Polyethylene for making fibers and process for preparing the same

Abstract

The present disclosure relates to a polyethylene suitable for the preparation of fibers having improved yellowness index and filterability in the spinning process by increasing the aging lifetime of the polyethylene and a process for the preparation thereof.

Description

[0001] This application is a divisional application of the invention patent application with application number 202280014008.6 (international application number: PCT / KR2022 / 002424), application date February 18, 2022, entitled "Polyethylene for Preparing Fibers and a Method Thereof". Cross-reference to related applications

[0002] This application claims the rights to Korean Patent Application No. 10-2021-0022711, filed with the Korean Intellectual Property Office on February 19, 2021, and No. 10-2022-0020900, filed on February 17, 2022, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a polyethylene suitable for preparing fibers and a method thereof, wherein the fibers have an improved yellow index and filterability in spinning processes by increasing aging life. Background Technology

[0004] To produce high-toughness fibers such as ropes and fishing nets, high-density polyethylene is used, and high-density polyethylene is required to have properties such as high tensile strength and high toughness.

[0005] In fiber products, it is known that the narrower the molecular weight distribution of high-density polyethylene (HDPE), the better its mechanical properties. That is, if HDPE has a narrow molecular weight distribution, it has a high elongation ratio, and due to this high elongation, it can possess high toughness. However, if the molecular weight distribution of HDPE is too narrow, its filtration properties may deteriorate.

[0006] The olefin polymerization catalyst systems used to prepare such high-density polyethylene or linear low-density polyethylene can be divided into Ziegler-Natta catalyst systems and metallocene catalyst systems, which are developed based on their respective characteristics.

[0007] Meanwhile, in the process of preparing polyethylene using commercially available Ziegler-Natta catalysts, it is difficult to obtain polymers with uniform molecular weight and a wide molecular weight distribution.

[0008] While polyethylene with a wide molecular weight distribution has good filtration properties, its disadvantages include deteriorated mechanical properties and the elution of low molecular weight fractions during processing, which reduces the original properties of the resin.

[0009] To address these issues, a method for preparing polyethylene with a narrow molecular weight distribution using a metallocene catalyst system has been proposed. However, for application in existing commercial processes such as slurry and gas-phase processes, metallocenes should be supported on a suitable support, but currently used supported metallocene catalysts suffer from drawbacks such as broadened molecular weight distribution and reduced catalytic activity.

[0010] In particular, the Ziegler-Natta catalyst system, which uses titanium tetrachloride (TiCl4) as the polymerization active site, is widely used in the preparation of high-density polyethylene or linear low-density polyethylene. The polymer obtained from this catalyst, namely polyethylene, contains residues of halogen compounds (such as HCl) that are components of the catalyst. This can cause corrosion of metallic materials such as molding machines and promote the decomposition reaction of polyethylene, becoming the main cause of discoloration.

[0011] A conventional technique to address this problem is to add a neutralizing agent (acid scavenger) during the extrusion process to react with catalyst residues [Holzner, A. and Chmil, K., Acid Scavenger, Plastic additives handbook, Zweifel, H., and Maier, R. (Eds.), 6th edition, Hanser: Munich, 2009]. The most commonly used additive in this case is a metal stearate (e.g., calcium stearate). However, when using polyethylene obtained in this way to manufacture low-denier (fine) fibers, a disadvantage exists: yarn breakage occurs during the spinning process due to the metallic inorganic material. Additionally, to prevent yarn breakage, a mesh filter is installed at the bottom of the extruder die during the fiber spinning process to remove the metallic inorganic material and other foreign matter. In this case, if the filter pressure increases due to foreign matter, the filter replacement cycle may be shortened, thereby reducing process yield.

[0012] Therefore, in order to overcome the above-mentioned shortcomings, there is a continued need to develop a polyethylene resin composition that, by improving the aging life of polyethylene, is suitable for preparing fibers or nonwoven fabrics with enhanced yellow index and filtration properties in spinning processes. Summary of the Invention

[0013] [Technical Issues] In this disclosure, a polyethylene is provided that is suitable for preparing fibers with an improved yellow index and enhanced filtration properties in spinning processes.

[0014] In addition, a method for preparing the polyethylene used to prepare fibers described above is also provided.

[0015] In addition, a spunbond nonwoven fabric formed from the aforementioned polyethylene fibers is also provided.

[0016] [Technical Solution] According to one embodiment of this disclosure, a polyethylene is provided that satisfies the following conditions: a melt index (ASTM D 1238, 190°C, 2.16 kg) of 15 g / 10 min to 40 g / 10 min, and a melt flow rate ratio (MFRR, MI5 / MI5). 2.16 The content of alkaline earth metals and transition metals measured by inductively coupled plasma (ICP) spectroscopy is less than 3, the content of halogens measured by combustion ion chromatography (IC) is less than 0.8 ppm, and the content of halogens measured by combustion ion chromatography (IC) is less than 5 ppm.

[0017] In addition, a method for preparing the polyethylene used to prepare fibers described above is also provided.

[0018] In addition, a spunbond nonwoven fabric formed from the aforementioned polyethylene fibers is also provided.

[0019] [Beneficial Effects] According to this disclosure, by improving the aging life of polyethylene, fibers or nonwoven fabrics with enhanced yellowness index and filtration properties in spinning processes can be provided. Detailed Implementation

[0020] In this disclosure, the terms “first,” “second,” etc., are used to describe different components, and these terms are used only to distinguish one component from other components.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. In this disclosure, the terms “comprising,” “including,” or “having” are used to describe the expressed features, numbers, steps, components, or combinations thereof, and do not exclude the addition of one or more other features, numbers, steps, components, or combinations thereof.

[0022] The terms “approximately” or “substantially” are intended to mean approximating the specified value or range with permissible error, and are intended to prevent the accurate or absolute values ​​disclosed for the purpose of understanding the invention from being used illegally or unfairly by any unethical third party.

[0023] Furthermore, the term "parts by weight" as used herein refers to a relative concept of the weight ratio of the remaining material to the weight of a specific material. For example, in a mixture containing 50 g of material A, 20 g of material B, and 30 g of material C, based on 100 parts by weight of material A, the amounts of materials B and C are 40 parts by weight and 60 parts by weight, respectively.

[0024] Additionally, "wt% (weight %)" refers to an absolute concept 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 50 wt%, 20 wt%, and 30 wt%, respectively. At this point, the sum of the contents of each component does not exceed 100 wt%.

[0025] Since the present invention can be modified in various ways and has various forms, specific embodiments thereof are shown by way of example and will be 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, or substitutions within the spirit and scope of the invention.

[0026] The present invention will now be described in detail.

[0027] According to one embodiment of this disclosure, a polyethylene suitable for preparing fibers with an improved yellow index and enhanced filtration properties in spinning processes is provided.

[0028] Specifically, the polyethylene disclosed herein meets the following conditions: melt index (ASTM D 1238, 190°C, 2.16 kg) of 15 g / 10 min to 40 g / 10 min, and melt flow rate ratio (MFRR, MI5 / MI5). 2.16 The content of alkaline earth metals and transition metals measured by inductively coupled plasma (ICP) spectrophotometry is less than 3, and the content of halogens measured by combustion ion chromatography (IC) is less than 5 ppm.

[0029] In particular, the polyethylene (as will be described later) fundamentally blocks halogen compounds in the polyethylene by using a specific metallocene catalyst, thereby increasing the yellow index when preparing bicomponent fibers and enhancing the filtration properties in the spinning process.

[0030] Specifically, polyethylene may have a melt index of 16 g / 10 min or more, 17 g / 10 min or more, 18 g / 10 min or more, 18.5 g / 10 min or more, or 18.9 g / 10 min or more, and less than 38 g / 10 min, less than 35 g / 10 min, less than 33 g / 10 min, less than 30 g / 10 min, or less than 29.7 g / 10 min (ASTM D 1238, 190°C, 2.16 kg).

[0031] This optimizes the weight-average molecular weight of polyethylene, minimizing yarn breakage during the spinning process when manufacturing low-denier (fine) fibers, and reducing the processing load on mesh filters, thereby improving filtration performance and process yield. For reference, denier is an international unit used to express the fineness of yarn. One denier is defined as the weight of 1 gram when a standard length of 9,000 meters is weighed.

[0032] Furthermore, polyethylene may preferably have a melt flow rate ratio (MFRR, MI5 / MI) of 2 to 3. 2.16 ).

[0033] MFRR is the MFR5 measured according to ASTM D 1238 at 190°C and 5 kg load, divided by the MFR measured at 190°C and 2.16 kg load. 2.16 The value of .

[0034] More specifically, the melt flow rate ratio (MFRR, MFR5 / MFR) of polyethylene measured at 190°C according to ASTM D1238. 2.16 The value can be 2.2 or higher, 2.3 or higher, 2.4 or higher, or 2.5 or higher, and below 2.90, 2.85, 2.7 or lower, or 2.56.

[0035] With such a narrow melt flow rate ratio range, the polyethylene disclosed herein achieves excellent filterability and improved process yield.

[0036] Furthermore, the content of alkaline earth metals and transition metals, as measured by inductively coupled plasma (ICP) spectroscopy, is less than 0.8 ppm, or 0 to 0.8 ppm. Preferably, the content of alkaline earth metals and transition metals may be less than 0.5 ppm, less than 0.1 ppm, less than 0.08 ppm, less than 0.05 ppm, less than 0.03 ppm, or less than 0.01 ppm. Polyethylene is characterized by the absence or minimization of residual metallic inorganic substances such as alkaline earth metals and transition metals from the polymerization process. However, in practice, the content of alkaline earth metals and transition metals in polyethylene may be greater than 0.0001 ppm, greater than 0.0002 ppm, greater than 0.0005 ppm, greater than 0.0008 ppm, greater than 0.001 ppm, greater than 0.002 ppm, greater than 0.005 ppm, or greater than 0.008 ppm. Preferably, the content of alkaline earth metals and transition metals in polyethylene may be 0.

[0037] The polyethylene disclosed herein reduces or eliminates the content of alkaline earth metals and transition metals as described above, thereby preventing yarn breakage caused by metallic inorganic materials during the spinning process when manufacturing low denier (fine) fibers.

[0038] Specifically, polyethylene can be measured using various methods known for residue analysis of inorganic substances, as described in the examples below. For instance, inorganic residue analysis of polyethylene can be performed using an inductively coupled plasma (ICP) spectrometer (ICP-OES, Optima 8300Dv). For example, polyethylene can be heated at 200°C for 1 hour, at 400°C for 2 hours, and then at 650°C for 3 hours. Afterward, inorganic substances, such as alkaline earth metals and transition metals, can be analyzed by inductively coupled plasma (ICP) spectroscopy.

[0039] Furthermore, polyethylene may have a halogen content of less than 5 ppm, or 0 to 5 ppm, as measured by combustion ion chromatography (IC). Preferably, the halogen content may be less than 3.5 ppm, less than 3 ppm, less than 2.5 ppm, less than 2 ppm, less than 1.8 ppm, less than 1.5 ppm, less than 1.3 ppm, less than 1.2 ppm, less than 1.1 ppm, less than 1 ppm, less than 0.8 ppm, less than 0.5 ppm, less than 0.3 ppm, less than 0.1 ppm, less than 0.08 ppm, less than 0.05 ppm, less than 0.03 ppm, or less than 0.01 ppm. Polyethylene is characterized by the absence or minimization of residual halogens from the polymerization process. However, in practice, the halogen content in polyethylene can be 0.0001 ppm or more, 0.0002 ppm or more, 0.0005 ppm or more, 0.0008 ppm or more, 0.001 ppm or more, 0.002 ppm or more, 0.005 ppm or more, or 0.008 ppm or more. Preferably, the halogen content, such as chlorine (Cl), in polyethylene can be 0.

[0040] Thus, the polyethylene disclosed herein can prevent discoloration by reducing the residue of halogen compounds or by being free of halogen substances (such as chlorine), thereby preventing corrosion of metallic materials such as molding machines and decomposition of polyethylene due to oxidation reactions.

[0041] Specifically, polyethylene can be measured using various methods known for residual analysis of halogenated substances, and specific measurement methods can be understood with reference to the examples described later. For example, halogenated residues in polyethylene can be analyzed using combustion ion chromatography (ICS-2100 / AQF-2100H). For example, halogenated substances in polyethylene, such as chlorine (Cl), can be analyzed by combustion ion chromatography at combustion temperatures of 900°C to 1000°C.

[0042] In the case of polyethylene according to one embodiment of the present disclosure, the weight-average molecular weight and molecular weight distribution are optimized, and the occurrence of yarn breakage in the spinning process can be minimized when manufacturing low-denier (fine) fibers. This can reduce the processing load of the mesh filter, thereby improving filtration performance and process yield.

[0043] Specifically, polyethylene may have a molecular weight distribution (Mw / Mn) of 2.0 to 2.6, preferably 2.2 or more, 2.3 or more, 2.32 or more, or 2.35 or more, and less than 2.55, 2.50, 2.48 or less, 2.45 or less, or 2.39 or less.

[0044] In addition, polyethylene can have a weight-average molecular weight of 38,000 g / mol to 65,000 g / mol, and preferably 38,000 g / mol or more, 39,000 g / mol or more, 39,500 g / mol or more, or 40,000 g / mol or more, and less than 63,000 g / mol, less than 60,000 g / mol, less than 58,000 g / mol, less than 55,000 g / mol, or less than 50,000 g / mol.

[0045] In this disclosure, since polyethylene has a narrow molecular weight distribution and has the optimized melt index and weight-average molecular weight as described above, it can simultaneously satisfy excellent mechanical properties and tensile strength.

[0046] In this disclosure, the number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution are molecular weights converted from standard polystyrene measured by gel permeation chromatography (GPC). However, the weight-average molecular weight is not limited thereto and can be measured by other methods known in the art to which this invention pertains.

[0047] For example, polyethylene samples were evaluated using a Waters Polymer Laboratories PLgel MIX-B 300 mm long column and a PL-GPC220 instrument. The measurement temperature was 160°C, and 1,2,4-trichlorobenzene was used as the solvent at a flow rate of 1 mL / min. 200 μL of sample was provided at a concentration of 10 mg / 10 mL. Mw and Mn were determined using calibration curves formed from polystyrene standards. Nine polystyrene standards 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 were used.

[0048] In addition, polyethylene can have a content of 0.945 g / cm³. 3 Up to 0.965 g / cm 3 High-density polyethylene (HDPE) with a density of (ASTM D 1505, 23°C).

[0049] More specifically, the density of polyethylene can be 0.948 g / cm³. 3 Above, 0.949 g / cm 3 Above, or 0.950 g / cm 3 The above, and 0.960 g / cm 3 Below, 0.958 g / cm 3 Below, 0.955 g / cm 3 Below, or 0.954 g / cm 3 the following.

[0050] According to one embodiment of the present disclosure, the polyethylene may be a copolymer of ethylene and at least one comonomer selected from propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. More specifically, according to one embodiment of the present disclosure, the polyethylene may be a copolymer of ethylene and 1-butene.

[0051] Specifically, repeating units derived from comonomers may be included in amounts of about 5 mol% or less, or from about 0 to about 5 mol% of the polyethylene. When included within the above range, polyethylene exhibits better filterability. Preferably, based on the total molar weight of polyethylene, repeating units derived from comonomers may be included in amounts of about 4.8 mol% or less, 4.5 mol% or less, 4.2 mol% or less, 4 mol% or less, 3.8 mol% or less, or 3.5 mol% or less. However, considering the excellent effect of improving filterability by controlling the amount of repeating units derived from comonomers, based on the total weight of polyethylene, repeating units derived from comonomers may be included in amounts of about 0.2 mol% or more, about 0.5 mol% or more, 1 mol% or more, 1.2 mol% or more, 1.5 mol% or more, 1.8 mol% or more, or 2 mol% or more.

[0052] For example, repeating units derived from the comonomer can be included in an amount obtained by reacting the comonomer at a rate of less than 10 mL / min, or from 0 to 10 mL / min, with ethylene at a rate of 10 kg / hr in the copolymerization step described later.

[0053] The polyethylene of this disclosure, which satisfies the above-mentioned physical properties, is characterized by the absence or minimization of residual components of halogenated substances or metallic inorganic substances (such as alkaline earth metals and transition metals) derived from the polymerization process. Furthermore, the melt index, melt flow rate ratio, and narrow molecular weight distribution are optimized, making the polyethylene highly preferably suitable for manufacturing bicomponent fibers or nonwovens with enhanced yellow index and filtration properties in spinning processes by improving aging life.

[0054] To confirm the degree of decrease in tensile strength and the degree of discoloration after oxidation over a certain period of time, the aging properties of the polyethylene disclosed herein can be evaluated by preparing fibers (resin) using conventional methods and storing them in an air convection oven at 80°C for at least 10 days. In this case, the physical properties measured before being placed in the 80°C oven are defined as the pre-aging measurements, and the physical properties measured after being placed in the 80°C oven for more than 10 days are defined as the post-aging measurements.

[0055] Specifically, to confirm the degree of discoloration that occurs after polyethylene has been oxidized for a certain period of time, the yellow index (YI) can be measured according to ASTM E313. For example, the yellow index (YI) can be measured using a COH-400 spectrophotometer (NIPPON DENSHOKUINDUSTRIES), and the specific measurement method can be understood by referring to the examples described later.

[0056] According to one embodiment of this disclosure, the polyethylene may have a ratio (%) of the difference between the yellow index (YI) after aging and the yellow index (YI) before aging, expressed as a percentage (%), which is the ratio of the yellow index (YI) after aging to the yellow index (YI) before aging, and can minimize discoloration during the aging evaluation period.

[0057] Specifically, the physical properties measured after the sample is prepared by injection molding using polyethylene are expressed as the measurement values ​​before aging evaluation (day 0), and the physical properties measured after storage in an air convection oven at 80°C for 10 days are expressed as the measurement values ​​after aging evaluation (day 10). The absolute value of the difference between the yellow index before and after aging can be less than 0.8, or from 0 to 0.8, and preferably less than 0.5, less than 0.3, or less than 0.25. For example, when the yellow index before aging evaluation (day 0) is -8, the measurement value after aging evaluation (day 10) can be from -8.8 to -8.

[0058] Meanwhile, to confirm the extent to which the tensile strength of polyethylene decreases over a certain period of time, the tensile strength (MPa) can be measured according to ASTM D638. For example, it can be measured at room temperature (23°C) using a sample with a thickness of 6.4 mm, at a tensile rate of 50 mm / min, according to the method specified in ASTM D 638.

[0059] According to one embodiment of this disclosure, the polyethylene may have a ratio (%) of the difference between the tensile strength (MPa) after aging and the tensile strength (MPa) before aging, expressed as a percentage (%), that is, the ratio of the tensile strength (MPa) after aging to the tensile strength (MPa) before aging to the tensile strength (MPa) before aging, and the degradation of tensile strength during the aging evaluation period may be minimized.

[0060] Specifically, the physical properties measured after the sample is prepared by injection molding using polyethylene are expressed as the measurements before aging evaluation (day 0), and the physical properties measured after storage in an air convection oven at 80°C for 10 days are expressed as the measurements after aging evaluation (day 10). The absolute value of the difference in tensile strength used to determine the degree of reduction in tensile strength before and after aging can be less than 5 MPa, or 0 to 5 MPa, preferably less than 4.5 MPa, less than 4.0 MPa, or less than 3.5 MPa. For example, when the tensile strength before aging evaluation (day 0) is 30 MPa, the measurement after aging evaluation (day 10) can be between 25 MPa and 30 MPa.

[0061] For example, the tensile strength measured before aging (day 0) as described above can be 25 MPa or more, or 25 MPa to 50 MPa, and preferably 26 MPa or more, 27 MPa or more, or 28 MPa or more. Furthermore, the tensile strength measured after aging (day 10) as described above can be 20 MPa or more, or 20 MPa to 50 MPa, and preferably 22 MPa or more, 24 MPa or more, or 25 MPa or more.

[0062] Furthermore, polyethylene exhibits improved aging life as described above, and can improve the yellow index in bicomponent fiber manufacturing and significantly enhance filterability in spinning processes. Specifically, polyethylene can have a die pressure increase rate (bar / hr) of about 3.7 bar / hr or less, or about 0 to about 3.7 bar / hr, i.e., filterability. Here, filterability is measured in the filterability test by performing an extruder die pressure increase rate test (e.g., 4 hours, #500, 25 kg / hr), and is the increase in die pressure (ΔP) during the extrusion test period (Δt). Preferably, the polyethylene may have a filterability of less than about 3.5 bar / hr, less than about 3.4 bar / hr, less than about 3.2 bar / hr, or less than about 3.1 bar / hr, and more than about 0.5 bar / hr, more than about 1 bar / hr, more than about 2 bar / hr, or more than about 2.5 bar / hr, i.e., the rate of increase in die pressure per unit time (bar / hr) measured by an extruder die pressure increase rate test (4 hours, #500, 25 kg / hr).

[0063] Meanwhile, according to another embodiment of this disclosure, a method for preparing the above-described polyethylene is provided.

[0064] Specifically, polyethylene is prepared by a method including the step of polymerizing one or more olefin monomers in the presence of a hybrid supported metallocene catalyst. The hybrid supported metallocene catalyst includes a first co-catalyst supported on a support, at least one first metallocene compound represented by the following chemical formula 1, at least one second metallocene compound represented by the following chemical formula 2, and a second co-catalyst. The preparation is carried out by a method comprising the following steps: loading a first metallocene compound of chemical formula 1 and a second metallocene compound of chemical formula 2, respectively, before and after the step of loading a first cocatalyst onto a support; and The step of loading a second co-catalyst onto a support: [Chemical Formula 1] (Cp 1 R a ) n (Cp 2 R b M 1 Z 1 3-n In chemical formula 1, M 1 It is a Group 4 transition metal; Cp 1 and Cp2 They may be identical or different from each other, and each independently is selected from any of the following groups: cyclopentadienyl, indenyl, 4,5,6,7-tetrahydro-1-indenyl, and fluorenyl, wherein they can be C 1-20 Hydrocarbon substitution; R a and R b They may be the same or different from each other, and each can be independently hydrogen, substituted or unsubstituted C. 1-20 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-20 alkoxyalkyl, substituted or unsubstituted C 6-20 aryl, substituted or unsubstituted C 6-10 aryloxy, substituted or unsubstituted C 2-20 alkenyl, substituted or unsubstituted C 7-40 alkylaryl, substituted or unsubstituted C 7-40 arylalkyl, substituted or unsubstituted C 8-40 aryl alkenyl, or substituted or unsubstituted C 2-10 alkynyl group; Z 1 Each is an independent halogen atom, substituted or unsubstituted C. 1-20 Alkyl, substituted or unsubstituted C 2-10 alkenyl, substituted or unsubstituted C 7-40 alkylaryl, substituted or unsubstituted C 7-40 arylalkyl, substituted or unsubstituted C 6-20 aryl, substituted or unsubstituted C 1-20 Alkylidene, substituted or unsubstituted amino group, substituted or unsubstituted C 2-20 Alkylalkoxy, or substituted or unsubstituted C 7-40 arylalkoxy; and n is 1 or 0; [Chemical Formula 2]

[0065] In chemical formula 2, B represents boron. M is a group 4 transition metal. R1 through R4 are each independently hydrogen, substituted, or unsubstituted C. 1-20 Alkyl, substituted or unsubstituted C 3-20 cycloalkyl, or substituted or unsubstituted C 6-20 Aryl groups, or R1 and R2 or R3 and R4, bond to each other to form substituted or unsubstituted C. 6-60 Aromatic rings, R5 and R6 are independently substituted or unsubstituted C. 1-20Alkyl, substituted or unsubstituted C 3-20 cycloalkyl, or substituted or unsubstituted C 6-20 Aryl groups, or R5 and R6 bonds to each other to form substituted or unsubstituted C groups. 3-60 Aliphatic rings or substituted or unsubstituted C 6-60 Aromatic rings, X1 and X2 are each independently substituted or unsubstituted C. 1-20 Alkyl or -O(CO)R', where R' is C 1-20 alkyl, Q represents whether C is substituted or not substituted. 2-60 Heterocyclic compounds containing at least one selected from N, O, and S. Y and Y' are the elements that make up Q. Y is N, O, or S. Y' is the element in Q that is adjacent to Y, and Y' is N or C.

[0066] The substituents are described in more detail below.

[0067] In this document, unless otherwise stated, the following terms may be defined as follows.

[0068] The halogen can be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

[0069] Furthermore, the alkyl group can be either straight-chain or branched. Specifically, C 1-20 Alkyl groups can be C 1-20 Straight-chain alkyl; C 1-10 Straight-chain alkyl; C 1-5 Straight-chain alkyl; C 3-20 Branched alkyl; C 3-15 Branched alkyl groups; or C 3-10 Branched alkyl groups. More specifically, C 1-20 The alkyl group can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, or isopentyl, but the invention is not limited thereto. Meanwhile, "iPr" as used herein refers to isopropyl.

[0070] Cycloalkyl groups can be cyclic alkyl groups. Specifically, C 3-20 Cycloalkyl groups can be C 3-20 Cycloalkyl; C 3-15 Cycloalkyl; or C 3-10 Cyclic alkyl groups. More specifically, they can be cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, etc., but the invention is not limited thereto. Furthermore, as used herein, "Cy" refers to C3 to C6 cycloalkyl groups.

[0071] Furthermore, 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.

[0072] The alkoxy group can be straight-chain, branched, or cyclic. Specifically, the C 1-20 Alkoxy groups can be C 1-20 Straight-chain alkoxy; C 1-10 Straight-chain alkoxy; C 1-5 Straight-chain alkoxy; C 3-20 Branched or cyclic alkoxy groups; C 3-15 Branched or cyclic alkoxy groups; or C 3-10 Branched or cyclic alkoxy groups. More specifically, C 1-20 The alkoxy group can be methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, or cyclohexyloxy, but this disclosure is not limited thereto.

[0073] Alkoxyalkyl groups may have -R a -OR b The structure can be alkyl (-R) a One or more hydrogen atoms of ) are alkoxylated (-OR) b Substituents that replace ) Specifically, C 2-20 The alkoxyalkyl group can be methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, tert-butoxyhexyl, etc.

[0074] The aryl group can be a monocyclic, bicyclic, or tricyclic aromatic hydrocarbon. According to embodiments of this disclosure, the aryl group can have 6 to 60 carbon atoms or 6 to 20 carbon atoms. Specifically, the aryl group can be phenyl, naphthyl, anthraceneyl, dimethylaniline, anisyl, etc., but is not limited thereto.

[0075] A heteroaryl is a heteroaryl containing at least one of O, N and S as a heteroelement, and although there is no particular limitation on the number of carbon atoms, it can have 2 to 60 carbon atoms or 2 to 20 carbon atoms. Specifically, it can be xanthium, thiophene, furanyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, oxadiazolyl, triazolyl, pyridylgroup, bipyridyl, pyridinyl group, pyrimidinyl, triazinyl, acridineyl, pyridazinyl, quinolinyl, quinazolinyl, quinoxolinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, isoquinolinyl, indolyl, carbazole, benzoxazolyl, benzoimidazolyl, benzothiazolyl, benzocarbazole, benzothiaphene, dibenzothiaphene, benzofuranyl, phenanthrolyl, isoxazolyl, thiadiazolyl, phenothiazinyl, dibenzofuranyl, etc., but this disclosure is not limited to these.

[0076] A hydrocarbon group is a monovalent hydrocarbon compound and can include alkyl, alkenyl, alkynyl, aryl, aralkyl, aryl-alkenyl, arylynyl, alkylaryl, alkenylaryl, alkynylaryl, etc. For example, the 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 be an alkylaryl group, such as methylphenyl, ethylphenyl, methylbiphenyl, and methylnaphthyl, or an arylalkyl group, such as benzyl, phenethyl, biphenylmethyl, and naphthylmethyl. It can also be an alkenyl group, such as allyl, vinyl, propenyl, butenyl, and pentenyl.

[0077] Furthermore, heterocycles include aliphatic rings containing at least one selected from N, O, and S, and aromatic rings containing at least one selected from N, O, and S.

[0078] Furthermore, the Group 4 transition metals can be titanium (Ti), zirconium (Zr), hafnium (Hf), or ruthenium (Rf), and particularly titanium (Ti), zirconium (Zr), or hafnium (Hf). More specifically, they can be zirconium (Zr) or hafnium (Hf), but are not limited thereto.

[0079] Within the range of effects exhibiting the same or similar effects as desired, the above substituents may optionally be replaced by one or more substituents selected from the following: hydroxyl; halogen; alkyl or alkenyl, aryl, alkoxy; alkyl or alkenyl, aryl, alkoxy containing at least one heteroatom of group 14 to 16; amino; silyl; alkylsilyl or alkoxysilyl; phosphine group; phosphide group; sulfonate group; and sulfone group.

[0080] The metallocene catalysts for ethylene polymerization disclosed herein may include at least one first metallocene compound represented by chemical formula 1 and at least one second metallocene compound represented by chemical formula 2 as catalyst precursors.

[0081] When the first metallocene compound represented by Formula 1 is activated by a suitable method and used as a catalyst for olefin polymerization, polyethylene with a low molecular weight can be provided. Therefore, a hybrid supported catalyst comprising the first and second metallocene compounds can provide polyethylene with a broad molecular weight distribution.

[0082] Specifically, Cp of chemical formula 1 1 and Cp 2 It can be cyclopentadienyl. Where Cp... 1 and Cp 2 The first metallocene compound, which is cyclopentadienyl and cyclopentadiethyl unbridged, exhibits low comonomer binding with α-olefins in olefin polymerization and primarily produces polyethylene with low molecular weight. Therefore, when the first metallocene compound is mixed with a second metallocene compound of Formula 2 and loaded onto the same support, the molecular weight distribution of polyethylene, the distribution of comonomers in the polyethylene chain, and the copolymerization characteristics of the olefins can be readily controlled, thereby making it easier to achieve the desired physical properties of the polyethylene of this disclosure.

[0083] Cp 1 It can be one to five Rs a Replace, and Cp 2 It can be one to five Rs b Substitution. When two or more R in chemical formula 1 a When replaced, multiple R a They can be the same as or different from each other. Furthermore, when there are two or more R's in chemical formula 1... b When replaced, multiple R b They can also be the same as or different from each other.

[0084] R a and R b They can each be independently hydrogen or C. 1-10 hydrocarbon group, C 1-10 alkyl groups and C 2-20 Any of the hydroxyl or hydrocarbon groups. Specifically, R a and R b They can each be independently hydrogen or C. 1-20 Alkyl, C 1-10 Alkoxy, C 2-20 Alkoxyalkyl, C 6-20 Aryl, C 6-10 aryloxy group, C 2-20 alkenyl, C 7-40alkylaryl, C 7-40 Arylalkyl, C 8-40 aryl alkenyl or C 2-10 Alkyne groups. More specifically, they can each independently be hydrogen, C, or C. 1-6 Alkyl, C 7-12 Arylalkyl, C 2-12 Alkoxyalkyl, C 6-12 Aryl or C 2-6 Alkenyl. Preferably, R a and R b Each of these can be independently hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, butenyl, phenyl, phenyl-substituted methyl, phenyl-substituted butyl, or tert-butoxyhexyl. Where R... a and R b First metallocene compounds with the same substituents may exhibit excellent loading stability.

[0085] In addition, Z of chemical formula 1 1 Each can be an independent halogen. In which Z... 1 In the first metallocene compounds having the aforementioned substituents, the halogen group can be readily replaced by an alkyl group through reaction with an alkyl metal or methylaluminoxane as a cocatalyst. Furthermore, the first metallocene compound more readily provides a cationic form by forming an ionic intermediate with the cocatalyst through subsequent alkyl abstraction; this is the active material for olefin polymerization.

[0086] Preferably, M 1 It could be zirconium (Zr).

[0087] For example, in chemical formula 1, M 1 It can be zirconium (Zr) or hafnium (Hf), with zirconium (Zr) being preferred. Furthermore, Cp... 1 and Cp 2 Each can be cyclopentadienyl, indenyl, or fluorenyl. Additionally, R... a and R b They can each be hydrogen or carbon. 1-6 Alkyl, C 7-12 Arylalkyl, C 2-12 Alkoxyalkyl, C 6-12 Aryl or C 2-6 Alkenyl, and preferably hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, butenyl, phenyl, phenyl-substituted methyl, phenyl-substituted butyl, or tert-butoxyhexyl. Furthermore, each Z... 1 It can be a halogen atom, and preferably chlorine (Cl). In addition, n can be 1.

[0088] The compound represented by chemical formula 1 can be, for example, a compound represented by one of the following structural formulas, but is not limited thereto.

[0089] .

[0090] The first metallocene compound represented by chemical formula 1 can be synthesized by employing known reactions, and more specific synthetic methods can be understood by referring to the examples.

[0091] Specifically, hybrid supported catalysts may include first metallocene compounds, wherein Cp 1 and Cp 2 It is cyclopentadienyl, R a and R b It is tert-butoxyhexyl, M 1 It's zirconium, Z. 1 It is chlorine (Cl), and n is 1.

[0092] Meanwhile, polyethylene according to this disclosure can be prepared by polymerizing ethylene in the presence of a catalyst containing at least one second metallocene compound represented by the following chemical formula 2 and at least one first metallocene compound as a catalyst precursor.

[0093] Unlike conventionally used CGC (confined geometry catalyst) precursors, the metallocene compounds represented by Formula 2 employ a bridging structure including boron anions. Traditional CGC precursors have a silicon-containing neutral bridging structure, resulting in negatively charged ligand units. This leads to structural confinement and makes it difficult to achieve different physical properties when preparing olefin polymers.

[0094] On the other hand, the metallocene compounds represented by Formula 2 according to this disclosure can have neutral ligand units because the bridge structure is negatively charged. The ligand unit of this disclosure is a heterocyclic Q of Formula 2, wherein Y, as an element of Q, is coordinated with the metal, and Y', as an element of Q and adjacent to Y, is connected to the bridge. Therefore, since this disclosure employs various neutral ligand units that satisfy the above structure, catalysts with higher activity and higher comonomer binding than conventional CGC precursors can be prepared.

[0095] In addition, alkyl or carboxylic acid esters are included as metal substituents in metallocene compounds represented by Formula 2, which serve as good leaving groups to promote reactions with co-catalysts (such as MAO), thereby enhancing activity.

[0096] Specifically, in chemical formula 2, B represents boron.

[0097] Specifically, in chemical formula 2, M can be zirconium (Zr).

[0098] Furthermore, in chemical formula 2, R1 to R4 can each be independently hydrogen, substituted or unsubstituted C. 1-10 Alkyl, or substituted or unsubstituted C 6-20 Aryl groups; or R1 and R2 or R3 and R4 can bond to each other to form substituted or unsubstituted C groups. 6-20 Aromatic ring. Preferably, R1 to R4 can each be hydrogen or methyl independently; or R1 and R2 or R3 and R4 can be bonded to each other to form a benzene ring or a 1,2,3,4-tetrahydronaphthalene ring, wherein the benzene ring or the 1,2,3,4-tetrahydronaphthalene ring is unsubstituted or substituted by one to four substituents selected from methyl, tert-butyl and 4-tert-butylphenyl.

[0099] More preferably, R1 to R4 can all be methyl groups.

[0100] Furthermore, in chemical formula 2, R5 and R6 are each independently substituted or unsubstituted C. 1-10 Alkyl, or substituted or unsubstituted C 6-20 Aryl groups, or R5 and R6 bonds to each other to form substituted or unsubstituted C groups. 3-20 Aliphatic rings or substituted or unsubstituted C 6-20 Aromatic ring. Preferably, R5 and R6 can each be methyl or phenyl independently, or R5 and R6 can be bonded to each other to form a cyclooctane ring.

[0101] More preferably, both R5 and R6 can be phenyl.

[0102] Furthermore, in chemical formula 2, X1 and X2 can each be independently substituted or unsubstituted C. 1-10 Alkyl or -O(CO)R', where R' is C 1-10 Alkyl group. Preferably, X1 and X2 can each be methyl or acetate independently.

[0103] Furthermore, in chemical formula 2, R' can be a methyl group.

[0104] Furthermore, in chemical formula 2, X1 and X2 can be the same.

[0105] More preferably, X1 and X2 can be methyl groups.

[0106] Furthermore, in chemical formula 2, Q can be a substituted or unsubstituted C containing at least one selected from N, O, and S. 2-20 Or C 2-12Heterocyclic ring. Preferably, Q can be a pyridine ring, a quinoline ring, a 4,5-dihydrooxazole ring, a pyrazole ring, or a benzoxazole ring, wherein Q is unsubstituted or substituted with one to four substituents selected from methyl, isopropyl, and diphenylamino. More preferably, Q can be a pyridine ring, a 4,5-dihydrooxazole ring, a pyrazole ring, or a benzoxazole ring, wherein Q is unsubstituted or substituted with one to four substituents selected from methyl, isopropyl, and diphenylamino.

[0107] Furthermore, in chemical formula 2, Y is a heteroatom coordinated with metal M. Preferably, Y can be N.

[0108] More preferably, in chemical formula 2, Q, which includes Y and Y', can be a pyridine ring.

[0109] Meanwhile, specific examples of the second metallocene compound represented by chemical formula 2 may include compounds represented by the following structural formulas, but this disclosure is not limited thereto:

[0110]

[0111] .

[0112] When X1 and X2 are identical, the second metallocene compound represented by chemical formula 2 can be prepared, for example, by the preparation method shown in reaction formula 1 below. However, this disclosure is not limited thereto, and it can be prepared according to known methods for preparing organic compounds and metallocene compounds. More detailed methods are described in the preparation examples described later.

[0113] [Reaction Formula 1]

[0114] In reaction formula 1, B, M, R1 to R6, X1, X2, Q, Y and Y' are as defined in chemical formula 2 above.

[0115] Specifically, the supported hybrid catalyst may include a second metallocene compound, wherein B is boron, M is zirconium, R1 to R4 are methyl, R5 and R6 are phenyl, X1 and X2 are methyl, Y is N, Y' is C, and Q containing Y and Y' is a pyridine ring.

[0116] Furthermore, the first and second metallocene compounds can be combined in appropriate amounts according to the physical properties of the polyethylene to be prepared. For example, to provide polyethylene with a wide molecular weight distribution and high molecular weight, the first and second metallocene compounds can be used in a molar ratio of 3:1 to 1:10 (first metallocene compound: second metallocene compound). Specifically, the molar ratio of the first and second metallocene compounds can be 2.5:1 to 1:5, 2:1 to 1:4, 2:1 to 1:2, or 2:1 to 1:1. Therefore, by easily controlling the molecular weight distribution of polyethylene, the distribution of comonomers in the polyethylene chain, and the copolymerization characteristics of ethylene, the desired physical properties can be achieved more easily.

[0117] In particular, the metallocene catalyst disclosed herein is a hybrid supported catalyst, wherein at least one first metallocene compound represented by Chemical Formula 1 and at least one second metallocene compound represented by Chemical Formula 2 are supported. When using the supported metallocene catalyst, the polyethylene to be prepared exhibits excellent morphology and physical properties, and is suitable for conventional slurry polymerization, bulk polymerization, or gas-phase polymerization processes.

[0118] In the hybrid supported metallocene catalysts disclosed herein, the support for supporting the first and second metallocene compounds may have highly reactive hydroxyl, silanol, or siloxane groups on its surface. The support may be surface-modified by calcination or dried to remove moisture from its surface. For example, the support may be silica prepared by calcining silica gel, silica dried at high temperature, silica-alumina, or silica-magnesium oxide, and may typically contain oxides, carbonates, sulfates, or nitrates, such as Na₂O, K₂CO₃, BaSO₄, Mg(NO₃)₂, etc.

[0119] The support is preferably used in a sufficiently dry state before loading the first and second cocatalysts. The support is preferably calcined or dried at about 200 to 600°C, more preferably about 250 to 600°C. At low temperatures, the support contains excessive moisture, which may react with the cocatalyst. Furthermore, due to the excess hydroxyl groups, the cocatalyst loading may be relatively high, but this requires a large amount of cocatalyst. At excessively high temperatures, the pores on the support surface may bind together, reducing the surface area, and many hydroxyl or silanol groups may be lost from the surface, leaving only siloxane groups. Therefore, the number of reaction sites with the cocatalyst may decrease, which is undesirable.

[0120] The amount of hydroxyl groups on the surface is preferably 0.1 to 10 mmol / g, or 0.5 to 5 mmol / g. The amount of hydroxyl groups on the surface can be controlled by the preparation method of the support, the preparation conditions, or the drying conditions such as temperature, time, vacuum, or spray drying.

[0121] When the amount of hydroxyl groups is less than 0.1 mmol / g, there may be insufficient reaction sites with the co-catalyst. When the amount of hydroxyl groups is greater than 10 mmol / g, in addition to the hydroxyl groups present on the surface of the support particles, it may also be caused by moisture, which is undesirable.

[0122] For example, the amount of hydroxyl groups on the surface can be 0.1 to 10 mmol / g, or 0.5 to 5 mmol / g. The amount of hydroxyl groups can be controlled by the preparation method of the support, the preparation conditions, or the drying conditions, such as temperature, time, vacuum, or spray drying. When the amount of hydroxyl groups is too low, there may be insufficient reaction sites with the co-catalyst. When the amount of hydroxyl groups is too high, it may be due to moisture in addition to the hydroxyl groups present on the surface of the support particles, which is undesirable.

[0123] In the aforementioned supports, silica prepared by calcination (especially silica gel) exhibits almost no catalyst release from the support surface during propylene polymerization because the functional groups of the silica support and the compound of Formula 1 are supported by chemical bonds. Consequently, scaling phenomena, such as adhesion to the reactor wall surface or adhesion to each other, can be minimized when preparing polyethylene via slurry polymerization or gas-phase polymerization.

[0124] Furthermore, when supported on a support, based on the weight of the support, for example, 1 g of silicon dioxide, the total amount of the first metallocene compound of Formula 1 and the second metallocene compound of Formula 2 can be about 10 μmol or more, about 20 μmol or more, about 30 μmol or more, or about 50 μmol or more, and about 250 μmol or less, about 200 μmol or less, about 180 μmol or less, or about 150 μmol or less. When supported within the above ranges, the supported catalyst can exhibit appropriate activity, which is advantageous in terms of maintaining catalytic activity and economic feasibility.

[0125] Furthermore, the hybrid metallocene catalyst disclosed herein may include a first co-catalyst and a second co-catalyst for preparing the catalytically active material. By using two types of co-catalysts, catalytic activity can be improved, and in particular, the molecular weight distribution of polyethylene can be controlled by using the second co-catalyst.

[0126] The first cocatalyst can be any cocatalyst used for the polymerization of olefins in the presence of a general metallocene catalyst. This first cocatalyst leads to the formation of bonds between the hydroxyl groups and the transition metal on the support. Furthermore, since the first cocatalyst exists only on the surface of the support, it can help ensure the inherent properties of the specific hybrid catalyst compositions of this disclosure without fouling phenomena such as adhesion to the reactor wall surface or adhesion between them.

[0127] In hybrid supported metallocene catalysts, the first co-catalyst may be at least one compound selected from those represented by chemical formulas 3 and 4: [Chemical Formula 3] -[Al(R 31 )-O] m - In chemical formula 3, R 31 They may be the same as or different from each other, and each is independently a halogen; or C is either unsubstituted or halogenated. 1-20 hydrocarbon groups; and m is an integer greater than or equal to 2. [Chemical Formula 4] D(R 41 )3 In chemical formula 4, D is aluminum or boron, and R 41 They may be the same as or different from each other, and each is independently a halogen; or C is either unsubstituted or halogenated. 1-20 Hydrocarbon group.

[0128] The compound represented by chemical formula 3 can be methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc. Preferably, it can be methylaluminoxane.

[0129] The compound represented by Formula 4 can be trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, trisec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc. Preferably, it can be selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0130] Furthermore, in this disclosure, the second co-catalyst included in the hybrid supported metallocene catalyst may be a borate compound represented by the following chemical formula 5 or chemical formula 6: [Chemical Formula 5] [LH] + [ZA4] - [Chemical Formula 6] [L] + [ZA4] - In chemical formulas 5 and 6, L is an independent neutral or cationic Lewis base; H is a hydrogen atom; Z is independently boron; and A is the same as or different from each other, and each is independently C. 6-20 Aryl or C1-20 Alkyl, wherein C 6-20 Aryl or C 1-20 Alkyl groups are either unsubstituted or selected from halogens, C 1-20 Alkyl, C 1-20 Alkoxy and C 6-20 At least one substituent of the aryloxy group is substituted.

[0131] Furthermore, in chemical formula 5, [LH] + It is a protic acid.

[0132] Specifically, the second cocatalyst based on borates may include trimethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium n-butyltris(pentafluorophenyl)borate, N,N-dimethylphenylammonium benzyltris(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 pentafluorophenoxytris(pentafluorophenyl)borate, N,N-dimethyl-2,4,6-trimethylphenylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethylphenylammonium tetra(2,3,4,6-tetrafluorophenyl)borate, hexadecyldimethylammonium tetra(pentafluorophenyl)borate, N-methyl-N-dodecylphenylammonium tetra(pentafluorophenyl)borate or methylbis(dodecyl)ammonium tetra(pentafluorophenyl)borate. Preferably, the second borate-based cocatalyst may comprise triphenylmethyltetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, or tripropylammonium tetra(pentafluorophenyl)borate, and more preferably N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate. Because the cocatalyst of this disclosure is used to prepare polyethylene suitable for fiber production, it exhibits specificity in both application and manufacturing method.

[0133] In the preparation of the hybrid supported metallocene catalyst of this disclosure, the loading sequence of the components preferably includes: loading a first metallocene compound of chemical formula 1 and a second metallocene compound of chemical formula 2 before and after the step of loading a first cocatalyst on the support; and loading a second cocatalyst on the support. According to this method, the hybrid supported metallocene catalyst of this disclosure may include a first cocatalyst supported on the support, first and second metallocene compounds of chemical formulas 1 and 2; and a second cocatalyst.

[0134] Furthermore, there are no particular limitations on the loading conditions, and the loading steps can be performed within a range known to those skilled in the art. For example, the loading steps can be performed appropriately at high and low temperatures. Specifically, when the first and second cocatalysts are loaded on the support, the loading temperature can be in the range of about 25°C to 100°C. The loading time of the first and second cocatalysts can be appropriately controlled according to the amount of cocatalyst to be loaded. In addition, the reaction temperature of the first and second metallocene compounds with the support can be from -30°C to 150°C, preferably room temperature to 100°C, more preferably 30°C to 80°C. The supported catalyst after the reaction can be used directly after removing the reaction solvent by filtration or vacuum distillation, or it can be used after Soxhlet filtration with aromatic hydrocarbons such as toluene as needed.

[0135] Furthermore, in hybrid supported metallocene catalysts, the total amount of the first and second cocatalysts relative to the total amount of the first metallocene compound of Formula 1 and the second metallocene compound of Formula 2 can be within a molar ratio of about 1000:1 to about 1:1000, preferably about 100:1 to about 1:100, and more preferably about 60:1 to about 1:60 (total of the first and second cocatalysts: total of the first and second metallocene compounds). When the molar ratio of the metallocene compounds exceeds about 1000, the metal content of the cocatalyst is too low, resulting in poor formation of catalytically active substances and low activity. When the molar ratio of the cocatalysts exceeds about 1000, the metal of the cocatalyst may act as a catalyst poison.

[0136] Based on 1 g of support, the first and second cocatalysts can be loaded in total amounts of about 3 mmol to 25 mmol, about 5 mmol to 20 mmol, or about 6 mmol to 15 mmol.

[0137] Specifically, in hybrid supported metallocene catalysts, the molar ratio of the total metal contained in the metallocene catalyst comprising the first and second metallocene compounds to the boron contained in the borate-based second co-catalyst can be 1:0.45 or higher, 1:0.8 or higher, or 1:1 or higher, and 1:3 or lower, 1:2.8 or lower, or 1:2.7 or lower. When the molar ratio is less than 1:0.45, there is a problem of reduced catalytic activity, and when it exceeds 1:3, the activity is excellent, but there is a problem of uneven polymerization reactivity, making the process difficult to operate.

[0138] Supported catalysts can be prepared in the presence of a solvent or in the absence of a solvent. When a solvent is used, it may include C5 to C12 aliphatic hydrocarbon solvents, such as hexane or pentane; aromatic hydrocarbon solvents, such as toluene or benzene; chlorinated hydrocarbon solvents, such as dichloromethane; ether solvents, such as diethyl ether or tetrahydrofuran (THF); and common organic solvents, such as acetone or ethyl acetate. Hexane, heptane, toluene, or dichloromethane are preferred. The solvent used herein is preferably treated with a small amount of alkylaluminum to remove trace amounts of water or air, which may act as catalyst poisons, before use. A co-catalyst may also be used further.

[0139] The preparation method of the hybrid supported catalyst is detailed in the examples described later. However, the preparation method of the hybrid supported catalyst is not limited to this specification. The preparation method may further include steps that are generally performed in the technical field of this invention, and the steps of the preparation method may be modified by generally variable steps.

[0140] Polyethylene according to one embodiment of the present disclosure can be provided by a method including a step of polymerizing olefin monomers in the presence of a hybrid supported catalyst.

[0141] Examples of olefin monomers that can be polymerized by hybrid supported catalysts include ethylene, α-olefins, and cyclic olefins, and diene or triene olefin monomers having two or more double bonds can also be polymerized. Specific examples of such monomers include ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, norbornene, norbornadiene, ethylidene norbornene, phenyl norbornene, vinyl norbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, α-methylstyrene, divinylbenzene, 3-chloromethylstyrene, etc., and these monomers can be copolymerized by mixing two or more of them. When polyethylene is a copolymer of ethylene and another comonomer, the comonomer is preferably at least one selected from propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Specifically, the comonomer may be 1-butene or 1-hexene, and 1-butene is preferred.

[0142] Furthermore, as described above, in the copolymerization step, the comonomer can be added in an amount such that repeating units derived from α-olefins are included in the polyethylene in an optimal quantity. For example, the comonomer can be added in an amount such that repeating units derived from the comonomer obtained by the copolymerization process are included in the polyethylene in an amount of about 5 mol% or less, or from about 0 to about 5 mol%. Specifically, the input amount of comonomer can be adjusted within the range described above, taking into account the amount of repeating units derived from the comonomer included in the polyethylene.

[0143] For example, the copolymerization step can be carried out by reacting a comonomer in an amount of about 0.05 mol or less, or 0 to about 0.05 mol, based on 1 mol of ethylene. When reacted within the above range, polyethylene exhibits better filterability. Preferably, based on 1 mol of ethylene, about 0.048 mol or less, 0.045 mol or less, 0.042 mol or less, 0.04 mol or less, 0.038 mol or less, or 0.035 mol or less of comonomer can be reacted. However, considering the excellent effect of improving filterability by controlling the amount of repeating units derived from the comonomer, based on 1 mol of ethylene, more than 0.005 mol, more than 0.01 mol, more than 0.012 mol, more than 0.015 mol, more than 0.018 mol or more, or more than 0.02 mol of comonomer can preferably be reacted.

[0144] Specifically, in the copolymerization step, when 10 kg / hr of ethylene is added, the comonomer is added at a rate of 10 mL / min or less, or 0 to 10 mL / min, to initiate the reaction. This can be done within the aforementioned range to allow repeating units derived from the comonomer to be included in the polyethylene in the optimal amount. More specifically, when 10 kg / hr of ethylene is added, the comonomer can be added at rates of 8.0 mL / min or less, 6.0 mL / min or less, 5.0 mL / min or less, 4.5 mL / min or less, 4.2 mL / min or less, 4.0 mL / min or less, 3.8 mL / min or less, 3.5 mL / min or less, 3.0 mL / min or less, or 2.6 mL / min or less to initiate the reaction. However, considering the excellent effect of improving filtration by controlling the amount of repeating units derived from the comonomer, when adding 10 kg / hr of ethylene, the comonomer can be added at a rate of 0.1 mL / min or higher, 0.5 mL / min or higher, 1.0 mL / min or higher, 1.3 mL / min or higher, 1.5 mL / min or higher, 1.8 mL / min or higher, 1.9 mL / min or higher, 2.0 mL / min or higher, or 2.1 mL / min or higher.

[0145] For the polymerization of olefin monomers, various polymerization processes known as polymerization of olefin monomers can be used, such as continuous solution polymerization, bulk polymerization, suspension polymerization, slurry polymerization, or emulsion polymerization.

[0146] Specifically, polymerization can be carried out at temperatures ranging from about 25°C to 500°C, preferably from about 25°C to 200°C, more preferably from about 50°C to 150°C, or from about 60°C to about 100°C. Furthermore, polymerization can be carried out at temperatures of about 1 kgf / cm³.2 Up to 100 kgf / cm 2 Preferably about 1 kgf / cm 2 Up to 50 kgf / cm 2 And more preferably about 5 kgf / cm 2 Up to 30 kgf / cm 2 Polymerization occurs under pressure.

[0147] Furthermore, in polymerization reactions, the hybrid supported catalyst can be used in a state of dissolution or dilution in solvents such as pentane, hexane, heptane, nonane, decane, toluene, benzene, dichloromethane, chlorobenzene, etc. The solvent used here is preferably used after treatment with a small amount of alkylaluminum to remove trace amounts of water or air that may adversely affect the catalyst.

[0148] Furthermore, the polymerization step can be carried out by introducing hydrogen gas at a concentration of approximately 15 ppm to approximately 800 ppm based on the ethylene content. Preferably, based on the ethylene content, hydrogen gas can be introduced at concentrations of approximately 20 ppm or more, approximately 25 ppm or more, approximately 30 ppm or more, approximately 50 ppm or more, approximately 60 ppm or more, approximately 80 ppm or more, approximately 90 ppm or more, approximately 95 ppm or more, or approximately 100 ppm or more, and at concentrations of approximately 500 ppm or less, approximately 400 ppm or less, approximately 350 ppm or less, approximately 300 ppm or less, approximately 250 ppm or less, approximately 200 ppm or less, approximately 180 ppm or less, approximately 170 ppm or less, approximately 165 ppm or less, approximately 160 ppm or less, or approximately 155 ppm or less. For example, when adding 10 kg / hr of ethylene, hydrogen gas can be introduced at a rate of approximately 0.15 g / hr to approximately 8 g / hr, with the preferred ranges as described above. More specifically, when 10 kg / hr of ethylene is added during the polymerization step, hydrogen can be introduced at a rate of about 1.09 g / hr to about 1.51 g / hr.

[0149] In ethylene polymerization processes, catalyst compositions comprising the metallocene compounds of this disclosure can exhibit high catalytic activity. For example, the catalytic activity during ethylene polymerization is calculated as the ratio of the weight of polyethylene produced per unit time (hr) (kg PE) to the mass (g) of the catalyst composition used, and can be above about 4.0 kg PE / g·cat·hr, or from about 4.0 kg PE / g·cat·hr to about 50 kg PE / g·cat·hr. Specifically, the catalytic activity can be above approximately 4.5 kg PE / g·cat·hr, above approximately 5.0 kg PE / g·cat·hr, above approximately 7 kg PE / g·cat·hr, above approximately 8.5 kg PE / g·cat·hr, above approximately 10 kg PE / g·cat·hr, above approximately 12 kg PE / g·cat·hr, above approximately 13.5 kg PE / g·cat·hr, above approximately 14 kg PE / g·cat·hr, above approximately 15 kg PE / g·cat·hr, above approximately 15.5 kg PE / g·cat·hr, above approximately 16 kg PE / g·cat·hr, above approximately 16.5 kg PE / g·cat·hr, above approximately 17 kg PE / g·cat·hr, or above approximately 18 kg PE / g·cat·hr. However, in terms of the actual catalytic activity during ethylene polymerization, it can be below approximately 48 kg PE / g·cat·hr, below 45 kg PE / g·cat·hr, below approximately 42 kg PE / g·cat·hr, below approximately 40 kg PE / g·cat·hr, below approximately 38 kg PE / g·cat·hr, below approximately 35 kg PE / g·cat·hr, below approximately 30 kg PE / g·cat·hr, or below approximately 28 kg PE / g·cat·hr.

[0150] The polyethylene prepared by one embodiment is characterized by the absence or minimization of residual components of halogenated substances or metallic inorganic substances (such as alkaline earth metals and transition metals) originating from the polymerization process. Furthermore, the melt index, melt flow rate ratio, and narrow molecular weight distribution are optimized, thereby improving aging life, enhancing the yellow index when manufacturing bicomponent fibers, and significantly improving filtration properties during spinning processes.

[0151] In particular, the polyethylene according to one embodiment of the present disclosure is characterized by the absence or minimization of halogen compound residues from the polymerization process, such that when manufacturing bicomponent fibers, corrosion of metallic materials (such as molding machines) and discoloration caused by polyethylene decomposition do not occur, even if neutralizers (acid scavengers) such as metal stearates (e.g., calcium stearate) or extrusion aids are not used in the extrusion process.

[0152] Preferred embodiments are provided below to aid in understanding the invention. However, these embodiments are for illustrative purposes only, and the invention is not limited to these embodiments.

[0153] <Example> [Preparation of catalyst precursors] Synthesis Example 1: Preparation of the First Metallocene Compound

[0154] tert-butyl-O-(CH2)6-Cl was prepared using 6-chlorohexanol by the method shown in Tetrahedron Lett. 2951 (1988), and then reacted with sodium cyclopentadienyl (NaCp) to obtain tert-butyl-O-(CH2)6-C5H5 (yield: 60%, boiling point (bp) 80°C / 0.1 mmHg).

[0155] Then, tert-butyl-O-(CH2)6-C5H5 was dissolved in tetrahydrofuran (THF) at -78°C, and n-butyllithium (n-BuLi) was slowly added to it. The mixture was then heated to room temperature and reacted for 8 hours. The resulting lithium salt solution was then slowly added at -78°C to a ZrCl4(THF)2 (170 g, 4.50 mmol) / THF (30 mL) suspension, 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. The filtrate was dried under vacuum, and hexane was added to precipitate at low temperature (-20°C). The precipitate was filtered at low temperature to give [tert-butyl-O-(CH2)6-C5H4]2ZrCl2] as a white solid (92% yield).

[0156] 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) 13 C-NMR (300 MHz, CDCl3, ppm): δ 135.09, 116.66, 112.28, 72.42, 61.52,30.66, 30.31, 30.14, 29.18, 27.58, 26.00 Synthesis Example 2: Preparation of Second Metallocene Compounds

[0157] After dissolving 2-bromopyridine (1 eq.) in tetrahydrofuran (0.1 M), n-butyllithium (1 eq.) was slowly added dropwise at -90°C, followed by stirring at the same temperature for 1 hour. Then, dichlorophenylborane (1 eq.) was dissolved in toluene (0.3 M) and slowly added dropwise to the first reactant at -78°C, followed by stirring for 1 hour. After stirring at room temperature for 12 hours, the solvent was dried under vacuum, toluene was added, and the residue after removing the solids through a filter was dried under vacuum to obtain diphenyl(pyridin-2-yl)borane.

[0158] Diphenyl(pyridin-2-yl)borane (1 eq.) was dissolved in tetrahydrofuran (0.1 M), and a solution in which lithium tetramethylcyclopentadienide (Li(CpMe4), 1 eq.) was dissolved in tetrahydrofuran (0.1 M) was slowly added dropwise at 0°C, followed by stirring overnight at room temperature. The solvent was then dried under vacuum, and toluene / diethyl ether (3 / 1 v / v, 0.3 M) was added and dissolved. MCl4 (1 eq.) was then mixed with toluene (0.2 M) and added at -78°C, followed by stirring overnight at room temperature. After the reaction was complete, the solvent was dried under vacuum, and dichloromethane was added to remove salts through a filter, etc. The filtrate was dried under vacuum and recrystallized by adding dichloromethane / hexane. The resulting solid was filtered and dried under vacuum to give dichloro{diphenyl(pyridin-2-yl-κN)(η 5 Zirconium(IV)-2,3,4,5-tetramethylcyclopentan-2,4-diene-1-yl)borate.

[0159] Dissolve dichloro{diphenyl(pyridin-2-yl-κN)(η)} in toluene / diethyl ether (3 / 1 v / v, 0.3 M). 5 =-2,3,4,5-Tetramethylcyclopentane-2,4-diene-1-yl)borate}zirconium(IV) (1 eq.), then a solution in which methyllithium (2 eq.) is dissolved in hexane or diethyl ether is slowly added dropwise at -78°C, followed by stirring at room temperature for 12 hours. After the reaction is complete, the solvent is dried under vacuum, and dichloromethane is added to remove salts through a filter, etc. The filtrate is dried under vacuum and recrystallized by adding dichloromethane / hexane. The resulting solid is filtered and dried under vacuum to obtain the precursor compound.

[0160] 1H NMR (500 MHz, CDCl3, ppm): δ 8.32(d, 1H), 8.05(d, 4H), 7.70(t, 1H),7.42(t, 1H), 7.40(t, 4H), 7.23(d, 1H), 7.17(t, 2H), 2.08(s, 6H), 1.93(s, 6H)0.95(s, 6H) [Preparation of Hybrid Supported Catalysts] Preparation Example 1 A hybrid supported metallocene catalyst was prepared by using the first metallocene compound of Synthesis Example 1, the second metallocene compound of Synthesis Example 2, silica as a support (manufactured by Grace, product name: SP952X_1836, calcined at 600°C), methylaluminoxane as the first cocatalyst, and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate as the second cocatalyst. In this case, methylaluminoxane with 8 mmol / g-SiO2 was used as the first cocatalyst, the first metallocene compound of Synthesis Example 1 with 0.1 mmol / g-SiO2, the second metallocene compound of Synthesis Example 2 with 0.05 mmol / g-SiO2, and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate with 0.2 mmol / g-SiO2 as the second cocatalyst.

[0161] Specifically, 100 mL of toluene solution was placed in a glass reactor, and 10 g of the prepared silica was added. The reactor temperature was then raised to 60°C while stirring. After the silica was fully dispersed, the first metallocene compound from Synthesis Example 1 was added and the mixture was stirred for 2 hours. Stirring was stopped, and 53.1 mL of a methylaluminoxane (MAO) / toluene solution was added, followed by stirring at 80°C and 200 rpm for 16 hours. Afterward, the temperature was lowered to 40°C, and the mixture was washed with sufficient toluene to remove unreacted aluminum compounds.

[0162] Then, 100 mL of toluene was added, followed by the addition of the second metallocene compound from Synthesis Example 2, and the mixture was stirred for 2 hours. At this point, the first metallocene compound from Synthesis Example 1 and the second metallocene compound from Synthesis Example 2 were each pre-dissolved in 20 mL of toluene and then added as solutions.

[0163] Subsequently, N,N-dimethylphenylammonium-tetra(pentafluorophenyl)borate was dissolved in 50 mL of toluene using the same molar amount as described above, and then placed in a reactor containing a supported catalyst (of which methylaluminoxane and two metallocene catalysts were supported on silica). Approximately 50 mL of toluene was then added to the reactor to adjust the total solution volume to approximately 150 mL, and the mixture was stirred at 80°C and 200 rpm for 1 hour.

[0164] The mixed solution was then stirred for approximately 2 hours to allow the reaction to proceed. After the reaction was complete, stirring was stopped, the toluene layer was separated and removed, and the remaining toluene was removed under reduced pressure at 40°C, thereby obtaining the hybrid supported metallocene catalyst of Example 1.

[0165] Preparation Example 2 Except for the use of N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate as a second cocatalyst at 0.4 mmol / g-SiO2, the hybrid supported catalyst was prepared in the same manner as in Preparation Example 1.

[0166] Comparative Preparation Example 1 Except for the first metallocene compound of Synthesis Example 1, which was loaded with only 0.15 mmol / g-SiO2 and without using the second metallocene compound, the supported catalyst was prepared in the same manner as in Preparation Example 1.

[0167] Comparative Preparation Example 2 Except that a metallocene compound of the following chemical formula A was used instead of the metallocene compound of synthesis example 1, the silica-supported metallocene catalyst of comparative preparation example 2 was prepared in the same manner as in comparative preparation example 1.

[0168] [Chemical Formula A] .

[0169] [Preparation of Polyethylene] Example 1 In a 220 L reactor of the pilot plant, the hybrid supported catalyst prepared in Example 1 was fed into a single slurry polymerization process to prepare high-density polyethylene (HDPE) according to conventional methods. Ethylene (10 kg / hr) and hydrogen (0.5 g / hr) were continuously reacted in a hexane slurry at a reactor temperature of 80°C. 1-Butene was then added as a comonomer at a rate of 5 mL / min. After the reaction, HDPE was prepared in powder form following solvent removal and drying processes.

[0170] An antioxidant (Irgafos 168, CIBA) of 1,000 ppm was added to the high-density polyethylene obtained above, and granulation was performed using a twin-screw extruder (W&P Twin Screw Extruder, Φ = 75, L / D = 36) at extrusion temperatures ranging from 170°C to 220°C. Here, the antioxidant content is based on the weight of the high-density polyethylene.

[0171] Example 2 High-density polyethylene was prepared in the same manner as in Example 1, except that the hybrid supported catalyst of Preparation Example 2 was used.

[0172] Example 3 High-density polyethylene was prepared in the same manner as in Example 1, except that 10 kg / hr of ethylene and 1 g / hr of hydrogen were introduced.

[0173] Comparative Example 1 High-density polyethylene was prepared in the same manner as in Example 1, except that the supported catalyst of Comparative Preparation Example 1 was used.

[0174] Comparative Example 2 Comparative Example 2 used polyethylene prepared using a Ziegler-Natta catalyst for fiber production (ASPUN 6850A, manufactured by DOW). Here, ASPUN 6850A is a product containing 1000 ppm of antioxidant (Irgafos 168, manufactured by CIBA) and 500 ppm of neutralizing agent (SC110, Ca-St, manufactured by Doobon). The antioxidant and neutralizing agent contents are based on the weight of the high-density polyethylene.

[0175] Comparative Example 3 Comparative Example 3 used a polyethylene product (ASPUN 6835A, manufactured by DOW) prepared with a Ziegler-Natta catalyst for fiber production. Here, ASPUN 6835A is a product containing 1000 ppm of antioxidant (Irgafos 168, manufactured by CIBA) and 1000 ppm of neutralizing agent (SC110, Ca-St, manufactured by Doobon). The antioxidant and neutralizing agent contents are based on the weight of the high-density polyethylene.

[0176] Comparative Example 4 High-density polyethylene was prepared in the same manner as in Example 1, except that the supported catalyst of Comparative Preparation Example 2 was used.

[0177] <Experimental Example 1: Evaluation of the Physical Properties of Polyethylene> The polyethylene prepared in the Examples and Comparative Examples was evaluated for physical properties and analyzed for residues in the following manner, and the results are shown in Table 1 below.

[0178] (1) Catalytic activity (kg PE / g cat·hr) It is calculated as the ratio of the weight of polyethylene produced per unit time (h) (kg PE) to the content of the supported catalyst used (g Cat).

[0179] In Table 1 below, “<15” indicates that the catalytic activity measurement is “less than 15 kg PE / g cat·hr”.

[0180] (2) Melt Index (MI) Melt Index (MI) 2.16 MI5) was measured at 190°C under loads of 2.16 kg and 5 kg respectively, according to ASTM D 1238 (Condition E), and expressed as the weight (g) of the polymer melted in 10 minutes.

[0181] (3) Melt Flow Rate Ratio (MFRR) Melt Flow Rate Ratio (MFRR, MI5 / MI) 2.16 ) is MI5 (MI, 5 kg load) divided by MI 2.16 The ratio of (MI, 2.16 kg load).

[0182] (4) Molecular weight distribution (PDI, polydispersity index, Mw / Mn) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured using gel permeation chromatography (GPC, manufactured by Water Corporation), and the molecular weight distribution (PDI, Mw / Mn) was calculated by dividing the weight-average molecular weight by the number-average molecular weight.

[0183] Specifically, a Waters PL-GPC220 was used as the gel permeation chromatography (GPC) instrument, and a Polymer Laboratories PLgel MIX-B 300 mm column was employed. The measurement temperature was 160°C, and 1,2,4-trichlorobenzene was used as the solvent at a flow rate of 1 mL / min. Each polymer sample was pretreated by dissolving it in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160°C for 10 hours using the GPC analyzer (PL-GP220), and a sample concentration of 10 mg / 10 mL was injected at a volume of 200 μL. Mw and Mn were determined using a calibration curve derived from polystyrene standards. Nine polystyrene standards 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 were used.

[0184] (5) Density The density of polyethylene (g / cm³) was measured according to ASTM D 1505. 3 ).

[0185] (6) Polymer residue analysis For the polyethylene according to the examples and comparative examples, the residues in the polymer were analyzed in the following manner.

[0186] Specifically, polyethylene was heated at 200°C for 1 hour, at 400°C for 2 hours, and then at 650°C for 3 hours. Afterwards, inorganic substances, such as alkaline earth metals, transition metals, and silicon, were analyzed by inductively coupled plasma (ICP) spectroscopy.

[0187] 1. Inorganic substance analysis: ICP-OES (Optima 8300DV) 1) Dispense approximately 1 g to 2 g of the sample into a platinum crucible and weigh it accurately.

[0188] 2) To decompose the organic matter, the sample was slowly heated in an electric furnace to carbonize it.

[0189] Step 1: 200°C, 1 hour; Step 2: 400°C, 2 hours; Step 3: 650°C, 3 hours. 3) Add 1 mL of nitric acid and 10 µL of hydrofluoric acid to the residue and seal with parafilm.

[0190] 4) After adding 1 mL of supersaturated boric acid solution, add 200 μL of 1000 mg / kg Sc internal standard, and dilute the mixture with ultrapure water to a total volume of 20 mL.

[0191] 5) Measured by ICP-OES.

[0192] In addition, halogens, such as chlorine (Cl), are analyzed by combustion ion chromatography at combustion temperatures of 900°C to 1000°C.

[0193] 2. Cl content analysis: Combustion ion chromatography (ICS-2100 / AQF-2100H) 1) Combustion temperature: Inlet temperature 900°C, outlet temperature 1000°C 2) Gas flow rate: Argon 200 mL / min, Oxygen 400 mL / min 3) Humidification rate: 0.23 mL / min, internal standard (PO4) 3- ): 20 mg / kg 4) Absorbent (HO2), absorbent volume: 5 mL, final dilution volume: 10 mL 5) Column: IonPac AS18 (4 x 250 mm) 6) Eluent type: KOH (30.5 mM), elution flow rate: 1 mL / min 7) Detector: Suppression conductivity detector, SRS current: 76 mA 8) Injection volume: 100 μL, isocratic / gradient condition: isocratic 9) Accurately measure approximately 0.04 g of sample on the sample boat.

[0194] 10) The sample was measured by combustion IC.

[0195] In Table 1 below, “<10” indicates that the content of the component was measured to be “less than 10 ppm”, and “ND” indicates that the component was “not detected”.

[0196] Table 1

[0197] Polyethylenes of Examples 1 to 3 were prepared in controlled amounts using a hybrid supported metallocene catalyst containing a specific metallocene compound and a borate compound as a second cocatalyst, without the use of a separate neutralizing agent. As a result, as shown in Table 1 above, alkaline earth metals such as calcium (Ca) and magnesium (Mg), as well as transition metal components (ND) such as titanium (Ti) and zirconium (Zr), were completely undetectable, and only a minimum amount of halogens, such as chlorine (Cl), was detected at 1 ppm. Furthermore, the polyethylene exhibited higher catalytic activity than before, and the melt index (MI) was [not specified]. 2.16 (ASTM D1238, 190°C, 2.16 kg) and melt flow rate ratio (MFRR, MI5 / MI) 2.16 Ensure it is within the optimal range.

[0198] <Experimental Example 2: Physical Properties of Polyethylene Products> Injection-molded samples were prepared using polyethylene prepared in one of the Examples and Comparative Examples. Their properties and filterability were evaluated as follows, and the results are shown in Table 2.

[0199] Specifically, the physical properties measured after the polyethylene prepared in one of the Examples and Comparative Examples was injection molded are expressed as the measurements before aging evaluation (day 0), and the physical properties measured after storage in an air convection oven at 80°C for 10 days are expressed as the measurements after aging evaluation (day 10).

[0200] (1) Yellow Index (YI) To confirm the degree of discoloration that occurs after oxidation for a certain period of time, the yellow index (YI) was measured using a COH-400 spectrophotometer (NIPPON DENSHOKU INDUSTRIES) according to ASTM E 313.

[0201] (2) Spinning treatment load test (filtration test) Each type of polyethylene prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was extruded, and an extruder die pressure increase rate test was performed (4 hours, #500, 25 kg / hr). The more clogged the filter in the production line, the higher the die pressure. Therefore, the filterability, i.e., the spinning treatment load, was defined as the die pressure increase rate and measured. Specifically, the die pressure increment (ΔP) during the extrusion test period (Δt) was measured, and the die pressure increase rate, i.e., the filterability, was calculated.

[0202] (3) Tensile strength (MPa) To determine the extent to which tensile strength decreases over time, tensile strength (MPa) is measured according to ASTM D 638. Specifically, it can be measured at room temperature (23°C) using a sample with a thickness of 6.4 mm, at a tensile rate of 50 mm / min, according to the method specified in ASTM D 638.

[0203] Table 2

[0204] As shown in Table 2, the examples minimize alkaline earth metal and transition metal residues and halogens in polyethylene, while optimizing the melt index and melt flow rate ratio, thus improving aging life compared to the comparative examples, and producing fiber products with enhanced yellow index and filtration properties in the spinning process.

[0205] However, Comparative Examples 1 and 4, prepared using a single supported metallocene catalyst, exhibited significantly reduced tensile strength after aging and high chlorine residue, resulting in discoloration and preventing the production of high-toughness fibers. Furthermore, Comparative Examples 2 and 3, prepared using a Ziegler-Natta catalyst, contained chlorine residue, which caused corrosion of metallic materials (such as molding machines) and promoted the decomposition of polyethylene, leading to discoloration. In particular, Comparative Example 3, prepared by increasing the antioxidant content as an extrusion aid, reduced discoloration, but its tensile strength after aging was significantly reduced due to Ca residue, and it could not produce high-toughness fibers.

Claims

1. A polyethylene that satisfies the following conditions: According to ASTM D 1238, the melt index, measured at 190°C under a load of 2.16 kg, is 15 g / 10 min to 40 g / 10 min. Melt flow rate ratio MI5 / MI 2.16 Below 3 The molecular weight distribution is from 2.0 to 2.

45. The contents of alkaline earth metals and transition metals, as measured by inductively coupled plasma spectroscopy, were below 0.8 ppm. The halogen content, measured by combustion ion chromatography, was below 5 ppm. in, MI5 is the melt index measured according to ASTM D 1238 at 190°C under a 5 kg load, and MI 2.16 The melt index is measured according to ASTM D 1238 at 190°C under a load of 2.16 kg, and The polyethylene has a yellow index (YI) of less than 25% as a percentage of the difference between the yellow index (YI) after aging and the yellow index (YI) before aging, wherein the yellow index (YI) is measured according to ASTM E 313, and the aging is performed by storing the polyethylene in an air convection oven at 80°C for 10 days. The transition metals are Ti and Zr.

2. The polyethylene according to claim 1, wherein, The melt index, measured at 190°C and under a load of 2.16 kg according to ASTM D 1238, is 18 g / 10 min to 33 g / 10 min.

3. The polyethylene according to claim 1, wherein, The melt flow rate ratio MI5 / MI 2.16 It is 2 to 3. MI5 is the melt index measured according to ASTM D 1238 at 190°C under a 5 kg load, and MI 2.16 It is the melt index measured according to ASTM D 1238 at 190°C under a load of 2.16 kg.

4. The polyethylene according to claim 1, wherein, The density, measured at 23°C according to ASTM D 1505, is 0.945 g / cm³. 3 Up to 0.965 g / cm 3 .

5. The polyethylene according to claim 1, wherein, The polyethylene is a copolymer of ethylene and at least one comonomer selected from propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.

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