Polyethylene resin composition and biaxially stretched film comprising same

Abstract

The present invention provides: a polyethylene resin composition which can form a small and uniform crystal structure and is thus useful for manufacturing a biaxially stretched film having excellent transparency and surface characteristics while maintaining high strength characteristics; and a biaxially stretched film comprising same.

Description

Polyethylene resin 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. 10-2024-0086290, filed July 1, 2024, Korean Patent Application No. 10-2024-0093172, filed July 15, 2024, and Korean Patent Application No. 10-2025-0062161, filed May 13, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a polyethylene resin composition useful for manufacturing a biaxially oriented film having excellent transparency and surface properties while maintaining high strength characteristics, by enabling the formation of a small and uniform crystal structure, and to a biaxially oriented film comprising the same.

[0004]

[0005] With increasing consumer concern for the environment, easily recyclable single-material packaging materials are gaining attention. For example, the food packaging and distribution industries are increasingly adopting "all-PE" films made solely from the versatile polyethylene (PE) material.

[0006] Conventional multilayer film packaging materials utilize composite materials, such as BOPP (biaxially oriented polypropylene), BOPET (biaxially oriented polyethylene terephthalate), or BOPA (biaxially oriented polyamide), in their printed layers. However, because these composite materials are non-recyclable, research and development are underway to manufacture single-material packaging films by replacing the printed layer film with PE. Replacing the printed layer film with PE requires higher physical properties and transparency than conventional PE blown film.

[0007] Meanwhile, biaxially oriented polyethylene (BOPE) film is manufactured by stretching a cast sheet in the machine direction (MD) and transverse direction (TD), and has significantly superior tensile strength, impact strength, and transparency compared to conventional blown films.

[0008] Previously, resin development for BOPE has focused on linear low-density polyethylene (LLDPE), which boasts excellent stretchability due to its low density. However, manufacturing BOPE film from LLDPE suffers from severe shrinkage and poor heat resistance, making it difficult to apply to printed layers. Furthermore, while high-density polyethylene (HDPE) offers excellent physical properties, its high crystallinity makes stretching difficult and the resulting film has low transparency.

[0009] Accordingly, in order to secure transparency and processability of the stretch film, development of a high-density polyethylene resin composition with a controlled structure is necessary.

[0010]

[0011] In order to solve the problems of the above-mentioned prior art, the present invention aims to provide a polyethylene resin composition useful for producing a biaxially oriented film having excellent transparency and surface properties while maintaining high strength properties by forming a small and uniform crystal structure, and a biaxially oriented film comprising the same.

[0012]

[0013] In order to solve the above-mentioned problem, according to the present invention, a polyethylene resin composition comprising at least one type of polyethylene and satisfying the following conditions (i) to (v) is provided:

[0014] (i) Density measured according to ASTM D792: 0.940 g / cm3 or greater;

[0015] (ii) Melt index: 0.50 to 3.00 g / 10 min when measured under a load of 2.16 kg at 190°C according to ASTM D1238;

[0016] (iii) 3.5 <logMw < 4.5 영역에서의 탄소 1000개당 SCB 평균 개수: 3.0 내지 15.0;

[0017] (iv) NCD index calculated according to the following mathematical formula 1: greater than 0;

[0018] [Mathematical Formula 1]

[0019] NCD index = - (number of SCBs per 1000 carbons at logMw=5.5 - number of SCBs per 1000 carbons at logMw=4.5)

[0020] In the above mathematical formula 1, Mw means the weight average molecular weight of the polyethylene resin composition, and SCB means a short branch chain having 2 to 7 carbon atoms bonded to the main chain of polyethylene.

[0021] (v) When the relative ratio of peak areas according to melting temperature (Tm) was measured using the SSA (successive self-nucleation and annealing) analysis method, the ratio of peak areas with Tm less than 100℃ to the total peak area was f Tm<100 ℃ and the ratio of peak areas at Tm exceeding 120℃ f Tm>120 ℃ When you say,

[0022] f Tm<100℃ is greater than 0.100, and f Tm<100℃ / f Tm>120 ℃ 0.100 to 0.300.

[0023] In addition, according to the present invention, a stretched film, specifically a biaxially stretched film, comprising the polyethylene resin composition is provided.

[0024]

[0025] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention.

[0026]

[0027] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0028]

[0029] In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

[0030]

[0031] In addition, the terms "about," "substantially," and the like used throughout this specification are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent to the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which exact or absolute values ​​are mentioned to aid understanding of the present invention.

[0032]

[0033] Also, throughout this specification, the term “polyethylene” or “ethylene (co)polymer” is a concept that includes both ethylene homopolymer and / or copolymer of ethylene and alpha-olefin.

[0034]

[0035] 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.

[0036]

[0037] The present invention is susceptible to various modifications and takes various forms. Specific examples are illustrated and described in detail below. However, this does not limit the invention to a specific disclosed form, but rather encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0038]

[0039] Hereinafter, the present invention will be described in detail.

[0040]

[0041] Specifically, the polyethylene resin composition according to the present invention comprises at least one type of polyethylene and satisfies the following conditions (i) to (v):

[0042] (i) Density measured according to ASTM D792: 0.940 g / cm3 or greater;

[0043] (ii) Melting index (MI) measured under a load of 2.16 kg at 190°C 2.16 ): 0.5 to 3.00 g / 10 min

[0044] (iii) 3.5 <logMw < 4.5 영역의 SCB 평균 개수 [ / 1000C]: 3.0 내지 15.0

[0045] (iv) NCD index calculated according to the following mathematical formula 1: greater than 0

[0046] [Mathematical Formula 1]

[0047] NCD index = - (number of SCBs per 1000 carbons at logMw=5.5 - number of SCBs per 1000 carbons at logMw=4.5)

[0048] In the above mathematical formula 1, Mw means the weight average molecular weight of the polyethylene resin composition, and SCB means a short branch chain having 2 to 7 carbon atoms bonded to the main chain of polyethylene in the polyethylene resin composition.

[0049] (v) When the relative ratio of peak areas according to melting temperature (Tm) was measured using the SSA (successive self-nucleation and annealing) analysis method, the ratio of peak areas with Tm less than 100℃ to the total peak area was f Tm<100 ℃ and the ratio of peak areas at Tm exceeding 120℃ f Tm>120 ℃ When you say,

[0050] f Tm<100℃ is greater than 0.100, and f Tm<100℃ / f Tm>120 ℃ 0.100 to 0.300.

[0051]

[0052] Meanwhile, in the present invention, SCB (Short Chain Branch) means a short chain bonded in a branch-like form to the main chain of polyethylene, specifically, a short branch chain having 2 to 7 carbon atoms bonded to the main chain of polyethylene. It is a short branch chain formed when an alpha olefin having 4 or more carbon atoms, such as 1-butene, 1-hexene, or 1-octene, is used as a comonomer, and its content may be proportional to the content of the α-olefin monomer included in the polymer chains. The SCB content means the number of branch chains having 2 to 7 carbon atoms per 1,000 carbon atoms (unit: number / 1,000C), and can be calculated through analysis using proton nuclear magnetic resonance (1H-NMR) or Fourier transform infrared spectroscopy (FT-IR). In the present invention, it was calculated through FT-IR analysis, and the specific analysis method is described in detail in the experimental examples below.

[0053]

[0054] In polyethylene resin compositions, when the SCB content is high in the low molecular weight region, specifically in the region of 3.5 < logMw < 4.5, the SCB is likely to act as a crystal nucleus. On the other hand, in the high molecular weight region, the SCB has difficulty acting as a crystal nucleus because other chains cannot quickly settle around it due to the long chain length around it. In other words, the higher the comonomer content in the low molecular weight region, the more quickly and efficiently crystal nuclei can be formed during the cooling process of the film, and the smaller the crystal size, which can lead to an improvement in the transparency of the film. A similar transparency-increasing effect can be obtained when a nucleating agent is added during film manufacturing.

[0055]

[0056] The polyethylene resin composition according to the present invention has a high average number of SCBs [ / 1000C] of 3 to 15 in the low molecular weight region of 3.5 < logMw < 4.5. Accordingly, formation of a small and uniform crystal structure is possible, and as a result, an extended film having excellent transparency can be produced. More specifically, the polyethylene resin composition may have an average number of SCBs [ / 1000C] of 3 or more, or 5 or more, or 5.4 or more, and 15 or less, or 10 or less, or 9.5 or less in the low molecular weight region of 3.5 < logMw < 4.5.

[0057]

[0058] In addition, the polyethylene resin composition according to the present invention has an NCD index greater than 0 calculated according to the above mathematical formula 1.

[0059]

[0060] In the present invention, a molecular structure having a high content of SCB derived from a comonomer in a low molecular weight region, i.e., a NCD (Normal comonomer distribution) structure, is parameterized by the NCD index as in the above mathematical formula 1, and optimized to a range that exhibits excellent stretchability and transparency improvement effects.

[0061]

[0062] In the present invention, the NCD index of the polyethylene resin composition, as defined in the above mathematical formula 1, is a graph derived through GPC and FT-IR analysis, specifically, an SCB distribution graph in which the logarithm value (log Mw) of the weight average molecular weight (Mw) (g / mol) is plotted on the x-axis and the number of SCBs per 1000 carbon atoms for the logarithm value is plotted on the y-axis, and the slope of the straight line connecting the y-values ​​(number of SCBs) between the x-axis (log Mw) section 4.5 and 5.5 is multiplied by -1. When the polyethylene resin composition has an NCD structure, the slope value becomes a negative number because the SCB content is higher at low molecular weights. Therefore, in order to indicate that the NCD structure is strengthened as the NCD index has a positive value, the slope is multiplied by -1 and expressed as a positive number.

[0063]

[0064] Meanwhile, the number of SCBs per 1000 carbon atoms at log Mw = 5.5 and the number of SCBs per 1000 carbon atoms at log Mw = 4.5 used in calculating the NCD index value can be calculated by measuring the molecular weight distribution and the number of SCBs (short-chain branches, side branches having 2 to 7 carbon atoms per 1000 carbon atoms) for each molecular weight through GPC and FT-IR analysis of the polyethylene resin composition. The specific measurement method and measurement conditions are described in detail in the experimental examples below.

[0065]

[0066] If the NCD index is greater than 0, i.e., a positive value, it has an NCD structure in which the content of SCB derived from the comonomer is high in the low molecular weight region. On the other hand, if the NCD index is 0 or less than 0, i.e., a negative value, it has a BOCD structure in which the content of SCB derived from the comonomer is low in the low molecular weight region and the content of SCB is high in the high molecular weight region. In this case, the stretchability is deteriorated because the fluidity and chain entanglement of the low molecular weight tie molecules involved in the formation of microfibrils during TD stretching after MD stretching are reduced. It is also disadvantageous in terms of transparency.

[0067]

[0068] More specifically, the polyethylene resin composition according to the present invention may have an NCD index of more than 0, or 0.5 or more, or 1.0 or more, or 1.5 or more, or 1.7 or more, or 2.0 or more. On the other hand, if the NCD index is too high, the density of the low molecular weight region during polymerization is very low, making it difficult to manufacture using a slurry process, or the average SCB content increases, lowering the density, and as a result, the tensile strength and shrinkage characteristics, and heat resistance of the film may deteriorate. Therefore, the polyethylene resin composition may have an NCD index of 10 or less, or 8 or less, or 6 or less, or 5.5 or less, or 5.2 or less, or 5.0 or less.

[0069]

[0070] Meanwhile, in the case of biaxially stretched films, they are generally extruded at about 250°C and then rapidly cooled to below 100°C through a chill roll.

[0071] In this regard, the polyethylene resin composition according to the present invention has a fraction of polymers capable of nucleation at a temperature of less than 100°C, i.e., a fraction of low crystallinity, as measured by SSA. Tm<100 ℃When defined as , the range is 0.100 or greater.

[0072]

[0073] As the fraction of low-crystallinity increases, the film's crystal size decreases, increasing the film's transparency and reducing its surface roughness. The film's surface roughness indirectly indicates the size of the crystals present on the surface; smaller crystals decrease surface roughness. Furthermore, assuming similar internal haze, surface roughness and haze are proportional.

[0074]

[0075] The polyethylene resin composition according to the present invention can exhibit excellent transparency and reduced surface roughness by having a low crystal fraction of 0.100 or more. More specifically, the polyethylene resin composition f Tm<100℃ It may be 0.100 or more, or 0.101 or more, or 0.102 or more, or 0.110 or more, and 0.200 or less, or 0.150 or less, or 0.145 or less, or 0.140 or less, or 0.135 or less.

[0076]

[0077] Meanwhile, as the fraction of the above low crystallinity increases, the crystal size of the film decreases and the transparency of the stretched film increases, but as the fraction of the low crystallinity increases, high crystallinity (f Tm>120 ℃ ) decreases. In this case, the overall density decreases, which lowers the stiffness of the film. In this regard, the polyethylene resin composition according to the present invention has f Tm>120℃ f for Tm<100 ℃ The ratio of f Tm<100 ℃ / f Tm>120 ℃ By controlling the range of 0.100 to 0.300, the effect of increasing transparency can be implemented while maintaining the rigidity of the film at a certain level or higher. More specifically, the polyethylene resin composition is fTm<100 ℃ / f Tm>120 ℃ It may be 0.100 or more, or 0.120 or more, or 0.140 or more, or 0.150 or more, and 0.300 or less, or 0.280 or less, or 0.270 or less, or 0.200 or less.

[0078]

[0079] In addition, when the polyethylene resin composition is measured for the relative ratio of peak areas according to melting temperature (Tm) using the SSA analysis method, the ratio of peak areas having Tm exceeding 100°C and less than 120°C to the total peak area is f100°C. <Tm<120℃라고 했을 때, f100℃<Tm<120℃가 0.150 내지 0.350 일 수 있다. 보다 구체적으로는 f100℃<Tm<120℃가 0.150 이상, 또는 0.160 이상, 또는 0.170 이상, 또는 0.180 이상이고, 0.350 이하, 또는 0.345 이하, 또는 0.340 이하, 또는 0.200 이하일 수 있다.

[0080]

[0081] In addition, when the polyethylene resin composition was measured for the relative ratio of peak areas according to melting temperature (Tm) using the SSA analysis method, the ratio f of the peak area at Tm exceeding 120°C to the total peak area Tm>120℃ can be between 0.500 and 0.800. More specifically, f Tm>120℃ It may be 0.500 or more, or 0.510 or more, or 0.520 or more, or 0.600 or more, and 0.800 or less, or 0.750 or less, or 0.730 or less, or 0.725 or less, or 0.720 or less.

[0082]

[0083] Successive Self-nucleation and Annealing (SSA) is a method that uses a Differential Scanning Calorimeter (DSC) to gradually lower the temperature and rapidly cool at the end of each step to preserve the crystals crystallized at the corresponding temperature at each step.

[0084]

[0085] That is, when a polyethylene resin composition is heated to completely melt, cooled to a specific temperature (T), and slowly annealed, lamellae that are not stable at that temperature (T) remain melted, and only stable lamellae crystallize. At this time, the stability for that temperature (T) depends on the thickness of the lamellae, and the thickness of the lamellae depends on the chain structure. Therefore, by performing this heat treatment step by step, the lamella thickness and its distribution according to the polymer chain structure can be quantitatively measured, and accordingly, the distribution of each melting peak area can be measured.

[0086]

[0087] The above SSA can be performed by heating the polyethylene resin composition to a first heating temperature of 120 to 124°C using a differential scanning calorimeter, maintaining the temperature for 15 to 30 minutes, and then cooling to 28 to 32°C, and then gradually lowering the heating temperature to a temperature 3 to 7°C lower than the nth heating temperature, and repeating heating-annealing-quenching until the final heating temperature becomes 50 to 54°C.

[0088]

[0089] More specifically, the above SSA can be performed in the following steps i) to v):

[0090] i) A step of heating a polyethylene resin composition to 160°C using a differential scanning calorimeter and maintaining it for 30 minutes to remove all thermal history before measurement;

[0091] ii) A step of lowering the temperature from 160℃ to 122℃, maintaining it for 20 minutes, and then lowering the temperature to 30℃ and maintaining it for 1 minute;

[0092] iii) A step of heating to a temperature of 117℃, which is 5℃ lower than 122℃, and maintaining it for 20 minutes, then lowering the temperature to 30℃ and maintaining it for 1 minute;

[0093] iv) a step of gradually lowering the heating temperature by making the n+1th heating temperature 5℃ lower than the nth heating temperature, and maintaining the same heating rate, holding time, and cooling temperature until the heating temperature reaches 52℃; and

[0094] v) Finally, the temperature is raised from 30℃ to 160℃.

[0095]

[0096] More specifically, using a differential scanning calorimeter (Device name: DSC8000, Manufacturer: PerkinElmer), the polyethylene resin composition is initially heated to 160°C and maintained for 30 minutes to completely remove the sample's thermal history prior to measurement. The temperature is then reduced from 160°C to 122°C and maintained for 20 minutes, then reduced to 30°C and maintained for 1 minute before being increased again.

[0097]

[0098] Next, heat to a temperature (117℃) that is 5℃ lower than the initial heating temperature of 122℃ and maintain for 20 minutes, then lower the temperature to 30℃ and maintain it for 1 minute, and then increase the temperature again. In this way, the n+1th heating temperature is set to a temperature that is 5℃ lower than the nth heating temperature, and the holding time and cooling temperature are the same while gradually lowering the heating temperature until it reaches 52℃. At this time, the temperature rising and falling speeds are each adjusted to 20℃ / min. Finally, in order to quantitatively analyze the distribution of the crystals formed by repeating heating-annealing-quenching, the temperature is increased from 30℃ to 160℃ at a heating rate of 10℃ / min and the heat amount change is observed to measure the thermogram.

[0099]

[0100] In this way, when the polyethylene resin composition of the present invention is repeatedly heated-annealed-quenched in the SSA manner, peaks appear at different temperatures, and the relative content of the peaks according to the melting temperature range can be calculated from these peaks. At this time, the relative content of the peaks can be defined as the ratio of the peak area in the corresponding melting temperature range (less than 100°C, greater than 100°C and less than 120°C, greater than 120°C) to the area of ​​the crystal melting peak in the entire temperature range.

[0101]

[0102] In addition, the polyethylene resin composition according to the present invention has a density of 0.940 g / cm3 or more as measured according to ASTM D792.

[0103] The density of the polyethylene resin composition affects the film stiffness during the production of the stretched film. When the density of the polyethylene resin composition is 0.940 g / cm 3 If it is less than 0.940 g / cm, the film rigidity is reduced. More specifically, the density of the polyethylene resin composition is 0.940 g / cm 3 Exceeding 0.942 g / cm 3or 0.943 g / cm 3 or 0.945 g / cm 3 or 0.948 g / cm 3 or 0.950 g / cm 3 It may be abnormal. On the other hand, if the density of the polyethylene resin composition is too high, it is not easy to manufacture, and the film using it may break when stretched. Considering this, the polyethylene resin composition has a density of 0.970 g / cm. 3 or less, or 0.960 g / cm 3 or less, or 0.955 g / cm 3 or less, or 0.953 g / cm 3 or less, or 0.951 g / cm 3 It could be as follows:

[0104]

[0105] In addition, the polyethylene resin composition has a melt index (MI) of 0.5 to 3.00 g / 10 min along with a high density as described above. 2.16 ) is indicated.

[0106] For the production of a stretched film according to the present invention, it is preferable that the polyethylene resin composition have a melting index within the above range. MI 2.16If it is less than 0.5 g / 10 min, the processing pressure increases, resulting in a decrease in processability, and if it exceeds 3.00 g / 10 min, bubble stability deteriorates due to high fluidity, which may cause film thickness deviation. More specifically, the polyethylene resin composition has an MI of 0.50 g / 10 min or more, or 0.80 g / 10 min or more, or 1.00 g / 10 min or more, or 1.20 g / 10 min or more, or 1.25 g / 10 min or more, or 1.30 g / 10 min or more, and 3.00 g / 10 min or less, or 2.50 g / 10 min or less, or 2.00 g / 10 min or less, or 1.80 g / 10 min or less, or 1.65 g / 10 min or less, or 1.60 g / 10 min or less. 2.16 can be expressed.

[0107]

[0108] Meanwhile, in the present invention, the melting index of the polyethylene resin composition can be measured under a load of 2.16 kg at 190°C according to ASTM D1238, and is expressed as the weight (g) of the polymer after melting for 10 minutes.

[0109]

[0110] In addition, in the polyethylene resin composition according to the present invention, the polyethylene may be specifically an ethylene / alpha olefin copolymer having 3 to 20 carbon atoms, more specifically an ethylene / alpha olefin copolymer having 4 to 10 carbon atoms. Even more specifically, the polyethylene may be an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, or an ethylene / 1-octene copolymer.

[0111]

[0112] Meanwhile, in the polyethylene resin composition according to the present invention, the polyethylene can be produced by a production method including a step of polymerizing ethylene and an olefin monomer having 3 to 20 carbon atoms in the presence of a hybrid supported metallocene catalyst including, for example, at least one first metallocene compound selected from compounds represented by the following chemical formula 1; at least one second metallocene compound selected from compounds represented by the following chemical formula 2; and a carrier supporting the first and second metallocene compounds.

[0113] [Chemical Formula 1]

[0114]

[0115] In the above chemical formula 1,

[0116] M1 is a group 4 transition metal,

[0117] X 11 and X 12 are each independently substituted or unsubstituted C 1-20 Alkyl or halogen,

[0118] R1 to R5, and R7 to R 12 are each independently hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 And,

[0119] R6 is substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 However,

[0120] R1 to R 12 At least one of them is -(CH2) n1 -OR 13 And,

[0121] R 13 Silver substituted or unsubstituted C 1-20 It is alkyl,

[0122] n1 is an integer from 0 to 10,

[0123] [Chemical Formula 2]

[0124]

[0125] In the above chemical formula 2,

[0126] M2 is a group 4 transition metal,

[0127] X 21 and X 22 are each independently substituted or unsubstituted C 1-20 Alkyl or halogen,

[0128] T2 is C (carbon) or Si (silicon),

[0129] Q 21 and Q 22 are each independently substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n2 -OR 32 This or Q 21 and Q 22 C, which is substituted or unsubstituted by combining with each other 3-20 Forming a cycloalkyl ring,

[0130] R 20 Inland R 31 are each independently hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n2 -OR 32 This or R 20 Inland R 31 C, which is substituted or unsubstituted, is formed by combining two adjacent C's. 3-20 Forming a cycloalkyl ring,

[0131] R 20 Inland R 31 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 And,

[0132] R 32 is substituted or unsubstituted C 1-20 It is alkyl,

[0133] n2 is an integer from 0 to 10.

[0134]

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

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

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

[0138] C 3-20 The cycloalkyl ring may be a ring composed of carbon atoms. It may be a hydrocarbon ring having 3 to 20 carbon atoms; a hydrocarbon ring having 3 to 15 carbon atoms; or a hydrocarbon ring having 3 to 10 carbon atoms. More specifically, C 3-20 The cycloalkyl ring may be a cyclopropene ring, a cyclobutene ring, a cyclopentene ring, or a cyclohexene ring.

[0139] C 2-20 Alkenyl may be straight-chain, branched-chain or cyclic alkenyl. Specifically, the above C 2-20The alkenyl may be a straight chain alkenyl having 2 to 20 carbon atoms, a straight chain alkenyl having 2 to 10 carbon atoms, a straight chain alkenyl having 2 to 5 carbon atoms, a branched chain alkenyl having 3 to 20 carbon atoms, a branched chain alkenyl having 3 to 15 carbon atoms, a branched chain alkenyl having 3 to 10 carbon atoms, a cyclic alkenyl having 5 to 20 carbon atoms or a cyclic alkenyl having 5 to 10 carbon atoms. More specifically, C 2-20 The alkenyl may be ethenyl, propenyl, butenyl, pentenyl or cyclohexenyl.

[0140] C 1-20 Alkoxy may be a straight-chain, branched-chain or cyclic alkoxy group. Specifically, the above C 1-20 The alkoxy may be a straight chain alkoxy group having 1 to 20 carbon atoms; a straight chain alkoxy group having 1 to 10 carbon atoms; a straight chain alkoxy group having 1 to 5 carbon atoms; a branched chain or cyclic alkoxy group having 3 to 20 carbon atoms; a branched chain or cyclic alkoxy group having 3 to 15 carbon atoms; or a branched chain or cyclic alkoxy group having 3 to 10 carbon atoms. More specifically, the alkoxy group having 1 to 20 carbon atoms may be a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a tert-butoxy group, an n-pentoxy group, an iso-pentoxy group, a neo-pentoxy group, or a cyclohexene group.

[0141] C 2-20 Alkoxyalkyl is -R y -OR z Alkyl (-R) with a structure containing y ) is one or more hydrogens of alkoxy (-OR z ) may be a substituent substituted with. Specifically, the alkoxyalkyl having C2 to C20 carbon atoms may be a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an iso-propoxymethyl group, an iso-propoxyethyl group, an iso-propoxyhectyl group, a tert-butoxymethyl group, a tert-butoxyethyl group, or a tert-butoxyhexyl group.

[0142] C 6-60Aryl may refer to a monocyclic, bicyclic, or tricyclic aromatic hydrocarbon. Specifically, the C6 to C60 aryl may be a phenyl group, a naphthyl group, an anthracenyl group, or the like.

[0143] C 7-20 Alkylaryl may mean a substituent in which one or more hydrogens of aryl are replaced by alkyl. Specifically, the above C 7-20 The alkylaryl may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl or cyclohexylphenyl.

[0144] C 7-20 Arylalkyl may mean a substituent in which one or more hydrogens of alkyl are replaced by aryl. Specifically, the above C 7-20 The arylalkyl group may be benzyl, phenylpropyl or phenylhexyl.

[0145] Also, group 4 transition metals can include titanium, zirconium, and hafnium.

[0146]

[0147] The above hybrid supported metallocene catalyst is a hybrid catalyst comprising a first metallocene compound having a high molecular weight and high crystallinity and a second metallocene compound having a low molecular weight and low crystallinity.

[0148]

[0149] Copolymerization in a single reactor using a hybrid supported metallocene catalyst requires controlling the expression of polymerization characteristics that differ among the metallocene compounds constituting the hybrid supported metallocene catalyst under a single copolymerization condition. Specifically, obtaining polyethylene suitable for biaxial stretching requires the coexistence of high-molecular-weight, high-crystallinity components and low-molecular-weight, low-crystallinity components.

[0150]

[0151] The first metallocene compound represented by the above chemical formula 1 has the characteristics of a lower polymerization rate of the comonomer and a higher polymerization rate of the ethylene monomer compared to the second metallocene compound due to the structure of the non-bridged ligand bonded to the central metal. As a result, under ethylene / 1-hexene copolymerization conditions, it can express a high molecular weight, high crystallinity polyethylene with a small number of SCBs and a high Mw.

[0152]

[0153] Meanwhile, the second metallocene compound represented by Chemical Formula 2 has a higher polymerization rate of comonomer and a lower polymerization rate of ethylene monomer compared to the first metallocene compound due to the bridge-type ligand structure bonded to the central metal. This allows the expression of low-molecular-weight, low-crystallinity polyethylene with a high SCB and low Mw under polyethylene polymerization conditions.

[0154]

[0155] Specifically, the central metal (M1) of chemical formula 1 may be a Group 4 transition metal, specifically Ti, Zr, or Hf, and more specifically Hf or Zr.

[0156]

[0157] Specifically, X 11 and X 12 can each independently be methyl or chloro, and more specifically X 11 and X 12 can be all methyl or all chloro.

[0158]

[0159] Specifically, R1 to R5, and R7 to R 12 are each independently hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-20 Aryl, or -(CH2) n1 -OR 13 , and R6 is substituted or unsubstituted C 1-20Alkyl, substituted or unsubstituted C 6-20 Aryl, or -(CH2) n1 -OR 13 However, R1 to R 12 One or both of them are -(CH2) n1 -OR 13 It could be.

[0160]

[0161] Specifically, either R7 or R8 is -(CH2) n1 -OR 13 And the rest of R1 to R5 and R9 to R 12 are each independently hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 , and R6 is substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 It could be.

[0162]

[0163] Specifically, R1 to R5 are each independently hydrogen, methyl, isopropyl, n-butyl, phenyl, or -(CH2) n1 -OR 13 may be. More specifically, R1 to R5 may each independently be hydrogen, methyl, n-butyl, phenyl, or tertbutoxyhexyl.

[0164]

[0165] Specifically, R6 is unsubstituted or C 6-10 C substituted with aryl or Si(R')3 1-20 Alkyl; or unsubstituted, or C 1-12 C substituted with alkyl or Si(R')3 6-20 Aryl; may be, where R' is C 1-20 Alkyl or C 6-12Aryl may be. More specifically, R6 is C unsubstituted or substituted with phenyl, trimethylsilyl, or triphenylsilyl. 1-20 Alkyl; or C unsubstituted or substituted with methyl, ethyl, propyl, n-butyl, iso-butyl, or tert-butyl 6-20 Aryl; may be. More specifically, R6 may be methyl, ethyl, isopropyl, benzyl, trimethylsilylmethyl, or phenyl.

[0166]

[0167] Specifically, either R7 or R8 is -(CH2) n1 -OR 13 And the rest of R9 to R 12 Each of R7 or R8 may be hydrogen. More specifically, one of R7 or R8 is tert-butoxy hexyl, and the other and R9 to R 12 Each can be hydrogen.

[0168]

[0169] Specifically, R 13 It may be tert-butyl.

[0170]

[0171] Specifically, n1 may be an integer from 4 to 10, more specifically, n1 may be an integer from 4 to 7, and even more specifically, n1 may be 6.

[0172]

[0173] Specifically, the first metallocene compound represented by the above chemical formula 1 may be any one selected from the group consisting of:

[0174] .

[0175]

[0176] Meanwhile, the method for producing the first metallocene compound represented by the above chemical formula 1 is not particularly limited, but may be produced by a method such as the following reaction scheme 1, for example.

[0177]

[0178] The compound represented by the above chemical formula 1 is difficult to synthesize due to the steric hindrance of the indene ligand, but the compound represented by the above chemical formula 1 can be produced in high yield and high purity according to a method such as the following reaction scheme 1.

[0179]

[0180] Accordingly, according to one embodiment of the present invention, the compound represented by the chemical formula 1 is

[0181] A step of preparing a ligand of chemical formula 1-3 by reacting a compound represented by chemical formula 1-1 with a compound represented by chemical formula 1-2; and

[0182] It can be produced by a production method including a step of reacting a ligand of chemical formula 1-3, a compound represented by chemical formula 1-4, and a halogen salt of a transition metal represented by chemical formula 1-5:

[0183] [Reaction Formula 1]

[0184]

[0185] In the above reaction formula 1,

[0186] M1, X 11 , X 12 and R1 to R 12 is as defined in the above chemical formula 1,

[0187] X' is each independently a halogen.

[0188]

[0189] Specifically, the central metal (M2) of chemical formula 2 may be a Group 4 transition metal such as Ti, Zr, or Hf, and more specifically, may be Zr.

[0190]

[0191] Specifically, X 21 , X 22 can each independently be methyl or chloro, and more specifically X 21 , X 22Each can be chloro.

[0192]

[0193] Specifically, T2 can be C (carbon).

[0194]

[0195] Specifically, R 20 Inland R 31 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 It can be. More specifically, R 20 Inland R 25 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 It can be. More specifically, R 20 Inland R 31 , Q 21 and Q 22 One or both of them are -(CH2) n2 -OR 32 It can be. More specifically, R 20 Inland R 25 , Q 21 and Q 22 One or both of them are -(CH2) n2 -OR 32 It can be. More specifically, R 20 Inland R 25 , Q 21 and Q 22 Either one or both may be tert-butoxyhexyl.

[0196]

[0197] Specifically, Q 21 and Q 22 are each independently substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 6-20 Aryl, or -(CH2) n2 -OR 32 This or Q 21 and Q 22C, which is substituted or unsubstituted by combining with each other 3-20 can form a cycloalkyl ring. More specifically, Q 21 and Q 22 are each independently methyl, ethyl, isopropyl, phenyl, or -(CH2) n2 -OR 32 This or Q 21 and Q 22 can combine with each other to form a cyclopentene ring or a cyclohexene ring.

[0198]

[0199] Specifically, R 20 Inland R 23 are each independently hydrogen, C 1-20 Alkyl, C 6-20 Aryl, or -(CH2) n2 -OR 32 It can be, more specifically, R 20 Inland R 23 can each independently be hydrogen, methyl, n-butyl, phenyl, or tertbutoxyhexyl. More specifically, R 20 Inland R 23 One of them is tert-butoxyhexyl or n-butyl, and the other is hydrogen, or R 20 Inland R 23 Two of them can be independently methyl, n-butyl, or phenyl, and the remainder can be hydrogen.

[0200]

[0201] Specifically, R 24 Inland R 31 are each independently hydrogen, C 1-10 Alkyl, C 6-20 Aryl, or -(CH2) n2 -OR 32 This or R 24 Inland R 31 C, which is substituted or unsubstituted, is formed by combining two adjacent C's. 3-10 can form a cycloalkyl ring. More specifically, R 24 Inland R31 are each independently hydrogen, tert-butyl or tert-butoxyhexyl, or R 24 Inland R 31 Two adjacent ones can combine to form a cyclohexane ring substituted with four methyl groups.

[0202]

[0203] Specifically, R 32 may be tertbutyl.

[0204]

[0205] Specifically, n2 may be an integer from 4 to 10, more specifically, n2 may be an integer from 4 to 7, and even more specifically, n2 may be 6.

[0206]

[0207] Specifically, the metallocene compound represented by the above chemical formula 2 may be any one selected from the group consisting of:

[0208] .

[0209]

[0210] Meanwhile, the method for producing the second metallocene compound represented by the above chemical formula 2 is not particularly limited, but may be produced by a method such as the following reaction formula 2, for example.

[0211] The compound represented by the above chemical formula 2 is difficult to synthesize due to the steric hindrance of the indene ligand, but the compound represented by the above chemical formula 2 can be produced in high yield and high purity according to a method such as the following reaction scheme 2.

[0212]

[0213] Accordingly, according to one embodiment of the present invention, the compound represented by the chemical formula 2 is

[0214] A step of producing a compound represented by chemical formula 2-3 by reacting a compound represented by chemical formula 2-1 with a compound represented by chemical formula 2-2;

[0215] A step of preparing a ligand of chemical formula 2-5 by reacting a compound represented by chemical formula 2-3 with a compound represented by chemical formula 2-4; and

[0216] It can be produced by a production method including a step of reacting a ligand of Chemical Formula 2-5 with a halogen salt of a transition metal represented by Chemical Formula 2-6:

[0217] [Reaction Formula 2]

[0218]

[0219] In the above reaction formula 2,

[0220] M2, X 21 , X 22 , T2, Q 21 , Q 22 and R 20 Inland R 31 is as defined in the above chemical formula 2,

[0221] X" is each independently a halogen.

[0222]

[0223] Meanwhile, in the hybrid supported metallocene catalyst, the first metallocene compound and the second metallocene compound may be supported in a molar ratio of 1:1 to 25:1, or 5:1 to 25:1, or 7:1 to 20:1, or 7:1 to 15:1, or 7:1 to 10:1, or 10:1 to 20:1, or 10:1 or 15:1, or 15:1 to 20:1. That is, the molar ratio of the first metallocene compound to 1 mole of the second metallocene compound may be 1 to 25, or 5 to 25, or 7 to 20, or 7 to 15, or 7 to 10, or 10 to 20, or 10 or 15, or 15 to 20. When the molar ratio of the first metallocene compound to 1 mole of the second metallocene compound is less than 1, the high crystallinity content is low, making it difficult for the stretched film to have heat resistance, and when the molar ratio of the first metallocene compound to 1 mole of the second metallocene compound exceeds 25, the low crystallinity content is low, making biaxial stretching processability difficult.

[0224]

[0225] In addition, in the hybrid supported metallocene catalyst, a carrier having a highly reactive hydroxyl group, silanol group, or siloxane group on the surface may be used as a carrier for supporting the first metallocene compound and the second metallocene compound, and for this purpose, a carrier whose surface has been modified by calcination or whose surface has had moisture removed by drying may be used. Specifically, silica such as silica manufactured by calcining silica gel, silica dried at high temperature, silica-alumina, and silica-magnesia may be used, and these may typically contain oxides, carbonates, sulfates, and nitrate components such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0226]

[0227] In addition, when used in a supported catalyst state, the particle shape and bulk density of the polymer produced are excellent, and it can be suitably used in conventional slurry polymerization, bulk polymerization, and gas phase polymerization processes. In addition, among various carriers, the silica carrier is supported by chemically bonding the functional group of the transition metal compound, so that almost no catalyst is liberated from the surface of the carrier during the ethylene polymerization process, and as a result, when producing polyethylene by slurry or gas phase polymerization, fouling caused by adhesion of the reactor wall or polymer particles to each other can be minimized.

[0228]

[0229] In addition, when supported on the carrier, the supported amount of the first and second metallocene compounds is not particularly limited, and it is preferable that they be supported so as to realize sufficient catalytic activity. For example, the first and second metallocene compounds may be independently supported in an amount of 1 mmol or more and 500 mmol or less based on 1,000 g of the carrier.

[0230]

[0231] In addition, the above hybrid metallocene catalyst may further include a cocatalyst in order to improve high activity and process stability.

[0232] Specifically, the cocatalyst may include at least one compound represented by the following chemical formula 3.

[0233] [Chemical Formula 3]

[0234] -[Al(R 41 )-O]a-

[0235] In the above chemical formula 3,

[0236] R 41 is a halogen; or C substituted or unsubstituted with a halogen 1-20 It is hydrocarbyl;

[0237] a is an integer greater than or equal to 2.

[0238]

[0239] Meanwhile, in the present specification, a hydrocarbyl group is a monovalent functional group in the form of removing a hydrogen atom from a hydrocarbon, and may include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an aralkenyl group, an aralkynyl group, an alkylaryl group, an alkenylaryl group, and an alkynylaryl group. In addition, the hydrocarbyl group having 1 to 20 carbon atoms may be a hydrocarbyl group having 1 to 15 carbon atoms or 1 to 10 carbon atoms. Specifically, the hydrocarbyl group having 1 to 20 carbon atoms is a straight-chain, branched-chain, or cyclic alkyl group such as a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, or a cyclohexyl group; Or it may be an aryl group such as a phenyl group, a naphthyl group, or anthracenyl group.

[0240]

[0241] Examples of compounds represented by the above chemical formula 3 include alkylaluminoxane compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one of these or a mixture of two or more thereof may be used.

[0242]

[0243] Among the above compounds, the cocatalyst may be, more specifically, an alkylaluminoxane cocatalyst such as methylaluminoxane.

[0244] The above alkylaluminoxane cocatalyst can further enhance catalytic activity by including a metal element that stabilizes the first and second metallocene compounds and acts as a Lewis acid to form a bond through a Lewis acid-base interaction with a functional group introduced into a bridge group of the first and second metallocene compounds.

[0245]

[0246] In addition, the amount of the cocatalyst used can be appropriately adjusted depending on the properties or effects of the desired catalyst and polyethylene. For example, when silica is used as the carrier, the cocatalyst can be supported in an amount of 100 g or more, or 500 g or more, or 750 g or more, and 5000 g or less, or 3000 g or less, or 1000 g or less, based on 1,000 g of silica.

[0247]

[0248] The hybrid metallocene catalyst according to the present invention having the above-described configuration can be produced by a production method including a step of supporting a promoter compound on a support, and a step of supporting the first and second transition metal compounds on the support. The supporting order of the promoter and the first and second transition metal compounds can be changed as needed, and the supporting order of the first and second transition metal compounds can also be changed as needed. In addition, the first and second transition metal compounds can be supported simultaneously. Considering the effect of the supported catalyst having a structure determined according to the supporting order, among these, supporting the promoter on the support and then sequentially supporting the first and second transition metal compounds can enable the produced supported catalyst to realize high catalytic activity and superior process stability in the process of producing polyethylene.

[0249]

[0250] As described above, the hybrid supported metallocene catalyst can exhibit excellent catalytic activity by including first and second metallocene compounds having specific structures. Accordingly, the hybrid supported metallocene catalyst can be suitably used for the polymerization of ethylene and olefin monomers.

[0251]

[0252] The above-mentioned hybrid supported metallocene catalyst can be dissolved or diluted and injected into an aliphatic hydrocarbon solvent having 4 to 12 carbon atoms, such as isobutane, pentane, hexane, heptane, nonane, decane, and their isomers, an aromatic hydrocarbon solvent such as toluene and benzene, a hydrocarbon solvent substituted with a chlorine atom such as dichloromethane and chlorobenzene, etc. It is preferable to use the solvent used here after removing a small amount of water or air, etc. that act as catalyst poisons, by treating it with a small amount of alkyl aluminum, and it is also possible to carry out the process using an additional cocatalyst.

[0253]

[0254] Meanwhile, the olefin monomer polymerized with ethylene may be an olefin compound having 3 to 20 carbon atoms, or 4 to 10 carbon atoms. Specific examples of the olefin monomer include 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, or 1-eicosene, and one or two or more of these may be used. More specifically, the olefin monomer may be 1-butene, 1-hexene, or 1-octene.

[0255]

[0256] The amount of the olefin monomer added as a comonomer may be determined depending on the properties of the polyethylene to be manufactured. For example, considering the properties of the polyethylene to be implemented in the present invention, the olefin monomer may be added in an amount of 3.0 to 10.0 wt% based on the total weight of ethylene. More specifically, it may be 3.0 wt% or more, or 3.5 wt% or more, or 4.0 wt% or more, or 4.3 wt% or more, or 4.5 wt% or more, and 10.0 wt% or less, or 8.0 wt% or less, or 7.5 wt% or less, or 7.3 wt% or less.

[0257]

[0258] In addition, the above polymerization reaction is performed under the condition of hydrogen input.

[0259] Specifically, the hydrogen may be introduced in an amount of 100 to 3000 ppm based on the weight of ethylene, which is a monomer. More specifically, it may be 100 ppm or more, or 500 ppm or more, or 920 ppm or more, or 1000 ppm or more, or 1300 ppm or more, and 3000 ppm or less, or 2500 ppm or less, or 2300 ppm or less, or 2100 ppm or less, or 2050 ppm or less.

[0260] When injected within the above range, it is easier to implement the properties of the polyethylene and the polyethylene resin composition containing the polyethylene.

[0261]

[0262] Additionally, the polymerization reaction can be carried out as a gas phase polymerization reaction or a slurry polymerization reaction.

[0263] Accordingly, it can be performed using a single gas phase polymerization reactor, a continuous slurry polymerization reactor, or a loop slurry reactor.

[0264]

[0265] In addition, the above polymerization reaction can be carried out at a temperature of 40°C or higher, or 60°C or higher, or 80°C or higher, and 110°C or lower, or 100°C or lower, or 90°C or lower. In addition, when the pressure conditions during the above polymerization reaction are further controlled, 5 kgf / cm 2 or more than 7 kgf / cm 2 Above, 20 kgf / cm 2 or less, or 15 kgf / cm 2 or less, or 10 kgf / cm 2 It can be performed under the following pressure. When polymerization is carried out under such temperature and pressure, the properties of the desired polyethylene and the polyethylene resin composition containing the same can be more easily achieved.

[0266]

[0267] The polyethylene resin composition according to the present invention comprises at least one type of polyethylene.

[0268] Specifically, the polyethylene resin composition may include one type of polyethylene having the same monomer type, molecular structure, crystal structure, and physical properties, or may include two or more types of polyethylene having different monomer types, molecular structures, crystal structures, and physical properties in at least one of the monomer types, molecular structures, crystal structures, and physical properties. Meanwhile, the physical properties may be density, melt index, weight-average molecular weight, number-average molecular weight, or molecular weight distribution.

[0269]

[0270] As another example, the polyethylene resin composition according to the present invention may be composed of only one type of polyethylene, or may be composed of only two or more types of polyethylene.

[0271]

[0272] As another example, the polyethylene resin composition according to the present invention may further include at least one type of antioxidant and at least one type of neutralizing agent together with at least one type of polyethylene.

[0273]

[0274] The above antioxidants include phenol-based antioxidants, phosphorus-based antioxidants, amine-based antioxidants, and sulfur compounds, and one or a mixture of two or more of these may be used.

[0275]

[0276] In addition, specific examples of the phenol-based antioxidant include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and the like, and any one or a mixture of two or more of these may be used. In addition, examples of the phosphorus-based antioxidant include tris(2,4-di-tert.-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and the like, and any one or a mixture of two or more of these may be used. In addition, examples of the amine-based antioxidant include phenylnaphthylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, and N,N'-di-2-naphthyl-p-phenylenediamine, and any one of these or a mixture of two or more thereof may be used. In addition, commercially available Irganox™ 1010 (manufactured by BASF), Irganox™ 3114 (manufactured by BASF), Irganox™ 1076 (manufactured by BASF), Irgafos™ 168 (manufactured by BASF), Irgafos™ 626 (manufactured by BASF), or Cyanox™ 1790 (manufactured by CYTEC) may also be used.

[0277]

[0278] In addition, the polyethylene resin composition may include a mixture of a phenolic primary antioxidant and a phosphorus secondary antioxidant. In this case, the phenolic primary antioxidant and the phosphorus secondary antioxidant may be included in a weight ratio of 5:1 to 1:5. More specifically, they may be included in a weight ratio of 3:1 to 1:3, or 2:1 to 1:1.

[0279]

[0280] The above antioxidant may be included in an amount of 2500 ppm or less based on the total weight of the polymerization product obtained as a result of the above polymerization reaction, specifically, polyethylene. More specifically, the antioxidant may be included in an amount of 2500 ppm or less, or 2000 ppm or less, or 1500 ppm or less, and 500 ppm or more, or 800 ppm or more, or 1000 ppm or more based on the total weight of polyethylene.

[0281]

[0282] In addition, the neutralizing agent may include a fatty acid metal salt; or hydrotalcite (magnesium aluminum hydroxy carbonate) or a similar compound thereof (hydrotalcite-like compound), and one or a mixture of two or more of these may be used.

[0283]

[0284] In the above fatty acid metal salt, the metal may be an alkaline earth metal or a transition metal. In addition, the fatty acid may be a saturated fatty acid having 13 to 36 carbon atoms, and more specifically, it may be a saturated fatty acid having 13 or more carbon atoms, or 14 or more carbon atoms, or 16 or more carbon atoms, and 36 or less, or 20 or less, or 18 or less carbon atoms. Specific examples of the fatty acid metal salt include calcium stearate (Ca-St), zinc stearate, magnesium stearate, calcium palmitate, or zinc palmitate, and any one of these or a mixture of two or more thereof may be used. In addition, commercially available DHT-4A (manufactured by KYOWA) may be used as the neutralizing agent.

[0285]

[0286] The neutralizing agent may be included in an amount of 2000 ppm or less based on the total weight of the polymerization product obtained as a result of the polymerization reaction, specifically, polyethylene. More specifically, the neutralizing agent may be included in an amount of 100 ppm or more, or 300 ppm or more, or 500 ppm or more, or 1000 ppm or more, and 2000 ppm or less, or 1500 ppm or less, or 1300 ppm or less based on the total weight of polyethylene.

[0287]

[0288] In addition, the polyethylene resin composition according to the present invention may further include one or more additives, such as a nucleating agent, a slip agent, an anti-blocking agent, a UV stabilizer, and an antistatic agent, in addition to the polyethylene, antioxidant, and neutralizing agent described above. The content of the additives is not particularly limited, and may be, for example, 500 ppm or more, or 700 ppm or more, or 1,000 ppm or more, and 2,500 ppm or less, or 1,500 ppm or less, based on the total weight of the polyethylene.

[0289]

[0290] Meanwhile, when the polyethylene resin composition according to the present invention is composed only of polyethylene, the polyethylene resin composition can be manufactured using the above-described method for manufacturing polyethylene.

[0291]

[0292] In addition, when the polyethylene resin composition according to the present invention further comprises at least one type of polyethylene, at least one type of antioxidant and neutralizer, and optionally an additive, after completion of the polymerization reaction for producing the aforementioned polyethylene, a step of adding and mixing at least one type of antioxidant and neutralizer, and optionally an additive, to the produced polymerization product may be further included.

[0293] At this time, the mixing method is not particularly limited, and a normal mixing process and mixing device can be used.

[0294]

[0295] In addition, the method for producing a polyethylene resin composition according to the present invention may further include a step of melting and extruding the resulting mixture after the mixing step.

[0296] After the polymerization reaction for the production of the above polyethylene, the polymer product is obtained in powder form. Therefore, the types of antioxidants that can be used are limited. Furthermore, the antioxidant content varies significantly from powder to powder, resulting in significant variations in the physical properties of products manufactured using the polymer. However, performing a melting and extrusion process allows the components, including the antioxidant, to be uniformly mixed, resulting in products with uniform physical properties.

[0297]

[0298] Meanwhile, in the present invention, the term "pellet" or "pellet-type" refers to small particles or pieces formed by extrusion of a raw material, and includes all shapes classified as pellets in the relevant technical field, such as circular, flat, sliver, polygonal, and rod-shaped. In addition, the size of the pellet is appropriately determined according to the use and shape and is not particularly limited. However, in order to be able to distinguish it from powder having a small average diameter of about 1 mm, the pellet in the present invention is defined as having an average diameter of 2 mm or more. Here, the "diameter" is the longest distance among any straight line distances on the outer surface of the pellet, and can be measured using an imaging microscope or the like.

[0299]

[0300] The above melt extrusion process can be performed using a conventional extruder, and the specific method and conditions are not particularly limited as long as the morphological conditions of the pellet are satisfied.

[0301]

[0302] Additionally, the above melting and extrusion process can be performed according to a conventional method. For example, it can be performed at an extrusion temperature of 180 to 220°C, or 180 to 210°C, using an extruder such as a twin screw extruder.

[0303]

[0304] A polyethylene resin composition satisfying the aforementioned physical property conditions is produced using the above-described manufacturing method. The produced polyethylene resin composition has a molecular structure with a high SCB content in the low molecular weight range, enabling the formation of a small and uniform crystal structure during the production of a stretched film. As a result, a stretched film can be produced that maintains high strength characteristics while also possessing excellent transparency and surface properties.

[0305]

[0306] Accordingly, according to the present invention, a stretched film, specifically a biaxially stretched film, is provided, which is manufactured using the above polyethylene resin composition and includes the above polyethylene resin composition.

[0307]

[0308] The above-mentioned stretch film can be manufactured according to a conventional film manufacturing method, except that the above-mentioned polyethylene resin composition is used.

[0309]

[0310] For example, a stretched film according to the present invention can be manufactured according to the following stretching conditions, and more specific film manufacturing methods and conditions are as described in the examples described below.

[0311] - Using Bruckner's lab extruder line (L / D ratio: 42, Screw diameter: 25 mm, Melt / T-Die temperature: 250 ℃), a cast sheet of the above polyethylene was manufactured with a thickness of 0.72 mm.

[0312] - Biaxial stretching was performed using a polyethylene sheet measuring 90 mm X 90 mm in length and width using KARO 5.0 equipment.

[0313] - Sequential stretching (MD→TD) was performed after preheating for 100 seconds at 120℃ each.

[0314]

[0315] The above-mentioned stretched film exhibits improved transparency and strength properties along with excellent stretchability by including the above-mentioned polyethylene resin composition.

[0316]

[0317] Specifically, when the stretched film has a thickness of 10 to 100 μm, the MD (machine direction) direction stretch ratio may be 4 to 8, or 6 to 8, and the TD (transverse direction) direction stretch ratio may be 7 to 12, or 7 to 10.

[0318]

[0319] In addition, the above-mentioned stretched film, when stretched at a stretch ratio (MD X TD) of 6X10 and has a thickness of 30μm, has a haze measured according to ISO 13468 of 10.0% or less, more specifically, less than 10.0%, or 9.0% or less, or 8.9% or less, or 5.0% or less. Since a lower haze value is better, the lower limit is not limited, but for example, it may be 1.0% or more, or 3.0% or more.

[0320]

[0321] In addition, the stretched film is stretched at a stretch ratio (MD X TD) of 6X10 and has a thickness of 30μm, and has a gloss (Gloss) measured according to ASTM D2457 of 100 GU or more, more specifically, more than 100 GU, or 110 GU or more, or 120 GU or more, or 125 GU or more, or 130 GU or more. The gloss is not limited to an upper limit because the higher the gloss, the better, but for example, it may be 200 GU or less, or 180 GU or less, or 160 GU or less.

[0322]

[0323] In addition, when the stretched film is stretched at a stretch ratio (MD X TD) of 6X10 and has a thickness of 30μm, the surface roughness measured by AFM may be 20.0nm or less, more specifically, less than 20.0nm, or 18.0nm or less, or 16.5nm or less, or 16.0nm or less. Since the surface properties are better as the surface roughness decreases, the lower limit value is not limited, but for example, it may be 1.0nm or more, or 5.0nm or more, or 7.0nm or more.

[0324]

[0325] In addition, when the stretched film is stretched at a stretch ratio (MD X TD) of 6X10 and has a thickness of 30μm, the 1% secant modulus in the MD direction measured according to ASTM D 882 is 900 MPa or more, and the 1% secant modulus in the TD direction is 1000 MPa or more. More specifically, the 1% secant modulus in the MD direction is 900 MPa or more, or 950 MPa or more, and the 1% secant modulus in the TD direction is 1000 MPa or more, or 1100 MPa or more.

[0326]

[0327] The polyethylene resin composition according to the present invention enables the formation of a small, uniform crystal structure, enabling the production of a stretched film with excellent transparency and surface properties while maintaining high strength characteristics. This enables the provision of a recyclable, single-material film that can replace conventional composite material films.

[0328]

[0329] Hereinafter, embodiments of the present invention will be described in more detail in the following examples. However, the following examples are merely illustrative of embodiments of the present invention, and the content of the present invention is not limited by the following examples.

[0330] <Preparation of metallocene compounds>

[0331] Synthesis Example 1-1: Preparation of the first metallocene compound A1

[0332] (A1)

[0333] (1) Synthesis of ligands

[0334] Under Ar, 27.2 g (100 mmol) of 3-(6-tert-butoxyhexyl)-1H-indene and 250 mL of n-hexane were added to a dried 2 L Schlenk flask. After cooling to -78 °C, 42 mL (1.05 eq., 105 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 h. After cooling again to -78 °C, 21.3 g (1.5 eq., 150 mmol) of iodomethane was added dropwise. After slowly warming to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 24.1 g (84.2 mmol, 84.2% yield) of 3-(6-tert-butoxyhexyl)-1-methyl-1H-indene.

[0335] 1H NMR (500 MHz, CDCl3): 1.12 (9H, s), 1.29 (3H, d), 1.42 (4H, m), 1.56 (2H, m), 1.70 (2H, m), 2.52 (2H, t), 3.34 (2H, t), 3.42 (1H, m), 6.25 (1H, brs), 7.21 (1H, t), 7.25-7.32 (2H, m), 7.40 (1H, d).

[0336]

[0337] (2) Synthesis of metallocene compounds

[0338] Under Ar, 5.73 g (20 mmol) of the ligand synthesized above and 70 mL of diethyl ether were added to a dried 250 mL Schlenk flask. After cooling to -78 °C, 8.4 mL (1.05 eq., 21 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 hours. After cooling again to -78 °C, 8.46 g (1.0 eq., 20 mmol) of (1-n-butyl-3-methylcyclopentadienyl)ZrCl3dimethoxyethane complex and 30 mL of diethyl ether were added. After slowly warming to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure, and dichloromethane was added. The resulting suspension was filtered under Ar to remove LiCl, the filtrate was dried under reduced pressure, and n-hexane was added. The resulting suspension was filtered under Ar to obtain 7.52 g (12.9 mmol, 64.5% yield) of metallocene compound A1 in solid form.

[0339] 1 ​H NMR (500 MHz, CDCl3): 0.77-0.81 (3H, m), 1.09 (9H, s), 1.16-1.28 (6H, m), 1.48-1.56 (6H, m), 1.95 (3H, d), 2.14 (1H, m), 2.42 (4H, m), 2.68 (1H, m), 2.90 (1H, m), 3.23 (2H, t), 4.97 (1H, dt), 5.11 (1H, dt), 5.76 (1H, t), 6.41 (1H, brs), 7.13-7.15 (2H, m), 7.46-7.48 (2H, m).

[0340]

[0341] Synthesis Example 1-2: Preparation of the first metallocene compound A2

[0342] (A2)

[0343] (1) Synthesis of ligands

[0344] Under Ar, 54.5 g (200 mmol) of 3-(6-tert-butoxyhexyl)-1H-indene and 500 mL of n-hexane were added to a dried 2 L Schlenk flask. After cooling to -78 °C, 84 mL (1.05 eq., 210 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 h. After cooling again to -78 °C, 46.8 g (1.5 eq., 300 mmol) of iodoethane was added dropwise. After slowly warming to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 43.3 g (144 mmol, 72% yield) of 3-(6-tert-butoxyhexyl)-1-ethyl-1H-indene.

[0345] 1H NMR (500 MHz, CDCl3): 0.94 (3H, t), 1.12 (9H, s), 1.29 (2H, m), 1.32-1.90 (8H, m), 2.52 (2H, t), 3.34 (2H, t), 3.45 (1H, m), 6.27 (1H, brs), 7.22 (1H, t), 7.25-7.35 (2H, m), 7.39 (1H, d).

[0346]

[0347] (2) Synthesis of metallocene compounds

[0348] Under Ar, 6.61 g (22 mmol) of the ligand synthesized above and 80 mL of diethyl ether were added to a dried 250 mL Schlenk flask. After cooling to -78 °C, 9.3 mL (1.06 eq., 23.3 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 hours. After cooling again to -78 °C, 9.00 g (1.0 eq., 22 mmol) of (n-butylcyclopentadienyl)ZrCl3dimethoxyethane complex and 30 mL of diethyl ether were added. After slowly warming to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure, and dichloromethane was added. The resulting suspension was filtered under Ar to remove LiCl, the filtrate was dried under reduced pressure, and n-hexane was added. The resulting suspension was filtered under Ar to obtain 8.10 g (13.9 mmol, 63.2% yield) of metallocene compound A2 in solid form.

[0349] 1 ​H NMR (500 MHz, CDCl3): 0.75-0.85 (3H, m), 0.87 (3H, m), 1.11 (9H, s), 1.18-1.29 (6H, m), 1.47-1.56 (6H, m), 2.16 (1H, m), 2.40-2.65 (4H, m), 2.89 (1H, m), 3.26 (2H, t), 4.96-5.94 (4H, m), 6.40 (1H, brs), 7.11-7.17 (2H, m), 7.44-7.48 (2H, m).

[0350]

[0351] Synthesis Example 1-3: Preparation of the first metallocene compound A3

[0352] (A3)

[0353] (1) Synthesis of ligands

[0354] Under Ar, 120 g (440 mmol) of 3-(6-tert-butoxyhexyl)-1H-indene and 1.1 L of n-hexane were added to a dried 2 L Schlenk flask. After cooling to -78 °C, 185 mL (1.05 eq., 462.5 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 h. After cooling again to -78 °C, 82.8 g (1.1 eq., 484 mmol) of benzyl bromide was added dropwise. After slowly warming to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 137 g (377 mmol, 85.7% yield) of 3-(6-tert-butoxyhexyl)-1-benzyl-1H-indene.

[0355] 1H NMR (500 MHz, CDCl3): 1.22 (9H, s), 1.32 (4H, m), 1.44 (2H, m), 1.57 (2H, m), 1.73 (2H, m), 2.59 (2H, m), 3.38 (2H, t), 3.75 (1H, m), 6.14 (1H, brs), 7.14-7.45 (9H, m).

[0356]

[0357] (2) Synthesis of metallocene compounds

[0358] Under Ar, 9.06 g (25 mmol) of the ligand synthesized above and 90 mL of diethyl ether were added to a dried 250 mL Schlenk flask. After cooling to -78 °C, 11 mL (1.05 eq., 27.5 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 hours. After cooling again to -78 °C, 10.6 g (1.0 eq., 25 mmol) of (1-n-butyl-3-methylcyclopentadienyl)ZrCl3dimethoxyethane complex and 30 mL of diethyl ether were added. After slowly warming to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure, and dichloromethane was added. The resulting suspension was filtered under Ar to remove LiCl, the filtrate was dried under reduced pressure, and n-hexane was added. The resulting suspension was filtered under Ar to obtain 8.76 g (13.3 mmol, 53.2% yield) of metallocene compound A3 in solid form.

[0359] 1H NMR (500 MHz, CDCl3): 0.88-0.91 (3H, m), 1.22 (9H, s), 1.29-1.40 (8H, m), 1.52-1.76 (4H, m), 2.06 (3H, s), 2.11-2.22 (2H, m), 2.59-2.68 (2H, m), 2.99-3.07 (2H, m), 3.34 (2H, t), 4.43 (1H, dt), 5.21 (1H, dt), 5.78 (1H, t), 6.47 (1H, brs), 7.11-7.63 (9H, m).

[0360]

[0361] Synthesis Example 1-4: Preparation of the first metallocene compound A6

[0362] (A6)

[0363] (1) Synthesis of ligands

[0364] Under Ar, 44.2 g (230 mmol) of 3-phenyl-1H-indene and 600 mL of tetrahydrofuran were added to a dried 2 L Schlenk flask. After cooling to -78 °C, 97 mL (1.06 eq., 243 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 h. After cooling again to -78 °C, 44.4 g (1.0 eq., 230 mmol) of 6-tert-butoxyhexyl chloride was added dropwise. After slowly warming to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 31.7 g (91.0 mmol, 39.5% yield) of 1-(6-tert-butoxyhexyl)-3-phenyl-1H-indene.

[0365] 1H NMR (500 MHz, CDCl3): 1.18 (9H, s), 1.32 (4H, m), 1.42 (2H, m), 1.55 (2H, m), 1.97 (2H, m), 3.32 (2H, t), 3.61 (1H, m), 6.66 (1H, brs), 7.08-7.50 (9H, m).

[0366]

[0367] (2) Synthesis of metallocene compounds

[0368] Under Ar, 11.5 g (33 mmol) of the ligand synthesized above and 120 mL of diethyl ether were added to a dried 250 mL Schlenk flask. After cooling to -78 °C, 13.9 mL (1.05 eq., 34.8 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 hours. After cooling again to -78 °C, 11.0 g (1.0 eq., 33 mmol) of (pentamethylcyclopentadienyl)ZrCl3 and 30 mL of diethyl ether were added. After slowly warming to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure, and dichloromethane was added. The resulting suspension was filtered under Ar to remove LiCl, the filtrate was dried under reduced pressure, and n-hexane was added. The resulting suspension was filtered under Ar to obtain 15.3 g (23.7 mmol, 71.8% yield) of metallocene compound A6 in solid form.

[0369] 1 H NMR (500 MHz, CDCl3): 1.21 (9H, s), 1.26-1.43 (4H, m), 1.55-1.71 (4H, m), 1.74 (15H, brs), 2.24 (2H, m), 3.32 (2H, t), 6.61 (1H, brs), 7.10-7.65 (9H, m).

[0370]

[0371] Synthesis Example 2: Preparation of a second metallocene compound B1

[0372] (B1)

[0373] (1) Synthesis of ligands

[0374] Under Ar, 100 g (450 mmol) of 2-(6-tert-butoxyhexyl)cyclopentadiene, 103 g (2.0 eq., 900 mmol) of 2,4-dimethyl-3-pentanone, and 1 L of ethanol were added to a dried 250 mL Schlenk flask. After cooling to 0 °C, 48.0 g (1.5 eq., 675 mmol) of pyrrolidine was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 24 h. After cooling the reaction mixture to 0 °C, 1 L of 10 vol% aq. acetic acid was added and stirred for 30 min. The organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 44.9 g (141 mmol, 31.3% yield) of 2-(6-tert-butoxyhexyl)-5-(2,4-dimethylpentan-3-ylidene)-cyclopenta-1,3-diene.

[0375] Under Ar, 1.66 g (10 mmol) of fluorene and 40 mL of tetrahydrofuran were added to another dried 250 mL Schlenk flask. After cooling to -78 °C, 4.8 mL (1.2 eq., 12 mmol) of 2.5 M n-BuLi in hexane was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 h. After cooling to -78 °C, 3.19 g (1.0 eq., 10 mmol) of 2-(6-tert-butoxyhexyl)-5-(2,4-dimethylpentan-3-ylidene)-cyclopenta-1,3-diene synthesized above was added together with 10 mL of tetrahydrofuran. After slowly warming to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried over MgSO4 to obtain 3.94 g (8.12 mmol, 81.2% yield) of ligand.

[0376] 1 H NMR (500 MHz, CDCl3): 0.87 (12H, d), 1.12 (9H, s), 1.34 (2H, m), 1.41 (2H, m), 1.46 (2H, m), 1.55 (4H, m), 2.18 (2H, t), 2.91 (2H, d), 3.36 (2H, t), 3.73 (1H, s), 6.15 (1H, t), 6.25 (1H, brs), 7.25-7.44 (4H, m), 7.55 (2H, dd), 7.90 (2H, dd).

[0377]

[0378] (2) Synthesis of metallocene compounds

[0379] ​Under Ar, 3.94 g (8.12 mmol) of the ligand synthesized above, 5 mL of methyl t-butyl ether, and 20 mL of toluene were added to a dried 250 mL Schlenk flask. After cooling to -78 °C, 7.1 mL (2.2 eq., 17.8 mmol) of a 2.5 M n-BuLi in hexane solution was added dropwise. The reaction mixture was slowly warmed to room temperature and stirred for 8 hours. After cooling to -78 °C, 23.06 g (1.0 eq., 8.12 mmol) of ZrCl4(THF) and 5 mL of methyl t-butyl ether were added. After slowly warming to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure at room temperature to remove methyl t-butyl ether. The resulting toluene suspension was filtered under Ar to remove LiCl, and the filtrate was dried under reduced pressure at 50°C and n-hexane was added. The resulting suspension was filtered under Ar to obtain 2.61 g (4.04 mmol, 49.8% yield) of a solid metallocene compound B1.

[0380] 1 H NMR (500 MHz, C6D6): 1 H NMR (500 MHz, C6D6): 0.91 (12H, d), 1.13 (9H, s), 1.15-1.38 (6H, m), 1.40-1.55 (6H, m), 3.22 (2H, t), 5.32-6.12 (3H, m), 7.20-7.32 (2H, t), 7.47-7.55 (2H, dd), 7.72 (2H, d), 7.93 (2H, t).

[0381]

[0382] <Manufacture of supported catalysts>

[0383] Manufacturing Example 1: Manufacturing of Catalyst 1

[0384] Silica (SP 952, manufactured by Grace Davision) was dehydrated and dried under vacuum at 200°C for 12 hours.

[0385] 800 g of dried silica was placed in a 20 L SUS reactor, and 6 kg of methylaluminoxane (MAO) solution (10 wt% in toluene) in toluene solution was added, and the mixture was slowly reacted with stirring at 70 ° C. for 1 hour. After completion of the reaction, the mixture was washed several times with a sufficient amount of toluene until the unreacted aluminum compound was completely removed. A solution prepared by dissolving 25.4 g of the first metallocene compound A1 and 2.8 g of the second metallocene compound B1 in toluene was sequentially added to the reactor, and the mixture was reacted with stirring at 40 ° C. for 4 hours. After washing with a sufficient amount of toluene, the mixture was vacuum-dried to obtain a hybrid supported metallocene catalyst 1 as a solid powder.

[0386]

[0387] Manufacturing Examples 2 to 6: Manufacturing of Catalysts 2 to 6

[0388] Hybrid supported metallocene catalysts 2 to 6 were each prepared in the same manner as in Preparation Example 1, except that the types and contents of metallocene compounds were used as described in Table 1 below instead of 25.4 g of the first metallocene compound A1 and 2.8 g of the second metallocene compound B1.

[0389] Meanwhile, the structures of metallocene compounds A4, A5, B2, and B3 used in Manufacturing Examples 4 and 5 are as follows.

[0390]

[0391] Manufacturing example Catalyst 1st metallocene compound 2nd metallocene compound ratio 1st metallocene compound input amount (g) 2nd metallocene compound input amount (g) Manufacturing example 1 Catalyst 1A1B11025.42.8 Manufacturing example 2 Catalyst 2A2B1724.53.9 Manufacturing example 3 Catalyst 3A3B12030.11.5 Manufacturing example 4 Catalyst 4A4B2314.66.1 Manufacturing example 5 Catalyst 5A5B3213.46.8 Manufacturing example 6 Catalyst 6A6B11529.01.9

[0392] The 'ratio' in Table 1 above means the molar ratio of the first metallocene compound to 1 mol of the second metallocene compound.

[0393]

[0394] <Manufacture of polyethylene resin composition>

[0395] Example 1-1

[0396] Polyethylene resin composition A was slurry polymerized through a polymerization process using a 100 L continuous stirred tank reactor (CSTR) in the presence of catalyst 1 prepared in the above manufacturing example 1.

[0397] Specifically, in a CSTR, a polymerization reaction was performed by continuously and constantly adding a catalyst, ethylene, hydrogen, and a comonomer under the conditions described in Table 2 below. At this time, 0.3 mM triethylaluminum (TEAL) was used as a cocatalyst at 75 mL / hr.

[0398] Based on the total weight of the polymerization product obtained as a result of the polymerization reaction, 500 ppm of Irganox™ 1010 from BASF as a primary antioxidant, 500 ppm of Irgafos™ 168 from BASF as a secondary antioxidant, and 1,000 ppm of calcium stearate (Ca-St) as a neutralizer were added and mixed, and then extruded at an extrusion temperature of 190°C using a twin screw extruder (TEK 30 MHS, manufactured by SMPLATECH CO., diameter 32 pi, L / D=40) to produce a polyethylene composition A in the form of pellets.

[0399]

[0400] Examples 1-2 to 1-5 and Comparative Examples 1-1 to 1-10

[0401] Polyethylene resin compositions were each manufactured in the same manner as in Example 1-1, except that the conditions described in Table 2 below were changed.

[0402]

[0403] Catalyst typeCatalyst input amount (ml / hr)Ethylene input amount (kg / hr)Comonomer typeComonomer input amount (ml / min)Comonomer input amount (weight%) a )Hydrogen input amount (g / hr)Hydrogen input amount (ppm) b )Temperature (℃)Pressure (kgf / cm) 2 )Example 1-1 Catalyst 150101-butene12.04.514.01400807Example 1-2 Catalyst 260101-butene12.24.515.51550807Example 1-3 Catalyst 150101-hexene16.86.813.21320807Example 1-4 Catalyst 380101-octene17.07.320.32030807Example 1-5 Catalyst 270101-hexene9.53.89.2920807Comparative Example 1-1 Catalyst 450101-butene12.54.714.21420808Comparative Example 1-2 Catalyst 450101-hexene 14.75.9 17.01700807 Comparative Example 1-3 Catalyst 455101-hexene 18.87.6 16.11610807 Comparative Example 1-4 Catalyst 470101-butene 13.04.8 11.21120806 Comparative Example 1-5 Catalyst 53010--018.01800849 Comparative Example 1-6 Catalyst 150101-octene 8.03.4 8.2820867 Comparative Example 1-7 Catalyst 250101-hexene 9.73.9 3.0300807 Comparative Example 1-8 Catalyst 680101-octene 19.28.2 23.12310809 Comparative Example 1-9 Catalyst 480 101-butene 17.36.411.81180848 Comparative Example 1-10 Catalyst 565 101-butene 14.75.98.2820828

[0404] In the above Table 2, the weight % of a represents the amount of monomer input as a percentage based on the total weight of ethylene, and the ppm of b represents the amount of hydrogen input as a million parts based on the total weight of ethylene.

[0405]

[0406] Experimental Example 1: Evaluation of Physical Properties of Polyethylene Resin Compositions

[0407] The physical properties of the polyethylene resin compositions of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-10 manufactured above were evaluated by the following method, and the results are shown in Tables 3 to 5 below.

[0408]

[0409] (1) MI 2.16

[0410] Melt Index (MI) according to ASTM D1238 (Condition E, 190 ℃, 2.16 kg load) 2.16 )(g / 10min) was measured.

[0411]

[0412] (2) Density

[0413] Density (g / cm) according to ASTM D792 3 ) was measured.

[0414]

[0415] (3) Average number of SCBs and NCD index

[0416] For the polyethylene resin compositions according to the above examples and comparative examples, the SCB content was derived as the number of short branch chains having 2 to 7 carbon atoms per 1000 carbon atoms ( / 1000C) through gel permeation chromatography (GPC) analysis and Fourier transform infrared spectroscopy (FT-IR).

[0417] Specifically, the polyethylene resin composition sample was pretreated by dissolving it in 1,2,4-trichlorobenzene containing 0.025% BHT at 160℃ for 4 hours using a GPC device, Waters PL-GPC220 (Polymer Laboratories PLgel MIX-B 300 mm length column), and then preparing a concentration of 20 mg / 10 mL, and then supplying 200 μL at a rate of 1 mL / min. At this time, the weight average molecular weights (g / mol) of the polystyrene standards were 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000, 9 types. Next, measurements were made under the following conditions using an FT-IR connected to the above GPC device.

[0418] <FT-IR 측정 기기 및 측정 조건>

[0419] Measuring instrument: PerkinElmer Spectrum 100

[0420] Measurement temperature: 160℃

[0421] Wavenumber: 2700 cm -1 3000 cm inland -1

[0422] Number of scans: 8

[0423] Resolution: 8 cm -1

[0424] Detector: DTGS

[0425] Through the above FT-IR analysis, an SCB distribution graph was derived with the logarithm value (log Mw) of the weight average molecular weight (Mw) (g / mol) as the x-axis and the number of SCBs per 1000 carbon atoms for the logarithm value as the y-axis, and 3.5 <logMw < 4.5 영역에서의 탄소 1000개당 SCB 평균 개수를 구하였다( / 1000C)).

[0426]

[0427] In addition, the number of SCBs per 1000 carbon atoms at logMw=5.5 and the number of SCBs per 1000 carbon atoms at logMw=4.5 were calculated, and then the NCD index was calculated using the following mathematical formula 1.

[0428] [Mathematical Formula 1]

[0429] NCD index = - (number of SCBs per 1000 carbons at logMw=5.5 - number of SCBs per 1000 carbons at logMw=4.5)

[0430]

[0431] (5) Crystal content according to melting temperature

[0432] Using a differential scanning calorimeter (Device name: DSC8000, Manufacturer: PerkinElmer), the polyethylene resin composition was initially heated to 160°C and then maintained for 30 minutes to remove all thermal history of the sample prior to measurement.

[0433] After the temperature was lowered from 160℃ to 122℃, it was maintained for 20 minutes, then lowered to 30℃, maintained for 1 minute, and then increased again. Next, it was heated to a temperature (117℃) that was 5℃ lower than the initial heating temperature of 122℃, maintained for 20 minutes, lowered to 30℃, maintained for 1 minute, and then increased again. In this way, the n+1th heating temperature was 5℃ lower than the nth heating temperature, and the holding time and cooling temperature were the same, while gradually lowering the heating temperature until it reached 52℃. At this time, the temperature rising and falling speeds were each controlled to 20℃ / min. Finally, the SSA thermogram was measured by observing the heat amount change while increasing the temperature at a heating rate of 10℃ / min from 30℃ to 160℃.

[0434] The peak area was quantified using the Tm and heat capacity (area) of each melting peak from the measured SSA thermogram. Specifically, the ratio (f) of the peak area at Tm less than 100℃ to the total peak area of ​​melting peaks in the entire SSA thermogram Tm<100℃ ), the ratio of peak areas where Tm is greater than 100°C and less than 120°C (f100°C <Tm<120℃), 그리고 Tm 120℃ 초과에서의 피크 면적의 비(f Tm>120℃ ) are obtained respectively, and the above f Tm<100℃ value and f Tm>120℃ From the value f Tm<100℃ / f Tm>120℃ was saved.

[0435]

[0436]

[0437]

[0438]

[0439]

[0440]

[0441]

[0442] As a result of the experiment, the polyethylene resin composition of the example had an SCB content in the low molecular weight region and f Tm<100 ℃ was higher than that of the comparative example. Accordingly, it can be expected that the formation of a small and uniform crystal structure is possible during the production of a stretched film, and as a result, the transparency and surface properties of the stretched film can be improved.

[0443]

[0444] <Manufacturing of Stretch Film>

[0445] Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-10

[0446] Biaxially stretched films of examples and comparative examples were manufactured under the following conditions. In this case, the biaxially stretched films of comparative examples 2-1 and 2-5 to 2-7 could not be preheated and stretched under conditions of 120 to 127°C.

[0447] (1) Manufacturing of biaxially stretched film

[0448] - Using Bruckner's lab extruder line (L / D ratio: 42, Screw diameter: 25 mm, Melt / T-Die temperature: 250 ℃), a cast sheet of the above polyethylene was manufactured with a thickness of 0.72 mm.

[0449] - Biaxial stretching was performed using a polyethylene sheet measuring 90 mm X 90 mm in length and width using KARO 5.0 equipment.

[0450] - Sequential stretching (MD→TD) was performed after preheating for 100 seconds at 120℃ each.

[0451] - When extended, the speed is 300% / s.

[0452] - Final film thickness (based on a stretching ratio of 6X10): 30㎛

[0453]

[0454] Experimental Example 2: Film Property Evaluation

[0455] The physical properties of the biaxially stretched films of the examples and comparative examples manufactured above were evaluated using the following methods, and the results are shown in Tables 6 and 7.

[0456] (1) Transparency

[0457] Haze of biaxially oriented films was measured according to ISO 13468.

[0458]

[0459] (2) Gloss

[0460] The gloss of the biaxially oriented film was measured according to ASTM D2457.

[0461]

[0462] (3) 1% secant modulus

[0463] The 1% secant modulus of the film MD and TD directions was measured according to ASTM D882.

[0464]

[0465] (4) Surface roughness

[0466] The biaxially oriented film manufactured above was cut into 20 nm x 20 nm pieces to manufacture each sample, and the surface roughness of the biaxially oriented film was measured using an atomic force microscope (AFM). The measurements were performed three times using the same method and the average value was expressed.

[0467]

[0468]

[0469]

[0470]

[0471]

[0472] Experimental results showed that the SCB content was high in the low molecular weight region, and f Tm<100 ℃ The biaxially oriented film of the example including the high polyethylene resin composition exhibited significantly improved transparency and surface properties while maintaining excellent film strength properties compared to the comparative example.

Claims

Contains 1.1 or more types of polyethylene, A polyethylene resin composition satisfying the following conditions (i) to (v): (i) Density measured according to ASTM D792: 0.940 g / cm3 or greater; (ii) Melt index: 0.50 to 3.00 g / 10 min when measured under a load of 2.16 kg at 190°C according to ASTM D1238; (iii) Average number of SCBs per 1000 carbons in the region 3.5 < logMw < 4.5: 3.0 to 15.0 (iv) NCD index calculated according to the following mathematical formula 1: greater than 0 [Mathematical Formula 1] NCD index = - (number of SCBs per 1000 carbons at logMw=5.5 - number of SCBs per 1000 carbons at logMw=4.5) In the above mathematical formula 1, Mw means the weight average molecular weight of the polyethylene resin composition, and SCB means a short branch chain having 2 to 7 carbon atoms bonded to the main chain of polyethylene. (v) When the relative ratio of peak areas according to melting temperature (Tm) was measured using the SSA (successive self-nucleation and annealing) analysis method, the ratio of peak areas with Tm less than 100℃ to the total peak area was f Tm<100 ℃ and the ratio of peak areas at Tm exceeding 120℃ f Tm>120 ℃ When you say, f Tm<100℃ is greater than 0.100, and f Tm<100℃ / f Tm>120 ℃ 0.100 to 0.

300.

2. In paragraph 1, When the relative ratio of peak areas according to melting temperature (Tm) was measured using the successive self-nucleation and annealing (SSA) analysis method, the ratio of peak areas with Tm exceeding 100°C and less than 120°C to the total peak area (f100°C) <Tm<120℃)가 0.150 내지 0.350인, Polyethylene resin composition.

3. In paragraph 1, When the relative ratio of peak areas according to melting temperature (Tm) was measured using the successive self-nucleation and annealing (SSA) analysis method, the ratio of peak areas above Tm 120℃ to the total peak area (f Tm>120 ℃ ) is 0.500 to 0.800, Polyethylene resin composition.

4. In paragraph 1, The above polyethylene is an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, or an ethylene / 1-octene copolymer. Polyethylene resin composition.

5. In paragraph 1, The above polyethylene resin composition further comprises at least one of an antioxidant and a neutralizer. Polyethylene resin composition.

6. A biaxially oriented film comprising a polyethylene resin composition according to paragraph 1.

7. In paragraph 6, The above stretched film has a MD (machine direction) direction stretch ratio of 4 to 8 and a TD (transverse direction) direction stretch ratio of 7 to 12 when the thickness is 10 to 100 μm. Biaxially oriented film.

8. In paragraph 6, The above stretched film is stretched at a stretch ratio (MD X TD) of 6X10 times and has a thickness of 30μm, and has a haze of 10.0% or less measured according to ISO 13468. Biaxially oriented film.

9. In paragraph 6, The above biaxially stretched film is stretched at a stretch ratio (MD X TD) of 6X10 times and has a thickness of 30μm, and has a gloss of 100 GU or more measured according to ASTM D2457. Biaxially oriented film.

10. In paragraph 6, The above biaxially stretched film is stretched at a stretching ratio (MD X TD) of 6X10 times and has a thickness of 30 μm, and has a surface roughness of 20.0 nm or less. Biaxially oriented film.

11. In paragraph 6, The above biaxially oriented film, when stretched at a stretch ratio (MD X TD) of 6X10 times and has a thickness of 30 μm, has a 1% secant modulus in the MD direction of 900 MPa or more and a 1% secant modulus in the TD direction of 1000 MPa or more, as measured according to ASTM D882. Biaxially oriented film.

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