JP7424027B2 - Recycled resin composition and blow container - Google Patents

Description

The present invention relates to a recycled resin composition for blow containers and blow containers.

In the field of 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 blow containers using synthetic resins.

For example, as shown in Patent Document 1, it is characterized by being made of an ethylene/α-olefin copolymer having 3 to 18 carbon atoms and having 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).

On the other hand, regarding polyethylene resin, for example, as shown in Patent Document 3, 10 to 40% by mass of a specific polyethylene component (A), 5 to 50% by mass of a specific polyethylene component (B), Contains 40 to 85% by mass of (C), property (1): MFR is 0.1 to 1 g/10 min, property (2): HLMFR is 10 to 50 g/10 min, property (3) : HLMFR/MFR is 50 to 140, Characteristic (4): Density is 0.940 to 0.965 g/ ^cm3 , Characteristic (5): Temperature 170°C, elongation strain rate 0.1 (unit: 1 In the logarithmic plot of the extensional viscosity η(t) (unit: Pa seconds) measured at 1/sec) and the elongation time t (unit: seconds), an inflection point in the extensional viscosity due to strain hardening is observed. A polyethylene resin composition that satisfies the characteristics of Nothing is suggested.

For example, 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 multistage polymerization is performed 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, etc. However, there is no suggestion regarding specific recycled materials and their application to fields of use.

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

Under these circumstances, it is desired to apply recycled materials to 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 blow products in the molding of polyethylene blow containers, and to reduce the amount of plastic waste (waste plastic). The aim is to solve the problem of
Particularly, it is an object of the present invention to provide a blow container that is sufficiently suitable as a blow container and has excellent bottle ESCR (durability) by modifying recycled materials.

As a result of extensive research in order to solve the above problems, the present inventors have succeeded in applying recycled materials to blow products by using recycled polyolefin resins with specific properties and polyethylene resins with specific properties in blow containers. , discovered that it is possible to reduce the amount of plastic used and solve the problem of plastic waste (waste plastic), and that it is sufficiently suitable for use as a blow container, and that by modifying recycled materials, it is possible to improve bottle ESCR (durability). ), and have completed the present invention.

That is, according to the first invention of the present invention, 1 to 95% by mass of recycled polyolefin resin satisfying the following properties (1-1) to (1-4) and the following properties (2-1) to (2) A recycled resin composition comprising 99 to 5% by mass of a resin composition containing metallocene polyethylene that satisfies -4) and satisfies the following properties (i) to (iv) is provided.
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 (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.
Characteristic (i): Density is 0.940 to 0.970 g/cm ³ .
Characteristic (ii): MFR is 0.1 to 10 g/10 minutes, and HLMFR is 10 to 100 g/10 minutes.
Characteristic (iii): HLMFR/MFR is 40 to 140.
Characteristic (iv): The content of carbonyl groups resulting from the maleic anhydride-containing compound is less than 2.5% by mass.

Further, according to the second aspect of the present invention, in the recycled resin composition, the resin composition containing the metallocene-based polyethylene contains 10% by mass or more and 40% by mass or less of a polyethylene component polymerized by a metallocene-based catalyst. The polyethylene component polymerized with a chromium catalyst may be contained in an amount of 5% by mass or more and 50% by mass or less, and the polyethylene component polymerized with a Ziegler catalyst may be contained in a range of 40% by mass or more and 85% by mass or less.

According to the third aspect of the present invention, in the recycled resin composition, the polyethylene component polymerized by the metallocene catalyst has a melt flow rate (HLMFR) of 0.0 at a temperature of 190° C. and a load of 21.6 kg. It may be polyethylene having a density of 2 g/10 minutes or more and less than 5 g/10 minutes and a density of 0.915 g/cm ³ or more and 0.945 g/cm ³ or less.

Further, according to the fourth aspect of the present invention, in the recycled resin composition, 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 It may be polyethylene having a weight of more than 0.945 g/cm ³ and less than 0.965 g/cm ³ .

According to the fifth aspect of the present invention, in the recycled resin composition, the polyethylene component polymerized by the Ziegler catalyst has a melt flow rate (MFR) of 10 g/10 at a temperature of 190°C and a load of 2.16 kg. 200 g/10 min or more and a density of 0.960 g/cm ³ or more and 0.980 g/cm ³ or less.

According to a sixth aspect of the present invention, there is provided a blow container containing the recycled resin composition.

According to the present invention, in polyethylene blow containers, recycled materials are applied to blow products, the amount of plastic used is reduced, the problem of plastic waste (waste plastic) is solved, and the blow containers can be used as blow containers. The suitability is sufficient, and by modifying the recycled material, it is possible to provide a blow container with excellent bottle ESCR (durability) and appearance.

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.
In addition, 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 further used in final products or parts 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 blow container of the present invention, it is desirable to minimize the decrease in physical properties and develop physical properties equivalent to or higher than virgin materials. It is important that the system is capable of
It is important that the recycled polyolefin resin of the present invention satisfies the following properties (1-1) to (1-4).

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, which will be 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) was determined by adding a nonionic surfactant (manufactured by Sigma-Aldrich: polyoxyethylene (9) nonylphenyl ether, Fill the container 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. 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 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 (1-6)
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 blow container tends to decrease.
In the present invention, the type and content of additives can be analyzed by a normal analytical method.

Characteristics of recycled polyolefin resin (1-7)
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.

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 305 kJ/m ² or more, and more preferably 310 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 is preferably a resin composition containing a polyethylene component polymerized with a metallocene catalyst, a polyethylene component polymerized with a chromium catalyst, and a polyethylene component polymerized with a Ziegler catalyst. Contains 10% by mass or more and 40% by mass or less of a polyethylene component, 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 and 85% by mass or less of a polyethylene component polymerized by a Ziegler catalyst. Preferably, a resin composition containing a polyethylene component polymerized with a metallocene catalyst is 15% by mass or more and 35% by mass or less, and a polyethylene component polymerized with a chromium catalyst is 10% by mass or more and 40% by mass or less , a composition containing 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-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 the Ziegler catalyst has a density of 0.960 g/cm ³ or more and 0.980 g/cm ³ or less, preferably 0.961 g/cm ³ or more, 0. It is preferably 0.975 g/cm ³ or less, more preferably 0.963 g/cm ³ or more and 0.970 g/cm ³ or less. If the density is less than 0.960 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. Recycled Resin Composition The recycled resin composition of the present invention is a recycled polyolefin resin that satisfies the above properties (1-1) to (1-4) in an amount of 1 to 95% by mass, preferably 2 to 94% by mass, and more preferably 3 to 93% by mass, and 99 to 5% by mass, preferably 98 to 6% by mass, more preferably 97% by mass, and a metallocene polyethylene that satisfies the above properties (2-1) to (2-4). ~7% by mass, and satisfies the following properties (i) to (iv).
Characteristic (i): Density is 0.940 to 0.970 g/cm ³ .
Characteristic (ii): MFR is 0.1 to 10 g/10 minutes, and HLMFR is 10 to 100 g/10 minutes.
Characteristic (iii): HLMFR/MFR is 40 to 140.
Characteristic (iv): The content of carbonyl groups resulting from the maleic anhydride-containing compound is less than 2.5% by mass.
The recycled resin composition of 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, and if it contains 95% by mass or less, , contains at least 5% by mass of virgin material, and since virgin materials usually have a high bottle ESCR of 100 hours or more, the bottle ESCR of the molded product should be the same or higher than when only virgin materials are used. It is thought that it can be done.

Characteristics of recycled resin composition (i)
In the present invention, the recycled resin composition 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 to 0.958 g /cm ³ is important. If the density of the recycled resin composition is less than 0.940 g/cm ³ , the rigidity may be insufficient and the crystallization rate may decrease, resulting in a decrease in the molding cycle. On the other hand, if the density exceeds 0.970 g/cm ³ , the bottle ESCR may decrease.
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 resin composition containing metallocene polyethylene, and the blending ratio of the components constituting the resin composition containing metallocene polyethylene; It can be adjusted by changing the blending ratio of the resin composition containing metallocene polyethylene and recycled polyolefin resin.

Characteristics of recycled resin composition (ii)
In the present invention, the recycled resin composition 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, 0.20 g/10 minutes or more, 0. 25 g/10 minutes or more, 0.30 g/10 minutes or more, and 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, 3 g/10 minutes or less and is 1 g/10 minutes or less.
If this MFR is less than 0.1 g/10 minutes, the fluidity of the recycled resin composition will decrease, which may increase the amount of resin heat generated due to the extruder motor load and shearing during molding, and may cause shark skin and melt problems. 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 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.
MFR can be measured in accordance with JIS K6922-2:1997.
The MFR of the recycled resin composition is determined by the hydrogen amount and temperature during polymerization of the components constituting the resin composition containing metallocene polyethylene, the blending ratio of the components constituting the resin composition containing metallocene polyethylene, and the metallocene It can be adjusted by changing the blending ratio of the resin composition containing polyethylene-based polyethylene and the recycled polyolefin resin.

Further, in the present invention, the recycled resin composition 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, 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 recycled resin composition will decrease, which may increase the extruder motor load and resin heat generation due to shearing during molding, and may cause problems such as shark skin and melt fracture. The appearance of the molded product may be damaged because the flow instability phenomenon is more likely to occur. 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.
HLMFR can be measured in accordance with JIS K6922-2:1997.
The HLMFR of the recycled resin composition is determined by the amount of hydrogen and temperature during polymerization of the components constituting the resin composition containing metallocene polyethylene, the blending ratio of the components constituting the resin composition containing metallocene polyethylene, and the metallocene It can be adjusted by changing the blending ratio of the resin composition containing polyethylene-based polyethylene and the recycled polyolefin resin.

Characteristics of recycled resin composition (iii)
In the present invention, the recycled resin composition 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, or 55 or more; The upper limit of MFR is preferably 135 or less, 130 or less, or 125 or less from the viewpoint of impact resistance of the molded article.
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 impact resistance of the molded product may decrease, and if the HLMFR/MFR exceeds 40, the melt tension of the molded product may decrease or the bottle ESCR of the molded product may decrease.
The method for controlling HLMFR/MFR can be carried out mainly in accordance with the method for controlling molecular weight distribution.

Characteristics of recycled resin composition (iv)
The recycled resin composition of the present invention preferably has a carbonyl group content of less than 2.5% 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 resin composition can be measured by infrared absorption spectroscopy, and preferably no absorption peaks are observed at 1710 cm ⁻¹ and 1790 cm ⁻¹ . The presence of carbonyl groups originating from maleic anhydride-containing compounds is undesirable because it may lead to the formation of gels and the like.
In order to ensure that recycled resin compositions do not contain carbonyl groups caused by maleic anhydride-containing compounds, it is important that recycled polyolefin resins, etc. undergo quality control and quality certification to ensure that they do not contain carbonyl groups. .

Characteristics of recycled resin composition (v)
In the present invention, the recycled resin composition preferably has a tensile impact strength of 135 KJ/m ² or more, more preferably 140 KJ/m ² or more. If the tensile impact strength is less than 135 KJ/m ² , the impact resistance as a blow container tends to decrease. The tensile impact strength can be increased by increasing the composition ratio of the resin composition containing metallocene polyethylene.
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 resin composition (vi)
In the present invention, the recycled resin composition preferably has a flexural modulus of 1275 MPa or more, more preferably 1280 MPa or more. When the flexural modulus is less than 1275 MPa, the rigidity as a blow container tends to decrease. The flexural modulus can be increased by decreasing the composition ratio of the resin composition containing metallocene polyethylene.
Flexural modulus can be measured in accordance with JIS K6922-2:1997.

The recycled resin composition of the present invention may contain various antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, antifogging agents, antiblocking agents, processing aids, coloring contents, and crosslinking agents as necessary. , blowing agents, inorganic or organic fillers, flame retardants, etc. can be added.

4. Method for Molding Blow Container The blow container of the present invention can be molded by a normal blow molding method. Examples of the blow molding method include an extrusion method, an accumulator method, a hot parison method, a cold parison method, and an injection method. For example, in the blow container of the present invention, a recycled resin composition is extruded from an extruder to produce a molten parison, the parison is set in a mold having a desired container shape of a blow molding machine, and then compressed gas It can be manufactured by blowing into the mold to expand it to the inner wall of the mold, and then cooling it. Examples of the continuous molding mechanism include shuttle type, rotary type, and satellite type, and examples of mold clamping methods include hydraulic type, electric type, and toggle type.
In the specific method for molding the blow container of the present invention, the extrusion temperature of the resin is 180 to 240°C, preferably 190 to 230°C, and 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.

5. Blow Container The blow container of the present invention is not particularly limited as long as it contains the recycled resin composition of the present invention, and may be a blow container made of the recycled resin composition of the present invention. Further, the blow container of the present invention may be a blow molded product made from the recycled resin composition by a blow molding method, or if necessary, the recycled resin composition may be multilayer blow molded by a multilayer blow molding machine. It may also be a quality item. The size of the blow molded product is not particularly limited, but is preferably about 10 ml to 2000 ml. Further, the shape of the container is not particularly limited, but various types of printing or layers may be provided on the surface of the outer layer of the blow container of the present invention, if necessary.
In particular, the blow container of the present invention does not have a simple cylindrical shape, such as a container with a handle, a container with a bellows-like structure, a container with a constriction, a container with a combination of different diameter parts, etc. It may be a hollow container having a shape having portions where the blowing ratio of the parison is greatly different.

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 blow container of the present invention does not reduce the bottle ESCR and has a bottle ESCR of 100 hours or more, preferably 250 hours or more, preferably 300 hours or more. It is possible to provide a container that can be used more preferably for 500 hours or more, and even more preferably for 600 hours or more.

The 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. 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 good quality.
Furthermore, examples of uses of the blow container of the present invention include medical containers, food containers, cosmetic containers, etc. Food containers include various beverage containers, concentrated beverage containers, seasoning containers, prepared food containers, Examples include dressing containers, mayonnaise/ketchup containers, various retort food containers, baby bottles, etc. Cosmetic containers include hair styling products, hair products, perfumes, hair dyes, eye shadows, nail polish, lotions, creams, milky lotions, and makeup. Examples include containers for water, perm solution, etc.

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 Tensile impact strength was measured by creating a 1.5 mm compression molded sheet in accordance with JIS K6922-2, and creating a test piece punched with an S-shaped dumbbell in accordance with ASTM D1822. The measurement was performed under the conditions of 23° C. and 50% RH.

(5) Flexural modulus Measured in accordance with JIS K6922-2:1997.

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

(7) Container drop strength test A blow-molded cylindrical container (bottle) with an internal volume of 760 ml was filled with 600 ml of water, sealed with a container lid, and the drop height was measured at a temperature of 5°C in the drop test atmosphere. The container was dropped from 1.5 m to a concrete floor with the circular bottom facing down, then the container was dropped with the cylindrical side facing down, and the two types of dropping operations were repeated 5 times. This test was repeated several times, and it was confirmed whether or not the container would break after a total of 10 drops.

(8) Bottle ESCR
A nonionic surfactant (manufactured by Sigma-Aldrich: polyoxyethylene (9) nonylphenyl ether, Igepar CO-630) was diluted to 33% by mass in a blow-molded cylindrical container (bottle) with an internal volume of 760 ml. The container was filled with 190 ml of the aqueous solution, and the container was sealed with a molten parison made of the same material as the container, and the sealed container was stored in a constant temperature bath at a temperature of 65°C, and the time until the container broke 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.

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

(10) Comprehensive evaluation A comprehensive evaluation of the blow-molded container was conducted to ensure that it did not break in the drop strength test, the bottle ESCR was 100 hours or more, the proportion of recycled polyolefin resin was 1% by mass or more, and Those in which no occurrence occurred were classified as "conforming," and the others were classified as "nonconforming."

2. Raw materials (1) Recycled polyolefin resin (A-1)
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 (A-2)
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 (B) containing metallocene polyethylene
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 ) [Resin composition (B) containing metallocene polyethylene] was prepared and used.

3. Examples and comparative examples [Example 1]
Blow containers (cylindrical bottles with a narrow mouth) shown in Table 1 were 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 blow container of Example 1 did not break in the drop strength test, had a bottle ESCR of 100 hours or more, used a recycled polyolefin resin of 1% by mass or more, and had a gel content. No waste was generated, and the container was ``suitable'' for recycling.
Blow molding machine: Single layer molding machine manufactured by Blenz (type: BEX70/BLS-5E/BK50).
Molding temperature settings: Extruder 150-180°C, head die 180°C.
Mold temperature: 20°C, molding cycle: 13 seconds, blow pressure: 0.5 MPa.

[Example 2]
The 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 blow container of Example 2 did not break in the drop strength test, had a bottle ESCR of 100 hours or more, used a recycled polyolefin resin of 1% by mass or more, and had a gel content. No waste was generated, and the container was ``suitable'' for recycling.

[Example 3]
The 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 blow container of Example 3 did not break in the drop strength test, had a bottle ESCR of 100 hours or more, used a recycled polyolefin resin of 1% by mass or more, and had a gel content. No waste was generated, and the container was ``suitable'' for recycling.

[Example 4]
The 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 blow container of Example 4 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 the gel was No waste was generated, and the container was ``suitable'' for recycling.

[Example 5]
The 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 blow container of Example 5 did not break in the drop strength test, had a bottle ESCR of 100 hours or more, used a recycled polyolefin resin of 1% by mass or more, and had a gel content. No waste was generated, and the container was ``suitable'' for recycling.

[Example 6]
The 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 blow container of Example 6 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 the gel was No waste was generated, and the container was ``suitable'' for recycling.

[Comparative example 1]
The 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 blow container of Comparative Example 1 used 100% by mass of recycled polyolefin resin, broke in the drop strength test, had a bottle ESCR of less than 100 hours, and was considered "unsuitable" as a recycling container. "Met.

[Comparative example 2]
The 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 blow container of Comparative Example 2 did not break in the 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; Since the content of carbonyl groups in the resin composition was 2.5% by mass, gel was generated, so the container was "unsuitable" as a recycling container.

[Comparative example 3]
The 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 blow container of Comparative Example 3 did not break in the drop strength test, but because the proportion of recycled polyolefin resin (recycled material) used was 97% by mass, the bottle ESCR was less than 100 hours. Therefore, the container was not suitable for recycling.

[Comparative example 4]
The 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 blow container of Comparative Example 4 did not break in the drop strength test and had a bottle ESCR of 100 hours or more, but the proportion of recycled polyolefin resin used was less than 1% by mass, and the bottle was recycled. It was found to be "unsuitable" as a container.

According to the present invention, by using recycled polyolefin resin with specific properties and polyethylene resin with specific properties in a polyethylene blow container, recycled materials can be applied to blow products, reducing the amount of plastic used, and reducing the amount of plastic used. It solves the problem of garbage (waste plastic), is sufficiently suitable as a blow container, and can provide blow containers with excellent bottle ESCR (durability) by modifying recycled materials. The above is very useful.
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 method for producing a recycled resin composition by mixing a resin composition containing a recycled polyolefin resin and a metallocene polyethylene, the method comprising:
The recycled polyolefin resin satisfies the following properties (1-1) to (1-4) in an amount of 1 to 95% by mass, and the recycled resin composition satisfies the following properties (2-1) to (2-4). The resin composition contains 99 to 5% by mass of the metallocene polyethylene, satisfies the following characteristics (i) to ( iii ) , and contains carbonyl groups resulting from the maleic anhydride-containing compound contained in the recycled polyolefin resin . A method for producing a recycled resin composition , which is controlled so as to satisfy the following characteristic (iv) depending on the amount .
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 (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.
Characteristic (i): Density is 0.940 to 0.970 g/cm ³ .
Characteristic (ii): MFR is 0.1 to 10 g/10 minutes, and HLMFR is 10 to 100 g/10 minutes.
Characteristic (iii): HLMFR/MFR is 40 to 140.
Characteristic (iv): The content of carbonyl groups resulting from the maleic anhydride-containing compound is less than 2.5% by mass. The resin composition containing the 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 The method for producing a recycled resin composition according to claim 1, which contains 40% by mass or more and 85% by mass or less of a polyethylene component polymerized by a Ziegler catalyst. The polyethylene component polymerized by the 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/10 minutes. ^3. The method for producing a recycled resin composition according to claim 2, which is polyethylene having a density of 0.945 g/cm 3 or more and 0.945 g/cm ³ or less. The polyethylene component polymerized by the chromium-based catalyst is 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 . A method for producing a recycled resin composition according to claim 2 or 3. 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 0.960 g/cm ³ or more. , 0.980 g/cm ³ or less, the method for producing a recycled resin composition according to any one of claims 2 to 4. A blow container containing a recycled resin composition obtained by the manufacturing method according to any one of claims 1 to 5.