Polyethylene having improved drop impact strength and composition comprising same

Abstract

The present invention provides polyethylene and a polyethylene composition comprising same, the polyethylene having excellent surface impact strength with no change in processability, when combined with recycled polyethylene, and being capable of improving the drop impact strength of a final product.

Description

Polyethylene with improved drop impact resistance and a composition containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0133321 filed September 30, 2024 and Korean Patent Application No. 10-2025-0141621 filed September 29, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003]

[0004] The present invention relates to polyethylene that has excellent drop impact strength without changing processability when combined with recycled polyethylene and can improve the surface impact of the final product, and a polyethylene composition containing the same.

[0005]

[0006] The demand for polyethylene resin is steadily increasing and it is being used in various applications.

[0007]

[0008] Recently, as environmental concerns have intensified, regulations aimed at curbing carbon dioxide emissions have been strengthened. In particular, as environmental pollution caused by the increased use of plastics has emerged as a serious issue, regulations at the manufacturing stage are being tightened, such as mandating the use of recycled resins, primarily in the United States. Consequently, manufacturers are required to add a certain amount of recycled resin when producing resin molded products, and eco-friendliness ratings are assigned based on the recycled resin content.

[0009]

[0010] However, since recycled resin is already processed, its properties have already changed during the high-temperature processing, resulting in significantly lower impact strength, tensile strength, chemical resistance, and thermal stability compared to conventional virgin resin. To address this problem, methods have been attempted to include a certain level of virgin resin in compositions containing recycled resin. However, this requires an excessive amount of virgin resin to minimize the degradation of mechanical properties, and issues regarding the deterioration of key properties, such as environmental stress cracking resistance (ESCR), remain unresolved. Furthermore, this problem becomes more severe as the number of processing cycles increases.

[0011]

[0012] Furthermore, in the case of polyethylene resin products using recycled resin, there is a problem in that it is difficult to satisfy both mechanical properties and processability due to a trade-off relationship. For instance, the use of recycled materials increases the orientation of the polyethylene composition, lowers low-temperature drop impact strength, and causes cracking in the final resin product; consequently, there is a need for a product with an optimal structure that possesses excellent drop impact strength without compromising processability.

[0013]

[0014] Accordingly, there is an urgent need for research and development of polyethylene with improved environmental stress crack resistance and excellent mechanical properties as a virgin resin to be blended with such recycled resin.

[0015]

[0016] The present invention aims to provide polyethylene and a polyethylene composition containing the same, which can improve processability and simultaneously possess excellent surface impact and enhance the drop impact strength of the final product when blended with recycled polyethylene.

[0017]

[0018] According to one embodiment of the invention,

[0019] The SCB content is 3.0 (pieces / 1000C) or higher, and

[0020] The BOCD (Broad Orthogonal Co-monomer Distribution Index) is 2 or higher, and

[0021] The complex viscosity (η*(ω500), complex viscosity) measured at a frequency (ω) of 500 rad / s is 700 Pa·s or less, and

[0022] The relaxation time is 4 seconds or less, and

[0023] A residual stress ratio of 0.25% or less,

[0024] Polyethylene is provided.

[0025]

[0026] In addition, the present invention provides a polyethylene composition comprising virgin polyethylene (or Booster PE) and recycled polyethylene (PCW PE, Post consumer waste polyethylene), wherein the virgin polyethylene comprises the polyethylene described above.

[0027]

[0028] According to the present invention, by optimizing the molecular structure of polyethylene to improve the SCB content and BOCD index, and at the same time minimizing the complex viscosity, relaxation time, and residual stress ratio so as not to increase orientation due to processing, it is possible to have excellent surface impact when blended with recycled polyethylene and improve the drop impact of the final product.

[0029]

[0030] In the present invention, terms such as first, second, etc. are used to describe various components, and these terms are used solely for the purpose of distinguishing one component from another.

[0031]

[0032] Furthermore, the terms used herein are used merely to describe exemplary embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0033]

[0034] Additionally, terms such as "approximately" and "substantially" used throughout this specification are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the stated meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0035]

[0036] In addition, in this specification, "part by weight" refers to a relative concept in which the weight of one substance is expressed as a ratio to the weight of another substance. For example, in a mixture containing 50 g of substance A, 20 g of substance B, and 30 g of substance C, the amounts of substance B and substance C are 40 parts by weight and 60 parts by weight, respectively, based on 100 parts by weight of substance A.

[0037]

[0038] In addition, "weight % (% by weight)" refers to an absolute concept in which the weight of a substance is expressed as a percentage of the total weight. In the mixture given as an example above, the content of substance A, substance B, and substance C is 50 weight%, 20 weight%, and 30 weight%, respectively, out of 100% of the total weight of the mixture. At this time, the total content of each component does not exceed 100 weight%.

[0039]

[0040] The present invention is capable of various modifications and may take various forms, and specific embodiments are illustrated and described in detail below. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0041]

[0042] The present invention will be described in more detail below.

[0043]

[0044] According to one embodiment of the invention, polyethylene is provided that optimizes the molecular structure to improve processability and simultaneously provide excellent surface impact and enhance drop impact of the final product even when combined with recycled polyethylene, while simultaneously improving SCB content and BOCD index, and minimizes complex viscosity, relaxation time, and residual stress ratio so that orientation due to processing does not increase.

[0045]

[0046] Specifically, the polyethylene of the present invention has an SCB content of 3.0 (pieces / 1000C) or more, a BOCD index (Broad Orthogonal Co-monomer Distribution Index) of 2 or more, a complex viscosity (η*(ω500)) measured at a frequency (ω) of 500 rad / s of 700 Pa·s or less, a relaxation time of 4 seconds or less, and a residual stress ratio of 0.25% or less.

[0047]

[0048] In particular, the above polyethylene can effectively improve environmental stress cracking resistance (ESCR) while maintaining excellent drop impact resistance of the final product, by optimizing the molecular structure and improving the SCB content and BOCD index, and by minimizing the complex viscosity, relaxation time, and residual stress ratio so that the orientation due to processing does not increase, thereby improving processability and providing excellent surface impact when blended with recycled polyethylene.

[0049]

[0050] The polyethylene of the present invention will be described in more detail below.

[0051]

[0052] Specifically, the polyethylene according to one embodiment of the present invention may be an ethylene homopolymer or an ethylene / alpha-olefin copolymer.

[0053]

[0054] The above alpha-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, 1-eicocene, and mixtures thereof.

[0055]

[0056] For example, the polyethylene according to the present invention may not contain the aforementioned alpha-olefin or may contain it in an amount of 10 weight% or less. That is, the alpha-olefin may be contained in an amount of 0 to 10 weight% or less. Specifically, the alpha-olefin may be 8 weight% or less, or 6.5 weight% or less, or 5 weight% or less, or 4.5 weight% or less, or 4 weight% or less, or 3.5 weight% or less, or 3 weight% or less, or 2.5 weight% or less, or 2.2 weight% or less, or 2 weight% or less, or 1.8 weight% or less, or 1.5 weight% or less, but is not limited thereto. In addition, when the polyethylene is an ethylene / alpha-olefin copolymer, the alpha-olefin may be 0.1 wt% or more, or 0.3 wt% or more, or 0.5 wt% or more, or 0.7 wt% or more, or 0.85 wt% or more, or 0.9 wt% or more, or 1.0 wt% or more, or 1.2 wt% or more, but is not limited thereto.

[0057]

[0058] For example, when the polyethylene according to the present invention is a copolymer, 1-hexene or 1-butene can be used as the alpha-olefin copolymerized with ethylene, and more specifically, 1-hexene can be used.

[0059]

[0060] In addition, the polyethylene may be a dry blend of one or more or two or more ethylene homopolymers as described above, or a dry blend of one or more or two or more ethylene / alpha-olefin copolymers.

[0061]

[0062] Meanwhile, in the polyethylene according to one embodiment of the invention, the SCB content derived from GPC-IR analysis relative to the total moles of the total polyethylene is 2.0 (units / 1000C) or more, or 2.0 (units / 1000C) or more and 13.0 (units / 1000C) or less, as the number of short chain branches per 1000 carbon atoms, i.e., the number of short branch chains with 2 to 7 carbon atoms ( / 1000C).

[0063]

[0064] The SCB content of the above polyethylene may be 2.3 (pieces / 1000C) or more, 2.5 (pieces / 1000C) or more, 2.6 (pieces / 1000C) or more, 2.7 (pieces / 1000C) or more, 2.8 (pieces / 1000C) or more, 2.9 (pieces / 1000C) or more, or 3.0 (pieces / 1000C) or more, and may also be 12 (pieces / 1000C) or less, 10 (pieces / 1000C) or less, 8 (pieces / 1000C) or less, 7 (pieces / 1000C) or less, 6.5 (pieces / 1000C) or less, 6 (pieces / 1000C) or less, 5.5 (pieces / 1000C) or less, or 5.2 (pieces / 1000C) or less.

[0065]

[0066] In the present invention, SCB (Short Chain Branch) refers to a short chain bonded to the polymer main chain in a branch-like form in polyethylene, specifically a short branched chain having 2 to 7 carbon atoms bonded to the main chain of polyethylene. It is a short branched chain formed when an alpha-olefin having 4 or more carbon atoms, such as 1-butene, 1-hexene, or 1-octene, is used as a comonomer, and its content may be proportional to the content of the α-olefin monomer included in the polymer chains. SCB content refers to the number of branched chains having 2 to 7 carbon atoms per 1,000 carbon atoms (unit: number / 1,000 C), and Proton Nuclear Magnetic Resonance (PNR, 1It can be calculated through analysis using H-NMR or gel chromatography (GPC-IR). In the present invention, it was calculated by measuring at 160°C using GPC-IR equipment, and the specific analysis method is explained in detail in the experimental examples below.

[0067]

[0068] Meanwhile, the above polyethylene has a BOCD index (Broad Orthogonal Co-monomer Distribution Index) of 2.2 or higher, or from 2.2 to 10.0 or lower.

[0069]

[0070] The BOCD structure used in this specification refers to a structure in which the content of short chain branches (SCB) in polyethylene is concentrated in the high molecular weight main chain, for example, a structure in which the content of comonomers such as alpha olefins is concentrated in the high molecular weight main chain, that is, a structure in which the content of short chain branches (SCB) increases as it goes toward the high molecular weight.

[0071]

[0072] The BOCD index can be obtained by using a GPC-IR device to continuously and simultaneously measure the weight-average molecular weight, molecular weight distribution, and SCB content, plotting a molecular weight distribution curve with the logarithm of the weight-average molecular weight (M) (log M) as the x-axis and the molecular weight distribution (dwt / dlog M) corresponding to the logarithm as the y-axis, measuring the SCB (Short Chain Branch) content (content of branches with 2 to 7 carbon atoms per 1,000 carbon atoms, unit: number / 1,000C) at the left and right boundaries of the middle 60% excluding the left and right ends relative to the total area, and then calculating according to the following Equation 1 using the measured values. In this case, the SCB content on the high molecular weight side and the SCB content on the low molecular weight side refer to the SCB content values ​​at the right boundary and the left boundary, respectively, within the middle 60% range excluding the left and right ends.

[0073] [Equation 1]

[0074]

[0075] In the above Equation 1, the SCB content in the high molecular weight region and the SCB content in the low molecular weight region represent the SCB content value at logMw corresponding to 20% of the high molecular weight region and the low molecular weight region, respectively. The high molecular weight log Mw and low molecular weight log Mw values ​​are the logMw values ​​corresponding to 20% of the high molecular weight region and the low molecular weight region, respectively, relative to the total area of ​​the y-axis (dw / dlogMw) and x-axis (logMw) curves obtained through GPC analysis.

[0076]

[0077] In this case, if the BOCD index is 0 or less, it is not a polymer with a BOCD structure, and if it is greater than 0, it is considered to be a polymer with a BOCD structure; the larger the value, the more it has a structure with a high SCB (Short Chain Branch) content in the high molecular weight region.

[0078]

[0079] The polyethylene according to one embodiment of the invention has a high BOCD index of 2 or higher, thereby having a high comonomer content in the high molecular weight portion, and as a result, can exhibit high environmental stress crack resistance along with excellent mechanical properties.

[0080]

[0081] Specifically, the BOCD index of the polyethylene may be 2.1 or higher, 2.15 or higher, 2.2 or higher, 2.22 or higher, 2.25 or higher, 2.28 or higher, or 2.3 or higher, and may also be 9.0 or lower, 8.5 or lower, 8.0 or lower, 7.5 or lower, 7.2 or lower, 7.0 or lower, 6.8 or lower, 6.5 or lower, 6.2 or lower, or 6.17 or lower.

[0082]

[0083] Meanwhile, polyethylene according to one embodiment of the invention optimizes the molecular structure of polyethylene and improves the SCB content and BOCD index, while simultaneously minimizing the complex viscosity, relaxation time, and residual stress ratio so that the orientation due to processing does not increase, thereby having excellent surface impact without changes in processability when blended with recycled polyethylene and improving the drop impact of the final product.

[0084]

[0085] Specifically, the polyethylene has a complex viscosity (η*(ω500)) measured at a frequency (ω) of 500 rad / s of 700 Pa·s or less, or 250 Pa·s or more and 700 Pa·s or less.

[0086]

[0087] Preferably, the complex viscosity (η*(ω500)) of the polyethylene measured at a frequency (ω) of 500 rad / s may be 680 Pa·s or less, or 650 Pa·s or less, or 630 Pa·s or less, or 600 Pa·s or less, or 580 Pa·s or less, or 550 Pa·s or less, or 530 Pa·s or less, or 520 Pa·s or less, or 515 Pa·s or less, or 513 Pa·s or less, or 500 Pa·s or less, or 480 Pa·s or less, or 450 Pa·s or less, or 430 Pa·s or less, or 400 Pa·s or less, or 380 Pa·s or less, or 360 Pa·s or less, or 340 Pa·s or less, and may also be 260 Pa·s or more, or 270 Pa·s or more, or 280 Pa·s It may be 290 Pa·s or more, or 300 Pa·s or more, or 310 Pa·s or more, or 320 Pa·s or more, 330 Pa·s or more, or 335 Pa·s or more.

[0088]

[0089] In addition, the polyethylene may have a complex viscosity (η*(ω0.05), complex viscosity) measured at a frequency (ω) of 0.05 rad / s of 5000 Pa·s or more and 60000 Pa·s or less.

[0090]

[0091] Preferably, the complex viscosity (η*(ω0.05), complex viscosity) of the polyethylene measured at a frequency (ω) of 0.05 rad / s may be 6000 Pa·s or more, or 7000 Pa·s or more, or 8000 Pa·s or more, or 10000 Pa·s or more, or 12000 Pa·s or more, or 15000 Pa·s or more, or 18000 Pa·s or more, or 18500 Pa·s or more, and may be 58000 Pa·s or less, or 55000 Pa·s or less, or 53000 Pa·s or less, or 50000 Pa·s or less, 49000 Pa·s or less, 48500 Pa·s or less, 48000 Pa·s or less, 47500 Pa·s or less, 47000 Pa·s or less, or 46500 Pa·s or less. It may be 46,000 Pa·s or less, or 45,600 Pa·s or less.

[0092]

[0093] For example, the above complex viscosity can be measured using a rotational rheometer, for instance, using the rotational rheometer ARES (Advanced Rheometric Expansion System, ARES G2) from TA Instruments. Here, the term "ARES (Advanced Rheometric Expansion System)" refers to a rheological property measuring instrument that evaluates viscoelastic characteristics such as viscosity, shear modulus, loss factor, and storage modulus of a material. The instrument is a mechanical measuring device capable of applying dynamic and steady states to a specimen and measuring the transmitted torque, which is the degree to which the specimen resists the applied stress. A polyethylene sample 190 oIn C, parallel plates with a diameter of 25.0 mm were used to ensure a gap of 2.0 mm. Measurements were performed in dynamic strain frequency sweep mode, with a strain of 5% and a frequency ranging from 0.05 rad / s to 500 rad / s, capable of measuring a total of 41 points (10 points per decade). The specific analysis method is described in detail in Test Example 1 below.

[0094]

[0095] In general, perfectly elastic materials undergo deformation in proportion to elastic shear stress, which is known as Hooke's Law. Furthermore, in the case of pure viscous liquids, deformation occurs in proportion to viscous shear stress, which is known as Newton's Law. In perfectly elastic materials, elastic energy is accumulated, so deformation can be restored once the elastic shear stress is removed; however, in perfectly viscous materials, energy is entirely dissipated through deformation, so deformation does not recover even if the viscous shear stress is removed. Additionally, the viscosity of the material itself does not change.

[0096]

[0097] However, polymers exhibit properties intermediate between those of perfectly elastic materials and viscous liquids in the molten state, a characteristic known as viscoelasticity. In other words, when polymers are subjected to shear stress in the molten state, the deformation is not proportional to the shear stress; furthermore, they possess the characteristic of changing viscosity according to the shear stress, which is why they are also referred to as non-Newtonian fluids. These characteristics are attributed to the complexity of deformation under shear stress, resulting from the polymer's large molecular size and complex intermolecular structure.

[0098]

[0099] In particular, when manufacturing molded articles using polymers, shear thinning is considered important among the characteristics of non-Newtonian fluids. Shear thinning refers to the phenomenon in which the viscosity of a polymer decreases as the shear rate increases, and the molding method of the polymer is determined according to these shear thinning characteristics. In particular, when manufacturing final molded products such as liquid containers by blending with recycled polyethylene as in the present invention, significant pressure must be applied to the molten polymer; therefore, if the shear thinning characteristics are not exhibited, it is difficult to manufacture such molded articles, and thus the shear thinning characteristics are considered important.

[0100]

[0101] Accordingly, the present invention measures shear fluidization characteristics through complex viscosity (η*[Pa.s]) according to frequency (ω[rad / s]). In particular, by optimizing the complex viscosity at a frequency (ω) of 500 rad / s and, if necessary, additionally including the complex viscosity at a frequency (ω) of 0.05 rad / s, it is possible to improve processability when blended with recycled polyethylene, while simultaneously achieving excellent surface impact and enhancing drop impact of the final product.

[0102]

[0103] Meanwhile, the above polyethylene has a relaxation time of 4 seconds or less, or 0.1 seconds or more to 4 seconds or less.

[0104]

[0105] Specifically, the relaxation time of the polyethylene may be 3.8 seconds or less, 3.5 seconds or less, 3.3 seconds or less, 3.2 seconds or less, 3.1 seconds or less, 3.0 seconds or less, or 2.9 seconds or less, and may also be 0.2 seconds or more, 0.3 seconds or more, 0.4 seconds or more, 0.5 seconds or more, 0.6 seconds or more, 0.7 seconds or more, 0.8 seconds or more, or 0.9 seconds or more.

[0106]

[0107] For example, the relaxation time of the polyethylene can be determined by measuring the viscosity of the polyethylene under each temperature condition and each angular frequency condition of 0.05 rad / s to 500 rad / s using a rotational rheometer as described above, and then calculating the relaxation time (seconds) of the polyethylene using a specific cross model based on this viscosity. Alternatively, the relaxation time (seconds) under specific temperature conditions can be calculated using an Arrhenius plot based on the relaxation time (seconds) measured at each temperature as described above. For example, the method for measuring the relaxation time of the polyethylene is as described in Test Example 1 below. However, the stress relaxation time of the polyethylene is not limited thereto and can be measured by other methods known in the art to which the present invention belongs.

[0108]

[0109] For example, the relaxation time (seconds) of polyethylene can be determined by using the ARES-G2 rotary rheometer from TA Instruments (New Castle, Delaware, USA) to measure the viscosity at each temperature at 150 ℃, 170 ℃, 190 ℃, 210 ℃, and 230 ℃ at a strain of 0.5%, at each angular frequency of 0.05 rad / s to 500 rad / s. From the viscosity values ​​measured at each temperature, the relaxation time (seconds) at each temperature is calculated using the cross model of Equation 2 below.

[0110] [Equation 2]

[0111] η = η ∞ + (η0 - η ∞ ) / (1 + λ × (Shear rate) m )

[0112] In the above Equation 2,

[0113] The above η is the viscosity of polyethylene measured using a rotational rheometer under conditions of each measurement temperature among 150 ℃, 170 ℃, 190 ℃, 210 ℃, and 230 ℃ and each frequency (Angular Frequency) of 0.05 rad / s to 500 rad / s, and

[0114] The above η ∞ is an infinite shear viscosity, and

[0115] The above η0 is the zero-point shear viscosity, and

[0116] The above shear rate is the shear rate applied to polyethylene and is equal to the angular frequency, and

[0117] The above λ and m are parameters obtained by fitting a log-log graph with angular frequency on the x-axis and viscosity measurement η on the y-axis using the cross model of Equation 2,

[0118] The above λ is the relaxation time (seconds) of polyethylene, which is the reciprocal of the angular frequency at which viscosity η begins to decrease, and

[0119] The above m is the slope of viscosity η in the region where viscosity η decreases.

[0120]

[0121] In addition, through the Arrhenius plot based on the relaxation time (seconds) measured at each temperature as described above, the relaxation time (RT) at 120 ℃ 120℃ ) is estimated.

[0122]

[0123] For example, after obtaining the Arrhenius constant (A) through an Arrhenius plot based on the relaxation time (seconds) for each temperature, the relaxation time of polyethylene is calculated according to Equation 3 below.

[0124] [Equation 3]

[0125] lnK = LnA + E a / RT

[0126] In the above Equation 3,

[0127] The above K is the relaxation time (seconds) of polyethylene, and

[0128] Ea is the activation energy (J / mol), and

[0129] R is the gas constant (8.314 J / mol·K), and

[0130] A is the Arrhenius constant, and

[0131] T is absolute temperature (Kelvin).

[0132]

[0133] Meanwhile, the above polyethylene has a residual stress ratio of 0.25% or less, or 0.01% or more to 0.25% or less.

[0134]

[0135] The residual stress ratio of the above polyethylene may be 0.245% or less, 0.24% or less, 0.235% or less, 0.23% or less, 0.228% or less, 0.225% or less, or 0.223% or less, and may also be 0.015% or more, 0.018% or more, 0.02% or more, 0.021% or more, 0.022% or more, or 0.023% or more.

[0136]

[0137] For example, the residual stress ratio of the polyethylene was determined by measuring the change in residual stress for 10 minutes after applying a 60% strain to the polyethylene sample at 190°C. For example, as described above, a rotary rheometer can be used to measure the residual stress, and the sample can be sufficiently loaded between upper and lower plates with a diameter of 25 mm, melted at 190°C, and then the gap can be fixed at 2 mm for measurement. The method for measuring the residual stress ratio can be further specified in Test Example 1, which will be described later.

[0138]

[0139] For example, the above residual stress ratio may be a value obtained by calculating according to Equation 4 below.

[0140] [Equation 4]

[0141] Residual stress ratio = (RS1 / RS0)×100

[0142] In the above Equation 4,

[0143] RS0 is the residual stress at any point in time (t0) of less than 0.05 seconds after applying 60% deformation to the polyethylene at 190 ℃, and

[0144] RS1 is the residual stress at any point in time (t1) between 0.05 seconds and 90 seconds after applying 60% deformation to the polyethylene at 190°C.

[0145]

[0146] Specifically, in the above Equation 4, t0 can be selected from 0.01 seconds, or 0.015 seconds, or 0.02 seconds, or 0.025 seconds, or 0.03 seconds, or 0.035 seconds, or 0.04 seconds, or 0.045 seconds. And, in the above calculation formula 1, t1 is 0.05 seconds, or 0.10 seconds, or 0.20 seconds, or 0.5 seconds, or 1.0 seconds, or 1.5 seconds, or 2 seconds, or 3 seconds, or 5 seconds, or 7 seconds, or 10 seconds, or 12 seconds, or 15 seconds, or 18 seconds, or 20 seconds, or 22 seconds, or 25 seconds, or 28 seconds, or 30 seconds, or 32 seconds, or 35 seconds, or 38 seconds, or 40 seconds, or 42 seconds, or 45 seconds, or 48 seconds, or 50 seconds, or 52 seconds, or 55 seconds, or 58 seconds, or 60 seconds, or 62 seconds, or 65 seconds, or 68 seconds, or 70 seconds, or 72 seconds, or 75 seconds, or 78 seconds, or It can be selected from 80 seconds, or 82 seconds, or 85 seconds, or 88 seconds, or 90 seconds. Preferably, in order to easily obtain valid data when measuring residual stress, t0 in Equation 2 may be 0.02 seconds and t1 may be 60 seconds.

[0147]

[0148] This residual stress ratio is a physical property related to the viscosity and elasticity of the molten resin, and is associated with the processability and stiffness of the polymer. If the value is too low, injection molding of molded parts becomes difficult due to reduced resin stiffness and decreased viscosity; conversely, if it is too low, while resin stiffness increases, the sharp rise in processing load makes it unsuitable for injection molding of molded parts.

[0149]

[0150] Meanwhile, the polyethylene according to the present invention may be one in which the complex viscosity, relaxation time, and residual stress ratio are all optimized along with the SCB content and BOCD index as described above, while the molecular weight distribution (PDI, Mw / Mn) is also optimized.

[0151]

[0152] Specifically, the polyethylene may have a molecular weight distribution (Mw / Mn) of 20 or more, or from 20 or more to 50 or less. Preferably, the molecular weight distribution (Mw / Mn) of the polyethylene may be 21 or more, 21.5 or more, 22 or more, 22.5 or more, or 23 or more, and may also be 45 or less, 40 or less, 35 or less, 30 or less, 28 or less, 26 or less, 25.5 or less, 25 or less, or 24.6 or less.

[0153]

[0154] By having the molecular weight distribution (Mw / Mn) as described above, the ratio of the low molecular weight region within the molecular structure of the polyethylene is strengthened while the ratio of the high molecular weight region is maintained, and when combined with recycled polyethylene, excellent mechanical properties are maintained and environmental stress cracking resistance (ESCR) can be improved.

[0155]

[0156] For example, the polydispersity index (PDI) in the above GPC curve graph is measured using gel permeation chromatography (GPC). Specifically, it can be measured using the polystyrene conversion assay method with gel permeation chromatography (GPC, manufactured by Polymer Char).

[0157]

[0158] Here, the polydispersity index (PDI) can be calculated by measuring the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polyethylene and dividing the weight-average molecular weight by the number-average molecular weight.

[0159]

[0160] Specifically, the Polymer Char GPC-IR instrument is used as the gel permeation chromatography (GPC) device, and a Polymer Laboratories PLgel MIX-B 300 mm long column can be used. In this case, the measurement temperature is 160 o C, and 1,2,4-trichlorobenzene can be used as a solvent, and a flow rate of 1 mL / min can be applied. Each of the above polyethylene samples was analyzed using a GPC analyzer (GPC-IR) in 1,2,4-trichlorobenzene containing 0.0125% butylated hydroxytoluene (BHT) at 160 oC, pre-treated by dissolving for 2 hours, prepared at a concentration of 10 mg / 10 mL, and supplied in an amount of 200 microliters (μL). Values ​​of Mw and Mn can be derived using a calibration curve formed using a polystyrene standard specimen. Nine types of polystyrene standard specimens with weight-average molecular weights can be 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 10000000 g / mol.

[0161]

[0162] In addition, the polyethylene may have a weight-average molecular weight of 100,000 g / mol or more, or between 100,000 g / mol and 500,000 g / mol. Preferably, the weight-average molecular weight of the polyethylene may be 105,000 g / mol or more, or 110,000 g / mol or more, or 115,000 g / mol or more, or 120,000 g / mol or more, or 122,000 g / mol or more, or 125,000 g / mol or more. However, considering compatibility with recycled polyethylene, the weight-average molecular weight may be 480,000 g / mol or less, or 450,000 g / mol or less, or 400,000 g / mol or less, or 350,000 g / mol or less, or 300,000 g / mol or less, or 250,000 g / mol or less, or 200,000 g / mol or less, or 190,000 g / mol or less, or 185,000 g / mol or less, or 180,000 g / mol or less, or 178,500 g / mol or less.

[0163]

[0164] By having the weight average molecular weight (Mw) as described above, the molecular weight distribution of the polyethylene is optimized, and when combined with recycled polyethylene, the environmental stress cracking resistance (ESCR) can be improved along with excellent mechanical properties.

[0165]

[0166] Meanwhile, the polyethylene according to the present invention can optimize the complex viscosity, relaxation time, and residual stress ratio along with the SCB content and BOCD index as described above, while simultaneously optimizing the melt index.

[0167]

[0168] The above polyethylene has a melt index (MI). 2.16 , ASTM D 1238, 190 ℃, 2.16 kg load) may be 0.10 g / 10 min to 1.2 g / 10 min. Preferably, the melt index (MI) of the polyethylene 2.16 (ASTM D 1238, 190 ℃, 2.16 kg load) may be 0.15 g / 10 min or more, 0.18 g / 10 min or more, 0.2 g / 10 min or more, or 0.22 g / 10 min or more, and 1.18 g / 10 min or less, 1.15 g / 10 min or less, 1.12 g / 10 min or less, or 1.10 g / 10 min or less. As described above, the melt index (MI) of polyethylene 2.16 By having ), the molecular weight distribution of polyethylene is optimized, and when combined with recycled polyethylene, environmental stress cracking resistance (ESCR) can be improved along with excellent mechanical properties.

[0169]

[0170] By possessing the melt index described above, the molecular weight of polyethylene is optimized, and when blended with recycled polyethylene, environmental stress cracking resistance (ESCR) can be improved along with excellent mechanical properties. In particular, considering compatibility with recycled polyethylene, the melt index (MI) of polyethylene 2.16 , ASTM D 1238, 190 ℃, 2.16 kg) is preferably 0.1 g / 10 min to 1.2 g / 10 min.

[0171]

[0172] Meanwhile, the polyethylene according to one embodiment of the present invention has a density (ASTM D 1505, 23 °C) of 0.935 g / cm³ 3 Above, or 0.935 g / cm³ 3 Up to 0.960 g / cm³ 3 It may be high-density polyethylene (HDPE) that satisfies the condition.

[0173]

[0174] More specifically, the density of the polyethylene is 0.938 g / cm³ 3 Above, 0.940 g / cm³ 3 Above, 0.942 g / cm³ 3 Above, 0.945 g / cm³ 3 Above, 0.946 g / cm³ 3 Above, or 0.950 g / cm³ 3 It may be greater than 0.958 g / cm³ 3 Below, 0.956 g / cm³ 3 Below, 0.955 g / cm³ 3 Less than or equal to 0.952 g / cm³ 3 It may be less than.

[0175]

[0176] In the present invention, density (g / cm³) 3) can be measured according to ASTM D 1505 standards, and, for example, may be a value measured at 23 ℃. For example, such density (g / cm³) 3 The method for measuring ) is as described in the experimental examples below.

[0177]

[0178] When the density of the polyethylene satisfies the range described above, when mixed with recycled polyethylene, it can improve environmental stress cracking resistance (ESCR), improve processability, have excellent surface impact, and improve drop impact of the final product.

[0179]

[0180] Meanwhile, the polyethylene of the present invention can be produced by homopolymerizing ethylene in the presence of a metallocene catalyst in a slurry loop process, or by copolymerizing ethylene with a comonomer such as an alpha-olefin, and a more detailed synthesis method can be referenced in the examples.

[0181]

[0182] For example, the polyethylene may be a dry blend of one or more ethylene homopolymers or two or more ethylene copolymers prepared in the presence of a metallocene catalyst as described above, or a dry blend of one or more ethylene / alpha-olefin copolymers or two or more ethylene / alpha-olefin copolymers.

[0183]

[0184] In addition, the above-mentioned novel polyethylene may be manufactured by introducing hydrogen gas in the presence of a catalyst composition comprising one first metallocene compound represented by the following chemical formula 1 and two or more second metallocene compounds represented by the following chemical formula 2.

[0185] [Chemical Formula 1]

[0186] (Cp 1 R a) n (Cp 2 R b )M 1 Z 1 3-n

[0187] In the above chemical formula 1,

[0188] M 1 It is a Group 4 transition metal;

[0189] Cp 1 and Cp 2 are respectively cyclopentadiennyl, and these are C 1-20 Substituted with or unsubstituted with hydrocarbons;

[0190] R a and R b are identical or different from each other, and independently hydrogen, C 1-20 Alkyl, C 1-20 Alkoxy, C 2-20 Alkoxyalkyl, C 6-20 Aril, C 6-20 Aryloxy, C 2-20 Alkenyl, C 7-40 Alkylaryl, C 7-40 Arylalkyl, C 8-40 Aryl alkenil, C 2-20 C comprising alkynyl, or one or more heteroatoms selected from the group consisting of N, O, and S. 2-20 It is heteroaryl, provided that R a and R b At least one of them is C 1-20 alkyl or C 7-20 It is an arylalkyl, and one of the others is C 2-20 It is an alkoxyalkyl;

[0191] Z 1 Silver is a halogen, C 1-20 Alkyl, C 2-20 Alkenyl, C 7-40 Alkylaryl, C 7-40 Arylalkyl, C 6-20 Aryl, substituted or unsubstituted C 1-20 Alkylidene, substituted or unsubstituted amino group, C 2-20 Alkylalkoxy, or C 7-40 It is an aryl alkoxy;

[0192] n is 1 or 0 and;

[0193] [Chemical Formula 2]

[0194]

[0195] In the above chemical formula 2,

[0196] C1 is any one of the ligands represented by the following chemical formulas 3 to 6, and

[0197] [Chemical Formula 3]

[0198]

[0199] [Chemical Formula 4]

[0200]

[0201] [Chemical Formula 5]

[0202]

[0203] [Chemical Formula 6]

[0204]

[0205] In the above chemical formulas 3 to 6,

[0206] R1 to R6 are identical or different from one another, and each independently contains hydrogen, C 1-30 Alkyl, C 1-30 Alkoxy, C 2-30 Alkoxyalkyl, C 6-30 Aril, C 6-30 Aryloxy, C 2-30 Alkenyl, C 2-30 Alkinyl, C 3-30 Cycloalkyl, C 7-40 Alkylaryl, C 8-40 Alkenylaryl, C 8-40 Alkynylaryl, C 7-40 Arylalkyl, C 8-40 Aryl alkenyl, or C 8-40 It is Arylalkinil, and

[0207] M is Ti, Zr, or Hf, and

[0208] Z is -O-, -S-, -NR7- or -PR7-, and

[0209] R7 is hydrogen, C 1-30 Alkyl, C 6-30 Aril, C 2-30 Alkenyl, C 2-30 Alkinyl, C 3-30 Cycloalkyl, C 7-40 Alkylaryl, C 8-40 Alkenylaryl, C 8-40 Alkynylaryl, C 7-40 Arylalkyl, C 8-40 Aryl alkenil, C 8-40 Arylalkinyl, C 1-30 Alkoxysilyl group, C 6-30 Aryloxysilyl, C 1-30 Alkylsilyl group, or C 1-30 It is a silylalkyl group, and

[0210] X1 and X2 are identical or different from each other and each independently halogen, C 1-30 Alkyl, C 2-30 Alkenyl, C 7-30 Alkylaryl, C 7-30 Arylalkyl, C 6-20 Aryl, substituted or unsubstituted C 1-30 Alkylidene, substituted or unsubstituted amino group, C 2-30 Alkylalkoxy, or C 7-30 It is an aryl alkoxy, and

[0211] T is or And,

[0212] T1 is C, Si, Ge, Sn, or Pb, and

[0213] Y1 is hydrogen, hydrogen, C 1-30 Alkyl, C 1-30 Alkoxy, C 2-30 Alkoxyalkyl, C 6-30 Aril, C 6-30 Aryloxy, C 2-30 Alkenyl, C 2-30 Alkinyl, C 3-30 Cycloalkyl, C 7-40 Alkylaryl, C 8-40 Alkenylaryl, C 8-40 Alkynylaryl, C 7-40 Arylalkyl, C 8-40Aryl alkenyl, or C 8-40 Arylalkinyl, silyl group (-SiH3), C 1-30 Alkoxysilyl group, C 2-30 Alkoxyalkylsilyl group, C 6-30 Aryloxysilyl, C 1-30 Haloalkyl, C 6-30 Haloaryl, or -NR9R 10 And,

[0214] Y2 is C 2-30 Alkoxyalkyl, or C 7-40 It is an aryloxyalkyl, and

[0215] R9 and R 10 Each independently hydrogen, C 1-30 Alkyl, C 6-30 Aril, C 2-30 Alkenyl, C 2-30 Alkinyl, C 3-30 Cycloalkyl, C 7-40 Alkylaryl, C 8-40 Alkenylaryl, C 8-40 Alkynylaryl, C 7-40 Arylalkyl, C 8-40 Aryl alkenyl, or C 8-40 They are arylalkynyl, or linked together to form aliphatic or aromatic rings.

[0216]

[0217] Meanwhile, unless otherwise specifically limited in this specification, the following terms may be defined as follows.

[0218]

[0219] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0220]

[0221] C 1-30 The alkyl group may be a straight-chain, branched-chain, or cyclic alkyl group. Specifically, C 1-20 The alkyl group is C 1-15 Straight-chain alkyl group; C 1-10 Straight-chain alkyl group; C 1-5 Straight-chain alkyl group; C 3-20 Branched or cyclic alkyl group; C3-15 Branched or cyclic alkyl group; or C 3-10 It may be a branched chain or a cyclic alkyl group. More specifically, C 1-20 The alkyl group of may be a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, or cyclohexyl group, etc.

[0222]

[0223] C 2-30 The alkenyl group can be a straight-chain, branched-chain, or cyclic alkenyl group. Specifically, C 2-30 The alkenyl group is C 2-20 Straight-chain alkenyl group, C 2-10 Straight-chain alkenyl group, C 2-5 Straight-chain alkenyl group, C 3-20 Branched-chain alkenyl group, C 3-15 Branched-chain alkenyl group, C 3-10 Branched-chain alkenyl group, C 5-20 The cyclic alkenyl group or C 5-10 It may be a cyclic alkenyl group. More specifically, C 2-20 The alkenyl group of may be an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, or a cyclohexanyl group, etc.

[0224]

[0225] C 6-30 Aryl can refer to monocyclic, bicyclic, or tricyclic aromatic hydrocarbons. Specifically, C 6-30 The aryl group can be a phenyl group, a naphthyl group, or anthracenyl group, etc.

[0226]

[0227] C 7-40 Alkylaryl may refer to a substituent in which one or more hydrogens of an aryl are substituted by an alkyl group. Specifically, C 7-40 The alkylaryl may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl, or cyclohexylphenyl, etc.

[0228]

[0229] C 7-40 Arylalkyl may refer to a substituent in which one or more hydrogens of an alkyl group are substituted by an aryl group. Specifically, C 7-40 The arylalkyl group may be a benzyl group, phenylpropyl or phenylhexyl, etc.

[0230]

[0231] The above C 1-20 Examples of alkoxy groups include methoxy groups, ethoxy groups, phenyloxy groups, cyclohexyloxy groups, etc., but are not limited to these.

[0232]

[0233] The above C 2-20 The alkoxyalkyl group is a functional group in which one or more hydrogens of the alkyl group described above are substituted with an alkoxy group, specifically, alkoxyalkyl groups such as methoxymethyl group, methoxyethyl group, ethoxymethyl group, iso-propoxymethyl group, iso-propoxyethyl group, iso-propoxyhexyl group, tert-butoxymethyl group, tert-butoxyethyl group, tert-butoxyhexyl group; or aryloxyalkyl groups such as phenoxyhexyl group, but is not limited thereto.

[0234]

[0235] The above C 1-20 alkylsilyl group or C 1-20 The alkoxysilyl group is a functional group in which 1 to 3 hydrogens of -SiH3 are substituted with 1 to 3 alkyl groups or alkoxy groups as described above, and specifically, examples include alkylsilyl groups such as methylsilyl, dimethylsilyl, trimethylsilyl, dimethylethylsilyl, diethylmethylsilyl, or dimethylpropylsilyl; alkoxysilyl groups such as methoxysilyl, dimethoxysilyl, trimethoxysilyl, or dimethoxyethoxysilyl; and alkoxyalkylsilyl groups such as methoxydimethylsilyl, diethoxymethylsilyl, or dimethoxypropylsilyl, but are not limited thereto.

[0236]

[0237] The above C1-20 The silylalkyl group is a functional group in which one or more hydrogens of the alkyl group described above are substituted with a silyl group, and specifically, examples include -CH2-SiH3, methylsilylmethyl group or dimethylethoxysilylpropyl group, but are not limited thereto.

[0238]

[0239] The above sulfonate group has the structure -O-SO2-R', where R' is C 1-20 It may be an alkyl group. Specifically, C 1-20 Sulfonate groups include methanesulfonate groups or phenylsulfonate groups, but are not limited to these.

[0240]

[0241] The above heteroaryl comprises one or more of N, O, and S as heteroelements, C 2-20 As heteroaryls, specific examples include xanthene, thioxanthen, thiophene group, furan group, pyrrole group, imidazole group, thiazole group, oxazole group, oxadiazole group, triazole group, pyridyl group, bipyridyl group, pyrimidyl group, triazine group, acridyl group, pyridazine group, pyrazinyl group, quinolinyl group, quinazolinyl group, quinoxalinyl group, phthalazinyl group, pyridopyrimidinyl group, pyridopyrazinyl group, pyrazinopyrazinyl group, isoquinoline group, indole group, carbazole group, benzoxazole group, benzimidazole group, benzothiazole group, benzocarbazole group, benzothiophen group, dibenzothiophen group, benzofuranyl group, phenanthroline, There are isooxazolyl groups, thiadiazolyl groups, phenothiazinyl groups and dibenzofuranyl groups, but are not limited to these.

[0242]

[0243] The substituents described above may be optionally substituted with one or more substituents selected from the group consisting of hydroxyl groups; halogens; alkyl groups or alkenyl groups, aryl groups, alkoxy groups; alkyl groups or alkenyl groups, aryl groups, alkoxy groups comprising one or more heteroatoms of groups 14 to 16; silyl groups; alkylsilyl groups or alkoxysilyl groups; phosphine groups; phosphide groups; sulfonate groups; and sulfone groups, within the range of producing the same or similar effects as the desired effect.

[0244]

[0245] Furthermore, the fact that two adjacent substituents are connected to form an aliphatic or aromatic ring means that the atom(s) of the two substituents and the valence (atoms) to which the two substituents are bonded are connected to form a ring. Specifically, -NR9R 10 R9 and R 10 Examples of these interconnected groups forming an aliphatic ring include piperidinyl groups, and -NR9R 10 R9 and R 10 Examples of groups connected to form an aromatic ring include pyrrolyl groups.

[0246]

[0247] In addition, group 4 transition metals include titanium (Ti), zirconium (Zr), hafnium (Hf), etc., but are not limited to these.

[0248]

[0249] For example, the first metallocene compound represented by the above chemical formula 1 is Cp 1 and Cp 2 As a non-crosslinked compound containing a ligand of, Cp 1 and Cp 2 The ligands of may be identical or different from each other, and are each cyclopentadiennyl, and C 1-10 It can be substituted with 1 or more alkyl groups or 1 to 3.

[0250]

[0251] Also, the above Cp 1 and Cp 2 The ligand of can easily control characteristics such as the chemical structure, molecular weight, molecular weight distribution, mechanical properties, and transparency of the olefin polymer produced by adjusting the degree of steric hindrance effect according to, for example, the type of substituted functional group. Specifically, the above Cp 1 and Cp 2 The ligands of are R, respectively. a and R b It is replaced with, at this time, the above R a and R b are identical or different from each other, and independently, hydrogen, C 1-20 Alkyl, C 2-20 Alkoxyalkyl, C 7-40 C comprising arylalkyl, or one or more heteroatoms selected from the group consisting of N, O, and S. 2-12 It can be heteroaryl, and more specifically, C 1-10 Alkyl, C 2-10 Alkoxyalkyl, C 7-20 C comprising arylalkyl, or one or more heteroatoms selected from the group consisting of N, O, and S. 4-12 It can be heteroaryl. However, R a and R b At least one of them is C 1-20 alkyl or C 7-20 It is an arylalkyl, and one of the others is C 2-20 It is an alkoxyalkyl. For example, R a One or more of them are C 1-20 alkyl or C 7-20 It is an arylalkyl, and R a The remainder is hydrogen, and R b One of them is C 2-20 It is an alkoxyalkyl, and R b The remainder is hydrogen, or C 1-20 alkyl or C 7-20 It can be an arylalkyl.

[0252]

[0253] Also, the above Cp 1 and Cp 2 Between the ligands of M 1 Z 1 3-n This exists, M 1 Z 1 3-n can affect the storage stability of metal complexes. To ensure this effect more effectively, Z 1 Each independently is a halogen or C 1-20 It may be an alkyl group, and more specifically, it may be F, Cl, Br, or I independently. Also, the above M 1 It may be Ti, Zr or Hf; Zr or Hf; or Zr.

[0254]

[0255] Among the first transition metal compounds above, Cp in Chemical Formula 1 1 and Cp 2 are each an unsubstituted or substituted cyclopentadienyl group, and R a and R b Each independently hydrogen, C 1-10 Alkyl, C 2-10 Alkoxyalkyl, or C 7-20 It is an arylalkyl, but R a and R b At least one of them may be an alkyl group such as methyl or butyl, or an arylalkyl group such as phenylpropyl, and the remainder may be an alkoxyalkyl group such as a t-butoxyhexyl group, more specifically a -(CH2)n-OR substituent (wherein R is a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms, and n is an integer from 2 to 4).

[0256]

[0257] The first metallocene compound represented by the above chemical formula 1 may be, for example, a compound represented by one of the following structural formulas, but is not limited thereto.

[0258]

[0259]

[0260] Meanwhile, the second metallocene compound comprises an aromatic ring compound containing thiophene as a different ligand and a base compound containing a group 14 or 15 atom, the different ligands are cross-linked by -T-, and have a structure in which M(X1)(X2) exist between the different ligands.

[0261]

[0262] More specifically, in the above chemical formula 2, M is Ti, Zr, or Hf, and more specifically, may be Ti.

[0263]

[0264] Also, R1 to R4 are each independently hydrogen, or C 1-20 It is an alkyl, and more specifically, it can be hydrogen or methyl.

[0265]

[0266] Also, R5 and R6 each independently C 1-10 It is alkyl, and more specifically, both R5 and R6 can be methyl.

[0267]

[0268] Also, Z is -NR7-, and the above R7 is C 1-10 Alkyl, more specifically C such as t-butyl 3-10 It can be a branched alkyl.

[0269]

[0270] Also, T is And, the above T1 is C or Si, and Y1 is C 1-20 Alkyl, C 1-20 Alkoxy, C 2-20 Alkoxyalkyl, C 6-20 Aril, C 7-30 Alkylaryl, C 7-30 Arylalkyl, C 6-20 Aryloxy, or C 7-30 It is aryloxyalkyl, and Y2 is C 2-20Alkoxyalkyl, or C 7-30 It is an aryloxyalkyl, and more specifically, Y1 can be any one of a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, and Y2 is C 2-20 Alkoxyalkyl, or C 7-30 It is an aryloxyalkyl, and more specifically, Y2 may be any one of a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhexyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, a tert-butoxyhexyl group, and a phenoxyhexyl group.

[0271]

[0272] Also, X1 and X2 are each independently halogen or C 1-20 It is an alkyl, and more specifically, it can be chloro or methyl.

[0273]

[0274] For example, as the second metallocene compound, compounds represented by the following chemical formulas 2a to 2d may be exemplified, and among the compounds represented by the following chemical formulas 2a to 2d, two or more compounds of different structures are included.

[0275]

[0276] According to one embodiment of the present invention, as the second metallocene compound, a combination of two compounds represented by the following formula 2a and two compounds represented by the following formula 2b, or a combination of two compounds represented by the following formula 2a and two compounds represented by the following formula 2c, or a combination of two compounds represented by the following formula 2a and two compounds represented by the following formula 2d, or a combination of two compounds represented by the following formula 2b and two compounds represented by the following formula 2c, or a combination of two compounds represented by the following formula 2b and two compounds represented by the following formula 2d, or a combination of two compounds represented by the following formula 2c and two compounds represented by the following formula 2d may be used.

[0277]

[0278] In this way, by mixing and using two or more compounds with different structures among the compounds represented by the following chemical formulas 2a to 2d as the second metallocene compound together with one first metallocene compound, it is possible to produce polyethylene with optimized complex viscosity, relaxation time, and residual stress ratio along with SCB content and BOCD index.

[0279] [Chemical Formula 2a]

[0280]

[0281] [Chemical Formula 2b]

[0282]

[0283] [Chemical Formula 2c]

[0284]

[0285] [Chemical Formula 2d]

[0286]

[0287] In the above chemical formulas 2a to 2d, R1 to R7, M, X1, X2, T1, Y1, and Y2 are as previously defined.

[0288]

[0289] More specifically, in the second metallocene compound of the above formulas 2a to 2d, M is Ti, Zr, or Hf, more specifically Ti; and R1 to R4 are each independently hydrogen, or C 1-20 It is alkyl, more specifically hydrogen or methyl; R5 and R6 are each independently C 1-10 It is alkyl, more specifically, both R5 and R6 are methyl; and the above R7 is C 1-10 It is an alkyl, and more specifically, C such as t-butyl. 3-10 It is a branched alkyl; above, T1 is C or Si, and Y1 is C 1-20 Alkyl, C 1-20 Alkoxy, C2-20 Alkoxyalkyl, C 6-20 Aril, C 7-30 Alkylaryl, C 7-30 Arylalkyl, C 6-20 Aryloxy, or C 7-30 It is aryloxyalkyl, and Y2 is C 2-20 Alkoxyalkyl, or C 7-30 It is an aryloxyalkyl, more specifically, Y1 is any one of a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, and Y2 is C 2-20 Alkoxyalkyl, or C 7-30 It is an aryloxyalkyl, more specifically, Y2 is any one of a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhexyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, a tert-butoxyhexyl group, and a phenoxyhexyl group, and X1 and X2 are each independently a halogen or C 1-20 It may be a compound that is alkyl, and more specifically, chloro or methyl.

[0290]

[0291] More specifically, specific examples of the second metallocene compound may include compounds having the following structures, but are not limited thereto: , ,

[0292] , ,

[0293] , .

[0294]

[0295] Meanwhile, the first and second metallocene compounds in the catalyst composition may be included in a molar ratio of 1:0.3 to 1:3, and more specifically, in a molar ratio of 1:0.3 or higher, or 1:0.4 or higher, or 1:0.5 or higher, and in a molar ratio of 1:3 or lower, or 1:2 or lower.

[0296]

[0297] In addition, two types of second metallocene compounds of different structures in the catalyst composition may be included in a molar ratio of 1:0.1 to 1:1, and more specifically, in a molar ratio of 1:0.1 or higher, or 1:0.2 or higher, or 1:0.4 or higher, and in a molar ratio of 1:1 or lower, or 1:0.8 or lower.

[0298]

[0299] Meanwhile, the catalyst composition may further include a carrier, in which case the first and second metallocene compounds are used in a state supported on the carrier.

[0300]

[0301] Specific examples of the above carriers include silica, alumina, magnesia, silica-alumina, silica-magnesia, etc., and these may further include oxide, carbonate, sulfate, and nitrate components such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0302]

[0303] In addition, the catalyst composition may further include a co-catalyst to improve high activity and process stability, and the co-catalyst may be, more specifically, an alkylaluminoxan-based co-catalyst such as methylaluminoxan, ethylaluminoxan, isobutylaluminoxan, or butylaluminoxan.

[0304]

[0305] Meanwhile, in a polyethylene composition according to one embodiment of the present invention, the aforementioned novel polyethylene is prepared by polymerizing ethylene using the aforementioned catalyst composition, and the polymerization process can be carried out as a monomodal (or unimodal) polymerization process in which a polymerization reaction is performed under single polymerization reaction conditions using a single catalyst in a single reactor, and more specifically, it can be carried out in a single loop-type slurry reactor in the presence of the aforementioned hybrid supported catalyst.

[0306]

[0307] For example, the polymerization process described above can be carried out by additionally adding an alpha-olefin copolymer along with ethylene.

[0308]

[0309] The above alpha-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, 1-eicocene, and mixtures thereof. Preferably, 1-hexene or 1-butene may be used as the alpha-olefin, and more specifically, 1-hexene may be used.

[0310]

[0311] For example, in the polymerization process described above, the alpha-olefin described above may be introduced in an amount of 12% by weight or less relative to the amount of ethylene introduced. Specifically, the alpha-olefin may be introduced in an amount of 10% by weight or less, or 8% by weight or less, or 7.5% by weight or less, or 7% by weight or less, or 6.5% by weight or less, or 6% by weight or less, or 5.8% by weight or less, or 5.5% by weight or less, but is not limited thereto. In addition, the alpha-olefin may be introduced in an amount of 0.1% by weight or more, or 0.3% by weight or more, or 0.5% by weight or more, or 0.7% by weight or more, or 0.85% by weight or more, or 0.9% by weight or more, or 1.0% by weight or more, or 1.2% by weight or more, or 1.4% by weight or more, or 1.6% by weight or more, but is not limited thereto.

[0312]

[0313] In addition, the polyethylene in the present invention can be manufactured by introducing hydrogen gas in the presence of the catalyst composition described above.

[0314]

[0315] Specifically, the polymerization step can be performed by introducing hydrogen gas at a concentration of about 180 ppm to about 480 ppm based on ethylene content. More specifically, hydrogen gas can be introduced at a concentration of about 190 ppm or more, or about 200 ppm or more, or about 220 ppm or more, or about 225 ppm or more, or about 230 ppm or more, or about 235 ppm or more, or about 240 ppm or more, or about 245 ppm or more, and at the same time, can be introduced at a concentration of about 460 ppm or less, or about 450 ppm or less, or about 445 ppm or less, or about 440 ppm or less, or about 435 ppm or less, or about 430 ppm or less.

[0316]

[0317] At this time, the polymerization temperature may be 25 ℃ to 500 ℃, and preferably 25 ℃ to 200 ℃, or 60 ℃ to 120 ℃, or 70 ℃ to 100 ℃, or 72 ℃ to 95 ℃, or 75 ℃ to 90 ℃, or 78 ℃ to 88 ℃, or 80 ℃ to 85 ℃.

[0318]

[0319] In addition, the polymerization pressure may be 1 Kgf / ㎠ to 100 Kgf / ㎠, preferably 1 Kgf / ㎠ to 70 Kgf / ㎠, or 2 Kgf / ㎠ to 50 Kgf / ㎠, or 5 Kgf / ㎠ to 50 Kgf / ㎠, or 8 Kgf / ㎠ to 45 Kgf / ㎠, or 10 Kgf / ㎠ to 42 Kgf / ㎠.

[0320]

[0321] Meanwhile, polyethylene according to one embodiment of the present invention may further include one or more additives selected from the group consisting of antioxidants, neutralizing agents, slip agents, anti-blocking agents, reinforcing agents, fillers, weather stabilizers, antistatic agents, lubricants, nucleating agents, flame retardants, pigments, and dyes together with the polyethylene described above, but is not particularly limited to these.

[0322]

[0323] In a specific embodiment of the present invention, the polyethylene described above may be used with an additional antioxidant to increase its heat stability. In this case, the content of the antioxidant may be 0.05% or more and 0.75% or less relative to the weight of the polyethylene. Preferably, the antioxidant may be 0.06% or more, or 0.08% or more, or 0.1% or more, or 0.12% or more, or 0.15% or more, and may also be 0.73% or less, or 0.7% or less, or 0.68% or less, or 0.65% or less, or 0.63% or less, or 0.6% or less, or 0.5% or less, or 0.4% or less, or 0.35% or less, or 0.3% or less.

[0324]

[0325] Here, the antioxidant may be a phenolic antioxidant, a phosphorus-based antioxidant, etc. Specifically, the phenolic antioxidants are pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate, product name: Irganox 1010), octadecyl-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (product name: Irganox 1076), and 3,3',3',5,5',5'-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl)tri-p-cresol The above phosphorus-based antioxidant may be one or more selected from the group consisting of (3,3',3',5,5',5'-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl) tri-p-cresol, product name: Irgaonx 1330), but is not particularly limited thereto. In addition, the above phosphorus-based antioxidant may be one or more selected from the group consisting of tris(2,4-di-tert-butylphenyl) phosphite (product name: Irafos 1680) and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (product name: Eunox AO-626), but is not particularly limited thereto.

[0326]

[0327] In addition, in a specific embodiment of the present invention, a neutralizing agent may be further included to remove residual catalyst components in the polyethylene described above. At this time, the content of the neutralizing agent may be 0.01% or more and 0.2% or less relative to the weight of the polyethylene. Preferably, the neutralizing agent may be 0.02% or more, or 0.03% or more, or 0.04% or more, or 0.05% or more, or 0.15% or more, and may also be 0.18% or less, or 0.17% or less, or 0.15% or less, or 0.12% or less, or 0.1% or less.

[0328]

[0329] Here, the above neutralizing agent may include calcium stearate, etc., but is not specifically limited to these.

[0330]

[0331] In addition, the above-mentioned additives, such as antioxidants or neutralizing agents, may be used after undergoing a process such as dry mixing with the aforementioned polyethylene, and may be manufactured into pellet form through an extrusion process after such dry mixing, but are not particularly limited to these.

[0332]

[0333] Meanwhile, according to another embodiment of the invention, a polyethylene composition is provided comprising virgin polyethylene (or Booster PE) and recycled polyethylene (PCW PE, Post consumer waste polyethylene), wherein the virgin polyethylene is the polyethylene of the above-described embodiment or a mixture thereof.

[0334]

[0335] In particular, the polyethylene composition according to the present invention uses polyethylene in which the molecular structure is optimized as described above, and the complex viscosity, relaxation time, and residual stress ratio are all optimized along with the SCB content and BOCD index. This allows for the improvement of environmental stress cracking resistance (ESCR) while maintaining excellent mechanical properties when combined with recycled polyethylene, thereby improving processability and providing excellent surface impact when combined with recycled polyethylene, and improving the drop impact of the final product.

[0336]

[0337] Accordingly, the polyethylene composition of the present invention can produce a molded article having high mechanical properties along with excellent environmental stress cracking resistance (ESCR) even when combined with recycled polyethylene resin by using the polyethylene of the above-described embodiment.

[0338]

[0339] For example, in a polyethylene composition, the virgin polyethylene may be included in an amount of 5% or more by weight or from 5% to 85% by weight based on the total weight of the composition, and the recycled polyethylene may be included in an amount of 15% or more by weight or from 15% to 95% by weight based on the total weight of the composition. In particular, to enhance the carbon dioxide emission suppression effect of the polyethylene composition and to reduce costs, the content of the virgin polyethylene may be 85% or less by weight, or 50% or less by weight, or 30% or less by weight, and the content of the recycled polyethylene resin (PCW PE) may be 15% or more by weight, or 20% or more by weight, or 30% or more by weight. In addition, in terms of improving processability and having excellent surface impact when the polyethylene composition is blended with recycled polyethylene, enhancing drop impact of the final product, and achieving physical properties equivalent to those of virgin resin, the content of the virgin polyethylene may be 5 weight% or more, or 7 weight% or more, or 10 weight% or more, and the content of the recycled polyethylene resin (PCW PE) may be 95 weight% or less, or 80 weight% or less, or 60 weight% or less.

[0340]

[0341] Here, the total sum of the new polyethylene content and the recycled polyethylene content does not exceed 100%.

[0342]

[0343] Meanwhile, the above-mentioned novel polyethylene may additionally include high-density polyethylene together with the polyethylene of the above-described embodiment.

[0344]

[0345] For example, the high-density polyethylene among the above-mentioned virgin polyethylene may be included in an amount of 80% by weight or less, or 0 to 80% by weight or less, based on the total weight of the entire composition. In particular, to enhance the carbon dioxide emission suppression effect of the polyethylene composition and to reduce costs, the content of high-density polyethylene among the above-mentioned virgin polyethylene may be 80% by weight or less, 70% by weight or less, or 60% by weight or less. In addition, to ensure that the polyethylene composition has excellent surface impact and improved processability when blended with recycled polyethylene, enhances drop impact of the final product, and achieves physical properties equivalent to those of virgin resin, the content of high-density polyethylene among the above-mentioned virgin polyethylene may be 5% by weight or more, 20% by weight or more, or 40% by weight or more.

[0346]

[0347] Specifically, the high-density polyethylene additionally included as the novel polyethylene has a density (ASTM D 1505, 23 °C) of 0.955 g / cm³ 3 Above or 0.955 g / cm³ 3 Up to 0.965 g / cm³ 3 It may be. More specifically, the density of the high-density polyethylene is 0.956 g / cm³ 3 Above, or 0.957 g / cm³ 3 Above, or 0.958 g / cm³ 3 It may be greater than 0.963 g / cm³ 3 Less than or equal to 0.962 g / cm³ 3 Less than or equal to 0.961 g / cm³ 3 Less than or equal to 0.960 g / cm³ 3 It may be less than.

[0348]

[0349] In addition, the above high-density polyethylene has a melt index (MI 2.16 , 190 oC (measured under a 2.16 kg load) may be 0.1 g / 10 min to 0.5 g / 10 min.

[0350]

[0351] In addition, the above high-density polyethylene may have an environmental stress cracking resistance (ESCR) of 200 hours or more or 200 to 400 hours as measured according to ASTM D 1693 (Condition B, F50, Igepal 10%).

[0352]

[0353] Meanwhile, the above recycled polyethylene (PCW PE) has a density (ASTM D 1505, 23 ℃) of 0.940 g / cm³ 3 Up to 0.960 g / cm³ 3 It can be represented by such characteristics. More specifically, the density of the recycled polyethylene (PCW PE) (ASTM D 1505, 23 ℃) is 0.943 g / cm³. 3 Above, or 0.945 g / cm³ 3 Above, or 0.948 g / cm³ 3 Above, or 0.950 g / cm³ 3 It may be greater than 0.958 g / cm³ 3 Less than or equal to 0.956 g / cm³ 3 Less than or equal to 0.955 g / cm³ 3 Less than or equal to 0.953 g / cm³ 3 It may be less than.

[0354]

[0355] In addition, the above recycled polyethylene (PCW PE) has a melt index (MI 2.16 , 190 o C (measured under a 2.16 kg load) may be 0.1 g / 10 min to 0.7 g / 10 min.

[0356]

[0357] In addition, the above recycled polyethylene (PCW PE) may have an environmental stress cracking resistance (ESCR) of 20 to 60 hours as measured according to ASTM D 1693 (Condition B, F50, Igepal 10%).

[0358]

[0359] Meanwhile, the polyethylene composition according to the present invention has excellent drop impact strength without changing processability while increasing the recycled polyethylene content, and with excellent impact strength, tensile strength, chemical resistance, and thermal stability comparable to virgin resin, it is possible to simultaneously secure excellent processability and high drop strength while achieving high loading strength with excellent mechanical properties when used as a blow container.

[0360]

[0361] Specifically, the above polyethylene composition may have an environmental stress cracking resistance (ESCR) of 200 hours or more, measured according to ASTM D 1693 (Condition B, F50, Igepal 10%). For example, the method for measuring the environmental stress cracking resistance (ESCR) is as described in Test Example 2 below. However, the environmental stress cracking resistance (ESCR) is not limited thereto and may be measured by other methods known in the art to which the present invention belongs. The polyethylene composition of the present invention, with its excellent ESCR characteristics as described above, can simultaneously secure excellent processability and high drop strength along with excellent mechanical properties when used as a blow container.

[0362]

[0363] In addition, the above polyethylene composition may have an energy, i.e., a face impact strength, measured according to the ASTM D 3763 method under conditions of an impact energy of 15.5 J, an impact velocity of 4.55 m / s, and a temperature of 5 ℃, which is 7.5 J or more, or 7.5 J or more and 30 J or less. For example, the method for measuring the face impact strength is as described in Test Example 2 below. However, the face impact strength is not limited thereto and may be measured by other methods known in the art to which the present invention belongs. Preferably, the face impact strength of the above polyethylene composition may be 7.6 J or more, or 7.8 J or more, or 8 J or more, or 8.1 J or more, or 8.2 J or more, or 8.3 J or more, or 8.4 J or more, or 8.5 J or more, or 8.6 J or more, or 8.8 J or more, or 9 J or more, or 9.1 J or more.

[0364]

[0365] In addition, the polyethylene composition may have an SCB content of 1.8 (pieces / 1000C) or more, or 1.8 to 5 (pieces / 1000C).

[0366]

[0367] In addition, the polyethylene composition may have a BOCD index (Broad Orthogonal Co-monomer Distribution Index) of 0.7 or higher, or 0.7 to 1.8.

[0368]

[0369] In addition, the polyethylene composition may have a weight-average molecular weight of 130,000 g / mol to 160,000 g / mol and a molecular weight distribution (Mw / Mn) of 15.0 to 21.5.

[0370]

[0371] In addition, the above polyethylene composition has a melt index (MI) measured at 190°C and a 2.16 kg load according to ASTM D 1238. 2.16 ) may be 0.2 g / 10min to 0.5 g / 10min, or 0.25 g / 10min to 0.33 g / 10min.

[0372]

[0373] In addition, the polyethylene composition has a density (ASTM D 1505, 23 °C) of 0.945 g / cm³ 3 Above or 0.945 g / cm³ 3 Up to 0.960 g / cm³ 3 It could be.

[0374]

[0375] At this time, the SCB content, BOCD index, weight-average molecular weight, molecular weight distribution (Mw / Mn), and melt index (MI) of the polyethylene composition 2.16 The measurement methods for density, etc., are as described above with respect to polyethylene, and can be used to measure polyethylene compositions instead of polyethylene using these methods, and specific details are omitted.

[0376]

[0377] Preferred embodiments are presented below to aid in understanding the present invention. However, the following embodiments are provided merely to facilitate a better understanding of the invention and do not limit the scope of the invention.

[0378]

[0379] [Example]

[0380] Manufacture of Polyethylene

[0381] Example 1-1

[0382] High-density polyethylene was manufactured through a single slurry polymerization process as follows.

[0383]

[0384] First, 25 kg / h of isobutane and 30 kg / h of ethylene were injected into a single slurry loop reactor, along with hydrogen at a flow rate of 245 ppm. Subsequently, a catalyst (molar ratio of first metallocene compound (1), second metallocene compound (2), and second metallocene compound (3) = 1:0.41:0.2) in which the first metallocene compound (1), second metallocene compound (2), and second metallocene compound (3) were hybrid-supported on a silica carrier (Grace Davison, SP2212) and a comonomer (1-hexene) were injected. The comonomer used here was 1-hexene, and the input amount was 5.4 wt% relative to the ethylene input amount. At this time, the reactor was maintained between 80 and 85 ℃, and the pressure was 42 kg / cm². 3 A copolymerization process was performed by maintaining the solvent, and subsequently, a high-density ethylene / 1-hexene copolymer was prepared in powder form through a solvent removal facility and a dryer.

[0385]

[0386] The high-density ethylene / 1-hexene copolymer prepared in this way was dry-blended with 1000 ppm of Irganox 1010 (BASF), 1500 ppm of Irgafos 168 (BASF), and 500 ppm of Calcium stearate (Daemyung Chemical), and then processed into pellets using a Twin Screw (SM Platec) extruder to produce the high-density virgin polyethylene (HDPE, Virgin polyethylene) of Example 1-1. At this time, the extruder temperature was operated at 190–220 ℃ and the die temperature at 210 ℃.

[0387]

[0388] (1)

[0389] (2) (3).

[0390]

[0391] Examples 1-2

[0392] The same polymerization and pelletizing processes as in Example 1-1 were performed, but the amount of Irgafos 168 (BASF) was changed to 6000 ppm during the pelletizing process to produce the high-density new polyethylene of Example 1-2.

[0393]

[0394] Examples 1-3

[0395] The same polymerization and pelletizing processes as in Example 1-1 were performed, but the hydrogen content in the polymerization process was changed to 430 ppm and the coconomer (1-hexene) content to 2.3 wt% to homopolymerize, thereby producing the high-density new polyethylene of Example 1-3.

[0396]

[0397] Examples 1-4

[0398] The same polymerization and pelletizing processes as in Example 1-1 were performed, but the hydrogen content in the polymerization process was changed to 270 ppm and the comonomer(1-hexene) content to 1.6 wt% to homopolymerize, thereby producing the high-density new polyethylene of Example 1-4.

[0399]

[0400] Comparative Example 1-1

[0401] A commercially available high-density polyethylene (HDPE) product manufactured using a chromium catalyst (product of DL Chemical, product name TR570) was prepared as the high-density new polyethylene of Comparative Example 1-1.

[0402]

[0403] Comparative Example 1-2

[0404] High-density new polyethylene of Comparative Example 1-2 was produced by performing the same polymerization process as in Example 1-1, but by adding a catalyst (molar ratio of the first metallocene compound and the second metallocene compound = 2:1) in which the following first metallocene compound (1) and second metallocene compound (2) were hybridized and supported on a silica carrier (Grace Davison, SP2212), and by changing the hydrogen to 220 ppm and the coconomer (1-hexene) to 1.5 wt% to homopolymerizing.

[0405] (1) (2).

[0406]

[0407] Comparative Examples 1-3

[0408] A commercially available high-density polyethylene (HDPE) product manufactured using a metallocene catalyst (LG Chem product, product name SP4701) was prepared as the high-density new polyethylene of Comparative Example 1-3.

[0409]

[0410] Comparative Examples 1-4

[0411] A commercially available high-density polyethylene (HDPE) product manufactured using a Ziegler-Natta catalyst (product of Lotte Chemical, product name 8301B) was prepared as the high-density new polyethylene of Comparative Example 1-4.

[0412]

[0413] Comparative Examples 1-5

[0414] The same polymerization process as in Comparative Example 1-2 was performed, but with hydrogen changed to 200 ppm and Commonomer (1-hexene) to 0.9 wt%, and homopolymerization was carried out to produce the high-density polyethylene of Comparative Example 1-5(a). The high-density polyethylene of Comparative Example 1-5(a) prepared in this way was mixed with 80 wt% of the high-density polyethylene of Comparative Example 1-2 prepared earlier to prepare the new high-density polyethylene of Comparative Example 1-5.

[0415]

[0416] <Test Example 1: Evaluation of Physical Properties of Polyethylene>

[0417] The physical properties of the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 were evaluated in the following manner, and the measurement results are shown in Table 1 below.

[0418]

[0419] (1) Melt index

[0420] 190 according to the American Society for Testing and Materials standard ASTM D 1238 (Condition E) o Each melt index (MI) under C with loads of 2.16 kg and 21.6 kg 2.16 ) and Melt Index (MI 21.6 ) was measured and expressed as the weight (g) of the polymer that melted out over 10 minutes.

[0421]

[0422] Specifically, for the polyethylenes of Examples 1-1 to 1-4 and Comparative Examples 1-2 to 1-5, the respective melt index (MI) measured under a load of 2.16 kg 2.16 ) is shown in Table 1 below, and the melt index (MI) measured under a load of 21.6 kg for the polyethylene of Comparative Example 1-1 21.6 ) is shown in Table 1 below.

[0423]

[0424] (2) Density

[0425] Density of polyethylene (g / cm³) according to the American Society for Testing and Materials (ASTM) D 1505 standard 3 ) was measured.

[0426]

[0427] (3) Weight-average molecular weight (Mw, g / mol) and molecular weight distribution (PDI, polydispersity index, Mw / Mn)

[0428] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polyethylene were measured using gel permeation chromatography (GPC, manufactured by Polymer Char), and the molecular weight distribution (PDI, Mw / Mn) was calculated by dividing the weight-average molecular weight by the number-average molecular weight.

[0429]

[0430] Specifically, a PolymerChar GPC-IR instrument was used as the gel permeation chromatography (GPC) device, and a Polymer Laboratories PLgel MIX-B 300 mm long column was used. The measurement temperature was 160 ℃, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was 1 mL / min. Polyethylene samples according to Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 were each pretreated by dissolving them in trichlorobenzene (1,2,4-trichlorobenzene) containing 0.0125% butylated hydroxytoluene (BHT) at 160 ℃ for 2 hours using a GPC analyzer (GPC-IR), 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 polystyrene standard specimens with 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 10000000 g / mol.

[0431]

[0432] (4) SCB content

[0433] SCB ( / 1000TC) was measured for the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 at 160 ℃ using GPC-IR equipment.

[0434]

[0435] Specifically, the sample was pretreated by melting it in 1,2,4-Trichlorobenzene containing 0.0125% BHT at 160 ℃ for 2 hours, and then measured at 160 ℃ using IR4 and IR6 connected to a high-temperature GPC (GPC-IR).

[0436]

[0437] (5) BOCD index

[0438] As described above, the SCB (Short Chain branch) content was measured at the left and right boundaries of the middle 60% excluding the left and right ends relative to the total area of ​​the GPC curve graph, which is a log graph of the weight-average molecular weight (Mw) of the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 measured through GPC analysis, i.e., a GPC curve graph where the x-axis is log MW and the y-axis is dw / dlogMw, and the BOCD was measured as shown in Equation 1 below.

[0439] [Equation 1]

[0440] .

[0441] At this time, the SCB content in the high molecular weight region and the SCB content in the low molecular weight region refer to the SCB content value at logMw corresponding to 20% of the high molecular weight region and the low molecular weight region, respectively, and the high molecular weight log Mw and low molecular weight log Mw values ​​are the logMw values ​​corresponding to 20% of the high molecular weight region and the low molecular weight region, respectively, relative to the total area of ​​the y-axis (dw / dlogMw) and x-axis (logMw) curves through GPC analysis.

[0442]

[0443] (6) Complex Viscosity

[0444] Complex Viscosity (0.05 rad / s and 500 rad / s, Pa.s) was measured for the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 at 190 ℃, 0.05 rad / s, and 500 rad / s, respectively, using an ARES-G2 instrument.

[0445]

[0446] (7) Relaxation time (seconds)

[0447] A stress relaxation test was performed on the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5, and the relaxation time was measured in seconds.

[0448]

[0449] Specifically, the relaxation time (seconds) of polyethylene was determined by measuring the viscosity at each temperature at 150 °C, 170 °C, 190 °C, 210 °C, and 230 °C at a strain of 0.5% using the ARES-G2 rotary rheometer from TA Instruments (New Castle, Delaware, USA) at each angular frequency of 0.05 rad / s to 500 rad / s. From the viscosity values ​​measured at each temperature, the relaxation time (seconds) at each temperature was calculated using the cross model of Equation 2 below.

[0450] [Equation 2]

[0451] η = η ∞ + (η0 - η ∞ ) / (1 + λ × (Shear rate) m )

[0452] In the above Equation 2,

[0453] The above η is the viscosity of polyethylene measured using a rotational rheometer under conditions of each measurement temperature among 150 ℃, 170 ℃, 190 ℃, 210 ℃, and 230 ℃ and each frequency (Angular Frequency) of 0.05 rad / s to 500 rad / s, and

[0454] The above η ∞ is an infinite shear viscosity, and

[0455] The above η0 is the zero-point shear viscosity, and

[0456] The above shear rate is the shear rate applied to polyethylene and is equal to the angular frequency, and

[0457] The above λ and m are parameters obtained by fitting a log-log graph with angular frequency on the x-axis and viscosity measurement η on the y-axis using the cross model of Equation 2,

[0458] The above λ is the relaxation time (seconds) of polyethylene, which is the reciprocal of the angular frequency at which viscosity η begins to decrease, and

[0459] The above m is the slope of viscosity η in the region where viscosity η decreases.

[0460]

[0461] In addition, through the Arrhenius plot based on the relaxation time (seconds) measured at each temperature as described above, the relaxation time (RT) at 120 ℃ 120℃ ) was estimated.

[0462]

[0463] For example, the Arrhenius constant (A) was obtained through an Arrhenius plot based on the relaxation time (seconds) for each temperature, and the relaxation time of polyethylene was calculated according to Equation 3 below.

[0464] [Equation 3]

[0465] lnK = LnA + E a / RT

[0466] In the above Equation 3,

[0467] The above K is the relaxation time (seconds) of polyethylene, and

[0468] Ea is the activation energy (J / mol), and

[0469] R is the gas constant (8.314 J / mol·K), and

[0470] A is the Arrhenius constant, and

[0471] T is absolute temperature (Kelvin).

[0472]

[0473] (8) Residual stress ratio (%)

[0474] For the polyethylene of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5, a sample was taken and a strain of 60% was applied at 190°C, and the change in residual stress was measured for 10 minutes.

[0475]

[0476] For the measurement of the above residual stress, the ARES-G2 rotary rheometer from TA Instruments (New Castle, Delaware, USA) was used, and the sample was sufficiently loaded between upper and lower plates with a diameter of 25 mm, melted at 190 ℃, and then measured with the gap fixed at 1 mm.

[0477]

[0478] Based on the measured residual stress data, the ratio of residual stress (RS%) was calculated according to Equation 4 below and is shown in Table 1 below:

[0479] [Equation 4]

[0480] Residual stress ratio = (RS1 / RS0)×100

[0481] In the above Equation 4,

[0482] RS0 is the residual stress at any point in time (t0) of less than 0.05 seconds after applying 60% deformation to the polyethylene at 190 ℃, and

[0483] RS1 is the residual stress at any point in time (t1) between 0.05 seconds and 90 seconds after applying 60% deformation to the polyethylene at 190°C.

[0484]

[0485] Specifically, in Equation 4 above, t0 was 0.02 seconds and t1 was 60 seconds, and the residual stress ratio (%) was calculated from the measured residual stress values ​​and shown in Table 1 below.

[0486]

[0487] MI (g / 10 min) Density (g / cm²) 3)Mw(g / mol)PDI(Mn / Mw)SCB(piece / 1000C)BOCDComplex Viscosity(0.05 rad / s)Complex Viscosity(500 rad / s)RelaxationTime(s)Residual Stress Ratio(%) Example 1-10.55(2.16 kg load)0.94614810022.45.26.1724,3453321.10.036 Example 1-20.55(2.16 kg load)0.94614320022.15.26.1718,8403350.90.023 Example 1-31.08(2.16 kg Load) 0.95111680023.54.13.2710,9543551.40.059 Example 1-40.22 (2.16 kg Load) 0.95017830024.63.02.345,5515132.90.223 Comparative Example 1-13.1 (21.6 kg) 0.95030740029.00.70.15202,721947520.508 Comparative Example 1-20.51 (2.16 kg Load) 0.94714360016.82.51.6822,6344371.80.104 Comparative Example 1-30.17 (2.16 kg Load)0.94721030021.32.30.953,5306301.80.264 Comparative Example 1-40.04(2.16 kg Load)0.95125050019.53.01.51116,26381111.90.402 Comparative Example 1-50.45(2.16 kg Load)0.94613570015.84.52.1393184665.90.280

[0488]

[0489] In Table 1 above, the melt index measurements are the respective melt index (MI) measured under a load of 2.16 kg for the polyethylenes of Examples 1-1 to 1-4 and Comparative Examples 1-2 to 1-5. 2.16 ) was shown, and for the polyethylene of Comparative Example 1-1, the melt index (MI) measured under a load of 21.6 kg was 21.6 It represented ).

[0490]

[0491] <Preparation of Polyethylene Compound (PCR Compound) Mixed with Recycled Polyethylene (PCW PE)>

[0492] Example 2-1

[0493] 10 wt% of the polyethylene prepared in Example 1-1 and 60 wt% of high-density polyethylene (product of Lotte Chemical, product name 6200B) were used as virgin polyethylene, and 30 wt% of recycled polyethylene (PCW PE, Post consumer waste polyethylene) were dry blended and then extruded through a twin screw extruder to prepare the polyethylene composition (PCR Compound) of Example 2-1.

[0494]

[0495] Specifically, the high-density polyethylene is a commercially available Booster Grade high-density polyethylene (HDPE) product for PCR manufactured using a Ziegler-Natta catalyst (Z / N, Zeigier-Natta catalyst) (product of Lotte Chemical, product name 6200B).

[0496]

[0497] In addition, the above-mentioned recycled polyethylene (BSN Baeksan natural color product of Baeksan Plastic Co., Ltd.) has a melt index MI 2.16 (190 according to ASTM D 1238 (Condition E) o (Measured under a 2.16 kg load at C) is at the level of 0.15–0.2 g / 10 min, and the density (measured according to ASTM D 1505 standard) is 0.951–0.953 g / cm³ 3 , ESCR (measured the time to F50 (50% destruction) under 50°C conditions using 10% Igepal CO-630 Solution according to ASTM D 1693) is at the 40–50 hour level.

[0498]

[0499] Examples 2-2 to 2-4

[0500] Polyethylene resin compositions (PCR Compounds) were prepared in the same manner as in Example 2-1, but using the polyethylene of Examples 1-2 to 1-4 instead of the polyethylene of Example 1-1, and mixing recycled polyethylene (PCW PE) in the same manner as in Example 2-1 to prepare the polyethylene compositions (PCR Compounds) of Examples 2-2 to 2-4.

[0501]

[0502] Comparative Examples 2-1 to 2-5

[0503] Polyethylene resin compositions (PCR Compounds) were prepared in the same manner as in Example 2-1, but using the polyethylene of Comparative Examples 1-1 to 1-5 instead of the polyethylene of Example 1-1, and mixing recycled polyethylene (PCW PE) in the same manner as in Example 2-1 to prepare the polyethylene compositions (PCR Compounds) of Comparative Examples 2-1 to 2-5.

[0504]

[0505] <Test Example 2: Evaluation of Physical Properties of Polyethylene Composition>

[0506] For the polyethylene compositions (PCR Compound) of Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-5 prepared as described above, complex viscosity and relaxation time were measured as described in the previous evaluation of the physical properties of polyethylene, and the face impact strength and ESCR measurements were evaluated as follows, and the measurement results are shown in Table 2 below.

[0507]

[0508] (7) Surface impact

[0509] A disc was manufactured based on a polyethylene composition (PCR Compound) in the following manner, and a weight was dropped onto the disc to measure the energy (J) at which a crack occurs, which is shown as a surface impact in Table 2 below.

[0510]

[0511] 7-1. Manufacture of Surface Impact Discs

[0512] - The disc was manufactured using an injection molding machine, with the temperature gradient set to 210–230 ℃, PCR Compound injected, and produced at an injection speed of 11 mm / s and a holding pressure of 450 bar.

[0513] - Disc size (diameter 50 mm, thickness 2 mm).

[0514]

[0515] 7-2. Surface Impact Assessment

[0516] - Measure face impact strength using the ASTM D 3763 method

[0517] Specifically, using the Instron 9440 (Impact Drop Tower) product, the energy at which a crack occurs was measured by dropping a weight after fixing the disc (J, Impact energy 15.5 J, Impact velocity 4.55 m / s, Temperature 5 ℃).

[0518]

[0519] (8) ESCR measurement value

[0520] According to the method of ASTM D 1693-07, the time to F50 (50% destruction) for a polyethylene composition (PCR Compound) was measured using 10% Igepal CO-630 Solution at a temperature of 50 ℃ under Condition B, and is expressed as ESCR (hr) in Table 2 below.

[0521]

[0522] Polyethylene content (wt%) High-density polyethylene content (wt%) Recycled polyethylene resin (PCW PE) content (wt%) Complex Viscosity (0.05 rad / s) Complex Viscosity (500 rad / s) Relaxation Time (s) Residual stress ratio (%) Surface impact strength (at 5 ℃, J) ESCR (hr) Example 2-1 10 60 30 48,8 9 45 0 9 19.7 0.4 5 6 7.6 30 0 Example 2-2 10 60 30 43,05 34 9 9 16 0.3 12 9.1 31 0 Example 2-3 10 60 30 45,6 29 5 0 9 21.9 0.4 0 7 8.5 21 0 Example 2-410603053,22351022.50.4869.2250Comparative Example 2-110603069,81359880.60.8126.6150Comparative Example 2-210603043,26851315.90.4477.8180Comparative Example 2-310603056,32551825.40.5018170Comparative Example 2-410603063,97757460.40.6676.5190Comparative Example 2-510603061,12051227.20.4476.9200

[0523]

[0524] Referring to Table 2 above, it can be seen that when using the polyethylene of Examples 1-1 to 1-4, in which the complex viscosity, relaxation time, and residual stress ratio are all optimized along with the SCB content and BOCD index according to the present invention, excellent face impact strength is exhibited when combined with recycled polyethylene (PCW PE), and at the same time, environmental stress cracking resistance (ESCR) can be significantly improved.

Claims

1. The SCB content is 3.0 (pieces / 1000C) or higher, and The BOCD (Broad Orthogonal Co-monomer Distribution Index) is 2 or higher, and The complex viscosity (η*(ω500)) measured at a frequency (ω) of 500 rad / s is 700 Pa·s or less, and The relaxation time is 4 seconds or less, and A residual stress ratio of 0.25% or less, Polyethylene.

2. In Paragraph 1, The above polyethylene is an ethylene homopolymer or an ethylene / alpha-olefin copolymer, Polyethylene.

3. In Paragraph 2, The above alpha-olefin is 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, 1-eicocene, and mixtures thereof. Polyethylene.

4. In Paragraph 1, The above polyethylene has a complex viscosity (η*(ω0.05), complex viscosity) measured at a frequency (ω) of 0.05 rad / s of 5,000 Pa·s or more and 60,000 Pa·s or less, Polyethylene.

5. In Paragraph 1, The above polyethylene has a molecular weight distribution (Mw / Mn) of 20 or more, Polyethylene.

6. In Paragraph 1, The above polyethylene has a weight-average molecular weight of 100,000 g / mol or more, Polyethylene.

7. In Paragraph 1, The above polyethylene has a melt index (MI) measured at 190°C and a 2.16 kg load according to ASTM D 1238. 2.16 ) having 0.1 g / 10 min to 1.2 g / 10 min, Polyethylene.

8. In Paragraph 1, The above polyethylene has a density of 0.935 g / cm³ 3 Lee Sang-in, Polyethylene.

9. A polyethylene composition comprising virgin polyethylene and recycled polyethylene (PCW PE, Post consumer waste polyethylene), The above-mentioned novel polyethylene is polyethylene or a mixture thereof according to any one of claims 1 to 8, Polyethylene composition.

10. In Paragraph 9, The above-mentioned novel polyethylene is included in an amount of 5% by weight or more based on the total weight of the entire composition, and The above recycled polyethylene is included in an amount of 15 weight percent or more based on the total weight of the entire composition, Polyethylene composition.

11. In Paragraph 9, The above-mentioned novel polyethylene further comprises high-density polyethylene, Polyethylene composition.

12. In Paragraph 9, The above recycled polyethylene has a melt index (MI) measured at 190°C and a 2.16 kg load according to ASTM D 1238. 2.16 ) having 0.1 g / 10 min to 0.7 g / 10 min, Polyethylene composition.

13. In Paragraph 9, The above recycled polyethylene has a density of 0.940 g / cm³ 3 Up to 0.960 g / cm³ 3 person, Polyethylene composition.

14. In Paragraph 9, The above polyethylene composition is, Environmental stress crack resistance (ESCR) measured according to ASTM D 1693 (Condition B, F50, Igepal 10%) is 200 hours or more, Polyethylene composition.

15. In Paragraph 9, The above polyethylene composition is, With an energy of 7.5 J or higher measured under conditions of an impact energy of 15.5 J, an impact velocity of 4.55 m / s, and a temperature of 5 ℃ according to the ASTM D 3763 method, Polyethylene composition.

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