Polyethylene and preparation method thereof

Abstract

A polyethylene and a method for preparing the same are provided, wherein the polyethylene is improved in terms of total volatile organic compounds (TVOC) generated from a low molecular weight polymer and thus is suitable for fiber production.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of Korean Patent Application Nos. 10-2020-0165109 and 10-2021-0166074, filed on November 30, 2020 and November 26, 2021, respectively, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present invention relates to a polyethylene and a method for preparing the same, which has a reduced generation of total volatile organic compounds (TVOC) due to polymer distribution in a low molecular weight region and is suitable for fiber production. Background Art

[0004] Olefin polymerization catalyst system can be divided into Ziegler-Natta (Ziegler-Natta) and metallocene catalyst system, and these two kinds of high activity catalyst systems have been developed according to their characteristics. Since its development in the 1950s, Ziegler-Natta catalyst has been widely used in existing industrial production. However, since Ziegler-Natta catalyst is a multi-active site catalyst in which multiple active sites are mixed, it has the characteristics of a wide range of polymer molecular weight distribution. In addition, due to the uneven distribution of the composition of the comonomer, the problem is that there is limitation in ensuring the required physical properties.

[0005] In contrast, metallocene catalysts consist of a main catalyst whose main component is a transition metal compound and a cocatalyst whose main component is an organometallic compound, whose main component is aluminum. This catalyst is a single-site catalyst (i.e., a homogeneous composite catalyst) and, due to the characteristics of a single site, provides polymers with a narrow molecular weight distribution and a uniform comonomer composition distribution.

[0006] On the other hand, polypropylene resins used as nonwoven materials have excellent chemical resistance and tensile strength and are mainly used as surface materials for sanitary products such as diapers, sanitary napkins, etc. However, homopolymerized polypropylene resins have the disadvantage of producing a rough feel on the nonwoven surface because they generally have a low content of low molecular weight copolymers and low xylene solubility.

[0007] In order to improve the texture of the surface, bicomponent fibers (wherein polypropylene resin is used for the inner portion and polyethylene resin is used for the outer portion) are produced by mixing polypropylene resin with polyethylene resin, and have been used as materials for nonwovens having improved texture and softness. In addition, in order to provide convenience to users by improving the texture and softness of nonwovens, the thickness of the spun yarn used has been reduced.

[0008] In particular, polyethylene produced using Ziegler-Natta catalysts has high total volatile organic compounds (TVOCs) due to the polymer distribution in the low molecular weight region, making it difficult to use polyethylene as a material closely related to life. During the high-temperature process of producing the final fiber or nonwoven, TVOCs may generate harmful gases such as noxious fumes.

[0009] Therefore, in the production of polyethylene for bicomponent fibers, it is more necessary to develop a polyethylene having a narrow molecular weight distribution to achieve excellent tensile strength and softness, and reduced total volatile organic compound (TVOC) generation that may be increased due to the polymer distribution in the low molecular weight region. Summary of the Invention

[0010] Technical issues

[0011] A polyethylene is provided which has reduced total volatile organic compounds (TVOCs) which may be generated due to the distribution of the polymer in the low molecular weight region, thereby being suitable for fiber production.

[0012] Also provided is a method for preparing the polyethylene for fiber production.

[0013] Technical Solution

[0014] According to one embodiment of the present invention, there is provided a polyethylene, wherein the melt index (ASTM D 1238, 190° C., 2.16 kg) is 15 g / 10 min to 40 g / 10 min,

[0015] Melt flow rate ratio (MFRR, MI5 / MI 2.16 ) is 2.3 to 2.7,

[0016] wherein in the GPC curve with log Mw on the x-axis and dw / dlogMw on the y-axis, the integrated value in the region where Log Mw is 3.0 or less is 0.8% to 1.8% of the total integrated value, and

[0017] When the peak area of ​​straight-chain hydrocarbons having 3 to 32 carbon atoms in a GC-FID chart obtained by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes) is converted into a ratio relative to the peak area of ​​polyethylene, the content of the straight-chain hydrocarbons having 3 to 32 carbon atoms is 600 ppm or less based on 1 g of polyethylene.

[0018] Also provided is a method for preparing the polyethylene for fiber production.

[0019] Beneficial effects

[0020] According to the present invention, there can be provided a polyethylene having a narrow molecular weight distribution due to uniform reaction of ethylene and hydrogen in a reactor by increasing the input amount of hydrogen, and having minimum polymer distribution in a low molecular weight region according to GPC and GC-FID analysis, and a polyethylene having a narrow molecular weight distribution due to uniform reaction of ethylene and hydrogen in a reactor by increasing the input amount of hydrogen, and having a minimum polymer distribution in a low molecular weight region according to GPC and GC-FID analysis, and a polyethylene having a narrow molecular weight distribution due to uniform reaction of ethylene and hydrogen in a reactor by optimizing the melt index (ASTM D 1238, 190° C., 2.16 kg) and the melt flow rate ratio (MFRR, MI5 / MI6). 2.16 ) with reduced TVOC generation.

[0021] Therefore, the polyethylene according to the present invention can be effectively applied to the production of fiber products such as sanitary materials (including diapers and masks), medical products and other general consumer products. DETAILED DESCRIPTION

[0022] In the present invention, the terms "first", "second", etc. are used to describe various components, and these terms are only used to distinguish a certain component from other components.

[0023] In addition, the terms used in this specification are only used to explain the exemplary embodiments and are not intended to limit the present invention. Singular expressions may include plural expressions unless they are expressed differently in the context. It must be understood that the terms "including," "equipped with," or "having" in this specification are only used to indicate the presence of a feature, number, step, component, or combination thereof that is active, and do not preclude the presence or possible addition of one or more different features, numbers, steps, components, or combinations thereof.

[0024] When defining specific allowable errors in preparation or materials, the terms "approximately", "substantially", etc. used in this specification have meanings close to the corresponding numbers and are used to prevent any malicious infringers from improperly using the disclosure of accurate or absolute numbers provided to help understand the present disclosure.

[0025] In addition, "parts by weight" as used herein refers to a relative concept of the weight ratio of a material based on 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 material B and material C are 40 parts by weight and 60 parts by weight, respectively.

[0026] In addition, "weight % (% by weight)" is an absolute concept indicating the percentage weight of a specific material based on the total weight. In the above mixture, the contents of material A, material B, and material C are 50 weight %, 20 weight %, and 30 weight %, respectively, based on 100% of the total weight of the mixture. In this case, the total content of each component does not exceed 100 weight %.

[0027] The present invention can be modified and have various forms, and specific exemplary embodiments will be described and explained in detail below. However, it is not intended to limit the present invention to specific exemplary embodiments, and it must be understood that the present invention includes every modification, equivalent or alternative included in the spirit and technical scope of the present invention.

[0028] Hereinafter, the present invention will be described in more detail.

[0029] According to one embodiment of the present invention, there is provided a polyethylene having a narrow molecular weight distribution due to uniform reaction of ethylene and hydrogen in a reactor by increasing the input amount of hydrogen, and having a minimum polymer distribution in a low molecular weight region according to GPC and GC-FID analysis, and ... optimizing the melt index (ASTM D 1238, 190° C., 2.16 kg) and the melt flow rate ratio (MFRR, MI5 / MI6). 2.16 ) and has reduced TVOC generation, making it suitable for fiber production.

[0030] Specifically, regarding polyethylene, the melt index (ASTM D 1238, 190°C, 2.16 kg) is 15 g / 10 min to 40 g / 10 min, the melt flow rate ratio (MFRR, MI5 / MI 2.16 ) is from 2.3 to 2.7, the integrated value in the region where Log Mw is 3.0 or less in a GPC curve wherein the x-axis is log Mw and the y-axis is dw / dlogMw is from 0.8 to 1.8% of the total integrated value, and when the peak area of ​​straight-chain hydrocarbons having 3 to 32 carbon atoms is converted into a ratio relative to the peak area of ​​polyethylene in a GC-FID chart obtained by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes), the content of straight-chain hydrocarbons having 3 to 32 carbon atoms is 600 ppm or less based on 1 g of polyethylene.

[0031] In particular, when a specific metallocene catalyst as described below is used, polyethylene may have a narrow molecular weight distribution and may have reduced TVOC generation due to uniform reaction of ethylene and hydrogen in a reactor by increasing the input amount of hydrogen.

[0032] In producing polyethylene for bicomponent fibers (polypropylene resin for the inner portion and polyethylene resin for the outer portion), it is necessary to develop a polyethylene having reduced total volatile organic compounds (TVOC) due to polymer distribution in the low molecular weight region and a narrow molecular weight distribution, thereby ensuring excellent tensile strength and softness.

[0033] Hereinafter, the polyethylene of the present invention will be described in more detail.

[0034] For polyethylene, the melt index (ASTM D 1238, 190° C., 2.16 kg) is 15 to 40 g / 10 min.

[0035] Specifically, regarding polyethylene, the melt index (ASTM D 1238, 190°C, 2.16 kg) is preferably 16 g / 10 min or more, or 17 g / 10 min or more, or 17.5 g / 10 min or more, or 18 g / 10 min or more, or 18.5 g / 10 min or more, or 18.9 g / 10 min or more, and is 38 g / 10 min or less, or 35 g / 10 min or less, or 33 g / 10 min or less, or 32 g / 10 min or less, or 30 g / 10 min or less, or 29.8 g / 10 min or less.

[0036] By having a melt index as described above, the molecular weight and viscosity of the polyethylene can be optimized, and the flowability and processability can be improved.

[0037] In addition, regarding polyethylene, the melt flow rate ratio (MFRR, MI5 / MI 2.16 ) is preferably 2.3 to 2.7.

[0038] According to ASTM D1238, MFRR is the polyethylene melt index (MI5) measured at 190°C under a 5 kg load divided by the melt index (MI5) measured at 190°C under a 2.16 kg load. 2.16 ) is the value obtained.

[0039] More specifically, the melt flow rate ratio (MFRR, MI5 / MI5) measured at 190°C according to ASTM D1238 2.16 ) may preferably be 2.35 or more, or 2.4 or more, or 2.45 or more, or 2.50 or more, and 2.65 or less, or 2.6 or less, or 2.59 or less, or 2.56 or less, or 2.54 or less.

[0040] Since the polyethylene has the melt flow rate ratio as described above, the molecular weight distribution of the polyethylene can be optimized, and the fluidity and processability can be improved.

[0041] Furthermore, regarding polyethylene, in a GPC curve in which the x-axis is log Mw and the y-axis is dw / dlogMw, the integrated value in the region where Log Mw is 3.0 or less is 0.8% to 1.8% of the total integrated value.

[0042] Specifically, with respect to polyethylene, if the integrated value in the region where Log Mw is 3.0 or less in a GPC curve where the x-axis is log Mw and the y-axis is dw / dlogMw is greater than 1.6% of the total integrated value, problems such as harmful fumes, mold drooling, and odor may occur, which may reduce work stability and efficiency during processing. In this regard, the integrated value in the region where Log Mw is 3.0 or less may be preferably 1.6% or less, or 1.5% or less, or 1.4% or less, or 1.3% or less, or 1.25% or less, or 1.23% or less. However, when the integrated value in the region where Log Mw is 3.0 or less is less than 0.8%, flowability during processing may deteriorate. In this regard, the integrated value in the region where Log Mw is 3.0 or less may be preferably 0.85% or more, or 0.9% or more, or 0.93% or more, or 0.95% or more, or 0.98% or more, or 1.0% or more, or 1.02% or more.

[0043] When the polyethylene has the above-mentioned integrated value in the region where Log Mw is 3.0 or less, its molecular weight distribution can be optimized, fluidity and processability can be improved, and optimal spinning conditions can be easily achieved.

[0044] At the same time, the polyethylene according to one embodiment of the present invention can optimize the weight average molecular weight and molecular weight distribution, can minimize the occurrence of single yarns in the spinning process during the production of low denier (fine) fibers, and can improve processability (filterability) and process output by reducing the processing load of the mesh filter.

[0045] Specifically, the molecular weight distribution (Mw / Mn) of the polyethylene can be 2.0 to 2.6, preferably 2.1 or more, or 2.2 or more, or 2.25 or more, or 2.3 or more, or 2.32 or more, or 2.35 or more, and 2.55 or less, or 2.52 or less, or 2.50 or less, or 2.48 or less, or 2.45 or less, or 2.42 or less, or 2.39 or less.

[0046] In addition, the weight average molecular weight of the polyethylene can be 38,000 g / mol to 65,000 g / mol, preferably 38,500 g / mol or more, or 39,000 g / mol or more, or 39,500 g / mol or more, or 40,000 g / mol or more, or 42,000 g / mol or more, and 63,000 g / mol or less, or 60,000 g / mol or less, or 58,000 g / mol or less, or 55,000 g / mol or less, or 50,000 g / mol or less, or 49,000 g / mol or less.

[0047] In the present invention, since the polyethylene has a narrow molecular weight distribution while optimizing the melt index and weight average molecular weight as described above, it can have excellent mechanical properties and can minimize the polymer distribution in the low molecular weight region.

[0048] As used herein, the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution are values ​​converted relative to polystyrene standards, as measured using gel permeation chromatography (GPC). However, the weight average molecular weight is not limited thereto and may be measured by another method known in the art to which the present invention pertains.

[0049] For example, polyethylene samples were evaluated using a PL-GPC220 instrument produced by Waters and a Polymer Laboratories PLgel MIX-B 300 mm long column. The evaluation temperature was 160°C, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was 1 ml / min. Each sample was prepared at a concentration of 10 mg / 10 mL and injected in an amount of 200 μL. The Mw and Mn values ​​were measured using a calibration curve formed using polystyrene standards. Nine polystyrene standard samples with the following weight average molecular weights were used: 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 100000000 g / mol.

[0050] Meanwhile, polyethylene is characterized by having a narrow molecular weight distribution while optimizing the melt index and weight average molecular weight as described above, and having minimal polymer distribution in the low molecular weight region, as well as excellent mechanical properties.

[0051] The polymer distribution in the low molecular weight region of polyethylene can be confirmed by measuring the content of linear hydrocarbons having 3 to 32 carbon atoms, or 5 to 32 carbon atoms, or 6 to 32 carbon atoms, or 8 to 32 carbon atoms, or 10 to 32 carbon atoms, or 12 to 32 carbon atoms, or 14 to 32 carbon atoms by gas chromatography / flame ionization detector analysis (GC-FID, inlet and detector temperature: 300°C, residence time: 20 minutes). For example, confirmation can be performed by correcting the value obtained by the GC / FID peak area corresponding to linear hydrocarbons having 3 to 32 carbon atoms with the weight of the polyethylene sample.

[0052] Specifically, with respect to polyethylene, the content of linear hydrocarbons having 3 to 32 carbon atoms is 600 ppm or less or 80 ppm to 600 ppm, as measured by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes).

[0053] Polyethylene is characterized by having a narrow molecular weight distribution while optimizing the melt index and weight average molecular weight as described above, and having minimal polymer distribution in the low molecular weight region, as well as excellent mechanical properties.

[0054] As used herein, gas chromatography / flame ionization detector (GC-FID) analysis refers to an instrument or method for separating the contents of various sample solutions. In GC / FID, a gas chromatograph (GC) for separating various compounds is connected to a flame ionization detector (FID) for measuring the atomic mass of the substance entering from the GC. By calculating the area ratio of the GC / FID, the content of the compound can be relatively compared.

[0055] Specifically, with respect to polyethylene, the content of linear hydrocarbons having 3 to 32 carbon atoms, as measured by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes), may preferably be 580 ppm or less, or 570 ppm or less, or 560 ppm or less, or 550 ppm or less, or 548 ppm or less. However, considering the basic molecular structure and molecular weight distribution of polyethylene, the content of linear hydrocarbons having 3 to 32 carbon atoms, as measured by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes), may be 100 ppm or more, or 200 ppm or more, or 300 ppm or more, or 350 ppm or more, or 400 ppm or more, or 450 ppm or more, or 500 ppm or more, or 521 ppm or more.

[0056] Regarding polyethylene, when the peak area of ​​straight-chain hydrocarbons having 3 to 32 carbon atoms in a GC-FID chart obtained by gas chromatography / flame ionization detector analysis (GC-FID, inlet, detector temperature: 300° C., residence time: 20 minutes) is converted into a ratio relative to the peak area of ​​polyethylene, the content of straight-chain hydrocarbons having 3 to 32 carbon atoms is a value (ppm) based on 1 g of polyethylene.

[0057] Specifically, about 50 mg of a sample prepared using polyethylene was weighed and subjected to gas chromatography / flame ionization detector analysis (GC-FID) under the following conditions.

[0058] [GC / FID analysis conditions]

[0059] -GC instrument: 7890A GC system manufactured by Agilent

[0060] -GC oven: 100°C (5 minutes) - 15°C / minute - 320°C (20 minutes)

[0061] - Inlet and detector temperature: 300°C

[0062] For example, a 7890A GC system manufactured by Agilent can be used as a GC instrument, and analysis can be performed under the following GC oven conditions: the oven is held at 100° C. for 5 minutes and heated at a rate of 15° C. per minute, and then held at 320° C. for 20 minutes. At this time, measurement can be performed in the instrument at an inlet temperature and a detector temperature of 300° C.

[0063] Specifically, gas chromatography / flame ionization detector (GC-FID) analysis can measure the content of linear hydrocarbons containing 3 to 32 carbon atoms in polyethylene by subjecting the polyethylene sample to the following pretreatment process. For example, the pretreatment process is performed as follows: 0.5 g of polyethylene sample is dissolved in 10 mL of xylene, the resin component is precipitated by adding 10 mL of ethanol, and then centrifuged. The supernatant is dried with nitrogen (N2) to remove the solvent, and the product is dissolved in chloroform (CHCl3) or a mixed solvent of chloroform and acetone (CHCl3 / acetone), and the solution is injected into the measuring instrument.

[0064] In the graph obtained by GC-FID analysis performed under the above conditions, the peak area of ​​linear hydrocarbons having 3 to 32 carbon atoms was converted into a ratio relative to the peak area of ​​polyethylene, and the content (ppm) of linear hydrocarbons having 3 to 32 carbon atoms based on 1 g of polyethylene was determined.

[0065] In this analysis, the relative comparison of the polymer distribution in the low molecular weight region can be calculated by the area ratio of GC / FID. In order to confirm the composition of each peak, GC / MS analysis can be performed first. This GC / MS analysis can be performed with reference to the method described in the following experimental examples.

[0066] At the same time, the polyethylene may satisfy a density (ASTM D1505, 23°C) of 0.945 g / cm 3 to 0.965g / cm 3 of high-density polyethylene (HDPE).

[0067] More specifically, the density of polyethylene may preferably be 0.946 g / cm 3 Above, or 0.947g / cm 3 Above, or 0.948g / cm 3 Above, or 0.950g / cm 3 Above or 0.951g / cm 3 Above, and 0.963g / cm 3 Below, or 0.960g / cm 3 Below, or 0.958g / cm 3Below, or 0.956g / cm 3 Below or 0.954g / cm 3 the following.

[0068] The polyethylene according to one embodiment of the present invention may be a homopolymer of ethylene or a C 4-20 Copolymers of α-olefin monomers and ethylene.

[0069] For example, the α-olefin may include an α-olefin having 4 to 20 carbon atoms, or 4 to 15 carbon atoms, or 4 to 12 carbon atoms, specifically, one or more selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene or a mixture of two or more thereof, preferably 1-butene or 1-hexene.

[0070] More specifically, the polyethylene according to one embodiment of the present invention may be a copolymer of ethylene and 1-butene.

[0071] Specifically, the amount of the repeating unit derived from alpha-olefin included in the polyethylene can be about 5 mol % or less, or about 0 mol % to about 5 mol %. When the repeating unit derived from alpha-olefin is included in the above range, the polyethylene can show excellent processability. Preferably, based on the gross weight of the polyethylene, the content of the repeating unit derived from alpha-olefin can be about 4.8 mol % or less, or 4.5 mol % or less, or 4.2 mol % or less, or 4 mol % or less, or 3.8 mol % or less or 3.5 mol %. However, considering the effect of improving processability according to the content of the repeating unit derived from alpha-olefin controlled, based on the gross weight of the polyethylene, the content of the repeating unit derived from alpha-olefin can more preferably be about 0.2 mol % or more, about 0.5 mol % or more, or 1 mol % or more, or 1.2 mol % or more, or 1.5 mol % or more, or 1.8 mol % or more or 2 mol %.

[0072] The polyethylene of the present invention that satisfies the above physical properties has a narrow molecular weight distribution by increasing the amount of hydrogen input so that ethylene and hydrogen react uniformly in the reactor, and has a minimum polymer distribution in the low molecular weight region according to GPC and GC-FID analysis, and is obtained by optimizing the melt index (ASTM D 1238, 190°C, 2.16 kg) and melt flow rate ratio (MFRR, MI5 / MI6). 2.16 ) with reduced TVOC generation and is therefore very preferably used for producing bicomponent fibers or nonwovens.

[0073] As used herein, the term "volatile organic compounds (VOCs)" may be defined as all organic compounds present in the gas phase in the atmosphere. It is a collective term used to refer to all organic materials that may be present in the gas phase at room temperature and atmospheric pressure, such as hydrocarbons composed solely of carbon and hydrogen, halogenated hydrocarbons, and hydrocarbons containing nitrogen or sulfur. In a broader sense, semivolatile organic compounds may also be included. In this specification, volatile organic compounds may be, for example, byproducts of thermal decomposition of organic solvents or curing agents, or byproducts generated by addition reactions.

[0074] In this manual, gas chromatography / mass spectrometry (GC / MS) refers to an instrument or method for separating various sample solution contents. In GC / MS, a gas chromatography (GC) for separating various compounds is connected with a flame ionization detector (FID) for measuring the atomic mass of the material entering from GC. Residence time and quality vary because of compound type. Because GC / MS is connected to a computer storing a specific form compound library, the type of compound and its concentration thereof are identified by comparing with a library that can measure compound in solution. After determining the presence of the compound, a continuous investigation is usually carried out to analyze specific materials by GC.

[0075] In particular, regarding the polyethylene of the present invention, the emission of total volatile organic compounds (TVOC) is 150 μg / g or less, or 10 μg / g to 150 μg / g.

[0076] Specifically, regarding the polyethylene of the present invention, the emission of total volatile organic compounds (TVOC) may preferably be 150 μg / g or less, or 150 μg / g or less, or 150 μg / g or less, or 150 μg / g or less. However, considering the basic molecular structure and molecular weight distribution of the polyethylene, the emission of total volatile organic compounds (TVOC) may be 15 μg / g or more, or 30 μg / g or more, or 40 μg / g or more, or 50 μg / g or more, or 70 μg / g or more, or 90 μg / g ppm or more.

[0077] For example, total volatile organic compound (TVOC) emissions are determined by exposing a sample dissolved in a toluene standard solution to high temperature, analyzing the sample by GC / MS, etc., and adding the individual VOC values ​​produced by the test samples.

[0078] Specifically, total volatile organic compound (TVOC) emissions from polyethylene can be measured by gas chromatography / mass spectrometry thermal desorption (GC / MS-TD) after exposure to high temperature under the following conditions.

[0079] [GC / MS-TD analysis conditions]

[0080] -Sample: 20mg

[0081] - Temperature and time: 200℃, 10 minutes

[0082] -GC oven: 50°C (5 minutes) - 10°C / minute - 300°C (10 minutes)

[0083] - Column: HP-5MS

[0084] -Toluene standard solution

[0085] The total volatile organic compound (TVOC) emissions (μg / g) were calculated as shown in Equation 1 below.

[0086] [Equation 1]

[0087] VOC 化合物 =[(A 化合物 / A 标准 )×C 标准 ] / W 样品

[0088] VOC 化合物 : VOC value of a single material produced by the test sample (μg / g)

[0089] A 化合物 : Chromatographic peak area of ​​individual materials produced by the test sample

[0090] A 标准 : Peak area of ​​toluene standard solution

[0091] C 标准 : Weight of toluene injected using toluene standard solution (μg)

[0092] W 样品 : Weight of test sample (g)

[0093] Specifically, with respect to the toluene standard solution, toluene can be used alone, or at a concentration of about 0.1 μg / uL or more, or about 0.2 μg / uL or more, or about 0.5 μg / uL or more, or about 0.7 μg / uL or more, or about 0.8 μg / uL or more, or about 1.0 μg / uL or more, or about 1.2 μg / uL or more, and about 3.5 μg / uL or less, or about 3.0 μg / uL or less, or about 2.8 μg / uL or less, or about 2.5 μg / uL or less, or about 2.2 μg / uL or less, or about 2.0 μg / uL or less, or about 1.9 μg / uL or less, or about 1.7 μg / uL or less, or about 1.5 μg / uL or less, or about 1.4 μg / uL or less in a solvent such as methanol.

[0094] The results of gas chromatography / mass spectrometry thermal desorption (GC / MS-TD) analysis are values ​​(μg / g) calculated from the peak area relative to the peak area of ​​a toluene standard solution.

[0095] Meanwhile, according to another embodiment of the present invention, a method for preparing the above-mentioned polyethylene is provided.

[0096] Specifically, polyethylene is prepared by a method of polymerizing ethylene in the presence of a catalyst composition comprising a metallocene compound represented by the following Chemical Formula 1:

[0097] [Chemical Formula 1]

[0098]

[0099] In Chemical Formula 1,

[0100] B is boron,

[0101] M is a Group 4 transition metal,

[0102] R1 to R4 are each independently hydrogen, C 1-20 Alkyl, C 3-20 Cycloalkyl or C 6-20 Aryl, or R1 and R2 or R3 and R4 are connected to each other to form a C 6-60 Aromatic ring,

[0103] R5 and R6 are each independently C 1-20 Alkyl, C 3-20 Cycloalkyl or C 6-20 Aryl, or R5 and R6 are connected to each other to form C 3-60 Aliphatic ring or C 6-60 Aromatic ring,

[0104] X1 and X2 are each independently C 1-20 Alkyl or -O(CO)R', where R' is C 1-20 alkyl,

[0105] Q is a substituted or unsubstituted C containing any one or more selected from the group consisting of N, O and S. 2-60 heterocyclic rings,

[0106] Y and Y' are the elements that make up Q,

[0107] Y is N, O or S, and

[0108] Y' is an element of Q that is adjacent to Y and is either N or C.

[0109] The above-mentioned substituents are explained more specifically below.

[0110] In this specification, the following terms are defined as follows unless otherwise specified.

[0111] The hydrocarbyl group is a monovalent functional group in which a hydrogen atom is removed from a hydrocarbon, and may include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aralkenyl group, an aralkynyl group, an alkylaryl group, an alkenylaryl group, an alkynylaryl group, and the like. 1-30 The hydrocarbyl group may be C 1-20 or C 1-10 For example, the hydrocarbyl group may be a straight chain, branched chain or cyclic alkyl group. More specifically, C 1-30 The hydrocarbyl group can be a straight chain, branched or cyclic alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, a n-heptyl group, a cyclohexyl group, etc.; or an aryl group, such as a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group or a fluorenyl group. In addition, it can be an alkylaryl group, such as a methylphenyl group, an ethylphenyl group, a methylbiphenyl group, a methylnaphthyl group, etc., and can be an arylalkyl group, such as a phenylmethyl group, a phenylethyl group, a biphenylmethyl group, a naphthylmethyl group, etc. In addition, it can be an alkenyl group, such as an allyl group, a vinyl group, a propenyl group, a butenyl group, a pentenyl group, etc.

[0112] A hydrocarbyloxy group is a functional group in which a hydrocarbyl group is bonded to oxygen. Specifically, C 1-30 The hydrocarbyloxy group may be a C 1-20 or C 1-10 For example, the hydrocarbyloxy group can be a straight chain, branched chain or cyclic alkyl group. More specifically, C 1-30 The hydrocarbyloxy group can be a straight chain, branched or cyclic alkoxy group, such as a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a tert-butoxy group, a n-pentoxy group, a n-hexoxy group, a n-heptoxy group, a cyclohexyloxy group, etc.; or an aryloxy group, such as a phenoxy group, a naphthoxy group, etc.

[0113] A hydrocarbyloxyhydrocarbyl group is a functional group in which one or more hydrogen atoms of a hydrocarbyl group are replaced by one or more hydrocarbyloxy groups. 2-30 The hydrocarbyloxyhydrocarbyl group may be C 2-20 or C 2-15 For example, the alkyloxyalkyl group can be a straight chain, branched chain or cyclic alkyl group. More specifically, C 2-30 The hydrocarbon oxide group can be an alkoxyalkyl group, such as a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an isopropoxymethyl group, an isopropoxyethyl group, an isopropoxyhexyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, a tert-butoxyhexyl group, etc.; or an aryloxyalkyl group, such as a phenoxyhexyl group, etc.

[0114] The hydrocarbyl(oxy)silyl group is a functional group in which 1 to 3 hydrogen atoms of -SiH3 are replaced by 1 to 3 hydrocarbyl groups or hydrocarbyloxy groups. 1-30 The hydrocarbyl(oxy)silyl group may be a C 1-20 、C 1-15 、C 1-10 or C 1-5 More specifically, C 1-30 The hydrocarbyl(oxy)silyl group may be an alkylsilyl group, such as a methylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a dimethylethylsilyl group, a diethylmethylsilyl group, a dimethylpropylsilyl group, etc.; an alkoxysilyl group, such as a methoxysilyl group, a dimethoxysilyl group, a trimethoxysilyl group, a dimethoxyethoxysilyl group, etc.; or an alkoxyalkylsilyl group, such as a methoxydimethylsilyl group, a diethoxymethylsilyl group, a dimethoxypropylsilyl group, etc.

[0115] In addition, C 1-20 A silylalkyl group is a functional group in which one or more hydrogen atoms of a hydrocarbon group are replaced by a silyl group. Specifically, the silyl group may be -SiH3 or a hydrocarbon (oxy) silyl group. Specifically, C 1-20 The silyl hydrocarbyl group may be C 1-15 or C 1-10 More specifically, C 1-20 The silyl hydrocarbyl group can be a silylalkyl group, such as -CH2-SiH3, etc.; an alkylsilylalkyl group, such as a methylsilylmethyl group, a methylsilylethyl group, a dimethylsilylmethyl group, a trimethylsilylmethyl group, a dimethylethylsilylmethyl group, a diethylmethylsilylmethyl group, a dimethylpropylsilylmethyl group, etc.; or an alkoxysilylalkyl group, such as a dimethylethoxysilylpropyl group, etc.

[0116] The halogen may be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

[0117] The alkyl group may be a straight chain or a branched chain. 1-20 The alkyl group can be C 1-20 Straight chain alkyl; C 1-10 Straight chain alkyl; C 1-5 Straight chain alkyl; C 3-20 Straight chain alkyl; C 3-15 Branched alkyl; or C 3-10More specifically, C 1-20 The alkyl group may be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, etc., but is not limited thereto. Meanwhile, in this specification, "iPr" means an isopropyl group.

[0118] The cycloalkyl group may be a cyclic alkyl group. Specifically, C 3-20 The cycloalkyl group may be C 3-20 Cyclic alkyl; C 3-15 Cyclic alkyl; or C 3-10 Cyclic alkyl. More specifically, the cycloalkyl group may 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 is not limited thereto. Meanwhile, in this specification, "Cy" means a cycloalkyl group having 3 to 6 carbon atoms.

[0119] The alkenyl group may be a straight chain, branched chain or cyclic alkenyl group. 2-20 Alkenyl 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 More specifically, C 2-20 The alkenyl group may be ethenyl, propenyl, butenyl, pentenyl or cyclohexenyl, etc.

[0120] The alkoxy group may be a straight chain, branched chain or cyclic alkoxy group. 1-20 The alkoxy group 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; C 3-15 Branched or cyclic alkoxy; or C 3-10 More specifically, C 1-20 The alkoxy group may be methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, cycloheptyloxy, or the like, but is not limited thereto.

[0121] Alkoxyalkyl groups have a a -OR bThe structure of alkyl (-R a ) is replaced by one or more hydrogen atoms of an alkoxy group (-OR b ) substituted substituent. Specifically, C 2-20 The alkoxyalkyl group may be methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, tert-butoxyhexyl, or the like, but is not limited thereto.

[0122] The aryl group includes monocyclic, bicyclic or tricyclic aromatic hydrocarbons. According to one embodiment of the present invention, the aryl group may have 6 to 60 carbon atoms or 6 to 20 carbon atoms, and the aryl group is specifically phenyl, naphthyl, anthracenyl, dimethylphenylamino, anisole, etc., but is not limited thereto.

[0123] The heteroaryl group is a heteroaryl group containing one or more of N, O and S as a heteroatom, and the number of carbon atoms may be, but is not particularly limited to, 2 to 60 or 2 to 20. Examples of the heteroaryl group may include xanthene, thioanthene, thiophene, furan, pyrrole, imidazole, thiazole, oxazole, oxadiazole, triazole, pyridyl, bipyridyl, pyrimidyl, triazine, acridinyl, pyridazine, pyrazinyl, quinolyl, quinazolinyl, quinoxazoline, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, isoquinolyl, indole, carbazole, benzoxazole, benzimidazole, benzothiazole, benzocarbazole, benzothiophene, dibenzothiophene, benzofuranyl, o-phenanthroline, isoxazolyl, thiadiazolyl, phenothiazinyl, dibenzofuranyl and the like, but are not limited thereto.

[0124] Hydrocarbyl groups refer to monovalent hydrocarbon compounds, including alkyl groups, alkenyl groups, alkynyl groups, aryl groups, aralkyl groups, aralkenyl groups, aralkynyl groups, alkylaryl groups, alkenylaryl groups, alkynylaryl groups, etc. For example, the hydrocarbyl group can be a straight chain, branched chain or cyclic alkyl group. More specifically, the hydrocarbyl group with 1 to 30 carbon atoms can be a straight chain, branched chain or cyclic alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group. An n-heptyl group, a cyclohexyl group, etc.; or an aryl group, such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, etc. In addition, it can be an alkylaryl group, such as methylphenyl, ethylphenyl, methylbiphenyl, methylnaphthyl, etc.; or an arylalkyl group, such as phenylmethyl, phenylethyl, biphenylmethyl, naphthylmethyl, etc. It may also be an alkenyl group such as allyl, vinyl, propenyl, butenyl, pentenyl, and the like.

[0125] The heterocyclic ring includes all aliphatic rings containing any one or more selected from the group consisting of N, O and S, and aromatic rings containing any one or more selected from the group consisting of N, O and S.

[0126] In addition, the Group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf) or (Rf), specifically, titanium (Ti), zirconium (Zr), or hafnium (Hf), more specifically, zirconium (Zr) or hafnium (Hf), but not limited thereto.

[0127] The above substituents may be optionally substituted by one or more substituents selected from the group consisting of hydroxy, halogen, alkyl, alkenyl, aryl or alkoxy, alkyl, alkenyl, aryl or alkoxy containing one or more hetero atoms among hetero atoms of Groups 14 to 16, amino, silyl, alkylsilyl or alkoxysilyl, phosphine, phosphide, sulfonate and sulfone, within the range of exhibiting the same or similar effects as the desired effects.

[0128] As the metallocene catalyst for ethylene polymerization of the present invention, a catalyst precursor including one or more metallocene compounds represented by Chemical Formula 1 may be used.

[0129] The metallocene compound represented by Chemical Formula 1 employs a bridge structure containing a boron anion, unlike the commonly used constrained geometry catalyst (CGC) precursor. Conventional CGC precursors have a neutral bridge structure containing silicon, resulting in negatively charged ligand units. Due to this structural limitation, achieving various physical properties during the preparation of olefin polymers is difficult.

[0130] In contrast, the metallocene compound represented by Chemical Formula 1 according to the present invention can have a neutral ligand unit because the bridge structure is negatively charged. The ligand unit of the present invention is a heterocyclic ring Q of Chemical Formula 1, wherein Y, as an element of Q, coordinates with the metal, and Y', as an element of Q, is adjacent to Y and connected to the bridge. Therefore, in the present invention, by using various neutral ligand units that meet the above structure, catalysts with higher activity and higher copolymerizability than existing CGC precursors can be prepared.

[0131] In addition, the metallocene compound represented by Chemical Formula 1 includes an alkyl group or a carboxylate group as a metal substituent, which acts as a good leaving group to promote the reaction with a co-catalyst such as MAO, thereby improving the activity.

[0132] Therefore, when using metallocene compounds, it is possible to maintain a high melt index of polyethylene, reduce low molecular weight components, narrow the molecular weight distribution, increase the SCB content to increase the effective number of physical crosslinks of the molecules, and thus prepare polyethylene with reduced total volatile organic compound (TVOC) generation.

[0133] Specifically, in Chemical Formula 1, M may be zirconium (Zr).

[0134] In addition, in Chemical Formula 1, R1 to R4 are each independently hydrogen, C 1-10 Alkyl or C6-20 aryl group, and R1 and R2 or R3 and R4 are connected to each other to form a C with or without substituents 6-60 Aromatic ring. Preferably, R1 to R4 are each independently hydrogen or methyl, or R1 and R2 or R3 and R4 are linked 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 may be unsubstituted or substituted with one to four substituents selected from the group consisting of a methyl group, a tert-butyl group, and a 4-tert-butylphenyl group.

[0135] In addition, in Chemical Formula 1, R5 and R6 are each independently C 1-10 Alkyl or C 6-20 Aryl, or R5 and R6 are connected to each other to form C 3-20 Aromatic ring or C 6-20 Aromatic ring. Preferably, R5 and R6 are each independently a methyl group or a phenyl group, or R5 and R6 are linked to each other to form a cyclooctane ring.

[0136] More preferably, R5 and R6 may each be a phenyl group.

[0137] In addition, in Chemical Formula 1, X1 and X2 may each independently be a methyl group or an acetate group.

[0138] In addition, in Chemical Formula 1, R' may be a methyl group.

[0139] In addition, in Chemical Formula 1, X1 and X2 may be the same as each other.

[0140] In addition, in Chemical Formula 1, Q may be C with or without a substituent. 2-20 A heterocyclic ring containing any one or more selected from the group consisting of N, O and S.

[0141] Preferably, Q may 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 the group consisting of methyl, isopropyl and diphenylamino.

[0142] More preferably, Q may 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 the group consisting of a methyl group, an isopropyl group, and a diphenylamino group.

[0143] In addition, in Chemical Formula 1, Y is a heteroatom coordinated with the metal M. Preferably, Y may be N.

[0144] Meanwhile, specific examples of the second metallocene compound represented by Chemical Formula 1 may include compounds represented by the following structural formulas, but the present invention is not limited thereto:

[0145]

[0146]

[0147] When X1 and X2 are the same, the metallocene compound represented by Chemical Formula 1 can be prepared by, for example, the method shown in the following Reaction Scheme 1, but is not limited thereto and can be prepared according to known methods for preparing organic compounds and metallocene compounds. This preparation method will be more specifically embodied in the preparation examples described below.

[0148] [Reaction Scheme 1]

[0149]

[0150] In Reaction Scheme 1, B, M, R1 to R6, X1, X2, Q, Y and Y' are the same as defined in Chemical Formula 1.

[0151] Meanwhile, in this specification, equivalent (eq.) means molar equivalent.

[0152] The catalyst composition according to one embodiment of the present invention may include the metallocene compound of Chemical Formula 1 as a single catalyst.

[0153] In this regard, the catalyst composition may comprise a metallocene compound as a single component, or may be in the form of a supported metallocene catalyst comprising the metallocene compound and a support. When a supported metallocene catalyst is used, the morphology and physical properties of the polyethylene to be prepared can be improved, and the catalyst composition may be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes.

[0154] Specifically, as a support, a support having highly active hydroxyl groups, silanol groups or siloxane groups on its surface can be used. For this purpose, a support whose surface has been modified by calcination or a support whose surface has been dehydrated by drying can be used. For example, silica prepared by calcining silica gel, silica dried at high temperature, silica-alumina and silica-magnesia can be used. These generally include oxides, carbonates, sulfates and nitrates, such as Na2O, K2CO3, BaSO4 and Mg(NO3)2.

[0155] The support can be calcined or dried at a temperature of about 200°C to 600°C or about 250°C to 600°C. When the calcination or drying temperature of the support is low, excess moisture remains in the support, and it is believed that the moisture on the surface may react with the co-catalyst. In addition, the co-catalyst loading rate may be relatively high due to the excessive number of hydroxyl groups, but this requires a large amount of co-catalyst. When the drying or calcination temperature is too high, the pores on the support surface may merge with each other, reducing the surface area, and many hydroxyl groups or silanol groups may be lost from the surface, leaving only siloxane groups. Therefore, it is believed that the reaction sites with the co-catalyst may be reduced.

[0156] The amount of hydroxyl groups on the support surface is preferably 0.1 mmol / g to 10 mmol / g, more preferably 0.5 mmol / g to 5 mmol / g. The amount of hydroxyl groups on the support surface can be controlled by the preparation method and preparation conditions or drying conditions of the support, for example, temperature, time, vacuum or spray drying, etc.

[0157] When the amount of hydroxyl groups is less than 0.1 mmol / g, the reaction sites with the co-catalyst may be reduced. When the amount of hydroxyl groups exceeds 10 mmol / g, in addition to the hydroxyl groups existing on the surface of the support particles, they may also be generated by moisture, which is undesirable.

[0158] For example, the amount of hydroxyl groups on the support surface may be 0.1 mmol / g to 10 mmol / g or 0.5 mmol / g to 5 mmol / g. The amount of hydroxyl groups on the support surface may be controlled by the preparation method and preparation conditions or drying conditions of the support, for example, temperature, time, vacuum or spray drying, etc. When the amount of hydroxyl groups is too small, the reaction sites with the co-catalyst may be reduced. When the amount of hydroxyl groups is too large, in addition to the hydroxyl groups present on the surface of the support particles, it may also be caused by moisture.

[0159] Among the aforementioned supports, silica prepared by calcining silica (particularly silica gel) rarely releases the catalyst from the support surface during propylene polymerization. This is because the functional groups of the compound of Chemical Formula 1 are chemically bonded to and supported on the silica support. Therefore, when polyethylene is produced by slurry polymerization or gas phase polymerization, fouling, where polymer particles adhere to reactor walls or to each other, can be minimized.

[0160] In addition, when supported on a support, the supported amount of the compound of Chemical Formula 1 can be about 10 μmol or more or about 30 μmol or more, and about 100 μmol or less or about 80 μmol or less, based on the weight of the support, for example, about 1 g of silica. When supported within the above content range, the supported catalyst may exhibit appropriate activity, which is advantageous in terms of maintaining catalytic activity and economic feasibility.

[0161] The catalyst composition may further comprise one or more cocatalysts as well as the metallocene compound and the support described above.

[0162] Any cocatalyst can be used as a cocatalyst, as long as it can be used in the presence of a conventional metallocene catalyst for olefin polymerization. Such a cocatalyst allows for bonding between the hydroxyl groups on the support and the Group 13 transition metal. In addition, because the cocatalyst is present only on the support surface, it may contribute to the unique properties of the specific mixed catalyst composition of the present application without the fouling phenomenon of polymer particles adhering to the reactor walls or to each other.

[0163] Furthermore, the catalyst composition according to the present invention may comprise one or more co-catalyst compounds other than the metallocene compound, which are selected from the group consisting of compounds represented by the following Chemical Formulas 2 to 4:

[0164] [Chemical Formula 2]

[0165] -[Al(R 10 )-O] a -

[0166] In Chemical Formula 2,

[0167] R 10 is halogen or substituted or unsubstituted C 1-20 a hydrocarbon group; and

[0168] a is an integer greater than 2,

[0169] [Chemical Formula 3]

[0170] D(R 11 )3

[0171] In Chemical Formula 3,

[0172] D is aluminum or boron; and

[0173] R 11 is halogen or substituted or unsubstituted C 1-20 Hydrocarbon group,

[0174] [Chemical Formula 4]

[0175] [LH] + [ZA4] - or [L] + [ZA4] -

[0176] In Chemical Formula 4,

[0177] L is a neutral or cationic Lewis base;

[0178] H is a hydrogen atom;

[0179] Z is a Group 13 element; and

[0180] A is each independently C 6-40 Aryl or C 1-20 Alkyl, where C 6-40 Aryl or C 1-20 The alkyl group is unsubstituted or substituted by one or more substituted groups selected from halogen, C 1-20 Alkyl, C 1-20 Alkoxy and C 6-40 The substituents are substituted with the group consisting of allyloxy groups.

[0181] Specifically, in Chemical Formula 4, [LH] + It is a Bronsted acid.

[0182] The compound represented by Chemical Formula 2 may be used as an alkylating agent and an activating agent, the compound represented by Chemical Formula 3 may be used as an alkylating agent, and the compound represented by Chemical Formula 4 may be used as an activating agent.

[0183] The compound represented by Chemical Formula 2 is not particularly limited as long as it is an alkylaluminoxane, for example, it is methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc., preferably, methylaluminoxane.

[0184] The compound represented by Chemical Formula 3 is not particularly limited as long as it is an alkyl metal compound, and may be, for example, trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, and the like, and may preferably be selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0185] The compound represented by Chemical Formula 4 may include triethylammonium tetraphenylboron, tributylammonium tetraphenylboron, trimethylammonium tetraphenylboron, tripropylammonium tetraphenylboron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, trimethylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetra(pentafluorophenyl)boron, N,N-diethylanilinium tetraphenylboron, N,N-diethylanilinium tetra(pentafluorophenyl)boron, diethylammonium tetra(pentafluorophenyl)boron, triphenylphosphine tetraphenylboron, trimethylphosphine tetraphenylboron, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammonium tetraphenylaluminum, trimethylammonium tetra (p-Tolyl) aluminum, tripropylammonium tetra(p-tolyl) aluminum, triethylammonium tetra(o,p-dimethylphenyl) aluminum, tributylaluminum tetra(p-trifluoromethylphenyl) aluminum, trimethylammonium tetra(p-trifluoromethylphenyl) aluminum, tributylammonium tetra(pentafluorophenyl) aluminum, N,N-diethylanilinium tetraphenylaluminum, N,N-diethylanilinium tetra(pentafluorophenyl) aluminum, diethylammonium tetra(pentafluorophenyl) aluminum, triphenylphosphine tetraphenylaluminum, trimethylphosphine tetraphenylaluminum, tripropylammonium tetra(p-tolyl) boron, triethylammonium tetra(o,p-dimethylphenyl) boron, tributylammonium tetra(p-trifluoromethylphenyl) boron, triphenylcarbonium tetra(p-trifluoromethylphenyl) boron, triphenylcarbonium tetra(pentafluorophenyl) boron, etc. Preferably, aluminoxane can be used, and more preferably, methylaluminoxane (MAO), which is an alkylaluminoxane, can be used.

[0186] In addition, the catalyst composition may include a co-catalyst and a metallocene compound of Chemical Formula 1 in a molar ratio of about 1:1 to about 1:10000, preferably about 1:1 to about 1:1000, and more preferably about 1:10 to about 1:100. In this regard, when the molar ratio is less than about 1, the metal content of the co-catalyst is too small, so that the formation of catalytically active species is poor, resulting in reduced activity. When the molar ratio exceeds about 10000, the metal of the co-catalyst may act as a catalyst poison.

[0187] The loading amount of the co-catalyst may be about 3 mmol to about 25 mmol, or about 5 mmol to about 20 mmol, based on 1 g of the support.

[0188] Meanwhile, the catalyst composition can be prepared by a method for preparing a catalyst composition comprising a carrier on which a cocatalyst and a metallocene compound are supported, the method comprising the steps of supporting the cocatalyst on the carrier; and supporting the metallocene compound on the carrier having supported the cocatalyst.

[0189] In this method, the loading conditions are not particularly limited, and the loading can be performed within a range known to those skilled in the art. For example, high temperature loading and low temperature loading can be appropriately performed, and the loading temperature can be, for example, in the range of about -30°C to about 150°C, preferably about 50°C to about 98°C or about 55°C to about 95°C. The loading time can be appropriately controlled according to the amount of the first metallocene compound to be loaded. After removing the reaction solvent by filtration or reduced pressure distillation, the loaded catalyst so reacted can be used as is, and if necessary, can be used after Soxhlet filtration using an aromatic hydrocarbon (such as toluene).

[0190] In addition, the preparation of the supported catalyst can be carried out in the presence or absence of a solvent. When a solvent is used, suitable solvents may include aliphatic hydrocarbon solvents (such as hexane or pentane), aromatic hydrocarbon solvents (such as toluene or benzene), hydrocarbon solvents substituted with chlorine atoms (such as dichloromethane), ether solvents (such as diethyl ether or tetrahydrofuran (THF)), organic solvents (such as acetone, ethyl acetate), etc. Hexane, heptane, toluene or dichloromethane are preferred.

[0191] Meanwhile, the polyethylene according to one embodiment of the present invention may be prepared by a method including the step of polymerizing ethylene in the presence of a catalyst composition including a metallocene compound.

[0192] The method for preparing polyethylene can be carried out by a slurry polymerization process using ethylene as a raw material or using ethylene and α-olefin as raw materials in the presence of the above-mentioned catalyst composition and by applying general equipment and contact technology.

[0193] The method for preparing polyethylene may be to homopolymerize ethylene or copolymerize ethylene and α-olefin using a continuous slurry polymerization reactor, a ring type slurry reactor, etc., but is not limited thereto.

[0194] In addition, the α-olefin may include an α-olefin having 4 to 20 carbon atoms, or 4 to 15 carbon atoms, or 4 to 12 carbon atoms. Specifically, the α-olefin may be one or more selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene, or a mixture of two or more thereof.

[0195] Specifically, in the process for producing polyethylene, for example, 1-butene can be used as the α-olefin.

[0196] Meanwhile, during the copolymerization step, the α-olefin comonomer can be injected in an amount such that the polyethylene contains an appropriate amount of repeating units derived from the α-olefin. For example, the α-olefin comonomer can be injected in an amount such that the polyethylene obtained through the copolymerization contains repeating units derived from the α-olefin in an amount of about 5 mol% or less, or from about 0 mol% to about 5 mol%. Specifically, the amount of α-olefin comonomer injected can be controlled within the above-mentioned range with reference to the content of repeating units derived from the α-olefin contained in the polyethylene.

[0197] For example, the copolymerization step can be carried out by making the ethylene based on 1 mole be about 0.05 mole or 0 mole to about 0.05 mole of alpha-olefin reaction.When allowing to react within the above range, polyethylene may show excellent processability.Preferably, based on 1 mole of ethylene, alpha-olefin can be with about 0.048 mole or below 0.045 mole or below 0.042 mole or below 0.04 mole or below 0.038 mole or below 0.035 mole amount reaction.Considering the effect of improving processability according to the content of the repeating unit being derived from alpha-olefin of control, based on 1 mole of ethylene, alpha-olefin can be with about 0.005 mole or above 0.01 mole or above 0.012 mole or above 0.015 mole or above 0.018 mole or above 0.02 mole amount reaction.

[0198] Specifically, the copolymerization step can be performed by injecting 10 mL / min or 0 mL / min to 10 mL / min of α-olefins while injecting 10 kg / hr of ethylene. Alpha-olefin monomers can be injected within the above range so that an appropriate amount of repeating units derived from α-olefins are included in the polyethylene. More specifically, when injecting 10 kg / hr of ethylene, α-olefins can react with an amount of less than 8.0 mL / min, or less than 6.0 mL / min, or less than 5.0 mL / min, or less than 4.5 mL / min, or less than 4.2 mL / min, or less than 4.0 mL / min, or less than 3.8 mL / min, or less than 3.5 mL / min, or less than 3.0 mL / min, or less than 2.6 mL / min. However, considering the effect of improving processability according to controlling the content of repeating units derived from α-olefin, when 10 kg / hr of ethylene is injected, α-olefin may be reacted in an amount of 0.1 mL / min or more, or 0.5 mL / min or more, or 1.0 mL / min or more, or 1.3 mL / min or more, or 1.5 mL / min or more, or 1.8 mL / min or more, or 1.9 mL / min or more, or 2.0 mL / min or more, or 2.1 mL / min or more.

[0199] In addition, the polymerization temperature may be about 25° C. to about 500° C., or about 25° C. to about 300° C., or about 30° C. to about 200° C., or about 50° C. to about 150° C., or about 60° C. to about 120° C. In addition, the polymerization pressure may be about 1 kgf / cm 2 to about 100kgf / cm 2 , or about 1kgf / cm 2 to about 50kgf / cm 2 , or about 5kgf / cm 2 to about 45kgf / cm 2 , or about 7kgf / cm 2 to about 40kgf / cm 2 , or about 9kgf / cm 2 to about 35kgf / cm 2 .

[0200] The catalyst composition comprising the metallocene compound of Chemical Formula 1 according to the present invention can be injected after being dissolved or diluted in the following solvents: aliphatic hydrocarbon solvents having 5 to 12 carbon atoms, for example, pentane, hexane, heptane, nonane, decane and isomers thereof; and aromatic hydrocarbon solvents such as toluene and benzene; or hydrocarbon solvents substituted with chlorine atoms such as dichloromethane and chlorobenzene. The solvent used herein is preferably used after being treated with a small amount of alkylaluminum to remove a small amount of water or air (as a catalyst poison). It is possible to further use a cocatalyst.

[0201] In addition, the polymerization step can be carried out by injecting about 15ppm to about 800ppm of hydrogen based on the amount of ethylene. Preferably, based on the amount of ethylene, the injection amount of hydrogen can be more than about 20ppm, or more than about 25ppm, or more than about 30ppm, or more than about 50ppm, or more than about 60ppm, or more than about 80ppm, or more than about 90ppm, or more than about 95ppm, or more than about 100ppm, and less than about 500ppm, or less than about 400ppm, or less than about 350ppm, or less than about 300ppm, or less than about 250ppm, or less than about 200ppm, or less than about 180ppm, or less than about 170ppm, or less than about 165ppm, or less than about 160ppm, or less than about 155ppm. For example, when injecting 10kg / hr of ethylene, hydrogen can be injected with an amount of about 0.15g / hr to about 8g / hr, and preferred range is the same as above. More specifically, in the polymerization step, when 10 kg / hr of ethylene is injected, hydrogen may be injected in an amount of about 1.09 g / hr to about 1.51 g / hr.

[0202] In such a method for polymerizing ethylene, the catalyst composition comprising the metallocene compound of the present invention can exhibit high catalytic activity. For example, in the process of ethylene polymerization, when calculated as the ratio of the weight of polyethylene produced (kg PE) per unit time (hr) relative to the weight of the catalyst composition used (g), the catalytic activity can be about 4.0 kg PE / g cat hr or more, or about 4.0 kg PE / g cat hr to about 50 kg PE / g cat hr. Specifically, the activity of the catalyst composition can be about 4.2 kg PE / g cat hr or more, or about 4.3 kg PE / g cat hr or more, or about 4.5 kg PE / g cat hr or more, or about 40 kg PE / g cat hr or less, or about 30 kg PE / g cat hr or less, or about 15 kg PE / g cat hr or less.

[0203] The method for preparing polyethylene can provide polyethylene having excellent physical properties by conducting slurry polymerization in the presence of the above-mentioned catalyst composition.

[0204] In particular, the catalyst composition including the metallocene compound of Chemical Formula 1 according to the present invention may exhibit high activity as described above during homopolymerization of ethylene or copolymerization of ethylene and α-olefin.

[0205] The polyethylene prepared by the method of one embodiment as described above has a narrow molecular weight distribution by increasing the amount of hydrogen input so that ethylene and hydrogen react uniformly in the reactor, and has a minimum polymer distribution in the low molecular weight region according to GPC and GC-FID analysis, and optimizes the melt index (ASTM D 1238, 190°C, 2.16 kg) and melt flow rate ratio (MFRR, MI5 / MI6). 2.16 ) with significantly reduced TVOC generation, making it suitable for fiber production.

[0206] Specifically, a spunbonded nonwoven fabric made of the polyethylene fiber is provided.

[0207] For example, to improve the surface texture, a polypropylene resin is mixed with the above-mentioned polyethylene resin and co-extruded to produce a bicomponent fiber, wherein the polypropylene resin or polyethylene terephthalate resin is used for the inner portion and the polyethylene resin is used for the outer portion, thereby providing a nonwoven fabric with improved texture and softness. In particular, when the polyethylene of the present invention is used, the occurrence of single yarns can be minimized even in a bicomponent fiber spinning process performed at high temperatures, compared to a conventional fiber spinning process. As a result, the fiber is less likely to break, and the generation of smoke can be significantly reduced.

[0208] Hereinafter, preferred exemplary embodiments are provided to better understand the present invention. However, the following exemplary embodiments are provided only to more easily understand the present invention, but the content of the present invention is not limited thereto.

[0209] Example

[0210] [Preparation of catalyst precursor]

[0211] Synthesis example 1

[0212]

[0213] 2-Bromopyridine (1 equivalent) was dissolved in tetrahydrofuran (0.1 M), and then n-butyllithium (1 equivalent) was slowly added dropwise at -90°C, followed by stirring at the same temperature for 1 hour. Chlorodiphenylborane (1 equivalent) was then dissolved in toluene (0.3 M) and slowly added dropwise to the first reaction product at -78°C, followed by stirring for 1 hour. Thereafter, the mixture was stirred at room temperature for 12 hours, the solvent was dried under vacuum, toluene was added, and the filtrate obtained by removing the solid through a filter was dried under vacuum to obtain diphenyl(pyridin-2-yl)borane.

[0214] Diphenyl(pyridin-2-yl)borane (1 equivalent) was dissolved in tetrahydrofuran (0.1 M), and a solution of tetramethylcyclopentadienyllithium (Li(CpMe4), 1 equivalent) dissolved in tetrahydrofuran (0.1 M) was slowly added dropwise at 0° C., followed by stirring at room temperature overnight. The solvent was dried under vacuum, toluene / ether (volume ratio of 3 / 1, 0.3 M) was introduced to dissolve, and MCl4 (1 eq.) was mixed with toluene (0.2 M), then introduced at -78° C., and then stirred at room temperature overnight. When the reaction was complete, the solvent was dried under vacuum, dichloromethane was introduced, and the salt was removed by filtering. The filtrate was dried under vacuum and then recrystallized by adding dichloromethane / hexane. The resulting solid was filtered and dried under vacuum to obtain dichloro{diphenyl(pyridin-2-yl-κN)(η 5 -2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl)zirconium(IV)borate.

[0215] Dichloro{diphenyl(pyridin-2-yl-κN)(η 5-2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl) zirconium (IV) boronic acid (1 equivalent) was dissolved in toluene / diethyl ether (volume ratio 3 / 1, 0.3 M), and then a solution of methyl lithium (2 equivalents) dissolved in hexane or diethyl ether was slowly added dropwise at -78 ° C., followed by stirring at room temperature for 12 hours. When the reaction was complete, the solvent was dried under vacuum, dichloromethane was introduced, and the salt was removed by filtering. The filtrate was dried under vacuum and then recrystallized by adding dichloromethane / hexane. The resulting solid was filtered and dried under vacuum to obtain the precursor compound.

[0216] 1 H NMR (500MHz, CDCl3, ppm): δ8.32(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)

[0217] Comparative Synthesis Example 1

[0218] Tert-butyl-O-(CH2)6-Cl was prepared by the method described in the literature (Tetrahedron Lett. 2951 (1988)) using 6-chlorohexanol and reacted with sodium cyclopentadienyl (NaCp) to obtain tert-butyl-O-(CH2)6-C5H5 (yield 60%, bp 80°C / 0.1 mmHg).

[0219] In addition, tert-butyl-O-(CH2)6-C5H5 was dissolved in THF at -78°C, and n-butyllithium (n-BuLi) was slowly added thereto. Thereafter, it was heated to room temperature and reacted for 8 hours. The lithium salt solution synthesized as described above was slowly added to a ZrCl4(THF)2 (170 g, 4.50 mmol) / THF (30 mL) suspension at -78°C, and further reacted at room temperature for about 6 hours. All volatiles were removed by vacuum drying, and the resulting oily liquid material was filtered by adding hexane. The filtered solution was dried under vacuum, and hexane was added at low temperature (-20°C) to obtain a precipitate. The resulting precipitate was filtered at low temperature to obtain a white solid [t-Bu-O-(CH2)6-C5H4]2ZrCl2 compound (yield 92%).

[0220]

[0221] 1H NMR (300MHz, CDCl3): 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).

[0222] 13 C NMR (CDCl3): 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.61, 30.14, 29.18, 27.58, 26.00.

[0223] Comparative Synthesis Example 2

[0224] Preparation of ligand compounds

[0225] 50 g of Mg(s) was added to a 10 L reactor at room temperature, followed by 300 mL of THF. About 0.5 g of I2 was added, and the reactor temperature was maintained at 50°C. After the reactor temperature stabilized, 250 g of 6-tert-butoxyhexyl chloride was added to the reactor at a rate of 5 mL / min using a feed pump. By adding 6-tert-butoxyhexyl chloride, an increase of about 4°C to 5°C in the reactor temperature was observed. The mixture was stirred for 12 hours while continuously adding 6-tert-butoxyhexyl chloride. After reacting for 12 hours, a black reaction solution was obtained. 2 mL of the resulting black solution was taken, and water was added thereto to obtain an organic layer, which was then 1 H-NMR analysis identified the product as 6-tert-butoxyhexane. The Grignard reaction was successful using 6-tert-butoxyhexane. Thus, 6-tert-butoxyhexyl magnesium chloride was synthesized.

[0226] 500g of methyltrichlorosilyl (MeSiCl3) and 1L of THF were added to the reactor, and the reactor temperature was then cooled to -20°C. 560g of synthesized 6-tert-butoxyhexyl magnesium chloride was added to the reactor at a rate of 5mL / min using a feed pump. After completing the Grignard reagent feed, the mixture was stirred for 12 hours while slowly raising the reactor temperature to room temperature. After 12 hours of reaction, the formation of a white MgCl2 salt was observed. 4L of hexane was added thereto, and the salt was removed by a labdori to obtain a filtered solution. The filtered solution thus obtained was added to the reactor, and the hexane was then removed at 70°C to obtain a light yellow liquid. The liquid thus obtained was purified by a filtration step. 1 The compound was identified as the desired methyl(6-tert-butoxyhexyl)dichlorosilane by H-NMR.

[0227] 1H-NMR(CDCl3): 3.3(t,2H),1.5(m,3H),1.3(m,5H),1.2(s,9H),1.1(m,2H),0.7(s,3H).

[0228] 1.2 moles (150 g) of tetramethylcyclopentadiene and 2.4 L of THF were added to the reactor, and the reactor temperature was then cooled to -20 ° C. 480 mL of n-BuLi was added to the reactor at a rate of 5 mL / min using a feed pump. After adding n-BuLi, the mixture was stirred for 12 hours while slowly raising the reactor temperature to room temperature. After reacting for 12 hours, an equivalent of methyl (6-tert-butoxyhexyl) dichlorosilane (326 g, 350 mL) was rapidly added to the reactor. The mixture was stirred for 12 hours while slowly raising the reactor temperature to room temperature. Then, the reactor temperature was cooled to 0 ° C, and then 2 equivalents of t-BuNH2 were added. The mixture was stirred for 12 hours while slowly raising the reactor temperature to room temperature. After reacting for 12 hours, tetrahydrofuran was removed and 4 L of hexane was added thereto, and the salt was removed by labdori to obtain a filtered solution. The filtered solution was added to the reactor, and then the hexane was removed at 70 ° C to obtain a yellow solution. The yellow solution thus obtained was purified by HPLC. 1 The product was identified as methyl(6-tert-butoxyhexyl)(tetramethyl CpH)tert-butylaminosilane by H-NMR.

[0229] Preparation of metallocene compounds

[0230] TiCl3(THF)3 (10 mmol) was quickly added to the dilithium salt of the ligand, which was synthesized from n-BuLi and the ligand compound dimethyl(tetramethylcyclopentadienyl)tert-butylaminosilane in a THF solution at -78°C. The reaction solution was stirred for 12 hours while the temperature was slowly raised from -78°C to room temperature. After stirring for 12 hours, an equivalent amount of PbCl2 (10 mmol) was added to the reaction solution at room temperature, followed by stirring for 12 hours. After stirring for 12 hours, a dark black solution with a blue color was obtained. After removing THF from the resulting reaction solution, hexane was added to filter the product. After removing hexane from the filtered solution, the solution was filtered. 1 H-NMR identified it as (tBu-O-(CH2)6)(CH3)Si(C5(CH3)4)(tBu-N)TiCl2 compound, which was the desired [methyl(6-tert-butoxyhexyl)silyl(η5-tetramethylCp)(tert-butylamino)]TiCl2.

[0231]

[0232] 1H-NMR (CDCl3): 3.3 (s, 4H), 2.2 (s, 6H), 2.1 (s, 6H), 1.8 ~ 0.8 (m), 1.4 (s, 9H), 1.2 (s, 9H), 0.7 (s, 3H).

[0233] [Preparation of supported catalyst]

[0234] Preparation Example 1

[0235] 50 mL of toluene was added to the pico reactor, followed by 7 g of silica gel (SYLOPOL 952X, calcined at 250°C) under Ar. 8.5 mmol / g of methylaluminoxane (MAO) was then slowly injected at room temperature and stirred at 95°C for 24 hours. After the reaction was complete, the solution was cooled to room temperature, allowed to stand for 15 minutes, and the solvent was removed using a cannula. Toluene (400 mL) was added, stirred for 1 minute, allowed to stand for 15 minutes, and the solvent was removed using a cannula.

[0236] The metallocene compound of 60 μmol of synthesis example 1 is dissolved in 30mL toluene, and is transferred to reactor using conduit, is allowed to react 2 hours under 80 ℃ stirring.When reaction is complete and precipitation is complete, solution is cooled to room temperature and is placed for 15 minutes, and solvent is poured out using conduit. Remove supernatant, the remaining reaction product is washed with toluene. After washing with hexane again, the N, N-bis (2-hydroxyethyl) pentadecylamine (Atmer 163) as antistatic agent of 2 weight % based on the weight of silicon dioxide (g) is dissolved in 3mL hexane, is subsequently stirred at room temperature for 10 minutes.When reaction is complete and precipitation is complete, remove supernatant, the remaining product is transferred to glass filter to remove solvent.

[0237] The primary drying was performed at room temperature under vacuum for 5 hours, and the secondary drying was performed at 45° C. under vacuum for 4 hours to obtain a silica-supported metallocene catalyst in the form of solid particles.

[0238] Comparative Preparation Example 1

[0239] 3.0 kg of the toluene solution was added to a 20 L stainless steel (SUS) high-pressure reactor, and the reactor temperature was maintained at 40° C. 500 g of silica (Grace Davison, SP2212) that had been dehydrated at 600° C. under vacuum for 12 hours was added to the reactor to fully disperse the silica. 2.78 kg of a 10 wt% methylaluminoxane (MAO) / toluene solution was added, and the mixture was stirred at 80° C. and 200 rpm for 15 hours or longer.

[0240] The reactor temperature was lowered to 40° C., and then 200 g of the first metallocene compound / toluene solution (7.8 wt % in toluene) prepared in Comparative Synthesis Example 1 was added to the reactor, followed by stirring at 200 rpm for 1 hour. Subsequently, 220 g of the second metallocene compound / toluene solution (7.8 wt % in toluene) prepared in Comparative Synthesis Example 2 was added to the reactor, followed by stirring at 200 rpm for 1 hour.

[0241] 70g of the cocatalyst (anilinium tetrakis (pentafluorophenyl) borate) was diluted with toluene and the solution was added to the reactor, followed by stirring at 200 rpm for 15 hours or longer. The reactor temperature was cooled to room temperature, stirring was then stopped, and the mixture was allowed to settle for 30 minutes. The reaction solution was then poured out.

[0242] The toluene slurry was transferred to a filter dryer and then filtered. 3.0 kg of toluene was added and stirred for 10 minutes. Then, stirring was stopped and the mixture was filtered. 3.0 kg of hexane was added to the reactor and stirred for 10 minutes. Then, stirring was stopped and the mixture was filtered. The product was dried under reduced pressure at 50° C. for 4 hours to prepare 450 g of the SiO supported catalyst of Comparative Preparation Example 1.

[0243] Comparative Preparation Example 2

[0244] A silica-supported metallocene catalyst was prepared in the same manner as in Example 1. However, the silica-supported metallocene catalyst of Comparative Preparation Example 2 was prepared using a metallocene compound of the following Chemical Formula A instead of the metallocene compound of Synthesis Example 1.

[0245] [Chemical Formula A]

[0246]

[0247] [Preparation of polyethylene]

[0248] Example 1

[0249] The metallocene catalyst prepared in Preparation Example 1 was placed in a 220 L reactor in a pilot plant to produce high-density polyethylene in a single slurry polymerization process according to conventional methods. At a reactor temperature of 80°C, 10 kg / hr of ethylene and 1.09 g / hr of hydrogen were continuously reacted in a hexane slurry. 2.23 mL / min of 1-butene was added as a comonomer. After the reaction, the high-density polyethylene was produced in powder form by solvent removal and drying.

[0250] Example 2

[0251] The high-density polyethylene (ethylene / 1-butene copolymer) of Example 2 was prepared in powder form by the same polymerization process as Example 1, except that the input amounts of hydrogen and 1-butene were changed to 1.20 g / hr and 2.49 mL / min, respectively.

[0252] Example 3

[0253] The high-density polyethylene (ethylene / 1-butene copolymer) of Example 3 was prepared in powder form by the same polymerization process as Example 1, except that the input amounts of hydrogen and 1-butene were changed to 1.47 g / hr and 2.52 mL / min, respectively.

[0254] Example 4

[0255] The high-density polyethylene (ethylene / 1-butene copolymer) of Example 4 was prepared in powder form by the same polymerization process as Example 1, except that the input amounts of hydrogen and 1-butene were changed to 1.13 g / hr and 2.34 mL / min, respectively.

[0256] Example 5

[0257] The high-density polyethylene (ethylene / 1-butene copolymer) of Example 5 was prepared in powder form by the same polymerization process as Example 1, except that the input amounts of hydrogen and 1-butene were changed to 1.51 g / hr and 2.20 mL / min, respectively.

[0258] Example 6

[0259] The high-density polyethylene (ethylene / 1-butene copolymer) of Example 6 was prepared in powder form by the same polymerization process as Example 1, except that the input amounts of hydrogen and 1-butene were changed to 1.48 g / hr and 2.11 mL / min, respectively.

[0260] Comparative Example 1

[0261] The high density polyethylene (ethylene / 1-butene copolymer) of Comparative Example 1 in powder form was prepared by the same polymerization process as in Example 1, except that the mixed supported catalyst prepared in Comparative Example 1 was used instead of the metallocene catalyst prepared in Preparation Example 1.

[0262] Comparative Example 2

[0263] ME9180 (LG Chemical Co., Ltd.) produced using a Ziegler-Natta catalyst was used as the polyethylene of Comparative Example 2 (ethylene / 1-butene copolymer).

[0264] Comparative Example 3

[0265] SK MK910 (SK Chemical) produced using a Ziegler-Natta catalyst was used as the polyethylene of Comparative Example 3 (ethylene / 1-butene copolymer).

[0266] Comparative Example 4

[0267] MM810 (SK Chemical) was used as polyethylene (ethylene / 1-butene copolymer) in Comparative Example 4. MM810 is a high-density polyethylene (HDPE) with a melt index (MI) of 2.16 (MI, 2.16 kg load, 190°C) is 30.8 g / 10 min and the density is 0.954 g / cm 3 .

[0268] Comparative Example 5

[0269] 7200F (Formosa Plastics) was used as polyethylene (ethylene / 1-butene copolymer) in Comparative Example 5. 7200F is a high-density polyethylene (HDPE) with a melt index MI 2.16 (MI, 2.16 kg load, 190°C) is 22.0 g / 10 min and the density is 0.955 g / cm 3 .

[0270] Comparative Example 6

[0271] A high-density polyethylene (ethylene / 1-butene copolymer) of Comparative Example 6 was prepared in powder form in the same polymerization process as in Example 1, except that the metallocene catalyst prepared in Comparative Preparation Example 2 was used instead of the metallocene catalyst prepared in Preparation Example 1.

[0272] Comparative Example 7

[0273] A high-density polyethylene (ethylene homopolymer) of Comparative Example 7 was prepared in a powder form in the same polymerization process as Comparative Example 1, except that ethylene alone was polymerized without copolymerization with 1-butene.

[0274] <Experimental Example 1: Evaluation of Physical Properties of Polyethylene>

[0275] The physical properties of the polyethylenes prepared in the Examples and Comparative Examples were evaluated by the following methods, and the content of compounds in the low molecular weight region was analyzed. The results are shown in Table 1 below.

[0276] (1) Melt index

[0277] Melt Index (MI 2.16) and melt index (MI5) were measured according to American Society for Testing and Materials (ASTM) D 1238 (Condition E) at 190°C under loads of 2.16 kg and 5 kg, respectively, and the weight (g) of the polymer melted for 10 minutes was recorded as the melt index.

[0278] (2) Melt flow rate ratio (MFRR, MI5 / MI 2.16 )

[0279] The melt flow rate ratio is obtained by dividing the melt index MI5 (MI, load 5kg) by the melt index MI 2.16 (MI, load 2.16 kg) the ratio obtained (MI5 / MI 2.16 ).

[0280] (3) Density (g / cm 3 )

[0281] Density of polyethylene (g / cm 3 ) were measured according to the American Society for Testing and Materials (ASTM) D 1505.

[0282] (4) Weight average molecular weight and molecular weight distribution (PDI, polydispersity index, Mw / Mn) and Log MW (less than 3.0) ratio according to GPC analysis

[0283] The molecular weight distribution (PDI, Mw / Mn) was determined by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer using gel permeation chromatography (GPC, manufactured by Water).

[0284] Specifically, PL-GPC220 produced by Waters was used as a gel permeation chromatography (GPC) instrument, and a Polymer Laboratories PLgel MIX-B 300mm long column was used. At this time, the evaluation temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1ml / min. Using a GPC analyzer (PLGP220), each polymer sample of the embodiment and the comparative example was dissolved in 1,2,4-trichlorobenzene containing 0.0125% butylated hydroxytoluene (BHT) at 160°C for 10 hours. These samples were pretreated and prepared to a concentration of 10 mg / 10 mL, and then injected in an amount of 200 μL. Mw and Mn were obtained using a calibration curve formed using a polystyrene standard sample. Nine polystyrene standard samples were used, with weight average molecular weights of 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 100000000 g / mol.

[0285] In addition, the ratio (%) of the integrated value in the region where Log MW is 3.0 or less in the logarithmic graph relative to the weight average molecular weight (MW) of the measured polyethylene to the total integrated value was calculated and shown in the following Table 1, where the graph is a GPC curve graph in which the x-axis is log Mw and the y-axis is dw / dlogMw.

[0286] (5) GC mass spectrometry

[0287] About 50 mg of a sample prepared using each of the polyethylenes prepared in Examples and Comparative Examples was weighed and subjected to gas chromatography / flame ionization detector analysis (GC-FID) under the following conditions.

[0288] [GC / FID analysis conditions]

[0289] -GC instrument: 7890A GC system manufactured by Agilent

[0290] -GC oven: 100°C (5 minutes) - 15°C / minute - 320°C (20 minutes)

[0291] - Inlet and detector temperature: 300°C

[0292] In addition, in gas chromatography / flame ionization detector (GC-FID) analysis, polyethylene samples were pretreated as follows: Specifically, 0.5 g of polyethylene sample was dissolved in 10 mL of xylene, and the resin component was precipitated by adding 10 mL of ethanol, followed by centrifugation. The supernatant was dried with nitrogen (N2) to remove the solvent, and the product was dissolved in chloroform (CHCl3) or a mixed solvent of chloroform and acetone (CHCl3 / acetone), and the solution was injected into the measuring instrument.

[0293] In the graph obtained by GC-FID analysis performed under the above conditions, the peak area of ​​linear hydrocarbons having 3 to 32 carbon atoms was converted into a ratio relative to the peak area of ​​polyethylene, and the content (ppm) of linear hydrocarbons having 3 to 32 carbon atoms based on 1 g of polyethylene was determined.

[0294] (6) Total volatile organic compound (TVOC) emissions

[0295] The polyethylenes prepared in Examples and Comparative Examples were subjected to gas chromatography / mass spectrometry thermal desorption (GC / MS-TD) by exposure to high temperature under the following conditions.

[0296] [GC / MS-TD analysis conditions]

[0297] -Sample: 20mg

[0298] - Temperature and time: 200℃, 10 minutes

[0299] -GC oven: 50°C (5 minutes) - 10°C / minute - 300°C (10 minutes)

[0300] - Column: HP-5MS

[0301] -Toluene standard solution

[0302] The total volatile organic compound (TVOC) emissions (μg / g) were calculated as shown in Equation 1 below.

[0303] [Equation 1]

[0304] VOC 化合物 =[(A 化合物 / A 标准 )x C 标准 ] / W 样品

[0305] VOC 化合物 : VOC value of a single material produced by the test sample (μg / g)

[0306] A 化合物 : Chromatographic peak area of ​​individual materials produced by the test sample

[0307] A标准 : Peak area of ​​toluene standard solution

[0308] C 标准 : Weight of toluene injected using toluene standard solution (μg)

[0309] W 样品 : Weight of test sample (g)

[0310] The results of gas chromatography / mass spectrometry thermal desorption (GC / MS-TD) analysis are values ​​(μg / g) calculated from the peak area relative to the peak area of ​​a toluene standard solution.

[0311]

Table 1

[0312]

[0313] Referring to Table 1, the polyethylenes of Examples 1 to 3 of the present invention were confirmed to have narrow molecular weight distribution by increasing the amount of hydrogen input so that ethylene and hydrogen reacted uniformly in the reactor, and to have minimum polymer distribution in the low molecular weight region according to GPC and GC-FID analysis, and to have a narrow molecular weight distribution by optimizing the melt index (ASTM D 1238, 190°C, 2.16 kg) and melt flow rate ratio (MFRR, MI5 / MI6). 2.16 ) with reduced TVOC generation.

[0314] Therefore, in order to improve the texture of the surface, even if a bicomponent fiber is prepared by mixing a polypropylene resin and a polyethylene resin (where the polypropylene resin is used for the inner portion and the polyethylene resin is used for the outer portion) and performing a high-temperature spinning process, the polyethylene of the present invention can minimize the occurrence of single yarns, the fiber can be less broken, and the smoke generation can be significantly reduced.

Claims

1. A polyethylene, wherein The melt index measured according to ASTM D 1238 at 190°C and 2.16 kg load is 15 g / 10 min to 40 g / 10 min, Melt flow rate ratio (MFRR) MI5 / MI 2.16 2.3 to 2.7, among which MI5 and MI 2.16 Measured according to ASTM D 1238 at 190°C under loads of 5 kg and 2.16 kg, respectively, wherein in the GPC curve with log Mw on the x-axis and dw / dlogMw on the y-axis, the integrated value in the region where Log Mw is 3.0 or less is 0.8% to 1.8% of the total integrated value, and When the peak area of ​​straight-chain hydrocarbons having 3 to 32 carbon atoms in a GC-FID graph obtained by gas chromatography / flame ionization detector analysis (GC-FID) is converted into a ratio relative to the peak area of ​​polyethylene, the content of the straight-chain hydrocarbons having 3 to 32 carbon atoms is less than 600 ppm based on 1 g of polyethylene, wherein the GC-FID analysis is performed at an inlet temperature, a detector temperature of 300° C. and a residence time of 20 minutes.

2. The polyethylene according to claim 1, wherein In the GPC curve with log Mw on the x-axis and dw / dlogMw on the y-axis, the integrated value in the region where Log Mw is 3.0 or less is 0.9% to 1.5% of the total integrated value.

3. The polyethylene according to claim 1, wherein The molecular weight distribution (Mw / Mn) of the polyethylene is 2.0 to 2.

6.

4. The polyethylene according to claim 1, wherein The weight average molecular weight of the polyethylene is 38000 g / mol to 65000 g / mol.

5. The polyethylene according to claim 1, wherein When the peak area of ​​straight-chain hydrocarbons having 3 to 32 carbon atoms in a GC-FID chart obtained by gas chromatography / flame ionization detector analysis (GC-FID) is converted into a ratio relative to the peak area of ​​polyethylene, the content of the straight-chain hydrocarbons having 3 to 32 carbon atoms is 80 ppm to 600 ppm based on 1 g of polyethylene.

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

7. The polyethylene according to claim 1, wherein The polyethylene is a homopolymer of ethylene or C 4-20 Copolymers of α-olefin monomers and ethylene.

8. A method for preparing the polyethylene of claim 1, comprising the step of polymerizing ethylene in the presence of a catalyst composition comprising a metallocene compound represented by the following Chemical Formula 1: [Chemical formula 1] In Chemical Formula 1, B is boron, M is a Group 4 transition metal, R1 to R4 are each independently hydrogen, C 1-20 Alkyl, C 3-20 Cycloalkyl or C 6-20 aryl group, or R1 and R2 or R3 and R4 are connected to each other to form a C 6-60 Aromatic ring, R5 and R6 are each independently C 1-20 Alkyl, C 3-20 Cycloalkyl or C 6-20 Aryl, or R5 and R6 are connected to each other to form a C 3-60 Aliphatic ring or C 6-60 Aromatic ring, X1 and X2 are each independently C 1-20 Alkyl or -O(CO)R', where R' is C 1-20 alkyl, Q is C which may or may not have a substituent 2-60 a heterocyclic ring containing any one or more selected from the group consisting of N, O and S, Y and Y' are the elements that make up Q, Y is N, O or S, and Y' is an element of Q, adjacent to Y, and is either N or C.

9. The method of claim 8, wherein: R1 to R4 are each independently hydrogen or methyl, or R1 and R2 or R3 and R4 are connected 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 has no substituent or is substituted with one to four substituents selected from the group consisting of a methyl group, a tert-butyl group and a 4-tert-butylphenyl group.

10. The method of claim 8, wherein: R5 and R6 are each independently a methyl group or a phenyl group, or R5 and R6 are linked to each other to form a cyclooctane ring.

11. The method of claim 8, wherein: The compound represented by Chemical Formula 1 is any one of the compounds represented by the following structural formulas:

12. The method of claim 8, wherein: The catalyst composition further comprises one or more co-catalyst compounds selected from the group consisting of compounds represented by Chemical Formula 2 to Chemical Formula 4: [Chemical formula 2] <h2 style=";text-align:left;direction:ltr">-[Al(R<h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> )-O]<h2 style=";text-align:left;direction:ltr"> a <h2 style=";text-align:left;direction:ltr"> - In chemical formula 2, R 10 is halogen, or substituted or unsubstituted C 1-20 a hydrocarbon group; and a is an integer greater than 2, [Chemical formula 3] D(R 11 )3 In chemical formula 3, D is aluminum or boron; and R 11 is halogen, or substituted or unsubstituted C 1-20 Hydrocarbon, [Chemical formula 4] [LH] + [ZA4] - or [L] + [ZA4] - In chemical formula 4, L is a neutral or cationic Lewis base; H is a hydrogen atom; Z is a Group 13 element; and A is independently C 6-40 Aryl or C 1-20 Alkyl, where C 6-40 Aryl or C 1-20 The alkyl group is unsubstituted or substituted by one or more substituted alkyl groups selected from halogen, C 1-20 Alkyl, C 1-20 Alkoxy and C 6-40 The substituent group consisting of the allyloxy group is substituted.

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