JP7367508B2 - multilayer blow container - Google Patents

Description

The present invention relates to multilayer blow containers.

In the field of multilayer blow containers, various thermoplastic resins are used, and among them, polyethylene has been studied and used because it exhibits excellent mechanical properties, thermal properties, chemical resistance, etc.

In recent years, as plastic waste (waste plastic) has become an international issue, efforts are being made to reduce the amount of plastic used and introduce new materials. There is a movement among companies to review the raw materials themselves and create new recycling systems. Under these circumstances, studies are underway to apply recycled materials to products in the field of multilayer blow containers using synthetic resins.

Regarding polyethylene resin, for example, as shown in Patent Document 1, it is made from an ethylene/α-olefin copolymer having 3 to 18 carbon atoms with specific properties produced using a recycled polyolefin resin and a metallocene catalyst. A recycled polyolefin resin composition is disclosed. However, it is difficult for the recycled polyolefin resin composition to exhibit sufficient rigidity due to the low density of the ethylene/α-olefin copolymer having 3 to 18 carbon atoms produced using a metallocene catalyst. Not suitable as a blow container.

Further, as shown in Patent Document 2, [A] (1) may contain units derived from an α-olefin having 3 to 6 carbon atoms in an amount less than 10 mol%, and (2) the density is 0.92 to 0.98 g/ ^cm3 , (3) has an intrinsic viscosity [η] of 0.4 to 10 dl/g, and (4) using a catalyst containing a metallocene compound represented by a specific structural formula. A modifier for high-density polyethylene characterized by comprising an ethylene-based polymer produced and [B] a resin composition for blow molding comprising a high-density polyethylene for blow molding other than the above [A] is disclosed. . However, since the modified material has a wide range of physical properties, it cannot be said that modifying the recycled material is sufficient to provide a blow container with excellent bottle ESCR (durability).

Furthermore, as shown in Patent Document 3, the specific polyethylene component (A) is 10 to 40% by mass, the specific polyethylene component (B) is 5 to 50% by mass, and the specific polyethylene component (C) is 40 to 85% by mass. Contains mass%, characteristic (1): MFR is 0.1 to 1 g/10 minutes, characteristic (2): HLMFR is 10 to 50 g/10 minutes, characteristic (3): HLMFR/MFR is 50 to 140.Property (4): Density is 0.940 to 0.965g/ ^cm3.Property (5): Measured at a temperature of 170°C and an elongation strain rate of 0.1 (unit: 1/sec). Polyethylene that satisfies the property that an inflection point in the extensional viscosity due to strain hardening is observed in a logarithmic plot of the extensional viscosity η(t) (unit: Pa・sec) and extension time t (unit: seconds). Although a resin composition is disclosed and it is disclosed that molded bodies can be produced by various molding methods such as blow molding, injection molding, inflation molding, and extrusion molding, there is no suggestion of application to the field of recycled materials.

In addition, as shown in Patent Document 4, the component (A) and component (B) with specific properties are ethylene/α-olefin copolymers polymerized with a metallocene catalyst, and are polymerized in multiple stages in this order. A polyethylene resin composition and a modifier are disclosed, which are characterized by satisfying specific properties such as (i) density, (ii) HLMFR, and the like. However, there is no suggestion regarding specific recycled materials and their application to fields of use.

On the other hand, regarding blow containers, for example, as shown in Patent Document 5, in a multilayer blow container consisting of at least three types, the intermediate layer is made of a heat-treated recycled material of the same type of polyolefin as the polyolefin of the inner and outer layers. , and the thickness of the intermediate layer is 60% to 80% of the total thickness.

In addition, as shown in Patent Document 6, it is formed by blow molding an extruded cylindrical multilayer parison, has a mouth part, a shoulder part, a body part, and a bottom part, and has at least an outer layer, an inner layer, and one intermediate layer. A multi-layer blow container formed from the above, wherein the outer layer and the inner layer are formed of the same synthetic resin, the intermediate layer is formed from a recycled material whose main component is the synthetic resin forming the inner and outer layers, and the parison is extruded. A multilayer blow container is disclosed, which is characterized in that a non-forming area where the intermediate layer is not formed, or a thin layer area where the intermediate layer is thinner than other parts is formed in a predetermined range along the direction. .

Japanese Patent Application Publication No. 8-127676 Japanese Patent Application Publication No. 9-095571 JP2017-179256A Patent No. 6281371 Patent No. 2757688 Japanese Patent Application Publication No. 2008-55808

Under these circumstances, it is desired to apply recycled materials to multilayer blow products, reduce the amount of plastic used, and solve the problem of plastic waste (waste plastic).

The purpose of the present invention is to reduce the amount of plastic used by applying recycled materials to multilayer blown polyethylene containers in the molding of polyethylene multilayer blown containers, and to reduce the amount of plastic used. The aim is to solve the problem of plastic.

As a result of extensive research in order to solve the above problems, the present inventors have found that, in a multilayer blow container having at least an outer layer and an inner layer, by using recycled polyolefin resin and polyethylene resin with specific properties in the outer layer and/or inner layer. They discovered that the problem of plastic waste (waste plastic) could be solved by applying recycled materials to multilayer blow products, reducing the amount of plastic used, and completed the present invention.

That is, according to the first aspect of the present invention, there is provided a multilayer blow container having at least an outer layer and an inner layer, and at least one of the outer layer and the inner layer has the following characteristics (2-1) to (2-4). is a resin composition containing metallocene polyethylene that satisfies the following, and the intermediate layer between the outer layer and the inner layer is a recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5),
A multilayer blow container is provided that contains the resin composition containing the metallocene polyethylene in an amount of 5% by mass or more based on the total mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

Further, according to a second aspect of the present invention, there is provided a multilayer blow container having at least an outer layer and an inner layer, wherein at least one of the outer layer and the inner layer has the following characteristics (2-1) to (2-4). It is a resin composition containing metallocene polyethylene that satisfies the following, and the intermediate layer between the outer layer and the inner layer is a recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5) in an amount of 1 to 95% by mass. and a recycled resin composition consisting of 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies the following characteristics (2-1) to (2-4),
A multilayer blow container is provided that contains the resin composition containing the metallocene polyethylene in an amount of 5% by mass or more based on the total mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

Further, according to a third aspect of the present invention, there is provided a multilayer blow container having at least an outer layer and an inner layer, wherein the outer layer is made of recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5). The inner layer is a resin composition containing metallocene polyethylene that satisfies the following properties (2-1) to (2-4),
A multilayer blow container is provided that contains the resin composition containing the metallocene polyethylene in an amount of 5% by mass or more based on the total mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

According to a fourth aspect of the present invention, there is provided a multilayer blow container having at least an outer layer and an inner layer, wherein the inner layer is made of recycled polyolefin resin satisfying the following characteristics (1-1) to (1-5). The outer layer is a resin composition containing metallocene polyethylene that satisfies the following properties (2-1) to (2-4),
A multilayer blow container is provided that contains the resin composition containing the metallocene polyethylene in an amount of 5% by mass or more based on the total mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

Further, according to a fifth aspect of the present invention, there is provided a multilayer blow container having at least an outer layer and an inner layer, wherein at least one of the outer layer and the inner layer has the following characteristics (1-1) to (1-5). A recycled resin composition containing 1 to 95% by mass of recycled polyolefin resin that satisfies the following and 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies the following properties (2-1) to (2-4). can be,
A multilayer blow container is provided that contains the resin composition containing the metallocene polyethylene in an amount of 5% by mass or more based on the total mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

According to the sixth aspect of the present invention, in the multilayer blow container, the resin composition containing metallocene polyethylene contains 10% by mass or more and 40% by mass or less of a polyethylene component polymerized by a metallocene catalyst, chromium The polyethylene component polymerized by a system catalyst may be contained in a range of 5% by mass to 50% by mass, and the polyethylene component polymerized by a Ziegler catalyst may be contained in a range of 40% by mass to 85% by mass.

According to the seventh aspect of the present invention, in the multilayer blow container, the polyethylene component polymerized by the metallocene catalyst has a melt flow rate (HLMFR) of 0.2 g at a temperature of 190° C. and a load of 21.6 kg. /10 minutes or more and less than 5 g/10 minutes, and may be polyethylene having a density of 0.915 g/cm ³ or more and 0.945 g/cm ³ or less.

According to the eighth aspect of the present invention, in the multilayer blow container, the polyethylene component polymerized by the chromium-based catalyst has an HLMFR of 2 g/10 minutes or more and less than 20 g/10 minutes, and a density of 0. It may be polyethylene having a weight of more than .945 g/cm ³ but not more than 0.965 g/cm ³ .

According to the ninth aspect of the present invention, in the multilayer blow container, the polyethylene component polymerized by the Ziegler catalyst has a melt flow rate (MFR) of 10 g/10 minutes at a temperature of 190° C. and a load of 2.16 kg. The polyethylene may have a density of 200 g/10 minutes or less and a density of 0.956 g/cm ³ or more and 0.980 g/cm ³ or less.

According to the present invention, in a polyethylene multilayer blow container, recycled materials are applied to the multilayer blow product, the amount of plastic used is reduced, the problem of plastic waste (waste plastic) is solved, and the blow container By modifying the recycled material, it is possible to provide a blow container with excellent bottle ESCR (durability) and appearance.

A first aspect of the multilayer blow container of the present invention is a resin composition in which at least one of the outer layer and the inner layer contains metallocene polyethylene that satisfies the following characteristics (2-1) to (2-4), The intermediate layer between the outer layer and the inner layer is a recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5), and the metallocene polyethylene is added to the total mass of the multilayer blow container. This is a multilayer blow container containing 5% by mass or more of a resin composition.
Further, in a second aspect of the multilayer blow container of the present invention, at least one of the outer layer and the inner layer is made of a resin composition containing metallocene polyethylene that satisfies the following properties (2-1) to (2-4). 1 to 95% by mass of recycled polyolefin resin in which the intermediate layer between the outer layer and the inner layer satisfies the following properties (1-1) to (1-5) and the following properties (2-1) to (2). -4) is a recycled resin composition consisting of 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies It is a multilayer blow container containing at least % by mass.
Further, in a third aspect of the multilayer blow container of the present invention, the outer layer is made of recycled polyolefin resin that satisfies the following properties (1-1) to (1-5), and the inner layer is made of recycled polyolefin resin that satisfies the following properties (2-1) to (1-5). ) to (2-4), which is a resin composition containing metallocene polyethylene, and which contains 5% by mass or more of the resin composition containing metallocene polyethylene based on the entire mass of the multilayer blow container. It is.
Further, in a fourth aspect of the multilayer blow container of the present invention, the inner layer is made of a recycled polyolefin resin that satisfies the following properties (1-1) to (1-5), and the outer layer is made of a recycled polyolefin resin that satisfies the following properties (2-1) to (1-5). ) to (2-4), which is a resin composition containing metallocene polyethylene, and which contains 5% by mass or more of the resin composition containing metallocene polyethylene based on the entire mass of the multilayer blow container. It is.
Further, in a fifth aspect of the multilayer blow container of the present invention, at least one of the outer layer and the inner layer contains 1 to 95% by mass of recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5). It is a recycled resin composition containing 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies the following characteristics (2-1) to (2-4), based on the entire mass of the multilayer blow container. This is a multilayer blow container containing 5% by mass or more of a resin composition containing the metallocene polyethylene.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more.

Hereinafter, the present invention will be explained in detail item by item.
In the present invention, the polyethylene resin is a general term for an ethylene homopolymer and a copolymer of ethylene and an olefin described below, and can also be referred to as an ethylene polymer.
Furthermore, in this specification, "~" indicating a numerical range is used to include the numerical values written before and after it as a lower limit value and an upper limit value.

1. Recycled Polyolefin Resin In the present invention, recycled polyolefin resin (recycled material) means a polyolefin resin recovered and recycled after molding and/or use. Specifically, we collect burrs, defective products, off-products, by-products, etc. that occur during the polyolefin resin molding process, as well as unused or used molded products that have been molded into products, and reuse them. Examples include recycled materials and recycled plastic materials.
Furthermore, in this specification, recycled plastic materials are defined in JIS Q14021:2000 as "materials that are reprocessed from recovered [recycled] materials in the manufacturing process and are used in final products or parts that are incorporated into products." means.
The recycled polyolefin resin of the present invention contains 60% by mass of one or more ethylene polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. % or more, preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 100% by mass.
In the present invention, it can be confirmed that the recycled polyolefin resin contains an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, for example, by Raman scattering. It can also be identified by measuring its spectrum.
It should be noted that if the recycled polyolefin resin used in the present invention is commercially available, it is preferably one whose quality has been controlled and quality certified by a commercial company. In addition, for quality control of recycled plastic materials, for example, guidelines based on standards defined in JIS Q9091:2016 can be referred to. Specific examples of the recycled polyolefin resin include, for example, HDPE "HA" manufactured by Mie Kasei Co., Ltd., but there are no particular limitations as long as it satisfies the characteristics requirements of the present invention.
Recycled polyolefin resin often has deteriorated physical properties compared to virgin materials, so in the multilayer blow container of the present invention, the decrease in physical properties is minimized and physical properties comparable to or higher than virgin materials are developed. It is important that it is something that can be done.
It is important that the recycled polyolefin resin of the present invention satisfies the following characteristics (1-1) to (1-5).

Characteristics of recycled polyolefin resin (1-1)
In the present invention, the recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ , preferably 0.945 to 0.960 g/cm ³ , and more preferably 0.950 to 0.957 g/cm 3 . It is important to choose one that is ^cm3 . If the density of the recycled polyolefin resin is less than 0.940 g/cm ³ , the recycled polyolefin resin may lack rigidity and the crystallization rate may decrease, resulting in a decrease in the molding cycle of the molded product. On the other hand, if the density exceeds 0.970 g/cm ³ , the bottle ESCR of the molded product may decrease. Moreover, if the density is within the above range, the miscibility of the recycled polyolefin resin with a resin composition containing metallocene polyethylene, which will be described later, will be good.
Density can be measured in accordance with JIS K6922-1, 2:1997.

Characteristics of recycled polyolefin resin (1-2)
In the present invention, the recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes, preferably 0.15 to 5 g/10 minutes, measured at a temperature of 190°C and a load of 2.16 kg. It is important to select one that has a content of 0.2 to 2 g/10 minutes, and more preferably 0.2 to 2 g/10 minutes. If the MFR of the recycled polyolefin resin is less than 0.1 g/10 minutes, the fluidity of the recycled polyolefin resin will decrease, which may increase the amount of resin heat generated due to extruder motor load and shearing during molding, and may cause shark skin. Flow instability phenomena such as melt fractures are more likely to occur, which may impair the appearance of the molded product. On the other hand, if this MFR exceeds 10 g/10 minutes, the impact resistance and bottle ESCR of the molded product cannot be achieved, and there is a risk that the drop impact resistance and long-term durability of the molded product will decrease. Moreover, if the MFR is within the above range, the miscibility of the recycled polyolefin resin with a resin composition containing metallocene polyethylene described later will be good.
MFR can be measured in accordance with JIS K6922-2:1997.

Furthermore, in the present invention, the recycled polyolefin resin has a melt flow rate (HLMFR) of 10 to 100 g/10 minutes, preferably 15 to 80 g/10 minutes, measured at a temperature of 190° C. and a load of 21.6 kg. More preferably, it is important to select one with a rate of 20 to 50 g/10 minutes. If the HLMFR of the recycled polyolefin resin is less than 10 g/10 minutes, the fluidity of the recycled polyolefin resin will decrease, which may increase the amount of heat generated by the extruder motor and shear during molding, and may cause problems such as sharkskin and melt. Since flow instability phenomena such as fractures are more likely to occur, the appearance of the molded product may be impaired. On the other hand, if this HLMFR exceeds 100 g/10 minutes, the impact resistance and bottle ESCR of the molded product cannot be achieved, and there is a risk that the drop impact resistance and long-term durability of the molded product will decrease. Moreover, if the HLMFR is within the above range, the miscibility of the recycled polyolefin resin with a resin composition containing metallocene polyethylene, which will be described later, will be good.
HLMFR can be measured in accordance with JIS K6922-2:1997.

Characteristics of recycled polyolefin resin (1-3)
In the present invention, it is important to select a recycled polyolefin resin having a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140, preferably 50 to 110, and more preferably 60 to 90. be. HLMFR/MFR has a strong correlation with molecular weight distribution; when HLMFR/MFR takes a large value, the molecular weight distribution becomes wide, and when HLMFR/MFR takes a small value, the molecular weight distribution becomes narrow. If the HLMFR/MFR exceeds 140, the pinch-off strength of the bottle molded product may decrease, and if the HLMFR/MFR exceeds 40, the melt tension of the bottle molded product may decrease, and melt fracture is likely to occur during resin extrusion. Moreover, if HLMFR/MFR is within the above range, the miscibility of the recycled polyolefin resin with a resin composition containing metallocene polyethylene, which will be described later, will be good.

Characteristics of recycled polyolefin resin (1-4)
In the present invention, the recycled polyolefin resin has an environmental stress cracking resistance (bottle ESCR) of less than 100 hours. As mentioned above, recycled polyolefin resins usually have lower physical properties than virgin materials, and the recycled polyolefin resin of the present invention preferably has an environmental stress cracking resistance (bottle ESCR) of 1 hour or more at the lower limit. is 10 hours or more, but targets those whose upper limit is less than 100 hours. In addition, in the present invention, by combining a resin composition containing a specific metallocene polyethylene, it is possible to exhibit environmental stress cracking resistance (bottle ESCR) equivalent to or higher than that of containers molded using virgin materials. be.
Environmental stress cracking resistance (bottle ESCR) is determined by applying a nonionic surfactant (manufactured by Sigma-Aldrich: polyoxyethylene (9) nonylphenyl ether) to a cylindrical container (bottle) with an internal volume of 760 ml that is made by multilayer blow molding. Fill with 190 ml of an aqueous solution diluted to 33% by mass of Igepar CO-630), seal the container with a molten parison made of the same material as the container, and store the sealed container in a constant temperature bath at a temperature of 65 ° C. It can be determined by measuring the time until the container breaks. This measurement is performed on 10 identical containers, and the time when 5 or more of the 10 containers are damaged is defined as the bottle ESCR value.

Characteristics of recycled polyolefin resin (1-5)
In the present invention, the recycled polyolefin resin preferably has a carbonyl group content of less than 5.0% by mass due to the maleic anhydride-containing compound, and more preferably does not contain carbonyl groups. The content of the carbonyl group contained in the recycled polyolefin resin can be measured by infrared absorption spectrum analysis, and preferably no absorption peaks are observed at 1710 cm ⁻¹ and 1790 cm ⁻¹ . The presence of a carbonyl group resulting from a maleic anhydride-containing compound is undesirable because it may lead to the formation of gel or the like in the molded product.
In order to ensure that the recycled polyolefin resin does not contain carbonyl groups caused by maleic anhydride-containing compounds, it is important that the recycled polyolefin resin undergoes quality control and quality certification so that it does not contain carbonyl groups.

Characteristics of recycled polyolefin resin (1-6)
In the present invention, the recycled polyolefin resin usually has a tensile impact strength of less than 300 kJ/m ² , and many have a tensile impact strength of approximately 130 kJ/m ² or less. Recycled polyolefin resins usually have lower physical properties than virgin materials, and the recycled polyolefin resin of the present invention has a lower limit of tensile impact strength of 10 kJ/m ² or more, preferably 20 kJ/m ² or more, The target is those whose upper limit is less than 300 kJ/m ² or less than 150 kJ/m ² . In the present invention, by combining a resin composition containing a specific metallocene polyethylene, it is possible to exhibit impact resistance equal to or higher than that of a container molded using virgin material.
The tensile impact strength was determined by making a 1.5 mm compression molded sheet in accordance with JIS K6922-2, and making a test piece by punching it with an S-shaped dumbbell in accordance with ASTM D1822, at 23°C and 50% RH. It can be measured under the following conditions.

Characteristics of recycled polyolefin resin (1-7)
In the present invention, the content of additives in the recycled polyolefin resin is preferably 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. In the present invention, additives include ordinary olefin polymers, rubber, etc., as well as antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, antifogging agents, antiblocking agents, and processing aids. Contains known additives such as colored pigments, crosslinking agents, blowing agents, inorganic or organic fillers, flame retardants, etc., such as antioxidants (phenolic, phosphorus, sulfur), lubricants, antistatic agents, light Examples include stabilizers and ultraviolet absorbers. Examples of fillers include calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silica, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can.
In the present invention, when the content of the additive exceeds 10% by mass, the environmental stress cracking resistance (bottle ESCR) of the multilayer blow container tends to decrease.
In the present invention, the type and content of the additive can be analyzed by a conventional analytical method.

2. Resin composition containing metallocene polyethylene The resin composition containing metallocene polyethylene of the present invention may be a mixture of two or more types of polyethylene. Note that the resin composition containing metallocene polyethylene of the present invention is not a recycled material but a normal virgin material. That is, in the present invention, a resin composition containing metallocene polyethylene means a resin that is not recovered and recycled after molding and/or use, and if it is a recycled material, that fact is clearly indicated.
It is important that the resin composition containing the metallocene polyethylene of the present invention satisfies the following properties (2-1) to (2-4).

Characteristics of resin compositions containing metallocene polyethylene (2-1)
In the present invention, the resin composition containing metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ , preferably 0.952 to 0.960 g/cm ³ , more preferably 0.953 g/cm 3 It is important to select one with a weight of ~0.958 g/cm ³ . If the density of the resin composition containing metallocene polyethylene is less than 0.940 g/ ^cm3 , the rigidity of the resin composition containing metallocene polyethylene will be insufficient and the crystallization rate will decrease, resulting in the formation of molded articles. There is a risk that the molding cycle will be reduced. On the other hand, if the density exceeds 0.970 g/cm ³ , the bottle ESCR of the molded product may decrease. Moreover, if the density is within the above range, the miscibility of the recycled polyolefin resin and the resin composition containing metallocene polyethylene will be good.
Density can be measured in accordance with JIS K6922-1, 2:1997.
The density can be adjusted by the amount of α-olefin during polymerization of the components constituting the polyethylene resin, and can also be adjusted by the blending ratio of the components constituting the polyethylene resin.

Characteristics of resin compositions containing metallocene polyethylene (2-2)
In the present invention, the resin composition containing metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes, and the lower limit of the MFR is preferably 0.15 g/10 minutes or more and 0.20 g/10 minutes. The upper limit of the MFR is preferably 8 g/10 minutes or less, 6 g/10 minutes or less, 4 g/10 minutes or less, and 3 g/10 minutes or more. /10 minutes or less, and 1g/10 minutes or less.
If this MFR is less than 0.1 g/10 minutes, the fluidity of the resin composition containing metallocene polyethylene may decrease, which may increase the amount of heat generated from the resin due to the extruder motor load and shearing during molding. Flow instability phenomena such as shark skin and melt fracture are more likely to occur, which may impair the appearance of the molded product. On the other hand, if this MFR exceeds 10 g/10 minutes, the impact resistance and bottle ESCR of the molded product cannot be achieved, and there is a risk that the drop impact resistance and long-term durability of the molded product will decrease. Moreover, if MFR is within the above range, the miscibility of the recycled polyolefin resin and the resin composition containing metallocene polyethylene will be good.
MFR can be measured in accordance with JIS K6922-2:1997.
The MFR of the polyethylene resin can be adjusted by the amount of hydrogen and temperature during polymerization of the components constituting the polyethylene resin, and the blending ratio of the components constituting the polyethylene resin.

Further, in the present invention, the resin composition containing metallocene polyethylene has an HLMFR of 10 to 100 g/10 minutes, and the lower limit of the HLMFR is preferably 11 g/10 minutes or more, 12 g/10 minutes or more, 13 g/10 minutes or more. 10 minutes or more, 14 g/10 minutes or more, and the upper limit of the HLMFR is preferably 95 g/10 minutes or less, 90 g/10 minutes or less, 85 g/10 minutes or less, and 80 g/10 minutes or less.
If this HLMFR is less than 10 g/10 minutes, the fluidity of the resin composition containing metallocene polyethylene will decrease, which may increase the amount of heat generated from the resin due to extruder motor load and shearing during molding. Flow instability phenomena such as melt fractures are more likely to occur, which may impair the appearance of the molded product. On the other hand, if this HLMFR exceeds 100 g/10 minutes, the impact resistance and bottle ESCR of the molded product cannot be achieved, and there is a risk that the drop impact resistance and long-term durability of the molded product will decrease. Moreover, if HLMFR is within the above range, the miscibility of the recycled polyolefin resin and the resin composition containing metallocene polyethylene will be good.
HLMFR can be measured in accordance with JIS K6922-2:1997.
The HLMFR of the polyethylene resin can be adjusted by the amount of hydrogen and temperature during polymerization of the components constituting the polyethylene resin, and the blending ratio of the components constituting the polyethylene resin.

Characteristics of resin compositions containing metallocene polyethylene (2-3)
In the present invention, the resin composition containing metallocene polyethylene has an HLMFR/MFR of 40 to 140, and the lower limit of the HLMFR/MFR is preferably 40 or more, 45 or more, 50 or more, 55 or more, and The upper limit of the HLMFR/MFR is preferably 135 or less, 130 or less, or 125 or less from the viewpoint of the impact resistance of the molded product.
HLMFR/MFR has a strong correlation with molecular weight distribution; when HLMFR/MFR takes a large value, the molecular weight distribution becomes wide, and when HLMFR/MFR takes a small value, the molecular weight distribution becomes narrow. If HLMFR/MFR exceeds 140, the impact resistance of the molded product may decrease, and if HLMFR/MFR exceeds 39, the melt tension of the molded product may decrease or the bottle ESCR of the molded product may decrease. Moreover, if HLMFR/MFR is within the above range, the miscibility of the recycled polyolefin resin and the resin composition containing metallocene polyethylene will be good.
The method for controlling HLMFR/MFR can be carried out mainly in accordance with the method for controlling molecular weight distribution.

Characteristics of resin compositions containing metallocene polyethylene (2-4)
In the present invention, the resin composition containing metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more, preferably 310 kJ/m ² or more, and more preferably 350 kJ/m ² or more. Further, the upper limit of the tensile impact strength of the resin composition containing metallocene polyethylene is not particularly limited, but is usually about 800 kJ/m ² or less. It is difficult for Ziegler-based polyethylene resin alone or chromium-based polyethylene resin alone to exhibit the high tensile impact strength that resin compositions containing metallocene-based polyethylene have. By using a resin having a tensile impact strength of 300 kJ/m ² or more, the tensile impact strength of the composition with the recycled polyolefin resin can be increased.
The tensile impact strength was determined by making a 1.5 mm compression molded sheet in accordance with JIS K6922-2, and making a test piece by punching it with an S-shaped dumbbell in accordance with ASTM D1822, at 23°C and 50% RH. It can be measured under the following conditions.

Characteristics of resin compositions containing metallocene polyethylene (2-5)
The resin composition containing metallocene polyethylene used in the present invention may be a mixture of two or more types of polyethylene as long as it satisfies the above-mentioned characteristics. can be used. The resin composition containing the metallocene-based polyethylene is preferably a resin composition containing a polyethylene component polymerized with a metallocene-based catalyst, a polyethylene component polymerized with a chromium-based catalyst, and a polyethylene component polymerized with a Ziegler catalyst. 10% by mass or more and 40% by mass or less of a polyethylene component polymerized by a catalyst, 5% by mass or more and 50% by mass or less of a polyethylene component polymerized by a chromium catalyst, and 40% by mass or more of a polyethylene component polymerized by a Ziegler catalyst. A resin composition containing 85% by mass or less is preferable, and more preferably a resin composition containing 15% by mass or more and 35% by mass or less of a polyethylene component polymerized with a metallocene catalyst, and 10% by mass or more of a polyethylene component polymerized with a chromium catalyst. , 40% by mass or less, and 45% by mass or more and 75% by mass or less of a polyethylene component polymerized by a Ziegler catalyst. More preferably, the polyethylene component polymerized with a metallocene catalyst is 20% by mass or more and 30% by mass or less, the polyethylene component polymerized with a chromium catalyst is 10% by mass or more and 30% by mass or less, and the polyethylene component polymerized with a Ziegler catalyst is The composition preferably contains a polyethylene component of 50% by mass or more and 70% by mass or less. As the metallocene catalyst, chromium catalyst, and Ziegler catalyst, commonly known polymerization catalysts can be used, and preferably, the polymerization catalyst described in JP-A No. 2017-179256 can be used.

Characteristics of polyethylene components polymerized with metallocene catalysts (2-5-1)
In the resin composition containing the metallocene-based polyethylene, the polyethylene component polymerized by the metallocene-based catalyst has a melt flow rate (HLMFR) of 0.2 g/10 minutes or more and 5 g/10 minutes at a temperature of 190° C. and a load of 21.6 kg. It is preferably less than 0.3 g/10 minutes, preferably 0.3 g/10 minutes or more and 1.0 g/10 minutes or less, more preferably 0.4 g/10 minutes or more and 0.7 g/10 minutes or less. If this HLMFR is less than 0.2 g/10 min, the final resin composition will not be able to achieve HLMFR within the specified range, and there is a risk that fluidity and compatibility will decrease, resulting in molded products. There is a risk of damaging the appearance. On the other hand, if the HLMFR is 5 g/10 minutes or more, the final resin composition may not be able to achieve environmental stress cracking resistance, and the long-term durability of the molded article may be reduced. HLMFR can be measured in accordance with JIS K6922-2:1997. HLMFR can be adjusted mainly by the amount of hydrogen and polymerization temperature during polymerization of the polyethylene component.

In the resin composition containing the metallocene-based polyethylene, the polyethylene component polymerized by the metallocene-based catalyst has an HLMFR/MFR of preferably 30 or less, more preferably 25 or less, on the other hand, preferably 15 or more, and even more preferably is preferably 20 or more. HLMFR/MFR has a strong correlation with molecular weight distribution; when HLMFR/MFR takes a large value, the molecular weight distribution becomes wide, and when HLMFR/MFR takes a small value, the molecular weight distribution becomes narrow. When HLMFR/MFR exceeds 35, it is suggested that the influence of the long chain branched structure appears strongly, and when HLMFR/MFR is 35 or less, the compatibility of each component tends to be good, and the surface of the molded object is The properties tend to be smooth and the appearance is excellent, and it is easy to suppress deterioration of physical properties such as impact resistance of molded products. On the other hand, the lower limit is not particularly limited, but is preferably 10 or more because impact resistance and ESCR are required. A method for controlling HLMFR/MFR can be achieved by employing a catalyst that can control molecular weight distribution and appropriate polymerization conditions. Moreover, in the case of a bimodal or multimodal polymer, it can be controlled by adjusting the molecular weight of each component.

In the resin composition containing the metallocene polyethylene, the polyethylene component polymerized by the metallocene catalyst has a density of 0.915 g/cm ³ or more and 0.945 g/cm ³ or less, preferably 0.920 g/cm ³ or more, It is preferably 0.935 g/cm ³ or less, more preferably 0.924 g/cm ³ or more and 0.930 g/cm ³ or less. If the density is less than 0.915 g/ ^cm3 , the density range in the final resin composition may not be achieved, the rigidity may be insufficient, and the crystallization rate may decrease, resulting in a reduction in the molding cycle. . On the other hand, if the density exceeds 0.945 g/cm ³ , the environmental stress cracking resistance of the final resin composition may deteriorate. Density can be measured in accordance with JIS K6922-1, 2:1997. The density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component.

Characteristics of polyethylene components polymerized with chromium-based catalysts (2-5-2)
In the resin composition containing the metallocene polyethylene, the polyethylene component polymerized with a chromium catalyst has an HLMFR of 2 g/10 minutes or more and less than 20 g/10 minutes, preferably 3 g/10 minutes or more and 15 g/10 minutes or less, More preferably, it is 4 g/10 minutes or more and 12 g/10 minutes or less, particularly preferably 4 g/10 minutes or more and 10 g/10 minutes or less. If this HLMFR is less than 2 g/10 minutes, the molecular weight will increase and there is a risk that fluidity and moldability may not be ensured. In addition, in the final resin composition, there is a risk that the HLMFR may not be within the specified range and the fluidity may decrease, and the polyethylene component becomes the component with the highest viscosity in the low strain rate region, resulting in poor dispersion of the polyethylene component. There is a risk of damaging the appearance of the molded product. On the other hand, if this HLMFR is 20 g/10 minutes or more, there is a risk that impact resistance may not be ensured or the dispersion promotion effect of each component may be reduced due to the influence of an increase in the amount of low molecular weight components. HLMFR can be measured in the same manner as described above. HLMFR can be adjusted mainly by the amount of hydrogen and polymerization temperature during polymerization of the polyethylene component.

In the resin composition containing the metallocene-based polyethylene, the polyethylene component polymerized with a chromium-based catalyst has a density of more than 0.945 g/cm ³ and less than 0.965 g/cm ³ , preferably 0.950 g/cm ³ or more, It is preferably 0.963 g/cm ³ or less, more preferably 0.955 g/cm ³ or more and 0.961 g/cm ³ or less. If the density of the polyethylene component is less than 0.945 g/cm ³ , the density range in the final resin composition cannot be achieved, the rigidity is insufficient, and the crystallization rate decreases, resulting in a decrease in the molding cycle. There is a risk of Furthermore, the rigidity of the container is poor and it becomes easily deformed at high temperatures, and there is a risk that the container will deform due to the influence of the internal pressure of the container and cause leakage. On the other hand, if the density exceeds 0.965 g/cm ³ , the impact resistance of the final resin composition may decrease, and the impact resistance of the container may deteriorate. Density can be measured in the same manner as described above. The density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component.

In the resin composition containing the metallocene polyethylene, the polyethylene component polymerized with a chromium catalyst has a molecular weight distribution (Mw/Mn) measured by gel permeation chromatography (GPC) of 10 or more and 50 or less, preferably More preferably, it is 15 or more and 30 or less. The molecular weight distribution (Mw/Mn) measured by GPC is related to improvements in various physical properties and moldability of the polymer, and is also related to improvements in the appearance of molded products. When the molecular weight distribution (Mw/Mn) of the polyethylene component used in the present invention is within the above range, better blow molding processability can be exhibited. Moreover, it is preferable that the molecular weight distribution (Mw/Mn) is 10 or more because the compatibility of each component becomes better and the product appearance is excellent. On the other hand, when the molecular weight distribution (Mw/Mn) is 50 or less, it is easy to suppress deterioration of the pinch-off shape of the molded product, and it is easy to improve the impact strength as a hollow molded product. Setting the molecular weight distribution within a predetermined range can be achieved by employing a catalyst that can control the molecular weight distribution and appropriate polymerization conditions. Moreover, in the case of a bimodal or multimodal polymer, it can be controlled by adjusting the molecular weight of each component. The molecular weight and molecular weight distribution can be measured by gel permeation chromatography (GPC) under the conditions described in JP-A No. 2017-179256.

Characteristics of polyethylene component polymerized by Ziegler catalyst (2-5-3)
In the resin composition containing the metallocene polyethylene, the polyethylene component polymerized by a Ziegler catalyst has a melt flow rate (MFR) of 10 g/10 minutes or more and 200 g/10 minutes or less at a temperature of 190° C. and a load of 2.16 kg, preferably is preferably 11 g/10 minutes or more and 198 g/10 minutes or less, more preferably 11 g/10 minutes or more and 195 g/10 minutes or less. If this MFR is less than 10 g/10 minutes, the molecular weight will increase and there is a risk that fluidity and moldability may not be ensured. In addition, in the final resin composition, the HLMFR cannot be achieved within the specified range, and the fluidity decreases, making it more likely that fluid instability phenomena such as shark skin and melt fracture will occur. There is a risk of damaging the appearance. On the other hand, if this MFR exceeds 200 g/10 minutes, impact resistance may not be ensured due to the influence of an increase in the amount of low molecular weight components. In addition, the final resin composition may not be able to achieve impact resistance, and the drop impact resistance of the molded product may be reduced. MFR can be measured in the same manner as described above. MFR can be adjusted mainly by the amount of hydrogen and polymerization temperature during polymerization of the polyethylene component.

In the resin composition containing the metallocene polyethylene, the polyethylene component polymerized by a Ziegler catalyst has a density of 0.956 g/cm ³ or more and 0.980 g/cm ³ or less, preferably 0.956 g/cm ³ or more, 0. It is preferably 0.975 g/cm ³ or less, more preferably 0.956 g/cm ³ or more and 0.970 g/cm ³ or less. If the density is less than 0.956 g/ ^cm3 , the density range in the final resin composition may not be achieved, the rigidity may be insufficient, and the crystallization rate may decrease, resulting in a reduction in the molding cycle. . Furthermore, the rigidity of the container is poor and it becomes easily deformed at high temperatures, and there is a risk that the container will deform due to the influence of the internal pressure of the container and cause leakage. On the other hand, if the density exceeds 0.980 g/cm ³ , the impact resistance of the final resin composition may be reduced, and the container may have poor drop impact resistance. Density can be measured in the same manner as described above. The density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component.

The ethylene used in the polyethylene component used in the resin composition containing metallocene polyethylene of the present invention may be ethylene produced from crude oil derived from ordinary fossil raw materials, or ethylene derived from plants. It's okay. Examples of plant-derived ethylene and polyethylene include ethylene and polymers thereof described in Japanese Patent Publication No. 2010-511634. Plant-derived ethylene and its polymers are carbon neutral (no fossil raw materials are used and do not lead to an increase in atmospheric carbon dioxide), making it possible to provide environmentally friendly products.

3. Molding method for multilayer blow molding container The multilayer blow container of the present invention can be molded by a normal multilayer blow molding method. The extrusion temperature of the resin is 180 to 240°C, preferably 190 to 230°C, more preferably 200 to 220°C. The extrusion pressure of the resin is 50 MPa or less, preferably 40 MPa or less, more preferably 30 MPa or less. The temperature of the blow mold is 5 to 30°C, preferably 10 to 25°C, more preferably 15 to 20°C. The blowing pressure is 0.3 to 0.8 MPa, preferably 0.4 to 0.7 MPa, and more preferably 0.5 to 0.6 MPa.

4. Multilayer Blow Container The multilayer blow container of the present invention has at least an outer layer and an inner layer. An intermediate layer can be provided between the outer layer and the inner layer if necessary. The ratio of the thickness of the outer layer to the inner layer is such that the outer layer is 5 to 95% and the inner layer is 5 to 95%, preferably the outer layer is 10 to 90% and the inner layer is 10 to 90%, and more preferably the outer layer is 10 to 90%. The inner layer is 20-80% compared to 20-80%.
In addition, when providing an intermediate layer, the ratio of the thickness of the outer layer, intermediate layer, and inner layer is 5 to 20% for the outer layer, 60 to 90% for the intermediate layer, and 5 to 20% for the inner layer. 7 to 18%, the middle layer is 64 to 86%, the inner layer is 7 to 18%, and more preferably the outer layer is 10 to 15%, the middle layer is 70 to 80%, and the inner layer is 10 to 15%. %.
Further, if necessary, various types of printing or layers may be provided on the surface of the outer layer of the multilayer blow container of the present invention.

In the multilayer blow container having an outer layer and an inner layer, at least one of the outer layer and the inner layer contains 1 to 95% by mass, preferably 1 to 95% by mass, of a recycled polyolefin resin that satisfies the above characteristics (1-1) to (1-5). 2 to 94% by mass, more preferably 3 to 93% by mass, and 99 to 5% by mass, preferably 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies the above characteristics (2-1) to (2-4). In the case of a recycled resin composition containing 98 to 6% by mass, more preferably 97 to 7% by mass, the other layer may be the above recycled resin composition, the above recycled polyolefin resin, or the above recycled resin composition. It may also be a resin composition containing metallocene polyethylene.
Further, when at least one of the outer layer and the inner layer is made of the recycled polyolefin resin, the other layer may be made of the recycled resin composition, and the other layer may be a resin composition containing the metallocene polyethylene. Good too.
The recycled resin composition used in the present invention contains 1% by mass or more of recycled polyolefin resin, and by containing 1% by mass or more of recycled polyolefin resin, it is possible to reduce the amount of plastic used. If there is, it will contain at least 5% by mass of virgin material, and since virgin material usually has a high bottle ESCR of 100 hours or more, the bottle ESCR of the molded product should be about the same as when only virgin material is used. It is thought that the above can be achieved.

In the multilayer blow container having an intermediate layer, when at least one layer selected from the group consisting of the outer layer, the intermediate layer, and the inner layer is made of the above recycled resin composition, the remaining two layers are each made of the above recycled resin composition. It may be the recycled polyolefin resin described above, or it may be a resin composition containing the metallocene polyethylene described above.
Further, when at least one layer selected from the group consisting of the outer layer, the intermediate layer, and the inner layer is made of the recycled polyolefin resin, at least one of the remaining two layers is made of the recycled resin composition or As long as it is a resin composition containing metallocene polyethylene, the other layer may be the above-mentioned recycled resin composition, the above-mentioned recycled polyolefin resin, or the resin composition containing the above-mentioned metallocene polyethylene. Good too.

The mass ratio of recycled polyolefin resin to the entire mass of the multilayer blow container is not particularly limited, but from the perspective of reducing the amount of plastic used, it may be 1% by mass or more, or 2% by mass or more. The content may be 95% by mass or less, or may be 94% by mass or less from the viewpoint of achieving the same or higher bottle ESCR as when only virgin material is used. In addition, if the resin composition (virgin material) containing metallocene polyethylene is contained in an amount of at least 5% by mass or more based on the entire mass of the multilayer blow container, the virgin material usually has a bottle ESCR of 100 hours or more. Since it is expensive, it is thought that the bottle ESCR of the molded product can be made to be at least the same level as when only virgin material is used.

By making at least one layer in the multilayer blow container the recycled resin composition or the recycled polyolefin resin, the bottle ESCR of the molded product can be made to the same level or higher than when only virgin materials are used. . Therefore, according to the present invention, it is possible to reduce the amount of plastic used and help solve the problem of plastic waste (waste plastic).

Usually, if even a small amount of recycled material is used, durability, such as bottle ESCR, etc., will be significantly reduced. However, despite using the recycled polyolefin resin, the multilayer blow container of the present invention does not reduce the bottle ESCR and has a bottle ESCR of 100 hours or more, preferably 300 hours or more, and more preferably 500 hours. As described above, it is possible to provide a container that can be used for more preferably 600 hours or more.

The multilayer blow container of the present invention has good wall thickness uniformity, excellent surface uniformity, chemical resistance, bottle ESCR, etc., and is suitable for applications such as containers that require such characteristics, and in particular, It can be suitably used for cosmetic containers, containers for detergents, shampoos and conditioners, containers for foods such as edible oil, etc., which are required to have a good appearance.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

1. Measurement method The measurement method used in the examples is as follows.
(1) Density Measured in accordance with JIS K6922-1, 2:1997.
(2) Melt flow rate (MFR) at a temperature of 190°C and a load of 2.16kg
Measured in accordance with JIS K6922-2:1997.
(3) Melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg
Measured in accordance with JIS K6922-2:1997.
(4) Tensile impact strength A 1.5 mm compression molded sheet was prepared in accordance with JIS K6922-2, and a test piece was punched out using an S-shaped dumbbell in accordance with ASTM D1822. Measurements were performed under RH conditions.

(5) Carbonyl group content Absorption peaks at 1710 cm ⁻¹ and 1790 cm ⁻¹ were measured by infrared absorption spectrum analysis.

(6) Drop strength test of container A multilayer blow-molded cylindrical container (bottle) with an internal volume of 760 ml is filled with 600 ml of water, sealed with a container lid, and tested at a drop height of 5°C in the drop test atmosphere. The container was dropped from a height of 1.5 m onto a concrete floor with the circular bottom facing down, and then the container was dropped with the cylindrical side facing down, and the two types of dropping operations were then performed. This was repeated 5 times, and it was confirmed whether the container would break after being dropped a total of 10 times.

(7) Bottle ESCR
A nonionic surfactant (manufactured by Sigma-Aldrich: polyoxyethylene (9) nonylphenyl ether, Igepar CO-630) was added in an amount of 33% by mass in a cylindrical container (bottle) with an internal volume of 760 ml that was made by injection stretch blow molding. Fill the container with 190 ml of an aqueous solution diluted to It was measured. This measurement was performed on 10 identical containers, and the time when 5 or more of the 10 containers were damaged was defined as the bottle ESCR value.

(8) Usage ratio of recycled polyolefin resin The ratio of the mass of the recycled polyolefin resin used to the entire mass of the multilayer blow container was defined as the usage ratio of the recycled polyolefin resin.

(9) Comprehensive evaluation A comprehensive evaluation of the multilayer blow-molded container was conducted, and the container did not break in a drop strength test, the bottle ESCR was 100 hours or more, and the proportion of recycled polyolefin resin used was 1% by mass or more. Those in which no gel was generated were classified as "conforming," and the others were classified as "nonconforming."

2. Raw materials (1) Recycled polyolefin resin [Recycled material (A)]
Density is 0.954 g/cm ³ , MFR is 0.26 g/10 min, HLMFR is 36 g/10 min, HLMFR/MFR is 138, tensile impact strength is 130 kJ/m ² , bottle ESCR is less than 100 hours, additive material A recycled plastic "HDPE HA" manufactured by Mie Kasei Co., Ltd. having a content of 10% by mass or less and a carbonyl group content of 0% by mass was used.

(2) Recycled polyolefin resin [Recycled material (B)]
Density is 0.954 g/cm ³ , MFR is 0.26 g/10 min, HLMFR is 36 g/10 min, HLMFR/MFR is 138, tensile impact strength is 130 kJ/m ² , bottle ESCR is less than 100 hours, additive material Recycled plastic having a content of 10% by mass or less and a carbonyl group content of 5% by mass was used.

(3) Resin composition containing metallocene polyethylene [virgin material (A)]
According to the method described in Example 2 of JP-A No. 2017-179256, 25% by mass of a polyethylene component (HLMFR 0.6 g/10 min, density 0.920 g/cm ³ ) polymerized with a metallocene catalyst , 15% by mass of a polyethylene component polymerized by a chromium catalyst (HLMFR 5.0 g/10 min, density 0.956 g/cm ³ ), a polyethylene component polymerized by a Ziegler catalyst (MFR 19 g/10 min, HLMFR Resin composition containing 60% by mass (density 0.953 g/cm ³ , MFR 0.39 g/10 min, HLMFR 27 ^g /10 min, HLMFR /MFR of 69 and tensile impact strength of 310 kJ/m ² ) [Virgin material (A)] was prepared and used.

(4) Resin composition containing metallocene polyethylene [virgin material (B)]
According to the method for preparing the virgin material (A), 25% by mass of a polyethylene component (HLMFR 0.6 g/10 min, density 0.920 g/cm ³ ) polymerized with a metallocene catalyst was polymerized with a chromium catalyst. 15% by mass of polyethylene component (HLMFR 5.0 g/10 min, density 0.956 g/cm ³ ), polyethylene component polymerized by Ziegler catalyst (MFR 20 g/10 min, HLMFR 159 g/10 min) , a density of 0.956 g/cm ³ ) containing 60% by mass (density of 0.953 g/cm ³ , MFR of 0.42 g/10 min, HLMFR of 28 g/10 min, HLMFR/MFR of 67, A virgin material (B) having a tensile impact strength of 390 kJ/m ² was prepared and used.

(5) Polyethylene resin [virgin material (C)]
A chromium-catalyzed polyethylene resin [virgin material] with a density of 0.947 g/cm ³ , an MFR of 0.3 g/10 min, an HLMFR of 32 g/10 min, an HLMFR/MFR of 107, and a tensile impact strength of 160 kJ/m ² . (C)] was prepared and used.

3. Examples and comparative examples [Example 1]
A multilayer blow container (cylindrical bottle with a narrow mouth) shown in Table 1 was molded and evaluated under the conditions shown below. The container after blow molding has an outer diameter of the mouth of about 25 mm, an inner diameter of the mouth of about 20 mm, a height of the mouth of about 25 mm, an outer diameter of the body of about 73 mm, and a height of the body of about 160 mm. The height of the entire container was about 230 mm, the average wall thickness of the mouth was about 2.5 mm, the average wall thickness of the body was about 0.36 mm, and the internal volume was about 760 ml when fully filled. As shown in Table 1, the multilayer blow container of Example 1 has an outer layer made of a resin composition containing metallocene polyethylene (virgin material), an inner layer made of recycled polyolefin resin (recycled material), and a drop strength test. It did not break, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.
Multilayer blow molding machine: Bekum molding machine (modified product from Brenz)
Dice: 3 types, 3 layers multi-manifold die, outer layer 40mmφ, middle layer 30mmφ, inner layer 40mmφ
Molding temperature settings: outer layer 150-180°C/middle layer 150-180°C/inner layer 150-180°C, head/die 180°C.
Mold temperature: 20°C, molding cycle: 13 seconds, blow pressure: 0.5 MPa.

[Example 2]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 2 had an outer layer made of recycled polyolefin resin (recycled material) and an inner layer made of a resin composition containing metallocene polyethylene (virgin material), and was tested in the drop strength test. It did not break, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.

[Example 3]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 3 had an outer layer made of a recycled resin composition and an inner layer made of a resin composition containing metallocene polyethylene (virgin material), and did not break in the drop strength test. , the bottle ESCR was 100 hours or more, the proportion of recycled polyolefin resin used was 1% by mass or more, and no gel was generated, making it "suitable" as a recycling container.

[Example 4]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 4 has an inner and outer layer made of a resin composition containing metallocene polyethylene (virgin material), an intermediate layer made of recycled polyolefin resin (recycled material), and a drop strength of It did not break in the test, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.

[Example 5]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 5 had inner and outer layers made of a resin composition containing metallocene polyethylene (virgin material), an intermediate layer made of a recycled resin composition, and failed in the drop strength test. No, the bottle ESCR was 100 hours or more, the proportion of recycled polyolefin resin used was 1% by mass or more, and no gel was generated, making it "suitable" as a recycling container.

[Example 6]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 6 has an inner and outer layer made of a resin composition containing metallocene polyethylene (virgin material), an intermediate layer made of recycled polyolefin resin (recycled material), and a drop strength of It did not break in the test, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.

[Example 7]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 7 has the inner and outer layers made of recycled resin composition, does not break in the drop strength test, has a bottle ESCR of 100 hours or more, and uses recycled polyolefin resin. The proportion was 1% by mass or more, no gel was generated, and the container was "suitable" as a recycling container.

[Example 8]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 8 had an outer layer made of recycled polyolefin resin (recycled material) and an inner layer made of a resin composition containing metallocene polyethylene (virgin material), and was tested in the drop strength test. It did not break, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.

[Example 9]
The multilayer blow containers shown in Table 1 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 1. As shown in Table 1, the multilayer blow container of Example 9 has an inner and outer layer made of a resin composition containing metallocene polyethylene (virgin material), an intermediate layer made of recycled polyolefin resin (recycled material), and a drop strength of It did not break in the test, had a bottle ESCR of 100 hours or more, had a recycled polyolefin resin usage rate of 1% by mass or more, and did not generate gel, and was "suitable" as a recycling container.

[Comparative example 1]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, since the multilayer blow container of Comparative Example 1 does not include a layer of the resin composition (virgin material) containing metallocene polyethylene, it was destroyed in the drop strength test and the bottle ESCR was less than 100 hours. Therefore, it was found to be "unsuitable" as a recycling container.

[Comparative example 2]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, the multilayer blow container of Comparative Example 2 did not include a layer of the resin composition (virgin material) containing metallocene polyethylene, so it broke in the drop strength test and the bottle ESCR was less than 100 hours. Therefore, it was found to be "unsuitable" as a recycling container.

[Comparative example 3]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, the multilayer blow container of Comparative Example 3 does not include a layer of recycled polyolefin resin (recycled material), so the proportion of recycled polyolefin resin used is less than 1% by mass, and it is considered "unsuitable" as a recycling container. "Met.

[Comparative example 4]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, in the multilayer blow container of Comparative Example 4, the mass ratio of the resin composition (virgin material) containing metallocene polyethylene to the entire mass of the multilayer blow container was 3%, and 5% by mass. %, the bottle broke in the drop strength test and the bottle ESCR was less than 100 hours, making it "unsuitable" as a recycling container.

[Comparative example 5]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, the multilayer blow container of Comparative Example 5 broke in the drop strength test because the resin composition (virgin material) containing metallocene polyethylene had a tensile impact strength of 160 kJ/m ² . The ESCR was less than 100 hours and the container was not suitable for recycling.

[Comparative example 6]
The multilayer blow containers shown in Table 2 were molded and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. As shown in Table 2, in the multilayer blow container of Comparative Example 6, the content of carbonyl groups in the recycled polyolefin resin (recycled material) was 5% by mass, so gel was generated on the exterior and it was considered "unsuitable" as a recycling container. "Met.

According to the present invention, in the molding of a polyethylene-based multilayer blow container, in the multilayer blow container having at least an outer layer and an inner layer, the outer layer and/or the inner layer contain a recycled polyolefin resin having specific properties, so that the recycled material is multilayered. It is very useful industrially because it can be applied to blow products, reduce the amount of plastic used, and solve the problem of plastic waste (waste plastic).
In particular, the present invention makes it possible to use recycled materials efficiently, making it possible to construct a circular economic system from the perspective of saving resources and solving global environmental problems, which is extremely useful in industry. be.

Claims (6)

A multilayer blow container having at least an outer layer and an inner layer,
At least one of the outer layer and the inner layer is a resin composition containing metallocene polyethylene that satisfies the following characteristics (2-1) to (2-4),
The intermediate layer between the outer layer and the inner layer is a recycled polyolefin resin that satisfies the following characteristics (1-1) to (1-5),
A multilayer blow container containing 5% by mass or more of the resin composition containing the metallocene polyethylene based on the entire mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more. A multilayer blow container having at least an outer layer and an inner layer,
At least one of the outer layer and the inner layer is a resin composition containing metallocene polyethylene that satisfies the following characteristics (2-1) to (2-4),
The intermediate layer between the outer layer and the inner layer is a recycled polyolefin resin of 1 to 95% by mass that satisfies the following properties (1-1) to (1-5) and the following properties (2-1) to (2-4). ) is a recycled resin composition consisting of 99 to 5% by mass of a resin composition containing metallocene polyethylene,
A multilayer blow container containing 5% by mass or more of the resin composition containing the metallocene polyethylene based on the entire mass of the multilayer blow container.
Characteristics (1-1): The recycled polyolefin resin has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (1-2): The recycled polyolefin resin has a melt flow rate (MFR) of 0.1 to 10 g/10 minutes measured at a temperature of 190°C and a load of 2.16 kg; The melt flow rate (HLMFR) measured at 6Kg is 10-100g/10min.
Characteristic (1-3): The recycled polyolefin resin has a ratio of HLMFR to MFR (HLMFR/MFR) of 40 to 140.
Characteristic (1-4): The recycled polyolefin resin has environmental stress cracking resistance (bottle ESCR) of less than 100 hours.
Characteristic (1-5): The recycled polyolefin resin has a carbonyl group content of less than 5.0% by mass due to maleic anhydride-containing compounds.
Characteristic (2-1): The resin composition containing the metallocene polyethylene has a density of 0.940 to 0.970 g/cm ³ .
Characteristics (2-2): The resin composition containing the metallocene polyethylene has an MFR of 0.1 to 10 g/10 minutes and an HLMFR of 10 to 100 g/10 minutes.
Characteristic (2-3): The resin composition containing the metallocene polyethylene has an HLMFR/MFR of 40 to 140.
Characteristic (2-4): The resin composition containing the metallocene polyethylene has a tensile impact strength of 300 kJ/m ² or more. The resin composition containing metallocene polyethylene contains 10% by mass or more and 40% by mass or less of a polyethylene component polymerized by a metallocene catalyst, 5% by mass or more and 50% by mass or less of a polyethylene component polymerized by a chromium catalyst, and Ziegler. The multilayer blow container according to claim 1 or 2, containing 40% by mass or more and 85% by mass or less of a polyethylene component polymerized by a catalyst. The polyethylene component polymerized using a metallocene catalyst has a melt flow rate (HLMFR) of 0.2 g/10 minutes or more and less than 5 g/10 minutes at a temperature of 190° C. and a load of 21.6 kg, and a density of 0.915 g/cm. 4. The multilayer blow container according to claim ³ , which is polyethylene having a density of ³ or more and 0.945 g/cm3 or less. The polyethylene component polymerized using a chromium-based catalyst is a polyethylene having an HLMFR of 2 g/10 minutes or more and less than 20 g/10 minutes, and a density of more than 0.945 g/cm ³ and less than 0.965 g/cm ³ The multilayer blow container according to item 3 or 4 . The polyethylene component polymerized by the Ziegler catalyst has a melt flow rate (MFR) of 10 g/10 minutes or more and 200 g/10 minutes or less at a temperature of 190° C. and a load of 2.16 kg, and a density of 0.956 g/cm ³ or more. The multilayer blow container according to any one of claims 3 to 5, which is polyethylene having a content of 0.980 g/cm ³ or less.