Polyethylene and its manufacturing method

Abstract

The present invention provides polyethylene that has excellent processability and can reduce the reject rate in injection molding, and a method for producing the same.

Description

Technical Field

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0165107 filed on November 30, 2020 and Korean Patent Application No. 10-2021-0166153 filed on November 26, 2021, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to polyethylene having excellent processability and capable of reducing the defective rate of injection molding, and a method for producing the same.

Background Art

[0003] The demand for polyethylene resins is increasing steadily and they are used in various application fields. With the requirement for high-performance polyethylene for relatively new plastics, polymerization process technologies have been developed to support the production of new polymer materials.

[0004] Generally, olefin polymerization catalyst systems can be classified into Ziegler-Natta and metallocene catalyst systems, and these two types of highly active catalyst systems have been developed to suit their respective characteristics. Since the Ziegler-Natta catalyst was invented in the 1950s, it has been widely applied to existing commercial processes. However, since it is a multisite catalyst with a large number of mixed active sites, it is characterized by a wide molecular weight distribution of the polymer, and there is a problem in that it has limitations in ensuring desired physical properties because the composition distribution of the comonomer is not uniform.

[0005] On the one hand, a metallocene catalyst consists of a combination of a main catalyst with a transition metal compound as the main component and a cocatalyst with an organometallic compound with aluminum as the main component. Such a catalyst is a homogeneous complex catalyst, a single site catalyst, and due to its single site characteristics, a polymer with a narrow molecular weight distribution and a uniform composition distribution of comonomers can be obtained, and it has the characteristics that the stereoregularity, copolymerization characteristics, molecular weight, crystallinity, etc. of the polymer can be changed by the deformation of the ligand structure of the catalyst and the change of polymerization conditions.

[0006] U.S. Patent No. 5,914,289 describes a method for controlling the molecular weight and molecular weight distribution of a polymer using a metallocene catalyst supported on each carrier. However, it requires a large amount of the solvent used during the production of the supported catalyst and a long production time, and there is the trouble that each metallocene catalyst used has to be supported on the carrier.

[0007] Korean Patent Application No. 2003 - 12308 discloses a scheme for controlling the molecular weight distribution by polymerizing while changing the combination of catalysts in the reactor by supporting a binuclear metallocene catalyst and a mononuclear metallocene catalyst on a carrier together with an activator. However, such a method has limitations in simultaneously realizing the characteristics of each catalyst, and there is also the disadvantage that the metallocene catalyst part is released as a carrier component of the completed catalyst, inducing fouling in the reactor.

[0008] On the other hand, when polyethylene is used in the production of injection molded products such as bottle caps, generally excellent processability, mechanical properties, and excellent chemical properties such as a high level of environmental stress crack resistance (ESCR) are required. Therefore, technologies related to the production of polyethylene that can be suitably used in containers, bottle caps, etc., by satisfying a large molecular weight, a wider molecular weight distribution, and a suitable comonomer distribution, etc. have been continuously demanded.

[0009] In particular, when manufacturing a bottle cap using high-density polyethylene, hair is one of the molding defects that occur when the resin that has not yet fully solidified in the gate area of the cap during cap injection molding grows. The influencing factors for hair generation are not yet clear, and the problem has mainly been solved by increasing the viscosity through a decrease in processing temperature. For example, with the same resin, the hair generation rate varies depending on the mold (cooling rate during injection). However, due to the characteristics of various resins and molds, there are cases where it cannot be solved by increasing the viscosity through a temperature decrease, and this remains an issue that must be addressed in the future.

[0010] Therefore, in order to control the hair generation rate, an understanding of the mechanism and a molecular structure approach are required. The hair generation mechanism can be roughly divided into two stages: 1) initial hair generation and 2) increase in the generated hair, and the influencing factors at each stage are different. The factors involved in initial hair generation include solidification temperature, crystallization temperature (Tc), Tc distribution, mold design, etc., and the factors that make the hair longer include viscosity, extensional viscosity, etc. Also, when producing polyethylene resin using a Ziegler-Natta catalyst, it has a broad crystallization distribution and a low crystallization temperature that induce initial hair generation due to a relatively broad molecular weight distribution.

[0011] Therefore, in order to solve the above disadvantages, there is an increasing demand for the development of polyethylene that can reduce the hair generation rate while reducing the dependence on processing conditions such as cooling rate during the production of injection products such as bottle caps.

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention provides polyethylene for manufacturing injection molded products that can improve injection molding defects with excellent processability, particularly reduce the hair generation rate.

[0013] The present invention also provides a method for producing the polyethylene for manufacturing an injection molded article described above.

[0014] The present invention also provides an injection molded article containing the polyethylene described above.

Means for Solving the Problems

[0015] According to an embodiment of the invention, in the GPC curve graph of polyethylene where the x-axis is log Mw and the y-axis is dw / dlogMw, the integral value in the region where Log Mw is 5.5 or more is 9% or less of the total integral value, and the crystallization temperature (Tc 40 ) measured at a cooling rate of 10°C / min with respect to the crystallization temperature (Tc 10 ) measured at a cooling rate of 40°C / min, the ratio (Tc 10 / Tc 40 ) is less than 1.04, and polyethylene is provided.

[0016] The present invention also provides a method for producing the polyethylene for manufacturing an injection molded article described above.

[0017] The present invention also provides an injection molded article containing the polyethylene described above.

Effects of the Invention

[0018] According to the present invention, it is possible to provide high-density polyethylene in which the molecular weight distribution in the high molecular weight region and the crystallization temperatures (Tc10 and Tc40) according to the cooling rate are all optimized, the hair generation rate during injection is low, and the dependence on processing conditions such as the cooling rate during injection is low.

Modes for Carrying Out the Invention

[0019] In the present invention, terms such as first and second are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another component.

[0020] Also, the terms used in this specification are merely used to explain exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including", "comprising", or "having" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and should not be construed as precluding the presence or addition possibility of one or more other features, numbers, steps, components, or combinations thereof.

[0021] Also, terms such as "about" and "substantially" used throughout this specification are used in a meaning close to that numerical value or that numerical value when manufacturing and material tolerances inherent in the mentioned meaning are presented, and are used to prevent unscrupulous infringers from improperly using the disclosure where exact or absolute numerical values are mentioned to assist in the understanding of this application.

[0022] Also, "part by weight" in this specification means a relative concept indicating the weight of the remaining substances in ratio based on the weight of a certain substance. For example, in a mixture containing substance A with a weight of 50 g, substance B with a weight of 20 g, and substance C with a weight of 30 g, based on 100 parts by weight of substance A, the amounts of substance B and substance C are 40 parts by weight and 60 parts by weight respectively.

[0023] Also, "% by weight" means an absolute concept indicating the weight of a certain substance in the total weight as a percentage. In the mixture cited as the above example, the contents of substance A, substance B, and substance C in 100% of the total weight of the mixture are 50% by weight, 20% by weight, and 30% by weight respectively. At this time, the sum of the contents of each component does not exceed 100% by weight.

[0024] The present invention can be subjected to various modifications and can have various forms, and specific embodiments will be exemplified and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood to include all modifications, equivalents, and alternatives included in the spirit and technical scope of the present invention.

[0025] Hereinafter, the present invention will be described in more detail.

[0026] According to an embodiment of the invention, in order to reduce the dependence on processing conditions such as the cooling rate during injection and improve the hair defect of injection molded products, by adjusting the molecular weight distribution in the region showing a high molecular weight and the crystallization temperature (Tc10 and Tc40) according to the cooling rate, polyethylene suitable for manufacturing injection molded products such as bottle caps with excellent processability is provided.

[0027] Specifically, the polyethylene of the present invention has an x-axis of log Mw and a y-axis of dw / dlogMw in the GPC curve graph of polyethylene. The integral value in the region where Log Mw is 5.5 or more is 9% or less of the total integral value, and the crystallization temperature (Tc 40 ) measured at a cooling rate of 10°C / min with respect to the crystallization temperature (Tc 10 ) measured at a cooling rate of 40°C / min. The ratio (Tc 10 / Tc 40 ) is less than 1.04.

[0028] In particular, the polyethylene can reduce the dependence on processing conditions such as the cooling rate during injection by adjusting the molecular weight distribution in the region showing a high molecular weight and the crystallization temperature (Tc10 and Tc40) according to the cooling rate using a specific metallocene catalyst as described later, and can effectively improve injection molding defects, particularly hair defects.

[0029] Hereinafter, the polyethylene of the present invention will be described in more detail.

[0030] The polyethylene has an integral value in the region where the x-axis is log Mw and the y-axis is dw / dlogMw in the GPC curve graph, and the integral value in the region where Log Mw is 5.5 or more is 9% or less of the total integral value, or 5% to 9%.

[0031] Specifically, the integral value in the region where Log Mw is 5.5 or more can preferably be 8.98% or less, or 8.95% or less, or 8.91% or less. However, considering the substantial processability of polyethylene, the integral value in the region where Log Mw is 5.5 or more can be 5.5% or more, or 6% or more, or 7% or more, or 8% or more, or 8.3% or more.

[0032] By having the integral value in the region where Log Mw is 5.5 or more as described above, the high molecular weight (or molecular weight) of polyethylene can be optimized, and the crystallization temperature (or processability) can be improved.

[0033] Also, the polyethylene has an integral value in the region where the x-axis is log Mw and the y-axis is dw / dlogMw in the GPC curve graph, and the integral value in the region where Log Mw is 6.5 or more can be 0.3% or less of the total integral value, or 0.01% to 0.3%.

[0034] Specifically, the integral value in the region where Log Mw is 6.5 or more can preferably be 0.28% or less, or 0.25% or less, or 0.23% or less. However, considering the substantial processability of polyethylene, the integral value in the region where Log Mw is 6.5 or more can be 0.02% or more, or 0.05% or more, or 0.08% or more, or 0.1% or more, or 0.15% or more.

[0035] By having the integral value in the region where Log Mw is 6.5 or more as described above, the ultra-high molecular weight (or molecular weight) of polyethylene can be optimized, and the crystallization temperature (or processability) can be improved.

[0036] Further, the polyethylene may have a ratio (UH / H) of the integral value (UH Mw) of the region where Log Mw is 6.5 or more to the integral value (H Mw) of the region where Log Mw is 5.5 or more in a GPC curve graph with the x-axis being Log Mw and the y-axis being dw / dlogMw of 0.02 or more, or may be 0.02 to 0.03.

[0037] Specifically, the ratio (UH / H) of the integral value (UH Mw) of the region where Log Mw is 6.5 or more to the integral value (H Mw) of the region where Log Mw is 5.5 or more may preferably be 0.021 or more, or 0.0215 or more, or 0.022 or more. However, considering the substantial processability of polyethylene, the ratio (UH / H) of the integral value (UH Mw) may be 0.028 or less, or 0.026 or less, or 0.024 or less.

[0038] By having the ratio (UH / H) of the integral value (UH Mw) of the region where Log Mw is 6.5 or more to the integral value (H Mw) of the region where Log Mw is 5.5 or more as described above, the ratio of the high molecular weight content of polyethylene can be optimized, and the crystallization temperature can be improved.

[0039] The polyethylene of the present invention may have the ratio of the high molecular weight region in the molecular structure within the optimal range as described above, and at the same time, the molecular weight distribution (MWD, Mw / Mn) may be optimized.

[0040] Specifically, the polyethylene may have a molecular weight distribution (Mw / Mn) of 10 to 13, preferably 10.5 or more, or 11 or more, or 11.2 or more, and may be 12.5 or less, or 12.1 or less, or 11.9 or less.

[0041] By having the molecular weight distribution (Mw / Mn) as described above, the molecular weight and molecular weight distribution of polyethylene can be optimized, and the crystallization temperature (or processability) can be improved.

[0042] As an example, the ratio of the regions where the Log Mw value is 5.5 or more and 6.5 or more in the GPC curve graph and the molecular weight distribution (MWD, polydispersity index) are measured using gel permeation chromatography (GPC, manufactured by Waters).

[0043] Here, the molecular weight distribution (MWD, polydispersity index) can be calculated by measuring the weight average molecular weight (Mw) and the number average molecular weight (Mn) of polyethylene and dividing the weight average molecular weight by the number average molecular weight.

[0044] Specifically, as the gel permeation chromatography (GPC) apparatus, Waters PL-GPC220 equipment can be used, and a 300 mm long column of Polymer Laboratories PLgel MIX-B can be used. At this time, the measurement temperature is 160 °C, 1,2,4-trichlorobenzene can be used as the solvent, and the flow rate can be applied at 1 mL / min. The polyethylene sample is pretreated by dissolving it in 1,2,4-trichlorobenzene containing 0.0125% of butylated hydroxytoluene (BHT) at 160 °C for 10 hours using a GPC analyzer (PL-GP220), and after adjusting the concentration to 10 mg / 10 mL, it can be supplied in an amount of 200 microliters (μL). The values of Mw and Mn can be derived using the calibration curve formed using polystyrene standard specimens. The weight average molecular weights of the polystyrene standard specimens that can be used are 9 types: 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 10000000 g / mol.

[0045] In addition, the polyethylene may have a weight average molecular weight of 90,000 g / mol to 150,000 g / mol, preferably 95,000 g / mol or more, or 100,000 g / mol or more, or 105,000 g / mol or more, and may be 140,000 g / mol or less, or 130,000 g / mol or less, or 125,000 g / mol or less, or 120,000 g / mol or less.

[0046] By having the weight average molecular weight (Mw) as described above, the molecular weight distribution of polyethylene can be optimized, and the processability can be improved.

[0047] On the other hand, the polyethylene of the present invention is characterized in that while showing the ratio of the polymer region in the molecular structure within the optimal range as described above, it optimizes the crystallization temperature (Tc10 and Tc40) according to the cooling rate.

[0048] The polyethylene has a crystallization temperature (Tc 40 ) measured at a cooling rate of 10°C / min to the crystallization temperature (Tc 10 ) measured at a cooling rate of 40°C / min. The ratio (Tc 10 / Tc 40 ) is less than 1.04 or 1 or more and less than 1.04.

[0049] Specifically, the ratio (Tc 40 ) of the crystallization temperature (Tc 10 ) measured at a cooling rate of 10°C / min to the crystallization temperature (Tc 10 / Tc 40 ) measured at a cooling rate of 40°C / min may preferably be 1.038 or less, or 1.035 or less, or 1.03 or less, or 1.028 or less, or 1.024 or less. However, considering the substantial processability of polyethylene, the ratio (Tc 40 ) of the crystallization temperature (Tc 10 ) measured at a cooling rate of 10°C / min to the crystallization temperature (Tc 10 / Tc 40 ) may be 1 or more, or 1.01 or more, or 1.015 or more, or 1.017 or more.

[0050] The crystallization temperature (Tc 40 ) measured at a cooling rate of 40 °C / min as described above, with respect to the crystallization temperature (Tc 10 ) measured at a cooling rate of 10 °C / min, has a ratio (Tc 10 / Tc 40 ) such that the crystallization temperature of polyethylene can be optimized and the dependence on the processing speed can be reduced.

[0051] Also, the polyethylene has a crystallization temperature (Tc 40 ) measured at a cooling rate of 40 °C / min that is 113 °C to 114 °C.

[0052] Specifically, the polyethylene has a crystallization temperature (Tc 40 ) measured at a cooling rate of 40 °C / min that is preferably 113.2 °C or higher, or 113.5 °C or higher, or 113.7 °C or higher, and can be 113.95 °C or lower, or 113.9 °C or lower, or 113.8 °C or lower.

[0053] By having the crystallization temperature (Tc 40 ) measured at a cooling rate of 40 °C / min as described above, the crystallization rate during the injection process of polyethylene can be optimized and the processability can be improved.

[0054] Also, the polyethylene has a crystallization temperature (Tc 10 ) measured at a cooling rate of 10 °C / min that is 115 °C to 117 °C.

[0055] Specifically, the polyethylene has a crystallization temperature (Tc 10 ) measured at a cooling rate of 10 °C / min that is preferably 115.2 °C or higher, or 115.5 °C or higher, or 115.7 °C or higher, and can be 116.9 °C or lower, or 116.8 °C or lower, or 116.6 °C or lower.

[0056] The crystallization temperature (Tc 10By having ), the crystallization temperature of polyethylene can be optimized, and the processability can be improved.

[0057] In particular, factors involved in hair generation include the crystallization temperature (Tc), etc., and factors for the hair to become longer include viscosity, etc. Hair generation has mainly solved problems through an increase in viscosity due to a decrease in the processing temperature. However, since the hair generation rate varies depending on the characteristics of various resins and molds (such as mold temperature, cooling rate, etc.), there are limitations to the solution method through adjusting the processing temperature. Therefore, the hair generation rate can be reduced by reducing the dependence of the resin itself on processing conditions (such as cooling rate).

[0058] Also, in the actual process, the cooling rate is faster than 100 °C per minute. Therefore, if the resin itself does not solidify at a fast rate, the non-solidified resin will stretch for a long time and hair will be generated. For example, the faster the crystallization rate at a cooling rate of 100 °C or more per minute, the higher the viscosity of the resin, and the dependence on hair generation associated with this can be reduced. Therefore, by minimizing the ratio (Tc 10 / Tc 40 ) of the crystallization temperature at high speed (40 °C / min) to the crystallization temperature at low speed (10 °C / min), the hair generation rate in the actual process can be improved, and the defective rate of injection molding can be reduced. 10 / Tc 40 )

[0059] The polyethylene of the present invention can show the crystallization temperatures (Tc10 and Tc40) according to the cooling rate in the optimal range as described above, and at the same time, the melting temperatures (Tm10 and Tm40) can be optimized.

[0060] The polyethylene has a ratio (Tm 40 ) of the melting temperature measured at a rising rate of 10 °C / min to the melting temperature (Tm 10 ) measured at a rising rate of 40 °C / min 10 / Tm40 ) can be 1.004 to 1.012.

[0061] Also, the polyethylene has a melting temperature (Tm 40 ) measured at a heating rate of 40 °C / min that can be 117 °C to 118 °C.

[0062] Also, the polyethylene has a melting temperature (Tm 10 ) measured at a heating rate of 10 °C / min that can be 128 °C to 130 °C.

[0063] As an example, the crystallization temperature (Tc 10 , Tc 40 ) and the melting temperature (Tm 10 , Tm 40 ) can be measured using a differential scanning calorimeter (DSC).

[0064] Specifically, the copolymer is heated to 200 °C and maintained for 3 minutes, then cooled down to 30 °C again, and then the temperature is increased again. At this time, the heating rate is adjusted to 10 °C / min, and the cooling rates are adjusted to 10 °C / min and 40 °C / min respectively. The result measured in the section where the second temperature rises is taken as the melting temperature, and the result measured in the section where the temperature decreases is taken as the crystallization temperature.

[0065] On the other hand, the polyethylene of the present invention optimizes the crystallization temperature (Tc10 and Tc40) according to the ratio of the polymer region in the molecular structure and the cooling rate as described above, and at the same time, the melt index, melt flow index, density, etc. can be optimized.

[0066] In addition, the polyethylene may have a melt index (ASTM D 1238, 190 °C, 2.16 kg) of 0.2 to 2.0 g / 10 min, preferably 0.3 g / 10 min or more, or 0.5 g / 10 min or more, or 0.85 g / 10 min or more, or 1.0 g / 10 min or more, or 1.03 g / 10 min or more, and may be 1.8 g / 10 min or less, or 1.6 g / 10 min or less, or 1.5 g / 10 min or less, or 1.2 g / 10 min or less, or 1.15 g / 10 min or less, or 1.05 g / 10 min or less.

[0067] By having the melt index as described above, the molecular weight of polyethylene can be optimized and the crystallization temperature can be improved.

[0068] In addition, the polyethylene has a melt flow rate ratio (MFRR, Melt flow rate ratio, MI5 / MI 2.16 ) which may preferably be 3.5 to 4.0, preferably 3.52 or more, or 3.54 or more, or 3.56 or more, or 3.58 or more, and may be 3.98 or less, or 3.95 or less, or 3.93 or less, or 3.91 or less.

[0069] The MFRR is the value obtained by dividing the melt index (MI5) measured for the polyethylene at 190 °C and under a load of 5 kg based on ASTM D1238 by the melt index (MI 2.16 ) measured at 190 °C and under a load of 2.16 kg.

[0070] By having the melt flow rate as described above, the molecular weight distribution of polyethylene can be optimized and the crystallization temperature can be improved.

[0071] In addition, the polyethylene may be high density polyethylene (HDPE) having a density (ASTM D1505, 23 °C) of 0.945 g / cm 3 ~0.965 g / cm 3 .

[0072] More specifically, the density of the polyethylene is preferably 0.946 g / cm 3 or more, or 0.947 g / cm 3 or more, or 0.948 g / cm 3 or more, or 0.950 g / cm 3 or more, or 0.951 g / cm 3 or more, and 0.963 g / cm 3 or less, or 0.960 g / cm 3 or less, or 0.958 g / cm 3 or less, or 0.956 g / cm 3 or less.

[0073] The polyethylene according to one embodiment of the present invention is an ethylene copolymer with a C 4-20 α-olefin monomer.

[0074] As an example, the α-olefin may be an α-olefin having 4 to 20 carbon atoms, or 4 to 15 carbon atoms, or 4 to 12 carbon atoms. Specifically, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. may be mentioned, and any one or a mixture of two or more of these may be included. More specifically among these, it may be 1-butene or 1-hexene, and even more specifically, it may be 1-butene.

[0075] More specifically, the polyethylene according to one embodiment of the present invention may be a copolymer of ethylene and 1-butene.

[0076] Further, the repeating unit derived from the α-olefin may be contained in an amount of about 0.2 mol% to about 5 mol% in the polyethylene. When contained within the above content range, the polyethylene can exhibit better processability. However, if the content of the repeating unit derived from the α-olefin is lower than 0.2 mol%, it is difficult to obtain the effect of improving processability by including the repeating unit derived from the α-olefin, and if it exceeds 5 mol%, the effect of improving the lifespan may decrease. Considering the excellence of the processability improvement effect according to the control of the content of the repeating unit derived from the α-olefin, more preferably, the repeating unit derived from the α-olefin is 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% or more based on the total weight of the polyethylene, and may be contained in an amount of 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% or less.

[0077] On the other hand, in the present invention, "hair" is a type of processing defect that occurs during the injection molding process, and means a phenomenon in which the resin that has been melted or injection molded in the injection system passes or is transferred, flows in or out, and the resin injection molded near the gate (gate) grows long. In the present invention, when injection molding under the conditions of using 1.6 g to 2.4 g of polyethylene, a holding pressure of 300 bar to 1000 bar, a holding time of 0.5 seconds to 2.0 seconds, a cooling time of 0.5 seconds to 3.0 seconds, an injection temperature of 190°C to 250°C, an injection speed of 50 mm / s to 100 mm / s, a plasticizing length of 6 mm to 25 mm, and a back pressure of 5 bar to 100 bar, if the length of the elongated polyethylene is 2.5 mm or more, it is expressed as "hair" or "floss", and can be regarded as one of the injection molding defects.

[0078] In the present invention, the "hair generation rate" refers to the ratio of the number of injection-molded products with hair to the total number of injection-molded products, expressed as a percentage, when polyethylene resin is injection-molded under the injection molding conditions of holding pressure of 300 bar to 1000 bar, holding time of 0.5 seconds to 2.0 seconds, cooling time of 0.5 seconds to 3.0 seconds, injection temperature of 190 °C to 250 °C, injection speed of 50 mm / s to 100 mm / s, plasticizing length of 6 mm to 25 mm, and back pressure of 5 bar to 100 bar. As an example, under the above-mentioned conditions, when 20 kg of polyethylene resin is molded with a bottle cap of PC01881 standard (thickness of the top plate is 1.0 mm), it refers to the ratio of the number of injection-molded products with hair to the total number of injection-molded products, expressed as a percentage.

[0079] Specifically, the hair generation rate can be defined and calculated by the following Mathematical Formula 1.

[0080] [Mathematical Formula 1] Hair generation rate (%) = [B / A] × 100

[0081] In the Mathematical Formula 1, A means the total number of injection-molded products produced when polyethylene resin is molded under the injection molding conditions of holding pressure of 300 bar to 1000 bar, holding time of 0.5 seconds to 2.0 seconds, cooling time of 0.5 seconds to 3.0 seconds, injection temperature of 190 °C to 250 °C, injection speed of 50 mm / s to 100 mm / s, plasticizing length of 6 mm to 25 mm, and back pressure of 5 bar to 100 bar. Specifically, it means the total number of injection-molded products produced when 20 kg of polyethylene resin is molded with a bottle cap of PC01881 standard (thickness of the top plate is 1.0 mm). B means the number of injection-molded products with hair generated in the injection-molded products produced by injection molding under the above conditions.

[0082] In particular, the polyethylene of the present invention has a hair generation rate during injection according to the Mathematical Formula 1 of 5% or less, or 0.001% to 5% or less.

[0083] Specifically, the polyethylene may have a hair generation rate during injection of preferably 4.8% or less, or 4.5% or less, or 4% or less, or 3.5% or less, or 3% or less, or 2.5% or less. However, considering the substantial processability in the injection process, the hair generation rate during injection may be 0.005% or more, or 0.01% or more, or 0.015% or more, or 0.02% or more, or 0.05% or more, or 0.1% or more.

[0084] By having the hair generation rate during injection as described above, the defective rate of polyethylene injection molding can be optimized and the processability can be improved.

[0085] On the other hand, according to another embodiment of the invention, a method for producing the aforementioned polyethylene is provided.

[0086] Specifically, the polyethylene is produced by a method including a step of polymerizing an olefin monomer in the presence of a catalyst composition containing a metallocene compound represented by the following Chemical Formula 1.

[0087]

Chemical Formula

[0088] 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, or R1 and R2 or R3 and R4 are bonded to each other to form a substituted or unsubstituted 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 bonded 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 a substituted or unsubstituted C 2-60 heterocycle containing any one or more selected from the group consisting of N, O and S, Y and Y’ are elements constituting Q, Y is N, O, or S, Y’ is an element of Q adjacent to Y and is N or C.

[0089] More specifically, the substituents are as follows.

[0090] Unless otherwise specifically restricted in this specification, the following terms can be defined as follows.

[0091] The halogen may be fluoro (F), chloro (Cl), bromo (Br) or iodo (I).

[0092] The alkyl may be linear or branched alkyl. Specifically, the C 1-20 alkyl is a linear alkyl of C 1-20 ; a linear alkyl of C 1-10 ; a linear alkyl of C 1-5 ; a linear alkyl of C 3-20 ; a branched alkyl of C 3-15 ; a branched alkyl of C 3-10 ; or a branched alkyl of C 1-20 alkyl may be, for example, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, or an iso-pentyl group, etc., but is not limited thereto. On the other hand, “iPr” herein means an iso-propyl group.

[0093] The cycloalkyl may be cyclic alkyl. Specifically, the C 3-20 cycloalkyl is a cyclic alkyl of C 3-20 ; a cyclic alkyl of C 3-15 ; or a cyclic alkyl of C3-10 It may be a cyclic alkyl. More specifically, examples include, but are not limited to, 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, and the like. On the other hand, in this specification, "Cy" means a cycloalkyl having 3 to 6 carbon atoms.

[0094] The alkenyl may be a linear, branched or cyclic alkenyl. Specifically, the C 2-20 alkenyl is C 2-20 linear alkenyl, C 2-10 linear alkenyl, C 2-5 linear 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 may be cyclic alkenyl. More specifically, the C 2-20 alkenyl may be ethenyl, propenyl, butenyl, pentenyl or cyclohexenyl, etc.

[0095] The alkoxy may be a linear, branched or cyclic alkoxy group. Specifically, the C 1-20 alkoxy is C 1-20 linear alkoxy group; C 1-10 linear alkoxy; C 1-5 linear alkoxy group; C 3-20 branched or cyclic alkoxy; C 3-15 branched or cyclic alkoxy; or C 3-10 may be branched or cyclic alkoxy. More specifically, the C 1-20 alkoxy may be a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, iso-butoxy group, tert-butoxy group, n-pentoxy group, iso-pentoxy group, neo-pentoxy group or cycloheptoxy group, etc., but is not limited thereto.

[0096] The alkoxyalkyl may be a substituent having a structure including -Ra-O-Rb, in which one or more hydrogens of the alkyl (-Ra) are substituted with an alkoxy (-O-Rb). Specifically, the C 2-20 Examples of the alkoxyalkyl include, but are not limited to, 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, or a tert-butoxyhexyl group.

[0097] The aryl 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 specifically includes, but is not limited to, phenyl, naphthyl, anthracenyl, dimethylanilinyl, anisoryl, etc.

[0098] The heteroaryl is a heteroaryl containing one or more of O, N, and S as hetero elements, and the number of carbon atoms is not particularly limited, but may be 2 to 60 carbon atoms or 2 to 20 carbon atoms. Examples of the heteroaryl include, but are not limited to, xanthene, thioxanthen, thiophene group, furan group, pyrrole group, imidazole group, thiazole group, oxazole group, oxadiazole group, triazole group, pyridyl group, bipyridyl group, pyridinyl group, pyrimidyl group, triazine group, acridyl group, pyridazine group, pyrazinyl group, quinolinyl group, quinazoline group, quinoxalinyl group, phthalazinyl group, pyridopyrimidinyl group, pyridopyrazinyl group, pyrazinoprazinyl group, isoquinolinyl group, indole group, carbazole group, benzoxazole group, benzimidazole group, benzothiazole group, benzocarbazole group, benzothiophene group, dibenzothiophene group, benzofuranyl group, phenanthroline, isoxazolyl group, thiadiazolyl group, phenothiazinyl group, and dibenzofuranyl group.

[0099] The hydrocarbyl group means a monovalent hydrocarbon compound and includes alkyl groups, alkenyl groups, alkynyl groups, aryl groups, aralkyl groups, aralkenyl groups, aralkynyl groups, alkylaryl groups, alkenylaryl groups, alkynylaryl groups, etc. As an example, the hydrocarbyl group can be a straight-chain, branched-chain or cyclic alkyl. More specifically, a hydrocarbyl group having 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 iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, a cyclohexyl group; or an aryl group such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, or fluorenyl. Also, it can be an alkylaryl such as methylphenyl, ethylphenyl, methylbiphenyl, methylnaphthyl, and can be an aralkyl such as phenylmethyl, phenylethyl, biphenylmethyl, naphthylmethyl. Also, it can be an alkenyl such as allyl, ethenyl, propenyl, butenyl, pentenyl.

[0100] The heterocycle 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.

[0101] And the Group 4 transition metal can be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherfordium (Rf), specifically can be titanium (Ti), zirconium (Zr), or hafnium (Hf), more specifically can be zirconium (Zr) or hafnium (Hf), but is not limited thereto.

[0102] The above-mentioned substituents can be arbitrarily substituted with one or more substituents selected from the group consisting of a hydroxy group; a halogen; an alkyl or alkenyl, aryl, alkoxy; an alkyl or alkenyl, aryl, alkoxy containing one or more heteroatoms among the heteroatoms of Group 14 to Group 16; an amino; a silyl; an alkylsilyl or alkoxysilyl; a phosphine group; a phosphide group; a sulfonate group; and a sulfone group within the range of exhibiting the same or similar effects as the intended effect.

[0103] As the metallocene catalyst for ethylene polymerization of the present invention, a catalyst precursor containing one or more metallocene compounds represented by the above Chemical Formula 1 can be used.

[0104] The metallocene compound represented by the above Chemical Formula 1 adopts a bridge structure containing a boron anion, which is different from the conventionally used CGC (constrained geometry catalyst) type precursor. The conventional CGC type precursor contains a neutral bridge structure containing silicon and the ligand unit is negatively charged. As a result, there is a problem that it has structural limitations and it is difficult to exhibit various physical properties during the production of olefin polymers.

[0105] On the contrary, the metallocene compound represented by the above Chemical Formula 1 according to the present invention can have a negatively charged bridge structure and a neutral ligand unit. The ligand unit of the present invention is the heterocyclic ring Q of the above Chemical Formula 1, and Y, which is an element of Q, forms a coordination bond with the metal, and Y', which is an element of Q adjacent to Y, is connected to the bridge. Therefore, in the present invention, a catalyst having higher activity and higher copolymerizability than the existing CGC precursor can be produced by adopting various neutral ligand units satisfying the above structure.

[0106] Further, the metal substituent of the metallocene compound represented by the above Chemical Formula 1 contains an alkyl or carboxylate, which plays the role of a good leaving group, thereby promoting the reaction with a cocatalyst such as MAO and having the effect of increasing the activity.

[0107] Therefore, by using the metallocene compound, 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, and increase the effective number of physical cross-links of the molecules, so that polyethylene with a reduced total volatile organic compound (TVOC) generation amount can be produced.

[0108] Specifically, in the Chemical Formula 1, M can be zirconium (Zr).

[0109] Also, in the Chemical Formula 1, R1 to R4 are each independently hydrogen, C 1-10 alkyl or C 6-20 aryl, or R1 and R2 or R3 and R4 are bonded to each other to form a substituted or unsubstituted C 6-20 aromatic ring. Preferably, R1 to R4 are each independently hydrogen or methyl, or R1 and R2 or R3 and R4 are bonded to each other to form a benzene ring or a 1,2,3,4-tetrahydronaphthalene ring, where the benzene ring or the 1,2,3,4-tetrahydronaphthalene ring is unsubstituted or substituted with 1 to 4 substituents selected from the group consisting of methyl, tert-butyl, and 4-tert-butylphenyl.

[0110] Also, in the Chemical Formula 1, R5 and R6 are each independently C 1-10 alkyl or C 6-20 aryl, or R5 and R6 are bonded to each other to form a C 3-20 aliphatic ring or a C 6-20 aromatic ring. Preferably, R5 and R6 are each independently methyl or phenyl, or R5 and R6 are bonded to each other to form a cyclooctane ring.

[0111] More preferably, R5 and R6 can each be phenyl.

[0112] In the chemical formula 1, X1 and X2 can each independently be methyl or acetate.

[0113] In the chemical formula 1, R’ can be methyl.

[0114] In the chemical formula 1, X1 and X2 can be the same as each other.

[0115] In the chemical formula 1, Q can be a substituted or unsubstituted C 2-20 heterocyclic ring containing any one or more selected from the group consisting of N, O, and S.

[0116] Preferably, Q can be a pyridine ring, a quinoline ring, a 4,5-dihydrooxazole ring, a pyrazole ring, or a benzoxazole ring, and the Q can be unsubstituted or substituted with 1 to 4 substituents selected from the group consisting of methyl, isopropyl, and diphenylamino.

[0117] More preferably, Q can be a pyridine ring, a 4,5-dihydrooxazole ring, a pyrazole ring, or a benzoxazole ring, and the Q can be unsubstituted or substituted with 1 to 4 substituents selected from the group consisting of methyl, isopropyl, and diphenylamino.

[0118] In the chemical formula 1, Y is a heteroatom that forms a coordination bond with metal M, and preferably, Y can be N.

[0119] On the other hand, specific examples of the second metallocene compound represented by the chemical formula 1 include compounds represented by the following structural formulas, but the present invention is not limited thereto.

[0120]

Chemical formula

Chemical formula

Chemical formula

[0121] When X1 and X2 are identical to each other, the metallocene compound represented by the chemical formula 1 can be produced, for example, by a production method such as the following reaction formula 1, but is not limited thereto, and can be produced by known production methods of organic compounds and metallocene compounds. The production method can be further embodied in production examples described later.

[0122]

Chemical formula

[0123] In the reaction formula 1, B, M, R1 to R6, X1, X2, Q, Y and Y' are as defined in the chemical formula 1.

[0124] On the other hand, in this specification, "equivalent (eq.)" means molar equivalent.

[0125] The catalyst composition according to an embodiment of the invention can contain the metallocene compound of the chemical formula 1 as a single catalyst.

[0126] At this time, the catalyst composition can also be included as a single component of the metallocene compound, or may be in the form of a supported metallocene catalyst containing the metallocene compound and a carrier. When a supported metallocene catalyst is used, it is excellent in the morphology and physical properties of the produced polyethylene and can be appropriately used in conventional slurry polymerization, bulk polymerization, and gas-phase polymerization processes.

[0127] Specifically, as the carrier, a carrier having a highly reactive hydroxy group, silanol group or siloxane group on its surface can be used. For this purpose, a carrier surface-modified by calcination or a carrier with moisture removed from its surface by drying can be used. For example, silica produced by calcining silica gel, silica dried at a high temperature, silica-alumina, and silica-magnesia can be used, and these can usually contain oxide, carbonate, sulfate, and nitrate components such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0128] The temperature during calcination or drying of the carrier can be about 200°C to about 600°C, or about 250°C to about 600°C. When the calcination or drying temperature of the carrier is low, there may be too much moisture remaining in the carrier, and the surface moisture may react with the promoter. Also, due to the excessive amount of hydroxyl groups present, the promoter loading rate may be relatively high, but this will require a large amount of promoter. On the other hand, when the drying or calcination temperature is excessively high, the pores on the carrier surface close up, the surface area decreases, the number of hydroxy groups or silanol groups on the surface decreases, and only siloxane groups remain, which may reduce the reaction sites with the promoter.

[0129] The amount of hydroxy groups on the carrier surface is preferably 0.1 mmol / g to 10 mmol / g, and more preferably 0.5 mmol / g to 5 mmol / g. The amount of hydroxy groups on the carrier surface can be adjusted by the manufacturing method and conditions of the carrier or the drying conditions, such as temperature, time, vacuum or spray drying.

[0130] If the amount of hydroxy groups is less than 0.1 mmol / g, the reaction sites with the promoter are few. If it exceeds 10 mmol / g, it may be caused by moisture other than the hydroxy groups present on the surface of the carrier particles, which is not preferable.

[0131] As an example, the amount of hydroxyl groups on the carrier surface can 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 carrier surface can be adjusted by the manufacturing method and conditions of the carrier or the drying conditions, such as temperature, time, vacuum, or spray drying. If the amount of the hydroxyl groups is excessively low, there will be few reaction sites with the cocatalyst. If it is excessively high, it may be caused by moisture other than the hydroxyl groups present on the surface of the carrier particles.

[0132] Among the carriers, in the case of silica, especially silica produced by calcining silica gel, since the functional group of the compound of Chemical Formula 1 is chemically bonded and supported on the silica carrier, there is almost no catalyst released from the carrier surface in the propylene polymerization process. As a result, fouling between the reactor wall surface and the polymer particles can be minimized when producing polyethylene by slurry or gas-phase polymerization.

[0133] Also, when supported on the carrier, the compound of Chemical Formula 1 can be supported in a content range of, for example, 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 about 1 g of silica as the carrier weight. When supported in the above content range, it can show appropriate supported catalyst activity and be advantageous in terms of maintaining the activity of the catalyst and economy.

[0134] And the catalyst composition can further include one or more cocatalysts together with the metallocene compound and the carrier described above.

[0135] Any cocatalyst can be used as long as it is a cocatalyst used when polymerizing olefins under a general metallocene catalyst. The above cocatalyst causes a bond to be formed between the hydroxyl groups on the carrier and the Group 13 transition metal. Also, the cocatalyst can contribute to ensuring the unique properties of the specific hybrid catalyst configuration of the present invention by existing only on the surface of the carrier without fouling phenomena where the polymer particles get entangled with the reactor wall surface or each other.

[0136] In addition, the catalyst composition according to the present invention may contain one or more cocatalyst compounds selected from the group consisting of compounds represented by the following Chemical Formulas 2 to 4 in addition to the metallocene compound.

[0137] [Chemical Formula 2] -[Al(R 10 )-O] a -

[0138] In Chemical Formula 2, R 10 is halogen; or a C 1-20 hydrocarbyl which is substituted or unsubstituted with halogen; a is an integer of 2 or more,

[0139] [Chemical Formula 3] D(R 11 )3

[0140] In Chemical Formula 3, D is aluminum or boron; R 11 is halogen; or a C 1-20 hydrocarbyl which is substituted or unsubstituted with halogen,

[0141] [Chemical Formula 4] [L-H] + [ZA4] - Or [L] + [ZA4] -

[0142] In Chemical Formula 4, L is a neutral or cationic Lewis base; H is a hydrogen atom; Z is a Group 13 element; A is, independently of each other, a C 1-20 aryl or C 1-20 alkyl in which one or more hydrogen atoms are substituted with halogen, C 6-20 hydrocarbyl, C 1-20 alkoxy, or phenoxy.

[0143] Specifically, [L-H] in the chemical formula 4 + is a Brønsted acid.

[0144] The compound represented by the chemical formula 2 can serve as an alkylating agent and an activator, the compound represented by the chemical formula 3 can serve as an alkylating agent, and the compound represented by the chemical formula 4 can serve as an activator.

[0145] The compound represented by the chemical formula 2 is not particularly limited as long as it is an alkylaluminoxane. For example, it can be methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc., and preferably it can be methylaluminoxane.

[0146] The compound represented by the chemical formula 3 is not particularly limited as long as it is an alkyl metal compound. For example, it can be trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-s-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc., and preferably it can be selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0147] Examples of the compound represented by the chemical formula 4 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 tetrapentafluorophenylboron, N,N-diethylanilinium tetraphenylboron, N,N-diethylanilinium tetrapentafluorophenylboron, diethylammonium tetrapentafluorophenylboron, triphenylphosphonium tetraphenylboron, trimethylphosphonium 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, tributylammonium tetra(p-trifluoromethylphenyl)aluminum, trimethylammonium tetra(p-trifluoromethylphenyl)aluminum, tributylammonium tetrapentafluorophenylaluminum, N,N-diethylanilinium tetraphenylaluminum, N,N-diethylanilinium tetrapentafluorophenylaluminum, diethylammonium tetrapentafluorophenylaluminum, triphenylphosphonium tetraphenylaluminum, trimethylphosphonium tetraphenylaluminum, tripropylammonium tetra(p-tolyl)boron, triethylammonium tetra(o,(p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, triphenylcarbonium tetra(p-trifluoromethylphenyl)boron, triphenylcarbonium tetrapentafluorophenylboron, etc. are available. Preferably, an alumoxane can be used, and more preferably, methylaluminoxane (MAO), which is an alkylaluminoxane, can be used.,

[0148] In addition, the catalyst composition can contain the cocatalyst and the metallocene compound of Chemical Formula 1 in a molar ratio of about 1:1 to about 1:10000, preferably in a molar ratio of about 1:1 to about 1:1000, and more preferably in a molar ratio of about 1:10 to about 1:100. At this time, if the molar ratio is less than about 1, the metal content of the cocatalyst is excessively low and the catalytically active species cannot be formed well, and the activity may decrease. If the molar ratio exceeds about 10000, the metal of the cocatalyst may rather act as a catalyst poison.,

[0149] The loading amount of such a cocatalyst can be about 3 mmol to about 25 mmol, or about 5 mmol to about 20 mmol based on 1 g of the carrier.,

[0150] On the other hand, the catalyst composition can be produced by a production method including a step of supporting a cocatalyst on a carrier; a step of supporting a metallocene compound on the carrier on which the cocatalyst is supported; and a carrier including the carrier on which the cocatalyst and the metallocene compound are supported.,

[0151] In the above method, the loading conditions are not particularly limited and can be carried out within the range well known to those skilled in the art. For example, it can be carried out by appropriately using high-temperature loading and low-temperature loading. For example, the loading temperature can be 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 adjusted according to the amount of the first metallocene compound to be loaded. The loaded catalyst after the reaction can be used as it is by filtering the reaction solvent or removing it by distillation under reduced pressure, and if necessary, it can be used after Soxhlet extraction with an aromatic hydrocarbon such as toluene.

[0152] And the production of the supported catalyst can be carried out in the presence of a solvent or without a solvent. When a solvent is used, the solvents that can be used 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), and most organic solvents such as acetone and ethyl acetate. Hexane, heptane, toluene, or dichloromethane is preferred.

[0153] On the other hand, polyethylene according to an embodiment of the present invention can be produced by a method for producing polyethylene including a step of polymerizing polyethylene in the presence of a catalyst composition containing the metallocene compound.

[0154] The method for producing the polyethylene can be carried out by a slurry polymerization method by applying ordinary equipment and contacting techniques using ethylene and α-olefin as raw materials in the presence of the catalyst composition described above.

[0155] The method for producing the polyethylene can copolymerize ethylene and α-olefin by using a continuous slurry polymerization reactor, a loop slurry reactor, etc., but is not limited thereto.

[0156] In addition, examples of the α-olefin include α-olefins having 4 to 20 carbon atoms, or 4 to 15 carbon atoms, or 4 to 12 carbon atoms. Specifically, examples include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. It can be any one or a mixture of two or more thereof.

[0157] Specifically, in the method for producing polyethylene, for example, 1-butene or 1-hexene can be used as the α-olefin, and more specifically, 1-butene can be used.

[0158] As an example, the copolymerization step can be carried out by reacting the α-olefin in an amount of about 0.002 mol to about 0.05 mol based on 1 mol of ethylene. When reacting within the content range, the polyethylene can exhibit better processability. However, if the α-olefin is reacted in an amount less than 0.002 mol, it is difficult to obtain the effect of improving processability due to the inclusion of repeating units derived from the α-olefin. If it exceeds 0.05 mol, the effect of improving the lifetime may decrease. Considering the excellent effect of improving processability by controlling the content of the repeating units derived from the α-olefin, more preferably, the α-olefin is 0.005 mol or more, or 0.01 mol or more, or 0.012 mol or more, or 0.015 mol or more, or 0.018 mol or more, or 0.02 mol or more based on 1 mol of ethylene, and can be reacted in an amount of 0.048 mol or less, or 0.045 mol or less, or 0.042 mol or less, or 0.04 mol or less, or 0.038 mol or less, or 0.035 mol or less.

[0159] And the polymerization temperature can 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. Also, the polymerization pressure is about 1 kgf / cm 2 ~about 100 kgf / cm 2 、or about 1 kgf / cm 2~about 50 kgf / cm 2 or about 5 kgf / cm 2 ~about 45 kgf / cm 2 or about 10 kgf / cm 2 ~about 40 kgf / cm 2 or about 15 kgf / cm 2 ~about 35 kgf / cm 2 may be possible.

[0160] The catalyst composition containing the metallocene compound of Chemical Formula 1 according to the present invention can be dissolved or diluted and injected into an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, an aromatic hydrocarbon solvent such as toluene and benzene, and a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene. The solvent used here is preferably used after removing a small amount of water or air acting as a catalyst poison by treating with a small amount of alkylaluminum, and it is also possible to carry out using a cocatalyst.

[0161]

[0162] As an example, the polymerization step can be carried out by introducing hydrogen gas at about 900 ppm or less, or about 0 to about 900 ppm based on the ethylene content. Specifically, the hydrogen gas can be introduced at about 800 ppm or less, or about 750 ppm or less, or about 700 ppm or less, or about 650 ppm or less, or about 600 ppm or less, or about 550 ppm or less, or about 500 ppm or less, or about 450 ppm or less based on the ethylene content. However, when manufacturing polyethylene as an injection product, in terms of ensuring better processability, the hydrogen gas can be introduced at about 15 ppm or more, or about 30 ppm or more, or about 50 ppm or more, or about 100 ppm or more, or about 150 ppm or more, or about 180 ppm or more, or about 200 ppm or more, or about 220 ppm or more, or about 250 ppm or more, or about 270 ppm or more, or about 285 ppm or more, or about 300 ppm or more, or about 320 ppm or more, or about 330 ppm or more, or about 340 ppm or more.Specifically, the method for producing polyethylene described above involves introducing hydrogen in the presence of a catalyst composition containing the metallocene compound represented by the above Chemical Formula 1, and copolymerizing ethylene with an α-olefin of C 4-20 and the method may be carried out by including a step of copolymerizing ethylene with an α-olefin, wherein the hydrogen is introduced in an amount of 0.015 g / hr to 9 g / hr, or 0.02 g / hr to 7 g / hr, or 0.3 g / hr to 5 g / hr, or 0.5 g / hr to 3.4 g / hr based on the input of 10 kg / hr of ethylene monomer, and the α-olefin is introduced in an amount of 0.1 to 8.0 mL / min, or 2 to 7.0 mL / min, or 3.5 to 6.5 mL / min, or 4 to 6 mL / min based on the input of 10 kg / hr of ethylene monomer.

[0163] In such an ethylene copolymerization process, the catalyst composition containing the metallocene compound of the present invention can exhibit high catalytic activity. As an example, the catalytic activity during ethylene copolymerization is calculated as the ratio of the weight of polyethylene produced (kgPE) per unit mass (g) of the catalyst composition used per unit time (hr), and can be about 4.0 kgPE / g·cat·hr or more, or about 4.0 kgPE / g·cat·hr to about 50 kgPE / g·cat·hr. Specifically, the activity of the catalyst composition can be about 4.2 kgPE / g·cat·hr or more, or about 4.3 kgPE / g·cat·hr or more, or about 4.5 kgPE / g·cat·hr or more, or about 40 kgPE / g·cat·hr or less, or about 30 kgPE / g·cat·hr or less, or about 15 kgPE / g·cat·hr or less.

[0164] Thus, according to the present invention, polyethylene can be produced by copolymerizing ethylene and an α-olefin using the catalyst composition containing the metallocene compound of Chemical Formula 1 described above.

[0165] At this time, the polyethylene produced may be an ethylene-1-butene copolymer.

[0166] The method for producing the polyethylene can provide polyethylene with excellent physical properties by performing slurry polymerization in the presence of the catalyst composition described above.

[0167] In particular, the catalyst composition containing the metallocene compound of Chemical Formula 1 according to the present invention exhibits high activity as described above during the copolymerization of ethylene and α-olefin, and does not excessively increase the content of the α-olefin as a comonomer, and can increase the intramolecular short chain branch (SCB) content together with a high molecular weight.

[0168] The polyethylene produced by the method of the above-described embodiment exhibits a molecular weight distribution in a region with a high molecular weight and a crystallization temperature (Tc 10 and Tc 40 ) optimized to reduce the dependence on processing conditions such as the cooling rate during injection, improve injection molding defects, particularly hairline defects, and can be appropriately applied to injection molded products such as bottle caps.

[0169] Therefore, according to still another embodiment of the invention, there is provided an injection molded product including a polyethylene resin composition produced by the method of the above-described embodiment.

[0170] In particular, according to the present invention, by using the polyethylene resin composition produced by the above-described method, injection molded products such as bottle caps having excellent physical and chemical properties can be produced even when applying a relatively low injection pressure of 1000 to 1500 bar, or 1200 to 1480 bar.

[0171] Further, such injection molded products can exhibit excellent injection processability at a low injection pressure and excellent physical and chemical properties.

[0172] More specifically, when the injection molded article is manufactured as an injection molded article in the form of a bottle cap by injection and continuous compression molding (CCM) methods using the polyethylene resin composition produced by the method of the above-described embodiment, it can exhibit excellent ESCR properties. More specifically, the above-described ESCR properties can be evaluated by a method of measuring the time until cracks occur after exposing the injection molded article in the form of the container lid to an IGEPAL 5 wt% solution at a temperature of 42°C and applying a pressure of 5 bar, and the ESCR properties of the injection molded article indicated by such evaluation results can exhibit excellent chemical physical properties of 18 hours or more, or 30 hours or more, or 40 hours to 145 hours, or 50 hours to 130 hours.

[0173] Such an injection molded article can typically be a lightweight bottle cap, and can also be various other injection molded articles.

[0174] On the other hand, the injection molded article of the above-described and other embodiments can be manufactured by a general injection method except that the polyethylene resin composition produced by the method of the above embodiment is applied and a relatively low injection pressure is applied. Additional explanations regarding this are omitted.

[0175] Hereinafter, preferred examples are presented for the understanding of the present invention. However, the following examples are only provided to more easily understand the present invention, and the content of the present invention is not limited thereby.

[0176] <Example> [Production of Catalyst Precursor] Synthesis Example 1

[0177] [Chemical Formula]

[0178] After dissolving 2-bromopyridine (1 eq.) in tetrahydrofuran (0.1 M), n-butyllithium (1 eq.) was gradually added dropwise at -90 °C, and then the mixture was stirred at the same temperature for 1 hour. Subsequently, chlorodiphenylborane (1 eq.) was dissolved in toluene (0.3 M), and then gradually added dropwise to the first reactant at -78 °C and stirred 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 residual liquid after removing the solid through a filter etc. was dried under vacuum to obtain diphenyl(pyridin-2-yl)borane.

[0179] After dissolving the diphenyl(pyridin-2-yl)borane (1 eq.) in tetrahydrofuran (0.1 M), a solution of lithium tetramethylcyclopentadienide (Li(CpMe4), 1 eq.) dissolved in tetrahydrofuran (0.1 M) was gradually added dropwise at 0 °C, and then the mixture was stirred overnight at room temperature. After drying the solvent under vacuum, toluene / diethyl ether (volume ratio 3 / 1, 0.3 M) was added and dissolved, MCl4 (1 eq.) was mixed in toluene (0.2 M) and added at -78 °C and stirred overnight at room temperature. After completion of the reaction, the solvent was dried under vacuum, dichloromethane was added, the salt was removed through a filter etc., the filtrate was dried under vacuum, and then dichloromethane / hexane was added for recrystallization. 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-ylidene)borate}zirconium(IV)(Dichloro{diphenyl(pyridin-2-yl-κN)(η 5 -2,3,4,5-tetramethylcyclopenta-2,4-dien-1-ylidene)borate}zirconium(IV)) was obtained.

[0180] Dichloro{diphenyl(pyridin-2-yl-κN)(η 5 -2,3,4,5-Tetramethylcyclopenta-2,4-dien-1-ylidene)borate}zirconium(IV)(Dichloro{diphenyl(pyridin-2-yl-κN)(η 5 -2,3,4,5-tetramethylcyclopenta-2,4-dien-1-ylidene)borate}zirconium(IV)) (1 eq.) was dissolved in toluene / diethyl ether (volume ratio 3 / 1, 0.3 M). Then a solution of methyl lithium (2 eq.) dissolved in hexane or diethyl ether was slowly added dropwise at -78 °C, and the mixture was stirred at room temperature for 12 hours. After completion of the reaction, the solvent was dried under vacuum, dichloromethane was added, and salts were removed through a filter etc. The filtrate was dried under vacuum, and then dichloromethane / hexane was added for recrystallization. The resulting solid was filtered and dried under vacuum to obtain the precursor compound.

[0181] 1 H NMR (500 MHz, CDCl3, ppm): δ 8.32(d, 1H), 8.05(d, 4H), 7.70(t, 1H), 7.42(t, 1H), 7.40(t, 4H), 7.23(d, 1H), 7.17(t, 2H), 2.08(s, 6H), 1.93(s, 6H) 0.95(s, 6H)

[0182] Comparative Synthesis Example 1

[0183] [Chemical Formula]

[0184] Using 6-chlorohexanol, t-butyl-O-(CH2)6-Cl was produced by the method described in the literature (Tetrahedron Lett. 2951 (1988)), and cyclopentadienylsodium (NaCp) was reacted therewith to obtain t-butyl-O-(CH2)6-C5H5 (yield 60%, b.p. 80 °C / 0.1 mmHg).

[0185] Also, t-butyl-O-(CH2)6-C5H5 was dissolved in tetrahydrofuran (THF) at -78 °C, n-butyllithium (n-BuLi) was gradually added, then the temperature was raised to room temperature and reacted for 8 hours. The solution was again cooled to -78 °C, and the synthesized lithium salt solution was gradually added to a suspension solution of ZrCl4(THF)2 (170 g, 4.50 mmol) / THF (30 mL) and reacted at room temperature for another 6 hours. All volatile substances were removed by vacuum drying, hexane was added to the obtained oily liquid substance and filtered. After vacuum drying the filtered solution, hexane was added to induce precipitation at low temperature (-20 °C). The obtained precipitate was filtered at low temperature to obtain [tert-butyl-O-(CH2)6-C5H4]2ZrCl2] in the form of a white solid (yield 92%).

[0186] 1 H-NMR (300 MHz, 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) 13 C-NMR (CDCl3): 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.31, 30.14, 29.18, 27.58, 26.00

[0187] Comparative Synthesis Example 2

[0188]

Chemical formula

[0189] In a THF solvent, 1.0 mole of a solution of tert-butyl-O-(CH2)6MgCl, a Grignard reagent, was obtained from the reaction between a tert-butyl-O-(CH2)6Cl compound and Mg(0). The prepared Grignard compound was added to a flask containing (CH3)SiCl3 compound (176.1 mL, 1.5 mol) and THF (2.0 mL) at -30 °C, stirred at room temperature for 8 hours or more, and then the filtered solution was dried under vacuum to obtain a compound of tert-butyl-O-(CH2)6Si(CH3)Cl2 (yield 92%).

[0190] In a reactor at -20 °C, fluorene (Flu, fluoren, 3.33 g, 20 mmol), hexane (100 mL), and MTBE (methyl tert-butyl ether, 1.2 mL, 10 mmol) were added, and 8 mL of n-BuLi (2.5 M in Hexane) was gradually added and stirred at room temperature for 6 hours. After the stirring was completed, the reactor temperature was cooled to -30 °C, and the prepared fluorenyllithium solution was gradually added dropwise to a solution of tert-butyl-O-(CH2)6Si(CH3)Cl2 (2.7 g, 10 mmol) dissolved in hexane (100 mL) at -30 °C over 1 hour. After stirring at room temperature for 8 hours or more, water was added for extraction and dried (evaporation) to obtain a (tert-butyl-O-(CH2)6(CH3)Si(9-C 13 H 10 )2 compound (5.3 g, yield 100%). The structure of the ligand was confirmed by 1 1H-NMR.

[0191] 11H NMR (500 MHz, CDCl3): -0.35 (CH3Si, 3H, s), 0.26 (Si-CH2, 2H, m), 0.58 (CH2, 2H, m), 0.95 (CH2, 4H, m), 1.17 (tert-butyl-O, 9H, s), 1.29 (CH2, 2H, m), 3.21 (tert-butyl-O-CH2, 2H, t), 4.10 (Flu-9H, 2H, s), 7.25 (Flu-H, 4H, m), 7.35 (Flu-H, 4H, m), 7.40 (Flu-H, 4H, m), 7.85 (Flu-H, 4H, d).

[0192] At -20 °C, 4.8 mL of n-BuLi (2.5 M in hexane) was gradually added to a solution of (tert-butyl-O-(CH2)6(CH3)Si(9-C 13 H 10 )2 (3.18 g, 6 mmol) in MTBE (20 mL), and the mixture was reacted for over 8 hours while warming to room temperature. Then, at -20 °C, the prepared dilithium salts slurry solution was gradually added to a slurry solution of ZrCl4(THF)2 (2.26 g, 6 mmol) in hexane (20 mL), and the reaction was continued at room temperature for 8 hours. The precipitate was filtered off and washed several times with hexane to obtain a red solid form of (tert-butyl-O-(CH2)6(CH3Si(9-C 13 H9)2ZrCl2 compound (4.3 g, yield 94.5%).

[0193] 11H NMR (500 MHz, C6D6): 1.15 (tert-butyl-O, 9H, s), 1.26 (CH3Si, 3H, s), 1.58 (Si-CH2, 2H, m), 1.66 (CH2, 4H, m), 1.91 (CH2, 4H, m), 3.32 (tert-butyl-O-CH2, 2H, t), 6.86 (Flu-H, 2H, t), 6.90 (Flu-H, 2H, t), 7.15 (Flu-H, 4H, m), 7.60 (Flu-H, 4H, dd), 7.64 (Flu-H, 2H, d), 7.77 (Flu-H, 2H, d).

[0194] [Production of Supported Catalyst] Production Example 1 After putting 50 mL of toluene into a pico reactor, 7 g of silica gel (Silica gel, SYLOPOL 952X, calcinated under 250 °C) was added under Ar, and 10 mmol of methylaluminoxane (MAO) was gradually injected at room temperature and stirred at 95 °C for 24 hours to cause a reaction. After the reaction was completed, it was cooled to room temperature, left standing for 15 minutes, and the solvent was decanted using a cannula. Toluene (400 mL) was added, stirred for 1 minute, left standing for 15 minutes, and the solvent was decanted using a cannula.

[0195] After dissolving 60 μmol of the metallocene compound of Synthesis Example 1 in 30 mL of toluene, it was transferred to a reactor using a cannula. The reaction was carried out with stirring at 80 °C for 2 hours. After the precipitation ended after the reaction, it was cooled to room temperature and left standing for 15 minutes, and then the solvent was decanted using a cannula. The upper layer solution was removed, and the remaining reaction product was washed with toluene. After washing again with hexane, N,N-bis(2-hydroxyethyl)pentadecylamine (Atmer163), as an antistatic agent, was dissolved in 3 mL of hexane at 2 wt% based on the silica weight (g) and added, and then stirred at room temperature for 10 minutes. After the precipitation ended after the reaction, the upper layer was removed, transferred with a glass filter, and the solvent was removed.

[0196] It was dried for the first time under vacuum at room temperature for 5 hours and then dried for the second time under vacuum at 45 °C for 4 hours to obtain a silica-supported metallocene catalyst in the form of solid particles.

[0197] Comparative Production Example 1: Production of Hybrid Supported Catalyst 5.0 kg of a toluene solution was placed in a 20 L stainless steel (sus) high-pressure reactor, and the reactor temperature was maintained at 40 °C. 1000 g of silica (manufactured by Grace Davison, SP948) dehydrated by applying a vacuum at a temperature of 600 °C for 12 hours was charged into the reactor, and after the silica was sufficiently dispersed, 84 g of the metallocene compound of Comparative Synthesis Example 1 was dissolved in toluene and charged, and the reaction was carried out with stirring at 40 °C at 200 rpm for 2 hours. Thereafter, the stirring was stopped, and the reaction solution was decanted after setting for 30 minutes.

[0198] 2.5 kg of toluene was charged into the reactor, and after charging 9.4 kg of a 10 wt% methylaluminoxane (MAO) / toluene solution, the mixture was stirred at 40 °C and 200 rpm for 12 hours. After the reaction, stirring was stopped and the mixture was allowed to settle for 30 minutes to decant the reaction solution. 3.0 kg of toluene was charged and stirred for 10 minutes, then stirring was stopped and the mixture was allowed to settle for 30 minutes to decant the toluene solution.

[0199] 3.0 kg of toluene was charged into the reactor, 116 g of the metallocene compound of Comparative Synthesis Example 2 was dissolved in 1 L of a toluene solution and charged into the reactor, and the mixture was stirred at 40 °C and 200 rpm for 2 hours for reaction. At this time, the ratio of the metallocene compound of Comparative Synthesis Example 1 to the metallocene compound of Comparative Synthesis Example 2 was 1:1.2 based on the molar ratio. After the reactor temperature was lowered to room temperature, stirring was stopped and the mixture was allowed to settle for 30 minutes to decant the reaction solution.

[0200] 2.0 kg of toluene was charged into the reactor and stirred for 10 minutes, then stirring was stopped and the mixture was allowed to settle for 30 minutes to decant the reaction solution.

[0201] 3.0 kg of hexane was charged into the reactor, and the hexane slurry was transferred to a filter dryer to filter the hexane solution. It was dried under reduced pressure at 40 °C for 4 hours to produce a 1 kg-SiO2 hybrid supported catalyst.

[0202] [Production of Polyethylene] Example 1 The metallocene supported catalyst produced in Production Example 1 was charged into a 220 L reactor of a pilot plant in a single slurry polymerization process to produce high-density polyethylene by a conventional method. 10 kg / hr of ethylene and 3.4 g / hr of hydrogen were continuously reacted in a hexane slurry state at a reactor temperature of 80 °C. Here, 5 mL / min of 1-butene was charged as a comonomer. After the reaction, high-density polyethylene in powder form was produced through a solvent removal and drying process.

[0203] Example 2 The polymerization step was carried out in the same manner as in Example 1, but the hydrogen input amount was changed to 0.5 g / hr to produce high-density polyethylene in powder form.

[0204] Comparative Example 1 It was produced in the same manner as in Example 1, but the copolymerization step was carried out with ethylene and 1-butene using the hybrid-supported metallocene catalyst produced in Comparative Production Example 1. High-density polyethylene was produced by changing to 10 kg / hr of ethylene and 2.0 g / hr of hydrogen.

[0205] Comparative Example 2 It was produced in the same manner as in Comparative Example 1, but high-density polyethylene was produced by changing to 15 kg / hr of ethylene and 0.5 g / hr of hydrogen.

[0206] Comparative Example 3 It was produced in the same manner as in Comparative Example 1, but high-density polyethylene was produced by changing to 10 kg / hr of ethylene and 1.0 g / hr of hydrogen.

[0207] <Test Example 1: Physical Property Evaluation of Polyethylene> Physical property evaluations were carried out on the polyethylene produced in the examples and comparative examples by the following methods, and the measurement results are shown in Table 1 below.

[0208] (1) Melt index According to the standard ASTM D 1238 (Condition E) of the American Society for Testing and Materials, the melt index (MI 2.16 ) and melt index (MI5) were measured at 190 °C under loads of 2.16 kg and 5 kg, respectively, and were expressed as the weight (g) of the polymer melted and extruded in 10 minutes.

[0209] (2) Melt flow rate ratio (MFRR, MI5 / MI2.16) The melt index (MI5, 5 kg load) was divided by the melt index (MI 2.16 (MI, 2.16 kg load) to obtain the ratio (MI5 / MI 2.16 ).

[0210] (3) Weight-average molecular weight, molecular weight distribution (PDI, polydispersity index, Mw / Mn), and ratio of Log Mw (5.5 or more and 6.5 or more) by GPC analysis The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were measured using gel permeation chromatography (GPC, manufactured by Waters), and the molecular weight distribution (PDI, Mw / Mn) was calculated by dividing the weight-average molecular weight by the number-average molecular weight.

[0211] Specifically, as the gel permeation chromatography (GPC) apparatus, a Waters PL-GPC220 instrument was used, and a 300 mm long column of Polymer Laboratories PLgel MIX-B was used. At this time, the measurement temperature was 160 °C, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was set to 1 mL / min. Polymer samples according to the examples and comparative examples were each pretreated by dissolving them in trichlorobenzene (1,2,4-Trichlorobenzene) containing 0.0125% of butylated hydroxytoluene (BHT) at 160 °C for 10 hours, prepared to a concentration of 10 mg / 10 mL, and then supplied in an amount of 200 μL. The values of Mw and Mn were derived using a calibration curve formed using polystyrene standard specimens. Nine types of weight-average molecular weights of polystyrene standard specimens, namely 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 10000000 g / mol, were used.

[0212] Also, in the log graph of the weight-average molecular weight (Mw) of polyethylene measured in this way, that is, in the GPC curve graph where the x-axis is log Mw and the y-axis is dw / dlogMw, the ratio (U Hw, unit: %) of the integral value of each region where the log Mw value is 5.5 or more to the total integral value and the ratio (UH Mw, unit: %) of the integral value of each region where the log Mw value is 6.5 or more to the total integral value were calculated and shown in Table 1 below.

[0213] (4) Crystallization temperature (Tc) and melting temperature (Tm) Using a differential scanning calorimeter (Differential Scanning Calorimeter, DSC, device name: DSC2500, manufacturer: TA instrument), the crystallization temperature (Tc 10 , Tc 40 , Tc 10 / Tc 40 ) and the melting temperature (Tm 10 , Tm 40 ) of polyethylene were measured.

[0214] Specifically, after raising the temperature to heat polyethylene to 200 °C and then maintaining that temperature for 5 minutes (1 st RUN heat history removal), then lowering it to 30 °C, and then increasing the temperature again, the temperature at the maximum point of the endothermic peak corresponding to the apex of the DSC (Differential Scanning Calorimeter, manufactured by TA) curve shown was measured as the melting temperature (Tm). At this time, the rates of temperature increase and decrease were measured at 10 °C / min and 40 °C / min, respectively.

[0215] That is, the melting temperature (Tm 10 , Tm 40 ) was measured at the maximum point of the endothermic peak at temperature increase rates of 10 °C / min and 40 °C / min, respectively, in the second temperature increase section (2 nd RUN), and the crystallization temperature (Tc 10 , Tc 40 ) was measured in the second temperature decrease section (2 ndIt shows the maximum points of the exothermic peaks according to the results measured at temperature decrease rates of 10 °C / min and 40 °C / min, respectively, in the RUN).

[0216] (5) Density (g / cm3) The density (g / cm of polyethylene was measured according to the standard ASTM D 1505 of the American Society for Testing and Materials 3 ) was measured.

[0217]

Table 1

[0218] Referring to Table 1 above, the polyethylene of Examples 1 to 2 of the present invention is produced from an HDPE resin having an increased Tc (crystallization temperature) by adjusting the molecular weight distribution (high polymer content), and the ratio of Tc 10 / Tc 40 is 1.017 to 1.024 and approximates 1, indicating that the dependence on processing conditions is reduced and the hair generation rate can be reduced.

Claims

1. comprising the step of polymerizing an olefin monomer in the presence of a catalyst composition containing a metallocene compound represented by the following Chemical Formula 1 to produce polyethylene, wherein the polyethylene has an integral value in the region where Log Mw is 5.5 or more of 9% or less of the total integral value in the GPC curve graph of polyethylene with the x-axis being log Mw and the y-axis being dw / dlogMw, and the ratio (Tc 10 / Tc 40) of the crystallization temperature (Tc 10) measured at a cooling rate of 10°C / min to the crystallization temperature (Tc 40) measured at a cooling rate of 40°C / min is less than 1.04, A method for producing polyethylene. 【Chemical 1】 (In the Chemical Formula 1, B is boron, M is zirconium or hafnium, R １ ~R ４ each independently represents hydrogen, C １－２０ alkyl, C ３－２０ cycloalkyl, or C ６－２０ aryl, or R １ and R ２ or R ３ and R ４ are bonded to each other to form a substituted or unsubstituted C ６－６０ aromatic ring, R ５ and R ６ are each independently C １－２０ alkyl, C ３－２０ cycloalkyl, or C ６－２０ aryl, or R ５ and R ６ are bonded to each other to form a C ３－６０ aliphatic ring, or a C ６－６０ aromatic ring, X １ and X ２ are each independently C １－２０ alkyl or -O(CO)R', where R' is C １－２０ alkyl Q is a substituted or unsubstituted C containing N ２－６０ heterocycle, Y and Y' are elements constituting Q, Y is N, Y' is an element of Q adjacent to Y and is C.)

2. R １ to R ４ are each independently hydrogen or methyl, or R １ and R ２ or R ３ and R ４ are bonded to each other to form a benzene ring or a 1,2,3,4 - tetrahydronaphthalene ring, wherein the benzene ring or 1,2,3,4-tetrahydronaphthalene ring is unsubstituted or substituted with 1 to 4 substituents selected from the group consisting of methyl, tert-butyl, and 4-tert-butylphenyl, The method for producing polyethylene according to Claim 1.

3. R ５ and R ６ are each independently methyl or phenyl, or R ５ and R ６ are joined to each other to form a cyclooctane ring The method for producing polyethylene according to Claim 1 or 2.

4. The compound represented by the Chemical Formula 1 is any one of the compounds represented by the following structural formulas, The method for producing polyethylene according to any one of Claims 1 to 3. [Chemical Formula 2] [Chemical Formula 3] 【Chemical Formula 4】

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