Polyethylene compositions and articles made therefrom

Abstract

The present invention relates to a polyethylene composition comprising polyethylene having an excellent balance between processability and mechanical properties. The polyethylene composition has significantly improved polymer melt strength and also exhibits good shear sensitive behavior while also providing improved mechanical properties. As shown in the present invention, due to the synergistic behavior of the dual catalyst system, in which a single polymerization reactor can be used to prepare the polyethylene, as a result of polymers characterized by molecular weight distribution and short chain branching distribution.

Description

Technical Field

[0001] This invention relates to the scientific field, and more particularly to polyethylene compositions and articles comprising polyethylene compositions. Background Technology

[0002] Olefin-based polymers, particularly vinyl polymers or polyethylene, can be used in many products. The properties and characteristics of polyethylene can be adjusted or differentiated according to key factors in the polymerization process and the catalysts used in the polymerization process to suit different applications.

[0003] Currently, the development of polyethylene for diverse applications focuses on simultaneously developing multiple properties and characteristics of polyethylene. This can be achieved through cascade polymerization processes, such as the solution polymerization process using two cascaded reactors employed by Dow Chemical, or the slurry polymerization process using a circulating reactor employed by Borealis, followed by a gas-phase polymerization process. Optionally, this can be achieved by selecting catalyst systems from several aspects, such as multi-site catalyst systems or mixed catalyst systems containing two or more different polymerization catalysts, which may be Ziegler-Natta catalysts or metallocene catalysts, wherein the average molar mass of polyethylene produced by each catalyst or at each site differs from that produced by another catalyst or at other sites.

[0004] The following literature discloses the development of polyethylene, focusing on the development of several properties of polyethylene by selecting catalyst systems.

[0005] Patent document US20210147661A1 discloses polyethylene having low molecular weight fractions and high molecular weight fractions, wherein the low molecular weight fraction has a low concentration of short chain branches (SCB) of comonomers, and the high molecular weight fraction has a high concentration of short chain branches of comonomers. The ratio of the number of short chain branches at Z-average molecular weight (Mz) to the number of short chain branches at number-average molecular weight (Mn) is 11.5 to 22. The polyethylene is prepared via a dual-catalyst system comprising a non-bridged metallocene compound having an indenyl group (which has at least one halogenated hydrocarbon substituent with at least two halogen atoms) and a single-atom-bridged metallocene compound having a fluorenyl group and a cyclopentadienyl group. The polyethylene exhibits improved environmental stress crack resistance (ESCR), improved resistance to slow crack growth, and improved elongation.

[0006] Patent document WO2007008361A1 discloses a polyethylene comprising a low-molecular-weight polyethylene component and a high-molecular-weight polyethylene component. The low-molecular-weight polyethylene component has a higher concentration of long-chain branches (LCBs) than the high-molecular-weight polyethylene component. The low-molecular-weight polyethylene component is selected from polyethylene prepared using a single-site catalyst containing a bridging indole ligand. The high-molecular-weight polyethylene component is selected from polyethylene prepared using a single-site catalyst containing a non-bridging indole ligand. The polyethylene exhibits good mechanical and processing properties.

[0007] Patent document WO2002074816A2 discloses a polyethylene comprising low molecular weight components and high molecular weight components, wherein the comonomers of the low molecular weight components and high molecular weight components are incorporated in substantially equal amounts. The polyethylene is prepared using at least two catalysts during the polymerization process. The polyethylene has been found to possess good polymer melt strength and processing properties, as well as optical properties similar to low-density polyethylene (LDPE) and better mechanical properties compared to LDPE.

[0008] Patent document US20210309841A1 discloses a polyethylene comprising a low molecular weight component with numerous long-chain branches and a high molecular weight component with virtually no long-chain branches. The polyethylene is prepared via a dual-catalytic system comprising a metallocene compound with single-atom bridging of indene and cyclopentadienyl groups and a non-bridging hafnium metallocene compound with two cyclopentadienyl groups. The polyethylene exhibits good strength, good toughness, and good tear strength, while maintaining polymer melt strength and film / bubble stability.

[0009] Patent document US20170145123A1 discloses polyethylene with low density, high molecular weight, and a wide molecular weight distribution, wherein most of the long-chain branches are in the low molecular weight component, and most of the short-chain branches are in the high molecular weight component. The polyethylene is prepared using a bismetallocene catalytic system. Membranes prepared from the polyethylene exhibit improved impact resistance and puncture resistance.

[0010] Patent document US20190233551A1 discloses polyethylene with an inverted short-chain branching distribution, wherein the number of short-chain branches at the Z-average molecular weight (Mz) is greater than the number of short-chain branches at the number-average molecular weight (Mn). The polyethylene is prepared via a catalytic system comprising a semi-metallocene titanium compound, a bridging metallocene compound, an activator, and a co-catalyst. The polyethylene exhibits good strength and toughness, as well as good processability and shear thinning. In particular, blown films prepared from this polyethylene exhibit good dart impact resistance, tear strength, and optical properties, and are easier to process and have better polymer melt strength than linear low-density polyethylene resins prepared using conventional metallocene catalysts.

[0011] It can be seen that the choice of catalytic system affects the differences in the introduction of comonomers, leading to differences in the number and distribution of side chains formed by the introduced monomers, i.e., short chain branching distribution (SCBD). These affect the crystallization behavior of polyethylene, especially its mechanical properties. While the flow properties affecting processing performance mainly depend on molar mass and molar mass distribution, short chain branching distribution also influences flow properties and processing performance. However, from the perspective of possible combinations, a balanced combination of good processing performance and good mechanical properties is rare, and only a portion have been disclosed in previously published inventions.

[0012] Therefore, the present invention provides a polyethylene composition comprising polyethylene, which has an excellent balance between processing properties and mechanical properties. In another aspect, the polyethylene is characterized by a molecular weight distribution and a short-chain branching distribution, and the polyethylene is prepared by a polymerization process using a single reactor with a dual-catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound. Summary of the Invention

[0013] The present invention aims to provide a polyethylene composition comprising polyethylene having an excellent balance between processability and mechanical properties, wherein the polyethylene comprises ethylene monomer and 0.1 to 35% by weight of C3-C20 α-olefin comonomer, and wherein the polyethylene has the following properties:

[0014] - Density ranges from 0.910 to 0.935 g / cm³ 3 ;

[0015] - Melt flow rate (MFR) ranges from 0.1 to 100 g / 10 min (measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg);

[0016] - Molecular weight distribution (Mw / Mn) is 3 to 50;

[0017] - The gpcBR index is equal to or greater than 0.3;

[0018] - Chromatograms obtained by gel permeation chromatography (GPC) exhibit multimodal characteristics, wherein the chromatograms undergo deconvolution using a Schulz-Flory distribution and include:

[0019] a) 30% to 55% of the first component having a weight-average molecular weight (Mw) of 20,000 to 75,000 g / mol compared to the total area of ​​the chromatogram;

[0020] b) 35% to 55% of the second component having a weight-average molecular weight (Mw) of 80,000 to 200,000 g / mol, compared to the total area of ​​the chromatogram; and

[0021] c) 5% to 20% of the third component having a weight-average molecular weight (Mw) of 300,000 to 800,000 g / mol, compared to the total area of ​​the chromatogram; and

[0022] -SCB logM2 / SCB logM1 Equal to or less than 1, SCB logM1 Greater than 10, and SCB logM3 / SCB logM2 Greater than or equal to 1, where SCB logM1 The number of short-chain branches (SCB) per 1000 total carbon atoms in polyethylene is measured using logM1. logM2 This is the number of short-chain branches per 1000 total carbon atoms in polyethylene, measured as logM2, and the SCB. logM3 LogM3 is the number of short-chain branches per 1000 total carbon atoms in polyethylene, where logM1, logM2, and logM3 are the logarithms of molecular weights of 4, 5, and 5.5, respectively, in gel permeation chromatography (GPC-IR) analysis with an infrared detector. Attached Figure Description

[0023] Figure 1 Chromatograms of the sample according to invention 1 compared to comparative samples 1 and 2 by gel permeation chromatography (GPC) are shown, illustrating the relationship between the differential weight fraction (dWf / dLogM) and the logarithm of molecular weight (LogM), and the relationship between the number of short-chain branches per 1000 total carbon atoms (SCB / 10000TC) and the logarithm of molecular weight (LogM).

[0024] Figure 2 Chromatograms of the sample according to invention 1 compared to comparative samples 3, 4, 5 and 6 by gel permeation chromatography (GPC) are shown, wherein the relationship between the differential weight fraction (dWf / dLogM) and the logarithm of the molecular weight (LogM) is shown, as well as the relationship between the number of short-chain branches per 1000 total carbon atoms (SCB / 10000TC) and the logarithm of the molecular weight (LogM).

[0025] Figure 3 A gel permeation chromatography (GPC) chromatogram of a sample according to invention 1 is shown, wherein the chromatogram undergoes deconvolution using a Schulz-Flory distribution, wherein the x-axis of the chromatogram represents the logarithm of molecular weight (LogMW), and the y-axis of the chromatogram represents the proportion of the logarithm of molecular weight (W). LogMW ).

[0026] Figure 4 A cross-fractionation chromatography (CFC) chromatogram of a sample according to the present invention is shown, wherein the solid line in the figure represents the relationship between differential weight (dW / dT) relative to temperature and fractionation temperature in degrees Celsius (°C), the dotted line in the figure represents the relationship between the logarithm of molecular weight (LogM) and fractionation temperature in degrees Celsius (°C), and the dashed line in the figure represents the relationship between cumulative weight percentage (total weight) and fractionation temperature in degrees Celsius (°C).

[0027] Figure 5 The cross fractionation chromatography (CFC) chromatogram of Comparative Sample 5 is shown, where the solid line represents the relationship between differential weight (dW / dT) relative to temperature and fractionation temperature in degrees Celsius (°C), the dotted line represents the relationship between the logarithm of molecular weight (LogM) and fractionation temperature in degrees Celsius (°C), and the dashed line represents the relationship between cumulative weight percentage (total weight) and fractionation temperature in degrees Celsius (°C).

[0028] Figure 6 The cross fractionation chromatography (CFC) chromatogram of Comparative Sample 6 is shown. The solid line in the figure represents the relationship between differential weight (dW / dT) relative to temperature and fractionation temperature in degrees Celsius (°C). The dotted line in the figure represents the relationship between the logarithm of molecular weight (LogM) and fractionation temperature in degrees Celsius (°C). The dashed line in the figure represents the relationship between cumulative weight percentage (total weight) and fractionation temperature in degrees Celsius (°C).

[0029] Figure 7The shear viscosity versus shear rate of the sample according to invention 1 at 190°C is shown compared to comparative samples 5 and 6. Detailed Implementation

[0030] This invention relates to polyethylene compositions comprising polyethylene, which have an excellent balance between processing and mechanical properties, wherein the polyethylene is characterized by a molecular weight distribution and a short-chain branching distribution, the polyethylene being prepared by a polymerization process using a single reactor with a dual catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound, which will be described in the following aspects of the invention.

[0031] Any aspect set forth herein is intended to include application to other aspects of the invention, unless otherwise stated.

[0032] The technical or scientific terms used herein have their definitions as understood by one of ordinary skill in the art, unless otherwise stated.

[0033] Any tools, equipment, methods, or chemicals mentioned herein refer to tools, equipment, methods, or chemicals that are commonly operated or used by those skilled in the art, unless otherwise stated, they are only tools, equipment, methods, or chemicals specific to this invention.

[0034] The singular nouns or singular pronouns used with “comprising” in the claims or description mean “one”, and also include “one or more”, “at least one” and “one or more”.

[0035] All compositions and / or methods disclosed in this application, as well as the claims, are intended to cover any embodiments of operation, execution, modification, or adjustment of any element without requiring experiments significantly different from those of the present invention, and to achieve the same practicality and results as embodiments of the present invention to a person skilled in the art, although not specifically stated in the claims. Therefore, alternatives or similar objects to embodiments of the present invention (including any minor modifications or adjustments obvious to a person skilled in the art) should be interpreted as still within the spirit, scope, and concept of the invention as set forth in the appended claims.

[0036] In this application, the term “about” means that any figures appearing or expressed herein may be altered or deviated from due to any error by the equipment, method, or person using said equipment or method, including alterations or deviations due to changes in reaction conditions such as uncontrollable factors like humidity and temperature.

[0037] definition

[0038] "Polyethylene" or "vinyl polymer" means a polymer containing more than 50 mol% of units derived from ethylene monomers. This includes homopolymers or copolymers of polyethylene. Common forms of polyethylene known in the art include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), single-point catalytic linear low-density polyethylene (including linear and essentially linear low-density resins) (m-LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

[0039] "Catalyst system" refers to one or more polymerization catalysts and may also include activators, supports / carriers, or any combination thereof. The terms "catalyst" and "catalyst system" are used interchangeably herein.

[0040] "Dual catalyst system" refers to a catalyst system containing two types or two polymerization catalysts, wherein the polymerization catalysts can be the same or different types, and may also include an activator, a support / transporter, or any combination thereof.

[0041] "Carrier" refers to a support, deposition, attachment, contact, binding, incorporation, adsorption, or absorption of one or more compounds, wherein one or more compounds are supported, deposited on, attached to, in contact with, bound to, incorporated into, adsorbed into, or absorbed on the carrier or transport. This can be referred to as "co-carrier".

[0042] The following describes embodiments of the invention, but they are not intended to limit the scope of the invention.

[0043] This invention relates to a polyethylene composition comprising polyethylene, said polyethylene comprising ethylene monomer and 0.1 to 35% by weight of C3-C20 α-olefin comonomer, wherein said polyethylene has the following properties:

[0044] - Density ranges from 0.910 to 0.935 g / cm³ 3 ;

[0045] - Melt flow rate (MFR) ranges from 0.1 to 100 g / 10 min (measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg);

[0046] - Molecular weight distribution (Mw / Mn) is 3 to 50;

[0047] - The gpcBR index is equal to or greater than 0.3;

[0048] - Chromatograms obtained by gel permeation chromatography (GPC) exhibit multimodal characteristics, wherein the chromatograms undergo deconvolution using a Schulz-Flory distribution and include:

[0049] a) 30% to 55% of the first component having a weight-average molecular weight (Mw) of 20,000 to 75,000 g / mol compared to the total area of ​​the chromatogram;

[0050] b) 35% to 55% of the second component having a weight-average molecular weight (Mw) of 80,000 to 200,000 g / mol, compared to the total area of ​​the chromatogram; and

[0051] c) 5% to 20% of the third component having a weight-average molecular weight (Mw) of 300,000 to 800,000 g / mol, compared to the total area of ​​the chromatogram; and

[0052] -SCB logM2 / SCB logM1 Equal to or less than 1, SCB logM1 Greater than 10, and SCB logM3 / SCB logM2 Greater than or equal to 1, where SCB logM1 The number of short-chain branches (SCB) per 1000 total carbon atoms in polyethylene is measured using logM1. logM2 SCB is the number of short-chain branches per 1000 total carbon atoms in polyethylene, measured as logM2. logM3 LogM3 is the number of short-chain branches per 1000 total carbon atoms in polyethylene, where logM1, logM2, and logM3 are the logarithms of molecular weights of 4, 5, and 5.5, respectively, in gel permeation chromatography (GPC-IR) analysis with an infrared detector.

[0053] In one aspect of the invention, the density of the polyethylene ranges from 0.910 to 0.930 g / cm³. 3 The preferred range is 0.915 to 0.925 g / cm³. 3 The optimal range is 0.915 to 0.920 g / cm³. 3 .

[0054] In one aspect of the invention, the melt flow rate of the polyethylene ranges from 0.1 to 50 g / 10 min (measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg), preferably from 0.1 to 20 g / 10 min, and most preferably from 0.1 to 10 g / 10 min.

[0055] In one aspect of the invention, the chromatogram of the polyethylene obtained by gel permeation chromatography exhibits multimodal characteristics, wherein the chromatogram undergoes deconvolution using a Schulz-Flory distribution and includes:

[0056] a) 30 to 55% of the first component having a weight-average molecular weight (Mw) of 35,000 to 70,000 g / mol, preferably 40,000 to 65,000 g / mol, compared to the total area of ​​the chromatogram;

[0057] b) 35% to 55% of the second component having a weight-average molecular weight (Mw) of 80,000 to 180,000 g / mol, preferably 100,000 to 150,000 g / mol, compared to the total area of ​​the chromatogram; and

[0058] c) 5 to 20% of a third component having a weight-average molecular weight (Mw) of 350,000 to 600,000 g / mol, preferably 400,000 to 550,000 g / mol, compared to the total area of ​​the chromatogram.

[0059] In one aspect of the invention, the gpcBR index of the polyethylene is equal to or greater than 0.3 but less than 1, preferably equal to or greater than 0.3 but less than or equal to 0.7.

[0060] In one aspect of the invention, the SCB of the polyethylene logM2 / SCB logM1 SCB is preferred if it is greater than or equal to 0.7 but less than or equal to 1. logM2 / SCB logM1 The value is greater than or equal to 0.7 but less than 1, with the optimal value being greater than 0.7 but less than 1.

[0061] In one aspect of the invention, the SCB of the polyethylene logM1 For values ​​greater than 10 but less than 30, SCB is preferred. logM1 The optimal value is SCB if the value is greater than 10 but less than 25. logM1 Greater than 10 but less than 20.

[0062] In one aspect of the invention, the SCB of the polyethylene logM3 / SCB logM2 Greater than 1, SCB is preferred. logM3 / SCB logM2 Greater than 1 but less than or equal to 1.3.

[0063] In one aspect of the invention, the Mw1 / Mw2 of the polyethylene is less than 1, wherein Mw1 / Mw2 is the ratio of the weight-average molecular weight (Mw) of the first half of the temperature elution fractionation (TREF) curve from cross fractionation chromatography (CFC) to the weight-average molecular weight of the second half of the temperature elution fractionation curve, preferably Mw1 / Mw2 is greater than or equal to 0.5 but less than 1, and most preferably Mw1 / Mw2 is greater than or equal to 0.7 but less than or equal to 0.95.

[0064] In one aspect of the invention, the polyethylene has a Tw1-Tw2 of -16 to -38, wherein Tw1-Tw2 is the difference between the weight-average elution temperature (Tw) of the first half of the heating elution fractionation curve and the weight-average elution temperature of the second half of the heating elution fractionation curve, preferably Tw1-Tw2 is -20 to -35, and most preferably Tw1-Tw2 is -20 to -30.

[0065] In one aspect of the invention, the polyethylene exhibits multimodal characteristics in the elution curve of cross-fractional chromatography (CFC), including:

[0066] a) 10 to 30% by weight of a fraction eluted at a temperature below 60°C with a weight-average molecular weight of 40,000 to 120,000 g / mol, preferably with a weight-average molecular weight of 60,000 to 100,000 g / mol.

[0067] b) 50 to 80% by weight of a fraction eluted at a temperature range of 60 to 90°C with a weight-average molecular weight of 100,000 to 200,000 g / mol, preferably 120,000 to 160,000 g / mol; and

[0068] c) 5 to 25% by weight of a fraction eluted at temperatures above 90°C with a weight-average molecular weight of 100,000 to 200,000 g / mol, preferably 120,000 to 160,000 g / mol.

[0069] In one aspect of the invention, the polyethylene exhibits multimodal characteristics in the elution curve of cross-fractional chromatography (CFC), including:

[0070] a) 15 to 25% by weight of a fraction eluted at a temperature below 60°C with a weight-average molecular weight of 40,000 to 120,000 g / mol, preferably with a weight-average molecular weight of 60,000 to 100,000 g / mol.

[0071] b) 60 to 75% by weight of a fraction eluted at a temperature range of 60 to 90°C with a weight-average molecular weight of 100,000 to 200,000 g / mol, preferably 120,000 to 160,000 g / mol; and

[0072] c) 10 to 25% by weight of a fraction eluted at temperatures above 90°C with a weight-average molecular weight of 100,000 to 200,000 g / mol, preferably 120,000 to 160,000 g / mol.

[0073] In one aspect of the invention, the polyethylene has a T75-T25 of 20 to 30, wherein T75 and T25 are the temperatures at which 75% and 25% of the polymer are eluted from a thermal elution fractionation (TREF) analysis, respectively.

[0074] In one aspect of the invention, the composition distribution width index (CDBI) of the polyethylene is 35% to 55%, preferably 40% to 50%.

[0075] In one aspect of the invention, the polyethylene has a weight-average molecular weight (Mw) of 80,000 to 300,000 g / mol as analyzed by gel permeation chromatography (GPC), preferably 80,000 to 200,000 g / mol, and most preferably 100,000 to 200,000 g / mol.

[0076] In one aspect of the invention, the number-average molecular weight (Mn) of the polyethylene analyzed by gel permeation chromatography (GPC) is 15,000 to 35,000 g / mol, preferably 20,000 to 35,000 g / mol.

[0077] In one aspect of the invention, the polyethylene is analyzed by gel permeation chromatography (GPC) to determine its Z-average molecular weight (M). z The concentration is 300,000 to 600,000 g / mol, preferably 300,000 to 550,000 g / mol, and most preferably 350,000 to 500,000 g / mol.

[0078] In one aspect of the invention, the molecular weight distribution (Mw / Mn) or Mw / Mn of the polyethylene is 3 to 30, preferably 3 to 20, more preferably 3 to 15, and most preferably 3 to 10.

[0079] In one aspect of the invention, the ratio of the Z-average molecular weight to the number-average molecular weight (Mz / Mn) of the polyethylene is 5 to 40, preferably 5 to 30, and most preferably 10 to 20.

[0080] In one aspect of the invention, the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) of the polyethylene is 2 to 10, preferably 2 to 5.

[0081] In one aspect of the invention, the number of short-chain branches (SCB / 1000TC) per 1000 total carbon atoms of the polyethylene is 5 to 25, preferably 10 to 20.

[0082] In one aspect of the invention, the polyethylene has a polymer melt strength equal to or greater than 10 cN, preferably greater than 10 cN but less than 50 cN, more preferably greater than 10 cN but less than 30 cN, and most preferably greater than 10 cN but less than 25 cN.

[0083] In one aspect of the invention, the C3-C20 α-olefin comonomer is a C3-C10 α-olefin comonomer. Preferably, it is selected from 1-hexene, 1-octene, 1-decene, or a mixture of said α-olefin comonomers. Most preferably, the C3-C20 α-olefin comonomer is 1-hexene.

[0084] In one aspect of the invention, the amount of the C3-C20 α-olefin comonomer is 0.1 to 30% by weight, preferably 1 to 20% by weight, and most preferably 1 to 15% by weight.

[0085] In one aspect of the invention, the polyethylene is prepared by a polymerization process using a single reactor with a dual catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound.

[0086] In one aspect of the invention, the dual-catalyst system comprises a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound, the dual-catalyst system being supported on a co-support, wherein the co-support is selected from inorganic oxides, including oxides of Group 2, 3, 4, 5, 13, or 14 metals or magnesium chloride. Preferably, the inorganic oxide may be selected from, but is not limited to, silica, alumina, magnesium oxide, titanium dioxide, zirconium oxide, montmorillonite, zeolite, silica-chromium, silica-alumina, silica-titanium dioxide, silica-magnesium oxide, or mixtures thereof.

[0087] In one aspect of the invention, the Group IV transition metal is selected from hafnium, titanium, or zirconium, preferably titanium or zirconium.

[0088] In one aspect of the invention, the weight percentage of the bridged Group IV transition metal-based metallocene compound ranges from 20% to 80% relative to the total weight of the non-bridged Group IV transition metal-based metallocene compound and the bridged Group IV transition metal-based metallocene compound, preferably ranging from 40% to 80% relative to the total weight of the non-bridged Group IV transition metal-based metallocene compound and the bridged Group IV transition metal-based metallocene compound.

[0089] In one aspect of the invention, the non-bridged Group IV transition metal-based metallocene compound is a non-bridged Group IV transition metal-based metallocene compound between cyclopentadienyl ligands, as shown in Structure 1:

[0090]

[0091] The cyclopentadienyl ligands described therein may or may not have substituents.

[0092] The substituents R1, R2, R3, R4, R5, R'1, R'2, R'3, R'4, and R'5 are independently selected from, but not limited to, hydrogen or alkyl; or any two adjacent groups of the substituents R1, R2, R3, R4, R5, R'1, R'2, R'3, R'4, and R'5 are linked such that the atoms attached to them would form an aromatic ring with 6 carbon atoms, optionally wherein the aromatic ring is substituted by one or more groups, and if the remaining substituents R1, R2, R3, R4, R5, R'1, R'2, R'3, R'4, or R'5 are not linked together, then the remaining unlinked substituents are independently selected from hydrogen or alkyl; preferably, the substituents R1, R2, R3, R4, R5, R'1, R'2, R'3, R'4, and R'5 are independently selected from hydrogen or alkyl groups selected from methyl, ethyl, propyl, and butyl, and

[0093] M is a Group IV transition metal selected from hafnium, titanium, or zirconium, with titanium or zirconium being preferred.

[0094] In one aspect of the invention, the bridging group IV transition metal-based metallocene compound is selected from, but not limited to, group IV transition metal-based metallocene compounds bridging between cyclopentadienyl ligands or cyclopentadienyl ligands and nitrogen.

[0095] In one aspect of the invention, the bridged Group IV transition metal-based metallocene compound is a Group IV transition metal-based metallocene compound bridged between cyclopentadienyl ligands, as shown in Structure 2:

[0096]

[0097] The cyclopentadienyl ligands described therein may or may not have substituents.

[0098] The R1, R2, R3, and R4 substituents are independently selected from, but not limited to, hydrogen or alkyl groups; or any two adjacent groups of the R1, R2, R3, and R4 substituents are linked such that the atoms attached to them would form an aromatic ring having 6 carbon atoms, optionally wherein the aromatic ring is substituted by one or more groups, and if the remaining R1, R2, R3, or R4 substituents are not linked together, the remaining unlinked substituents are independently selected from hydrogen or alkyl groups; preferably, the R1, R2, R3, and R4 substituents are independently selected from hydrogen or alkyl groups selected from methyl, ethyl, propyl, and butyl.

[0099] The R'1, R'2, R'3, and R'4 substituents are independently selected, but not limited to, hydrogen or alkyl; or any two adjacent groups selected from the R'1, R'2, R'3, and R'4 substituents are linked such that the atoms attached to them would form an aromatic ring with 6 carbon atoms, optionally wherein the aromatic ring is substituted by one or more groups selected from hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, and if the remaining R'1, R'2, R'3, or R'4 substituents are not linked together, the remaining unlinked substituents are independently selected from hydrogen or alkyl; preferably, any two adjacent groups selected from the R'1, R'2, R'3, and R'4 substituents are linked such that the atoms attached to them would form an aromatic ring with 6 carbon atoms, wherein the aromatic ring is substituted by one or more groups selected from hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, most preferably, the aromatic ring is substituted by aralkyl, and the remaining unlinked R'1, R'2, R'3, or R'4 substituents are independently selected from hydrogen or alkyl.

[0100] Where M is a Group IV transition metal, selected from hafnium, titanium, or zirconium, preferably titanium or zirconium.

[0101] The X bridging site is selected from, but not limited to, carbon or silicon, preferably silicon, and

[0102] The R5 and R6 substituents at the bridging positions are selected from, but not limited to, hydrogen or alkyl groups, preferably from alkyl groups of methyl, ethyl, propyl or butyl.

[0103] In one aspect of the invention, the bridged Group IV transition metal-based metallocene compound is a Group IV transition metal-based metallocene compound bridged between a cyclopentadienyl ligand and nitrogen, as shown in Structure 3:

[0104]

[0105] The cyclopentadienyl ligands described therein may or may not have substituents.

[0106] The R1, R2, R3, and R4 substituents are independently selected from, but not limited to, hydrogen or alkyl groups; or any two adjacent groups selected from the R1, R2, R3, and R4 substituents are linked such that the atoms attached to them would form an aromatic ring having 6 carbon atoms, optionally wherein the aromatic ring is substituted by one or more groups, and if the remaining R1, R2, R3, or R4 substituents are not linked together, the remaining unlinked substituents are independently selected from hydrogen or alkyl groups; preferably, the R1, R2, R3, and R4 substituents are independently selected from hydrogen or alkyl groups selected from methyl, ethyl, propyl, and butyl.

[0107] The nitrogen may or may not have substituents.

[0108] The R' substituent is selected from, but not limited to, hydrogen, alkyl, cycloalkyl, aryl, or aralkyl groups, preferably from alkyl groups of methyl, ethyl, propyl, or butyl.

[0109] Where M is a Group IV transition metal, selected from hafnium, titanium, or zirconium, preferably titanium or zirconium.

[0110] The X bridging site is selected from, but not limited to, carbon or silicon, preferably silicon, and

[0111] The R5 and R6 substituents at the bridging positions are selected from, but not limited to, hydrogen or alkyl groups, preferably from alkyl groups of methyl, ethyl, propyl or butyl.

[0112] In one aspect of the invention, the dual-catalyst system may further include an activator. For example, the catalyst system may include an activator-support, an aluminoxane compound, an organoboron compound or organoborate compound, an ionized compound, or any combination thereof. The catalyst system may also include one or more activators.

[0113] In one aspect of the invention, the polymerization process is carried out in a gas-phase polymerization manner.

[0114] In one aspect of the invention, the polymerization process is carried out at a temperature of 60 to 100°C and a total pressure of 15 to 30 bar.

[0115] In one aspect of the invention, the polyethylene composition may further comprise additives selected from primary antioxidants, secondary antioxidants, processing aids, nucleating agents, acid scavengers, plasticizers, stabilizers, corrosion inhibitors, foaming agents, ultraviolet absorbers, quenchers, antistatic agents, slip agents, pigments, dyes and fillers, curing agents, or any combination thereof. These additives, along with other general additives used in the polyolefin industry, are present in the polyethylene composition in an amount of 0.01 to 50% by weight, preferably 0.1 to 20% by weight, and most preferably 1 to 5% by weight.

[0116] Specifically, the primary antioxidant, the secondary antioxidant, the processing aid, or a mixture thereof may be present in the polyethylene composition in an amount of 0.001 to 5% by weight, preferably 0.02 to 5% by weight.

[0117] In one aspect of the invention, the polyethylene composition may be further processed by any suitable method selected from, but not limited to, calendering, casting, coating, compounding, extrusion, foaming; all forms of molding, including compression molding, injection molding, blow molding, rotational molding, and transfer molding; blown film or cast film and all methods of film formation, such as uniaxial or biaxial orientation; thermoforming, including formation by lamination, pultrusion, extrusion, stretch compression, spunbond, melt spinning, meltblowing, and other forms of fibrous and nonwoven fabrics, and combinations thereof.

[0118] In one aspect of the invention, the polyethylene composition and mixtures or blends thereof can be used in molding operations, such as extrusion and co-extrusion of films, sheets, and fibers, including blow molding, injection molding, and rotational molding. Films include blown or cast films formed by co-forming or lamination, which can be used as shrink films, food wraps, stretch films, sealing films, oriented films, snack packaging, heavy-duty bags, grocery bags, baked and frozen food packaging, medical packaging, industrial linings, membranes, and other applications involving contact with food and non-food items. Fibers include melt spinning, solution spinning, and meltblown fiber operations for the preparation of filters, diapers, medical clothing, geotextiles, etc., in woven or non-woven forms. Extruded articles include medical tubing, wire and cable coatings, pipes, geomembranes, and pond liners. Molded articles include single-layer and multi-layer structures in the form of bottles, cans, large hollow products, rigid food containers, and toys.

[0119] In another embodiment, the present invention relates to articles prepared from the polyethylene composition described above. Preferably, the article is a film.

[0120] In one aspect of the invention, the tensile modulus of the membrane in the machine direction is 200 MPa or greater, preferably 250 MPa or greater. The tensile modulus of the membrane in the transverse direction is 200 MPa or greater, preferably 250 MPa or greater.

[0121] In one aspect of the invention, the membrane has a longitudinal tensile strength of 25 MPa or greater, preferably 30 MPa or greater. The membrane has a transverse tensile strength of 20 MPa or greater, preferably 25 MPa or greater.

[0122] In one aspect of the invention, the membrane has a longitudinal elongation at break of 700% or greater, preferably 800% or greater, and most preferably 900% or greater. The membrane has a transverse elongation at break of 600% or greater, preferably 700% or greater.

[0123] In one aspect of the invention, the membrane has an Elmendorf tear strength of 400 g-forces (gf) or greater in the longitudinal direction, preferably 500 g-forces or greater. The membrane has an Elmendorf tear strength of 600 g-forces or greater in the transverse direction, preferably 650 g-forces or greater.

[0124] In one aspect of the invention, the membrane has a puncture resistance of 60N or greater, preferably 70N or greater, and most preferably 80N or greater.

[0125] Definitions and measurement methods

[0126] -density

[0127] The density in this invention refers to the density of polyethylene, which is measured at 23°C using the water displacement method according to ASTM D792 (Method A).

[0128] - Melt flow rate (MFR or MI)

[0129] The melt flow rate in this invention refers to the melt flow rate of polyethylene, which is used to determine the melt flowability of the polymer under test conditions of 190°C and a load of 2.16 kg. The melt flow rate is determined according to ASTM D1238 using a melt flow indexer (MI-4). )Measurement.

[0130] - Comonomer content

[0131] The comonomer content in this invention is determined by high resolution. 13 C nuclear magnetic resonance (C 13 Comonomer content analyzed by C-NMR spectroscopy. 13 C-NMR spectra were recorded using a Bruker 500Hz NMR spectrometer (AVANCE IIIHD) with a broadband observation probe. Samples were prepared by dissolving polymer samples in tritium-modified 1,1,2,2-tetrachloroethane-d2 as a solvent at 130°C.

[0132] Gel permeation chromatography (GPC)

[0133] The gel permeation chromatography procedure was as follows: The sample was dissolved in 1,2,4-trichlorobenzene (TCB) containing 300 ppm butylated hydroxytoluene (BHT) at 160 °C for 60 minutes to prepare a polymer solution of approximately 1 mg / mL. Then, 200 mg of the sample solution was injected into a high-temperature gel permeation chromatograph equipped with three detectors (3D-GPC, Polymer Char, SA, Valencia, Spain): an infrared detector (IR5), a viscometer, and a multi-angle light scattering detector (Wyatt Technology). A 3PL gel Olexis column (Agilent) was used at a flow rate of 1 mL / min, a column temperature of 160 °C, and a detector temperature of 160 °C. Data were obtained via GPC. Software (Polymer Char) processing.

[0134] - Molecular weight and molecular weight distribution (MWD)

[0135] Number average molecular weight (M n ), weight-average molecular weight (M w ) and Z-average molecular weight (M z ) was analyzed by gel permeation chromatography (GPC) as described in the section on gel permeation chromatography (GPC).

[0136] The molecular weight distribution (MWD) according to the present invention is expressed by weight-average molecular weight (M w Divide by the number-average molecular weight (M) n The molecular weight distribution was calculated.

[0137] - Deconvolution methods for chromatograms in gel permeation chromatography

[0138] Chromatograms obtained by gel permeation chromatography were deconvolved using a Schulz-Flory distribution after deconvolution of the molecular weight distribution. This method can identify catalyst behavior during polymerization. However, it may not be able to identify the actual number of active sites on the catalyst.

[0139] The research paper by Abdulaziz A. Alghyamah et al. (Macromolecular Rapid Communications, 2009, 30(4-5), 384-393) has described the aforementioned deconvolution method for determining the relevant weight percentage (wt%) of each component of polyethylene using the weight ratio of each component, and for determining the relevant weight-average molecular weight (Mb) using mathematical calculations of the molecular weight distribution in the form of the Schulz-Flory distribution. w ) and number-average molecular weight (M n The method fixes the polydispersity index (PDI), which represents the width of the molecular weight distribution, to 2 theoretically for a single-point catalyst, and sets the average molar mass (Mi) of the repeating unit of polyethylene as the average molar mass. 平均 The value is fixed at 28.

[0140] - Short Chain Branching (SCB) and Short Chain Branching Distribution (SCBD)

[0141] The determination of the number of short-chain branches per 1000 total carbon atoms is expressed as SCB / 1000TC in the molecular weight distribution. In this determination, it is assumed that each chain is linear and that each chain is terminally capped with a methyl group; the number of short-chain branches is corrected by subtracting the terminal methyl groups. The number of short-chain branches was analyzed by gel permeation chromatography (GPC) equipped with an infrared detector (IR5, Polymer Char, SA, Valencia, Spain). The analytical method for the number of short-chain branches has been disclosed in the research paper of A. Ortín et al. (Macromolecular Symposia, 2013, 330, 63-80). https: / / onlinelibrary.wiley.com / authored-by / Ort%C3%ADn / A.

[0142] -gpcBR index

[0143] The gpcBR index in this invention is used for high-precision identification of the branching level of polymers. The gpcBR index of linear polymers will be close to zero, while branched polymers will have a gpcBR index greater than 0. In fact, the gpcBR index shows the fractional change in intrinsic viscosity ([η]) due to the molecular size shrinkage effect caused by polymer branching. The gpcBR index measures the branching level of the polymer by combining intrinsic viscosity and absolute MW measured by a viscometer and a light scattering (LS) detector. Analysis of the gpcBR index has been disclosed in patent document EP3176213A1. The gpcBR index can be calculated using the following formula:

[0144]

[0145] Among them, M W,CC M V,CC and [η] CC These are weight-average molecular weight, viscosity-average molecular weight, and intrinsic viscosity, calculated using conventional gel permeation chromatography (GPC) under the assumption that the polymer is linear and free of long-chain branches (LCB). [η] is the actual intrinsic viscosity, calculated using the viscometer peak area method and measured by an online viscometer. W The absolute molecular weights are weight-averaged values ​​obtained through a light scattering (LS) detector and calculated using the LS peak area method. At 160°C, the Mark–Houwink–Sakurada coefficients α and K for polyethylene in 1,2,4-trichlorobenzene (TCB) are 0.725 and 0.0004416, respectively.

[0146] - Cross-fractionation chromatography (CFC)

[0147] Cross-fraction chromatography was performed using a cross-fraction chromatograph (SA, Valencia, Spain). The technique employed a combination of gel permeation chromatography (GPC) and temperature elution fractionation (TREF). The analytical methods have been disclosed in the research paper of Alberto Ortin et al. (Macromolecular Symposia, 2007, 257, 13–28).

[0148] The analysis was performed by dissolving the sample in 1,2,4-trichlorobenzene (TCB) containing 300 ppm butylated hydroxytoluene (BHT) at 160 °C for 60 minutes to prepare a polymer solution with a concentration of approximately 4 mg / mL. A 0.5 mL solution containing 2 mg of polymer was packed into the center of a TREF column. The TREF column temperature was lowered and maintained at approximately 100 °C for 45 minutes. The TREF column was then slowly cooled at a decreasing rate of 0.2 °C / min until the temperature reached 30 °C. The temperature was then maintained at 30 °C for 30 minutes, and the soluble fractions were injected into a high-temperature gel permeation chromatography column equipped with an infrared detector (IR5, Polymer Char, SA, Valencia, Spain), using a 3PLgel Olexis column (Agilent), a flow rate of 1 mL / min, a column temperature of 160 °C, and a detector temperature of 160 °C. The TREF column temperature was then incrementally increased to the fraction set point to analyze the molecular weight of each fraction at temperatures increased to 120 °C. Data were analyzed by GPC. Software (Polymer Char) processing.

[0149] As shown in Table 4, the weight-average elution temperature and the weight-average molecular weight of the aggregates for the three temperature ranges (temperatures below 60°C, temperatures from 60 to 90°C, and temperatures above 90°C) were calculated according to the conventional definition of weight-average molecular weight, with fractions less than 0.5% by weight not included in the calculation.

[0150] Weight-average elution temperature (T) of polymers in individual fractions or fraction aggregates w The calculation of ) can be performed using the following equation:

[0151]

[0152] Among them, T i It is the elution temperature of each eluted fraction, W i It is the normalized weight of each eluted fraction.

[0153] The weight-average molecular weight (M) of a polymer in a single fraction or fraction aggregate w The calculation of ) can be performed using the following equation:

[0154]

[0155] Among them, M wi W is the weight-average molecular weight of each eluted fraction. i It is the normalized weight of each eluted fraction.

[0156] -Tw1, Tw2, Mw1 and Mw2

[0157] Tw1, Tw2, Mw1, and Mw2 were calculated from the analytical results of cross-fractional chromatography. The calculation methods for Tw1, Tw2, Mw1, and Mw2 have been disclosed in patent document WO2019108314A1.

[0158] Mw1 / Mw2 is the weight-average molecular weight (Mw1 / Mw2) from the first half of the temperature elution fractionation (TREF) curve obtained from cross-fraction chromatography (CFC) analysis. w The ratio of the weight-average molecular weight to the weight-average molecular weight in the latter half of the temperature-elution fractionation curve.

[0159] Tw1-Tw2 is the difference between the weight-averaged elution temperature (Tw) in the first half of the temperature-elution fractionation curve and the weight-averaged elution temperature in the second half of the temperature-elution fractionation curve.

[0160] - Composition Distribution Width Index (CDBI)

[0161] The composition distribution width index (CDBI) is analyzed using a temperature elution fractionation (TREF) instrument, wherein the method for analyzing the CDBI value is known to those skilled in the art, for example, as disclosed in patent document WO1993003093A1.

[0162] -T 75 T 50 and T 25

[0163] T 75 T 50 and T 25 The values ​​represent the temperatures at which 75%, 50%, and 25% of the polymer were eluted, respectively, and were analyzed using thermal elution fractionation (TREF) technology. 75 -T 25 This indicates the uniformity of the compositional distribution analyzed using the above-described techniques. The analysis and calculation methods are disclosed in patent document WO2009109367A1.

[0164] -Polymer melt strength

[0165] The polymer melt strength at 190°C was determined using a capillary rheometer (Rosand RH7, NETZSCH), wherein the molten polymer was extruded through a capillary die at a constant speed of 10 mm / min, the die having dimensions of 2 mm x 20 mm x 180 degrees.

[0166] -Shear viscosity

[0167] The shear viscosity as a function of shear rate was measured at 190°C using a capillary rheometer (Rosand RH7, NETZSCH), in which molten polymer was extruded through a capillary die with die dimensions of 1 mm x 16 mm x 180 degrees.

[0168] - Monolayer film preparation

[0169] A blown film machine (COLLIN) was used to prepare a single-layer film or a single-layer film with a thickness of 50 μm, wherein the ratio of the bubble diameter to the die diameter or the blow-up ratio of the blown film machine was 2.5:1, and the output was 1.62 kg / hour.

[0170] -Tension modulus

[0171] According to ASTM D882-12, the tensile modulus of blown film in the longitudinal (MD) and transverse (TD) directions is tested using a universal testing machine (UTM).

[0172] - Tensile strength at break

[0173] According to ASTM D882-12, the tensile strength at break of blown film in the longitudinal (MD) and transverse (TD) directions is tested using a universal testing machine (UTM) at a crosshead speed of 500 mm / min, a gauge length of 50 mm, at 23±2℃ and 50±5% relative humidity.

[0174] -Elongation at break

[0175] According to ASTM D882-12, the elongation at break of blown film in the longitudinal (MD) and transverse (TD) directions is tested using a universal testing machine (UTM).

[0176] -Elmendorf tear strength

[0177] Elmendorf tear strength of blown film in longitudinal (MD) and transverse (TD) directions is tested according to ASTM D1922 (83-76-10, TMI).

[0178] - Puncture resistance

[0179] According to ASTM D5748, the puncture resistance of blown film was tested using a universal testing machine (UTM) at a speed of 250 mm / min, a temperature of 23±2℃, and a relative humidity of 50±5%.

[0180] The following examples are only used to illustrate one aspect of the present invention and are not intended to limit the scope of the present invention in any way.

[0181] Sample according to invention 1

[0182] According to the present invention 1, the sample is a polyethylene composition comprising polyethylene, said polyethylene being prepared by a gas-phase polymerization process using a single reactor with a dual catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound as shown in Structure 1 and a bridged Group IV transition metal-based metallocene compound as shown in Structure 2, wherein both metallocene compounds are supported on a silica co-support. The polymerization conditions are as follows: a temperature of 60 to 100°C, a total pressure of 18 to 27 bar, a 1-hexene to ethylene weight ratio (C6 / C2) of about 0.1 g / g, a hydrogen to ethylene weight ratio (H2 / C2) of about 0.000006 g / g, and a reaction time of 60 to 120 minutes.

[0183] Sample according to invention 2

[0184] According to the present invention 2, the sample is a polyethylene composition containing polyethylene, which is prepared by the same gas-phase polymerization process and polymerization conditions as the sample according to the present invention 1 using a single reactor with a dual catalyst system, except that the weight ratio of 1-hexene to ethylene (C6 / C2) is about 0.1 (g / g) and the weight ratio of hydrogen to ethylene (H2 / C2) is about 0.000008 (g / g).

[0185] Sample according to invention 3

[0186] According to the present invention 3, the sample is a polyethylene composition containing polyethylene, which is prepared by the same gas-phase polymerization process and polymerization conditions as the sample according to the present invention 1 using a single reactor with a dual catalyst system, except that the weight ratio of 1-hexene to ethylene (C6 / C2) is about 0.08 (g / g) and the weight ratio of hydrogen to ethylene (H2 / C2) is about 0.00002 (g / g).

[0187] Comparison Sample 1

[0188] Comparative Sample 1 is a polyethylene composition containing polyethylene, which is prepared by gas-phase polymerization in a single reactor using a non-bridged Group IV transition metal-based metallocene compound, as shown in Structure 1, supported on a silica carrier. The polymerization conditions were the same as those used for the sample according to Embodiment 1.

[0189] Comparison Sample 2

[0190] Comparative sample 2 is a polyethylene composition containing polyethylene, which is prepared by gas-phase polymerization in a single reactor using a group IV transition metal-based metallocene compound with bridging as shown in structure 2 supported on a silica carrier. The polymerization conditions were the same as those used for the sample according to invention 1.

[0191] Comparison samples 3 to 6

[0192] Comparative samples 3 to 6 are commercially available polyethylene compositions known in the field of membrane preparation. These polyethylene compositions are prepared using a gas-phase polymerization process with 1-hexene as a comonomer.

[0193] These samples can be used for comparison with the polymers of the present invention in terms of properties, performance, and applications.

[0194]

[0195]

[0196]

[0197]

[0198]

[0199] As shown in Table 1, the sample according to the present invention has a higher gpcBR index than the control sample, indicating a higher level of branching. Considering the Tw1-Tw2 values, a broad chemical composition distribution (CCD) is observed. Figures 1 to 3When comparing the chromatograms and short-chain branching distributions obtained by gel permeation chromatography in Tables 2 to 4, it was found that the samples according to the invention have a high molecular weight component with higher comonomer incorporation and a higher proportion of short-chain branches within the high molecular weight component. Compared with comparative samples 1 and 2, including comparative samples 3 and 4, prepared from catalyst systems containing non-bridging Group IV transition metal-based metallocene compounds and bridged Group IV transition metal-based metallocene compounds respectively, it was found that the samples according to the invention exhibit a significantly higher molecular weight component with higher comonomer incorporation than comparative samples 1 to 4. When compared with comparative samples 5 and 6, the characteristics of the short-chain branching distribution were found to be different. The samples according to the invention exhibit a unique short-chain branching distribution in which the low molecular weight component has higher comonomer incorporation, and in gel permeation chromatography (GPC-IR) analysis with an infrared detector, the number of short-chain branches tends to decrease in the logarithmic range of molecular weight at 5, while comparative samples 5 and 6 exhibit low molecular weight components with low comonomer incorporation. Figures 4 to 6 The cross fractionation chromatography (CFC) analysis shown in Table 5 illustrates the differences in properties of the polymer compositions eluted at various temperature ranges.

[0200] As shown in Table 1, Figure 3 and Figure 7 As shown, compared to the comparative sample, the sample according to the invention exhibits significantly improved polymer melt strength and also displays better shear sensitivity behavior. This indicates improved processing properties of polyethylene. Table 6 shows the properties of film articles prepared from the sample according to the invention and the comparative sample, revealing that the film prepared from the sample according to the invention exhibits significantly higher puncture resistance and longitudinal elongation at break than the comparative sample. This also includes a higher longitudinal tensile modulus than the comparative sample. That is, the sample according to the invention also exhibits improved mechanical properties. This indicates that the sample according to the invention achieves an excellent balance between processing properties and mechanical properties. As shown in the invention, the synergistic behavior of the dual-catalyst system allows for the preparation of this polymer using only a single polymerization reactor, resulting in polymers characterized by molecular weight distribution and short-chain branching distribution.

[0201] The best mode or preferred embodiment of the present invention

[0202] The best mode or preferred embodiment of the present invention is as provided in the specification of the present invention.

Claims

1. A polyethylene composition comprising polyethylene, said polyethylene comprising ethylene monomer and 0.1 to 35% by weight of C3-C20 α-olefin comonomer, wherein said polyethylene has the following properties: - Density ranges from 0.910 to 0.935 g / cm³ 3 ; - Melt flow rate (MFR) ranges from 0.1 to 100 g / 10 min (measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg); - Molecular weight distribution (Mw / Mn) is 3 to 50; - The gpcBR index is equal to or greater than 0.3; - Chromatograms obtained by gel permeation chromatography (GPC) exhibit multimodal characteristics, wherein the chromatograms undergo deconvolution using a Schulz-Flory distribution and include: a) 30% to 55% of the first component having a weight-average molecular weight (Mw) of 20,000 to 75,000 g / mol compared to the total area of ​​the chromatogram; b) 35% to 55% of the second component having a weight-average molecular weight (Mw) of 80,000 to 200,000 g / mol compared to the total area of ​​the chromatogram; and c) 5% to 20% of the third component having a weight-average molecular weight (Mw) of 300,000 to 800,000 g / mol, compared to the total area of ​​the chromatogram; and -SCB logM2 / SCB logM1 Equal to or less than 1, SCB logM1 Greater than 10, and SCB logM3 / SCB logM2 Greater than or equal to 1, where SCB logM1 The number of short-chain branches (SCB) per 1000 total carbon atoms in polyethylene is measured using logM1. logM2 This is the number of short-chain branches per 1000 total carbon atoms in polyethylene, measured as logM2, and the SCB. logM3 LogM3 is the number of short-chain branches per 1000 total carbon atoms in polyethylene, where logM1, logM2, and logM3 are the logarithms of molecular weights of 4, 5, and 5.5, respectively, in gel permeation chromatography (GPC-IR) analysis with an infrared detector.

2. The polyethylene composition according to claim 1, wherein the melt flow rate of the polyethylene is in the range of 0.1 to 50 g / 10 min.

3. The polyethylene composition according to claim 1, wherein the polyethylene has a molecular weight distribution of 3 to 30.

4. The polyethylene composition according to claim 1, wherein the gpcBR index of the polyethylene is equal to or greater than 0.3 but less than 1.

5. The polyethylene composition according to claim 4, wherein the gpcBR index of the polyethylene is equal to or greater than 0.3 but less than or equal to 0.

7.

6. The polyethylene composition according to claim 1, wherein the SCB of the polyethylene logM2 / SCB logM1 Greater than or equal to 0.7 but less than or equal to 1.

7. The polyethylene composition according to claim 6, wherein the SCB of the polyethylene logM2 / SCB logM1 Greater than or equal to 0.7 but less than 1.

8. The polyethylene composition according to claim 1, wherein the SCB of the polyethylene logM1 Greater than 10 but less than 30.

9. The polyethylene composition according to claim 1, wherein the SCB of the polyethylene logM3 / SCB logM2 Greater than 1.

10. The polyethylene composition according to claim 9, wherein the SCB of the polyethylene logM3 / SCB logM2 Greater than 1 but less than or equal to 1.

3.

11. The polyethylene composition according to claim 1, wherein the Mw1 / Mw2 of the polyethylene is less than 1, wherein Mw1 / Mw2 is the ratio of the weight-average molecular weight (Mw) of the first half of the temperature elution fractionation (TREF) curve from cross fractionation chromatography (CFC) analysis to the weight-average molecular weight of the second half of the temperature elution fractionation curve.

12. The polyethylene composition according to claim 1, wherein the Tw1-Tw2 of the polyethylene is -16 to -38, wherein Tw1-Tw2 is the difference between the weight-average elution temperature (Tw) of the first half of the heating elution fractionation curve and the weight-average elution temperature of the second half of the heating elution fractionation curve.

13. The polyethylene composition of claim 1, wherein the polyethylene exhibits multimodal characteristics in the elution curve of cross-fractional chromatography (CFC) analysis, comprising: a) 10 to 30% by weight of the fraction eluted at temperatures below 60°C with a weight-average molecular weight of 40,000 to 120,000 g / mol. b) 50 to 80% by weight of the fraction eluted at temperatures ranging from 60 to 90°C, with a weight-average molecular weight of 100,000 to 200,000 g / mol; and c) 5 to 25% by weight of the fraction eluted at temperatures above 90°C with a weight-average molecular weight of 100,000 to 200,000 g / mol.

14. The polyethylene composition according to claim 1, wherein the polyethylene has a T 75 -T 25 It is between 20 and 30, where T 75 and T 25 These are the temperatures at which 75% and 25% of the polymer were eluted from the thermal elution fractionation (TREF) analysis, respectively.

15. The polyethylene composition according to claim 1, wherein the composition distribution width index (CDBI) of the polyethylene is 35 to 55%.

16. The polyethylene composition of claim 1, wherein the polyethylene has a Z-average molecular weight (M) as analyzed by gel permeation chromatography (GPC). z The concentration ranges from 300,000 to 600,000 g / mol.

17. The polyethylene composition according to claim 1, wherein the ratio of the Z-average molecular weight to the number-average molecular weight (Mz / Mn) of the polyethylene ranges from 5 to 40.

18. The polyethylene composition according to claim 1, wherein the ratio of Z-average molecular weight to weight-average molecular weight (Mz / Mw) of the polyethylene ranges from 2 to 10.

19. The polyethylene composition according to claim 1, wherein the polymer melt strength of the polyethylene is equal to or greater than 10 cN.

20. The polyethylene composition according to claim 1, wherein the C3-C20 α-olefin comonomer is selected from 1-hexene, 1-octene, 1-decene, or a mixture of the α-olefin comonomers.

21. The polyethylene composition according to claim 20, wherein the C3-C20 α-olefin comonomer is 1-hexene.

22. The polyethylene composition of claim 1, wherein the polyethylene is prepared by a polymerization process using a single reactor having a dual catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound.

23. The polyethylene composition of claim 22, wherein the dual catalyst system comprising a non-bridged Group IV transition metal-based metallocene compound and a bridged Group IV transition metal-based metallocene compound is supported on a co-support.

24. The polyethylene composition of claim 23, wherein the co-carrier is selected from magnesium chloride, silicon dioxide, aluminum oxide, magnesium oxide, titanium dioxide, zirconium oxide, montmorillonite, zeolite, silicon dioxide-chromium, silicon dioxide-alumina, silicon dioxide-titanium dioxide, silicon dioxide-magnesium oxide, or mixtures thereof.

25. The polyethylene composition of claim 22, wherein the Group IV transition metal is selected from hafnium, titanium or zirconium.

26. The polyethylene composition of claim 22, wherein the weight percentage of the bridged group IV transition metal-based metallocene compound ranges from 20% to 80% relative to the total weight of the non-bridged group IV transition metal-based metallocene compound and the bridged group IV transition metal-based metallocene compound.

27. The polyethylene composition of claim 26, wherein the weight percentage of the bridged group IV transition metal-based metallocene compound ranges from 40% to 80% relative to the total weight of the non-bridged group IV transition metal-based metallocene compound and the bridged group IV transition metal-based metallocene compound.

28. The polyethylene composition of claim 22, wherein the non-bridging group IV transition metal-based metallocene compound is a non-bridging group IV transition metal-based metallocene compound between cyclopentadienyl ligands.

29. The polyethylene composition of claim 28, wherein the cyclopentadienyl ligand has substituents independently selected from hydrogen or alkyl groups.

30. The polyethylene composition of claim 22, wherein the bridging group IV transition metal-based metallocene compound is selected from group IV transition metal-based metallocene compounds bridging between cyclopentadienyl ligands or cyclopentadienyl ligands and nitrogen.

31. The polyethylene composition of claim 30, wherein the bridging group IV transition metal-based metallocene compound is selected from group IV transition metal-based metallocene compounds bridged between cyclopentadienyl ligands.

32. The polyethylene composition of claim 31, wherein the bridging group IV transition metal-based metallocene compound between the cyclopentadienyl ligand and the cyclopentadienyl ligand is a bridging group IV transition metal-based metallocene compound between the cyclopentadienyl ligand (wherein the cyclopentadienyl ligand has substituents independently selected from hydrogen or alkyl) and the cyclopentadienyl ligand (wherein the cyclopentadienyl ligand has substituents, wherein any two adjacent groups of the substituents are linked such that the atoms connected to them would form an aromatic ring having 6 carbon atoms, optionally wherein the aromatic ring is substituted by one or more groups).

33. The polyethylene composition according to claim 31 or 32, wherein the bridging group IV transition metal-based metallocene compound between the cyclopentadienyl ligand and the cyclopentadienyl ligand is a bridging group IV transition metal-based metallocene compound between a cyclopentadienyl ligand (where the cyclopentadienyl ligand has substituents independently selected from hydrogen or alkyl) and a cyclopentadienyl ligand (where the cyclopentadienyl ligand has substituents, wherein any two adjacent substituents are linked such that the atoms connected to them form an aromatic ring having 6 carbon atoms, wherein the aromatic ring is substituted by one or more groups selected from hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, and the remaining unconnected substituents are independently selected from hydrogen or alkyl).

34. The polyethylene composition according to any one of claims 30 to 33, wherein the bridging position of the bridging group IV transition metal-based metallocene compound is selected from carbon or silicon, and the bridging position has a substituent selected from hydrogen or alkyl.

35. The polyethylene composition of claim 22, wherein the polymerization process is carried out by gas-phase polymerization.

36. An article prepared from a polyethylene composition according to any one of the preceding claims, wherein the article is a film.

37. The article of claim 36, wherein the tensile modulus of the membrane in the longitudinal direction is 200 MPa or greater.

38. The article of claim 36, wherein the film has a breaking elongation of 700% or greater in the longitudinal direction.

39. The article of claim 36, wherein the membrane has a puncture resistance of 60N or greater.

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