Container and method for manufacturing the same

Abstract

To provide a container which is formed by using polyethylene resin composition and has an excellent balance between rigidity and transparency, and to provide a manufacturing method of the same.SOLUTION: A container comprises polyethylene resin composition, and satisfies the following characteristics: (a) average thickness of a container trunk part is 0.4-1.0 mm; (b) tensile modulus of the container trunk part is equal to or greater than 800 MPa; and (c) haze of the container trunk part is equal to or less than 70%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a container and a method for manufacturing the same. [Background technology]

[0002] Injection stretch blow molding is a molding method in which a bottomed cylindrical preform formed by injection molding is stretched with a stretching rod while blown air is blown into it. Taking advantage of the fact that the desired area can be cooled and solidified during injection molding, allowing for the faithful transfer of the mold shape, it is possible to manufacture containers with highly dimensionally accurate screw-shaped openings. In addition, it has the advantage of being able to manufacture containers with improved physical properties due to the biaxial stretching effect of the stretching rod and blown air, so resins such as polypropylene and polyethylene terephthalate are widely used.

[0003] Polyethylene, particularly high-density polyethylene, is a well-known general-purpose resin. Its superior rigidity, impact resistance, and chemical resistance make it suitable for use in large and small containers obtained by extrusion blow molding. However, due to its rapid crystallization rate and high thermal shrinkage rate, achieving uniform wall thickness in the stretching direction is difficult, especially during the stretching process, in injection stretch blow molding. Therefore, its application has been limited to small containers with low stretching ratios. Furthermore, while higher density in polyethylene leads to higher crystallinity and superior rigidity, it is known that the light scattering effect of the crystals can cause the molded body to become opaque. Consequently, obtaining a high-density polyethylene resin container that possesses both transparency (ensures visibility of contents) and rigidity is challenging.

[0004] Under these circumstances, polyethylene resins and manufacturing methods that satisfy specific requirements have been proposed to obtain molded containers with good injection-stretch blow moldability and excellent transparency, and it has been stated that the haze value, an indicator of transparency of the resulting containers, is 50% or less (see, for example, Patent Document 1). Furthermore, polyethylene resin compositions consisting of multiple polyethylene resins have also been proposed for the purpose of further improving injection-stretch blow moldability and container characteristics (see, for example, Patent Documents 2 and 3). In addition, the present inventors have previously found that a resin composition consisting of a specific high-density polyethylene and an ethylene-α-olefin copolymer that satisfies specific requirements has an excellent balance of transparency and heat resistance (see Patent Document 4).

[0005] In addition, recent advances in molding equipment have made it possible to form containers with good shapes using injection-stretch blow molding of general-purpose polyethylene resin without satisfying specific requirements, through precise temperature equalization treatment in the temperature control process of preforms formed by injection molding and precise timing of blow air in the stretch blow molding process (see Patent Document 5). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-178276 [Patent Document 2] Japanese Patent Publication No. 2000-86833 [Patent Document 3] Japanese Patent Publication No. 2021-24163 [Patent Document 4] Japanese Patent Publication No. 2015-96190 [Patent Document 5] Japanese Patent Publication No. 2021-119056 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, our own investigations have shown that even with the high-density polyethylene and manufacturing method described in Patent Document 1, containers with excellent transparency cannot necessarily be obtained. Specifically, we have confirmed that even with extremely thin-walled containers of about 0.4 mm thickness as injection-stretched blow-molded containers, the haze value does not fall below 70%. Furthermore, while the methods proposed in Patent Documents 2 and 3 are described as having good moldability, surface gloss, rigidity, and resistance to environmental stress cracking, they do not mention transparency, and it is presumed that this is not a particular selling point as the transparency is within the range of general high-density polyethylene. Moreover, while the method proposed in Patent Document 4 is described as having an excellent balance between transparency and heat resistance, it does not mention the balance between transparency and rigidity, and all the molded bodies described in the examples relate to laminates, with no mention whatsoever of injection-stretched blow moldability or the characteristics of injection-stretched blow-molded bodies. Furthermore, the method proposed in Patent Document 5 described above is a manufacturing method for polyethylene resin, which states that if polyethylene with a melt flow rate of 0.3 to 1.0 g / 10 min is used, an injection-stretched blow molded article with uniform wall thickness can be obtained, but it does not mention the characteristics of the resulting molded article. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of the present invention have found that a container with rigidity, transparency, uniform wall thickness, and a good surface appearance can be easily obtained by injection stretch blow molding using a polyethylene resin composition that satisfies specific requirements, and have completed the present invention.

[0009] In other words, the embodiments of the present invention are as follows [1] to [3]. [1] A container made of a polyethylene resin composition that satisfies the following properties. (a) The average thickness of the container body is 0.4 to 1.0 mm (b) Tensile modulus of the container body is 800 MPa or higher (c) The haze on the container body is 70% or less. [2] The container according to [1], comprising a polyethylene resin composition containing 90 to 60% by weight of high-density polyethylene (A) satisfying the following characteristics (a) to (d) and 10 to 40% by weight of an ethylene-based polymer (B) satisfying the following characteristics (e) to (h) (the total of (A) and (B) is 100% by weight). (a) The density measured in accordance with JIS K6922-1 (hereinafter referred to as density) is 950 to 960 kg / m 3 . (b) The melt mass flow rate measured in accordance with JIS K6924-1 at a temperature of 190°C and a load of 21.18 N (hereinafter referred to as MFR) is 0.3 to 4.0 g / 10 minutes. (c) In the measurement of molecular weight by gel permeation chromatography (hereinafter referred to as GPC), the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 2.0 to 3.0. (d) 13 The number of branches of hexyl groups or more per 1000 carbon atoms (hereinafter referred to as LCB) determined from the measurement of the C-NMR spectrum is less than 0.5. (e) The density is 940 to 948 kg / m 3 . (f) The MFR is 0.3 to 3.0 g / 10 minutes. (g) In the measurement of molecular weight by GPC, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 3.5 to 5.0. (h) 13 The LCB determined from the measurement of the C-NMR spectrum is 0.5 to 2.0. [3] A method for manufacturing the container according to [1] or [2], comprising an injection molding step of forming a bottomed preform by injection molding, and a stretch blow molding step of introducing blow air into the preform and stretching the preform by pressing the bottom of the preform with a stretching rod.

Advantages of the Invention

[0010] A container according to one aspect of the present invention has excellent rigidity and transparency, and is therefore suitable for use as a medical container, food container, cosmetic container, and the like. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below.

[0012] One aspect of the present invention relates to a container made of a polyethylene resin composition that satisfies the following characteristics. (a) The average thickness of the container body is 0.4 to 1.0 mm (b) Tensile modulus of elasticity of 800 MPa or higher (c) Haze is 70% or less The container has an average thickness of 0.4 to 1.0 mm, preferably 0.5 to 0.8 mm, and a tensile modulus of elasticity of 800 MPa or more. Furthermore, the haze is 70% or less. If the average thickness of the container body is less than 0.4 mm, the container will have poor rigidity. If the average thickness of the container body exceeds 1.0 mm, the container will have poor transparency. If the tensile modulus of elasticity is less than 800 MPa, the container will have poor rigidity. If the haze exceeds 70%, the inside of the container cannot be seen with the naked eye, and sufficient visibility to check the contents cannot be ensured, so the container cannot be said to be transparent.

[0013] The polyethylene resin composition used in the present invention is not particularly limited, but from the viewpoint of maintaining rigidity, it is preferable that high-density polyethylene be the main component (50% by weight or more). Furthermore, in order to ensure transparency, it is preferable that highly transparent polyethylene be used as a secondary component (less than 50% by weight). Generally, as highly transparent polyethylene, it is preferable to use high-pressure low-density polyethylene or linear low-density polyethylene. In order to achieve a high degree of both rigidity and transparency, a resin composition containing high-density polyethylene and an ethylene-based polymer is preferred, and in particular, a polyethylene resin composition containing 90-60% by weight of high-density polyethylene (A) that satisfies the following characteristics (a)-(d) and 10-40% by weight of an ethylene-based polymer (B) that satisfies the following characteristics (e)-(h) (the total of (A) and (B) is 100% by weight) is preferred. (a) The density is 950 - 960 kg / m 3 . (b) The MFR is 0.3 - 4.0 g / 10 min (c) In the molecular weight measurement by GPC, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 2.0 - 3.0 (d) 13 The LCB determined from the measurement of the C-NMR spectrum is less than 0.5 (e) The density is 940 - 948 kg / m 3 . (f) The MFR is 0.3 - 3.0 g / 10 min (g) In the molecular weight measurement by GPC, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 3.5 - 5.0 (h) 13 The LCB determined from the measurement of the C-NMR spectrum is 0.5 - 2.0

[0014] The high-density polyethylene (A) is a homopolymer of ethylene or a copolymer of ethylene and an α-olefin, and preferably has a density of 950 - 960 kg / m 3 , more preferably 952 - 958 kg / m 3 . Also, the MFR is preferably 0.3 - 4.0 g / 10 min, more preferably 1.0 - 3.0 g / 10 min. Also, in the molecular weight measurement by GPC, it is preferable that the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 2.0 - 3.0. Further 13 the LCB determined from the measurement of the C-NMR spectrum is preferably less than 0.1. If the density is 950 kg / m 3 or more, the rigidity of the obtained container is excellent. Also, if the density is 960 kg / m 3The transparency of the resulting container is excellent if the following conditions are met: If the MFR is 0.3 g / 10 min or higher, the fluidity during processing is sufficient, and the surface of the preform is good in the injection molding process where a bottomed preform is formed by injection molding. If it is 4.0 g / 10 min or lower, the molten preform does not sag under its own weight in the stretch blow molding process where the preform is reheated and stretch blow molded, and the uniformity of the wall thickness can be controlled. If the Mw / Mn is 2.0 or higher, the fluidity during processing is sufficient, and the surface of the preform is good in the injection molding process where a bottomed preform is formed by injection molding. If the Mw / Mn is 3.0 or lower, the transparency of the resulting container is excellent when a polyethylene resin composition containing an ethylene polymer (B) is used and injection stretch blow molded. If the LCB is 0.1 or lower, the thermal shrinkage rate is not large, the preform does not shrink significantly during the soaking treatment in the temperature control process of the preform formed by injection molding, and the uniformity of the wall thickness in the stretching direction can be maintained in the stretching process.

[0015] High-density polyethylene (A) can be produced by the following methods. For example, it can be produced by manufacturing methods such as the slurry method, solution method, and gas phase method. When producing high-density polyethylene (A), generally, a Ziegler catalyst consisting of a solid catalyst component containing magnesium and titanium and an organoaluminum compound, a metallocene catalyst consisting of an organotransition metal compound containing a cyclopentadienyl derivative and a compound that reacts with it to form an ionic complex and / or an organometallic compound, or a vanadium-based catalyst can be used. It can be produced by homopolymerizing ethylene or copolymerizing ethylene with α-olefins using these catalysts. As α-olefins, any α-olefin generally referred to as α-olefins is fine, and it is preferable that they be α-olefins having 3 to 12 carbon atoms, such as propylene, butene-1, hexene-1, octen-1, and 4-methyl-1-pentene. Examples of copolymers of ethylene and α-olefins include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octen-1 copolymer.

[0016] The ethylene-based polymer (B) has a density of 940-948 kg / m³.3 It is preferably in the range of 941 to 947 kg / m 3 The range is as follows. Furthermore, the MFR is preferably 0.3 to 3.0 g / 10 min, and more preferably 0.4 to 2.0 g / 10 min. In addition, in molecular weight measurement by GPC, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is preferably in the range of 3.0 to 5.0, and more preferably in the range of 3.5 to 5.0. 13 The LCBs determined from the 1C-NMR spectrum are preferably 0.5 to 2. The density is 940 kg / m³. 3 If the above conditions are met, the resulting container will have superior rigidity. Furthermore, the density is 948 kg / m³. 3 The following conditions result in superior transparency: If the MFR is 0.3 g / 10 min or higher, the melt viscosity is not too high, and the molded product can be manufactured using a general-purpose molding machine. Also, if it is 3.0 g / 10 min or lower, the resulting container will have superior transparency. If the Mw / Mn ratio is between 3.0 and 5.0, the resulting container will have superior transparency. If the LCB is between 0.5 and 2.0, the resulting container will have superior transparency.

[0017] Ethylene polymers (B) are produced using a metallocene catalyst. The metallocene catalyst used preferably comprises one metallocene complex, an activating co-catalyst, and, if necessary, an organoaluminum compound, and carries out the synthesis of macromonomers simultaneously with copolymerization of macromonomers with ethylene, or macromonomers with ethylene and olefins having 3 to 6 carbon atoms. Macromonomers are olefin polymers having vinyl groups at their ends, and are ethylene polymers having vinyl groups at their ends obtained by ethylene homopolymerization or copolymerization of ethylene with olefins having 3 to 6 carbon atoms.

[0018] For the synthesis of macromonomers and copolymerization of macromonomers with ethylene, or macromonomers with ethylene and olefins having 3 to 6 carbon atoms, it is preferable to use a metallocene catalyst that employs a non-crosslinked bis(indenyl)zirconium complex, a non-crosslinked bis(cyclopentadienyl)zirconium complex, a crosslinked bis(cyclopentadienyl)zirconium complex, a crosslinked bis(indenyl)zirconium complex, a crosslinked (cyclopentadienyl)(indenyl)zirconium complex, a crosslinked (cyclopentadienyl)(fluorenyl)zirconium complex, or a crosslinked (indenyl)(fluorenyl)zirconium complex as the metallocene complex of the metallocene catalyst. Specific examples of metallocene complexes include, for example, bis(indenyl)zirconium dichloride, dimethylsilanediylbis(cyclopentadienyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(indenyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(2-methylindenyl)zirconium dichloride, dimethylsilanediyl(cyclopentadienyl)(4,7-dimethylindenyl)zirconium dichloride, and dimethylsilanediyl(cyclopentadienyl)(2,4,7 Examples of dichlorides such as -trimethylindenyl)zirconium dichloride, diphenylmethylene(1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride, diphenylmethylene(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride, and isopropylidene(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride, as well as dimethyl, diethyl, dihydro, diphenyl, and dibenzyl derivatives of the above transition metal compounds, can be cited. Compounds in which the zirconium atom of the above transition metal compound is substituted with a titanium atom or a hafnium atom can also be cited, but are not limited to these. One or more of these may be used, but it is particularly preferable to use one.

[0019] The activating co-catalyst used as a component of the metallocene catalyst is a compound that plays a role in converting the metallocene complex, or the reaction product of the metallocene complex and an organoaluminum compound, into an active species capable of polymerizing olefins. Preferably, it is a compound that generates a cationic compound from the metallocene complex, and the generated cationic compound acts as a polymerization active species capable of polymerizing olefins. The activating co-catalyst is a compound that, after forming a polymerization active species, weakly coordinates to or interacts with the generated cationic compound, but does not directly react with the active species.

[0020] Specific examples of activation co-catalysts include alkylaluminoxanes such as methylaluminoxane, silica gel-supported alkylaluminoxanes, tris(fluorinated aryl)borons such as tris(pentafluorophenyl)boron, boron compounds such as tetrakis(fluorinated aryl)boron salts such as N,N-dimethylammonium-tetrakis(pentafluorophenyl)boron, silica gel supports thereof, and clay minerals, as well as clay minerals treated with organic compounds. Among these activation co-catalysts, it is preferable to use clay minerals treated with organic compounds.

[0021] When using clay minerals treated with organic compounds as activation co-catalysts, it is preferable to use clay minerals belonging to the smectite group, with specific examples including montmorillonite, bydelite, saponite, and hectorite. It is also possible to use a mixture of these clay minerals.

[0022] Organic compound treatment refers to the process of introducing organic ions between clay mineral layers to form ion complexes. Examples of organic compounds used in organic compound treatment include alkylammonium salts such as N,N-dimethyl-n-octadecylamine hydrochloride, N,N-dimethyl-n-eicosylamine hydrochloride, N,N-dimethyl-n-docosylamine hydrochloride, N,N-dimethyloleylamine hydrochloride, N,N-dimethylbehenylamine hydrochloride, N-methyl-bis(n-octadecyl)amine hydrochloride, N-methyl-bis(n-eicosyl)amine hydrochloride, N-methyl-dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, and N,N-dimethylaniline hydrochloride.

[0023] There are no particular restrictions on the method of preparing the metallocene catalyst, such as a method of reacting a metallocene complex with an activation co-catalyst. Furthermore, during the preparation of the metallocene catalyst, alkylaluminum such as triethylaluminum or triisobutylaluminum may be used as needed to activate the metallocene complex or remove impurities from the solvent.

[0024] When producing the ethylene-based polymer (B), polymerization is preferably carried out at a polymerization temperature of -100 to 120°C, particularly 20 to 120°C considering productivity, and even more preferably in the range of 60 to 120°C. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of atmospheric pressure to 300 MPa. The polymerizable monomers are ethylene and α-olefins having 3 to 6 carbon atoms, and the supply ratio of ethylene to α-olefins having 3 to 6 carbon atoms (molar ratio) can be 1 to 200, preferably 3 to 100, and even more preferably 5 to 50. It is also possible to adjust the molecular weight using hydrogen or the like during polymerization. Polymerization can be carried out by batch, semi-continuous, or continuous methods, and it is also possible to carry out the polymerization in two or more stages by changing the polymerization conditions. The ethylene-α-olefin copolymer can be separated and recovered from the polymerization solvent by conventionally known methods after polymerization is complete, and then dried to obtain the copolymer.

[0025] Polymerization can be carried out in a slurry state, a solution state, or a gas phase state. In particular, when polymerization is carried out in a slurry state, ethylene-based polymers with uniform powder particle shapes can be produced efficiently and stably. Furthermore, ethylene-based polymer (B) can be produced by known methods such as those described in Japanese Patent Application Publication No. 2011-105934.

[0026] The preferred blending ratio of the high-density polyethylene (A) and the ethylene polymer (B) is 90-60% by weight of high-density polyethylene (A) and 10-40% by weight of the ethylene polymer (B) (the total of (A) and (B) is 100% by weight). Within this range, a container with excellent rigidity and transparency can be obtained.

[0027] The polyethylene resin composition can be obtained by mixing the aforementioned high-density polyethylene (A) and ethylene polymer (B) using conventionally known methods, such as a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., or by further melt-kneading the mixture obtained by such methods using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, etc., and then granulating it.

[0028] The polyethylene resin composition used in the present invention may contain, as appropriate and as necessary, commonly used known additives, such as antioxidants, neutralizing agents, antistatic agents, lubricants, antiblocking agents, antifogging agents, organic or inorganic pigments, ultraviolet absorbers, dispersants, etc., to the extent that they do not significantly impair the effects of the present invention. The method of incorporating the above-mentioned additives into the resin composition used in the present invention is not particularly limited, but examples include adding them directly in the pellet granulation process after polymerization, or preparing a high-concentration masterbatch in advance and dry-blending it during molding.

[0029] Furthermore, the polyethylene resin composition used in the present invention may also be blended with other thermoplastic resins such as ethylene-propylene copolymer rubber and poly-1-butene, within a range that does not impair the effects of the present invention.

[0030] A container according to one aspect of the present invention may be manufactured using any injection stretch blow molding method, as long as it includes an injection molding step of forming a bottomed preform by injection molding and a stretch blow molding step of introducing blow air into the preform and stretching the preform by pressing the bottom of the preform with a stretch rod. In order to maintain uniformity of the wall thickness of the container body, an injection stretch blow molding method is preferred, comprising an injection molding step of forming a bottomed preform by injection molding, a temperature control step of adjusting the temperature of the preform, and a stretch blow molding step of introducing blow air into the preform and stretching the preform by pressing the bottom of the preform with a stretch rod, wherein in the temperature control step, a temperature equalization treatment is performed by shrinking the preform in the longitudinal axis direction, and in the temperature equalization treatment, deformation of the preform in a direction intersecting the longitudinal axis direction is caused. As such an injection stretch blow molding method, the known method described in Japanese Patent Application Publication No. 2021-119056 can be applied. To improve the rigidity of the container through stretch orientation, in the stretch blow molding process, the stretch ratio is usually 1.2 times or more, preferably 2.0 times or more, in the height direction of the container (longitudinal stretch ratio). There are no particular limitations on the width direction of the container (lateral stretch ratio), but it is usually 1.2 times or more. In the stretch blow molding process, the stretch blow time can be appropriately set considering the stretch blow pressure, stretch ratio, and stretch speed.

[0031] Applications of a container according to one aspect of the present invention include medical containers, food containers, cosmetic containers, and the like. Examples of medical containers include infusion solution containers, ampoule containers, kit containers, eye drop containers, and the like. Examples of food containers include various beverage containers, concentrated beverage containers, seasoning containers, prepared food containers, dressing containers, mayonnaise and ketchup containers, various retort food containers, and baby bottles. Examples of cosmetic containers include containers for hair styling products, hair products, perfumes, hair dyes, eyeshadows, nail polishes, lotions, creams, emulsions, toners, and perm solutions. [Examples]

[0032] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0033] ~Resin~ The properties of the resins used in the examples and comparative examples were evaluated by the following method.

[0034] <mfr> The MFR (melt mass flow rate) was measured in accordance with JIS K6922-1 at 190°C and under a load of 21.18N.

[0035] <hlmfr> HLMFR was measured in accordance with JIS K6922-1 at 190°C and under a load of 211.8N.

[0036] <density> The density was measured using the density gradient pipe method in accordance with JIS K6922-1.

[0037] <Molecular weight, molecular weight distribution> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) were measured by GPC. A GPC instrument (HLC-8121GPC / HT, manufactured by Tosoh Corporation) and a column (TSKgel GMHhr-H(20)HT, manufactured by Tosoh Corporation) were used. The column temperature was set to 140°C, and 1,2,4-trichlorobenzene was used as the eluent. The sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected for measurement. The molecular weight calibration curve was calibrated using polystyrene samples with known molecular weights. Mw and Mn were determined as linear polyethylene equivalents.

[0038] <Long chain branching> The number of long-chain branchings per 1000 carbon atoms is determined by carbon nuclear magnetic resonance (CRN) using the Bruker AVANCE600 nuclear magnetic resonance spectrometer. 13 Carbon nuclear magnetic resonance (C-NMR) method of polymers 13 The 1C-NMR spectrum was measured, and the number of long-chain branches per 1000 carbon atoms in the polymer was determined using the calculation method described below. The measurement temperature was set to 130°C, and a mixture of 1,2-dichlorobenzene / 1,2-dichlorobenzene-d4 = 75 / 25 (volume ratio) was used as the solvent.

[0039] <Method for calculating the number of long chain branches (LCBs)> In NMR spectra processed with a Gaussian window function, the sum of the peak areas of all peaks with peak tops between 5 and 50 ppm was set to 1000. The number of long-chain branches (number of branches with 7 or more carbon atoms) was determined from the peak area of ​​the peak originating from the methine carbon to which branches with 7 or more carbon atoms are bonded. Under these measurement conditions, the number of long-chain branches (number of branches with 7 or more carbon atoms) was determined from the peak area of ​​the peak with peak tops around 38.22 to 38.27 ppm. The peak area of ​​the peak in question was defined as the signal area within the range from the chemical shift of the valley between adjacent peaks on the high-field side to the chemical shift of the valley between adjacent peaks on the low-field side. Under these measurement conditions, in the measurement of ethylene-1-octene copolymer, the peak top position of the peak originating from the methine carbon to which hexyl branches are bonded was 38.21 ppm.

[0040] In the examples and comparative examples, resins and commercially available products manufactured by the method described in the manufacturing example below were used.

[0041] Manufacturing example (1) High-density polyethylene For A-1, the following commercially available product was used.

[0042] Tosoh Corporation, (product name) Nipolon Hard 5110 (MFR = 0.9g / 10 min, density = 961kg / m³) 3 ) For A-2, the following commercially available product was used.

[0043] Tosoh Corporation, (product name) Nipolon Hard 8022 (MFR = 0.35 g / 10 min, density = 958 kg / m³) 3 ) For A-3, the following commercially available product was used.

[0044] Tosoh Corporation, (product name) Nipolon Hard 4020 (MFR = 5.4g / 10 min, density = 964kg / m³) 3 ) For A-4, polyethylene manufactured using the following method was used. [Preparation of organically modified clay] Add 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd., product name Ekinen F-3) and 300 ml of distilled water to a 1 liter flask, and add 15.0 g of concentrated hydrochloric acid and dioleylmethylamine ((C 18 H 35 63.7g (120 mmol) of 2(CH3)N (Lion Specialty Chemicals Co., Ltd., product name: Lipomin M2O) was added and heated to 45°C. Then, 100g of synthetic hectorite (BYK Co., Ltd., product name: Laponite RD) was dispersed in the mixture, and the temperature was raised to 60°C and maintained while stirring for 1 hour. After filtering off the slurry, it was washed twice with 600ml of 60°C water and dried in an 85°C dryer for 12 hours to obtain 130g of organically modified clay. This organically modified clay was pulverized with a jet mill to a median diameter of 15μm. [Preparation of polymerization catalyst] After purging a 300 mL flask equipped with a thermometer and reflux tubing with nitrogen, 25.0 g of the organically modified clay obtained in [Preparation of Organically Modified Clay] and 108 mL of hexane were added, followed by the addition of 0.392 g (1 mmol) of bis(indenyl) zirconium dichloride and 142 mL of 20% triisobutylaluminum, and the mixture was stirred at 60°C for 3 hours. After cooling to room temperature, the supernatant was removed, washed twice with 220 mL of hexane, and then 220 mL of hexane was added to obtain a catalyst suspension (solid weight: 12.0 wt%). [Manufacturing of A-4] 1.2 L of hexane and 1.0 mL of 20% triisobutylaluminum were added to a 2 L autoclave, along with 200 mg (equivalent to 24 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 85°C, and an ethylene / hydrogen mixed gas was continuously supplied to maintain a partial pressure of 0.90 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 450 ppm). After 90 minutes, the pressure was removed, the slurry was filtered off, and dried to obtain 205 g of polymer. The MFR of this polymer was 1.0 g / 10 min, and its density was 952 kg / m³. 3 That was the case.

[0045] Table 1 shows the results of the basic characteristic evaluation for A-1 to A-4. (2) Ethylene polymer B-1 [Preparation of modified clay] 300 mL of industrial alcohol (Ekinen F-3, manufactured by Nippon Alcohol Sales Co., Ltd.) and 300 mL of distilled water were placed in a 1 L flask. 15.0 g of concentrated hydrochloric acid and 42.4 g (120 mmol) of dimethylbehenylamine (Armin DM22D, manufactured by Lion Corporation) were added. The mixture was heated to 45°C to disperse 100 g of synthetic hectorite (Laponite RDS, manufactured by Rockwood Additives). The temperature was then raised to 60°C and the mixture was stirred for 1 hour while maintaining that temperature. After filtering the slurry, it was washed twice with 600 mL of 60°C water and dried in an oven at 85°C for 12 hours to obtain 122 g of organically modified clay. This organically modified clay was spray-dried to a median diameter of 15 μm. [Preparation of polymerization catalyst] After purging a 300 mL flask equipped with a thermometer and reflux tubing with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 mL of hexane were added, followed by 0.4406 g of dimethylsilylene (cyclopentadienyl) (2,4,7-trimethyl-1-indenyl) zirconium dichloride and 142 mL of 20% triisobutylaluminum, and the mixture was stirred at 60°C for 3 hours. After cooling to 45°C, the supernatant was removed, washed five times with 200 mL of hexane, and then 200 mL of hexane was added to obtain a catalyst suspension (solid weight: 12.0 wt%). [Manufacturing of B-1] In a 2 L autoclave, 1.2 L of hexane and 1.0 mL of 20% triisobutylaluminum were added, along with 358 mg (equivalent to 43 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. After heating to 70°C, 4.6 g of 1-butene was added, and an ethylene / hydrogen mixed gas was continuously supplied to maintain a partial pressure of 0.80 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 1600 ppm). After 90 minutes, the pressure was removed, the slurry was filtered off, and dried to obtain 86 g of polymer. The MFR of this polymer was 2.0 g / 10 min, and its density was 941 kg / m³. 3 It was as follows: Furthermore, the number-average molecular weight (Mn) was 2.0 × 10⁻⁶. 4 The weight-average molecular weight is 9.5 × 10⁻⁶. 4 The Mw / Mn ratio was 4.5, and the number of long-chain branches in the polymer was 1.6 per 1000 carbon atoms in the main chain.

[0046] Table 1 shows the results of the basic characteristics evaluation for B-1.

[0047] [Table 1]

[0048] ~Container Evaluation~ The evaluation methods for the containers used in the examples and comparative examples are shown below.

[0049] ~Evaluation of container thickness~ For wide-mouth screw bottles and narrow-mouth screw bottles manufactured using the method described in the examples, the container thickness was measured at 16 locations (4 in the height direction and 4 in the width direction) using a thickness gauge, and the average value was taken as the average thickness. The standard deviation obtained from the 16 data points was used as an indicator of thickness uniformity.

[0050] ○: Standard deviation is 0.1 mm or less ×: Standard deviation exceeds 0.1 mm ~Evaluation of surface appearance~ The surface appearance of wide-mouth screw bottles and narrow-mouth screw bottles manufactured by the method described in the examples was visually evaluated.

[0051] ○: The surface is glossy and free from patterns caused by uneven resin flow.

[0052] ×: The surface lacks gloss and has patterns caused by uneven resin flow.

[0053] ~Evaluation of Transparency~ Sample pieces measuring 1.0 mm thick and 50 mm square were cut from the body of a wide-mouth screw bottle manufactured by the method described in the examples, and sample pieces measuring 0.5 mm thick and 50 mm square were cut from a narrow-mouth screw bottle. The haze was measured using an NDH7000 type haze meter manufactured by Nippon Denshoku Industries, which conforms to the JIS K7136 standard.

[0054] ○: Haze is 70% or less ×: Haze exceeds 70% ~Evaluation of rigidity~ Strips measuring 1.0 mm thick, 3.3 mm wide, and 60 mm long were cut from the body of a wide-mouth screw bottle manufactured by the method described in the examples, and strips measuring 0.5 mm thick, 3.3 mm wide, and 60 mm long were cut from a narrow-mouth screw bottle. Tensile tests were performed using an Orientec Co., Ltd. Tensilon RTE-1210 tensile testing machine under the conditions of a tensile speed of 100 mm / min and a chuck distance of 30 mm. The slope of the stress-strain curve at a strain of 1% was taken from the obtained stress-strain curve and defined as the elastic modulus.

[0055] Example 1 (1) Manufacturing of resin composition High-density polyethylene (A-4) and ethylene polymer (B-1) were dry-blended in a ratio of 75:25 (parts by weight). This mixture was melt-extruded into strands using a 50mm diameter single-screw extruder manufactured by Placo, and then granulated into pellets using a pelletizer. The barrel temperatures were set to C1: 180°C, C2: 200°C, C3: 200°C, and die head: 200°C.

[0056] (2) Manufacturing of containers ~Container molding with a longitudinal stretching ratio of 2.3 times and a transverse stretching ratio of 2.6 times~ Using an injection stretch blow molding machine (ASB-12M) manufactured by Nissei ASB Machinery Co., Ltd., equipped with a 600ml narrow-mouth screw bottle mold, a preform with a height of 100mm and a width of 25mm was first molded using an injection molding extruder with a barrel temperature of 230°C, an injection pressure of 14MPa, an injection time of 5 seconds, and a cooling time of 2.5 seconds (cavity 50°C, inner core 20°C). The preform was then reheated using radiant heat from a heating pot and subjected to a temperature equalization treatment by shrinking it in the vertical direction. Since the heating pot allows for independent temperature control at three points in the height direction of the container (top, middle, and bottom), the temperatures at the three points of the heating pot were changed between 150 and 300°C while visually checking the degree of shrinkage of the preform to ensure uniform wall thickness of the preform body. By introducing blown air into a preform that had undergone a temperature-matching treatment, and by pressing the bottom of the preform with a stretching rod, a narrow-mouth screw bottle with a height of 230 mm, a width of 65 mm, and a body thickness of 0.5 mm was obtained. The results of the container evaluation are shown in Table 2.

[0057] Comparative Example 1 ~Container molding with a longitudinal stretching ratio of 1.0x and a transverse stretching ratio of 1.25x~ Using the resin composition described in Example 1, an injection stretch blow molding machine (ASB-12M) manufactured by Nissei ASB Machinery Co., Ltd., equipped with a 100 ml wide-mouth screw bottle mold, was first used to mold a preform with a height of 80 mm and a width of 30 mm. This was done at a barrel temperature of 220°C, an injection pressure of 14 MPa, an injection time of 3 seconds, and a cooling time of 2.5 seconds (cavity 60°C, inner core 60°C). Since no longitudinal stretching was performed, the temperature control process did not involve a uniform temperature treatment to shrink the preform in the longitudinal direction. Immediately after preform formation, blow air was introduced into the preform to obtain a wide-mouth screw bottle with a height of 80 mm, a width of 40 mm, and a body thickness of 1.0 mm.

[0058] Comparative Example 2 Using high-density polyethylene (A-4) as the container material, a wide-mouth screw bottle was obtained in the same manner as in Comparative Example 1. The results of the container evaluation are shown in Table 2.

[0059] Comparative Example 3 Using high-density polyethylene (A-1) as the container material, a wide-mouth screw bottle was obtained in the same manner as in Comparative Example 1. The results of the container evaluation are shown in Table 2.

[0060] Comparative Example 4 Using high-density polyethylene (A-2) as the container material, a wide-mouth screw bottle was obtained in the same manner as in Comparative Example 1. The results of the container evaluation are shown in Table 2.

[0061] Comparative Example 5 Using high-density polyethylene (A-3) as the container material, a wide-mouth screw bottle was obtained in the same manner as in Comparative Example 1. The results of the container evaluation are shown in Table 2.

[0062] Comparative Example 6 A narrow-mouth screw bottle was obtained using high-density polyethylene (A-4) as the container material, in the same manner as in Example 1. The results of the container evaluation are shown in Table 2.

[0063] Comparative Example 7 A narrow-mouth screw bottle was obtained using high-density polyethylene (A-1) as the container material, in the same manner as in Example 1. The results of the container evaluation are shown in Table 2.

[0064] Comparative Example 8 A narrow-mouth screw bottle was obtained using high-density polyethylene (A-2) as the container material, in the same manner as in Example 1. The results of the container evaluation are shown in Table 2.

[0065] Comparative Example 9 A narrow-mouth screw bottle was obtained using high-density polyethylene (A-3) as the container material, in the same manner as in Example 1. The results of the container evaluation are shown in Table 2.

[0066] [Table 2] < / hlmfr> < / mfr>

Claims

1. A single-layer container made of a polyethylene resin composition comprising 90 to 60% by weight of high-density polyethylene (A) satisfying the following characteristics (a) to (d), and 10 to 40% by weight of an ethylene polymer (B) satisfying the following characteristics (e) to (h) (total of (A) and (B) is 100% by weight), wherein the container satisfies the following characteristics (i) to (k). (a) Density measured in accordance with JIS K6922-1 (hereinafter referred to as density) of 950-960 kg / m³ ３ That is the case. (b) The melt mass flow rate (hereinafter referred to as MFR) measured in accordance with JIS K6924-1 at a temperature of 190°C and a load of 21.18 N is 0.3 to 4.0 g / 10 min. (c) In molecular weight measurement by gel permeation chromatography (hereinafter referred to as GPC), the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is in the range of 2.0 to 3.

0. (d) １３ The number of hexyl groups or more per 1000 carbon atoms (hereinafter referred to as LCB), determined from the measurement of the C-NMR spectrum, is less than 0.

5. (e) Density of 940–948 kg / m³ ３ That is the case. (f) The MFR is 0.3 to 3.0 g / 10 min. (g) In molecular weight measurement by GPC, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is in the range of 3.5 to 5.

0. (h) １３ The number of LCBs determined from the C-NMR spectrum measurement is between 0.5 and 2.

0. (i) The average thickness of the container body is 0.4 to 1.0 mm (j) The tensile modulus of the container body is 800 MPa or higher. (k) The haze on the container body is 70% or less.

2. The container according to claim 1, wherein the longitudinal stretching ratio is 1.2 times or more.

3. The container according to claim 1 or 2, wherein the transverse stretching ratio is 1.2 times or more.

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