Polyethylene composition and biaxially stretched film comprising the same

Abstract

The present invention provides a polyethylene composition and a biaxially-stretched film comprising the same, the composition having excellent mechanical properties and stretch stability, as well as outstanding film processability and productivity, suitable for producing a biaxially-stretched film having high shrink resistance, printability and transparency.

Description

Cross-references to related applications

[0001] This application claims priority to Korean Patent Application Nos. 10-2024-0013787 and 10-2025-0011591, filed with the Korean Intellectual Property Office on January 30, 2024 and January 24, 2025, respectively, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a polyethylene composition and a biaxially stretched film comprising the composition, the composition having excellent mechanical properties and tensile stability, as well as excellent film processability and productivity, suitable for producing biaxially stretched films with high shrinkage resistance, printability and transparency. Background Technology

[0003] Shrink films made of linear low-density polyethylene (LLDPE) and / or high-density polyethylene (HDPE) are widely used in packaging applications such as shopping bags, food and specialty packaging, and industrial liners. In these applications, shrink films, which can wrap products and maintain their shape, are primarily used to protect products from contact during display.

[0004] In particular, among these shrink films, biaxially oriented polymer films possess excellent mechanical properties, productivity, and printability, thus finding widespread application in packaging. Commercially available packaging films typically use biaxially oriented polypropylene (BOPP), biaxially oriented polyethylene terephthalate (BOPET), or biaxially oriented polyamide (BOPA) as the printing layer and LLDPE as the sealing layer. These composite materials are not recyclable, and due to the implementation of packaging material recycling regulations, the demand for single-material packaging films is increasing. Therefore, research and development efforts are underway to manufacture single-material packaging films by replacing the printed layer films with biaxially oriented polyethylene (BOPE) films.

[0005] However, commercially available polyethylene (PE) resins lack sufficient tensile stability, easily experiencing breakage and melting during stretching, making them unsuitable for biaxial stretching processes. To ensure tensile stability, a product has been developed in the form of a polyethylene composition containing a low-density, high melt index resin. However, due to its lower stiffness, shrinkage, and impact resistance, this composition is not suitable as a polyethylene resin for biaxially stretched films. Furthermore, its high processing viscosity may lead to reduced film productivity, and the formation of fine patterns due to high processing pressure results in poor film appearance.

[0006] Therefore, a method is needed to select polyethylene resins with molecular structures that are favorable for stretching, and to select suitable compositions that provide biaxially stretched polyethylene compositions that exhibit excellent tensile stability, outstanding mechanical properties, good film processability, and productivity due to their low processing viscosity. Summary of the Invention

[0007] Technical issues The present invention provides a polyethylene composition and a biaxially stretched film comprising the composition, the composition having excellent mechanical properties and tensile stability, as well as excellent film processability and productivity, and is suitable for producing biaxially stretched films with high shrinkage resistance, printability and transparency.

[0008] Technical solution According to one embodiment of the present disclosure, a polyethylene composition is provided comprising at least one ethylene-α-olefin copolymer, wherein, according to cross-fractional chromatography (CFC) analysis of the polyethylene composition: The high crystallinity fraction eluted at temperatures above 90°C accounts for more than 50 wt% to less than 80 wt% of the total eluted fraction; The weight-average molecular weight (Mw) of the highly crystallinity fraction is above 140,000 g / mol and below 180,000 g / mol; The medium-crystallinity fraction eluted at temperatures above 70°C and below 90°C accounts for more than 10 wt% and less than 45 wt% of the total eluted fraction; and The weight-average molecular weight (Mw) of the medium crystallinity fraction is above 50,000 g / mol and below 80,000 g / mol.

[0009] In another embodiment of this disclosure, a biaxially stretched film comprising the polyethylene composition of the above embodiments is provided.

[0010] The terminology used herein is for describing particular implementations only and is not intended to limit the invention.

[0011] Unless the context clearly specifies otherwise, the singular form should also include the plural form.

[0012] In this disclosure, terms such as “comprising,” “including,” or “having” are used to describe the features, quantities, steps, components, or combinations thereof, and do not exclude the addition of one or more other features, quantities, steps, components, or combinations thereof.

[0013] The terms “approximately” or “substantially” are intended to mean approximately, within permissible error, a value or range specifically specified, and are intended to prevent the precise or absolute values ​​disclosed for the purpose of understanding this invention from being used unlawfully or unfairly by any improper third party.

[0014] Furthermore, in this disclosure, the (co)polymer includes homopolymers and copolymers.

[0015] Unless otherwise defined herein, “copolymer” can mean block copolymer, random copolymer, graft copolymer or alternating copolymer, and “polymer” can mean block copolymer, random copolymer, graft copolymer or alternating copolymer.

[0016] Because the present invention can be modified in various ways and has various forms, specific embodiments will be shown and described in detail. However, it is not intended to limit the invention to the specific forms disclosed, and it should be understood that the invention includes all modifications, equivalents, and alternatives within its concept and scope of skill.

[0017] The following will describe this disclosure in more detail.

[0018] Polyethylene composition According to one aspect of the present invention, a polyethylene composition is provided comprising at least one ethylene-α-olefin copolymer, wherein, according to cross-fractional chromatography (CFC) analysis of the polyethylene composition: a highly crystalline fraction eluted at a temperature above 90°C accounts for 50 wt% to 80 wt% of the total eluted fraction; the weight-average molecular weight (Mw) of the highly crystalline fraction is 140,000 g / mol to 180,000 g / mol; a moderately crystalline fraction eluted at a temperature above 70°C and below 90°C accounts for 10 wt% to 45 wt% of the total eluted fraction; and the weight-average molecular weight (Mw) of the moderately crystalline fraction is 50,000 g / mol to 80,000 g / mol.

[0019] In this disclosure, the term "parts by weight" as used herein refers to a relative concept of the ratio of the weight of the remaining materials to the weight of a particular material. For example, in a mixture containing 50g of material A, 20g of material B, and 30g of material C, based on 100 parts by weight of material A, the amounts of material B and material C are 40 parts by weight and 60 parts by weight, respectively.

[0020] Meanwhile, "weight percentage (wt%)" refers to the absolute concept of expressing the weight of a specific material as a percentage based on the total weight. In the above mixture, based on 100% of the total weight of the mixture, the contents of materials A, B, and C are 50wt%, 20wt%, and 30wt%, respectively.

[0021] In the polyethylene composition disclosed herein, a first ethylene-α-olefin copolymer with excellent mechanical properties is blended with a second ethylene-α-olefin copolymer with excellent flowability, thereby imparting tensile properties, by applying specific metallocene catalysts (described in detail below), thereby adjusting the balance between mechanical properties and elongation. Therefore, this composition possesses characteristics suitable for manufacturing biaxially stretched films with high shrinkage resistance, printability, and transparency, while maintaining mechanical properties, productivity, and tensile stability comparable to or better than conventional films.

[0022] Preferably, the polyethylene composition may contain two or more ethylene-α-olefin copolymers. More preferably, the polyethylene composition may contain two types of ethylene-α-olefin copolymers.

[0023] Furthermore, according to cross-fractional chromatography (CFC) analysis of the polyethylene composition, the highly crystalline fraction eluted at temperatures above 90°C (T≥90°C) accounts for more than 50 wt% to less than 80 wt% of the total eluted fraction, with a weight-average molecular weight (Mw) of more than 140,000 g / mol to less than 180,000 g / mol; the moderately crystalline fraction eluted at temperatures above 70°C and below 90°C (T≥70°C, <90°C) accounts for more than 10 wt% to less than 45 wt% of the total eluted fraction, with a weight-average molecular weight (Mw) of more than 50,000 g / mol to less than 80,000 g / mol.

[0024] Preferably, the weight percentage of the high crystallinity fraction (T≥90°C) can be 51 wt% or more, or 51.5 wt% or more, or 52 wt% or more, or 52.5 wt% or more, or 53 wt% or more, or 53.5 wt% or more, or 53.8 wt% or more, or 54 wt% or more, or 54.2 wt% or more, or 54.5 wt% or more, or 54.6 wt% or more, while being less than 78 wt% or less, or 75 wt% or less, or 72 wt% or less, or 70 wt% or less, or 67.5 wt% or less, or 65 wt% or less, or 64.8 wt% or less, or 64.5 wt% or less, or 63.5 wt% or less, or 63 wt% or less. More preferably, the content of the high crystallinity fraction (T≥90°C) in the polyethylene composition can be 54.6 wt% or more and less than 63 wt%.

[0025] Furthermore, from the perspective of improving the stress relaxation rate of the polyethylene composition, thereby enabling the film to stabilize rapidly and reduce shrinkage during stretching, the weight-average molecular weight (Mw, T≥90℃) of the high crystallinity fraction (T≥90℃) of the composition can be below 180,000 g / mol, or below 178,000 g / mol, or below 175,000 g / mol, or below 173,000 g / mol, or below 170,000 g / mol, or below 168,000 g / mol, or below 165,000 g / mol, or below 163,000 g / mol, or below 160,000 g / mol, or below 158,000 g / mol, or below 155,000 g / mol, or below 153,000 g / mol, or below 151,000 g / mol. In addition, to maintain excellent mechanical properties of the film, the weight-average molecular weight (Mw) of the high crystallinity fraction backbone is also important. 主，T≥90℃ Preferably, the molecular weight (Mw, T≥90℃) of the high crystallinity fraction of the polyethylene composition is 140,000 g / mol or more, or 142,000 g / mol or more, or 145,000 g / mol or more, or 146,000 g / mol or more, or 147,000 g / mol or more. More preferably, the weight-average molecular weight (Mw, T≥90℃) of the high crystallinity fraction of the polyethylene composition can be 147,000 g / mol or more and 151,000 g / mol or less.

[0026] In this disclosure, cross-fractional chromatography (CFC) analysis can be specifically performed using the following methods. For example, such cross-fractional chromatography (CFC) analysis is described in Test Example 2 below.

[0027] Cross-fractional chromatography (CFC) measurement conditions (including TREF and GPC-IR analysis) - Instrument: Polymer Char CFC (Detector: Integrated IR5 MCT detector) - Sample preparation and loading: Place 32 mg of the polyethylene composition in a 10 mL vial, load it into an autosampler, add 8 mL of 1,2,4-trichlorobenzene (TCB), heat at 160 °C for 90 minutes to dissolve, then extract the sample by purging with nitrogen and loading it onto a temperature elution fractionation (TREF) column.

[0028] - Crystallization: The sample temperature loaded into the TREF column is adjusted to 100°C, and then cooled from 100°C to 35°C at a rate of 0.5°C / min.

[0029] - Temperature-elution fractionation (TREF) analysis: After crystallization, the temperature was increased from 35°C to 125°C in 3°C increments, held at each temperature for 25 minutes, to analyze the elution fractions. Specifically, extraction and analysis were performed at 35°C for 25 minutes, followed by stepwise temperature increases in 3°C increments, and finally held at 125°C for 25 minutes.

[0030] - GPC-IR Analysis: Fractions eluted at each temperature during the TREF analysis were transferred to a GPC (PL-GPC220) column to determine the molecular weight of the eluted molecules. The content of short-chain branches (scb) in the eluted molecules was determined using a connected PerkinElmer Spectrum 100 FT-IR spectrometer.

[0031] - Main chain average molecular weight (Mw) 主，T≥90℃ Determination of molecular weight (Mw): In fractions eluted at temperatures above 90°C as confirmed by CFC analysis, the weight-average molecular weight (Mw) of the main chain (excluding short-chain branches) is determined according to Formula 1. 主，T≥90℃ (g / mol).

[0032] [Formula 1] Mw 主,T≥90℃ (g / mol)=

[0033] In Formula 1, M T,i and C T,i These are the weight-average molecular weight (g / mol) and concentration of each fraction eluted at a given temperature, as determined by the CFC analysis described above. n scb T,i It is the number of side chains (scb) of each fraction eluted at a given temperature, as determined by the CFC analysis described above. M scb It is the weight-average molecular weight (g / mol) of the side chain branches (scb) determined by CFC analysis.

[0034] Specifically, the weight-average molecular weight (Mw) of the main chain of the high-crystallinity fraction in the polyethylene composition was determined by cross-fractional chromatography (CFC). 主, T≥90℃ The molecular weight (Mw) can be above 130,000 g / mol and below 175,000 g / mol. Preferably, in order to improve the stress relaxation rate of the polyethylene composition and reduce the shrinkage rate by rapidly stabilizing the film during stretching, the main chain weight-average molecular weight (Mw) is [value missing]. 主，T≥90℃The molecular weight (Mw) can be below 160,000 g / mol, or below 158,000 g / mol, or below 155,000 g / mol, or below 153,000 g / mol, or below 150,000 g / mol, or below 148,000 g / mol, or below 145,000 g / mol, or below 143,000 g / mol, or below 142,000 g / mol. However, to maintain excellent mechanical properties of the membrane, the main chain weight-average molecular weight (Mw) is... 主，T≥90℃ The concentration of the polyethylene composition can be 60,000 g / mol or more, or 70,000 g / mol or more, or 80,000 g / mol or more, or 90,000 g / mol or more, or 100,000 g / mol or more, or 105,000 g / mol or more, or 110,000 g / mol or more, or 115,000 g / mol or more, or 120,000 g / mol or more, or 125,000 g / mol or more, or 130,000 g / mol or more, or 135,000 g / mol or more, or 139,000 g / mol or more. More preferably, the Mw of the polyethylene composition... 主，T≥90℃ It can be above 139,000 g / mol and below 142,000 g / mol.

[0035] Meanwhile, according to cross-fractional chromatography (CFC) analysis of the polyethylene composition, the medium crystallinity fraction (T≥70℃, <90℃) eluted at temperatures above 70℃ and below 90℃ accounted for more than 10 wt% to less than 45 wt% of the total eluted fraction. The weight-average molecular weight (Mw) of this medium crystallinity fraction (T≥70℃, <90℃) was more than 50,000 g / mol and less than 80,000 g / mol.

[0036] Preferably, the content of the medium crystallinity fraction (T≥70℃, <90℃) in the total eluted fraction can be 10 wt% or more, or 10.2 wt% or more, or 10.5 wt% or more, or 10.6 wt% or more, or 10.7 wt% or more, or 10.8 wt% or more, or 11 wt% or more, or 11.2 wt% or more, or 11.3 wt% or more, while being less than 45 wt%, or less than 42 wt%, or less than 40 wt%, or less than 38 wt%, or less than 35 wt%, or less than 30 wt%, or less than 28 wt%, or less than 25 wt%, or less than 20 wt%, or less than 18 wt%, or less than 17.5 wt%. More preferably, the polyethylene composition has a medium crystallinity fraction (T≥70℃, <90℃) content of 11.3wt% or more and 17.5wt% or less.

[0037] Furthermore, for the medium crystallinity fraction (T≥70℃, <90℃), from the perspective of improving the stress relaxation rate of the polyethylene composition (thereby rapidly stabilizing the film and reducing shrinkage during stretching), the weight-average molecular weight (Mw) of the medium crystallinity fraction is... T≥70℃，<90℃ The molecular weight (Mw) can be below 80,000 g / mol, or below 78,000 g / mol, or below 75,000 g / mol, or below 73,000 g / mol, or below 70,000 g / mol, or below 68,000 g / mol, or below 67,000 g / mol, or below 66,000 g / mol, or below 65,000 g / mol, or below 64,500 g / mol, or below 64,000 g / mol, or below 63,500 g / mol, or below 63,000 g / mol. Furthermore, to maintain the excellent mechanical properties of the membrane, the main chain weight-average molecular weight (Mw) of the high crystallinity fraction is... 主，T≥90℃ The weight-average molecular weight (Mw) can be 50,000 g / mol or more, or 52,000 g / mol or more, or 55,000 g / mol or more, or 58,000 g / mol or more, or 60,000 g / mol or more. More preferably, the polyethylene composition has a medium crystallinity fraction with a weight-average molecular weight (Mw). T≥70℃，<90℃ It can be in the range of above 60,000 g / mol and below 63,000 g / mol.

[0038] Furthermore, according to CFC analysis of the polyethylene composition, the amount of low crystallinity fraction (T≥35℃, <70℃) eluted at a temperature above 35℃ and below 70℃ can be 13 wt% or more, or 13.5 wt% or more, or 14 wt% or more, or 14.5 wt% or more, or 15 wt% or more, or 15.2 wt% or more. Meanwhile, the amount of low crystallinity fraction (T≥35℃, <70℃) can also be less than 26.5 wt%, or less than 26.2 wt%, or less than 26 wt%, or less than 25.8 wt% or less, or less than 25.5 wt%. Here, the weight-average molecular weight (Mw) of the low crystallinity fraction (T≥35℃, <70℃) can be 41000 g / mol or more, or 41500 g / mol or more, or 42000 g / mol or more, or 42500 g / mol or more, or 43000 g / mol or more, or 43500 g / mol or more, or 44000 g / mol or more, and can be less than 50000 g / mol, or less than 49800 g / mol, or less than 49500 g / mol, or less than 49200 g / mol, or less than 49000 g / mol. More preferably, the polyethylene composition has a low crystallinity fraction (T≥35℃, <70℃) of 15.2 wt% or more and less than 25.5 wt%, and a weight-average molecular weight (Mw) of 44000 g / mol or more and less than 49000 g / mol.

[0039] Furthermore, according to CFC analysis of the polyethylene composition, the amount of soluble fraction (SF) eluted at a temperature below 35°C as a percentage of the total eluted fraction can be 1.5 wt% or more, or 1.6 wt% or more, or 1.7 wt% or more, or 1.8 wt% or more, or 1.9 wt% or more, or 2 wt% or more. The amount of soluble fraction (SF) can be 4.4 wt% or less, or 4.35 wt% or less, or 4.3 wt% or less, or 4.2 wt% or less. More preferably, the amount of soluble fraction (SF, T<35°C) in the polyethylene composition as a percentage of the total eluted fraction can be 2 wt% or more and 4.2 wt% or less.

[0040] In this disclosure, the contents of the high crystallinity fraction eluted at temperatures above 90°C (T≥90°C), the medium crystallinity fraction eluted at temperatures above 70°C but below 90°C (T≥70°C, <90°C), the low crystallinity fraction eluted at temperatures above 35°C but below 70°C (T≥35°C, <70°C), and the soluble fraction (SF) eluted at temperatures below 35°C all conform to the above-mentioned numerical ranges based on their respective amounts, and the sum of each fraction does not exceed 100%.

[0041] Furthermore, according to CFC analysis of the polyethylene composition, in the high molecular weight region of cross-fractional chromatography, for example, in the weight-average molecular weight (Mw) range of 200,000 g / mol or more and 500,000 g / mol or less, i.e., the Mw range is approximately 10... 5.3 Up to 10 5.7 Within the range of LogMW 5.3 to 5.7, the number of branched molecules (short-chain branches, scb) eluted within this range (the content of 2 to 7 short-chain branches per 1000 carbon atoms, unit: branches / 1000C) can be more than 4 per 1000 carbon atoms (more than 4 per 1000C, more than 4 / 1000C), or more than 4 to less than 14 per 1000 carbon atoms. For example, within the above-mentioned high molecular weight range, the content of short-chain branches (scb) eluted in molecules can be more than 4.1 per 1000C, or more than 4.12 per 1000C, or more than 4.15 per 1000C, or more than 4.18 per 1000C, or more than 4.2 per 1000C. Furthermore, the short-chain branched (scb) content of the molecules eluted in the aforementioned high molecular weight range may be less than 13.5 per 1000C, or less than 12 per 1000C, or less than 10 per 1000C, or less than 9.5 per 1000C, or less than 9 per 1000C, or less than 8.8 per 1000C, or less than 8.5 per 1000C, or less than 8 per 1000C, or less than 7.8 per 1000C, or less than 7.5 per 1000C, or less than 7.2 per 1000C. More preferably, the short-chain branched (scb) content of the molecules eluted in the polyethylene composition in the range of 200,000 g / mol or more to 500,000 g / mol or less may be 4.8 per 1000C and less than 7.2 per 1000C.

[0042] In one embodiment of this disclosure, the density of the polyethylene composition may be 0.925 g / cm³. 3 The value is above 0.950 g / cm³. 3 Preferably, the density is 0.927 g / cm³. 3 Above, 0.929 g / cm 3 Above, 0.931 g / cm 3 Above, 0.934 g / cm 3 Above, 0.935 g / cm 3 Above or 0.936 g / cm 3 The above values ​​are all 0.949 g / cm³. 3 Below, 0.948 g / cm 3 Below, 0.947 g / cm 3Below, 0.946 g / cm 3 Below, 0.945 g / cm 3 Below, 0.943 g / cm 3 Below or 0.940 g / cm 3 More preferably, the density of the polyethylene composition is 0.936 g / cm³. 3 Above and 0.940 g / cm 3 the following.

[0043] In this disclosure, density (g / cm³) 3 The density (g / cm³) was measured using a density gradient tube according to ASTM D 1505 standard. 3 Examples of measurement methods are disclosed in Test Examples 1 and 2.

[0044] In addition, the melt index (MI) of the polyethylene composition 2.16 The melt flow index (measured at 190°C and 2.16 kg load) can range from 0.1 g / 10 min to 2.0 g / 10 min. Preferably, the melt flow index (MI) is... 2.16 The melt flow index (MI) of the polyethylene composition, measured at 190°C and a load of 2.16 kg, is ≥0.2 g / 10 min, ≥0.3 g / 10 min, ≥0.4 g / 10 min, ≥0.45 g / 10 min, ≥0.48 g / 10 min, ≥0.5 g / 10 min, or ≥0.53 g / 10 min, and ≤0.9 g / 10 min, ≤0.8 g / 10 min, ≤0.75 g / 10 min, ≤0.7 g / 10 min, ≤0.68 g / 10 min, ≤0.65 g / 10 min, ≤0.62 g / 10 min, or ≤0.61 g / 10 min. More preferably, the melt flow index (MI) of the polyethylene composition is ≥0.2 g / 10 min, ≥0.3 g / 10 min, ≥0.4 g / 10 min, ≥0.45 g / 10 min, ≥0.48 g / 10 min, ≥0.48 g / 10 min, ≥0.45 g / 10 min, ≥0.53 g / 10 min, and ≤0.62 g / 10 min. 2.16 (Measured at 190℃ and 2.16 kg load) was above 0.53 g / 10 min and below 0.61 g / 10 min.

[0045] In this disclosure, melt index (MI) 2.16 The melt flow index (MI) is measured according to ASTM D 1238 (Condition E, 190°C, 2.16 kg) standard at 190°C and a load of 2.16 kg. For example, Test Examples 1 and 2 disclose a method for measuring the melt flow index (MI). 2.16 The method.

[0046] In addition, the melt flow rate ratio (MFRR, defined as MI) of the polyethylene composition 21.6 / MI 2.16 MI 21.6The MI was measured at 190℃ and under a load of 21.6 kg. 2.16 (Measured at 190°C and 2.16 kg load) can be above 70.0. Preferably, the melt flow rate ratio (MFRR, MI) is... 21.6 / MI 2.16 The melt flow rate ratio (MFRR, MI) of the polyethylene composition is 72 or higher, or 74 or higher, or 75 or higher, or 78 or higher, or 79 or higher, or 80 or higher, or 80.9 or higher, while simultaneously being 110 or lower, or 105 or lower, or 100 or lower, or 98 or lower, or 95 or lower, or 92 or lower, or 90 or lower, or 98 or lower, or 88.7 or lower. More preferably, the melt flow rate ratio (MFRR, MI) of the polyethylene composition is... 21.6 / MI 2.16 The value is above 80.9 and below 88.7.

[0047] In addition, the number-average molecular weight (Mn) of the polyethylene composition may be 15,000 g / mol or more, 17,000 g / mol or more, or 19,000 g / mol or more, and is less than 500,000 g / mol, less than 300,000 g / mol, less than 100,000 g / mol, less than 50,000 g / mol or less than 31,000 g / mol; the weight-average molecular weight (Mw) may be 100,000 g / mol or more, or 106,000 g / mol or more, and is less than 1,000,000 g / mol, less than 500,000 g / mol, less than 300,000 g / mol or less than 158,000 g / mol.

[0048] The molecular weight distribution (Mw / Mn) of the polyethylene composition can be from 5.0 or more to 11.5 or less. More preferably, the molecular weight distribution (Mw / Mn) of the polyethylene composition can be 11.2 or less, or 11.0 or less, or 10.8 or less, or 10.6 or less, or 10.5 or less, or 10.2 or less, or 10.0 or less, or 9.5 or less, or 9.3 or less, or 9.0 or less, or 8.5 or less, or 8.3 or less, or 8 or less, or 7.8 or less, or 7.5 or less, or 7.3 or less, or 7.0 or less, or 6.8 or less, or 6.7 or less. Furthermore, the molecular weight distribution (Mw / Mn) of the polyethylene composition can be 5.2 or more, or 5.3 or more, or 5.4 or more, or 5.5 or more, or 5.6 or more, or 5.7 or more, or 5.8 or more. Specifically, when the molecular weight distribution (Mw / Mn) of the polyethylene composition is 5.0 or higher, the bimodal molecular structure characteristics are enhanced, the bimodality of the GPC peak increases, and the processing viscosity may decrease. However, if the molecular weight distribution (Mw / Mn) of the polyethylene composition exceeds 11.5, it may adversely affect the physical properties or appearance of the film. More preferably, the molecular weight distribution (Mw / Mn) of the polyethylene composition can be 5.8 or higher to 6.7 or lower.

[0049] In this disclosure, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are conversion values ​​relative to standard polystyrene, determined by gel permeation chromatography (GPC, manufactured by Waters). However, the weight-average molecular weight is not limited to this method and can be determined by other methods known in the art. For example, the methods for determining the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are described in Test Examples 1 and 2 below.

[0050] In addition, the melting point (Tm) of the polyethylene composition can be above 127°C to below 130°C, or above 127.2°C to below 129.8°C, or above 127.3°C to below 129.5°C, or above 127.4°C to below 129°C, or above 127.5°C to below 128°C; the crystallization temperature (Tc) can be above 111°C to below 115°C, or above 111.5°C to below 114.5°C, or above 111.7°C to below 114°C, or above 112°C to below 112.5°C; and the crystallinity (Xc) can be above 55% to below 70%, or above 58% to below 68%, or above 60% to below 67.5%. More preferably, the polyethylene composition has a melting point (Tm) of 127.5°C or higher to 128°C or lower, a crystallization temperature (Tc) of 111.5°C or higher to 112.5°C or lower, and a crystallinity (Xc) of 60% or higher to 67.5%.

[0051] In this disclosure, melting point (Tm), crystallization temperature (Tc), and crystallinity (Xc) can be measured using a differential scanning calorimeter (DSC, such as the DSC Q20 manufactured by TA Instruments). For example, a method for measuring Tm, Tc, and Xc is described in Test Example 2.

[0052] In one embodiment of the present invention, the polyethylene composition comprises the following components: (a) A first ethylene-α-olefin copolymer with a density of 0.930 g / cm³ 3 Up to 0.960 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) measured at 190°C under a 2.16 kg load was 0.2 g / 10 min to 2.0 g / 10 min, and the molecular weight distribution (Mw / Mn) was above 5 to below 8.7. (b) A second ethylene-α-olefin copolymer with a density of 0.870 g / cm³. 3 Up to 0.920 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) measured at 190℃ under a 2.16 kg load was 3.0 g / 10 min to 10.0 g / 10 min, and the molecular weight distribution (Mw / Mn) was above 2.0 to below 4.0. Wherein, (a) the content of the first ethylene-α-olefin copolymer is 60 wt% to 90 wt%, and (b) the content of the second ethylene-α-olefin copolymer is 10 wt% to 40 wt%.

[0053] Preferably, (a) the content of the first ethylene-α-olefin copolymer is 65 wt% or more, 67 wt% or more, or 70 wt% or more, and 85 wt% or less, 83 wt% or less, or 80 wt% or less.

[0054] In addition, (b) the content of the second ethylene-α-olefin copolymer is preferably 15 wt% or more, 17 wt% or more or 20 wt% or more, and 35 wt% or less, 33 wt% or less or 30 wt% or less.

[0055] More preferably, in the polyethylene composition, (a) the first ethylene-α-olefin copolymer may be an ethylene / 1-hexene copolymer, and (b) the second ethylene-α-olefin copolymer may be an ethylene / 1-octene copolymer.

[0056] (a) First ethylene-α-olefin copolymer In the polyethylene composition according to embodiments of the present disclosure, (a) the first ethylene-α-olefin copolymer has excellent mechanical properties and a suitable balance between crystallinity and processing properties, thereby endowing it with characteristics suitable for producing biaxially stretched films with excellent tensile properties and high mechanical properties.

[0057] Specifically, (a) the density of the first ethylene-α-olefin copolymer is 0.930 g / cm³. 3 Up to 0.960 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) was 0.2 g / 10 min to 2.0 g / 10 min at 190 °C and 2.16 kg load, and the molecular weight distribution (Mw / Mn) was 5 or higher to 8.7 or lower.

[0058] Preferably, (a) the density of the first ethylene-α-olefin copolymer is at least 0.933 g / cm³. 3 or at least 0.935 g / cm³ 3 or at least 0.938 g / cm³ 3 or at least 0.941 g / cm³ 3 At most, it is 0.955 g / cm³. 3 or at most 0.950 g / cm³ 3 or at most 0.948 g / cm³ 3 .

[0059] (a) Melt index (MI) of the first ethylene-α-olefin copolymer 2.16 (At 190°C and 2.16 kg load) can be greater than 0.2 g / 10 min and less than 1.5 g / 10 min, or at most 1.0 g / 10 min, or at most 0.6 g / 10 min.

[0060] (a) The molecular weight distribution (Mw / Mn) of the first ethylene-α-olefin copolymer is above 5 to below 8.7.

[0061] In addition, (a) the number average molecular weight (Mn) of the first ethylene-α-olefin copolymer may be from more than 12,000 g / mol to less than 50,000 g / mol, and the weight average molecular weight (Mw) may be from more than 100,000 g / mol to less than 250,000 g / mol.

[0062] Preferably, (a) the number average molecular weight (Mn) of the first ethylene-α-olefin copolymer is at least 13,000 g / mol, or at least 13,500 g / mol, or at least 14,000 g / mol, or at least 14,500 g / mol, or 15,000 g / mol, and at most 40,000 g / mol, or at most 35,000 g / mol, or at most 30,000 g / mol, or at most 28,000 g / mol, or at most 25,000 g / mol, or at most 23,000 g / mol, or at most 20,000 g / mol, or at most 18,000 g / mol, or at most 17,000 g / mol, or at most 168,000 g / mol.

[0063] (a) The weight-average molecular weight (Mw) of the first ethylene-α-olefin copolymer may be at least 105,000 g / mol, or at least 110,000 g / mol, or at least 114,000 g / mol, or at least 118,000 g / mol, or at least 120,000 g / mol, or at least 123,000 g / mol, or at least 125,000 g / mol, or at least 128,000 g / mol, or at least 130,000 g / mol, or at least 132,000 g / mol, or at least 135,000 g / mol, while being less than 230,000 g / mol, or less than 210,000 g / mol, or less than 200,000 g / mol, or less than 185,000 g / mol, or less than 180,000 g / mol, or less than 175,000 g / mol, or less than 168,000 g / mol. Below g / mol, or below 165000 g / mol, or below 160000 g / mol, or below 158000 g / mol, or below 155000 g / mol, or below 153000 g / mol, or below 150000 g / mol, or below 148000 g / mol, or below 145000 g / mol, or below 143000 g / mol or below 140000 g / mol.

[0064] (a) The molecular weight distribution (Mw / Mn) of the first ethylene-α-olefin copolymer may be 5 or more to 8.7 or less. More preferably, (a) the molecular weight distribution (Mw / Mn) of the first ethylene-α-olefin copolymer may be 5.2 or more, 5.5 or more, 5.8 or more, 6.0 or more, 6.5 or more, 6.8 or more, 7.0 or more, 7.2 or more, 7.5 or more, 7.8 or more, 8.0 or more, 8.2 or more, or 8.4 or more, and may simultaneously be 8.69 or less, 8.68 or less, 8.65 or less, or 8.63 or less.

[0065] Specifically, (a) the first ethylene-α-olefin copolymer may have at least one of the above physical properties, and may have all of the above physical properties to exhibit excellent mechanical strength.

[0066] In this disclosure, (a) the first ethylene-α-olefin copolymer may comprise ethylene and at least one α-olefin selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof.

[0067] Preferably, (a) the first ethylene-α-olefin copolymer can be an ethylene / 1-hexene copolymer.

[0068] When (a) the first ethylene-α-olefin copolymer is the copolymer described above, the above physical properties can be obtained more easily. However, (a) the type of the first ethylene-α-olefin copolymer is not limited to this, and various types known in the art can be used as long as they can exhibit the above physical properties.

[0069] Meanwhile, (a) the first ethylene-α-olefin copolymer can be prepared in the presence of a metallocene catalyst.

[0070] Specifically, (a) the first ethylene-α-olefin copolymer can be prepared by copolymerizing ethylene with a comonomer in the presence of a catalyst composition while simultaneously introducing hydrogen gas, wherein the catalyst composition comprises a first metallocene compound represented by chemical formula 1 and a second metallocene compound represented by chemical formula 2 in a molar ratio of 1:1 to 1:8: [Chemical Formula 1] (Cp 1 R a ) m (Cp 2 R b M 2 Z 2 3-m In chemical formula 1, M 2 It is a Group 4 transition metal; Cp 1 and Cp 2 Each is independent and not replaced or by C 1-20 Hydrocarbon-substituted cyclopentadienyl group; R a and R b They may be the same as or different from each other, and each is independently hydrogen or carbon. 1-20 Alkyl, C 1-20 Alkoxy, C2-20 Alkoxyalkyl, C 6-20 Aryl, C 6-20 aryloxy group, C 2-20 alkenyl, C 7-40 alkylaryl, C 7-40 Aryl alkyl, C 8-40 Arylene, C 2-20 Alkyne group, or a substituted or unsubstituted C group containing at least one heteroatom selected from N, O, and S. 2-20 Heteroaryl, but only if R a and R b At least one of them is not hydrogen; Each Z 2 The functional group is independently a halogen, C 1-20 Alkyl, C 2-20 alkenyl, C 7-40 alkylaryl, C 7-40 Aryl alkyl, C 6-20 aryl, substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted amino groups, C 2-20 Alkyl alkoxy or C 7-40 arylalkoxy; and m is 1 or 0; [Chemical Formula 2]

[0071] In chemical formula 2, M 3 It is a group 4 transition metal. T 2 It is made of carbon, silicon, or germanium. X 3 and X 4 They may be the same as or different from each other, and each is independently a halogen or C. 1-20 alkyl, R 11 To R 14 They may be the same as or different from each other, and each is independently hydrogen or carbon. 1-20 Alkyl, C 2-20 alkenyl, C 6-20 Aryl, C 7-20 alkylaryl, C 7-20 Aryl group, or R 11 To R 14 Two or more adjacent groups are connected to each other to form a substituted or unsubstituted aliphatic ring, a substituted or unsubstituted aromatic ring, or a substituted or unsubstituted heteroaromatic ring containing at least one selected from N, O, and S. Q 3 and Q 4 They are either the same as or different from each other, and each is independently C. 1-20 Alkyl, C2-20 alkenyl, C 6-30 Aryl, or C 2-20 Alkoxyalkyl, and R 15 C 1-20 Alkyl, C 2-20 alkenyl or C 6-30 Aryl.

[0072] Unless otherwise specified herein, the following terms are defined as follows.

[0073] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0074] C 1-20 Alkyl groups can be straight-chain, branched, or cyclic. Specifically, C 1-20 Alkyl groups can be C 1-15 Straight-chain alkyl; C 1-10 Straight-chain alkyl; C 1-5 Straight-chain alkyl; C 3-20 Branched or cyclic alkyl groups; C 3-15 Branched or cyclic alkyl groups; or C 3-10 Branched or cyclic alkyl groups. More specifically, C 1-20 Alkyl groups can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, cyclohexyl, etc.

[0075] C 2-20 The alkenyl group can be straight-chain, branched, or cyclic. Specifically, C 2-20 The alkenyl group can be C 2-20 Straight-chain alkenyl, C 2-10 Straight-chain alkenyl, C 2-5 Straight-chain alkenyl, C 3-20 Branched alkenyl, C 3-15 Branched alkenyl, C 3-10 Branched alkenyl, C 5-20 Cyclic alkenyl or C 5-10 Cyclic alkenyl groups. More specifically, C 2-20 The alkenyl group can be vinyl, propenyl, butenyl, pentenyl, cyclohexenyl, etc.

[0076] C 6-20 The aryl group can be a monocyclic, bicyclic, or tricyclic aromatic hydrocarbon, including monocyclic aryl or fused aryl groups. Specifically, C 6-20 The aryl group can be phenyl, biphenyl, naphthyl, anthracene, phenanthryl, fluorene, etc.

[0077] C 7-40 Alkyl aryl groups can be substituents in which at least one hydrogen atom of an aryl group is replaced by an alkyl group. Specifically, C 7-40Alkyl aryl groups can be methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, tert-butylphenyl, cyclohexylphenyl, etc.

[0078] C 7-40 Aryl alkyl groups may include substituents in which at least one hydrogen atom of the alkyl group is replaced by an aryl group. Specifically, C 7-40 Aryl groups can be benzyl, phenylpropyl, phenylhexyl, etc.

[0079] C 6-20 The aryloxy group can be phenoxy, biphenoxy, naphthoxy, etc., but this disclosure is not limited to these.

[0080] C 1-20 The alkoxy group can be methoxy, ethoxy, phenoxy, cyclohexyloxy, etc., but this disclosure is not limited to these.

[0081] C 2-20 An alkoxyalkyl group is a functional group in which at least one hydrogen atom on the alkyl group is replaced by an alkoxy group. Specifically, the alkoxyalkyl group may be methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, tert-butoxyhexyl, etc., but this disclosure is not limited thereto.

[0082] C 1-20 Alkylsilyl or C 1-20 An alkoxysilyl group is a functional group in which one to three hydrogen atoms of -SiH3 are replaced by one to three of the aforementioned alkyl or alkoxy groups. Specifically, it can be an alkylsilyl group, such as methylsilyl, dimethylsilyl, trimethylsilyl, dimethylethylsilyl, diethylmethylsilyl, or dimethylpropylsilyl; an alkoxysilyl group, such as methoxysilyl, dimethoxysilyl, trimethoxysilyl, or dimethoxyethoxysilyl; or an alkoxyalkylsilyl group, such as methoxydimethylsilyl, diethoxymethylsilyl, or dimethoxypropylsilyl, but this disclosure is not limited thereto.

[0083] C 1-20 A silyl alkyl group is a functional group in which at least one hydrogen atom on the alkyl group is replaced by a silicon group. Specifically, it can be -CH2-SiH3, methylsilylmethyl, or dimethylethoxysilylpropyl, etc., but this disclosure is not limited thereto.

[0084] The sulfonic acid group has a structure of -O-SO2-R', where R' can be C 1-20 Alkyl groups. Specifically, C 1-20 The sulfonic acid group can be a methanesulfonic acid group, a phenylsulfonic acid group, etc., but this disclosure is not limited thereto.

[0085] Heteroaryl groups are C groups containing at least one of N, O, and S as heteroelements. 2-20Heteroaryl groups include monocyclic or fused heteroaryl groups. Specifically, they can be xanthyl, thioanthyl, thiophene, furanyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, oxadiazolyl, triazolyl, pyridyl, bipyridyl, pyrimidinyl, triazinyl, acridinel, pyridazinyl, pyrazinyl, quinolinyl, quinazolinyl, quinoxolinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, isoquinolinyl, indolyl, carbazole, benzoxazolyl, benzoimidazolyl, benzothiazolyl, benzocarbazole, benzothiaphene, dibenzothiaphene, benzofuranyl, phenanthrolinel, isoxazolyl, thiadiazolyl, phenothiazinyl, dibenzofuranyl, etc., but this disclosure is not limited thereto.

[0086] Furthermore, the Group 4 transition metal can be titanium (Ti), zirconium (Zr), hafnium (Hf), or ruthenium (Rf), more specifically titanium (Ti), zirconium (Zr), or hafnium (Hf). More specifically, it can be zirconium (Zr) or hafnium (Hf), but it is not limited to these.

[0087] Furthermore, Group 13 elements can be boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl), specifically boron (B) or aluminum (Al). However, they are not limited to these.

[0088] Within the range of effects that are the same as or similar to the desired effect, the above substituents may optionally be replaced by one or more of the following substituents: hydroxyl; halogen; alkyl or alkenyl, aryl, alkoxy; alkyl or alkenyl, aryl, alkoxy containing at least one heteroatom from Group 14 to Group 16; silyl; alkylsilyl or alkoxysilyl; phosphin; phosphide; sulfonate; and sulfone.

[0089] Furthermore, "two adjacent substituents connecting to form an aliphatic or aromatic ring" refers to the interconnection of the atoms of the two substituents and the atoms attached to these two substituents to form a ring structure. Specifically, -NR9R 10 R9 and R 10 Examples of compounds that interconnect to form aliphatic rings include piperidinyl groups, and -NR9R 10 R9 and R 10 Examples of compounds that connect to form aromatic rings include pyrrole groups.

[0090] In the catalyst composition, the first metallocene compound represented by Formula 1 is a non-crosslinked compound containing Cp 1 and Cp 2 Ligands are beneficial for the preparation of low molecular weight copolymers with low SCB (short-chain branched) content.

[0091] Specifically, in chemical formula 1, Cp 1 and Cp 2The ligands can be the same or different from each other, and each ligand can be cyclopentadienyl and be surrounded by one or more, or one to three C ions. 1-10 Alkyl substitution. Due to Cp 1 and Cp 2 The ligands possess a pair of non-covalent electrons capable of functioning as Lewis bases, thus enabling high polymerization activity. In particular, due to Cp... 1 and Cp 2 The ligands are cyclopentadienyl groups with relatively low steric hindrance, which exhibit high polymerization activity and low hydrogen reactivity, thus enabling highly active polymerization of low molecular weight polyethylene.

[0092] In addition, Cp 1 and Cp 2 The ligands can be used to easily control the chemical structure, molecular weight, molecular weight distribution, mechanical properties, and transparency of the prepared polyethylene by adjusting the degree of steric hindrance effect according to the type of substituted functional groups. Specifically, Cp 1 and Cp 2 The ligands were respectively R a and R b Replace, where R a and R b They may be the same as or different from each other, and can each be hydrogen or C independently. 1-20 Alkyl, C 2-20 Alkoxyalkyl, C 7-40 Aryl alkyl group or substituted or unsubstituted C containing at least one heteroatom selected from N, O and S. 2-12 heteroaryl, more specifically, C 1-10 Alkyl, C 2-10 Alkoxyalkyl, C 7-20 Aryl alkyl group or substituted or unsubstituted C containing at least one heteroatom selected from N, O and S. 4-12 Mixed aromatic compounds.

[0093] In addition, M 2 Z 2 3-m Existing in Cp 1 and Cp 2 Between the ligands, and M 2 Z 2 3-m This can affect the storage stability of metal complexes. To effectively ensure this effect, Z 1 They can each be halogen or C independently. 1-20 Alkyl groups, more specifically, can be F, Cl, Br, or I. Additionally, M 2 They can be independently Ti, Zr, or Hf; Zr or Hf; or Zr.

[0094] The first metallocene compound can be a compound such as Cp 1 and Cp 2 All are unsubstituted or substituted cyclopentadienyl groups, R a and R b Each independently is hydrogen, C 1-10 Alkyl, C 2-10 Alkoxyalkyl or C 7-20 Aryl alkyl group, wherein R a and R b At least one of them is an alkoxyalkyl group, such as tert-butoxyhexyl, and more specifically, -(CH2). p -OR c Substituents (where R) c It is a straight-chain or branched alkyl group having 1 to 6 carbon atoms (p is an integer from 2 to 4). Furthermore, in the preparation of polyethylene using comonomers, the comonomer conversion is lower in this case compared to other Cp-based catalysts without the above-mentioned substituents; therefore, low molecular weight polyethylene with controllable degree of copolymerization or comonomer distribution can be prepared. Additionally, when a first metallocene compound having the above structure is supported on a support, the -(CH2) substituent... p -OR c The functional groups can form covalent bonds through close interaction with the silanol groups on the silica surface used as a support. Therefore, stable supported polymerization can be achieved.

[0095] The first metallocene compound represented by chemical formula 1 can be a compound with one of the following structural formulas, but is not limited to: .

[0096] The first metallocene compound represented by chemical formula 1 can be synthesized by known reactions; more detailed synthesis methods can be found in the examples.

[0097] Meanwhile, in one embodiment of this disclosure, the second metallocene compound represented by Formula 2 comprises an aromatic ring compound containing a cyclopentadienyl group or a derivative thereof and a nitrogen atom, wherein the aromatic ring compound and the nitrogen atom are connected by a bridging group T. 2 Q 3 Q 4 Crosslinking. Second metallocene compounds with this specific structure exhibit high activity and high copolymerization when applied to the polymerization reaction of ethylene / 1-hexene copolymers, and can yield high molecular weight olefin copolymers.

[0098] In particular, the second metallocene compound represented by Formula 2 possesses a known confined geometry catalyst (CGC) structure, resulting in excellent comonomer incorporation. Furthermore, the distribution of the comonomer is controlled by the electronic and spatial properties of the ligands. These properties control the average ethylene sequence length (ASL), thereby increasing the mid-to-high molecular weight region in the molecular weight distribution and enhancing polymer chain entanglement. Therefore, it is easy to prepare ethylene-α-olefin copolymers that exhibit high resistance to membrane tearing and puncture during membrane processing, while also demonstrating excellent stretchability and processability.

[0099] M in the metallocene compound represented by chemical formula 2 3 It can be a Group 4 transition metal, preferably titanium (Ti), zirconium (Zr) or hafnium (Hf).

[0100] Preferably, T in chemical formula 2 2 It could be silicon.

[0101] Preferably, X in chemical formula 2 3 and X 4 They can be methyl or chlorine (Cl) independently.

[0102] Preferably, R in chemical formula 2 11 To R 14 They may be the same as or different from each other, and each can be methyl or phenyl independently.

[0103] Preferably, R in chemical formula 2 11 To R 14 Two or more adjacent groups are connected to each other to form a substituted or unsubstituted aliphatic ring, a substituted or unsubstituted aromatic ring, or a heteroaromatic ring containing at least one substituent selected from N, O, and S. For example, in chemical formula 2, when R 11 To R 14 When two or more adjacent groups are linked together to form an aliphatic ring, aromatic ring, or heteroaromatic ring, an indenyl, fluorenyl, benzothiopheneyl, or dibenzothiopheneyl group can be formed in which cyclopentadiene is fused. Furthermore, the indenyl, fluorenyl, benzothiopheneyl, and dibenzothiopheneyl groups can be substituted by one or more substituents.

[0104] Preferably, R in chemical formula 2 15 To R 16 They can be the same as or different from each other, and each can be methyl, ethyl, phenyl, propyl, hexyl or tert-butoxyhexyl independently.

[0105] Preferably, R in chemical formula 2 17 It can be methyl, ethyl, n-propyl, isopropyl, n-butyl, or tert-butyl.

[0106] As a second metallocene compound capable of providing ethylene-α-olefin copolymers with excellent tensile stability and superior mechanical properties during biaxial stretching due to the increase in the medium-to-high molecular weight region, the metallocene compound of Formula 2 can be any of the following compounds, but this disclosure is not limited thereto: .

[0107] The second metallocene compound represented by Formula 2 can be synthesized via known reactions. Specifically, it can be prepared by connecting a nitrogen compound and a cyclopentadiene derivative with a bridging compound to form a ligand compound, followed by a metal precursor compound to undergo a metallization reaction. However, this method is not limited to this; more detailed synthetic methods can be understood by referring to the examples.

[0108] The second metallocene compound of formula 2 exhibits excellent polymerization activity, enabling the polymerization of high molecular weight ethylene-α-olefin copolymers. In particular, this compound maintains high polymerization activity even when supported on a support, thus enabling the preparation of ultra-high molecular weight ethylene-α-olefin copolymers.

[0109] Furthermore, even when using hydrogen for polymerization to prepare ethylene-α-olefin copolymers with high molecular weight and wide molecular weight distribution, the second metallocene compound according to Formula 2 of this disclosure exhibits low hydrogen reactivity, thus enabling highly active copolymerization of ethylene-α-olefin copolymers with ultra-high molecular weight. Therefore, even when used in combination with catalysts of other properties, ethylene-α-olefin copolymers satisfying high molecular weight characteristics can be prepared without reducing activity, thereby facilitating the easy preparation of ethylene-α-olefin copolymers containing high molecular weight polyethylene resin and having a wide molecular weight distribution.

[0110] As described above, in the catalyst composition, the first metallocene compound represented by Formula 1 primarily contributes to the formation of a low molecular weight copolymer with a low SCB content, while the second metallocene compound represented by Formula 2 primarily contributes to the formation of a high molecular weight copolymer with a high SCB content. More specifically, the catalyst composition exhibits a high comonomer incorporation rate in the high molecular weight region of the copolymer through the second metallocene compound, and a low comonomer incorporation rate in the low molecular weight region of the copolymer through the first metallocene compound. Therefore, ethylene-α-olefin copolymers exhibiting excellent heat resistance and excellent mechanical properties due to their bimodal molecular weight distribution can be prepared.

[0111] In particular, controlling the content ratio of the first and second metallocene compounds in the catalyst composition can achieve the aforementioned physical properties and further enhance the improvement effect. Specifically, when the content of the second metallocene compound in the catalyst composition is higher than that of the first metallocene compound, the content of the medium and high molecular weight regions in the molecule increases, thereby enhancing the entanglement of polymer chains and optimizing the ratio of high molecular weight regions to low molecular weight regions.

[0112] Specifically, the molar ratio of the first and second metallocene compounds should be from 1:1 to 1:8. Preferably, the molar ratio of the first and second metallocene compounds can be from 1:1 to 1:7, 1:1 to 1:6, or 1:1 to 1:5.5. When the molar ratio of the first and second metallocene compounds is within the above range, the balance between the mechanical properties and elongation of the prepared ethylene-α-olefin copolymer can be controlled. Therefore, the copolymer maintains mechanical properties, productivity, and tensile stability comparable to or better than conventional copolymers, and can improve shrinkage resistance, printability, and transparency.

[0113] Meanwhile, the first and second metallocene compounds have the above-mentioned structural features, and therefore can be stably loaded onto the support.

[0114] In this case, the first and second metallocene compounds are used in a supported form. When used as a supported catalyst, the prepared polymer exhibits excellent particle shape and packing density, and the catalyst is suitable for conventional slurry polymerization, bulk polymerization, and gas-phase polymerization.

[0115] The support can be silica, alumina, magnesium oxide, silica-alumina, or silica-magnesium oxide, and may typically contain oxides, carbonates, sulfates, or nitrates, such as Na₂O, K₂CO₃, BaSO₄, Mg(NO₃)₂, etc. Among these supports, silica supports release very little catalyst from their surface during polymerization because the transition metal compounds are supported through chemical bonding with reactive functional groups (e.g., siloxane groups) present on the silica support surface. Therefore, when polymers are prepared using slurry polymerization or gas-phase polymerization, scaling that adheres to the reactor walls or between polymers can be minimized.

[0116] Furthermore, the surface of the support can be modified by calcination or drying processes to improve its loading efficiency and minimize leaching and scaling. Through the surface modification steps described above, moisture that inhibits reaction with the loaded component on the support surface can be removed, and the content of reactive functional groups (e.g., hydroxyl and siloxane groups) capable of chemically bonding with the loaded component can be increased.

[0117] Specifically, the calcination or drying process of the support can be carried out within a range from the temperature at which moisture disappears from the support surface to the temperature at which reactive functional groups (especially hydroxyl groups) present on the surface are completely eliminated. Specifically, this temperature can be 150°C to 600°C, or 200°C to 500°C. When the temperature is low (below 150°C), the moisture removal efficiency is low, causing residual moisture on the support to potentially react with the co-catalyst, thereby reducing the loading efficiency of the support. When the temperature is too high (above 600°C), the pores on the support surface may coalesce, resulting in a decrease in specific surface area, and many reactive functional groups (e.g., hydroxyl or silanol groups) may be lost from the surface, leaving only siloxane groups. Therefore, the number of active sites reacting with the co-catalyst may decrease, which is undesirable.

[0118] When the first and second metallocene compounds are supported on a support, and the support is silica, the total loading of the first and second metallocene compounds based on 1 g of silica can be 40 μmol or more, or 80 μmol or more, and less than 240 μmol or less, or less than 160 μmol. When loaded within the above ranges, appropriate loading activity can be exhibited, which is advantageous in terms of maintaining catalyst activity and economic feasibility.

[0119] In addition, to improve high activity and process stability, the catalyst composition may also contain a co-catalyst.

[0120] In the hybrid supported metallocene catalysts disclosed herein, the type and amount of additional co-catalysts included are the same as those described above for (a) the first ethylene-α-olefin copolymer, with specific details omitted.

[0121] For example, in the compounds described above, the cocatalyst can more specifically be an alkylaluminoxane-based cocatalyst, such as methylaluminoxane.

[0122] Furthermore, the alkylaluminoxane-based cocatalyst stabilizes the metallocene compound and functions as a Lewis acid, thereby further enhancing the catalytic activity by including a metal element that can form bonds with functional groups introduced into the bridging group of the second metallocene compound through Lewis acid-base interactions.

[0123] Furthermore, the amount of co-catalyst used can be appropriately adjusted according to the desired catalyst and the performance or effect of the resin composition. For example, when silica is used as a support, the loading of the co-catalyst can be based on the weight of the support (e.g., 1 g of silica) and be 8 mmol or more or 10 mmol or less, and 25 mmol or less or 20 mmol or less.

[0124] Furthermore, the catalyst composition described above can be used as is in the polymerization reaction, or it can be contacted with ethylene monomer before the polymerization reaction for use in a prepolymerized state. In this case, the preparation method according to the embodiments of this disclosure may further include a prepolymerization step of contacting the catalyst composition with ethylene monomer before preparing polyethylene by polymerization reaction.

[0125] Alternatively, the catalyst composition can be dissolved or diluted in an aliphatic hydrocarbon solvent (e.g., pentane, hexane, heptane, nonane, decane and their isomers), an aromatic hydrocarbon solvent (e.g., toluene and benzene), or a chlorinated hydrocarbon solvent (e.g., dichloromethane and chlorobenzene) containing 5 to 12 carbon atoms before injection. Preferably, the solvent used herein is used after treatment with a small amount of alkylaluminum to remove trace amounts of water or air, which act as catalyst poisons. A co-catalyst may also be used further.

[0126] Simultaneously, the polymerization process can be carried out by contacting ethylene and comonomers in the presence of the aforementioned catalyst composition. Specifically, the polymerization reaction can be carried out in a bimodal reactor (using two or more reactors) or a single polymerization reactor.

[0127] The polymerization reaction can be carried out at temperatures ranging from 25°C to 500°C, preferably from 25°C to 200°C, and more preferably from 50°C to 150°C. Furthermore, the polymerization reaction can be carried out at 1 kgf / cm³. 2 Up to 100 kgf / cm 2 Preferably 1 kgf / cm 2 Up to 50 kgf / cm 2 More preferably 5 kgf / cm 2 Up to 30 kgf / cm 2 It was carried out under pressure.

[0128] Furthermore, during the copolymerization process, the amount of α-olefin monomer added as a comonomer can be from about 3.0 wt% to about 6.0 wt% of the total ethylene input. More specifically, the amount of α-olefin monomer added can be about 3.1 wt% or more, about 3.2 wt% or more, about 3.3 wt% or more, about 3.4 wt% or more, about 3.5 wt% or more, about 3.55 wt% or more, about 3.6 wt% or more, about 3.65 wt% or more, or about 3.7 wt% or more, and about 5.9 wt% or less, about 5.8 wt% or less, about 5.6 wt% or less, about 5.4 wt% or less, about 5.2 wt% or less, about 5.0 wt% or less, about 4.8 wt% or less, about 4.5 wt% or less, about 4.2 wt% or less, or about 4 wt% or less.

[0129] Specifically, when 1-hexene is used as a comonomer in the copolymerization process, the amount of 1-hexene added as a comonomer may be more than about 3.65 wt%, more than about 3.7 wt%, more than about 3.75 wt%, and less than about 5.2 wt%, or less than about 5.0 wt%, or less than about 4.8 wt%, or less than 4.5 wt%, or less than about 4.2 wt%, or less than 4 wt% of the total amount of ethylene added.

[0130] For example, the copolymerization process can be carried out with an ethylene feed rate of 10.0 kg / hr and a comonomer 1-hexene feed rate of 6.2 mL / min to 6.8 mL / min or greater than 6.2 mL / min to 6.5 mL / min.

[0131] In this disclosure, the first ethylene-α-olefin copolymer can be prepared by copolymerizing ethylene with a comonomer in the presence of the above-described catalyst composition by introducing hydrogen gas. The amounts of hydrogen gas and α-olefin comonomer can be determined according to the desired properties of the first ethylene-α-olefin copolymer.

[0132] More specifically, based on the total weight of ethylene, the amount of hydrogen introduced can be from about 5 ppm to about 120 ppm. More specifically, based on the total weight of ethylene, the amount of hydrogen introduced can be from about 5.5 ppm or more, or about 7 ppm or more, or about 8.5 ppm or more, or about 10 ppm or more, or about 12 ppm or more, or about 15 ppm or more, or about 16 ppm or more, or about 17.5 ppm or more, or about 17.8 ppm or more, or about 18 ppm or more, and from about 100 ppm or less, or about 80 ppm or less, or about 65 ppm or less, or about 50 ppm or less, or about 40 ppm or less, or about 35 ppm or less, or about 30 ppm or less, or about 25 ppm or less, or about 20 ppm or less, or about 19 ppm or less, or about 18.5 ppm or less, or about 18.3 ppm or less.

[0133] For example, in the copolymerization process, the ethylene feed rate can be 10.0 kg / hr, while the hydrogen feed rate can be from more than about 1.75 g / hr to less than about 1.85 g / hr, or from more than about 1.75 g / hr to less than about 1.85 g / hr.

[0134] For example, based on the mass of ethylene, the amount of hydrogen introduced can be 35 ppm to 250 ppm, 40 ppm to 200 ppm, 50 ppm to 190 ppm, 55 ppm to 180 ppm, 58 ppm to 170 ppm, or 60 ppm to 145 ppm.

[0135] In the step of loading the catalyst precursor onto the cocatalyst support, the supported catalyst can be prepared by adding first and second transition metal compounds to the support for the cocatalyst, stirring, and then adding the cocatalyst.

[0136] In the hybrid supported metallocene catalyst according to this embodiment, the amounts of the support, co-catalyst, support for the supported co-catalyst, and transition metal compound can be appropriately adjusted according to the performance or effect required by the supported catalyst.

[0137] Meanwhile, when the molar ratio of the first transition metal compound to the second transition metal compound (first transition metal compound: second transition metal compound) is less than 1:0.3, it is difficult to prepare ultra-low density polyethylene due to the reduced amount of comonomer incorporation. When this ratio exceeds 1:5.5, it is difficult to reproduce the molecular structure of the desired polymer.

[0138] At this point, the loading of the metallocene compound supported on the silica support can be from 0.01 mmol / g to 1 mmol / g per gram of support. That is, considering the effect of the metallocene compound on the catalyst, it is preferable to control this amount within the above range.

[0139] When preparing hybrid supported catalysts, the reaction solvent can be a hydrocarbon solvent, such as pentane, hexane and heptane; or an aromatic solvent, such as benzene and toluene.

[0140] For detailed information on the preparation method of the supported catalyst, please refer to the examples described below. However, the preparation method of the supported catalyst is not limited to this description. The preparation method may also include steps commonly performed in the art, and the steps in the preparation method may be modified by generally variable steps.

[0141] Meanwhile, the aforementioned polyethylene copolymer can be prepared by a method including the step of copolymerizing polyethylene with α-olefins in the presence of the aforementioned hybrid supported metallocene catalyst.

[0142] The aforementioned hybrid supported catalysts exhibit excellent loading performance, catalytic activity, and high comonomer incorporation rate, enabling the preparation of polyethylene copolymers capable of producing biaxially stretched films with excellent scalable processing area characteristics and mechanical properties.

[0143] (a) The first ethylene-α-olefin copolymer can be prepared by means of slurry polymerization, using ethylene and α-olefin as raw materials, in the presence of the above-mentioned hybrid supported catalyst, using conventional equipment and contact technology.

[0144] (a) The preparation method of the first ethylene-α-olefin copolymer can be carried out by copolymerizing ethylene and α-olefin using a continuous slurry polymerization reactor, a loop slurry reactor, etc., but this disclosure is not limited thereto.

[0145] In other words, when the first metallocene compound and the second metallocene compound are loaded in the above molar ratio in the hybrid supported metallocene catalyst of this disclosure, the processing properties, shrinkage rate and mechanical properties of the polyethylene copolymer can be further improved due to the interaction of the two or more catalysts.

[0146] In the hybrid supported metallocene catalysts disclosed herein, the support for supporting the first and second metallocene compounds, the additional co-catalysts, and the polymerization process are the same as those described above for (a) the first ethylene-α-olefin copolymer, with specific details omitted.

[0147] As described above, the first ethylene-α-olefin copolymer of (a) of this disclosure can be prepared by using the above-described supported metallocene catalyst for copolyethylene and α-olefin.

[0148] The first ethylene-α-olefin copolymer having the above-described physical properties can be prepared by the above-described preparation method.

[0149] (b) Second ethylene-α-olefin copolymer In the polyethylene composition disclosed herein, a second ethylene-α-olefin copolymer (b) exhibiting excellent flowability, tensile stability, and shrinkage resistance is blended with the aforementioned first ethylene-α-olefin copolymer (a) to adjust the balance between mechanical properties and elongation. Therefore, it is possible to impart characteristics suitable for manufacturing biaxially stretched films with high shrinkage resistance, excellent printability and transparency, while maintaining mechanical properties, productivity, and tensile stability comparable to or better than those of conventional polyethylene compositions.

[0150] Specifically, (b) the density of the second ethylene-α-olefin copolymer is 0.870 g / cm³. 3 Up to 0.920 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) was 3.0 g / 10 min to 10.0 g / 10 min at 190℃ and 2.16 kg load, and the molecular weight distribution (Mw / Mn) was above 2.0 to below 4.0.

[0151] Preferably, (b) the density of the second ethylene-α-olefin copolymer is at least 0.880 g / cm³. 3 or at least 0.890 g / cm 3 or at least 0.895 g / cm³ 3And at most 0.915 g / cm 3 Or at most 0.910 g / cm 3 or at most 0.905 g / cm³ 3 .

[0152] (b) Melt index (MI) of the second ethylene-α-olefin copolymer 2.16 (At 190°C and 2.16 kg load) can be at least 4.0 g / 10 min, or at least 5.0 g / 10 min, or at least 5.5 g / 10 min, and at most 9.0 g / 10 min, or at most 8.0 g / 10 min, or at most 7.0 g / 10 min.

[0153] (b) The molecular weight distribution (Mw / Mn) of the second ethylene-α-olefin copolymer is above 2.0 and below 4.0.

[0154] In addition, (b) the number average molecular weight (Mn) of the second ethylene-α-olefin copolymer may be more than 20,000 g / mol to less than 50,000 g / mol, and the weight average molecular weight (Mw) may be more than 50,000 g / mol to less than 100,000 g / mol.

[0155] Preferably, (b) the number average molecular weight (Mn) of the second ethylene-α-olefin copolymer may be at least 23,000 g / mol, at least 25,000 g / mol, or at least 28,000 g / mol, and at most 45,000 g / mol, or at most 40,000 g / mol, or at most 35,000 g / mol.

[0156] (b) The weight-average molecular weight (Mw) of the second ethylene-α-olefin copolymer may be at least 55,000 g / mol, or at least 60,000 g / mol, or at least 65,000 g / mol, and at most 90,000 g / mol, or at most 80,000 g / mol, or at most 70,000 g / mol.

[0157] (b) The molecular weight distribution (Mw / Mn) of the second ethylene-α-olefin copolymer may be 2.1 or more, 2.2 or more, or 2.3 or more, and 3.5 or less, 3.0 or less, or 2.5 or less.

[0158] In particular, (b) the second ethylene-α-olefin copolymer may have at least one of the above physical properties, and may have all of the above physical properties, thereby exhibiting excellent mechanical strength.

[0159] In this disclosure, (b) the second ethylene-α-olefin copolymer may comprise ethylene and at least one α-olefin selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof.

[0160] Preferably, (b) the second ethylene-α-olefin copolymer can be an ethylene / 1-octene copolymer.

[0161] When (b) the second ethylene-α-olefin copolymer is the copolymer described above, the above physical properties can be obtained more easily. However, (b) the type of the second ethylene-α-olefin copolymer is not limited to this; various types known in the art can be used as long as they can exhibit the above physical properties.

[0162] Meanwhile, the second ethylene-α-olefin copolymer (b) having the above-mentioned physical properties can be prepared in the presence of a metallocene catalyst.

[0163] Specifically, (b) the second ethylene-α-olefin copolymer can be prepared by copolymerizing ethylene and comonomers in the presence of a catalyst composition comprising a metallocene compound represented by the following chemical formula 3: [Chemical Formula 3]

[0164] In chemical formula 3, M 1 It is a Group 4 transition metal; X 1 and X 2 They may be the same as or different from each other, and each independently can be halogen, nitro, amide, phosphine, phosphide, C1 to C30 hydrocarbon, C1 to C30 hydrocarbon oxy, C2 to C30 hydrocarbon oxy hydrocarbon, -SiH3, C1 to C30 hydrocarbon (oxy) silyl, C1 to C30 sulfonate or C1 to C30 sulfone. Z represents -O-, -S-, -NR a -or-PR a -; R a It is any one of hydrogen, C1 to C20 hydrocarbon group, C1 to C20 hydrocarbon (oxy) silicon group, or C1 to C20 silicon hydrocarbon group.

[0165] T is or , T 1 It can be C, Si, Ge, Sn, or Pb; Q 1 and Q 2They may be the same as or different from each other, and each independently is hydrogen, C1 to C30 hydrocarbon group, C1 to C30 alkyloxy group, C2 to C30 alkyloxyalkyl group, -SiH3, C1 to C30 hydrocarbon (oxy)silyl group, halogen-substituted C1 to C30 hydrocarbon group, and -NR. b R c Any one of them; R b and R c Each is independently hydrogen and at least one of C1 to C30 hydrocarbon groups, or they are connected to each other to form an aliphatic ring or an aromatic ring; and C 1 It is any one of the ligands represented by the following chemical formulas 3a to 3d. [Chemical Formula 3a]

[0166] [Chemical Formula 3b]

[0167] [Chemical formula 3c]

[0168] [Chemical formula 3d]

[0169] In chemical formulas 3a to 3d Y is O or S, and R 1 To R 6 They may be the same as or different from each other, and each is independently any one of hydrogen, C1 to C30 hydrocarbon group or C1 to C30 hydroxyl group.

[0170] Unless otherwise specified herein, the following terms are defined as follows.

[0171] A hydrocarbon group is a monovalent functional group formed by removing a hydrogen atom from a hydrocarbon. It can include alkyl, alkenyl, alkynyl, aryl, aralkyl, aryl-alkenyl, arylynyl, alkylaryl, alkenylaryl, alkynylaryl, etc. C1 to C30 hydrocarbon groups can be C1 to C20 or C1 to C10. For example, a hydrocarbon group can be a straight-chain, branched, or cyclic alkyl group. More specifically, C1 to C30 hydrocarbon groups can be straight-chain, branched, or cyclic alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, and cyclohexyl; or aryl, such as phenyl, biphenyl, naphthyl, anthraceneyl, phenanthrene, or fluorenyl. Furthermore, it can also be an alkylaryl group, such as methylphenyl, ethylphenyl, methylbiphenyl, and methylnaphthyl, or an alkyl group, such as benzyl, phenethyl, biphenylmethyl, and naphthylmethyl. It can also be alkenyl, such as allyl, vinyl, propenyl, butenyl, and pentenyl.

[0172] An alkyl group is a functional group in which a hydrocarbon group is bonded to an oxygen group. Specifically, C1 to C30 alkyl groups can be C1 to C20 or C1 to C10 alkyl groups. For example, an alkyl group can be a straight-chain, branched, or cyclic alkyl group. More specifically, C1 to C30 alkyl groups can be straight-chain, branched, or cyclic alkoxy groups, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptoxy, and cyclohexoxy; or aryloxy groups, such as phenoxy and naphthoxy.

[0173] A alkyloxyalkyl group is a functional group in which at least one hydrogen atom on a hydrocarbon group is replaced by at least one alkyloxy group. Specifically, the C2 to C30 alkyloxyalkyl group can be a C2 to C20 or a C2 to C15 alkyloxyalkyl group. For example, the alkyloxyalkyl group can be a straight-chain, branched, or cyclic alkyl group. More specifically, the C2 to C30 alkyloxyalkyl group can be an alkoxyalkyl group, such as methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, and tert-butoxyhexyl; or an aryloxyalkyl group, such as phenoxyhexyl.

[0174] A alkyl(oxy)silyl group is a functional group in which one to three hydrogen atoms in -SiH3 are replaced by one to three alkyl or alkyloxy groups. Specifically, C1 to C30 alkyl(oxy)silyl groups can be C1 to C20, C1 to C15, C1 to C10, or C1 to C5 alkyl(oxy)silyl groups. More specifically, C1 to C30 alkyl(oxy)silyl groups can be alkylsilyl groups, such as methylsilyl, dimethylsilyl, trimethylsilyl, dimethylethylsilyl, diethylmethylsilyl, or dimethylpropylsilyl; alkoxysilyl groups, such as methoxysilyl, dimethoxysilyl, trimethoxysilyl, or dimethoxyethoxysilyl; or alkoxyalkylsilyl groups, such as methoxydimethylsilyl, diethoxymethylsilyl, or dimethoxypropylsilyl.

[0175] C1 to C20 silyl hydrocarbon groups are functional groups in which at least one hydrogen atom on a hydrocarbon group is replaced by a silicon group. This silicon group can be -SiH3 or a silyl (oxy)silyl group. Specifically, C1 to C20 silyl hydrocarbon groups can be C1 to C15 or C1 to C10 silyl hydrocarbon groups. More specifically, C1 to C20 silyl hydrocarbon groups can be silyl alkyl groups, such as -CH2-SiH3; alkylsilyl alkyl groups, such as methylsilylmethyl, methylsilylethyl, dimethylsilylmethyl, trimethylsilylmethyl, dimethylethylsilylmethyl, diethylmethylsilylmethyl, or dimethylpropylsilylmethyl; or alkoxysilyl alkyl groups, such as dimethylethoxysilylpropyl.

[0176] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0177] The structure of the sulfonate group is -O-SO2-R d , where R d It can be a C1 to C30 hydrocarbon group. Specifically, the C1 to C30 sulfonate groups can be methanesulfonate groups, benzenesulfonate groups, etc.

[0178] The structure of the sulfone groups from C1 to C30 is -R e' -SO2-R e" , where R e' and R e" They can be the same as or different from each other, and each can be any of the C1 to C30 hydrocarbon groups independently. Specifically, the C1 to C30 sulfone groups can be methylsulfonylmethyl, methylsulfonylpropyl, methylsulfonylbutyl, phenylsulfonylpropyl, etc.

[0179] In this disclosure, "two adjacent substituents linked together to form an aliphatic or aromatic ring" means that the atoms of the two substituents and the atoms attached to these two substituents are linked together to form a ring. Specifically, -NR b R c or -NR b 'R c' R in b and R c Or R b' and R c' Examples of compounds that interconnect to form aliphatic rings include piperidinyl groups; -NR b R c or -NR b 'R c' R in b and R c Or R b' and R c' Examples of compounds that connect to form aromatic rings include pyrrole groups.

[0180] The Group 4 transition metal can be titanium (Ti), zirconium (Zr), hafnium (Hf), or ruthenium (Rf), specifically titanium (Ti), zirconium (Zr), or hafnium (Hf). More specifically, it can be zirconium (Zr) or hafnium (Hf), but this disclosure is not limited thereto.

[0181] Furthermore, the Group 13 element can be boron (B), aluminum (Al), gallium (Ga), indium (In) or thallium (Tl), and can specifically be boron (B) or aluminum (Al), but this disclosure is not limited thereto.

[0182] Within the range that exhibits the same or similar effect as desired, the above substituents may optionally be replaced by one or more substituents selected from the group consisting of: hydroxyl; halogen; hydrocarbon group; hydrocarbon oxy group; hydrocarbon group or hydrocarbon oxy group containing at least one heteroatom of group 14 to 16; silyl group; hydrocarbon oxysilyl group; phosphin group; phosphide group; sulfonate group; and sulfone group.

[0183] In this disclosure, A bond that is attached to another substituent.

[0184] Specifically, in chemical formula 3, Z is -NR a -, where R a It can be a C1 to C10 hydrocarbon group. Specifically, R a It can be a straight-chain or branched alkyl group from C1 to C6. More specifically, it can be tert-butyl.

[0185] In chemical formula 3, T is... T 1 For carbon (C) or silicon (Si), Q 1 and Q 2 Each can be independently hydrogen, a C1 to C30 hydrocarbon group, or a C1 to C30 hydroxyl group. Specifically, Q 1 and Q 2 Each can be a C1 to C10 hydrocarbon group or a C2 to C12 hydroxyl group. More specifically, Q 1 and Q 2 Each can be a C1 to C6 alkyl or a C1 to C6 alkoxy substituted C1 to C6 alkyl group. For example, Q 1 and Q 2 Each hexyl group can be independently substituted with hydrogen, methyl, ethyl, or tert-butoxy. More specifically, T 1 For silicon (Si); Q 1 and Q 2 All are methyl, or Q 1 and Q 2 One of them is a methyl group, and the other is a tert-butoxy-substituted hexyl group.

[0186] Specifically, the metallocene compound represented by chemical formula 3 can be any of the following compounds with chemical formulas 3-1 to 3-4.

[0187] [Chemical Formula 3-1]

[0188] [Chemical Formula 3-2]

[0189] [Chemical Formula 3-3]

[0190] [Chemical Formula 3-4]

[0191] In chemical formulas 3-1 to 3-4, M 1 X 1 X 2 R a T 1 Q 1 Q 2 Y and R 1 To R 6 The definition is the same as that in chemical formula 3.

[0192] In chemical formula 3, R 1 To R 4 It can be hydrogen or a C1 to C10 hydrocarbon group, R 5 and R 6 It can be a C1 to C10 hydrocarbon group. Specifically, R 1 To R 4 It can be hydrogen or a C1 to C10 alkyl group, R 5 and R 6 It can be a C1 to C10 alkyl group. More specifically, R 1 To R 4 Each can be either hydrogen or methyl, R 5 and R 6 It can be methyl.

[0193] In chemical formula 3, M 1 It can be titanium (Ti), zirconium (Zr) or hafnium (Hf), with titanium (Ti) being preferred.

[0194] Furthermore, in chemical formula 3, X 1 and X 2 All can be halogen, C1 to C10 alkyl or C1 to C6 alkyl, and specifically, chlorine or methyl.

[0195] Furthermore, in chemical formula 3, metallocene compounds can be represented by one of the following structural formulas.

[0196]

[0197] The metallocene compounds represented by the above structural formulas can be synthesized by known reactions. For more detailed synthesis methods, please refer to the examples and synthesis examples for understanding.

[0198] As described above, the transition metal compound represented by chemical formula 3 used in this disclosure controls the degree of introduction of α-olefin monomers during copolymerization due to the structural characteristics of the catalyst, and exhibits the aforementioned density, resulting in excellent flowability and tensile processing properties.

[0199] In this disclosure, the polymerization reaction can be carried out by continuously introducing hydrogen gas in the presence of a catalyst composition containing at least one transition metal compound represented by Formula 3, while simultaneously polymerizing ethylene and α-olefin monomers. Specifically, the polymerization reaction can be carried out while hydrogen gas is introduced at a rate of 5 cc / min to 100 cc / min.

[0200] Hydrogen gas inhibits the rapid reaction of transition metal compounds in the early stages of polymerization and acts as a terminating agent. Therefore, by using hydrogen gas and adjusting its dosage, ethylene / α-olefin copolymers with narrow molecular weight distributions can be effectively prepared.

[0201] For example, the hydrogen flow rate can be 5 cc / min or more, 7 cc / min or more, 8.5 cc / min or more, 10 cc / min or more, 12 cc / min or more, or 15 cc / min or more, and 100 cc / min or less, 50 cc / min or less, 45 cc / min or less, 35 cc / min or less, 30 cc / min or less, 29 cc / min or less, 25 cc / min or less, 20 cc / min or less, 18 cc / min or less, or 16 cc / min or less. When hydrogen is introduced under the above conditions, the prepared ethylene / α-olefin copolymer can achieve the physical properties described in this disclosure.

[0202] When the hydrogen flow rate is below 5 cc / min, the polymerization reaction cannot be terminated uniformly, making it difficult to prepare ethylene / α-olefin copolymers with the desired physical properties. When the hydrogen flow rate is above 100 cc / min, the reaction terminates too quickly, resulting in ethylene / α-olefin copolymers with extremely low molecular weights.

[0203] Meanwhile, the second ethylene-α-olefin copolymer of this disclosure can be prepared by copolymerizing ethylene with the comonomer by introducing hydrogen gas in the presence of the above-described catalyst composition. The amounts of hydrogen gas and α-olefin comonomer introduced can be determined according to the desired properties of the second ethylene-α-olefin copolymer.

[0204] In polymerization processes using α-olefins as comonomers, the amount of α-olefin used can be from about 10 wt% to about 48 wt% of the total weight of ethylene. Specifically, the amount of α-olefin used can be at least about 12 wt%, or at least about 15 wt%, or at least about 18 wt%, or at least about 20 wt%, or at least about 22 wt%, or at least about 25 wt%, or at least about 28 wt%, or at least about 30 wt%, or at least about 32 wt%, or at least about 35 wt%. Furthermore, the amount of α-olefin used can be up to about 46 wt%, or up to about 45 wt%, or up to about 43.5 wt%, or up to about 42 wt%, or up to about 40 wt%, or up to about 38.5 wt%, or up to about 38 wt%, or up to about 37.5 wt%, or up to about 37 wt%, or up to about 36.5 wt%, or up to about 36 wt%.

[0205] More specifically, when 1-octene is used as a comonomer in a copolymerization reaction, the amount of 1-octene may be more than 28 wt% of the total weight of ethylene, or more than 30 wt%, or more than 32 wt%, or more than 35 wt%. The amount of 1-octene may also be less than 40 wt%, or less than 38.5 wt%, or less than 38 wt%, or less than 37.5 wt%, or less than 37 wt%, or less than 36.5 wt%, or less than 36 wt%.

[0206] For example, when 1-octene is used as a comonomer and the ethylene feed rate is 0.87 kg / hr, the 1-octene feed rate can be above 0.25 kg / hr and below 0.35 kg / hr, or above 0.28 kg / hr and below 0.32 kg / hr.

[0207] Furthermore, the polymerization reaction can be carried out at temperatures ranging from 100°C to 200°C. By adjusting the polymerization temperature and the amount of hydrogen input, the crystallization distribution and molecular weight distribution of the ethylene / α-olefin copolymer can be more easily controlled. Specifically, the polymerization reaction can be carried out at temperatures ranging from 100°C to 200°C, 120°C to 180°C, 130°C to 170°C, or 140°C to 160°C, but is not limited to these temperatures.

[0208] In this disclosure, a co-catalyst may also be used in the catalyst composition to activate the transition metal compound of formula 3. The co-catalyst is an organometallic compound containing a group 13 metal, and more specifically, may include one or more compounds selected from formulas 4 to 6 below.

[0209] [Chemical Formula 4] R8-[Al(R7)-O] n -R9 In chemical formula 4, R7, R8, and R9 are each independently hydrogen, halogen, and carbon. 1-20 C with hydrocarbon or halogen substitution 1-20 hydrocarbon groups, and n is an integer greater than or equal to 2.

[0210] [Chemical Formula 5] D(R 10 )3 In chemical formula 5, D is aluminum or boron. R 10 Each is independently a halogen, C 1-20 hydrocarbon group, C 1-20 C with alkyl or halogen substitution 1-20 Hydrocarbon group.

[0211] [Chemical Formula 6] [LH] + [W(A)4] - Or [L] + [W(A)4] - In chemical formula 6, L is a neutral or cationic Lewis base. H is a hydrogen atom. W is a group 13 element. A is independently any one of the following: C 1-20 hydrocarbon group; C 1-20 alkyloxy groups; and one or more hydrogen atoms of these substituents are selected from halogens, C 1-20 alkyl groups and C 1-20 One or more substituents of a hydrocarbon (oxy)silyl group are used to replace the substituents.

[0212] Specifically, in chemical formula 6, [LH] + It is a Brønsted acid.

[0213] For example, [LH] + It can be trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, diethylammonium, trimethylphosphonium, or triphenylphosphonium, wherein [L] + It can be N,N-diethylphenylamine or triphenylcarbium.

[0214] Furthermore, in chemical formula 6, W can be B. 3+ Or Al 3+ .

[0215] Compounds represented by chemical formula 4 can be used as alkylating agents and activators, compounds represented by chemical formula 5 can be used as alkylating agents, and compounds represented by chemical formula 6 can be used as activators.

[0216] More specifically, the compound represented by Formula 4 can be an alkylaluminoxane-based compound, wherein the repeating units are linked in a linear, cyclic, or network structure, and specific examples may include methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, or tert-butylaluminoxane, etc. Non-limiting examples of the compound represented by Formula 4 may include methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, tert-butylaluminoxane, etc.

[0217] In addition, non-limiting examples of compounds represented by Formula 5 may include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, trisec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxide aluminum, dimethylethanol aluminum, etc.

[0218] Furthermore, non-limiting examples of compounds represented by Formula 6 may include: trimethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium n-butyltri(pentafluorophenyl)borate, N,N-dimethylphenylammonium benzyltri(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(4-(tert-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl)borate, and N,N-dimethylphenylammonium tetra(4-(triisopropylsilyl)-2,3,5,6-tetrafluorophenyl)borate. N,N-dimethylphenylammonium (Phenyl)boronic acid, N,N-dimethylphenylammonium pentafluorophenoxytris(pentafluorophenyl)boronic acid, N,N-dimethyl-2,4,6-trimethylphenylammonium tetra(pentafluorophenyl)boronic acid, trimethylammonium tetra(2,3,4,6-tetrafluorophenyl)boronic acid, N,N-dimethylphenylammonium tetra(2,3,4,6-tetrafluorophenyl)boronic acid, hexadecyl dimethylammonium tetra(pentafluorophenyl)boronic acid, N-methyl-N-dodecylphenylammonium tetra(pentafluorophenyl)boronic acid, methyl di(dodecyl)ammonium tetra(pentafluorophenyl)boronic acid, etc.

[0219] In the compounds described above, the cocatalyst can more specifically be an alkylaluminoxane-based cocatalyst, such as methylaluminoxane.

[0220] The amount of co-catalyst used can be adjusted appropriately according to the physical properties or function of the required hybrid supported metallocene catalyst.

[0221] The amount of co-catalyst used should be appropriate to ensure sufficient activation of the transition metal compound of formula 3. The amount of co-catalyst used can be adjusted appropriately according to the physical properties or function of the desired hybrid supported metallocene catalyst.

[0222] In this disclosure, the transition metal compound of formula 3 can be used in an unsupported form or in a supported form.

[0223] When a transition metal compound of Formula 3 is supported on a support, the weight ratio of the transition metal compound to the support can be from 1:10 to 1:1000, more specifically, from 1:10 to 1:500. When the support and the transition metal compound are included within the above weight ratio range, an optimized morphology can be exhibited. Furthermore, when a co-catalyst is supported on a support, the weight ratio of the co-catalyst to the support can be from 1:1 to 1:100, more specifically, from 1:1 to 1:50. When the co-catalyst and the support are included within the above weight ratio range, the activity of the catalyst can be improved and the microstructure of the prepared polymer can be optimized.

[0224] Meanwhile, the support can be silica, alumina, magnesium oxide, or a mixture thereof, or it can be used in the form of highly reactive hydroxyl or siloxane groups on the surface after removing surface moisture through high-temperature drying. In addition, the high-temperature dried support usually contains oxides, carbonates, sulfates, and nitrates, such as Na2O, K2CO3, BaSO4, Mg(NO3)2, etc.

[0225] The drying temperature of the support is preferably from about 200°C to 800°C, more preferably from about 300°C to 600°C, and most preferably from about 300°C to 400°C. When the drying temperature of the support is below 200°C, excessive moisture may cause surface moisture to react with the co-catalyst. When the drying temperature is above 800°C, the pores on the support surface will merge, reducing the surface area, and a large number of hydroxyl groups on the surface may be lost, leaving only siloxane groups, thereby reducing the reaction sites with the co-catalyst, which is undesirable.

[0226] The amount of hydroxyl groups on the carrier surface is preferably from 0.1 mmol / g to 10 mmol / g, more preferably from 0.5 mmol / g to 5 mmol / g. The content of hydroxyl groups on the carrier surface can be controlled by the preparation method and conditions of the carrier, or by the drying conditions (e.g., temperature, time, vacuum, spray drying, etc.).

[0227] Furthermore, organoaluminum compounds are added during the polymerization process to remove moisture from the reactor; the polymerization reaction can be carried out in the presence of organoaluminum compounds. Specific examples of such organoaluminum compounds include trialkylaluminum, dialkylaluminum halides, alkylaluminum dihalides, dialkylaluminum hydrides, or alkylsesquihalides. More specific examples include Al(C2H5)3, Al(C2H5)2H, Al(C3H7)3, Al(C3H7)2H, Al(i-C4H9)2H, and Al(C8H5)2H. 17 3. Al(C) 12 H 25 3. Al(C2H5)(C 12 H 25 )2、Al(i-C4H9)(C 12 H 25 2. Al(i-C4H9)2H, Al(i-C4H9)3, (C2H5)2AlCl, (i-C3H9)2AlCl, (C2H5)3Al2Cl3, etc. These organoaluminum compounds can be continuously added to the reactor, and can be added at a rate of approximately 0.1 to 10 moles per 1 kg of reaction medium added to the reactor to ensure thorough removal of moisture.

[0228] In addition, the polymerization pressure can be approximately 1 kgf / cm. 2 Approximately 100 kgf / cm 2 Preferably about 1 kgf / cm 2 Approximately 50 kgf / cm 2 More preferably about 5 kgf / cm 2 Approximately 30 kgf / cm 2 .

[0229] Furthermore, when transition metal compounds are used in a supported form, they can be dissolved or diluted in an aliphatic hydrocarbon solvent (e.g., pentane, hexane, heptane, nonane, decane and their isomers), an aromatic hydrocarbon solvent (e.g., toluene and benzene), or a chlorinated hydrocarbon solvent (e.g., dichloromethane and chlorobenzene) containing 5 to 12 carbon atoms before addition. The solvents used here are preferably treated with a small amount of alkylaluminum to remove trace amounts of water or air, which act as catalyst poisons, before use. A co-catalyst may also be used further.

[0230] As described above, (b) the second ethylene-α-olefin copolymer can be prepared by copolymerizing ethylene and α-olefin using the metallocene catalyst described above.

[0231] Specifically, the method for preparing (b) the second ethylene-α-olefin copolymer can be carried out by solution polymerization using conventional equipment and contact technology, with ethylene and α-olefin as raw materials, in the presence of a catalyst composition containing the aforementioned metallocene compound.

[0232] Furthermore, the catalyst composition can be dissolved or diluted in aliphatic hydrocarbon solvents having 5 to 12 carbon atoms (e.g., pentane, hexane, heptane, nonane, decane, and their isomers); aromatic hydrocarbon solvents (e.g., toluene and benzene); or chlorinated hydrocarbon solvents (e.g., dichloromethane and chlorobenzene); and then used in subsequent polymerization reactions. In this disclosure, the solvent is preferably treated with a small amount of alkylaluminum before use to remove trace amounts of water or air as catalyst poisons. A co-catalyst may also be used further.

[0233] The method for preparing (b) the second ethylene-α-olefin copolymer may include, but is not limited to, the copolymerization of ethylene and α-olefin using a continuous polymerization reactor.

[0234] The above preparation method can be used to prepare (b) second ethylene-α-olefin copolymer with the above physical properties.

[0235] Biaxial stretch film The polyethylene composition disclosed herein possesses the aforementioned physical properties and can be processed into biaxially stretched films that maintain excellent mechanical properties, productivity, and tensile stability, and exhibit high shrinkage resistance, printability, and transparency.

[0236] In addition to using the above-mentioned polyethylene composition, the biaxially stretched film can also be prepared by conventional film manufacturing methods.

[0237] For example, to prepare a biaxially stretched polyethylene film according to this disclosure, a polyethylene composition sheet with a thickness of 0.75 mm can be prepared using a Bruckner laboratory extruder production line (L / D ratio: 42, screw diameter: 25 mm, melt / T-die temperature: 220°C). The polyethylene composition sheet with length and width dimensions of 90 mm x 90 mm can then be biaxially stretched using a KARO 5.0 apparatus to prepare the biaxially stretched polyethylene film. Specific methods and conditions are described in Test Example 3 below.

[0238] In addition to the aforementioned polyethylene copolymer, the biaxially stretched polyethylene film according to this disclosure may also contain additives known in the art. Specifically, these additives may include solvents, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, metal passivators, fillers, reinforcing agents, plasticizers, lubricants, emulsifiers, pigments, optical brighteners, flame retardants, antistatic agents, foaming agents, etc. There are no particular limitations on the type of additives; commonly known additives in the art may be used.

[0239] The polyethylene biaxial stretch film prepared by the above method according to one embodiment of the present disclosure can have improved performance, as well as excellent scalable processing area characteristics and superior mechanical properties.

[0240] According to ASTM 1003 standards, the haze of biaxially oriented polyethylene film can be greater than 0.5%, or greater than 1.0%, or greater than 1.5%, or greater than 1.6%, or greater than 1.86%, or greater than 1.9%, and can be less than 8.5%, or less than 8.2%, or less than 8.0%, or less than 7.8%, or less than 7.7%, or less than 7.5%, or less than 7.0%, or less than 6.8%, or less than 6.5%, or less than 6.3%, or less than 6.0%, or less than 5.8% or less than 5.6%.

[0241] According to ASTM 2457, the gloss (@45°) of a biaxially oriented polyethylene film can be 80 GU or higher, or 80 GU or higher but less than 100 GU. Preferably, the gloss can be at least 85 GU, at least 88 GU, at least 90 GU, or at least 93 GU.

[0242] Specifically, biaxially stretched polyethylene film can be stretched with a longitudinal (MD) stretch ratio of 4 or more, or 5 or more, and a transverse (TD) stretch ratio of 7 or more, or 8 or more.

[0243] According to ASTM D 882, the tensile strength of biaxially oriented polyethylene film in the MD direction can be above 70 MPa, or above 75 MPa, or above 78 MPa, or above 80 MPa, or above 90 MPa, or above 95 MPa, or above 100 MPa, or above 110 MPa, or above 120 MPa, and below 150 MPa, or below 130 MPa. According to ASTM D 882, the tensile strength of biaxially oriented polyethylene film in the TD direction can be above 180 MPa, or above 190 MPa, or above 195 MPa, or above 200 MPa, or above 210 MPa, or above 220 MPa, or above 230 MPa, and below 280 MPa, or below 270 MPa, or below 265 MPa.

[0244] Measured according to ASTM D 882 standard, the average longitudinal (MD) tensile strength and transverse (TD) tensile strength of the biaxially stretched film can be 150 MPa or higher. Preferably, the average longitudinal (MD) tensile strength and transverse (TD) tensile strength of the biaxially stretched film can be 155 MPa or higher, or 160 MPa or higher, or 165 MPa or higher, or 168 MPa or higher, or 170 MPa or higher, and also below 200 MPa, or below 185 MPa, or below 180 MPa, or below 175 MPa.

[0245] Furthermore, according to ASTM D 882, the tensile modulus in the MD direction of biaxially oriented polyethylene film can be 500 MPa or higher. Specifically, the MD tensile modulus can be 520 MPa or higher, or 530 MPa or higher, or 535 MPa or higher, or 550 MPa or higher, or 600 MPa or higher, or 645 MPa or higher, and can also be below 1000 MPa, or below 950 MPa, or below 900 MPa, or below 850 MPa, or below 810 MPa. According to ASTM D 882, the tensile modulus in the TD direction of biaxially oriented polyethylene film can be 600 MPa or higher. The tensile modulus in the TD direction can be above 620 MPa, or above 650 MPa, or above 680 MPa, or above 690 MPa, or above 700 MPa, or above 800 MPa, or above 850 MPa, and can also be below 1500 MPa, or below 1200 MPa, or below 1000 MPa, or below 980 MPa.

[0246] According to ASTM D 882 standard, the average value of the MD tensile modulus and TD tensile modulus of the biaxially stretched film can be above 600 MPa. Preferably, the average value of the MD tensile modulus and TD tensile modulus of the biaxially stretched film can be above 605 MPa, or above 610 MPa, or above 613 MPa, while also being below 1000 MPa, or below 950 MPa, or below 920 MPa, or below 900 MPa, or below 895 MPa.

[0247] According to ASTM D 882, the MD elongation at break of biaxially oriented polyethylene film can be 150% to 250%, or 160% to 230%, or 170% to 180%, and the TD elongation at break can be 30% to 100%, 35% to 80%, or 38% to 60%.

[0248] In addition, according to ASTM 1922 standards, the MD tear strength of biaxially stretched polyethylene film ranges from 6 N / mm to 13.1 N / mm, and the TD tear strength ranges from 1.6 N / mm to 6.7 N / mm.

[0249] According to EN 14477, the puncture strength of biaxially oriented polyethylene film can be 400 N / mm or higher; preferably 420 N / mm, 430 N / mm or higher, 435 N / mm or higher, 440 N / mm or higher, or 445 N / mm or higher, while also being 600 N / mm or lower, 550 N / mm or lower, 500 N / mm or lower, 520 N / mm or lower, or 485 N / mm or lower.

[0250] Furthermore, according to ASTM D 1709 standard, using dart method A, the dart impact strength (front side) of the polyethylene biaxial stretch film is 490 g or more; preferably 495 g or more, 498 g or more, 500 g or more, or 530 g or more, while also being 700 g or less, or 650 g or less, or 620 g or less, or 600 g or less, or 580 g or less, or 550 g or less, or 540 g or less.

[0251] In this disclosure, the physical properties of the biaxially stretched membrane can be measured according to the above-mentioned standards, and the specific steps are described in Test Example 3 below.

[0252] Therefore, as described above, by blending a first ethylene-α-olefin copolymer with excellent mechanical properties with a second ethylene-α-olefin copolymer with excellent flowability and stretchability, the balance between mechanical properties and elongation can be controlled, thereby stably preparing biaxially stretched films with high shrinkage resistance, printability and transparency, while maintaining excellent mechanical properties, productivity and stretch stability.

[0253] [Beneficial Effects] The superior effect of the polyethylene disclosed herein is that it enables the production of biaxially stretched films with high shrinkage resistance, printability, and transparency, while maintaining excellent mechanical properties and tensile stability, with excellent film processability and productivity. Detailed Implementation

[0254] The embodiments of the present invention will be described in more detail below. However, the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0255]

Example

[0256] The preparation of tert-butyl-O-(CH2)6-Cl was carried out using the method in Tetrahedron Lett. 2951 (1988), which involved reacting 6-chlorohexanol with Na(C5H5)[NaCp] to give tert-butyl-O-(CH2)6-C5H5 (60% yield, boiling point 80 °C / 0.1 mmHg).

[0257] Furthermore, tert-butyl-O-(CH2)6-C5H5 was dissolved in tetrahydrofuran (THF) at -78 °C, and n-butyllithium (n-BuLi) was slowly added. The mixture was then heated to room temperature and reacted for 8 hours. At -78 °C, the synthesized lithium salt solution was slowly added to a suspension of ZrCl4(THF)2 (170 g, 4.50 mmol) / THF (30 mL), and reacted further at room temperature for approximately 6 hours. All volatiles were dried under vacuum, and the resulting oily liquid was filtered by adding hexane solvent. After vacuum drying of the filtrate, hexane was added, and a precipitate was obtained at low temperature (-20 °C). The precipitate was filtered at low temperature to give the compound [tert-butyl-O-(CH2)6-C5H4]2ZrCl2 as a white solid (92% yield).

[0258] 1 H-NMR (300 MHz, CDCl3): δ 6.28(t, J=2.6 Hz, 2H), 6.19(t, J=2.6 Hz,2H), 3.31(t, 6.6 Hz, 2H), 2.62(t, J=8 Hz), 1.7 - 1.3(m, 8H), 1.17(s,9H).

[0259] 13 C-NMR (CDCl3): δ 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.31, 30.14, 29.18, 27.58, 26.00.

[0260] Synthesis Example 2

[0261] At room temperature, 50 g of Mg was added to a 10 L reactor, followed by 300 mL of THF. 0.5 g of I₂ was then added, and the reactor temperature was maintained at 50 °C. After the reactor temperature stabilized, 250 g of 6-tert-butoxyhexyl chloride was added to the reactor at a rate of 5 mL / min using a feed pump. It was observed that the reactor temperature increased by 4 to 5 °C with the addition of 6-tert-butoxyhexyl chloride. The mixture was stirred for 12 hours while continuously adding 6-tert-butoxyhexyl chloride. After 12 hours of reaction, a black reaction solution was obtained. 2 mL of the black reaction solution was taken and water was added to obtain the organic layer. The organic layer was analyzed by proton nuclear magnetic resonance (NMR) spectroscopy. 1 ¹H-NMR analysis confirmed that the organic layer was 6-tert-butoxyhexane. This confirmed the successful conduct of the Grignard reaction. Thus, 6-tert-butoxyhexyl magnesium chloride was synthesized.

[0262] 500 g of trichloromethylsilane (MeSiCl3) and 1 L of tetrahydrofuran (THF) were added to the reactor, and the reactor temperature was cooled to -20°C. 560 g of the synthesized 6-tert-butoxyhexyl magnesium chloride was added to the reactor at a rate of 5 mL / min using a feed pump. After the Grignard reagent was added, the mixture was stirred for 12 hours while slowly heating to room temperature. After 12 hours of reaction, a white MgCl2 salt was confirmed to have formed. 4 L of hexane was added, and the salt was removed by passing the solution through a labdori filter to obtain a filtrate. The filtrate was added to the reactor, and the hexane was removed at 70°C to obtain a pale yellow liquid. 1 H-NMR confirmed that the obtained liquid was methyl(6-tert-butoxyhexyl)dichlorosilane.

[0263] 1 H-NMR (300 MHz, CDCl3): δ 3.3(t, 2H), 1.5(m, 3H), 1.3(m, 5H), 1.2(s,9H), 1.1(m, 2H), 0.7(s, 3H).

[0264] 1.2 mol (150 g) of tetramethylcyclopentadiene and 2.4 L of tetrahydrofuran (THF) were added to the reactor, and the reactor temperature was then cooled to -20 °C. 480 mL of n-butyllithium (n-BuLi) was added to the reactor at a rate of 5 mL / min using a feed pump. After the addition of n-BuLi, the mixture was stirred for 12 hours while slowly heating to room temperature. After 12 hours of reaction, 1 equivalent of methyl(6-tert-butoxyhexyl)dichlorosilane (326 g, 350 mL) was rapidly added. The mixture was stirred for 12 hours while slowly heating to room temperature. Then, the reactor temperature was cooled to 0 °C again, and 2 equivalents of tert-butylammonium (t-BuNH2) were added. The mixture was stirred for 12 hours while slowly heating to room temperature. After 12 hours of reaction, THF was removed. Subsequently, 4 L of hexane was added, and the salt was removed by a filter dryer to obtain a filtrate. The filtrate was added back to the reactor, and the hexane was removed at 70 °C to obtain a yellow solution. The solution was analyzed by 1H NMR spectroscopy (1H NMR spectroscopy). 1 ¹H-NMR confirmed that the obtained yellow solution was methyl(6-tert-butoxyhexyl)(tetramethylCpH)tert-butylaminosilane.

[0265] Dilithium salts of the aforementioned ligands were prepared from n-butyllithium and the ligands prepared above in a THF solution at -78°C, and then TiCl3(THF)3 (10 mmol) was rapidly added to the solution. The reaction mixture was stirred for 12 hours while being slowly heated from -78°C to room temperature. After stirring for 12 hours, 1 equivalent of PbCl2 (10 mmol) was added to the reaction mixture at room temperature, and the mixture was stirred for another 12 hours. After stirring for 12 hours, a dark black solution with a blue hue was obtained. THF was removed from the resulting reaction mixture, and hexane was added to filter the product. Hexane was removed from the filtrate, and the product was then filtered... 1 H-NMR confirmed the product to be (tBu-O-(CH2)6)(CH3)Si(C5(CH3)4)(tBu-N)TiCl2, ([methyl(6-tert-butoxyhexyl)silyl(η5-tetramethylCp)(tert-butylamino)]TiCl2).

[0266] 1 H-NMR (300 MHz, CDCl3): δ 3.3(s, 4H), 2.2(s, 6H), 2.1(s, 6H), 1.8 -0.8(m), 1.4(s, 9H), 1.2(s, 9H), 0.7(s, 3H).

[0267] Synthesis Example 3 (1) Preparation of ligand A A 1-benzothiophene solution was prepared by dissolving 4.0 g (30 mmol) of 1-benzothiophene in THF. Then, 14 mL (36 mmol, 2.5 M hexane solution) of n-butyllithium (n-BuLi) and 1.3 g (15 mmol) of cuprous cyanide (CuCN) were added to this 1-benzothiophene solution. Next, 3.6 g (30 mmol) of tigloyl chloride was slowly added to the solution at -80 °C, and the resulting solution was stirred at room temperature for approximately 10 hours. The reaction was then terminated by adding 10% hydrochloric acid, and the organic layer was separated with dichloromethane to obtain a pale yellow solid (2E)-1-(1-benzothiophene-2-yl)-2-methyl-2-buten-1-one.

[0268]

[0269] 1 H NMR(CDCl3): δ 7.85-7.82(m, 2H), 7.75(m, 1H), 7.44-7.34(m, 2H), 6.68(m, 1H), 1.99(m, 3H), 1.92(m, 3H).

[0270] 5.0 g (22 mmol) of the (2E)-1-(1-benzothiophene-2-yl)-2-methyl-2-buten-1-one prepared above was dissolved in 5 mL of chlorobenzene to prepare a solution. 34 mL of sulfuric acid was slowly added to this solution while stirring vigorously. The solution was then stirred at room temperature for approximately 1 hour. Subsequently, ice water was poured into the solution, and the organic layer was separated using diethyl ether to give 4.5 g of 1,2-dimethyl-1,2-dihydro-3H-benzo[b]cyclopentano[d]thiophene-3-one as a yellow solid (yield 91%).

[0271]

[0272] 1 H NMR(CDCl3): δ 7.95-7.91(m, 2H), 7.51-7.45(m, 2H), 3.20(m, 1H), 2.63(m, 1H), 1.59(d, 3H), 1.39(d, 3H).

[0273] At 0 °C, 570 mg (15 mmol) of NaBH4 was added to a solution obtained by dissolving 2.0 g (9.2 mmol) of 1,2-dimethyl-1,2-dihydro-3H-benzo[b]cyclopenta[d]thiophene-3-one in a mixed solvent of 20 mL THF and 10 mL methanol. The solution was then stirred at room temperature for about 2 hours. Afterward, HCl was added to adjust the pH of the solution to 1, and the organic layer was separated with diethyl ether to obtain the alcohol intermediate.

[0274] The alcohol intermediate was dissolved in toluene to prepare a solution. Then, 190 mg (1.0 mmol) of p-toluenesulfonic acid was added to the solution, and the mixture was refluxed for about 10 minutes. The resulting reaction mixture was separated by column chromatography to give 1.8 g (9.0 mmol, 98% yield) of 1,2-dimethyl-3H-benzo[b]cyclopentano[d]thiophene (ligand A) in the form of an orange-brown liquid.

[0275]

[0276] 1 H NMR(CDCl3): δ 7.81(d, 1H), 7.70(d, 1H), 7.33(t, 1H), 7.19(t, 1H), 6.46(s, 1H), 3.35(q, 1H), 2.14(s, 3H), 1.14(d, 3H).

[0277] (2) Preparation of ligand B 13 mL (120 mmol) of tert-butylamine and 20 mL of diethyl ether were added to a 250 mL Schlenk flask. 16 g (60 mmol) of (6-tert-butoxyhexyl)dichloro(methyl)silane and 40 mL of diethyl ether were added to another 250 mL Schlenk flask to prepare solutions of tert-butylamine and (6-tert-butoxyhexyl)dichloro(methyl)silane, respectively. The tert-butylamine solution was then cooled to -78 °C, and the (6-tert-butoxyhexyl)dichloro(methyl)silane solution was slowly added to the cooled solution, followed by stirring at room temperature for approximately 2 hours. The resulting white suspension was filtered to obtain an ivory-colored liquid form of 1-(6-(tert-butoxyhexyl)-N-(tert-butyl)-1-chloro-1-methylsilaneamine (ligand B).

[0278]

[0279] 1 H NMR(CDCl3): δ 3.29(t, 2H), 1.52-1.29(m, 10H), 1.20(s, 9H), 1.16(s,9H), 0.40(s, 3H).

[0280] (3) Crosslinking of ligands A and B 1.7 g (8.6 mmol) of 1,2-dimethyl-3H-benzo[b]cyclopentano[d]thiophene (ligand A) was added to a 250 mL Schulenk flask, followed by the addition of 30 mL of THF to prepare a solution of ligand A. The solution of ligand A was cooled to -78 °C, and then 3.6 mL (9.1 mmol, 2.5 M hexane solution) of n-butyllithium was added. The mixture was then stirred overnight at room temperature to obtain a purple-brown solution. Solution A was prepared by replacing the solvent of the purple-brown solution with toluene and adding 39 mg (0.43 mmol) of CuCN dispersed in 2 mL of THF.

[0281] Simultaneously, solution B was prepared by injecting 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-chloro-1-methylsilaneamine (ligand B) and toluene into a 250 mL Schlenk flask and cooling to -78°C. Solution A prepared above was slowly injected into the cooled solution B. Then, the mixture of solutions A and B was stirred overnight at room temperature. Subsequently, the resulting solid was removed by filtration to obtain 4.2 g (>99% yield) of 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-(1,2-dimethyl-3H-benzo[b]cyclopento[d]thiophene-3-yl)-1-methylsilaneamine (a crosslinking product of ligands A and B) in the form of a brown viscous liquid.

[0282]

[0283] To confirm the structure of the crosslinked product of ligands A and B, the crosslinked product was lithiated at room temperature, and then a sample dissolved in a small amount of pyridine-D5 and CDCl3 was used to obtain... 1 H-NMR spectrum.

[0284] 1 ¹H NMR (pyridine-D5 and CDCl3): δ 7.81 (d, 1H), 7.67 (d, 1H), 7.82–7.08 (m, 2H), 3.59 (t, 2H), 3.15 (s, 6H), 2.23–1.73 (m, 10H), 2.15 (s, 9H), 1.91 (s, 9H), 1.68 (s, 3H).

[0285] (4) Preparation of transition metal compounds 4.2 g (8.6 mmol) of 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophene-3-yl)-1-methylsilaneamine (the crosslinking product of ligands A and B) was added to a 250 mL Schlenk flask, and 14 mL of toluene and 1.7 mL of n-hexane were added to the flask to dissolve the crosslinking product. The solution was cooled to -78 °C, and then 7.3 mL (18 mmol, 2.5 M hexane solution) of n-butyllithium was added to the cooled solution. The solution was then stirred at room temperature for about 12 hours. Then, 5.3 mL (38 mmol) of trimethylamine was added to the solution, and the mixture was stirred at about 40 °C for about 3 hours to prepare solution C.

[0286] Simultaneously, 2.3 g (8.6 mmol) of TiCl4(THF)2 and 10 mL of toluene were added to a separately prepared 250 mL Schlenk flask to prepare solution D, in which TiCl4(THF)2 is dispersed in toluene. Solution C, prepared prior to solution D, was slowly injected at -78 °C, and the mixture of solutions C and D was stirred at room temperature for approximately 12 hours. Afterward, the solvent was removed under reduced pressure, and the resulting solute was dissolved in toluene. The undissolved solid in toluene was then removed by filtration, and the solvent was removed from the filtrate to give 4.2 g (83% yield) of a brown solid containing the transition metal compound.

[0287]

[0288] 1H NMR(CDCl3): δ 8.01(d, 1H), 7.73(d, 1H), 7.45-7.40(m, 2H), 3.33(t,2H), 2.71(s, 3H), 2.33(d, 3H), 1.38(s, 9H), 1.18(s, 9H), 1.80-0.79(m, 10H), 0.79(d, 3H).

[0289] Synthesis Example 4

[0290] (1) Preparation of ligand compounds: Synthesis of N-tert-butyl-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1,1-dimethylsilane. 4.65 g (15.88 mmol) of the compound of formula 3 was added to a 100 mL Schlenk flask, followed by 80 mL of tetrahydrofuran (THF). Tert-butylamine (tBuNH2, 4 equivalents, 6.68 mL) was added at room temperature, and the mixture was reacted at room temperature for 3 days. After the reaction was complete, THF was removed, and the mixture was filtered through hexane. After drying the solvent, 4.50 g (yield: 86%) of a yellow liquid was given.

[0291] 1 H-NMR (500 MHz, CDCl3): δ 7.99(d, 1H), 7.83(d, 1H), 7.35(dd, 1H), 7.24(dd, 1H), 3.49(s, 1H), 2.37(s, 3H), 2.17(s, 3H), 1.27(s, 9H), 0.19(s,3H), -0.17(s, 3H).

[0292] (2) Preparation of transition metal compounds The ligand compound (1.06 g, 3.22 mmol / 1.0 equivalent) and 16.0 mL (0.2 M) MTBE were added to a 50 mL Schlenk flask and stirred. At -40 °C, n-butyllithium (n-BuLi) (2.64 mL, 6.60 mmol / 2.05 equivalent, 2.5 M THF solution) was added, and the mixture was reacted overnight at room temperature. Then, MeMgBr (2.68 mL, 8.05 mmol / 2.5 equivalent, 3.0 M diethyl ether solution) was slowly added dropwise at -40 °C, followed by titanium tetrachloride (TiCl4) (2.68 mL, 3.22 mmol / 1.0 equivalent, 1.0 M toluene solution), and the reaction was continued overnight. The reaction mixture was filtered through diatomaceous earth with hexane. After solvent drying, 1.07 g (yield: 82%) of a brown solid was given.

[0293] 1 H-NMR (500 MHz, CDCl3): δ 7.99(d, 1H), 7.68(d, 1H), 7.40(dd, 1H),7.30(dd, 1H), 3.22(s, 1H), 2.67(s, 3H), 2.05(s, 3H), 1.54(s, 9H), 0.58(s,3H), 0.57(s, 3H), 0.40(s, 3H), -0.45(s, 3H).

[0294] <Preparation of Supported Catalysts> Catalyst Preparation Example 1: Preparation of Hybrid Supported Metallocene Catalysts 3.0 kg of toluene solution was added to a 20 L stainless steel (SUS) high-pressure reactor, and the reactor temperature was maintained at 40 °C. 500 g of silica (Grace Davison, SP2212) was vacuum dehydrated at 600 °C for 12 hours and then added to the reactor, allowing it to disperse thoroughly. Then, 2.78 kg of a 10 wt% methylaluminoxane (MAO) / toluene solution was added, and the mixture was stirred at 200 rpm for 15 hours at 80 °C to initiate the reaction.

[0295] After lowering the reactor temperature to 40°C, 200 g of the first metallocene compound / toluene solution (7.8 wt% toluene solution) prepared in Synthesis Example 1 was added to the reactor, and the mixture was stirred at 200 rpm for 1 hour. Subsequently, 250 g of the second metallocene compound (b) / toluene solution (7.8 wt% toluene solution) prepared in Synthesis Example 3 was added to the reactor, and the mixture was stirred at 200 rpm for 1 hour (the molar ratio of the first metallocene compound to the second metallocene compound was 1:1.3).

[0296] 70 g of the co-catalyst (phenylammonium tetra(pentafluorophenyl)borate) was diluted with toluene and added to the reactor, and stirred at 200 rpm for at least 15 hours. After the reactor temperature was lowered to room temperature, stirring was stopped, and the mixture was allowed to stand for 30 minutes before decantation.

[0297] The toluene slurry was transferred to a filter dryer for filtration. 3.0 kg of toluene was added and stirred for 10 minutes, then stirring was stopped and the mixture was filtered. 3.0 kg of hexane was added to the reactor and stirred for 10 minutes, then stirring was stopped and the mixture was filtered. The mixture was dried under reduced pressure at 50 °C for 4 hours to obtain 500 g of the SiO2 hybrid supported catalyst 1.

[0298] Catalyst Preparation Example 2: Preparation of Hybrid Supported Metallocene Catalyst 2 5.0 kg of toluene solution was added to a 20 L stainless steel (SUS) high-pressure reactor, and the reactor temperature was maintained at 40 °C. 1000 g of silica (Sylopol 948, manufactured by Grace Davison) was dehydrated under vacuum at 600 °C for 12 hours and then added to the reactor and thoroughly dispersed. Then, 80 g of the first metallocene compound from Synthesis Example 1 was dissolved in toluene and added to the reactor. The reaction was carried out at 40 °C and stirred at 200 rpm for 2 hours. After the reaction was completed, stirring was stopped, the mixture was allowed to stand for 30 minutes, and then the reaction solution was decanted.

[0299] Add 2.5 kg of toluene to the reactor, followed by 9.4 kg of a 10 wt% methylaluminoxane (MAO) / toluene solution. Stir at 200 rpm for 12 hours at 40°C. After the reaction is complete, stop stirring, let stand for 30 minutes, and then decant the reaction solution. Add 3.0 kg of toluene and stir for 10 minutes, then stop stirring, let stand for 30 minutes, and then decant the toluene solution.

[0300] 3.0 kg of toluene was added to the reactor, followed by 314 mL of a 29.2 wt% solution of the second metallocene compound from Synthesis Example 2. The reaction was carried out at 40 °C and stirred at 200 rpm for 2 hours. At this point, the molar ratio of the first metallocene compound to the second metallocene compound was 1:5. After cooling the reactor to room temperature, stirring was stopped, and the mixture was allowed to stand for 30 minutes before decanting the reaction solution.

[0301] Add 2.0 kg of toluene and stir for 10 minutes, then stop stirring, let stand for 30 minutes, and then decant the reaction solution.

[0302] 3.0 kg of hexane was added to the reactor, and the hexane slurry was transferred to a filter dryer to filter the hexane solution. The solution was then dried under reduced pressure at 40 °C for 4 hours to prepare 910 g of the SiO2 hybrid supported catalyst 2.

[0303] Preparation of ethylene-α-olefin copolymers Preparation Example 1: Preparation of ethylene / 1-hexene copolymer (PE-a) In the presence of the supported hybrid catalyst 1 prepared in Catalyst Preparation Example 1, ethylene / 1-hexene copolymer (PE-a) was polymerized in slurry using a single-peak polymerization process.

[0304] Specifically, a hexane slurry-stirred batch polymerization reactor was used in a single-ring reactor (polymerization temperature: 93℃, polymerization pressure: 7.7 kgf / cm²). 2 In the catalyst preparation example 1, the hybrid supported metallocene catalyst 1 prepared in the catalyst preparation example 1 was used to obtain ethylene / 1-hexene copolymer (PE-a) under the conditions of 10.0 kg / hr ethylene feed, 6.3 ml / min 1-hexene comonomer feed and 1.80 g / hr hydrogen feed.

[0305] Catalytic activity was obtained by measuring the weight of the catalyst used in the polymerization reaction and the weight of the polymer prepared by the polymerization reaction, and then calculating the weight ratio of the prepared polymer to the weight of the catalyst used. The result was 9.9 kgPE / gCat.hr.

[0306] Preparation Example 2: Preparation of Ethylene / 1-Hexene Copolymer (PE-b) The preparation method of ethylene / 1-hexene copolymer (PE-b) is the same as that in Preparation Example 1, except that when carrying out the slurry polymerization reaction of ethylene / 1-hexene copolymer, the feed rate of 1-hexene is adjusted to 6.2 mL / min and the feed rate of hydrogen is adjusted to 1.90 g / hr.

[0307] Preparation Example 3: Preparation of Ethylene / 1-Hexene Copolymer (PE-c) The preparation method of ethylene / 1-hexene copolymer (PE-c) is the same as that in Preparation Example 1, except that the hydrogen feed rate is adjusted to 1.73 g / hr when carrying out the slurry polymerization reaction of ethylene / 1-hexene copolymer.

[0308] Preparation Example 4: Preparation of Ethylene / 1-Hexene Copolymer (PE-d) In the presence of the hybrid supported catalyst 2 prepared in Catalyst Preparation Example 2, slurry polymerization of ethylene / 1-hexene copolymer (PE-d) was carried out.

[0309] At this point, the polymerization reactor was an isobutane (i-C4) slurry loop reactor, a continuous polymerization reactor with a reactor volume of 140 L and a flow rate of approximately 7 m / s. The gases required for polymerization (ethylene, hydrogen) and the comonomer 1-hexene were continuously introduced, with the flow rate adjusted according to the target product. At this point, the ethylene feed rate was 31.1 kg / hr, the 1-hexene feed rate was adjusted to 4.3 wt% relative to ethylene, and the hydrogen feed rate was adjusted to 95 ppm relative to ethylene. Furthermore, the concentrations of all gases and the 1-hexene comonomer used in Preparation Example 2 were confirmed by online gas chromatography. A supported catalyst was prepared and introduced in the form of a 4 wt% isobutane slurry, the reactor pressure was maintained at approximately 40 bar, and the polymerization temperature was approximately 80°C.

[0310] Preparation Example 5: Preparation of ethylene / 1-hexene copolymer (PE-e) The preparation method of ethylene / 1-hexene copolymer (PE-e) is the same as that in preparation Example 4, except that when carrying out the slurry polymerization reaction of ethylene / 1-hexene copolymer, the feed amount of 1-hexene is adjusted to 4.5 wt% relative to ethylene, and the feed amount of hydrogen is adjusted to 100 ppm relative to ethylene.

[0311] Preparation Example 6: Preparation of ethylene / 1-hexene copolymer (PE-f) The preparation method of ethylene / 1-hexene copolymer (PE-f) is the same as that in preparation Example 3, except that when carrying out the slurry polymerization reaction of ethylene / 1-hexene copolymer, the feed amount of 1-hexene is adjusted to 2.5 wt% relative to ethylene, and the feed amount of hydrogen is adjusted to 56 ppm relative to ethylene.

[0312] Preparation Example 7: Preparation of Ethylene / 1-Octene Copolymer (PE-g) The continuous process reactor (1.5 L) was preheated to 120 °C, and hexane solvent was introduced at a rate of 5 kg / h, while 1-octene was introduced at a rate of 0.31 kg / h. Triisobutylaluminum (Tibal, 0.045 mmol / min), the transition metal compound obtained in Synthesis Example 4, and dimethylphenylammonium tetra(pentafluorophenyl)borate cocatalyst (2.6 μmol / min) were simultaneously introduced into the reactor. Subsequently, ethylene (0.87 kg / hr) and hydrogen (10 cc / min) were introduced into the reactor, and the copolymerization reaction was carried out continuously at 160.0 °C for at least 60 minutes under a pressure of 89 bar to obtain the ethylene / 1-octene copolymer (PE-g).

[0313] <Test Example 1: Evaluation of the Physical Properties of Polyethylene> The physical properties of the ethylene-α-olefin copolymers prepared in Examples 1 to 7 were determined using the following methods and are shown in Table 1.

[0314] (1) Density Density (g / cm³) was determined using a density gradient column according to ASTM D 1505 (American Society for Testing and Materials) standard. 3 ).

[0315] (2) Melt index Melt Flow Index (MI) 2.16 According to ASTM D 1238 (condition E, 190°C, 2.16 kg), measured at 2.16 kg load and 190°C (measuring equipment: Gottfert MI-4), and expressed as the weight of polymer after 10 minutes of melting (g).

[0316] (3) Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) For the ethylene-α-olefin copolymers prepared in Examples 1 to 7, the weight-average molecular weight (Mw, g / mol) and number-average molecular weight (Mn, g / mol) were determined by gel permeation chromatography (GPC, Waters Corporation) according to ASTM D 6474 (American Society for Testing and Materials) standard. The molecular weight distribution (Mw / Mn, PDI, polydispersity index) was then calculated by dividing the weight-average molecular weight by the number-average molecular weight.

[0317] Specifically, a Waters PL-GPC220 gel permeation chromatography (GPC) instrument was used, along with a Polymer Laboratories PLgel MIX-B 300 mm long column. The evaluation temperature was 160 °C, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was 1 mL / min. The ethylene-α-olefin copolymer samples prepared in Examples 1 to 7 were pretreated using a GPC analyzer (PL-GP220) at 160 °C by dissolving in 1,2,4-trichlorobenzene containing 0.0125% BHT for 3 hours. A 200 μL sample at a concentration of 32 mg / 10 mL was then loaded. Mw and Mn were obtained using a calibration curve generated using polystyrene standards. Nine polystyrene standards were used, with 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.

[0318] Table 1

[0319] <Preparation of Polyethylene Compositions> Examples 1 to 2 and Comparative Examples 1 to 6 The polyethylene compositions of Examples 1 to 2 and Comparative Examples 1 to 6 were prepared using the ethylene-α-olefin copolymers of Examples 1 to 7 as shown in Table 2 below.

[0320] Specifically, the polyethylene composition was prepared as follows: extrusion granulation was carried out using a twin-screw extruder (extruder: SMPLATEK TEK30MHS, length-to-diameter ratio: 40, die diameter: 4 mm) at 220°C with a hopper speed of 18 rpm and a screw speed of 350 rpm.

[0321] <Test Example 2: Evaluation of the Physical Properties of Polyethylene Compositions> The physical properties of the polyethylene compositions prepared in Examples 1 to 2 and Comparative Examples 1 to 6 were determined by the following methods and are shown in Table 2 below.

[0322] First, the melt index (MI) of the polyethylene composition was determined using the same method as in Test Example 1 above. 2.16 MI 21.6 and MFRR = MI 21.6 / MI 2.16 ), density, weight-average molecular weight (Mw, g / mol), number-average molecular weight (Mn, g / mol), and molecular weight distribution (Mw / Mn, PDI).

[0323] (4) Melting temperature, crystallization temperature and crystallinity The melting temperature (Tm), crystallization temperature (Tc), and crystallinity (Xc) of the polyethylene compositions of Examples 1 and 2 and Comparative Examples 1 to 6 were determined using a differential scanning calorimeter (DSC, instrument name: DSC Q20, manufacturer: TA Instruments).

[0324] Specifically, the polyethylene composition was heated to 180°C at a rate of 10°C / min (Cycle 1), held at 180°C for 5 minutes, cooled to 0°C at a rate of 10°C / min, held at 30°C for 5 minutes, and then heated again to 180°C at a rate of 10°C / min (Cycle 2). In the resulting DSC curve, the temperature at the maximum endothermic peak was measured as the melting temperature (Tm,°C), and the temperature at the maximum exothermic peak was measured as the crystallization temperature (Tc,°C). Here, both the melting temperature (Tm) and the crystallization temperature (Tc) were obtained from Cycle 2 (the second heating and cooling process).

[0325] Furthermore, the heat of fusion ΔHm is obtained by calculating the area of ​​the melting peak in cycle 2 during the second temperature rise, and the crystallinity (Xc, %) is calculated by dividing ΔHm by H. 0 The value was calculated based on m = 293.6 J / g (which is the theoretical value when the crystallinity is 100%).

[0326] (5) Cross-fractional chromatography (CFC) The polyethylene compositions of Examples 1 to 2 and Comparative Examples 1 to 6 were analyzed by cross-fractional chromatography (CFC) in the following manner. This analysis measured the following values: the percentage of highly crystalline fractions eluted at temperatures above 90°C (wt%, T≥90°C) and their weight-average molecular weight (Mw, g / mol, T≥90°C), as well as the weight-average molecular weight of the main chain of the highly crystalline fractions (Mw...). 主，T≥90℃ The content ratio (wt%, T<90℃) and weight-average molecular weight (Mw, g / mol, T<90℃) of the medium and low crystallinity fractions eluted below 90℃; the content ratio (wt%, T≥70℃, <90℃) and weight-average molecular weight (Mw, g / mol, T≥70℃, <90℃) of the medium crystallinity fractions eluted from above 70℃ to below 90℃; the content ratio (wt%, T≥35℃, <70℃) and weight-average molecular weight (Mw, g / mol, T≥35℃, <70℃) of the low crystallinity fractions eluted from above 35℃ to below 70℃; and the content ratio (wt%, T<35℃) and weight-average molecular weight (Mw, g / mol, T<35℃) of the soluble fraction (SF) eluted below 35℃.

[0327] Cross-fractional chromatography (CFC) measurement conditions (including TREF and GPC-IR analysis) - Analysis equipment: Polymer Char CFC (Detector: Integrated detector IR5 MCT) - Sample preparation and injection: Add 32 mg of the polyethylene composition to a 10 mL vial and place it in an autosampler. Then add 8 mL of 1,2,4-trichlorobenzene (TCB), dissolve at 160 °C for 90 min, extract after nitrogen purging, and then load the sample onto a temperature elution fractionation column (TREF column).

[0328] - Crystallization: Adjust the temperature of the sample previously loaded onto the TREF column to 100°C, and then cool it from 100°C to 35°C at a rate of 0.5°C / min.

[0329] - Temperature-elution fractionation (TREF) analysis: The previously crystallized sample was heated from 35°C to 125°C at 3°C ​​intervals and held at this temperature. Fractions eluted for 25 minutes at each temperature were then analyzed. Specifically, extraction and analysis were performed at 35°C for 25 minutes, followed by extraction and analysis at 3°C ​​intervals, and finally extraction and analysis were performed at 125°C for 25 minutes.

[0330] - GPC-IR Analysis: Fractions eluted at different temperatures during TREF analysis were transferred to a GPC (PL-GPC220) column. The molecular weight of the eluted molecules was determined, and the number of short-chain branches (scb) was determined using a connected PerkinElmer Spectrum 100 FT-IR spectrometer. scb is defined as a branch containing 2 to 7 carbon atoms per 1000 carbon atoms (unit: branch / 1000 C).

[0331] - Main chain average molecular weight (Mw) 主，T≥90℃ Determination of molecular weight (Mw): In fractions eluted at temperatures above 90°C as confirmed by CFC analysis, the weight-average molecular weight (Mw) of the main chain (excluding short-chain branches) is determined according to Formula 1. 主，T≥90℃ (g / mol).

[0332] [Formula 1] Mw 主,T≥90℃ (g / mol)=

[0333] In Formula 1, M T,i and C T,i These are the weight-average molecular weight (g / mol) and concentration of each fraction eluted at a given temperature, as determined by the CFC analysis described above. n scb T,i It is based on the number of side chain branches (scb) in each fraction eluted at a given temperature, as determined by the CFC analysis described above; M scb The weight-average molecular weight (g / mol) of the side chain branches (scb) determined by CFC analysis.

[0334] (6) Short-chain branched (SCB) content CFC analysis was performed using the method described above. After determining the molecular weight of the eluted molecules, the molecular weights were determined to be between 200,000 g / mol and 500,000 g / mol (i.e., Mw range of 10). 5.3 Up to 10 5.7The number of short-chain branches (scb) is determined within the range of Log MW (5.3 to 5.7), specifically the content of branches with 2 to 7 carbon atoms per 1000 carbon atoms.

[0335] Table 2

[0336] <Test Example 3: Preparation and Physical Property Evaluation of Biaxially Stretched Membranes> Biaxially stretched films were prepared using the polyethylene compositions prepared in Examples 1 to 2 and Comparative Examples 1 to 6 according to the following process, and their physical properties were measured and are shown in Table 3 below.

[0337] Preparation of biaxially stretched membranes - Polyethylene composite sheets (0.75 mm thick) were produced using a laboratory extrusion line (Bruckner; L / D ratio: 42, screw diameter: 25 mm, melt / T-die temperature: 220°C).

[0338] - Biaxial stretching of polyethylene composition sheets with dimensions of 90 mm × 90 mm was performed using a KARO 5.0 machine.

[0339] - Under the following conditions, after preheating for 80 seconds, sequential stretching was performed (first longitudinal (MD) stretching, then transverse (TD) stretching). Example 1 and Comparative Example 1 were stretched at 122°C, Example 2 and Comparative Example 2 were stretched at 124°C, and Example 3, Comparative Example 3 and Comparative Example 4 were stretched at 126°C.

[0340] Evaluation of physical properties of biaxial stretch membrane - Haze (%): Measured according to ASTM 1003 standard.

[0341] - Tensile strength (MPa), tensile modulus (MPa), and elongation at break (%): measured in the MD / TD direction according to ASTM D 882.

[0342] - Tear strength (N / mm): Measured in the MD / TD direction according to ASTM 1922 standard.

[0343] - Shrinkage (%): Measured according to ASTM D 1204 standard, the length change is observed after shrinking at 100°C for 7 minutes. The calculation formula is [(1 - length after shrinkage) / length before shrinkage] × 100.

[0344] - Puncture strength (N / mm): Measured according to EN 14477 standard.

[0345] - Drop hammer impact strength (g): Measured according to ASTM D 1709 standard using the drop dart method A, i.e., drop dart impact strength (front).

[0346] Table 3

[0347] The results in Tables 2 and 3 show that, compared to Comparative Examples 1 to 6, the biaxially stretched films prepared using the polyethylene compositions of Examples 1 to 2 (which have a bimodal molecular structure, higher weight-average molecular weight, and higher content of high- and medium-crystallinity fractions) exhibit significantly higher tensile strength, puncture strength, and dart impact strength. This is because the higher weight-average molecular weight and the higher content of high- and medium-crystallinity fractions in the polyethylene compositions of Examples 1 to 2 enable the formation of a crystalline stretched backbone, thereby facilitating the formation of the stretched structure.

[0348] Therefore, the polyethylene compositions disclosed herein can be used to prepare biaxially stretched films with excellent tensile stability and mechanical properties (such as tensile strength, puncture strength, and dart impact strength), as well as high bimodality. This results in lower viscosity during processing, excellent processing performance, and high productivity, which is highly advantageous for the commercial production of single-material packaging films with high shrinkage resistance, printability, and transparency.

Claims

1. A polyethylene composition comprising at least one ethylene-α-olefin copolymer, wherein, Based on cross-fractional chromatography (CFC) analysis of the polyethylene composition: The high crystallinity fraction eluted at temperatures above 90°C accounts for more than 50 wt% to less than 80 wt% of the total eluted fraction; The weight-average molecular weight (Mw) of the highly crystallinity fraction is above 140,000 g / mol and below 180,000 g / mol; The medium-crystallinity fraction eluted at temperatures above 70°C and below 90°C accounts for more than 10 wt% and less than 45 wt% of the total eluted fraction; and The weight-average molecular weight (Mw) of the medium crystallinity fraction is above 50,000 g / mol and below 80,000 g / mol.

2. The polyethylene composition according to claim 1, wherein, Based on cross-fractional chromatography (CFC) analysis of the polyethylene composition: The low-crystallinity fraction eluted at a temperature above 35°C and below 70°C accounts for less than 15.2 wt% to 25.5 wt% of the total eluted fraction; and The weight-average molecular weight (Mw) of the low crystallinity fraction is above 44,000 g / mol and below 49,000 g / mol.

3. The polyethylene composition according to claim 1, wherein, Based on cross-fractional chromatography (CFC) analysis of the polyethylene composition: The soluble fraction (SF) eluted at temperatures below 35°C accounts for more than 2 wt% to less than 6 wt% of the total eluted fraction.

4. The polyethylene composition according to claim 1, wherein, Based on cross-fractional chromatography (CFC) analysis of the polyethylene composition: The eluted molecules with a weight-average molecular weight (Mw) ranging from 200,000 g / mol to less than 500,000 g / mol have a short-chain branch (scb) content of more than 4 per 1,000 carbon atoms.

5. The polyethylene composition according to claim 1, in, The polyethylene composition has the following properties: According to ASTM D 1505, the density is 0.925 g / cm³. 3 Up to 0.950 g / cm 3 The following; and According to ASTM D 1238, melt flow index (MI) 2.16 (At 190°C and 2.16 kg load) the concentration was 0.1 g / 10 min or more to 1.0 g / 10 min or less.

6. The polyethylene composition according to claim 1, in, The polyethylene composition has the following properties: According to ASTM D 1238, the melt flow rate ratio (MFRR, defined as MI) is... 21.6 / MI 2.16 MI 21.6 The MI was measured at 190℃ and a load of 21.6 kg. 2.16 (Measured at 190℃ and 2.16 kg load) The value is above 70.

0.

7. The polyethylene composition according to claim 1, in, The polyethylene composition has the following properties: The number-average molecular weight (Mn) is above 15000 g / mol. Weight-average molecular weight (Mw) of 100,000 g / mol or higher, and The molecular weight distribution (Mw / Mn) is above 5.0 to below 11.

5.

8. The polyethylene composition according to claim 1, in, The polyethylene composition has the following properties: Melting point (Tm) is above 127℃ and below 130℃. The crystallization temperature (Tc) is above 111℃ and below 115℃. Crystallinity (Xc) is above 55% and below 70%.

9. The polyethylene composition according to claim 1, in, The polyethylene composition comprises: (a) A first ethylene-α-olefin copolymer with a density of 0.930 g / cm³ 3 Up to 0.960 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) was 0.2 g / 10 min to 2.0 g / 10 min at 190 °C and 2.16 kg load, and the molecular weight distribution (Mw / Mn) was ≥5 to ≤8.7; and (b) A second ethylene-α-olefin copolymer with a density of 0.870 g / cm³. 3 Up to 0.920 g / cm 3 Melt index (MI) 2.16 The molecular weight distribution (Mw / Mn) was 3.0 g / 10 min to 10.0 g / 10 min at 190℃ and 2.16 kg load, and the molecular weight distribution (Mw / Mn) was above 2.0 to below 4.

0. The polyethylene composition comprises: (a) the first ethylene-α-olefin copolymer in amounts of 60 wt% to 90 wt%; and (b) the second ethylene-α-olefin copolymer in amounts of 10 wt% to 40 wt%.

10. The polyethylene composition according to claim 9, in, (a) The first ethylene-α-olefin copolymer has: Number-average molecular weight (Mn) from 12,000 g / mol to 50,000 g / mol, and Weight-average molecular weight (Mw) ranging from 100,000 g / mol to 250,000 g / mol.

11. The polyethylene composition according to claim 9, wherein, (a) The first ethylene-α-olefin copolymer is an ethylene / 1-hexene copolymer.

12. The polyethylene composition according to claim 9, in, (b) The second ethylene-α-olefin copolymer has: Number-average molecular weight (Mn) from 20,000 g / mol to 50,000 g / mol, and Weight-average molecular weight (Mw) ranging from 50,000 g / mol to 100,000 g / mol.

13. The polyethylene composition according to claim 9, wherein, (b) The second ethylene-α-olefin copolymer is an ethylene / 1-octene copolymer.

14. A biaxially stretched film comprising the polyethylene composition as described in claim 1.

15. The biaxially stretched membrane according to claim 14, wherein, The membrane has a longitudinal (MD) stretch ratio of 4 or more and a transverse (TD) stretch ratio of 7 or more.

16. The biaxially stretched membrane according to claim 14, wherein, The average longitudinal (MD) tensile strength and transverse (TD) tensile strength of the membrane, as measured according to ASTM D 882 standard, are above 150 MPa.

17. The biaxially stretched membrane according to claim 14, wherein, According to ASTM D 882 standard, the average value of the longitudinal (MD) tensile modulus and transverse (TD) tensile modulus of the membrane is above 600 MPa.

18. The biaxially stretched membrane according to claim 14, wherein, According to EN 14477 standard, the puncture strength of the membrane is above 400 N / mm.

19. The biaxially stretched membrane according to claim 14, wherein, According to ASTM D 1709 standard, using the dart impact test A, the dart impact strength (front side) of the membrane is above 490 g.

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