Polyethylene and film comprising same

Abstract

The present invention provides polyethylene having excellent low-temperature sealing properties, sealing stability, and process reliability, and a film comprising same.

Description

Polyethylene and films containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0073747, filed June 5, 2024, and Korean Patent Application No. 10-2025-0073934, filed June 5, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to polyethylene having excellent low-temperature sealing properties, processability and process reliability, and to a film comprising the same.

[0004]

[0005] Linear low density polyethylene (LLDPE) is a resin manufactured by copolymerizing ethylene and alpha-olefin at low pressure using a polymerization catalyst. It has a narrow molecular weight distribution, short-chain branches of a certain length, and no long-chain branches.

[0006] Linear low-density polyethylene film has the characteristics of general polyethylene, as well as high breaking strength and elongation, excellent film processability and transparency, and superior tear strength and drop impact strength, so its use is increasing in industrial films such as food packaging and industrial laminated films, heavy-duty films, and stretch wrap films, where conventional low-density polyethylene or high-density polyethylene is difficult to apply.

[0007] Linear low-density polyethylene (LPE) is generally known to exhibit increased drop impact strength as density decreases. However, the use of large amounts of comonomers to manufacture LPE can lead to increased fouling during the slurry polymerization process, and the resulting film can become sticky, necessitating increased use of anti-blocking agents. Furthermore, production processes can become unstable, and the resulting polyethylene morphology can deteriorate, resulting in a decrease in bulk density.

[0008] Due to recent market trends in sustainability and D4R (Design For Recyclability), the demand for down-gauging (D / G) is increasing, and accordingly, the demand for linear low-density polyethylene with excellent molding processability and drop impact strength is also increasing.

[0009] Before COVID-19, D / G focused on reducing the thickness of the polyethylene layer in multilayer films from a cost perspective. However, after COVID-19, with the increased interest in environmental issues, the demand for downgauging from a recycling perspective and energy consumption issues for carbon reduction have emerged.

[0010] In addition, the D4R design from the recycling perspective is attracting attention to promote and activate the transition to a resource circular economy, and the demand for improved sealing properties of the sealant layer during co-extrusion or bonding in the manufacturing process of BOPE (Biaxially Oriented Polyethylene) film and MDO (Machine Direction Orientation) film applied to single-material All-PE film is increasing.

[0011]

[0012] In order to solve the problems of the above prior art, the present invention aims to provide polyethylene having excellent low-temperature sealing properties, processability and process reliability.

[0013] In addition, the present invention seeks to provide a film comprising the polyethylene.

[0014]

[0015] According to the present invention,

[0016] The shear stress expressed by the following equation 1 is 0.2 MPa or less,

[0017] Satisfying the following equation 2,

[0018] We provide polyethylene:

[0019] [Formula 1]

[0020] Shear stress = [{G'(@125)} 2 + {G”(@125)} 2 ] 1 / 2

[0021] In the above equation 1,

[0022] G'(@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0023] G”(@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0024] [Formula 2]

[0025] 30 ≤ 0.0227 * RSS 125 * 1000 - H ≤40

[0026] In the above equation 2,

[0027] RSS 125 silver , wherein G' (@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s, and G” (@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0028] H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

[0029]

[0030] In addition, according to the present invention, a film including the polyethylene is provided.

[0031]

[0032] The polyethylene according to the present invention exhibits excellent low-temperature sealing properties, processability, and process reliability. Furthermore, the polyethylene exhibits excellent drop impact strength and rigidity. Accordingly, downgauging is possible during film production using the polyethylene, making it advantageous for D4R applications.

[0033] The above polyethylene can be usefully used in multipurpose films such as food, agricultural, general industrial films, or stretch films, and can be applied to a sealant layer during coextrusion or bonding in the manufacturing process of BOPE (Biaxially Oriented Polyethylene) film and MDO (Machine Direction Orientation) film applied to a single-material All-PE film.

[0034] Additionally, it is advantageous in responding to PPWR as it does not contain PFAS (Per- and Polyfluoroalkyl Substances), which are subject to the Packaging and Packaging Waste Regulation (PPWR) implemented by the European Union (EU).

[0035]

[0036] Figure 1 is a graph showing polyethylene of examples and comparative examples of the present invention, with the x-axis representing shear rate and the y-axis representing shear stress.

[0037] Figure 2 shows an image of the surface shape of an extruded polyethylene product of an example and a comparative example of the present invention, taken using a stereoscopic microscope.

[0038]

[0039] In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0040] Furthermore, the terminology used herein is merely for the purpose of describing exemplary embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprise," "include," or "have" indicate the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0041] Additionally, the term “to” used in describing a numerical range in this specification includes both the upper and lower limits. For example, “1 to 3” means 1 or more and 3 or less.

[0042] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this is not intended to limit the present invention to specific disclosed forms, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0043] Hereinafter, the polyethylene of the present invention and the film containing the same will be described in detail.

[0044]

[0045] Polyethylene according to one embodiment of the present invention satisfies a shear stress expressed by the following formula 1 of 0.2 MPa or less and satisfies the following formula 2:

[0046] [Formula 1]

[0047] Shear stress = [{G'(@125)} 2 + {G”(@125)} 2 ] 1 / 2

[0048] In the above equation 1,

[0049] G'(@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0050] G”(@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0051] [Formula 2]

[0052] 30 ≤ 0.0227 * RSS 125 * 1000 - H ≤40

[0053] In the above equation 2,

[0054] RSS 125 silver , wherein G' (@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s, and G” (@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0055] H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

[0056]

[0057] Polyethylene resins are widely used in packaging films, particularly heat sealing films, due to their excellent processability, mechanical properties, and economic efficiency. These films are sealed through heating, and the physical properties and thermal stability of the sealing area are directly related to the film's reliability.

[0058] Furthermore, while LLDPE (Linear Low-Density Polyethylene) possesses excellent physical properties due to its uniform polymer structure, its narrow molecular weight distribution hinders processability. To address this, a method using PPA (Polymer Processing Aid), which contains fluorinated compounds, has been used. However, with the recent expansion of regulations on the use of PPA, the need for improved processability is growing.

[0059] Instead of using PPA, products have been released that improve processability by introducing LCB (Long Chain Branch) to LLDPE or adjusting the content and distribution of SCB (Short Chain Branch), but it is difficult to find a product that simultaneously implements an excellent balance of physical properties, especially low-temperature sealing properties and processability.

[0060] Accordingly, the present invention more reliably reflects and quantifies the microstructure that affects the rigidity and sealing properties of polyethylene, respectively, thereby designing a resin based on the rigidity factor and sealing property factor, and providing a polyethylene resin having the rigidity factor and sealing property factor above a certain standard, thereby providing a product that simultaneously improves both sealing properties and rigidity.

[0061]

[0062] Shear stress refers to shear stress and is a key factor in controlling the balance of processing fluidity and sag resistance of polyethylene for heat sealing films.

[0063] More specifically, in Equation 1 for shear stress, when the storage modulus G′ and the loss modulus G″ are large, the stress during shearing increases, which leads to increased processing resistance. Conversely, when both G′ and G″ are small and the shear rate shear stress is 0.2 MPa or less, it means high rheological flexibility and excellent processability.

[0064] According to one embodiment of the present invention, polyethylene has a shear stress of 0.20 MPa or less as shown in Table 1 compared to conventional polyethylene, and thus can provide polyethylene suitable for manufacturing a film with a balance of sealing properties and processability.

[0065] More specifically, in the polyethylene according to one embodiment of the present invention, the Shear stress value of Equation 1 may be 0.20 MPa or less, or 0.19 MPa or less, or 0.18 MPa or less. Since the lower the Shear stress value, the better the processability, the lower limit thereof is not particularly limited, but may be, for example, 0.10 MPa or more, or 0.11 MPa or more, or 0.12 MPa or more, or 0.13 MPa or more, or 0.14 MPa or more.

[0066]

[0067] At the same time, the polyethylene according to one embodiment of the present invention satisfies the following equation 2:

[0068] [Formula 2]

[0069] 30 ≤ 0.0227 * RSS 125 * 1000 - H ≤40

[0070] In the above equation 2,

[0071] RSS 125 silver , wherein G' (@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s, and G” (@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0072] H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

[0073] The above equation 2 is the rheological properties (RSS) of polyethylene 125) and optical properties (Haze), and defines the conditions for implementing high-quality films by harmonizing transparency and processing stability.

[0074] RSS is Recoverable shear strain (RSS) refers to the degree to which a melt deforms under external force (e.g., shear stress) and elastically recovers when the force is removed. In other words, it is a measure that can be used to evaluate whether a melt wants to return to its original state, and it can be considered a concept similar to melt elasticity. The higher the RSS value, the stronger the elasticity of the melt and the longer the relaxation time.

[0075] So, RSS 125 Polyethylene with a high value (where 125 means RSS measured at an angular velocity of ω = 125 rad / s) is structurally stable and has the property of withstanding stress well during processing, and can suppress sagging during film processing.

[0076] Also, the above RSS 125 Since RSS is measured under high-speed rotation conditions (ω = 125 rad / s), it can be used as an indicator to evaluate structural stability and rheological cohesion in high-speed processing environments, and can be used to determine how stably polyethylene deforms and flows in high-speed extrusion, casting, and blown film processes. Therefore, RSS 125 High-value polyethylene has improved processability even in high-speed processing environments, which can suppress sagging during film processing.

[0077] The lower the haze value, the higher the transparency. Therefore, for transparent packaging films, lower haze indicates higher marketability. However, when trying to enhance rheological properties, haze can increase conversely due to changes in the dispersion or crystal structure. The RSS of polyethylene 125The above equation 3 is satisfied only when the is sufficiently large and the haze value is suitably low, which means that polyethylene is rheologically stable even during high-speed processing, while film transparency can be secured at the same time.

[0078] In the above equation 2 (0.0227 * RSS 125 * 1000 - H) The value may be 30 or greater, or 30.30 or greater, or 31 or greater, or 31.50 or greater, or 32 or greater, or 33 or greater, or 34 or greater, but less than or equal to 40, or 39.50 or less, or 39 or less, or 38.50 or less, or 38 or less, or 37.90 or less.

[0079] Polyethylene according to one embodiment of the present invention can simultaneously secure excellent flow stability and excellent film transparency even during high-speed film processing by satisfying the above formula 2.

[0080]

[0081] In addition, polyethylene according to one embodiment of the present invention can satisfy a critical shear rate, which is a shear rate when the shear stress is 0.2 MPa, of 125 rad / s or more.

[0082] The critical shear rate, which is the shear rate when the shear stress is 0.2 MPa, is the minimum shear rate at which the material begins to be seriously affected by extensional stress under a constant shear stress (0.2 MPa in the specification of the present invention), and refers to the shear rate at which melt fracture occurs. A high critical shear rate means that the material maintains strength with little deformation under low-speed conditions, and easily flows under high-speed conditions, showing stable flow during extrusion or film forming processing. Consequently, by using polyethylene with a high critical shear rate, it is possible to simultaneously secure suppression of melt fracture and processing stability during film processing.

[0083] According to one embodiment of the present invention, polyethylene has a critical shear rate of 125 rad / s or more compared to conventional polyethylene, and thus can provide polyethylene suitable for manufacturing a film having a balanced sealing property and processability.

[0084] More specifically, the critical shear rate of the polyethylene according to one embodiment of the present invention may be 125 rad / s or more, or 130 rad / s or more, or 135 rad / s or more, or 140 rad / s or more, or 145 rad / s or more, or 150 rad / s or more, or 155 rad / s or more, or 160 rad / s or more, or 165 rad / s or more, or 170 rad / s or more, or 175 rad / s or more. The higher the critical shear rate, the better the processability, so the upper limit thereof is not particularly limited, but may be, for example, 300 rad / s or less, or 295 rad / s or less, or 290 rad / s or less, or 285 rad / s or less, or 280 rad / s or less, or 275 rad / s or less, or 270 rad / s or less, or 265 rad / s or less, or 260 rad / s or less, or 255 rad / s or less, or 250 rad / s or less, or 245 rad / s or less.

[0085]

[0086] In addition, polyethylene according to one embodiment of the present invention satisfies the following formula 3:

[0087] [Formula 3]

[0088] 70 ≤ 0.0769 * RSS 50 * 1000-H ≤ 90

[0089] In the above equation 3,

[0090] RSS 50 silver , wherein G'(@50) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s, and G”(@50) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s.

[0091] H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

[0092] The above equation 3 also shows the rheological properties of polyethylene (RSS) 50 ) and optical properties (haze), and defines the conditions for implementing high-quality films by harmonizing transparency and processing stability.

[0093] So, RSS 50 Polyethylene with a high value (here, 50 means RSS measured at an angular velocity of ω=50 rad / s) is structurally stable and has the property of withstanding stress well during processing, and can suppress the sagging phenomenon during film processing.

[0094] The lower the haze value, the higher the transparency. Therefore, for transparent packaging films, lower haze values ​​indicate higher marketability. However, when attempting to enhance rheological properties, haze can increase conversely due to changes in the dispersion or crystal structure.

[0095] In the above equation 3 (0.0769 * RSS 50 *1000 - H) The value may be 70 or greater, or 71.50 or greater, or 72 or greater, or 72.40 or greater, or 73 or greater, or 73.40 or greater, and 90 or less, or 89 or less, or 88 or less, or 87 or less, or 86 or less, or 85 or less, or 84 or less, or 83 or less, or 82 or less, or 81 or less, or 80 or less.

[0096] According to one embodiment of the present invention, polyethylene satisfies the above formula 3, thereby enabling the production of a film having a balance of rheological stability and excellent transparency.

[0097]

[0098] For reference, in the above formulas 2 and 3, the haze was measured according to ASTM D1003 on a film formed into a single-layer film having a thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, using a blown film extruder (die diameter 120 mm, die gap 2.0 mm, BUR 2.5, Dual air-ring system) of a composition containing 95 wt% or more, or 96 wt% or more, or 97 wt% or more, or 98 wt% or more, or 99 wt% or more of the polyethylene of the present invention based on the total composition.

[0099]

[0100] In addition, polyethylene according to one embodiment of the present invention has a density of 0.900 to 0.925 g / cm as measured according to ASTM D 1505 standard. 3 am.

[0101] If the density of polyethylene is too low, it is difficult to ensure stability in the slurry polymerization process. In addition, there is a trade-off relationship between density and drop impact strength, and density and low-temperature sealing properties. If the density of polyethylene is too high, it is difficult to down-gauge during film production due to the decrease in drop impact strength and low-temperature sealing properties. More specifically, the polyethylene according to the present invention has a density of 0.900 g / cm. 3 or 0.901 g / cm 3 or 0.902 g / cm 3 or 0.903 g / cm 3 or 0.904 g / cm 3 or 0.905 g / cm 3 or 0.906 g / cm 3 or 0.907 g / cm 3 or 0.908 g / cm 3 or 0.909 g / cm 3 or 0.910 g / cm 3 or 0.911 g / cm 3 or 0.912 g / cm 3 or 0.913 g / cm 3 or 0.914 g / cm 3 or 0.915 g / cm 3 Ideally, 0.925 g / cm 3 or less, or 0.924 g / cm 3 or less, or 0.923 g / cm 3 or less, or 0.922 g / cm 3 or less, or 0.921 g / cm 3 or less, or 0.920 g / cm 3 or less, or 0.919 g / cm 3 or less, or 0.918 g / cm 3 It could be as follows:

[0102]

[0103] According to one embodiment of the present invention, the polyethylene has a significantly lower sealing initiation temperature than conventional polyethylene having a similar density, and thus can exhibit excellent low-temperature sealing properties and improved stiffness. As a product having a balanced sealing property and stiffness, when a low-density product is used to improve the existing low-temperature sealing properties, the waste of resources that are not used due to blocking problems that occur during actual application for packaging in roll form after lamination can be prevented, and additives such as anti-blocking agents used to lower the coefficient of friction can be reduced.

[0104]

[0105] In addition, the polyethylene according to one embodiment of the present invention has a molecular weight distribution (MWD, Mw / Mn) of 2.0 to 5.0.

[0106] If the molecular weight distribution is narrow, less than 2.0, the mechanical properties such as toughness are excellent, but there is a risk that the molding processability may deteriorate. If the molecular weight distribution exceeds 5.0, the molding processability is excellent, but there is a risk that the mechanical properties may deteriorate. More specifically, the polyethylene has a molecular weight distribution (MWD) of 2.0 or more, or 2.1 or more, or 2.2 or more, or 2.3 or more, or 2.4 or more, or 2.5 or more, or 2.6 or more, or 2.7 or more, or 2.8 or more, or 2.9 or more, or 3.0 or more, or 3.1 or more, or 3.2 or more, or 3.3 or more, or 3.4 or more, or 3.5 or more, or 3.6 or more, or 3.65 or more, or 3.7 or more, or 3.8 or more, and 5.0 or less, or 4.9 or less, or 4.8 or less, or 4.7 or less, or 4.6 or less, or 4.5 or less, or 4.4 or less, or 4.3 or less, or 4.25 or less, or 4.2 or less, or 4.15 or less, or 4.1 or less, or It may be 4.0 or less, or 3.9 or less. The polyethylene according to the present invention can exhibit well-balanced improved molding processability and mechanical properties by satisfying the above-mentioned molecular weight distribution conditions.

[0107]

[0108] Meanwhile, in the present invention, the weight average molecular weight (Mw) and number average molecular weight (Mn) of polyethylene were measured using gel permeation chromatography (GPC), and then the molecular weight distribution was calculated as the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn). Here, the weight average molecular weight (Mw) and number average molecular weight (Mn) are polystyrene-converted molecular weights analyzed by GPC.

[0109] Specifically, a sample of polyethylene was analyzed using a Polymer Char GPC-IR using a Polymer Laboratories PLgel MIX-B 300 mm length column. ®The evaluation was performed using a device. The evaluation temperature was 160℃, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was measured at a rate of 1 mL / min. The polyethylene sample was prepared at a concentration of 16 mg / 8 mL and then supplied in an amount of 200 μL. The values ​​of Mw and Mn were measured using a calibration curve formed using polystyrene standards. The molecular weights of the polystyrene standards were 9 types: 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000.

[0110]

[0111] In addition, the polyethylene according to one embodiment of the present invention has a melt index (MI) measured under a temperature of 190°C and a load of 2.16 kg according to ASTM D1238 standard. 2.16) is 0.5 to 5.0 g / 10 min. More specifically, 0.5 g / 10 min or more, or 0.6 g / 10 min or more, or 0.7 g / 10 min or more, or 0.8 g / 10 min or more, or 0.9 g / 10 min or more, or 1.0 g / min or more, or 1.1 g / 10 min or more, or 1.2 g / min or more, or 1.3 g / min or more, or 1.4 g / min or more, or 1.5 g / min or more, and 5.0 g / 10 min or less, or 4.9 g / 10 min or less, or 4.8 g / 10 min or less, or 4.7 g / 10 min or less, or 4.6 g / 10 min or less, or 4.5 g / 10 min or less, or 4.4 g / 10 min or less, or 4.3 g / 10 min or less, or 4.2 g / 10 min or less, or 4.1 g / 10 min or less, or 4.0 g / 10min or less, or 3.9 g / 10min or less, or 3.8 g / 10min or less, or 3.7 g / 10min or less, or 3.6 g / 10min or less, or 3.5 g / 10min or less, or 3.4 g / 10min or less, or 3.3 g / 10min or less, or 3.2 g / 10min or less, or 3.1 g / 10min or less, or 3.0 g / 10min or less, or 2.9 g / 10min or less, or 2.8 g / 10min or less, or 2.7 g / 10min or less, or 2.6 g / 10min or less, or 2.5 g / 10min or less, or 2.4 g / 10min or less, or 2.3 g / 10min or less, or 2.2 g / 10min or less, or 2.1 g / 10min or less, or It may be 2.0 g / 10 min or less, or 1.9 g / 10 min or less, or 1.8 g / 10 min or less, or 1.7 g / 10 min or less, or 1.6 g / 10 min or less.

[0112]

[0113] In addition to the aforementioned crystal distribution characteristics and molecular weight distribution characteristics, the polyethylene according to the present invention can exhibit improved molding processability and mechanical properties as well as excellent sealing properties and drop impact strength characteristics by satisfying the conditions of low density and optimal range molecular weight distribution and melting index.

[0114]

[0115] In addition, the polyethylene according to one embodiment of the present invention may be a copolymer of ethylene and alpha-olefin, specifically including an alpha-olefin repeating unit derived from an alpha-olefin monomer together with an ethylene repeating unit.

[0116] The above alpha-olefin monomer may specifically be an alpha-olefin monomer having 3 to 20 carbon atoms. Specific examples thereof include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, etc., and more preferably, it may be 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene. Preferably, the polyethylene according to one embodiment of the present invention may be a type of copolymer of ethylene and 1-hexene, rather than a mixture with another polyethylene.

[0117] Polyethylene having the above properties can be produced by a production method including, for example, a step of polymerizing an ethylene monomer and an alpha-olefin monomer in the presence of a hybrid supported metallocene catalyst comprising a first transition metal compound represented by the following chemical formula 1; and a second transition metal compound represented by the following chemical formula 2. The above production method is merely an example for implementing the polyethylene according to the present invention, and the polyethylene of the present invention is not limited to the above production method.

[0118] [Chemical Formula 1]

[0119]

[0120] In the above chemical formula 1,

[0121] M1 is a group 4 transition metal,

[0122] X 11 and X 12 are each independently, C 1-20 Alkyl or halogen,

[0123] A1 is carbon, silicon, or germanium,

[0124] Q 11 and Q 12 are each independently hydrogen, halogen, C 1-20 Alkyl, or C 2-20 It is an alkoxyalkyl,

[0125] R 11 Inland R 15 are each independently hydrogen or C 1-20 It is alkyl,

[0126] [Chemical Formula 2]

[0127]

[0128] In the above chemical formula 2,

[0129] M2 is a group 4 transition metal,

[0130] X 21 and X 22 are each independently, C 1-20 Alkyl or halogen,

[0131] R 21 Inland R 25 are each independently, C 1-20 It is alkyl,

[0132] R 26 is hydrogen or C 1-20 It is alkyl,

[0133] R 27 Silver hydrogen, C 1-20 Alkyl, C 2-20 Alkoxy, or C 2-20 It is an alkoxyalkyl.

[0134]

[0135] In the present invention, the substituents of the chemical formula are described more specifically as follows.

[0136] The halogen can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0137] C 1-20 The alkyl of may be straight-chain, branched-chain or cyclic alkyl. Specifically, the C 1-20 The alkyl may be a straight chain alkyl having 1 to 20 carbon atoms; a straight chain alkyl having 1 to 10 carbon atoms; a straight chain alkyl having 1 to 5 carbon atoms; a branched chain or cyclic alkyl having 3 to 20 carbon atoms; a branched chain or cyclic alkyl having 3 to 15 carbon atoms; or a branched chain or cyclic alkyl having 3 to 10 carbon atoms. More specifically, the alkyl having 1 to 20 carbon atoms may be a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an iso-pentyl group, or a cyclohexyl group.

[0138] C 2-20 The alkenyl of may be a straight-chain, branched-chain or cyclic alkenyl. Specifically, the C 2-20 The alkenyl may be a straight chain alkenyl having 2 to 20 carbon atoms, a straight chain alkenyl having 2 to 10 carbon atoms, a straight chain alkenyl having 2 to 5 carbon atoms, a branched chain alkenyl having 3 to 20 carbon atoms, a branched chain alkenyl having 3 to 15 carbon atoms, a branched chain alkenyl having 3 to 10 carbon atoms, a cyclic alkenyl having 5 to 20 carbon atoms or a cyclic alkenyl having 5 to 10 carbon atoms. More specifically, C 2-20 The alkenyl may be ethenyl, propenyl, butenyl, pentenyl or cyclohexenyl.

[0139] C 1-20 The alkoxy of may be a straight-chain, branched-chain or cyclic alkoxy group. Specifically, the C 1-20The alkoxy may be a straight chain alkoxy group having 1 to 20 carbon atoms; a straight chain alkoxy group having 1 to 10 carbon atoms; a straight chain alkoxy group having 1 to 5 carbon atoms; a branched chain or cyclic alkoxy group having 3 to 20 carbon atoms; a branched chain or cyclic alkoxy group having 3 to 15 carbon atoms; or a branched chain or cyclic alkoxy group having 3 to 10 carbon atoms. More specifically, the alkoxy group having 1 to 20 carbon atoms may be a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a tert-butoxy group, an n-pentoxy group, an iso-pentoxy group, a neo-pentoxy group, or a cyclohexene group.

[0140] C 2-20 Alkoxyalkyl of -R y -OR z Alkyl (-R) with a structure containing y ) is one or more hydrogens of alkoxy (-OR z ) may be a substituent substituted with. Specifically, the alkoxyalkyl having C2 to C20 carbon atoms may be a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhectyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, or a tert-butoxyhexyl group.

[0141] Also, group 4 transition metals can include titanium, zirconium, and hafnium.

[0142]

[0143] The hybrid supported metallocene catalyst used in the production of polyethylene according to the present invention is a hybrid catalyst comprising a first transition metal compound with high molecular weight and high polymerizability, and a second transition metal compound with low molecular weight and low polymerizability.

[0144] Specifically, the first transition metal compound represented by the above chemical formula 1 contributes to producing a high molecular weight copolymer having a high SCB content, and the second transition metal compound represented by the above chemical formula 2 contributes to producing a low molecular weight copolymer having a low SCB content. Accordingly, the hybrid supported metallocene catalyst can exhibit high copolymerizability in the high molecular weight region of polyethylene due to the first transition metal compound, while exhibiting low copolymerizability in the low molecular weight region of polyethylene due to the action of the second transition metal compound. As a result, the polyethylene produced using the hybrid supported metallocene catalyst can easily produce polyethylene that satisfies the above-described physical property requirements through tie-molecule formation due to strong low crystallinity expression in the high molecular weight region.

[0145] Specifically, in the hybrid supported metallocene catalyst, the first transition metal compound represented by the chemical formula 1 contributes to the production of a high molecular weight copolymer and exhibits a relatively high comonomer incorporation rate compared to the second transition metal compound.

[0146] Specifically, in the above chemical formula 1, M1 may be zirconium (Zr) or titanium (Ti).

[0147] Also, X 11 and X 12 are each independently halogen, and more specifically, may be chloro.

[0148] Also, in the above chemical formula 1, A1 is silicon, and Q 11 and Q 12 are each independently hydrogen, halogen, C 1-20 Alkyl, or C 2-20 Alkoxyalkyl, Q 11 and Q 12 Either one of C 2-20 It may be a tether group of an alkoxyalkyl. More specifically, Q 11 and Q 12 One of them is C2-20 One is alkoxyalkyl, and the other is C 1-20 It could be an alkyl.

[0149] As a bridging group connecting two ligands, Q 11 and Q 12 Either one of C 2-20 When the tether group of the alkoxyalkyl is included, the atomic size becomes larger and the available angle increases compared to the carbon bridge in the conventional metallocene compound, so that the monomer can easily approach during the polymerization reaction, thereby exhibiting excellent catalytic activity. In addition, the leaching of the catalyst precursor is prevented during the polymerization reaction, and as a result, fouling due to the reaction of the leached catalyst precursor and the cocatalyst can be prevented. Such an effect is described in the above Q 11 and Q 12 Either of them is -(CH2)nR b (Above R b is C 1-6 Alkoxy group, more specifically C 1-6 Straight chain alkoxy group or C 3-6 C, such as a branched alkoxy group, more specifically a tert-butoxy group 3-6 Branched alkoxy, n is an integer from 2 to 10, or from 3 to 9, and the remainder is C 1-4 It can be further increased in the case of alkyl. More specifically, Q 11 and Q 12 One of them may be tert-butoxyhexyl and the other may be methyl.

[0150] Also, in the above chemical formula 1, R 11 Inland R 14 are each independently, C 1-10 Alkyl, more specifically C 1-4 Alkyl, more specifically methyl. In this way, the cyclopentadienyl ligand in formula 1 is R 11 Inland R 14By being substituted, it can exhibit better catalytic activity due to the inductive effect that can supply sufficient electrons.

[0151] Also, in the above chemical formula 1, R 15 is C 1-6 It can be alkyl, more specifically C 1-4 Straight chain alkyl or C 3-6 It may be a branched alkyl, more specifically tert-butyl.

[0152] Specific examples of the first transition metal compound represented by the above chemical formula 1 include compounds having the following structures, but the present invention is not limited thereto.

[0153]

[0154]

[0155] The first transition metal compound represented by the above chemical formula 1 can be synthesized by applying known reactions, and a more detailed synthesis method can be found in the examples.

[0156] Meanwhile, in the hybrid supported metallocene catalyst, the second transition metal compound represented by the chemical formula 2 has a non-crosslinked structure of a hydrogenated indene ligand, specifically, a 4,5,6,7-tetrahydro-1-indene ligand and a cyclopentadiene ligand. Accordingly, the electronic / steric environment around the transition metal can be easily controlled, and as a result, the chemical structure, molecular weight distribution, and mechanical properties of the synthesized polyethylene can be easily controlled.

[0157] Specifically, in the above chemical formula 2, M2 may be zirconium (Zr). When the second transition metal compound includes Zr as a central metal, it has more orbitals capable of accepting electrons compared to when it includes other Group 14 elements such as Hf, and thus can easily bind to the monomer with higher affinity, resulting in a superior catalytic activity improvement effect.

[0158] Also, X 21 and X 22 can each independently be a halogen, and more specifically, a chloro.

[0159] Also, in the above chemical formula 2, R 21 Inland R 25 are each independently, C 1-10 Alkyl, more specifically C 1-4 Alkyl, more specifically methyl. Thus, the cyclopentadienyl ligand in formula 2 is R 21 Inland R 25 By being substituted, it can exhibit better catalytic activity due to the inductive effect that can supply sufficient electrons. In addition, by being used in combination with the first transition metal compound represented by the above chemical formula 1, the distribution of the comonomer in the polyethylene produced is appropriately controlled, so that polyethylene satisfying the above-described physical property requirements can be easily produced.

[0160] In addition, the second transition metal compound includes a hydrogenated indene ligand, i.e., a 4,5,6,7-tetrahydro-1-indene ligand, thereby exhibiting superior hydrogen reactivity compared to a case in which an indene group is included in the prior art. Accordingly, the amount of hydrogen input and the amount of wax generated during the polymerization reaction can be reduced, and as a result, process stability can be improved. In addition, by being used in combination with the first transition metal compound represented by the above chemical formula 1, the distribution of comonomers in the final polyethylene produced is concentrated toward a high molecular weight, and as a result, the impact strength properties of the polyethylene can be significantly improved.

[0161] In addition, the 1st and 3rd positions of the above 4,5,6,7-tetrahydro-1-indene ligand are unsubstituted, or R 26 and R 27 Each of which can be replaced by R 26 is specifically hydrogen or C 1-20 Alkyl, R 27 Silver hydrogen, C 1-20 Alkyl, C 2-20 Alkoxy, or C 2-20 It may be an alkoxyalkyl. More specifically, the R 26 is hydrogen or C 1-6 Alkyl, R 27 Silver hydrogen, C 1-6 Alkyl, or -(CH2) n -R b (Above R b is C 1-6 Alkoxy group, more specifically C 1-6 Straight chain alkoxy group or C 3-6 It may be an alkoxyalkyl group having a branched alkoxy group, and n is an integer from 2 to 10. In addition, the above -(CH2) n -R b In R b is C 3-6 C, such as a branched alkoxy group, more specifically a tert-butoxy group 3-6 Branched alkoxy, and n may be an integer from 3 to 9. More specifically, the R 26is hydrogen, or methyl, and R 27 may be hydrogen, methyl, ethyl, or tert-butoxyhexyl.

[0162] Specific examples of the second transition metal compound represented by the above chemical formula 2 include compounds having the following structures, but the present invention is not limited thereto.

[0163] .

[0164] The second transition metal compound represented by the above chemical formula 2 can be synthesized by applying known reactions, and a more detailed synthesis method can be found in the examples.

[0165] In addition, the hybrid supported metallocene catalyst can increase catalytic activity and more easily implement the properties of the polymer produced by controlling the molar ratio of the first and second transition metal compounds.

[0166] For example, the hybrid supported metallocene catalyst may include the first and second transition metal compounds in a molar ratio of 1:1 to 10:1. When the above-described mixing ratio conditions are satisfied, the catalytic activity is excellently maintained, while the high and low copolymerizabilities of the polyethylene produced from the hybrid supported catalyst are optimized, thereby further improving the sealing properties, drop impact strength properties, rigidity, and molding processability. More specifically, the molar ratio of the first and second transition metal compounds may be 2:1 to 8:1, or 2:1 to 5:1.

[0167] Additionally, the hybrid supported metallocene catalyst may include a cocatalyst.

[0168] Hybrid supported metallocene catalysts exhibit improved process stability along with high catalytic activity when they include a cocatalyst.

[0169] Specifically, the cocatalyst may include at least one compound represented by the following chemical formula 3.

[0170] [Chemical Formula 3]

[0171] -[Al(R 41 )-O]a-

[0172] In the above chemical formula 3,

[0173] R 41 is a halogen; or C substituted or unsubstituted with a halogen 1-20 It is hydrocarbyl;

[0174] a is an integer greater than or equal to 2.

[0175] Meanwhile, in the present specification, a hydrocarbyl group is a monovalent functional group in the form of removing a hydrogen atom from a hydrocarbon, and may include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aralkenyl group, an aralkynyl group, an alkylaryl group, an alkenylaryl group, and an alkynylaryl group. In addition, the hydrocarbyl group having 1 to 20 carbon atoms may be a hydrocarbyl group having 1 to 15 carbon atoms or 1 to 10 carbon atoms. Specifically, the hydrocarbyl group having 1 to 20 carbon atoms is a straight-chain, branched-chain, or cyclic alkyl group such as a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, or a cyclohexyl group; Or it may be an aryl group such as a phenyl group, a naphthyl group, or anthracenyl group.

[0176] Examples of compounds represented by the above chemical formula 3 include alkylaluminoxane compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one of these or a mixture of two or more thereof may be used. Among the above compounds, the cocatalyst may be more specifically methylaluminoxane.

[0177] The above alkylaluminoxane cocatalyst can further enhance catalytic activity by including a metal element that stabilizes the first and second transition metal compounds and acts as a Lewis acid to form a bond through a Lewis acid-base interaction with a functional group introduced to a bridge group of the first transition metal compound.

[0178] In addition, the amount of the cocatalyst used can be appropriately adjusted depending on the properties or effects of the desired catalyst and polyethylene. For example, when silica is used as the carrier described below, the cocatalyst can be supported in an amount of 100 g or more, 1000 g or more, or 2000 g or more, and 6000 g or less, or 5500 g or less, or 5400 g or less, based on the weight of the carrier, for example, 1,000 g of silica.

[0179] In addition, the hybrid supported metallocene catalyst may include a carrier. When the hybrid supported metallocene catalyst includes a carrier, the first and second transition metal compounds are used in the form of a supported catalyst supported on the carrier.

[0180] As the carrier, a carrier having a highly reactive hydroxyl group, silanol group, or siloxane group on the surface can be used. For this purpose, a carrier whose surface has been modified by calcination or whose surface has had moisture removed by drying can be used. For example, silica such as silica manufactured by calcining silica gel, or silica dried at high temperature, silica-alumina, and silica-magnesia can be used, and these can typically contain oxides, carbonates, sulfates, and nitrate components such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0181] When used in a supported catalyst state, the particle shape and bulk density of the polymer produced are excellent, and it can be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes. In addition, among various supports, the silica support is supported by chemical bonding of the functional group of the transition metal compound, so that almost no catalyst is liberated from the surface of the support during the ethylene polymerization process, and as a result, fouling caused by adhesion of the reactor wall or polymer particles to each other can be minimized when producing polyethylene by slurry or gas phase polymerization.

[0182] The above-mentioned carrier may have an average particle diameter (D50) of 20 to 40 μm. When the above-mentioned particle size is present, the transition metal compound can be supported with superior efficiency, and as a result, the catalytic activity can be enhanced. More specifically, the carrier may have an average particle diameter of 20 μm or more, or 25 μm or more, and 40 μm or less, or 30 μm or less.

[0183] Meanwhile, in the present invention, the average particle diameter (D50) of the carrier refers to the particle diameter at the 50% point of the cumulative distribution of the number of particles according to particle size (particle diameter). The D50 can be measured using a laser diffraction method. Specifically, the target carrier is dispersed in a dispersion medium such as deionized water, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern according to the particle size is measured to calculate the particle size distribution. The particle size at the point where it becomes 50% of the cumulative distribution of the number of particles according to the particle diameter in the measuring device is calculated, and this is taken as the average particle size.

[0184] In addition, when supported on the carrier, the first and second transition metal compounds may be supported in an amount of, for example, 1 mmol or more, 1.5 mmol or more, or 2 mmol or more, and 100 mmol or less, or 50 mmol or less, or 30 mmol or less, or 10 mmol or less, or 5 mmol or less, based on 1,000 g of the silica carrier. When supported in the above content range, it may exhibit appropriate supported catalytic activity, which may be advantageous in terms of maintaining the activity of the catalyst and economic efficiency.

[0185] The hybrid supported metallocene catalyst having the above-described configuration can be produced by a production method including a step of supporting a promoter compound on a support, and a step of supporting the first and second transition metal compounds on the support. In this case, the supporting order of the promoter and the first and second transition metal compounds can be changed as needed, and the supporting order of the first and second transition metal compounds can also be changed as needed. The first and second transition metal compounds can be supported simultaneously. Considering the effect of the supported catalyst having a structure determined according to the supporting order, among these, supporting the promoter on the support and then sequentially supporting the first and second transition metal compounds can enable the produced supported catalyst to realize high catalytic activity and better process stability in the process of producing polyethylene.

[0186] Meanwhile, in the polymerization reaction, specific examples of alpha-olefin monomers include, as described above, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, etc., and two or more of these may be used. More specifically, the alpha-olefin monomer may be 1-hexene.

[0187] The amount of the alpha-olefin monomer added may be determined depending on the properties of the polyethylene to be manufactured. For example, considering the properties of the polyethylene to be implemented in the present invention, the alpha-olefin monomer may be added in an amount of 4 to 30 wt%, more specifically, 4 wt% or more, or 8 wt% or more, or 10 wt% or more, or 12 wt% or more, and 30 wt% or less, or 25 wt% or less, or 20 wt% or less, based on the total weight of monomers including ethylene and the alpha-olefin monomer.

[0188] In addition, the above polymerization reaction is performed under the condition of hydrogen input.

[0189] Specifically, hydrogen may be introduced in an amount of 10 to 50 ppm, more specifically 10 ppm or more, or 15 ppm or more, or 20 ppm or more, or 25 ppm or more, and 50 ppm or less, or 45 ppm or less, or 40 ppm or less, or 38 ppm or less, or 35 ppm or less, based on the total weight of monomers including ethylene monomers and alpha-olefin monomers. When introduced in the above range, it is easier to implement the physical properties of the polyethylene described above. When the polymerization reaction is performed under conditions without introducing hydrogen, the melt index (MI) of the polyethylene produced may be significantly lowered.

[0190] Additionally, the above polymerization reaction can be carried out as a slurry polymerization reaction.

[0191] In the case of solution polymerization, since the catalyst is activated by a high temperature and high pressure reaction, catalyst decomposition and chain transfer are promoted, and the resulting resin composition has a narrow molecular weight distribution (MWD) and a low high molecular weight tail content. Accordingly, the resin composition manufactured by solution polymerization exhibits deteriorated moldability when manufacturing a film. However, in the case of the slurry polymerization process of the present invention, since polymerization is performed at a relatively low temperature, it is possible to secure a molecular structure containing a wide MWD and a large amount of high molecular weight tail, which is required for a polyethylene resin composition for manufacturing a transparent film. As a result, excellent moldability can be exhibited.

[0192] In the above slurry polymerization reaction, it can be performed using a single continuous slurry polymerization reactor or a loop slurry reactor.

[0193] In addition, during the above slurry polymerization reaction, the hybrid supported catalyst can be dissolved or diluted and injected in an aliphatic hydrocarbon solvent having 4 to 12 carbon atoms, such as isobutane, pentane, hexane, heptane, nonane, decane, and isomers thereof, an aromatic hydrocarbon solvent such as toluene and benzene, a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene, etc. It is preferable to use the solvent used here after removing a small amount of water or air, etc. that act as catalyst poisons, by treating it with a small amount of alkyl aluminum, and it is also possible to carry out the reaction using an additional cocatalyst.

[0194] In addition, the polymerization reaction may be carried out at a temperature of 40°C or higher, or 60°C or higher, or 80°C or higher, and 110°C or lower, or 100°C or lower, or 90°C or lower. In addition, when the pressure conditions during the polymerization reaction are further controlled, the polymerization reaction may be carried out under a pressure of 5 bar or higher, or 10 bar or higher, or 20 bar or higher, or 30 bar or higher, and 50 bar or lower, or 45 bar or lower, or 40 bar or lower. When polymerization is carried out under such temperature and pressure, the desired physical properties of polyethylene can be more easily realized.

[0195] The polyethylene produced by the above-described production method has the crystal distribution characteristics, molecular weight distribution characteristics, rheological characteristics, and processing characteristics described above. Accordingly, the polyethylene can exhibit excellent low-temperature sealing characteristics and hot-tack characteristics, and can also exhibit well-balanced improved molding processability along with excellent drop impact strength characteristics and rigidity. As a result, downgauging is possible when producing a film using the polyethylene, and the polyethylene is advantageous for D4R applications. In addition, the polyethylene can be usefully used in multi-purpose films such as food, agricultural, and general industrial films, or stretch films, and can be particularly used in the sealant layer of All-PE.

[0196] Accordingly, the present invention provides a resin composition comprising the polyethylene, specifically a composition for forming a film.

[0197] In addition, the present invention provides a film manufactured using the polyethylene or the resin composition.

[0198] The above film can be manufactured according to a conventional film manufacturing method, except that the above-mentioned polyethylene is used. For example, the film can be manufactured according to an inflation method in which a film-forming composition is manufactured by mixing only the above-mentioned polyethylene or optionally by mixing additives such as antioxidants and processing aids, and then extruding the film into a film using an extruder.

[0199] More specifically, the resin composition containing the polyethylene may be applied for a sealant layer, and co-extruded with a composition for forming another film layer, or extruded with a blown film extruder or a cast film extruder, or a film may be separately manufactured with the resin composition containing the polyethylene using extrusion coating on a substrate such as paper, and then the manufactured film may be laminated with another film. However, the present invention is not limited thereto, and any known manufacturing method may be applied to manufacture various films.

[0200]

[0201] The above film exhibits excellent low-temperature sealing properties, sealing stability and process reliability by including the above polyethylene.

[0202]

[0203] Specifically, when the film is a single-layer film having a film thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, the sealing initiation temperature (SIT) measured according to ASTM F 1921 is 85.0°C or less. More specifically, the sealing initiation temperature is 85.0°C or less, or 84.5°C or less, or 84.0°C or less, or 83.5°C or less, or 83.0°C or less, or 82.5°C or less, or 82.0°C or less, or 81.5°C or less, or 80.0°C or less, or 79.5°C or less, or 79.0°C or less, or 78.5°C or less, or 78.0°C or less, or 77.5°C or less, or 77.0°C or less, or 76.5°C or less, or 76.0°C or less, or 75.5°C or less, or 75.0°C or less, or 74.5°C or less, or 74.0°C or less. The lower the sealing initiation temperature, the better the low-temperature sealing property and sealing strength, so there is no particular limitation on the lower limit, but for example, it may be 60.0°C or higher, or 61.0°C or higher, or 62.0°C or higher, or 63.0°C or higher, or 64.0°C or higher, or 65.0°C or higher, or 66.0°C or higher, or 67.0°C or higher, or 68.0°C or higher, or 69.0°C or higher, or 70.0°C or higher, or 71.0°C or higher, or 72.0°C or higher, or 73.0°C or higher.

[0204] For reference, the above sealing initiation temperature is the temperature at which the heat seal strength reaches 2 N / 25.4 mm when the sealing strength is measured according to ASTM F 1921 (conditions of sealing time 0.5 sec, sealing pressure 0.3 MPa, delay time 30.0 sec, tensile speed 200 mm / sec, J&B 5000) when the film thickness is 45 to 55 µm, or 48 to 52 µm, more specifically, 50 µm, in a single-layer film.

[0205]

[0206] In addition, the polyethylene film can exhibit improved drop impact strength properties in addition to the sealing properties.

[0207] Specifically, when the film is a single-layer film having a film thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, the drop impact strength measured according to ASTM D 1709 [Method A] is 900 gf or more, or 950 gf or more, or 1,000 gf or more, or 1,150 gf or more. The drop impact strength is not particularly limited in its upper limit as it is better the higher it is, but for example, it may be 3,000 gf or less, or 2,900 gf or less, or 2,800 gf or less, or 2,700 gf or less, or 2,600 gf or less, or 2,500 gf or less, or 2,400 gf or less, or 2,300 gf or less, or 2,200 gf or less, or 2,100 gf or less, or 2,000 gf or less, or 1,900 gf or less, or 1,800 gf or less, or 1,700 gf or less.

[0208]

[0209] In addition, the polyethylene film can exhibit improved transparency in addition to the sealing properties.

[0210] Specifically, when the film is a single-layer film having a film thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, the haze measured according to ASTM D1003 is 23% or less, or 22% or less, or 21% or less, or 20% or less, or 19% or less, or 18% or less, or 17% or less, or 16% or less, or 15% or less, or 14% or less, or 13% or less. The lower limit of the haze is not particularly limited because the lower the value, the better, but for example, it may be 5% or more, or 6% or more, or 7% or more, or 8% or more.

[0211]

[0212] In addition, when the film is a single-layer film having a film thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, the 1% secant modulus in the MD direction of the film, measured according to ASTM D882 using a Universal Testing Machine (UTM), is 1,500 kg / cm. 2 or more than 1,600 kg / cm 2 or more than 1,700 kg / cm 2 or more than 1,800 kg / cm 2 And the 1% secant modulus in the TD direction is 1,800 kg / cm 2 or more than 1,900 kg / cm 2 or more than 2,000 kg / cm 2 or more than 2,100 kg / cm 2 That's all.

[0213] The secant modulus is defined in ASTM D882 and represents the stiffness of a film. The secant modulus is related to density, and the higher the density, the higher the secant modulus and stiffness. In addition, the higher the secant modulus, the better the openability, visibility, and coefficient of friction (COF). Accordingly, the upper limit of the secant modulus is not particularly limited, but as an example, the 1% secant modulus in the MD and TD directions of the film is 3,000 kg / cm each. 2 or less, or 2,900 kg / cm 2 or less, or 2,800 kg / cm 2 or less, or 2,700 kg / cm 2 or less, or 2,600 kg / cm 2 or less, or 2,500 kg / cm 2 or less, or 2,400 kg / cm 2 It could be as follows:

[0214]

[0215] For reference, the above sealing initiation temperature, haze, drop impact strength, and secant modulus were measured for a film formed into a single-layer film having a thickness of 45 to 55 μm, or 48 to 52 μm, more specifically 50 μm, using a blown film extruder (die diameter 120 mm, die gap 2.0 mm, BUR 2.5, Dual air-ring system) from a composition containing 95 wt% or more, or 96 wt% or more, or 97 wt% or more, or 98 wt% or more, or 99 wt% or more, of the polyethylene of the present invention based on the total composition.

[0216]

[0217] Hereinafter, preferred examples are presented to aid understanding of the present invention. However, the following examples are provided solely to facilitate understanding of the present invention and are not intended to limit the scope of the present invention.

[0218] Meanwhile, in this specification, room temperature means 23±2℃.

[0219]

[0220] <Preparation of Transition Metal Compounds>

[0221] Synthesis Example 1

[0222]

[0223] Preparation of ligands

[0224] Tetramethylcyclopentadiene (TMCP, 1 equiv) was dissolved in THF (0.3 M), and n-BuLi (1.05 eq) was slowly added dropwise at -25°C, followed by stirring at room temperature for 3 hours. t-BuOHexSiMeCl2 (1.00 eq) was added to the resulting reaction mixture at -10°C, followed by stirring at room temperature overnight. The solvent was completely vacuum-dried, and tBuNH2 (10 eq) was added and stirred at room temperature overnight. Afterwards, the mixture was worked up with water and dried to obtain the ligand.

[0225]

[0226] Preparation of transition metal compounds

[0227] The above-mentioned ligand was dissolved in toluene (0.3 M), n-BuLi (2.05 eq) was added at -25°C, and stirred at room temperature for 3 hours. In a glove box, TiCl4(THF)2 (titanium tetrachloride tetrahydrofuran adduct, 1 eq) was prepared in another flask, added to the ligand-Li flask using a cannula at -25°C, and washed and added using toluene (1.0 M).

[0228] Upon completion of the reaction, the solvent was vacuum-dried, DCM was re-introduced, LiCl was removed through a filter, and the filtrate was vacuum-dried to obtain a liquid transition metal compound (Cat 1).

[0229] 1 H NMR (500 MHz, CDCl3) δ 3.34 (t, 2H), 2.24 (d, J = 1.7 Hz, 6H), 2.13 (d, J = 3.2 Hz, 6H), 1.57 - 1.45 (m, 6H), 1.42 (s, 9H), 1.32 - 1.22 (m, 4H), 1.18 (s, 9H), 0.67 (s, 3H).

[0230]

[0231] Synthesis Example 2-1

[0232] (Cat 2-1)

[0233] Indene (1 eq) was dissolved in THF (0.3 M), and n-BuLi (1.05 eq) was slowly added dropwise at -25°C, and the mixture was stirred at room temperature for 3 hours. Then, CH3-I (1.05 eq) was added at -10°C, and the mixture was stirred overnight at room temperature, worked up with water, and dried to obtain 3-MethylIndene. 3-MethylIndene (1 eq) thus synthesized was dissolved in THF (0.3 M), and n-BuLi (1.05 eq) was slowly added dropwise at -25°C, and the mixture was stirred at room temperature for 3 hours. Then, CH3-I (1.05 eq) was added at -10°C, and the mixture was stirred overnight at room temperature, worked up with water, and dried to obtain 1,3-dimethyl-Indene.

[0234]

[0235] Preparation of transition metal compounds

[0236] The above-mentioned ligand was dissolved in Ether (0.3 M), n-BuLi (1.05 eq) was added at -25°C, and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (Pentamethylcyclopentadienylzirconium trichloride) (1 eq) was prepared in another flask, added to the ligand-Li flask using a cannula at -25°C, and washed and added using Ether (1.0 M).

[0237] Upon completion of the reaction, the solvent was vacuum-dried, DCM was reintroduced, LiCl was removed through a filter, the filtrate was vacuum-dried, and slurry was formed using hexane. The resulting solid was then filtered and vacuum-dried to obtain a solid metallocene compound intermediate.

[0238]

[0239] In a glove box, the above metallocene compound intermediate was placed in a mini parr, and 5 mol% of Pd / C (10 wt%) was added. A magnetic bar was inserted here and moved outside the glove box using a closing system. DCM (0.5 M) was added to the parr, and H2 gas (10 barg) was added. After repeating the vent-charge cycle three times, the mixture was placed in a 40°C oil bath and stirred. When the pressure of the parr decreased below 5 barg, the previous charging process was repeated, and the reaction was continued until there was no more consumption of H2 gas. Upon completion of the reaction, the remaining H2 gas was vented and replaced with Ar gas. After cooling to room temperature, the mixture was filtered using a cannula, and the filtrate was vacuum-dried. The dried filtrate was slurried using hexane, and this was filtered to obtain a solid transition metal compound (Cat 2-1).

[0240] 1 H NMR (500 MHz, CDCl3) δ 5.60 (s, 1H), 2.90 (dt, J = 16.4, 6.3 Hz, 2H), 2.32 (dt, J = 16.3, 6.0 Hz, 2H), 2.04 (s, 15H), 1.79 - 1.66 (m, 2H), 1.67 (s, 6H), 1.64 - 1.54 (m, 2H).

[0241]

[0242] Synthesis Example 2-2

[0243] (Cat 2-2)

[0244] Indene (1 eq) was dissolved in THF (0.3 M), and n-BuLi (1.05 eq) was slowly added dropwise at -25°C, followed by stirring at room temperature for 3 hours. Afterwards, CH3-I (1.05 eq) was added at -10°C, and stirred overnight at room temperature, worked up with water, and dried to obtain 3-MethylIndene. 3-MethylIndene (1 eq) thus synthesized was dissolved in THF (0.3 M), and n-BuLi (1.05 eq) was slowly added dropwise at -25°C, followed by stirring at room temperature for 3 hours. Afterwards, tert-butoxyhexyl-I (1.05 eq) was added at -10°C, stirred overnight at room temperature, worked up using water, and dried to obtain 1-methyl-3-(tert-butoxyhexyl)-Indene.

[0245]

[0246] Preparation of transition metal compounds

[0247] The above-mentioned ligand was dissolved in Ether (0.3 M), n-BuLi (1.05 eq) was added at -25°C, and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (Pentamethylcyclopentadienylzirconium trichloride) (1 eq) was prepared in another flask, added to the ligand-Li flask using a cannula at -25°C, and washed and added using Ether (1.0 M).

[0248] Upon completion of the reaction, the solvent was vacuum-dried, DCM was reintroduced, LiCl was removed through a filter, the filtrate was vacuum-dried, and slurry was formed using hexane. The resulting solid was then filtered and vacuum-dried to obtain a solid metallocene compound intermediate.

[0249]

[0250] In a glove box, the above metallocene compound intermediate was placed in a mini parr, and 5 mol% of Pd / C (10 wt%) was added. A magnetic bar was inserted here and moved outside the glove box using a closing system. DCM (0.5 M) was added to this parr, and H2 gas (10 barg) was added. After repeating the vent-charge cycle three times, the mixture was placed in a 40°C oil bath and stirred. When the pressure of the parr decreased below 5 barg, the previous charging process was repeated, and the reaction was continued until there was no more consumption of H2 gas. When the reaction was complete, the remaining H2 gas was vented and replaced with Ar gas. After cooling to room temperature, the mixture was filtered using a cannula, and the filtrate was vacuum-dried. The dried filtrate was slurried using hexane, and this was filtered to obtain a solid transition metal compound (Cat 2-2).

[0251] 1 H NMR (500 MHz, CDCl3) δ 5.57 (s, 1H), 3.31 (t, J = 6.7 Hz, 2H), 2.95 - 2.85 (m, 2H), 2.37 - 2.28 (m, 2H), 2.18 - 2.03 (m, 2H), 2.02 (s, 15H), 1.96 - 1.88 (m, 1H), 1.82 - 1.77 (m, 1H), 1.75 (s, 3H), 1.71 - 1.55 (m, 3H), 1.53 - 1.36 (m, 4H), 1.36 - 1.20 (m, 3H), 1.18 (s, 9H).

[0252]

[0253] Synthesis Example 2-3

[0254] (Cat 2-3)

[0255] Preparation of ligands

[0256] Indene (1 eq) was dissolved in THF (0.3 M), n-BuLi (1.05 eq) was slowly added dropwise at -25°C, and the mixture was stirred at room temperature for 3 hours. Then, CH3-CH2-I (1.05 eq) was added at -10°C, stirred overnight at room temperature, worked up with water, and dried to obtain 3-Ethyl-Indene.

[0257]

[0258] Preparation of transition metal compounds

[0259] The above-mentioned ligand was dissolved in Ether (0.3 M), n-BuLi (1.05 eq) was added at -25°C, and stirred at room temperature for 3 hours. In a glove box, PMCpZrCl3 (Pentamethylcyclopentadienylzirconium trichloride) (1 eq) was prepared in another flask, added to the ligand-Li flask using a cannula at -25°C, and washed and added using Ether (1.0 M).

[0260] Upon completion of the reaction, the solvent was vacuum-dried, DCM was reintroduced, LiCl was removed through a filter, the filtrate was vacuum-dried, and slurry was formed using hexane. The resulting solid was then filtered and vacuum-dried to obtain a solid metallocene compound intermediate.

[0261] In a glove box, the above metallocene compound intermediate was placed in a mini parr, and 5 mol% of Pd / C (10 wt%) was added. A magnetic bar was inserted here and moved outside the glove box using a closing system. DCM (0.5 M) was added to this parr, and H2 gas (10 barg) was added. After repeating the vent-charge cycle three times, the mixture was placed in a 40°C oil bath and stirred. When the pressure of the parr decreased below 5 barg, the previous charging process was repeated, and the reaction was continued until there was no more consumption of H2 gas. When the reaction was complete, the remaining H2 gas was vented and replaced with Ar gas. After cooling to room temperature, the mixture was filtered using a cannula, and the filtrate was vacuum-dried. The dried filtrate was slurried using hexane, and this was filtered to obtain a solid transition metal compound (Cat 2-3).

[0262] 1 H NMR (500 MHz, CDCl3) δ 5.60 (d, J = 2.7 Hz, 2H), 5.20 (d, J = 2.7 Hz, 2H), 2.83 - 2.71 (m, 2H), 2.49 - 2.36 (m, 3H), 2.21 (dd, J = 15.1, 7.6 Hz, 1H), 2.01 (s, 15H), 1.98 - 1.80 (m, 2H), 1.66 - 1.51 (m, 2H), 1.03 (t, J = 7.6 Hz, 3H).

[0263]

[0264] <Catalyst Manufacturing>

[0265] Manufacturing Example 1

[0266] 2.0 kg of toluene and 1000 g of silica (SP2410, Grace Davision) were charged into a 20L SUS high-pressure reactor, and the reactor temperature was raised to 40°C while stirring. 5.4 kg of methylaluminoxane (10 wt% in toluene, Albemarle) was charged into the reactor, the temperature was raised to 70°C, and the reactor was stirred at about 200 rpm for about 12 hours. Thereafter, the temperature of the reactor was lowered to 40°C, and stirring was stopped. The reaction product was allowed to stand for about 10 minutes and then decantated. 2.0 kg of toluene was again charged into the reaction product, stirred for about 10 minutes, stopped, and the reactor was allowed to stand for about 30 minutes before decantation.

[0267] 2.0 kg of toluene was charged into the reactor, and then the compound (Cat 1) (50 mmol) prepared in Synthesis Example 1 as the first transition metal compound, the compound (Cat 2-2) (10 mmol) prepared in Synthesis Example 2-2 as the second transition metal compound, and 1000 mL of toluene were charged. The temperature of the reactor was raised to 85°C, and stirring was performed for approximately 90 minutes.

[0268] Afterwards, the temperature of the reactor was lowered to room temperature, stirring was stopped, the reaction product was allowed to stand for about 30 minutes, and the reaction product was decantated. Next, 3 kg of hexane was added to the reactor, and the hexane slurry solution was transferred to a 20 L filter dryer, the solution was filtered, and dried under reduced pressure at 50 °C for about 4 hours to obtain 1.5 kg of a hybrid metallocene catalyst.

[0269] (Cat 1) (Cat 2-2)

[0270]

[0271] Manufacturing Examples 2 to 4

[0272] As described in Table 1 below, a hybrid supported metallocene catalyst was prepared in the same manner as in Preparation Example 1, except that the types of the first and second transition metal compounds were changed.

[0273]

[0274] Catalyst 1 Transition metal compound 2 Transition metal compound Mixing molar ratio Preparation example 1 Cat 1, 50 mmol Cat 2-2, 10 mmol 5:1 Preparation example 2 Cat 1, 25 mmol Cat 2-2, 10 mmol 2.5:1 Preparation example 3 Cat 1, 20 mmol Cat 2-3, 10 mmol 2:1 Preparation example 4 Cat 1, 55 mmol Cat 2-1, 10 mmol 5.5:1

[0275] <Manufacturing of polyethylene>

[0276] Examples 1-1 to 4-1

[0277] A 140 L continuous polymerizer capable of performing an isobutene slurry loop process with a polymerization reactor and operating at a reaction velocity of approximately 7 m / s was prepared. The reactants required for polyethylene polymerization were continuously fed into the reactor as described in Table 2. The catalysts used in each polymerization reaction were those prepared in the manufacturing examples described in Table 1, and the catalysts were mixed with the isobutene slurry and fed. Furthermore, the polymerization reaction was performed at a pressure of approximately 40 bar and a temperature of approximately 85°C, and other key conditions for the polymerization reaction are shown in Table 2 below.

[0278]

[0279] Comparative Example 1-1

[0280] HP1018, a copolymer of ethylene and 1-hexene manufactured by LG Chem, was used.

[0281]

[0282] Comparative Example 2-1

[0283] XM3108, a copolymer of ethylene and 1-hexene manufactured by LG Chem, was used.

[0284]

[0285] Comparative Example 3-1

[0286] XM3137, a copolymer of ethylene and 1-hexene manufactured by LG Chem, was used.

[0287]

[0288] Comparative Example 4-1

[0289] LF100A, a copolymer of ethylene and 1-octene manufactured by LG Chem, was used.

[0290]

[0291] Catalytic ethylene input (kg / hr)1-hexene input 1 (wt%) hydrogen input 2 (ppm)Activity (kgPE / kgSiO2·hr)Example 1-1 Manufacturing Example 1 2618385.2Example 2-1 Manufacturing Example 2 2617395.0Example 3-1 Manufacturing Example 3 26.5 20406.0Example 4-1 Manufacturing Example 427.5 17387.0

[0292] In Table 2 above, the activity (Activity, kgPE / kgSiO2·hr) was calculated as the ratio of the polymer weight (kgPE) produced per the catalyst weight (kg) used per unit time (hr).

[0293] Also, the 1-hexene input amount (wt%) is calculated as a percentage of the 1-hexene input amount based on the total weight of monomers containing ethylene and 1-hexene, and the hydrogen input amount (ppm) is calculated as a percentage of the total weight of monomers containing ethylene and 1-hexene.

[0294]

[0295] Film Manufacturing

[0296] A film was manufactured using the polyethylene manufactured in the examples and comparative examples using the following method.

[0297]

[0298] Examples 1-2 to 4-2, Comparative Examples 1-2 to 4-2

[0299] Based on the total weight of the polyethylene manufactured in the above examples or comparative examples, 1200 ppm of an antioxidant (Songnox 1076 (Songwon): Songnox 1680 (Songwon) = 1:2 in weight ratio) was added and mixed, and a twin screw extruder (Twin screw extruder; TEK 30 MHS, manufactured by SMPLATECH CO., diameter 32 pi, L / D = 40) was used to extrude at an extrusion temperature of 190°C at an extrusion rate of 35 kg / hr, thereby manufacturing a composition for forming a pellet-shaped film weighing about 18 kg.

[0300] A film was manufactured by inflation molding the film-forming composition manufactured above under the following film extrusion conditions.

[0301]

[0302] <Film forming conditions>

[0303] Single Screw Extruder (Eugene Engineering Single Screw Extruder, Blown Film M / C, 50 pi, L / D=32)

[0304] Melting temperature (or extrusion temperature): 185℃

[0305] Die Gap: 2.0mm

[0306] Die diameter: 120mm

[0307] Blown-Up Ratio: 2.5

[0308] Maintain Frost Line Height at 200~250mm

[0309] Sample extrusion rate: 300~500g / min

[0310] Cooling: Uses dual air-ring

[0311] Film thickness: 50㎛

[0312]

[0313] Experimental Example 1

[0314] The physical properties of the polyethylene manufactured in the above examples and comparative examples were measured as follows, and the results are shown in Tables 3 and 5 below.

[0315]

[0316] (1) Melt Index (MI) 2.16 ): Measured according to ASTM D1238 (Condition E, 190 ℃, 2.16 kg load).

[0317]

[0318] (2) Density: Measured according to ASTM D1505 standard.

[0319]

[0320] (3) Molecular weight distribution (MWD)

[0321] For the polyethylene according to the above examples and comparative examples, the weight average molecular weight (Mw, g / mol) and number average molecular weight (Mn, g / mol) were measured through gel permeation chromatography (GPC) analysis, and the molecular weight distribution (MWD, Mw / Mn) was obtained by dividing the weight average molecular weight measured above by the number average molecular weight.

[0322] Specifically, a Polymer Char GPC-IR® instrument was used as a gel permeation chromatography (GPC) device, and a Polymer Laboratories PLgel MIX-B 300 mm column was used. The measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL / min. Each sample of polyethylene manufactured in the examples and comparative examples was pretreated by dissolving in 1,2,4-trichlorobenzene containing 0.003% BHT at 160°C for 2 hours using a GPC analysis instrument (Polymer Char GPC-IR®), and then prepared at a concentration of 16 mg / 8 mL and supplied in an amount of 200 μL. The values ​​of Mw and Mn were calculated using a calibration curve formed using polystyrene standard specimens. The weight average molecular weights of the polystyrene standard specimens were 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, which were 9 types.

[0323]

[0324] (4) Rheological properties

[0325] The storage modulus (G') and loss modulus (G") of the polyethylene of the examples and comparative examples were measured in frequency sweep mode using a rotational rheometer (ARES-G2 Rheometer, manufactured by TA Instruments), respectively.

[0326] Specifically, the test chamber of the rheometer was purged with nitrogen to minimize polyethylene degradation, and the rheometer was preheated to an initial temperature of 190°C. After sample loading and oven thermal equilibration, the sample prepared above was placed between the parallel plates of the rheometer (plate diameter: 25.4 mm, gap between plates: 2 mm) and pressed to a thickness of 2.0 mm. Vacuum shear flow was applied at a strain of 5% over each frequency range of 0.05 to 500 rad / s under a nitrogen atmosphere. At this time, the strain was kept within 5% to satisfy the linear viscoelasticity condition. A total of 8 minutes elapsed between the time the sample was inserted between the plates and the start of the frequency sweep (0.03-100 rad / s), and the measurements were performed at 190°C. Meanwhile, a new sample was used at each temperature, and nitrogen (N2) was circulated within the test chamber for each measurement.

[0327] Through the above measurements, the storage modulus (G') and loss modulus (G") for the angular velocity (ω) were obtained.

[0328]

[0329] From the results obtained from the above rheological property measurement results, Shear stress, RSS according to Equation 1 below 50 , RSS 125 were obtained respectively.

[0330] [Formula 1]

[0331] Shear stress = [{G'(@125)} 2 + {G”(@125)} 2 ] 1 / 2

[0332] In the above equation 1,

[0333] G'(@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0334] G”(@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0335] RSS 50 silver , wherein G'(@50) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s, and G”(@50) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s.

[0336] RSS 125 silver , where G' (@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s, and G” (@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s.

[0337]

[0338] In addition, the storage elastic modulus and loss elastic modulus measured above were calculated as shear stress according to shear rate, and a graph with the x-axis as shear rate and the y-axis as shear stress is shown in Fig. 1.

[0339] Referring to Figure 1, the value of the shear rate of the X-axis when the y-axis is 0.2 MPa (200000 Pa) is the Critical shear rate.

[0340]

[0341] Experimental Example 2

[0342] The physical properties of the films manufactured in the examples and comparative examples were measured as follows, and the results are shown in Tables 4 and 6 below.

[0343]

[0344] (1) Dart drop impact strength

[0345] For the films of the examples and comparative examples manufactured above, the drop impact strength was measured according to the ASTM D1709 [Method A] standard, and the average value was taken by measuring at least 5 sets (20 times / 1 set) per film sample.

[0346]

[0347] (2) Sealing initiation temperature (SIT)

[0348] According to ASTM F 1921, when the seal strength was measured at each temperature at 5℃ intervals between 60℃ and 130℃ using a J&B Hot tack tester (Hot tacker 5000) under the conditions of a sealing time of 0.5 seconds, a sealing pressure of 0.3 MPa, a delay time of 30.0 seconds, and a tensile speed of 200 mm / sec, the temperature at which the heat seal strength reached 2 N / 25.4 mm was defined as the seal initiation temperature (SIT).

[0349] In the unit N / 25.4mm, “25.4mm” refers to the width of the film sample for which sealing is measured.

[0350]

[0351] (3) Haze

[0352] According to ASTM D1003, the degree of light refracted (%) was measured when light was shone on each example and comparative example film using a Haze meter (HM-150). Haze was calculated as Td (refracted light) / Tt (transmitted light) × 100 (%). Measurements were performed at least 10 times per film sample, and the average value was taken.

[0353]

[0354] (4) Secant modulus

[0355] For the films of the above examples and comparative examples, the 1% secant modulus in the machine direction (MD) and transverse direction (TD) of the films was measured according to ASTM D882 using an Instron UTM (Universal Testing Machine).

[0356]

[0357] (5) Melt fracture

[0358] For the polyethylene according to the above examples and comparative examples, melt fracture of the extrudate was confirmed using a capillary rheometer (R315-H9) at a piston size of 12 mm, an orifice size of L / D=20 / 2, 190°C, and a shear rate of 300 1 / s. In order to determine the surface shape of the extrudate, photographs were taken using a stereoscopic microscope (Olympus SZX16) at a magnification of 20 times.

[0359] The images captured for each example and comparative example are shown in Fig. 2.

[0360]

[0361] Example 1-1 Example 2-1 Example 3-1 Example 4-1 MI (g / 10 min) 1.387 1.33 1.52 1.31 Density (g / cm3) 0.9169 0.918 0.9177 0.918 4 Comonomer 1-hexene 1-hexene 1-hexene 1-hexene MWD 3.76 3.56 4.2 4.26 G'(ω) (@50 rad / s)(MPa) 0.05 107 0.05 766 0.05 98 3 0.06 768 G"(ω) (@50 rad / s)(MPa) 0.08 0 32 0.08 67 3 0.08 63 4 0.09 4 5 2 G'(ω) (@125 rad / s)(MPa)0.106060.117780.120350.13388G”(ω) (@125 rad / s)(MPa)0.127740.134550.129900.14038critical shear rate (@0.2MPa)177154159134Shear stress (@125 rad / s) (MPa)0.170.180.180.19RSS (@50 rad / s)1.05821.15111.24781.3322RSS (@125 rad / s)1.82312.0552.34712.5165Haze (%)9.78.822.921.9Equation 2 (0.0227 * RSS 125 *1000 - H) Calculated value 31.6837.8430.3835.23 Equation 3 (0.0769 * RSS) 50 *1000 - H) Calculated value 71.6779.7373.0680.54

[0362]

[0363] Example 1-2 Example 2-2 Example 3-2 Example 4-2 SIT (℃) 80.58 1767 9.5 Haze (%) 9.7 8.8 22.9 21.9 Drop impact strength (gf) 97 2 100 5 1369 1379 Melt fracture occurrence XXXX 1% Secant, MD (kg / cm 2 )16511544178616821% Secant, TD (kg / cm 2 )2025213421132050

[0364]

[0365] Comparative Example 1-1 Comparative Example 2-1 Comparative Example 3-1 Comparative Example 4-1 MI (g / 10 min) 111.26 0.996 Density (g / cm3) 0.918 0.918 0.926 7 0.905 Comonomer 1-hexene 1-hexene 1-hexene 1-octene MWD 2.43 3.42.89 2.41 G'(ω) (@50 rad / s)(MPa) 0.088 37 0.085 14 0.076 9 4 0.05 30 4 G"(ω) (@50 rad / s)(MPa) 0.115 30 0.107 26 0.114 36 0.074 0 8 G'(ω) (@125 rad / s)(MPa)0.169010.159420.155220.10323G”(ω) (@125 rad / s)(MPa)0.173480.1551940.179050.11681critical shear rate (@0.2MPa)6210092180Shear stress (@125 rad / s) (MPa)0.240.220.240.15RSS (@50 rad / s)1.53291.65201.17791.332RSS (@125 rad / s)2.65113.02662.00962.1005Haze (%)710.123.85.9Equation 2 (0.0227 * RSS 125 *1000 - H) Calculated value 53.1858.6021.8241.78 Equation 3 (0.0769 * RSS) 50 *1000 - H) Calculated value 110.88116.9266.7796.53

[0366]

[0367] Comparative Example 1-2Comparative Example 2-2Comparative Example 3-2Comparative Example 4-2SIT (℃)1029511269Haze (%)710.123.85.9Drop impact strength (gf)120020003002300Melt fracture occurrenceOOOX1%Secant, MD (kg / cm 2 )2000188029426391% Secant, TD (kg / cm 2 )230023213266687

[0368] Referring to Tables 3 to 6, the polyethylene of the examples of the present invention satisfies the Shear stress of 0.20 MPa or less and the RSS 125 As the relationship between the shear stress and haze satisfies the specified range of Equation 2, it can be confirmed that excellent flow stability and film transparency can be secured simultaneously even during high-speed film processing. In contrast, the polyethylene of the comparative examples has a shear stress or RSS 125 It can be confirmed that the relationship between the haze and the melt does not satisfy the range, and thus melt fracture occurs during extrusion, or the stiffness measured by the secant elastic modulus is low.

[0369] In addition, referring to Fig. 2, in the case of comparative examples 1, 2, and 3, it was confirmed that the surface of the extruded product had an unsmooth fracture shape.

Claims

1. The shear stress expressed by the following equation 1 is 0.2 MPa or less, Satisfying the following equation 2, Polyethylene: [Formula 1] Shear stress = [{G’(@125)} 2 + {G”(@125)} 2 ] 1 / 2 In the above equation 1, G'(@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s. G”(@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s. [Formula 2] 30 ≤ 0.0227 * RSS 125 * 1000 - H ≤40 In the above equation 2, RSS 125 silver , wherein G' (@125) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s, and G” (@125) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=125 rad / s. H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

2. In paragraph 1, Polyethylene having a critical shear rate, which is the shear rate when the shear stress is 0.2 MPa, of 125 rad / s or more.

3. In paragraph 1, Polyethylene satisfying the following equation 3: [Formula 3] 70 ≤ 0.0769 * RSS 50 * 1000-H ≤ 90 In the above equation 3, RSS 50 silver , wherein G'(@50) is the storage modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s, and G”(@50) is the loss modulus (unit: MPa) measured using a rotational rheometer (ARES-G2) in frequency sweep mode, at a temperature of 190℃, and an angular velocity of ω=50 rad / s. H is a haze value (unit: %) measured according to ASTM D1003 when a film containing polyethylene is manufactured with a thickness of 45 to 55㎛.

4. In paragraph 1, A density of 0.900 to 0.925 g / cm as measured according to ASTM D1505. 3 person, Polyethylene.

5. In paragraph 1, Polyethylene having a molecular weight distribution (MWD) of 2.0 to 5.

0.

6. In paragraph 1, The above polyethylene is a polyethylene having a melting index of 0.5 to 5.0 g / 10 min, measured at a temperature of 190°C and a load of 2.16 kg according to ASTM D1238.

7. In paragraph 1, The above polyethylene is a type of copolymer of ethylene and alpha olefin.

8. In paragraph 7, The above alpha olefin is 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene, Polyethylene.

9. A film containing polyethylene according to paragraph 1.

10. In paragraph 9, When the film thickness is 45 to 55 ㎛, the sealing initiation temperature (SIT) measured according to ASTM F 1921 is 85.0℃ or less. film.

11. In paragraph 10, When the film thickness is 45 to 55 ㎛, the drop impact strength measured according to ASTM D 1709 is 900 gf or more. film.

12. In paragraph 9, When the film thickness is 45 to 55 ㎛, the 1% secant modulus in the MD direction measured according to ASTM D882 is 1,500 kg / cm 2 And the 1% secant modulus in the TD direction is 1,800 kg / cm 2 Lee Sang-in, film.

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