Polyethylene resin composition and molded article comprising the same

Abstract

To provide a polyethylene resin composition having good water vapor barrier properties and transparency.SOLUTION: A polyethylene resin composition comprising 60 to 99 parts by weight of a polyethylene resin (A) satisfying the following (a) to (c) and 1 to 40 parts by weight of an ethylene-based polymer (B) satisfying the following (d) to (g) (the total of (A) and (B) is 100 parts by weight), and 200 to 2500ppm in total of a 1, 2-cyclohexane dicarboxylate and a stearate as a nucleating agent (C): (a) densities of 950 to 970kg / m3, (b) melt mass flow rates (MFR) of 0.1 to 50g / 10 minutes, (c) ratios (Mw / Mn) of number-average molecular weights (Mn) to weight-average molecular weights (Mw) of 5.0 or less, (d) densities of 940 to 949kg / m3, (e) MFRs of 0.1 to 3g / 10 minutes, (f) Mw / Mn of 3.0 to 5.0, (g) the number of branches of hexyl groups or more per 1000 carbon atoms (LCB) of 0.5 to 2 SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyethylene resin composition, and more particularly to a resin composition of a specific polyethylene and a nucleating agent, and a molded article made therefrom. [Background technology]

[0002] In recent years, there has been growing global interest in reducing waste from plastic packaging and plastic containers, leading to a demand for materials and technologies that can increase sustainability, and an increasing number of efforts are being made to reduce packaging thickness and promote recycling.

[0003] Many film packaging uses multilayer structures combining multiple materials, such as polyethylene, polypropylene, ethylene-vinyl alcohol copolymer, polyethylene terephthalate, and cyclic polyolefin, and is designed to take advantage of the properties of each material. However, combining these different materials presents challenges in recycling. Therefore, a single packaging material is required, but the properties achieved with other resins are lost, making it difficult to maintain the performance and processing characteristics of the packaging container. For example, when polyethylene is used alone, while it offers excellent moldability and post-processing properties and low manufacturing costs, it lacks sufficient gas barrier properties against water vapor and oxygen, potentially reducing its performance as a container for preserving the properties of the contents. While selecting polyethylene with a high degree of crystallinity, i.e., a high density, can achieve relatively high gas barrier properties, the gas barrier properties may not always be sufficient, resulting in reduced transparency and impaired visibility of the contents. Furthermore, even when thinning packaging as an environmentally friendly approach, the gas barrier properties tend to decrease as the thickness decreases. Therefore, a polyethylene resin with sufficient gas barrier properties and transparency, even when used alone, is desired.

[0004] Patent Document 1 proposes a method for achieving both recyclability and gas barrier properties by performing metal vapor deposition on a laminate consisting of a polyethylene main layer and a surface layer made of another resin.

[0005] In recent years, Patent Documents 2 and 3 have proposed nucleating agents that are effective for polyethylene resins. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-160255 [Patent Document 2] Patent No. 7019862 [Patent Document 3] Patent No. 7143508 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polyethylene resin composition having excellent gas barrier properties and transparency. [Means for solving the problem]

[0008] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by adding a specific polyethylene and a specific nucleating agent to polyethylene that satisfies specific requirements, it is possible to obtain water vapor barrier properties at a level not available in conventional polyethylene resins, thereby solving the above-mentioned problems, and have thus completed the present invention.

[0009] That is, the respective aspects of the present invention are as follows [1] to [3]. [1] A polyethylene resin composition comprising 60 to 99 parts by weight of a polyethylene resin (A) satisfying the following properties (a) to (c), and 1 to 40 parts by weight of an ethylene polymer (B) satisfying the following properties (d) to (g) (the total of (A) and (B) being 100 parts by weight), and containing 200 to 2500 ppm in total of a 1,2-cyclohexanedicarboxylate and a stearate as a nucleating agent (C). (a) Density is 950-970 kg / m 3 is. (b) The melt mass flow rate (MFR) measured in accordance with JIS K 6922-1 at 190°C under a load of 21.18 N is 0.1 to 50 g / 10 min. (c) The ratio (Mw / Mn) of number average molecular weight (Mn) to weight average molecular weight (Mw) is 5.0 or less. (d) Density is 940 to 949 kg / m 3 is. (e) MFR is 0.1 to 3.0 g / 10 min. (f) The ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is in the range of 3.0 to 5.0. (g) 13 The number of hexyl or higher branches (LCB) per 1000 carbon atoms determined from C-NMR spectroscopy is 0.5 to 2. [2] The polyethylene resin composition of [1], wherein the ratio of calcium 1,2-cyclohexanedicarboxylate to zinc stearate in the nucleating agent (C) is 60:40 to 70:30. [3] A molded article made of the resin composition according to [1] or [2]. [Effects of the Invention]

[0010] According to the present invention, a resin composition can be provided that suppresses moisture evaporation from the contents, which is a problem with polyethylene resin molded products, improves the shelf life of the contents, and provides transparency that ensures visibility of the contents. By using this resin composition, molded products can be obtained that are thinner than conventional products while maintaining water vapor barrier properties. Furthermore, by using a single raw material resin for multilayer molded products that were previously made from multiple raw material resins, applications such as easier recycling after use become possible. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. (1) Polyethylene resin (A) The polyethylene resin (A) used in the present invention is an ethylene homopolymer or a copolymer of ethylene and an α-olefin.

[0012] The polyethylene resin (A) has a density of 950 to 970 kg / m according to JIS K6760. 3 , preferably 950 to 960 kg / m 3 The density of the polyethylene resin (A) is 950 kg / m 3 If it is less than 970 kg / m, the water vapor barrier property will be poor. 3 When it exceeds 100, the transparency decreases.

[0013] The polyethylene resin (A) has a melt flow rate (hereinafter referred to as MFR) measured in accordance with JIS K 6922-1 at 190°C under a load of 2.16 kg of 0.1 to 50 g / 10 min, preferably 0.5 to 30 g / 10 min, and more preferably 1.0 to 10 g / 10 min. If the MFR is less than 0.1 g / 10 min, the load on the extruder increases during molding, making the surface prone to roughening during molding. If the MFR exceeds 50 g / 10 min, the melt tension decreases and molding stability decreases.

[0014] The polyethylene resin (A) has a weight average molecular weight (Mw) to Mn ratio (Mw / Mn) of 5.0 or less, preferably 2.0 to 4.0, and more preferably 2.0 to 3.5, as determined by molecular weight measurement by gel permeation chromatography (GPC). If Mw / Mn exceeds 5.0, the molded article will have poor water vapor barrier properties and poor transparency. If Mw / Mn is 2.0 or more, the extrusion load during molding is small and the appearance (surface texture) of the molded article is good, which is preferable.

[0015] The polyethylene resin (A) can be produced by, for example, a slurry method, a solution method, a gas phase method, etc. When producing the polyethylene resin (A), generally, a Ziegler catalyst comprising a solid catalyst component containing magnesium and titanium and an organoaluminum compound, a metallocene catalyst comprising an organic transition metal compound containing a cyclopentadienyl derivative and a compound and / or organic metal compound that reacts with the organic transition metal compound to form an ionic complex, a vanadium-based catalyst, etc. can be used, and the polyethylene resin (A) can be produced by homopolymerizing ethylene or copolymerizing ethylene and an α-olefin using such a catalyst, but production using a metallocene catalyst is particularly preferred because it gives high-density polyethylene with narrow molecular weight distribution and composition distribution and provides high water vapor barrier properties.

[0016] The polyethylene resin (A) may be a commercially available product, and examples thereof include Nipotec (registered trademark) 06S84A, 06S81H, and 06S81K (trade names) manufactured by Tosoh Corporation, and Nipolon Hard (registered trademark) 1200 (trade name) manufactured by Tosoh Corporation. (2) Ethylene polymer (B) The ethylene polymer (B) used in the present invention has a density of 940 to 949 kg / m according to JIS K6922-1. 3 , preferably 941 to 947 kg / m 3 The density is in the range of 940 kg / m 3 If the density is less than 949 kg / m, the water vapor barrier properties will be poor. 3 If it exceeds this value, the transparency will decrease.

[0017] The polyethylene resin (B) has a melt flow rate (hereinafter referred to as MFR) measured in accordance with JIS K 6922-1 at 190°C under a load of 2.16 kg in the range of 0.1 to 3.0 g / 10 min, preferably 0.2 to 2.0 g / 10 min. If the MFR is less than 0.1 g / 10 min, the melt viscosity is too high, making it difficult to produce molded articles using a general-purpose molding machine. If the MFR is more than 3.0 g / 10 min, transparency decreases.

[0018] The ethylene polymer (B) has a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) in the range of 3.0 to 5.0, preferably 3.5 to 4.5, as measured by GPC. If Mw / Mn is less than 3.0, transparency will decrease. If Mw / Mn is more than 5.0, transparency will also decrease.

[0019] The ethylene polymer (B) is 13 The number of hexyl or higher branches (LCB) per 1000 carbon atoms determined from C-NMR spectroscopy is 0.5 to 2. If the number of LCBs is less than 0.5, no significant improvement in water vapor barrier property or transparency can be obtained, and if the number of LCBs is more than 2, no significant improvement in water vapor barrier property or transparency can be obtained.

[0020] The ethylene polymer (B) is produced using a metallocene catalyst. The metallocene catalyst used contains a metallocene complex, an activating cocatalyst, and, if necessary, an organoaluminum compound as constituent components, and it is preferable to copolymerize the macromonomer, ethylene, and an olefin having 3 to 6 carbon atoms simultaneously with the synthesis of the macromonomer.

[0021] The macromonomer is an olefin polymer having a vinyl group at its terminal, i.e., an ethylene copolymer having a vinyl group at its terminal, obtained by copolymerizing ethylene with an olefin having 3 to 6 carbon atoms. As the metallocene complex of the metallocene catalyst for synthesizing the macromonomer and copolymerizing the macromonomer with ethylene and an olefin having 3 to 6 carbon atoms, a catalyst using a non-bridged bis(indenyl)zirconium complex, a non-bridged bis(cyclopentadienyl)zirconium complex, a bridged bis(cyclopentadienyl)zirconium complex, a bridged bis(indenyl)zirconium complex, a bridged (cyclopentadienyl)(indenyl)zirconium complex, a bridged (cyclopentadienyl)(fluorenyl)zirconium complex, or a bridged (indenyl)(fluorenyl)zirconium complex is preferred. Specific examples of metallocene complexes include bis(indenyl)zirconium dichloride, dimethylsilanediylbis(cyclopentadienyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(indenyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(2-methylindenyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(4,7-dimethylindenyl)zirconium dichloride, and dimethylsilanediyl(cyclopentadienyl)(2,4,7-dimethylindenyl)zirconium dichloride. Examples of suitable transition metal compounds include dichlorides such as diphenylmethylene(1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride, diphenylmethylene(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride, and isopropylidene(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride, as well as dimethyl, diethyl, dihydro, diphenyl, and dibenzyl forms of the above transition metal compounds. Examples of suitable transition metal compounds include, but are not limited to, compounds in which the zirconium atom of the above transition metal compound is substituted with a titanium atom or a hafnium atom. One or more of these compounds may be used.

[0022] The activating cocatalyst used as a constituent component of the metallocene catalyst refers to a compound that plays a role in converting a metallocene complex or a reaction product of a metallocene complex and an organoaluminum compound into an active species capable of polymerizing olefins, and is preferably a compound that generates a cationic compound from the metallocene complex, and the generated cationic compound acts as an active polymerization species capable of polymerizing olefins. The activating cocatalyst is a compound that, after forming the active polymerization species, provides a compound that weakly coordinates or interacts with the generated cationic compound but does not directly react with the active species.

[0023] Specific examples of the activating cocatalyst include boron compounds such as alkylaluminoxanes such as methylaluminoxane, silica gel-supported alkylaluminoxanes, tris(fluorinated aryl)borons such as tris(pentafluorophenyl)boron, and tetrakis(fluorinated aryl)boron salts such as N,N-dimethylammonium-tetrakis(pentafluorophenyl)boron, silica gel-supported versions of these, as well as clay minerals and clay minerals treated with organic compounds. Of these activating cocatalysts, it is preferable to use clay minerals treated with organic compounds.

[0024] When a clay mineral treated with an organic compound is used as an activating cocatalyst, the clay mineral used is preferably a clay mineral belonging to the smectite group, specific examples of which include montmorillonite, beidellite, saponite, hectorite, etc. A mixture of these clay minerals can also be used.

[0025] The organic compound treatment refers to the introduction of organic ions between clay mineral layers to form an ion complex. Examples of organic compounds used in the organic compound treatment include alkylammonium salts such as N,N-dimethyl-n-octadecylamine hydrochloride, N,N-dimethyl-n-eicosylamine hydrochloride, N,N-dimethyl-n-docosylamine hydrochloride, N,N-dimethyloleylamine hydrochloride, N,N-dimethylbehenylamine hydrochloride, N-methyl-bis(n-octadecyl)amine hydrochloride, N-methyl-bis(n-eicosyl)amine hydrochloride, N-methyl-dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, and N,N-dimethylaniline hydrochloride.

[0026] There are no particular limitations on the method for preparing the metallocene catalyst, such as a method of reacting a metallocene complex with an activating cocatalyst.

[0027] When preparing the metallocene catalyst, an alkylaluminum such as triethylaluminum or triisobutylaluminum may be used as needed for activating the metallocene complex or removing impurities in the solvent.

[0028] When producing the ethylene polymer (B), the polymerization temperature is preferably −100 to 120° C., and particularly considering productivity, 20 to 120° C. is preferred, and the polymerization temperature is more preferably in the range of 60 to 120° C. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa.

[0029] The polymerizable monomers are ethylene and an α-olefin having 3 to 6 carbon atoms. The ethylene and α-olefin having 3 to 6 carbon atoms can be fed at a molar ratio of α-olefin having 3 to 6 carbon atoms / ethylene of 0 to 0.2, preferably 0 to 0.15. It is also possible to adjust the molecular weight using hydrogen or the like during polymerization. In this case, the amount of hydrogen used can be such that the hydrogen / ethylene molar ratio is 0 to 0.002 (hydrogen concentration: 2,000 ppm), preferably 0 to 0.0005 (hydrogen concentration: 800 ppm). The ethylene polymer (B) produced with the α-olefin feed amount and hydrogen concentration within these ranges has an excellent balance between transparency and heat resistance, even among ethylene polymers (B), and can therefore be suitably used as one component of the resin composition of the present invention. The reason why the ethylene polymer (B) produced at the above-mentioned ranges of α-olefin supply amount and hydrogen concentration has a particularly excellent balance between transparency and heat resistance is not clear, but it is presumed that this is because the ethylene polymer (B) has an appropriate branched structure and molecular weight that contribute to achieving both transparency and heat resistance.

[0030] The polymerization can be carried out in a slurry state, a solution state or a gas phase state. In particular, when the polymerization is carried out in a slurry state, polyethylene having a regular powder particle shape can be produced efficiently and stably. (3) Nucleating agent (C) The nucleating agent (C) used in the present invention is a 1,2-cyclohexanedicarboxylate and a stearate. Examples of the 1,2-cyclohexanedicarboxylate include calcium 1,2-cyclohexanedicarboxylate and aluminum 1,2-cyclohexanedicarboxylate. Calcium 1,2-cyclohexanedicarboxylate is particularly preferred because adding it to the polyethylene resin (A) and ethylene polymer (B) produces a resin composition with high water vapor barrier properties. To disperse the nucleating agent well in the polyethylene resin, a stearate is used in combination as a dispersing aid. Examples of the stearate include zinc stearate, calcium stearate, and magnesium stearate. The combined use of 1,2-cyclohexanedicarboxylate and zinc stearate is particularly preferred because it improves the dispersibility of the 1,2-cyclohexanedicarboxylate and provides a high nucleating effect. A ratio of 1,2-cyclohexanedicarboxylate to stearate of 60:40 to 70:30 is preferred because it provides a high nucleating effect.

[0031] The nucleating agent (C) may be a commercially available product, such as Hyperform HPN-20E (trade name) manufactured by Milliken Chemical Co., Ltd. Hyperform HPN-20E contains calcium 1,2-cyclohexanedicarboxylate and zinc stearate in a ratio of 60:40 to 70:30. (4) Polyethylene resin composition The polyethylene resin composition of one embodiment of the present invention is produced by adding a nucleating agent (C) to 60 to 99 parts by weight of a polyethylene resin (A) and 1 to 40 parts by weight of an ethylene polymer (B) (the total of (A) and (B) is 100 parts by weight). The concentration of the nucleating agent (C) added is 200 to 2500 ppm, preferably 300 to 2500 ppm, and more preferably 400 to 2200 ppm. If the nucleating agent (C) is less than 200 ppm, the water vapor barrier property and transparency are reduced. If the nucleating agent (C) is more than 2500 ppm, production costs increase and contamination of the contents due to bleed-out of the nucleating agent component is likely to occur.

[0032] The method for adding the nucleating agent (C) to the polyethylene resin (A) and the ethylene-based resin polymer (B) is not particularly limited, and various known addition methods can be used. Examples include a method in which the polyethylene resin (A), the ethylene-based resin polymer (B), and the nucleating agent (C) are dry-blended using a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., or a method in which the nucleating agent is melt-kneaded using an extruder. Alternatively, a method in which a masterbatch containing a high concentration of the nucleating agent (C) is prepared and mixed with the polyethylene resin (A) and the ethylene-based resin polymer (B) may be used.

[0033] The blending amounts of the polyethylene resin (A) and the ethylene-based resin polymer (B) are 60 to 99 parts by weight of the polyethylene resin (A) and 1 to 40 parts by weight of the ethylene-based resin polymer (B), since the resulting polyethylene resin composition is particularly excellent in water vapor barrier properties and transparency.

[0034] The polyethylene resin composition may be blended with commonly used known additives, such as antioxidants, antistatic agents, lubricants, antiblocking agents, antifogging agents, organic or inorganic pigments, ultraviolet absorbers, dispersants, etc., as needed, within the scope of not significantly impairing the effects of the present invention. The method for blending the above additives with the resin composition of the present invention is not particularly limited, and examples include a method in which the additives are added to the polyethylene resin (A) and the ethylene resin polymer (B) together with the nucleating agent (C) by dry blending or melt kneading, and a method in which a high-concentration masterbatch is prepared in advance and then dry-blended with the polyethylene resin composition of the present invention during molding.

[0035] Furthermore, the resin composition according to one embodiment of the present invention may also be blended with other thermoplastic resins, such as high-density polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene, ethylene-propylene copolymer rubber, and poly-1-butene, within the range that does not impair the effects of the present invention. (4) Molded products The type of molded article obtained by molding the resin composition of the present invention is not particularly limited, and it can be molded into, for example, a film, a sheet, an injection-molded article, a tube, a pipe, a bottle, etc. The molded article obtained may be a single layer, or may contain the resin composition as one layer of a multilayer molded article or a laminate. [Example]

[0036] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0037] <density> The density was measured by the density gradient tube method in accordance with JIS K 6760 (1995).

[0038] <mfr> The MFR (melt flow rate) was measured at 190°C and a load of 21.18N in accordance with JIS K 6922-1.

[0039] <Molecular weight, molecular weight distribution> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) were measured by gel permeation chromatography (GPC). A GPC system (HLC®-8121GPC / HT, manufactured by Tosoh Corporation) and a column (TSKgel® GMHhr-H(20)HT, manufactured by Tosoh Corporation) were used. The column temperature was set to 140°C, and 1,2,4-trichlorobenzene was used as the eluent. The measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected for measurement. The molecular weight calibration curve was calibrated using polystyrene samples of known molecular weight. Mw and Mn were calculated as linear polyethylene equivalent values.

[0040] <Long chain branching> The number of long chain branches per 1000 carbon atoms was measured by carbon nuclear magnetic resonance ( 13 C-NMR) method to measure the carbon nuclear magnetic resonance ( 13 The C-NMR spectrum was measured, and the number of long chain branches per 1,000 carbon atoms in the polymer was calculated using the following method. The measurement temperature was set at 130°C, and the solvent was 1,2-dichlorobenzene / 1,2-dichlorobenzene-d 4 A mixed solution of 75 / 25 (volume ratio) was used.

[0041] <How to calculate the number of long chain branches (LCB)> In an NMR spectrum processed with a Gaussian window function, the sum of the peak areas of all peaks with peak tops between 5 and 50 ppm was set to 1000, and the number of long-chain branches (the number of branches with 7 or more carbon atoms) was determined from the peak area of ​​the peak derived from a methine carbon bonded to a branch with 7 or more carbon atoms. Under these measurement conditions, the number of long-chain branches (the number of branches with 7 or more carbon atoms) was determined from the peak area of ​​the peak with its top near 38.22 to 38.27 ppm. The peak area of ​​the peak was defined as the signal area ranging from the chemical shift of the valley between the adjacent peak on the high magnetic field side to the chemical shift of the valley between the adjacent peak on the low magnetic field side. Under these measurement conditions, the peak derived from a methine carbon bonded to a hexyl branch was at 38.21 ppm in the measurement of an ethylene-1-octene copolymer. ~Production and evaluation of resin compositions and molded products~ <Polyethylene resin (A)> The following polyethylene resins were used: The physical properties of the polyethylene resins are shown in Table 1.

[0042] (A)-1: Nipotec 06S81K (trade name) manufactured by Tosoh Corporation, MFR 5.0 g / 10 min, density 958 kg / m 3 (A)-2: Nipotec 06S81H (trade name) manufactured by Tosoh Corporation, MFR 1.0 g / 10 min, density 952 kg / m 3 (A)-3: Nipolon Hard 1200 (trade name) manufactured by Tosoh Corporation, MFR 21 g / 10 min, density 952 kg / m 3 (A)-4: Nipolon Hard 5110 (trade name) manufactured by Tosoh Corporation, MFR 0.9 g / 10 min, density 961 kg / m 3 (A)-5: Nipolon Hard 5700 (trade name) manufactured by Tosoh Corporation, MFR 1.0 g / 10 min, density 954 kg / m 3 (A)-6: Nipolon Hard 7300A (trade name) manufactured by Tosoh Corporation, MFR 0.05 g / 10 min, density 952 kg / m 3 <Ethylene-based resin polymer (B)> (B)-1 [Preparation of denatured clay] A 1-liter flask was charged with 300 mL of industrial alcohol (trade name: Equinene F-3, manufactured by Japan Alcohol Sales Co., Ltd.) and 300 mL of distilled water. 15.0 g of concentrated hydrochloric acid and 42.4 g (120 mmol) of dimethylbehenylamine (trade name: Armin DM22D, manufactured by Lion Corporation) were added, and the mixture was heated to 45 ° C. to disperse 100 g of synthetic hectorite (trade name: Laponite RDS, manufactured by Rockwood Additives). The mixture was then heated to 60 ° C. and stirred for 1 hour while maintaining the temperature. The slurry was filtered, washed twice with 600 mL of water at 60 ° C., and dried in a dryer at 85 ° C. for 12 hours to obtain 122 g of organically modified clay. This organically modified clay was then jet milled to a median diameter of 15 μm. [Preparation of polymerization catalyst] After replacing the air in a 300 mL flask equipped with a thermometer and reflux condenser with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 mL of hexane were added, followed by 0.4406 g of dimethylsilylene(cyclopentadienyl)(2,4,7-trimethyl-1-indenyl)zirconium dichloride and 142 mL of 20% triisobutylaluminum, and the mixture was stirred at 60°C for 3 hours. After cooling to 45°C, the supernatant was removed and washed five times with 200 mL of hexane, and 200 mL of hexane was added to obtain a catalyst suspension (solids content: 12.0 wt%). [Production of (B)-1] A 2-L autoclave was charged with 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 358 mg (equivalent to 43 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 70°C, and 1.2 g of 1-butene was added. An ethylene / hydrogen mixed gas was continuously fed so that the partial pressure reached 0.80 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 765 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to yield 65 g of polymer (activity: 1,510 g / g catalyst). The MFR of this polymer was 0.4 g / 10 min, and the density was 947 kg / m 3 The number average molecular weight (Mn) was 3.2 × 10 4 , weight average molecular weight is 13.0 × 10 4 The Mw / Mn ratio was 4.1, and the number of long chain branches contained in the polymer was 0.8 per 1000 carbon atoms in the main chain.

[0043] (B)-2 [Preparation of denatured clay] A modified clay compound was prepared in the same manner as in (B)-1. [Preparation of polymerization catalyst] A polymerization catalyst was prepared in the same manner as in (B)-1. [Production of (B)-2] A 2-L autoclave was charged with 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 358 mg (equivalent to 43 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 70°C, and 4.6 g of 1-butene was added. An ethylene / hydrogen mixed gas was continuously fed so that the partial pressure reached 0.80 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 1600 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to yield 86 g of polymer (activity: 1,600 g / g catalyst). The MFR of this polymer was 2.0 g / 10 min, and the density was 941 kg / m 3 The number average molecular weight (Mn) was 2.0 × 10 4 , weight average molecular weight is 9.5 × 10 4 The Mw / Mn ratio was 4.5, and the number of long chain branches contained in the polymer was 1.6 per 1000 carbon atoms in the main chain. (B)-3 [Preparation of denatured clay] A modified clay compound was prepared in the same manner as in (B)-1. [Preparation of polymerization catalyst] A polymerization catalyst was prepared in the same manner as in (B)-1. [Production of (B)-3] A 2-L autoclave was charged with 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 358 mg (equivalent to 43 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 70°C, and 0.7 g of 1-butene was added. An ethylene / hydrogen mixed gas was continuously fed so that the partial pressure reached 0.80 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 930 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to yield 110 g of polymer (activity: 2,550 g / g catalyst). The MFR of this polymer was 1.3 g / 10 min, and the density was 951 kg / m 3 The number average molecular weight (Mn) was 2.6 × 10 4 , weight average molecular weight is 10.5 × 10 4 The Mw / Mn was 4.0, and the number of long chain branches contained in the polymer was 1.0 per 1000 carbon atoms in the main chain.

[0044] (B)-4 [Preparation of denatured clay] A modified clay compound was prepared in the same manner as in (B)-1. [Preparation of polymerization catalyst] A polymerization catalyst was prepared in the same manner as in (B)-1. [Production of (B)-4] A 2-L autoclave was charged with 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 358 mg (equivalent to 43 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 70°C, and an ethylene / hydrogen mixed gas was continuously fed to a partial pressure of 0.80 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 2500 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 291 g of polymer (activity: 6,770 g / g catalyst). The MFR of this polymer was 4.0 g / 10 min, and the density was 959 kg / m 3 The number average molecular weight (Mn) was 1.8 × 10 4 , weight average molecular weight is 7.5 × 10 4 The Mw / Mn was 4.2, and the number of long chain branches contained in the polymer was 1.5 per 1000 carbon atoms in the main chain.

[0045] (B)―5 [Preparation of denatured clay] Dimethylbehenylamine (C) was added to a mixed solvent of 4.8 L of deionized water and 3.2 L of ethanol. 22 H 45 A dimethylbehenylamine hydrochloride solution was prepared by adding 354 g of )(CH3)2N and 83.3 mL of 37% hydrochloric acid. 1,000 g of synthetic hectorite was added to this solution and stirred overnight. The resulting reaction solution was filtered, and the solid was thoroughly washed with water. The solid was dried to obtain 1,180 g of an organically modified clay compound. The liquid content was measured using an infrared moisture meter and was found to be 0.8%. Next, this organically modified clay compound was crushed to an average particle size of 6.0 μm. [Preparation of polymerization catalyst] A 5-L flask was charged with 450 g of the organically modified clay compound prepared in the "Preparation of Modified Clay Compound" section and 1.4 kg of hexane. Then, 1.78 kg (1.8 mol) of a 20 wt% solution of triisobutylaluminum in hexane and 7.32 g (18 mmol) of bis(n-butylcyclopentadienyl)zirconium dichloride were added, heated to 60°C, and stirred for 1 hour. The reaction solution was cooled to 45°C and allowed to stand for 2 hours, after which the supernatant was removed by decantation. Next, 1.78 kg (0.09 mol) of a 1 wt% solution of triisobutylaluminum in hexane was added, and the reaction was continued at 45°C for 30 minutes. The reaction solution was allowed to stand at 45°C for 2 hours, after which the supernatant was removed by decantation. 0.45 kg (0.45 mol) of a 20 wt% solution of triisobutylaluminum in hexane was added, and the mixture was diluted again with hexane to a total volume of 4.5 L to prepare a polymerization catalyst. [Production of (B)-5] To a 300 L polymerization reactor, 135 kg / h of hexane, 20.0 kg / h of ethylene, 0.4 kg / h of butene-1, 6 NL / h of hydrogen, and the polymerization catalyst obtained in the section [Preparation of Polymerization Catalyst] were continuously fed. Furthermore, triisobutylaluminum was continuously fed as a cocatalyst so that the concentration in the liquid was 0.93 mmol / kg hexane. The polymerization temperature was controlled at 85°C. The obtained polymer ((B)-5) had an MFR of 3.0 g / 10 min and a density of 945 kg / m 3 The number average molecular weight (Mn) was 2.5 × 10 4 , weight average molecular weight is 8.0 × 10 4 The Mw / Mn was 3.2, and the number of long chain branches contained in the polymer was 0 per 1000 carbon atoms in the main chain.

[0046] <Resin composition> The resin composition according to the present invention was prepared by dry-blending a predetermined amount of polyethylene resin (A), a predetermined amount of ethylene-based resin polymer (B), and predetermined amounts of calcium 1,2-cyclohexanedicarboxylate and zinc stearate, and then melt-kneading the mixture at a cylinder temperature of 180°C using a 20 mm single-screw extruder (manufactured by Toyo Seiki Seisaku-sho, Ltd.). The strands were then cut to prepare pellets of the resin composition.

[0047] <Press sheet> Next, the resin composition pellets were compressed using a press (manufactured by Shinto Metal Industry Co., Ltd.) at a temperature of 200°C and a pressure of 0.1 MPa for 240 seconds, and then further compressed at a temperature of 200°C and a pressure of 1.0 MPa for 240 seconds, and then compressed at a temperature of 25°C and a pressure of 1.0 MPa for 180 seconds to produce a sheet with a thickness of 500 μm.

[0048] <Water vapor permeability coefficient> The press sheet was measured using a water vapor permeability meter (manufactured by Lyssy) at a temperature of 40°C, humidity of 90% RH, and a measurement area of ​​50 cm 2 The water vapor permeability was measured under the conditions of a standard sample PET (19 μm thick). The product of the thickness of the press sheet, which was measured in advance using a thickness meter (Mitutoyo), and the water vapor permeability was taken as the water vapor permeability coefficient. 2 If the temperature is below 24 hours, the water vapor barrier property is good (good), and if the temperature is below 50g μm / m 2 - If it took more than 24 hours, it was evaluated as poor (×).

[0049] <Light transmittance> The light transmittance of the press sheet at a wavelength of 450 nm was measured in pure water using an ultraviolet-visible spectrophotometer (Model 220A, manufactured by Hitachi, Ltd.) A light transmittance of 50% or more was evaluated as good transparency (◯), and a light transmittance of less than 50% was evaluated as poor transparency (×).

[0050] <Examples 1 to 7 and Comparative Examples 1 to 8> Tables 1 and 2 show the evaluation results of the resin compositions.

[0051] [Table 1]

[0052] [Table 2] < / mfr>

Claims

1. A polyethylene resin composition comprising 70 to 99 parts by weight of a polyethylene resin (A) satisfying the following properties (a) to (c), and 1 to 30 parts by weight of an ethylene polymer (B) satisfying the following properties (d) to (g) (the total of (A) and (B) being 100 parts by weight), and containing 200 to 2500 ppm in total of a 1,2-cyclohexanedicarboxylate and a stearate as a nucleating agent (C). (a) Density is 950 to 970 kg / m ３ is. (b) The melt mass flow rate (MFR) measured in accordance with JIS K 6922-1 at 190°C under a load of 21.18 N is 0.1 to 50 g / 10 min. (c) The ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) is 5.0 or less. (d) Density is 940 to 949 kg / m ３ is. (e) The MFR is 0.1 to 3.0 g / 10 min. (f) The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 3.0 to 5.

0. (g) １３ The number of hexyl or higher branches (LCB) per 1000 carbon atoms determined by C-NMR spectroscopy is 0.5 to 2.

2. 2. The polyethylene resin composition according to claim 1, wherein the ratio of calcium 1,2-cyclohexanedicarboxylate to zinc stearate in the nucleating agent (C) is 60:40 to 70:

30.

3. A molded article made from the polyethylene resin composition according to claim 1 or 2.

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