerization step is preferably carried out in the slurry, and the amount of polymer produced in the optional prepolymerization step is taken as the amount (wt%) of the ethylene polymer component (A).

[0086] When a prepolymerization step is present, it is preferable that all of the catalyst components be introduced into the prepolymerization step. However, when the solid catalyst components and cocatalysts can be fed separately, it is possible that only a portion of the cocatalyst 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 cocatalyst into the prepolymerization stage in order to achieve sufficient polymerization reaction therein.

[0087] It should be understood that, within the scope of this invention, the amount of polymer produced in the prepolymerization is between 1 and 5 wt% relative to the final metallocene-catalyzed multimodal copolymer (P). This can be considered as part of the first ethylene polymer component (A).

[0088] catalyst

[0089] The metallocene-catalyzed multimodal copolymer (P) used in the method of this invention 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 an organometallic compound (C).

[0090] Organometallic compounds (C) contain transition metals (M) of elements in groups 3 to 10 of the periodic table (IUPAC 2007), or of the actinides or lanthanides.

[0091] According to the present invention, the term "organometallic compound (C)" includes any metallocene or nonmetallocene compound of transition metals, which has at least one organic (coordinating) ligand and exhibits catalytic activity alone or in combination with a co-catalyst. Transition metal compounds are well known in the art, and the present invention covers compounds from Groups 3 to 10 of the periodic table (IUPAC 2007), such as Groups 3 to 7, or Groups 3 to 6, such as Groups 4 to 6, and compounds of lanthanides or actinides.

[0092] In one embodiment, the organometallic compound (C) has the following formula (I):

[0093]

[0094] Each X is independently a halogen atom, C1-6 -alkyl, C 1-6 -alkoxy, phenyl, or benzyl;

[0095] Each Het is independently a monocyclic heteroaromatic group containing at least one heteroatom selected from O or S;

[0096] L is -R'2Si-, where each R' is independently a C substituted with an alkoxy group having 1 to 10 carbon atoms. 1-20 - Hydrocarbon group or C 1-10 -alkyl;

[0097] M is Ti, Zr, or Hf;

[0098] Each R 1 Same or different, is C 1-6 -alkyl or C 1-6 -alkoxy group;

[0099] Each n is between 1 and 2;

[0100] Each R 2 Same or different, is C 1-6 -alkyl, C 1-6 -alkoxy or -Si(R)3 group;

[0101] Each R is arbitrarily selected by 1 to 3 Cs. 1-6 -alkyl-substituted C 1-10 -alkyl or phenyl; and

[0102] Each p is between 0 and 1.

[0103] Preferably, the compound of formula (I) has the structure of formula (I').

[0104]

[0105] Each X is independently a halogen atom, C 1-6 -alkyl, C 1-6 -alkoxy, phenyl, or benzyl;

[0106] L is Me2Si-;

[0107] Each R 1 Same or different and is C 1-6 -alkyl, such as methyl or tert-butyl;

[0108] Each n is between 1 and 2;

[0109] R 2 It is a -Si(R)3 alkyl group; each p is 1;

[0110] Each R is C 1-6 -alkyl or phenyl.

[0111] The highly preferred formula (I) complex is

[0112]

[0113]

[0114] Most preferably, the complex dimethylsilanediylbis[2-(5-trimethylsilylfuran-2-yl)-4,5-dimethylcyclopentadien-1-yl]zirconium dichloride is used.

[0115] 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.

[0116] To form the catalyst, a co-catalyst, also known as an activator, is used. Co-catalysts containing Al or B are well known and can be used here. Aluminoxanes (e.g., MAO) or boron-based co-catalysts (e.g., borates) are preferred.

[0117] In contrast to Ziegler-Natta catalysis, polyethylene copolymers prepared using site-specific catalysis exhibit characteristics that distinguish them from Ziegler-Natta materials. In particular, the comonomer distribution is more uniform. This can be visualized using TREF or Crystaf techniques. Catalyst residues can also indicate the catalyst used. Ziegler-Natta catalysts do not contain, for example, Zr or Group IV (Hf) metals.

[0118] Metallocene-catalyzed multimodal copolymers (P) may contain other polymer components and optional additives and / or fillers. When metallocene-catalyzed multimodal copolymers (P) contain other polymer components, the amount of the other polymer components typically varies between 3.0 and 20.0 wt%, depending on the total amount of the metallocene-catalyzed multimodal copolymer (P) and the other polymer components.

[0119] Optional additives and fillers, and their amounts, are common in membrane applications. Examples of such additives include antioxidants, UV stabilizers, pigments, fillers, antistatic additives, antiblocking agents, nucleating agents, and acid scavengers.

[0120] In one embodiment of the invention, the metallocene-catalyzed multimodal copolymer (P) contains no fluorinated polymer processing aids.

[0121] It should be understood here that any additives and / or fillers may optionally be added to a so-called masterbatch containing the corresponding additives and carrier polymers. In this case, based on the total amount (100 wt%) of the polymer composition, the carrier polymer is not calculated in the polymer component of the metallocene-catalyzed multimodal copolymer (P), but rather in the amount of the corresponding additives.

[0122] Polyethylene wax

[0123] In addition to the multimodal copolymer (P), the polyethylene polymer composition of the present invention also includes 0.1 to 3.0 wt% of polyethylene wax.

[0124] The amount of polyethylene wax added is preferably in the range of 0.2 to 2.5 wt%, more preferably 0.3 to 2.0 wt%, and even more preferably 0.4 to 1.5 wt%.

[0125] In this invention, polyethylene wax refers to homopolymers of ethylene, copolymers of ethylene and α-olefins, or blends thereof.

[0126] The polyethylene wax may have a weight-average molecular weight (determined by viscosity method) of 1,000 to 20,000 g / mol, preferably 1,500 to 15,000, and more preferably 2,000 to 10,000.

[0127] Polyethylene wax includes materials with a density of 960 kg / m³ 3 More or more high-density polyethylene wax, with a density of 940 to 950 kg / m³ 3 Medium-density polyethylene wax with a density of 930 kg / m³ 3 Or a low-density polyethylene wax with an even lower density. Preferably, a density of 900 to 930 kg / m³ is used. 3 Low-density polyethylene wax within the range.

[0128] Density is measured according to JIS K6760 or ISO 1183 (depending on the wax manufacturer).

[0129] The melt viscosity of a suitable polyethylene wax, measured at 140°C, can be in the range of 15 to 10,000 mPa·s, preferably in the range of 20 to 8,000 mPa·s, more preferably in the range of 50 to 7,000 mPa·s, and even more preferably in the range of 60 to 6,500 mPa·s.

[0130] Melt viscosity can be measured according to DIN 53019.

[0131] The polyethylene wax is alternatively or additionally characterized by a dropping point in the range of 115 to 140°C, preferably 118 to 135°C, more preferably 120 to 132°C, as measured according to ASTM 3954, and / or a softening point in the range of 90 to 140°C, preferably 92 to 135°C, more preferably 95 to 130°C, more preferably 98 to 125°C, as measured according to JIS K 2207.

[0132] Polyethylene wax can be prepared using a Ziegler-Natta catalyst or a metallocene catalyst.

[0133] This polyethylene wax is commercially available.

[0134] Specific examples of commercially available polyethylene waxes include Mitsui Chemicals’ Hi-WAX and Excerex series, or Clarinat’s Licowax and Licocene PE families.

[0135] The improved processability of the polyethylene polymer composition according to the invention is expressed by a critical shear rate (CSRR) determined according to ISO 11443, which is at least 400 s. -1 Preferably at least 410s -1 More preferably at least 420s -1 A suitable upper limit for the critical shear rate (CSR) is 1200 s. -1 1000s is preferred -1 , more preferably 1000s -1 .

[0136] The higher critical shear rate (CSR) did not come at the expense of good mechanical properties.

[0137] The membrane of the present invention

[0138] The membrane of the present invention comprises at least one layer containing a metallocene-catalyzed multimodal copolymer (P). The membrane may be a monolayer membrane containing a metallocene-catalyzed multimodal copolymer (P) or a multilayer membrane wherein at least one layer contains a metallocene-catalyzed multimodal copolymer (P). The terms "monolayer membrane" and "multilayer membrane" have well-known meanings in the art.

[0139] The single-layer or multi-layer membranes of the present invention may consist of the metallocene-catalyzed multimodal copolymer (P) itself, or a blend of the metallocene-catalyzed multimodal copolymer (P) with other polymers. In the case of blends, any other polymer is different from the metallocene-catalyzed multimodal copolymer (P), and is preferably a polyolefin. A portion of the above-mentioned additives may optionally be added to the metallocene-catalyzed multimodal copolymer (P) during the membrane preparation process.

[0140] Preferably, at least one layer of the present invention comprises at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, and still more preferably at least 80 wt% of the metallocene-catalyzed multimodal copolymer (P) of the present invention. Most preferably, the at least one layer of the membrane of the present invention is composed of a metallocene-catalyzed multimodal copolymer (P).

[0141] Therefore, the membrane of the present invention may comprise a single layer (i.e., a monolayer) or may comprise multiple layers. Multilayer membranes typically and preferably comprise at least three layers.

[0142] 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, a blown film is produced by extrusion via an annular die and by blowing a tubular film by forming bubbles, which then rupture between rolls after solidification. The film can then be cut, diced, or converted (e.g., folded) as needed. 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 typically co-extruded. Those skilled in the art will know the appropriate extrusion conditions.

[0143] The membrane according to the invention can undergo post-processing, such as surface modification, lamination, or orientation processes. Such orientation processes can be uniaxial (MDO) or biaxial orientation, with uniaxial orientation being preferred.

[0144] In another preferred embodiment, the membrane is non-oriented.

[0145] The resulting membrane can have any thickness conventional in the art. The membrane thickness is not critical and depends on the end application. Therefore, the membrane can have a thickness of, for example, 300 μm or less, typically 6 to 200 μm, preferably 10 to 180 μm, such as 20 to 150 μm or 20 to 120 μm. If desired, the polymers of the present invention can achieve thicknesses of less than 100 μm, for example, less than 50 μm. Membranes of the present invention with thicknesses even less than 20 μm can also be produced while maintaining good mechanical properties.

[0146] Furthermore, the present invention also relates to the use of the articles of the invention as packaging materials, particularly as packaging materials for food and / or medical products.

[0147] The membrane of the present invention is characterized in that, according to ASTM D1709, method A, the dart impact strength (DDI) on a 40 μm monolayer test blown film is at least 300 g and at most 2500 g, preferably 500 g to 2300 g, more preferably 700 g to 2000 g, and still more preferably 800 g to 1800 g.

[0148] In one embodiment, the haze of the film of the present invention (measured according to ASTM D 1003-00 on a 40 μm monolayer test blown film) is less than 30%, preferably 2% to 28%, more preferably 5% to 26%.

[0149] In yet another embodiment, the coefficient of friction (CoF) of the membrane according to the invention, as a measure of the membrane's frictional properties (determined using a method according to ISO 8295), is less than 0.83, preferably in the range of 0.50 to 0.82.

[0150] The invention will be further described with reference to the following non-limiting examples.

[0151] Measurement method:

[0152] Unless otherwise stated in the instructions or experimental section, the following methods are used to determine the performance of polymers (including their parts and components) and / or any sample formulations thereof as described in the text or experimental section.

[0153] melt flow rate

[0154] Melt flow rate (MFR) is determined according to ISO 1133 and expressed in g / 10 min. MFR is an indicator of polymer flowability and therefore also an indicator of polymer processing performance. A higher melt flow rate generally indicates a lower polymer viscosity. The MFR of polyethylene is measured at 190°C. MFR can be measured under different loads, such as 2.16 kg (MFR2), 5 kg (MFR5), or 21.6 kg (MFR6). 21 ).

[0155] Calculation of MFR2 for component B and part (A-2)

[0156] logA = x·logB + (1-X)·logC

[0157]

[0158] For component B:

[0159] B = MFR2 of component (A)

[0160] C = MFR2 of component (B)

[0161] A = Final MFR2 (mixture) of multimodal polyethylene copolymer (P)

[0162] X = weight fraction of component (A)

[0163] For part (A-2):

[0164] B = MFR2 of Part 1 (A-1)

[0165] C = MFR2 of Part 2 (A-2)

[0166] A = the final MFR2 (mixture) of the cyclic polymer (= component (A)).

[0167] X = weight fraction of part 1 (A-1)

[0168] density

[0169] The polymer density was measured according to ASTM D792, Method B (equilibrium density at 23°C) on compression-molded specimens prepared according to EN ISO 1872-2, in kg / m³. 3 .

[0170] Dart Drop Intensity (DDI)

[0171] Dart dropping measurements were performed on the membranes produced as shown below using ASTM D1709 Method A (Alternative Test Technique). Darts with hemispherical heads and a diameter of 38 mm were dropped from a height of 0.66 m onto the membrane clamped in the perforation. Twenty sets of specimens were tested consecutively. One weight was used for each set, and the weight increased (or decreased) in uniform increments between sets. The weight that caused 50% of the samples to break was calculated and reported.

[0172] Haze

[0173] Haze measured according to ASTM D 1003-00

[0174] Coefficient of friction (CoF)

[0175] The dynamic coefficient of friction (CoF) is determined using a method conforming to ISO 8295 as a measure of the film's frictional properties.

[0176] Critical shear rate (CSR)

[0177] According to ISO 11443, use a RHEOGRAPH 75 high-pressure capillary rheometer at 190°C. The determination of flow instability at high shear rates is initiated. Capillary L / D: 30 / 2.

[0178] Membrane sample preparation

[0179] Test films with a thickness of 40 μm, composed of the compositions of this invention and their respective comparative compositions, were prepared using a Collin 30 laboratory-scale single-layer blown film production line. The film samples were produced at 194 °C, a blown ratio of 1:2.5, and a frosting line distance of 120 mm.

[0180] Experimental Section

[0181] Example: Preparation of the catalyst (CAT1) of this invention

[0182] SiO2 loading:

[0183] Add 10 kg of silica (PQ Corporation ES757, calcined at 600°C) from the feed hopper and inertize it in the reactor until the O2 level is below 2 ppm.

[0184] Preparation of MAO / tol / MC:

[0185] At 25°C (oil circulation temperature) and with stirring at 95 rpm, 30 wt% MAO in toluene (14.1 kg) was added from a balance to another reactor, followed by the addition of toluene (4.0 kg). After the addition of toluene, the stirring speed was increased from 95 rpm to 200 rpm, and the stirring time was 30 minutes. 477 g of metallocene racemic dimethylsilanediylbis{2-(5-(trimethylsilyl)furan-2-yl)-4,5-dimethylcyclopentadien-1-yl}zirconium dichloride was added from a metal cylinder, followed by rinsing with 4 kg of toluene (total toluene was 8.0 kg). The reactor stirring speed was changed to 95 rpm for MC feed, then returned to 200 rpm and maintained for 3 hours of reaction. After the reaction time, the MAO / tol / MC solution was transferred to a feed vessel.

[0186] Preparation of catalysts:

[0187] The reactor temperature was set to 10℃ (oil circulation temperature) and MAO / tol / MC was added with stirring at 40 rpm. The MAO / tol / MC solution (target 22.5 kg, actual 22.2 kg) was added over 205 min, followed by stirring for 60 min (oil circulation temperature set to 25℃). After stirring, the "dry mixture" was stabilized at 25℃ (oil circulation temperature) for 12 h with a stirring speed of 0 rpm. The reactor was rotated 20° (back and forth) and stirred several times per hour at 5 rpm.

[0188] After stabilization, the catalyst was dried at 60°C (oil circulation temperature) for 2 hours under a nitrogen flow of 2 kg / h, followed by vacuum drying for 13 hours (with the same nitrogen flow and stirring at 5 rpm). Samples of the dried catalyst were taken, and the HC content was measured using thermogravimetric analysis with a Sartorius moisture analyzer (model MA45) in a glove box. The target HC level was <2% (actual 1.3%).

[0189] Comparative catalyst (CAT2)

[0190] CAT2 was prepared using the same procedure as CAT1, except that the silica loading was 5 kg, the MAO loading was 6.84 kg in a 30 wt% toluene solution, and the metallocene was bis(1-n-butyl-3-methylcyclopentadienyl)zirconium dichloride (0.481 kg in a 25 wt% toluene solution). The process parameters were adjusted accordingly.

[0191] Polymerization: The multimodal polyethylene copolymer (P) of the present invention having 1-butene and 1-hexene comonomers and comparative examples

[0192] The Borstar pilot plant consists of a three-reactor unit (loop 1-loop 2-GPR1) and a prepolymer loop reactor.

[0193] The multimodal copolymer (P) of the present invention in Example 1 (IE1) and the comparative copolymer were produced using the polymerization conditions given in Table 1.

[0194] Table 1: Aggregation Conditions

[0195]

[0196]

[0197] The polymer was mixed with 0.05 wt% Irganox 1010 (BASF), 0.2 wt% Irgafos 168 (BASF) and processing aids, compounded and extruded into granules using a twin-screw extruder ZSK18 under a nitrogen atmosphere; melt temperature 192°C.

[0198] The types and dosages of processing aids are shown in Table 2.

[0199] The processing aids used include:

[0200] PPA-1: Excerex 30050B, commercially available from Mitsui

[0201] PPA-2: HI-WAX 720P, commercially available from Mitsui

[0202] PPA3: Dynamar FX 5922, commercially available from 3M

[0203] Table 2: Material properties and membrane parameters of the compositions of the present invention and comparative compositions

[0204] Material IE1 IE2 IE3 CE1 CE2 CE3 LLDPE-1 99.25 98.75 99.25 99.973 99.75 LLDPE-2 99.25 PPA-1 0.5 1.0 - 0.5 - - PPA-2 - - 0.5 - - PPA-3 - - - - 0.027 - membrane IE1 IE2 IE3 CE1 CE2 CE3 DDI(g) 825 859 830 881 742 np CoF 0.81 0.62 0.81 0.99 0.87 0.83 Haze (%) 19.8 20.8 24.9 34.2 19.3 17.6 <![CDATA[CSR(s -1 )]]> 576 432 576 158 403 360

[0205] NP is impossible; that is, no processing aids were added, the film thickness distribution was poor, and DDI could not be measured correctly.

[0206] As can be clearly seen from the table above, the films composed of the compositions of the present invention (a combination of specific polymer designs made of specific metallocenes and polyethylene waxes) have higher or comparable DDI and lower CoF compared to the comparative examples.

[0207] Furthermore, such membranes can be processed at significantly higher critical shear rates.

Claims

1. A polyethylene polymer composition comprising: (1) 97.0 to 99.9 wt% of metallocene-catalyzed multimodal polyethylene copolymer (P), composed of the following (i) 30.0 to 60.0 wt% of ethylene polymer component (A), and (ii) 40.0 to 70.0 wt% of ethylene polymer component (B), The ethylene polymer component (A) has Between 920 and 980 kg / m 3 Density within a certain range MFR2, measured at 190°C under a load of 2.16 kg according to the method of ISO 1133, in the range of 2.0 to 250.0 g / 10 min. The ethylene polymer component (B) has Between 880 and 970 kg / m 3 Density within a certain range MFR2, measured at 190°C under a load of 2.16 kg according to the method of ISO 1133, in the range of 0.01 to 1.0 g / 10 min, within the range of 0.01 to 1.0 g / 10 min. The multimodal polyethylene copolymer (P) has Between 910 and 970 kg / m 3 Density within a certain range MFR2, measured at 190°C under a load of 2.16 kg according to the method of ISO 1133, in the range of 0.1 to 3.0 g / 10 min, and MFR measured at 190°C under a load of 21.6 kg according to the method of ISO 1133 in the range of 26 to 35. 21 The ratio of MFR2 to the MFR measured at 190°C under a load of 2.16 kg according to ISO 1133 method, MFR 21 / MFR2, and The ratio of the MFR2 of the ethylene polymer component (A) from 2.5 to 20.0, measured according to ISO 1133 at a load of 2.16 kg and at 190 °C, to the MFR2 of the final multimodal copolymer (P), measured according to ISO 1133 at a load of 2.16 kg and at 190 °C. (2) 0.1 to 3.0 wt% of polyethylene wax, wherein components (1) and (2) together comprise up to 100.0 wt%.

2. The composition according to claim 1, wherein the ethylene polymer component (A) comprises ethylene polymer portions (A-1) and (A-2), wherein the densities of portions (A-1) and (A-2) are in the range of 920 to 980 kg / m³. 3 The MFR2 ranges from 2.0 to 250 g / 10 min, as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg. The densities of the ethylene polymer portions (A-1) and (A-2) may be the same as or different from the MFR2 determined by the method of ISO 1133 at 190°C under a load of 2.16 kg.

3. The composition according to claim 1 or 2, wherein the ethylene polymer component (A) and the ethylene polymer (B) are ethylene and a polymer selected from C4 to C6. 12 Copolymers of α-olefin comonomers.

4. The composition according to claim 1 or 2, wherein the ethylene polymer component (A) and the ethylene polymer (B) are copolymers of ethylene and comonomers selected from C4 to C8 α-olefins.

5. The composition according to claim 1 or 2, wherein the ethylene polymer component (A) and the ethylene polymer (B) are copolymers of ethylene and comonomers selected from C4 to C6 α-olefins.

6. The composition 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 composition according to claim 6, 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 composition according to claim 1 or 2, wherein the MFR2 of the ethylene polymer component (A) of the metallocene-catalyzed multimodal polyethylene copolymer (P), determined according to ISO 1133 at a load of 2.16 kg and at 190 °C, is 2.5 to 100.0 g / 10 min. The MFR2 of the ethylene polymer component (B) of the metallocene-catalyzed multimodal polyethylene copolymer (P), determined according to ISO 1133 at 190°C under a load of 2.16 kg, is 0.05 to 0.9 g / 10 min.

9. The composition according to claim 8, wherein the MFR2 of the ethylene polymer component (A) of the metallocene-catalyzed multimodal polyethylene copolymer (P) is 3.0 to 30.0 g / 10 min, as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg.

10. The composition according to claim 8, wherein the MFR2 of the ethylene polymer component (A) of the metallocene-catalyzed multimodal polyethylene copolymer (P) is 3.5 to 10.0 g / 10 min, as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg.

11. The composition according to claim 8, wherein the MFR2 of the ethylene polymer component (B) of the metallocene-catalyzed multimodal polyethylene copolymer (P), as determined according to ISO 1133 at 190°C under a load of 2.16 kg, is 0.08 to 0.8 g / 10 min.

12. The composition according to claim 8, wherein the MFR2 of the ethylene polymer component (B) of the metallocene-catalyzed multimodal polyethylene copolymer (P) is 0.1 to 0.7 g / 10 min, as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg.

13. The composition according to claim 1 or 2, wherein the ratio of the MFR2 of the ethylene polymer component (A) as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg to the MFR2 of the final multimodal copolymer (P) as determined by the method of ISO 1133 at 190°C under a load of 2.16 kg is from 3.0 to 10.

0.

14. The composition according to claim 1 or 2, wherein the multimodal copolymer (P) is produced in the presence of a metallocene complex of formula (I): (I) Each X is independently a halogen atom, C 1-6 -alkyl, C 1-6 -alkoxy, phenyl, or benzyl; Each Het is independently a monocyclic heteroaromatic group containing at least one heteroatom selected from O or S; L is -R'2Si-, where each R' is independently a C substituted with an alkoxy group having 1 to 10 carbon atoms. 1-20 - Hydrocarbon group or C 1-10 -alkyl; M is Ti, Zr, or Hf; Each R 1 Same or different, is C 1-6 -alkyl or C 1-6 -alkoxy group; Each n is between 1 and 2; Each R 2 Same or different, is C 1-6 -alkyl, C 1-6 -alkoxy or -Si(R)3 group; Each R is arbitrarily selected by 1 to 3 Cs. 1-6 -alkyl-substituted C 1-10 -alkyl or phenyl; and Each p is between 0 and 1.

15. The composition according to claim 1 or 2, wherein the amount of polyethylene wax added ranges from 0.2 to 2.5 wt%.

16. The composition of claim 15, wherein the amount of polyethylene wax added ranges from 0.3 to 2.0 wt.

17. The composition of claim 15, wherein the amount of polyethylene wax added ranges from 0.4 to 1.5 wt%.

18. The composition according to claim 1 or 2, wherein the polyethylene wax is a homopolymer of ethylene, a copolymer of ethylene and α-olefins or a blend thereof, and can be prepared by using a Ziegler-Natta catalyst or by using a metallocene catalyst.

19. The composition according to claim 1 or 2, wherein the polyethylene wax has a weight-average molecular weight of 1,000 to 20,000 g / mol, the weight-average molecular weight being determined by a viscosity method.

20. The composition of claim 19, wherein the polyethylene wax has a weight-average molecular weight of 1,500 to 15,000, the weight-average molecular weight being determined by a viscosity method.

21. The composition of claim 19, wherein the polyethylene wax has a weight-average molecular weight of 2,000 to 10,000, the weight-average molecular weight being determined by a viscosity method.

22. The composition of claim 19, wherein the polyethylene wax has a melt viscosity in the range of 15 to 10,000 mPa·s, measured at 140°C.

23. The composition of claim 19, wherein the polyethylene wax has a melt viscosity in the range of 20 to 8000 mPa·s, measured at 140°C.

24. The composition of claim 19, wherein the polyethylene wax has a melt viscosity in the range of 50 to 7000 mPa·s, measured at 140°C.

25. The composition of claim 19, wherein the polyethylene wax has a melt viscosity in the range of 60 to 6500 mPa·s, measured at 140°C.

26. The composition according to claim 1 or 2, wherein the composition does not contain any fluoropolymer processing aids.

27. The composition according to claim 1 or 2, wherein the composition has improved processability, expressed by a critical shear rate (CSR) determined according to ISO 11443, said critical shear rate (CSR) being at least 400 s⁻¹. -1 Up to 1200 s -1 .

28. The composition according to claim 27, wherein the composition has improved processability, expressed by a critical shear rate (CSR) determined according to ISO 11443, said critical shear rate (CSR) being at least 410 s⁻¹. -1 .

29. The composition of claim 27, wherein the composition has improved processability, expressed by a critical shear rate (CSR) determined according to ISO 11443, said critical shear rate (CSR) being at least 420 s⁻¹. -1 .

30. The composition of claim 27, wherein the composition has improved processability, expressed by a critical shear rate (CSR) determined according to ISO 11443, the critical shear rate (CSR) being up to 1100 s⁻¹. -1 .

31. The composition according to claim 27, wherein the composition has improved processability, expressed by a critical shear rate (CSR) determined according to ISO 11443, the critical shear rate (CSR) being up to 1000 s⁻¹. -1 .

32. A film comprising the composition according to any one of claims 1 to 31.

33. The membrane of claim 32, wherein the membrane is characterized by a dart impact strength (DDI) of at least 300 g and at most 2500 g, determined by method A of ASTM D1709 on a 40 μm monolayer test blown film.

34. The membrane according to claim 32, wherein the membrane is characterized in that the dart impact strength (DDI) measured on a 40 μm monolayer test blown film according to ASTM D1709, Method A, is 500 g to 2300 g.

35. The membrane of claim 32, wherein the membrane is characterized by a dart impact strength (DDI) of 700 g to 2000 g as determined by Method A of ASTM D1709 on a 40 μm monolayer test blown film.

36. The membrane of claim 32, wherein the membrane is characterized in that the dart impact strength (DDI) measured on a 40 μm monolayer test blown film according to ASTM D1709, Method A, is 800 to 1800 g.

37. The membrane according to claim 32 or 33, wherein the membrane is characterized in that the coefficient of friction (CoF) measured according to the method of ISO 8295 as a measure of membrane friction performance is less than 0.

83.

38. The membrane according to claim 37, wherein the membrane is characterized in that the coefficient of friction (CoF) measured according to the method of ISO 8295 as a measure of membrane friction performance is in the range of 0.50 to 0.

82.

39. Use of the film according to any one of claims 32 to 38 as a packaging material.

40. Use of the film according to any one of claims 32 to 38 as a packaging material for food and / or medical products.

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