Polyethylene and film comprising the same

Abstract

The present invention provides a polyethylene having excellent low-temperature sealing performance, sealing stability, and process reliability, and a film comprising the same.

Description

Cross-references to related applications

[0001] This application claims priority to Korean Patent Application No. 10-2024-0073747, filed on June 5, 2024, and Korean Patent Application No. 10-2025-0073934, filed on June 5, 2025, and all disclosures in the aforementioned Korean patent applications are incorporated herein by reference. Technical Field

[0002] This invention relates to a polyethylene with excellent low-temperature sealing performance, processing performance and process reliability, and a film containing the polyethylene. Background Technology

[0003] Linear low-density polyethylene (LLDPE) is a resin produced by copolymerizing ethylene and α-olefins under low pressure using a polymerization catalyst. It has a narrow molecular weight distribution, short chain branches of constant length, and no long chain branches.

[0004] In addition to the properties of ordinary polyethylene, linear low-density polyethylene film also has high tensile strength and elongation, excellent film processing performance and transparency, and performs better in terms of tear strength and dart impact strength. Therefore, it has been more widely used in industrial film fields such as food packaging and industrial laminated films, heavy packaging bags and stretch wrap films, where it is difficult to apply traditional low-density polyethylene or high-density polyethylene.

[0005] It is well known that the lower the density of linear low-density polyethylene (LDPE), the higher its dart impact strength. However, using large amounts of comonomers to produce LDPE can lead to several problems, such as increased fouling frequency during slurry polymerization and the need to increase the amount of anti-blocking agents due to the stickiness when producing films containing LDPE. Furthermore, issues such as process instability or deterioration of the morphology of the resulting polyethylene can occur, leading to a decrease in bulk density.

[0006] Recently, driven by the market trends of sustainability and D4R (Design for Recyclability), the demand for down-gauging (D / G) has been growing, and consequently, the demand for linear low-density polyethylene with excellent molding performance and dart impact strength has also increased.

[0007] Before COVID-19, D / G primarily focused on reducing the thickness of the polyethylene layer in multilayer films from a cost perspective. However, after COVID-19, with increasing public concern about environmental issues, the demand for thinning from a recycling perspective has also increased. At the same time, the energy consumption issue of reducing carbon emissions has become increasingly prominent.

[0008] Furthermore, D4R design from a recycling perspective to promote and activate the transition to a circular economy is attracting attention, and the need to improve the sealing performance of the sealing layer is growing in the co-extrusion or lamination process of manufacturing BOPE (biaxially oriented polyethylene) and MDO (machine direction orientation) films used for uni-material All-PE films. Summary of the Invention

[0009] Technical issues To address the problems of the prior art, the present invention aims to provide a polyethylene with excellent low-temperature sealing performance, processing performance, and process reliability.

[0010] Furthermore, the present invention also aims to provide a film comprising the polyethylene.

[0011] Technical solution According to the present invention, a polyethylene is provided having a shear stress of 0.2 MPa or less, as expressed by the following Equation 1, and satisfying the following Equation 2: [Equation 1]

[0012] In equation 1 above, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. [Equation 2]

[0013] In equation 2 above, RSS 125 yes ,in, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

[0014] Furthermore, according to the present invention, a film comprising the polyethylene is also provided.

[0015] Effects of the present invention The polyethylene according to the present invention exhibits excellent low-temperature sealing performance, processing performance, and process reliability. Furthermore, the polyethylene also possesses excellent dart impact strength and stiffness. Therefore, thinner films can be manufactured using the polyethylene, which is beneficial for D4R applications.

[0016] The polyethylene can be used in various films (e.g., food films, agricultural films, general industrial films, or stretch films), and can be used as a sealing layer in the co-extrusion or lamination process of BOPE (biaxially oriented polyethylene) films and MDO (machine orientation oriented) films used in the manufacture of single-material All-PE films.

[0017] Furthermore, since it does not contain PFAS (per- and polyfluoroalkyl substances), which are subject to the Packaging and Packaging Waste Regulation (PPWR) implemented by the European Union (EU), it is also compliant with PPWR. Attached Figure Description

[0018] Figure 1 This is a graph showing the relationship between the shear stress on the y-axis and the shear rate on the x-axis of polyethylene in the embodiments and comparative examples of the present invention.

[0019] Figure 2 Images of the surface morphology of polyethylene extrudates in embodiments and comparative examples of the present invention, taken using a stereomicroscope, are shown. Detailed Implementation

[0020] In this invention, terms such as first and second are used to describe various constituent elements, and these terms are used only for the purpose of distinguishing one constituent element from another.

[0021] Furthermore, the terminology used in this specification is for describing exemplary embodiments only and is not intended to limit the invention. Unless the context clearly specifies otherwise, singular expressions include plural expressions. In this specification, it should be understood that terms such as “comprising,” “equipped,” or “having” are intended to indicate the presence of an implemented feature, quantity, step, component, or combination thereof, and do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, components, or combinations thereof.

[0022] Furthermore, the term "to" used in this specification to describe numerical ranges includes both upper and lower limits. For example, "1 to 3" means above 1 and below 3.

[0023] This invention can be modified in various ways and can take many forms, as detailed below. However, this is not intended to limit the invention to the specific forms disclosed, and it should be understood that the invention includes all modifications, equivalents, or alternatives contained within the spirit and scope of the invention.

[0024] The polyethylene of the present invention and the film comprising the polyethylene will now be described in detail.

[0025] The polyethylene according to an embodiment of the present invention satisfies a shear stress of 0.2 MPa or less, as expressed by Equation 1 below, and also satisfies Equation 2 below: [Equation 1]

[0026] In equation 1 above, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. [Equation 2]

[0027] In equation 2 above, RSS 125 yes ,in, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

[0028] Polyethylene-based resins are widely used in packaging films, especially in the field of heat-sealing films, due to their excellent processing performance, mechanical properties, and economic benefits. These films are sealed by heating, and the physical properties and thermal stability of the sealed area directly affect the reliability of the film.

[0029] Furthermore, while LLDPE (linear low-density polyethylene) possesses excellent physical properties due to its uniform polymer structure, its processing performance is poor due to its narrow molecular weight distribution. To compensate for this deficiency, methods using PPAs (polymer processing aids) containing fluorine-based compounds have been employed. However, in recent years, with the increasing regulation of PPA use, the demand for improved processing performance has also grown significantly.

[0030] Therefore, products with improved processing performance have been released to replace PPA by introducing LCB (Long Chain Branch) into LLDPE or by adjusting the content and distribution of SCB (Short Chain Branch). However, it is difficult to find a product that achieves an excellent balance of physical properties, especially between low-temperature sealing performance and processing performance.

[0031] Therefore, this invention, by more reliably reflecting and quantifying the microstructures that affect the stiffness and sealing properties of polyethylene, designs a resin based on the stiffness factor and sealing property factor, and by providing a polyethylene resin in which both the stiffness factor and sealing property factor are higher than a certain standard, can provide a product in which both sealing properties and stiffness are improved.

[0032] Shear stress is a key factor in controlling the balance between processing flowability and anti-sagging properties of polyethylene used in heat-sealing films.

[0033] More specifically, in Equation 1 for shear stress, if the storage modulus G' and loss modulus G'' are large, the stress during shearing also increases, leading to increased processing resistance. Conversely, if both G' and G'' are small, resulting in shear stress below 0.2 MPa at the shear rate, it signifies high rheological flexibility and excellent processing performance.

[0034] The polyethylene according to embodiments of the present invention has a shear stress value of less than 0.20 MPa, as expressed by Equation 1, compared with conventional polyethylene, thereby enabling the provision of polyethylene suitable for manufacturing films with a balance between sealing properties and processing performance.

[0035] More specifically, in the polyethylene according to embodiments of the present invention, the shear stress value of Equation 1 can be less than 0.20 MPa, less than 0.19 MPa, or less than 0.18 MPa. The lower the shear stress value, the better the processing performance; therefore, there is no particular limitation on its lower limit value. For example, it can be greater than 0.10 MPa, greater than 0.11 MPa, greater than 0.12 MPa, greater than 0.13 MPa, or greater than 0.14 MPa.

[0036] The polyethylene according to an embodiment of the present invention satisfies the following equation 2: [Equation 2]

[0037] In equation 2 above, RSS 125 yes ,in, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

[0038] Equation 2 above quantitatively expresses the rheological properties (RSS) of polyethylene. 125 The balance between transparency and optical properties (haze) defines the conditions for achieving a high-quality film that balances transparency and process stability.

[0039] RSS stands for Recoverable Shear Strain, which refers to the degree to which a melt elastically recovers its shape after being subjected to an external force (such as shear stress) and after the force is removed. In other words, it can be used as a measure of whether a melt tends to return to its original state, and can be considered a concept similar to melt elasticity. A higher RSS value indicates stronger melt elasticity and a longer relaxation time.

[0040] Therefore, it has a high RSS 125The RSS value of polyethylene (where 125 indicates that the RSS is measured at an angular velocity of ω=125 rad / s) is characterized by structural stability and good resistance to stress during processing, and can suppress sagging during film processing.

[0041] Furthermore, due to the RSS 125 Measured under high-speed rotation conditions (ω = 125 rad / s), it can therefore be used as an indicator to evaluate structural stability and rheological cohesion under high-speed processing environments, and can determine the deformation and flow stability of polyethylene in high-speed extrusion, casting, blown film, and other processes. Therefore, RSS... 125 High-value polyethylene exhibits improved processing performance even under high-speed processing conditions and can suppress sagging during film processing.

[0042] Regarding haze, the lower the value, the higher the transparency. Therefore, for transparent packaging films, lower haze equates to higher commercial value. However, when attempting to enhance rheological properties, haze may actually increase due to changes in the dispersion or crystal structure. Equation 3 above applies only to the RSS of polyethylene. 125 This holds true when the value is sufficiently large and the haze value is appropriately low. In this case, it means that polyethylene is rheologically stable even during high-speed processing, while also ensuring the transparency of the film.

[0043] In equation 2 above, The value can be 30 or above, or 30.30 or above, or 31 or above, or 31.50 or above, or 32 or above, or 33 or above, or 34 or above, and below 40, or below 39.50, or below 39, or below 38.50, or below 38, or below 37.90.

[0044] By satisfying Equation 2 above, the polyethylene according to the embodiments of the present invention can simultaneously ensure excellent flow stability and outstanding film transparency even during high-speed film processing.

[0045] Furthermore, the polyethylene according to embodiments of the present invention can meet the following condition: the critical shear rate (i.e., the shear rate when the shear stress is 0.2 MPa) is 125 rad / s or higher.

[0046] The critical shear rate, also known as the shear rate at which a shear stress of 0.2 MPa occurs, is the minimum shear rate at which a material begins to be significantly affected by tensile stress under constant shear stress (0.2 MPa in this specification). It refers to the shear rate at which melt fracture occurs. A high critical shear rate means that the material deforms little and remains rigid under low-speed conditions, and flows easily even at high speeds, exhibiting stable flow properties during extrusion or film forming processes. Therefore, by using polyethylene with a high critical shear rate, both melt fracture suppression and process stability can be ensured during film processing.

[0047] The polyethylene according to embodiments of the present invention has a critical shear rate of 125 rad / s or more compared with conventional polyethylene, and therefore can provide a polyethylene suitable for manufacturing a film with a balance between sealing properties and processing performance.

[0048] More specifically, in the polyethylene according to embodiments of the present invention, the critical shear rate may be 125 rad / s or more, or 130 rad / s or more, or 135 rad / s or more, or 140 rad / s or more, or 145 rad / s or more, or 150 rad / s or more, or 155 rad / s or more, or 160 rad / s or more, or 165 rad / s or more, or 170 rad / s or more, or 175 rad / s or more. The higher the critical shear rate, the better the processing performance. Therefore, there is no particular upper limit to its value. For example, it can be below 300 rad / s, or below 295 rad / s, or below 290 rad / s, or below 285 rad / s, or below 280 rad / s, or below 275 rad / s, or below 270 rad / s, or below 265 rad / s, or below 260 rad / s, or below 255 rad / s, or below 250 rad / s, or below 245 rad / s.

[0049] Furthermore, the polyethylene according to embodiments of the present invention satisfies the following equation 3: [Equation 3]

[0050] In Equation 3 above, RSS 50 yes ,in, It is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency scanning mode at a temperature of 190°C and an angular velocity of ω = 50 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity ω = 50 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

[0051] Equation 3 above also quantitatively expresses the rheological properties (RSS) of polyethylene. 50 The balance between transparency and optical properties (haze) defines the conditions for achieving a high-quality film that balances transparency and process stability.

[0052] Therefore, RSS 50 High-value polyethylene (where 50 indicates that the RSS is measured at an angular velocity of ω=50 rad / s) has the characteristics of structural stability and good resistance to stress during processing, and can suppress sagging during film processing.

[0053] Regarding haze, the lower the haze value, the higher the transparency. Therefore, for transparent packaging films, the lower the haze, the higher their commercial value. However, when attempting to enhance rheological properties, the haze may actually increase due to changes in the dispersion or crystal structure.

[0054] In equation 3 above, The value can be 70 or above, or 71.50 or above, or 72 or above, or 72.40 or above, or 73 or above, or 73.40 or above, or below 90, or below 89, or below 88, or below 87, or below 86, or below 85, or below 84, or below 83, or below 82, or below 81, or below 80.

[0055] By satisfying Equation 3 above, the polyethylene according to embodiments of the present invention can be used to manufacture films with a balance between rheological stability and excellent transparency.

[0056] For reference, in Equations 2 and 3 above, haze is measured according to ASTM D1003 for a film formed using a blown film extruder (die diameter 120 mm, die gap 2.0 mm, BUR 2.5, dual air ring system) from a composition containing at least 95% by weight, or at least 96% by weight, or at least 97% by weight, or at least 98% by weight, or at least 99% by weight, or at least 99.9% by weight, of the polyethylene of the present invention, to form a single-layer film with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm.

[0057] Furthermore, the density of the polyethylene according to embodiments of the present invention (measured according to ASTM D 1505) is 0.900 to 0.925 g / cm³.3 .

[0058] If the density of polyethylene is too low, it is difficult to guarantee the stability of the slurry polymerization process. Furthermore, there is a trade-off between density and dart impact strength, as well as between density and low-temperature sealing performance. Therefore, if the density of polyethylene is too high, the thinning process during film manufacturing becomes difficult due to the decrease in dart impact strength and low-temperature sealing performance. More specifically, the polyethylene according to the present invention has a density of 0.900 g / cm³. 3 Above, or 0.901 g / cm 3 Above, or 0.902 g / cm 3 Above, or 0.903 g / cm 3 Above, or 0.904 g / cm 3 Above, or 0.905 g / cm 3 Above, or 0.906 g / cm 3 Above, or 0.907 g / cm 3 Above, or 0.908 g / cm 3 Above, or 0.909 g / cm 3 Above, or 0.910 g / cm 3 Above, or 0.911 g / cm 3 Above, or 0.912 g / cm 3 Above, or 0.913 g / cm 3 Above, or 0.914 g / cm 3 Above, or 0.915 g / cm 3 The above, and 0.925 g / cm 3 Below, or 0.924 g / cm 3 Below, or 0.923 g / cm 3 Below, or 0.922 g / cm 3 Below, or 0.921 g / cm 3 Below, or 0.920 g / cm 3 Below, or 0.919 g / cm 3 Below, or 0.918 g / cm 3 the following.

[0059] The polyethylene according to embodiments of the present invention has a significantly lower sealing initiation temperature compared to conventional polyethylene with similar density, and exhibits excellent low-temperature sealing performance and improved stiffness. Therefore, as a product with a balance of sealing performance and stiffness, it can avoid the waste of resources that would otherwise be discarded before use due to adhesion problems in the actual application of laminated roll packaging when using low-density products to improve conventional low-temperature sealing performance, and reduces the use of additives such as anti-blocking agents used to reduce the coefficient of friction.

[0060] Furthermore, the molecular weight distribution (MWD, Mw / Mn) of the polyethylene according to embodiments of the present invention is 2.0 to 5.0.

[0061] If the molecular weight distribution is narrow, less than 2.0, the mechanical properties such as toughness are excellent, but there is a concern that the molding and processing performance may decrease. If the molecular weight distribution is greater than 5.0, the molding and processing performance is excellent, but there is a concern that the mechanical properties may decrease. More specifically, the molecular weight distribution (MWD) of the polyethylene is: 2.0 or more, or 2.1 or more, or 2.2 or more, or 2.3 or more, or 2.4 or more, or 2.5 or more, or 2.6 or more, or 2.7 or more, or 2.8 or more, or 2.9 or more, or 3.0 or more, or 3.1 or more, or 3.2 or more, or 3.3 or more, or 3.4 or more, or 3.5 or more, or 3.6 or more, or 3.65 or more, or 3.7 or more, or 3.8 or more, and 5.0 or less, or 4.9 or less, or 4.8 or less, or 4.7 or less, or 4.6 or less, or 4.5 or less, or 4.4 or less, or 4.3 or less, or 4.25 or less, or 4.2 or less, or 4.15 or less, or 4.1 or less, or 4.0 or less, or 3.9 or less. By satisfying the above molecular weight distribution conditions, the polyethylene of the present invention can exhibit a good balance and improved molding and processing performance and mechanical properties.

[0062] In this invention, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polyethylene are determined by gel permeation chromatography (GPC), and the molecular weight distribution is calculated using the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn). Here, both weight-average molecular weight (Mw) and number-average molecular weight (Mn) are the equivalent molecular weights of polystyrene obtained from GPC analysis.

[0063] Specifically, polyethylene samples were analyzed using a Polymer Char GPC-IR chromatogram equipped with a Polymer Laboratories PLgel MIX-B 300 mm column. ®The instrument was evaluated. The evaluation temperature was 160℃, using 1,2,4-trichlorobenzene as the solvent, and measurements were performed at a flow rate of 1 mL / min. Polyethylene samples were prepared as solutions with a concentration of 16 mg / 8 mL, and the injection volume was 200 μL. Mw and Mn values ​​were determined using calibration curves plotted with polystyrene standards. Nine polystyrene standards with molecular weights of 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000 were used.

[0064] Furthermore, the polyethylene according to embodiments of the present invention, at a temperature of 190°C and a load of 2.16 kg, has a melt flow index (MI) measured according to ASTM D1238 standard. 2.16The concentration is 0.5 to 5.0 g / 10 min. More specifically, it can be 0.5 g / 10 min or more, or 0.6 g / 10 min or more, or 0.7 g / 10 min or more, or 0.8 g / 10 min or more, or 0.9 g / 10 min or more, or 1.0 g / min or more, or 1.1 g / 10 min or more, or 1.2 g / min or more, or 1.3 g / min or more, or 1.4 g / min or more, or 1.5 g / min or more, and less than 5.0 g / 10 min, or less than 4.9 g / 10 min, or less than 4.8 g / 10 min, or less than 4.7 g / 10 min, or less than 4.6 g / 10 min, or less than 4.5 g / 10 min, or less than 4.4 g / 10 min, or less than 4.3 g / 10 min, or less than 4.2 g / 10 min, or less than 4.1 g / 10 min, or less than 4.0 g / 10 min, or 3.9 g / 10 min. Below 3.8 g / 10min, or below 3.7 g / 10min, or below 3.6 g / 10min, or below 3.5 g / 10min, or below 3.4 g / 10min, or below 3.3 g / 10min, or below 3.2 g / 10min, or below 3.1 g / 10min, or below 3.0 g / 10min, or below 2.9 g / 10min, or below 2.8 g / 10min, or below 2.7 g / 10min, or below 2.6 g / 10min, or below 2.5 g / 10min, or below 2.4 g / 10min, or below 2.3 g / 10min, or below 2.2 g / 10min, or below 2.1 g / 10min, or below 2.0 g / 10min, or below 1.9 g / 10min, or below 1.8 g / 10min, or below 1.7 g / 10min. Below g / 10min, or below 1.6 g / 10min.

[0065] Therefore, by satisfying the conditions of low density, optimal molecular weight distribution range and melt index, as well as the aforementioned crystal distribution characteristics and molecular weight distribution characteristics, the polyethylene according to the present invention can exhibit excellent sealing performance and dart impact strength performance, as well as improved molding and processing performance and mechanical properties.

[0066] Furthermore, the polyethylene according to embodiments of the present invention may specifically be a copolymer of ethylene and α-olefin, comprising ethylene repeating units and α-olefin repeating units derived from α-olefin monomers.

[0067] The α-olefin monomer can specifically be an α-olefin monomer having 3 to 20 carbon atoms. Specific examples include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene. More preferably, it can be 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene. Preferably, the polyethylene according to embodiments of the present invention can be a copolymer of ethylene and 1-hexene, rather than a mixture with other polyethylenes.

[0068] For example, polyethylene with such physical properties can be prepared by a manufacturing method comprising the following steps: polymerizing ethylene monomers and α-olefin monomers in the presence of a hybrid supported metallocene catalyst comprising a first transition metal compound represented by Chemical Formula 1 and a second transition metal compound represented by Chemical Formula 2. This manufacturing method is merely an example of achieving the polyethylene of the present invention, and the polyethylene of the present invention is not limited to this manufacturing method.

[0069] [Chemical Formula 1]

[0070] In the above chemical formula 1, M1 is a group 4 transition metal. X 11 and X 12 Each independently is C 1-20 Alkyl or halogen, A1 is carbon, silicon, or germanium. Q 11 and Q 12 Each is independently hydrogen, halogen, C 1-20 Alkyl or C 2-20 Alkoxyalkyl, and R 11 To R 15 Each is independently hydrogen or C 1-20 alkyl.

[0071] [Chemical Formula 2]

[0072] In the above chemical formula 2, M2 is a group 4 transition metal. X 21 and X 22 Each independently is C 1-20 Alkyl or halogen, R 21 To R 25 Each independently is C 1-20 alkyl, R 26 It is hydrogen or C 1-20 Alkyl groups, and R 27 For hydrogen, C 1-20 Alkyl, C 2-20 Alkoxy or C 2-20 Alkoxyalkyl.

[0073] In this invention, the substituents in the chemical formula are described in more detail below.

[0074] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0075] C 1-20 The alkyl group can be straight-chain, branched, or cyclic. Specifically, the C 1-20 The alkyl group can be: a straight-chain alkyl group having 1 to 20 carbon atoms; a straight-chain alkyl group having 1 to 10 carbon atoms; a straight-chain alkyl group having 1 to 5 carbon atoms; a branched alkyl group or cyclic alkyl group having 3 to 20 carbon atoms; a branched alkyl group or cyclic alkyl group having 3 to 15 carbon atoms; or a branched alkyl group or cyclic alkyl group having 3 to 10 carbon atoms. More specifically, the alkyl group having 1 to 20 carbon atoms can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, or cyclohexyl, etc.

[0076] C 2-20 The alkenyl group can be straight-chain, branched, or cyclic. Specifically, the C 2-20 The alkenyl group can be a straight-chain alkenyl group having 2 to 20 carbon atoms, a straight-chain alkenyl group having 2 to 10 carbon atoms, a straight-chain alkenyl group having 2 to 5 carbon atoms, a branched alkenyl group having 3 to 20 carbon atoms, a branched alkenyl group having 3 to 15 carbon atoms, a branched alkenyl group having 3 to 10 carbon atoms, a cyclic alkenyl group having 5 to 20 carbon atoms, or a cyclic alkenyl group having 5 to 10 carbon atoms. More specifically, the C 2-20 The alkenyl group can be vinyl, propenyl, butenyl, pentenyl, or cyclohexenyl, etc.

[0077] C 1-20 The alkoxy group can be straight-chain, branched, or cyclic. Specifically, the C 1-20The alkoxy group can be a straight-chain alkoxy group having 1 to 20 carbon atoms; a straight-chain alkoxy group having 1 to 10 carbon atoms; a straight-chain alkoxy group having 1 to 5 carbon atoms; a branched or cyclic alkoxy group having 3 to 20 carbon atoms; a branched or cyclic alkoxy group having 3 to 15 carbon atoms; or a branched or cyclic alkoxy group having 3 to 10 carbon atoms. More specifically, the alkoxy group having 1 to 20 carbon atoms can be methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, or cyclohexyloxy, etc.

[0078] C 2-20 Alkoxyalkyl groups can be alkyl groups (-R) y One or more hydrogens on the ) are alkoxy groups (-OR) z The substituents obtained by substitution have a structure containing -R y -OR z Specifically, the alkoxyalkyl group having C2 to C20 carbon atoms can be methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, or tert-butoxyhexyl, etc.

[0079] Furthermore, the group 4 transition metal can be titanium, zirconium, hafnium, etc.

[0080] The hybrid supported metallocene catalyst used in the manufacture of polyethylene according to the present invention is a hybrid catalyst comprising a first transition metal compound having a high molecular weight and high copolymerization ability and a second transition metal compound having a low molecular weight and low copolymerization ability.

[0081] Specifically, the first transition metal compound represented by Chemical Formula 1 facilitates the formation of high molecular weight copolymers with high SCB content, while the second transition metal compound represented by Chemical Formula 2 facilitates the formation of low molecular weight copolymers with low SCB content. Therefore, the hybrid supported metallocene catalyst exhibits high copolymerization ability in the high molecular weight region of polyethylene through the first transition metal compound, and low copolymerization ability in the low molecular weight region of polyethylene through the action of the second transition metal compound. Thus, by utilizing the hybrid supported metallocene catalyst, strong low crystallinity is exhibited in the high molecular weight region of polyethylene, thereby enabling the formation of tie-molecules, and thus polyethylene meeting the aforementioned physical property requirements can be readily prepared.

[0082] Specifically, in the hybrid supported metallocene catalyst, the first transition metal compound represented by the chemical formula 1 helps to produce high molecular weight copolymers and exhibits a higher comonomer incorporation rate compared to the second transition metal compound.

[0083] Specifically, in the chemical formula 1, M1 can be zirconium (Zr) or titanium (Ti).

[0084] In addition, X 11 and X 12 Each can be a halogen, or more specifically, chlorine.

[0085] Furthermore, in the aforementioned chemical formula 1, Al is silicon, and Q... 11 and Q 12 Each can be independently hydrogen, halogen, or C. 1-20 Alkyl or C 2-20 alkoxyalkyl, wherein Q 11 and Q 12 One of them can be a tether group (C) 2-20 Alkoxyalkyl. More specifically, Q 11 and Q 12 Any one of them can be C 2-20 alkoxyalkyl, the other can be C 1-20 alkyl.

[0086] Therefore, as a bridging group connecting two ligands, when Q 11 and Q 12 One of them contains a chain group C 2-20 When alkoxyalkyl is used, the atomic size becomes larger and the usable angle increases compared to the carbon bridges in traditional metallocene compounds, which facilitates monomer access during polymerization and exhibits excellent catalytic activity. Furthermore, it prevents the leaching of catalyst precursors during polymerization, thus avoiding scaling caused by the reaction of leached catalyst precursors with the co-catalyst. When Q 11 and Q 12 One of them is -(CH2)nR b (where R) b C 1-6 Alkoxy, more specifically C 1-6 Straight-chain alkoxy or C 3-6 Branched alkoxy groups, more specifically C 3-6 Branched alkoxy groups, such as tert-butoxy groups (where n is an integer from 2 to 10 or 3 to 9), while the other is C. 1-4 This effect can be further enhanced with alkyl groups. More specifically, Q 11 and Q 12 Either of them can be tert-butoxyhexyl, while the other can be methyl.

[0087] Furthermore, in the chemical formula 1, R 11 To R 14 Each can be independently designated as C. 1-10Alkyl, more specifically C 1-4 Alkyl groups, or more specifically methyl groups. Therefore, by using R... 11 To R 14 Replacing the cyclopentadienyl ligand in Formula 1 can provide sufficient electrons due to the inductive effect, thus exhibiting superior catalytic activity.

[0088] Furthermore, in the chemical formula 1, R 15 It can be C 1-6 Alkyl, more specifically C 1-4 Straight-chain alkyl or C 3-6 Branched alkyl groups, or more specifically tert-butyl groups.

[0089] As a specific example of a first transition metal compound represented by the aforementioned chemical formula 1, compounds having the following structure may be mentioned, but the invention is not limited thereto.

[0090]

[0091] The first transition metal compound represented by the chemical formula 1 can be synthesized by applying known reactions; more detailed synthesis methods can be found in the examples.

[0092] Meanwhile, in the hybrid supported metallocene catalyst, the second transition metal compound represented by Formula 2 has a structure in which the indene ligand (specifically, the 4,5,6,7-tetrahydro-1-indene ligand) and the cyclopentadiene ligand are not bridged. Therefore, the electronic / space environment around the transition metal is easily controlled, thereby facilitating the adjustment of the chemical structure, molecular weight distribution, and mechanical properties of the synthesized polyethylene.

[0093] Specifically, in the chemical formula 2, M2 can be zirconium (Zr). When the second transition metal compound contains Zr as the central metal, it has more orbitals that accept electrons compared to when it contains other Group 14 elements such as Hf as the central metal. Therefore, it can more easily bind to monomers with higher affinity, thus exhibiting a superior catalyst activity improvement effect.

[0094] In addition, X 21 and X 22 Each can be a halogen, or more specifically, chlorine.

[0095] Additionally, in the chemical formula 2, R 21 To R 25 Each can be independently designated as C. 1-10 Alkyl, more specifically C 1-4 Alkyl groups, or more specifically methyl groups. Therefore, by using R... 21 To R 25Replacing the cyclopentadienyl ligand in Formula 2 allows for the provision of sufficient electrons due to the inductive effect, resulting in superior catalytic activity. Furthermore, by combining it with the first transition metal compound represented by Formula 1, the distribution of comonomers in the manufactured polyethylene can be appropriately controlled, thereby readily producing polyethylene that meets the aforementioned physical property requirements.

[0096] Furthermore, since the second transition metal compound contains a hydride indene ligand, specifically 4,5,6,7-tetrahydro-1-indene ligand, it exhibits superior hydrogen reactivity compared to compounds containing conventional indene groups. Therefore, the amount of hydrogen input and wax generated during the polymerization reaction can be reduced, thereby improving process stability. Moreover, by using it in combination with the first transition metal compound represented by Formula 1, the distribution of comonomers in the final polyethylene is concentrated towards the high molecular weight side, thereby significantly improving the impact strength properties of the polyethylene.

[0097] Furthermore, the first and third positions of the 4,5,6,7-tetrahydro-1-indene ligand may be unsubstituted or substituted with R, respectively. 26 and R 27 Replacement. The R 26 Specifically, hydrogen or C 1-20 Alkyl, R 27 It can be hydrogen, C 1-20 Alkyl, C 2-20 Alkoxy or C 2-20 Alkoxyalkyl. More specifically, the R 26 Is it hydrogen or C? 1-6 Alkyl, R 27 It can be hydrogen, C 1-6 Alkyl or alkoxyalkyl-(CH2) n -R b (wherein, the R) b C 1-6 Alkoxy, more specifically C 1-6 Straight-chain alkoxy or C 3-6 Branched alkoxy groups, where n is an integer from 2 to 10. Furthermore, in the -(CH2)nR group... b In the middle, R b It can be C 3-6 Branched alkoxy groups, more specifically, for example, tert-butoxy groups with a C-axis. 3-6 Branched alkoxy groups, where n can be an integer from 3 to 9. Even more specifically, the R... 26 It is hydrogen or methyl, R 27 It can be hydrogen, methyl, ethyl, or tert-butoxyhexyl.

[0098] As a specific example of a second transition metal compound represented by the aforementioned chemical formula 2, compounds having the following structure may be mentioned, but the invention is not limited thereto.

[0099]

[0100] The second transition metal compound represented by the chemical formula 2 can be synthesized by applying known reactions; more detailed synthesis methods can be found in the examples.

[0101] Furthermore, the hybrid supported metallocene catalyst can improve catalyst activity by controlling the molar ratio of the first transition metal compound and the second transition metal compound, and can more easily achieve the physical properties of the manufactured polymer.

[0102] For example, the hybrid supported metallocene catalyst may comprise a first transition metal compound and a second transition metal compound in a molar ratio of 1:1 to 10:1. When the above mixing ratio conditions are met, the catalytic activity remains excellent, and the high and low copolymerization capabilities of polyethylene manufactured from this hybrid supported catalyst are optimized, thereby further improving sealing performance, dart impact strength, stiffness, and molding processability. More specifically, the molar ratio of the first transition metal compound to the second transition metal compound may be 2:1 to 8:1, or 2:1 to 5:1.

[0103] In addition, the hybrid supported metallocene catalyst may include a co-catalyst.

[0104] When hybrid supported metallocene catalysts contain a co-catalyst, they exhibit improved process stability while maintaining high catalyst activity.

[0105] Specifically, the co-catalyst may comprise one or more compounds represented by the following chemical formula 3.

[0106] [Chemical Formula 3] -[Al(R 41 )-O]a- In the above chemical formula 3, R 41 It is a halogen; or C that is either unsubstituted or halogenated. 1-20 hydrocarbon group; a is an integer greater than or equal to 2.

[0107] In this specification, a hydrocarbon group refers to a monovalent functional group in hydrocarbon form that has lost one hydrogen atom from a hydrocarbon, and may include alkyl, alkenyl, alkynyl, aryl, aralkyl, aryl-alkenyl, arylynyl, alkylaryl, alkenylaryl, and alkynylaryl, etc. Furthermore, a hydrocarbon group having 1 to 20 carbon atoms may have 1 to 15 carbon atoms or 1 to 10 carbon atoms. Specifically, a hydrocarbon group having 1 to 20 carbon atoms may be a straight-chain, branched, or cyclic alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, cyclohexyl, etc.; or an aryl group, such as phenyl, naphthyl, or anthraceneyl.

[0108] Examples of compounds represented by Formula 3 include alkylaluminoxane-based compounds, such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one or a mixture of two or more of these may be used. In these compounds, the co-catalyst may more specifically be methylaluminoxane.

[0109] The alkylaluminoxane-based cocatalyst stabilizes the first and second transition metal compounds and also acts as a Lewis acid, thereby further enhancing the catalyst's activity by including a metal element capable of forming bonds with functional groups introduced into the bridging groups of the first transition metal compound through Lewis acid-base interactions.

[0110] Furthermore, the amount of co-catalyst used can be appropriately adjusted according to the desired catalyst and the physical properties or effects of polyethylene. For example, when silica is used as the support as described below, based on a support weight of 1000g silica, the loading of the co-catalyst can be more than 100g, more than 1000g, more than 2000g, and less than 6000g, less than 5500g, or less than 5400g.

[0111] Furthermore, the hybrid supported metallocene catalyst may include a support. When the hybrid supported metallocene catalyst includes a support, the first transition metal compound and the second transition metal compound are used in the form of a supported catalyst on the support.

[0112] As the carrier, a carrier with highly active hydroxyl, silanol, or siloxane groups on its surface can be used. For this purpose, a carrier that has been calcined to modify its surface or a carrier that has been dried to remove surface moisture can be used. For example, silica prepared by calcining silica gel, or silica such as high-temperature dried silica, silica-alumina, and silica-magnesia, can be used. These typically contain oxide, carbonate, sulfate, and nitrate components, such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0113] When used as a supported catalyst, the produced polymer exhibits excellent particle shape and bulk density, making it suitable for conventional slurry polymerization, bulk polymerization, or gas-phase polymerization processes. Furthermore, among various supports, silica supports show almost no catalyst detachment from the support surface during ethylene polymerization. This is because the functional groups of the transition metal compounds are chemically bonded to the support, thus minimizing scaling caused by reactor wall or polymer particle adhesion when manufacturing polyethylene using slurry or gas-phase polymerization.

[0114] The support can be a support with an average particle size (D50) of 20 to 40 µm. When it has this particle size, it can load transition metal compounds more efficiently, thereby improving catalyst activity. More specifically, its particle size can be greater than 20 µm, or greater than 25 µm, and less than 40 µm, or less than 30 µm.

[0115] In this invention, the average particle size (D50) of the carrier refers to the particle size at which the cumulative distribution of particle number reaches 50%, based on particle size. The D50 can be measured using laser diffraction. Specifically, the carrier to be tested is dispersed in a dispersion medium such as deionized water, and then introduced into a commercial laser diffraction particle size measurement device (e.g., Microtrac S3500). The particle size distribution is calculated by measuring the change in the diffraction pattern as the particles pass through the laser beam. The particle size at which the cumulative distribution of particle number according to particle size reaches 50% in the measurement device is calculated, and this particle size is taken as the average particle size.

[0116] Furthermore, when loaded onto the support, the loading amounts of the first and second transition metal compounds can be respectively: 1 mmol or more, or 1.5 mmol or more, or 2 mmol or more, and less than 100 mmol, or less than 50 mmol, or less than 30 mmol, or less than 10 mmol, or less than 5 mmol, based on 1000 g silica support. When the loading amounts are within the aforementioned ranges, they exhibit suitable supported catalyst activity, which is beneficial for maintaining catalyst activity and improving economic efficiency.

[0117] The hybrid supported metallocene catalyst with the above configuration can be manufactured by a method including the following steps: loading a cocatalyst compound onto a support, and loading the first transition metal compound and the second transition metal compound onto the support. The loading order of the cocatalyst and the first and second transition metal compounds can be changed as needed. The first and second transition metal compounds can also be loaded simultaneously. Considering the influence of the loading order on the structure of the supported catalyst, loading the first and second transition metal compounds sequentially after loading the cocatalyst onto the support allows the manufactured supported catalyst to achieve high catalyst activity and better process stability in polyethylene production.

[0118] Furthermore, in the polymerization reaction, as described above, specific examples of α-olefin monomers include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, etc., and two or more of these may also be used. More specifically, the α-olefin monomer may be 1-hexene.

[0119] The amount of α-olefin monomer added can be determined based on the physical properties of the polyethylene to be manufactured. For example, considering the physical properties of the polyethylene to be achieved by the present invention, based on the total weight of the monomers including ethylene and α-olefin monomers, the amount of α-olefin monomer added can be 4 to 30% by weight, more specifically 4% or more by weight, or 8% or more by weight, or 10% or more by weight, or 12% or more by weight, and less than 30% by weight, or less than 25% by weight, or less than 20% by weight.

[0120] Furthermore, the polymerization reaction is carried out under conditions of hydrogen input.

[0121] Specifically, based on the total weight of the monomers including ethylene and α-olefin monomers, the hydrogen input can be from 10 to 50 ppm, more specifically, it can be above 10 ppm, or above 15 ppm, or above 20 ppm, or above 25 ppm, and below 50 ppm, or below 45 ppm, or below 40 ppm, or below 38 ppm, or below 35 ppm. When the hydrogen input is within this range, it is easier to achieve the aforementioned physical properties of polyethylene. If the polymerization reaction is carried out without the input of hydrogen, the melt index (MI) of the produced polyethylene may be significantly reduced.

[0122] Furthermore, the polymerization reaction can be carried out as a slurry polymerization reaction.

[0123] In solution polymerization, the catalyst is activated under high temperature and pressure, promoting catalyst decomposition and chain transfer. This results in a resin composition with a narrow molecular weight distribution and low content of high-molecular-weight tail chains. Consequently, when using resin compositions produced by solution polymerization to manufacture films, their molding and processing properties are poor. However, in the slurry polymerization process of this invention, because the polymerization reaction is carried out at a relatively low temperature, a molecular structure with a wide molecular weight distribution and high content of high-molecular-weight tail chains can be obtained, which is exactly what is needed for polyethylene resin compositions used to manufacture transparent films. Therefore, excellent molding and processing properties can be exhibited.

[0124] The slurry polymerization reaction can be carried out using a continuous slurry polymerization reactor or a loop slurry reactor.

[0125] Furthermore, during the slurry polymerization reaction, the hybrid supported catalyst can be injected by dissolving or diluting it in an aliphatic hydrocarbon solvent (e.g., isobutane, pentane, hexane, heptane, nonane, decane, and their isomers) having 4 to 12 carbon atoms, an aromatic hydrocarbon solvent (e.g., toluene and benzene), or a chlorine-substituted hydrocarbon solvent (e.g., dichloromethane and chlorobenzene). Preferably, before using the solvents used herein, the catalyst is treated with a small amount of alkylaluminum to remove trace amounts of water or air that act as catalyst poisons; a co-catalyst may also be used further.

[0126] Furthermore, the polymerization reaction can be carried out at temperatures above 40°C, or above 60°C, or above 80°C, and below 110°C, or below 100°C, or below 90°C. Moreover, if the pressure conditions during the polymerization reaction are further controlled, it can be carried out at pressures above 5 bar, or above 10 bar, or above 20 bar, or above 30 bar, and below 50 bar, or below 45 bar, or below 40 bar. When the polymerization reaction is carried out at such temperatures and pressures, the desired physical properties of polyethylene are more easily achieved.

[0127] The polyethylene manufactured using the above-described method possesses the aforementioned crystal distribution characteristics, molecular weight distribution characteristics, rheological properties, and processing properties. Therefore, the polyethylene exhibits excellent low-temperature sealing performance and hot tack, as well as excellent dart impact strength and stiffness, and a well-balanced and improved molding and processing performance. Thus, thinner films can be achieved when using the polyethylene to manufacture films, and the polyethylene is suitable for D4R applications. Furthermore, the polyethylene can be used to manufacture multi-purpose films such as food films, agricultural films, general industrial films, or stretch films, and is particularly suitable for All-PE sealing layers.

[0128] Therefore, the present invention provides a resin composition comprising the polyethylene, specifically a composition for film formation.

[0129] Furthermore, the present invention provides a film manufactured using the polyethylene or the resin composition.

[0130] The membrane can be manufactured according to conventional membrane manufacturing methods, the difference being the use of the polyethylene. For example, the membrane can be manufactured by blow molding, wherein the film-forming composition is prepared by containing only the aforementioned polyethylene, or by optionally mixing additives such as antioxidants and processing aids, and then extruded into a film using an extruder.

[0131] More specifically, the resin composition containing the polyethylene can be applied as a sealing layer and co-extruded with a composition for forming another film layer, or extruded using a blown film extruder or a cast film extruder. Alternatively, a film can be prepared from the resin composition containing the polyethylene on a substrate such as paper by extrusion coating, and then the prepared film can be laminated together with another film. However, the invention is not limited thereto, and various films can be made by any known manufacturing method.

[0132] Because the membrane contains the polyethylene, it has excellent low-temperature sealing performance, sealing stability, and process reliability.

[0133] Specifically, when the membrane is a single-layer membrane with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm, the seal initiation temperature (SIT) as measured according to ASTM F 1921 is below 85.0°C. More specifically, the sealing initiation temperature is below 85.0°C, or below 84.5°C, or below 84.0°C, or below 83.5°C, or below 83.0°C, or below 82.5°C, or below 82.0°C, or below 81.5°C, or below 80.0°C, or below 79.5°C, or below 79.0°C, or below 78.5°C, or below 78.0°C, or below 77.5°C, or below 77.0°C, or below 76.5°C, or below 76.0°C, or below 75.5°C, or below 75.0°C, or below 74.5°C, or below 74.0°C. Since the lower the sealing initiation temperature, the better the low-temperature sealing performance and sealing strength, there is no particular limitation on its lower limit value. For example, it can be above 60.0 °C, or above 61.0 °C, or above 62.0 °C, or above 63.0 °C, or above 64.0 °C, or above 65.0 °C, or above 66.0 °C, or above 67.0 °C, or above 68.0 °C, or above 69.0 °C, or above 70.0 °C, or above 71.0 °C, or above 72.0 °C, or above 73.0 °C.

[0134] For reference, the sealing initiation temperature refers to the temperature at which the heat seal strength reaches 2 N / 25.4 mm when the membrane is a single-layer membrane with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm, as measured according to ASTM F 1921 (sealing time 0.5 seconds, sealing pressure 0.3 MPa, delay time 30.0 seconds, tensile speed 200 mm / s, J&B 5000).

[0135] In addition to the aforementioned sealing properties, the polyethylene film also exhibits improved dart impact strength.

[0136] Specifically, when the membrane is a single-layer membrane with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm, the dart impact strength measured according to ASTM D 1709 [Method A] is greater than 900 gf, or greater than 950 gf, or greater than 1,000 gf, or greater than 1,150 gf. Since the higher the impact strength of the dart, the better, there is no particular upper limit. For example, it can be below 3,000 gf, or below 2,900 gf, or below 2,800 gf, or below 2,700 gf, or below 2,600 gf, or below 2,500 gf, or below 2,400 gf, or below 2,300 gf, or below 2,200 gf, or below 2,100 gf, or below 2,000 gf, or below 1,900 gf, or below 1,800 gf, or below 1,700 gf.

[0137] In addition to the sealing properties, the polyethylene film also exhibits improved transparency.

[0138] Specifically, when the membrane is a single-layer membrane with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm, the haze measured according to ASTM D1003 is below 23%, or below 22%, or below 21%, or below 20%, or below 19%, or below 18%, or below 17%, or below 16%, or below 15%, or below 14%, or below 13%. Since lower haze values ​​are better, there is no particular limitation on the lower limit; for example, it can be above 5%, or above 6%, or above 7%, or above 8%.

[0139] Furthermore, when the membrane is a single-layer membrane with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm, the 1% secant modulus in the MD direction of the membrane, measured using a universal testing machine (UTM) according to ASTM D882, is 1,500 kg / cm². 2 Above, or 1,600 kg / cm 2 Above, or 1,700 kg / cm 2 Above, or 1,800 kg / cm 2 The above indicates that the 1% secant modulus in the TD direction of the membrane is 1,800 kg / cm². 2 Above, or 1,900 kg / cm 2 Above, or 2,000 kg / cm 2 Above, or 2,100 kg / cm 2 above.

[0140] The secant modulus, as defined in ASTM D882, indicates the stiffness of a membrane. The secant modulus is density-dependent; higher density generally results in higher secant modulus and stiffness. Furthermore, a higher secant modulus generally indicates better membrane openability, visibility, and coefficient of friction (COF). Therefore, there is no specific upper limit to the secant modulus; for example, a membrane with a 1% secant modulus in the MD and TD directions can be 3,000 kg / cm². 2 Below, or 2,900 kg / cm 2 Below, or 2,800 kg / cm 2 Below, or 2,700 kg / cm 2 Below, or 2,600 kg / cm 2 Below, or 2,500 kg / cm 2 or 2,400 kg / cm 2 the following.

[0141] For reference, the sealing initiation temperature, haze, dart impact strength, and secant modulus mentioned above were measured for a film formed using a blown film extruder (die diameter 120 mm, die gap 2.0 mm, BUR 2.5, dual air ring system) from a composition of the polyethylene of the present invention comprising 95% or more, or 96% or more, or 97% or more, or 98% or more, or 99% or more, or 99.9% or more of the total composition, into a single-layer film with a thickness of 45 to 55 µm, or 48 to 52 µm, more specifically 50 µm.

[0142] The following are some preferred embodiments to aid in understanding the present invention. However, these embodiments are provided merely to help better understand the present invention, and the scope of the present invention is not limited thereto.

[0143] Meanwhile, in this instruction manual, "room temperature" refers to 23±2℃.

[0144] <Preparation of Transition Metal Compounds> Synthesis example 1

[0145] Preparation of ligands TMCp (tetramethylcyclopentadiene, 1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25 °C with stirring at room temperature for 3 hours. To the resulting reactant, t-BuOHexSiMeCl2 (1.00 equivalent) was added at -10 °C and stirred overnight at room temperature. All solvents were dried under vacuum, and then tBuNH2 (10 equivalent) was added with stirring overnight at room temperature. Afterwards, post-treatment with water was performed, followed by drying to obtain the ligand.

[0146] Preparation of transition metal compounds The ligand prepared above was dissolved in toluene (0.3 M), and n-BuLi (2.05 equivalents) was added at -25 °C and stirred at room temperature for 3 hours. TiCl4(THF)2 (titanium tetrachloride tetrahydrofuran adduct, 1 equivalent) was prepared in another flask in a glove box. The ligand-Li was transferred to this flask using a sleeve at -25 °C, and washed and transferred with toluene (1.0 M).

[0147] After the reaction was complete, the solvent was dried under vacuum, DCM was added back, LiCl was removed by filtration, and the filtrate was dried under vacuum to obtain a liquid transition metal compound (Cat1).

[0148] 1 H NMR (500 MHz, CDCl3) δ 3.34 (t, 2H), 2.24 (d, J = 1.7 Hz, 6H), 2.13 (d, J = 3.2 Hz, 6H), 1.57 - 1.45 (m, 6H), 1.42 (s, 9H), 1.32 - 1.22 (m,4H), 1.18 (s, 9H), 0.67 (s, 3H).

[0149] Synthesis example 2-1 (Cat 2-1) Indene (1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25 °C while stirring at room temperature for 3 hours. Subsequently, CH3-I (1.05 equivalent) was added at -10 °C, and the mixture was stirred overnight at room temperature. The mixture was then treated with water and dried to give 3-methylindene. The synthesized 3-methylindene (1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25 °C while stirring at room temperature for 3 hours. Subsequently, CH3-I (1.05 equivalent) was added at -10 °C, and the mixture was stirred overnight at room temperature. The mixture was then treated with water and dried to give 1,3-dimethylindene.

[0150] Preparation of transition metal compounds The ligand prepared above was dissolved in diethyl ether (0.3 M), and n-BuLi (1.05 equivalents) was added at -25 °C and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (pentamethylcyclopentadienyl zirconium trichloride) (1 equivalent) was prepared in another flask. The ligand-Li was transferred to this flask using a sleeve at -25 °C, and washed and transferred with diethyl ether (1.0 M).

[0151] After the reaction was complete, the solvent was dried under vacuum, DCM was added back, LiCl was removed by filtration, the filtrate was dried under vacuum, and then slurried with hexane. The resulting solid was then filtered and dried under vacuum to obtain a solid metallocene intermediate.

[0152] In a glove box, the metallocene intermediate was placed in a mini-parr, and 5 mol% Pd / C (10 wt%) was added. A magnetic stir bar was added to the parr, and the parr was removed from the glove box as a closed system. DCM (0.5 M) was added to the parr, and H2 (10 barg) was introduced. The vent-charge process was repeated three times, and then the parr was placed in a 40°C oil bath with stirring. When the pressure in the parr was reduced to below 5 barg, the venting process was repeated until no more hydrogen was consumed. After the reaction was complete, the remaining H2 was vented and replaced with Ar gas. After cooling to room temperature, the filtrate was filtered through a sleeve and dried under vacuum. The dried filtrate was slurried with hexane and then filtered to obtain a solid transition metal compound (Cat 2-1).

[0153] 1 H NMR (500 MHz, CDCl3) δ 5.60 (s, 1H), 2.90 (dt, J = 16.4, 6.3 Hz, 2H), 2.32 (dt, J = 16.3, 6.0 Hz, 2H), 2.04 (s, 15H), 1.79 - 1.66 (m, 2H), 1.67 (s, 6H), 1.64 - 1.54 (m, 2H).

[0154] Synthesis example 2-2 (Cat 2-2) Indene (1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25 °C while stirring at room temperature for 3 hours. Subsequently, CH3-I (1.05 equivalent) was added at -10 °C, and the mixture was stirred overnight at room temperature. After post-treatment with water, the mixture was dried to obtain 3-methylindene. Alternatively, the synthesized 3-methylindene (1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25 °C while stirring at room temperature for 3 hours. Subsequently, tert-butoxyhexyl iodine (1.05 equivalent) was added at -10 °C, and the mixture was stirred overnight at room temperature. After post-treatment with water, the mixture was dried to obtain 1-methyl-3-(tert-butoxyhexyl)indene.

[0155] Preparation of transition metal compounds The ligand prepared above was dissolved in diethyl ether (0.3 M), and n-BuLi (1.05 equivalents) was added at -25°C and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (pentamethylcyclopentadienyl zirconium trichloride) (1 equivalent) was prepared in another flask. At -25°C, the ligand-Li was transferred to this flask using a sleeve, and washed with diethyl ether (1.0 M) and transferred.

[0156] After the reaction was complete, the solvent was dried under vacuum, DCM was added back, LiCl was removed by filtration, the filtrate was dried under vacuum, and then slurried with hexane. The resulting solid was then filtered and dried under vacuum to obtain a solid metallocene intermediate.

[0157] In a glove box, the metallocene intermediate was placed in a small reactor, and 5 mol% Pd / C (10 wt%) was added. A magnetic stir bar was added to the reactor, and the reactor was removed from the glove box as a closed system. DCM (0.5 M) was added to the reactor, and H2 (10 barg) was introduced. The purging-gas cycle was repeated three times, and then the reactor was placed in a 40°C oil bath with stirring. When the reactor pressure dropped below 5 barg, the purging process was repeated until no more hydrogen was consumed. After the reaction was complete, the remaining H2 was purged and replaced with Ar gas. After cooling to room temperature, the filtrate was filtered through a sleeve and dried under vacuum. The dried filtrate was slurried with hexane and then filtered to obtain a solid transition metal compound (Cat 2-2).

[0158] 1 H NMR (500 MHz, CDCl3) δ 5.57 (s, 1H), 3.31 (t, J = 6.7 Hz, 2H), 2.95 - 2.85 (m, 2H), 2.37 - 2.28 (m, 2H), 2.18 - 2.03 (m, 2H), 2.02 (s, 15H),1.96 - 1.88 (m, 1H), 1.82 - 1.77 (m, 1H), 1.75 (s, 3H), 1.71 - 1.55 (m, 3H),1.53 - 1.36 (m, 4H), 1.36 - 1.20 (m, 3H), 1.18 (s, 9H).

[0159] Synthesis example 2-3 (Cat 2-3) Preparation of ligands Indene (1 equivalent) was dissolved in THF (0.3 M), and then n-BuLi (1.05 equivalent) was slowly added dropwise at -25°C while stirring at room temperature for 3 hours. Subsequently, chloroform iodine (1.05 equivalent) was added at -10°C and stirred overnight at room temperature. After treatment with water and drying, 3-ethylindene was obtained.

[0160] Preparation of transition metal compounds The ligand prepared above was dissolved in diethyl ether (0.3 M), and then n-BuLi (1.05 equivalents) was added at -25 °C and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (pentamethylcyclopentadienyl zirconium trichloride) (1 equivalent) was prepared in another flask. At -25 °C, the ligand-Li was transferred to this flask using a sleeve, and washed and transferred with diethyl ether (1.0 M).

[0161] After the reaction was complete, the solvent was dried under vacuum, DCM was added back in, LiCl was removed by filtration, the filtrate was dried under vacuum, and then slurried with hexane. The resulting solid was then filtered and dried under vacuum to obtain a solid metallocene intermediate.

[0162] In a glove box, the metallocene intermediate was placed in a small reactor, and 5 mol% Pd / C (10 wt%) was added. A magnetic stir bar was added, and the reactor was removed from the glove box as a closed system. DCM (0.5 M) was added to the reaction system, and H2 (10 barg) was introduced. The purging-gas cycle was repeated three times, and then the reaction system was placed in a 40°C oil bath and stirred. When the pressure of the reaction system dropped below 5 barg, the purging process was repeated until no more hydrogen was consumed. After the reaction was complete, the remaining H2 was purged and replaced with Ar gas. After cooling to room temperature, the filtrate was filtered through a sleeve and dried under vacuum. The dried filtrate was slurried with hexane and then filtered to obtain a solid transition metal compound (Cat 2-3).

[0163] 1 H NMR (500 MHz, CDCl3) δ 5.60 (d, J = 2.7 Hz, 2H), 5.20 (d, J = 2.7Hz, 2H), 2.83 - 2.71 (m, 2H), 2.49 - 2.36 (m, 3H), 2.21 (dd, J = 15.1, 7.6Hz, 1H), 2.01 (s, 15H), 1.98 - 1.80 (m, 2H), 1.66 - 1.51 (m, 2H), 1.03 (t, J= 7.6 Hz, 3H).

[0164] <Catalyst Preparation> Preparation Example 1 In a 20 L SUS high-pressure reactor, 2.0 kg of toluene and 1000 g of silica (SP2410, purchased from Grace Davison) were added, and the reactor temperature was raised to 40 °C with stirring. Then, 5.4 kg of methylaluminoxane (10 wt% toluene solution, purchased from Albemarle) was added to the reactor, and the temperature was raised to 70 °C. The mixture was then stirred at approximately 200 rpm for about 12 hours. Afterward, the reactor temperature was lowered to 40 °C, and stirring was stopped. The reaction product was allowed to stand for about 10 minutes before decantation. Another 2.0 kg of toluene was added to the reaction product, and the mixture was stirred for about 10 minutes. Stirring was then stopped, and the mixture was allowed to stand for about 30 minutes before decantation.

[0165] 2.0 kg of toluene was added to the reactor, followed by compound (Cat 1) (50 mmol) prepared in Synthesis Example 1 as the first transition metal compound and compound (Cat 2-2) (10 mmol) prepared in Synthesis Example 2-2 as the second transition metal compound, along with 1000 mL of toluene. The reactor temperature was raised to 85°C and stirred for approximately 90 minutes.

[0166] The reactor temperature was then lowered to room temperature, stirring was stopped, and the reaction was allowed to stand for about 30 minutes before the reaction product was decanted. Subsequently, 3 kg of hexane was added to the reactor, and the hexane slurry was transferred to a 20 L filter dryer for filtration and then dried under reduced pressure at 50 °C for about 4 hours to obtain 1.5 kg of hybrid metallocene catalyst.

[0167]

[0168] Preparation Examples 2 to 4 Except for changing the types of the first and second transition metal compounds as shown in Table 1 below, hybrid supported metallocene catalysts were prepared in the same manner as in Preparation Example 1.

[0169] Table 1

[0170] <Preparation of Polyethylene> Examples 1-1 to 4-1 A 140 L continuous polymerization reactor was prepared for use as the polymerization reactor. This reactor was capable of performing isobutylene slurry loop processes and operated at a reaction flow rate of approximately 7 m / s. The reactants required for polyethylene polymerization were then continuously introduced into the reactor according to Table 2. The catalysts used in each polymerization reaction were the catalysts prepared in the preparation examples described in Table 1, and these catalysts were mixed with the isobutylene slurry and introduced into the reactor. Furthermore, the polymerization reactions were carried out at a pressure of approximately 40 bar and a temperature of approximately 85°C. Other key conditions for the polymerization reactions are shown in Table 2 below.

[0171] Comparative Example 1-1 HP1018, a copolymer of ethylene and 1-hexene from LG Chem, was used.

[0172] Comparative Example 2-1 LG Chem's copolymer of ethylene and 1-hexene, XM3108, was used.

[0173] Comparative Example 3-1 LG Chem's copolymer of ethylene and 1-hexene, XM3137, was used.

[0174] Comparative Example 4-1 LG Chem's copolymer of ethylene and 1-octene, LF100A, was used.

[0175] Table 2

[0176] In Table 2 above, the activity (kgPE / kgSiO2·hr) is calculated as the ratio of the weight of polymer generated (kgPE) to the weight of catalyst used (kg) per unit time (hr).

[0177] Furthermore, the input of 1-hexene (wt%) is calculated as: the percentage of 1-hexene input based on the total weight of monomers including ethylene and 1-hexene; and the input of hydrogen (ppm) is based on the total weight of monomers including ethylene and 1-hexene.

[0178] <Membrane Preparation> A film was prepared using the polyethylene prepared in the Examples and Comparative Examples according to the following method.

[0179] Examples 1-2 to 4-2, Comparative Examples 1-2 to 4-2 Based on the total weight of polyethylene prepared in the examples or comparative examples, 1200 ppm of antioxidant (Songnox 1076 (Songwon):Songnox 1680 (Songwon) = 1:2 by weight) was added and mixed, and then extruded using a twin-screw extruder (TEK 30 MHS, purchased from SMPLATECH, diameter 32 phi, L / D=40) at an extrusion temperature of 190°C and an extrusion rate of 35 kg / h to prepare approximately 18 kg of granular composition for film formation.

[0180] The above-prepared film-forming composition is blown into a film under the following film extrusion conditions.

[0181] <Membrane Forming Conditions> Single-screw extruder (Yujin Engineering's single-screw extruder, blown film M / C, 50 phi, L / D=32) Melt temperature (or extrusion temperature): 185℃ Mold clearance: 2.0mm Mold diameter: 120mm Inflation ratio: 2.5 The height of the frost line should be maintained at 200~250mm. Sample extrusion rate: 300~500 g / min Cooling: Dual air rings are used Membrane thickness: 50 μm Experimental Example 1 The physical properties of the polyethylene prepared in the examples and comparative examples were measured as follows, and the results are shown in Tables 3 and 5.

[0182] (1) Melt index (MI) 2.16 ): Measured according to ASTM D1238 (condition E, 190°C, 2.16 kg load).

[0183] (2) Density: Measured according to ASTM D1505.

[0184] (3) Molecular weight distribution (MWD) For the polyethylene in the embodiments and comparative examples, the weight-average molecular weight (Mw, g / mol) and number-average molecular weight (Mn, g / mol) were determined by gel permeation chromatography (GPC), and the molecular weight distribution (MWD, Mw / Mn) was obtained by dividing the weight-average molecular weight by the number-average molecular weight.

[0185] Specifically, a Polymer Char GPC-IR® instrument was used as the gel permeation chromatography (GPC) apparatus, employing a Polymer Laboratories PLgel MIX-B 300 mm column. The measurement temperature was 160 °C, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was 1 mL / min. For each polyethylene sample prepared in the examples and comparative examples, pretreatment was performed by dissolving the polyethylene sample in 1,2,4-trichlorobenzene containing 0.003% BHT at 160 °C for 2 hours using a GPC analyzer (Polymer Char GPC-IR®), followed by preparation of a 16 mg / 8 mL solution, with 200 μL used as the sample. Mw and Mn values ​​were calculated using a calibration curve plotted using polystyrene standards. Nine polystyrene standard samples were used, with weight-average molecular weights of 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 10000000 g / mol.

[0186] (4) Rheological properties The storage modulus (G') and loss modulus (G'') of polyethylene in the embodiments and comparative examples were measured in frequency scanning mode using a rotational rheometer (TA Instruments ARES-G2 rheometer).

[0187] Specifically, to minimize polyethylene degradation, the rheometer's test chamber was purged with nitrogen, and the rheometer was preheated to an initial temperature of 190°C. After the sample was loaded and equilibrated in the oven, the prepared sample was placed between parallel plates of the rheometer (plate diameter 25.4 mm, plate spacing 2 mm) and compressed to a thickness of 2.0 mm. A vacuum shear flow was applied at 5% strain within an angular frequency range of 0.05 to 500 rad / s under a nitrogen atmosphere. The strain was maintained below 5% to satisfy the linear viscoelastic condition. A total of 8 minutes elapsed from the time the sample was inserted between the plates to the start of the frequency scan (0.03–100 rad / s), and the measurements were performed at 190°C. New samples were used at each temperature, and nitrogen (N2) was circulated within the test chamber for each measurement.

[0188] Through the above measurements, the relationship between the energy storage modulus (G') and the loss modulus (G”) and the angular velocity (ω) was obtained.

[0189] Based on the above rheological property measurement results, the shear stress and RSS were calculated according to Equation 1 below. 50and RSS 125 .

[0190] [Equation 1]

[0191] In equation 1 above, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency scanning mode at 190°C and an angular velocity of ω = 125 rad / s.

[0192] RSS 50 yes ,in, It is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency scanning mode at a temperature of 190°C and an angular velocity of ω = 50 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity ω = 50 rad / s. RSS 125 yes ,in, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency scanning mode at 190°C and an angular velocity of ω = 125 rad / s.

[0193] Furthermore, the storage modulus and loss modulus measured above are calculated as shear stress based on the shear rate. Figure 1 The graph is shown with shear rate as the x-axis and shear stress as the y-axis.

[0194] Reference Figure 1 When the y-axis is 0.2 MPa (200000 Pa), the shear rate value on the x-axis is the critical shear rate.

[0195] Experimental Example 2 The physical properties of the membranes prepared in the examples and comparative examples were measured as follows, and the results are shown in Tables 4 and 6 below.

[0196] (1) Impact intensity of the falling dart For the membranes prepared in the above examples and comparative examples, the dart impact strength was measured according to ASTM D1709 [Method A] standard. Each membrane sample was measured in more than 5 groups (20 times per group), and the average value was taken.

[0197] (2) Sealing start temperature (SIT) According to ASTM F 1921, using a J&B hot tack tester (Hot tacker 5000), the seal strength was measured at 5°C intervals between 60°C and 130°C under the conditions of a sealing time of 0.5 seconds, a sealing pressure of 0.3 MPa, a delay time of 30.0 seconds, and a tensile speed of 200 mm / s. The temperature at which the heat seal strength reaches 2 N / 25.4 mm was taken as the seal initiation temperature (SIT).

[0198] In the unit N / 25.4 mm, "25.4 mm" represents the width of the sealed membrane sample to be tested.

[0199] (3) Haze According to ASTM D1003, the refractive index (%) of the films of each embodiment and comparative example under illumination was measured using a haze meter (HM-150). Haze was calculated as: Td (refracted light) / Tt (transmitted light) × 100 (%). Each film sample was measured more than 10 times, and the average value was taken.

[0200] (4) Secant modulus For the membranes in the embodiments and comparative examples, the 1% secant modulus of the membranes in the longitudinal (MD) and transverse (TD) directions was measured using an Instron UTM (universal testing machine) according to ASTM D882.

[0201] (5) Melt fracture For the polyethylene in the embodiments and comparative examples, melt fracture of the extrudate was confirmed using a capillary rheometer (R315-H9) under the conditions of piston size of 12 mm, orifice diameter L / D=20 / 2, temperature of 190 °C, and shear rate of 300 1 / s. In order to determine the surface morphology of the extrudate, it was photographed using a stereo microscope (Olympus SZX16) at 20x magnification.

[0202] Images of the various embodiments and comparative examples are as follows: Figure 2 As shown.

[0203] Table 3

[0204] Table 4

[0205] Table 5

[0206] Table 6

[0207] Referring to Tables 3 to 6, the polyethylene in the embodiments of the present invention satisfies a shear stress of less than 0.20 MPa and an RSS of... 125 The relationship between the haze and the membrane transparency satisfies the predetermined range of Equation 2, thus confirming that excellent flow stability and membrane transparency can be maintained simultaneously even during high-speed membrane processing. In contrast, the shear stress or RSS of the polyethylene in the comparative example... 125 The relationship between haze and the specified range does not satisfy the given range, therefore it can be determined that melt fracture occurred during extrusion, or that the stiffness is low as measured by the secant modulus.

[0208] In addition, refer to Figure 2 In Comparative Examples 1, 2 and 3, it can be determined that the surface of the extrudate has an uneven fracture morphology.

Claims

1. A polyethylene having a shear stress of 0.2 MPa or less, as expressed by Equation 1 below, and satisfying Equation 2 below: [Equation 1] In equation 1 above, The storage modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity ω = 125 rad / s. [Equation 2] In equation 2 above, RSS 125 yes ,in, The storage modulus (in MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity of ω = 125 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

2. The polyethylene according to claim 1, wherein, The critical shear rate, which is the shear rate at a shear stress of 0.2 MPa, is above 125 rad / s.

3. The polyethylene according to claim 1, satisfying the following equation 3: [Equation 3] In equation 3 above, RSS 50 yes ,in, It is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency scanning mode at 190°C and an angular velocity ω = 50 rad / s. The loss modulus (unit: MPa) was measured using a rotational rheometer (ARES-G2) in frequency sweep mode at 190°C and an angular velocity ω = 50 rad / s. H is the haze value (in %) of a film containing the polyethylene with a thickness of 45 to 55 µm, measured according to ASTM D1003.

4. The polyethylene according to claim 1, wherein, The density, measured according to ASTM D1505, is 0.900 to 0.925 g / cm³. 3 .

5. The polyethylene according to claim 1, wherein, The molecular weight distribution (MWD) ranges from 2.0 to 5.

0.

6. The polyethylene according to claim 1, wherein, The polyethylene, measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg, has a melt index of 0.5 to 5.0 g / 10 min.

7. The polyethylene according to claim 1, wherein, The polyethylene is a copolymer of ethylene and α-olefin.

8. The polyethylene according to claim 7, wherein, The α-olefin is 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene.

9. A membrane comprising the polyethylene as described in claim 1.

10. The membrane according to claim 9, wherein, When the membrane thickness is 45 to 55 µm, the seal initiation temperature (SIT) measured according to ASTM F 1921 is below 85.0 °C.

11. The membrane according to claim 10, wherein, When the film thickness is 45 to 55 µm, the dart impact strength measured according to ASTM D 1709 is above 900 gf.

12. The membrane according to claim 9, wherein, When the film thickness is 45 to 55 µm, the 1% secant modulus in the MD direction, measured according to ASTM D882, is 1500 kg / cm². 2 The 1% secant modulus in the TD direction is 1800 kg / cm². 2 above.

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