JP2024048543A - Polyethylene resin composition and blow molded article - Google Patents

Abstract

[Problem] To provide a resin composition that makes it possible to manufacture hollow molded articles having mechanical strength and appearance comparable to conventional products while increasing the amount of recycled materials used. [Solution] A polyethylene resin composition that satisfies the specific requirements, comprising a recycled polyethylene resin (A) that satisfies specific requirements and an ethylene polymer (B) that satisfies specific requirements and contains a structural unit derived from at least one α-olefin having 4 to 10 carbon atoms, wherein, when the total content of components (A) and (B) is 100% by mass, the content of component (A) is in the range of 45% by mass to 95% by mass and the content of component (B) is in the range of 5% by mass to 55% by mass, and satisfies the specific requirements. [Selected Figure] None

Description

The present invention relates to a polyethylene resin composition and a blown molded article containing the composition.

Blow molding (hollow molding), especially direct blow molding, is a widely used method for molding containers. Containers made of high-density polyethylene have excellent impact resistance, weather resistance, and cold resistance, and are therefore widely used for storing fuel oils such as kerosene, cooking oils, water, detergents, and more.

On the other hand, because high-density polyethylene has a slightly inferior rigidity, it has been proposed to blend polypropylene, which has a higher rigidity than high-density polyethylene, with the high-density polyethylene (for example, Patent Document 1), or to blend polypropylene and an inorganic filler with high-density polyethylene (for example, Patent Document 2).

In addition, in recent years, with growing awareness of global environmental issues, various industries are seeking to develop products that reduce the burden on the environment. The field of hollow molded bodies is no exception to this demand, and the use of various recycled materials such as recycled polyethylene resins has been proposed (for example, Patent Documents 3 and 4).

Japanese Patent Application Laid-Open No. 8-112854 JP 2016-128570 A Patent No. 3299331 Japanese Patent No. 5792834

Considering environmental issues, it is desirable to use a large amount of recycled materials, but using a large amount of recycled materials can cause problems in the mechanical strength and appearance of the hollow molded article.
Therefore, one of the objects of the present invention is to provide a resin composition that can be used to produce a hollow molded article having mechanical strength and appearance comparable to those of conventional products while increasing the amount of recycled material used.

The present inventors conducted extensive research to solve the above problems. As a result, they discovered that the above problems can be solved, for example, by the following aspects.

[1]
A recycled polyethylene resin (A) that satisfies the following requirements (a1) and (a2);
and an ethylene-based polymer (B) which satisfies the following requirements (b1) and (b2) and contains at least one structural unit derived from an α-olefin having 4 to 10 carbon atoms,
When the total content of the components (A) and (B) is 100 mass%, the content of the component (A) is in the range of 45 mass% or more and 95 mass% or less, and the content of the component (B) is in the range of 5 mass% or more and 55 mass% or less,
A polyethylene resin composition satisfying the following requirements (1) to (3):
(a1) The melt flow rate at 190°C under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min;
(a2) density is in the range of 940 kg/m ³ or more and 980 kg/m ³ or less;
(b1) The melt flow rate at 190°C under a load of 2.16 kg is in the range of 0.005 to 1.0 g/10 min;
(b2) density is in the range of 930 kg/m ³ or more and 950 kg/m ³ or less;
(1) The melt flow rate at 190° C. under a load of 2.16 kg is in the range of 0.01 to 1.0 g/10 min;
(2) The melt flow rate at 190° C. under a load of 21.6 kg is in the range of 20 to 60 g/10 min;
(3) The density is in the range of 930 kg/ ^m3 or more and 970 kg/ ^m3 or less.

[2]
The composition further comprises an ethylene polymer (C) which satisfies the following requirements (c1) and (c2) and contains a structural unit derived from at least one α-olefin having 4 to 10 carbon atoms:
The polyethylene resin composition according to item [1], wherein the content of the component (A) is in the range of 40% by mass or more and 90% by mass or less, the content of the component (B) is in the range of 5% by mass or more and 50% by mass or less, and the content of the component (C) is in the range of 1% by mass or more and 40% by mass or less, when the total content of the components (A), (B) and (C) is 100% by mass:
(c1) The melt flow rate at 190° C. under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min.
(c2) The density is in the range of 900 kg/ ^m3 or more and less than 930 kg/ ^m3 .

[3]
The content of the component (A) is in the range of more than 50% by mass to 85% by mass or less,
The content of the component (B) is in the range of 8% by mass or more and 40% by mass or less,
The polyethylene resin composition according to item [2], wherein the content of the component (C) is in the range of 2% by mass or more and 30% by mass or less (wherein the total content of the components (A), (B) and (C) is 100% by mass).

[4]
The polyethylene resin composition according to item [1], wherein the component (A) further satisfies the following requirement (a3):
(a3) The recycled polyethylene resin is derived from PET bottle caps.

[5]
A blow molded article comprising the polyethylene resin composition according to any one of items [1] to [4].

By using the resin composition of the present invention, it is possible to produce hollow molded products that have the same mechanical strength and appearance as conventional products, even if the amount of recycled material used is increased, and this also contributes to an environmentally friendly society.

The present invention will be described in detail below.
The polyethylene resin composition of the present invention (hereinafter also simply referred to as "the composition of the present invention") contains a specific recycled polyethylene resin (A) and an ethylene polymer (B) described below.
[Recycled polyethylene resin]
The composition of the present invention contains a recycled polyethylene resin (A) that satisfies the following requirements (a1) and (a2).

<Requirement (a1)>
(a1) The melt flow rate ( _MFR2.16 ) at 190° C. under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min. The lower limit of the _MFR2.16 is preferably 0.2 g/10 min, more preferably 0.3 g/10 min, and the upper limit is preferably 4.5 g/10 min, more preferably 4.0 g/10 min.

When the MFR _2.16 of component (A) is within the above range, the composition of the present invention has excellent moldability and is capable of giving blown molded articles having good mechanical strength.

The melt flow rate (MFR) is strongly dependent on the molecular weight; the smaller the MFR, the higher the molecular weight, and the higher the MFR, the lower the molecular weight. It is also known that the molecular weight of an ethylene-based polymer is determined by the composition ratio of hydrogen to ethylene (hydrogen/ethylene) in the polymerization system (see, for example, Soga Kazuo et al., Catalytic Olefin Polymerization, Kodansha Scientific, 1990, p. 376). For this reason, it is possible to increase or decrease the MFR of an ethylene-based polymer by increasing or decreasing the hydrogen/ethylene ratio.

The melt flow rate (MFR _2.16 ) is measured in accordance with JIS K 7210 under conditions of 190° C. and a load of 2.16 kg (kgf).

<Requirement (a2)>
(a2) The density is in the range of 940 kg/m ³ or more and 980 kg/m ³ or less. The lower limit of the density is preferably 945 kg/m ³ , more preferably 950 kg/m ³ , and the upper limit is preferably 978 kg/m ³ , more preferably 975 kg/m ³ . The density is measured in accordance with JIS K 7112.

When the density of component (A) is within the above range, the resulting hollow molded body has good rigidity and impact strength, and the mechanical strength, such as the drop strength, of the hollow molded body is good.

Recycled polyethylene resins that can be used include those that are recycled by known methods from defective products that arise during the manufacture of various polyethylene resin products, and from various used and discarded polyethylene resin products. There are no particular limitations on the method for recycling polyethylene resins. Examples of such recycled polyethylene resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE). One or a blend of two or more of these recycled polyethylene resins that satisfy the above MFR and density are selected and used.

Preferred recycled polyethylene resins include copolymers of ethylene and α-olefins having 3 or more carbon atoms, preferably 3 to 20 carbon atoms (ethylene-α-olefin copolymers). Specific examples of the α-olefins in ethylene-α-olefin copolymers include propylene, butene, 1-octene, and 1-hexene.

It is preferable that the component (A) further satisfies the following requirement (a3).
<Requirement (a3)>
(a3) The recycled polyethylene resin is derived from a plastic bottle cap. The plastic bottle cap is manufactured by a general manufacturing method for a plastic bottle cap (compression molding or injection molding), and polyethylene or polypropylene is used.

Recycled polyethylene resin derived from PET bottle caps can be made by crushing or pelletizing PET bottle caps collected after use using a known method. More specifically, recycled polyethylene resin can be obtained by separating collected PET bottle caps into polyethylene-based and polypropylene-based caps using a spectroscopic method such as infrared spectroscopy (IR), crushing the separated polyethylene-based PET bottle caps, washing them with water, etc., and then melt-kneading and pelletizing them in an extruder.

[Ethylene-based polymer (B)]
The composition of the present invention contains an ethylene polymer (B) which satisfies the following requirements (b1) and (b2) and contains a structural unit derived from at least one α-olefin having 4 to 10 carbon atoms.

<Requirement (b1)>
(b1) The melt flow rate ( _MFR2.16 ) at 190° C. under a load of 2.16 kg is in the range of 0.005 to 1.0 g/10 min. The lower limit of the _MFR2.16 is preferably 0.01 g/10 min, more preferably 0.015 g/10 min, and the upper limit is preferably 0.8 g/10 min, more preferably 0.5 g/10 min.

When the MFR _2.16 of component (B) is within the above range, the composition of the present invention has excellent moldability. The melt flow rate (MFR _2.16 ) is measured in accordance with JIS K 7210 under conditions of 190° C. and a load of 2.16 kg (kgf).

<Requirement (b2)>
(b2) The density is in the range of 930 kg/m ³ or more and 950 kg/m ³ or less. The lower limit of the density is preferably 935 kg/m ³ , more preferably 940 kg/m ³ , and the upper limit is preferably 949 kg/m ³ . The density is measured in accordance with JIS K 7112.

By having the density of component (B) within the above range, the mechanical strength of the resulting hollow molded body is good.

Component (B) is a copolymer of ethylene and at least one α-olefin having 4 to 10 carbon atoms, specific examples of which include 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and 1-decene.

The ethylene-based polymer (B) may contain a biomass-derived monomer (ethylene, α-olefin). The monomers constituting the polymer may be only biomass-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers.

The biomass-derived monomer is a monomer made from any renewable natural raw material or its residue, such as plant- or animal-derived raw material, including fungi, yeast, algae, and bacteria, and contains ^{the 14C} isotope as carbon at a ratio of about ^10-12 , and has a biomass carbon concentration (pMC) of about 100 (pMC) measured in accordance with ASTM D 6866. The biomass-derived monomer is obtained by a conventionally known method.

It is preferable that the ethylene polymer (B) contains a biomass-derived monomer from the viewpoint of reducing the environmental load (mainly reducing greenhouse gases). If the polymer production conditions, such as the polymerization catalyst, the polymerization process, and the polymerization temperature, are the same, even if the raw material monomer contains a biomass-derived monomer, the molecular structure other than the content of ^14C isotopes in a ratio of about ^10-12 to ^10-14 is the same as that of an ethylene-α-olefin copolymer made of a fossil fuel-derived monomer. Therefore, the performance is said to be unchanged.

The ethylene-based polymer (B) may contain chemically recycled monomers (ethylene, α-olefin). The monomers constituting the polymer may be only chemically recycled monomers, or may contain chemically recycled monomers and fossil fuel-derived monomers and/or biomass-derived monomers. Chemically recycled monomers can be obtained by conventionally known methods.

It is preferable that the ethylene polymer (B) contains a monomer derived from chemical recycling from the viewpoint of reducing the environmental load (mainly reducing waste). Even if the raw material monomer contains a monomer derived from chemical recycling, the monomer derived from chemical recycling is a monomer obtained by depolymerizing or pyrolyzing a polymer such as waste plastic back into a monomer unit such as ethylene, as well as a monomer produced using the monomer as a raw material. Therefore, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure is the same as that of an ethylene-α-olefin copolymer made of a monomer derived from a fossil fuel. Therefore, the performance is said to be the same.

The content ratios of components (A) and (B) in the composition of the present invention are, when the total content of components (A) and (B) is 100 mass%,
The content of component (A) is in the range of 45% by mass or more and 95% by mass or less, preferably more than 50% by mass or more and 92% by mass or less, and more preferably 55% by mass or more and 88% by mass or less,
The content of component (B) is in the range of 5% by mass or more and 55% by mass or less, preferably 8% by mass or more and less than 50% by mass, and more preferably 12% by mass or more and less than 45% by mass.

By keeping the content ratios of components (A) and (B) within the above ranges, it is possible to produce hollow molded bodies that have the same mechanical strength and appearance as conventional products while increasing the amount of recycled material used.

[Ethylene-based polymer (C)]
It is preferable that the composition of the present invention further contains an ethylene polymer (C) which satisfies the following requirements (c1) and (c2) and contains a structural unit derived from at least one α-olefin having 4 to 10 carbon atoms.

<Requirement (c1)>
(c1) The melt flow rate ( _MFR2.16 ) at 190° C. under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min. The lower limit of the _MFR2.16 is preferably 0.2 g/10 min, more preferably 0.3 g/10 min, and the upper limit is preferably 4.5 g/10 min, more preferably 4.0 g/10 min.

When the MFR _2.16 of component (C) is within the above range, the composition of the present invention has excellent moldability and is capable of producing a hollow molded article having good mechanical strength. The melt flow rate (MFR _2.16 ) is measured in accordance with JIS K 7210 under conditions of 190°C and a load of 2.16 kg (kgf).

<Requirement (c2)>
(c2) Density is in the range of 900 kg/ ^m3 or more and less than 930 kg/ ^m3 , preferably 902 kg/ ^m3 or more and 928 kg/ ^m3 or less. When the density of component (C) is in the above range, the mechanical strength (particularly the drop strength) is improved. The density is measured in accordance with JIS K 7112.

Component (C) is a copolymer of ethylene and at least one α-olefin having 4 to 10 carbon atoms, specific examples of which include 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and 1-decene.

The ethylene-based polymer (C) may contain a biomass-derived monomer (ethylene, α-olefin). The monomers constituting the polymer may be only biomass-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers.

The biomass-derived monomer is a monomer made from any renewable natural raw material or its residue, such as plant- or animal-derived raw material, including fungi, yeast, algae, and bacteria, and contains ^{the 14C} isotope as carbon at a ratio of about ^10-12 , and has a biomass carbon concentration (pMC) of about 100 (pMC) measured in accordance with ASTM D 6866. The biomass-derived monomer is obtained by a conventionally known method.

It is preferable that the ethylene polymer (C) contains a biomass-derived monomer from the viewpoint of reducing the environmental load (mainly reducing greenhouse gases). If the polymer production conditions, such as the polymerization catalyst, the polymerization process, and the polymerization temperature, are the same, even if the raw material monomer contains a biomass-derived monomer, the molecular structure other than the content of ^14C isotopes in a ratio of about ^10-12 to ^10-14 is the same as that of an ethylene-α-olefin copolymer made of a fossil fuel-derived monomer. Therefore, the performance is said to be unchanged.

The ethylene-based polymer (C) may contain chemically recycled monomers (ethylene, α-olefin). The monomers constituting the polymer may be only chemically recycled monomers, or may contain chemically recycled monomers and fossil fuel-derived monomers and/or biomass-derived monomers. Chemically recycled monomers can be obtained by conventionally known methods.

It is preferable that the ethylene polymer (C) contains a monomer derived from chemical recycling from the viewpoint of reducing the environmental load (mainly reducing waste). Even if the raw material monomer contains a monomer derived from chemical recycling, the monomer derived from chemical recycling is a monomer obtained by depolymerizing or pyrolyzing a polymer such as waste plastic back into a monomer unit such as ethylene, as well as a monomer produced using the monomer as a raw material. Therefore, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure is the same as that of an ethylene-α-olefin copolymer made of a monomer derived from a fossil fuel. Therefore, the performance is said to be the same.

The content ratios of components (A), (B) and (C) in the composition of the present invention are, when the total content of components (A), (B) and (C) is 100 mass%,
The content of component (A) is in the range of 40% by mass or more and 90% by mass or less, preferably more than 50% by mass or more and 85% by mass or less, and more preferably 52% by mass or more and 82% by mass or less,
The content of component (B) is in the range of 5% by mass or more and 50% by mass or less, preferably 8% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 38% by mass or less,
The content of component (C) is in the range of 1 mass % or more and 40 mass % or less, preferably 2 mass % or more and 30 mass % or less, and more preferably 4 mass % or more and 25 mass % or less.

By keeping the content ratios of components (A), (B), and (C) within the above ranges, it is possible to produce hollow molded bodies that have the same mechanical strength and appearance as conventional products while increasing the amount of recycled materials used.

[Other ingredients]
The composition of the present invention may contain other additives, as necessary, such as a heat stabilizer, a weather stabilizer, a light stabilizer, an antiaging agent, an antioxidant, a fatty acid metal salt, a softener, a dispersant, a colorant, a pigment, an ultraviolet absorber, and a nucleating agent, as long as the object of the present invention is not impaired.

[Physical Properties of Polyethylene Resin Composition]
The composition of the present invention satisfies the following requirements (1) to (3).
<Requirement (1)>
(1) The melt flow rate ( _MFR2.16 ) at 190° C. under a load of 2.16 kg is in the range of 0.01 to 1.0 g/10 min. The lower limit of the _MFR2.16 is preferably 0.05 g/10 min, more preferably 0.1 g/10 min, and the upper limit is preferably 0.9 g/10 min, more preferably 0.8 g/10 min.

When the MFR _2.16 of the composition of the present invention is within the above range, a hollow molded article having excellent moldability and good mechanical strength can be obtained. The melt flow rate (MFR _2.16 ) is measured in accordance with JIS K 7210 under conditions of 190° C. and a load of 2.16 kg (kgf).

<Requirement (2)>
(2) The melt flow rate (MFR _21.6 ) at 190° C. under a load of 21.6 kg is in the range of 20 to 60 g/10 min. The lower limit of the MFR _21.6 is preferably 25 g/10 min, more preferably 30 g/10 min, and the upper limit is preferably 55 g/10 min.

When the MFR _21.6 of the composition of the present invention is within the above range, a hollow molded article having excellent moldability can be obtained. The melt flow rate (MFR _21.6 ) is measured in accordance with JIS K 7210 under conditions of 190° C. and a load of 21.6 kg (kgf).

<Requirement (3)>
(3) The density is in the range of 930 kg/m ³ or more and 970 kg/m ³ or less. The lower limit of the density is preferably 935 kg/m ³ , more preferably 940 kg/m ³ , and the upper limit is preferably 965 kg/m ³ , more preferably 960 kg/m ³ . The density is measured in accordance with JIS K 7112.

When the density of the composition of the present invention is within the above range, the resulting hollow molded body has good rigidity and impact strength, and the mechanical strength, such as the drop strength, of the hollow molded body is good.

[Method of producing polyethylene resin composition]
The composition of the present invention can be obtained by mixing the above-mentioned components using a dry blend, a Henschel mixer, a Banbury mixer or the like, or by mixing and then melt-kneading the components using a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder or the like.

[Molded body]
The composition of the present invention has excellent moldability, and can be used in various molding methods.Specific examples of the molded product of the present invention include injection molded products, foam molded products, injection foam molded products, extrusion molded products, hollow molded products, vacuum/pressure molded products, calendar molded products, stretched films, and inflation films, and hollow molded products are particularly preferred.The molding conditions for producing the molded product are not particularly limited, and known conditions can be adopted.

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

[material]
The polymers used in the examples and comparative examples are shown below.
<Recycled polyethylene resin (A)>
(A-1) Recycled polyethylene derived from PET bottle caps (MFR _2.16 : 1.5 g/10 min, density: 965 kg/m ³ )

<Ethylene-Based Polymer (B) or (B')>
(B-1) High density polyethylene ("Hi-Zex 8000F" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.03 g/10 min, density: 948 kg/m ³ )
(B'-2) High density polyethylene ("Hi-Zex 7800M" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.04 g/10 min, density: 954 kg/m ³ )
(B'-3) High density polyethylene ("Hi-Zex 8200B" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.03 g/10 min, density: 951 kg/m ³ )
(B'-4) High density polyethylene ("Hi-Zex 6008B" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.36 g/10 min, density: 955 kg/m ³ )

<Ethylene-Based Polymer (C)>
(C-1) Ethylene-based copolymer ("Evolue SP1510" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.9 g/10 min, density: 915 kg/m ³ )
(C-2) Ethylene-based copolymer ("Evolue SP3010" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.8 g/10 min, density: 926 kg/m ³ )
(C-3) Ethylene-based copolymer ("Evolue SP0510" manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 1.3 g/10 min, density: 904 kg/m ³ )
(C-4) Ethylene-based copolymer (Ultzekkusu 2005H, manufactured by Prime Polymer Co., Ltd., MFR _2.16 : 0.6 g/10 min, density: 919 kg/m ³ )

[Measurement and evaluation methods]
The physical properties of the polymers and ethylene-based resin compositions used in the examples and comparative examples were measured and evaluated by the following methods.

(1) Melt flow rate (MFR _2.16 ) (g/10 min)
The melt flow rate (MFR _2.16 ) was measured in accordance with JIS K 7210 under conditions of 190° C. and a load of 2.16 kg (kgf).

(2) Melt flow rate (MFR _21.6 ) (g/10 min)
The melt flow rate (MFR _21.6 ) was measured in accordance with JIS K 7210 under conditions of 230° C. and a load of 21.6 kg (kgf).

(3) Density (kg/ ^m3 )
The density was measured by a density gradient tube method in accordance with JIS K 7112, after the strand obtained during the MFR measurement was heat-treated at 100° C. for 1 hour and then allowed to stand at room temperature for 1 hour.

(4) Tensile Yield Stress Test pieces were prepared using the pellets obtained in the Examples and Comparative Examples in accordance with JIS K6921, and measurements were made in accordance with the method of JIS K7161.

(5) Nominal Tensile Strain at Break Test pieces were prepared according to JIS K6921 using the pellets obtained in the Examples and Comparative Examples, and measurements were made according to the method of JIS K7161.

(6) Flexural Modulus Test pieces were prepared using the pellets obtained in the Examples and Comparative Examples based on JIS K7151, and measurement was performed according to the method of JIS K7171.

(7) Charpy Impact Strength The Charpy impact strength of the test piece was measured in accordance with JIS K 7111-1 under the condition of 0° C. The measurement was performed on a notched test piece.

(8) Bottle Drop Strength Using a single-layer direct blow molding machine (Tahara Corp. blow molding machine MSE-50E), a die/core of 25/23 mmφ was used, and the molding temperature was 200° C., the discharge rate was 6.7 kg/hour, and the bottle weight was adjusted to 30 g. After 25 minutes had elapsed, a 1000 ml round bottle was shot-molded. The bottle drop strength was determined using the obtained round bottle as follows.

After filling the bottles with water and cooling them to ice temperature, a drop test was conducted. For example, if a bottle was dropped from a height of 2m and broke, the next bottle was dropped 0.2m lower, and if the bottle did not break after being dropped from a height of 2m, the next bottle was dropped 0.2m higher. A total of 20 bottles were dropped, and the weighted average of the heights at which they did not break was calculated and evaluated as the bottle drop strength.

(9) Bottle Appearance The 1000 ml round bottle prepared when measuring the bottle drop strength was cut into slices, and the inner surface of the bottle was visually observed. If any bumps or roughness due to melt fracture were observed on the inner surface of the bottle, it was marked as "X", and if no bumps or roughness were observed, it was marked as "O".

(10) Environmental friendliness Products that use recycled materials are marked with an "O" and products that do not use recycled materials are marked with an "X".

[Example 1]
As shown in Table 1, recycled polyethylene resin (A-1), ethylene polymer (B-1) and ethylene polymer (C-1) were dry blended in a ratio (mass ratio) of 60/25/15 (=A-1/B-1/C-1) and then blow molded to obtain a blown molded article made of an ethylene resin composition. The physical properties of the obtained ethylene resin composition and the blown molded article were measured and evaluated. The results are shown in Table 1.

The physical properties of the ethylene-based resin composition were measured using pellets obtained by dry blending each component, melt-kneading the components using a GM40-28 extruder manufactured by GM Sansho Co., Ltd. at a set temperature of 200°C and a screw rotation speed of 80 rpm, extruding the mixture into strands, and cutting the pellets.

[Examples 2 to 4 and Comparative Examples 1 to 4]
A blown molded article was produced in the same manner as in Example 1, except that the composition (type and blend ratio of each component) was used as shown in Table 1, and the physical properties of the obtained ethylene-based resin composition and the blown molded article were measured and evaluated. The results are shown in Table 1.

Claims (5)

A recycled polyethylene resin (A) that satisfies the following requirements (a1) and (a2);
and an ethylene-based polymer (B) which satisfies the following requirements (b1) and (b2) and contains at least one structural unit derived from an α-olefin having 4 to 10 carbon atoms,
When the total content of the components (A) and (B) is 100 mass%, the content of the component (A) is in the range of 45 mass% or more and 95 mass% or less, and the content of the component (B) is in the range of 5 mass% or more and 55 mass% or less,
A polyethylene resin composition satisfying the following requirements (1) to (3):
(a1) The melt flow rate at 190°C under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min;
(a2) density is in the range of 940 kg/m ³ or more and 980 kg/m ³ or less;
(b1) The melt flow rate at 190°C under a load of 2.16 kg is in the range of 0.005 to 1.0 g/10 min;
(b2) density is in the range of 930 kg/m ³ or more and 950 kg/m ³ or less;
(1) The melt flow rate at 190° C. under a load of 2.16 kg is in the range of 0.01 to 1.0 g/10 min;
(2) The melt flow rate at 190° C. under a load of 21.6 kg is in the range of 20 to 60 g/10 min;
(3) The density is in the range of 930 kg/ ^m3 or more and 970 kg/ ^m3 or less. The composition further comprises an ethylene polymer (C) which satisfies the following requirements (c1) and (c2) and contains a structural unit derived from at least one α-olefin having 4 to 10 carbon atoms:
The polyethylene resin composition according to claim 1, wherein the content of the component (A) is in the range of 40% by mass or more and 90% by mass or less, the content of the component (B) is in the range of 5% by mass or more and 50% by mass or less, and the content of the component (C) is in the range of 1% by mass or more and 40% by mass or less, when the total content of the components (A), (B) and (C) is 100% by mass:
(c1) The melt flow rate at 190° C. under a load of 2.16 kg is in the range of 0.1 to 5.0 g/10 min.
(c2) The density is in the range of 900 kg/ ^m3 or more and less than 930 kg/ ^m3 . The content of the component (A) is in the range of more than 50% by mass to 85% by mass or less,
The content of the component (B) is in the range of 8% by mass or more and 40% by mass or less,
3. The polyethylene resin composition according to claim 2, wherein the content of the component (C) is in the range of 2 mass % or more and 30 mass % or less (wherein the total content of the components (A), (B) and (C) is 100 mass %). The polyethylene resin composition according to claim 1, wherein the component (A) further satisfies the following requirement (a3):
(a3) The recycled polyethylene resin is derived from PET bottle caps. A blown molded article comprising the polyethylene resin composition according to any one of claims 1 to 4.