Polyethylene resin composition and molded article using the same

Abstract

To provide a polyethylene resin composition which is excellent in injection moldability, impact resistance and durability, and a molded article obtained by injection molding the polyethylene resin composition.SOLUTION: A polyethylene resin composition satisfies the following characteristics (1) to (6). Characteristic (1): HLMFR of 10 g / 10 min or more and 200 g / 10 min or less. Characteristic (2): density of 0.945 g / cm3 or more and 0.970 g / cm3 or less. Characteristic (3): Charpy impact strength at -40°C of 6.0 kJ / m2 or more. Characteristic (4): a rupture time in a full notch creep test under the conditions of 80°C and 6 MPa of 40 hours or more. Characteristic (5): Mw / Mn measured by GPC of less than 12. Characteristic (6): shear viscosity at 230°C and a shear rate of 243 sec-1 of 7,000 poise or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyethylene resin composition and a molded article using the same. More specifically, the present invention relates to a polyethylene resin composition for injection molding and a molded article obtained by injection molding the polyethylene resin composition. [Background technology]

[0002] Polyethylene resins are excellent in moldability and various physical properties, and are highly economical and environmentally friendly, making them highly valued as materials in a wide range of technical fields and used in a wide variety of applications. In order to obtain polyethylene resins that meet the requirements of various applications, various techniques have been proposed for combining two or more resin components to control the molecular weight distribution and composition of the polymer and improve various physical properties, moldability, appearance, etc. of the resins or molded articles. The present applicant has disclosed, as polyethylene resin compositions comprising a combination of two or more polyethylene resin components, a polyethylene resin composition for container closures (Patent Document 1), a polyethylene resin composition suitable for blow-molded products (Patent Document 2), and a polyethylene resin composition for thin-walled containers (Patent Document 3).

[0003] Polyethylene resin is also used in the field of automotive fuel tanks due to its low cost, high strength, good weather resistance, good chemical resistance, and recyclability. Meanwhile, electric vehicles such as plug-in hybrid vehicles (PHEVs) and range-extender electric vehicles can have smaller fuel tanks than gasoline-powered vehicles equipped with only an engine as a power source, so the increase in electric vehicles is expected to lead to further miniaturization of automotive fuel tanks. While plastic fuel tanks for automobiles have traditionally been produced mainly by blow molding, as automotive fuel tanks become smaller, there is a possibility that plastic fuel tanks made by injection molding will become more popular due to their molding cycle, stable quality, light weight, and cost reduction achieved by integral molding of internal components.

[0004] Although the polyethylene resin compositions disclosed in the above Patent Documents 1 to 3 can be used for injection molding, further improvements are required in terms of mechanical properties as materials for fuel tanks. On the other hand, in Patent Document 4, the present applicant has disclosed a polyethylene resin for injection-molded plastic fuel tanks, which has: (1) a density of 0.940 to 0.970 g / cm 3 (2) The high load melt flow rate (HLMFR) (test conditions: 190°C, 21.6 kg load) is 6 g / 10 min or more, and (3) the shear rate is 243 sec at 230°C. -1 (4) The shear viscosity at -40°C is 10,000 poise or less, and (5) the Charpy impact strength at -40°C is 5 kJ / m 2 The above is the above, and (5) a polyethylene resin having a rupture time of 80 hours or more in a full notch creep test (measured at 80°C and 6 MPa) is disclosed.

[0005] In addition, the applicant has disclosed in Patent Document 5 that polyethylene for injection molding for manufacturing automobile fuel tanks and the like has the following properties: (1) a density of 0.935 to 0.970 g / cm 3 (2) the HLMFR is 50 to 200 g / 10 min; (3) the weight ratio Wa (%) of the component (a) to the total weight of the high-molecular-weight polyethylene component (a) and the low-molecular-weight polyethylene component (b) and the density Da (g / cm 3 ) satisfies a specific formula, that is, the content of polyethylene component (a) is relatively high considering the density.

[0006] Patent Document 6 discloses a novel polyethylene having a molar mass distribution width (M W / M n ) is 7 to 15, and density is 0.942 to 0.954 g / cm 3 , weight average molar mass (M WThe polyethylene disclosed has a melt mass flow rate (MIE) of 1.0 to 3.0 g / 10 min at 190°C and a load of 2.16 kg, a melt mass flow rate (MIF) of 100 to 200 g / 10 min at 190°C and a load of 21.6 kg, and an MIF / MIE ratio of 40 to 50.

[0007] Furthermore, in Patent Document 7, the applicant discloses a polyethylene resin composition for use in injection stretch blown containers, which has (1) an MFR of more than 1.0 g / 10 min and not more than 5.0 g / 10 min, (2) an HLMFR of 30 g / 10 min or more and 300 g / 10 min or less, (3) a melt flow rate ratio (HLMFR / MFR) of 10 or more and 60 or less, and (4) a density of 0.940 g / cm 3 More than 0.965g / cm 3 (5) a number average molecular weight (Mn) of 8,600 or more and a weight average molecular weight (Mw) of 91,000 or more, as measured by gel permeation chromatography (GPC); and (6) a branching index of 2.34 or more, calculated by a specific formula using the number of branches per 1,000 carbon atoms of each component at molecular weights of 50,000, 100,000, 200,000, 300,000, and 400,000, as measured by GPC-IR.

[0008] However, conventional polyethylene resin compositions have good fluidity during injection molding but are insufficient in impact resistance or durability for use in fuel tanks, or have good impact resistance and durability but are insufficient in fluidity during injection molding. Therefore, there is a demand for polyethylene resin compositions that have an excellent balance between injection moldability and impact resistance and durability. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-189472 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-208817 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-241034 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-114819 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-183338 [Patent Document 6] Special Publication No. 2016-533411 [Patent Document 7] Japanese Patent Publication No. 2022-016268 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a polyethylene resin composition that is excellent in injection moldability, impact resistance, and durability, and to provide a molded article obtained by injection molding the polyethylene resin composition. [Means for solving the problem]

[0011] Means for Solving the Problems The present inventors have conducted extensive research to solve the above problems and have found that a polyethylene resin composition satisfying specific properties has an excellent balance between injection moldability, impact resistance, and durability, thereby completing the present invention.

[0012] The polyethylene resin composition of the present invention comprises, as an essential component, one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 to 12 carbon atoms, The polyethylene resin composition satisfies the following properties (1) to (6). Property (1): The high load melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 10 g / 10 min or more and 200 g / 10 min or less. Property (2): Density is 0.945g / cm 3 More than 0.970g / cm 3 The following is the result. Property (3): Charpy impact strength at -40°C is 6.0kJ / m 2That's all. Property (4): The time to rupture in a full notch creep test at 80°C and 6 MPa is 40 hours or more. Property (5): The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is less than 12. Properties (6): 230℃, shear rate 243sec -1 The shear viscosity is 7000 poise or less.

[0013] The polyethylene resin composition of the present invention comprises, as the ethylene polymer, the following polyethylene component (a) polymerized with a metallocene catalyst, and the following polyethylene component (b) polymerized with a metallocene catalyst or a Ziegler-Natta catalyst, The polyethylene resin composition is preferably such that the proportion of the polyethylene component (a) is 20% by mass or more and 45% by mass or less, and the proportion of the polyethylene component (b) is 55% by mass or more and 80% by mass or less, relative to 100% by mass of the total of the polyethylene components (a) and (b). Polyethylene component (a); Property (a1): High load melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 1.0 g / 10 min or more; Characteristics (A2): Density is 0.910cm 3 More than 0.930g / cm 3 An ethylene-based polymer, which is: polyethylene component (b); Property (b1): The melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg is 5.0 g / 10 min or more and 50.0 g / 10 min or less, Property (b2): Density is 0.950 cm 3 More than 0.980g / cm 3 An ethylene-based polymer, which is:

[0014] The polyethylene resin composition of the present invention is preferably used as a polyethylene resin composition for injection molding.

[0015] The molded article of the present invention is a molded article obtained by injection molding the polyethylene resin composition of the present invention. The molded article of the present invention can be suitably used as at least one selected from the group consisting of a fuel tank, an oil tank, a urea water tank, and a welded part. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a polyethylene resin composition that is excellent in injection moldability, impact resistance, and durability. Furthermore, according to the present invention, by injection molding the polyethylene resin composition, a molded article having excellent impact resistance and durability can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0017] I. Polyethylene resin composition The polyethylene resin composition of the present invention comprises, as an essential component, one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 to 12 carbon atoms, It is characterized by satisfying the following properties (1) to (6). Property (1): The high load melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 10 g / 10 min or more and 200 g / 10 min or less. Property (2): Density is 0.945g / cm 3 More than 0.970g / cm 3 The following is the result. Property (3): Charpy impact strength at -40°C is 6.0kJ / m 2 That's all. Property (4): The time to rupture in a full notch creep test at 80°C and 6 MPa is 40 hours or more. Property (5): The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is less than 12. Properties (6): 230℃, shear rate 243sec -1 The shear viscosity is 7000 poise or less.

[0018] The polyethylene resin composition of the present invention is adjusted to satisfy the above properties (1) to (6), and therefore has an excellent balance between injection moldability, impact resistance, and durability. The present invention will be described in detail below for each item. In the present invention, polyethylene refers collectively to ethylene homopolymers and copolymers of ethylene with olefins described below, and can also be referred to as ethylene-based polymers. In addition, in this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower limit and upper limit.

[0019] 1. Characteristics of polyethylene resin composition Characteristics (1) The polyethylene resin composition of the present invention has a high load melt flow rate (HLMFR) of 10 g / 10 min or more and 200 g / 10 min or less at a temperature of 190° C. and a load of 21.6 kg. The lower limit of the HLMFR is preferably 20 g / 10 min or more, more preferably 30 g / 10 min or more, and particularly preferably 50 g / 10 min or more, and the upper limit of the HLMFR is preferably 150 g / 10 min or less, more preferably 100 g / 10 min or less, and particularly preferably 80 g / 10 min or less. If the HLMFR is less than 10 g / 10 min, the flowability may decrease, which may result in poor injection moldability, whereas if the HLMFR is more than 200 g / 10 min, the impact resistance and durability may become insufficient. In the present invention, HLMFR can be measured in accordance with JIS K6922-1 (2018). The HLMFR of the polyethylene resin composition can be adjusted by the amount of hydrogen and temperature during polymerization of each ethylene polymer component constituting the polyethylene resin composition, as well as the blending amount of each component.

[0020] Characteristics (2) The polyethylene resin composition of the present invention has a density of 0.945 g / cm 3 More than 0.970g / cm 3 The lower limit of the density is preferably 0.945 g / cm 3 The upper limit of the density is preferably 0.960 g / cm 3 or less, more preferably 0.950 g / cm 3 The following is the result. Density is 0.945g / cm 3 On the other hand, if the density is less than 0.970 g / cm3, the rigidity may be insufficient. 3 If the temperature exceeds this range, the impact resistance and durability may become insufficient. In the present invention, the density can be measured in accordance with JIS K7112 (2023). The density can be adjusted by the amount of α-olefin used during polymerization of each ethylene polymer component constituting the polyethylene resin composition, and can also be adjusted by the blending amount of each component.

[0021] Characteristics (3) The polyethylene resin composition of the present invention has a Charpy impact strength of 6.0 kJ / m at -40°C. 2 As a result, the impact resistance is excellent. The upper limit of the Charpy impact strength is not particularly limited, but is usually 100 kJ / m 2 less than 10.0 kJ / m 2 or less, or 7.0 kJ / m 2 It may be the following: In the present invention, the Charpy impact strength at -40°C is measured by preparing a test specimen in accordance with JIS K6922-2 (2018) "Plastics - Polyethylene (PE) molding and extrusion materials - Part 2: Preparation of test specimens and determination of properties" and measuring the strength in accordance with JIS K7111-1 (2012) "Plastics - Determination of Charpy impact properties - Part 1: Non-instrumented impact test." The Charpy impact strength at −40°C can be increased by decreasing the MFR or narrowing the molecular weight distribution of each ethylene polymer component constituting the polyethylene resin composition. Furthermore, the Charpy impact strength at −40°C can be adjusted by the type of catalyst used in the polymerization of each ethylene polymer component constituting the polyethylene resin composition. More specifically, in a polyethylene resin composition containing a combination of polyethylene component (a) and polyethylene component (b) described below, it is preferred to use polyethylene component (b) polymerized with a metallocene catalyst or polyethylene component (b) polymerized with a Ziegler-Natta catalyst, and further use polyethylene component (a) satisfying property (a1-1) described below, so that polyethylene component (b) satisfies property (b1-1) described below.

[0022] Characteristics (4) The polyethylene resin composition of the present invention has excellent durability since it has a time to rupture of 40 hours or more in a full notch creep test (FNCT) under conditions of 80°C and 6 MPa. The lower limit of the time to rupture in the FNCT is preferably 60 hours or more, more preferably 80 hours or more, and particularly preferably 100 hours or more. On the other hand, the upper limit of the fracture time in the FNCT is not particularly limited, but is usually 200 hours or less. In this invention, the rupture time in a full notch creep test (FNCT) at 80°C and 6 MPa is measured in accordance with the full notch tensile creep test in Appendix JC of JIS K6774 (2022) "Polyethylene Pipe for Gas" at 80°C and 6 MPa. The test specimens used were cut from a 6 mm thick compression-molded sheet prepared under the conditions in Table 2 of JIS K6922-2 (2018) "Plastics - Polyethylene (PE) Materials for Molding and Extrusion - Part 2: Preparation of Test Specimens and Determination of Properties," and notched all around (test specimen thickness 6 mm, notch depth 1 mm, all around). The time to break in FNCT (test conditions: 80°C, 6 MPa) can generally be increased by decreasing the density of the polyethylene. Furthermore, the time to break in FNCT (test conditions: 80°C, 6 MPa) can be adjusted by the type of catalyst used in the polymerization of each ethylene polymer component constituting the polyethylene resin composition and the melt flow rate of each ethylene polymer component. More specifically, in a polyethylene resin composition containing a combination of polyethylene component (a) and polyethylene component (b) described below, it is preferred to use polyethylene component (b) polymerized with a metallocene catalyst, or polyethylene component (b) polymerized with a Ziegler-Natta catalyst, and further use polyethylene component (a) satisfying property (a1-1) described below, so that polyethylene component (b) satisfies property (b1-1) described below. Furthermore, the time to break in FNCT (test conditions: 80°C, 6 MPa) can be adjusted by the ratio of each ethylene polymer component constituting the polyethylene resin composition.

[0023] Characteristics (5) The polyethylene resin composition of the present invention has a molecular weight distribution, expressed as the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), measured by gel permeation chromatography (GPC), of less than 12, and preferably less than 10. If the Mw / Mn is 12 or more, the impact resistance or durability may be insufficient. The lower limit of the Mw / Mn ratio is not particularly limited, but is preferably 2 or more, more preferably 4 or more, from the viewpoint of injection moldability. The molecular weight distribution (Mw / Mn) of the polyethylene resin composition can be adjusted to a predetermined range mainly by selecting a polymerization catalyst and polymerization conditions when polymerizing each ethylene polymer component constituting the polyethylene resin composition, or by mixing multiple components having different molecular weights. The Mn and Mw of the polyethylene resin composition can be adjusted by adjusting the temperature and hydrogen concentration during polymerization of each ethylene polymer component constituting the polyethylene resin composition, and Mn and Mw can be increased by lowering the polymerization temperature or the hydrogen concentration.

[0024] Characteristics(6) The polyethylene resin composition of the present invention was heated at 230°C and a shear rate of 243 sec -1 Since the shear viscosity at room temperature is 7000 poise or less, it exhibits sufficient fluidity during injection molding and has excellent injection moldability. 230℃, shear rate 243sec -1 The shear viscosity at is measured by a Capillograph manufactured by Toyo Seiki Seisakusho using a nozzle with a diameter of 1.0 mm and a length of 40 mm. The shear viscosity of the polyethylene resin composition can be increased by decreasing the MFR of each ethylene polymer component constituting the polyethylene resin composition. Furthermore, the shear viscosity of the polyethylene resin composition can be adjusted by the type of catalyst used in the polymerization of each ethylene polymer component constituting the polyethylene resin composition. More specifically, in a polyethylene resin composition containing a combination of polyethylene component (a) and polyethylene component (b) described below, it is preferred to use polyethylene component (b) polymerized with a metallocene catalyst, or polyethylene component (b) polymerized with a Ziegler-Natta catalyst, and further use polyethylene component (a) satisfying property (a1-1) described below, so that polyethylene component (b) satisfies property (b1-1) described below.

[0025] 2. Constitution of polyethylene resin composition The polyethylene resin composition of the present invention contains, as an essential component, one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 to 12 carbon atoms. In order to make the polyethylene resin composition more likely to satisfy the above properties (1) to (6) simultaneously, the ethylene polymer preferably contains the following polyethylene component (a) polymerized with a metallocene catalyst, and the following polyethylene component (b) polymerized with a metallocene catalyst or a Ziegler-Natta catalyst. Polyethylene component (a); Property (a1): High load melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 1.0 g / 10 min or more; Characteristics (A2): Density is 0.910cm 3 More than 0.930g / cm 3 An ethylene-based polymer, which is: polyethylene component (b); Property (b1): The melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg is 5.0 g / 10 min or more and 50.0 g / 10 min or less, Property (b2): Density is 0.950 cm 3 More than 0.980g / cm 3 An ethylene-based polymer, which is:

[0026] In the polyethylene resin composition of the present invention, the compositional proportions of the polyethylene component (a) and the polyethylene component (b) are, from the viewpoint of easily satisfying the properties (1) to (6) above, preferably such that, relative to 100% by mass of the total of the polyethylene component (a) and the polyethylene component (b), the proportion of the polyethylene component (a) is 20% by mass or more and 45% by mass or less and the proportion of the polyethylene component (b) is 55% by mass or more and 80% by mass or less; more preferably such that the proportion of the polyethylene component (a) is 25% by mass or more and 45% by mass or less and the proportion of the polyethylene component (b) is 55% by mass or more and 75% by mass or less; and even more preferably such that the proportion of the polyethylene component (a) is 25% by mass or more and 35% by mass or less and the proportion of the polyethylene component (b) is 65% by mass or more and 75% by mass or less.

[0027] The polyethylene resin composition of the present invention may further contain optional components described below in addition to the polyethylene component (a) and the polyethylene component (b), as long as the properties (1) to (6) are simultaneously satisfied. When the polyethylene resin composition of the present invention contains optional components described below, the total content of the polyethylene component (a) and the polyethylene component (b) per 100 parts by mass of the polyethylene resin composition is appropriately adjusted so as to simultaneously satisfy the properties (1) to (6) above, and is not particularly limited, but is preferably 90 parts by mass or more, more preferably 95 parts by mass or more, and even more preferably 99 parts by mass or more, from the viewpoints of the injection moldability, impact resistance, and durability of the polyethylene resin composition.

[0028] Further, specific preferred examples of the polyethylene resin composition of the present invention include a polyethylene resin composition comprising a polyethylene component (a) polymerized by a metallocene catalyst and satisfying the following properties (a1) and (a2), and a polyethylene component (b) polymerized by a metallocene catalyst and satisfying the following properties (b1) and (b2); and a polyethylene resin composition comprising a polyethylene component (a) polymerized by a metallocene catalyst and satisfying the following properties (a1-1) and (a2), and a polyethylene component (b) polymerized by a Ziegler-Natta catalyst and satisfying the following properties (b1-1) and (b2).

[0029] 2-1. Polyethylene component (a) Characteristics (a1) The polyethylene component (a) used in the present invention has a high load melt flow rate (HLMFR) of 1.0 g / 10 min or more at a temperature of 190° C. and a load of 21.6 kg. When the polyethylene component (a) has an HLMFR of 1.0 g / 10 min or more, the polyethylene resin composition has sufficient fluidity and tends to have good injection moldability. The preferred range of the HLMFR of the polyethylene component (a) varies depending on the type of catalyst used in the polymerization of the polyethylene component (b) used in combination. When the polyethylene component (b) is an ethylene polymer polymerized using a metallocene catalyst, the lower limit of the HLMFR of the polyethylene component (a) may be 1.0 g / 10 min or more, and the upper limit is not particularly limited, but is preferably 30 g / 10 min or less, more preferably 25 g / 10 min or less, and even more preferably 20 g / 10 min or less, from the viewpoint of improving the durability of the polyethylene resin composition. On the other hand, when the polyethylene component (b) is an ethylene polymer polymerized with a Ziegler-Natta catalyst, the polyethylene component (a) preferably satisfies the following property (a1-1). Property (a1-1): The high load melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 5.0 g / 10 min or more. In the polyethylene component (a) satisfying the property (a1-1), the upper limit of the HLMFR is not particularly limited, but is preferably 25 g / 10 min or less, and more preferably 20 g / 10 min or less, in order to improve the durability of the polyethylene resin composition. In this way, by adjusting the HLMFR of the polyethylene component (a) to the above-mentioned lower limit or more depending on the type of catalyst used in polymerization of the polyethylene component (b) used in combination, the polyethylene resin composition has good flowability, improved injection moldability, and further good impact resistance and durability, and can easily satisfy properties (3), (4), and (6). The HLMFR of the polyethylene component (a) can be adjusted mainly by the amount of hydrogen and the polymerization temperature during polymerization of the polyethylene component (a).

[0030] Characteristics (a2) The polyethylene component (a) used in the present invention has a density of 0.910 cm 3 More than 0.930g / cm 3 The lower limit of the density of the polyethylene component (a) is preferably 0.915 g / cm 3 The upper limit of the density is preferably 0.925 g / cm 3 The following is the result. When the density is equal to or greater than the lower limit, the polyethylene resin composition is likely to achieve the density range described above and tend to have good rigidity, whereas when the density is equal to or less than the upper limit, the polyethylene resin composition is likely to have good impact resistance and durability. The density can be adjusted mainly by the amount of α-olefin used during polymerization of the polyethylene component (a).

[0031] The polyethylene component (a) used in the present invention is produced by homopolymerizing ethylene or copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms using a metallocene catalyst. Examples of metallocene catalysts include those that combine a co-catalyst with a complex called a metallocene complex, in which a ligand having a cyclopentadiene skeleton is coordinated to a transition metal. Specific metallocene catalysts include those that combine a metallocene complex in which a ligand having a cyclopentadiene skeleton, such as methylcyclopentadiene, dimethylcyclopentadiene, or indene, is coordinated to a transition metal such as Ti, Zr, or Hf, with an organometallic compound of an element from Groups 1 to 3 of the periodic table, such as aluminoxane, as a co-catalyst, and supported catalysts in which these complex catalysts are supported on a carrier such as silica. The metallocene catalyst used in the present invention is preferably a catalyst having a metallocene complex of a specific structure, and particularly preferably a metallocene complex having a cyclopentadienyl ring and a heterocyclic aromatic group, or a metallocene complex having a cyclopentadienyl ring and a fluorenyl ring. The metallocene catalyst used in the present invention is preferably a metallocene catalyst containing Ti, Zr or Hf.

[0032] The metallocene catalyst preferably used in the present invention is a catalyst comprising the following catalyst component (i) and catalyst component (ii), optionally in combination with catalyst component (iii). Catalyst component (i): metallocene complex Catalyst component (ii): a compound that reacts with catalyst component (i) to form a cationic metallocene compound Catalyst component (iii): fine particle support

[0033] (1) Catalyst component (i) The catalyst component (i) is a metallocene compound of a transition metal of Group 4 of the periodic table, specifically, a compound represented by the following general formulas (I) to (VII).

[0034] (C5H 5-a R 1 a )(C5H 5-b R 2 b )MXY General formula (I) Q 1 (C5H 4-c R 1 c )(C5H 4-d R 2 d )MXY General formula (II) Q 2 (C5H 4-e R 3 e )ZMXY General formula (III) (C5H 5-f R 3 f )ZMXY General formula (IV) (C5H 5-f R 3 f )MXYW General formula (V) Q 3 (C5H 5-g R 4 g )(C5H 5-h R 5 h )MXY General formula (VI) Q 4 Q 5 (C5H 3-i R 6 i )(C5H 3-j R 7 j )MXY General formula (VII)

[0035] Here, Q 1 , Q 4 , Q 5represents a bonding group that bridges two conjugated five-membered ring ligands, and Q 2 represents a linking group that bridges the conjugated five-membered ring ligand and the Z group, and Q represents a linking group that bridges the conjugated five-membered ring ligand and the Z group. 3 is R 4 and R 5 M is a transition metal of Groups 3 to 12 of the periodic table; X, Y, and W each independently represent hydrogen, halogen, a hydrocarbon group of 1 to 20 carbon atoms, an oxygen-containing hydrocarbon group of 1 to 20 carbon atoms, a nitrogen-containing hydrocarbon group of 1 to 20 carbon atoms, a phosphorus-containing hydrocarbon group of 1 to 20 carbon atoms, or a silicon-containing hydrocarbon group of 1 to 20 carbon atoms; Z is a ligand containing oxygen or sulfur, a silicon-containing hydrocarbon group of 1 to 40 carbon atoms, a nitrogen-containing hydrocarbon group of 1 to 40 carbon atoms, or a phosphorus-containing hydrocarbon group of 1 to 40 carbon atoms. M is preferably a transition metal of Group 4 of the periodic table, such as Ti, Zr, or Hf.

[0036] R 1 ~R 7 are each independently a hydrocarbon group having 1 to 20 carbon atoms, a halogen group, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group, an aryloxy group, an oxygen-containing hydrocarbon group, a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, or a boron-containing hydrocarbon group. 1 ~R 5 Preferably, at least one of the heterocyclic aromatic groups is a heterocyclic aromatic group. Among heterocyclic aromatic groups, a furyl group, a benzofuryl group, a thienyl group, or a benzothienyl group is preferred, with a furyl group or a benzofuryl group being more preferred. These heterocyclic aromatic groups may have a hydrocarbon group having 1 to 20 carbon atoms, a halogen group, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, an oxygen-containing hydrocarbon group, a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, or a boron-containing hydrocarbon group, in which case a hydrocarbon group having 1 to 20 carbon atoms or a silicon-containing hydrocarbon group is preferred. In addition, when two adjacent R 1 , 2 R 2 , 2 R 3 , 2 R 4 , 2 R 5 , 2 R 6 , or two R 7may be bonded to each other to form a ring having 4 to 10 carbon atoms. a, b, c, d, e, f, g, h, i, and j are integers that satisfy the following conditions: 0≦a≦5, 0≦b≦5, 0≦c≦4, 0≦d≦4, 0≦e≦4, 0≦f≦5, 0≦g≦5, 0≦h≦5, 0≦i≦3, 0≦j≦3.

[0037] A linking group Q bridging two conjugated five-membered ring ligands 1 , Q 4 , Q 5 , a bonding group Q bridging the conjugated five-membered ring ligand and the Z group 2 , and R 4 and R 5 Q 3 Specific examples of the alkylene group include: alkylene groups such as a methylene group and an ethylene group; alkylidene groups such as an ethylidene group, a propylidene group, an isopropylidene group, a phenylmethylidene group, and a diphenylmethylidene group; silicon-containing crosslinking groups such as a dimethylsilylene group, a diethylsilylene group, a dipropylsilylene group, a diphenylsilylene group, a methylethylsilylene group, a methylphenylsilylene group, a methyl-t-butylsilylene group, a disilylene group, and a tetramethyldisilylene group; germanium-containing crosslinking groups; alkylphosphines; and amines. Of these, alkylene groups, alkylidene groups, silicon-containing crosslinking groups, and germanium-containing crosslinking groups are particularly preferred.

[0038] Specific examples of Zr complexes represented by the general formulas (I), (II), (III), (IV), (V), (VI), and (VII) include the compounds described in paragraphs 0045 to 0055 of JP 2017-179304 A, and compounds in which Zr in these specific examples is replaced with Hf or Ti can also be used. Furthermore, the metallocene complexes represented by the general formulas (I), (II), (III), (IV), (V), (VI), and (VII) can be used as a mixture of two or more compounds represented by the same general formula or different general formulas.

[0039] Among the catalyst components (i) described above, preferred metallocene complexes for producing the polyethylene component (a) are metallocene complexes represented by general formula (I) or general formula (II), and among these, metallocene complexes having a cyclopentadienyl ring and a heterocyclic aromatic group are preferred, and metallocene complexes having an indenyl ring skeleton are even more preferred. From the viewpoints of being able to produce high molecular weight polymers and having excellent copolymerizability in copolymerization of ethylene with other α-olefins, metallocene complexes represented by general formula (II) are preferred, and metallocene complexes represented by general formula (II) having an indenyl ring skeleton are most preferred. The ability to produce high molecular weight polymers has the advantage of allowing the design of polymers with a variety of molecular weights. Furthermore, from the viewpoint of being able to produce polyethylene with a high molecular weight and long chain branches, the following compound group is preferred among the metallocene complexes represented by general formula (II).

[0040] In one preferred embodiment, the group of compounds is R 1 and R 2 The present invention relates to a bridged metallocene complex containing at least one heterocyclic aromatic group in the compound as at least one of the above. Preferred heterocyclic aromatic groups include a group consisting of a furyl group, a benzofuryl group, a thienyl group, and a benzothienyl group. These substituents may further have a substituent such as a silicon-containing group. Among the substituents selected from the group consisting of a furyl group, a benzofuryl group, a thienyl group, and a benzothienyl group, a furyl group and a benzofuryl group are more preferred. Furthermore, it is preferred that these substituents are introduced at the 2-position of a substituted cyclopentadienyl group or a substituted indenyl group, and a compound having at least one substituted cyclopentadienyl group that does not have any other fused ring structure is particularly preferred.

[0041] By using these compounds as metallocene complexes and by employing specific polymerization conditions, the polyethylene component (a) preferred in the present invention can be easily produced.

[0042] These metallocene complexes are preferably used as supported catalysts as described below. In the above-mentioned compounds, it is believed that the interaction between the so-called heteroatoms contained in the furyl or thienyl groups and the solid acid on the support causes heterogeneity in the active site structure, making it easier to generate long chain branches.

[0043] (2) Catalyst component (ii) The metallocene catalyst used in the present invention preferably contains, in addition to the above-mentioned catalyst component (i), a compound (catalyst component (ii)) that reacts with the metallocene compound of the catalyst component (i) to form a cationic metallocene compound, and, if necessary, a fine particle carrier (catalyst component (iii)).

[0044] One example of the catalyst component (ii) is an organoaluminum oxy compound. The organoaluminum oxy-compound has an Al-O-Al bond in its molecule, and the number of bonds is usually in the range of 1 to 100, preferably 1 to 50. Such an organoaluminum oxy-compound is usually a product obtained by reacting an organoaluminum compound with water. The reaction of an organoaluminum compound with water is usually carried out in an inert hydrocarbon (solvent). Examples of the inert hydrocarbon that can be used include aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, and xylene, but it is preferable to use an aliphatic hydrocarbon or an aromatic hydrocarbon.

[0045] The organoaluminum compound used in the preparation of the organoaluminum oxy-compound may be any of the compounds represented by the following general formula (VIII), but trialkylaluminum is preferably used. R a t AlX a 3-t General formula (VIII) (In general formula (VIII), R arepresents a hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, such as an alkyl group, an alkenyl group, an aryl group, or an aralkyl group; X a represents a hydrogen atom or a halogen atom, and t represents an integer of 1≦t≦3.

[0046] The alkyl group of the trialkylaluminum may be any of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl, decyl, and dodecyl groups, with methyl being particularly preferred. The organoaluminum compounds may be used in combination of two or more.

[0047] The reaction ratio of water to the organoaluminum compound (water / Al molar ratio) is preferably 0.25 / 1 to 1.2 / 1, and particularly preferably 0.5 / 1 to 1 / 1. The reaction temperature is usually in the range of -70 to 100°C, preferably -20 to 20°C. The reaction time is usually selected in the range of 5 minutes to 24 hours, preferably 10 minutes to 5 hours. The water required for the reaction may not only be simple water, but also water of crystallization contained in copper sulfate hydrate, aluminum sulfate hydrate, etc., or components that can generate water in the reaction system. Among the above-mentioned organoaluminum oxy compounds, those obtained by reacting alkylaluminum with water are usually called aluminoxanes, and methylaluminoxane (including those essentially consisting of methylaluminoxane (MAO)) is particularly suitable as an organoaluminum oxy compound. Of course, two or more of the above-mentioned organoaluminum oxy compounds may be used in combination as the organoaluminum oxy compound, or the organoaluminum oxy compound may be used in the form of a solution or dispersion in the above-mentioned inert hydrocarbon solvent.

[0048] Other specific examples of the catalyst component (ii) include borane compounds and borate compounds, such as those described in paragraphs 0065 to 0077 of JP 2017-179304 A.

[0049] Particularly preferred catalyst component (ii) is an organoaluminum oxy compound. By using these compounds as the catalyst component (ii) and by employing specific polymerization conditions, the polyethylene component (a) preferred in the present invention can be easily produced.

[0050] (3) Catalyst component (iii) The particulate support of catalyst component (iii) may be an inorganic support, a particulate polymer support, or a mixture thereof. The inorganic support may be a metal, a metal oxide, a metal chloride, a metal carbonate, a carbonaceous material, or a mixture thereof. Suitable metals that can be used for the inorganic support include, for example, iron, aluminum, nickel, and the like.

[0051] Furthermore, examples of metal oxides include single oxides or composite oxides of elements in Groups 1 to 14 of the periodic table, such as SiO2, Al2O3, MgO, CaO, B2O3, TiO2, ZrO2, Fe2O3, Al2O3·MgO, Al2O3·CaO, Al2O3·SiO2, Al2O3·MgO·CaO, Al2O3·MgO·SiO2, Al2O3·CuO, Al2O3·Fe2O3, Al2O3·NiO, and SiO2·MgO. Here, the above formula is not a molecular formula but represents only the composition, and the structure and catalytic component ratio of the composite oxide used in the present invention are not particularly limited. Furthermore, the metal oxide used in the present invention may absorb a small amount of moisture and may contain a small amount of impurities.

[0052] As the metal chloride, for example, chlorides of alkali metals and alkaline earth metals are preferred, and specifically, MgCl2, CaCl2, etc. are particularly suitable. As the metal carbonate, carbonates of alkali metals and alkaline earth metals are preferred, and specific examples include magnesium carbonate, calcium carbonate, and barium carbonate. Examples of carbonaceous materials include carbon black and activated carbon. Any of the above inorganic carriers can be suitably used in the present invention, but metal oxides, silica, alumina, etc. are particularly preferred.

[0053] These inorganic supports are preferably used after being calcined in air or an inert gas such as nitrogen or argon at 200 to 800°C, preferably 400 to 600°C, to adjust the amount of surface hydroxyl groups to 0.8 to 1.5 mmol / g. The properties of these inorganic carriers are not particularly limited, but usually, the average particle size is 5 to 200 μm, preferably 10 to 150 μm, the average pore size is 20 to 1000 Å, preferably 50 to 500 Å, and the specific surface area is 150 to 1000 m 2 / g, preferably 200 to 700m 2 / g, pore volume 0.3-2.5cm 3 / g, preferably 0.5 to 2.0 cm 3 / g, apparent specific gravity is 0.10 to 0.50 g / cm 3 It is preferable to use an inorganic carrier having the following formula:

[0054] The inorganic supports described above can be used as they are, but they can also be used after being pretreated by contacting them with an organoaluminum compound such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tripropylaluminum, tributylaluminum, trioctylaluminum, tridecylaluminum, or diisobutylaluminum hydride, or an organoaluminum oxy-compound containing an Al-O-Al bond.

[0055] Particularly preferred catalyst components (iii) include SiO2, Al2O3, and Al2O3·SiO2. By using these compounds as the catalyst component (iii) and by employing specific polymerization conditions, the polyethylene component (a) preferred in the present invention can be easily produced.

[0056] (4) Contact method, etc. In the metallocene catalyst preferably used in the present invention, the method for contacting the components when obtaining a catalyst comprising the catalyst component (i), the catalyst component (ii), and, if necessary, the catalyst component (iii) is not particularly limited, and for example, the following methods can be optionally adopted.

[0057] Contact method (1): The catalyst component (i) is contacted with the catalyst component (ii), and then the catalyst component (iii) is contacted. Contact method (2): The catalyst component (i) is contacted with the catalyst component (iii), and then the catalyst component (ii) is contacted. Contact method (3): The catalyst component (ii) is contacted with the catalyst component (iii), and then the catalyst component (i) is contacted.

[0058] Of these contact methods, contact methods (1) and (3) are preferred, with contact method (1) being most preferred. In any of these contact methods, the components are typically contacted in an inert atmosphere such as nitrogen or argon, with or without stirring, in the presence of a liquid inert hydrocarbon, typically an aromatic hydrocarbon (usually having 6 to 12 carbon atoms) such as benzene, toluene, xylene, or ethylbenzene, or an aliphatic or alicyclic hydrocarbon (usually having 5 to 12 carbon atoms) such as heptane, hexane, decane, dodecane, or cyclohexane. This contact is usually carried out at a temperature of -100°C to 200°C, preferably -50°C to 100°C, more preferably 0°C to 50°C, for 5 minutes to 50 hours, preferably 30 minutes to 24 hours, more preferably 30 minutes to 12 hours.

[0059] Furthermore, when catalyst component (i), catalyst component (ii) and catalyst component (iii) are contacted, as described above, either an aromatic hydrocarbon solvent in which some components are soluble or slightly soluble, or an aliphatic or alicyclic hydrocarbon solvent in which some components are insoluble or slightly soluble, can be used.

[0060] When the contact reactions of the components are carried out stepwise, the solvent used in the previous step may be used as it is in the subsequent contact reaction without removing it. Alternatively, after the previous contact reaction using a soluble solvent, a liquid inert hydrocarbon in which certain components are insoluble or poorly soluble (e.g., an aliphatic, alicyclic, or aromatic hydrocarbon such as pentane, hexane, decane, dodecane, cyclohexane, benzene, toluene, or xylene) may be added to recover the desired product as a solid. Alternatively, after partially or completely removing the soluble solvent by drying or other means to recover the desired product as a solid, the subsequent contact reaction of this desired product may be carried out using one of the above-mentioned inert hydrocarbon solvents. In the present invention, the contact reactions of the components may be carried out multiple times.

[0061] In the present invention, the proportions of catalyst component (i), catalyst component (ii) and catalyst component (iii) used are not particularly limited, but the following ranges are preferred.

[0062] When an organoaluminum oxy compound is used as catalyst component (ii), the atomic ratio (Al / M) of aluminum in the organoaluminum oxy compound to the transition metal (M) in catalyst component (i) is generally 1 to 100,000, preferably 5 to 1,000, and more preferably 50 to 200. When a borane compound or a borate compound is used, the atomic ratio (B / M) of boron to the transition metal (M) in the metallocene compound is generally 0.01 to 100, preferably 0.1 to 50, and more preferably 0.2 to 10. Furthermore, when a mixture of an organoaluminum oxy compound, a borane compound, and a borate compound is used as the catalyst component (ii), it is desirable to select the use ratio of each compound in the mixture relative to the transition metal (M) in the same manner as above.

[0063] The amount of catalyst component (iii) used is 1 g per 0.0001 to 5 mmol, preferably per 0.001 to 0.5 mmol, and more preferably per 0.01 to 0.1 mmol of the transition metal in catalyst component (i).

[0064] The metallocene catalyst can be obtained as a solid catalyst by contacting catalyst components (i), (ii), and (iii) with one another using any of the contact methods (1) to (3) and then removing the solvent. The solvent is desirably removed at atmospheric pressure or reduced pressure, at 0 to 200°C, preferably 20 to 150°C, for 1 minute to 50 hours, preferably 10 minutes to 10 hours.

[0065] The metallocene catalyst can also be obtained by the following method. Contact method (4): The catalyst component (i) is contacted with the catalyst component (iii) to remove the solvent, thereby obtaining a solid catalyst component, which is then contacted with an organoaluminum oxy compound, a borane compound, a borate compound, or a mixture thereof under polymerization conditions. Contact method (5): An organoaluminum oxy compound, a borane compound, a borate compound or a mixture thereof is contacted with catalyst component (iii) to remove the solvent, thereby forming a solid catalyst component, which is then contacted with catalyst component (i) under polymerization conditions. In the above contact methods (4) and (5), the component ratio, contact conditions, and solvent removal conditions can be the same as those described above.

[0066] Furthermore, a layered silicate can also be used as a component that serves as both the catalyst component (ii) and the catalyst component (iii). Layered silicates are silicate compounds that have a crystalline structure in which planes formed by ionic bonds or the like are stacked in parallel with each other with weak bonding forces. Most layered silicates occur naturally as the main component of clay minerals, but these layered silicates are not limited to those that are naturally occurring, and may also be artificially synthesized products.

[0067] Among these, smectites, vermiculites, and micas such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, and taeniolite are preferred.

[0068] Generally, natural products are often non-ion-exchangeable (non-swellable), and in such cases, it is preferable to subject them to treatment to impart ion-exchangeable (or swellable) properties to give them desirable ion-exchangeable (or swellable) properties. Among such treatments, the following chemical treatments are particularly preferred: Here, the chemical treatment can be either a surface treatment for removing impurities adhering to the surface or a treatment that affects the crystal structure and chemical composition of the layered silicate. Specific examples include (a) acid treatment using hydrochloric acid, sulfuric acid, etc., (b) alkali treatment using NaOH, KOH, NH3, etc., (c) salt treatment using salts consisting of a cation containing at least one atom selected from Groups 2 to 14 of the periodic table and at least one anion selected from the group consisting of anions derived from halogen atoms or inorganic acids, and (d) organic treatment using alcohols, hydrocarbon compounds, formamide, aniline, etc. These treatments may be carried out alone or in combination of two or more.

[0069] The particle properties of the layered silicate can be controlled by pulverization, granulation, sizing, fractionation, etc. at any time before, during, or after any of the steps. Any method suitable for the purpose can be used. In particular, examples of granulation methods include spray granulation, tumbling granulation, compression granulation, stirring granulation, briquetting, compaction, extrusion granulation, fluidized bed granulation, emulsion granulation, and submerged granulation. Of the above, particularly preferred granulation methods are spray granulation, tumbling granulation, and compression granulation.

[0070] The layered silicates described above can be used as they are, but they can also be used in combination with an organoaluminum compound such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, or diisobutylaluminum hydride, or an organoaluminum oxy compound containing an Al-O-Al bond.

[0071] In the metallocene catalyst preferably used in the present invention, the catalyst component (i) can be supported on the layered silicate by contacting the catalyst component (i) with the layered silicate, or by contacting the catalyst component (i), the organoaluminum compound, and the layered silicate with each other. The method for contacting the components is not particularly limited, and for example, the following methods can be optionally employed. Contact method (6): The catalyst component (i) is contacted with an organoaluminum compound, and then contacted with a layered silicate support. Contacting method (7): The catalyst component (i) is contacted with a layered silicate support, and then contacted with an organoaluminum compound. Contacting method (8): After contacting the organoaluminum compound with the layered silicate support, the resultant is contacted with the catalyst component (i).

[0072] Of these contacting methods, contacting methods (6) and (8) are preferred. In either contacting method, the components are typically contacted in an inert atmosphere such as nitrogen or argon, with or without stirring, in the presence of a liquid inert hydrocarbon, such as an aromatic hydrocarbon (usually having 6 to 12 carbon atoms) such as benzene, toluene, xylene, or ethylbenzene, or an aliphatic or alicyclic hydrocarbon (usually having 5 to 12 carbon atoms) such as heptane, hexane, decane, dodecane, or cyclohexane.

[0073] The proportions of the catalyst component (i), the organoaluminum compound, and the layered silicate support are not particularly limited, but the following ranges are preferred. The amount of the catalyst component (i) supported is usually 0.0001 to 5 mmol, preferably 0.001 to 0.5 mmol, and more preferably 0.01 to 0.1 mmol per gram of the layered silicate support. When an organoaluminum compound is used, the amount of Al supported is usually in the range of 0.01 to 100 mol, preferably 0.1 to 50 mol, and more preferably 0.2 to 10 mol.

[0074] The conditions for supporting and removing the solvent can be the same as those for the inorganic carrier described above. When a layered silicate is used as a component that serves as both the catalyst component (ii) and the catalyst component (iii), the polymerization activity is high, and the productivity of an ethylene polymer having long chain branches is improved. The metallocene catalyst thus obtained may be used after prepolymerizing the monomers, if necessary.

[0075] Metallocene catalysts can be produced by taking into consideration the "catalyst" and "raw material blending ratios and conditions" described in, for example, JP-A No. 2002-535339 and JP-A No. 2004-189869. The index of the polymer can be controlled by various polymerization conditions, for example, by the methods described in JP-A Nos. 2-269705 and 3-21607.

[0076] The polyethylene component (a) can be obtained by homopolymerizing ethylene or copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, or 1-octene. Copolymerization with a diene is also possible for the purpose of property modification. Examples of diene compounds used in this case include butadiene, 1,4-hexadiene, ethylidene norbornene, and dicyclopentadiene. The comonomer content during polymerization can be selected arbitrarily. For example, in the case of copolymerization of ethylene with an α-olefin having 3 to 12 carbon atoms, the α-olefin content in the ethylene-α-olefin copolymer is usually 0.001 to 40 mol%, preferably 0.001 to 30 mol%, more preferably 0.001 to 5 mol%, even more preferably 0.001 to 2 mol%, and even more preferably 0.02 to 1.5 mol%. The ethylene used in each polyethylene component of the present invention may be ethylene produced from crude oil derived from ordinary fossil fuels, or may be plant-derived ethylene. Examples of plant-derived ethylene and polyethylene include the ethylene and polymers thereof described in JP-A-2010-511634. Plant-derived ethylene and polymers thereof are carbon-neutral (do not use fossil fuels and do not contribute to an increase in atmospheric carbon dioxide), making it possible to provide environmentally friendly products.

[0077] The molecular weight of the produced polymer can be adjusted to some extent by changing the polymerization conditions such as the polymerization temperature and the molar ratio of the catalyst, but the molecular weight can be adjusted more effectively by adding hydrogen to the polymerization reaction system. Furthermore, a component for removing water, a so-called scavenger, may be added to the polymerization system without any problems. Examples of such scavengers include organoaluminum compounds such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, the organoaluminum oxycompounds, modified organoaluminum compounds containing branched alkyl groups, organozinc compounds such as diethylzinc and dibutylzinc, organomagnesium compounds such as diethylmagnesium, dibutylmagnesium, and ethylbutylmagnesium, and Grignard compounds such as ethylmagnesium chloride and butylmagnesium chloride. Among these, triethylaluminum, triisobutylaluminum, and ethylbutylmagnesium are preferred, with triethylaluminum being particularly preferred. The present invention can also be applied without any problems to a multi-stage polymerization method having two or more stages in which the polymerization conditions such as hydrogen concentration, amount of monomer, polymerization pressure, polymerization temperature, etc. are different from each other.

[0078] The polyethylene component (a) can be produced by a production process such as gas phase polymerization, solution polymerization, or slurry polymerization, with slurry polymerization being preferred. Among the polymerization conditions for the polyethylene component (a), the polymerization temperature can be selected from the range of 0 to 200°C. In slurry polymerization, the polymerization is carried out at a temperature lower than the melting point of the resulting polymer. The polymerization pressure can be selected from the range of atmospheric pressure to approximately 10 MPa. The polyethylene component (a) can be produced by slurry polymerization of ethylene and an α-olefin in the presence of an inert hydrocarbon solvent selected from aliphatic hydrocarbons such as hexane, heptane, and isobutane; aromatic hydrocarbons such as benzene, toluene, and xylene; and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, in a state substantially free of oxygen, water, and the like.

[0079] The polyethylene component (a) may be prepared by polymerization in a single polymerization vessel, or in a plurality of reactors connected in series or parallel in a continuous manner, or may be prepared by mixing a plurality of ethylene polymers which have been polymerized separately, as long as the polyethylene component (a) satisfies the range specified in the present invention.

[0080] 2-2. Polyethylene component (b) Characteristics (b1) The polyethylene component (b) used in the present invention has a melt flow rate (MFR) of 5.0 g / 10 min or more and 50.0 g / 10 min or less at a temperature of 190° C. and a load of 2.16 kg. The preferred range of the MFR of the polyethylene component (b) varies depending on the type of catalyst used in the polymerization of the polyethylene component (b). The lower limit of the MFR of the polyethylene component (b) polymerized with a metallocene catalyst is preferably 6.0 g / 10 min or more, more preferably 8.0 g / 10 min or more, and the upper limit of the MFR is preferably 50.0 g / 10 min or less, more preferably 40.0 g / 10 min or less, and even more preferably 30.0 g / 10 min or less. On the other hand, the polyethylene component (b) polymerized with a Ziegler-Natta catalyst preferably satisfies the following property (b1-1). Property (b1-1): The melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg is 5.0 g / 10 min or more and 15.0 g / 10 min or less. In the polyethylene component (b) satisfying the property (b1-1), the lower limit of the MFR is preferably 6.0 g / 10 min or more, more preferably 8.0 g / 10 min or more, and the upper limit of the MFR is preferably 10.0 g / 10 min or less. When the MFR of the polyethylene component (b) is at least the lower limit, the molecular weight of the polyethylene component (b) does not become too large, and the flowability and injection moldability of the polyethylene resin composition tend to be good. On the other hand, when the MFR of the polyethylene component (b) is at most the upper limit, deterioration of impact resistance due to the influence of low-molecular-weight components, i.e., the polyethylene component (b), is suppressed. Thus, by adjusting the MFR of the polyethylene component (b) within the above range depending on the type of catalyst used in the polymerization of the polyethylene component (b), the polyethylene resin composition has good flowability, improved injection moldability, and further good impact resistance and durability, and therefore can easily satisfy properties (3), (4), and (6). The MFR of the polyethylene component (b) can be adjusted mainly by the amount of hydrogen and the polymerization temperature during polymerization of the polyethylene component (b).

[0081] Characteristics (b2) The polyethylene component (b) used in the present invention has a density of 0.950 g / cm 3 More than 0.980g / cm 3 The lower limit of the density of the polyethylene component (b) is preferably 0.960 g / cm 3 The upper limit of the density is preferably 0.970 g / cm 3 The following is the result. When the density of the polyethylene component (b) is equal to or greater than the lower limit, the density range of the polyethylene resin composition is easily achieved, and the rigidity is likely to be good. On the other hand, when the density is equal to or less than the upper limit, the impact resistance and durability of the polyethylene resin composition are likely to be good. The density of the polyethylene component (b) can be adjusted mainly by the amount of α-olefin used during polymerization of the polyethylene component (b).

[0082] Characteristics (b3) The polyethylene component (b) preferably further satisfies the following property (b3). Property (b3): ​​The molecular weight distribution, expressed as the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), measured by gel permeation chromatography (GPC) is 1 or more and 10 or less. The molecular weight distribution (Mw / Mn) of the polyethylene component (b) polymerized with a metallocene catalyst is more preferably 1 or more and less than 5, and even more preferably 2 or more and 4 or less. On the other hand, the molecular weight distribution (Mw / Mn) of the polyethylene component (b) polymerized with a Ziegler-Natta catalyst is more preferably 5 or more and 10 or less, and even more preferably 6 or more and 8 or less. It is preferable that the molecular weight distribution (Mw / Mn) of the polyethylene component (b) used in the present invention is at least the above lower limit, because the flowability of the polyethylene resin composition is improved, resulting in good injection moldability, and the compatibility of the ethylene polymer components constituting the polyethylene resin composition is improved, making it easier to suppress deterioration in physical properties such as impact resistance and durability. On the other hand, when the molecular weight distribution (Mw / Mn) of the polyethylene component (b) is not more than the above upper limit, it is easier to make the impact resistance of the polyethylene resin composition good.

[0083] The polyethylene component (b) used in the present invention is produced by homopolymerizing ethylene or copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms using a metallocene catalyst or a Ziegler-Natta catalyst. The polyethylene component (b) can be produced using a metallocene catalyst in accordance with the above-mentioned method for producing the polyethylene component (a).

[0084] The Ziegler-Natta catalyst used in the production of the polyethylene component (b) may be a conventionally known catalyst and is not particularly limited. Examples of Ziegler-Natta catalysts include catalysts containing a transition metal compound such as titanium chloride and an organometallic compound such as trialkylaluminum. More specific examples include those containing a solid catalyst component containing titanium, magnesium, and halogen atoms, and optionally an electron donor compound, in combination with an organoaluminum compound or an electron donor compound as an external donor. Examples of the electron donor compound include organic compounds containing oxygen or nitrogen atoms. Specific examples include ethers, esters, ketones, acid halides, aldehydes, amines, amides, nitriles, isocyanates, and organosilicon compounds. Ziegler-Natta catalysts also include those obtained by treating titanium trichloride or a titanium trichloride composition obtained by reduction with an organoaluminum compound or the like with an electron donor compound to further activate it, and so-called supported catalysts obtained by supporting titanium tetrachloride on a carrier such as a magnesium compound. As the Ziegler-Natta catalyst used in the production of polyethylene component (b), such supported catalysts are preferably used. The Ziegler-Natta catalyst may further contain a metal halide such as aluminum trichloride or an acid halide such as phthalic acid dichloride as a reaction accelerator.

[0085] In the production of polyethylene component (b) using a Ziegler-Natta catalyst, the method for controlling the molecular weight of the produced polymer, the polymerization method, and the polymerization conditions may be the same as those in the production method of polyethylene component (a) using the above-mentioned metallocene catalyst. Furthermore, in the production of polyethylene component (b) using a Ziegler-Natta catalyst, a multi-stage polymerization method may also be adopted.

[0086] The polyethylene component (b) can be obtained by copolymerizing ethylene with a homopolymer of ethylene or an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, or 1-octene. Copolymerization with a diene is also possible for the purpose of modification. Examples of the diene compound used in this case include butadiene, 1,4-hexadiene, ethylidene norbornene, and dicyclopentadiene. The polyethylene component (b) produced using a metallocene catalyst is preferably a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. In this case, the comonomer content during polymerization can be selected as desired, but for example, in the case of copolymerization of ethylene and an α-olefin having 3 to 12 carbon atoms, the α-olefin content in the ethylene-α-olefin copolymer is usually 0.001 to 40 mol%, preferably 0.001 to 30 mol%, more preferably 0.001 to 5 mol%, even more preferably 0.001 to 2 mol%, and still more preferably 0.02 to 1.5 mol%. On the other hand, the polyethylene component (b) produced using a Ziegler-Natta catalyst is preferably an ethylene homopolymer.

[0087] 3. Method for producing polyethylene resin composition The polyethylene resin composition of the present invention contains, as essential components, one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 to 12 carbon atoms, and the production method thereof is not particularly limited as long as it is possible to produce a polyethylene resin composition that satisfies the above properties (1) to (6). The polyethylene resin composition of the present invention is preferably produced by melt-mixing the polyethylene component (a) and the polyethylene component (b) in a predetermined blending ratio, and by adding other components as necessary and melt-mixing them, since this makes it easy to produce a resin composition that satisfies the properties (1) to (6) above.

[0088] In addition to the polyethylene component (a) and the polyethylene component (b), the polyethylene resin composition of the present invention may contain the following substances as optional components within the scope of the present invention. For example, various ethylene polymers and modified products thereof can be used, such as high-density polyethylene, low-density polyethylene, high-pressure polyethylene, polar monomer-grafted modified polyethylene, ethylene wax, ultra-high molecular weight polyethylene, and ethylene elastomer. The addition of high-density polyethylene is preferred for improving rigidity, heat resistance, impact strength, etc. The addition of low-density polyethylene is preferred for improving flexibility, impact strength, easy adhesion, transparency, low-temperature strength, etc. The addition of high-pressure polyethylene is preferred for improving flexibility, easy adhesion, transparency, low-temperature strength, moldability, etc. The addition of polar monomer-grafted modified polyethylene such as maleic acid-modified polyethylene, ethylene-acrylic acid derivative copolymer, or ethylene-vinyl acetate copolymer is preferred for improving flexibility, easy adhesion, colorability, compatibility with various materials, gas barrier properties, etc. The addition of ethylene-based wax is preferred for improving colorability, compatibility with various materials, moldability, etc. The addition of ultra-high molecular weight polyethylene is preferred for improving mechanical strength, abrasion resistance, etc. The addition of ethylene-based elastomer is preferred for improving flexibility, mechanical strength, impact strength, etc. When the polyethylene component (a) and the polyethylene component (b) that satisfy the specific balance of physical properties are mixed in specific amounts and used, a resin that acts as a compatibilizer for the polyethylene component (a), which is a high-molecular-weight component, and the polyethylene component (b), which is a low-molecular-weight component, may be further added as a third component. In addition to the above polymers, various resins can be used, specifically, various nylon resins, various polyamides, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), various polyesters, polycarbonate resins, EVOH, EVA, PMMA, PMA, various engineering plastics, polylactic acid, celluloses, natural rubbers, polyurethane, vinyl chloride, fluorine-based resins such as Teflon (registered trademark), inorganic polymers such as silicone resins, etc.

[0089] The polyethylene resin composition of the present invention can be pelletized by mechanical melt mixing using a pelletizer, homogenizer or the like in a conventional manner, and then molded into a desired molded article using various molding machines. Furthermore, the polyethylene resin composition obtained by the above-mentioned method can be blended, in accordance with a conventional method, with other olefin polymers, rubbers, and the like, as well as known additives such as antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, antifogging agents, antiblocking agents, processing aids, coloring pigments, crosslinking agents, foaming agents, inorganic or organic fillers, and flame retardants. As additives, for example, antioxidants (phenolic, phosphorus-based, sulfur-based), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, etc. can be used alone or in combination as appropriate. As fillers, calcium carbonate, talc, metal powders (aluminum, copper, iron, lead, etc.), silica stone, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used, and among these, calcium carbonate, talc, mica, etc. are preferred. In either case, various additives can be blended with the polyethylene resin composition as necessary, and the mixture can be kneaded using a kneading extruder, Banbury mixer, etc. to prepare a molding material.

[0090] In the present invention, a nucleating agent may be used to accelerate the crystallization rate of the polyethylene resin composition. The nucleating agent may be a commonly known one, and may be a general organic or inorganic nucleating agent, such as dibenzylidene sorbitol or a derivative thereof, an organic phosphoric acid compound or a metal salt thereof, an aromatic sulfonate or a metal salt thereof, an organic carboxylic acid or a metal salt thereof, a partial metal salt of rosin acid, inorganic fine particles such as talc, imides, amides, quinacridonequinones, or a mixture thereof. Among these, dibenzylidene sorbitol derivatives, organic metal phosphates, organic metal carboxylates, etc. are preferred because of their excellent transparency. Specific examples of dibenzylidene sorbitol derivatives include 1,3:2,4-bis(o-3,4-dimethylbenzylidene)sorbitol, 1,3:2,4-bis(o-2,4-dimethylbenzylidene)sorbitol, 1,3:2,4-bis(o-4-ethylbenzylidene)sorbitol, 1,3:2,4-bis(o-4-chlorobenzylidene)sorbitol, and 1,3:2,4-dibenzylidene sorbitol. Specific examples of metal benzoates include aluminum hydroxy-di(t-butylbenzoate).

[0091] When a nucleating agent is blended into the polyethylene resin composition of the present invention, the blending amount of the nucleating agent is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, still more preferably 0.01 to 1 part by mass, and particularly preferably 0.01 to 0.5 parts by mass, per 100 parts by mass of the composition. If the amount of the nucleating agent is less than 0.01 part by mass, the effect of improving high-speed moldability is insufficient, while if it exceeds 5 parts by mass, the nucleating agent tends to aggregate and form lumps, which is a problem.

[0092] 4. Method for molding polyethylene resin composition The polyethylene resin composition of the present invention can be formed into a molded article by a known molding method such as injection molding, blow molding, extrusion molding, etc., as needed. The polyethylene resin composition of the present invention has flowability suitable for injection molding and excellent injection moldability, and is therefore suitably used for injection molding, and can be injection molded at low temperature and high speed.

[0093] 5. Uses of polyethylene resin composition The polyethylene resin composition of the present invention has excellent injection moldability and is therefore suitable for use as a material for producing various molded articles by injection molding. Furthermore, the polyethylene resin composition of the present invention also has excellent impact resistance and durability and is therefore preferably used in applications where impact resistance and durability are required. The polyethylene resin composition of the present invention particularly satisfies the injection moldability, impact resistance, and durability required for various containers and the like having a capacity of up to about 30 L, and is therefore suitable as a material for producing various containers and the like of this size. The polyethylene resin composition of the present invention can be suitably used not only for large containers but also for small parts to be attached to large containers, such as parts such as lids (caps), supply ports or outlets for internal solutions in industrial chemical cans or drums, and for fuel tanks, parts such as fuel supply ports, valves, or lids (caps) for fixing fuel pumps, which are welded to the body of the fuel tank. Examples of such small parts include hollow pipe-like small parts that serve as handles, supply ports or outlets for internal solutions, etc., which are attached integrally to the large container by welding, and various parts such as reinforcing parts for the opening of the large container, inlets, and opening liners. In addition, the scope of the invention can also include many small parts that have been redesigned to a specific shape and are handled separately from the so-called large container, such as caps for large containers, caps with threads on the inside for attachment to the threads of the large container, and caps that are simply fitted onto the mouth of the large container. Among these, suitable molded articles produced by injection molding using the polyethylene resin composition of the present invention include, for example, various containers such as fuel tanks, oil tanks, urea water tanks, industrial chemical containers, and drums, as well as various parts such as welded parts.

[0094] II. Molded products The molded article of the present invention is a molded article obtained by injection molding the polyethylene resin composition of the present invention described above. The molded article of the present invention may be, for example, any of the uses of the polyethylene resin composition described above, and particularly preferred molded articles of the present invention include various containers such as fuel tanks, oil tanks, urea water tanks, industrial chemical containers, drums, etc., as well as various parts such as welded parts, etc. Among these, particularly preferred molded articles of the present invention, which are produced by taking advantage of the injection moldability, impact resistance, and durability of the polyethylene resin composition of the present invention, include fuel tanks, urea water tanks, and welded parts.

[0095] The fuel tank, which is a molded product of the present invention, can be molded by a known method, and is not particularly limited thereto. For example, it can be obtained by molding two separate molded bodies by injection molding and welding them together at a welding portion. The fuel tank can be imparted with fuel permeation resistance by, for example, mixing a fuel barrier material with the polyethylene resin composition of the present invention and injection molding the mixture to cause the fuel barrier material to be present in the molded article in the form of layers, islands, or other shapes, or by in-mold molding a multilayer sheet of the fuel barrier material and polyethylene.Fuel permeation resistance can also be imparted by combining a molded article of the polyethylene resin composition of the present invention with a separately prepared fuel barrier material by adhesion, or by coating a molded article of the polyethylene resin composition of the present invention with a fuel barrier paint. Known materials can be used as the fuel barrier material, and examples thereof include resins such as EVOH (ethylene-vinyl alcohol copolymer) or nylon, inorganic fillers such as clay, metals such as aluminum, and epoxy paints. [Example]

[0096] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to these examples.

[0097] 1. Measurement and Evaluation The methods of measurement and evaluation carried out in the examples are as follows. (1) Density: Measurements were made in accordance with JIS K7112 (2023). (2) High Load Melt Flow Rate (HLMFR) (Test conditions: 190°C, 21.6 kg load): Measurements were performed in accordance with JIS K6922-1 (2018). (3) Melt flow rate (MFR) (Test conditions: 190°C, 2.16 kg load): Measurements were performed in accordance with JIS K6922-1 (2018).

[0098] (4) Ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn) measured by gel permeation chromatography (GPC): Gel permeation chromatography (GPC) measurements were carried out under the following conditions. Equipment: WATERS Alliance GPC V2000 Columns: Two HT-806M and one HT-G manufactured by Showa Denko Measurement temperature: 145℃ Concentration: 1mg / 1ml Solvent: o-dichlorobenzene The molecular weight calculation and column calibration were carried out according to the following methods. The GPC chromatography data was input into a computer at a frequency of one point per second, and data processing was performed according to the description in Chapter 4 of "Size Exclusion Chromatography" by Sadao Mori, published by Kyoritsu Publishing, to calculate the Mw and Mn values. The measured retention volume was converted to molecular weight using a calibration curve prepared in advance using standard polystyrene.

[0099] (5) Time to rupture in full notch creep test (FNCT) (test conditions: 80°C, 6MPa): Measurements were conducted at 80°C and 6 MPa in accordance with the full notch tensile creep test of JIS K6774(2022) Appendix JC. Test specimens were cut from 6 mm thick compression-molded sheets prepared under the conditions of JIS K6922-2(2018) Table 2, and notched all around (test specimen thickness 6 mm, notch depth 1 mm, all around). The fracture time results for this test are indicated in the table as "FNCT."

[0100] (6) Charpy impact strength at -40°C: Test specimens were prepared in accordance with JIS K6922-2 (2018) and measured in accordance with JIS K7111-1 (2012).

[0101] (7) 230°C, shear rate 243 sec -1 Shear viscosity at: Measurement was carried out using a Toyo Seiki Capillograph with a nozzle having a diameter of 1.0 mm and a length of 40 mm.

[0102] (8) Injection moldability: Measured at 230°C and a shear rate of 243 sec -1 Those having a shear viscosity of 7000 poise or less were marked as "Good", and those having a shear viscosity of more than 7000 poise were marked as "Poor".

[0103] (9) Impact resistance: The Charpy impact strength measured at -40°C was 6.0 kJ / m 2 Those above are marked as "○", and 6.0 kJ / m 2 Anything less than this was marked "x".

[0104] (10)Durability: Those for which the time to rupture in the FNCT (test conditions: 80° C., 6 MPa) measured above was 40 hours or more were rated "◯", and those for which the time to rupture was less than 40 hours were rated "X".

[0105] (11) Overall rating The suitability as a polyethylene resin composition was evaluated, and those which were good in all of the items of injection moldability, impact resistance and durability were given a "◯" and those which were not were given a "X".

[0106] 2. Examples and Comparative Examples <Synthesis of metallocene catalysts> Silica (average particle size 11 μm, surface area 313 m) was placed in a cylindrical flask equipped with an induction stirrer and thoroughly purged with nitrogen. 2 / g, pore volume 1.6 cm 3A flask containing 3 g of silica (2.0 g / g) was charged, 75 ml of toluene was added, and the mixture was heated to 75°C in an oil bath. 8.0 ml of a toluene solution of methylaluminoxane (Albemarle, 3.0 mol-Al / L) was dispensed into a separate flask. A toluene solution (15 ml) of dimethylsilylenebis[1,1'-{2-(2-(5-methyl)furyl)-4-(p-isopropylphenyl)-indenyl}]zirconium dichloride (63.4 mg, 75 μmol) was added to the toluene solution of methylaluminoxane at room temperature, and the mixture was heated to 75°C and stirred for 1 hour. Next, this toluene solution was added with stirring to a toluene slurry of silica heated to 75°C and maintained for 1 hour. Subsequently, 175 ml of n-hexane was added with stirring at 23°C. After 10 minutes, stirring was stopped and the mixture was allowed to stand. After allowing the catalyst to settle sufficiently, the supernatant was removed and 200 ml of n-hexane was added. After stirring once, the mixture was again allowed to stand and the supernatant was removed. This procedure was repeated three times to remove components liberated in n-hexane. The solvent was then distilled off under reduced pressure while heated to 40°C. After the degree of vacuum reached 0.8 mmHg or less, drying under reduced pressure was continued for another 15 minutes to obtain metallocene catalyst A.

[0107] <Production of anti-fouling ingredients> 3 g of n-octylated polyethyleneimine (in which 0.5 n-octyl groups are introduced per monomer unit of polyethyleneimine) derived from polyethyleneimine (molecular weight 10,000) and 1 g of phytic acid, a phosphate ester compound, were mixed and stirred at room temperature in 100 mL of xylene to form a salt. 6 g of dioctyl sulfosuccinate magnesium salt was then added to obtain antifouling component B.

[0108] <Synthesis of Ziegler-Natta catalyst> A 1-L pot (milling vessel) containing approximately 700 10-mm-diameter magnetic balls was charged with 20 g (17.8 mmol) of commercially available magnesium ethylate (average particle size 860 μm), 1.64 g (12.3 mmol) of granular aluminum trichloride, and 2.40 g (8.81 mmol) of diphenyldiethoxysilane under a nitrogen atmosphere. Co-milling was then carried out for 3 hours using a vibrating ball mill at an amplitude of 6 mm and a frequency of 30 Hz. After co-milling, the contents were separated from the magnetic balls under a nitrogen atmosphere. 10.0 g of the co-milled product obtained as described above and 40 ml of heptane were added to a 200 ml three-neck flask. The contents of the flask were stirred at room temperature, and 10.0 g (52.7 mmol) of titanium tetrachloride was added dropwise. The temperature was raised to 90°C, and stirring was continued for 90 minutes. The reaction system was then cooled, the supernatant liquid was removed, and hexane was added. This procedure was repeated three times, and the resulting pale yellow solid was dried at 50° C. under reduced pressure for 6 hours to obtain 15.6 g of a solid catalyst (Ziegler-Natta catalyst C).

[0109] <Production of polyethylene component (a1)> Polyethylene component (a1) was produced by copolymerizing ethylene with 1-hexene using a metallocene catalyst. The specific procedure is as follows. A loop-type slurry reactor with an internal volume of 290 L was supplied with 115 L / h of dehydrated and purified isobutane, 0.13 mol / h of triisobutylaluminum, and 6 ml / h of the antifouling component B obtained above. The temperature inside the reactor was set to 80°C, and ethylene, 1-hexene, and hydrogen were supplied while intermittently discharging isobutane from the reactor to maintain the pressure at 4.2 MPaG. During polymerization, the molar ratio of 1-hexene to ethylene (C6 / C2) in the liquid was 0.010, and the molar ratio of hydrogen to ethylene (H2 / C2) was 3.4 × 10 -4 Next, a hexane slurry prepared by diluting the metallocene catalyst A obtained above with hexane to 0.3 g / L was fed to the reactor at 3 L / h to initiate polymerization, and ethylene was fed so that the ethylene concentration in the reactor became 10 vol%. The produced polyethylene was intermittently discharged together with isobutane, and after being flashed, was sent to a product silo. In the production of the polyethylene component (a1), the melt flow rate was adjusted by supplying an appropriate amount of hydrogen, and the density was adjusted by adjusting the amount of 1-hexene supplied. The resulting polyethylene component (a1) had a HLMFR of 5.0 g / 10 min and a density of 0.920 g / cm 3 It was.

[0110] <Production of polyethylene component (a2)> According to the method for producing the polyethylene component (a1) described above, a polyethylene having an HLMFR of 2.0 g / 10 min and a density of 0.920 g / cm 3 The polymer was produced.

[0111] <Production of polyethylene component (a3)> According to the method for producing the polyethylene component (a1) described above, a polyethylene having an HLMFR of 1.1 g / 10 min and a density of 0.920 g / cm 3 The polymer was produced.

[0112] <Production of polyethylene component (a4)> According to the method for producing the polyethylene component (a1) described above, a polyethylene having an HLMFR of 25.0 g / 10 min and a density of 0.920 g / cm 3 The polymer was produced.

[0113] <Production of polyethylene component (a5)> According to the method for producing the polyethylene component (a1) described above, a polyethylene having an HLMFR of 1.4 g / 10 min and a density of 0.919 g / cm 3 The polymer was produced.

[0114] <Production of polyethylene component (a6)> The polyethylene component (a6) was produced by copolymerizing ethylene and 1-hexene using the Ziegler-Natta catalyst C obtained above. The specific procedure is as follows. Dehydrated and purified isobutane was continuously fed to a 200 L volume loop reactor packed with the polymerization liquid at a rate of 102 L / h, triisobutylaluminum at a rate of 54 g / h, the Ziegler-Natta catalyst C at a rate of 3.2 g / h, ethylene at a rate of 14 kg / h, hydrogen at a rate of 0.59 g / h, and 1-hexene as a comonomer at a rate of 1.38 kg / h, and copolymerization of ethylene and 1-hexene was carried out under conditions of 80°C, a polymerization pressure of 4.2 MPa, and an average residence time of 0.9 hours. In the production of the polyethylene component (a6), the melt flow rate was adjusted by supplying an appropriate amount of hydrogen, and the density was adjusted by adjusting the amount of 1-hexene supplied. The resulting polyethylene component (a6) had a HLMFR of 1.0 g / 10 min and a density of 0.932 g / cm 3 It was.

[0115] <Production of polyethylene component (a7)> According to the method for producing the polyethylene component (a6) described above, a polyethylene having an HLMFR of 0.09 g / 10 min and a density of 0.924 g / cm 3 The polymer was produced.

[0116] <Production of polyethylene component (a8)> According to the method for producing the polyethylene component (a6) described above, a polyethylene having an HLMFR of 2.6 g / 10 min and a density of 0.923 g / cm 3 The polymer was produced.

[0117] <Production of polyethylene component (a9)> According to the method for producing the polyethylene component (a6) described above, a polyethylene having an HLMFR of 0.7 g / 10 min and a density of 0.921 g / cm 3 The polymer was produced.

[0118] <Production of polyethylene component (a10)> According to the method for producing the polyethylene component (a6) described above, a polyethylene having an HLMFR of 1.0 g / 10 min and a density of 0.920 g / cm 3 The polymer was produced.

[0119] <Production of polyethylene component (b1)> A polyethylene component (a6) having an MFR of 10.0 g / 10 min and a density of 0.965 g / cm was prepared in accordance with the method for producing the polyethylene component (a6) described above, except that ethylene homopolymerization was carried out without using 1-hexene. 3 A polymer with Mw / Mn of 6 was produced.

[0120] <Production of polyethylene component (b2)> A polyethylene having an MFR of 24.0 g / 10 min and a density of 0.956 g / cm was obtained in accordance with the production method of the polyethylene component (a1) described above, except that 1-butene was used instead of 1-hexene. 3 A polymer with Mw / Mn of 3 was produced.

[0121] <Production of polyethylene component (b3)> A polyethylene component (a6) having an MFR of 20.0 g / 10 min and a density of 0.965 g / cm was prepared in accordance with the method for producing the polyethylene component (a6) described above, except that ethylene homopolymerization was carried out without using 1-hexene. 3 A polymer with Mw / Mn of 6 was produced.

[0122] <Production of polyethylene component (b4)> A polyethylene component (a6) having an MFR of 50.0 g / 10 min and a density of 0.966 g / cm was prepared in accordance with the production method of the polyethylene component (a6) described above, except that ethylene homopolymerization was carried out without using 1-hexene. 3 A polymer with Mw / Mn of 7 was produced.

[0123] <Production of polyethylene component (b5)> A polyethylene component (a6) having an MFR of 85.0 g / 10 min and a density of 0.967 g / cm was obtained in accordance with the production method of the polyethylene component (a6) described above, except that ethylene homopolymerization was carried out without using 1-hexene. 3 A polymer with Mw / Mn of 8 was produced.

[0124] <Production of polyethylene component (b6)> A polyethylene component (a6) having an MFR of 100.0 g / 10 min and a density of 0.970 g / cm was prepared in accordance with the method for producing the polyethylene component (a6) described above, except that ethylene homopolymerization was carried out without using 1-hexene. 3 A polymer with Mw / Mn of 8 was produced.

[0125] <Production of polyethylene resin composition> [Examples 1 to 4 and Comparative Examples 1 to 7] To a mixture of polyethylene component (a) and polyethylene component (b) of the types and ratios shown in Table 1, 500 ppm of IRGANOX (registered trademark) 1010 manufactured by BASF Japan Ltd. and 1500 ppm of IRGAFOS (registered trademark) 168 manufactured by BASF Japan Ltd. were added as additives. These were melt-mixed using a Labo Plastomill manufactured by Toyo Seiki Seisaku-sho, Ltd. under kneading conditions of a kneading temperature of 210°C and a screw rotation speed of 40 rpm, and then pelletized using a pelletizer to produce a polyethylene resin composition.

[0126] [Table 1]

[0127] The polyethylene resin compositions of Examples 1 to 4 all satisfied all of the above properties (1) to (6) and were excellent in balance between injection moldability, impact resistance, and durability.

[0128] On the other hand, the polyethylene resin compositions of Comparative Examples 1 and 2, which did not satisfy the properties (3), (4) and (5), were poor in impact resistance and durability. The polyethylene resin composition of Comparative Example 3, which did not satisfy the properties (5) and (6), had poor injection moldability. The polyethylene resin compositions of Comparative Examples 4 and 5, which did not satisfy the properties (3) and (5), were inferior in impact resistance. The polyethylene resin composition of Comparative Example 6, which did not satisfy the property (4), was inferior in durability. The polyethylene resin composition of Comparative Example 7, which did not satisfy the property (6), had poor injection moldability. [Industrial Applicability]

[0129] The polyethylene resin composition of the present invention is excellent in injection moldability, impact resistance, and durability. Therefore, by injection molding the polyethylene resin composition of the present invention, a molded article having excellent impact resistance and durability can be provided. Therefore, the polyethylene resin composition of the present invention and a molded article thereof can be produced by injection molding and is suitable for applications requiring impact resistance and durability, such as various containers such as fuel tanks, oil tanks, urea solution tanks, industrial chemical containers, and drums, as well as various parts such as welded parts, and is therefore highly useful industrially.

Claims

1. The present invention comprises, as an essential component, one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 to 12 carbon atoms, A polyethylene resin composition satisfying the following properties (1) to (6): Property (1): The high load melt flow rate (HLMFR) at a temperature of 190° C. and a load of 21.6 kg is 10 g / 10 min or more and 200 g / 10 min or less. Property (2): Density is 0.945 g / cm ３ Above, 0.970g / cm ３ The following is the result. Property (3): Charpy impact strength at -40°C is 6.0 kJ / m ２ That's all. Property (4): The time to rupture in a full notch creep test under conditions of 80°C and 6 MPa is 40 hours or more. Property (5): The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is less than 12. Property (6): 230°C, shear rate 243 sec －１ The shear viscosity at 1000 poise is 7000 poise or less.

2. The ethylene polymer comprises the following polyethylene component (a) polymerized by a metallocene catalyst, and the following polyethylene component (b) polymerized by a metallocene catalyst or a Ziegler-Natta catalyst, 2. The polyethylene resin composition according to claim 1, wherein a ratio of the polyethylene component (a) is 20% by mass or more and 45% by mass or less, and a ratio of the polyethylene component (b) is 55% by mass or more and 80% by mass or less, relative to 100% by mass of the total of the polyethylene component (a) and the polyethylene component (b). Polyethylene component (a); Property (a1): A high load melt flow rate (HLMFR) of 1.0 g / 10 min or more at a temperature of 190° C. and a load of 21.6 kg; Characteristics (a2): Density is 0.910cm ３ Above, 0.930g / cm ３ An ethylene-based polymer, which is: polyethylene component (b); Property (b1): Melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg is 5.0 g / 10 min or more and 50.0 g / 10 min or less, Property (b2): Density is 0.950 cm ３ Above, 0.980g / cm ３ An ethylene-based polymer, which is:

3. The polyethylene resin composition according to claim 1 or 2, which is for injection molding.

4. A molded article obtained by injection molding the polyethylene resin composition according to claim 1 or 2.

5. The molded product according to claim 4, which is at least one selected from the group consisting of a fuel tank, an oil tank, a urea water tank, and a welded part.

Images