Polyethylene resin composition

Abstract

To provide a polyethylene-based resin composition which enables formation of a molding having a smooth surface by extrusion molding.SOLUTION: A polyethylene-based resin composition contains a polyethylene-based resin and an organic acid metal salt, wherein a density of the polyethylene-based resin is 880-910 kg / m3, and a content of the organic acid metal salt is 0.025-0.5 pts.mass with respect to 100 pts.mass of the polyethylene-based resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyethylene resin composition. [Background technology]

[0002] The polyethylene resin composition is extruded to be processed into a molded article such as a sheet, film, or filament. The molded article is used as a variety of industrial materials. The polyethylene resin composition is preferably a polyethylene-based resin having (A) a density of 0.945 to 0.970 g / cm 3 A polyethylene resin composition for extrusion molding is known, which is characterized by being obtained by blending 0.01 to 1.5 parts by weight of (B) a fatty acid amide, 0.01 to 1.5 parts by weight of (C) an organic acid metal salt, and 0.01 to 1.0 part by weight of (D) a phenolic antioxidant and / or a phosphorus-based antioxidant with 100 parts by weight of a polyethylene resin having a melt index of 0.1 to 2.0 g / 10 min (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-126448 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, in the case of molded articles intended for use in a manner that is likely to be visible to the human eye or that come into contact with the skin, it is desirable that the smoothness of the surface formed by extrusion of the polyethylene resin composition be as high as possible from the viewpoints of the appearance and feel of the molded article.

[0005] Therefore, one aspect of the present invention provides a polyethylene resin composition that can be extruded to form a molded article having a smooth surface. [Means for solving the problem]

[0006] One aspect of the present invention is a polyethylene resin having a density of 880 to 910 kg / m3, which comprises a polyethylene resin and an organic acid metal salt. 3 The polyethylene resin composition has the following formula: wherein the content of the organic acid metal salt is 0.025 to 0.5 parts by mass per 100 parts by mass of the polyethylene resin. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide a polyethylene resin composition that can be extruded to form a molded article having a smooth surface. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention is not limited to the following examples.

[0009] An example of the polyethylene resin composition contains at least a polyethylene resin and an organic acid metal salt.

[0010] The polyethylene resin is a copolymer containing a monomer unit based on ethylene. The polyethylene resin may be, for example, an ethylene-α-olefin copolymer. From the viewpoint of excellent moldability, the polyethylene resin may be an ethylene-α-olefin copolymer having a long chain branch. The polyethylene resin may be one type alone or two or more types may be used in combination.

[0011] The number of carbon atoms of the α-olefin in the ethylene-α-olefin copolymer may be 4 to 20, 5 to 20, or 6 to 20. Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 4-methyl-1-hexene. The α-olefin may be one type alone, or two or more types may be used in combination. The α-olefin may be 1-hexene, 4-methyl-1-pentene, or 1-octene.

[0012] The content of ethylene-based monomer units (ethylene units) in the polyethylene resin may be 50% by mass or more, 70% by mass or more, 75% by mass or more, or 79% by mass or more, and may be 99.5% by mass or less, 95% by mass or less, 92% by mass or less, or 89% by mass or less, based on the total mass of the polyethylene resin. The content of ethylene-based monomer units (ethylene units) in the polyethylene resin may be 50 to 99.5% by mass, based on the total mass of the polyethylene resin.

[0013] The content of monomer units based on α-olefin in the polyethylene resin may be 0.5% by mass or more, 5% by mass or more, 8% by mass or more, or 11% by mass or more, and may be 50% by mass or less, 30% by mass or less, 25% by mass or less, or 21% by mass or less, relative to the total mass of the polyethylene resin. The content of monomer units based on α-olefin in the polyethylene resin may be 0.5 to 50% by mass, relative to the total mass of the polyethylene resin.

[0014] The polyethylene resin may have, in addition to monomer units based on ethylene and monomer units based on α-olefins, monomer units based on other monomers, such as conjugated dienes (e.g., butadiene and isoprene), non-conjugated dienes (e.g., 1,4-pentadiene), acrylic acid, acrylic acid esters (e.g., methyl acrylate and ethyl acrylate), methacrylic acid, methacrylic acid esters (e.g., methyl methacrylate and ethyl methacrylate), and vinyl acetate.

[0015] Examples of polyethylene-based resins include ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-1-butene-1-hexene copolymers, ethylene-1-butene-4-methyl-1-pentene copolymers, and ethylene-1-butene-1-octene copolymers. The polyethylene-based resin may be an ethylene-1-hexene copolymer, an ethylene-1-butene-1-hexene copolymer, or an ethylene-1-butene-4-methyl-1-pentene copolymer.

[0016] The density of polyethylene resin is 880 to 910 kg / m 3 The density of polyethylene resin is set to 881 kg / m from the viewpoint of increasing the rigidity of the molded body and reducing deformation of the molded body due to load. 3 Above, 882kg / m 3 Above, 883kg / m 3 Above, 884kg / m 3 More than 885kg / m 3 More than 886kg / m 3 Above, 887kg / m 3 Above, 888kg / m 3 Above, 889kg / m 3 More than 890kg / m 3 Above, 891kg / m 3 Above, 892kg / m 3 Above, 893kg / m 3 Above, 894kg / m 3 Above, 895kg / m 3 Above, 896kg / m 3 Above, 897kg / m 3 Above, 898kg / m 3 Above, 899kg / m 3 or more, or 900 kg / m 3 The density of the polyethylene resin may be 909 kg / m or more from the viewpoint of further improving the transparency of the molded article and increasing the impact resistance of the molded article. 3 Below, 908kg / m 3 Below, 907kg / m 3 Below, 906kg / m 3 Below, 905kg / m 3 Below, 904kg / m 3 Below, 903kg / m 3 Below, 902kg / m 3 Below, 901kg / m 3 or less than 900 kg / m 3 The density of the polyethylene resin means a value measured in accordance with the method specified in Method A of JIS K7112-1980.

[0017] The polyethylene resin may have an MFR (melt flow rate) of 3.0 g / 10 min or more, 3.2 g / 10 min or more, or 3.4 g / 10 min or more from the viewpoints of improving moldability and reducing the load applied during extrusion. The polyethylene resin may have an MFR of 8.5 g / 10 min or less, 8.0 g / 10 min or less, 7.5 g / 10 min or less, 7.0 g / 10 min or less, 6.5 g / 10 min or less, 6.0 g / 10 min or less, 5.5 g / 10 min or less, 5.0 g / 10 min or less, or 4.5 g / 10 min or less from the viewpoint of improving the mechanical strength of a molded article. The polyethylene resin may have an MFR of 3.0 to 8.5 g / 10 min, or 3.0 to 5.0 g / 10 min. The MFR of a polyethylene resin means a value measured by Method A under conditions of a load of 21.18 N and a temperature of 190°C in accordance with the method specified in JIS K7210-1995.

[0018] The molecular weight distribution Mw / Mn of the polyethylene resin may be 1.5 or more, or 1.7 or more, from the viewpoints of improving moldability and reducing the load applied during extrusion. The molecular weight distribution Mw / Mn of the polyethylene resin may be 2.5 or less, or 2.0 or less, from the viewpoint of improving the mechanical strength of the molded body. The molecular weight distribution Mw / Mn of the polyethylene resin may be 1.5 to 2.5. The molecular weight distribution Mw / Mn of the polyethylene resin refers to a value calculated from the weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC). Specifically, the molecular weight distribution Mw / Mn of the polyethylene resin can be calculated by the method described in the Examples below.

[0019] The temperature at which the maximum value of the melting peak observed in differential scanning calorimetry of a polyethylene-based resin is observed (hereinafter sometimes referred to as the "melting peak temperature") may be 100°C or lower, 95°C or lower, 93°C or lower, 90°C or lower, 85°C or lower, or 80°C or lower, from the viewpoint of improving moldability and reducing the load on the polyethylene-based resin composition during extrusion molding. The melting peak temperature of a polyethylene-based resin may be 50°C or higher, 55°C or higher, 60°C or higher, 65°C or higher, 70°C or higher, or 75°C or higher. The melting peak temperature of a polyethylene-based resin refers to the temperature shown by the maximum value of the melting peak with the greatest height among the melting peaks present in the range from 25°C to 150°C, obtained by obtaining a DSC thermogram including a melting peak using a differential scanning calorimeter. Specifically, the maximum melting peak temperature of a polyethylene-based resin can be measured by the method described in the Examples below.

[0020] Polyethylene resins can be produced by conventional polymerization methods using conventional polymerization catalysts. Examples of polymerization catalysts include metallocene catalysts, vanadium catalysts, Ziegler-Natta catalysts, and chromium catalysts. Examples of polymerization methods include liquid-phase polymerization, slurry polymerization, gas-phase polymerization, and high-pressure ionic polymerization. The polymerization method may be, for example, batch polymerization, continuous polymerization, or multi-stage polymerization (two or more stages). Commercially available polyethylene resins with a specified density can also be used.

[0021] Examples of metallocene catalysts include those described in JP-A-58-19309, JP-A-60-35005, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, JP-A-61-130314, JP-A-3-163088, JP-A-4-268307, JP-A-9-12790, JP-A-9-87313, JP-A-11-80233, and JP-T-10-508055.

[0022] Specific examples of metallocene catalysts include those represented by the general formula R 1 k R 2l R 3 m R 4 n M (where M is zirconium, titanium, hafnium or vanadium), R 1 is a group having a cyclopentadiene-type anionic skeleton, and R 2 , R 3 and R 4 are each a group having a cyclopentadiene-type anion skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or a hydrogen atom, and k and l are integers of 1 or more, and k+l+m+n=4.

[0023] Examples of the metallocene compound represented by the above general formula include bis(cyclopentadienyl)diethyltitanium, bis(cyclopentadienyl)dimethyltitanium, bis(pentamethylcyclopentadienyl)titanium, bis(cyclopentadienyl)dichlorotitanium, bis(cyclopentadienyl)titanium monochloride monohydride, bis(indenyl)titanium monochloride monohydride, bis(indenyl)titanium dichloride, ethylene Ethylenebis(indenyl)dimethyltitanium, Ethylenebis(indenyl)methyltitanium chloride, Ethylenebis(indenyl)titanium dichloride, Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride, Ethylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethyltitanium, Ethylenebis(4-methyl-1-indenyl)titanium dichloride, Ethylenebis(2,3-dimethyl-1-indenyl)titanium dichloride, bis(cyclopentadienyl)diethyltitanium, bis(cyclopentadienyl)dimethylzirconium, bis(pentamethylcyclopentadienyl)zirconium, bis(cyclopentadienyl)dichlorozirconium, bis(cyclopentadienyl)monochloride monohydride, bis(indenyl)zirconium monochloride monohydride, bis(indenyl)zirconium dichloride, ethylenebis(indenyl)dimethylzirconium, ethylene Examples include ethylene bis(indenyl)methyl zirconium dichloride, ethylene bis(indenyl)zirconium dichloride, ethylene bis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride, ethylene bis(4,5,6,7-tetrahydro-1-indenyl)dimethyl zirconium, ethylene bis(4-methyl-1-indenyl)zirconium dichloride, and ethylene bis(2,3-dimethyl-1-indenyl)zirconium dichloride.

[0024] Examples of organoaluminum oxide compounds include tetramethyldialuminoxane, tetraethyldialuminoxane, tetrabutyldialuminoxane, tetrahexyldialuminoxane, methylaluminoxane, ethylaluminoxane, butylaluminoxane, and hexylaluminoxane.

[0025] The vanadium catalyst may be a catalyst containing a vanadium compound and an organoaluminum compound. The vanadium compound may be a compound represented by the general formula VO(OR) n X 3-n (wherein R is a hydrocarbon group, X is a halogen atom, and n is an integer of 0 to 3), and specific examples thereof include VOCl3, VO(OCH3)Cl2, VO(OCH3)2Cl, VO(OCH3)3, VO(OC2H5)Cl2, VO(OC2H5)2Cl, VO(OC2H5)3, VO(OC3H7)Cl2, VO(OC3H7)2Cl, VO(OC3H7)3, and mixtures thereof.

[0026] Examples of organoaluminum compounds include those represented by the general formula R' m AlX 3-m (wherein R' is a hydrocarbon group, X is a halogen atom, and m is an integer of 1 to 3), and specifically, (C2H5)2AlCl, (C4H9)2AlCl, (C6H 13 )2AlCl, (C2H5) 1.5 AlCl 1.5 , (C4H9) 1.5 AlCl 1.5 , (CH 13 ) 1.5 AlCl 1.5 , C2H5AlCl2, C4H9AlCl2, and C6H 13 Examples include AlCl2.

[0027] Ziegler-Natta catalysts include catalysts comprising a magnesium compound-based support containing at least one component selected from the group consisting of titanium trichloride, vanadium trichloride, titanium tetrachloride, and titanium haloalcoholates, and an organometallic co-catalyst, as well as catalysts comprising a coprecipitate or eutectic of a magnesium compound and a titanium compound and an organometallic co-catalyst.

[0028] Examples of chromium-based catalysts include catalysts comprising a component in which a chromium compound is supported on silica or silica-alumina, and an organometallic compound as a cocatalyst.

[0029] The content of the polyethylene resin may be 95% by mass or more, 97% by mass or more, or 99% by mass or more, or 99.9% by mass or less, 99.5% by mass or less, or 99.1% by mass or less, based on the total mass of the polyethylene resin composition. The content of the polyethylene resin may be 95 to 99.9% by mass, based on the total mass of the polyethylene resin composition.

[0030] The organic acid metal salt is a salt formed from an organic acid and a metal. The organic acid metal salt may be a metal soap. The organic acid may be a higher fatty acid or an aliphatic oxyacid. The metal may be magnesium, calcium, barium, zinc, aluminum, lithium, tin, or lead.

[0031] Examples of higher fatty acids include chain monocarboxylic acids having carbon atoms of 10 to 22. The aliphatic oxyacid may be an aliphatic carboxylic acid having an alcoholic hydroxyl group.

[0032] The organic acid metal salt may be, for example, at least one selected from the group consisting of magnesium stearate, calcium stearate, barium stearate, zinc stearate, aluminum stearate, lithium stearate, calcium citrate, calcium lactate, calcium 12-hydroxystearate, calcium stearyl lactate, and calcium lauryl lactate.

[0033] The content of the organic acid metal salt may be 0.025 parts by mass or more, 0.030 parts by mass or more, 0.040 parts by mass or more, 0.045 parts by mass or more, or 0.50 parts by mass or more, relative to 100 parts by mass of the polyethylene resin, from the viewpoint of reducing the load on the polyethylene resin composition during extrusion molding. The content of the organic acid metal salt may be 0.5 parts by mass or less, 0.4 parts by mass or less, 0.3 parts by mass or less, 0.2 parts by mass or less, or 0.1 parts by mass or less, relative to 100 parts by mass of the polyethylene resin, from the viewpoint of maintaining the mechanical strength of the molded product. The content of the organic acid metal salt may be 0.025 to 0.5 parts by mass, based on the total mass of the polyethylene resin composition.

[0034] The polyethylene resin composition may further contain components other than the polyethylene resin and the organic acid metal salt, such as a stabilizer, a lubricant, an antistatic agent, an antiblocking agent, a dye, or a pigment.

[0035] Examples of the stabilizer include phenolic stabilizers such as 2,6-di-t-butyl-p-cresol (BHT), tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, and n-octadecyl-3-(4'-hydroxy-3,5'-di-t-butylphenyl)propionate; and phosphite stabilizers such as bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite and tris(2,4-di-t-butylphenyl)phosphite.

[0036] The lubricant may be an organic fatty acid amide. Examples of the organic fatty acid amide include saturated fatty acid amides, unsaturated fatty acid amides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides. Examples of the saturated fatty acid amides include stearic acid amide and behenic acid amide. Examples of the unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Examples of the saturated fatty acid bisamides include ethylene bisstearic acid amide. Examples of the unsaturated fatty acid bisamides include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, and N,N'-dioleyl sebacate amide.

[0037] Examples of antistatic agents include glycerin esters, sorbitan acid esters, and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms. Examples of antiblocking agents include silica, calcium carbonate, and talc.

[0038] The polyethylene resin composition can be produced by melt-kneading a polyethylene resin and an organic acid metal salt. The polyethylene resin composition may also be produced by melt-kneading a plurality of polyethylene resins and organic acid metal salts.

[0039] Examples of a method for melt-kneading a polyethylene resin and an organic acid metal salt include a method in which the polyethylene resin and the organic acid metal salt are mixed in a blender such as a Henschel mixer or a tumbler mixer, and then melt-kneaded using a single-screw extruder, a twin-screw extruder, a Banbury mixer, a heated roll, etc. Examples of a method for adding components other than the polyethylene resin and the organic acid metal salt include a method of melt-kneading the polyethylene resin together with the organic acid metal salt, a dry blending method, and a method of preparing a masterbatch and dry-blending this masterbatch with the polyethylene resin, etc.

[0040] The polyethylene resin composition may be for extrusion molding. By extrusion molding using the polyethylene resin composition according to the present disclosure, a molded article having a smooth surface can be easily formed. For example, the surface roughness Rz of a molded article formed by extrusion molding in which the polyethylene resin composition is extruded through a die hole is 950 to 1050 s -1 When the polyethylene resin composition is 1.5 μm or less, the average particle size may be 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less. The polyethylene resin composition may be formed by melt-kneading a raw material mixture containing the polyethylene resin and the organic acid metal salt in an extruder. [Example]

[0041] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0042] 1. Polyethylene resin The following polyethylene resins were prepared. Polyethylene resin P1 (ethylene-1-hexene copolymer, ethylene unit content: 80% by mass) Polyethylene resin P2 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P3 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P4 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P5 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P6 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P7 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P8 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P9 (ethylene-1-hexene copolymer, ethylene unit content: 79% by mass) Polyethylene resin P10 (ethylene-1-hexene copolymer, ethylene unit content: 82% by mass) Polyethylene resin P11 (ethylene-1-hexene copolymer, ethylene unit content: 80% by mass) Polyethylene resin P12 (ethylene-1-hexene copolymer, ethylene unit content: 83% by mass) Polyethylene resin P13 (ethylene-1-hexene copolymer, ethylene unit content: 89% by mass)

[0043] 2. Evaluation of polyethylene resins density The density of the polyethylene resin was measured according to the method specified in Method A of JIS K7112-1980.

[0044] Melt Flow Rate The melt flow rate of the polyethylene resin was measured by Method A, which is a method specified in JIS K7210-1995, under conditions of a load of 21.18 N and a temperature of 190°C.

[0045] Molecular weight distribution Mw / Mn The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polyethylene resins were measured in terms of standard polystyrene using gel permeation chromatography (GPC) under the following conditions (1) to (8). The molecular weight distribution (Mw / Mn) of polyethylene resins was calculated from Mw and Mn. The baseline on the chromatogram was defined as a straight line connecting the points in the stable, flat region with a retention time sufficiently shorter than the appearance of the polyethylene resin elution peak and the points in the stable, flat region with a retention time sufficiently longer than the observed solvent elution peak. (1) Apparatus: Waters, Waters 150C (2) Separation column: TOSOH TSKgelGMH6-HT (3) Measurement temperature: 140℃ (4) Carrier: o-dichlorobenzene (5)Flow rate: 1.0mL / min (6) Injection volume: 500μL (7) Detector: Differential refraction (8) Molecular weight standard: Standard polystyrene

[0046] Melting Peak Temperature A polyethylene resin was pressed at 10 MPa for 5 minutes using a hot press at 150°C, followed by cooling for 5 minutes using a cooling press at 30°C to obtain a sheet approximately 100 μm thick. Approximately 10 mg of a sample was cut from the sheet and sealed in an aluminum pan. Using the aluminum pan containing the sample, differential scanning calorimetry was performed under the following conditions: 150°C for 5 minutes, then cooled from 150°C to -80°C at 10°C / min, held at -80°C for 2 minutes, and then heated from -80°C to 150°C at 10°C / min. A DSC thermogram including a melting peak was obtained. A differential scanning calorimeter (PerkinElmer, DSC-7) was used as the measuring device. The temperature at which the maximum value of the largest melting peak was observed in the DSC thermogram between 25°C and 150°C was determined as the melting peak temperature.

[0047] 3. Extrusion molding test A co-rotating twin-screw kneading extruder (KZW20TW, manufactured by Technobel Co., Ltd.) having a feeder and a nozzle head attached to the extruder side was prepared. The temperatures of nine barrels C1 to C9, which were arranged in order from the hopper side of the twin-screw kneading extruder along the extrusion direction, were 100°C for barrel C1, 170°C for barrel C2, and 210°C for barrels C3 to C9. A polyethylene resin and an organic acid metal salt shown in Table 1 or Table 2 were fed into the hopper opening of barrel C1 of the twin-screw kneading extruder. Tables 1 and 2 show the amount of organic acid metal salt added (unit: parts by mass) per 100 parts by mass of polyethylene resin. The nozzle head temperature was set to 210°C, and the screw rotation speed was set to 300 rpm, and the polyethylene resin and the organic acid metal salt were melt-kneaded. The resulting kneaded product (polyethylene resin composition) was discharged from the die hole of the twin-screw kneading extruder at a throughput of 5 kg / hour. The discharged kneaded product was cooled in a water bath at 10 to 35°C to obtain a strand-shaped molded product. The shear rate γ of the polyethylene resin composition passing through the die holes was calculated using the formula: γ = 32Q / (πD 3 ) was calculated to be 950-1050S -1 In the formula, Q is the volumetric flow rate (unit: mm 3 / s), and D is the inner diameter of the die hole (unit: mm).

[0048] exterior The appearance of the strand-shaped molded articles thus produced was visually observed, and the appearance of each molded article was classified as transparent, translucent, or opaque.

[0049] Surface smoothness The surface roughness of the molded body was evaluated using a microscope (RH-2000, manufactured by HiROX Co., Ltd.). Specifically, photographs of the molded body surface were taken at intervals of 0.15 μm along the direction perpendicular to the extrusion direction of the strand, and the obtained images were processed using a 3D profile to determine the surface roughness Rz.

[0050] Time until eye discharge occurs When obtaining a strand-shaped molded body, the polyethylene resin and the organic acid metal salt were fed into the hopper opening of the barrel C1 of the twin-screw kneading extruder, and 5 minutes after this was set as time 0. The time until adhesion of the resin to the die hole was confirmed was measured.

[0051] [Table 1]

[0052] [Table 2]

Claims

1. Contains a polyethylene resin and an organic acid metal salt, The density of the polyethylene resin is 880 to 910 kg / m ３ and the organic acid metal salt is a salt formed from an organic acid and a metal, the organic acid is a higher fatty acid, the higher fatty acid is a chain monocarboxylic acid having 10 to 22 carbon atoms, The polyethylene-based resin composition has a content of the organic acid metal salt of 0.025 to 0.5 parts by mass per 100 parts by mass of the polyethylene-based resin.

2. A polyethylene resin composition as described in claim 1, wherein the organic acid metal salt is at least one selected from the group consisting of magnesium stearate, calcium stearate, barium stearate, zinc stearate, aluminum stearate, and lithium stearate.

3. 3. The polyethylene resin composition according to claim 1, wherein the polyethylene resin has an MFR of 3.0 to 8.5 g / 10 min.

4. the molecular weight distribution Mw / Mn of the polyethylene resin is 1.5 to 2.5; The polyethylene resin composition according to any one of claims 1 to 3, wherein the temperature at which a maximum value of a melting peak is observed in differential scanning calorimetry of the polyethylene resin is 100°C or lower.

5. The polyethylene resin composition according to any one of claims 1 to 4, which is for extrusion molding.

6. The surface roughness Rz of a molded article formed by extrusion molding in which the polyethylene resin composition is extruded through a die hole is such that the shear rate of the polyethylene resin composition passing through the die hole is 950 to 1050 s －１ The polyethylene resin composition according to any one of claims 1 to 5, wherein the particle size is 4.5 µm or less when

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