Polyethylene resin

Abstract

The objective is to provide polyethylene resin that minimizes the leaching of contaminants such as elutes and degraded materials when used as a container for semiconductor cleaning chemicals. [Solution] Density of 0.960~0.970 g / cm³ 3 A low molecular weight ethylene-based polymer with a density of 0.920-0.940 g / cm³ 3 A polyethylene resin comprising two components of a high molecular weight ethylene polymer, wherein the weight ratio of the two components is 40:60 to 60:40, and having specific properties.

Description

[Technical Field]

[0001] This invention relates to polyethylene resin. [Background technology]

[0002] In recent years, with the remarkable development of the electronics industry, the demand for semiconductor cleaning chemicals has been increasing. Semiconductor cleaning chemicals are used as essential chemicals in the manufacture of electronic circuits such as large-scale, integrated LSIs. Specifically, sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, ammonium fluoride, hydrogen peroxide, isopropyl alcohol, xylene, TMAH (tetramethylammonium hydroxide), methanol, acetic acid, phosphoric acid, ammonia water, PGMEA (propylene glycol acetate methyl ether), DMSO (dimethyl sulfoxide), and NMP (N-methyl-2-pyrrolidone) are used for applications such as wafer cleaning and etching, wiring and insulating film etching, jig cleaning, developing solutions, resist diluents, resist stripping solutions, and drying.

[0003] The quality requirements for semiconductor cleaning chemicals have changed; previously, the metal impurity concentration was required to be 1000 PPT or less, but now it is required to be less than 10 PPT. Furthermore, while the size of microparticles was previously a concern for particles between 100 and 200 nm, recently, particles as small as 30 nm have become a point of concern. Traditionally, polyethylene resin has been used as the container material for these semiconductor cleaning chemicals due to its chemical resistance, impact resistance, and cost. With the increasing integration density of semiconductor circuits, the demand for cleanliness in the containers used to fill these chemicals is also increasing year by year in order to meet the quality requirements of semiconductor cleaning chemicals.

[0004] To solve this problem, a melt index of 0.1-8 g / 10 min and a density of 0.94 g / cm³ is used. 3 While the use of high-density polyethylene (HDPE) in hydrofluoric acid containers has been proposed, there is no mention of resin additives that may be contaminants (see Patent Document 1).

[0005] Furthermore, polyethylene containing a light-shielding agent forms the outer layer, and the innermost layer has a density of 0.958 g / cm³. 3 As described above, containers for sulfuric acid and the like have been proposed with a number-average molecular weight of 5,000 to 12,000 and an Mw / Mn ratio of 15 or more, and with specified concentrations of fatty acid metal salts and hindered phenol antioxidants, but the level of fine particles is low, at 0.5 μm or more (see Patent Document 2).

[0006] Furthermore, containers have been proposed that reduce the amount of hydrocarbon solvents extracted from polyethylene resin, suppress the content of low-molecular-weight components, and limit the amount of antioxidants, neutralizing agents, and lightfasteners added. However, improvements to address the effects of ash content due to residual catalytic components in the polyethylene resin are insufficient, and measures to address the concentration of metal impurities leaching into chemicals remain incomplete. In addition, the level of fine particles is not sufficient, being 0.2 μm or larger (see Patent Documents 3 and 4).

[0007] Furthermore, the density is 0.940~0.970 g / cm³ 3 High-purity polyethylene and high-purity chemical containers have been proposed, characterized by a melt flow rate of 2 to 50 g / 10 min at a temperature of 190°C and a load of 21.6 kg, a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) of 8 to 15 determined by gel permission chromatography (GPC), and an ash content of 50 PPM or less in the polyethylene resin. However, improvements to address the influence of ash content due to residual catalyst components in the polyethylene resin are insufficient, and measures to address the concentration of metal impurities leaching into the chemicals remain incomplete (see Patent Document 5). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 5-41502 [Patent Document 2] Special Publication No. 6-51399 [Patent Document 3] Japanese Patent Application Publication No. 7-62161 [Patent Document 4] Japanese Patent Application Laid-Open No. 7-257540 [Patent Document 5] Japanese Patent Application Laid-Open No. 11-80257 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] The present invention is a polyethylene resin, and when the polyethylene resin is used as a container, it aims to provide a polyethylene resin that suppresses the elution of contaminants such as eluates and deteriorated products of the resin as much as possible. [Means for Solving the Problems]

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that by using polyethylene having specific properties such as density, melt flow rate, molecular weight determined by gel permeation chromatography (GPC), metal content, ESCR, etc., a container with few polyethylene-derived fine particles and metal impurities derived from the polymerization catalyst component can be obtained, and the present invention has been developed.

[0011] That is, each aspect of the present invention is as shown in [1] to [2] below. [1] A low molecular weight ethylene-based polymer having a density of 0.960 to 0.970 g / cm 3 , and a melt flow rate (MFR) of 10 to 30 g / 10 minutes at a temperature of 190 ° C and a load of 2.16 kg, and a high molecular weight ethylene-based polymer having a density of 0.920 to 0.950 g / cm 3 , and a melt flow rate (HLMFR) of 0.005 to 5 g / 10 minutes at a temperature of 190 ° C and a load of 21.6 kg, and the weight ratio of the two components is 40:60 to 60:40, and a polyethylene resin having the following properties (1) to (7). (1) The density is 0.940 to 0.965 g / cm 3 (2) The melt flow rate (HLMFR) at a temperature of 190 ° C and a load of 21.6 kg is 3.0 to 60 g / 10 minutes (3) The melt flow rate (MFR) at a temperature of 190 °C and a load of 2.16 kg is 0.03 to 1.5 g / 10 min (4) The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 6.0 to 18 (5) In the molecular weight distribution curve obtained using GPC, the component with a molecular weight of 500 or less is 0.15% by weight or less (6) The contents of magnesium (Mg), aluminum (Al), and titanium (Ti) are 10 PPM or less based on the polyethylene resin (7) The environmental stress crack resistance (ESCR) is 50 hours or more [2] The polyethylene resin according to [1] above, which does not contain an additive.

Effect of the Invention

[0012] When the polyethylene resin which is one aspect of the present invention is used, it is possible to provide a container with less elution of fine particles derived from the polyethylene resin and metal impurities derived from the polymerization catalyst.

Mode for Carrying Out the Invention

[0013] The polyethylene resin which is one aspect of the present invention has a density of 0.960 to 0.970 g / cm 3 , a low molecular weight ethylene-based polymer having a melt flow rate (MFR) of 10 to 30 g / 10 min at a temperature of 190 °C and a load of 2.16 kg, and a density of 0.920 to 0.940 g / cm [[ID=##]] 3 , and contains two components of a high molecular weight ethylene-based polymer having a melt flow rate (HLMFR) of 0.005 to 5 g / 10 min at a temperature of 190 °C and a load of 21.6 kg. The weight ratio of the two components is 40:60 to 60:40, and has the following properties (1) to (7). (1) The density is 0.940 to 0.965 g / cm 3 (2) The HLMFR at a temperature of 190 °C and a load of 21.6 kg is 3.0 to 60 g / 10 min (3) The MFR at a temperature of 190 °C and a load of 2.16 kg is 0.03 to 1.5 g / 10 min (4) The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) determined by gel permeation chromatography (GPC) is between 6.0 and 18. (5) In the molecular weight distribution curve obtained using GPC, the component with a molecular weight of 500 or less is 0.15% by weight or less. (6) Mg, Al, and Ti content is 10 PPM or less relative to polyethylene resin (7) ESCR runs for more than 50 hours The polyethylene resin can be produced using a Ziegler-type catalyst. For example, it can be suitably produced by copolymerizing ethylene or ethylene with α-olefins having 3 to 20 carbon atoms in a ratio that achieves a desired density, using a highly active Ziegler-type catalyst consisting of a transition metal compound such as Ti, a Mg compound, and an organic Al compound as the polymerization catalyst.

[0014] Examples of catalysts include the catalyst described in Japanese Patent No. 3319051.

[0015] Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene.

[0016] In the polymerization method for producing the polyethylene resin, slurry polymerization using a polymerization solvent with 6 to 10 carbon atoms, such as n-hexane or n-heptane, is preferred in order to keep the concentration of metal impurities eluted into the chemical low and to limit the incorporation of low-molecular-weight polymers into the resin, which can cause the generation of fine particles, and the density is 0.960 to 0.970 g / cm³. 3 A low molecular weight ethylene polymer with an MFR of 10-30 g / 10 min and a density of 0.920-0.950 g / cm³ 3It contains two components of high molecular weight ethylene polymers with an HLMFR of 0.005 to 5 g / 10 min, and the weight ratio of these two components is 40:60 to 60:40. The two components, a low molecular weight component and a high molecular weight component, can be produced, for example, by a two-step polymerization method. The density of the low molecular weight ethylene polymer is 0.960 to 0.970 g / cm³. 3 If the MFR is 10-30 g / 10 min, the generation of low molecular weight polyethylene components and branched components derived therefrom, which cause fine particles, can be suppressed. If the density of the high molecular weight ethylene polymer is 0.920-0.950 g / cm³ and the HLMFR is 0.005-5 g / 10 min, the resin will have excellent mechanical strength and ESCR. Furthermore, if the weight ratio of the two components is 40:60-60:40, the resin will have an excellent balance between low fine particle elution and moldability when used as a container.

[0017] The density of the polyethylene resin (JIS K6922-1) is 0.940 to 0.965 g / cm³. 3 The concentration is preferably 0.945 to 0.955 g / cm³. 3 It is 0.940 g / cm³. 3 Below this level, the amount of polymer components leaching into the chemicals in the container increases, leading to the generation of fine particles. Also, a density of 0.965 g / cm³ is considered insufficient. 3 If it exceeds a certain level, the container's ESCR will decrease.

[0018] The HLMFR (JIS K6922-1) of the polyethylene resin is 3.0 to 60 g / 10 min, preferably 5.0 to 50 g / 10 min. Below 3.0 g / 10 min, the surface texture of the container deteriorates. Above 60 g / 10 min, the drawdown increases and moldability deteriorates.

[0019] The MFR (JIS K6922-1) of the polyethylene resin is 0.03 to 1.5 g / 10 min, preferably 0.03 to 1.2 g / 10 min. Below 0.03 g / 10 min, the surface texture of the container deteriorates. Above 1.5 g / 10 min, the drawdown increases and moldability deteriorates.

[0020] The Mw / Mn ratio of the polyethylene resin, determined by GPC, is between 6.0 and 18, preferably between 6.0 and 15. If the Mw / Mn ratio is less than 6.0, the molecular weight distribution is narrow, the surface texture of the container deteriorates, and the ESCR of the container also decreases. If the Mw / Mn ratio exceeds 18, the shape of the pinch-off portion, which is the parison bond, deteriorates, and the drop strength of the container decreases. In the molecular weight distribution curve obtained using GPC of the polyethylene resin, the component with a molecular weight of 500 or less is 0.15% by weight or less. If the component with a molecular weight of 500 or less exceeds 0.15% by weight, the low molecular weight component increases, and the number of fine particles with a molecular weight of 20 nm or more that leach from the container increases. The component with a molecular weight of 500 or less can be reduced by lowering the MFR of the low molecular weight component and increasing the proportion of the high molecular weight component.

[0021] The Mg, Al, and Ti content of the polyethylene resin is 10 PPM or less relative to the polyethylene resin. When Mg, Al, and Ti are 10 PPM or less, the amount of metal leaching into semiconductor cleaning chemicals is low, thus suppressing the concentration of metal impurities in the chemicals. The Mg, Al, and Ti content represents the proportion of metals to the total resin in weight PPM, and is obtained by alkali melting after ashing the resin.

[0022] The ESCR of the polyethylene resin is 50 hours or more. If the ESCR is less than 50 hours, for example, if a surfactant is filled in and left for more than 6 months, the container may break due to environmental stress cracking.

[0023] Furthermore, this polyethylene resin contains no additives whatsoever, including antioxidants, light stabilizers, and neutralizing agents. Here, neutralizing agents refer to fatty acid metal salts such as calcium stearate and zinc stearate, and hydrotalcites, all of which dissolve into the chemical and become metal contaminants or fine particles.

[0024] The polyethylene resin can be molded into a container shape by direct blow molding, injection molding, and injection blow molding to produce semiconductor cleaning chemical containers. In particular, a blow molding method using a direct blow molding machine installed in a clean room and using air from which fine particles have been removed by a filter as the blow air is preferable for producing clean containers. The shape of the semiconductor cleaning chemical container obtained using the resin is not specified, but in order to reinforce the barrier properties of the contents and the strength of the container, the polyethylene resin may be used as the inner layer, and other polyethylene resins, ethylene-vinyl alcohol copolymers, polyvinyl alcohol resins, and polyamide resins may be used as the intermediate layer, or other polyethylene resins and FRP may be used as the outer layer for reinforcement.

[0025] When an unwashed container molded using the polyethylene resin is filled with ultrapure water, it is preferable that the number of fine particles 20 nm or larger that leach from the container is 35 particles / mL or less after storage at 40°C for 35 days. If the number of fine particles 20 nm or larger is 35 particles / mL or less, it can accommodate the miniaturization of LSIs.

[0026] Furthermore, it is preferable that the amount of Mg, Al, and Ti leached from an unwashed container molded using the polyethylene resin, filled with ultrapure water and stored at 23°C for 7 days, is 10 PPT or less. If the amount of Mg, Al, and Ti leached is 10 PPT or less, defects in semiconductor devices can be suppressed.

[0027] Examples of containers that can be obtained using the polyethylene resin of the present invention include gallon containers, 20L industrial chemical cans, and 200L plastic drums. [Examples]

[0028] The present invention will be described below with reference to examples, but is not limited to these examples. The test methods used in the examples and comparative examples are as follows.

[0029] (1) Blow molding Using a direct blow molding machine MSE-50E / 54M-A (manufactured by Tahara Corporation) with a 50mmΦ extrusion screw, the cylinder temperature was set to 170-200°C, the parison temperature to 170-210°C, and the parison shear rate at the die exit to 30-150s. -1 The parison was continuously extruded from the die tip by modifying the parameters within the specified range, and a container with an internal volume of 800 mL was formed.

[0030] (2) Number of fine particles In a cleanroom at 23°C, an unwashed container with an internal volume of 800 mL, obtained by blow molding, was filled to 80% of its internal volume with ultrapure water so that the Reynolds number (Re) of the liquid at the time of filling was 2200 ≤ Re ≤ 3200. The container was then sealed and stored for 35 days in a clean oven (Yamato Scientific Co., Ltd., DE411) at a set temperature of 40°C. After that, the number of particles larger than 20 nm in the filled water was measured using a particle counter (Rion Co., Ltd., controller: KE-40B1, particle sensor: KS-20F). The number of particles in the water is expressed as particles / mL.

[0031] (3) Amount of metal elution In a cleanroom at 23°C, an unwashed container with an internal volume of 800 mL, obtained by blow molding, was filled to capacity with ultrapure water, sealed, and stored for 7 days. The elution amounts of Mg, Al, and Ti in the filled water were then measured using an inductively coupled plasma mass spectrometer (PerkinElmer, ELAN DRCII). The elution amounts of Mg, Al, and Ti in the filled water are shown in PowerPoint.

[0032] (4) Maximum roughness of the inner surface of the container Rz The maximum surface roughness Rz value of the inner surface of the container body was measured using a shape measuring laser microscope (VK-X200, manufactured by Keyence Corporation).

[0033] (5) Arithmetic mean roughness Ra of the inner surface of the container The arithmetic mean roughness Ra value of the inner surface of the container body was measured using a shape measuring laser microscope (VK-X200, manufactured by Keyence Corporation).

[0034] (6) Density The density was measured using the density gradient pipe method in accordance with JIS K6922-1.

[0035] (7) MFR Measurements were taken in accordance with JIS K6922-1, at 190°C and under a load of 2.16 kg.

[0036] (8) Mw / Mn The molecular weight was measured by GPC using Tosoh HLC-8321GPC / HT (columns: Tosoh TSKgel guardcolumnHHR and TSKgelGMHHR-H) with 1,2,4-trichlorobenzene as the eluent. The molecular weight calibration curve was calibrated using polystyrene samples with known molecular weights. (9) HLMFR Measurements were taken in accordance with JIS K6922-1, at 190°C and under a load of 21.6 kg.

[0037] (10) Components with a molecular weight of 500 or less The proportion of the integrated amount of components with a molecular weight of 500 or less was calculated from the molecular weight distribution curve obtained by GPC measurement.

[0038] (11) Catalyst residue amount Polyethylene resin was ashed and then subjected to alkaline fusion to obtain a solution, which was used as the measurement solution. The Mg, Al, and Ti content in the sample was measured by ICP-AES.

[0039] (12) Environmental stress crack resistance (ESCR) In accordance with JIS K6922-2, test specimens were immersed in a nonionic surfactant (10 wt% aqueous solution) at a temperature of 50°C, and the time at which the test specimen fractured with a 50% probability (F50 value) was measured.

[0040] Example 1 <Preparation of Solid Catalyst Component A> In a 3L glass flask equipped with a stirring device, 30.0 g (1.23 mol) of metallic magnesium powder and 168.0 g (0.494 mol) of titanium tetrabutoxide were placed. 192 g (2.59 mol) of n-butanol dissolved in 1.5 g of iodine was added over 2 hours at 90°C, and the mixture was stirred at 140°C for 2 hours under a nitrogen seal while removing the generated hydrogen gas. After reducing the temperature to 110°C, 26 g (0.125 mol) of tetraethoxysilane and 19 g (0.125 mol) of tetramethoxysilane were added, and the mixture was stirred at 140°C for another 2 hours. Then, 2.1 liters of hexane were added to obtain a homogeneous solution.

[0041] This homogeneous solution was placed in a 10 L stainless steel autoclave equipped with a stirring device. Maintaining the autoclave's internal temperature at 45°C, 800 mL of hexane solution containing 1.0 mol / L of diethylaluminum chloride and 0.5 mol / L of i-butylaluminum dichloride was added over 1 hour, and the mixture was stirred at 60°C for another hour to generate particles. After returning the temperature to 45°C, 1.04 kg (3.35 mol / L) of 50% hexane solution was added over 2 hours. After all components had been added, the mixture was stirred at 60°C for 1 hour to obtain solid catalyst component A. The obtained solid catalyst component A was used as a hexane slurry for the production of polyethylene A after removing any remaining unreacted materials and by-products using hexane. <Manufacturing of Polyethylene A> In the first stage of a 370L continuous polymerizer, 110L / hour of dehydrated and purified hexane, 110 mmol / hour of tributylaluminum as an organoaluminum compound, 0.4 g / hour of solid catalyst components, 25.4 kg / hour of ethylene, and hydrogen were supplied at a concentration ratio of 0.30 mol / mol / ethylene, while maintaining a temperature of 85°C and a total pressure of 30 kg / cm². 2 Under conditions of an average residence time of 3.4 hours, the first stage of ethylene polymerization (low molecular weight component) was carried out continuously.

[0042] The hexane slurry containing the first-stage polymer was introduced into a 545L second-stage polymerizer after removing unreacted hydrogen and ethylene in a flash tank. While supplying an additional 45L / hour of hexane to this polymerizer, ethylene was supplied at 21.5kg / hour, 1-butene at 2.5kg / hour, and hydrogen at a concentration ratio of 0.020mol / mol / ethylene, at a temperature of 80°C and a total pressure of 20kPa / cm². 2 Ethylene polymerization (high molecular weight component) was carried out under conditions of an average residence time of 3.3 hours. The waste from the second polymerizer was flushed in a flash tank to remove unreacted hydrogen, ethylene, and 1-butene, washed with hexane at 50 L / hour, and then dried to obtain a mixed powder of ethylene copolymers. The proportion of low molecular weight components was 45% by weight, and the proportion of high molecular weight components was 55% by weight. The powder polymerized in the above two-stage process was pelletized without the addition of any additives to obtain polyethylene A. The results of the physical property measurements are shown in Table 1.

[0043] Using polyethylene A, blow molding was performed with a cylinder temperature of 180°C, a parison temperature of 182-183°C, and a parison shear rate of 35-60s at the die exit. -1 An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0044] Example 2 <Preparation of Solid Catalyst Component B> 40.0 g (1.65 mol) of metallic magnesium powder and 224 g (0.66 mol) of titanium tetrabutoxide were added to a 3 L glass flask equipped with a stirrer. A mixture of 108 g (1.8 mol) of i-propanol dissolved in 2.0 g of iodine and 135 g (1.8 mol) of n-butanol was placed in a dropping funnel. This mixture was added dropwise to the 3 L flask over 2 hours at a temperature of 80-95°C. To complete the reaction, the temperature was further raised to 120°C and stirred for 1 hour. Then, 2.1 L of hexane was added to obtain a homogeneous solution. Next, this homogeneous solution was placed in a 10 L stainless steel autoclave equipped with a stirrer, and the internal temperature of the autoclave was maintained at 45°C. 1.32 kg (3.3 mol) of a 30% hexane solution of diethylaluminum chloride was added over 1 hour, and the mixture was further stirred at 60°C for 1 hour. Next, 197 g of methylhydropolysiloxane (viscosity approximately 30 centistokes at 25°C) (3.3 grams of silicon atoms) was added, and the mixture was stirred at 68-70°C for 1 hour. After cooling to 45°C, 2.8 kg (9.1 mol) of a 50% hexane solution of i-butylaluminum dichloride was added over 2 hours. After adding all the components, the mixture was stirred at 70°C for 1 hour to obtain solid catalyst component B. The obtained solid catalyst component B was used to remove any remaining unreacted materials and by-products using hexane, and then used to produce hexane slurry and polyethylene B. <Manufacturing of Polyethylene B> In the first stage of a 370L continuous polymerizer, 110L / hour of dehydrated and purified hexane, 120 mmol / hour of tributylaluminum as an organoaluminum compound, 0.5 g / hour of solid catalyst component B, 25.4 kg / hour of ethylene, and hydrogen were supplied at a concentration ratio of 0.35 mol / mol / L relative to ethylene, while maintaining a temperature of 85°C and a total pressure of 30 kg / cm². 2 Under conditions of an average residence time of 3.4 hours, the first stage of ethylene polymerization (low molecular weight component) was carried out continuously.

[0045] The hexane slurry containing the first-stage polymer was introduced into a 545L second-stage polymerizer after removing unreacted hydrogen and ethylene in a flash tank. While supplying an additional 45L / hour of hexane to this polymerizer, ethylene was supplied at 18.0 kg / hour, 1-butene at 0.6 kg / hour, and hydrogen at a concentration ratio of 0.014 mol / mol to ethylene, at a temperature of 80°C and a total pressure of 20 kPa / cm². 2 Ethylene polymerization (high molecular weight component) was carried out under conditions of an average residence time of 3.3 hours. The waste from the second polymerizer was flushed in a flash tank to remove unreacted hydrogen, ethylene, and 1-butene, washed with hexane at 50 L / hour, and then dried to obtain a mixed powder of ethylene copolymers. The proportion of low molecular weight components was 49% by weight, and the proportion of high molecular weight components was 51% by weight. The powder polymerized in the above two-stage process was pelletized without the addition of additives to obtain polyethylene B. The results of the physical property measurements are shown in Table 1.

[0046] Using polyethylene B, blow molding was performed with a cylinder temperature of 175°C, a parison temperature of 182-183°C, and a parison shear rate of 60-90s at the die exit. -1 An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0047] Example 3 <Manufacturing of Polyethylene C> Except for supplying hydrogen to the second stage polymerizer at an ethylene-to-ethylene concentration ratio of 0.05 mol / mol, polymerization powder was obtained by copolymerization of ethylene and butene-1 in hexane in the same manner as in Example 2, using a two-stage polymerization method. The two-stage polymerized powder was pelletized without the addition of any additives to obtain polyethylene C. The results of the physical property measurements are shown in Table 1.

[0048] Using polyethylene C, blow molding was performed with a cylinder temperature of 185°C, a parison temperature of 187-188°C, and a parison shear rate of 40-70s at the die exit. -1An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0049] Comparative Example 1 <Manufacturing of Polyethylene D> In the first polymerizer, hydrogen was supplied at a concentration ratio of 0.28 mol / mol / L relative to ethylene. In the second polymerizer, 1-butene was supplied at a rate of 0.8 kg / hour, with hydrogen supplied at a concentration ratio of 0.012 mol / mol / L relative to ethylene. The proportion of low molecular weight components was 50% by weight, and the proportion of high molecular weight components was 50% by weight. Polymerized powder was obtained by copolymerizing ethylene and butene-1 in hexane in the same manner as in Example 1, using a two-stage polymerization method. The two-stage polymerized powder was pelletized without the addition of any additives to obtain polyethylene D. The results of the physical property measurements are shown in Table 1.

[0050] Using polyethylene D, blow molding was performed with a cylinder temperature of 185°C, a parison temperature of 191-192°C, and a parison shear rate of 75-100 s at the die exit. -1 An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0051] Comparative Example 2 <Manufacturing of Polyethylene E> In the first polymerizer, hydrogen was supplied at a concentration ratio of 0.85 mol / mol / L relative to ethylene. In the second polymerizer, 1-butene was supplied at a rate of 1.9 kg / hour, with hydrogen supplied at a concentration ratio of 0.016 mol / mol / L relative to ethylene. The second polymerizer consisted of 55% by weight of low molecular weight components and 45% by weight of high molecular weight components. Except for these differences, polymerization powder was obtained by copolymerizing ethylene and butene-1 in hexane in the same manner as in Example 1. The two-stage polymerized powder was pelletized without the addition of any additives to obtain polyethylene E. The results of the physical property measurements are shown in Table 1.

[0052] Using polyethylene E, blow molding was performed with a cylinder temperature of 200°C, a parison temperature of 204-206°C, and a parison shear rate of 50-65s at the die exit. -1An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0053] Comparative Example 3 <Manufacturing of Polyethylene F> As polyethylene F, the following commercially available high-density polyethylene was used.

[0054] Manufactured by Tosoh Corporation, (product name) Nipolon Hard (registered trademark) 8300A (density = 0.955 g / cm³) 3 , MFR=0.35g / 10min) Using polyethylene F, blow molding was performed with a cylinder temperature of 180°C, a parison temperature of 185-186°C, and a parison shear rate of 60-90s at the die exit. -1 An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0055] Comparative Example 4 <Manufacturing of Polyethylene G> As polyethylene G, the following commercially available high-density polyethylene was used.

[0056] Manufactured by Tosoh Corporation, (product name) Nipolon Hard (registered trademark) 4030 (density = 0.965 g / cm³) 3 (MFR = 5.0g / 10 mins) Using polyethylene G, blow molding was performed with a cylinder temperature of 180°C, a parison temperature of 185-186°C, and a parison shear rate of 70-100 s at the die exit. -1 An 800 mL container was molded within the specified range, and the number of fine particles larger than 20 nm and the amount of metal leached from the resulting unwashed container were measured. The results are shown in Table 1.

[0057] [Table 1]

Claims

1. Density of 0.960–0.970 g / cm³ ３ A low molecular weight ethylene polymer having a melt flow rate (MFR) of 10-30 g / 10 min at a temperature of 190°C and a load of 2.16 kg, and a density of 0.920-0.950 g / cm³. ３ A polyethylene resin comprising two components of high molecular weight ethylene polymers having a melt flow rate (HLMFR) of 0.005 to 5 g / 10 min at a temperature of 190°C and a load of 21.6 kg, wherein the weight ratio of the two components is 40:60 to 60:40, and having the following properties (1) to (7). (1) Density of 0.940 to 0.965 g / cm³ ３ (2) Melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is 3.0 to 60 g / 10 min (3) Melt flow rate (MFR) of 0.03 to 1.5 g / 10 min at a temperature of 190°C and a load of 2.16 kg (4) The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) determined by gel permeation chromatography (GPC) is between 6.0 and 18. (5) In the molecular weight distribution curve obtained using GPC, the component with a molecular weight of 500 or less is 0.15% by weight or less. (6) Magnesium (Mg), aluminum (Al), and titanium (Ti) content is 10 PPM or less relative to the polyethylene resin. (7) Environmental stress crack resistance (ESCR) of 50 hours or more

2. The polyethylene resin according to claim 1, which does not contain additives.

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