Polyethylene resin composition and film comprising same

Abstract

The present invention relates to a polyethylene resin composition capable of producing a film having excellent drawing process stability, and excellent transparency and mechanical properties during drawing, and a drawn film produced using same.

Description

Polyethylene resin composition and film containing the same

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

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0190237 filed on December 18, 2024, and all contents disclosed in said document are incorporated herein as part of this specification.

[0003] The present invention relates to a polyethylene resin composition and a stretched film comprising the same.

[0004] With the recent increase in consumer interest in the environment, single-material packaging that is easy to recycle is gaining attention. Notably, the food packaging and distribution industries are trending toward manufacturing "All-PE" films using only polyethylene (PE), a general-purpose material.

[0005] Conventional multilayer film packaging materials have used composite materials in which BOPP (bi-axially oriented polypropylene), BOPET (biaxially-oriented polyethylene terephthalate), or BOPA (biaxially-oriented polyamide) are applied to the printing layer. However, since these composite materials are not recyclable, research and development are underway to manufacture single-material packaging films by replacing the printing layer film with PE. To replace the printing layer film with PE, higher physical properties and transparency than existing PE blown films are required.

[0006] Meanwhile, biaxially oriented polyethylene (BOPE) film is manufactured by stretching a cast sheet in the machine direction (MD) and transverse direction (TD), respectively, and has significantly superior tensile strength, impact strength, and transparency compared to conventional blown films.

[0007] Conventional development of resins for BOPE has focused on linear low-density polyethylene (LLDPE), which has excellent stretchability due to its low density. However, when manufacturing BOPE films with LLDPE, there are problems such as severe shrinkage and poor heat resistance, making it difficult to apply to printing layers. In addition, while high-density polyethylene (HDPE) has excellent physical properties, it has problems such as high crystallinity, making it difficult to stretch, and low transparency of the film.

[0008] Accordingly, there is a need to develop a high-density polyethylene resin composition capable of simultaneously securing transparency and processability, as well as the physical properties of the stretched film.

[0009] One objective of the present invention is to provide a polyethylene resin composition that has excellent mechanical properties, such as surface elasticity modulus and tensile strength, and also high transparency when manufactured into a film.

[0010] Another objective of the present invention is to provide a stretched film comprising the above-described polyethylene resin composition that has excellent mechanical properties, such as surface elastic modulus and tensile strength, and also has high transparency.

[0011] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0012] According to one embodiment of the present invention, the invention relates to a polyethylene resin composition comprising an ethylene homopolymer or an ethylene / alpha olefin copolymer having 3 to 20 carbon atoms, satisfying the following conditions (i) to (v):

[0013] (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater;

[0014] (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min; and

[0015] (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20;

[0016] (iv) haze less than 15% as measured according to ISO 13468; and

[0017] (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃.

[0018] The conditions of (iv) and (v) above are based on a film made of the composition, for example, a stretched film with a thickness of about 20±5μm.

[0019] The above density is 0.940 g / cm³ 3 Above 0.970 g / cm³ 3 It could be.

[0020] The above melt index (MI) 2.16 ) can be 1.00 to 2.00 g / 10 min.

[0021] The above haze may be 13% or less.

[0022] The above surface modulus may be 1.2 GPa or more and 2.0 GPa or less.

[0023] When the above polyethylene resin composition is manufactured into a film, the gloss may be 63 GU or higher and 200 GU or lower.

[0024] According to another embodiment of the present invention, the invention relates to a cast sheet comprising the polyethylene resin composition described above.

[0025] According to another embodiment of the present invention, the invention relates to a stretched film comprising the polyethylene resin composition described above. Herein, the stretched film may comprise both a uniaxially stretched film and a biaxially stretched film.

[0026] According to another embodiment of the present invention, the invention relates to a biaxially stretched film comprising a polyethylene resin composition comprising an ethylene homopolymer or an ethylene / alpha-olefin copolymer having 3 to 20 carbon atoms, satisfying the conditions of (i) to (v) below:

[0027] (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater;

[0028] (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min; and

[0029] (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20;

[0030] (iv) haze less than 15% as measured according to ISO 13468; and

[0031] (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃.

[0032] The above density is 0.940 g / cm³ 3 Above 0.970 g / cm³ 3 It could be.

[0033] The above melt index (MI) 2.16 ) can be 1.00 to 2.00 g / 10 min.

[0034] The above haze may be 13% or less.

[0035] The above surface modulus may be 1.2 GPa or more and 2.0 GPa or less.

[0036] The gloss of the above film may be 63 GU or more and 200 GU or less.

[0037] The thickness of the above biaxially stretched film may be 10 to 100 μm.

[0038] The polyethylene resin composition of the present invention not only exhibits excellent stretchability, but the film produced therefrom, particularly the stretched film, also possesses a balanced combination of excellent mechanical properties such as surface modulus and tensile strength, as well as transparency (i.e., appearance characteristics). Therefore, the aforementioned film can be utilized as a packaging material for various applications, and because it is easy to recycle, it is suitable as a single material to replace existing functional multilayer films.

[0039] Unless otherwise defined in this specification, all technical and scientific terms are used merely to describe exemplary embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the presence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

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

[0041] The technical terms used in this specification are intended merely to refer to specific embodiments and are not intended to limit the invention. Furthermore, the singular forms used herein include plural forms unless the phrases clearly indicate otherwise.

[0042] In this specification, the terms “polyethylene” or “ethylene (co)polymer” include both ethylene homopolymers and / or copolymers of ethylene and alpha-olefins.

[0043] In addition, throughout this specification, the term “polyethylene resin composition” is a concept that includes all resin compositions comprising the ethylene (co)polymer, or resin compositions in which additives, generally belonging to the technical field to which the present invention belongs, may be further added to such homopolymers or copolymers.

[0044] According to one embodiment of the present invention, a polyethylene resin composition satisfying the conditions (i) to (v) below is provided:

[0045] (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater;

[0046] (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min; and

[0047] (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20;

[0048] (iv) haze less than 15% as measured according to ISO 13468; and

[0049] (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃.

[0050] The above polyethylene composition has a density of 0.940 g / cm³ 3 Above 0.970 g / cm³ 3 The following applies. The density of the above polyethylene resin composition affects the stiffness of the stretched film. The density of the polyethylene resin composition is 0.940 g / cm³ 3 If it is less than, there is a risk that the stiffness of the stretched film will decrease, and 0.970 g / cm² 3If it exceeds, the stretchability of the film may be reduced due to the excessively high density. Preferably, the density of the polyethylene resin composition is 0.941 g / cm³ 3 Above, 0.942 g / cm³ 3 Above, 0.943 g / cm³ 3 Above, 0.944 g / cm³ 3 Above, or 0.945 g / cm³ 3 Above, 0.970 g / cm³ 3 Below, 0.965 g / cm³ 3 Below, 0.964 g / cm³ 3 Below, 0.963 g / cm³ 3 Below, 0.960 g / cm³ 3 Below, 0.958 g / cm³ 3 Below, 0.955 g / cm³ 3 Below, 0.953 g / cm³ 3 Less than, or 0.950 g / cm³ 3 It may be less than.

[0051] The above density (g / cm³) 3 ) can be measured according to ASTM D792 standards, for example, and may be a value measured at 23 ℃.

[0052] In addition, the polyethylene resin composition has a high density as described above, along with a melt index (MI 2.16 ) may be 0.50 to 3.00 g / 10 min. Melt index (MI) of the polyethylene resin composition 2.16 ) may be related to film processability and dimensional stability during the manufacture of stretched films. The above melt index (MI 2.16 If ) is less than 0.50 g / 10min, the processing pressure increases, leading to reduced processability, and if it exceeds 3.00 g / 10min, bubble stability deteriorates due to high fluidity, which may result in variations in film thickness. The melt index (MI) of the above polyethylene resin composition 2.16) may be 0.50 g / 10min or more, or 0.80 g / 10min or more, or 1.00 g / 10min or more, or 1.20 g / 10min or more, or 1.25 g / 10min or more, or 1.30 g / 10min or more, and 3.00 g / 10min or less, or 2.50 g / 10min or less, or 2.00 g / 10min or less, or 1.80 g / 10min or less, or 1.65 g / 10min or less, or 1.60 g / 10min or less. Specific examples include 0.50 to 3.00 g / 10min, 1.00 to 3.00 g / 10min, 1.00 to 2.50 g / 10min, or 1.00 to 2.00 g / 10min.

[0053] The above melt index (MI) 2.16 ) can be measured at 190°C under a 2.16 kg load according to ASTM D1238 standards and can be expressed as the weight (g) of the polymer melted over 10 minutes.

[0054] The molecular weight distribution (Mw / Mn, MWD) of the above polyethylene resin composition may be 5 or more, 5.5 or more, 6 or more, 6.5 or more, 7 or more, 7.5 or more, 8 or more, 8.5 or more, 9 or more, or 10 or more, and less than 20, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11.5 or less, 11 or less, or 10.5 or less. Specifically, the molecular weight distribution (Mw / Mn, MWD) of the above polyethylene composition may be 5 or more and less than 20, 6 or more and 18 or less, 6 or more and 16 or less, 6 or more and 14 or less, 6 or more and 12 or less, 6.5 or more and 18 or less, 6.5 or more and 16 or less, 6.5 or more and 14 or less, or 6.5 or more and 12 or less.

[0055] The aforementioned molecular weight distribution is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the polyethylene resin composition, and is also referred to as the polydispersity index or PDI. The molecular weight distribution (MWD) of the polyethylene resin composition may be related to film processability, mechanical strength, and impact resistance during the manufacture of stretched films. If the molecular weight distribution falls outside the aforementioned range, it may be difficult to achieve the desired stretchability or mechanical properties.

[0056] The above molecular weight distribution can be calculated by measuring the weight-average molecular weight (Mw) and the number-average molecular weight (Mn). In this case, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) may be converted values ​​for standard polystyrene measured using gel permeation chromatography (GPC).

[0057] Conventional high-density polyethylene (HDPE) resins have excellent physical properties, but they have problems such as high crystallinity making stretching difficult and low film transparency. The polyethylene resin composition of the present invention, when manufactured into a film, possesses a crystal structure of controlled size, thereby exhibiting excellent mechanical strength, such as a high surface modulus, and can also have high transparency.

[0058] The surface modulus of a film is an indirect indicator of the size of crystals present on the surface. The larger the size of the polymer crystals formed within the film, the higher the surface modulus. Assuming the internal haze of the film is similar, the surface modulus is proportional to the haze. In other words, the larger the surface modulus, the more opaque the film becomes.

[0059] As described above, the polyethylene resin composition according to the present invention can have both high surface modulus and low haze characteristics in balance as it has crystals of controlled size when manufactured into a film.

[0060] The numerical ranges for haze and surface modulus, additionally gloss and tensile strength below are based on the polyethylene resin composition being manufactured into a film having a thickness in the range of about 20 to 40 μm, in particular a stretched film. Preferably, it may be based on the composition being manufactured into a stretched film having a thickness of about 20 ± 5 μm.

[0061] Specifically, the haze may be less than 15%, 14.5% or less, 14% or less, 13.5% or less, 13% or less, 12.5% ​​or less, 12% or less, 11.5% or less, 11% or less, 10.5% or less, or 10% or less. Since a lower haze value is better, the lower limit is not specifically limited, but, for example, it may be 0.5% or more or 1% or more.

[0062] The above haze can be measured according to ISO 13468 standards.

[0063] The above surface modulus may be 1.2 GPa or more, 1.25 GPa or more, 1.3 GPa or more, 1.4 GPa or more, or 1.5 GPa or more, and may be 2.0 GPa or less, 1.9 GPa or less, 1.8 GPa or less, 1.7 GPa or less, or 1.6 GPa or less, and specifically, may be 1.2 GPa or more and 2.0 GPa or less, 1.2 GPa or more and 1.8 GPa or less, or 1.2 GPa or more and 1.7 GPa or less.

[0064] The above surface modulus can be measured using the indentation method. Specifically, after preparing a stretched film with dimensions of 40 mm x 40 mm and a thickness of approximately 20 ± 5 μm, a modulus profile analysis according to the film indentation depth is performed in Sinus mode using a nano indenter (HM-2000; Helmut Fischer). The surface of the film is indented at a temperature of 25 ± 5 ℃ using the Vickers triangular tip of the nano indenter, with a maximum applied load of 1 mN and a maximum indentation depth of 1 μm. However, in Sinus mode, the Sinus frequency is 10 Hz, Sinus amplitude is 0.1 mN, and Constant strain rate is 0.1 sec. -1 It is set to this. In the modulus profile graph according to depth obtained from the above analysis, the Y-intercept value was obtained by performing linear fitting on the section connecting the point with an x-axis value of 0.4 μm and the point with an x-axis value of 0.7 μm. The surface modulus for the corresponding film is represented as the average value of the Y-intercept values ​​obtained after performing the above analysis at any three points on the specimen.

[0065] Generally, in polyethylene stretched films, transparency improves as the size of surface crystals decreases, but the mechanical properties of the film may deteriorate; conversely, in the case of films with excellent mechanical properties, unnecessary wavy patterns may form on the surface or gloss may decrease during actual stretching. However, a film manufactured from the polyethylene resin composition according to the present invention simultaneously satisfies a balance of properties including high surface modulus and high transparency, thereby possessing excellent durability, abrasion resistance, and scratch resistance, as well as superior appearance characteristics. In the case of the film, if either the haze or the surface modulus falls outside the aforementioned range, it may be difficult to expect such effects.

[0066] Additionally, based on the above-mentioned film standards, the gloss may be 60 GU or more, 63 GU or more, 65 GU or more, 70 GU or more, 75 GU or more, 77 GU or more, 78 GU or more, 79 GU or more, or 80 GU or more, and specifically, it may be 60 GU or more and 200 GU or less, or 63 GU or more and 200 GU or less. Since a higher gloss is superior, the upper limit is not specifically limited, but for example, it may be 200 GU or less, or 180 GU or less.

[0067] The above glossiness can be measured at a 60° measurement angle according to ASTM D2457 standards.

[0068] In addition, based on the film, the tensile strength in the transverse direction (TD) may be 70 MPa or more, 80 MPa or more, 90 MPa or more, 100 MPa or more, 110 MPa or more, 130 MPa or more, or 150 MPa or more, and 220 MPa or less. In addition, the tensile strength in the machine direction (MD) may be 30 MPa or more, 35 MPa or more, 40 MPa or more, 50 MPa or more, 60 MPa or more, 70 MPa or more, or 80 MPa or more, and 150 MPa or less, or 130 MPa or less.

[0069] The above-mentioned tensile strength can be measured according to ASTM D 882 standards.

[0070] The polyethylene resin composition according to the present invention also has excellent stretchability.

[0071] The resin composition described above can be uniaxially or biaxially stretched with a stretching ratio of 4 to 8 times in the length (MD) direction or 5 to 10 times in the width (TD) direction.

[0072] As an example, the resin composition described above can be biaxially stretched with a stretching ratio of 4 to 8 times in the length (MD) direction and 7 to 10 times in the width (TD) direction.

[0073] As another example, the resin composition described above can be biaxially stretched with a stretching ratio of 5 times in the length (MD) direction and 8 times in the width (TD) direction.

[0074] In this specification, "excellent stretchability" or "stretchable" means that when a sheet made of the above-described polyethylene resin composition is uniaxially stretched or biaxially stretched at the corresponding stretching ratio, no breakage, melting, shrinkage, or melt drawing occurs in the film. Furthermore, it may mean that the average thickness of the stretched film is greater than 14 μm, greater than 15 μm, greater than 16 μm, greater than 17 μm, greater than 18 μm, greater than 19 μm, or greater than 20 μm, and the thickness deviation is less than 5 μm, less than 4 μm, less than 3 μm, or less than 2.5 μm, but is not limited thereto. Alternatively, the average thickness of the stretched film may be 1.5% or more, 1.6% or more, 1.7% or more, 1.8% or more, 1.9% or more, or 2.0% or more of the average thickness of the sheet before stretching.

[0075] The average thickness and standard deviation of the film described in this specification are the average and standard deviation values ​​of thickness values ​​measured at 20 or more non-overlapping points on a stretched film (e.g., a stretched film with dimensions of 210 mm in width and 297 mm in length). The thickness measurement method may be performed using a thickness gauge, but may also be measured by other methods known in the art to which the present invention belongs.

[0076] In the polyethylene resin composition according to the present invention, the polyethylene may be an ethylene homopolymer or an ethylene / alpha olefin copolymer having 3 to 20 carbon atoms. More specifically, the copolymer may be an ethylene / alpha olefin copolymer having 4 to 10 carbon atoms, and specific examples may be an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, or a mixture of two or more of these, but are not limited thereto.

[0077] The above-described polyethylene resin composition can be prepared by polymerizing ethylene by introducing hydrogen gas in the presence of a catalyst, or by copolymerizing ethylene with a comonomer.

[0078] The above comonomer may be an olefin monomer. The olefin monomer may be an olefin compound having 3 to 20 carbon atoms or 4 to 10 carbon atoms. Specific examples 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-eicocene, and any one or more of these may be used. More specifically, the above olefin monomer may be 1-butene, 1-hexene, or 1-octene, but is not limited thereto.

[0079] The amount of the above comonomer added may be determined according to the physical properties of the polyethylene to be manufactured, but considering the physical properties of the polyethylene to be realized in the present invention, it may be added in an amount of 3.0 to 10.0 weight% based on the total weight of ethylene. More specifically, it may be 3.0 weight% or more, 3.5 weight% or more, 4.0 weight% or more, 4.3 weight% or more, or 4.5 weight% or more, and 10.0 weight% or less, 9.0 weight% or less, 8.0 weight% or less, 7.5 weight% or less, or 7.3 weight% or less.

[0080] In addition, the polymerization reaction is carried out under conditions of hydrogen input. The amount of hydrogen input may be determined according to the physical properties of the polyethylene to be manufactured, but considering the physical properties of the polyethylene to be realized in the present invention, it may be input at an amount of 100 ppm or more, 500 ppm or more, 1000 ppm or more, or 1300 ppm or more based on the weight of the monomer ethylene, and 3000 ppm or less, 2500 ppm or less, 2300 ppm or less, 2100 ppm or less, or 2050 ppm or less. Specifically, it may be input in an amount of 100 to 3000 ppm, 500 to 3000 ppm, or 1000 to 3000 ppm.

[0081] The above polymerization reaction may be carried out at a temperature of 40°C or higher, or 60°C or higher, or 80°C or higher, and 110°C or lower, or 100°C or lower, or 90°C or lower.

[0082] In addition, when controlling the pressure conditions during the above polymerization reaction, 5 kgf / cm 2 Above, or 7 kgf / cm² 2 This is the limit, and 20 kgf / cm² 2 Less than or equal to 15 kgf / cm² 2 Less than or equal to 10 kgf / cm² 2 It can be performed under the following pressure.

[0083] When the polymerization reaction is carried out under the above-mentioned temperature and pressure conditions, the desired physical properties of the polyethylene resin composition can be achieved more easily.

[0084] The above polymerization reaction may be carried out in the presence of a catalyst. In this case, the catalyst may be a Ziegler-Natta catalyst, a metallocene catalyst, or a mixture thereof, but is not limited thereto. Preferably, a metallocene catalyst may be used.

[0085] The metallocene catalyst may include one or more of a first metallocene compound selected from compounds represented by the following chemical formula 1; and a second metallocene compound selected from compounds represented by the following chemical formula 2. Preferably, it may include one or more first metallocene compounds selected from compounds represented by the following chemical formula 1 and one or more second metallocene compounds selected from compounds represented by the following chemical formula 2.

[0086] [Chemical Formula 1]

[0087]

[0088] In the above chemical formula 1,

[0089] M1 is a group 4 transition metal, and

[0090] X 11 and X 12 Each independently, substituted or unsubstituted C 1-20 It is an alkyl or halogen, and

[0091] R1 to R5 and R7 to R 12 Each independently contains hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted, or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 And,

[0092] R6 is substituted or unsubstituted C 1-20 Alkyl, substituted, or unsubstituted C 6-60 Aryl, or -(CH2) n1 -OR 13 However,

[0093] R1 to R 12 At least one of them is -(CH2) n1 -OR 13 And,

[0094] R 13 is substituted or unsubstituted C 1-20 It is an alkyl,

[0095] n1 is an integer from 0 to 10.

[0096] [Chemical Formula 2]

[0097]

[0098] In the above chemical formula 2,

[0099] M2 is a group 4 transition metal, and

[0100] X 21 and X 22 Each independently, substituted or unsubstituted C 1-20 It is an alkyl or halogen, and

[0101] T2 is C (carbon) or Si (silicon), and

[0102] Q 21 and Q 22 C, each independently substituted or unsubstituted 1-20 Alkyl, substituted, or unsubstituted C 6-60 Aryl, or -(CH2) n2 -OR 32 Or, Q 21 and Q 22 C that combines with each other to become substituted or non-substituted 3-20 Forming a cycloalkyl ring,

[0103] R 20 to R 31 Each independently contains hydrogen, substituted or unsubstituted C 1-20 Alkyl, substituted, or unsubstituted C 6-60 Aryl, or -(CH2) n2 -OR 32 Or, R 20 to R 31 Among them, two adjacent C's are combined to form a substituted or unsubstituted C' 3-20 Forms a cycloalkyl ring,

[0104] R 20 to R 31 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 And,

[0105] R 32is substituted or unsubstituted C 1-20 It is alkyl, and

[0106] n2 is an integer from 0 to 10.

[0107] In the present invention, the substituents of the above chemical formula are described in more detail as follows.

[0108] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0109] The above C 1-20 The alkyl group may be a straight-chain, branched-chain, or cyclic alkyl group. Specifically, the above C 1-20 The alkyl group 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, etc.

[0110] 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 can be a cyclopropene ring, a cyclobutene ring, a cyclopentene ring, or a cyclohexene ring, etc.

[0111] C 2-20 The alkenyl can be a straight-chain, branched-chain, or cyclic alkenyl. Specifically, the above C 2-20The alkenyl of 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 of may be ethenyl, propenyl, butenyl, fentenyl, or cyclohexanyl, etc.

[0112] C 1-20 The alkoxy group may be a straight-chain, branched-chain, or cyclic alkoxy group. Specifically, the above C 1-20 The alkoxy group 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 cyclohexoxy group, etc.

[0113] C 2-20 Alkoxyalkyl is -R y -OR z A structure containing alkyl(-R y One or more hydrogens of ) are alkoxy(-OR z It may be a substituent substituted with ). Specifically, the above carbon atoms C2 to C 20 The alkoxyalkyl group may be a methoxymethyl group, methoxyethyl group, ethoxymethyl group, iso-propoxymethyl group, iso-propoxyethyl group, iso-propoxyhexyl group, tert-butoxymethyl group, tert-butoxyethyl group, or tert-butoxyhexyl group, etc.

[0114] C6-60 Aryl may refer to monocyclic, bicyclic, or tricyclic aromatic hydrocarbons. Specifically, the C6 to C 60 The aryl group can be a phenyl group, a naphthyl group, or anthracenyl group, etc.

[0115] C 7-20 Alkylaryl may refer to a substituent in which one or more hydrogens of an aryl are substituted by an alkyl group. Specifically, the above C 7-20 The alkylaryl of may be methylphenyl, ethylphenyl, n-propylphenyl, iso-propylphenyl, n-butylphenyl, iso-butylphenyl, tert-butylphenyl, or cyclohexylphenyl, etc.

[0116] C 7-20 Arylalkyl may refer to a substituent in which one or more hydrogens of an alkyl group are substituted by an aryl group. Specifically, the above C 7-20 The arylalkyl group can be a benzyl group, phenylpropyl or phenylhexyl, etc.

[0117] In addition, group 4 transition metals may include titanium, zirconium, hafnium, etc.

[0118] The above metallocene catalyst may be a hybrid catalyst comprising a first metallocene compound of high molecular weight and high crystallinity and a second metallocene compound of low molecular weight and low crystallinity.

[0119] In copolymerization in a single reactor using a hybrid metallocene catalyst, it is important to control the expression of polymerization characteristics between the metallocene compounds constituting the hybrid metallocene catalyst under a single copolymerization condition. In particular, to obtain a polyethylene polymer for biaxial stretching, high molecular weight, highly crystalline components and low molecular weight, low-crystalline components must be composed together. The polyethylene copolymer of the present invention can express each characteristic under a single polymerization condition by using a hybrid metallocene catalyst obtained from a combination of the first metallocene compound and the second metallocene compound.

[0120] The first metallocene compound represented by Chemical Formula 1 above has the characteristic of having 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, high molecular weight, highly crystalline polyethylene can be produced under ethylene / 1-hexene copolymerization conditions.

[0121] Meanwhile, the second metallocene compound represented by Chemical Formula 2 has the characteristic of having a high polymerization rate of the comonomer and a low polymerization rate of the ethylene monomer compared to the first metallocene compound due to the bridge-type ligand structure bonded to the central metal. As a result, low molecular weight, low-crystallinity polyethylene can be produced under ethylene / 1-hexene copolymerization conditions.

[0122] Preferably, the central metal (M1) of Formula 1 may be a group 4 transition metal specifically Ti, Zr, or Hf, and more specifically Hf or Zr.

[0123] Preferably, X 11 , X 12 Each can independently be methyl or chloro, and more preferably X 11 , X 12 All of them may be methyl or all of them may be chloro.

[0124] Preferably, R1 to R5 and R7 to R 12 Each independently contains 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 1-20 Alkyl, substituted, or unsubstituted C 6-20 Aryl, or -(CH2) n1 -OR 13 However, R1 to R 12 One or two of them are -(CH 2)n1 -OR13 It could be.

[0125] Preferably, either R7 or R8 is -(CH2) n1 -OR 13 While, the remainder and R1 to R5 and R9 to R 12 Each independently contains 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.

[0126] Preferably, R1 to R5 are each independently hydrogen, methyl, isopropyl, n-butyl, phenyl, or -(CH2) n1 -OR 13 It may be. More preferably, R1 to R5 may each independently be hydrogen, methyl, n-butyl, phenyl, or tert-butoxyhexyl.

[0127] Preferably, R6 is unsubstituted or C 6-10 C substituted with aryl or Si(R')3 1-20 alkyl, or C 6-20 It could be Aril, and here R' is C 1-20 alkyl or C 6-10 It may be an aryl. More preferably, R6 is unsubstituted or C substituted with phenyl, trimethylsilyl, or triphenylsilyl. 1-20 alkyl, or C 6-20 It may be an aryl. Most preferably, R6 may be methyl, ethyl, isopropyl, benzyl, trimethylsilylmethyl, or phenyl.

[0128] Preferably, either R7 or R8 is -(CH2) n1 -OR 13 While being, the remainder and R9 to R 12Each may be hydrogen. More preferably, either R7 or R8 is tertbutoxyhexyl, and the remainder and R9 to R 12 Each can be hydrogen.

[0129] Preferably, R 13 It can be tertbutyl.

[0130] Preferably, n1 can be an integer from 4 to 10, more preferably, n1 can be an integer from 4 to 7, and most preferably, n1 can be 6.

[0131] Preferably, the first metallocene compound represented by the above formula 1 may be any one selected from the group consisting of the following:

[0132]

[0133] Meanwhile, the method for preparing the first metallocene compound represented by the above chemical formula 1 is not particularly limited, but, for example, it can be prepared by the method shown in the following reaction formula 1.

[0134] Although the compound represented by the above chemical formula 1 is difficult to synthesize due to the steric hindrance of the indene ligand, the compound of the above chemical formula 1 can be prepared with high yield and high purity according to a method such as the following reaction scheme 1.

[0135] Accordingly, according to one embodiment of the present invention, the compound represented by Formula 1 may be prepared by a manufacturing method comprising: a step of preparing a ligand of Formula 1-3 by reacting a compound represented by Formula 1-1 with a compound represented by Formula 1-2; and a step of reacting the ligand of Formula 1-3, a compound represented by Formula 1-4, and a halogen salt of a transition metal represented by Formula 1-5:

[0136] [Reaction Equation 1]

[0137]

[0138] In the above reaction scheme 1, M1, X11 , X 12 and R1 to R 12 is as defined in Chemical Formula 1 above, and X' is independently a halogen.

[0139] Preferably, the central metal (M2) of Formula 2 may be a group 4 transition metal such as Ti, Zr, or Hf, and more specifically, Zr.

[0140] Preferably, X 21 , X 22 Each can independently be methyl or chloro, and more preferably X 21 , X 22 Each can be chloro.

[0141] Preferably, T2 can be C (carbon).

[0142] Preferably, R 20 to R 31 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 It can be. More preferably, R 20 to R 25 , Q 21 and Q 22 At least one of them is -(CH2) n2 -OR 32 It can be. More preferably, R 20 to R 31 , Q 21 and Q 22 One or two of them are -(CH2) n2 -OR 32 It can be. More preferably, R 20 to R 25 , Q 21 and Q 22 One or two of them are -(CH2) n2 -OR 32 It can be. Most preferably, R 20 to R 25 , Q 21 and Q22 Either one or two of them may be tertbutoxyhexyl.

[0143] Preferably, Q 21 and Q 22 C, each independently substituted or unsubstituted 1-20 Alkyl, substituted, or unsubstituted C 6-20 Aryl, or -(CH2) n2 -OR 32 Or, Q 21 and Q 22 C that combines with each other to be substituted or unsubstituted 3-20 It can form a cycloalkyl ring. More preferably, Q 21 and Q 22 are independently methyl, ethyl, isopropyl, phenyl, or -(CH2) n2 -OR 32 Or, Q 21 and Q 22 They can combine with each other to form a cyclopentene ring or a cyclohexene ring.

[0144] Preferably, R 20 to R 23 Each independently, hydrogen, C 1-20 Alkyl, C 6-20 Aryl, or -(CH2) n2 -OR 32 It can be, and more preferably, R 20 to R 23 Each can independently be hydrogen, methyl, n-butyl, phenyl, or tertbutoxyhexyl. More preferably, R 20 to R 23 One is tertbutoxyhexyl or n-butyl, and the rest are hydrogen, or R 20 to R 23 Two of them may each independently be methyl, n-butyl, or phenyl, and the remainder may be hydrogen.

[0145] Preferably, R 24 to R 31 Each independently, hydrogen, C 1-10Alkyl, C 6-20 Aryl, or -(CH2) n2 -OR 32 Or, R 24 to R 31 Among them, two adjacent C's are combined to form a substituted or unsubstituted C' 3-10 It can form a cycloalkyl ring. More preferably, R 24 to R 31 Each is independently hydrogen, tertbutyl, or tertbutoxyhexyl, or R 24 to R 31 Two adjacent ones can combine to form a cyclohexane ring substituted with four methyl groups.

[0146] Preferably, R 32 It could be tertbutyl.

[0147] Preferably, n2 can be an integer from 4 to 10, more preferably, n2 can be an integer from 4 to 7, and most preferably, n2 can be 6.

[0148] Preferably, the metallocene compound represented by Formula 2 may be any one selected from the group consisting of the following:

[0149]

[0150] Meanwhile, the method for preparing the second metallocene compound represented by the above chemical formula 2 is not particularly limited, but, for example, it can be prepared by the method shown in reaction formula 2 below.

[0151] Although the compound represented by the above chemical formula 2 is difficult to synthesize due to the steric hindrance of the indene ligand, the compound of the above chemical formula 2 can be prepared with high yield and high purity according to a method such as the following reaction scheme 2.

[0152] Accordingly, according to one embodiment of the present invention, the compound represented by Formula 2 may be prepared by a method comprising the steps of: reacting a compound represented by Formula 2-1 with a compound represented by Formula 2-2 to produce a compound represented by Formula 2-3; reacting a compound represented by Formula 2-3 with a compound represented by Formula 2-4 to produce a ligand of Formula 2-5; and reacting the ligand of Formula 2-5 with a halogen salt of a transition metal represented by Formula 2-6.

[0153] [Reaction Equation 2]

[0154]

[0155] In the above reaction scheme 2,

[0156] M2, X 21 , X 22 , T2, Q 21 , Q 22 and R 20 to R 31 is as defined in the above chemical formula 2, and X" is independently a halogen.

[0157] In the above-described hybrid metallocene catalyst, the first metallocene compound and the second metallocene compound may be included in a molar ratio of 1:1 to 25:1, 2:1 to 25:1, 3:1 to 25:1, 3:1 to 23:1, or 3:1 to 20:1. If the ratio of the first metallocene compound to the second metallocene compound is less than 1:1, the high crystal content is low, making it difficult for the stretched film to have heat resistance; and if the ratio of the first metallocene compound to the second metallocene compound exceeds 25:1, the low crystal content is low, making biaxial stretching processability difficult.

[0158] The above metallocene catalyst may be a metallocene supported catalyst comprising a carrier that supports a metallocene compound. As the carrier, a carrier containing hydroxyl groups on its surface may be used, and preferably, a carrier having highly reactive hydroxyl groups, silanol groups, or siloxane groups on its surface may be used. For this purpose, a carrier that has been surface-modified by calcination or has had moisture removed from its surface by drying may be used.

[0159] For example, silica prepared by calcining silica gel, silica dried at high temperatures, silica-alumina, and silica-magnesia may be used, and these may typically contain oxide, carbonate, sulfate, and nitrate components such as Na2O, K2CO3, BaSO4, and Mg(NO3)2.

[0160] When used in the above supported catalyst state, the particle shape and bulk density of the polymer produced are excellent, and it can be used in conventional slurry polymerization, bulk polymerization, or gas phase polymerization processes. In addition, among the various supports, since the functional groups of the transition metal compound are chemically bonded and supported on the silica support, there is almost no catalyst released from the surface of the support during the ethylene polymerization process, and as a result, fouling caused by the reactor walls or polymer particles sticking together can be minimized when producing polyethylene copolymers by slurry or gas phase polymerization.

[0161] The above-mentioned carrier may have an average particle size (D50) of 20 to 60 μm. When having the above-mentioned particle size, transition metal compounds can be supported with superior efficiency, and as a result, catalytic activity can be increased. More specifically, it may be 20 μm or more, or 25 μm or more, and 60 μm or less, or 50 μm or less.

[0162] Meanwhile, the average particle size (D50) of the above carrier refers to the particle size at the 50% point of the cumulative distribution of the number of particles according to particle size (particle diameter). The above D50 can be measured using the laser diffraction method. Specifically, the carrier to be measured is dispersed in a dispersion medium such as deionized water, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500). The particle size distribution is calculated by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. The particle size at the point that is 50% of the cumulative distribution of the number of particles according to particle size in the measuring device is calculated and used as the average particle size.

[0163] In addition, when supported on the above-mentioned carrier, the metallocene compound may be supported in a content range of 1 mmol or more, 10 mmol or more, 15 mmol or more, 20 mmol or more, 25 mmol or more, or 30 mmol or more, based on 1,000 g of the carrier, and 500 mmol or less, 400 mmol or less, 300 mmol or less, 200 mmol or less, 100 mmol or less, 80 mmol or less, 60 mmol or less, or 52.5 mmol or less. When the metallocene compound includes both the first metallocene compound and the second metallocene compound, each compound may be supported in the above-mentioned content. When supported in the above content range, appropriate supported catalyst activity is exhibited, which may be advantageous in terms of maintaining catalyst activity and economic efficiency.

[0164] In addition, the metallocene catalyst may further include a co-catalyst to improve high activity and process stability.

[0165] Specifically, the above co-catalyst may include one or more of the compounds represented by the following chemical formula 3.

[0166] [Chemical Formula 3]

[0167] -[Al(R 41)-O] a -

[0168] In the above chemical formula 3,

[0169] R 41 is a halogen; or C substituted or unsubstituted with a halogen 1-20 It is hydrocarbil;

[0170] a is an integer greater than or equal to 2.

[0171] Meanwhile, in this specification, the hydrocarbyl group is a monovalent functional group in which a hydrogen atom has been removed from a hydrocarbon, and may include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, aralkyl groups, aralkenyl groups, aralkinyl groups, alkylaryl groups, alkenylaryl groups, and alkynylaryl groups, etc. Furthermore, 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.

[0172] Examples of compounds represented by the above chemical formula 3 include alkylaluminoxane compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and any one or more of these may be used.

[0173] Among the compounds mentioned above, the co-catalyst may be, more specifically, an alkylaluminoxan-based co-catalyst such as methylaluminoxan.

[0174] The above alkylaluminoxane-based co-catalyst 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 Lewis acid-base interaction with the functional group introduced into the bridge group of the first and second metallocene compounds.

[0175] In addition, the amount of the above co-catalyst used can be appropriately adjusted according to the physical properties or effects of the desired catalyst and polyethylene copolymer. For example, when silica is used as the carrier, the above co-catalyst can be supported in an amount of 100g or more, 1000g or more, or 2000g or more, and 6000g or less, or 5500g or less, or 5400g or less, based on 1000g of silica.

[0176] A hybrid metallocene catalyst according to the present invention having the above-described composition can be manufactured by a manufacturing method comprising the steps of: supporting a co-catalyst compound on a carrier; and supporting the first and second metallocene compounds on the carrier. In this case, the order of supporting the co-catalyst and the first and second metallocene compounds may be changed as needed, and the order of supporting the first and second metallocene compounds may also be changed as needed. The first and second metallocene compounds may be supported simultaneously. Considering the effect of the supported catalyst with a structure determined by the order of support, among these, sequentially supporting the first and second metallocene compounds after supporting the co-catalyst on the carrier allows the manufactured supported catalyst to achieve superior process stability along with high catalytic activity in the manufacturing process of polyethylene copolymers.

[0177] As described above, the hybrid supported metallocene catalyst can exhibit excellent catalytic activity by including first and second metallocene compounds having a specific structure. Accordingly, the hybrid supported metallocene catalyst can be suitably used for the polymerization of ethylene and olefin monomers.

[0178] In addition, the polymerization reaction may be carried out as a gas phase polymerization reaction or a slurry polymerization reaction. Accordingly, it may be carried out using a single gas phase polymerization reactor, a continuous slurry polymerization reactor, or a loop slurry reactor.

[0179] Meanwhile, the method for manufacturing a polyethylene resin composition according to the present invention may further include a step of adding and mixing one or more of an antioxidant and a neutralizing agent to the polymerization product manufactured after the completion of the polymerization reaction described above. In addition, the manufacturing method may further include a step of melting and extruding the resulting mixture after the mixing step.

[0180] Examples of the above antioxidants include phenolic antioxidants; phosphorus-based antioxidants; amine-based antioxidants or sulfur compounds, and any one or more of these may be used.

[0181] In addition, specific examples of the above-mentioned phenolic antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and any one or more of these may be used. In addition, examples of phosphorus-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and any one or more of these may be used. In addition, the above-mentioned amine-based antioxidants may include phenylnaphthylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, and N,N'-di-2-naphthyl-p-phenylenediamine, and any one or a mixture of two or more of these may be used. Also, commercially available Irganox TM 1010 (BASF), Irganox TM 3114 (BASF), Irganox TM 1076 (BASF manufactured), Irgafos TM 168 (BASF), Irgafos TM 626 (BASF) or Cyanox TM You can also use 1790 (manufactured by CYTEC), etc.

[0182] In addition, the polyethylene resin composition may include a mixture of a phenolic primary antioxidant and a phosphorus-based secondary antioxidant. In this case, the phenolic primary antioxidant and the phosphorus-based 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.

[0183] 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 polymerization reaction, specifically polyethylene. More specifically, the above antioxidant may be included in an amount of 2500 ppm or less, or 2000 ppm or less, or 1500 ppm or less based on the total weight of the polyethylene, or in an amount of 500 ppm or more, or 800 ppm or more, or 1000 ppm or more.

[0184] In addition, the above neutralizing agent may include fatty acid metal salts; or hydrotalcite (magnesium aluminum hydroxy carbonate) or a similar compound thereof (hydrotalcite-like compound), and any one or more of these may be used.

[0185] In the above fatty acid metal salt, the metal may be an alkaline earth metal or a transition metal. In addition, the above 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, or 36 or fewer carbon atoms, or 20 or fewer carbon atoms, or 18 or fewer carbon atoms. Specific examples of the above fatty acid metal salt include calcium stearate (Ca-St), zinc stearate, magnesium stearate, calcium palmitate, or zinc palmitate, and any one or more of these may be used. In addition, commercially available DHT-4A (manufactured by KYOWA), etc., may be used as the above neutralizing agent.

[0186] The above neutralizing agent may be included in an amount of 2000 ppm or less based on the total weight of the polyethylene, specifically the polymerization product obtained as a result of the above polymerization reaction. More specifically, the above 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 the polyethylene.

[0187] Meanwhile, 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 for example, each may be 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.

[0188] At this time, the mixing method is not particularly limited, and conventional mixing processes and mixing devices may be used.

[0189] Since the polymerization product obtained after the polymerization reaction for the production of the above-mentioned polyethylene is in powder form, the types of usable antioxidants are limited, and because the antioxidant content varies significantly depending on the powder, there is a large variation in the physical properties of articles manufactured using this. However, when a melting and extrusion process is performed, the constituent components, including the antioxidants, are uniformly mixed, and the resulting articles can possess uniform physical properties.

[0190] Meanwhile, in the present invention, a pellet or pellet-type refers to a small particle or piece formed by the extrusion of a raw material, and includes all forms classified as pellets in the relevant technical field, such as circular, flat, slab-shaped, polygonal, and rod-shaped forms. Furthermore, the size of the pellet is not particularly limited and is appropriately determined according to the use and shape; however, in order to distinguish it from powders having a small average diameter of typically 1 mm, the pellet in the present invention is defined as having an average diameter of 2 mm or more. At this time, "diameter" is the longest straight distance among any straight distances on the outer surface of the pellet, and can be measured using an imaging microscope or the like.

[0191] The above melt extrusion process can be performed using a conventional extruder, and as long as the morphological conditions of the pellets are satisfied, the specific method and conditions are not particularly limited.

[0192] In addition, the melting and extrusion processes can be performed according to conventional methods. For example, using an extruder such as a twin screw extruder, the process can be performed at an extrusion temperature of 180 to 220 ℃ or 180 to 210 ℃.

[0193] A polyethylene resin composition satisfying the aforementioned physical property conditions is manufactured by the above-described manufacturing method. The manufactured polyethylene resin composition can form a small and uniform crystalline structure upon stretching, and the stretched film can be produced as a stretched film having excellent transparency and surface properties while maintaining high strength characteristics.

[0194] According to another embodiment of the present invention, the invention relates to an unoriented sheet comprising the polyethylene resin composition described above.

[0195] The thickness of the above sheet may be 0.1 to 5 mm, 0.1 to 3 mm, 0.1 to 2 mm, 0.5 to 2 mm, or 0.5 to 1 mm, but can be appropriately adjusted according to the application of the polyethylene resin composition or according to the stretching conditions to be subsequently performed on the above sheet.

[0196] The above-mentioned unoriented sheet may be a cast sheet manufactured by a casting process. For example, it may be manufactured by maintaining the cylinder temperature of a T-die extrusion laminator capable of melt extrusion at 150 to 230 ℃ and the T-die temperature at 200 to 280 ℃ and extruding the molten resin, but is not limited thereto.

[0197] According to another embodiment of the present invention, the invention relates to a stretched film comprising the polyethylene resin composition described above.

[0198] The above-mentioned stretched film comprises a polyethylene resin composition according to the present invention, and may be obtained by stretching a sheet comprising the polyethylene resin composition provided in the present invention.

[0199] The stretched film of the present invention satisfies all of the conditions (i) to (v) below. Such a stretched film has excellent stretchability, along with enhanced transparency, surface modulus of elasticity, and furthermore, high tensile strength.

[0200] (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater;

[0201] (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min;

[0202] (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20;

[0203] (iv) haze less than 15% as measured according to ISO 13468; and

[0204] (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃.

[0205] The haze of the above film may be less than 15%, 14.5% or less, 14% or less, 13.5% or less, 13% or less, 12.5% ​​or less, 12% or less, 11.5% or less, 11% or less, 10.5% or less, or 10% or less. Since a lower haze value is better, the lower limit is not specifically limited, but, for example, it may be 0.5% or more or 1% or more.

[0206] The surface modulus of the above film may be 1.2 GPa or more, 1.25 GPa or more, 1.3 GPa or more, 1.4 GPa or more, or 1.5 GPa or more, and may be 2.0 GPa or less, 1.9 GPa or less, 1.8 GPa or less, 1.7 GPa or less, or 1.6 GPa or less, and specifically, may be 1.2 GPa or more and 2.0 GPa or less, 1.2 GPa or more and 1.8 GPa or less, or 1.2 GPa or more and 1.7 GPa or less.

[0207] The gloss of the above film may be 60 GU or more, 65 GU or more, 70 GU or more, 75 GU or more, 77 GU or more, 78 GU or more, 79 GU or more, or 80 GU or more. Since a higher gloss is superior, there is no specific upper limit, but for example, it may be 200 GU or less, or 180 GU or less.

[0208] In addition, the film may have a tensile strength in the width direction (TD) of 70 MPa or more, 80 MPa or more, 90 MPa or more, 100 MPa or more, 110 MPa or more, 130 MPa or more, or 150 MPa or more, and 220 MPa or less. In addition, the tensile strength in the length direction (MD) may be 30 MPa or more, 35 MPa or more, 40 MPa or more, 50 MPa or more, 60 MPa or more, 70 MPa or more, or 80 MPa or more, and 150 MPa or less, or 130 MPa or less.

[0209] The stretched film may be a uniaxially stretched or biaxially stretched film. The stretched film may be a sheet that has been uniaxially stretched or biaxially stretched with a stretching ratio of 4 to 8 times in the length (MD) direction or 5 to 10 times in the width (TD) direction.

[0210] As an example, the above-mentioned stretched film may be a sheet that has been biaxially stretched with a stretching ratio of 4 to 8 times in the length (MD) direction and 7 to 10 times in the width (TD) direction.

[0211] As another example, the above-mentioned stretched film may be a sheet that has been biaxially stretched with a stretching ratio of 5 times in the length (MD) direction and 8 times in the width (TD) direction.

[0212] The thickness of the stretched film may be a value measured at 10 to 100 μm, for example, 14 to 95 μm, 20 to 95 μm, or 30 to 90 μm, or 40 to 85 μm.

[0213] However, the above haze and surface modulus are based on the thickness of the stretched film being 20±5㎛.

[0214] The above-mentioned stretched film has high thickness smoothness, and may mean that the average thickness is greater than 14 μm, 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, or 20 μm or more, and 100 μm or less, and the thickness deviation is 5 μm or less, 4 μm or less, 3 μm or less, or 2.5 μm or less, but is not limited thereto.

[0215] In addition, the above-mentioned stretched film with high thickness smoothness has an average thickness greater than 14 μm, and the smoothness, which is the percentage of the standard deviation of the average thickness value, may be 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less, and may be 0.001% or more considering actual process limitations.

[0216] The average thickness and standard deviation of the above-mentioned stretched film may be the average and standard deviation values ​​of thickness measurements taken at 20 or more non-overlapping points of the stretched film (e.g., with dimensions of 210 mm in width and 297 mm in length). The thickness measurement method may be performed using a thickness gauge, but may be measured by other methods known in the art to which the present invention belongs.

[0217] The above-described stretched film may have a Young's Modulus in the MD direction measured according to ASTM D882-07 of 300 MPa or more, 400 MPa or more, 500 MPa or more, 600 MPa or more, or 700 MPa or more, and may be 1000 MPa or less, 950 MPa or less, 900 MPa or less, 800 MPa or less, or 700 MPa or less. Specifically, the Young's Modulus in the MD direction may be 300 MPa or more and 1000 MPa or less, 400 MPa or more and 1000 MPa or less, or 500 MPa or more and 1000 MPa or less, but is not limited thereto.

[0218] The above-mentioned stretched film may have a tensile modulus in the MD direction measured according to ASTM D 882 of 300 MPa or more, 500 MPa or more, 700 MPa or more, 900 MPa or more, 1000 MPa or more, or 1100 MPa or more. However, in terms of simultaneously achieving excellent stretchability and transparency of the final film, it may be 3000 MPa or less, 2500 MPa or less, 2000 MPa or less, 1500 MPa or less, 1400 MPa or less, 1300 MPa or less, or 1200 MPa or less.

[0219] In addition, the stretched film may have a tensile modulus in the TD direction measured according to ASTM D 882 of 300 MPa or more, 500 MPa or more, 700 MPa or more, 900 MPa or more, 1000 MPa or more, 1100 MPa or more, or 1200 MPa or more. However, in terms of simultaneously achieving excellent stretchability and transparency of the final film, it may be 3000 MPa or less, 2500 MPa or less, 2000 MPa or less, 1900 MPa or less, 1800 MPa or less, or 1700 MPa or less.

[0220] The polyethylene stretched film produced in the present invention can be highly advantageously applied as a packaging material for various products, such as product bags, food bags, food and special packaging, and industrial liners.

[0221] The present invention will be explained in detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following examples.

[0222] <Example>

[0223] Preparation of Metallocene Compounds

[0224] Synthesis Example 1: Preparation of Metallocene Compound A1

[0225]

[0226] 1. Synthesis of ligands

[0227] 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 heated to room temperature and stirred for 8 hours. After cooling again to -78 °C, 21.3 g (1.5 eq., 150 mmol) of iodomethane was added dropwise. After slowly raising the temperature to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried with MgSO4 to obtain 24.1 g of 3-(6-tert-butoxyhexyl)-1-methyl-1H-indene (84.2 mmol, 84.2% yield).

[0228] 1 H 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).

[0229] 2. Synthesis of Metallocene Compounds

[0230] 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 heated 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)ZrCl3 dimethoxyethane complex was added along with 30 mL of diethyl ether. After slowly heating 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 solid metallocene compound A1.

[0231] 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).

[0232] Synthesis Example 2: Preparation of Metallocene Compound B1

[0233]

[0234] 1. Synthesis of ligands

[0235] 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 heated to room temperature and stirred for 24 hours. After cooling the reaction mixture to 0 °C, 1 L of 10 vol% aq. acetic acid was added and stirred for 30 minutes. The organic layer was separated using water and diethyl ether and dried with 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.

[0236] Under Ar, 1.66 g (10 mmol) of fluorene and 40 mL of tetrahydrofuran were added to another dry 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 heated to room temperature and stirred for 8 hours. After cooling to -78 °C, 3.19 g (1.0 eq., 10 mmol) of the 2-(6-tert-butoxyhexyl)-5-(2,4-dimethylpentan-3-ylidene)-cyclopenta-1,3-diene synthesized above was added along with 10 mL of tetrahydrofuran. After slowly raising the temperature to room temperature and stirring for 24 hours, the organic layer was separated using water and diethyl ether and dried with MgSO4 to obtain 3.94 g of ligand (8.12 mmol, 81.2% yield).

[0237] 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).

[0238] 2. Synthesis of Metallocene Compounds

[0239] 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 2.5 M n-BuLi in hexane solution was added dropwise. The reaction mixture was slowly heated 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) was added along with 5 mL of methyl t-butyl ether. After slowly heating to room temperature and stirring for 24 hours, the reaction mixture was dried under reduced pressure at room temperature to remove the methyl t-butyl ether. The generated toluene suspension was filtered under Ar to remove LiCl, the filtrate was dried under reduced pressure at 50 °C, and n-hexane was added. The generated suspension was filtered under Ar to obtain 2.61 g (4.04 mmol, 49.8% yield) of solid metallocene compound B1.

[0240] 1 ¹H 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).

[0241] Preparation of Hybrid Supported Metallocene Catalysts

[0242] Preparation Example 1: Preparation of Hybrid Supported Metallocene Catalyst 1

[0243] Silica (SP 952, manufactured by Grace Davision) was dehydrated and dried under vacuum at a temperature of 200°C for 12 hours.

[0244] 800 g of dried silica was placed in a 20 L SUS reactor, and 6 kg of methylaluminoxan (MAO) solution (10 wt% in toluene) was added to the toluene solution and reacted slowly with stirring at 70 °C for 1 hour. After the reaction was complete, the unreacted aluminum compound was washed several times with a sufficient amount of toluene until it was completely removed. A solution prepared by dissolving 25.4 g of metallocene compound A1 and 2.8 g of metallocene compound B1 (moles of metallocene compound 1 / moles of metallocene compound 2 = 10) in toluene was sequentially added to the reactor, and the reaction was carried out with stirring at 40 °C for 4 hours. After washing with a sufficient amount of toluene, the mixture was vacuum dried to obtain hybrid supported metallocene catalyst 1 as a solid powder.

[0245] <Preparation of Polyethylene Resin Composition>

[0246] Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4

[0247] A polyethylene composition was slurry polymerized using a bimodal polymerization process with two 100L continuous stirred tank reactors (CSTRs) in the presence of the hybrid supported catalyst 1 prepared in the above catalyst preparation example 1. Specifically, a first polyethylene product was polymerized in the first reactor at a polymerization temperature of 80°C or higher in the presence of ethylene, the catalyst, hydrogen, and a comonomer as shown in Table 1 below. In the second reactor, a second polyethylene was polymerized at a polymerization temperature of 75°C under the comonomer input conditions shown in Table 2 below, wherein the polyethylene product polymerized in the first reactor was fed into the second reactor connected in series and mixed with the second polyethylene product to produce a polyethylene resin having a bimodal structure.

[0248] Based on the total weight of the polymerization product obtained as a result of the secondary polymerization reaction, 200 ppm of BASF’s Irganox 1010 as a primary antioxidant, 400 ppm of BASF’s Irgafos 168 as a secondary antioxidant, and 500 ppm of calcium stearate (Ca-St) or DHT4A as a neutralizing agent were added and mixed, and then extruded at an extrusion temperature of 190 ℃ using a twin screw extruder (TEK 30 MHS, manufactured by SMPLATECH CO., diameter 32 phi, L / D=40) to produce a polyethylene composition in the form of pellets.

[0249] Classification 1 Reactor 1 Ethylene Catalyst Comonomer 1 Hydrogen Temperature Pressure Reactor Melting Index [kg / hr][ml / hr][ml / min][g / hr][℃][bar] MI 2.16 [g / 10min] Example 1-18705(1-butene) 6.5826.8350 Example 1-28705(1-butene) 7.0826.8400 Example 1-38705(1-hexene) 6.0826.8320 Example 1-48705(1-butene) 3.0825.0150 Example 1-58705(1-hexene) 3.0825.2130 Comparative Example 1-18705(1-butene) 6.5826.8350 Comparative Example 1-28705(1-hexene) 6.0826.8320 Comparative Example 1-38705(1-Octene) 4.0826.9210 Comparative Example 1-487007.0827.2450

[0250] Classification Reactor 2 Ethylene Catalyst Comonomer 2 Hydrogen Temperature Pressure Reactor Melting Index [kg / hr][ml / hr][ml / min][g / hr][℃][bar] MI 2.16[g / 10min] Example 1-16.53 02(1-Octene)0752.54.0 Example 1-26.53 02(1-hexene)0752.53.7 Example 1-373 001.5752.34.4 Example 1-482 02(1-Octene)0753.33.2 Example 1-583 02(1-Octene)1.0753.04.3 Comparative Example 1-1825 00752.21.6 Comparative Example 1-27.525 00752.22.0 Comparative Example 1-36.53 02.0753.53.2 Comparative Example 1-482 000752.02.1

[0251]

[0252] Experimental Example 1: Evaluation of Physical Properties of Polyethylene Resin Composition

[0253] The physical properties of the polyethylene resin compositions of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 prepared were evaluated in the following manner, and the results are shown in Table 3 below.

[0254] 1. Melt Index (MI) 2.16 )

[0255] Melting Index (MI) 2.16 ) was measured according to ASTM D1238 (condition E, 190 ℃, 2.16 kg load).

[0256] 2. Density (g / cm³) 3 )

[0257] Density (g / cm³) according to ASTM D 792 3 ) was measured.

[0258] 3. Molecular weight distribution

[0259] Molecular weight (Mw, Mn) and molecular weight distribution

[0260] The polyethylene resin compositions according to the above examples and comparative examples were analyzed by gel permeation chromatography (GPC) to measure the weight-average molecular weight (Mw) and number-average molecular weight (Mn), respectively, and the molecular weight distribution (Mw / Mn; MWD) was obtained by dividing the weight-average molecular weight measured above by the number-average molecular weight. Specifically, the measurement samples were measured using a Waters PL-GPC220 instrument with a Polymer Laboratories PLgel MIX-B 300 mm long column. The measurement temperature was 160 ℃, 1,2,4-trichlorobenzene was used as the solvent, and the flow rate was measured at 1 mL / min. Polyethylene resin composition samples were pretreated by melting in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160°C for 10 hours using a GPC analyzer PL-GP220, prepared at a concentration of 10 mg / 10 mL, and supplied in an amount of 200 μL. The values ​​of Mw and Mn were measured using a calibration curve formed using polystyrene standards. Nine types of polystyrene standards with molecular weights of 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000 were used.

[0261] Classification MI 2.16 Density (g / 10 min) (g / cm³) 3 Molecular Weight Distribution (MWD) Example 1-1 1.3 20.9 48 10.4 Example 1-2 1.3 70.9 45 9.1 Example 1-3 1.4 30.9 41 8.0 Example 1-4 1.3 80.9 48 8.6 Example 1-5 1.4 20.9 45 6.6 Comparative Example 1-1 0.9 00.9 54 14.1 Comparative Example 1-2 1.0 70.9 53 20.6 Comparative Example 1-3 2.1 00.9 34 3.0 Comparative Example 1-4 1.2 70.9 70 12.6

[0262] As shown in Table 3 above, the polyethylene resin composition according to the present invention has a density of 0.940 g / cm³3 A composition comprising the above high-density polyethylene resin, wherein the melt index (MI 2.16 It can be seen that the molecular weight distribution (MWD) is 0.50 to 3.00 g / 10 min and is 5 or more and less than 20.

[0263] Manufacture of Stretched Film

[0264] Examples 2-1 to 2-5, and Comparative Examples 2-1 to 2-5

[0265] Biaxially stretched films were prepared according to the following conditions using the polyethylene resin compositions of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 prepared above. However, the resin compositions of Comparative Examples 1-1 and 1-4 could not be manufactured into films because fracture occurred during biaxial stretching.

[0266] - A cast sheet of the above polyethylene was first manufactured using a Bruckner lab extruder line (L / D ratio: 42, Screw diameter: 25 mm, Melt / T-Die temperature: 250 ℃, thickness: 0.72 mm).

[0267] - Using KARO 5.0 equipment, biaxial stretching was performed on a polyethylene sheet with dimensions of 90 mm x 90 mm.

[0268] - After preheating for 100 seconds at 128 ℃, sequential biaxial stretching was performed with a stretching ratio of 5x in the MD direction and 8x in the TD direction. The stretching speed was 300% / s.

[0269] - The final film thickness (based on a stretch ratio of 5x8) was approximately 20㎛.

[0270] Experimental Example 2: Evaluation of Film Properties

[0271] The physical properties of the biaxially stretched films of the examples and comparative examples prepared above were evaluated in the following manner, and the results are shown in Table 4.

[0272] 1. Transparency

[0273] The haze of the biaxially stretched film was measured according to ISO 13468.

[0274] 2. Gloss

[0275] The glossiness of the biaxially stretched film was measured at a measurement angle of 60° according to ASTM D2457.

[0276] 3. Surface modulus

[0277] The stretched film was trimmed to dimensions of 40 mm x 40 mm. The film's depth modulus profile was analyzed in Sinus mode using a nano indenter (HM-2000; Helmut Fischer) at a temperature of 25 ± 5 ℃. The film surface was indented using the Vickers triangular tip of the nano indenter with a maximum applied load of 1 mN and a maximum indentation depth of 1 µm; the Sinus mode was configured with a sinus frequency of 10 Hz, sinus amplitude of 0.1 mN, and constant strain rate of 0.1 sec. -1 It was set as follows. Through the above analysis, a modulus profile graph according to depth was obtained. Linear fitting was performed within the region where the modulus stabilizes in the graph to obtain the Y-intercept value. The above analysis was repeated for three arbitrary points on the film, and the average value of the Y-intercept values ​​obtained for each point was taken as the surface modulus (GPa) value of the corresponding film.

[0278] Classification MI 2.16 Density (g / 10 min) (g / cm³) 3Molecular Weight Distribution (MWD) Haze (%) Gloss (GU) Surface Modulus (GPa) Example 2-1 1.32 0.948 10.41 2.978 8.3 1.525 Example 2-2 1.37 0.945 9.11 0.775 1.565 Example 2-3 1.43 0.941 8.01 1.378 1.213 Example 2-4 1.38 0.948 8.61 0.779 1.523 Example 2-5 1.4 20.9 45 6.6 11.8 6 3.6 1.2 9 2 Comparative Example 2-10.9 0 0.9 5 4 14.1 --- Comparative Example 2-21.0 7 0.9 5 3 20.6 16 16 22.2 7 0 Comparative Example 2-32.1 0 0.9 3 4 3.0 6.4 1 3 20.9 2 7 Comparative Example 2-41.2 7 0.9 7 12.6 ---

[0279] As shown in Table 4 above, all polyethylene resin compositions according to the present invention could be stretched into films with a thickness of approximately 20 μm without fracture or melt drawing, indicating excellent stretchability. Furthermore, the films of Examples 2-1 to 2-5, prepared using the polyethylene resin compositions according to the present invention, exhibited excellent characteristics in terms of balanced transparency and surface modulus, with a haze of less than 15% and a surface modulus of 1.2 GPa or higher and 2.0 GPa or lower. Moreover, the gloss of the film was also excellent, at 63 GU or higher.

[0280] However, in the case of Comparative Examples 2-1 and 2-4, fracture occurred, making biaxial stretching impossible. In the case of Comparative Examples 2-2 and 2-3, stretching was possible, but the film of Comparative Example 2-2 had a surface modulus of 2.270 GPa and a haze of 16.1%, indicating very poor transparency. The film of Comparative Example 2-3 had a low haze of 6.4%, but it was observed that the surface modulus was only 0.927 GPa.

[0281] Through the above-mentioned experiment, the high density (0.940 g / cm³) according to the present invention 3Above) It was observed that the polyethylene resin composition not only exhibits excellent stretchability, but the biaxially stretched film produced therefrom also has excellent appearance characteristics (transparency and gloss) and simultaneously possesses excellent mechanical properties (surface modulus).

[0282] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

A polyethylene resin composition comprising an ethylene homopolymer or an ethylene / alpha-olefin copolymer having 3 to 20 carbon atoms, satisfying the conditions of (i) to (v) below: (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater; (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min; and (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20; When manufactured into a film, (iv) haze less than 15% as measured according to ISO 13468; and (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃. In paragraph 1, The above density is 0.940 g / cm³ 3 Above 0.970 g / cm³ 3 And, the above melt index (MI) 2.16 A polyethylene resin composition having a content of 1.00 to 2.00 g / 10 min. In paragraph 1, A polyethylene resin composition having a haze of 13% or less. In paragraph 1, A polyethylene resin composition having a surface modulus of 1.2 GPa or more and 2.0 GPa or less. In paragraph 1, The above polyethylene resin composition is a polyethylene resin composition having a gloss of 63 GU or more and 200 GU or less when manufactured into a film. A cast sheet comprising a polyethylene resin composition according to any one of claims 1 to 5. A stretched film comprising a polyethylene resin composition according to any one of claims 1 to 5. A biaxially stretched film comprising a polyethylene resin composition comprising an ethylene homopolymer or an ethylene / alpha-olefin copolymer having 3 to 20 carbon atoms, satisfying the conditions of (i) to (v) below: (i) Density measured according to ASTM D792: 0.940 g / cm³ or greater; (ii) Melt index (MI) measured at 190 ℃ under a load of 2.16 kg 2.16 ): 0.50 to 3.00 g / 10 min; and (iii) Molecular weight distribution (Mw / Mn, MWD): 5 or greater, less than 20; (iv) haze less than 15% as measured according to ISO 13468; and (v) Surface modulus of 1.2 GPa or more due to nanoindenters at 25±5 ℃. In paragraph 8, The above density is 0.940 g / cm³ 3 Above 0.970 g / cm³ 3 And, the above melt index (MI) 2.16 A biaxially stretched film having a g / 10 min of 1.00 to 2.

00. In paragraph 8, The above-mentioned haze is 13% or less, a biaxially stretched film. In paragraph 8, A biaxially stretched film having a surface modulus of 1.2 GPa or more and 2.0 GPa or less. In paragraph 8, A biaxially stretched film having a gloss of 63 GU or more and 200 GU or less. In paragraph 8, A biaxially stretched film having a thickness of 10 to 100 μm.

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