JP7205350B2 - Polyethylene resin composition, molding and container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyethylene resin composition, and a molded article and a container containing the polyethylene resin composition.

In blow molding, injection molding, inflation molding, and extrusion molding of polyethylene, materials with good moldability and physical properties are generally required. Especially for hollow bottles, which are generally used as containers for cosmetics, containers for detergents, shampoos and conditioners, or containers for food such as edible oil, polyethylene resin with excellent moldability, physical properties and chemical properties is used. is widely used.
In recent years, there has been a marked trend toward shorter molding cycles to improve productivity, and thinner and lighter containers to reduce costs and reduce environmental impact. There is a demand for more highly balanced strength.

However, as container weight reduction and design diversification are progressing more and more, in order to ensure the rigidity of the container while keeping the container thin, it becomes necessary to increase the density of polyethylene, that is, to suppress the amount of comonomer copolymerization. However, this conflicts with the maintenance of environmental stress crack resistance, so there is still a demand for a material that has a good balance of rigidity and environmental stress crack resistance and can be used for thinning.

Accordingly, multi-component polyethylene resin compositions are disclosed that include metallocene-based catalyzed polyethylenes to provide an improved balance of stiffness and environmental stress crack resistance.
For example, Patent Document 1 discloses an ethylene-based resin that simultaneously satisfies the following requirements [a] to [c].
[a] Environmental stress fracture resistance (ESCR) T (hr) at 50° C. measured in accordance with ASTM-D-1693 is 500 hours or more when the flexural modulus is 1000 MPa to 1500 MPa, and the flexural modulus is 1500 MPa. 100 hours or more for up to 2000 MPa.
[b] The melt tension at 190°C is 50 (mN) or more.
[c] The melt drawing breaking speed is 90 (m/min) or less.
The ethylene-based resin disclosed in Patent Document 1 uses an ethylene-based resin that is multi-stage polymerized using a metallocene-based catalyst, and has excellent rigidity and ESCR, as well as parison stability and cutting properties. A bottle formed from the resin is said to have an excellent appearance.
However, the ethylene-based resin described in Patent Document 1 has low fluidity and poor high-speed moldability. In addition, there is no description of impact resistance, and since impact resistance generally decreases when rigidity is high, impact resistance may be insufficient.

Further, Patent Document 2 discloses a polyethylene resin composition characterized by satisfying the following requirements (a) to (d).
(a) Code D MFR of 3.5 to 10.0 g/10 min measured under conditions of a temperature of 190° C. and a load of 2.16 kg according to JIS K7210;
(b) a density of 963 to 967 kg/m ³ as measured according to JIS K7112;
(c) the isothermal crystallization time of the peak at 124°C obtained by DSC crystallization time measurement is 10 minutes or less; and
(d) an f50 fracture time of 20 hours or longer as determined by the Environmental Stress Cracking Test (ESCR);
The polyethylene resin composition disclosed in Patent Document 2 uses an ethylene-based resin obtained by multi-stage polymerization using a metallocene-based catalyst, and has environmental stress crack resistance (stress crack resistance) that can withstand the internal pressure of a beverage bottle. It is said to be a polyethylene resin composition for bottle caps that has excellent rigidity and excellent high-speed moldability without lowering the opening torque, and also has excellent required performance such as opening torque.
However, although the polyethylene resin composition described in Patent Document 2 has high fluidity, its impact resistance is insufficient. Since the polyethylene resin composition of Patent Document 2 is substantially for injection molding of bottle caps, the required impact resistance is low, and the impact resistance for blow-molded containers and the like is insufficient.

Further, in Patent Document 3, the content of structural units derived from α-olefins having 3 to 10 carbon atoms is 0 to 1.0 mol%, and the following requirements (1) to (6) are satisfied. A coalescence is disclosed.
(1) A melt flow rate of 5 to 15 g/10 min at 190° C. under a load of 2.16 kg.
(2) The ratio of the melt flow rate at 190°C with a load of 21.6 kg to the melt flow rate with a load of 2.16 kg at 190°C is 40 or more.
(3) Density is 940-965 kg/m ³ .
(4) The ratio (Mw/Mn) of the weight average molecular weight Mw to the number average molecular weight Mn measured by gel permeation chromatography is 4.5 to 7.0.
(5) The intrinsic viscosity [η] measured in decalin at 135°C is less than 1.3 dl/g.
(6) Spiral flow length at 200° C. and thickness of 1 mm is 20 cm or more.
The ethylene-based polymer disclosed in Patent Document 3 is an ethylene-based polymer that is multi-stage polymerized using a metallocene-based catalyst, has good fluidity, and exhibits high impact resistance and environmental stress fracture resistance. It is said to be suitable for injection molding.
However, although the ethylene-based polymer described in Patent Document 3 has high fluidity, it has insufficient impact resistance. Since the ethylene-based polymer of Patent Document 3 is substantially for injection molding, the required impact resistance is low, and the impact resistance for blow-molded containers and the like is insufficient.

For the purpose of further enhancing the environmental stress cracking resistance of polyethylene using metallocene catalysts, increasing the molecular weight is extremely effective. In a polyethylene resin composition, it is important to design a resin that achieves both compatibility and resistance to environmental stress cracking.
In view of these circumstances, it is possible to achieve high-speed molding and high cycle while maintaining the hollow moldability, high rigidity, impact resistance, etc. required of conventional polyethylene resin compositions for containers. There is a need for polyethylene materials that are particularly aesthetically pleasing.

Therefore, the present applicant has found a polyethylene material with a high crystallization rate that can achieve a further high-speed molding and high cycle while having hollow moldability, high rigidity, impact resistance, etc., and filed an application earlier. (Patent Documents 4 to 9). In Patent Documents 4 to 6, 60 to 90% by mass of specific polyethylene is polymerized using a metallocene catalyst containing Ti, Zr or Hf, HLMFR and density are each specific values, and long chain branching A polyethylene resin composition for containers is disclosed which contains 10 to 40% by mass of a specific ethylene polymer having a structure and which satisfies specific properties.
Patent Documents 7 to 9 disclose polyethylene resin compositions containing specific amounts of three specific types of polyethylene components and satisfying properties (1) to (5).
Characteristic (1): MFR is 0.1 to 1 g/10 minutes.
Characteristic (2): HLMFR is 10 to 50 g/10 minutes.
Property (3): HLMFR/MFR is 50-140.
Characteristic (4): Density is 0.940 to 0.965 g/cm ³ .
Characteristic (5): Both elongational viscosity η (t) (unit: Pa·sec) and elongation time t (unit: sec) measured at a temperature of 170°C and an elongation strain rate of 0.1 (unit: 1/sec) In the logarithmic plot, an inflection point of extensional viscosity due to strain hardening is observed.
Further, in Patent Document 10, the specific polyethylene component (A) is 5% by mass or more and 40% by mass or less, and the specific polyethylene component (B) is 60% by mass or more and 95% by mass or less, and the following characteristics (1) A polyethylene resin composition satisfying (4) is disclosed.
Characteristic (1): MFR is 0.1 g/10 minutes or more and 1 g/10 minutes or less.
Characteristic (2): HLMFR is 10 g/10 minutes or more and 50 g/10 minutes or less.
Characteristic (3): The melt flow rate ratio (HLMFR/MFR), which is the ratio of HLMFR to MFR, is 40 or more and 140 or less.
Characteristic (4): Density is 0.950 g/cm ³ or more and 0.970 g/cm ³ or less.
However, although the polyethylene resin compositions described in Patent Documents 4 to 10 all have high impact resistance, the molded products have low fluidity and the resin temperature tends to increase during the extrusion process, shortening the entire molding cycle. There were still problems with the realization of

In addition, the present applicant has disclosed in Patent Document 11 that the density (D) is 0.900 to 0.975 g/cm ³ , the melt flow rate (MFR (D), according to JIS K7210, the temperature is 190 ° C., component (A) having a specific density and HLMFR, respectively, with respect to 10 to 90% by weight of the ethylene polymer (D), which is 0.05 to 1000 g/10 min (measured at a load of 2.16 kg) and an ethylene polymer composition for thin-walled containers containing 90 to 10% by weight of an ethylene polymer (C) obtained by multi-stage polymerization of the component (B). The disclosed ethylene-based polymer disclosed in Patent Document 11 is excellent in moldability, durability and impact strength, and is less likely to cause unevenness derived from high molecular weight gel, and can produce molded articles with excellent appearance. is said to be possible.
However, the required performance required for products is increasing day by day, and higher impact resistance than the ethylene polymer of Patent Document 11 is required, and further performance improvement is required to address the problems of the above-described conventional technology. .

International Publication 2007/094376 JP 2012-229355 A JP 2017-128692 A JP 2013-204015 A JP 2014-208749 A JP 2014-208750 A JP 2017-179256 A JP 2017-179294 A JP 2018-131571 A JP 2017-186515 A JP 2016-55871 A

In various molding methods such as blow molding, injection molding, inflation molding, and extrusion molding, one of the effective means of shortening the molding cycle is the cooling and solidification process after molding the molten resin in the mold. shortening of the time required for Therefore, it is desirable to lower the molding temperature in the step of melting and kneading the resin before molding the molten resin in the mold as much as possible.
Therefore, a polyethylene resin composition that has a good balance of the high rigidity, environmental stress crack resistance, impact resistance, etc. required for a polyethylene resin composition for containers and that suppresses the heat generation of the resin during the extrusion process of extruding the molten resin is needed. It has been demanded.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the object of the present invention is to provide a polyethylene resin composition which has an excellent balance of rigidity, environmental stress crack resistance, and impact resistance, and which suppresses heat generation of the resin during the extrusion process. and to provide a molded article and a container using the same.

As a result of intensive research conducted by the present inventors in order to solve the above problems, the molded product has an excellent balance of rigidity, environmental stress crack resistance, and impact resistance, and the heat generation of the resin is suppressed during the extrusion process. The inventors have found that a polyethylene resin composition and a molded article made of the same can be obtained, and have completed the present invention.

The polyethylene resin composition of the present invention essentially contains one or more ethylene polymers selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. Contains as a component and satisfies the following characteristics (1) to (5).
Characteristic (1): The melt flow rate (MFR) measured at a temperature of 190° C. and a load of 2.16 kg is 0.5 g/10 minutes or more and 5 g/10 minutes or less.
Characteristic (2): The melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is more than 50 g/10 minutes and not more than 100 g/10 minutes.
Characteristic (3): The melt flow rate ratio (HLMFR/MFR), which is the ratio of HLMFR to MFR, is 40 or more and 100 or less.
Characteristic (4): Density is 0.950 g/cm ³ or more and 0.970 g/cm ³ or less.
Characteristic (5): The rupture time (FNCT) (unit: hours) and the density (d) (unit: g/cm ³ ) in a full-circumference notch type creep test performed in accordance with ISO DIS 16770 are expressed by the following formula (1). satisfies the relationship shown by
FNCT≧5.5×10 ⁻⁵ ×d ⁻³²⁴ Expression (1)

The polyethylene resin composition of the present invention preferably satisfies the following property (6) from the viewpoint of having an excellent balance between rigidity (density) and impact resistance.
Property (6): Tensile impact strength (TIS) at 23° C. (unit: kJ/m ² ) and density (d) (unit: g/cm ³ ) satisfy the relationship represented by the following formula (2).
TIS≧−22000×d+21184 Expression (2)

The polyethylene resin composition of the present invention preferably satisfies the following property (7) from the viewpoint of excellent blow moldability.
Characteristic (7): Melt tension (MT) (unit: mN) measured at 190° C. and HLMFR (unit: g/10 min) satisfy the relationship represented by the following formula (3).
MT≧334.85×HLMFR− ^0.635 Expression (3)

The polyethylene resin composition of the present invention easily satisfies the above properties (1) to (5), and has high compatibility of the resin components, excellent appearance of the molded product, and excellent moldability. It is preferable to contain 10% by mass or more and 30% by mass or less of (A) and 70% by mass or more and 90% by mass or less of polyethylene component (B) described below.
Polyethylene component (A); property (a1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (a2): density is 0.915 g/cm ³ or more and 0.940 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (B); property (b1): MFR is 0.1 g/10 min or more and 10 g/10 min or less; property (b2): density is 0.950 g/cm ³ or more and 0.980 g/cm ³ or less Characteristic (b3): HLMFR is 1 g / 10 minutes or more and 1000 g / 10 minutes or less, Characteristic (b4): 10% by mass or more and 50% by mass or less of the following polyethylene component (C), the following polyethylene component (D ) in an amount of 50% by mass or more and 90% by mass or less.
Polyethylene component (C); property (c1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (c2): density is 0.900 g/cm ³ or more and 0.950 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (D); property (d1): MFR is 10 g/10 min or more and 400 g/10 min or less; property (d2): density is 0.900 g/cm ³ or more and 0.980 g/cm ³ or less Ethylene polymer.

The polyethylene resin composition of the present invention has a molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by a gel permeation chromatography (GPC) method of 5. ∼25 is preferable from the viewpoint of compatibility and the appearance of the molded product.

The polyethylene resin composition of the present invention has a screw diameter (Ds) of 70 mm, a ratio (Ls/Ds) of the effective screw length (Ls) to the screw diameter (Ds) of 24, and a compression ratio of 3.0. With a die with an outer diameter of 14 mm and an inner diameter of 10.5 mm attached to the extruder installed inside, the set temperature of the cylinder and die is 185 ° C. and the screw rotation speed is adjusted to an extrusion rate of 70 kg / hour. It is preferable that the resin temperature is 235° C. or less when the resin temperature is measured with a contact resin thermometer, from the viewpoint of shortening the entire molding cycle by shortening the cooling time.

The molded article of the present invention is characterized by containing the polyethylene resin composition of the present invention.

Further, the container of the present invention is characterized by having a layer containing the polyethylene resin composition of the present invention.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a polyethylene resin composition which has an excellent balance of rigidity, environmental stress crack resistance, and impact resistance of a molded article, and which suppresses heat generation of the resin during an extrusion process, and a molded article and container using the same. There is an effect that it is possible to provide

FIG. 1 is a plot diagram of typical elongational viscosity, and is a diagram for explaining a case where an inflection point of elongational viscosity is observed. FIG. 2 is a plot diagram of a typical elongational viscosity, and is a diagram for explaining a case where no inflection point of the elongational viscosity is observed. FIG. 3 is a graph showing the relationship between the density (d) of the polyethylene resin compositions of Examples and Comparative Examples and the rupture time (FNCT) of the full circumference notch type creep test. FIG. 4 is a diagram showing the relationship between the HLMFR of the polyethylene resin compositions of Examples and Comparative Examples and the rupture time (FNCT) in a full-circumference notch creep test. FIG. 5 is a graph showing the relationship between density (d) and tensile impact strength (TIS) of polyethylene resin compositions of Examples and Comparative Examples. FIG. 6 is a diagram showing the relationship between HLMFR and tensile impact strength (TIS) of polyethylene resin compositions of Examples and Comparative Examples. FIG. 7 is a diagram showing the relationship between HLMFR and melt tension (MT) of polyethylene resin compositions of Examples and Comparative Examples.

I. Polyethylene resin composition The polyethylene resin composition of the present invention comprises one or more ethylene-based polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. It contains a polymer as an essential component and is characterized by satisfying the following properties (1) to (5).
Characteristic (1): The melt flow rate (MFR) measured at a temperature of 190° C. and a load of 2.16 kg is 0.5 g/10 minutes or more and 5 g/10 minutes or less.
Characteristic (2): The melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is more than 50 g/10 minutes and not more than 100 g/10 minutes.
Characteristic (3): The melt flow rate ratio (HLMFR/MFR), which is the ratio of HLMFR to MFR, is 40 or more and 100 or less.
Characteristic (4): Density is 0.950 g/cm ³ or more and 0.970 g/cm ³ or less.
Characteristic (5): The rupture time (FNCT) (unit: hours) and the density (d) (unit: g/cm ³ ) in a full-circumference notch type creep test performed in accordance with ISO DIS 16770 are expressed by the following formula (1). satisfies the relationship shown by
FNCT≧5.5×10 ⁻⁵ ×d ⁻³²⁴ Expression (1)

By satisfying the properties (1) to (5), the polyethylene resin composition of the present invention has an excellent balance between the rigidity of the molded product, environmental stress crack resistance, and impact resistance, and heat generation of the resin during the extrusion process. is suppressed.
Since the polyethylene resin composition of the present invention suppresses the heat generation of the resin during the extrusion process, the molding temperature can be lowered, so the time required for the cooling and solidification process after molding the molten resin in the mold can be shortened, and the shortening of the entire molding cycle can be achieved.
Therefore, the polyethylene resin composition of the present invention has the effect that it is possible to obtain a molded article having excellent physical properties while shortening the entire molding cycle.
Hereinafter, the present invention will be described in detail for each item.
In the present invention, polyethylene is a general term for ethylene homopolymers and copolymers of ethylene and olefins described later, and can also be called ethylene-based polymers.
Further, in this specification, the term "to" indicating a numerical range is used to include the numerical values before and after it as lower and upper limits.

1. Properties of Polyethylene Resin Composition It is important that the polyethylene resin composition of the present invention satisfy the following properties (1) to (5).
Characteristics (1)
From the viewpoint of fluidity and long-term durability, the polyethylene resin composition of the present invention has a melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg of 0.5 g / 10 minutes or more and 5 g / 10 minutes. Choose the one that is: The MFR is preferably 0.5 g/10 min or more and 2 g/10 min or less, more preferably 0.6 g/10 min or more and 1 g/10 min or less.
If the MFR is less than 0.5 g/10 minutes, the flowability will decrease, which may increase the extruder motor load during molding and the amount of heat generated by the resin due to shearing, and flow problems such as shark skin and melt fracture. Since the stability phenomenon is likely to occur, the appearance of the molded product may be impaired.
On the other hand, if the MFR exceeds 5 g/10 minutes, impact resistance and environmental stress crack resistance cannot be achieved, and there is a risk that the drop impact resistance and long-term durability of the molded product will decrease.
In the present invention, MFR can be measured according to JIS K6922-2:1997.
The MFR of the polyethylene resin composition can be adjusted by adjusting the hydrogen content and temperature of each ethylene-based polymer constituting the polyethylene resin composition and the compounding amount of each component.

Characteristic (2)
In terms of fluidity and long-term durability, the polyethylene resin composition of the present invention has a melt flow rate (HLMFR) at a temperature of 190° C. and a load of 21.6 kg exceeding 50 g/10 minutes and not more than 100 g/10 minutes. choose things. The HLMFR is preferably in the range of 51 g/10 min or more and 70 g/10 min or less, more preferably 51 g/10 min or more and 65 g/10 min or less.
If the HLMFR is 50 g/10 minutes or less, the fluidity is lowered, which may increase the resin heat generation due to extruder motor load and shear during molding.
On the other hand, if the HLMFR exceeds 100 g/10 minutes, impact resistance and environmental stress cracking resistance cannot be achieved, and the drop impact resistance and long-term durability of the molded product may deteriorate.
In the present invention, HLMFR can be measured according to JIS K6922-2:1997.
The HLMFR of the polyethylene resin composition can be adjusted by adjusting the hydrogen content and temperature during polymerization of each ethylene-based polymer constituting the polyethylene resin composition, and the compounding amount of each component.

Characteristic (3)
The polyethylene resin composition of the present invention should have a melt flow rate ratio (HLMFR/MFR) of 40 or more and 100 or less, which is the ratio of HLMFR to MFR, from the viewpoint of impact resistance and environmental stress crack resistance. The melt flow rate ratio is preferably in the range of 50 to 100, more preferably 60 to 100.
The HLMFR/MFR has a strong correlation with the molecular weight distribution. When the HLMFR/MFR takes a large value, the molecular weight distribution becomes broad, and when the HLMFR/MFR takes a small value, the molecular weight distribution becomes narrow. When the HLMFR/MFR exceeds 100, the compatibility of each component may deteriorate and the impact resistance may decrease. There is a risk that the environmental stress crack resistance will be reduced.
HLMFR/MFR can be controlled mainly according to the molecular weight distribution control method.

Characteristic (4)
For the polyethylene resin composition of the present invention, one having a density of 0.950 g/cm ³ or more and 0.970 g/cm ³ or less is selected from the viewpoint of impact resistance and environmental stress crack resistance. The density is preferably 0.950 g/cm ³ or more and 0.965 g/cm ³ or less, more preferably 0.953 g/cm ³ or more and 0.960 g/cm ³ or less.
If the density is less than 0.950 g/cm ³ , the rigidity may be insufficient. On the other hand, if the density exceeds 0.970 g/cm ³ , the environmental stress crack resistance and impact resistance may decrease.
Density in the present invention can be measured according to JIS K6922-1,2:1997.
The density can be adjusted by adjusting the amount of α-olefin at the time of polymerization of each ethylene-based polymer constituting the polyethylene resin composition, and by adjusting the blending amount of each component.

Characteristic (5)
The polyethylene resin composition of the present invention has the following rupture time (FNCT) (unit: hours) and density (d) (unit: g/cm ³ ) in a full circumference notch creep test performed in accordance with ISO DIS 16770. It satisfies the relationship represented by the formula (1).
FNCT≧5.5×10 ⁻⁵ ×d ⁻³²⁴ Expression (1)
In general, polyethylene resin compositions with high density (rigidity) tend to have low durability, so it is desirable that the polyethylene resin composition has both density (rigidity) and long-term durability such as resistance to environmental stress cracking. be Formula (1) indicates that the polyethylene resin composition of the present invention is superior in durability to density (large FNCT) compared to conventional polyethylene resins. That is, in order to distinguish the polyethylene resin composition of the present invention from the conventional one, the rupture time (FNCT) of the full circumference notch type creep test is considered as a function having a negative correlation with the increase in density (d). , set the parameters of the function, and show that the FNCT of the polyethylene resin composition of the present invention is larger in proportion to the density than the FNCT defined by the function. Specifically, based on the data of the example and the comparative example, assuming the value of the FNCT and the density that distinguishes the example and the comparative example with a small FNCT corresponding to the density, the relational expression that holds between the FNCT and the density , the parameters of the relational expression are determined by the method of least squares.
In order to satisfy the formula (1), it can be achieved by appropriately selecting specific constituent components of the composition of the present invention.

Characteristic (5')
The polyethylene resin composition of the present invention has a rupture time (FNCT) (unit: hours) and HLMFR (unit: g / 10 minutes) in a full circumference notch creep test performed in accordance with ISO DIS 16770 according to the following formula (1 -2) is preferable from the standpoint of durability.
FNCT≧1.2×10 ⁵ ×HLMFR ⁻² Equation (1-2)
In general, polyethylene resin compositions exhibiting high fluidity tend to have low long-term durability such as resistance to environmental stress cracking. desired. Formula (1-2) indicates that the polyethylene resin composition of the present invention is superior to conventional polyethylene resins in resistance to environmental stress cracking in proportion to fluidity. That is, in order to distinguish the polyethylene resin composition of the present invention from the conventional one, the rupture time (FNCT) in the full circumference notch creep test is considered to be a function that has a negative correlation with the increase in fluidity (HLMFR). By setting the parameters of the function, it is shown that the FNCT of the polyethylene resin composition of the present invention is larger than the FNCT defined by the function in terms of fluidity. Specifically, based on the data of Examples and Comparative Examples, assuming values of FNCT and fluidity (HLMFR) that distinguish Comparative Examples with small FNCT corresponding to fluidity (HLMFR) from Examples, the FNCT and the fluidity The parameter of the relational expression is determined by the method of least squares with respect to the relational expression that is established between the sex (HLMFR).
Satisfaction of formula (1-2) can be achieved by appropriately selecting specific components of the composition of the present invention.

The polyethylene resin composition of the present invention preferably satisfies the above relational expression (1) and has an FNCT (time) of 50 hours or more, more preferably 80 hours or more.
The polyethylene resin composition of the present invention preferably satisfies the above relational expression (1-2) and has an FNCT (time) of 50 hours or more, more preferably 80 hours or more.
In the present invention, the all-around notched creep test can be performed in accordance with ISO DIS 16770. As a sample, a 6 mm × 6 mm × 11 mm prism with a notch of 1 mm was added to the entire periphery with a razor blade, and a test piece having a cross section of 4 mm × 4 mm was prepared. Inside, a tensile stress equivalent to 3.7 MPa is applied to the sample, and the time required for the sample to break is measured and taken as the rupture time of the FNCT.

Characteristic (6)
In the polyethylene resin composition of the present invention, the relationship between the tensile impact strength (TIS) (unit: kJ/m ² ) at 23° C. and the density (d) (unit: g/cm ³ ) is expressed by the following formula (2). meet.
TIS≧−22000×d+21184 Expression (2)
The polyethylene resin composition of the present invention has a tensile impact strength (TIS) (unit: kJ/m ² ) and a density (d) (unit: g/cm ³ ) at 23° C. further expressed by the following formula (2′). Satisfying the relationship shown is more preferable from the point of impact resistance.
TIS≧−22000×d+21208 Expression (2′)
In general, a polyethylene resin composition having a high density (rigidity) tends to have a low tensile impact strength (TIS), so it is desired that the polyethylene resin composition has both density (rigidity) and tensile impact strength (TIS). . Formula (2) indicates that the polyethylene resin composition of the present invention is superior in impact resistance to density (high tensile impact strength) as compared with conventional polyethylene resins. That is, in order to distinguish the polyethylene resin composition of the present invention from the conventional one, the tensile impact strength (TIS) is considered to be a function that has a negative correlation with the increase in density (d), and the parameters of the function are It is shown that the tensile impact strength of the polyethylene resin composition of the present invention is higher than the tensile impact strength defined by the function in proportion to the density. Specifically, based on the data of Examples and Comparative Examples, assuming values of tensile impact strength and density that distinguish Comparative Examples with insufficient tensile impact strength in proportion to density from Examples, the tensile impact strength and density The parameter of the relational expression is determined by the method of least squares. In order to further limit the range defined by equation (2'), parameters of equation (2') are determined in the same manner as in equation (2).
The satisfaction of formulas (2) and (2') can be achieved by appropriately selecting specific constituents of the composition of the present invention.

Characteristic (6')
The polyethylene resin composition of the present invention has a relationship between tensile impact strength (TIS) (unit: kJ/m ² ) at 23° C. and HLMFR (unit: g/10 min) represented by the following formula (2-2). It is preferable from the point of view of impact resistance to satisfy.
TIS≧−1.75×HLMFR+225 Formula (2-2)
In general, polyethylene resin compositions exhibiting high fluidity tend to have low tensile impact strength (TIS), so it is desired that the polyethylene resin composition has both high fluidity and tensile impact strength (TIS). The formula (2-2) indicates that the polyethylene resin composition of the present invention has excellent fluidity-matched impact resistance (high tensile impact strength) compared to conventional polyethylene resins. That is, in order to distinguish the polyethylene resin composition of the present invention from the conventional one, the tensile impact strength (TIS) is considered to be a function that has a negative correlation with the increase in fluidity (HLMFR), and the parameter of the function is , indicating that the tensile impact strength of the polyethylene resin composition of the present invention is greater than the tensile impact strength defined by the function in terms of fluidity. Specifically, based on the data of Examples and Comparative Examples, assuming values of tensile impact strength and fluidity that distinguish Comparative Examples with insufficient tensile impact strength in terms of HLMFR from Examples, the tensile impact strength and Regarding the relational expression that holds between liquidity and liquidity, the parameters of the relational expression are determined by the method of least squares.
Satisfaction of formula (2-2) can be achieved by appropriately selecting specific components of the composition of the present invention.

The polyethylene resin composition of the present invention preferably satisfies the above relational expression (2) and has a tensile impact strength (TIS) at 23° C. of 120 kJ/m ² or more, more preferably 130 kJ/m ² or more. Preferably.
Further, the polyethylene resin composition of the present invention preferably satisfies the above relational expression (2-2) and has a tensile impact strength (TIS) at 23° C. of 120 kJ/m ² or more, and further preferably 130 kJ/m m ² or more is preferable.
In the present invention, the tensile impact strength (TIS) (unit: kJ/m ² ) of the polyethylene resin composition at 23° C. is determined according to JIS K6922-2 by preparing a 1.5 mm compression-molded sheet and measuring ASTM D1822. A test piece punched out with an S-shaped dumbbell can be prepared according to , and measured under the conditions of 23° C. and 50% RH.

Characteristic (7)
The polyethylene resin composition of the present invention preferably further satisfies the following property (7) from the viewpoint of hollow moldability.
Characteristic (7): Melt tension (MT) (unit: mN) measured at 190° C. and HLMFR (unit: g/10 min) satisfy the relationship represented by the following formula (3).
MT≧334.85×HLMFR− ^0.635 Expression (3)
In general, a polyethylene resin composition exhibiting high fluidity tends to have a low melt tension. Therefore, a polyethylene resin composition having both high fluidity and good melt tension is desired. Formula (3) indicates that the polyethylene resin composition of the present invention is superior to conventional polyethylene resins in moldability corresponding to HLMFR (high melt tension). That is, in order to distinguish the polyethylene resin composition of the present invention from the conventional one, the melt tension (MT) is considered to be a function that has a negative correlation with the increase in HLMFR, and the parameters of the function are set. It shows that the MT of the polyethylene resin composition of the invention is larger than the MT defined by the function in terms of HLMFR. Specifically, based on the data of Examples and Comparative Examples, assuming values of MT and HLMFR that distinguish Examples and Comparative Examples having a small melt tension corresponding to HLMFR, the relationship established between the MT and HLMFR For the formula, the parameters of the relational formula are determined by the method of least squares.
In order to satisfy the formula (3), it can be achieved by appropriately selecting specific components of the composition of the present invention.

The polyethylene resin composition of the present invention preferably has a melt tension (MT) of 25 mN or more, more preferably 30 mN or more.
In the present invention, the melt tension of the polyethylene resin composition is determined by measuring the stress when the melted polyethylene resin composition is stretched at a constant speed, and can be measured under the following conditions.
[Measurement condition]
Model used: Capilograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd.
Nozzle diameter: 2.095mm
Nozzle length: 8.0mm
Inflow angle: 180° (flat)
Extrusion speed: 15 mm/min Take-up speed: 6.5 m/min Measurement temperature: 190°C

Characteristic (8)
It is preferable that the polyethylene resin composition of the present invention further satisfies the following property (8) from the viewpoint of compatibility and the appearance of molded articles.
Characteristic (8): The molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 5 to 25. be.
The molecular weight distribution (Mw/Mn) preferably has a lower limit of 10 or more and 14 or more, and an upper limit of 23 or less and 21 or less.
The molecular weight distribution (Mw/Mn) measured by GPC is involved in improving various physical properties and fluidity in the resin composition.
When the molecular weight distribution (Mw/Mn) of the polyethylene resin composition used in the present invention is at least the lower limit, the compatibility of each ethylene-based polymer component constituting the polyethylene resin composition becomes better, and the present invention It becomes easy to suppress the deterioration of the physical properties such as impact resistance and environmental stress crack resistance of the polyethylene resin composition of No. 2, and the appearance of the molded article becomes good, and the fluidity is easily improved. Moreover, it is preferable from the viewpoint that heat generation of the resin during the extrusion process can be easily suppressed by improving the fluidity of the polyethylene resin composition of the present invention. On the other hand, when the molecular weight distribution (Mw/Mn) is equal to or less than the upper limit, the long-term durability and impact resistance of the final resin composition are likely to be improved.
A molecular weight distribution within a predetermined range can be achieved by adopting a catalyst capable of controlling the molecular weight distribution and appropriate polymerization conditions. In the case of a bimodal or multimodal polymer, it can be controlled by adjusting the molecular weight of each component.

In the present invention, the molecular weight and molecular weight distribution can be measured by gel permeation chromatography (GPC) under the following conditions.
[Measurement condition]
Model used: Alliance GPCV2000 type manufactured by Japan Waters Co., Ltd. Measurement temperature: 145°C
Solvent: ortho-dichlorobenzene (ODCB)
Column: Showa Denko Shodex HT-806M × 2 + same HT-G
Flow rate: 1.0 mL/min Injection volume: 0.3 mL

[Sample preparation]
3 mg of sample and 3 mL of ortho-dichlorobenzene (containing 0.1 mg/mL of 1,2,4-trimethylphenol) were weighed into a 4-mL vial bottle and capped with a resin screw cap and a Teflon (registered trademark) septum. After that, using a SSC-9300 high-temperature shaker manufactured by Senshu Kagaku Co., Ltd. set at a temperature of 150° C., the mixture is melted for 2 hours. After the dissolution is completed, it is visually confirmed that there are no insoluble components.
[Create a calibration curve]
Prepare four 4 mL glass bottles, weigh 0.2 mg each of monodisperse polystyrene standard samples or n-alkanes of the following combinations (1) to (4), and then add orthodichlorobenzene (0.1 mg / mL 1,2,4-trimethylphenol) is weighed out, covered with a resin screw cap and a Teflon (registered trademark) septum, and then set to a temperature of 150 ° C. SSC-9300 type manufactured by Senshu Kagaku Co., Ltd. Dissolution is carried out for 2 hours using a hot shaker.
(1) Shodex S-1460, S-66.0, n-eicosane (2) Shodex S-1950, S-152, n-tetracontane (3) Shodex S-3900, S-565, S -5.05
(4) Shodex S-7500, S-1010, S-28.5
A vial containing the sample solution is set in the apparatus, measurement is performed under the conditions described above, and a chromatogram (retention time and response data set of the differential refractometer detector) is recorded at a sampling interval of 1 second. The retention time (peak apex) of each polystyrene standard sample is read from the resulting chromatogram and plotted against the logarithmic value of the molecular weight. Here, the molecular weights of n-eicosane and n-tetracontane are assumed to be 600 and 1200, respectively. A nonlinear least squares method is applied to this plot, and the obtained quartic curve is used as a calibration curve.

[Calculation of molecular weight]
Measurement is performed under the conditions described above, and a chromatogram is recorded at a sampling interval of 1 second.
From this chromatogram, "Size Exclusion Chromatography" written by Sadao Mori (Kyoritsu Shuppan), Chapter 4, p. 51-60 to calculate the differential molecular weight distribution curve and average molecular weight values (Mn, Mw and Mz). However, in order to correct the molecular weight dependence of dn/dc, the height H from the baseline in the chromatogram is corrected by the following formula. Chromatogram recording (data acquisition) and average molecular weight calculation are performed using an in-house program (created with Microsoft Visual Basic 6.0) on a PC installed with Microsoft OS Windows (registered trademark) XP.
H′=H/[1.032+189.2/M(PE)]
The following formula is used for molecular weight conversion from polystyrene to polyethylene.
M(PE) = 0.468 x M(PS)

Characteristic (9)
It is preferable that the polyethylene resin composition of the present invention further satisfies the following property (9) from the viewpoint that heat generation of the resin can be easily suppressed during the extrusion process and the molding cycle can be efficiently shortened.
Characteristic (9): A screw with a screw diameter (Ds) of 70 mm, a ratio (Ls/Ds) of the screw effective length (Ls) to the screw diameter (Ds) of 24, and a compression ratio of 3.0 was mounted in the cylinder. With a die having an outer diameter of 14 mm and an inner diameter of 10.5 mm attached to the extruder, the temperature of the resin at the die exit when the set temperature of the cylinder and die is 185 ° C. and the screw rotation speed is adjusted to an extrusion rate of 70 kg / hour. , the resin temperature is 235° C. or less when measured with a contact type resin thermometer.
An extruder equipped with a screw having a screw diameter (Ds) of 70 mm, a ratio (Ls/Ds) of the effective length of the screw (Ls) and the screw diameter (Ds) of 24, and a compression ratio of 3.0 in the cylinder. As a state in which a die of 14 mm and an inner diameter of 10.5 mm is attached, for example, a single-layer direct blow molding machine (eg BEX70/BLS-5E manufactured by Blends Co., Ltd.) having the above conditions can be used.
In order to make the characteristic (9) within a predetermined range, it is possible to adjust the hydrogen amount and temperature during the polymerization of each ethylene-based polymer component constituting the polyethylene resin composition, and the blending amount of each component. .

2. Structure of polyethylene-based resin composition The polyethylene-based resin composition of the present invention is one or two selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. By using the above ethylene-based polymer as an essential component, the properties (1) to (5) are simultaneously satisfied. The polyethylene-based resin composition of the present invention may further contain optional components described later in addition to the ethylene-based polymer as long as the properties (1) to (5) are satisfied at the same time. .
The copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms of the present invention usually contains 0.001 to 5 mol%, preferably 0.001, of structural units derived from an α-olefin having 3 to 12 carbon atoms. It is an ethylene polymer containing up to 2 mol %, more preferably 0.02 to 1.5 mol %, and even more preferably 0.02 to 1.3 mol %.
Here, α-olefins having 3 to 12 carbon atoms (hereinafter also simply referred to as “α-olefins”) include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3 -methyl-1-pentene, 1-octene, 1-decene and the like. In the present invention, among these α-olefins, it is preferable to use at least one selected from 1-hexene, 4-methyl-1-pentene and 1-octene.
A polyethylene resin composition that simultaneously satisfies the properties (1) to (5) considers the polymerization temperature and hydrogen concentration during polymerization for controlling the MFR, HLMFR, and melt flow rate ratio (HLMFR/MFR), It is produced by considering the type and content of the α-olefin for controlling the density, and by appropriately selecting the specific constituents of the composition of the present invention. When two or more ethylene-based polymers are contained, the two or more ethylene-based polymers may be continuously polymerized, or the two or more ethylene-based polymers are separately produced and then the Polymers may be melt-mixed, or two or more ethylene-based polymers may be continuously polymerized and one or more separately produced ethylene-based polymers may be melt-mixed.

The polyethylene-based resin composition of the present invention is not particularly limited in its polymerization catalyst, production method, etc., as long as it satisfies the properties (1) to (5).
Among them, the polyethylene resin composition of the present invention contains 10% by mass or more and 30% by mass or less of the following polyethylene component (A) and 70% by mass or more and 90% by mass or less of the following polyethylene component (B). (1) to (5) are likely to be satisfied at the same time, the compatibility of the resin component is high, the external appearance of the molded product is likely to be excellent, and the characteristics (6) to (9) are easily satisfied.
Polyethylene component (A); property (a1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (a2): density is 0.915 g/cm ³ or more and 0.940 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (B); property (b1): MFR is 0.1 g/10 min or more and 10 g/10 min or less; property (b2): density is 0.950 g/cm ³ or more and 0.980 g/cm ³ or less Characteristic (b3): HLMFR is 1 g/10 min or more and 1000 g/10 min or less; Characteristic (b4): 10% by mass or more and 50% by mass or less of polyethylene component (C) below; ) in an amount of 50% by mass or more and 90% by mass or less.
Polyethylene component (C); property (c1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (c2): density is 0.900 g/cm ³ or more and 0.950 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (D); property (d1): MFR is 10 g/10 min or more and 400 g/10 min or less; property (d2): density is 0.900 g/cm ³ or more and 0.980 g/cm ³ or less Ethylene polymer.

In the polyethylene-based resin composition of the present invention, the composition ratio of the polyethylene component (A) and the polyethylene component (B) satisfies the above characteristics (1) to (5) at the same time, compatibility and appearance of the molded product From the point of view, it is more preferable to contain 15% by mass or more and 25% by mass or less of the polyethylene component (A) and 75% by mass or more and 85% by mass or less of the polyethylene component (B), and the polyethylene component (A) is More preferably, it contains 20% by mass or more and 25% by mass or less, and 75% by mass or more and 80% by mass or less of the polyethylene component (B).

(1) polyethylene component (A)
Characteristic (a1)
The polyethylene component (A) used in the present invention should have an HLMFR of 0.5 g/10 minutes or more and 5 g/10 minutes or less from the viewpoint of fluidity and long-term durability. The upper limit of HLMFR of the polyethylene component (A) is preferably 3 g/10 minutes or less, more preferably 2 g/10 minutes or less.
If this HLMFR is less than the above lower limit, the HLMFR in the final resin composition cannot be achieved within the specified range, the fluidity may decrease, the resin may easily generate heat during the extrusion process, and the compatibility may deteriorate. Since it decreases, there is a possibility that the external appearance of the molded article may be impaired. On the other hand, if the HLMFR exceeds the above upper limit, the final resin composition may fail to achieve environmental stress cracking resistance, and the long-term durability of the molded article may deteriorate.
HLMFR can be adjusted mainly by the amount of hydrogen during polymerization of the polyethylene component (A) and the polymerization temperature.

Characteristic (a2)
The polyethylene component (A) used in the present invention should have a density of 0.915 g/cm ³ or more and 0.940 g/cm ³ or less from the viewpoint of impact resistance and environmental stress crack resistance. The lower limit of the density of the polyethylene component (A) is preferably 0.916 g/cm ³ or more, more preferably 0.918 g/cm ³ or more, and the upper limit of the density is preferably 0.930 g/cm ³ . 0.925 g/cm 3 or less, more preferably 0.925 g/cm ³ or less.
If the density is less than the lower limit, the density range of the final resin composition cannot be achieved, and there is a risk that the rigidity will decrease. On the other hand, if the density exceeds the above upper limit, the environmental stress crack resistance and impact resistance of the final resin composition may decrease.
Density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component (A).

Characteristic (a3)
The polyethylene component (A) used in the present invention preferably further satisfies the following property (a3) from the viewpoint of compatibility and molded product appearance.
Property (a3): The molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is from 1.5 to 10.
The molecular weight distribution (Mw/Mn) of the polyethylene component (A) preferably has a lower limit of 2 or more and 3 or more, and an upper limit of 8 or less and 5 or less.
When the molecular weight distribution (Mw/Mn) of the polyethylene component (A) used in the present invention is at least the lower limit, the compatibility of each ethylene-based polymer component constituting the polyethylene resin composition is improved. It is preferable from the viewpoint that deterioration of the physical properties such as impact resistance and environmental stress crack resistance of the polyethylene resin composition of the invention can be easily suppressed, the external appearance of the molded product can be improved, and the fluidity can be easily improved. Moreover, it is preferable from the viewpoint that heat generation of the resin during the extrusion process can be easily suppressed by improving the fluidity of the polyethylene resin composition of the present invention. On the other hand, when the molecular weight distribution (Mw/Mn) of the polyethylene component (A) is equal to or less than the upper limit, the long-term durability and impact resistance of the final resin composition are likely to be improved.

The polyethylene component (A) used in the present invention is not particularly limited as a production method as long as it satisfies the above specific properties, but is preferably produced by polymerization using a specific metallocene catalyst as a polymerization catalyst. can do.
Also, the polyethylene component (A) having a long-chain branched structure can be obtained through chain transfer to ethylene to produce a polyethylene (macromonomer) having a terminal vinyl group, followed by copolymerization of the macromonomer and ethylene.
Among metallocene-based catalysts, catalysts having a metallocene complex with a specific structure are preferred, and metallocene complexes having a cyclopentadienyl ring and a heterocyclic aromatic group, or metallocene complexes having a cyclopentadienyl ring and a fluorenyl ring are particularly preferred. preferable.

Polyethylene component (A) is preferably polymerized with a metallocene catalyst containing Ti, Zr or Hf. Examples of metallocene-based catalysts include a combination of a complex called a metallocene complex, in which a ligand having a cyclopentadiene skeleton is coordinated to a transition metal, and a cocatalyst. Specific metallocene catalysts include a metallocene complex in which a transition metal containing Ti, Zr, Hf, etc. is coordinated with a ligand having a cyclopentadiene skeleton such as methylcyclopentadiene, dimethylcyclopentadiene, and indene; Examples of co-catalysts include those in which organometallic compounds of Groups 1 to 3 of the periodic table such as aluminoxane are combined, and supported catalysts in which these complex catalysts are supported on a carrier such as silica.

The metallocene catalyst used in the present invention contains the following catalyst component (i) and catalyst component (ii), optionally in combination with catalyst component (iii).
catalyst component (i): metallocene complex catalyst component (ii): compound that reacts with catalyst component (i) to form a cationic metallocene compound catalyst component (iii): particulate carrier

(1) catalyst component (i)
A metallocene compound of a Group 4 transition metal in the periodic table is used as the catalyst component (i). Specifically, compounds represented by the following general formulas (I) to (VII) are used.

(C ₅ H _5-a R ¹ _a )(C ₅ H _5-b R ² _b )MXY general formula (I)
Q ¹ (C ₅ H _4-c R ¹ _c )(C ₅ H _4-d R ² _d )MXY general formula (II)
Q ² (C ₅ H _4-e R ³ _e )ZMXY general formula (III)
(C ₅ H _5-f R ³ _f )ZMXY general formula (IV)
(C ₅ H _5-f R ³ _f )MXYW general formula (V)
Q ³ (C ₅ H _5-g R ⁴ _g )(C ₅ H _5-h R ⁵ _h )MXY general formula (VI)
Q ⁴ Q ⁵ (C ₅ H _3-i R ⁶ _i )(C ₅ H _3-j R ⁷ _j )MXY general formula (VII)

Here, Q ¹ , Q ⁴ and Q ⁵ are bonding groups that bridge two conjugated five-membered ring ligands, Q ² is a bonding group that bridges the conjugated five-membered ring ligand and Z group, Q ³ is a bonding group that bridges R ⁴ and R ⁵ , M is a transition metal of Groups 3 to 12 of the periodic table, X, Y and W are each independently hydrogen, halogen, or having 1 to 20 carbon atoms. hydrocarbon group, oxygen-containing hydrocarbon group having 1 to 20 carbon atoms, nitrogen-containing hydrocarbon group having 1 to 20 carbon atoms, phosphorus-containing hydrocarbon group having 1 to 20 carbon atoms, or silicon-containing hydrocarbon group having 1 to 20 carbon atoms Z is a ligand containing oxygen or sulfur, a silicon-containing hydrocarbon group having 1 to 40 carbon atoms, a nitrogen-containing hydrocarbon group having 1 to 40 carbon atoms or a phosphorus-containing hydrocarbon group having 1 to 40 carbon atoms. show. M is preferably a Group 4 transition metal such as Ti, Zr, Hf.

R ¹ to R ⁷ each independently represents a hydrocarbon group having 1 to 20 carbon atoms, a halogen group, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group, an aryloxy group, an oxygen-containing hydrocarbon group, silicon It represents a hydrocarbon-containing group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group or a boron-containing hydrocarbon group. Among these, at least one of R ¹ to R ⁵ is preferably a heterocyclic aromatic group. Among heterocyclic aromatic groups, furyl group, benzofuryl group, thienyl group and benzothienyl group are preferable, and furyl group and benzofuryl group are more preferable. These heterocyclic aromatic groups include hydrocarbon groups having 1 to 20 carbon atoms, halogen groups, halogen-containing hydrocarbon groups having 1 to 20 carbon atoms, oxygen-containing hydrocarbon groups, silicon-containing hydrocarbon groups, and phosphorus-containing hydrocarbon groups. It may have a hydrogen group, a nitrogen-containing hydrocarbon group or a boron-containing hydrocarbon group, but in this case, a hydrocarbon group having 1 to 20 carbon atoms or a silicon-containing hydrocarbon group is preferred. Two R ¹ , two R ² , two R ³ , two R ⁴ , two R ⁵ , two R ⁶ , or two R ⁷ adjacent to each other are bound may form a ring having 4 to 10 carbon atoms. a, b, c, d, e, f, g, h, i and j are 0≤a≤5, 0≤b≤5, 0≤c≤4, 0≤d≤4, 0≤e≤ 4, 0≦f≦5, 0≦g≦5, 0≦h≦5, 0≦i≦3, 0≦j≦3.

Linking groups Q ¹ , Q ⁴ , and Q ⁵ that bridge between two conjugated five-membered ring ligands, a linking group Q ² that bridges the conjugated five-membered ring ligand and Z group, and R Specific examples of Q ³ that bridges ⁴ and R ⁵ include the following. methylene group, alkylene group such as ethylene group, ethylidene group, propylidene group, isopropylidene group, phenylmethylidene group, alkylidene group such as diphenylmethylidene group, dimethylsilylene group, diethylsilylene group, dipropylsilylene group, diphenyl silicon-containing cross-linking groups such as a silylene group, a methylethylsilylene group, a methylphenylsilylene group, a methyl-t-butylsilylene group, a disilylene group, a tetramethyldisilylene group, a germanium-containing cross-linking group, an alkylphosphine, an amine, and the like; . Among these, an alkylene group, an alkylidene group, a silicon-containing cross-linking group, and a germanium-containing cross-linking group are particularly preferably used.

Specific Zr complexes represented by the above general formulas (I), (II), (III), (IV), (V), (VI) and (VII) are disclosed in JP-A-2017-179304. and compounds described in paragraphs 0045 to 0055 of this specific example, and compounds in which Zr in the specific examples is replaced with Hf or Ti can also be used. In addition, the metallocene complexes represented by general formulas (I), (II), (III), (IV), (V), (VI) and (VII) may be compounds represented by the same general formula or different general formulas. It can be used as a mixture of two or more compounds represented by the formula.

Among the catalyst components (i) described above, preferred metallocene complexes for producing the polyethylene component (A) are metallocene complexes represented by general formula (I) or general formula (II). However, metallocene complexes having a cyclopentadienyl ring and a heterocyclic aromatic group are preferred, and metallocene complexes having an indenyl ring skeleton are more preferred. A metallocene complex represented by the general formula (II) is preferable from the viewpoint of being able to produce a high-molecular-weight polymer and having excellent copolymerizability in the copolymerization of ethylene with other α-olefins. Most preferred is a metallocene complex represented by and having an indenyl ring skeleton. Being able to produce high-molecular-weight materials has the advantage that polymers with various molecular weights can be designed by adjusting the molecular weights of various polymers, as will be described later.
Furthermore, among the metallocene complexes represented by the general formula (II), the following compound group is preferable from the viewpoint of being able to produce polyethylene having a high molecular weight and long chain branches.

As an example of a preferred embodiment, the compound group is a bridged metallocene complex containing at least one heterocyclic aromatic group in the compound as R ¹ to R ² . Preferred heteroaromatic groups include the group consisting of furyl, benzofuryl, thienyl and benzothienyl groups. These substituents may further have a substituent such as a silicon-containing group. Of the substituents selected from the group consisting of furyl, benzofuryl, thienyl and benzothienyl groups, furyl and benzofuryl are more preferred. Furthermore, these substituents are preferably introduced at the 2-position of the substituted cyclopentadienyl group or substituted indenyl group, and at least one substituted cyclopentadienyl group having no other condensed ring structure is It is particularly preferred that the compound has

By using these compounds as metallocene complexes and by adopting specific polymerization conditions, the preferred polyethylene component (A) in the present invention can be easily produced.

These metallocene complexes are preferably used as a supported catalyst as described later. In the group of compounds mentioned above, it is thought that interaction between the so-called heteroatom contained in the furyl group or thienyl group and the solid acid on the carrier causes non-uniformity in the active site structure and tends to generate long chain branches. there is In addition, it is believed that in the above-mentioned group of compounds as well, the use of a supported catalyst changes the space around the active site, making it easier to generate long-chain branches.

(2) catalyst component (ii)
In the method for producing the polyethylene component (A) according to the present invention, as an essential component of the catalyst for olefin polymerization, in addition to the catalyst component (i), the metallocene compound of the catalyst component (i) is reacted to form a cationic metallocene compound. It is preferable to contain a compound (catalyst component (ii)) and, if necessary, a fine particle carrier (catalyst component (iii)).

One of the catalyst components (ii) is an organoaluminumoxy compound.
The organoaluminumoxy compound has an Al--O--Al bond in the molecule, and the number of bonds is usually in the range of 1-100, preferably 1-50. Such an organoaluminumoxy compound is usually a product obtained by reacting an organoaluminum compound with water.
The reaction of organoaluminum with water is usually carried out in an inert hydrocarbon (solvent). As inert hydrocarbons, aliphatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene and xylene, alicyclic hydrocarbons and aromatic hydrocarbons can be used. It is preferred to use aromatic hydrocarbons.

Any compound represented by the following general formula (VIII) can be used as the organoaluminum compound used for preparing the organoaluminumoxy compound, but trialkylaluminum is preferably used.
R ^a _t AlX ^a _3-t general formula (VIII)
(In general formula (VIII), R ^a represents a hydrocarbon group such as an alkyl group, alkenyl group, aryl group, or aralkyl group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, and X ^a represents a hydrogen atom or represents a halogen atom, and t represents an integer of 1≤t≤3.)

The alkyl group of trialkylaluminum may be any of methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group and the like. is particularly preferred.
Two or more of the organoaluminum compounds may be used in combination.

The reaction ratio between water and the organoaluminum compound (water/Al molar ratio) is preferably 0.25/1 to 1.2/1, particularly preferably 0.5/1 to 1/1, and the reaction temperature is , usually in the range of -70 to 100°C, preferably -20 to 20°C. The reaction time is usually selected in the range of 5 minutes to 24 hours, preferably 10 minutes to 5 hours. As the water required for the reaction, not only water but also water of crystallization contained in copper sulfate hydrate, aluminum sulfate hydrate, etc., and components capable of producing water in the reaction system can be used.
Among the organoaluminumoxy compounds described above, those obtained by reacting alkylaluminum with water are usually called aluminoxanes, particularly methylaluminoxane (including those substantially composed of methylaluminoxane (MAO)). is suitable as the organoaluminum oxy compound.
Of course, as the organoaluminum oxy compound, two or more of the above organoaluminum oxy compounds can be used in combination, and a solution or dispersion of the above organoaluminum oxy compound in the above inert hydrocarbon solvent. It is also possible to use

Further, other specific examples of the catalyst component (ii) include borane compounds and borate compounds. Specific examples of the borane compound and borate compound include compounds described in paragraphs 0065 to 0077 of JP-A-2017-179304.

A more particularly preferred catalyst component (ii) is an organoaluminumoxy compound.
By using these compounds as the catalyst component (ii) and by adopting specific polymerization conditions, the preferred polyethylene component (A) in the present invention can be easily produced.

(3) catalyst component (iii)
The particulate carrier, which is the catalyst component (iii), includes an inorganic carrier, a particulate polymer carrier, or a mixture thereof. As the inorganic carrier, metals, metal oxides, metal chlorides, metal carbonates, carbonaceous substances, or mixtures thereof can be used.
Suitable metals that can be used for the inorganic carrier include, for example, iron, aluminum, nickel and the like.

Examples of metal oxides include single oxides and composite oxides of elements of Groups 1 to 14 of the periodic table, such as SiO ₂ , Al ₂ O ₃ , MgO, CaO, B ₂ O ₃ , TiO ₂ , _{ZrO2 , Fe2O3 , Al2O3.MgO , Al2O3.CaO , Al2O3.SiO2 , Al2O3.MgO.CaO , Al2O3.MgO.SiO2 , Al 2} O ₃ ·CuO, Al ₂ O ₃ ·Fe ₂ O ₃ , Al ₂ O ₃ ·NiO, SiO ₂ ·MgO and other various natural or synthetic single oxides or complex oxides can be exemplified.
Here, the above formula is not a molecular formula but represents only the composition, and the structure and catalyst component ratio of the composite oxide used in the present invention are not particularly limited.
Moreover, the metal oxide used in the present invention may absorb a small amount of water and may contain a small amount of impurities.

As metal chlorides, for example, chlorides of alkali metals and alkaline earth metals are preferable, and specifically, MgCl ₂ , CaCl ₂ and the like are particularly preferable.
As metal carbonates, carbonates of alkali metals and alkaline earth metals are preferable, and specific examples include magnesium carbonate, calcium carbonate, barium carbonate, and the like.
Examples of carbonaceous substances include carbon black and activated carbon.
Any of the above inorganic carriers can be suitably used in the present invention, but metal oxides, silica, alumina and the like are particularly preferred.

These inorganic supports are generally calcined at 200 to 800° C., preferably 400 to 600° C. in air or in an inert gas such as nitrogen or argon to reduce the amount of surface hydroxyl groups to 0.8 to 1.5 mmol/g. It is preferable to use it after adjusting to .
The properties of these inorganic carriers are not particularly limited, but usually the average particle diameter is 5 to 200 μm, preferably 10 to 150 μm, the average pore diameter is 20 to 1000 Å, preferably 50 to 500 Å, and the specific surface area is 150 to 1000 m. ² /g, preferably 200-700 m ² /g, pore volume 0.3-2.5 cm ³ /g, preferably 0.5-2.0 cm ³ /g, apparent specific gravity 0.10-0. It is preferred to use mineral supports with 50 g/cm ³ .

Of course, the above-mentioned inorganic carriers can be used as they are. It can be used after being brought into contact with an organic aluminum compound such as diisobutylaluminum hydride or an organic aluminum oxy compound containing an Al—O—Al bond.

Further particularly preferred catalyst components (iii) include SiO ₂ , Al ₂ O ₃ and Al ₂ O ₃ ·SiO ₂ .
By using these compounds as the catalyst component (iii) and by employing specific polymerization conditions, the preferred polyethylene component (A) in the present invention can be easily produced.

(4) Contacting method, etc. The metallocene catalyst according to the present invention is a method of contacting each component when obtaining a catalyst composed of the catalyst component (i), the catalyst component (ii), and optionally the catalyst component (iii). is not particularly limited, and for example, the following methods can be arbitrarily adopted.

Contact method (1): After contacting the catalyst component (i) with the catalyst component (ii), the catalyst component (iii) is contacted.
Contact method (2): After contacting the catalyst component (i) with the catalyst component (iii), the catalyst component (ii) is contacted.
Contacting method (3): After contacting the catalyst component (ii) with the catalyst component (iii), the catalyst component (i) is contacted.

Among these contacting methods, contacting methods (1) and (3) are preferred, and contacting method (1) is most preferred. In either contacting method, an aromatic hydrocarbon (generally having 6 to 12 carbon atoms) such as benzene, toluene, xylene, ethylbenzene, heptane, hexane, decane, dodecane, or the like is generally used in an inert atmosphere such as nitrogen or argon. , cyclohexane, and other aliphatic or alicyclic hydrocarbons (generally having 5 to 12 carbon atoms) in the presence of a liquid inert hydrocarbon, with or without stirring, each component is brought into contact.
This contact is usually carried out at a temperature of -100°C to 200°C, preferably -50°C to 100°C, more preferably 0°C to 50°C, for 5 minutes to 50 hours, preferably 30 minutes to 24 hours, more preferably is preferably carried out for 30 minutes to 12 hours.

Further, when the catalyst component (i), the catalyst component (ii) and the catalyst component (iii) are brought into contact with each other, as described above, an aromatic hydrocarbon solvent in which certain components are soluble or sparingly soluble and Any aliphatic or alicyclic hydrocarbon solvent in which is insoluble or sparingly soluble can be used.

When the contact reaction between each component is carried out in stages, the solvent used in the former step may be used as it is as the solvent for the contact reaction in the latter step without removing it. In addition, after the initial contact reaction using a soluble solvent, some components are insoluble or sparingly soluble in liquid inert hydrocarbons (e.g., aliphatics such as pentane, hexane, decane, dodecane, cyclohexane, benzene, toluene, and xylene). after adding a hydrocarbon, an alicyclic hydrocarbon or an aromatic hydrocarbon) and recovering the desired product as a solid matter, or once part or all of the soluble solvent is removed by means of drying or the like to obtain the desired product. After removing the product as a solid, subsequent catalytic reaction of the desired product can be carried out using any of the inert hydrocarbon solvents described above. In the present invention, the contact reaction of each component may be carried out multiple times.

In the present invention, the ratio of use of catalyst component (i), catalyst component (ii) and catalyst component (iii) is not particularly limited, but the following ranges are preferred.

When an organoaluminumoxy compound is used as the catalyst component (ii), the atomic ratio (Al/M) of the aluminum of the organoaluminumoxy compound to the transition metal (M) in the catalyst component (i) is usually 1 to 100, 000, preferably 5 to 1,000, more preferably 50 to 200. When using a borane compound or borate compound, the atomic ratio of boron to the transition metal (M) in the metallocene compound (B/ M) is usually desirably selected in the range of 0.01-100, preferably 0.1-50, more preferably 0.2-10.
Furthermore, when a mixture of an organoaluminumoxy compound, a borane compound, and a borate compound is used as the catalyst component (ii), each compound in the mixture is used in the same manner as above for the transition metal (M). It is desirable to select by percentage.

The amount of the catalyst component (iii) used is 1 g per 0.0001 to 5 mmol, preferably 0.001 to 0.5 mmol, more preferably 0.01 to 0.1 mmol of the transition metal in the catalyst component (i). is.

The catalyst component (i), the catalyst component (ii), and the catalyst component (iii) are contacted with each other by any one of the contact methods (1) to (3), and then the solvent is removed. , an olefin polymerization catalyst can be obtained as a solid catalyst. It is desirable to remove the solvent under normal pressure or reduced pressure at 0 to 200° C., preferably 20 to 150° C., for 1 minute to 50 hours, preferably 10 minutes to 10 hours.

The metallocene catalyst can also be obtained by the following method.
Contacting method (4): The catalyst component (i) and the catalyst component (iii) are brought into contact with each other to remove the solvent. in contact with a mixture of
Contacting method (5): An organoaluminumoxy compound, a borane compound, a borate compound, or a mixture thereof is brought into contact with the catalyst component (iii) to remove the solvent, obtain a solid catalyst component, and convert the catalyst component ( i).
In the contact methods (4) and (5), the same conditions as those described above can be used for the component ratio, contact conditions, and solvent removal conditions.

A layered silicate can also be used as a component serving as both the catalyst component (ii) and the catalyst component (iii), which are essential components of the method for producing the polyethylene component (A) according to the present invention.
A layered silicate is a silicate compound having a crystal structure in which planes formed by ionic bonds or the like are stacked in parallel with weak bonding force.
Most of the layered silicates are naturally produced mainly as a main component of clay minerals, but these layered silicates are not particularly limited to naturally occurring ones, and may be artificially synthesized ones.

Among these, montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, teniolite, and other smectites, vermiculites, and micas are preferred.

In general, natural products are often non-ion-exchangeable (non-swelling). It is preferable to carry out a treatment for imparting. Particularly preferred among such treatments are the following chemical treatments.
Here, the chemical treatment can be any of surface treatment for removing impurities adhering to the surface and treatment for influencing the crystal structure and chemical composition of the layered silicate.
Specifically, (a) acid treatment using hydrochloric acid, sulfuric acid, etc., (b) alkali treatment using NaOH, KOH, _NH3 , etc., (c) selected from groups 2 to 14 of the periodic table (iv) alcohol, hydrocarbon Compounds, formamide, organic matter treatment such as aniline, and the like. These treatments may be performed alone, or two or more treatments may be combined.

The particle properties of the layered silicate can be controlled by pulverization, granulation, sizing, fractionation, or the like before, during, or after all steps. The method can be any sensible one. In particular, granulation methods include spray granulation, tumbling granulation, compression granulation, stirring granulation, briquetting, compacting, extrusion granulation, and fluid bed granulation. method, emulsion granulation method and submerged granulation method. Particularly preferred granulation methods are spray granulation, tumbling granulation and compression granulation.

Of course, the layered silicates described above can be used as they are, but these layered silicates can be used as trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, It can be used in combination with an organoaluminum compound such as diisobutylaluminum hydride or an organoaluminum oxy compound containing an Al—O—Al bond.

In the metallocene catalyst according to the present invention, the catalyst component (i) can be supported on the layered silicate by bringing the catalyst component (i) and the layered silicate into contact with each other, or by adding the catalyst component (i) and the organoaluminum compound. , the layered silicates may be brought into contact with each other.
The method of contacting each component is not particularly limited, and for example, the following method can be optionally adopted.
Contacting method (6): After contacting the catalyst component (i) with an organoaluminum compound, they are contacted with a layered silicate support.
Contact method (7): After contacting the catalyst component (i) with the layered silicate support, they are contacted with an organoaluminum compound.
Contacting method (8): After contacting the organoaluminum compound and the layered silicate support, they are contacted with the catalyst component (i).

Among these contacting methods, contacting methods (6) and (8) are preferred. In either contacting method, an aromatic hydrocarbon (usually having 6 to 12 carbon atoms) such as benzene, toluene, xylene, ethylbenzene, heptane, hexane, decane, dodecane is generally used in an inert atmosphere such as nitrogen or argon. , cyclohexane, and other aliphatic or alicyclic hydrocarbons (usually having 5 to 12 carbon atoms) in the presence of a liquid inert hydrocarbon, with or without stirring, each component is brought into contact.

The proportions of catalyst component (i), organoaluminum compound, and layered silicate support are not particularly limited, but are preferably within the following ranges.
The supported amount of the catalyst component (i) is 0.0001 to 5 mmol, preferably 0.001 to 0.5 mmol, more preferably 0.01 to 0.1 mmol per 1 g of the layered silicate support.
When using an organoaluminum compound, the amount of Al supported is desirably in the range of 0.01 to 100 mol, preferably 0.1 to 50 mol, and more preferably 0.2 to 10 mol.

As for the method of supporting and solvent removal, the same conditions as those for the inorganic carrier can be used.
When a layered silicate is used as a component that serves both as the catalyst component (ii) and the catalyst component (iii), the polymerization activity is high and the productivity of the ethylene polymer having long chain branches is improved.
The olefin polymerization catalyst thus obtained may be used after prepolymerizing the monomer if necessary.

As examples of the production of metallocene catalysts, for example, it is possible to produce by considering the "catalyst" and "mixing ratio and conditions of raw materials" described in JP-A-2002-535339 and JP-A-2004-189869. can. Moreover, the index of the polymer can be controlled by various polymerization conditions, for example, by the methods described in JP-A-2-269705 and JP-A-3-21607.

The polyethylene component (A) is an ethylene homopolymer or ethylene and an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1 - Obtained by copolymerization with octene or the like. Copolymerization with a diene is also possible for the purpose of modification. Examples of diene compounds used at this time include butadiene, 1,4-hexadiene, ethylidenenorbornene, dicyclopentadiene and the like. The comonomer content during polymerization can be arbitrarily selected. The α-olefin content therein is 0.001-40 mol%, preferably 0.001-30 mol%.
The ethylene used in each polyethylene component used in the present invention may be ethylene produced from crude oil derived from ordinary fossil raw materials, or may be plant-derived ethylene. Plant-derived ethylene and polyethylene include, for example, ethylene and polymers thereof described in JP-T-2010-511634. Plant-derived ethylene and its polymers are carbon-neutral (does not use fossil raw materials and does not lead to an increase in carbon dioxide in the atmosphere), making it possible to provide environmentally friendly products.

The molecular weight of the produced polymer can be adjusted to some extent by changing the polymerization conditions such as the polymerization temperature and the molar ratio of the catalyst, but the molecular weight can be more effectively adjusted by adding hydrogen to the polymerization reaction system. can be done.
Also, a component for removing moisture, a so-called scavenger, may be added to the polymerization system without any problem.
Such scavengers include organoaluminum compounds such as trimethylaluminum, triethylaluminum and triisobutylaluminum, the above organoaluminumoxy compounds, modified organoaluminum compounds containing branched alkyl, organozinc compounds such as diethyl zinc and dibutyl zinc, diethyl Magnesium, organomagnesium compounds such as dibutylmagnesium and ethylbutylmagnesium, Grignard compounds such as ethylmagnesium chloride and butylmagnesium chloride, and the like are used. Among these, triethylaluminum, triisobutylaluminum and ethylbutylmagnesium are preferred, and triethylaluminum is particularly preferred.
It can also be applied to a multi-stage polymerization system having two or more stages in which polymerization conditions such as hydrogen concentration, amount of monomers, polymerization pressure and polymerization temperature are different from each other.

The polyethylene component (A) can be produced by a production process such as a gas phase polymerization method, a solution polymerization method, or a slurry polymerization method, preferably a slurry polymerization method. Among the polymerization conditions for the polyethylene component (A), the polymerization temperature can be selected from the range of 0 to 200°C. In slurry polymerization, the polymerization is carried out at a temperature below the melting point of the polymer produced. The polymerization pressure can be selected from the range of atmospheric pressure to about 10 MPa. From aliphatic hydrocarbons such as hexane, heptane, and isobutane, aromatic hydrocarbons such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, etc., in a state where oxygen, water, etc. are substantially cut off. It can be prepared by slurry polymerization of ethylene and α-olefin in the presence of selected inert hydrocarbon solvent.

If the polyethylene component (A) satisfies the range specified in the present invention, it is polymerized sequentially and continuously in a single polymerization vessel, a plurality of reactors connected in series or in parallel, and a plurality of ethylene-based polymers are separately It may be one mixed after polymerization.

(2) polyethylene component (B)
Characteristic (b1)
For the polyethylene component (B) used in the present invention, one having an MFR of 0.1 g/10 min or more and 10 g/10 min or less is selected from the viewpoint of fluidity and impact resistance. The lower limit of the MFR of the polyethylene component (B) is preferably 2 g/10 minutes or more, more preferably 5 g/10 minutes or more, and the upper limit of the MFR is preferably 9 g/10 minutes or less, more preferably 8 g. /10 minutes or less.
If this MFR is less than the lower limit, the molecular weight increases, and 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 is reduced, so that the resin tends to generate heat during the extrusion process, and the flow is unstable such as shark skin and melt fracture. Since the phenomenon is likely to occur, there is a risk that the appearance of the molded product will be impaired.
On the other hand, if the MFR exceeds the upper limit, impact resistance may not be ensured due to the effect of an increase in the amount of low-molecular-weight components. Moreover, in the final resin composition, the impact resistance cannot be achieved, and the drop impact resistance of the molded product may be lowered.
The MFR can be adjusted mainly by adjusting the amount of hydrogen during polymerization of the polyethylene component (B) and the polymerization temperature.

Characteristic (b2)
The polyethylene component (B) used in the present invention should have a density of 0.950 g/cm ³ or more and 0.980 g/cm ³ or less from the viewpoint of impact resistance and environmental stress crack resistance. The lower limit of the density of the polyethylene component (B) is preferably 0.951 g/cm ³ or more, and the upper limit of the density is preferably 0.975 g/cm ³ or less, more preferably 0.968 g/cm ³ . It is below.
If the density of the polyethylene component (B) is less than the above lower limit, the density range in the final resin composition cannot be achieved, and the rigidity may be insufficient. On the other hand, if the density exceeds the above upper limit, the impact resistance and environmental stress cracking resistance of the final resin composition may deteriorate, and the drop impact resistance and long-term durability of the container may deteriorate.
The density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component (B).

Characteristic (b3)
As the polyethylene component (B), one having an HLMFR of 1 g/10 min or more and 1000 g/10 min or less is selected from the viewpoints of compatibility and appearance of the molded article. The lower limit of the HLMFR of the polyethylene component (B) is preferably 100 g/10 min or more, more preferably 250 g/10 min or more, and the upper limit of the HLMFR is preferably 800 g/10 min or less, more preferably 600 g. /10 minutes or less.
If the HLMFR is less than the lower limit, the viscosity of the polyethylene component (C), which is a high-molecular weight component, in the low strain rate region becomes too high, and the polyethylene component (C) is not sufficiently dispersed, resulting in poor surface properties of the molded product. It is difficult to smoothen the surface and the appearance may be inferior. On the other hand, when the upper limit is exceeded, the viscosity of the polyethylene component (B) in the low strain rate region decreases, the dispersion promoting effect of the polyethylene component (A) decreases, and as a result the polyethylene component (A) is sufficiently dispersed. This may result in poor appearance of the molded product.

Characteristic (b4)
The polyethylene component (B) further contains 10% by mass or more and 50% by mass or less of the following polyethylene component (C) and 50% by mass or more and 90% by mass or less of the following polyethylene component (D) from the viewpoint of the appearance of the molded product. It is an ethylene polymer.
Polyethylene component (C); property (c1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (c2): density is 0.900 g/cm ³ or more and 0.950 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (D); property (d1): MFR is 10 g/10 min or more and 400 g/10 min or less; property (d2): density is 0.900 g/cm ³ or more and 0.980 g/cm ³ or less Ethylene polymer.

Thus, the polyethylene component (B) contains specific amounts of the relatively high molecular weight polyethylene component (C) and the relatively low molecular weight polyethylene component (D).
In the polyethylene component (B) used in the present invention, the composition ratio of the polyethylene component (C) and the polyethylene component (D) satisfies the properties (1) to (5) at the same time, and the polyethylene component (A) From the viewpoint of suppressing poor dispersion of and improving the appearance of the molded product, the polyethylene component (C) is 15% by mass or more and 40% by mass or less, and the polyethylene component (D) is 60% by mass or more and 85% by mass or less. More preferably, the content of the polyethylene component (C) is 20% by mass or more and 30% by mass or less, and the content of the polyethylene component (D) is 70% by mass or more and 80% by mass or less.

Characteristic (c1)
The polyethylene component (C) contained in the polyethylene component (B) has an HLMFR of 0.5 g/10 minutes or more and 5 g/10 minutes or less from the viewpoints of suppression of resin heat generation during the extrusion process and appearance of the molded product. choose things. The lower limit of the HLMFR of the polyethylene component (C) is preferably 0.8 g/10 min or more, more preferably 1.0 g/10 min or more, and the upper limit of the HLMFR is preferably 3 g/10 min or less. More preferably, it is 2.5 g/10 minutes or less.
If the HLMFR is less than the above lower limit, the HLMFR in the final resin composition cannot be achieved within the specified range, the fluidity may decrease, the resin may easily generate heat during the extrusion process, and the compatibility may deteriorate. Since it decreases, there is a possibility that the external appearance of the molded article may be impaired. On the other hand, if the HLMFR exceeds the upper limit, the final resin composition cannot achieve environmental stress cracking resistance, and the long-term durability of the molded article may deteriorate.
HLMFR can be adjusted mainly by the amount of hydrogen during polymerization of the polyethylene component (C) and the polymerization temperature.

Characteristic (c2)
The polyethylene component (C) contained in the polyethylene component (B) should have a density of 0.900 g/cm ³ or more and 0.950 g/cm ³ or less from the viewpoint of impact resistance and environmental stress crack resistance. . The lower limit of the density of the polyethylene component (C) is preferably 0.930 g/cm ³ or more, more preferably 0.940 g/cm ³ or more, and the upper limit of the density is preferably 0.948 g/cm ³ . It is below.
If the density of the polyethylene component (C) is less than the above lower limit, the density range in the final resin composition cannot be achieved, and the rigidity may be insufficient. On the other hand, if the density exceeds the above upper limit, the final resin composition may deteriorate in impact resistance and may deteriorate in drop impact resistance and long-term durability of the container.
Density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component (C).

Characteristic (d1)
For the polyethylene component (D) contained in the polyethylene component (B), one having an MFR of 10 g/10 min or more and 400 g/10 min or less is selected from the viewpoint of moldability and appearance of the molded product. The lower limit of the MFR of the polyethylene component (D) is preferably 150 g/10 minutes or more, more preferably 250 g/10 minutes or more, and the upper limit of the MFR is preferably 350 g/10 minutes or less, more preferably 320 g. /10 minutes or less.
If this MFR is less than the lower limit, the molecular weight increases, and 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 is reduced, so that the resin tends to generate heat during the extrusion process, and the flow is unstable such as shark skin and melt fracture. Since the phenomenon is likely to occur, there is a risk that the appearance of the molded product will be impaired.
On the other hand, if the MFR exceeds the upper limit, impact resistance may not be ensured due to the effect of an increase in the amount of low-molecular-weight components. Moreover, in the final resin composition, the impact resistance cannot be achieved, and the drop impact resistance of the molded product may be lowered.
The MFR can be adjusted mainly by adjusting the amount of hydrogen during polymerization of the polyethylene component (D) and the polymerization temperature.

Characteristic (d2)
The polyethylene component (D) contained in the polyethylene component (B) should have a density of 0.900 g/cm ³ or more and 0.980 g/cm ³ or less from the viewpoint of impact resistance and environmental stress crack resistance. . The lower limit of the density of the polyethylene component (D) is preferably 0.950 g/cm ³ or more, more preferably 0.960 g/cm ³ or more, and the upper limit of the density is preferably 0.975 g/cm ³ . 0.970 g/cm 3 or less, more preferably 0.970 g/cm ³ or less.
If the density of the polyethylene component (B) is less than the above lower limit, the density range in the final resin composition may not be achieved and the rigidity may be insufficient. On the other hand, if the density exceeds the upper limit, the impact resistance and environmental stress cracking resistance of the final resin composition may decrease, and the drop impact resistance and long-term durability of the container may deteriorate. .
Density can be adjusted mainly by the amount of α-olefin during polymerization of the polyethylene component (D).

Characteristic (b5)
The polyethylene component (B) preferably satisfies the following property (b5) from the viewpoint of compatibility and appearance of molded articles.
Characteristic (b5): The molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 10 to 30. be.
The molecular weight distribution (Mw/Mn) of the polyethylene component (B) preferably has a lower limit of 12 or more and 15 or more, and an upper limit of 25 or less and 20 or less.
When the molecular weight distribution (Mw/Mn) of the polyethylene component (B) used in the present invention is at least the lower limit, the compatibility of each ethylene-based polymer component constituting the polyethylene resin composition is improved. It is preferable from the viewpoint that deterioration of the physical properties such as impact resistance and environmental stress crack resistance of the polyethylene resin composition of the invention can be easily suppressed, the external appearance of the molded product can be improved, and the fluidity can be easily improved. Moreover, it is preferable from the viewpoint that heat generation of the resin during the extrusion process can be easily suppressed by improving the fluidity of the polyethylene resin composition of the present invention. On the other hand, when the molecular weight distribution (Mw/Mn) of the polyethylene component (B) is equal to or less than the upper limit, the long-term durability and impact resistance of the final resin composition are likely to be improved.

Characteristic (b6)
The polyethylene component (B) used in the present invention preferably satisfies the following property (b6) from the viewpoint of appearance of the molded article.
Property (b6): Ratio of melt flow rate (HLMFR _A ) of polyethylene component (A) to melt flow rate (HLMFR _C ) of polyethylene component (C), which is a high molecular weight component contained in polyethylene component (B) (HLMFR _A /HLMFR _C ) is 0.1 or more and 1.5 or less.
If HLMFR _A /HLMFR _C is less than the above lower limit, the viscosity ratio of the polyethylene component (A) and the polyethylene component (B) in the low shear region becomes small, and the effect of accelerating the dispersion of the polyethylene component (A) may decrease. be. On the other hand, when the HLMFR _A /HLMFR _C exceeds the above upper limit, the viscosity of the polyethylene component (C) increases, the polyethylene component (C) is not sufficiently dispersed, and the surface properties of the molded product become difficult to smooth, resulting in poor appearance. There is a risk of deterioration.

Characteristic (b7)
The polyethylene component (B) used in the present invention preferably satisfies the following property (b7) from the viewpoint of fluidity and moldability.
Characteristic (b7): The ratio (HLMFR _B /HLMFR _A ) of the melt flow rate (HLMFR _B ) of the polyethylene component (B) to the melt flow rate (HLMFR _A ) of the polyethylene component (A) is 100 or more and 1500 or less. HLMFR _B /HLMFR _A of the polyethylene component (B) is more preferably 200 or more and 1000 or less.
When the HLMFR _B /HLMFR _A of the polyethylene component (B) is 100 or more, the fluidity of the polyethylene resin composition is improved, which is preferable because heat generation of the resin is easily suppressed during the extrusion process. On the other hand, when the HLMFR _B /HLMFR _A is 1500 or less, the melt tension of the polyethylene resin composition is improved, which is preferable from the viewpoint of improving moldability.

The polyethylene component (B) used in the present invention is an ethylene homopolymer or a copolymer of ethylene and α-olefin, and can be polymerized using various polymerization catalysts as long as the above properties are satisfied. can. The polyethylene component (B) used in the present invention can be produced by polymerization using a Ziegler-Natta catalyst or metallocene catalyst, preferably a Ziegler-Natta catalyst. This is because polyethylene derived from a Ziegler-Natta catalyst has a moderately wide molecular weight distribution, excellent melt molding properties, and mechanical strength.
The Ziegler-Natta catalyst is a polymerization catalyst that uses titanium as an active species, and can be appropriately selected and used from conventionally known catalysts. As the Ziegler-Natta catalyst, a magnesium-titanium composite Ziegler-Natta catalyst is particularly preferable. The magnesium-titanium composite Ziegler-Natta catalyst has excellent particle shape and excellent polymerization activity.
The magnesium-titanium composite Ziegler-Natta catalyst is preferably further modified with an organoaluminum compound. By using such a modified Ziegler-Natta catalyst, it is possible to produce polyethylene with few short chain branches. A magnesium-titanium composite Ziegler-Natta catalyst modified with an organoaluminum compound can be produced with reference to JP-A-2012-72229.

Conventionally known methods can be appropriately used as the method for polymerizing the polyethylene component (B) using a Ziegler-Natta catalyst. For example, slurry polymerization, a liquid phase polymerization method such as solution polymerization, or a gas phase polymerization method can be employed, but the slurry polymerization method is particularly preferable, and the slurry polymerization method using a pipe loop reactor, Any slurry polymerization method using an autoclave reactor can be used. Among them, a slurry polymerization method using a pipe loop type reactor is preferable (for details of a pipe loop type reactor and slurry polymerization using the same, see Kazuo Matsuura and Naotaka Mikami, "Polyethylene Technical Readers", page 148, 2001, listed in the Industrial Research Institute).
Ethylene used as a raw material can be the same as that in the polyethylene component (A).

A liquid phase polymerization method is usually carried out in a hydrocarbon solvent. As the hydrocarbon solvent, inert hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene, and xylene are used singly or as a mixture. As the gas phase polymerization method, a commonly known polymerization method such as a fluidized bed, agitated bed, etc., can be employed in the presence of an inert gas, and a so-called condensing mode in which a medium for removing the heat of polymerization is allowed to coexist can also be employed. .
The polymerization temperature in the liquid phase polymerization method is generally 0 to 300°C, practically 20 to 200°C, preferably 40 to 180°C, more preferably 50 to 150°C, particularly preferably 70 to 110°C. °C. The catalyst concentration and ethylene concentration in the reactor can be any concentration sufficient to allow polymerization to proceed. For example, the catalyst concentration can range from about 0.0001 to about 5 weight percent, based on the weight of the reactor contents, for liquid phase polymerization. Similarly, the ethylene concentration can range from about 1% to about 10% based on the weight of the reactor contents for liquid phase polymerizations. Similarly, the ethylene concentration can be in the range of 0.1 to 10 MPa as total pressure in the case of gas phase polymerization. In addition, it is possible to carry out polymerization in the presence of hydrogen. In order to produce an ethylene-based polymer with an excellent balance of durability, impact resistance, and rigidity, it is necessary to set hydrogen and ethylene in a specific ratio. It is better to polymerize in the bottom. Hydrogen generally functions as a so-called chain transfer agent for adjusting molecular weight.

As a polymerization method, in addition to single-stage polymerization in which an ethylene-based polymer is produced using one reactor, at least two or more reactions are used to improve the production amount or to widen the molecular weight distribution or comonomer composition distribution. Multistage polymerization can also be carried out by connecting the reactors in series and/or in parallel. In the case of multi-stage polymerization, serial multi-stage polymerization is preferred in which a plurality of reactors are connected and the reaction mixture obtained by polymerization in the first reactor is continuously supplied to the second and subsequent reactors. In the series multi-stage polymerization method, the polymerization reaction mixture in the reactor of the preceding stage is transferred to the reactor of the subsequent stage by continuous discharge through a connecting pipe.

The polyethylene component (B) contains specific amounts of the polyethylene component (C) and the polyethylene component (D), and the polyethylene component (C) and the polyethylene component (D) are polymerized respectively. It may be a mixture, may be obtained by continuous multi-stage polymerization, or may be obtained by a combination thereof. Among them, the polyethylene component (B) is preferably obtained by multi-stage polymerization of the polyethylene component (C) and the polyethylene component (D) from the viewpoint of improving the production amount.
Among them, the polyethylene component (B) obtained by first polymerizing the polyethylene component (C) and then polymerizing the polyethylene component (D) by multi-stage polymerization is a polyethylene component (B) even when the viscosity of the polyethylene component (C) is high. The previously polymerized polyethylene component (C) present on the outer surface of the particles of ) is spread out in the state of particles by the subsequently polymerized polyethylene component (D) present in the center, and the polyethylene component (A) It is preferable from the point that the effect of improving the compatibility when kneading with is obtained.

A specific embodiment of the above multi-stage polymerization will be described by taking a two-stage polymerization using two reactors as an example.
In the case of two-stage polymerization of the polyethylene component (C) and the polyethylene component (D), the high-molecular-weight component is produced in the first-stage reactor, the low-molecular-weight component is produced in the second-stage reactor, or the low-molecular-weight component is produced in the first-stage reactor. Either method of producing the molecular weight component and the high molecular weight component in the second stage reactor may be used, but the method of producing the high molecular weight component in the first stage reactor and the low molecular weight component in the second stage reactor is preferred. , it is more preferable in terms of productivity because it does not require an intermediate hydrogen flash tank when shifting from the first stage to the second stage.

In the first stage, copolymerization of ethylene alone or, if necessary, other ethylene as a comonomer is performed while adjusting the molecular weight by adjusting the ratio of the hydrogen concentration to the ethylene concentration, the polymerization temperature, or both, and by adjusting the comonomer concentration to the ethylene concentration. The polymerization reaction is carried out while adjusting the density by weight ratio.
In the second stage, there is hydrogen in the reaction mixture flowing in from the first stage and ethylene also flowing in, but if necessary, fresh hydrogen and ethylene can be added respectively. Therefore, in the second stage as well, the polymerization reaction can be carried out while adjusting the molecular weight by the ratio of the hydrogen concentration to the ethylene concentration, the polymerization temperature, or both, and by adjusting the density by the ratio of the comonomer concentration to the ethylene concentration. With respect to catalysts and organometallic compounds such as organoaluminum compounds, not only does the polymerization reaction continue in the second stage with the catalyst that flows in from the first stage, but the catalyst and organometallic compounds such as organoaluminum compounds are newly added in the second stage. Either compound or both may be supplied.

Since the polyethylene resin composition of the present invention is a polyethylene resin composition that simultaneously satisfies the properties (1) to (5), heat generation of the resin is suppressed during the extrusion process, and rigidity, environmental stress crack resistance, and impact resistance are obtained. It is possible to obtain a molded article having an excellent balance of
Furthermore, preferably, a polyethylene resin composition having one or more of the above properties (6) to (9) in addition to the above properties (1) to (5) exhibits the above effects even better.
Among them, when the content of the polyethylene component (A) is 10% by mass or more and 30% by mass or less and the content of the polyethylene component (B) is 70% by mass or more and 90% by mass or less, the compatibility of the resin components is increased, and the molded body It also becomes excellent in appearance.

Effects exhibited by the polyethylene resin composition of the present invention will be further described below.
In general, polyethylene is processed into industrial products by molding methods that pass through a molten state, such as injection molding, film molding, blow molding, and foam molding. Efforts are being made to shorten it. In many molding methods, it is effective to shorten the molding cycle by shortening the cooling and solidification steps after molding polyethylene in a molten state. Therefore, it is desirable to suppress shear heat generation of the resin during molding as much as possible. By reducing the time required for the cooling cycle, electric power costs can be reduced, and oxidative deterioration of polyethylene and the generation of foreign substances derived from volatile components are suppressed, making it possible to mold at a lower molten resin temperature. increasingly desired. However, when the molten resin temperature is lowered, the melt viscosity of the material increases, resulting in insufficient filling in the mold such as short shot, residual stress in the product due to polymer molecular orientation, and the accompanying cracks and product damage. Molding defects such as deterioration of dimensional stability tend to occur. Therefore, there is a demand for a polyethylene resin composition which has good fluidity even when the temperature of the molten resin is lowered and which suppresses the heat generation of the resin during the extrusion process.
However, at the same time as shortening the molding cycle, it is also required to maintain the function as a molded product. A high degree of balance is required. That is, in order to achieve an excellent balance of rigidity, environmental stress cracking resistance and impact resistance, it is required to contain a high molecular weight copolymer component having excellent strength, but the viscosity of the high molecular weight component is too high. Due to poor dispersion, the impact strength of the molded product is lowered, and the resin heats up during the extrusion process. In addition, the inclusion of a high-molecular-weight copolymer component, which is superior in strength, tends to generate heat in the resin during the extrusion process.
In contrast, in the present invention, a specific MFR, a specific HLMFR, a specific HLMFR/MFR ratio, and a specific density are satisfied, and the rupture time and density in the full circumference notch creep test are specified. By making a polyethylene resin composition that satisfies these relationships, the balance between the rigidity of the molded product, environmental stress crack resistance, and impact resistance, etc., is improved in terms of fluidity, and heat generation of the resin is suppressed during the extrusion process with high fluidity. A polyethylene resin composition was achieved.

Among them, when the polyethylene component (A) that satisfies the specific physical property balance and the polyethylene component (B) are mixed in a specific amount and used, the polyethylene component (B) that satisfies the specific physical property balance is highly Since the polyethylene component (C), which is a molecular weight component, and the polyethylene component (D), which is a low molecular weight component, are contained, compatibility with the polyethylene component (A), which is a high molecular weight component, is increased while containing the low molecular weight component. , each resin component in the resin composition has excellent compatibility, the surface properties are easily smoothed, and the polyethylene resin composition has excellent appearance of the molded product. In addition, since it has a high melt tension in terms of fluidity, it has excellent drawdown resistance and excellent moldability.

3. Method for producing polyethylene resin composition The polyethylene resin composition of the present invention is one or more selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. The production method is not particularly limited as long as it can produce a polyethylene resin composition containing the ethylene polymer as an essential component and satisfying the above properties (1) to (5).
The polyethylene resin composition of the present invention, among others, is easy to produce a resin composition that satisfies the above characteristics (1) to (5), and each resin component has excellent compatibility, and the appearance of the molded product is excellent. From the viewpoint of excellent properties, it is produced by melt-mixing the polyethylene component (A) and the polyethylene component (B) in a predetermined mixing ratio, and by adding other components as necessary and melt-mixing. is preferred.

In addition to the polyethylene component (A) and the polyethylene component (B), the polyethylene resin composition of the present invention may optionally contain the following substances as long as the object of the present invention is not impaired.
For example, various ethylene-based polymers such as high-density polyethylene, low-density polyethylene, high-pressure polyethylene, polar monomer-graft-modified polyethylene, ethylene-based wax, ultra-high-molecular-weight polyethylene, ethylene-based elastomer, and modified products thereof can be used. Addition of high-density polyethylene is preferable for improving rigidity, heat resistance, impact strength, and the like. Addition of low-density polyethylene is preferable for improving flexibility, impact strength, easy adhesion, transparency, low-temperature strength, and the like. Addition of high-pressure polyethylene is preferable for improving flexibility, easy adhesion, transparency, low-temperature strength, moldability and the like. Addition of polar monomer-graft-modified polyethylene such as maleic acid-modified polyethylene, ethylene/acrylic acid derivative copolymer, and ethylene/vinyl acetate copolymer improves flexibility, easy adhesion, colorability, compatibility with various materials, gas barrier properties, etc. preferred to improve Addition of ethylene wax is preferable for improving colorability, compatibility with various materials, moldability, and the like. Addition of ultra-high molecular weight polyethylene is preferable for improving mechanical strength, abrasion resistance, and the like. Addition of an ethylene-based elastomer is preferable for improving flexibility, mechanical strength, impact strength, and the like.
In addition to the above polymers, various resins can be used. Specifically, various nylon resins, various polyamides, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), various polyesters, polycarbonate resins, EVOH, EVA, PMMA, PMA, various engineering plastics, polylactic acid, celluloses, Examples include natural rubbers, polyurethane, vinyl chloride, fluorinated resins such as Teflon (registered trademark), inorganic polymers such as silicone resins, and the like.

The polyethylene resin composition of the present invention can be pelletized by mechanical melt-mixing using a pelletizer, homogenizer, or the like according to a conventional method, and then molded using various molding machines to obtain a desired molded product.
In addition to other olefinic polymers and rubbers, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, and antistatic agents may be added to the polyethylene resin composition obtained by the above method in accordance with conventional methods. Known additives such as clouding agents, antiblocking agents, processing aids, coloring pigments, cross-linking agents, foaming agents, inorganic or organic fillers, and flame retardants can be blended.
As additives, for example, antioxidants (phenol-based, phosphorus-based, sulfur-based), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like can be used singly or in combination of two or more. Fillers that can be used include calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silica stone, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, and titanium oxide. Among them, it is preferable to use calcium carbonate, talc and mica. In any case, the polyethylene resin composition may be blended with various additives, if necessary, and kneaded with a kneading extruder, Banbury mixer, or the like to obtain a molding material.

Further, in the present invention, a nucleating agent may be used in order to accelerate the crystallization speed of the polyethylene resin composition.
As the nucleating agent, generally known agents can be used, and general organic or inorganic nucleating agents can be used. For example, dibenzylidene sorbitol or its derivative, organic phosphoric acid compound or its metal salt, aromatic sulfonate or its metal salt, organic carboxylic acid or its metal salt, rosin acid partial metal salt, inorganic fine particles such as talc, imides , amides, quinacridone quinones, or mixtures thereof.
Among them, dibenzylidene sorbitol derivatives, organic metal phosphates, organic carboxylic acid metal salts and the like are suitable for their excellent transparency.
Specific examples of dibenzylidene sorbitol derivatives include 1,3:2,4-bis(o-3,4-dimethylbenzylidene) sorbitol and 1,3:2,4-bis(o-2,4-dimethylbenzylidene). Sorbitol, 1,3:2,4-bis(o-4-ethylbenzylidene)sorbitol, 1,3:2,4-bis(o-4-chlorobenzylidene)sorbitol, 1,3:2,4-dibenzylidene sorbitol, and specific examples of benzoic acid metal salts include hydroxy-di(t-butylbenzoate) aluminum and the like.

When a nucleating agent is added to the polyethylene resin composition of the present invention, the amount of the nucleating agent is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, per 100 parts by mass of the composition. Part by mass, more preferably 0.01 to 1 part by mass, particularly preferably 0.01 to 0.5 part by mass. If the amount of the nucleating agent is less than 0.01 parts by mass, the effect of improving the high-speed moldability is not sufficient.

4. Uses of the polyethylene-based resin composition The polyethylene-based resin composition of the present invention has an excellent balance between the rigidity of the molded article, environmental stress crack resistance, and impact resistance, and suppresses the heat generation of the resin during the extrusion process. Various moldings can be produced by various molding methods. Since the polyethylene-based resin composition of the present invention is excellent in hollow moldability such as drawdown resistance, it is preferably molded mainly by a blow molding method or the like, preferably to obtain various molded articles such as hollow containers. can be done.

5. Molded Article and Container The molded article of the present invention is a molded article containing the polyethylene resin composition of the present invention.
The molded article of the present invention can be produced by various molding methods using the polyethylene resin composition of the present invention as a raw material. The molded article of the present invention is preferably molded mainly by a blow molding method or the like, and preferably includes various hollow molded articles such as hollow containers.
The blow molded article containing the polyethylene-based resin composition of the present invention is not particularly limited, but can be produced by extrusion blow molding using a conventionally known blow molding machine or multi-layer blow molding machine. For example, after heating and melting the constituent resin of each layer with a plurality of extruders, the molten parison is extruded with a multi-layer die, then this parison is sandwiched between molds, and air is blown into the interior of the parison to produce a multi-layer hollow plastic. A molded body is produced.

The container of the present invention is a container having a layer containing the polyethylene resin composition of the present invention.
In the container of the present invention, the layer containing the polyethylene resin composition according to the present invention may further contain a colorant-containing resin composition such as a pigment masterbatch.
The container of the present invention may have a single layer structure of a layer containing the polyethylene resin composition of the present invention, or may have at least one layer containing the polyethylene resin composition of the present invention. It may be a structure. When the container of the present invention has a multilayer structure, it may have, for example, a permeation-reducing barrier layer, and a barrier layer is usually used for the permeation-reducing barrier layer.
The container of the present invention can be manufactured by appropriately selecting a conventionally known manufacturing method.

Since the polyethylene resin composition of the present invention satisfies the above properties, the molded article of the present invention using it has an excellent balance of rigidity, environmental stress crack resistance, and impact resistance, and also has excellent The appearance is easy to obtain, and heat generation of the resin is suppressed during the extrusion process, so the molding cycle can be shortened, and production can be performed with excellent production efficiency.
Therefore, it is suitable for applications such as containers that require such properties, and can be suitably used for applications such as containers for cosmetics, containers for detergents, shampoos and conditioners, and containers for foods such as edible oils.
Since the polyethylene resin composition of the present invention satisfies the above characteristics, among others, containers for cosmetics, detergents, shampoos and conditioners, containers for food such as edible oils, etc., which are required to have a good appearance, etc. It can be suitably used for the purpose of

In particular, a container, which is a molded article using the polyethylene resin composition of the present invention, can be molded at high speed and in a high cycle, has excellent product characteristics, and is economically advantageous. It is suitable as a container for

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

1. Measurement method The measurement method used in the examples is as follows.
(1) Melt flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg:
Measured according to JIS K6922-2:1997.
(2) Melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg:
Measured according to JIS K6922-2:1997.
(3) Density:
Measured according to JIS K6922-1, 2:1997.

(4) Measurement of molecular weight and molecular weight distribution by gel permeation chromatography (GPC):
It was measured by gel permeation chromatography (GPC) under the following conditions.
[Measurement condition]
Model used: Alliance GPCV2000 type manufactured by Japan Waters Co., Ltd. Measurement temperature: 145°C
Solvent: ortho-dichlorobenzene (ODCB)
Column: Showa Denko Shodex HT-806M × 2 + same HT-G
Flow rate: 1.0 mL/min Injection volume: 0.3 mL

[Sample preparation]
3 mg of sample and 3 mL of ortho-dichlorobenzene (containing 0.1 mg/mL of 1,2,4-trimethylphenol) were weighed into a 4-mL vial bottle and capped with a resin screw cap and a Teflon (registered trademark) septum. After that, using a Senshu Scientific SSC-9300 high-temperature shaker set at a temperature of 150° C., melting was performed for 2 hours. After the dissolution was completed, it was visually confirmed that there was no insoluble component.
[Create a calibration curve]
Four 4 mL glass bottles were prepared, and 0.2 mg each of monodisperse polystyrene standard samples or n-alkanes in the following combinations (a) to (d) were weighed out, followed by orthodichlorobenzene (0.1 mg/mL of 1,2,4-trimethylphenol) was weighed out, covered with a resin screw cap and a Teflon (registered trademark) septum, and then set to a temperature of 150 ° C. Senshu Scientific SSC-9300 model high temperature Dissolution was performed for 2 hours using a shaker.
(a) Shodex S-1460, S-66.0, n-eicosane (b) Shodex S-1950, S-152, n-tetracontane (c) Shodex S-3900, S-565, S -5.05
(d) Shodex S-7500, Shodex S-1010, Shodex S-28.5
A vial containing the sample solution was set in the apparatus, measurement was performed under the conditions described above, and a chromatogram (data set of retention time and response of the differential refractometer detector) was recorded at a sampling interval of 1 s. The retention time (peak apex) of each polystyrene standard sample was read from the resulting chromatogram and plotted against the logarithmic value of the molecular weight. Here, the molecular weights of n-eicosane and n-tetracontane were set to 600 and 1200, respectively. A nonlinear least squares method was applied to this plot, and the resulting quartic curve was used as a calibration curve.

[Calculation of molecular weight]
Measurement was performed under the conditions described above, and a chromatogram was recorded at a sampling interval of 1 s. From this chromatogram, "Size Exclusion Chromatography" written by Sadao Mori (Kyoritsu Shuppan), Chapter 4, p. A differential molecular weight distribution curve and average molecular weight values (Mn, Mw and Mz) were calculated by the methods described in 51-60. However, in order to correct the molecular weight dependence of dn/dc, the height H from the baseline in the chromatogram was corrected by the following formula. Chromatogram recording (data acquisition) and average molecular weight calculation were performed using an in-house program (created with Microsoft Visual Basic 6.0) on a PC installed with Microsoft OS Windows (registered trademark) XP.
H′=H/[1.032+189.2/M(PE)]
The following formula was used for molecular weight conversion from polystyrene to polyethylene.
M(PE) = 0.468 x M(PS)

(5) Environmental stress crack resistance (FNCT):
All notched creep tests were performed according to ISO DIS 16770. For the sample, a 6 mm × 6 mm × 11 mm prism with a notch of 1 mm around the entire circumference with a razor blade was prepared, and a test piece having a cross section of 4 mm × 4 mm was prepared and treated with pure water at 80 ° C. Among them, a tensile stress equivalent to 3.7 MPa was applied to the sample, and the time until the sample broke was measured and used as the rupture time of the FNCT.

(6) Tensile impact strength (TIS):
In accordance with JIS K6922-2, a 1.5 mm compression molded sheet was created, and in accordance with ASTM D1822, a test piece was punched out with an S-type dumbbell, and measured at 23 ° C. and 50% RH. went.

(7) Melt Tension (MT):
The melt tension was determined by measuring the stress when the molten ethylene polymer was stretched at a constant speed, and was measured under the following conditions.
[Measurement condition]
Model used: Capilograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd.
Nozzle diameter: 2.095mm
Nozzle length: 8.0mm
Inflow angle: 180° (flat)
Extrusion speed: 15 mm/min Take-up speed: 6.5 m/min Measurement temperature: 190°C

(8) Resin temperature during extrusion process:
An extruder equipped with a screw having a screw diameter (Ds) of 70 mm, a ratio (Ls/Ds) of the effective length of the screw (Ls) and the screw diameter (Ds) of 24, and a compression ratio of 3.0 in the cylinder. In a single-layer direct blow molding machine (BEX70/BLS-5E, manufactured by Blends Co., Ltd.) equipped with a hollow molding die of 14 mm and an inner diameter of 10.5 mm, the set temperature of the cylinder and die is 185 ° C., and the extrusion rate is The temperature of the resin at the die outlet when the screw rotation speed was adjusted to 70 kg/hour was measured with a contact resin thermometer (DP-350, manufactured by Rika Kogyo Co., Ltd.).

(9) Environmental stress crack resistance:
When the rupture time of environmental stress cracking resistance (FNCT) was 50 hours or more, it was evaluated as "○", and the others were evaluated as "x".

(10) Impact resistance:
A sample with a tensile impact strength (TIS) of 120 kJ/m ² or more was rated as “◯”, and the others were rated as “x”.

(11) Hollow moldability:
Single-layer direct blow molding machine (manufactured by Blends Co., Ltd., BEX70/BLS-5E, screw diameter (Ds) is 70 mm, ratio of screw effective length (Ls) to screw diameter (Ds) (Ls/Ds) is 24, compression At a ratio of 3.0), a straight die with an arbitrary die core diameter is used so that a constant pinch-off width is obtained, the molding resin temperature is adjusted to about 210 ° C. under the condition of a screw rotation speed of 10 rpm, and the parison is extruded to about 400 ml flat container shape (container with a length of about 19 cm, width of about 7 cm, maximum depth of about 5 cm, outer diameter of about 2 cm, height of about 2 cm, and a screw-shaped mouth) Blow mold (cavity surface blast finish , a mold with a cavity surface roughness Ra value of 0.7 μm), a mold temperature of 20° C., a blow pressure of 6 kg/cm ² , a container weight of about 30 g, and a molding cycle of about 10 to 12 seconds. If the container can be molded within the above conditions, the blow moldability is "good (○)", and holes are formed at the fused interface during blow-up, and a molded product with a uniform thickness distribution cannot be obtained due to significant drawdown, etc. Those that were difficult were rated as "defective (x)".

(12) Shortening of molding cycle:
When the resin temperature during the extrusion process was 235° C. or less, it was evaluated as “◯”, and when it was not, it was evaluated as “×”.

(13) Visual confirmation of molded product appearance:
The area ratio of fish eyes was measured by the following mixing evaluation method, and this was used to evaluate the external appearance of the molded product.
[Mixability evaluation method]
The sample to be measured is compressed at a temperature of 180 ° C. and a pressure of 100 kgf / cm ² in the first step using a mold with a thickness of 0.35 mm and two press molding machines for compression processing and cooling, In the second step, it is cooled at a temperature of 30° C. and a pressure of 50 kgf/cm ² to form a press sheet with a thickness of 0.4 mm. This press sheet was cut into test pieces of 50×50×0.4 mm.
Next, the test piece was stretched with a biaxial stretching device. As a biaxial stretching device, a biaxial stretching device SS-60 manufactured by Shibayama Scientific Instruments Co., Ltd. was used, and the test piece was stretched twice at a temperature of 150° C. and a stretching speed of 60 mm/min. The stretching procedure was such that a 1 cm square portion of the end of the test piece was chucked with 4-point chucks of a biaxial stretching device, and the non-chucked central portion of the press sheet was set to a square of 30×30 mm. After that, this test piece is heated to a temperature of 130 to 170° C. and biaxially stretched until the distance between diagonal chucks becomes 60 mm, and a sheet in which the central portion that is not chucked is stretched about twice as much is obtained. Created.
The surface of a square area of 30×30 mm located approximately in the center of the biaxially stretched sheet was imaged using a reflective 3D microscope. The magnification of the 3D microscope is 10×, and the area of the sheet to be photographed (one field of view) is 10×10 mm. In order to increase the reliability of the measurement, the measurement was performed four times in a square range of 30×30 mm located in the center of the sheet so that the fields of view do not overlap. The photographed image was binarized into a fish-eye portion and a non-fish-eye portion (uniform matrix portion). The conditions for the binarization process were set by the operator and used for all measurements.
The binarized image was read by a scanner and digitized to obtain image data.
The resolution of the scanner is 600 dpi or higher, preferably 900 dpi or higher. As a scanner, a scanner GT-F670 (manufactured by EPSON, resolution: 4800 dpi) was used.
Analysis of image data is realized by a personal computer and a software program executed thereon, and the image data is processed by the personal computer to determine the area, perimeter, length-to-width ratio, particle diameter, and circularity of each particle. We calculated characteristic parameters such as In this case, the characteristic parameters can be calculated using commercially available image processing software.
The image data is binarized and processed at some appropriate level, thresholding the coloration of the black and white portions of the image. The conditions for the binarization process were set by the operator and used for all measurements.
In the image analysis, the area, perimeter, maximum length, maximum length vertical length (length in the direction perpendicular to the maximum length), etc. of each particle are calculated by known means, and various parameters of the particles are calculated from them for each particle. The calculated parameters include the equivalent circle diameter of the particle (diameter of a circle with an area equal to the area of the image of the particle), circularity (perimeter of a circle with an area equal to the area of the image of the particle and the perimeter of the image), and the aspect ratio (ratio of the maximum length of the particle image to the maximum vertical length).
Note that the equivalent circle diameter is the equivalent circle diameter = (area value of the image of the particle/π) ^1/2 × 2, and the circularity is the circularity = (perimeter of the circle having the area value of the image of the particle)/( Perimeter of particle image), and the aspect ratio is calculated by (maximum length of particle image)/(maximum vertical length of particle image).
In the present invention, as the measurement of fisheyes, the area ratio of fisheyes in the image was obtained. The fisheye area ratio of one sample was calculated by averaging measured values obtained in four fields of view photographed on one test piece.
Then, "1" when the area ratio of the fish eye in the image is 0.2% or less, "2" when it is more than 0.2 to 0.5%, and more than 0.5 to 3.0%. The case was evaluated as "3", the case of more than 3.0 to 5.0% as "4", and the case of more than 5% as "5".
The case of "1" or "2" was given as "◯", and the others were given as "x".

(14) Comprehensive evaluation:
Evaluate the suitability as a polyethylene resin composition, and the environmental stress crack resistance, impact resistance, and shortening of the molding cycle are all good items, "○", and others are "x". bottom.

2. Examples and Comparative Examples <Synthesis of Metallocene Catalyst>
3 g of silica having an average particle size of 11 μm (average particle size of 11 μm, surface area of 313 m ² /g, pore volume of 1.6 cm ³ /g) was filled in a cylindrical flask equipped with an induction stirrer and sufficiently replaced with nitrogen, 75 ml of toluene was added and heated to 75° C. with an oil bath. 8.0 ml of a toluene solution of methylaluminoxane (manufactured by Albemarle, 3.0 mol-Al/L) was placed in another flask. Dimethylsilylenebis[1,1′-{2-(2-(5-methyl)furyl)-4-(p-isopropylphenyl)-indenyl}]zirconium dichloride (63.4 mg, 75 μmol) in toluene solution (15 ml) was added to a toluene solution of methylalumoxane at room temperature, the temperature was raised to 75° C., and the mixture was stirred for 1 hour. Then, this toluene solution was added to a toluene slurry of silica heated to 75° C. with stirring and maintained for 1 hour. Then, 175 ml of n-hexane was added while stirring at 23° C. After 10 minutes, the stirring was stopped and the mixture was allowed to stand. After sufficiently settling the catalyst, the supernatant was removed and 200 ml of n-hexane was added. After stirring once, the mixture was allowed to stand again and the supernatant was removed. This operation was repeated three times to remove the components liberated in n-hexane. Further, the solvent was distilled off under reduced pressure while heating to 40°C. After the degree of pressure reduction became 0.8 mmHg or less, drying under reduced pressure was continued for 15 minutes to obtain a metallocene catalyst (i).
<Production of anti-fouling component>
In 100 mL of xylene, 3 g of n-octylated polyethyleneimine derived from polyethyleneimine (molecular weight 10,000) (0.5 n-octyl group per monomer unit of polyethyleneimine introduced) and phosphoric acid ester 1 g of the compound phytic acid was mixed and stirred at room temperature to form a salt. After that, 6 g of dioctylsulfosuccinate magnesium salt was mixed to obtain an anti-fouling component.

<Production of Ziegler-Natta catalyst>
A Ti-based catalyst obtained by a dissolution precipitation method was used as a solid catalyst component. The manufacturing method thereof is as follows.
After sufficiently purging the inside of a 1-liter three-necked flask equipped with a stirrer and a condenser with nitrogen, 250 ml of dry hexane and 11.4 g of anhydrous magnesium chloride that had previously been ground for 1 hour with a 3-liter vibration mill and n. 110 ml of -butanol was added and heated at 68° C. for 2 hours to form a homogeneous solution (1a).
After cooling this solution (1a) to room temperature, 8 g of methylpolysiloxane having a kinematic viscosity at 25° C. of 25 cSt was added and stirred for 1 hour to obtain a uniform solution (1b).
Next, after cooling solution (1b) with water, 50 ml of titanium tetrachloride and 50 ml of dry hexane were added dropwise thereto using a dropping funnel over 1 hour to obtain solution (1c). The solution (1c) was homogeneous and no reaction product complex was precipitated.
Heat treatment was performed at 68° C. for 2 hours while the solution (1c) was refluxed. Precipitation of the reaction product complex (1d) was observed about 30 minutes after the heating was started. This was collected, washed 6 times with 250 ml of dry hexane, and further dried with nitrogen gas to recover 19 g of the reaction product complex (1d).
Analysis of the reaction product complex (1d) revealed that it contained 14.5% by mass of Mg, 44.9% by mass of n-butanol and 0.3% by mass of Ti, and had a specific surface area of 17 m ² /g. .

Next, 4.5 g of the reaction product complex (1d) was taken in a 1-liter three-necked flask equipped with a stirrer and a condenser under a nitrogen atmosphere, and 250 ml of dry hexane and 25 ml of titanium tetrachloride were added thereto. After heat treatment at 68° C. for 2 hours under reflux and cooling to room temperature, the mixture was washed with 250 ml of dry hexane six times and dried with nitrogen gas to recover 4.6 g of solid catalyst component (1e).
Analysis of this solid catalyst component (1e) revealed that it contained 12.5% by mass of Mg, 17.0% by mass of n-butanol and 9.0% by mass of Ti, and had a specific surface area of 29 m ² /g. . When this solid catalyst component (1e) was observed by SEM, the particle size was uniform and the shape was almost spherical.

<Production of polyethylene component (A1)>
A polyethylene component (A1) was produced by carrying out ethylene/1-hexene copolymerization using the metallocene catalyst. That is, 115 L/h of dehydrated purified isobutane, 0.13 mol/h of triisobutylaluminum, and 6 ml/h of an anti-fouling component were supplied to a loop-type slurry reactor having an internal volume of 290 L, and the temperature in the reactor was set to 80°C. , while intermittently discharging from the reactor so as to maintain the pressure at 4.2 MPaG, ethylene, 1-hexene and hydrogen were supplied, and the molar ratio of 1-hexene and ethylene in the liquid during polymerization (C6/C2 ) was 0.010, and the molar ratio of hydrogen and ethylene (H2/C2) was adjusted to 3.4×10 ⁻⁴ . Next, a hexane slurry of the metallocene catalyst (i) diluted to 0.3 g/L with hexane was supplied to the reactor at 3 L/h to initiate polymerization, and the ethylene concentration in the reactor was adjusted to 10 vol%. was supplied with ethylene. The polyethylene produced was intermittently discharged together with the isobutane, flushed and sent to the product silo.
The HLMFR of the polyethylene component (A1) obtained at this time was 0.6 g/10 min, the density was 0.919 g/cm ³ , and the Mw/Mn was 3.1.

<Production of polyethylene component (A2)>
A polyethylene component (A2) was produced using a metallocene catalyst according to the method for producing the polyethylene component (A1). The polyethylene component (A2) had an HLMFR of 1.4 g/10 min, a density of 0.919 g/cm ³ and an Mw/Mn of 3.6.

<Production of polyethylene component (A3)>
A polyethylene component (A3) was produced according to the method for producing the polyethylene component (A1), using a chromium-based catalyst instead of the metallocene-based catalyst. The polyethylene component (A3) had an HLMFR of 5.0 g/10 minutes, a density of 0.941 g/cm ³ and an Mw/Mn of 6.7.

<Production of polyethylene component (A4)>
With reference to Example 7 of JP-A-2016-55871, the component (A-7) and component (B-7) of Example 7 are subjected to continuous multistage polymerization in that order, and the component of Example 7 ( A polyethylene component (A4) was produced in the same manner as in C-7). The polyethylene component (A4) had an HLMFR of 0.8 g/10 minutes, a density of 0.928 g/cm ³ and an Mw/Mn of 13.4.

<Production of polyethylene component (A5)>
A polyethylene component (A5) was produced in the same manner as the component (A1) of Example 7 with reference to Example 7 of JP-A-2017-186515. The polyethylene component (A5) had an HLMFR of 0.6 g/10 minutes, a density of 0.924 g/cm ³ and an Mw/Mn of 3.0.

<Production of polyethylene component (B1)>
0.94 g/hr of the solid catalyst component (1e) obtained in the production of the above Ziegler-Natta catalyst was added from the catalyst supply line to a liquid-filled loop-type first-stage reactor having an internal volume of 145 liters, and triisobutylaluminum (TIBAL ) was continuously supplied from the organometallic compound supply line at a rate of 0.2 mmol/hr, and while discharging the polymerization content at a required rate, dehydrated and purified isobutane was added at 110 (l/hr) at 80 ° C. ), hydrogen was supplied at a rate of 0.80 (g/hr) and ethylene was supplied at a rate of 5.0 (kg/hr). Stage polymerization was performed.
A part of the polymerization product in the first stage reactor was sampled, and a powdery polymer (polyethylene component (C)) was recovered. As a result of measuring the physical properties of the recovered polyethylene component (C), the HLMFR was 2 g/10 min and the density was 0.947 kg/m ³ .

The entire amount of the slurry polymerization product produced in the first-stage reactor is directly introduced into the second-stage reactor having an internal volume of 290 liters, and the contents of the polymerization vessel are discharged at a required rate without adding catalyst. , dehydrated and purified isobutane 60 (l / hr), hydrogen 14.2 (g / hr), ethylene 14.4 (kg / hr) at 90 ° C., total pressure 4.2 MPa, average retention The second-stage polymerization was continuously performed under the condition of 0.8 hours.
The polymerized product discharged from the second-stage reactor was introduced into the flushing tank, the polymerized product was continuously withdrawn, and unreacted gas was removed from the degassing line.
The results of evaluating the physical properties of the obtained polyethylene component (B1) are as shown in Table 1. The MFR was 7.6 g/10 min, the HLMFR was 571 g/10 min, the HLMFR/MFR ratio was 75, and the density was 0. .966 kg/m ³ and Mw/Mn was 17.2.
Moreover, the ratio of the polyethylene component (C) to the total polyethylene component (B1) was 25% by mass.
Further, the physical property values of the polyethylene component (D) obtained in the second stage polymerization are calculated based on the addition rule from the physical property values of the polyethylene component (B1) and the physical property values of the polyethylene component (C), and the MFR is 300 g. /10 min, the density was 0.969 g/cm ³ , and the ratio of the polyethylene component (D) to the total polyethylene component (B1) was 75% by mass.

<Production of polyethylene components (B2) to (B4)>
In the production of the polyethylene component (B1), except that the conditions for the amount of ethylene as the main raw material and the amount of hydrogen as the chain transfer agent were changed so as to obtain the polymer shown in Table 1, the production of the polyethylene component (B1) and the Polyethylene components (B2) to (B4) were obtained in the same manner.

<Production of polyethylene component (B5)>
A polyethylene component (B5) was produced in the same manner as the component (D-7) of Example 7 with reference to Example 7 of JP-A-2016-55871. The polyethylene component (B5) had an MFR of 200 g/10 minutes, a density of 0.969 g/cm ³ and an Mw/Mn of 13.4.

<Production of polyethylene component (B6)>
A polyethylene component (B6) was produced in the same manner as the component (B7) of Example 7 with reference to Example 7 of JP-A-2017-186515. The polyethylene component (B6) had an MFR of 2.12 g/10 minutes, an HLMFR of 31.9 g/10 minutes, a density of 0.964 g/cm ³ and an Mw/Mn of 14.9.

[Example 1]
<Production of polyethylene resin composition>
1,000 ppm of IRGANOX B225 manufactured by BASF Japan Co., Ltd. and 500 ppm of calcium stearate manufactured by Tannan Kagaku Kogyo Co., Ltd. are blended as additives in the composition having the blending ratio described in Example 1 in Table 1, manufactured by Toshiba Machine Co., Ltd. Pelletization was performed using a TEM26SX (screw diameter: 26 mm, L/D = 64) under conditions of set temperature: 200°C, screw rotation speed: 200 rpm, and discharge rate: 15 kg/hr.
Table 1 shows the physical properties and evaluation results of the polyethylene resin composition. The obtained composition has good compatibility of each component, has excellent hollow moldability due to appropriate fluidity and high melt tension, and has a long breaking time, high tensile impact strength, and good appearance of the molded product. was good.

[Examples 2-3, Comparative Examples 1-4]
A polyethylene resin composition was produced in the same manner as in Example 1, except that the conditions were set so that the composition shown in Table 1 was obtained. Table 1 shows the physical properties and evaluation results of the obtained polyethylene resin composition.

FIG. 3 is a graph showing the relationship between the density (d) of the polyethylene resin compositions of Examples and Comparative Examples and the rupture time (FNCT) of the full circumference notch type creep test.
FIG. 4 is a diagram showing the relationship between the HLMFR of the polyethylene resin compositions of Examples and Comparative Examples and the rupture time (FNCT) in a full-circumference notch creep test.
FIG. 5 is a graph showing the relationship between density (d) and tensile impact strength (TIS) of polyethylene resin compositions of Examples and Comparative Examples.
FIG. 6 is a diagram showing the relationship between HLMFR and tensile impact strength (TIS) of polyethylene resin compositions of Examples and Comparative Examples.
FIG. 7 is a diagram showing the relationship between HLMFR and melt tension (MT) of polyethylene resin compositions of Examples and Comparative Examples.

The polyethylene resin compositions of Examples 1 to 3 had an excellent balance of hollow moldability, rigidity of the molded body, environmental stress crack resistance, and impact resistance, and the heat generation of the resin was suppressed during the extrusion process. It was possible to shorten the cycle.

On the other hand, the polyethylene resin composition of Comparative Example 1, which did not satisfy the properties (3) and (5), was one in which resin heat generation was suppressed during the extrusion process. It was of poor quality.
The polyethylene resin composition of Comparative Example 2, which did not satisfy the properties (1), (2), (3), and (5), had poor impact resistance and environmental stress crack resistance of the molded article, and Resin heat generation was likely to occur.
In the polyethylene resin composition of Comparative Example 3, which did not satisfy the characteristic (5), the resin heat generation was suppressed during the extrusion process, but the impact resistance and environmental stress crack resistance of the molded product were inferior. .
The polyethylene resin composition of Comparative Example 4, which did not satisfy the properties (1), (2), and (5), was inferior in environmental stress crack resistance of the molded article, and resin heat generation was likely to occur during the extrusion process. .

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a polyethylene resin composition that has an excellent balance of rigidity, environmental stress crack resistance, and impact resistance of a molded article, and that suppresses heat generation of the resin during an extrusion process, and a molded article using the same. .
Furthermore, the polyethylene resin composition of the present invention exhibits excellent high flowability during molding, and the molded article of the present invention exhibits excellent rigidity, environmental stress crack resistance, impact resistance, and the like.
Therefore, the polyethylene resin composition of the present invention and its molded article are suitable for applications such as containers that require such properties, and are particularly suitable for cosmetic containers, containers for detergents, shampoos and conditioners, or edible oils, etc., which are excellent in appearance. It can be suitably used for applications such as food containers.
Furthermore, the container using the polyethylene resin composition of the present invention can shorten the molding cycle at the time of production, has excellent product characteristics, and is economically advantageous for cosmetics, detergents, shampoos, conditioners, etc. It is suitable as a container for
In addition, since the polyethylene resin composition of the present invention has excellent performance as described above, it can be suitably used for kerosene cans, chemical containers, etc., which require such characteristics, in addition to the containers described above. Since it can be done, it is industrially very useful.

Claims (8)

One or more ethylene-based polymers selected from the group consisting of ethylene homopolymers and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms are included as essential components, and have the following characteristics (1 ) to a polyethylene resin composition satisfying (5).
Characteristic (1): The melt flow rate (MFR) measured at a temperature of 190° C. and a load of 2.16 kg is 0.5 g/10 minutes or more and 5 g/10 minutes or less.
Characteristic (2): The melt flow rate (HLMFR) at a temperature of 190°C and a load of 21.6 kg is more than 50 g/10 minutes and not more than 100 g/10 minutes.
Characteristic (3): The melt flow rate ratio (HLMFR/MFR), which is the ratio of HLMFR to MFR, is 40 or more and 100 or less.
Characteristic (4): Density is 0.950 g/cm ³ or more and 0.970 g/cm ³ or less.
Characteristic (5): The rupture time (FNCT) (unit: hours) and density (d) (unit: g/cm ³ ) in a full-circumference notch creep test performed in accordance with ISO DIS 16770 are expressed by the following formula (1). satisfies the relationship shown by
FNCT≧5.5×10 ⁻⁵ ×d ⁻³²⁴ Expression (1) The polyethylene resin composition according to claim 1, further satisfying the following property (6).
Property (6): Tensile impact strength (TIS) (unit: kJ/m ² ) at 23° C. and density (d) (unit: g/cm ³ ) satisfy the relationship represented by the following formula (2).
TIS≧−22000×d+21184 Expression (2) 3. The polyethylene resin composition according to claim 1, which further satisfies the following property (7).
Property (7): Melt tension (MT) (unit: mN) measured at 190° C. and HLMFR (unit: g/10 min) satisfy the relationship represented by the following formula (3).
MT≧334.85×HLMFR− ^0.635 Expression (3) The polyethylene resin composition according to any one of claims 1 to 3, which contains 10% by mass or more and 30% by mass or less of the following polyethylene component (A) and 70% by mass or more and 90% by mass or less of the following polyethylene component (B). thing.
Polyethylene component (A); property (a1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (a2): density is 0.915 g/cm ³ or more and 0.940 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (B); property (b1): MFR is 0.1 g/10 min or more and 10 g/10 min or less; property (b2): density is 0.950 g/cm ³ or more and 0.980 g/cm ³ or less Characteristic (b3): HLMFR is 1 g/10 min or more and 1000 g/10 min or less; Characteristic (b4): 10% by mass or more and 50% by mass or less of polyethylene component (C) below; ) in an amount of 50% by mass or more and 90% by mass or less.
Polyethylene component (C); property (c1): HLMFR is 0.5 g/10 min or more and 5 g/10 min or less; property (c2): density is 0.900 g/cm ³ or more and 0.950 g/cm ³ or less Ethylene-based polymer.
Polyethylene component (D); property (d1): MFR is 10 g/10 min or more and 400 g/10 min or less; property (d2): density is 0.900 g/cm ³ or more and 0.980 g/cm ³ or less Ethylene polymer. The molecular weight distribution represented by the ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 5 to 25. 5. The polyethylene resin composition according to any one of 4. An extruder equipped with a screw having a screw diameter (Ds) of 70 mm, a ratio (Ls/Ds) of the effective length of the screw (Ls) and the screw diameter (Ds) of 24, and a compression ratio of 3.0 in the cylinder. With a die of 14 mm and an inner diameter of 10.5 mm attached, the temperature of the resin at the die exit when the set temperature of the cylinder and die is 185 ° C. and the screw rotation speed is adjusted to an extrusion rate of 70 kg / hour is the contact resin temperature. The polyethylene resin composition according to any one of claims 1 to 5, wherein the resin temperature is 235°C or less when measured with a meter. A molded article comprising the polyethylene resin composition according to any one of claims 1 to 6. A container having a layer containing the polyethylene resin composition according to any one of claims 1 to 6.

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