JP6950566B2 - Polyethylene resin composition for cross-linked polyethylene pipe and cross-linked polyethylene pipe - Google Patents

Description

The present invention relates to a polyethylene resin composition for a cross-linked polyethylene pipe and a cross-linked polyethylene pipe containing the polyethylene resin composition. More specifically, the present invention has excellent creep performance (strength) at high temperature, is easy to install, and has good cross-linking efficiency. The present invention relates to a polyethylene resin composition for a crosslinked polyethylene tube having good moldability and surface smoothness, and a crosslinked polyethylene tube containing the polyethylene resin composition.

In recent years, plastics having excellent corrosion resistance and workability as compared with conventional metal materials have been used as piping materials. Among these, cross-linked polyethylene pipes using cross-linked polyethylene, which is particularly excellent in pressure resistance and creep resistance in a high temperature region, are often used.
Cross-linked polyethylene pipes are used for hot water supply pipes and hot water pipes for floor heating because they have better "strength under high temperature (high temperature creep performance)" than ordinary polyethylene pipes.

For example, Patent Document 1 discloses a technique for providing a cross-linked polyethylene pipe that can be used for a floor heating pipe, a hot water supply pipe, or the like having excellent pressure-resistant creep performance, flexibility, and the like.
Further, Patent Document 2 discloses a technique for providing a cross-linked polyethylene pipe exhibiting high pressure resistance without lowering pipe workability and productivity.

Japanese Unexamined Patent Publication No. 2003-074753 Japanese Unexamined Patent Publication No. 2009-120846

At present, high temperature (about 80 ° C.) heat pump units equipped with hot water storage units for home use are becoming widespread, the creep performance level required for hot water supply pipes is increasing, and pipes that can withstand the use of high temperature water for a long period of time are required.
On the other hand, the heat pump unit is required to be more compact, and there is a deep-rooted need for ease of handling of the pipe in order to increase the degree of freedom in the shape of the pump unit.
From these facts, there are great expectations for the improvement of creep performance of cross-linked polyethylene pipes that are easy to handle and install.
In view of the situation of the prior art, the present application is a polyethylene resin composition for cross-linked polyethylene pipe, which has excellent creep performance (strength) at high temperature, is easy to install, has good cross-linking efficiency, and has good formability and surface smoothness. An object of the present invention is to provide a cross-linked polyethylene pipe containing the polyethylene resin composition.

The polyethylene resin composition for cross-linked polyethylene pipe of the present invention is characterized by satisfying the following properties (1) to (3).
Characteristics (1): The melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg is 35 to 150 g / 10 minutes.
Characteristics (2): density exceeds 0.943 g / cm ^3, is 0.955 g / cm ³ or less.
Property (3): 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 9 to 25.

In the polyethylene resin composition for crosslinked polyethylene pipes of the present invention, the polyethylene resin composition has one or more ethylene-based weights having a higher density than the ethylene-based copolymer (A) and the ethylene-based copolymer (A). Contains the polyethylene-based polymer (B) containing a coalescing component,
The ethylene-based copolymer (A) is a copolymer of ethylene polymerized using a metallocene catalyst and an α-olefin having 3 to 20 carbon atoms, and has an HLMFR (A) of 0.2 to 1. ^{The density (A) is 0.915 to 0.930 g / cm 3} at 5 g / 10 minutes, and the density (A) is 0.915 to 0.930 g / cm 3.
The polyethylene resin composition contains 15 parts of the ethylene-based copolymer (A) per 100 parts by mass of the ethylene-based copolymer (A) and the ethylene-based polymer (B) in the polyethylene resin composition. It may contain ~ 40 parts by mass.

In the polyethylene resin composition for cross-linked polyethylene pipe of the present invention, the ethylene-based copolymer (A) may be polymerized using a metallocene catalyst having a cyclopentadienyl ring and a heterocyclic aromatic group.

In the polyethylene resin composition for a crosslinked polyethylene pipe of the present invention, the ethylene-based polymer (A) and the ethylene-based polymer (B) are contained in the polyethylene resin composition in a total amount of 100 parts by mass. B) contains 60 to 85 parts by mass,
The ethylene-based polymer (B) is at least one of an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and is melted at a temperature of 190 ° C. and a load of 2.16 kg. The flow rate (MFR (B)) may be 1 to 100 g / 10 minutes and the density (B) may be 0.946 to 0.975 g / cm ³ .

The cross-linked polyethylene pipe of the present invention contains the polyethylene resin composition and contains the polyethylene resin composition.
It is characterized in that the rupture time in a high temperature tensile creep test (80 ° C., load 3.5 kg) on a cross-linked polyethylene sheet exceeds 1000 hours.

According to the present invention, a polyethylene resin composition for cross-linked polyethylene pipe, which has excellent creep performance (strength) at high temperature, is easy to install, has good cross-linking efficiency, and has good formability and surface smoothness, and the polyethylene resin. A cross-linked polyethylene tube containing the composition can be provided.

1. 1. Polyethylene resin composition for cross-linked polyethylene pipe The polyethylene resin composition for cross-linked polyethylene pipe of the present invention is characterized by satisfying the following characteristics (1) to (3).
Characteristics (1): The melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg is 35 to 150 g / 10 minutes.
Characteristics (2): density exceeds 0.943 g / cm ^3, is 0.955 g / cm ³ or less.
Property (3): 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 9 to 25.

The polyethylene resin composition for cross-linked polyethylene pipes of the present invention is particularly excellent in long-term pressure resistance at high temperatures in order to satisfy the above characteristics, and is used, for example, for polyethylene pipes that can be used for hot water pipes for floor heating and hot water supply pipes. Can be done.
Further, the polyethylene resin composition for cross-linked polyethylene pipe of the present invention exhibits excellent productivity in extrusion molding due to the above characteristics.
Specifically, in extrusion molding, there is an effect that the extrusion load is low and the surface smoothness is excellent.
That is, the polyethylene resin composition for cross-linked polyethylene pipe of the present invention is particularly excellent in long-term pressure resistance at high temperature, and has an economically effective point in extrusion molding.
Hereinafter, the polyethylene resin composition for cross-linked polyethylene pipes of the present invention and the like will be described in detail for each item. In addition, in this specification, "~" indicating a numerical range is used in the meaning of including the numerical values described before and after it as a lower limit value and an upper limit value.

1-1. Characteristic (1): HLMFR
In the polyethylene resin composition for cross-linked polyethylene pipe of the present invention, the melt flow rate (HLMFR) of the characteristic (1) at a temperature of 190 ° C. and a load of 21.6 kg is 35 to 150 g / 10 minutes, preferably 36 to 140 g / 10. Minutes.
When HLMFR is 35 g / 10 minutes or more, the molecular weight is lowered, the fluidity is improved, and the moldability is improved. Further, when the HLMFR is 150 g / 10 minutes or less, the long-term durability is improved.

In the present specification, HLMFR is a value measured according to JIS K6922-2: 1997.
The HLMFR can be adjusted by adjusting the ethylene polymerization temperature, the use of a chain transfer agent, etc. in the production of the polyethylene resin composition, and a desired one can be obtained.
That is, for example, the HLMFR can be increased as a result of lowering the molecular weight by raising the polymerization temperature of ethylene and α-olefin, and the HLMFR can be lowered as a result of raising the molecular weight by lowering the polymerization temperature. can do.
Further, in the copolymerization reaction of ethylene and α-olefin, by increasing the amount of hydrogen coexisting (the amount of chain transfer agent), the HLMFR can be increased as a result of lowering the molecular weight, and the amount of hydrogen coexisting (the amount of hydrogen coexisting). By reducing the amount of chain transfer agent), the HLMFR can be reduced as a result of increasing the molecular weight.
Further, the HLMFR can be adjusted by the MFR or HLMFR of the ethylene-based copolymer (A) and the ethylene-based polymer (B) to be combined, which will be described later, and the composition ratio.

1-2. Characteristics (2): In the crosslinked polyethylene pipe polyethylene resin composition of the Density present invention, the density of characteristic (2), beyond the 0.943 g / cm ^3, and a 0.955 g / cm ³ or less, preferably 0.944 It is ~ 0.954 g / cm ³ , more preferably 0.944 to 0.953 g / cm ³ .
When the present density ^{exceeds 0.943 g / cm 3} , the flexural modulus is improved, and as a result, the rigidity of the material is improved and the pressure resistance is improved. On the other hand, when the density is 0.955 g / cm ³ or less, long-term durability and flexibility are improved.

In the present specification, the densities of the polyethylene resin composition, the ethylene-based copolymer (A), the ethylene-based polymer (B) and the like are values measured according to JIS K6922-1, 2: 1997.
The desired density can be obtained, for example, by changing the type and amount of the comonomer to be copolymerized with ethylene. Further, it can be adjusted by the density and composition ratio of the ethylene-based copolymer (A) and the ethylene-based polymer (B) to be combined.

1-3. Characteristic (3): Mw / Mn
In the polyethylene resin composition of the present invention, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of the characteristic (3) is 9 to 9. It is 25, preferably 9 to 23. When Mw / Mn is 9 or more, the durability of the molded product is improved. On the other hand, when Mw / Mn is 25 or less, impact resistance, stress crack resistance and the like are improved.

In the present specification, Mw / Mn of the polyethylene resin composition refers to a value calculated from the weight average molecular weight Mw measured by GPC and the number average molecular weight Mn.
Mw / Mn can be achieved mainly by selecting the polymerization catalyst and the polymerization conditions. Further, it can be adjusted by the Mw / Mn and the composition ratio of the ethylene-based copolymer (A) and the ethylene-based polymer (B) to be combined.

The measurement of the molecular weight (weight average molecular weight Mw) by gel permeation chromatography (GPC) can be performed by the following method.
That is, it can be measured by gel permeation chromatography (GPC) under the following conditions.
Equipment: 150C manufactured by WATERS
Column: 3 AD80M / S manufactured by Showa Denko Co., Ltd. Measurement temperature: 140 ° C
Concentration: 1 mg / 1 ml
Solvent: o-dichlorobenzene The molecular weight is calculated and the column is calibrated according to the following method.
GPC chromatographic data is taken into a computer at a frequency of 1 point / sec, and the data is processed according to the description in Chapter 4 of "Size Exclusion Chromatography" written by Sadao Mori and published by Kyoritsu Publishing Co., Ltd., and the Mw value is calculated.
The column was calibrated by Showa Denko's monodisperse polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28. A series of monodisperse polystyrene measurements were performed using 0.2 mg / ml solutions of each of .5, S-5.05), n-eicosan and n-tetracontane, and the log of their elution peak times and molecular weights. The calibration curve is obtained by fitting the relationship with a fourth-order polypoly.
The molecular weight of polystyrene (MPS) is converted to the molecular weight of polyethylene (MPE) using the following formula. MPE = 0.468 x MPS

1-4. Ethylene copolymer (A)
Since the polyethylene resin composition of the present invention is easy to prepare the polyethylene resin composition of the present invention and is a preferable polyethylene resin composition for a crosslinked polyethylene tube, it is polymerized using a metallocene catalyst, preferably Ti, Zr or Hf. It is polymerized using the contained metallocene catalyst, and contains an ethylene-based copolymer (A) having an HLMFR of 0.2 to 1.5 g / 10 minutes and a density of 0.915 to 0.930 g / cm ^3. It is preferable that the product is polymerized.

The HLMFR (A) of the ethylene-based copolymer (A) is 0.2 g / 10 minutes or more, 1.5 g / 10 minutes or less, preferably 0.3 to 1.5 g / 10 minutes, and more preferably 0.5. The range is ~ 1.5 g / 10 minutes.
When the HLMFR (A) is 0.2 g / 10 minutes or more, the HLMFR can be achieved within the specified range in the final polyethylene resin composition, and the fluidity is improved.
On the other hand, when the HLMFR (A) is 1.5 g / 10 minutes or less, the long-term durability is improved in the final polyethylene resin composition.
The HLMFR (A) can be adjusted by adjusting the ethylene polymerization temperature, the use of a chain transfer agent, etc. in the production of the ethylene-based copolymer (A), and a desired one can be obtained.
That is, for example, HLMFR (A) can be increased as a result of lowering the molecular weight by raising the polymerization temperature of ethylene and α-olefin, and as a result of raising the molecular weight by lowering the polymerization temperature, HLMFR (A) can be reduced.
Further, in the copolymerization reaction of ethylene and α-olefin, by increasing the amount of hydrogen to coexist (the amount of chain transfer agent), as a result of lowering the molecular weight, HLMFR (A) can be increased and coexist. By reducing the amount of hydrogen (the amount of chain transfer agent), the HLMFR (A) can be reduced as a result of increasing the molecular weight.

The density (A) of the ethylene-based copolymer (A) is 0.915 to 0.930 g / cm ³ , preferably 0.920 to 0.930 g / cm ³ , and more preferably 0.923 to 0. It is 930 g / cm ³ .
When the density (A) is 0.915 g / cm ³ or more, the density range in the final polyethylene resin composition can be achieved, the flexural modulus is improved, and as a result, the rigidity of the material is improved and the pressure resistance is improved. ..
On the other hand, when the density (A) is 0.930 g / cm ³ or less, the long-term durability of the final polyethylene resin composition is improved.
A desired density (A) can be obtained, for example, by changing the density (A) depending on the type and amount of the comonomer to be copolymerized with ethylene.

The ethylene-based copolymer (A) is preferably polymerized with a metallocene catalyst, more preferably a metallocene catalyst containing Ti, Zr or Hf.
Examples of the metallocene catalyst include a combination of a complex in which a ligand having a cyclopentadiene skeleton is coordinated to a transition metal and a co-catalyst.
Specific metallocene catalysts include a complex catalyst in which a transition metal containing Ti, Zr, Hf, etc. is coordinated with a ligand having a cyclopentadiene skeleton such as methylcyclopentadiene, dimethylcyclopentadiene, and inden. As a catalyst, a combination of organic metal compounds of Group 1 to Group 3 elements in a long periodic table (hereinafter, simply referred to as "periodic table") such as aluminoxane, or a complex catalyst of these compounds such as silica is used. Examples thereof include a carrying type supported on a carrier.

The metallocene catalyst used in the present invention contains the following catalyst component (A) and catalyst component (B), and is a catalyst formed in combination with the catalyst component (C) as needed.
Catalyst component (A): metallocene compound Catalyst component (B): a compound that reacts with the catalyst component (A) to form a cationic metallocene compound Catalyst component (C): fine particle carrier

(1) Catalyst component (A)
As the catalyst component (A), a metallocene compound of a transition metal of Group 4 of the periodic table is used. Specifically, compounds represented by the following general formulas (I) to (VI) are used.
(C ₅ H _5-a R ¹ _a ) (C ₅ H _5-b R ² _b ) MXY (I)
Q (C ₅ H _4-c R ¹ _c ) (C ₅ H _4-d R ² _d ) MXY (II)
Q'(C ₅ H _4-e R ³ _e ) ZMXY (III)
(C ₅ H _5-f R ³ _f ) ZMXY (IV)
(C ₅ H _5-f R ³ _f ) MXYW (V)
Q "(C ₅ H _5-g R ⁴ _g ) (C ₅ H _5-h R ⁵ _h ) MXY (VI)

Here, Q indicates a binding group that bridges two conjugated five-membered ring ligands, Q'indicates a binding group that bridges a conjugated five-membered ring ligand and a Z group, and Q'is. represents a binding group which crosslinks the ^{R 4} and ^{R 5,} M is, Ti, shows the Zr or Hf, X, Y and W are each independently hydrogen atom, a halogen atom, having 1 to 20 carbon atoms Hydrocarbon groups, oxygen-containing hydrocarbon groups with 1 to 20 carbon atoms, nitrogen-containing hydrocarbon groups with 1 to 20 carbon atoms, phosphorus-containing hydrocarbon groups with 1 to 20 carbon atoms, or silicon-containing hydrocarbon groups with 1 to 20 carbon atoms Indicates a group, where Z is an oxygen atom, a ligand containing a sulfur atom, 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 group having 1 to 40 carbon atoms. Indicates a hydrocarbon group.

R ^{1 to} R ⁵ are independently each of 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, and an oxygen-containing hydrocarbon group. Indicates a sulfur-containing hydrocarbon group, a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, or a boron-containing hydrocarbon group. Further, form two of ^R 1 adjacent, two ^R 2, two ^R 3, two ^{R 4,} or two ^{R 5,} bonded to each of several 4 to 10 carbon ring You may be doing it. Further, a, b, c, d, e, f, g and h are 0 ≦ a ≦ 5, 0 ≦ b ≦ 5, 0 ≦ c ≦ 4, 0 ≦ d ≦ 4, 0 ≦ e ≦ 4, respectively. It is an integer that satisfies 0 ≦ f ≦ 5, 0 ≦ g ≦ 5, and 0 ≦ h ≦ 5.

Binding group Q which bridges the two conjugated five-membered cyclic ligands, bonding group bridging the conjugated five-membered ring ligands and Z group Q ', and, bridging the R ⁴ and R ⁵ Specific examples of "Q" include the following.
That is, an alkylene group such as a methylene group and an ethylene group, an ethylidene group, a propylidene group, an isopropylidene group, a phenylmethylidene group and an alkylidene group such as a diphenylmethylidene group, a dimethylsilylene group, a diethylsilylene group and a dipropylsilylene group. , Diphenyl silylene group, methyl ethyl silylene group, methylphenyl silylene group, methyl-t-butyl silylene group, disylylene group, silicon-containing cross-linking group such as tetramethyl disylylene group, germanium-containing cross-linking group, alkylphosphine, amine, etc. Is. Of 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) or (VI) are exemplified below, but Zr is replaced with Hf or Ti. Compounds can be used in the same manner.
Further, the catalyst component (A) represented by the general formulas (I), (II), (III), (IV), (V) or (VI) is a compound represented by the same general formula or a different general formula. It can be used as a mixture of two or more compounds represented by.

Compound of general formula (I):
Biscyclopentadienyl zirconium dichloride,
Bis (2-methylindenyl) zirconium dichloride,
Bis (2-methyl-4,5 benzoindenyl) zirconium dichloride,
Bisfluolenyl zirconium dichloride,
Bis (4H-azurenyl) zirconium dichloride,
Bis (2-methyl-4H-azurenyl) cyclopentadienyl zirconium dichloride,
Bis (2-methyl-4-phenyl-4H-azurenyl) zirconium dichloride,
Bis (2-methyl-4- (4-chlorophenyl) -4H-azurenyl) zirconium dichloride,
Bis (2-furylcyclopentadienyl) zirconium dichloride,
Bis (2-frilled indenyl) zirconium dichloride,
Bis (2-furyl-4,5-benzoindenyl) zirconium dichloride and the like can be exemplified.

Compound of general formula (II):
Dimethylsilylenebis (1,1'-cyclopentadienyl) zirconium dichloride, dimethylsilylenebis [1,1'-(2-methylindenyl)] zirconium dichloride, ethylenebis [1,1'-(2-methyl-) 4,5 benzoindenyl)] zirconium dichloride,
Dimethylsilylenebis [1,1'-(2-methyl-4-hydroazurenyl)] zirconium dichloride,
Dimethylsilylenebis [1,1'-(2-methyl-4-phenyl-4-hydroazurenyl)] zirconium dichloride,
Dimethylsilylenebis {1,1'-[2-methyl-4- (4-chlorophenyl) -4-hydroazurenyl]} zirconium dichloride,
Dimethylsilylenebis [1,1'-(2-ethyl-4-phenyl-4-hydroazurenyl)] zirconium dichloride,
Ethylenebis [1,1'-(2-methyl-4-hydroazurenyl)] zirconium dichloride,
Dimethylsilylenebis [1,1'-(2-furylcyclopentadienyl)] zirconium dichloride,
Dimethylsilylenebis {1,1'-[2- (2-furyl) -4,5-dimethyl-cyclopentadienyl]} zirconium dichloride,
Dimethylsilylenebis {1,1'-{2- [2- (5-trimethylsilyl) frills] -4,5-dimethyl-cyclopentadienyl} zirconium dichloride,
Dimethylsilylenebis {1,1'-[2- (2-furyl) indenyl]} zirconium dichloride,
Dimethylsilylenebis {1,1'-[2- (2-furyl) -4-phenyl-indenyl]} zirconium dichloride,
Isopropylidene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride,
Isopropylidene (cyclopentadienyl) [9- (2,7-t-butyl) fluorenyl] zirconium dichloride,
Diphenylmethylene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride,
Diphenylmethylene (cyclopentadienyl) [9- (2,7-t-butyl) fluorenyl] zirconium dichloride,
Dimethylsilylene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride,
Examples thereof include diphenylcilylene (cyclopentadienyl) [9- (2,7-t-butyl) fluorenyl] zirconium dichloride.

Compound of general formula (III):
(Tertiary Butyramide) (Tetramethyl-η ⁵ -Cyclopentadienyl) -1,2-Ethandiyl Zirconium Dichloride,
(Methylamide)-(tetramethyl-η ⁵ -cyclopentadienyl) -1,2-ethanediyl-zirconium dichloride,
(Ethylamide) (Tetramethyl-η ⁵ -Cyclopentadienyl) -Methylene Zirconium Dichloride,
(Tertiary Butyramide) Dimethyl- (Tetramethyl-η ⁵ -Cyclopentadienyl) Silanezirconium Dichloride,
(Tertiary Butyramide) Dimethyl (Tetramethyl-η ⁵ -Cyclopentadienyl) Silanezirconium Dibenzyl,
(Benzylamide) Dimethyl (Tetramethyl-η ⁵ -Cyclopentadienyl) Silanezirconium Dichloride,
(Fenylphosphide) dimethyl (tetramethyl-η ⁵ -cyclopentadienyl) silanezirconium dibenzyl and the like can be exemplified.

Compound of general formula (IV):
(Cyclopentadienyl) (phenoxy) zirconium dichloride,
(2,3-dimethylcyclopentadienyl) (phenoxy) zirconium dichloride,
(Pentamethylcyclopentadienyl) (phenoxy) zirconium dichloride,
(Cyclopentadienyl) (2,6-di-t-butylphenoxy) zirconium dichloride,
(Pentamethylcyclopentadienyl) (2,6-di-i-propylphenoxy) zirconium dichloride and the like can be exemplified.

Compound of general formula (V):
(Cyclopentadienyl) Zirconium trichloride,
(2,3-Dimethylcyclopentadienyl) Zirconium trichloride,
(Pentamethylcyclopentadienyl) Zirconium trichloride,
(Cyclopentadienyl) Zirconium triisopropoxide,
(Pentamethylcyclopentadienyl) Zirconium triisopropoxide and the like can be exemplified.

Compounds of general formula (VI):
Ethylene bis (7,7'-indenyl) zirconium dichloride,
Dimethylsilylenebis {7,7'-(1-methyl-3-phenylindenyl)} zirconium dichloride,
Dimethylsilylenebis {7,7'-[1-methyl-4- (1-naphthyl) indenyl]} zirconium dichloride,
Dimethylsilylenebis [7,7'-(1-ethyl-3-phenylindenyl)] zirconium dichloride,
Examples thereof include dimethylsilylenebis {7,7'-[1-isopropyl-3- (4-chlorophenyl) indenyl]} zirconium dichloride.

In addition, a compound in which the silylene group of the compounds of these specific examples is replaced with a gelmilene group is also exemplified as a suitable compound.
Among the catalyst components (A) described above, the metallocene complex represented by the general formula (I) or the general formula (II) is a preferable metallocene complex for producing the ethylene-based copolymer (A). Preferably, the metallocene complex represented by the general formula (II) is preferable from the viewpoint that a high-molecular-weight polymer can be produced and the copolymerization property of ethylene and other α-olefins is excellent.
One method for satisfying the characteristics of the polyethylene resin composition of the present invention is to introduce a long-chain branch into an ethylene-based copolymer, but it is said that polyethylene having a high molecular weight and a long-chain branch can be produced. From the viewpoint, among the metallocene complexes represented by the general formula (II), the following two compound groups are preferable.

In a preferred embodiment, the first compound group is a crosslinked metallocene complex containing at least one heterocyclic aromatic group in the compound as ^{R 1 to} R ^2.
Preferred heterocyclic aromatic groups include a group consisting of a frill group, a benzofuryl group, a thienyl group and a benzothienyl group.
These substituents may further have a substituent such as a silicon-containing group.
Among the substituents selected from the group consisting of a frill group, a benzofuryl group, a thienyl group and a benzothienyl group, a frill group and a benzofuryl group are more preferable.
Furthermore, these substituents are preferably introduced at the 2-position of the substituted cyclopentadienyl group or the substituted indenyl group, and at least one substituted cyclopentadienyl group having no fused ring structure is used. It is particularly preferable that the compound has.

The second group of compounds is a crosslinked metallocene complex that combines a substituted cyclopentadienyl group and a substituted fluorenyl group.

These metallocene complexes are preferably used as a supporting catalyst as described later.
In the first compound group, the frill group causes heterogeneity in the active point structure due to the interaction between the so-called heteroatom contained in the thienyl group and the solid acid on the carrier, and long-chain branching is likely to occur. I think it was.
Also, in the second compound group, it is considered that the space around the active site is changed by using the supported catalyst, so that long-chain branching is easily generated.

(2) Catalyst component (B)
In the method for producing the ethylene-based copolymer (A) according to the present invention, as an essential component of the catalyst for olefin polymerization, in addition to the catalyst component (A), the metallocene compound of the catalyst component (A) (hereinafter, "component (A)" ) ”Or simply“ A ”) to form a cationic metallocene compound (catalyst component (B), hereinafter also simply referred to as“ B ”), as required. It is characterized by containing a fine particle carrier (catalyst component (C), hereinafter, may be simply referred to as “C”).

An organoaluminum oxy compound can be mentioned as one of the catalyst components (B) that reacts with the catalyst component (A) to form a cationic metallocene compound.
The organoaluminum oxy compound has an Al—O—Al bond in the molecule, and the number of the bonds is usually in the range of 1 to 100, preferably 1 to 50. Such an organoaluminum oxy compound is usually a product obtained by reacting an organoaluminum compound with water.
The reaction between organoaluminum and water is usually carried out in an inert hydrocarbon (solvent). As the inert hydrocarbon, aliphatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene and xylene, alicyclic hydrocarbons and aromatic hydrocarbons can be used, but aliphatic hydrocarbons or It is preferable to use aromatic hydrocarbons.

As the organoaluminum compound used for preparing the organoaluminum oxy compound, any compound represented by the following general formula (a) can be used, but trialkylaluminum is preferably used.
R ⁵ _t AlX ³ _3-t (a)
(In the formula, R ⁵ represents a hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, an alkenyl group, an aryl group, an aralkyl group, etc., and X ³ represents a hydrogen atom or a halogen atom. , T represents an integer of 1 ≦ t ≦ 3.)

The alkyl group of trialkylaluminum may be any of a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group and the like, but a methyl group. Is particularly preferable.
Two or more kinds of the above-mentioned organoaluminum compounds can be mixed and used.

The reaction ratio (water / Al molar ratio) of water to the organoaluminum compound is preferably 0.25 / 1 to 1.2 / 1, particularly 0.5 / 1-1 / 1, and the reaction temperature is , Usually in the range of −70 to 100 ° C., preferably in the range of −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 and the like, and components capable of producing water in the reaction system can be used.
Among the above-mentioned organoaluminum oxy compounds, those obtained by reacting alkylaluminum with water are usually called aluminoxane, and in particular, methylaluminoxane (including those substantially composed of methylaluminoxane (MAO)). Is suitable as an organoaluminum oxy compound.
As the organoaluminum oxy compound, two or more kinds of the above-mentioned organoaluminum oxy compounds can be used in combination, and the above-mentioned organoaluminum oxy compound is used as a solution or a solution in which the above-mentioned inert hydrocarbon solvent is used. You may use the thing.

Further, as another specific example of the catalyst component (B), a borane compound and a borate compound can be mentioned.
More specifically, the above borane compounds are triphenylborane, tri (o-tolyl) borane, tri (p-tolyl) borane, tri (m-tolyl) borane, tri (o-fluorophenyl) borane, tris ( p-fluorophenyl) borane, tris (m-fluorophenyl) borane, tris (2,5-difluorophenyl) borane, tris (3,5-difluorophenyl) borane, tris (4-trifluoromethylphenyl) borane, tris (3,5-ditrifluoromethylphenyl) borane, tris (2,6-ditrifluoromethylphenyl) borane, tris (pentafluorophenyl) borane, tris (perfluoronaphthyl) borane, tris (perfluorobiphenyl), tris ( Examples include perfluoroanthril) borane and tris (perfluorobinaphthyl) borane.

Among these, tris (3,5-ditrifluoromethylphenyl) borane, tris (2,6-ditrifluoromethylphenyl) borane, tris (pentafluorophenyl) borane, tris (perfluoronaphthyl) borane, tris (perfluoro) Biphenyl) borane, tris (perfluoroanthril) borane, tris (perfluorobinaphthyl) borane are more preferred, and even more preferably tris (2,6-ditrifluoromethylphenyl) borane, tris (pentafluorophenyl) borane, tris ( Perfluoronaphthyl) borane and tris (perfluorobiphenyl) borane are exemplified as preferred compounds.

Further, specifically expressing the borate compound, the first example is a compound represented by the following general formula (b).
[L ¹ −H] ⁺ [BR ⁶ R ⁷ X ⁴ X ⁵ ] ⁻ (b)

In formula (b), L ¹ is a neutral Lewis base, H is a hydrogen atom, and [L ^1- H] is a Bronsted acid such as ammonium, anilinium, and phosphonium.
Examples of ammonium include trialkyl-substituted ammonium such as trimethylammonium, triethylammonium, tripropylammonium, tributylammonium and tri (n-butyl) ammonium, and dialkylammonium such as di (n-propyl) ammonium and dicyclohexylammonium.

Examples of anilinium include N, N-dialkylaniliniums such as N, N-dimethylanilinium, N, N-diethylanilinium, and N, N-2,4,6-pentamethylanilinium.
Further, examples of phosphonium include triarylphosphonium such as triphenylphosphine, tributylphosphonium, tri (methylphenyl) phosphonium, and tri (dimethylphenyl) phosphonium, and trialkylphosphonium.

Further, in the formula (b), R ⁶ and R ⁷ are the same or different aromatic or substituted aromatic hydrocarbon groups containing 6 to 20, preferably 6 to 16 carbon atoms, which are linked to each other by a bridging group. As the substituent of the substituted aromatic hydrocarbon group, an alkyl group typified by a methyl group, an ethyl group, a propyl group, an isopropyl group and the like, and a halogen such as fluorine, chlorine, bromine and iodine are preferable.
Furthermore, X ⁴ and X ⁵ each independently, hydride radicals, halide radicals, hydrocarbon group containing from 1 to 20 carbon atoms, 1 to 20 in which one or more hydrogen atoms are substituted by a halogen atom carbon It is a substituted hydrocarbon group containing an atom.

As a specific example of the compound represented by the above general formula (b),
Tributylammonium tetra (pentafluorophenyl) borate,
Tributylammonium tetra (2,6-ditrifluoromethylphenyl) borate,
Tributylammonium tetra (3,5-ditrifluoromethylphenyl) borate,
Tributylammonium tetra (2,6-difluorophenyl) borate,
Tributylammonium tetra (perfluoronaphthyl) borate,
Dimethylanilinium tetra (pentafluorophenyl) borate,
Dimethylanilinium tetra (2,6-ditrifluoromethylphenyl) borate,
Dimethylanilinium tetra (3,5-ditrifluoromethylphenyl) borate,
Dimethylanilinium tetra (2,6-difluorophenyl) borate,
Dimethylanilinium tetra (perfluoronaphthyl) borate,
Triphenylphosphonium tetra (pentafluorophenyl) borate,
Triphenylphosphonium tetra (2,6-ditrifluoromethylphenyl) borate,
Triphenylphosphonium tetra (3,5-ditrifluoromethylphenyl) borate,
Triphenylphosphonium tetra (2,6-difluorophenyl) borate,
Triphenylphosphonium tetra (perfluoronaphthyl) borate,
Trimethylammonium tetra (2,6-ditrifluoromethylphenyl) borate,
Triethylammonium tetra (pentafluorophenyl) borate,
Triethylammonium tetra (2,6-ditrifluoromethylphenyl) borate,
Triethylammonium tetra (perfluoronaphthyl) borate,
Tripropylammonium tetra (pentafluorophenyl) borate,
Tripropylammonium tetra (2,6-ditrifluoromethylphenyl) borate,
Tripropylammonium tetra (perfluoronaphthyl) borate,
Di (1-propyl) ammonium tetra (pentafluorophenyl) borate,
Examples thereof include dicyclohexylammonium tetraphenylborate.

Among these,
Tributylammonium tetra (pentafluorophenyl) borate,
Tributylammonium tetra (2,6-ditrifluoromethylphenyl) borate,
Tributylammonium tetra (3,5-ditrifluoromethylphenyl) borate,
Tributylammonium tetra (perfluoronaphthyl) borate,
Dimethylaniliniutetra (pentafluorophenyl) borate,
Dimethylanilinium tetra (2,6-ditrifluoromethylphenyl) borate,
Dimethylanilinium tetra (3,5-ditrifluoromethylphenyl) borate,
Dimethylanilinium tetra (perfluoronaphthyl) borate is preferred.

The second example of the borate compound is represented by the following general formula (c).
[L ² ] ⁺ [BR ⁶ R ⁷ X ⁴ X ⁵ ] ^- (c)

In formula (c), L ² is a carbocation, methyl cation, ethyl cation, propyl cation, isopropyl cation, butyl cation, isobutyl cation, tert-butyl cation, pentyl cation, tropinium cation, benzyl cation, trityl cation, sodium. Examples include cations and protons. Further, R ⁶ , R ⁷ , X ⁴ and X ⁵ are the same as the definitions in the general formula (b).

Specific examples of the compound represented by the above general formula (c) include
Trityl tetraphenyl borate,
Trityl Tetra (o-Trill) Borate,
Trityl Tetra (p-Trill) Borate,
Trityl Tetra (m-Trill) Borate,
Trityltetra (o-fluorophenyl) borate,
Trityltetra (p-fluorophenyl) borate,
Trityltetra (m-fluorophenyl) borate,
Trityltetra (3,5-difluorophenyl) borate,
Trityl Tetra (Pentafluorophenyl) Borate,
Trityltetra (2,6-ditrifluoromethylphenyl) borate,
Trityltetra (3,5-ditrifluoromethylphenyl) borate,
Trityl Tetra (Perfluoronaphthyl) Borate,
Tropinium tetraphenylborate,
Tropinium tetra (o-trill) borate,
Tropinium tetra (p-tolyl) borate,
Tropinium tetra (m-trill) borate,
Tropinium tetra (o-fluorophenyl) borate,
Tropinium tetra (p-fluorophenyl) borate,
Tropinium tetra (m-fluorophenyl) borate,
Tropinium tetra (3,5-difluorophenyl) borate,
Tropinium tetra (pentafluorophenyl) borate,
Tropinium tetra (2,6-ditrifluoromethylphenyl) borate,
Tropinium tetra (3,5-ditrifluoromethylphenyl) borate,
Tropinium tetra (perfluoronaphthyl) borate,
NaBPh ₄ ,
NaB (o-CH _3- Ph) ₄ ,
NaB (p-CH _3- Ph) ₄ ,
NaB (m-CH _3- Ph) ₄ ,
NaB (o-F-Ph) ₄ ,
NaB (p-F-Ph) ₄ ,
NaB (m-F-Ph) ₄ ,
NaB (3,5-F _2- Ph) ₄ ,
NaB (C ₆ F ₅ ) ₄ ,
NaB (2,6- (CF ₃ ) _2- Ph) ₄ ,
NaB (3,5- (CF ₃ ) _2- Ph) ₄ ,
NaB (C ₁₀ F ₇ ) ₄ ,
H ⁺ BPh ₄ · 2 diethyl ether,
_{^{H + B (3,5-F 2}} -Ph) 4 · 2 diethyl ether,
^{_{H + B (C 6 F 5}} ) 4 - · 2 diethyl ether,
^{_{H + B (2,6- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (3,5- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (C 10 H 7}} ) 4 · 2 can be exemplified diethyl ether.
The above "Ph" represents a phenyl group.

Among these,
Trityl Tetra (Pentafluorophenyl) Borate,
Trityltetra (2,6-ditrifluoromethylphenyl) borate,
Trityltetra (3,5-ditrifluoromethylphenyl) borate,
Trityl Tetra (Perfluoronaphthyl) Borate,
Tropinium tetra (pentafluorophenyl) borate,
Tropinium tetra (2,6-ditrifluoromethylphenyl) borate,
Tropinium tetra (3,5-ditofluoromethylphenyl) borate,
Tropinium tetra (perfluoronaphthyl) borate,
NaB (C ₆ F ₅ ) ₄ ,
NaB (2,6- (CF ₃ ) _2- Ph) ₄ ,
NaB (3,5- (CF ₃ ) _2- Ph) ₄ ,
NaB (C ₁₀ F ₇ ) ₄ ,
^{_{H + B (C 6 F 5}} ) 4 - · 2 diethyl ether,
^{_{H + B (2,6- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (3,5- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (C 10 H 7}} ) 4 · 2 diethyl ether.

More preferably, among these, trityltetra (pentafluorophenyl) borate,
Trityltetra (2,6-ditrifluoromethylphenyl) borate,
Tropinium tetra (pentafluorophenyl) borate,
Tropinium tetra (2,6-ditrifluoromethylphenyl) borate,
NaB (C ₆ F ₅ ) ₄ ,
NaB (2,6- (CF ₃ ) _2- Ph) ₄ ,
^{_{H + B (C 6 F 5}} ) 4 - · 2 diethyl ether,
^{_{H + B (2,6- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (3,5- (CF 3}} ) 2 -Ph) 4 · 2 diethyl ether,
^{_{H + B (C 10 H 7}} ) 4 · 2 diethyl ether.

(3) Catalyst component (C)
Examples of the fine particle carrier as the catalyst component (C) include an inorganic carrier, a particulate polymer carrier, or a mixture thereof. As the inorganic carrier, a metal, a metal oxide, a metal chloride, a metal carbonate, a carbonaceous substance, or a mixture 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 or composite oxides of elements of Groups 1 to 14 of the periodic table. For example, SiO ₂ , Al ₂ O ₃ , MgO, CaO, B ₂ O ₃ , TiO ₂ , ZrO ₂ , Fe ₂ O ₃ , Al ₂ O ₃ · MgO, Al ₂ O ₃ · CaO, Al ₂ O ₃ · SiO ₂ , Al ₂ O ₃ · MgO · CaO, Al ₂ O ₃ · MgO · SiO ₂ , Various natural or synthetic single oxides or composite oxides such as Al ₂ O ₃ · CuO, Al ₂ O ₃ · Fe ₂ O ₃ , Al ₂ O ₃ · NiO, SiO _{2 · MgO can be exemplified.}
Here, the above formula represents only the composition, not the molecular formula, and the structure and component ratio of the composite oxide used in the present invention are not particularly limited.
Further, the metal oxide used in the present invention may absorb a small amount of water and may contain a small amount of impurities.

As the metal chloride, 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 the metal carbonate, an alkali metal or alkaline earth metal carbonate is preferable, and specific examples thereof include magnesium carbonate, calcium carbonate, and barium carbonate.
Examples of carbonaceous materials include carbon black and activated carbon.
All of the above inorganic carriers can be preferably used in the present invention, but the use of metal oxides, silica, alumina and the like is particularly preferable.

These inorganic carriers are usually 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 adjust to.
The properties of these inorganic carriers are not particularly limited, but usually, the average particle size 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 to 700 m ² / g, pore volume 0.3 to 2.5 cm ³ / g, preferably 0.5 to 2.0 cm ³ / g, apparent specific gravity 0.10 to 0 It is preferable to use an inorganic carrier having a capacity of .50 g / cm ^3.

The above-mentioned inorganic carriers can be used as they are, but as a preliminary treatment, these carriers are used as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tripropylaluminum, tributylaluminum, trioctylaluminum, tridecylaluminum, and diisobutyl. It can be used after being contacted with an organic aluminum compound such as aluminum hydride or an organic aluminum oxy compound containing an Al—O—Al bond.

The metallocene catalyst according to the present invention is not particularly limited in the contact method of each component when obtaining a catalyst composed of a catalyst component (A), a catalyst component (B), and a catalyst component (C) if necessary. For example, the following method can be arbitrarily adopted.

(I) The catalyst component (A) and the catalyst component (B) are brought into contact with each other, and then the catalyst component (C) is brought into contact with the catalyst component (C).
(II) The catalyst component (A) and the catalyst component (C) are brought into contact with each other, and then the catalyst component (B) is brought into contact with the catalyst component (B).
(III) The catalyst component (B) and the catalyst component (C) are brought into contact with each other, and then the catalyst component (A) is brought into contact with the catalyst component (A).

Among these contact methods, (I) and (III) are preferable, and (I) is most preferable. In either contact method, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene (usually having 6 to 12 carbon atoms), heptane, hexane, decane and dodecane are generally used in an inert atmosphere such as nitrogen or argon. , A method of contacting each component with stirring or non-stirring in the presence of an aliphatic or alicyclic hydrocarbon (usually 5 to 12 carbon atoms) such as cyclohexane is adopted.
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, still more preferably. It is desirable to carry out in 30 minutes to 12 hours.

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

When the contact reaction between the components is carried out stepwise, the solvent used in the previous stage may be used as it is as the solvent for the contact reaction in the subsequent stage without removing it.
In addition, after the contact reaction in the previous stage using a soluble solvent, liquid inert hydrocarbons such as pentane, hexane, decane, dodecane, cyclohexane, benzene, toluene, and xylene, in which certain components are insoluble or sparingly soluble, are aliphatic. (Hydrocarbons, alicyclic hydrocarbons or aromatic hydrocarbons) are added to recover the desired product as a solid, or a part or all of the soluble solvent is once removed by means such as drying to obtain the desired product. After the product is taken out as a solid, the subsequent contact reaction of the desired product can also be carried out using any of the above-mentioned inert hydrocarbon solvents.
In the present invention, it does not prevent the contact reaction of each component from being carried out a plurality of times.

In the present invention, the ratio of the catalyst component (A), the catalyst component (B), and the catalyst component (C) to be used is not particularly limited, but the following range is preferable.

When an organic aluminum oxy compound is used as the catalyst component (B), the atomic ratio (Al / M) of aluminum of the organic aluminum oxy compound to the transition metal (M) in the catalyst component (A) is usually 1 to 100. The range of 000, preferably 5 to 1000, more preferably 50 to 200 is desirable, and when a borane compound or a borate compound is used, the atomic ratio of boron to the transition metal (M) in the metallocene compound (B / M). Is usually preferably selected in the range of 0.01 to 100, preferably 0.1 to 50, and more preferably 0.2 to 10.
Further, when a mixture of an organic aluminum oxy compound, a borane compound and a borate compound is used as the catalyst component (B), the same use as above is applied to the transition metal (M) for each compound in the mixture. It is desirable to select by proportion.

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

By bringing the catalyst component (A), the catalyst component (B), and the catalyst component (C) into contact with each other by any of the contact methods (I) to (III), and then removing the solvent. , A catalyst for olefin polymerization can be obtained as a solid catalyst.
The solvent is preferably removed 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 contact methods (IV) and (V).
(IV) The catalyst component (A) and the catalyst component (C) are brought into contact with each other to remove the solvent, and this is used as a solid catalyst component, which is combined with an organic aluminum oxy compound, a borane compound, a borate compound or a mixture thereof under polymerization conditions. Make contact.
(V) The solvent is removed by contacting the organic aluminum oxy compound, the borane compound, the borate compound or a mixture thereof with the catalyst component (C), and this is used as a solid catalyst component, and the catalyst component (A) and the catalyst component (A) are used under polymerization conditions. Make contact.
Also in the case of the above-mentioned contact methods (IV) and (V), the same conditions as described above can be used as the component ratio, the contact condition and the solvent removal condition.

Further, a layered silicate can also be used as a component that also serves as a catalyst component (B) and a catalyst component (C) used in the production of the ethylene-based copolymer (A) used in the present invention.
The layered silicate is a silicate compound having a crystal structure in which surfaces formed by ionic bonds or the like are stacked in parallel with each other with a weak bonding force.
Most of the layered silicates are naturally produced mainly as the main component of clay minerals, but these layered silicates are not limited to those naturally produced, and may be artificial compounds.

Among these, montmorillonite, saponite, byderite, nontronite, saponite, hectorite, stepnsite, bentonite, teniolite and other smectites, vermiculite and mica are preferable.

In general, natural products are often non-ion exchangeable (non-swellable), and in that case, in order to have preferable ion exchange property (or swelling property), the ion exchange property (or swelling property) is determined. It is preferable to carry out a process for imparting. Among such treatments, the following chemical treatments are particularly preferable.
Here, as the chemical treatment, any of a surface treatment for removing impurities adhering to the surface and a treatment for affecting the crystal structure and chemical composition of the layered silicate can be used.
Specifically, (i) acid treatment performed using hydrochloric acid, sulfuric acid, etc., (ii) _{alkaline treatment performed using NaOH, KOH, NH 3,} etc., (iii) selected from Group 2 to Group 14 of the Periodic Table. Salt treatment with salts consisting of at least one anion selected from the group consisting of cations containing at least one atom and anions derived from halogen atoms or inorganic acids, (iv) alcohols, hydrocarbons. Examples thereof include treatment with organic substances such as compounds, formamides and aniline. These processes may be performed alone or in combination of two or more processes.

The particle properties of the layered silicate can be controlled by pulverization, granulation, granulation, separation, etc. at any time before, during, or after all the steps. The method can be arbitrary and purposeful. In particular, regarding the granulation method, for example, the spray granulation method, the rolling granulation method, the compression granulation method, the stirring granulation method, the briquetting method, the compacting method, the extrusion granulation method, and the fluidized bed granulation method. Examples thereof include a method, an emulsified granulation method, and an in-liquid granulation method. Among the above, particularly preferable granulation methods are the spray granulation method, the rolling granulation method and the compression granulation method.

The above-mentioned layered silicates can be used as they are, but these layered silicates can be used as trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, and diisobutyl. It can be used in combination with an organic aluminum compound such as aluminum hydride or an organic aluminum oxy compound containing an Al—O—Al bond.

In the metallocene catalyst used in the present invention, in order to support the catalyst component (A) on the layered silicate, the catalyst component (A) and the layered silicate are brought into mutual contact, or the catalyst component (A), an organoaluminum compound, and the like. The layered silicates may be brought into contact with each other.
The contact method for each component is not particularly limited, and for example, the following methods can be arbitrarily adopted.

(VI) The catalyst component (A) is brought into contact with the organoaluminum compound, and then is brought into contact with the layered silicate carrier.
(VII) The catalyst component (A) is brought into contact with the layered silicate carrier, and then is brought into contact with the organoaluminum compound.
(VIII) The organoaluminum compound is brought into contact with the layered silicate carrier, and then is brought into contact with the catalyst component (A).

Among these contact methods, (VI) and (VIII) are preferable. In either contact method, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene (usually having 6 to 12 carbon atoms), heptane, hexane, decane and dodecane are generally used in an inert atmosphere such as nitrogen or argon. , A method of contacting each component with stirring or non-stirring in the presence of an aliphatic or alicyclic hydrocarbon (usually 5 to 12 carbon atoms) such as cyclohexane is adopted.

The proportion of the catalyst component (A), the organoaluminum compound, and the layered silicate carrier used is not particularly limited, but is preferably in the following range.
The amount of the catalyst component (A) supported is 0.0001 to 5 mmol, preferably 0.001 to 0.5 mmol, and more preferably 0.01 to 0.1 mmol per 1 g of the layered silicate carrier.
When an organoaluminum compound is used, the amount of Al supported is preferably in the range of 0.01 to 100 mol, preferably 0.1 to 50 mol, and more preferably 0.2 to 10 mol.

As the method of carrying and removing the solvent, the same conditions as those of the above-mentioned inorganic carrier can be used.
When a layered silicate is used as a component that also serves as the catalyst component (B) and the catalyst component (C), the polymerization activity is high and the productivity of the ethylene-based polymer having a long-chain branch is improved.
The catalyst for olefin polymerization thus obtained may be used after prepolymerization of the monomers, if necessary.

As an example of manufacturing a metallocene catalyst, for example, by referring to "catalyst" and "blending ratio and conditions of raw materials" described in JP-A-2002-535339 and JP-A-2004-189869, which are publicly known publications, Can be manufactured.
Further, the index of the polymer can be controlled by various polymerization conditions, and can be controlled by, for example, the methods described in JP-A-2-269705 and JP-A-3-21607.

The ethylene-based copolymer (A) includes 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-octene and the like. Obtained by copolymerization with.
In addition, copolymerization with a diene is also possible for the purpose of modification. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like.
The comonomer content at the time of polymerization can be arbitrarily selected. For example, in the case of copolymerization of ethylene and an α-olefin having 3 to 12 carbon atoms, an ethylene / α-olefin copolymer is used. The α-olefin content in the medium is 1 to 40 mol%, preferably 1 to 30 mol%.

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 adjusted more effectively by adding hydrogen to the polymerization reaction system. Can be done.
Further, even if a component for removing water, a so-called scavenger, is added to the polymerization system, it can be carried out without any problem.
Examples of such scavengers include organoaluminum compounds such as trimethylaluminum, triethylaluminum and triisobutylaluminum, the organoaluminum oxy compounds, modified organoaluminum compounds containing branched alkyl, organozinc compounds such as diethylzinc and dibutylzinc, and diethyl. Organoaluminium compounds such as magnesium, dibutylmagnesium and ethylbutylmagnesium, and greenia compounds such as ethylmagnesium chloride and butylmagnesium chloride are used. Among these, triethylaluminum, triisobutylaluminum, and ethylbutylmagnesium are preferable, and triethylaluminum is particularly preferable.
It can also be applied to a multi-step polymerization method having two or more steps in which polymerization conditions such as hydrogen concentration, monomer amount, polymerization pressure, and polymerization temperature are different from each other without any problem.

The ethylene-based copolymer (A) can be produced by a production process such as a vapor phase polymerization method, a solution polymerization method, or a slurry polymerization method, and a slurry polymerization method is preferable.
Among the polymerization conditions of the ethylene-based copolymer (A), the polymerization temperature can be selected from the range of 0 to 200 ° C.
In slurry polymerization, polymerization is carried out at a temperature lower than the melting point of the produced polymer.
The polymerization pressure can be selected from the range of atmospheric pressure to about 10 MPa.
Selected from aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane with substantially no oxygen or water. It can be produced by performing slurry polymerization of ethylene and α-olefin in the presence of an inert hydrocarbon solvent.

The ethylene-based copolymer (A) can be polymerized sequentially and continuously in a single polymer, a plurality of reactors connected in series or in parallel, and a plurality of ethylene copolymers can be separately polymerized if a predetermined range is satisfied. It may be a mixture after polymerization.

1-5. Ethylene polymer (B)
From the viewpoint of pressure resistance and / or durability, the polyethylene resin composition for a crosslinked polyethylene tube of the present invention contains an ethylene homopolymer having a higher density than the ethylene-based polymer (A) and an ethylene homopolymer as the ethylene-based polymer (B). / Or it is preferable to contain a copolymer of ethylene and α-olefin having 3 to 20 carbon atoms.
In the present invention, the ethylene-based polymer (B) has a melt flow rate (MFR (B)) of 1 to 100 g / 10 minutes at a temperature of 190 ° C. and a load of 2.16 kg, and a density (B) of 0.946 to. It is preferably 0.975 g / cm ^3.

The MFR (B) of the ethylene polymer (B) is 1 to 100 g / 10 minutes, preferably more than 5 g / 10 minutes and 100 g / 10 minutes or less, more preferably 5.5 to 60 g / 10 minutes, and further. It is preferably 5.5 to 50 g / 10 minutes.
When the MFR (B) is 1 g / 10 minutes or more, the molecular weight is reduced, the fluidity is improved, and the moldability is improved.
On the other hand, when the MFR (B) is 100 g / 10 minutes or less, the impact resistance is improved.

Here, MFR is a value measured according to JIS K6922-2: 1997.
The MFR (B) can be adjusted by adjusting the ethylene polymerization temperature, the use of a chain transfer agent, etc. in the production of the ethylene-based polymer, and a desired one can be obtained.
That is, for example, the MFR (B) can be increased as a result of lowering the molecular weight by raising the polymerization temperature of ethylene and α-olefin, and as a result of raising the molecular weight by lowering the polymerization temperature, The MFR (B) can be reduced.
Further, in the copolymerization reaction of ethylene and α-olefin, by increasing the amount of hydrogen to coexist (the amount of chain transfer agent), as a result of lowering the molecular weight, MFR (B) can be increased and coexist. By reducing the amount of hydrogen (the amount of chain transfer agent), the MFR (B) can be reduced as a result of increasing the molecular weight.

The density of the ethylene polymer (B) (B) is preferably 0.946~0.975g / cm ^3, more preferably 0.951~0.965g / cm ^3, particularly preferably 0.951 ~ 0.962 g / cm ³ .
When the density (B) is 0.946 g / cm ³ or more, the pressure resistance is improved in the final polyethylene resin composition.
On the other hand, when the density (B) is 0.975 g / cm ³ or less, the polyethylene resin composition can be easily produced and the impact resistance of the final polyethylene resin composition is improved.
The density (B) can be obtained, for example, by changing the type and amount of the comonomer to be copolymerized with ethylene, and can be reduced by increasing the content of the α-olefin.

The ethylene-based polymer (B) contained in the polyethylene resin composition of the present invention preferably contains one or more ethylene-based polymer components having a higher density than the ethylene-based polymer (A).
Specifically, the ethylene polymer (B) has an HLMFR (B-1) of 0.2 to 4.0 g / 10 minutes and a density (B-1) of 0.935 to 0.945 g / cm ³ . A certain ethylene polymer component (B-1) and / or MFR (B-2) is 5.5 to 200 g / 10 minutes, and the density (B-2) is 0.946 to 0.975 g / cm ³ . It is preferable to contain a certain ethylene-based polymer component (B-2).
The ethylene-based polymer (B) contains 20 to 28% by mass of the ethylene-based polymer component (B-1), more preferably 20 to 28% by mass, and 70 to 82% by mass of the ethylene-based polymer component (B-2). %, More preferably 72 to 80% by mass.
When the ethylene-based polymer component (B-1) is 18% by mass or more and the ethylene-based polymer component (B-2) is 82% by mass or less, the durability is improved and the ethylene-based polymer component is improved. When (B-1) is 30% by mass or less and the ethylene-based polymer component (B-2) is 70% by mass or more, the pressure resistance of the molded product during long-term use is improved.

The HLMFR (B-1) of the ethylene polymer component (B-1) is preferably 0.2 to 4.0 g / 10 minutes, more preferably 0.3 to 2.0 g / 10 minutes, and even more preferably 0. 4 to 0.8 g / 10 minutes.
The HLMFR (B-1) of the ethylene polymer component (B-1) can be measured by the same method as the above-described HLMFR measurement method.
When the HLMFR (B-1) is 0.2 g / 10 minutes or more, the compatibility with the ethylene polymer component (B-2) tends to be improved, and the impact resistance of the molded product tends to be improved.
When HLMFR (B-1) is 4.0 g / 10 minutes or less, the impact resistance of the molded product tends to be improved.
The HLMFR (B-1) can be adjusted by changing the amount of the chain transfer agent (hydrogen, etc.) coexisting during ethylene polymerization or by changing the polymerization temperature, and the amount of hydrogen is increased. Alternatively, the HLMFR (B-1) can be increased by increasing the polymerization temperature.

The density (B-1) of the ethylene polymer component (B-1) ^{is preferably 0.935 to 0.945 g / cm 3} , and more preferably 0.943 to 0.944 g / cm ³ .
The density (B-1) of the ethylene polymer component (B-1) can be measured by the same method as the above-mentioned density measuring method.
When the density (B-1) is 0.935 g / cm ³ or more, the rigidity of the molded product is improved, while when it is 0.945 g / cm ³ or less, the durability and flexibility of the molded product are improved. ..
The density (B-1) can be adjusted, for example, by changing the amount of α-olefin copolymerized with ethylene, and the density can be decreased by increasing the amount of α-olefin.

The MFR (B-2) of the ethylene polymer component (B-2) is preferably 5.5 to 200 g / 10 minutes, more preferably 5.5 to 80 g / 10 minutes.
The MFR (B-2) of the ethylene polymer component (B-2) can be measured by the same method as the above-mentioned MFR measuring method.
When the MFR (B-2) is 5.5 g / 10 minutes or more, the fluidity during molding is improved.
When the MFR (B-2) is 200 g / 10 minutes or less, the impact resistance of the molded product is improved.
The MFR (B-2) can be adjusted by changing the amount of chain transfer agent (hydrogen, etc.) coexisting during ethylene polymerization or by changing the polymerization temperature, and the amount of hydrogen is increased. Alternatively, the MFR (B-2) can be increased by increasing the polymerization temperature.

The density (B-2) of the ethylene polymer component (B-2) ^{is preferably 0.946 to 0.975 g / cm 3} , and more preferably 0.951 to 0.968 g / cm ³ .
The density (B-2) of the ethylene polymer component (B-2) can be measured by the same method as the above-mentioned density measuring method.
When the density (B-2) is 0.946 g / cm ³ or more, the rigidity of the molded product is improved, while when it is 0.975 g / cm ³ or less, the impact resistance is improved.
The density (B-2) can be adjusted, for example, by changing the amount of α-olefin copolymerized with ethylene, and the density can be reduced by increasing the amount of α-olefin.

The polymerization catalyst of the ethylene-based polymer (B) is not particularly limited, and examples thereof include a Ziegler catalyst and the above-mentioned metallocene catalyst.
Examples of the Ziegler catalyst include a solid Ziegler catalyst composed of a Ti and / or V compound and an organometallic compound of Group 1 to Group 3 elements of the periodic table.
Examples of the solid Ziegler catalyst include solid catalysts containing titanium (Ti) and / or vanadium (V) and magnesium (Mg), and organometallic compounds that can be used together with these components include organoaluminum compounds, especially tri. Alkyl aluminum is preferred.
The amount of the organoaluminum compound used in the polymerization reaction is not particularly limited, but when used, it is usually preferably in the range of 0.05 to 1000 mol with respect to 1 mol of the transition metal compound.

As an example of the Ziegler catalyst, for example, the "catalyst" described in Example 1 of JP-A-63-20602 is used, and as a polymerization method, it is described in Example 1 of JP-A-2004-123995. The ethylene-based polymer (B) according to the present invention can be produced by taking into consideration the "blending ratio and conditions of raw materials".

The ethylene-based polymer (B) is a homopolymerization of ethylene, or an α-olefin having 3 to 20 carbon atoms with ethylene, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene. , 1-Octene and the like. In addition, copolymerization with a diene is also possible for the purpose of modification. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like.
The comonomer content at the time of polymerization can be arbitrarily selected. For example, in the case of copolymerization of ethylene and an α-olefin having 3 to 20 carbon atoms, an ethylene / α-olefin copolymer is used. The α-olefin content in the medium is 1 to 40 mol%, preferably 1 to 30 mol%.

The ethylene-based polymer (B) can be produced by a production process such as a vapor phase polymerization method, a solution polymerization method, or a slurry polymerization method, and a slurry polymerization method is preferable.
Among the polymerization conditions of the ethylene polymer, the polymerization temperature can be selected from the range of 0 to 300 ° C.
In slurry polymerization, polymerization is carried out at a temperature lower than the melting point of the produced polymer.
The polymerization pressure can be selected from the range of atmospheric pressure to about 10 MPa.
Selected from aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane with substantially no oxygen or water. It can be produced by performing slurry polymerization of ethylene and α-olefin in the presence of an inert hydrocarbon solvent.

In the slurry polymerization, hydrogen supplied to the polymer is consumed as a chain transfer agent to determine the average molecular weight of the ethylene-based polymer produced, and a part of the hydrogen is dissolved in a solvent and discharged from the polymer. The solubility of hydrogen in the solvent is low, and the hydrogen concentration near the polymerization active site of the catalyst is low unless a large amount of gas phase parts are present in the polymerizer. Therefore, if the hydrogen supply amount is changed, the hydrogen concentration at the polymerization active point of the catalyst changes rapidly, and the molecular weight of the produced ethylene-based polymer changes following the hydrogen supply amount in a short period of time. Therefore, if the hydrogen supply amount is changed in a short cycle, a more homogeneous product can be produced. For this reason, it is preferable to adopt the slurry polymerization method as the polymerization method. Further, it is preferable to change the hydrogen supply amount discontinuously rather than continuously because the effect of widening the molecular weight distribution can be obtained.
In the ethylene-based polymer (B) according to the present invention, it is important to change the hydrogen supply amount as described above, but other polymerization conditions such as polymerization temperature, catalyst supply amount, and supply of olefins such as ethylene are important. It is also important to appropriately change the amount, the amount of comonomer such as 1-hexene, the amount of solvent supplied, etc. at the same time as or separately from the change of hydrogen.

The ethylene-based polymer (B) can be composed of a plurality of components.
The ethylene-based polymer (B) may be a polymer that is sequentially and continuously polymerized in a multi-stage polymerization reactor using one type of catalyst, and may be used in a single-stage or multi-stage polymerization reactor using a plurality of types of catalysts. It may be a polymer produced in the above-mentioned method, or it may be a mixture of polymers polymerized by using one kind or a plurality of kinds of catalysts. Further, the ethylene-based polymer (B) uses a plurality of types of catalysts or a catalyst having a plurality of active sites at the same time as the ethylene-based copolymer (A) as long as the properties of the polyethylene resin composition for polyethylene pipes are not impaired. A polymer produced in a single-stage or multi-stage polymerization reactor may be used.

When a so-called multi-stage polymerization method in which a plurality of reactors connected in series are sequentially and continuously polymerized is used, a high-molecular-weight component is produced in the first polymerization region (first-stage reactor) as long as a predetermined range is satisfied. Even in the order in which the polymer is polymerized by adopting the production conditions to be carried out, the obtained polymer is transferred to the next reaction region (second stage reactor), and the low molecular weight component is produced in the second stage reactor. On the contrary, the polymer was polymerized by adopting the production conditions for producing a low molecular weight component in the first polymerization region (first stage reactor), and the obtained polymer was used in the next reaction region (second stage reactor). ), And the order in which the high-molecular-weight component is produced in the second-stage reactor may be either.
A specific preferable polymerization method is the following method. That is, using a Ziegler catalyst containing a titanium-based transition metal compound and an organoaluminum compound and two reactors, ethylene and α-olefin are introduced into the first-stage reactor, and the weight of the low-density high-molecular-weight component is heavy. A coalescence is produced, the polymer extracted from the first stage reactor is transferred to the second stage reactor, ethylene and hydrogen are introduced into the second stage reactor, and the density is low. This is a method for producing a polymer having a molecular weight component.
In the case of multi-stage polymerization, the amount of ethylene-based polymer produced in the second and subsequent stages of polymerization and its properties are determined by determining the amount of polymer produced in each stage (which can be grasped by unreacted gas analysis, etc.). The physical characteristics of the polymer extracted after each stage can be measured, and the physical properties of the polymer produced in each stage can be determined based on the additivity.

The ethylene used in the ethylene-based polymer (B) and the ethylene-based copolymer (A) may be ethylene produced from ordinary crude oil derived from fossil fuels, or ethylene derived from plants. good.
Examples of plant-derived ethylene and polyethylene include ethylene and its polymers described in JP-A-2010-511634.
Plant-derived ethylene and its polymers have carbon-neutral properties (which do not use fossil raw materials and do not lead to an increase in carbon dioxide in the atmosphere), making it possible to provide environmentally friendly products.

1-6. Composition ratio of ethylene-based copolymer (A) and ethylene-based polymer (B) The polyethylene resin composition contains the ethylene-based copolymer (A) and the ethylene-based polymer (B) in the polyethylene resin composition. A total of 100 parts by mass contains 15 to 40 parts by mass, preferably 25 to 35 parts by mass, and more preferably 25 to 30 parts by mass of the ethylene-based copolymer (A).
Further, the polyethylene resin composition contains 60 to 85 parts by mass of the ethylene-based polymer (B) per 100 parts by mass of the total of the ethylene-based copolymer (A) and the ethylene-based polymer (B) in the polyethylene resin composition. It contains, preferably 65 to 75 parts by mass, and more preferably 70 to 75 parts by mass.
When the composition ratio of the ethylene-based copolymer (A) is 15 parts by mass or more, the long-term durability of the polyethylene resin composition of the present invention is improved. On the other hand, if it is 40 parts by mass or less, the HLMFR and density of the polyethylene resin composition of the present invention are improved, and the fluidity, rigidity and pressure resistance are improved.

1-7. Production of Polyethylene Resin Composition The polyethylene resin composition of the present invention can be obtained by, for example, melt-mixing an ethylene-based copolymer (A) and an ethylene-based polymer (B) at the above composition ratios.
The melt-mixing conditions are not particularly limited, but in order for the polyethylene resin composition to satisfy the above characteristics, it is preferable to mix the polyethylene resin composition at a temperature condition of 200 ° C. to 250 ° C. using a twin-screw extruder.

2. Cross-linked polyethylene pipe The cross-linked polyethylene pipe of the present invention contains the polyethylene resin composition of the present invention.
It is characterized in that the rupture time in a high temperature tensile creep test (80 ° C., load 3.5 kg) on a cross-linked polyethylene sheet exceeds 1000 hours.
Since the cross-linked polyethylene pipe containing the polyethylene resin composition of the present invention uses the polyethylene resin composition for cross-linked polyethylene pipe of the present invention, it is possible to improve the service life, expand the application points, and the like.

2-1. High temperature tensile creep test The cross-linked polyethylene pipe of the present invention has a breaking time of more than 1000 hours in a high temperature tensile creep test (80 ° C., load 3.5 kg) on a cross-linked polyethylene sheet prepared using a polyethylene resin composition, preferably. It is 1200 hours or more, more preferably 1500 hours or more.
When the rupture time of the high temperature tensile creep test (80 ° C., load 3.5 kg) exceeds 1000 hours, the high temperature durability of the molded product during long-term use is improved.

In the present invention, the rupture time in the high temperature tensile creep test (80 ° C., load 3.5 kg) is a value measured at 80 ° C. and a load of 3.5 kg. The test piece is punched into a dumbbell shape from a 2 mm flat plate (sheet) made of a crosslinked polyethylene resin composition. The test is carried out by molding the crosslinked polyethylene resin composition into a sheet shape for convenience, but the same result can be obtained when the test is performed by molding the crosslinked polyethylene resin composition into a tube shape.
The failure time in the high temperature tensile creep test (80 ° C., load 3.5 kg) is generally, for example, reducing the density (A) of the ethylene-based copolymer (A) constituting the polyethylene resin composition and HLMFR (A). ), And the density (B) of the ethylene-based polymer (B) can be increased to increase the density (B).

2-2. Gel fraction (crosslinking degree) (%)
The cross-linked polyethylene pipe of the present invention preferably has a gel fraction of 65% or more, preferably 75% or more.
When the gel fraction is 65% or more, the effect of cross-linking can be sufficiently exerted, and the long-term pressure resistance performance at a particularly high temperature is improved.
The gel fraction can be expressed by the following formula (d) according to the gel fraction defined in JIS K6769: 2013.
Gel fraction (%) = ((sample mass before solvent extraction-sample mass after solvent extraction) / sample mass before solvent extraction) x 100 ... (d)
In the above formula (d), the sample mass after solvent extraction is defined by dissolving the uncrosslinked resin component remaining in the sample with a solvent capable of dissolving the selected crosslinked thermoplastic resin. It refers to the mass of only the remaining insoluble matter.

2-3. Method for Producing Cross-Linked Polyethylene Pipe The cross-linked polyethylene pipe of the present invention can be produced by silane-modifying the above-mentioned polyethylene resin composition as a base resin, molding the polyethylene resin composition into a tubular shape, and cross-linking the cross-linked polyethylene pipe by a silane cross-linking method.
Further, in the present invention, the process of molding the cross-linked polyethylene pipe can be diverted from the usual pipe molding process. The extruder used is not particularly limited, and examples thereof include a single-screw extruder, a twin-screw extruder, and a multi-screw extruder.
The mold used is not particularly limited, and examples thereof include types such as a bridge, a spider, and a spiral, which are usually used as a mold for forming a pipe.

A step-up pushing device such as a gear pump may be installed between the extruder and the die in order to ensure the uniformity of the flow rate of the polyethylene-based resin composition.
Further, it is also possible to measure the wall thickness of the pipe in the process line for forming the cross-linked polyethylene pipe and feed it back to the gear pump or the take-up machine.

Specifically, as one method, an extruder capable of reacting is used, and an additive such as a silane compound, a radical generator, a silanol condensation catalyst, and an antioxidant, if necessary, is added to the base resin. The silane-modified resin composition is obtained through steps such as melting, kneading, and reaction while heating in an extruder.
This is extruded into a pipe shape, molded into a pipe shape, and cooled to form a molded tube made of a silane-modified polyethylene resin composition, and an appropriate heat is applied to the molded tube in the presence of water to carry out a silanol condensation reaction. A cross-linked polyethylene pipe can be obtained by performing a cross-linking treatment to promote the process.
Such a method is called a one-stage manufacturing method of a silane cross-linked polyethylene pipe.

In addition, as another method, in the first step, a silane compound and a radical generator, and if necessary, an additive such as an antioxidant are added to the base resin by using an extruder capable of reacting. Here, the silanol condensation catalyst is not blended, and it is extruded into strands through steps such as melting, kneading, and reaction while heating in a reactor such as an extruder, and this is cooled and cut to modify pellet-shaped silane. A polyethylene resin composition.
In the second step, a masterbatch in which the silane-modified polyethylene resin composition, for example, a polyethylene-based silanol condensation catalyst prepared in advance in a separate step, and an additive such as an antioxidant, if necessary, are blended. To prepare a silane-modified polyethylene resin composition through the steps of melting and kneading while heating in an extruder.
This is extruded into a pipe shape, molded into a pipe shape, and cooled to form a molded tube made of a silane-modified polyethylene resin composition, and an appropriate heat is applied to the molded tube in the presence of water to carry out a silanol condensation reaction. A cross-linked polyethylene pipe can be obtained by performing a cross-linking treatment to promote the process.
Such a method is called a two-stage manufacturing method of a silane cross-linked polyethylene pipe.

Examples of the method of cross-linking treatment include a method of immersing in a hot water tank at 80 to 95 ° C. for about 1 to 24 hours and a method of contacting with steam for 1 to 24 hours.

The silane compound used in the silane cross-linking method is the general formula RR'SiY ₂ (in the formula, R is an unsaturated hydrocarbon group such as a vinyl group or an allyl group, or a hydroxycarbonoxy group, and Y is a methoxy group or an ethoxy group. A hydrolyzable organic group such as an alkoxyl group represented by a butoxy group, R'is a substituent similar to R or Y).
More specifically, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyltris (β-methoxyethoxy) silane and the like can be mentioned.
The blending amount of the silane compound is preferably about 0.2 to 5 parts by mass with respect to 100 parts by mass of the base resin.

The radical generator is not particularly limited as long as it is used for silane cross-linking, and is, for example, dicumyl peroxide, di- (t-butylperoxy) -m-di-isopropylbenzene, 2,5-dimethyl-2. , 5-Di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) -hexin-3, α, α'-bis (t-butylperoxydiisopropyl) Benzene, t-butylperoxycumene, 4,4'-di (t-butylperoxy) valeric acid n-butyl ester, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane Examples thereof include organic peroxides such as azobis-isobutyronitrile and azo compounds such as dimethylazoisodibutyrate.
The mixing ratio of the radical generator depends on the type of the radical generator and the abundance of the additive having a radical scavenging function, but is 0.1 to 10 parts by mass, preferably 0, based on 100 parts by mass of the silane compound. .5 to 5 parts by mass.

The silanol condensation catalyst is not particularly limited as long as it is used for silane cross-linking, and for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, dioctyltin dilaurate, tin (II) octate, tin naphthenate, caprylic acid. Examples thereof include zinc, tetrabutyl ester of titanate, tetranonyl ester of titanate, and bis (acetylacetate) diisopropyl titanate.
The blending ratio of the silanol condensation catalyst is 0.0005 to 1 part by mass, preferably 0.01 to 0.5 part by mass with respect to 100 parts by mass of the base resin. In addition, these can be substituted by using commercially available products that have been master-batched. (For example, HZ082: 1 to 10 parts by mass in the case of Mitsubishi Chemical Corporation)

In addition to the above components, the polyethylene resin composition for cross-linked polyethylene pipes in the present invention contains other olefin-based polymers, rubbers, etc., as well as antioxidants, ultraviolet absorbers, light stabilizers, lubricants, etc. Known additives such as antistatic agents, antifogging agents, antiblocking agents, processing aids, color pigments, cross-linking agents, foaming agents, inorganic or organic fillers, and flame retardants can be blended.
As the additive, for example, one or more kinds of antioxidants (phenolic, phosphorus, sulfur), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers and the like can be appropriately used in combination.
As the filler, calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silicate, diatomaceous soil, alumina, plaster, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used. Of these, calcium carbonate, talc, mica and the like are preferably used.

In the present invention, it is also an effective method to use a nucleating agent in order to further accelerate the crystallization rate of the polyethylene resin composition for cross-linked polyethylene pipe.
As the nucleating agent, generally known ones 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, logonic acid partial metal salt, inorganic fine particles such as talc, imides , Amidos, quinacridone quinones, or mixtures thereof.
Among them, dibenzylideneacetone sorbitol derivative, organic phosphate metal salt, organic carboxylic acid metal salt and the like are suitable because they are excellent in transparency.
Specific examples of the dibenzylidene sorbitol derivative 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 can be mentioned.
Specific examples of the benzoic acid metal salt include hydroxy-di (t-butylbenzoic acid) aluminum and the like.

When the nucleating agent is blended in the polyethylene resin composition for cross-linked polyethylene pipe of the present invention, the blending amount of the nucleating agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyethylene resin composition for cross-linked polyethylene pipe. It is preferably 0.01 to 3 parts by mass, more preferably 0.01 to 1 part by mass, and particularly preferably 0.01 to 0.5 parts by mass. If the amount of the nucleating agent is 0.01 parts by mass or more, the desired effect of improving the high-speed moldability can be obtained, while if the amount is 5 parts by mass or less, the nucleating agent is less likely to aggregate and become lumpy.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not restricted by these Examples as long as it does not deviate from the gist thereof. The physical characteristics of the polyethylene resin composition for cross-linked polyethylene pipe were measured by the following method.

1. 1. Measurement method (1) Melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg:
Measured according to JIS K6922-2: 1997.
(2) Melt flow rate (MFR) at a temperature of 190 ° C. and a load of 2.16 kg:
Measured according to JIS K6922-2: 1997.
(3) Density:
Measured according to JIS K6922-1, 2: 1997.

(4) Measurement of molecular weight by gel permeation chromatography (GPC) (weight average molecular weight Mw):
It was measured by gel permeation chromatography (GPC) under the following conditions.
Equipment: 150C manufactured by WATERS
Column: 3 AD80M / S manufactured by Showa Denko Co., Ltd. Measurement temperature: 140 ° C
Concentration: 1 mg / 1 ml
Solvent: o-dichlorobenzene The molecular weight was calculated and the column was calibrated according to the following method.
The GPC chromatographic data was taken into a computer at a frequency of 1 point / sec, and the data was processed according to the description in Chapter 4 of "Size Exclusion Chromatography" written by Sadao Mori and published by Kyoritsu Publishing Co., Ltd., and the Mw value was calculated.
The column was calibrated by Showa Denko's monodisperse polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28. A series of monodisperse polystyrene measurements were performed using 0.2 mg / ml solutions of each of .5, S-5.05), n-eicosan and n-tetracontane, and the log of their elution peak times and molecular weights. The calibration curve was obtained by fitting the relationship with a fourth-order polypoly.
The molecular weight of polystyrene (MPS) was converted to the molecular weight of polyethylene (MPE) using the following formula. MPE = 0.468 x MPS

(5) Gel fraction (%)
The cross-linked polyethylene sheet was measured according to JIS K6769: 2013. For convenience, the measurement was performed on a crosslinked polyethylene resin composition molded into a sheet shape, but the same result can be obtained when the measurement is performed on a tube-shaped molded product.

(6) Fracture time in high temperature tensile creep test (80 ° C, load 3.5 kg):
The test piece is a 2 mm flat plate (sheet) made of a crosslinked polyethylene resin composition, and a No. 2 dumbbell specified in JIS K7115: 2015 is used. A creep test was carried out until the test piece broke, and the rupture time was measured. The superiority of creep performance in this evaluation correlates with the superiority of creep tests using pipes.

(7) Surface smoothness:
About the polyethylene resin composition before cross-linking, a sheet of 50 mm × 50 mm × 1 mmt was prepared by hot pressing, the sheet was set in a biaxial stretching / stretching machine equipped with a heating oven, and the sheet was held at 155 ° C. for 10 minutes, and then the stretching ratio was 1.5. Biaxial stretching was performed until it was doubled. Immediately after stretching, the oven was released, the sheet was cooled, the sheet was taken out from the biaxial stretching / stretching machine, and the surface condition was observed. The surface was visually confirmed, and those with no bumps and good surface smoothness were rated as good "○", and those with bumps were rated as "x". It is known that in the material of "x" in this evaluation method, lumps appear on the surface of the pipe in pipe molding, and a problem occurs in the surface smoothness of the pipe.

(8) Extrudability:
Regarding the polyethylene resin composition before cross-linking, those having an HLMFR (190 ° C./21.6 kg) of 35 g / 10 min or more have good extrusion properties, and those having an HLMFR (190 ° C./21.6 kg) of less than 35 g / 10 min. Was marked as "x" with poor extrudability.

2. Material used in Example 1 (1) Ethylene-based copolymer (A)
<Manufacturing of metallocene catalyst A>
A cylindrical flask equipped with an induction stirrer fully substituted with nitrogen was filled with 3 g of silica having an average particle size of 11 μm (average particle size 11 μm, surface area 313 m ² / g, pore volume 1.6 cm ^{3 / g).} 75 ml of toluene was added, and the mixture was heated to 75 ° C. in an oil bath.
In another flask, 8.0 ml of a toluene solution of methylaluminoxane (3.0 mol-Al / L manufactured by Albemarle Corporation) was taken.
Dimethylsilylenebis [1,1'-{2- (2- (5-methyl) frill) -4- (p-isopropylphenyl) -indenyl}] Zirconium dichloride (63.4 mg, 75 μmol) in toluene (15 ml) Was added to a toluene solution of methylarmoxane at room temperature, the temperature was raised to 75 ° C., and the mixture was stirred for 1 hour.
Next, this toluene solution was added to a toluene slurry of silica heated to 75 ° C. with stirring, and the mixture was held for 1 hour.
Then, 175 ml of n-hexane was added while stirring at 23 ° C., and after 10 minutes, stirring was stopped and the mixture was allowed to stand.
After the catalyst was sufficiently precipitated, the supernatant was removed and 200 ml of n-hexane was added.
After stirring once, the mixture was allowed to stand again to remove the supernatant.
This operation was repeated 3 times to remove the component liberated in n-hexane.
Further, the solvent was distilled off by reducing the pressure while heating at 40 ° C.
After the degree of reduced pressure became 0.8 mmHg or less, drying under reduced pressure was continued for another 15 minutes to obtain a silica-supported metallocene catalyst A.

<Manufacturing of anti-fouling component B>
To 100 mL of xylene, 3 g of n-octylated polyethyleneimine derived from polyethyleneimine (molecular weight 10,000) (0.5 n-octyl groups introduced per monomer unit of polyethyleneimine) and a phosphate ester. 1 g of the compound phytic acid was mixed and stirred at room temperature to form a salt.
Then, 6 g of dioctyl sulfosuccinate magnesium salt was mixed to obtain an antifouling component B.

<Manufacturing of ethylene-based copolymer (A)>
Dehydrated and purified isobutane 115 L / h, triisobutylaluminum 0.13 mol / h, and fouling prevention component B 6 ml / h were supplied to a loop-type slurry reactor having an internal volume of 290 L, and the temperature inside the reactor was set to 90 ° C. While intermittently discharging from the reactor so as to keep the pressure at 4.1 MPaG, ethylene, 1-hexene and hydrogen were supplied, and the molar ratio of 1-hexene to ethylene in the liquid being polymerized was 0.019. The molar ratio of hydrogen to ethylene was adjusted to ^{4.4 × 10 -4.}
Next, the hexane slurry of the metallocene catalyst A diluted to 0.3 g / L with hexane was supplied to the reactor at 3 L / h to start the polymerization, and ethylene was added so that the ethylene concentration in the reactor became 10 vol%. Supplied.
The polyethylene produced was intermittently discharged with isobutane, flushed and then sent to the product silo.
As a result, the ethylene-based copolymer (A) was produced at 11 kg / h, the HLMFR was 0.50 g / 10 minutes, and the density was 0.925 g / cm ³ .
The characteristics of the obtained ethylene-based copolymer (A) are shown in Table 1.

(2) Ethylene polymer (B)
An ethylene polymer (B) having the characteristics shown in Tables 1 and 2 was produced.
The characteristics of the obtained ethylene polymer (B) are shown in Tables 1 and 2.

3. 3. Example and Comparative Example [Example 1]
<Manufacturing and evaluation of polyethylene resin composition for cross-linked polyethylene pipe>
The above ethylene-based copolymer (A) and ethylene-based polymer (B) were melt-mixed at the ratios shown in Table 1 to produce a polyethylene resin composition for cross-linked polyethylene pipes.
The obtained polyethylene resin composition had good extrusion properties and surface smoothness.
Table 1 shows the physical characteristics and evaluation results of the polyethylene resin composition for cross-linked polyethylene pipe.
<Manufacturing and evaluation of cross-linked polyethylene sheet>
To 60 g of the obtained polyethylene resin composition for cross-linked polyethylene pipe, 1.8 ml of a silane coupling agent (KBE-1003; manufactured by Shinetsu Silicone Co., Ltd.) and 0.1 ml of a radical generator (Kayahexa AD; manufactured by Kayaku Akzo) were added. After kneading with a 100 cc small mixer (Laboplast Mill R100 manufactured by Toyo Seiki Seisakusho) at a kneading temperature of 165 ° C. for 3 minutes, 5 parts of silanol condensation catalyst MB (HZ082; manufactured by Mitsubishi Chemical Co., Ltd.) was additionally added and kneaded for 3 minutes. The kneaded resin composition was immediately heat-pressed at a molding temperature of 180 ° C., a pressure of 50 kgf, and a holding time of 5 minutes, and molded into a sheet having a thickness of 150 mm × 150 mm × 2 mm.
Next, the molded sheet was immersed in warm water at 80 ° C. for 24 hours, then stored in a drying oven kept at 50 ° C. for 5 hours and dried to prepare a cross-linked polyethylene sheet.
The obtained cross-linked polyethylene sheet had a high gel fraction and was excellent in high-temperature creep performance.
The evaluation results of the cross-linked polyethylene sheet are shown in Table 1.

[Examples 2 to 8]
According to Example 1, the ethylene-based copolymer (A) and the ethylene-based polymer (B) shown in Table 1 were used, melt-mixed at the ratios shown in Table 1, and used for cross-linked polyethylene pipes in the same manner as in Example 1. A polyethylene resin composition and a cross-linked polyethylene sheet were produced.
The obtained polyethylene resin composition had good surface smoothness and extrudability.
The obtained cross-linked polyethylene sheet was excellent in high temperature creep performance.
The evaluation results of the obtained polyethylene resin composition and the cross-linked polyethylene sheet are shown in Table 1.

[Comparative Example 1]
As a polyethylene resin composition for cross-linked polyethylene pipe, a polyethylene resin composition having the physical properties shown in Table 2 ( ^{Cleorex TM} K4750; manufactured by Asahi Kasei Co., Ltd.) was prepared, and the polyethylene resin composition was used for cross-linked in the same manner as in Example 1. A polyethylene sheet was manufactured.
The polyethylene resin composition obtained in Comparative Example 1 had good surface smoothness and extrudability, but the cross-linked polyethylene sheet obtained in Comparative Example 1 did not have good high-temperature creep performance.
Table 2 shows the evaluation results of the obtained polyethylene resin composition for cross-linked polyethylene pipe and the cross-linked polyethylene sheet.

[Comparative Example 2]
As a polyethylene resin composition for cross-linked polyethylene pipe, a polyethylene resin composition having the physical properties shown in Table 2 (Novatec ^TM HD HJ360; manufactured by Nippon Polyethylene Co., Ltd.) was prepared, and the polyethylene resin composition was used in the same manner as in Example 1. A cross-linked polyethylene sheet was produced.
The polyethylene resin composition obtained in Comparative Example 2 had good surface smoothness and extrudability, but the cross-linked polyethylene sheet obtained in Comparative Example 2 did not have good high-temperature creep performance.
Table 2 shows the evaluation results of the obtained polyethylene resin composition for cross-linked polyethylene pipe and the cross-linked polyethylene sheet.

[Comparative Examples 3 to 6]
The ethylene-based copolymer (A) and the ethylene-based polymer (B) shown in Table 2 were used, melt-mixed at the ratios shown in Table 2, respectively, and the polyethylene resin composition for cross-linked polyethylene pipe and cross-linked polyethylene were cross-linked in the same manner as in Example 1. Manufactured a polyethylene sheet.

The cross-linked polyethylene sheet obtained in Comparative Example 3 was excellent in high-temperature creep performance, but the polyethylene resin composition obtained in Comparative Example 3 was not good in surface smoothness and extrudability.
The cross-linked polyethylene sheets obtained in Comparative Examples 4 to 5 were excellent in high-temperature creep performance, but the polyethylene resin compositions obtained in Comparative Examples 4 to 5 were excellent in surface smoothness but not good in extrudability. There wasn't.
Although the polyethylene resin composition obtained in Comparative Example 6 had good extrusion properties, the surface smoothness was not good, and the cross-linked polyethylene sheet obtained in Comparative Example 6 did not have good high-temperature creep performance.
Table 2 shows the evaluation results of the obtained polyethylene resin composition for cross-linked polyethylene pipe and the cross-linked polyethylene sheet.

The polyethylene resin composition for cross-linked polyethylene pipe of the present invention is easy to install and has good moldability, and the cross-linked polyethylene pipe containing the polyethylene resin composition has good cross-linking efficiency and excellent creep performance (strength) at high temperature. , The surface smoothness is also good.

Claims (4)

It is a polyethylene resin composition and
The polyethylene resin composition contains an ethylene-based polymer (A) and an ethylene-based polymer (B) containing one or more ethylene-based polymer components having a higher density than the ethylene-based copolymer (A). ,
The ethylene-based copolymer (A) is a copolymer of ethylene polymerized using a metallocene catalyst and an α-olefin having 3 to 20 carbon atoms, and has an HLMFR (A) of 0.2 to 1. ^{The density (A) is 0.915 to 0.930 g / cm 3} at 5 g / 10 minutes, and the density (A) is 0.915 to 0.930 g / cm 3.
The polyethylene resin composition contains 15 parts of the ethylene-based copolymer (A) per 100 parts by mass of the ethylene-based copolymer (A) and the ethylene-based polymer (B) in the polyethylene resin composition. Including ~ 40 parts by mass
The polyethylene resin composition is a polyethylene resin composition for cross-linked polyethylene pipes, which satisfies the following properties (1) to (3).
Characteristics (1): The melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg is 35 to 150 g / 10 minutes.
Characteristics (2): density exceeds 0.943 g / cm ^3, is 0.955 g / cm ³ or less.
Property (3): 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 9 to 25. The polyethylene resin composition for a cross-linked polyethylene tube according to claim 1 , wherein the ethylene-based copolymer (A) is polymerized using a metallocene catalyst having a cyclopentadienyl ring and a heterocyclic aromatic group. The polyethylene resin composition contains 60 to 85 parts by mass of the ethylene-based polymer (B) per 100 parts by mass in total of the ethylene-based copolymer (A) and the ethylene-based polymer (B).
The ethylene-based polymer (B) is at least one of an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and is melted at a temperature of 190 ° C. and a load of 2.16 kg. The polyethylene resin composition for a crosslinked polyethylene tube according to claim 1 or 2 , wherein the flow rate (MFR (B)) is 1 to 100 g / 10 minutes and the density (B) is 0.946 to 0.975 g / cm ^3. thing. The polyethylene resin composition according to any one of claims 1 to 3 is included.
A cross-linked polyethylene pipe characterized in that a rupture time in a high-temperature tensile creep test (80 ° C., load 3.5 kg) on a cross-linked polyethylene sheet exceeds 1000 hours.