Polyethylene composition, and biaxially-oriented film comprising same

Abstract

The present invention relates to a polyethylene composition and a biaxially-oriented film comprising same.

Description

Polyethylene composition and biaxially oriented film comprising the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0039384, filed March 21, 2024, and U.S. Patent Application No. 19 / 057,074, filed February 19, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a polyethylene composition suitable for producing a biaxially oriented film that maintains excellent mechanical properties and has high shrinkage resistance, printability and transparency.

[0004] In addition, the present invention relates to a biaxially oriented film that maintains excellent mechanical properties and has high shrinkage resistance, printability, and transparency.

[0005] Linear low-density polyethylene (LLDPE) film and / or high-density polyethylene (HDPE) film, which are thin films manufactured from linear low-density polyethylene (LLDPE) and / or high-density polyethylene (HDPE), are used in a variety of applications. Specifically, they are widely used as sealing layers in packaging films used in packaging applications such as merchandise bags, grocery bags, food and specialty packaging, and industrial liners.

[0006] Packaging film composed of a printing layer and a sealing layer enables packaging of products while maintaining their shape, and can perform the function of protecting products from external stimuli when displayed.

[0007] Among various packaging films, biaxially oriented films with excellent mechanical properties, productivity, and printability are widely used for packaging purposes.

[0008] More specifically, commercially available packaging films typically use BOPP (biaxially oriented polypropylene), BOPET (biaxially oriented polyethylene terephthalate), or BOPA (biaxially oriented polyamide) for the printing layer, and LLDPE film or HDPE film for the sealing layer. However, this form of using composite materials has had the problem of making the packaging film impossible to recycle due to the type of film used in the printing layer.

[0009] To address this, research and development is underway to manufacture a single-material packaging film that replaces the printed layer film with biaxially-oriented polyethylene (BOPE) film.

[0010] However, commercial polyethylene (PE) resins used in the production of biaxially-oriented polyethylene (BOPE) films do not have sufficient stretching stability, and phenomena such as breakage and melting occur during stretching, making it difficult to apply the biaxial stretching process.

[0011] To ensure stretchability, polyethylene compositions containing resins with low density and high melt index are being developed. However, these compositions exhibit low rigidity, shrinkage, and impact resistance, making them unsuitable for use in biaxially oriented films.

[0012] Accordingly, there is a need for a polyethylene composition for biaxial stretching that exhibits stretching stability during biaxial stretching and good film mechanical properties.

[0013] The present invention provides a polyethylene composition capable of producing a biaxially oriented film having excellent mechanical properties, productivity and stretching stability, and high shrinkage resistance, printability and transparency.

[0014] In addition, the present invention provides a biaxially oriented film that maintains excellent mechanical properties, productivity and stretching stability, and has high shrinkage resistance, printability and transparency.

[0015] The present invention relates to a polyethylene composition comprising at least one ethylene-alphaolefin copolymer,

[0016] The above polyethylene composition provides a polyethylene composition in which a Successive Self-nucleation and Annealing (SSA) thermogram, which indicates the relationship between heat flux and temperature, satisfies the following equation 1.

[0017] [Formula 1]

[0018] 0.16 ≤ B / A ≤ 0.4

[0019] In the above equation 1,

[0020] A represents the area for the entire temperature range in the above SSA thermal analysis diagram,

[0021] B refers to the area for the temperature range of 128 ℃ or higher in the above SSA thermal analysis diagram.

[0022] The present invention also provides a biaxially oriented film comprising a polyethylene composition according to the present invention.

[0023] The polyethylene composition of the present invention has excellent stretching stability such as a maximum stretching ratio and can produce a biaxially stretched film having excellent mechanical properties.

[0024] The biaxially stretched film of the present invention has excellent stretching stability such as a maximum stretching ratio and excellent mechanical properties.

[0025] FIG. 1 is a diagram showing an SSA thermogram of a polyethylene composition according to one embodiment of the present invention and the meaning of the area of ​​a temperature region of 128°C or higher.

[0026] Figures 2 and 3 are SSA thermograms derived from polyethylene compositions of Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention.

[0027] Unless otherwise defined herein, all technical and scientific terms used herein are used solely to describe exemplary embodiments and are not intended to limit the present invention. Furthermore, singular expressions include plural expressions unless the context clearly dictates otherwise.

[0028] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify 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.

[0029] 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 scope of the invention.

[0030] The technical terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. Furthermore, the singular forms "a," "an," and "the" as used herein also include the plural forms, unless the context clearly dictates otherwise.

[0031] The terms "about," "substantially," and the like, as used throughout this specification, are used to mean at or near the numerical value when manufacturing and material tolerances inherent in the meanings referred to are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of the present disclosure.

[0032] Additionally, in this specification, (co)polymer means both a homopolymer and a copolymer.

[0033] Unless otherwise defined herein, “copolymerization” may mean block copolymerization, random copolymerization, graft copolymerization or alternating copolymerization, and “copolymer” may mean block copolymer, random copolymer, graft copolymer or alternating copolymer.

[0034] In this specification, "part by weight" means a relative concept that expresses the weight of a substance as a ratio based on the weight of the remaining 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.

[0035] Meanwhile, "% by weight" refers to an absolute concept that expresses the weight of a certain substance as a percentage of the total weight. In the mixture in the example above, the contents of substance A, substance B, and substance C are 50% by weight, 20% by weight, and 30% by weight, respectively, out of 100% of the total weight of the mixture.

[0036] In this specification, 'a to b' means a or more and b or less.

[0037] In this specification, 'a, b, c or d' means a, or b, or c, or d.

[0038] Hereinafter, a polyethylene composition according to a specific embodiment of the invention and a biaxially oriented film comprising the same will be described in more detail.

[0039] Ⅰ. Polyethylene composition

[0040] The polyethylene composition of the present invention is characterized in that the area ratio of the SSA thermogram derived by SSA (Successive Self-nucleation and Annealing) analysis is adjusted to satisfy the above equation 1.

[0041] When a polyethylene composition is rapidly cooled and then slowly annealed at a specific temperature, stable lamellae crystallize, while unstable lamellae remain molten. In this case, lamellae refer to a plate-like structure formed by folded polymer chains that align long polymer chains in a regular manner within a narrow space. Lamellar structures are also called layered structures.

[0042] SSA analysis is an analysis method that measures the changes that occur when stable lamellae crystallize and unstable lamellae remain in a molten state during annealing, repeating the phenomenon step by step, using a differential scanning calorimeter (DSC).

[0043] Additionally, the SSA thermogram refers to the expression of the SSA analysis results in a graph in which the x-axis represents temperature and the y-axis represents heat flux.

[0044] More specifically, the SSA analysis and SSA thermogram are derived through the following steps.

[0045] Step 1) Stepwise annealing

[0046] ① (Heating) A polyolefin composition at room temperature (approximately 25°C) is heated to a set heating temperature until the temperature is reached. At this time, the heating temperature is changed as described below during the process of repeating the process. Specifically, the first heating temperature is set to 175°C to 185°C and heated for 15 to 25 minutes so that the temperature of the polyolefin composition reaches the first heating temperature.

[0047] ② (Quick cooling) Next, the polyolefin composition at the first heating temperature is cooled at a rate of 15°C / min to 25°C / min (first cooling rate) for 1.5 to 2 minutes (first cooling time), until the temperature of the polyolefin composition reaches 140°C to 150°C (quenching temperature). Thereafter, the temperature is maintained for 15 to 25 minutes.

[0048] ③ (Cooling) Additionally, the polyolefin composition that has reached the rapid cooling temperature is cooled at a rate of 5°C / min to 10°C / min (second cooling rate) for 10 to 25 minutes (second cooling time), so that the temperature of the polyolefin composition is cooled to 25°C to 35°C. Thereafter, the temperature is maintained for 1 to 10 minutes.

[0049] ④ Next, the processes of heating, rapid cooling, and cooling are repeated for the polyolefin composition described above, except that the n+1 heating temperature is set to be 3 to 7 ℃ lower than the nth heating temperature. Specifically, heating, rapid cooling, and cooling are repeated for the polyolefin composition until the n+1 heating temperature is set to 55 to 70 ℃. In addition, in this process, the heating temperature is the n+1 heating temperature, and the first cooling rate and the first cooling time of the rapid cooling step and the second cooling rate and the second cooling time of the cooling step are the same.

[0050] ⑤ When the n+1 heating temperature is set to 55 ℃ to 70 ℃, the n+2 heating temperature is lowered by 7 ℃ to 13 ℃ from the n+1 heating temperature, and heating, rapid cooling, and cooling are repeated for the polyolefin composition. That is, the degree of lowering the heating temperature is changed. Specifically, after the n+1 heating temperature is set to 55 ℃ to 70 ℃, heating, rapid cooling, and cooling are repeated for the polyolefin composition until the n+2 heating temperature becomes 35 ℃ to 45 ℃. In this process, the heating temperature is the n+2 heating temperature, and the first cooling rate and the first cooling time of the rapid cooling step and the second cooling rate and the second cooling time of the cooling step are the same.

[0051] Step 2) Deriving the SSA thermogram

[0052] ① In the final annealing step, the temperature of the polyolefin composition is cooled to 25°C to 35°C, maintained for 1 to 10 minutes, and then cooled to -55°C to -45°C.

[0053] ② The polyolefin composition cooled to -55 ℃ to -45 ℃ is heated to 175 ℃ to 185 ℃ at a rate (heating rate) of 7 ℃ / min to 13 ℃ / min, and an SSA thermogram as shown in Fig. 1 is derived.

[0054] The SSA analysis process includes both steps 1 and 2, and the changes in steps 1 and 2 can be measured using a differential scanning calorimeter (DSC). In addition, the temperature and time ranges described in steps 1 and 2 are ranges set in consideration of the allowable error.

[0055] Step 3) Find the area ratio (C)

[0056] In the above SSA thermogram, the temperature range where no lamellar peak appears is set as the baseline, and the area for the entire temperature range and the area for the temperature range above 128°C are calculated.

[0057] Next, using the following calculation formula 1, C, which is the ratio of the area for the temperature range of 128°C or higher to the area for the entire temperature range, is calculated.

[0058] [Calculation Formula 1]

[0059] C = B / A

[0060] In the above calculation formula 1,

[0061] A represents the area for the entire temperature range in the above SSA thermal analysis diagram,

[0062] B refers to the area for the temperature range of 128 ℃ or higher in the above SSA thermal analysis diagram.

[0063] The polyolefin composition according to the present invention satisfies the following formula 1.

[0064] [Formula 1]

[0065] 0.16 ≤ B / A ≤ 0.4

[0066] In the above equation 1,

[0067] A represents the area for the entire temperature range in the above SSA thermal analysis diagram,

[0068] B refers to the area for the temperature range of 128 ℃ or higher in the above SSA thermal analysis diagram.

[0069] The above A and B represent areas calculated by setting the temperature region where the lamellar peak does not appear as a baseline in the SSA thermogram derived through SSA analysis. That is, as can be seen in Fig. 1, which shows an example of an SSA thermogram, the ratio of the area for the temperature region of 128°C or higher to the area for the entire temperature region satisfies Equation 1, which is a feature of the present invention.

[0070] The above 128°C is the temperature that includes the last peak observed in the SSA analysis results, and the temperature range above 128°C indicates the ratio of the longest ethylene sequence. The lamellar peak refers to the peak shown in the SSA thermogram.

[0071] The polyolefin composition of the present invention is a semi-crystalline polymer composition, which may include a crystalline portion and an amorphous portion. Specifically, the crystalline portion may be formed by the folding of polymer chains including ethylene repeating units to form bundles, thereby forming crystalline blocks (or segments) in a lamellar shape. Typically, in order to provide a polyethylene composition for producing a biaxially oriented film that maintains excellent mechanical properties, productivity, and stretching stability, and has high shrinkage resistance, printability, and transparency, the crystal structure of the polyethylene must be appropriately controlled.

[0072] The polyethylene crystal structure is influenced by the length distribution of the ethylene repeating units that form the lamellar crystals. That is, the physical properties of the polyethylene film can vary significantly depending on the ratio of polymer chains with long ethylene repeating units to polymer chains with short ethylene repeating units among the polymer chains that form the lamellar crystals.

[0073] In the polyethylene crystal structure, the ethylene repeating unit in the polymer chain that forms the lamellar crystal is called the ethylene sequence. The polyolefin composition contains ethylene repeating units of various lengths, i.e., ethylene sequences of various lengths. In addition, the length distribution of the ethylene sequences within the polyethylene composition, i.e., the ratio of long ethylene sequences to short ethylene sequences, can affect the crystal structure of the polyethylene.

[0074] The length distribution of ethylene sequences can be controlled by controlling molecular structures such as polyethylene polydispersity (PDI) and short chain branches (SCB) within the polyethylene composition.

[0075] The inventors of the present invention have discovered that when the ratio of long ethylene sequences exceeding a certain length is within an appropriate range, a polyethylene composition having improved stretching stability and physical properties can be obtained during biaxial stretching. That is, when the ratio of long ethylene sequences exceeding a certain length is excessive, the polyethylene has a low melting crystal content at the stretching temperature, resulting in low flexibility, making high-magnification stretching difficult.

[0076] In addition, it was found that if the ratio of long ethylene sequences exceeding a certain length is too low, the ratio of thick crystals is low, making it difficult to maintain the crystal shape, resulting in poor processability.

[0077] The longer length of the ethylene sequence described above may mean that the number of ethylene repeating units forming lamellar crystals is greater, and thus, the thickness of the lamellar crystals is also greater. In other words, a polyethylene composition having a long ethylene sequence can form thick lamellae. In other words, since the lamellar thickness can be said to be proportional to the length of the ethylene sequence, the length distribution of the ethylene sequence can be predicted through the distribution of the lamellar thickness of the polyethylene composition.

[0078] As described above, since the lamellar thickness distribution can be confirmed through SSA analysis, the length distribution of the ethylene sequence can also be predicted when performing SSA analysis.

[0079] The present inventors have found that when a polyethylene composition has an area in a temperature range of 128°C or higher as measured by SSA thermography, which has a specific range value compared to the area in the entire temperature range, i.e., when it satisfies Equation 1 in the SSA thermography, a biaxially oriented film having excellent mechanical properties, productivity, and stretching stability, and high shrinkage resistance, printability, and transparency can be obtained.

[0080] The fact that the polyethylene composition satisfies Equation 1 means that a certain level of thick lamellae is included in the polyethylene composition, which can be said to mean that an appropriate level of ethylene sequences having a length greater than a certain length are included.

[0081] In the SSA thermogram, the area in the temperature range of 128 ℃ or higher means that there are many ethylene sequences that can form thick lamellae, which means that the length of the ethylene sequence is long. In other words, the temperature range of 128 ℃ or higher means the proportion of long ethylene sequences. In other words, the proportion of the area in the temperature range of 128 ℃ or higher to the total area means the proportion of long ethylene sequences among the total ethylene sequences, and the proportion of long ethylene sequences that can form thick lamellae can be said to affect the mechanical properties, which are important factors in the production of polyethylene stretched films.

[0082] The inventors of the present invention adjusted the type and content of polyethylene in the polyethylene composition to satisfy the above formula 1.

[0083] B / A of the above formula 1 may be 0.16 or more, 0.163 or more, 0.17 or more, 0.175 or more, 0.18 or more, 0.185 or more, 0.19 or more, 0.195 or more, 0.2 or more, or 0.22 or more, and may be 0.4 or less, 0.38 or less, 0.36 or less, 0.35 or less, 0.33 or less, or 0.31 or less. For example, B / A of the above formula 1 may be 0.16 or more and 0.4 or less, preferably 0.16 or more and 0.35 or less, and more preferably 0.16 or more and 0.31 or less.

[0084] A polyethylene composition satisfying the above range has characteristics suitable for manufacturing a biaxially oriented film having high shrinkage resistance, printability, and transparency, by blending a first ethylene-alpha olefin copolymer having excellent flowability and stretchability by applying a specific metallocene catalyst described below, and a second ethylene-alpha olefin copolymer having excellent mechanical properties, thereby controlling the balance between mechanical properties and stretchability, thereby maintaining mechanical properties, productivity, and stretchability equivalent to or superior to those of the prior art.

[0085] The above polyethylene composition has a density of 0.925 g / cm 3 0.950 g / cm 3 , 0.925 g / cm 3 0.940 g / cm 3 , or 0.925 g / cm 3 0.938 g / cm 3 It can be. Preferably, the density is 0.925 g / cm 3 or 0.926 g / cm 3 Ideally, 0.950 g / cm 3 Below, 0.940 g / cm 3 or less, or 0.938 g / cm 3 It could be as follows:

[0086] In this specification, density (g / cm 3 ) can be measured using a density gradient tube according to the American Society for Testing and Materials ASTM D 1505 standard.

[0087] The above polyethylene composition may have a melt index (MI2.16, 190°C, 2.16 kg load) of 0.1 g / 10 min to 3.0 g / 10 min. Preferably, the melt index (MI2.16, 190°C, 2.16 kg load) may be 0.1 g / 10 min or more, 0.2 g / 10 min or more, 0.3 g / 10 min or more, or 0.35 g / 10 min or more, and 3.0 g / 10 min or less, 2.8 g / 10 min or less, 2.6 g / 10 min or less, or 2.4 g / 10 min or less.

[0088] The above melt index (MI2.16) can be measured under a load of 2.16 kg at 190 ℃ according to the American Society for Testing and Materials standard ASTM D1238 (condition E, 190 ℃, 2.16 kg).

[0089] The polyethylene composition may have a number average molecular weight Mn of 16,000 g / mol or more. Preferably, the number average molecular weight Mn may be 16,000 g / mol or more and 500,000 g / mol or less, 16,000 g / mol or more and 300,000 g / mol or less, or 16,000 g / mol or more and 50,000 g / mol or less.

[0090] The above polyethylene composition may have a weight average molecular weight Mw of 80,000 g / mol or more. Preferably, the weight average molecular weight Mw may be 80,000 g / mol or more and 1,000,000 g / mol or less, 80,000 g / mol or more and 800,000 g / mol or less, or 85,000 g / mol or more and 200,000 g / mol or less.

[0091] In addition, the molecular weight distribution Mw / Mn of the polyethylene composition may be 10.0 or less. The molecular weight distribution Mw / Mn of the polyethylene composition may be 9.8 or less, 9.5 or less, 9.3 or less, or 9.0 or less, or 8.8 or less. In addition, the molecular weight distribution Mw / Mn may be 0.5 or more, 1.0 or more, 1.2 or more, 1.5 or more, 1.8 or more, 2.0 or more, 2.5 or more, 2.8 or more, 3.0 or more, or 3.2 or more.

[0092] The above-mentioned weight average molecular weight (Mw) and number average molecular weight (Mn) are conversion values ​​for standard polystyrene measured using gel permeation chromatography (GPC).

[0093] As a specific example, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polyethylene composition can be measured using gel permeation chromatography (GPC, gel permeation chromatography, manufactured by Waters) according to the American Society for Testing and Materials ASTM D 6474 standard. Specifically, as the gel permeation chromatography (GPC) device, a Waters PL-GPC220 device can be used, and a Polymer Laboratories PLgel MIX-B 300 mm long column can be used. At this time, the measurement temperature is 160 ℃, 1,2,4-trichlorobenzene can be used as a solvent, and the flow rate can be applied at 1 mL / min. A sample of the above polyethylene composition can be pretreated by dissolving it in trichlorobenzene (1,2,4-Trichlorobenzene) containing 0.0125% BHT at 160°C for 10 hours using a GPC analysis instrument (PL-GP220), preparing it at a concentration of 10 mg / 10 mL, and then supplying it in an amount of 200 μL. Here, the values ​​of Mw and Mn can be derived using a calibration curve formed using a polystyrene standard specimen. The weight average molecular weight of the polystyrene standard specimen can be used in nine types: 2,000 g / mol, 10,000 g / mol, 30,000 g / mol, 70,000 g / mol, 200,000 g / mol, 700,000 g / mol, 2,000,000 g / mol, 4,000,000 g / mol, and 10,000,000 g / mol.

[0094] The above polyethylene composition may have a melting point Tm of 125°C to 129°C, a crystallization temperature Tc of 110°C to 115°C, and a crystallinity Xc of 35% to 48%.

[0095] These melting point Tm, crystallization temperature Tc, and crystallinity Xc can be measured using a differential scanning calorimeter (DSC).

[0096] As a specific example, the melting point Tm, crystallization temperature Tc, and crystallinity Xc of the polyethylene composition can be measured using a differential scanning calorimeter (DSC, device name: DSC Q20, manufacturer: TA instrument). First, the temperature is increased to heat the polyethylene composition sample to 180 ℃ at 10 ℃ / min (Cycle 1), isothermalized at 180 ℃ for 5 minutes, cooled to 0 ℃ at 10 ℃ / min, isothermalized at 30 ℃ for 5 minutes, and heated again to 180 ℃ at 10 ℃ / min (Cycle 2). In the DSC curve obtained through this, the temperature at the maximum point of the endothermic peak is measured as the melting temperature (Tm, ℃), and the temperature at the maximum point of the exothermic peak is measured as the crystallization temperature (Tc, ℃). At this time, the melting temperature (Tm) and crystallization temperature (Tc) are expressed as the results measured in the second temperature rising and falling section (Cycle 2), respectively.

[0097] In addition, in the second temperature-increasing section (Cycle 2), the Heat of Fusion ΔHm is obtained as the area of ​​the melting peak, and this is the theoretical value H when the crystallinity is 100%. 0 The crystallinity (Xc, %) can be obtained by dividing by m = 293.6 J / g.

[0098] The above polyethylene composition can provide a polyethylene composition satisfying the above formula 1 by including a first ethylene-alpha olefin copolymer and a second ethylene-alpha olefin copolymer.

[0099] To this end, the polyethylene composition according to the present invention may include (a) the first ethylene-alphaolefin copolymer in an amount of more than 0% by weight and less than 40% by weight, and (b) the second ethylene-alphaolefin copolymer in an amount of more than 60% by weight and less than 100% by weight.

[0100] Preferably, the (a) first ethylene-alphaolefin copolymer may be included in an amount of 5 wt% or more, 10 wt% or more, or 15 wt% or more, but not more than 38 wt%, not more than 35 wt%, or not more than 30 wt%.

[0101] Additionally, the (b) second ethylene-alphaolefin copolymer may be included in an amount of 62 wt% or more, 65 wt% or more, or 70 wt% or more, but 85 wt% or less, 90 wt% or less, or 95 wt% or less.

[0102] In this way, by combining the first and second ethylene-alphaolefin copolymers in appropriate amounts, the composition of one embodiment can satisfy the above formula 1 by satisfying an appropriate crystal structure, etc., and thereby satisfy the above-described excellent overall physical properties.

[0103] In addition, in the polyethylene composition, the first and second ethylene-alphaolefin copolymers may each be a copolymer of ethylene and an alpha-olefin having 3 to 20 carbon atoms, and in a more specific example, may be a copolymer of ethylene and 1-butene, 1-hexene or 1-octene. In a specific example, these first and second ethylene-alphaolefin copolymers may be the same or different polymers, for example, (a) the first ethylene-alphaolefin copolymer may be an ethylene / 1-octene copolymer, and (b) the second ethylene-alphaolefin copolymer may be an ethylene / 1-hexene copolymer, but the present invention is not limited thereto, and a combination satisfying the above formula 1 may be used.

[0104] (a) first ethylene-alphaolefin copolymer

[0105] The above (a) first ethylene-alpha olefin copolymer has a density of 0.870 g / cm 3 0.920 g / cm 3 , and the melting index (MI2.16, 190 ℃, 2.16 kg load) is 3.0 g / 10 min to 10.0 g / 10 min. Preferably, the (a) first ethylene-alpha olefin copolymer has a density of 0.880 g / cm 3 Above, 0.890 g / cm 3 or 0.895 g / cm 3 Ideally, 0.915 g / cm 3 Below, 0.910 g / cm 3 or less, or 0.905 g / cm 3 It could be as follows:

[0106] In addition, the above (a) first ethylene-alpha olefin copolymer may have a melting index (MI2.16, 190°C, 2.16 kg load) of 3.5 g / 10 min or more, 4.0 g / 10 min or more, or 4.5 g / 10 min or more, and 9.0 g / 10 min or less, 8.0 g / 10 min or less, or 7.0 g / 10 min or less.

[0107] That is, the above (a) first ethylene-alphaolefin copolymer has excellent flowability, excellent stretching stability, and high shrinkage resistance, and a polyethylene composition including the same can have characteristics suitable for producing a biaxially oriented film.

[0108] The above (a) first ethylene-alpha olefin copolymer may have a number average molecular weight Mn of 20,000 g / mol or more and 35,000 g / mol or less, a weight average molecular weight Mw of 60,000 g / mol or more and less than 95,000 g / mol, and a molecular weight distribution Mw / Mn of 2.0 or more and less than 3.5.

[0109] Preferably, the number average molecular weight Mn of the (a) first ethylene-alphaolefin copolymer may be 22,000 g / mol or more, 25,000 g / mol or more, or 28,000 g / mol or more, and may be 34,000 g / mol or less, 33,000 g / mol or less, or 32,000 g / mol or less.

[0110] In addition, the weight average molecular weight Mw of the (a) first ethylene-alpha olefin copolymer may be 62,000 g / mol or more, 64,000 g / mol or more, or 65,000 g / mol or more, and may also be 90,000 g / mol or less, 80,000 g / mol or less, or 70,000 g / mol or less.

[0111] In addition, the molecular weight distribution Mw / Mn of the (a) first ethylene-alphaolefin copolymer may be 2.1 or more, 2.2 or more, or 2.3 or more, and 3.2 or less, 3.0 or less, 2.8 or less, or 2.5 or less.

[0112] The above (a) first ethylene-alphaolefin copolymer may have at least one of the above-described properties, and may have all of the above-described properties to exhibit excellent mechanical strength.

[0113] Here, the method for measuring each property of the (a) first ethylene-alphaolefin copolymer is the same as that described above for the polyethylene composition, and thus a detailed description thereof is omitted.

[0114] Meanwhile, the (a) first ethylene-alpha-olefin copolymer comprises at least one alpha-olefin 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-eicosene, and mixtures thereof, together with ethylene.

[0115] Additionally, the (a) first ethylene-alphaolefin copolymer may be an ethylene / 1-octene copolymer.

[0116] The above (a) first ethylene-alpha-olefin copolymer can more easily realize the above-described properties when it is the above-described copolymer. However, the type of the above (a) first ethylene-alpha-olefin copolymer is not limited to the above-described types, and various types known in the technical field to which the present invention pertains can be provided as long as they can exhibit the above-described properties.

[0117] Meanwhile, the (a) first ethylene-alpha olefin copolymer having the above-described physical properties may be produced in the presence of a metallocene catalyst.

[0118] Specifically, the above (a) first ethylene-alphaolefin copolymer can be prepared by copolymerizing ethylene and a comonomer in the presence of a catalyst composition including a first metallocene compound represented by one of the following structural formulas.

[0119]

[0120] The first metallocene compound represented by the above structural formulas can be synthesized by applying known reactions, and more detailed synthesis methods can be referred to the examples and synthesis examples described below.

[0121] When using the first metallocene compound, the structural characteristics of the catalyst allow for controlling the degree of introduction of alpha-olefin monomers in the copolymerization process. This allows the density of the first ethylene-alpha-olefin copolymer to meet the above-described range, thereby ensuring excellent flowability and stretchability.

[0122] In the present invention, the polymerization reaction may be carried out by continuously introducing hydrogen in the presence of a catalyst composition comprising at least one of the first metallocene compounds to continuously polymerize ethylene and alpha-olefin monomers. In this case, the continuous polymerization reaction may be carried out by introducing hydrogen at a rate of 5 cc / min to 100 cc / min.

[0123] The hydrogen gas suppresses the rapid reaction of the transition metal compound in the early stage of polymerization and terminates the polymerization reaction. Accordingly, by controlling the use and amount of hydrogen gas, an ethylene / alpha-olefin copolymer with a narrow molecular weight distribution can be effectively produced.

[0124] For example, the hydrogen may be introduced at 5 cc / min or more, 7 cc / min or more, or 10 cc / min or more, or 100 cc / min or less, 50 cc / min or less, 45 cc / min or less, 35 cc / min or less, or 29 cc / min or less. When introduced under the above conditions, the ethylene / alpha-olefin copolymer produced may exhibit the above-described physical properties.

[0125] If the hydrogen gas content is less than 5 cc / min, the polymerization reaction may not be completed uniformly, making it difficult to produce an ethylene / alpha-olefin copolymer with desired properties. If it is more than 100 cc / min, there is a concern that the termination reaction may occur too quickly, resulting in the production of an ethylene / alpha-olefin copolymer with very low molecular weight.

[0126] In addition, the continuous polymerization reaction can be carried out at 100°C to 200°C, and by controlling the polymerization temperature together with the above-mentioned hydrogen input amount, the crystallinity distribution and molecular weight distribution within the ethylene / alpha-olefin copolymer can be more easily controlled. Specifically, the polymerization reaction can be carried out at 100°C to 200°C, 120°C to 180°C, 130°C to 170°C, or 140°C to 160°C, but is not limited thereto.

[0127] In the present invention, a cocatalyst may be additionally used in the catalyst composition to activate the first metallocene compound. The cocatalyst may be an organometallic compound containing a Group 13 metal.

[0128] More specifically, the cocatalyst may be an alkylaluminoxane compound having repeating units bonded in a linear, circular or network shape, and specific examples thereof include methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane or tert-butylaluminoxane. These are merely examples and are not limiting. Such cocatalysts may function as alkylating agents and activators.

[0129] Additionally, the cocatalyst may be trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide or dimethylaluminum ethoxide, which are examples and not limitation thereof. These cocatalysts may function as alkylating agents.

[0130] Finally, the cocatalyst is trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium n-butyltris(pentafluorophenyl)borate, N,N-dimethylanilinium benzyltris(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl)borate, N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)-2,3,5,6-tetrafluorophenyl)borate, N,N-dimethylanilinium pentafluorophenoxytris(pentafluorophenyl)borate, N,N-dimethyl2,4,6-trimethylanilinium Examples and not limitation thereof include, but are not limited to, tetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(2,3,4,6-tetrafluorophenyl)borate, hexadecyldimethylammonium tetrakis(pentafluorophenyl)borate, N-methyl-N-dodecylanilinium tetrakis(pentafluorophenyl)borate, or methyldi(dodecyl)ammonium tetrakis(pentafluorophenyl)borate. These cocatalysts can act as activators.

[0131] The amount of the above cocatalyst used can be appropriately adjusted depending on the properties or effects of the desired hybrid supported metallocene catalyst.

[0132] The above cocatalyst may be used in an appropriate amount so that the activation of the first metallocene compound, which is a transition metal compound, can proceed sufficiently. The amount of the cocatalyst used may be appropriately adjusted depending on the properties or effects of the desired hybrid supported metallocene catalyst.

[0133] In the present invention, the first metallocene compound can be used in a form supported on a carrier.

[0134] When the first metallocene compound is supported on a carrier, the weight ratio of the first metallocene compound and the carrier may be 1:10 to 1:1,000, more specifically 1:10 to 1:500. When the carrier and the first metallocene compound, which is a transition metal compound, are included in a weight ratio within the above range, an optimal shape may be exhibited. In addition, when the cocatalyst is supported on the carrier together, the weight ratio of the cocatalyst to the carrier may be 1:1 to 1:100, more specifically 1:1 to 1:50.

[0135] When the cocatalyst and carrier are included in the above weight ratio, the catalytic activity can be improved and the microstructure of the polymer produced can be optimized.

[0136] Meanwhile, silica, alumina, magnesia, or a mixture thereof may be used as the carrier, or these materials may be dried at high temperature to remove moisture from the surface, thereby allowing the material to be used in a state in which it contains highly reactive hydroxyl or siloxane groups on the surface. In addition, the carriers dried at high temperature may further contain oxides, carbonates, sulfates, or nitrates such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0137] The drying temperature of the carrier is preferably 200°C to 800°C, more preferably 300°C to 600°C, and most preferably 300°C to 400°C. If the drying temperature of the carrier is less than 200°C, the moisture content is too high, causing the moisture on the surface to react with the cocatalyst. If the drying temperature is more than 800°C, the pores on the surface of the carrier merge, reducing the surface area. In addition, many hydroxyl groups on the surface disappear, leaving only siloxane groups, reducing the reaction sites with the cocatalyst, which is not preferable.

[0138] In addition, the amount of hydroxyl groups on the surface of the carrier is preferably 0.1 mmol / g to 10 mmol / g, and more preferably 0.5 mmol / g to 5 mmol / g. The amount of hydroxyl groups on the surface of the carrier can be controlled by the manufacturing method and conditions of the carrier or drying conditions, such as temperature, time, vacuum or spray drying.

[0139] In addition, during the polymerization reaction, an organoaluminum compound may be further added to remove moisture in the reactor, and the polymerization reaction may proceed in its presence. Specific examples of such organoaluminum compounds include trialkylaluminum, dialkylaluminum halides, alkylaluminum dihalides, aluminum dialkyl hydrides, or alkylaluminum sesquihalides, and more specific examples thereof include Al(C2H5)3, Al(C2H5)2H, Al(C3H7)3, Al(C3H7)2H, Al(i-C4H9)2H, Al(C8H 17 )3, Al(C 12 H 25 )3, Al(C2H5)(C 12 H 25 )2, Al(i-C4H9)(C 12 H 25 )2, Al(i-C4H9)2H, Al(i-C4H9)3, (C2H5)2AlCl, (i-C3H9)2AlCl or (C2H5)3Al2Cl3. These organic aluminum compounds can be continuously introduced into the reactor, and can be introduced at a ratio of about 0.1 to 10 moles per 1 kg of the reaction medium introduced into the reactor to ensure proper moisture removal.

[0140] In addition, the polymerization pressure during continuous polymerization reaction is about 1 kgf / cm 2 About 100 kgf / cm 2 , preferably about 1 kgf / cm 2 About 50 kgf / cm 2 , more preferably about 5 kgf / cm 2About 30 kgf / cm 2 It could be.

[0141] In addition, when the first metallocene compound, which is a transition metal compound, is used in a form supported on a carrier, the first metallocene compound may be dissolved or diluted in an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, an aromatic hydrocarbon solvent such as toluene and benzene, a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene, and then introduced. It is preferable to use the solvent used here after removing a small amount of water or air, which act as a catalyst poison, by treating it with a small amount of alkyl aluminum, and it is also possible to carry out the process using an additional cocatalyst.

[0142] By using the first metallocene catalyst described above, (a) a first ethylene-alphaolefin copolymer having the above-described physical properties can be produced.

[0143] (b) second ethylene-alphaolefin copolymer

[0144] The above (b) second ethylene-alpha olefin copolymer has a density of 0.930 g / cm 3 0.950 g / cm 3 , and the melting index (MI2.16, 190 ℃, 2.16 kg load) may be 0.1 g / 10 min to 2.0 g / 10 min.

[0145] Preferably, the (b) second ethylene-alphaolefin copolymer has a density of 0.935 g / cm 3 Above, 0.938 g / cm 3 or 0.940 g / cm 3 Ideally, 0.949 g / cm 3 or less, or 0.948 g / cm 3 It could be as follows:

[0146] In addition, the second ethylene-alphaolefin copolymer (b) may have a melting index (MI2.16, 190°C, 2.16 kg load) of 0.15 g / 10 min or more, or 0.18 g / 10 min or more, and 1.8 g / 10 min or less, 1.5 g / 10 min or less, 1.2 g / 10 min or less, or 0.8 g / 10 min or less.

[0147] And, the second ethylene-alpha olefin copolymer (b) may have a number average molecular weight Mn of 12,000 g / mol or more and 35,000 g / mol or less, a weight average molecular weight Mw of 80,000 g / mol or more and 250,000 g / mol or less, and a molecular weight distribution Mw / Mn of 3.5 or more and 14.0 or less.

[0148] Preferably, the number average molecular weight Mn of the second ethylene-alphaolefin copolymer (b) may be 13,000 g / mol or more, or 15,000 g / mol or more, and may also be 33,000 g / mol or less, 32,000 g / mol or less, or 30,000 g / mol or less.

[0149] In addition, the weight average molecular weight Mw of the second ethylene-alphaolefin copolymer (b) may be 95,000 g / mol or more, 100,000 g / mol or more, 105,000 g / mol or more, or 110,000 g / mol or more, and may also be 240,000 g / mol or less, 230,000 g / mol or less, or 220,000 g / mol or less.

[0150] In addition, the molecular weight distribution Mw / Mn of the second ethylene-alphaolefin copolymer (b) may be 3.6 or more, 3.7 or more, 3.9 or more, or 4.0 or more, and 13.9 or less, 13.8 or less, 13.7 or less, or 13.6 or less.

[0151] That is, the (b) second ethylene-alpha-olefin copolymer has superior mechanical properties to the (a) first ethylene-alpha-olefin copolymer. Therefore, by blending the (a) first ethylene-alpha-olefin copolymer and the (b) second ethylene-alpha-olefin copolymer, the balance between the mechanical properties and the stretchability characteristics can be adjusted, thereby maintaining mechanical properties, productivity, and stretchability equivalent to or superior to those of the prior art, and providing characteristics suitable for manufacturing a biaxially oriented film having high shrinkage resistance, printability, and excellent transparency.

[0152] The above (b) second ethylene-alphaolefin copolymer may have at least one of the above-described properties, and may have all of the above-described properties to exhibit excellent mechanical strength.

[0153] Here, the method for measuring each property of the second ethylene-alphaolefin copolymer (b) is the same as that described above for the polyethylene composition, and thus a detailed description thereof is omitted.

[0154] Meanwhile, the second ethylene-alpha-olefin copolymer (b) comprises at least one alpha-olefin 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-eicosene, and mixtures thereof, together with ethylene.

[0155] Additionally, the (b) second ethylene-alphaolefin copolymer may be an ethylene / 1-hexene copolymer.

[0156] The above (b) second ethylene-alpha-olefin copolymer, if it is the above-described copolymer, can more easily implement the above-described properties. However, the type of the above (b) second ethylene-alpha-olefin copolymer is not limited to the above-described types, and various types known in the technical field to which the present invention pertains can be provided as long as they can exhibit the above-described properties.

[0157] And, the above (b) second ethylene-alpha olefin copolymer is produced in the presence of a metallocene catalyst.

[0158] Specifically, the above (b) second ethylene-alphaolefin copolymer can be produced by copolymerizing ethylene and a comonomer while introducing hydrogen gas in the presence of a catalyst composition including a second metallocene compound and a third metallocene compound.

[0159] The second metallocene compound may be, for example, a compound represented by one of the structural formulas below, but is not limited thereto.

[0160]

[0161] The second metallocene compound represented by the above structural formula can be synthesized by applying known reactions, and a more detailed synthesis method can be referred to the examples.

[0162] The second metallocene compound is a non-crosslinked compound containing two ligands corresponding to cyclopentadienyl substituted or unsubstituted with a hydrocarbon having 1 to 20 carbon atoms, and is advantageous in producing a low-molecular-weight copolymer having a low SCB (short chain branch) content. Specifically, the second metallocene compound can exhibit high polymerization activity because the two ligands have unshared electron pairs that can act as Lewis bases. In addition, since the two ligands are cyclopentadienyl groups with relatively low steric hindrance, the second metallocene compound exhibits high polymerization activity and low hydrogen reactivity, thereby enabling high-activity polymerization of low-molecular-weight polyethylene.

[0163] The above second metallocene compound can easily control the chemical structure, molecular weight, molecular weight distribution, mechanical properties, transparency, etc. of the polyethylene produced by controlling the degree of steric hindrance effect depending on the type of substituted functional group.

[0164] In addition, the third metallocene compound may be any one selected from the group consisting of the following compounds, but the present invention is not limited thereto:

[0165]

[0166] The third metallocene compound represented by the above structural formula can be synthesized by applying known reactions. Specifically, it can be synthesized by connecting a nitrogen compound and a cyclopentadiene derivative with a bridge compound to prepare a ligand compound, and then introducing a metal precursor compound to perform metallation, but the present invention is not limited thereto. For more detailed synthetic methods, please refer to the Examples.

[0167] The above-mentioned third metallocene compound exhibits excellent activity and can polymerize high-molecular-weight polyethylene resins. This allows for a polyethylene resin with superior mechanical properties, long-term stability, and processability, all through an increased medium-molecular-weight range. In particular, when used in a carrier, it exhibits high polymerization activity, enabling the production of ultra-high-molecular-weight polyethylene resins.

[0168] Furthermore, even when conducting a polymerization reaction including hydrogen to produce a polyethylene resin having both a high molecular weight and a broad molecular weight distribution, the third metallocene compound exhibits low hydrogen reactivity, thereby still enabling polymerization of an ultra-high molecular weight polyethylene resin with high activity. Therefore, even when used in combination with a catalyst having different characteristics, a polyethylene resin satisfying the characteristics of a high molecular weight can be produced without a decrease in activity, thereby facilitating the production of a polyethylene resin having a broad molecular weight distribution while including a high molecular weight polyethylene resin.

[0169] As described above, in the catalyst composition, the second metallocene compound may contribute to forming a low-molecular-weight copolymer having a mainly low SCB content, and the third metallocene compound may contribute to forming a high-molecular-weight copolymer having a mainly high SCB content. More specifically, the catalyst composition exhibits low copolymerizability toward a comonomer in a copolymer in a low-molecular-weight region due to the second metallocene compound, and exhibits high copolymerizability toward a comonomer in a copolymer in a high-molecular-weight region due to the third metallocene compound.

[0170] As a result, it is possible to manufacture a polyethylene resin that not only has excellent mechanical properties but also exhibits a bimodal molecular weight distribution and thus excellent heat resistance.

[0171] In particular, the above-described properties can be achieved by controlling the content ratio of the second and third metallocene compounds in the catalyst composition of the present invention, and the resulting improvement effect can be further enhanced. Specifically, by including the third metallocene compound in the catalyst composition at a higher content than the second metallocene compound, the intramolecular medium-molecular region can be increased, thereby expanding the tie molecule fraction ratio, increasing the entanglement of polymer chains, and optimizing the ratio of high-molecular-weight regions to low-molecular-weight regions.

[0172] Specifically, the second and third metallocene compounds should be included in a molar ratio of 1:0.3 to 1:8. Preferably, the second and third metallocene compounds may be included in a molar ratio of 1:0.5 to 1:7, 1:0.8 to 1:6, or 1:1 to 1:5.5.

[0173] Meanwhile, the second and third metallocene compounds have the structural characteristics described above and can be stably supported on the carrier.

[0174] In this case, the second and third metallocene compounds are used in a supported state on the carrier. When used in the supported catalyst state, the resulting polymer has excellent particle shape and bulk density, and can be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes.

[0175] Specific examples of the above-mentioned support include silica, alumina, magnesia, silica-alumina, silica-magnesia, etc., and these may further include oxides, carbonates, sulfates, and nitrates, such as Na2O, K2CO3, BaSO4, and Mg(NO3)2. Among these, when a silica support is used, the transition metal compound is supported by chemically bonding with reactive functional groups, such as siloxane groups, present on the surface of the silica support, so that almost no catalyst is liberated from the support surface during the polymer polymerization process, and as a result, fouling, in which the reactor wall or polymer particles stick together, can be minimized when manufacturing a polymer by slurry or gas phase polymerization.

[0176] Additionally, the carrier may be surface-modified through a calcination or drying process to enhance the loading efficiency and minimize leaching and fouling. Through the surface modification step described above, moisture on the carrier surface that inhibits reaction with the loading components is removed, and instead, the content of reactive functional groups capable of chemical bonding with the loading components, such as hydroxyl groups and siloxane groups, can be increased.

[0177] Specifically, the calcination or drying process for the carrier can be performed in a range from a temperature at which moisture disappears from the surface of the carrier to a temperature below which reactive functional groups, particularly hydroxyl groups (OH groups), present on the surface completely disappear. Specifically, the temperature can be 150°C to 600°C or 200°C to 500°C. If the temperature during calcination or drying for the carrier is lower than 150°C, the moisture removal efficiency is low, and as a result, there is a concern that moisture remaining in the carrier may react with the cocatalyst, thereby lowering the support efficiency. On the other hand, if the drying or calcination temperature is excessively high, exceeding 600°C, the pores present on the surface of the carrier merge, reducing the specific surface area, and also many reactive functional groups such as hydroxyl groups or silanol groups present on the surface disappear, leaving only siloxane groups, which may reduce the reaction sites with the cocatalyst.

[0178] When the above-mentioned second and third metallocene compounds are supported on a carrier, for example, when the carrier is silica, the first and third metallocene compounds may be supported in a total amount of 40 μmol or more, or 80 μmol or more, and 240 μmol or less, or 160 μmol or less, based on 1 g of silica. When supported in the above-mentioned amount range, it may exhibit appropriate supported catalytic activity, which may be advantageous in terms of maintaining the activity of the catalyst and economic efficiency.

[0179] In addition, the catalyst composition may additionally include a cocatalyst to improve high activity and process stability.

[0180] In the hybrid supported metallocene catalyst of the present invention, the type and content of the additionally included cocatalyst are as described above, and specific details are omitted.

[0181] For example, among the above compounds, the cocatalyst may be, more specifically, an alkylaluminoxane cocatalyst such as methylaluminoxane.

[0182] In addition, the alkylaluminoxane cocatalyst can further enhance catalytic activity by including a metal element that stabilizes the metallocene compounds, acts as a Lewis acid, and can form a bond through a Lewis acid-base interaction with a functional group introduced into a bridge group of the third metallocene compound.

[0183] In addition, the amount of the cocatalyst used can be appropriately adjusted depending on the properties or effects of the desired catalyst and resin composition. For example, when silica is used as the carrier, the cocatalyst can be supported in an amount of 8 mmol or more, or 10 mmol or more, and 25 mmol or less, or 20 mmol or less, based on the weight of the carrier, for example, 1 g of silica.

[0184] In addition, the above-described catalyst composition may be used for polymerization as is, or may be used in a prepolymerized state through contact with an ethylene monomer prior to use in the polymerization reaction. In this case, the manufacturing method according to one embodiment of the invention may further include a step of prepolymerizing (or prepolymerizing) the catalyst composition by contacting it with an ethylene monomer prior to producing polyethylene through a polymerization reaction.

[0185] In addition, the catalyst composition may be dissolved or diluted in an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms, such as pentane, hexane, heptane, nonane, decane, and isomers thereof, an aromatic hydrocarbon solvent such as toluene and benzene, a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene, and then introduced into the polymerization reaction described below.

[0186] 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 use an additional cocatalyst.

[0187] Meanwhile, the polymerization process can be carried out by contacting ethylene and a comonomer in the presence of the above-described catalyst composition. In particular, the polymerization reaction can be carried out in a bimodal manner using two or more reactors, or in a single polymerization reactor.

[0188] And, the polymerization temperature may be 25°C to 500°C, preferably 25°C to 200°C, and more preferably 50°C to 150°C. In addition, the polymerization pressure may be 1 kgf / cm2 to 100 kgf / cm2, preferably 1 kgf / cm2 to 50 kgf / cm2, and more preferably 5 kgf / cm2 to 40 kgf / cm2.

[0189] And, when 1-hexene is introduced as a comonomer in the copolymerization process, the amount of 1-hexene introduced may be about 2.0 wt% to about 6.0 wt% based on the total weight of ethylene introduced. More specifically, the amount of 1-hexene introduced may be about 2.1 wt% or more, about 2.2 wt% or more, about 2.3 wt% or more, about 2.4 wt% or more, or about 2.5 wt% or more, and about 5.9 wt% or less, about 5.8 wt% or less, about 5.6 wt% or less, about 5.4 wt% or less, about 5.2 wt% or less, or about 5.0 wt% or less, based on the total weight of ethylene introduced.

[0190] Meanwhile, the polyethylene resin according to the present invention can be manufactured by copolymerizing ethylene and a comonomer by introducing hydrogen gas in the presence of the above-described catalyst composition.

[0191] For example, the hydrogen gas may be present in an amount of 35 ppm to 250 ppm, 40 ppm to 200 ppm, 50 ppm to 190 ppm, 55 ppm to 180 ppm, or 55 ppm to 170 ppm relative to the weight of ethylene.

[0192] The contents of the carrier, cocatalyst, cocatalyst-supported carrier, and the second and third metallocene compounds used in the hybrid supported metallocene catalyst according to the above implementation can be appropriately adjusted depending on the properties or effects of the desired supported catalyst.

[0193] When preparing the above hybrid supported catalyst, a hydrocarbon solvent such as pentane, hexane, heptane, etc., or an aromatic solvent such as benzene, toluene, etc. may be used as a reaction solvent.

[0194] The specific manufacturing method of the supported catalyst described above can be referenced in the examples described below. However, the manufacturing method of the supported catalyst is not limited to the contents described herein. The manufacturing method may additionally employ steps commonly employed in the technical field to which the present invention pertains, and the step(s) of the manufacturing method may be modified by step(s) that are typically changeable.

[0195] Meanwhile, a polyethylene copolymer as described above can be produced through a method including a step of copolymerizing ethylene and alpha-olefin in the presence of the hybrid supported metallocene catalyst.

[0196] The above-described hybrid supported catalyst can exhibit excellent supporting performance, catalytic activity and high copolymerizability, and can produce a polyethylene copolymer capable of producing a biaxially oriented film having excellent expandable processing area characteristics and mechanical properties.

[0197] The above (b) method for producing the second ethylene-alpha-olefin copolymer can be carried out by a slurry polymerization method using ethylene and alpha-olefin as raw materials in the presence of the above-described hybrid supported catalyst, using a conventional device and contact technology.

[0198] The method for producing the second ethylene-alpha-olefin copolymer (b) above can copolymerize ethylene and alpha-olefin using a continuous slurry polymerization reactor, a loop slurry reactor, etc., but is not limited thereto.

[0199] In the hybrid supported metallocene catalyst of the present invention, the polymerization process, including the carrier for supporting the second metallocene compound and the third metallocene compound and the additionally included cocatalyst, etc., are as described above with respect to (a) the first ethylene-alphaolefin copolymer, and specific details are omitted.

[0200] (b) A second ethylene-alpha-olefin copolymer having the above-described physical properties using the supported metallocene catalyst described above can be produced by copolymerizing ethylene and alpha-olefin.

[0201] Ⅱ. Biaxially oriented film

[0202] The polyethylene composition according to the present invention having the above-described physical properties maintains excellent mechanical properties, productivity and stretching stability, and can stably form a biaxially stretched film having high shrinkage resistance, printability and transparency.

[0203] Meanwhile, the above biaxially oriented film can be manufactured by a conventional film manufacturing method, except that the above polyethylene composition is used.

[0204] For example, a biaxially oriented film according to the present invention can be manufactured into a polyethylene composition sheet with a thickness of 0.75 mm using a Bruckner lab extruder line (L / D ratio: 42, Screw diameter: 25 mm, Melt / T-Die temperature: 220°C). Thereafter, a biaxially oriented film can be manufactured by performing biaxial stretching on a polyethylene composition sheet with a width X length of 90 mm X 90 mm using a KARO 5.0 device.

[0205] Additionally, since it is a biaxially oriented film manufactured using a polyethylene composition, it can also be called a polyethylene biaxially oriented film.

[0206] The biaxially oriented film according to the present invention may further comprise additives well known in the art in addition to the polyethylene copolymer described above. Specifically, such additives include solvents, heat stabilizers, antioxidants, UV absorbers, light stabilizers, metal deactivators, fillers, reinforcing agents, plasticizers, lubricants, emulsifiers, pigments, optical bleaching agents, flame retardants, antistatic agents, and foaming agents. The types of the additives are not particularly limited, and general additives known in the art can be used.

[0207] The polyethylene biaxially oriented film according to the present invention manufactured by the above method can improve performance in terms of extensibility processing area characteristics and excellent mechanical properties.

[0208] A biaxially stretched film according to one embodiment of the present invention satisfies an MD stretch ratio of 4 or more or 5 or more, and a TD stretch ratio of 6 or more or 8 or more.

[0209] The above polyethylene biaxially oriented film may have a tensile strength in the MD direction (MD / Machine Direction direction, film length direction, longitudinal direction) measured according to ASTM D 882 standard of 70 MPa or more, 100 MPa or more, or 110 MPa or more, and 150 MPa or less, or 140 MPa or less, and a tensile strength in the TD direction (TD / Transverse Direction direction, film width direction, transverse direction) of 130 MPa or more, 150 MPa or more, or 170 MPa or more, and 250 MPa or less, or 230 MPa or less.

[0210] In addition, the polyethylene biaxially oriented film may have a tensile modulus in the MD direction measured according to ASTM D 882 of 450 MPa or more, or 500 MPa or more, and 1500 MPa or less, or 1200 MPa or less, and a tensile modulus in the TD direction of 600 MPa or more, or 700 MPa or more, or 800 MPa or more, and 1600 MPa or less, or 1400 MPa or less.

[0211] In addition, the polyethylene biaxially oriented film may have a tensile elongation in the MD direction of 200% to 300%, or 220% to 280%, and a tensile elongation in the TD direction of 70% to 140%, or 85% to 125%, as measured according to ASTM D 882.

[0212] In addition, the polyethylene biaxially oriented film may have a tensile strength in the MD direction of 6 N / mm to 14.8 N / mm, and a tensile strength in the TD direction of 2.5 N / mm to 6.8 N / mm, as measured according to ASTM 1922 standards.

[0213] In addition, the polyethylene biaxially oriented film may have a haze measured according to ASTM 1003 standards of 3% or less, or 3% or less to 0% or more, preferably 2.8% or less, 2.5% or less, 2.3% or less, 2.2% or less, 2.0% or less, or 1.9% or less, and in fact, considering the limitations in implementing the physical properties of the film, it may be 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, or 1.6% or more.

[0214] In addition, the above polyethylene biaxially oriented film has a 45 degree of elasticity measured according to ASTM 2457 standard. o Gloss (gloss 45) o) may be 80 GU or more, or 80 GU to 100 GU, and preferably 85 GU or more, 88 GU or more, 90 GU or more, or 94 GU or more.

[0215] In addition, since the above-described polyethylene biaxially oriented film has excellent stretchability and stretching stability, it can be formed into a film stretched at a stretching ratio of more than 4 times, more than 4.5 times, or less than 5 times in the MD direction, and more than 6 times, more than 6.5 times, or less than 8 times in the TD direction.

[0216] For example, the polyethylene biaxially oriented film described above may have a MD / TD direction shrinkage sum of 6.0% or less, or 5.9% or less, or 5.8% or less when shrinking at 100°C for 7 minutes according to ASTM 1204 under the condition of satisfying a draw ratio of more than 4 in the MD direction and a draw ratio of more than 6 in the TD direction, or may have a MD / TD direction shrinkage sum of 22.0% or less, 21.5% or less, or 21% or less when shrinking at 120°C for 7 minutes according to ASTM 1204.

[0217] In addition, the polyethylene biaxially oriented film described above may have a puncture strength measured according to EN 14477 of 190 N / mm or more, 300 N / mm or more, or 350 N / mm or more, and 450 N / mm or less, or 400 N / mm or less.

[0218] In the present invention, the physical properties of the biaxially stretched film can be measured according to the above-described standards.

[0219] In the present invention, by blending a first ethylene-alpha olefin copolymer having excellent flowability and extensibility as described above with a second ethylene-alpha olefin copolymer having excellent mechanical properties, the balance between mechanical properties and extensibility is controlled, thereby maintaining excellent mechanical properties, productivity, and extensibility stability, and stably producing a biaxially oriented film having high shrinkage resistance, printability, and transparency.

[0220] Hereinafter, the functions and effects of the invention will be described in more detail through specific examples. However, these examples are provided merely as examples of the invention and do not define the scope of the invention.

[0221] <Synthesis Example 1>

[0222] (1) Preparation of transition metal compound (B, first metallocene compound)

[0223]

[0224]

[0225] Ligand compound (A) (1.06 g, 3.22 mmol / 1.0 eq) and MTBE 16.0 mL (0.2 M) were placed in a 50 mL Schlenk flask and stirred first. n-BuLi (2.64 mL, 6.60 mmol / 2.05 eq, 2.5 M in THF) was added at -40 °C and reacted overnight at room temperature. After that, MeMgBr (2.68 mL, 8.05 mmol / 2.5 eq, 3.0 M in diethyl ether) was slowly added dropwise at -40 °C, followed by TiCl4 (2.68 mL, 3.22 mmol / 1.0 eq, 1.0 M in toluene) and reacted overnight at room temperature. The reaction mixture was then filtered through Celite using hexane. After drying the solvent, a brown solid transition metal compound (B) was obtained in a yield of 1.07 g (82%).

[0226] 1 H-NMR (500 MHz, CDCl3): δ 7.99 (d, 1H), 7.68 (d, 1H), 7.40 (dd, 1H), 7.30 (dd, 1H), 3.22 (s, 1H), 2.67 (s, 3H), 2.05 (s, 3H), 1.54 (s, 9H), 0.58 (s, 3H), 0.57 (s, 3H), 0.40 (s, 3H), -0.45 (s, 3H).

[0227] <Synthesis Example 2>

[0228] (1) Preparation of transition metal compound (C, second metallocene compound)

[0229]

[0230] t-butyl-O-(CH2)6-Cl was prepared using 6-chlorohexanol according to the method described in the literature (Tetrahedron Lett. 2951(1988)), and then reacted with Na(C5H5) [NaCp] to obtain t-butyl-O-(CH2)6-C5H5 (yield 60%, bp 80 ℃ / 0.1 mmHg).

[0231] Also, t-butyl-O-(CH2)6-C5H5 was dissolved in tetrahydrofuran (THF) at -78 ℃, n-BuLi was slowly added, the mixture was warmed to room temperature, and reacted for 8 hours. The above-synthesized lithium salt solution was slowly added to a suspension solution of ZrCl4(THF)2 (170 g, 4.50 mmol) / THF (30 mL) at -78 ℃, and the mixture was further reacted at room temperature for 6 hours. All volatile substances were removed by vacuum drying, and hexane was added to the obtained oily liquid substance and filtered. After the filter solution was vacuum dried, hexane was added to induce a precipitate at a low temperature (-20 ℃). The obtained precipitate was filtered at a low temperature to obtain a transition metal compound (C) in the form of a white solid (yield 92%).

[0232] 1H-NMR (300 MHz, CDCl3): δ 6.28 (t, J=2.6 Hz, 2H), 6.19 (t, J=2.6 Hz, 2H), 3.31 (t, 6.6 Hz, 2H), 2.62 (t, J=8 Hz), 1.7 - 1.3 (m, 8H), 1.17 (s, 9H).

[0233] 13 C-NMR (CDCl3): δ 135.09, 116.66, 112.28, 72.42, 61.52, 30.66, 30.31, 30.14, 29.18, 27.58, 26.00.

[0234] <Synthesis Example 3>

[0235] (1) Preparation of transition metal compound (D, tertiary metallocene compound)

[0236]

[0237] After adding 50 g of Mg(s) to a 10 L reactor at room temperature, 300 mL of THF was added. After adding approximately 20.5 g of I, the reactor temperature was maintained at 50°C. After the reactor temperature stabilized, 250 g of 6-t-butoxyhexyl chloride was added to the reactor at a rate of 5 mL / min using a feeding pump.

[0238] As 6-t-butoxyhexyl chloride was added, the reactor temperature was observed to rise by about 4 to 5°C. 6-t-butoxyhexyl chloride was continuously added and stirred for 12 hours. After 12 hours of reaction, a black reaction solution was obtained. 2 mL of the resulting black solution was taken and water was added to obtain an organic layer. 16-t-butoxyhexane was confirmed by H-NMR. This indicated that the Grignard reaction proceeded smoothly from 6-t-butoxyhexane. Thus, 6-t-butoxyhexyl magnesium chloride was synthesized.

[0239] After adding 500 g of MeSiCl3 and 1 L of THF to the reactor, the reactor temperature was cooled to -20 °C. 560 g of the synthesized 6-t-butoxyhexyl magnesium chloride was added to the reactor at a rate of 5 mL / min using a feeding pump. After the feeding of the Grignard reagent was completed, the reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, it was confirmed that a white MgCl2 salt was produced. 4 L of hexane was added, and the salt was removed through a labdori to obtain a filter solution. The obtained filter solution was added to the reactor, and hexane was removed at 70 °C to obtain a pale yellow liquid.

[0240] The obtained liquid 1 The desired compound, methyl(6-t-butoxy hexyl)dichlorosilane, was confirmed through H-NMR.

[0241] 1 H-NMR (300 MHz, CDCl3): δ 3.3 (t, 2H), 1.5 (m, 3H), 1.3 (m, 5H), 1.2 (s, 9H), 1.1 (m, 2H), 0.7 (s, 3H).

[0242] After adding 1.2 mol (150 g) of tetramethylcyclopentadiene and 2.4 L of THF to the reactor, the reactor temperature was cooled to -20 ℃.

[0243] n-BuLi 480 mL was added to the reactor at a rate of 5 mL / min using a feeding pump. After adding n-BuLi, the reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, an equivalent amount of methyl(6-t-butoxy hexyl)dichlorosilane (326 g, 350 mL) was rapidly added to the reactor. The reactor temperature was slowly raised to room temperature and stirred for 12 hours, then cooled to 0 ℃ and 2 equivalents of t-BuNH2 were added. The reactor temperature was slowly raised to room temperature and stirred for 12 hours. After 12 hours of reaction, THF was removed, 4 L of hexane was added, and a filter solution was obtained by removing salts through a labdori. The filter solution was added back to the reactor, and hexane was removed at 70 ℃ to obtain a yellow solution. The obtained yellow solution was confirmed to be a compound of methyl(6-t-butoxyhexyl)(tetramethylCpH)t-butylaminosilane through 1H-NMR.

[0244] TiCl3(THF)3 (10 mmol) was rapidly added to the dilithium salt of the ligand synthesized from n-BuLi and the ligand dimethyl(tetramethylCpH)t-butylaminosilane in a THF solution at -78°C. The reaction solution was slowly warmed from -78°C to room temperature and stirred for 12 hours. After stirring for 12 hours, an equivalent amount of PbCl2 (10 mmol) was added to the reaction solution at room temperature and stirred for 12 hours. After stirring for 12 hours, a dark black solution with a bluish tint was obtained. After removing THF from the resulting reaction solution, hexane was added and the product was filtered. After removing hexane from the obtained filter solution, 1 It was confirmed to be a transition metal compound (D) from H-NMR.

[0245] 1 H-NMR (300 MHz, CDCl3): δ 3.3 (s, 4H), 2.2 (s, 6H), 2.1 (s, 6H), 1.8 to 0.8 (m), 1.4 (s, 9H), 1.2 (s, 9H), 0.7 (s, 3H).

[0246] <Synthesis Example 4>

[0247] (1) Preparation of ligand A

[0248] 1-Benzothiophene 4.0 g (30 mmol) was dissolved in THF to prepare a 1-benzothiophene solution. Then, 14 mL (36 mmol, 2.5 M in hexane) of n-BuLi solution and 1.3 g (15 mmol) of CuCN were added to the 1-benzothiophene solution. Subsequently, 3.6 g (30 mmol) of tigloyl chloride was slowly added to the solution at -80 °C, and the resulting solution was stirred at room temperature for about 10 hours. Afterwards, 10% HCl was poured into the solution to quench the reaction, and the organic layer was separated with dichloromethane to obtain (2E)-1-(1-benzothien-2-yl)-2-methyl-2-buten-1-one as a beige solid.

[0249]

[0250] 1 H NMR (CDCl3): 7.85-7.82 (m, 2H), 7.75 (m, 1H), 7.44-7.34 (m, 2H), 6.68 (m, 1H), 1.99 (m, 3H), 1.92 (m, 3H)

[0251] 5.0 g (22 mmol) of (2E)-1-(1-benzothien-2-yl)-2-methyl-2-buten-1-one prepared above was dissolved in 5 mL of chlorobenzene, and 34 mL of sulfuric acid was slowly added to the solution while stirring vigorously. Then, the solution was stirred at room temperature for about 1 hour. Afterwards, ice water was poured into the solution, and the organic layer was separated with ether solvent to obtain 4.5 g (91% yield) of 1,2-dimethyl-1,2-dihydro-3H-benzo[b]cyclopenta[d]thiophene-3-one as a yellow solid.

[0252]

[0253] 1 H NMR (CDCl3): 7.95-7.91 (m, 2H), 7.51-7.45 (m, 2H), 3.20 (m, 1H), 2.63 (m, 1H), 1.59 (d, 3H), 1.39 (d, 3H)

[0254] To a solution of 2.0 g (9.2 mmol) of 1,2-dimethyl-1,2-dihydro-3H-benzo[b]cyclopenta[d]thiophene-3-one in a mixed solvent of 20 mL of THF and 10 mL of methanol, 570 mg (15 mmol) of NaBH4 was added at 0°C. The solution was stirred at room temperature for about 2 hours. Afterwards, HCl was added to the solution to adjust the pH to 1, and the organic layer was separated with an ether solvent to obtain an alcohol intermediate.

[0255] The alcohol intermediate was dissolved in toluene to prepare a solution. Then, 190 mg (1.0 mmol) of p-toluenesulfonic acid was added to the solution, and refluxed for about 10 minutes. The resulting reaction mixture was separated by column chromatography to obtain 1.8 g (9.0 mmol, 98% yield) of 1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophene (ligand A) in a liquid form with an orange-brown color.

[0256]

[0257] 1 H NMR (CDCl3): 7.81(d, 1H), 7.70(d, 1H), 7.33(t, 1H), 7.19(t, 1H), 6.46(s, 1H), 3.35(q, 1H), 2.14(s, 3H), 1.14(d, 3H)

[0258] (2) Preparation of ligand B

[0259] 13 mL (120 mmol) of t-butylamine and 20 mL of ether solvent were added to a 250 mL schlenk flask, and 16 g (60 mmol) of (6-tert-butoxyhexyl)dichloro(methyl)silane and 40 mL of ether solvent were added to a 250 mL schlenk flask and a different 250 mL schlenk flask to prepare t-butylamine solution and (6-tert-butoxyhexyl)dichloro(methyl)silane solution, respectively. Then, the t-butylamine solution was cooled to -78 °C, and the (6-tert-butoxyhexyl)dichloro(methyl)silane solution was slowly injected into the cooled solution, and the mixture was stirred at room temperature for about 2 hours. The resulting white suspension was filtered to obtain 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-chloro-1-methylsilanamine (ligand B), which was ivory in color and in liquid form.

[0260]

[0261] 1 H NMR (CDCl3): 3.29 (t, 2H), 1.52-1.29 (m, 10H), 1.20 (s, 9H), 1.16 (s, 9H), 0.40 (s, 3H)

[0262] (3) Cross-linking of ligands A and B

[0263] A 250 mL Schlenk flask was charged with 1.7 g (8.6 mmol) of 1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophene (ligand A), and 30 mL of THF was added to prepare a ligand A solution. After cooling the ligand A solution to -78 °C, 3.6 mL (9.1 mmol, 2.5 M in hexane) of n-BuLi solution was added to the ligand A solution, and the mixture was stirred at room temperature overnight to obtain a purple-brown solution. The solvent of the purple-brown solution was replaced with toluene, and a solution of 39 mg (0.43 mmol) of CuCN dispersed in 2 mL of THF was injected into the solution to prepare solution A.

[0264] Meanwhile, 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-chloro-1-methylsilanamine (ligand B) and toluene were injected into a 250 mL Schlenk flask, and the prepared solution B was cooled to -78 °C. The previously prepared solution A was slowly injected into the cooled solution B. Then, the mixture of solutions A and B was stirred at room temperature overnight. Then, the produced solid was filtered and removed to obtain 4.2 g (> 99% yield) of 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1-methylsilanamine (crosslinked product of ligands A and B) as a viscous liquid with a brown color.

[0265]

[0266] In order to confirm the structure of the crosslinked product of the above ligands A and B, the crosslinked product was lithiated at room temperature, and then a sample dissolved in a small amount of pyridine-D5 and CDCl3 was used. 1 H-NMR spectra were obtained.

[0267] 1H NMR (pyridine-D5 and CDCl3): 7.81 (d, 1H), 7.67 (d, 1H), 7.82-7.08 (m, 2H), 3.59 (t, 2H), 3.15 (s, 6H), 2.23-1.73 (m, 10H), 2.15 (s, 9H), 1.91(s, 9H), 1.68(s, 3H)

[0268] (4) Preparation of transition metal compounds (third metallocene compounds)

[0269] 4.2 g (8.6 mmol) of 1-(6-(tert-butoxy)hexyl)-N-(tert-butyl)-1-(1,2-dimethyl-3H-benzo[b]cyclopenta[d]thiophen-3-yl)-1-methylsilanamine (crosslinked product of ligands A and B) was placed in a 250 mL Schlenk flask, and 14 mL of toluene and 1.7 mL of n-hexane were injected into the flask to dissolve the crosslinked product. After cooling the solution to -78 °C, 7.3 mL (18 mmol, 2.5 M in hexane) of n-BuLi solution was injected into the cooled solution.

[0270] Then, the solution was stirred at room temperature for about 12 hours. Then, 5.3 mL (38 mmol) of trimethylamine was added to the solution, and the solution was stirred at about 40°C for about 3 hours to prepare solution C.

[0271] Meanwhile, 2.3 g (8.6 mmol) of TiCl4(THF)2 and 10 mL of toluene were added to a separately prepared 250 mL Schlenk flask to prepare a solution D in which TiCl4(THF)2 was dispersed in toluene. The previously prepared solution C was slowly injected into the solution D at -78 °C, and the mixture of solutions C and D was stirred at room temperature for about 12 hours. Thereafter, the solution was depressurized to remove the solvent, and the obtained solute was dissolved in toluene. Then, the solid that was not dissolved in toluene was filtered off, and the solvent was removed from the filtered solution to obtain 4.2 g (83% yield) of a transition metal compound in the form of a brown solid.

[0272]

[0273] 1 H NMR (CDCl3): 8.01 (d, 1H), 7.73 (d, 1H), 7.45-7.40 (m, 2H), 3.33 (t, 2H), 2.71 (s, 3H), 2.33 (d, 3H), 1.38 (s, 9H), 1.18 (s, 9H), 1.80-0.79(m, 10H), 0.79(d, 3H)

[0274] <Manufacture of supported catalysts>

[0275] 1) Catalyst Preparation Example 1: Preparation of Hybrid Supported Metallocene Catalyst 1

[0276] 5.0 kg of toluene solution was placed in a 20 L sus high-pressure reactor, and the reactor temperature was maintained at 40°C. 1,000 g of silica (SYLOPOL 948, manufactured by Grace Davison) dehydrated by applying vacuum at 600°C for 12 hours was placed in the reactor, and after sufficiently dispersing the silica, 80 g of the second metallocene compound, which is the transition metal compound (C) obtained in Synthesis Example 2, was dissolved in toluene and placed in the reactor, and the mixture was stirred at 200 rpm for 2 hours at 40°C for reaction. Afterwards, stirring was stopped, and the reaction solution was allowed to settle for 30 minutes, and then decantated.

[0277] 2.5 kg of toluene was charged into the reactor, and 9.4 kg of a 10 wt% methylaluminoxane (MAO) / toluene solution was added, followed by stirring at 200 rpm at 40°C for 12 hours. After the reaction, stirring was stopped, the reaction solution was allowed to settle for 30 minutes, and then decanted. 3.0 kg of toluene was added, stirred for 10 minutes, stopped, and the reaction solution was allowed to settle for 30 minutes, and then decanted.

[0278] 3.0 kg of toluene was charged into the reactor, and 314 mL of the third metallocene compound / toluene solution, which is the transition metal compound (D) obtained in Synthesis Example 3 at 29.2 wt%, was charged into the reactor, and the mixture was stirred at 200 rpm for 2 hours at 40°C to react. At this time, the molar ratio of the second metallocene compound and the third metallocene compound was 1:5 (number of moles of the second metallocene compound: number of moles of the third metallocene compound). After the reactor temperature was lowered to room temperature, stirring was stopped, and the mixture was allowed to settle for 30 minutes, and then the reaction solution was decantated.

[0279] 2.0 kg of toluene was added to the reactor and stirred for 10 minutes. After stopping the stirring and allowing it to settle for 30 minutes, the reaction solution was decanted.

[0280] 3.0 kg of hexane was added to the reactor, the hexane slurry was transferred to a filter dryer, and the hexane solution was filtered. The solution was dried under reduced pressure at 40°C for 4 hours to produce 910 g of a SiO2 hybrid supported catalyst.

[0281] 2) Catalyst Preparation Example 2: Preparation of Hybrid Supported Metallocene Catalyst 2

[0282] 3.0 kg of toluene solution was placed in a 20 L sus high-pressure reactor, and the reactor temperature was maintained at 40°C. 500 g of silica (Grace Davison, SP2212), dehydrated by applying vacuum at 600°C for 12 hours, was placed in the reactor, and after sufficient dispersion, 2.78 kg of 10 wt% methylaluminoxane (MAO) / toluene solution was placed, and the mixture was stirred at 80°C and 200 rpm for more than 15 hours.

[0283] After lowering the reactor temperature to 40°C, 200 g of the second metallocene compound / toluene solution (7.8 wt% in toluene), which is a transition metal compound prepared in Synthesis Example 2, was added to the reactor and stirred at 200 rpm for 1 hour. Next, 250 g of the third metallocene compound / toluene solution (7.8 wt% in toluene), which is a transition metal compound prepared in Synthesis Example 4, was added to the reactor and stirred at 200 rpm for 1 hour (molar ratio of the second metallocene compound and the third metallocene compound = 1:1.3).

[0284] 70 g of cocatalyst (anilinium tetrakis(pentafluorophenyl)borate) was diluted in toluene and added to the reactor, followed by stirring at 200 rpm for more than 15 hours. After lowering the reactor temperature to room temperature, stirring was stopped, and the reaction solution was allowed to settle for 30 minutes before decantation.

[0285] The toluene slurry was transferred to a filter dryer and filtered. 3.0 kg of toluene was added and stirred for 10 minutes, then stirring was stopped and filtered. 3.0 kg of hexane was added to the reactor and stirred for 10 minutes, then stirring was stopped and filtered. The mixture was dried under reduced pressure at 50°C for 4 hours to produce a 500 g-SiO2 supported catalyst.

[0286] <Manufacture of ethylene-alphaolefin copolymer>

[0287] Manufacturing Example 1: Manufacturing of ethylene / 1-hexene copolymer (PE-a)

[0288] An ethylene / 1-hexene copolymer (PE-a) was slurry polymerized in the presence of the hybrid supported catalyst prepared in catalyst preparation example 1.

[0289] At this time, the polymerization reactor was a continuous polymerizer of isobutane (i-C4) slurry loop process, with a reactor volume of 140 L and a reaction flow rate of approximately 7 m / s. The gases (ethylene, hydrogen) required for polymerization and the comonomer 1-hexene were continuously fed continuously and the individual flow rates were adjusted to suit the target product. At this time, the ethylene supply was 31.1 kg / hr, the 1-hexene input was adjusted to 2.5 wt% relative to ethylene, and the hydrogen input was adjusted to 56 ppm relative to ethylene.

[0290] In addition, the concentrations of all gases and the comonomer 1-hexene in Manufacturing Example 1 were confirmed by on-line gas chromatography. The supported catalyst was prepared as an isobutane slurry with a concentration of 4 wt% and introduced, the reactor pressure was maintained at approximately 40 bar, and the polymerization temperature was performed at approximately 80°C.

[0291] Manufacturing Example 2: Manufacturing of ethylene / 1-hexene copolymer (PE-b)

[0292] An ethylene / 1-hexene copolymer was prepared through a monomodal polymerization process.

[0293] Specifically, the ethylene supply was 10.0 kg / hr, the comonomer 1-hexene input was 6.3 ml / min, and the hydrogen input was 1.73 g / hr, using the hybrid supported metallocene catalyst 2 manufactured in the catalyst manufacturing example 2, using a hexane slurry stirred tank process polymerizer, and the polymerization reaction was performed in one loop reactor (polymerization temperature 93 ℃, polymerization pressure 7.7 kgf / cm2 ) was used to prepare ethylene / 1-hexene copolymer (PE-b).

[0294] Manufacturing Example 3: Manufacturing of ethylene / 1-butene copolymer (PE-c)

[0295] A commercially available product (LG Chem ME1000, Ziegler-Natta catalyst) was used as the ethylene / 1-butene copolymer (PE-c).

[0296] Manufacturing Example 4: Manufacturing of ethylene / 1-hexene copolymer (PE-d)

[0297] A commercially available product (LG Chem SP980, metallocene catalyst) was used as the ethylene / 1-hexene copolymer (PE-d).

[0298] Manufacturing Example 5: Manufacturing of homopolyethylene (PE-e)

[0299] A commercially available homopolyethylene (PE-e) product (LG Chem SP380, metallocene catalyst) was used.

[0300] Manufacturing Example 6: Manufacturing of ethylene / 1-octene copolymer (PE-f)

[0301] A 1.5 L continuous process reactor was preheated to 120°C while introducing 5 kg / h of hexane solvent and 0.31 kg / h of 1-octene. Triisobutylaluminum (Tibal, Triisobutylaluminum, 0.045 mmol / min), the first metallocene compound (B), which is the transition metal compound obtained in Synthesis Example 1, and dimethylanilinium tetrakis(pentafluorophenyl)borate cocatalyst (2.6 μmol / min) were simultaneously introduced into the reactor. Subsequently, ethylene (0.87 kg / h) and hydrogen gas (10 cc / min) were introduced into the reactor, and the copolymerization reaction was carried out by maintaining the temperature at 160.0°C for more than 60 minutes in a continuous process at a pressure of 89 bar, thereby obtaining an ethylene / 1-octene copolymer (PE-f).

[0302] <Test Example 1: Evaluation of the physical properties of polyethylene>

[0303] The physical properties of the ethylene-alphaolefin copolymers manufactured in the above manufacturing examples 1 to 6 were measured by the method described below and are shown in Table 1 below.

[0304] (1) Density

[0305] According to the American Society for Testing and Materials ASTM D 1505 standard, density (g / cm) is measured using a density gradient pipe. 3 ) was measured.

[0306] (2) Melting index

[0307] The melt index (MI2.16) was measured at 190°C under a load of 2.16 kg according to the American Society for Testing and Materials standard ASTM D 1238 (condition E, 190°C, 2.16 kg) (measuring equipment: Gottfert MI-4), and expressed as the weight (g) of the polymer melted for 10 minutes.

[0308] (3) Number average molecular weight, weight average molecular weight, and molecular weight distribution

[0309] For the ethylene-alphaolefin copolymers manufactured in the above Manufacturing Examples 1 to 6, the weight average molecular weight (Mw, g / mol) and number average molecular weight (Mn, g / mol) were measured using gel permeation chromatography (GPC, manufactured by Water) according to the American Society for Testing and Materials standard ASTM D 6474, and the molecular weight distribution (Mw / Mn, PDI, polydispersity index) was calculated by dividing the weight average molecular weight by the number average molecular weight.

[0310] Specifically, a Waters PLGPC220 gel permeation chromatography (GPC) device and a Polymer Laboratories PLgel MIX-B 300 mm column were used. The measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was 1 mL / min. Each sample of the ethylene-alphaolefin copolymers prepared in Preparation Examples 1 to 6 was pretreated by dissolving in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160°C for 10 hours using a GPC analyzer (PL-GP220), preparing a concentration of 10 mg / 10 mL, and then supplying it in an amount of 200 μL. The values ​​of Mw and Mn were derived using a calibration curve formed using a polystyrene standard sample. The weight average molecular weights of the polystyrene standard specimens were 9 types: 2,000 g / mol, 10,000 g / mol, 30,000 g / mol, 70,000 g / mol, 200,000 g / mol, 700,000 g / mol, 2,000,000 g / mol, 4,000,000 g / mol, and 10,000,000 g / mol.

[0311]

[0312] <Preparation of polyethylene compositions - Examples 1 to 4 and Comparative Examples 1 to 4>

[0313] Using the ethylene-alphaolefin copolymers of the above-described Manufacturing Examples 1 to 6, polyethylene compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were prepared, respectively, with the compositions shown in Table 2 below.

[0314] Specifically, a polyethylene composition was manufactured by extruding and granulating under the conditions of Twin extruder equipment, hopper 18 rpm, screw 350 rpm, and 220 ℃ (extruder: SMPLATEK TEK30MHS, L / D ratio=40, die diameter: 4 mm).

[0315]

[0316] As can be seen in Table 2 above, the polyethylene compositions of Examples 1 to 4 and Comparative Examples 1 to 4 each used two types of ethylene-alpha olefin copolymers. For example, the polyethylene composition of Example 1 contains 70 wt% of ethylene-alpha olefin copolymer PE-a and 30 wt% of ethylene-alpha olefin copolymer PE-f. This can be expressed as 70 wt% of PE-a + 30 wt% of PE-f. The same description can be applied to the polyethylene compositions of Examples 2 to 4 and Comparative Examples 1 to 4.

[0317] <Test Example 2: Evaluation of Physical Properties of Polyethylene Composition>

[0318] The physical properties of the polyethylene compositions manufactured in Examples 1 to 4 and Comparative Examples 1 to 4 were measured by the methods described below and are shown in Tables 2 and 3 below.

[0319] (1) Derivation of SSA thermogram - Distribution of ethylene sequence according to SSA analysis

[0320] Step 1) Stepwise annealing

[0321] ① (Heating) The polyolefin composition of Example 1 was heated at a first heating temperature of 180°C for 20 minutes, so that the temperature of the polyolefin composition at room temperature (approximately 25°C) reached the first heating temperature of 180°C.

[0322] ② (Quick cooling) Next, the polyolefin composition of Example 1 was cooled at a rate of 20°C / min for 1.75 minutes, until the temperature of the polyolefin composition reached 145°C (quick cooling). Thereafter, the temperature was maintained for 20 minutes.

[0323] ③ (Cooling) Additionally, the polyolefin composition at 145°C was cooled at a rate of 10°C / min for about 16.5 minutes until the temperature of the polyolefin composition reached 30°C. Thereafter, it was maintained for 5 minutes.

[0324] ④ Next, heating, rapid cooling, and cooling of the polyolefin composition of Example 1 were repeated in the same manner as described above, except that the polyolefin composition of Example 1 was heated while lowering the n+1 heating temperature by 5°C from the nth heating temperature. Specifically, heating, rapid cooling, and cooling of the polyolefin composition of Example 1 were repeated until the n+1 heating temperature reached 60°C.

[0325] ⑤ When the n+1 heating temperature becomes 60°C, the n+2 heating temperature is lowered by 10°C from the n+1 heating temperature, and heating, rapid cooling, and cooling of the polyolefin composition of Example 1 are repeated in the same manner as described above, except that the polyolefin composition is heated. Specifically, heating, rapid cooling, and cooling of the polyolefin composition are repeated until the n+2 heating temperature becomes 40°C.

[0326] Step 2) Deriving the SSA thermogram

[0327] ① In the final annealing step, the temperature of the polyolefin composition of Example 1 was cooled to -50°C after cooling to 30°C and maintained for 1 minute.

[0328] ② The polyolefin composition cooled to -50 ℃ was heated to 180 ℃ at a rate of 10 ℃ / min, and an SSA thermogram as shown in Fig. 2 was derived.

[0329] Step 3) Find the area ratio (C)

[0330] In the above SSA thermogram, the temperature range where the lamellar peak does not appear was set as the baseline, and the area for the entire temperature range and the area for the temperature range above 128°C were calculated.

[0331] Next, using the following calculation formula 1, C, which is the ratio of the area for the temperature range of 128 ℃ or higher to the area for the entire temperature range, was calculated.

[0332] [Calculation Formula 1]

[0333] C = B / A

[0334] In the above calculation formula 1,

[0335] A represents the area for the entire temperature range in the above SSA thermogram,

[0336] B refers to the area for the temperature region of 128 ℃ or higher in the above SSA thermogram.

[0337] The same process was performed for the polyethylene compositions of Examples 2 to 4 and Comparative Examples 1 to 4. The SSA thermograms derived from the results of the polyethylene compositions of Examples 2 to 4 and Comparative Examples 1 to 4 were as shown in FIGS. 2 and 3, respectively.

[0338] The results calculated by the above calculation formula 1 are shown in Table 3 below.

[0339]

[0340] (2) Density, melt index (MI2.16), weight-average molecular weight (Mw, g / mol), number-average molecular weight (Mn, g / mol), and molecular weight distribution (Mw / Mn, PDI)

[0341] First, the density, melt index (MI2.16), weight average molecular weight (Mw, g / mol), number average molecular weight (Mn, g / mol), and molecular weight distribution (Mw / Mn, PDI) of the polyethylene composition were measured using the same method as in Test Example 1.

[0342] The results are shown in Table 4 below.

[0343] (3) Melting temperature and crystallization temperature, crystallinity

[0344] Using a differential scanning calorimeter (DSC, device name: DSC Q20, manufacturer: TA instrument), the melting temperature (Tm), crystallization temperature (Tc), and crystallinity (Xc) of the polyethylene compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were measured.

[0345] Specifically, the polyethylene composition was heated to 180 ℃ at 10 ℃ / min by increasing the temperature (Cycle 1), isothermalized at 180 ℃ for 5 minutes, cooled to 0 ℃ at 10 ℃ / min, isothermalized at 30 ℃ for 5 minutes, and then heated again to 180 ℃ at 10 ℃ / min (Cycle 2). In the DSC curve obtained through this, the temperature at the maximum point of the endothermic peak was measured as the melting temperature (Tm, ℃), and the temperature at the maximum point of the exothermic peak was measured as the crystallization temperature (Tc, ℃). At this time, the melting temperature (Tm) and the crystallization temperature (Tc) are expressed as the results measured in the second temperature increasing and decreasing section (Cycle 2), respectively.

[0346] In addition, in the second temperature-increasing section (Cycle 2), the Heat of Fusion ΔHm is obtained as the area of ​​the melting peak, and this is the theoretical value H when the crystallinity is 100%. 0 The crystallinity (Xc, %) was calculated by dividing by m= 293.6 J / g.

[0347] The results are shown in Table 4 below.

[0348]

[0349] <Test Example 3: Manufacturing and Property Evaluation of Biaxially Stretched Film>

[0350] Biaxially stretched films were manufactured using the polyethylene compositions manufactured in Examples 1 to 4 and Comparative Examples 1 to 4, and then the physical properties of each were measured and shown in Table 5.

[0351] (1) Manufacturing of biaxially stretched film

[0352] - Using Bruckner's lab extruder line (L / D ratio: 42, Screw diameter: 25 mm, Melt / T-Die temperature: 220 ℃) ​​to produce polyethylene composition sheets with a thickness of 0.75 mm.

[0353] - Biaxial stretching is performed on a polyethylene composition sheet measuring 90 mm X 90 mm in length and width using KARO 5.0 equipment.

[0354] - Sequential stretching (MD→TD) is performed after preheating for 80 seconds under the following conditions.

[0355] 1) Example 1: Preheating and stretching at 120 ℃

[0356] 2) Example 2: Preheating and stretching at 125 ℃

[0357] 3) Examples 3 and 4: Preheating and stretching at 122°C

[0358] 4) Comparative Example 1: Preheating and stretching at 115 ℃

[0359] 5) Comparative examples 2 and 4: Preheating and stretching at 125 ℃

[0360] 6) Comparative Example 3: Extension was attempted under the same conditions as Comparative Example 2, but it was determined that extension was not possible.

[0361] (2) Evaluation of biaxially stretched film properties

[0362] - Tensile strength (MPa), tensile modulus (MPa), and tensile elongation (%): Measured in each MD / TD direction according to ASTM D 882 standard

[0363] - Haze (%): Measured according to ASTM 1003 standard

[0364] - Puncture strength (N / mm): Measured according to EN 14477 standard

[0365]

[0366] From the results in Tables 3 to 5 above, it was possible to manufacture a biaxially stretched film having an excellent maximum draw ratio using the polyethylene composition according to the present invention satisfying Equation 1 above.

[0367] That is, it was confirmed that a biaxially oriented film with excellent stretching stability can be manufactured using the polyethylene composition according to the present invention. Furthermore, it was confirmed that the mechanical properties of the manufactured biaxially oriented film were also excellent. In particular, it was confirmed that the mechanical properties were even better when biaxially oriented using the polyethylene compositions of Examples 1 to 3.

[0368] This appears to be because, when the above equation 1 is satisfied, the ethylene sequence length distribution of polyethylene in the polyethylene composition is excellent.

[0369] That is, it was confirmed that the polyethylene composition according to the present invention satisfying the above formula 1 has a structure suitable for producing a biaxially stretched film having excellent properties such as high shrinkage resistance, printability, and transparency.

Claims

1. A polyethylene composition comprising at least one ethylene-alphaolefin copolymer, The above polyethylene composition has a Successive Self-nucleation and Annealing (SSA) thermogram that shows the relationship between heat flux and temperature, satisfying the following equation 1. Polyethylene composition: [Formula 1] 0.16 ≤ B / A ≤ 0.4 In the above equation 1, A represents the area for the entire temperature range in the above SSA analysis diagram, B refers to the area for the temperature region of 128 ℃ or higher in the above SSA analysis diagram.

2. In paragraph 1, The above polyethylene composition, Density is 0.925 g / cm 3 0.950 g / cm 3 person, Polyethylene composition.

3. In paragraph 1, The above polyethylene composition, The number average molecular weight Mn is 16,000 g / mol or more, The weight average molecular weight Mw is 80,000 g / mol or more, The molecular weight distribution Mw / Mn is 10.0 or less, Polyethylene composition.

4. In paragraph 1, The above polyethylene composition, The melting point Tm is 125 ℃ to 129 ℃, The crystallization temperature Tc is 110 ℃ to 115 ℃, The crystallinity Xc is 35% to 48%, Polyethylene composition.

5. In paragraph 1, The above polyethylene composition, (a) a first ethylene-alphaolefin copolymer and (b) comprising a second ethylene-alphaolefin copolymer, The above (a) first ethylene-alpha olefin copolymer has a density of 0.870 g / cm 3 0.920 g / cm 3 and the melting index (MI2.16, 190 ℃, 2.16 kg load) is 3.0 g / 10 min to 10.0 g / 10 min, The above (b) second ethylene-alpha olefin copolymer has a density of 0.930 g / cm 3 0.960 g / cm 3 and the melting index (MI2.16, 190 ℃, 2.16 kg load) is 0.2 g / 10 min to 2.0 g / 10 min. Polyethylene composition.

6. In paragraph 5, (a) containing more than 0 and less than 40 wt% of the first ethylene-alphaolefin copolymer, (b) containing 60 wt% or more and less than 100 wt% of the second ethylene-alphaolefin copolymer, Polyethylene composition.

7. In paragraph 5, The above (a) first ethylene-alphaolefin copolymer, The number average molecular weight Mn is 20,000 g / mol or more, The weight average molecular weight Mw is 60,000 g / mol or more and less than 95,000 g / mol, Molecular weight distribution Mw / Mn is 2.0 or more and less than 3.5, Polyethylene composition.

8. In paragraph 5, The above (b) second ethylene-alpha olefin copolymer, The number average molecular weight Mn is 12,000 g / mol or more, The weight average molecular weight Mw is 80,000 g / mol or more and 150,000 g / mol or less, Molecular weight distribution Mw / Mn is 3.5 or more and 14.0 or less, Polyethylene composition.

9. A biaxially oriented film comprising a polyethylene composition according to any one of claims 1 to 8.

10. In paragraph 9, The above film, The maximum MD elongation ratio is greater than 4, Satisfying the maximum TD elongation ratio of more than 6, Biaxially oriented film.

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