Piping material for ultrapure water and polyethylene resin composition for ultrapure water piping material

Abstract

To provide a polyethylene-based resin composition for a piping material for ultrapure water which has reduced amount of calcium eluted therefrom, has a small shrinkage anisotropy ratio, and is excellent in mechanical characteristics.SOLUTION: A polyethylene-based resin composition for a piping material for ultrapure water is provided, satisfying characteristics (1) to (4). (1) Melt flow rate (MFR21.6) at a temperature of 190°C and a load of 21.6 kg is 6 g / 10 min or more and 25 g / 10 min or less, (2) density is 0.946 g / cm3 or more and 0.960 g / cm3 or less, (3) in molecular weight distribution measured by GPC, Mz / Mw is 2.5 or more and 5.5 or less, (4) concentration of included calcium is 100 ppm or less, and (5) the polyethylene-based resin composition includes, as a polymer component, 20 wt.% or more and 50 wt.% or less of a homopolymer of ethylene or a copolymer of the ethylene and α-olefin having 3 to 12 carbon atoms, wherein the ethylene has an MFR21.6 of 0.2 g / 10 min or more and 1.0 g / 10 min or less and a density of 0.910 g / cm3 or more and 0.935 g / cm3 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a piping material for ultrapure water and a polyethylene resin composition for ultrapure water piping material. More specifically, the present invention relates to polyethylene resin pipes, fittings, valves, etc. used as piping materials for ultrapure water, and a polyethylene resin composition for ultrapure water piping material. [Background technology]

[0002] Conventionally, in the manufacture of precision devices such as semiconductor devices or liquid crystal display devices, ultrapure water refined to an extremely high purity has been used in wet processes such as cleaning. If metal ions or the like are present in the water at a concentration above a certain level, the metals will be adsorbed onto the wafer surface or the like, adversely affecting the quality of the precision device, and therefore, strict restrictions are being put into place on the impurities in the ultrapure water.

[0003] Impurities can also get mixed into ultrapure water in the piping that makes up the ultrapure water transport line. Metals such as stainless steel, which have excellent gas barrier properties, have been used as piping materials, but considering the impact of metal elution from the piping, it is considered preferable to use resin.

[0004] Resins used as materials for ultrapure water piping are fluororesins, which are chemically inert, have gas barrier properties, and are extremely unlikely to leach into ultrapure water. For example, fluororesin double-layered tubes, in which two layers of fluororesin are laminated, are used as piping for semiconductor manufacturing equipment, liquid crystal manufacturing equipment, etc. Examples of fluororesin double-layered tubes include those in which the inner layer tube is made of a fluororesin with excellent corrosion resistance and chemical resistance (e.g., tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or tetrafluoroethylene-ethylene copolymer (ETFE)) and the outer layer tube is made of a fluororesin that can suppress gas permeation (e.g., polyvinylidene fluoride (PVDF)).

[0005] Patent Document 1 also discloses a multi-layer pipe for piping ultrapure water, characterized in that it comprises a first resin layer made of fluororesin that comes into contact with the ultrapure water, and a second resin layer made of gas-impermeable resin that is provided on the outer circumferential surface of the first resin layer. It further discloses that a third resin layer that protects the second resin layer is provided on the outer circumferential surface of the second resin layer, and that polyethylene is used for the third resin layer.

[0006] Among the resins used for ultrapure water piping materials, polyvinylidene fluoride (PVDF) is used in all practical applications in the semiconductor industry, such as piping within ultrapure water production equipment and piping for transporting ultrapure water from the equipment to use points, and has become the technical standard for ultrapure water piping materials.

[0007] Recently, with the increasing integration density of semiconductor chips, circuit patterns have become increasingly finer, making them more susceptible to even low-level impurities. As a result, the quality requirements for ultrapure water have become increasingly strict. For example, the standard for the quality of ultrapure water used in semiconductor manufacturing has been published as SEMI F75, which is updated every two years. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-234576 Summary of the Invention [Problem to be solved by the invention]

[0009] Fluororesin piping such as PVDF has some disadvantages in terms of workability and cost compared to other common piping, but with the demands for ultrapure water quality becoming stricter, fluororesin piping is effectively the only option that meets the required water quality.

[0010] The present inventors have deliberately focused on alternative materials for piping materials for ultrapure water. For example, polyethylene-based resins, which are excellent in workability and cost, are commonly used as piping materials. However, polyethylene-based resins, which are commonly used as piping materials, are synthesized by polymerization using a chlorine-based catalyst such as a Ziegler catalyst, and require the addition of a neutralizing agent such as calcium stearate to neutralize the catalyst residue after polymerization. Furthermore, among neutralizing agents, fatty acid metal soaps such as calcium stearate not only neutralize chlorine but also exhibit a lubricating effect on molds. Therefore, they are commonly added to piping materials as a surface smoothness improver, regardless of the type of polyethylene polymerization catalyst. For this reason, typical polyethylene-based resin pipes leach a large amount of calcium from the neutralizing agent into the water they transport, making them far below the water quality required for ultrapure water. On the other hand, polyethylene resins, which are commonly used as general piping materials, have a large shrinkage after solidification, and because the shrinkage rate differs depending on the resin flow direction during molding, the shrinkage anisotropy, which is the ratio of the flow direction to the direction perpendicular to the flow, is large, making it difficult to obtain the perfect circular shape required for piping materials. Normally, to achieve a perfect circular shape in piping materials using polyethylene resins, it is known to knead in a pigment that exhibits a crystal nucleating agent effect in order to control the shrinkage of the polyethylene resin. However, when considering piping materials for ultrapure water, kneading in a pigment into polyethylene resins raises concerns that trace metals derived from the pigment and wax components used as a pigment dispersant will leach out, which could worsen the quality of the ultrapure water.

[0011] An object of the present invention is to provide a piping material for ultrapure water, which reduces calcium elution, has a small anisotropic shrinkage coefficient, and is provided with mechanical properties and dimensional stability after molding that are sufficiently excellent for use in a pressure pipe system, and a polyethylene resin composition for such a piping material. [Means for solving the problem]

[0012] As a result of extensive research, the inventors have found that the amount of calcium elution can be significantly reduced by controlling the calcium concentration of the polyethylene resin in contact with ultrapure water on the inner wall of the polyethylene resin piping material to a specific range, and by limiting the structure of the phenolic antioxidant, if any, to a specific type. They have also found that controlling the MFR, molecular weight, and molecular weight distribution of the polyethylene resin to specific ranges can reduce the shrinkage anisotropy and achieve long-term strength.

[0013] That is, the present disclosure provides the following aspects.

[0014] The polyethylene resin composition for ultrapure water piping material according to the first aspect is a polyethylene resin composition used for ultrapure water piping material, which contains a polyethylene resin and satisfies the following properties (1) to (5):

[0015] Property (1): Melt flow rate (MFR) at a temperature of 190°C and a load of 21.6 kg 21.6 ) is between 6g / 10min and 25g / 10min.

[0016] Property (2): Density is 0.946 g / cm 3 More than 0.960g / cm 3 The following is the result.

[0017] Property (3): In the molecular weight distribution measured by GPC, Mz / Mw, which is an index showing the breadth of the molecular weight distribution, is 2.5 or more and 5.5 or less.

[0018] Property (4): The calcium concentration contained in the polyethylene resin composition is 100 ppm or less.

[0019] Property (5): MFR as a high molecular weight component 21.6 is 0.2g / 10min or more and 1.0g / 10min or less, density is 0.910g / cm 3 More than 0.935g / cm 3The polymer contains 20% by weight or more and 50% by weight or less of an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, which is as follows:

[0020] The polyethylene resin composition for ultrapure water piping material according to the second aspect is the polyethylene resin composition according to the first aspect, in which components having a molecular weight of 3,000,000 or more account for 2% or less of the total in the molecular weight distribution measured by GPC.

[0021] The polyethylene resin composition for ultrapure water piping material according to the third aspect is the polyethylene resin composition for ultrapure water piping material according to the second aspect, and has a fracture time of 100 hours or more in an FNCT test (measured at 80°C and 5 MPa).

[0022] The polyethylene resin composition for ultrapure water piping material according to the fourth aspect is the polyethylene resin composition for ultrapure water piping material according to the third aspect, and further contains an antioxidant.

[0023] A polyethylene resin composition for ultrapure water piping material according to a fifth aspect is the polyethylene resin composition for ultrapure water piping material according to the fourth aspect, wherein the antioxidant includes a phenolic antioxidant that does not contain oxygen derived from groups other than phenol groups.

[0024] A polyethylene resin composition for ultrapure water piping material according to a sixth aspect is the polyethylene resin composition for ultrapure water piping material according to the fourth aspect, wherein the antioxidant includes a phenolic antioxidant having oxygen derived from a group other than a phenol group, and the calcium concentration is 50 ppm or less.

[0025] The polyethylene resin composition for ultrapure water piping material according to the seventh aspect is the polyethylene resin composition for ultrapure water piping material according to any one of the first to sixth aspects, and does not substantially contain a stabilizer.

[0026] An eighth aspect of the present invention relates to a piping material for ultrapure water, which is a piping material molded from the polyethylene resin composition for ultrapure water piping material according to any one of the first to seventh aspects.

[0027] The ultrapure water piping material according to a ninth aspect is the ultrapure water piping material according to the eighth aspect, in which the thickness of the layer containing polyethylene resin as a main component is 0.3 mm or more.

[0028] The ultrapure water piping material according to a tenth aspect is the ultrapure water piping material according to the ninth aspect, in which the thickness of the layer containing polyethylene resin as a main component is 2.0 mm or less. [Effects of the Invention]

[0029] According to the present invention, it is possible to provide a piping material for ultrapure water that reduces calcium elution and has mechanical properties and dimensional stability after molding, and a polyethylene resin composition for use as a piping material for ultrapure water. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic cross-sectional view showing a pipe as an example of a piping material for ultrapure water according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of a pipe for ultrapure water piping material according to an embodiment of the present invention. [Figure 3A] 1 is a diagram showing a joint of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 3B] 1 is a diagram showing a joint of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 3C] 1 is a diagram showing a joint of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 3D] 1 is a diagram showing a joint of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 3E] 1 is a diagram showing a joint of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 4] 1 is a diagram showing a valve of an example of a piping material for ultrapure water in an embodiment of the present invention. [Figure 5] This is the structural formula of Irganox1010. [Figure 6] This is the structural formula of Irganox1330. DETAILED DESCRIPTION OF THE INVENTION

[0031] The following describes ultrapure water piping materials according to embodiments of the present invention. The term "ultrapure water piping materials" refers to the general term for components that make up ultrapure water piping, including pipes, joints, valves, and the like.

[0032] [Pipe configuration] The tube of this embodiment will be described below.

[0033] The pipe of this embodiment has a polyethylene resin layer that forms the inner surface of the pipe and is mainly composed of a polyethylene resin. If necessary, a coating resin layer may be provided on the outside of the polyethylene resin layer.

[0034] Fig. 1 is a schematic cross-sectional view showing an example of a tube according to the present embodiment, and Fig. 2 is a schematic cross-sectional view showing another example of a tube according to the present embodiment.

[0035] A pipe 10 (an example of a piping material for ultrapure water) shown in Fig. 1 includes a polyethylene-based resin layer 21 (an example of a layer). A pipe 11 (an example of a piping material for ultrapure water) shown in Fig. 2 includes a polyethylene-based resin layer 21 that forms the innermost layer and a coating resin layer 22 disposed on the outer side thereof.

[0036] The pipe 10 shown in Fig. 1 is formed of a polyethylene-based resin layer 21. The polyethylene-based resin layer 21 forms an inner surface 10a (an example of the inner surface of a piping material) of the pipe 10. The outer surface 10b of the pipe 10 shown in Fig. 1 is also formed of the polyethylene-based resin layer 21. The polyethylene-based resin layer 21 is formed in a cylindrical shape to constitute the pipe 10.

[0037] 2, the polyethylene-based resin layer 21 forms the inner surface 11a (an example of the inner surface of a piping material) of the pipe 11. In the pipe 11 shown in FIG. 2, the outer surface 11b is formed of a coating resin layer 22. The polyethylene-based resin layer 21 is formed in a cylindrical shape so as to constitute the innermost layer of the pipe 11. The coating resin layer 22 is formed in a cylindrical shape so as to cover the polyethylene-based resin layer 21.

[0038] In addition, in the pipe 11 shown in Figure 2, only one coating resin layer 22 is provided on the outside of the polyethylene-based resin layer 21, but the number of layers of the coating resin layer 22 is not particularly limited, and it may be one layer or two or more layers.

[0039] The inner surfaces 10a and 11a face the flow paths 10c and 11c inside the pipes 10 and 11, and can be said to be surfaces that may come into contact with ultrapure water.

[0040] [Fitting Configuration] The joint of this embodiment will be described below.

[0041] The joints of the present invention are not particularly limited, but include sockets, elbows, tee's, flanges, and the like.

[0042] 3A to 3E are diagrams showing examples of the joint of this embodiment.

[0043] 3A is a socket into which pipes are inserted from both ends to connect the two pipes in a straight line. The joint 31 is, for example, an electrofusion joint.

[0044] The joint 32 shown in FIG. 3B is an elbow, for example, for connecting pipes at a right angle.

[0045] The joint 33 shown in Figure 3C is a tee joint. The joint 33 connects three pipes at 90-degree intervals.

[0046] 3D is a flange. The joint 34 has a flange portion 34d and is connected to a valve or the like.

[0047] 3E is a reducer that connects two pipes of different diameters in a straight line.

[0048] The above-described pipe configurations can be applied to the configurations of the joints 31 to 35 shown in Figures 3A to 3E, and the cross-sectional shapes are similar to those of the above-described pipe configurations (see Figures 1 and 2). That is, the joints 31 to 35 all have a polyethylene-based resin layer 21 that forms the inner surfaces 31a to 35a that face the flow path. A coating resin layer 22 may be provided on the outside of the polyethylene-based resin layer 21.

[0049] [Valve configuration] The valve of this embodiment will be described below.

[0050] The valve of the present embodiment is not particularly limited, but examples thereof include a diaphragm valve, a ball valve, a butterfly valve, a globe valve, a gate valve, and a check valve.

[0051] FIG. 4 shows a butterfly valve as an example of a valve. The butterfly valve 40 shown in FIG. 4 includes a valve body 41, a seat ring 42, a valve stem (not shown), a valve disc 43, and a handle 44. The valve body 41 is disposed between pipe members through which a fluid flows. A through-hole is formed in the valve body 41. The seat ring 42 is attached to the inner circumferential surface of the through-hole in the valve body 41. The valve disc 43 is fixed to the valve stem and rotates with the rotation of the valve stem, compressing the seat ring 42 and thereby blocking a flow path 41a formed inside the seat ring 42. The valve stem is rotated by rotating the handle 44.

[0052] The above-described pipe configuration can be applied to the configuration of the above-described seat ring 42, and the cross-sectional shape is the same as the above-described pipe configuration (see FIGS. 1 and 2). That is, the seat ring 42 has a polyethylene-based resin layer 21 that forms an inner surface 42a facing the flow path 41a. A coating resin layer 22 may be provided on the outside of the polyethylene-based resin layer 21.

[0053] [Polyethylene resin layer] As long as the polyethylene resin composition used in the polyethylene resin layer 21 satisfies the range specified in the present invention, it may be a composition obtained by polymerizing a single ethylene polymer in a single polymerization vessel, by polymerizing a plurality of ethylene polymers in series or in parallel in succession, or by polymerizing a plurality of ethylene polymers separately and then mixing them.

[0054] The polyethylene resin may be copolymerized with an α-olefin, if necessary. Examples of the α-olefin to be copolymerized with the polyethylene resin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene-1-hexene, 1-butene-4-methyl-1-pentene, and 1-butene-1-octene.

[0055] Polyethylene resins are polymerized using catalysts that include one or more transition metal derivatives.

[0056] The Ziegler catalyst used in this embodiment is well known, and for example, the catalyst systems described in Japanese Patent Laid-Open Nos. 53-78287, 54-21483, 55-71707, and 58-225105 are used.

[0057] Specifically, a catalyst system can be mentioned which comprises a solid catalyst component obtained by contacting a tetravalent titanium compound with a co-ground product obtained by co-grounding aluminum trihalide, an organosilicon compound having an Si-O bond, and a magnesium alcoholate, and an organoaluminum compound.

[0058] The solid catalyst component preferably contains 1 to 15% by weight of titanium atoms. Preferred organosilicon compounds include those having a phenyl group or an aralkyl group, such as diphenyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triphenylethoxysilane, and triphenylmethoxysilane.

[0059] In producing the co-ground product, the proportions of aluminum trihalide and organosilicon compound used per mole of magnesium alcoholate are generally 0.02 to 1.0 moles, preferably 0.05 to 0.20 moles, and the molar ratio of aluminum atoms in the aluminum trihalide to silicon atoms in the organosilicon compound is preferably 0.5 to 2.0.

[0060] To produce the co-ground product, a conventional method may be applied using a mill such as a rotary ball mill, a vibrating ball mill, or a colloid mill, which are commonly used in producing this type of solid catalyst component. The average particle size of the obtained co-ground product is usually 50 to 200 μm, and the specific surface area is usually 20 to 200 m. 2 / g.

[0061] The co-ground product thus obtained is contacted with a tetravalent titanium compound in the liquid phase to obtain a solid catalyst component. The organoaluminum compound used in combination with the solid catalyst component is preferably a trialkylaluminum compound, such as triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, or tri-i-butylaluminum.

[0062] The metallocene catalyst used in the present embodiment is a catalyst containing the following catalyst component (A) and catalyst component (B), and optionally in combination with catalyst component (C). Catalyst component (A): metallocene compound Catalyst component (B): a compound that reacts with catalyst component (A) to form a cationic metallocene compound. Catalyst component (C): fine particle support

[0063] (1) Catalyst component (A) The catalyst component (A) is a metallocene compound of a transition metal of Group 4 of the periodic table, specifically, a compound represented by the following general formulas (I) to (VI). (C5H 5-a R 1a )(C5H 5-b R 2 b )MXY (I) Q(C5H 4-c R 1 c )(C5H 4-d R 2 d )MXY (II) Q'(C5H 4-e R 3 e )ZMXY (III) (C5H 5-f R 3 f )ZMXY (IV) (C5H 5-f R 3 f )MXYW (V) Q”(C5H 5-g R 4 g )(C5H 5-h R 5 h )MXY (VI)

[0064] Here, Q represents a bonding group that bridges two conjugated five-membered ring ligands, Q' represents a bonding group that bridges the conjugated five-membered ring ligand and the Z group, and Q" represents a bonding group that bridges R 4 and R 5 M represents Ti, Zr, or Hf; X, Y, and W each independently represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an oxygen-containing hydrocarbon group having 1 to 20 carbon atoms, a nitrogen-containing hydrocarbon group having 1 to 20 carbon atoms, a phosphorus-containing hydrocarbon group having 1 to 20 carbon atoms, or a silicon-containing hydrocarbon group having 1 to 20 carbon atoms; and Z represents 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 hydrocarbon group having 1 to 40 carbon atoms.

[0065] R 1 ~R 5each independently represents a hydrocarbon group having 1 to 20 carbon atoms, a halogen group, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group, an aryloxy group, an oxygen-containing hydrocarbon group, 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. 1 , 2 R 2 , 2 R 3 , 2 R 4 , or two R 5 may be bonded to each other to form a ring having 4 to 10 carbon atoms. In addition, a, b, c, d, e, f, g, and h are integers that satisfy the following conditions: 0≦a≦5, 0≦b≦5, 0≦c≦4, 0≦d≦4, 0≦e≦4, 0≦f≦5, 0≦g≦5, and 0≦h≦5.

[0066] A bonding group Q bridging two conjugated five-membered cyclic ligands, a bonding group Q′ bridging a conjugated five-membered cyclic ligand and a Z group, and R 4 and R 5 Specific examples of Q″ that crosslinks the following include:

[0067] That is, alkylene groups such as methylene and ethylene groups, alkylidene groups such as ethylidene, propylidene, isopropylidene, phenylmethylidene and diphenylmethylidene groups, silicon-containing crosslinking groups such as dimethylsilylene, diethylsilylene, dipropylsilylene, diphenylsilylene, methylethylsilylene, methylphenylsilylene, methyl-t-butylsilylene, disilylene and tetramethyldisilylene groups, germanium-containing crosslinking groups, alkylphosphines, amines, etc. Of these, alkylene groups, alkylidene groups, silicon-containing crosslinking groups and germanium-containing crosslinking groups are particularly preferred.

[0068] Specific examples of Zr complexes represented by the above general formulas (I), (II), (III), (IV), (V) and (VI) are shown below, but compounds in which Zr is replaced by Hf or Ti can also be used. The catalyst component (A) represented by general formulas (I), (II), (III), (IV), (V) and (VI) can be a compound represented by the same general formula or a mixture of two or more compounds represented by different general formulas.

[0069] Compounds of general formula (I): Biscyclopentadienylzirconium dichloride, bis(2-methylindenyl)zirconium dichloride, bis(2-methyl-4,5-benzoindenyl)zirconium dichloride, bisfluorenylzirconium dichloride, bis(4H-azulenyl)zirconium dichloride, bis(2-methyl-4H-azulenyl)cyclopentadienylzirconium dichloride, bis(2-methyl-4-phenyl-4H-azulenyl)zirconium dichloride, bis(2-methyl-4-(4-chlorophenyl)-4H-azulenyl)zirconium dichloride. Bis(2-furylcyclopentadienyl)zirconium dichloride, bis(2-furylindenyl)zirconium dichloride, bis(2-furyl-4,5-benzoindenyl)zirconium dichloride.

[0070] Compounds of general formula (II): Dimethylsilylenebis(1,1'-cyclopentadienyl)zirconium dichloride, dimethylsilylenebis[1,1'-(2-methylindenyl)]zirconium dichloride, dimethylsilylenebis[1,1'-(2-methylindenyl)]zirconium dichloride, ethylenebis[1,1'-(2-methyl-4,5benzoindenyl)]zirconium dichloride, dimethylsilylenebis[1,1'-(2-methyl-4-hydroazulenyl)]zirconium dichloride, Dimethylsilylenebis[1,1'-(2-methyl-4-phenyl-4-hydroazulenyl)]zirconium dichloride, dimethylsilylenebis{1,1'-[2-methyl-4-(4-chlorophenyl)-4-hydroazulenyl]}zirconium dichloride, dimethylsilylenebis[1,1'-(2-ethyl-4-phenyl-4-hydroazulenyl)]zirconium dichloride, ethylenebis[1,1'-(2-methyl-4-hydroazulenyl)]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)furyl]-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, isopropyl 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, diphenylsilylene(cyclopentadienyl)[9-(2,7-t-butyl)fluorenyl]zirconium dichloride.

[0071] Compounds of general formula (III): (tertiary butylamide)(tetramethyl-η 5 -cyclopentadienyl)-1,2-ethanediylzirconium dichloride, (methylamido)-(tetramethyl-η 5 -cyclopentadienyl)-1,2-ethanediyl-zirconium dichloride, (ethylamido)(tetramethyl-η 5 -cyclopentadienyl)-methylenediylkonium dichloride, (tert-butylamido)dimethyl-(tetramethyl-η 5 -Cyclopentadienyl)silane zirconium dichloride, (tert-butylamido)dimethyl(tetramethyl-η 5 -Cyclopentadienyl)silane zirconium dibenzyl, (benzylamido)dimethyl (tetramethyl-η 5 -Cyclopentadienyl)silane zirconium dichloride, (phenylphosphide)dimethyl (tetramethyl-η 5 -cyclopentadienyl)silane zirconium dibenzyl.

[0072] Compounds 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, (pentamethylcyclo Pentadienyl)(2,6-di-i-propylphenoxy)zirconium dichloride.

[0073] Compounds of general formula (V): (Cyclopentadienyl)zirconium trichloride, (2,3-dimethylcyclopentadienyl)zirconium trichloride, (pentamethylcyclopentadienyl)zirconium trichloride, (cyclopentadienyl)zirconium triisopropoxide, (pentamethylcyclopentadienyl)zirconium triisopropoxide.

[0074] Compounds of general formula (VI): Ethylene bis(7,7'-indenyl)zirconium dichloride, dimethylsilylene bis{7,7'-(1-methyl-3-phenylindenyl)}zirconium dichloride, dimethylsilylene bis{7,7'-[1-methyl-4-(1-naphthyl)indenyl]}zirconium dichloride, dimethylsilylene bis[7,7'-(1-ethyl-3-phenylindenyl)]zirconium dichloride, dimethylsilylene bis{7,7'-[1-isopropyl-3-(4-chlorophenyl)indenyl]}zirconium dichloride.

[0075] In addition, compounds in which the silylene group of these specific examples is replaced with a germylene group are also exemplified as suitable compounds. Among the catalyst components (A) described above, preferred metallocene complexes for producing a polyethylene resin component are those represented by general formula (I) or general formula (II), and more preferably, the metallocene complex represented by general formula (II) is preferred from the viewpoints of being capable of producing high molecular weight polymers and exhibiting excellent copolymerizability in copolymerization of ethylene with other α-olefins. The ability to produce high molecular weight polymers has the advantage that polymers of various molecular weights can be designed by various polymer molecular weight adjustment techniques as described below. Among the metallocene complexes represented by general formula (II), the following two compound groups are preferred in order to satisfy the properties of the polyethylene resin of the present embodiment.

[0076] In a preferred embodiment, the first group of compounds is R 1 ~R 2The present invention relates to a bridged metallocene complex containing at least one heterocyclic aromatic group within the compound. Preferred heterocyclic aromatic groups include a group consisting of a furyl 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 furyl group, a benzofuryl group, a thienyl group, and a benzothienyl group, a furyl group and a benzofuryl group are more preferred. Furthermore, it is preferred that these substituents are introduced at the 2-position of a substituted cyclopentadienyl group or a substituted indenyl group, and a compound having at least one substituted cyclopentadienyl group that does not have any other fused ring structure is particularly preferred.

[0077] The second group of compounds is bridged metallocene complexes that combine a substituted cyclopentadienyl group with a substituted fluorenyl group.

[0078] (2) Catalyst component (B) The method for producing an ethylene-α-olefin copolymer in this embodiment is characterized in that, in addition to the above-mentioned catalyst component (A), the olefin polymerization catalyst contains, as essential components, a compound (catalyst component (B), hereinafter sometimes simply referred to as "B") that reacts with the metallocene compound of catalyst component (A) (hereinafter sometimes referred to as "component (A)" or simply "A") to form a cationic metallocene compound, and, if necessary, a fine particle carrier (catalyst component (C), hereinafter sometimes simply referred to as "C").

[0079] One example of the catalyst component (B) that reacts with the catalyst component (A) to form a cationic metallocene compound is an organoaluminum oxy compound. The organoaluminum oxy-compound has an Al-O-Al bond in the molecule, and the number of 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 of organoaluminum with water is usually carried out in an inert hydrocarbon (solvent), which may be an aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, or xylene, but is preferably an aliphatic hydrocarbon or aromatic hydrocarbon.

[0080] The organoaluminum compound used in the preparation of the organoaluminum oxy-compound may be any compound represented by the following general formula (4), but trialkylaluminum is preferably used. R 5 t AlX 3 3-t (4) (In the formula, R 5 represents a hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, such as an alkyl group, an alkenyl group, an aryl group, or an aralkyl group; X 3 represents a hydrogen atom or a halogen atom, and t represents an integer of 1≦t≦3.

[0081] The alkyl group of the trialkylaluminum may be any of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl, decyl, and dodecyl groups, with methyl being particularly preferred. The organoaluminum compounds may be used in combination of two or more.

[0082] The reaction ratio of water to the organoaluminum compound (water / Al molar ratio) is preferably 0.25 / 1 to 1.2 / 1, particularly preferably 0.5 / 1 to 1 / 1, and the reaction temperature is usually in the range of -70 to 100°C, preferably -20 to 20°C. The reaction time is usually selected in the range of 5 minutes to 24 hours, preferably 10 minutes to 5 hours. The water required for the reaction may not only be simple water, but also water of crystallization contained in copper sulfate hydrate, aluminum sulfate hydrate, etc., or components that can generate water in the reaction system. Among the above-mentioned organoaluminum oxy compounds, those obtained by reacting alkylaluminum with water are usually called aluminoxanes, and methylaluminoxane (including those essentially consisting of methylaluminoxane (MAO)) is particularly suitable as an organoaluminum oxy compound. Of course, two or more of the above-mentioned organoaluminum oxy compounds may be used in combination as the organoaluminum oxy compound, or the organoaluminum oxy compound may be used in the form of a solution or dispersion in the above-mentioned inert hydrocarbon solvent.

[0083] Other specific examples of the catalyst component (B) include borane compounds and borate compounds. More specific examples of the borane compound include 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(perfluoroanthryl)borane, and tris(perfluorobinaphthyl)borane.

[0084] Among these, tris(3,5-ditrifluoromethylphenyl)borane, tris(2,6-ditrifluoromethylphenyl)borane, tris(pentafluorophenyl)borane, tris(perfluoronaphthyl)borane, tris(perfluorobiphenyl)borane, tris(perfluoroanthryl)borane, and tris(perfluorobinaphthyl)borane are more preferred, and tris(2,6-ditrifluoromethylphenyl)borane, tris(pentafluorophenyl)borane, tris(perfluoronaphthyl)borane, and tris(perfluorobiphenyl)borane are even more preferred examples of the compound.

[0085] Furthermore, specifically representing the borate compound, a first example is a compound represented by the following general formula (5). [L 1 -H] + [BR 6 R 7 X 4 X 5 ] - (5)

[0086] In formula (5), L 1 is a neutral Lewis base, H is a hydrogen atom, and [L 1 -H] is a Bronsted acid such as ammonium, anilinium, or 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.

[0087] Examples of anilinium include N,N-dialkylanilinium such as N,N-dimethylanilinium, N,N-diethylanilinium, and N,N-2,4,6-pentamethylanilinium. Further, examples of the phosphonium include triarylphosphoniums and trialkylphosphoniums such as triphenylphosphonium, tributylphosphonium, tri(methylphenyl)phosphonium, and tri(dimethylphenyl)phosphonium.

[0088] In addition, in formula (5), 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 may be linked to each other via a bridging group, and the substituents of the substituted aromatic hydrocarbon groups are preferably alkyl groups typified by methyl, ethyl, propyl, isopropyl, etc., or halogens such as fluorine, chlorine, bromine, and iodine. Additionally, X 4 and X 5 are each independently a hydride group, a halide group, a hydrocarbon group containing 1 to 20 carbon atoms, or a substituted hydrocarbon group containing 1 to 20 carbon atoms in which one or more hydrogen atoms have been substituted with halogen atoms.

[0089] Specific examples of the compound represented by the general formula (5) include 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, ammonium tetra(2,6-ditrifluoromethylphenyl)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, dicyclohexylammonium tetraphenylborate, and the like can be exemplified.

[0090] Among these, tributylammonium tetra(pentafluorophenyl)borate, tributylammonium tetra(2,6-ditrifluoromethylphenyl)borate, tributylammonium tetra(3,5-ditrifluoromethylphenyl)borate, tributylammonium tetra(perfluoronaphthyl)borate, dimethylanilinium tetra(pentafluorophenyl)borate, dimethylanilinium tetra(2,6-ditrifluoromethylphenyl)borate, dimethylanilinium tetra(3,5-ditrifluoromethylphenyl)borate, and dimethylanilinium tetra(perfluoronaphthyl)borate are preferred.

[0091] A second example of the borate compound is represented by the following general formula (6). [L 2 ] + [BR 6 R 7 X 4 X 5 ] - (6)

[0092] In formula (6), L 2 Examples of R include a carbocation, a methyl cation, an ethyl cation, a propyl cation, an isopropyl cation, a butyl cation, an isobutyl cation, a tert-butyl cation, a pentyl cation, a tropinium cation, a benzyl cation, a trityl cation, a sodium cation, and a proton. 6 , R 7 , X 4 and X 5 is the same as defined in the general formula (5).

[0093] Specific examples of the compound represented by the general formula (6) include trityl tetraphenylborate, trityl tetra(o-tolyl)borate, trityl tetra(p-tolyl)borate, trityl tetra(m-tolyl)borate, trityl tetra(o-fluorophenyl)borate, trityl tetra(p-fluorophenyl)borate, trityl tetra(m-fluorophenyl)borate, trityl tetra(3,5-difluorophenyl)borate, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, trityl tetra(3,5-ditrifluoromethylphenyl)borate, trityl tetra(perfluoronaphthyl)borate, tropinium tetraphenylborate, tropinium tetra(o-tolyl)borate, tropinium tetra(p-tolyl)borate, and tropinium tetra(m-tolyl)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, phenyl)borate, tropinium tetra(perfluoronaphthyl)borate, NaBPh4, NaB(o-CH3-Ph)4, NaB(p-CH3-Ph)4, NaB(m-CH3-Ph)4, NaB(oF-Ph)4, NaB(pF-Ph)4, NaB(mF-Ph)4, NaB(3,5-F2-Ph)4, NaB(C6F5)4, NaB(2,6-(CF3)2-Ph)4, NaB(3,5-(CF3)2-Ph)4, NaB(C 10 F7)4, H + BPh4·2 diethyl ether, H + B(3,5-F2-Ph)4·2 diethyl ether, H + B(C6F5)4 - 2-Diethyl ether, H + B(2,6-(CF3)2-Ph)4·2 diethyl ether, H + B(3,5-(CF3)2-Ph)4·2 diethyl ether, H+ B(C 10 H7) 4·2 diethyl ether is an example. Note that "Ph" above represents a phenyl group.

[0094] Among these, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, trityl tetra(3,5-ditrifluoromethylphenyl)borate, trityl tetra(perfluoronaphthyl)borate, tropinium tetra(pentafluorophenyl)borate, tropinium tetra(2,6-ditrifluoromethylphenyl)borate, tropinium tetra(3,5-ditrifluoromethylphenyl)borate, tropinium tetra(perfluoronaphthyl)borate, NaB(CF), NaB(2,6-(CF-Ph), NaB(3,5-(CF-Ph), NaB(CF), NaB(CF). 10 F7)4, H + B(C6F5)4 - 2-Diethyl ether, H + B(2,6-(CF3)2-Ph)4·2 diethyl ether, H + B(3,5-(CF3)2-Ph)4·2 diethyl ether, H + B(C 10 H7) 4·2 diethyl ether is preferred.

[0095] Among these, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, tropinium tetra(pentafluorophenyl)borate, tropinium tetra(2,6-ditrifluoromethylphenyl)borate, NaB(CF), NaB(2,6-(CF-Ph), H + B(C6F5)4 - 2-Diethyl ether, H + B(2,6-(CF3)2-Ph)4·2 diethyl ether, H + B(3,5-(CF3)2-Ph)4·2 diethyl ether, H + B(C 10 H7) 4·2 diethyl ether.

[0096] (3) Catalyst component (C) The particulate support that is the catalyst component (C) can be an inorganic support, a particulate polymer support, or a mixture thereof. The inorganic support can be a metal, a metal oxide, a metal chloride, a metal carbonate, a carbonaceous material, or a mixture thereof. Suitable metals that can be used for the inorganic support include, for example, iron, aluminum, nickel, and the like.

[0097] Furthermore, examples of metal oxides include single oxides or composite oxides of elements in Groups 1 to 14 of the periodic table, such as SiO2, Al2O3, MgO, CaO, BO, TiO2, ZrO2, Fe2O3, Al2O3·MgO, Al2O3·CaO, Al2O3·SiO2, Al2O3·MgO·CaO, Al2O3·MgO·SiO2, Al2O3·CuO, Al2O3·Fe2O3, Al2O3·NiO, and SiO2·MgO. Here, the above formula is not a molecular formula but represents only the composition, and the structure and component ratio of the composite oxide used in this embodiment are not particularly limited. Furthermore, the metal oxide used in this embodiment may absorb a small amount of moisture and may contain a small amount of impurities.

[0098] As the metal chloride, for example, chlorides of alkali metals and alkaline earth metals are preferred, and specifically, MgCl2, CaCl2, etc. are particularly suitable. As the metal carbonate, carbonates of alkali metals and alkaline earth metals are preferred, and specific examples include magnesium carbonate, calcium carbonate, and barium carbonate. Examples of carbonaceous materials include carbon black and activated carbon. Any of the above inorganic carriers can be suitably used in the present disclosure, but metal oxides, silica, alumina, etc. are particularly preferred.

[0099] These inorganic supports are preferably used after being calcined in air or an inert gas such as nitrogen or argon at 200 to 800°C, preferably 400 to 600°C, to adjust the amount of surface hydroxyl groups to 0.8 to 1.5 mmol / g. 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 size 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 700m 2 / g, pore volume 0.3 to 2.5 cm 3 / g, preferably 0.5 to 2.0 cm 3 / g, apparent specific gravity is 0.10 to 0.50 g / cm 3 It is preferable to use an inorganic carrier having the following formula:

[0100] The inorganic supports described above can be used as they are, but they can also be used after being pretreated by contacting them with an organoaluminum compound such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tripropylaluminum, tributylaluminum, trioctylaluminum, tridecylaluminum, or diisobutylaluminum hydride, or an organoaluminum oxy compound containing an Al-O-Al bond.

[0101] In the metallocene catalyst according to the present embodiment, the method for contacting the components when obtaining a catalyst comprising the catalyst component (A), the catalyst component (B), and, if necessary, the catalyst component (C) is not particularly limited, and for example, the following methods can be arbitrarily adopted.

[0102] (I) The catalyst component (A) is contacted with the catalyst component (B), and then the catalyst component (C) is contacted with the catalyst component (B). (II) The catalyst component (A) is contacted with the catalyst component (C), and then the catalyst component (B) is contacted therewith. (III) The catalyst component (B) is contacted with the catalyst component (C), and then the catalyst component (A) is contacted therewith.

[0103] Of these contact methods, (I) and (III) are preferred, with (I) being the most preferred. In any of these contact methods, the components are typically contacted in an inert atmosphere such as nitrogen or argon, with or without stirring, in the presence of a liquid inert hydrocarbon, such as an aromatic hydrocarbon (usually having 6 to 12 carbon atoms) such as benzene, toluene, xylene, or ethylbenzene, or an aliphatic or alicyclic hydrocarbon (usually having 5 to 12 carbon atoms) such as heptane, hexane, decane, dodecane, or cyclohexane. This contact is desirably carried out at a temperature of usually -100°C to 200°C, preferably -50°C to 100°C, and more preferably 0°C to 50°C, for 5 minutes to 50 hours, preferably 30 minutes to 24 hours, and more preferably 30 minutes to 12 hours.

[0104] Furthermore, when catalyst component (A), catalyst component (B) and catalyst component (C) are contacted, as described above, either an aromatic hydrocarbon solvent in which some components are soluble or slightly soluble, or an aliphatic or alicyclic hydrocarbon solvent in which some components are insoluble or slightly soluble, can be used.

[0105] When the contact reactions of the components are carried out stepwise, the solvent used in the previous step may be used as it is in the subsequent contact reaction without removing it. Alternatively, after the previous contact reaction using a soluble solvent, a liquid inert hydrocarbon in which certain components are insoluble or poorly soluble (e.g., an aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon such as pentane, hexane, decane, dodecane, cyclohexane, benzene, toluene, or xylene) may be added to recover the desired product as a solid. Alternatively, after partially or completely removing the soluble solvent by drying or other means to recover the desired product as a solid, the subsequent contact reaction of this desired product may be carried out using one of the above-mentioned inert hydrocarbon solvents. In this embodiment, the contact reactions of the components may be carried out multiple times.

[0106] In the present embodiment, the proportions of catalyst component (A), catalyst component (B) and catalyst component (C) used are not particularly limited, but the following ranges are preferred.

[0107] When an organoaluminum oxy compound is used as catalyst component (B), the atomic ratio (Al / M) of aluminum in the organoaluminum oxy compound to the transition metal (M) in catalyst component (A) is generally 1 to 100,000, preferably 5 to 1000, and more preferably 50 to 200. When a borane compound or a borate compound is used, the atomic ratio (B / M) of boron to the transition metal (M) in the metallocene compound is generally 0.01 to 100, preferably 0.1 to 50, and more preferably 0.2 to 10. Furthermore, when a mixture of an organoaluminum oxy compound, a borane compound, and a borate compound is used as the catalyst component (B), it is desirable to select the use ratio of each compound in the mixture relative to the transition metal (M) in the same manner as above.

[0108] The amount of catalyst component (C) used is 1 g per 0.0001 to 5 mmol, preferably per 0.001 to 0.5 mmol, more preferably per 0.01 to 0.1 mmol of the transition metal in catalyst component (A).

[0109] The catalyst for olefin polymerization can be obtained as a solid catalyst by contacting catalyst components (A), (B), and (C) with each other using any of the contact methods (I) to (III) and then removing the solvent. The solvent is desirably removed at atmospheric 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.

[0110] The metallocene catalyst can also be obtained by the following method. (IV) The catalyst component (A) is contacted with the catalyst component (C) to remove the solvent, and the resulting solid catalyst component is contacted with an organoaluminum oxy compound, a borane compound, a borate compound, or a mixture thereof under polymerization conditions. (V) An organoaluminum oxy compound, a borane compound, a borate compound or a mixture thereof is contacted with catalyst component (C) to remove the solvent, thereby forming a solid catalyst component, which is then contacted with catalyst component (A) under polymerization conditions. In the above contact methods (IV) and (V), the component ratio, contact conditions, and solvent removal conditions can be the same as those described above.

[0111] Furthermore, a layered silicate can also be used as a component that serves as both the catalyst component (B) and the catalyst component (C), which are essential components in the method for producing ethylene-α-olefin copolymerization according to this embodiment. Layered silicates are silicate compounds that have a crystalline structure in which planes formed by ionic bonds or the like are stacked in parallel with each other with weak bonding forces. Most layered silicates occur naturally as the main component of clay minerals, but these layered silicates are not limited to those that are naturally occurring, and may also be artificially synthesized products.

[0112] Among these, smectites, vermiculites, and micas, such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, and taeniolite, are preferred.

[0113] Generally, natural products are often non-ion-exchangeable (non-swellable), and in such cases, it is preferable to subject them to treatment to impart ion-exchangeable (or swellable) properties to give them desirable ion-exchangeable (or swellable) properties. Among such treatments, the following chemical treatments are particularly preferred: Here, the chemical treatment can be either a surface treatment for removing impurities adhering to the surface or a treatment that affects the crystal structure and chemical composition of the layered silicate. Specific examples include (i) acid treatment using hydrochloric acid, sulfuric acid, etc., (ii) alkali treatment using NaOH, KOH, NH3, etc., (iii) salt treatment using salts consisting of a cation containing at least one atom selected from Groups 2 to 14 of the periodic table and at least one anion selected from the group consisting of a halogen atom or an anion derived from an inorganic acid, and (iv) organic treatment using alcohol, hydrocarbon compound, formamide, aniline, etc. These treatments may be performed alone or in combination of two or more.

[0114] The particle properties of the layered silicate can be controlled by pulverization, granulation, sizing, fractionation, etc. at any time before, during, or after any of the steps. Any method suitable for the purpose can be used. In particular, examples of granulation methods include spray granulation, tumbling granulation, compression granulation, stirring granulation, briquetting, compaction, extrusion granulation, fluidized bed granulation, emulsion granulation, and submerged granulation. Of the above, particularly preferred granulation methods are spray granulation, tumbling granulation, and compression granulation.

[0115] The layered silicates described above can be used as they are, but they can also be used in combination with an organoaluminum compound such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, or diisobutylaluminum hydride, or an organoaluminum oxy compound containing an Al-O-Al bond.

[0116] In the metallocene catalyst according to the present embodiment, the catalyst component (A) can be supported on the layered silicate by contacting the catalyst component (A) with the layered silicate, or by contacting the catalyst component (A), the organoaluminum compound, and the layered silicate with each other. The method for contacting the components is not particularly limited, and for example, the following methods can be optionally employed.

[0117] (VI) The catalyst component (A) is contacted with an organoaluminum compound, and then contacted with a layered silicate support. (VII) After the catalyst component (A) is contacted with the layered silicate support, it is contacted with an organoaluminum compound. (VIII) The organoaluminum compound is contacted with the layered silicate support, and then contacted with catalyst component (A).

[0118] Of these contact methods, (VI) and (VIII) are preferred. In either contact method, the components are contacted with or without stirring in an inert atmosphere such as nitrogen or argon, generally in the presence of a liquid inert hydrocarbon, such as an aromatic hydrocarbon (usually having 6 to 12 carbon atoms) such as benzene, toluene, xylene, or ethylbenzene, or an aliphatic or alicyclic hydrocarbon (usually having 5 to 12 carbon atoms) such as heptane, hexane, decane, dodecane, or cyclohexane.

[0119] The proportions of the catalyst component (A), the organoaluminum compound, and the layered silicate support used are not particularly limited, but the following ranges are preferred. The amount of 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 gram of the layered silicate support. When an organoaluminum compound is used, the amount of Al supported is desirably in the range of 0.01 to 100 mol, preferably 0.1 to 50 mol, and more preferably 0.2 to 10 mol.

[0120] The conditions for supporting and removing the solvent can be the same as those for the inorganic carrier described above. When a layered silicate is used as a component that serves as both the catalyst component (B) and the catalyst component (C), the polymerization activity is high and the productivity of the ethylene polymer is improved. The olefin polymerization catalyst thus obtained may be used after prepolymerization of monomers, if necessary.

[0121] As an example of a production method for a metallocene catalyst, the catalyst can be produced by taking into consideration the "catalyst" and "raw material blending ratio and conditions" described in the publicly known publications, for example, JP-A-2002-535339 and JP-A-2004-189869. The index of the polymer can be controlled by various polymerization conditions, for example, by the methods described in JP-A-2-269705 and JP-A-3-21607.

[0122] Examples of the neutralizing agent include fatty acid metal salts such as calcium stearate, zinc stearate, and magnesium stearate, and hydrotalcites.

[0123] However, if polyethylene resin is polymerized using magnesium stearate or hydrotalcite as a neutralizing agent, when the resulting resin is molded into a piping material, a large amount of aluminum and magnesium will dissolve into water, which is not preferred for this embodiment.

[0124] In contrast, when polyethylene resin is polymerized using calcium stearate as a neutralizing agent, the metal elution of aluminum and magnesium as described above does not occur, and favorable low elution properties can be obtained, so calcium stearate is a preferred neutralizing agent in this embodiment.

[0125] High-density polyethylene (HDPE) is preferred as a polyethylene-based resin composition because it provides sufficient pressure resistance against water pressure during water transport and allows for thin pipe walls. Among HDPEs, HDPE classified as PE100 or higher in ISO 9080, ISO 1167, and ISO 12162 is more preferred to ensure the long-term durability of ultrapure water piping materials. Even among HDPEs classified as PE100 or higher, HDPE with high resistance to slow crack growth (slow crack growth resistance) is preferred to further enhance the safety of the pipe system, and HDPE with high fluidity to improve the smoothness of the inner surface of the pipe. Note that slow crack growth refers to a type of damage caused by stress concentration, such as scratches on the piping material or at the joint between the pipe and the fitting.

[0126] As an index of a polyethylene resin composition that satisfies the pressure resistance class of PE100 or more and has good fluidity, specifically, the melt flow rate (MFR) of the polyethylene resin composition at a temperature of 190°C and a load of 21.6 kg is used. 21.6 ) is 6g / 10min or more and 25g / 10min or less, and the density is 0.946g / cm 3 More than 0.960g / cm 3 It is preferable that:

[0127] MFR of polyethylene resin composition 21.6 If the MFR is less than 6g / 10min, the fluidity of the resin material will be low, the mold transferability will be poor, and the smoothness of the inner surface of the pipe will be insufficient. 21.6 If the melt flow rate exceeds 25g / 10min, it becomes difficult to design a resin that satisfies PE100. The density is 0.946g / cm 3 If the density is less than 0.960 g / cm, the pressure resistance performance will decrease and it will be difficult to reach PE100. 3 If the temperature exceeds this value, the resistance to slow cracking of the piping material will decrease, and the safety of the piping system will decrease over the long term.

[0128] Furthermore, if the Mz / Mw ratio of a polyethylene resin composition is less than 2.5, the shrinkage of the material itself will be small, but the difference in relaxation time between the components in the resin composition will be too small, resulting in poor flow during melting, and residual strain will remain in the molded product, resulting in a large anisotropic shrinkage ratio. On the other hand, if the Mz / Mw ratio exceeds 5.5, the resin composition will be more likely to undergo molecular orientation, which will also result in residual strain remaining in the molded product, resulting in a large anisotropic shrinkage ratio. In addition, since molecular orientation tends to occur more frequently during molding as the amount of components with a molecular weight exceeding 3,000,000 exceeds 2% of the total, the anisotropic shrinkage ratio will become even larger.

[0129] The calcium concentration of the polyethylene resin layer 21 is 100 ppm or less, preferably 60 ppm or less, and more preferably 50 ppm or less. If the calcium concentration exceeds 100 ppm, the amount of calcium eluted into the ultrapure water becomes excessive, and the required quality of the ultrapure water cannot be met.

[0130] From the viewpoint of further suppressing the amount of calcium eluted into ultrapure water, it is preferable that the calcium concentration of the polyethylene resin layer 21 is as low as possible.

[0131] The long-term durability required of polyethylene resins is resistance to slow crack growth, and FNCT is a method for measuring this. FNCT is a test method that measures slow crack growth below the material's yield stress. Materials with low long-term durability will fail due to slow crack growth in a much shorter time than creep failure, so it can be used as an indicator of long-term durability. Assuming a typical service life of 40 years for a polyethylene resin pipe at 20°C, the performance required of FNCT is that it should not fail for more than 100 hours when subjected to a stress of 5.0 MPa in an environment of a surfactant solution at 80°C.

[0132] The material properties of the polyethylene resin composition more preferably have a pressure resistance of "PE100" or higher as specified in the ISO 9080, ISO 1167, and ISO 12162 standards. "PE100" refers to polyethylene in which the LPL value, which is the minimum guaranteed stress after 50 years at 20°C estimated by extrapolation using a multiple correlation average after measuring stress-rupture time curves for at least 9,000 hours at three different temperatures, with the maximum and minimum temperatures being at least 50°C apart, is 10 MPa or higher and 11.19 MPa or lower, according to the classification table specified in ISO 12162.

[0133] The polyethylene resin layer 21 may or may not contain an antioxidant. Examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, aromatic amine-based antioxidants, and lactone-based antioxidants.

[0134] Phenolic antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexane-1,6-diylbis[3-(3,5- di-tert-butyl-4-hydroxyphenyl)propionamide], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy, C7-C9 side chain alkyl ester, 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 4,6-bis(dodecylthiomethyl)-o-cresol, 4,6-bis(octyl methylthiomethyl)-o-cresol, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1 ,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-[4,6-bis(octylthio)-1,3,5-triazin-2-ylamino]phenol, and diethyl[{3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl}methyl]phosphonate.

[0135] When a phenolic antioxidant is used, a single type may be used alone, or two or more types may be used in combination. However, from the viewpoint of preventing calcium elution, it is preferable that the antioxidant does not contain oxygen derived from groups other than the phenol group. Examples of the antioxidant include 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 2,6-di-tert-butyl-4-[4,6-bis(octylthio)-1,3,5-triazin-2-ylamino]phenol, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), and 6,6'-di-tert-butyl-4,4'-butylidenebis-m-cresol. Furthermore, when a phenolic antioxidant containing oxygen derived from groups other than the phenol group is used as the antioxidant, the calcium concentration in the polyethylene resin is preferably 50 ppm or less. Examples of functional groups having oxygen derived from groups other than phenol groups include ester groups, carbonyl groups, carboxy groups, ether groups, nitro groups, nitroso groups, amide groups, azoxy groups, and sulfo groups.

[0136] Examples of phosphorus-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite, tris[2-[[2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphen-6-yl]oxy]ethyl]amine, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester phosphorous acid, and tetrakis(2,4-di-tert-butylphenyl)(1,1-biphenyl)-4,4′-diylbisphosphonite.

[0137] Examples of sulfur-based antioxidants include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, and pentaerythrityl tetrakis(3-laurylthiopropionate).

[0138] Examples of aromatic amine antioxidants include monoamine compounds such as diphenylamine compounds, quinoline compounds, and naphthylamine compounds, and diamine compounds such as phenylenediamine compounds and benzimidazole compounds. Diphenylamine compounds include p-(p-toluenesulfonylamido)-diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, and 4,4'-dioctyldiphenylamine derivatives.

[0139] Examples of quinoline compounds include 2,2,4-trimethyl-1,2-dihydroquinoline polymers. Examples of naphthylamine compounds include phenyl-α-naphthylamine and N,N'-di-2-naphthyl-p-phenylenediamine.

[0140] Examples of phenylenediamine compounds include N-N'-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, a mixture of N-N'-diphenyl-p-phenylenediamines, diaryl-p-phenylenediamine derivatives or mixtures thereof.

[0141] Examples of the benzimidazole compound include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, the zinc salt of 2-mercaptobenzimidazole, and the zinc salt of 2-mercaptomethylbenzimidazole.

[0142] Examples of lactone antioxidants include the reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene.

[0143] The content of the antioxidant in the polyethylene resin layer 21 is, from the viewpoint of suppressing the influence of oxygen and ensuring a desirable strength, for example, 0.01% by weight or more, preferably 0.03% by weight or more, and more preferably 0.05% by weight or more, and the upper limit of the content of the antioxidant is, for example, 5% by weight or less, preferably 1% by weight or less, and more preferably 0.5% by weight or less.

[0144] The polyethylene resin layer 21 may or may not contain a light stabilizer, but preferably does not substantially contain a light stabilizer in order to prevent the elution of total organic carbon (TOC). Examples of light stabilizers include hindered amine light stabilizers (HALS). Here, "substantially does not contain" means that light stabilizers are not actively added, but that unavoidable inclusion as impurities is permitted. The lower the concentration of light stabilizers that are inevitably mixed in as impurities, the better, e.g., 600 ppm or less.

[0145] Examples of the hindered amine light stabilizer include NH-type hindered amine compounds, NR-type hindered amine compounds, and N-OR-type hindered amine compounds.

[0146] Examples of NH-type hindered amine compounds include Tinuvin 770DF, Kimassorb 2020FDL, Kimassorb 944FDL (all trade names, manufactured by BASF), Adeka STAB LA-68, Adeka STAB LA-57 (all trade names, manufactured by Adeka Corporation), Cyasorb UV-3346, Cyasorb UV-3853 (all trade names, manufactured by Sun Chemical Company), and the like.

[0147] Examples of the NR-type hindered amine compound include Tinuvin 622SF, Tinuvin 765, Tinuvin PA144, Chimassorb 119, and Tinuvin 111 (all trade names, manufactured by BASF), Savostab UV119 (trade name, manufactured by Sabo Corporation), Adekastab LA-63P, and Adekastab LA-52 (all trade names, manufactured by Adeka Corporation).

[0148] Examples of the N-OR type hindered amine compound include Tinuvin 123, Tinuvin 5100, Tinuvin NOR371FF, and Flame Stab NOR116FF (all trade names, manufactured by BASF).

[0149] The polyethylene resin layer 21 may or may not contain an ultraviolet absorber (UVA). Examples of ultraviolet absorbers include benzophenone-based ultraviolet absorbers, salumarate-based ultraviolet absorbers, benzocoat-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and quenchers. For polyethylene or polypropylene, benzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are particularly preferred as ultraviolet absorbers.

[0150] Benzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxy-benzophenone. Examples of benzotriazole-based ultraviolet absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole (Sumisorb 200, manufactured by Sumika Chemtex Co., Ltd.), 2-(2-hydroxy-5-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (Tinuvin 326, manufactured by BASF), 2-(2-hydroxy-3,5-di-t-butylphenyl)-5-chlorobenzotriazole (Tinuvin 327, manufactured by BASF), and 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole (Tinuvin 328, manufactured by BASF).

[0151] The density of the polyethylene resin composition of the polyethylene resin layer 21 is preferably 0.946 g / cm from the viewpoint of obtaining good rigidity of the polyethylene resin composition. 3 More preferably, 0.947 g / cm 3 More preferably, 0.948 g / cm 3 The density is preferably 0.960 g / cm from the viewpoint of obtaining good long-term durability and flexibility of the polyethylene resin composition. 3or less, more preferably 0.957 g / cm 3 or less, more preferably 0.953 g / cm 3 The density is a value measured in accordance with JIS K6922-2:1997.

[0152] The melt flow rate (MFR) of the polyethylene resin composition of the polyethylene resin layer 21 at a temperature of 190°C and a load of 21.6 kg 21.6 In order to obtain good processability of the polyethylene resin composition, the MFR 21.6 The MFR is preferably 8 g / 10 min or more, more preferably 12 g / 10 min or more, and even more preferably 15 g / min or more. 21.6 The MFR is preferably 22 g / 10 min or less, and more preferably 20 g / 10 min or less. 21.6 is a value measured in accordance with JIS K6922-2:1997.

[0153] In the molecular weight distribution of the polyethylene resin composition of the polyethylene resin layer 21 measured by GPC, Mz / Mw, which is an index showing the breadth of the molecular weight distribution, is 2.5 or more and 5.5 or less. From the viewpoint of fluidity, it is preferably 2.7 or more, more preferably 3.0 or more. Furthermore, from the viewpoint of molecular orientation, it is preferably 5.3 or less, more preferably 5.0 or less.

[0154] In the molecular weight distribution of the polyethylene resin composition of the polyethylene resin layer 21 measured by GPC, components having a molecular weight of 300,000 or more account for 2% or less of the total, preferably 1.5% or less, more preferably 1.0% or less, from the viewpoint of molecular orientation.

[0155] When a coating resin layer 22 is provided on the outside of the innermost polyethylene resin layer 21 that forms the inner surface 11a, 31a to 35a, 42a (an example of the inner surface of the piping material) of the ultrapure water piping material, the thickness of the innermost polyethylene resin layer 21 is preferably 0.3 mm or more, and more preferably 0.4 mm or more, taking into consideration the strength of the entire ultrapure water piping material and the calcium concentration contained in the coating resin layer 22. The upper limit of the thickness is preferably 2.0 mm or less, and more preferably 1.5 mm or less.

[0156] When no coating resin layer 22 is provided on the outside of the polyethylene-based resin layer 21 that forms the inner surface 10a, 31a to 35a, 42a (an example of the inner surface of the piping material) of the ultrapure water piping material, the thickness of the polyethylene-based resin layer 21 is not particularly limited, and the lower limit of the thickness can be, for example, 0.3 mm or more.

[0157] [Coating resin layer] The type of coating resin layer 22 is not particularly limited, and may be a polyethylene resin layer made of a polyethylene resin, a gas barrier resin layer made of a gas barrier resin, or a combination thereof.

[0158] When a polyethylene resin layer is provided as the coating resin layer 22, the polyethylene resin can be appropriately selected from the polyethylene resin composition that is the main component of the polyethylene resin layer 21 of the innermost layer described above.

[0159] Among the above-mentioned polyethylene resins, HDPE is preferred from the viewpoint of suppressing the elution of low molecular weight components and / or from the viewpoint of durability when pipes are washed with chemicals.

[0160] The polyethylene-based resin that is the main component of the polyethylene-based resin layer of the coating resin layer 22 may be the same as or different from the polyethylene-based resin composition that is the main component of the polyethylene-based resin layer 21 of the innermost layer. However, when the two layers are laminated in contact with each other, it is more preferable that the polyethylene-based resins be the same type of polyethylene-based resin, from the viewpoint of improving the adhesion between the two layers and achieving a desired strength.

[0161] The polyethylene resin layer in the coating resin layer 22 preferably contains an antioxidant. Examples of antioxidants include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, aromatic amine-based antioxidants, and lactone-based antioxidants. From the viewpoint of suppressing the effects of oxygen and ensuring desirable strength, the content of the antioxidant in the polyethylene resin layer in the coating resin layer 22 is, for example, 0.01% by weight or more, preferably 0.1% by weight or more. The upper limit of the antioxidant content is, for example, 5% by weight or less, preferably 1% by weight or less, and more preferably 0.5% by weight or less.

[0162] When a gas barrier layer is provided as the coating resin layer 22, the gas barrier layer may be laminated on the outside of the innermost polyethylene resin layer 21. The gas barrier layer may constitute the outermost layer of the ultrapure water piping material (e.g., pipe 11), or another layer may be provided further outside the gas barrier layer.

[0163] The provision of a gas barrier layer is preferable because it can effectively prevent gas dissolution into ultrapure water. The gas barrier layer also prevents oxygen from penetrating from the outer surface 11b of the ultrapure water piping material (e.g., pipe 11) into the innermost polyethylene-based resin layer 21 or an outer polyethylene-based resin layer provided as needed, thereby improving the long-term strength of the ultrapure water piping material (e.g., pipe 11). This prevents oxygen from penetrating from the outer surface 11b of the ultrapure water piping material (e.g., pipe 11) into the innermost polyethylene resin layer 21 or an outer polyethylene resin layer provided as needed, thereby improving the strength of the ultrapure water piping material (e.g., pipe 11). In addition, providing a gas barrier layer is also preferable in that it effectively prevents gas from dissolving in ultrapure water.

[0164] Examples of materials for the gas barrier layer include polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride resin (PVDC), and polyacrylonitrile (PAN), and preferably polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

[0165] The thickness of the gas barrier layer is not particularly limited as long as it is a thickness that can at least ensure the gas barrier properties of the polyethylene resin, but examples include 30 to 300 μm, preferably 50 to 250 μm, and more preferably 70 to 250 μm.

[0166] [Ultra-pure water piping applications] The piping material for ultrapure water according to the embodiment of the present invention is used for transporting ultrapure water. Specifically, the piping material for ultrapure water according to the embodiment of the present invention can be used as piping within an ultrapure water production apparatus, piping for transporting ultrapure water from an ultrapure water production apparatus to a use point, piping for returning ultrapure water from a use point, etc.

[0167] The ultrapure water piping material according to the embodiment of the present invention is preferably used as water piping for nuclear power generation, which requires particularly strict water quality for ultrapure water, or as ultrapure water transport piping used in wet processing steps such as cleaning in the manufacturing process of pharmaceuticals, semiconductor devices, or liquid crystals, more preferably semiconductor devices. The semiconductor devices in question are preferably those with a high degree of integration, and more specifically, are preferably used in manufacturing processes for semiconductor devices with a minimum line width of 65 nm or less. Standards for the quality of ultrapure water used in semiconductor manufacturing include, for example, SEMI F75.

[0168] Furthermore, the ultrapure water piping material according to the embodiment of the present invention has a polyethylene resin layer, which makes it easy to work with, for example, butt fusion welding or electrofusion welding (EF) welding at a relatively low temperature.

[0169] [Manufacturing piping materials for ultrapure water] The piping material for ultrapure water according to the embodiment of the present invention can be manufactured by preparing a polyethylene resin, which is the main component of the polyethylene resin layer 21 that forms the inner surfaces 10a, 11a, 31a-35a, and 42a of the piping material, and, if necessary, a coating resin that forms the outer coating resin layer 22, and co-extrusion molding the layers so that each layer has a predetermined thickness. Because the piping material for ultrapure water according to the embodiment of the present invention is made of a polyethylene resin, it can be manufactured inexpensively. [Example]

[0170] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Examples 1 to 5] [Comparative Examples 1 to 3] The following materials were prepared and evaluated as follows: (antioxidant) Irganox 1010 (BASF Japan) Irganox 1330 (BASF Japan) Figure 5 shows the structural formula of Irganox 1010. Figure 6 shows the structural formula of Irganox 1330.

[0171] Example 1 (1) Continuous polymerization of polyethylene resins using Ziegler catalysts (Preparation of solid catalyst component) A 1-L pot (milling vessel) containing approximately 700 10-mm-diameter magnetic balls was charged with 20 g of commercially available magnesium ethylate (average particle size 860 μm), 1.66 g of granular aluminum trichloride, and 2.72 g of diphenyldiethoxysilane in a nitrogen atmosphere. These were co-milled using a vibrating ball mill at an amplitude of 6 mm and a frequency of 30 Hz for 3 hours. After co-milling, the contents were separated from the magnetic balls in a nitrogen atmosphere.

[0172] 5 g of the co-ground product obtained in this manner and 20 ml of n-heptane were added to a 200 ml three-neck flask. 10.4 ml of titanium tetrachloride was added dropwise at room temperature while stirring, and the mixture was heated to 90°C and stirred for 90 minutes. The reaction system was then cooled, the supernatant liquid was removed, and n-hexane was added. This procedure was repeated three times. The resulting pale yellow solid was dried at 50°C under reduced pressure for 6 hours to obtain a solid catalyst component.

[0173] (Production of polyethylene resin composition) Dehydrated and purified isobutane was continuously fed to a first polymerization liquid-filled loop reactor having an internal volume of 100 L at a rate of 63 L / hr, triisobutylaluminum at a rate of 20 g / hr, the solid catalyst at a rate of 3.6 g / hr, and ethylene at a rate of 7 kg / hr. 21.6 Copolymerization of ethylene and 1-hexene was carried out under the conditions of 85°C, polymerization pressure of 4.3 MPa, and average residence time of 0.9 hours, with hydrogen (to control MFR) and 1-hexene (to control density) added as a comonomer to achieve the desired comonomer content. A portion of the polymerization reaction product was sampled and its properties were measured. 21.6 is 0.3g / 10min, density is 0.924g / cm 3 It was.

[0174] Next, the isobutane slurry containing the polymerization product of the first step was introduced into a 200 L reactor for the second step, and the second step polymerization was carried out without adding any catalyst under the conditions of 40 L / hr of isobutane, 7 kg / hr of ethylene, 85°C, polymerization pressure of 4.2 MPa, and an average residence time of 0.9 hr. In this second step, hydrogen and 1-hexene were fed so as to produce substantially the same polymer as in the first step. A portion of the polymerization reaction product after the second step was sampled and its physical properties were measured, resulting in a MFR of 1. 21.6 is 0.3g / 10min, density is 0.922g / cm 3 It was.

[0175] Next, the isobutane slurry containing the second step polymerization product was introduced as it was into a 400 L third step reactor, and without adding any catalyst or 1-hexene, 87 L / hr of isobutane and 18 kg / hr of ethylene were continuously fed. 21.6 Hydrogen was supplied so that the temperature became equal to or greater than 90°C, and polymerization was carried out under the conditions of a polymerization pressure of 4.1 MPa and an average residence time of 1.5 hours. The polyethylene polymer discharged from the reactor for the third step was dried, and the obtained polymer powder was melt-kneaded with predetermined additives to form a polyethylene resin composition. The MFR 21.6 is 19g / 10min, density is 0.950g / cm 3 The proportion of the polymer (high molecular weight component) produced in both the first and second steps was 20% by weight.

[0176] On the other hand, the MFR of the polyethylene polymer of the low molecular weight component produced in the third step was determined by separately polymerizing it under the polymerization conditions of the third step, and was found to be 150 g / 10 min. The density of the polyethylene polymer of the low molecular weight component produced in the third step was determined to be 0.970 g / cm by using the fact that the density after the third step and the density after the second step are additivity-related in terms of weight percent. 3 The results are shown in Table 1.

[0177] In Examples 2 and 3 and Comparative Examples 1 to 3, the same production method as in Example 1 was used, but the amount of hydrogen supplied, the amount of 1-hexene supplied, and the polymerization ratio of each component were adjusted to achieve predetermined MFR and density.

[0178] Examples 4 and 5 (2) Homopolymerization of polyethylene resins using Ziegler catalysts <Production of Ziegler catalyst> 20 g of commercially available magnesium ethylate, 1.64 g (12.3 mmol) of granular aluminum trichloride, and 2.40 g (8.81 mmol) of diphenyldiethoxysilane were co-ground to obtain 10.0 g of the co-ground product. 40 ml of heptane and 10.0 g (52.7 mmol) of titanium tetrachloride were added dropwise at room temperature, the mixture was heated to 90 °C, and stirring was continued for 90 minutes. 15.6 g of solid catalyst was obtained by washing with hexane at room temperature.

[0179] <Production of polyethylene resins (medium molecular weight components, low molecular weight components)> A 2.0 L autoclave, thoroughly purged with nitrogen, was charged with 1.0 mmol of triisobutylaluminum (0.50 mol / L hexane solution) and 1.0 L of isobutane, and the internal temperature was raised to 90°C. After hydrogen was further charged, 20 mg of solid catalyst was introduced under pressure with ethylene, and polymerization was continued for 1 hour by maintaining the ethylene partial pressure. Thus, a MFR of 100 g / 10 min and a density of 0.969 g / cm were obtained. 3 The same procedure was repeated except for the amount of hydrogen used to obtain an ethylene polymer of MFR 0.2 g / 10 min and density 0.940 g / cm. 3 Ethylene polymer, MFR 150g / 10min, density 0.969g / cm 3 As a result, ethylene polymers of the above amounts were obtained. (3) Homopolymerization of polyethylene resins using metallocene catalysts

[0180] <Production of Metallocene Catalyst A> In a cylindrical flask equipped with an induction stirrer and thoroughly purged with nitrogen, silica with an average particle size of 11 μm (average particle size 11 μm, surface area 313 m) was added. 2 / g, pore volume 1.6 cm 3A flask containing 3 g of silica (1,1'-{2-(2-(5-methyl)furyl)-4-(p-isopropylphenyl)-indenyl}]zirconium dichloride was charged, 75 ml of toluene was added, and the mixture was heated to 75°C in an oil bath. 8.0 ml of a toluene solution of methylaluminoxane (Albemarle, 3.0 mol-Al / L) was dispensed into a separate flask. A toluene solution (15 ml) of dimethylsilylenebis[1,1'-{2-(2-(5-methyl)furyl)-4-(p-isopropylphenyl)-indenyl}]zirconium dichloride (63.4 mg, 75 μmol) was added to the toluene solution of methylaluminoxane at room temperature, and the mixture was heated to 75°C and stirred for 1 hour. Next, this toluene solution was added with stirring to a toluene slurry of silica heated to 75°C and maintained for 1 hour. Subsequently, 175 ml of n-hexane was added with stirring at 23°C. After 10 minutes, stirring was stopped and the mixture was allowed to stand. After allowing the catalyst to settle sufficiently, the supernatant was removed and 200 ml of n-hexane was added. After stirring once, the mixture was again allowed to stand and the supernatant was removed. This procedure was repeated three times to remove components liberated in n-hexane. The solvent was then distilled off under reduced pressure while heated to 40°C. After the degree of vacuum reached 0.8 mmHg or less, drying under reduced pressure was continued for another 15 minutes to obtain silica-supported metallocene catalyst A.

[0181] <Production of anti-fouling component B> 3 g of n-octylated polyethyleneimine (in which 0.5 n-octyl groups are introduced per monomer unit of polyethyleneimine) derived from polyethyleneimine (molecular weight 10,000) and 1 g of phytic acid, a phosphate ester compound, were mixed and stirred at room temperature in 100 mL of xylene to form a salt. 6 g of dioctyl sulfosuccinate magnesium salt was then added to obtain antifouling component B.

[0182] <Production of polyethylene resin composition (high molecular weight component)> Dehydrated and purified isobutane was fed to a loop-type slurry reactor having an internal volume of 290 L at 115 L / h, triisobutylaluminum at 0.13 mol / h, and antifouling component B at 6 ml / h. The temperature inside the reactor was kept at 80°C, and ethylene, 1-hexene, and hydrogen were fed while intermittently discharging the gas from the reactor to maintain the pressure at 4.2 MPaG. During polymerization, the molar ratio of 1-hexene to ethylene in the liquid was 0.019, and the molar ratio of hydrogen to ethylene was 3.5 × 10 -4 It was adjusted so that

[0183] Next, a hexane slurry of catalyst A diluted to 0.3 g / L with hexane was fed to the reactor at 3 L / h to initiate polymerization, and ethylene was fed so that the ethylene concentration in the reactor reached 10 vol%. The produced polyethylene was intermittently discharged together with isobutane, flashed, and then sent to a product silo. As a result, polyethylene was produced at a rate of 11 kg / h, with an HLMFR of 0.2 g / 10 min and a density of 0.922 g / cm. 3 It was. The polyethylene resin compositions and ethylene polymers produced above were melt-kneaded in the blending ratios shown in Table 1 using a twin-screw extruder at a barrel temperature of 210° C. to obtain Examples 4 and 5.

[0184] (1) Calculation of Mz / Mw by GPC (Gel Permeation Chromatography) Measurement was carried out under the following conditions. Equipment: WATERS 150C Column: Showa Denko AD80M / S (3 columns) Measurement temperature: 140℃ Concentration: 1mg / 1ml Solvent: o-dichlorobenzene

[0185] The molecular weight calculation and column calibration were carried out according to the following methods. The GPC chromatography data was input into a computer at a frequency of one point per second, and data processing was performed according to the description in Chapter 4 of "Size Exclusion Chromatography" by Sadao Mori, published by Kyoritsu Publishing. After calculating the Mw and Mz values, the Mz value was divided by the Mw value to calculate Mz / Mw. The column was calibrated by measuring a series of monodisperse polystyrenes manufactured by Showa Denko K.K. (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28.5, S-5.05), n-eicosane, and n-tetracontane in 0.2 mg / ml solutions, and a calibration curve was prepared by fitting the relationship between the elution peak time and the logarithm of the molecular weight with a fourth-order polynomial. The molecular weight of polystyrene (MPS) was converted to the molecular weight of polyethylene (MPE) using the following formula: MPE = 0.468 × MPS

[0186] (2) FNCT (Full Notch Tensile Creep Test) Measurements were conducted at 80°C and 5 MPa in accordance with the full-circumference notched tensile creep test specified in Appendix 1 of JIS K6774 (1995). Test specimens were cut from 6 mm thick compression-molded sheets prepared under the conditions specified in Table 2 of JIS K6922-2 (1997) and notched all around (6 mm test specimen thickness, 1 mm notch depth, all around). The test solution in which the samples were immersed was a 1% aqueous solution of sodium lauryl sulfate. The standard value that FNCT must meet was a time to failure of 100 hours or more at 80°C and 5 MPa.

[0187] (3) Shrinkage anisotropy evaluation Using a Fanuc 100t injection molding machine, a 130x130x2mm flat plate was molded with a film gate (gate thickness 0.2mm) on one side under the following molding conditions: molding temperature 190°C, mold temperature 40°C, injection speed 50mm / s, maximum injection time 2 seconds, dwell pressure 66MPa, and cooling time 20 seconds. After molding, the plate was left at 23°C for 48 hours, and then the machine direction width (MD) 30mm below the gate finish and the width 30mm below the edge in the transverse direction (TD) were measured, and the MD / TD ratio was calculated as the anisotropic shrinkage ratio. The standard value that must be met for anisotropic shrinkage is a shrinkage anisotropy ratio of 2.5 or less.

[0188] The results of the polyethylene resin compositions and mechanical properties obtained as Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1. Examples 1 to 5 and Comparative Examples 1 to 3 were the same except for the resin component. Calcium stearate was added so that the calcium concentration in the resin was approximately 40 ppm, and 1000 ppm of Irganox 1010 was further added as a phenolic antioxidant.

[0189] (Table 1) TIFF0007724070000001.tif21588

[0190] As shown in the above table, comparing Examples 1 to 5 with Comparative Examples 1 to 3, it was confirmed that the polyethylene resin composition according to the present embodiment has a good balance between dimensional stability and durability, as shown in Examples 1 to 5. Comparative Examples 1 and 2, in which the proportion of components with molecular weights exceeding 3,000,000 is more than 2% and the Mz / Mw, which indicates the spread of the molecular weight distribution, is more than 5.5, have good durability, but the shrinkage anisotropy is large, exceeding 2.5, so that the circularity of the molded article is low and poor connection of the joint is likely to occur. On the other hand, the density of the high molecular weight component is 0.935 g / cm 3 Comparative Example 3, which satisfies the specific requirements of this embodiment except for the following, is excellent in dimensional stability, but the amount of copolymerized α-olefin is insufficient, resulting in a low probability of tie molecule presence, an FNCT of less than 100 hours, and concerns about damage to the pipe material over long-term use. Therefore, the polyethylene resin compositions that do not satisfy the specific requirements of this embodiment are inferior in balance between dimensional stability and durability to the polyethylenes of Examples 1 to 5. (Comparative Examples 1 to 3)

[0191] (4) Preparation of polyethylene resin composition sheet In this example, various evaluations were carried out in a sheet shape rather than a tube shape. According to the formulation shown in Table 2 below, polyethylene resin pellets were heat-pressed at 200°C for 3 minutes to form them into sheets of 180mm x 180mm x 1mm to obtain test samples.

[0192] (5) Calcium concentration evaluation The sheet was cut to prepare test pieces weighing 0.1 g, which were then fed into a microwave decomposition system (MARS6 manufactured by CEM) together with 6 mL of nitric acid, and the test pieces were decomposed by microwaves. After decomposition, 1 mL of hydrogen peroxide was added, and then ultrapure water was added to bring the volume to 25 mL. The calcium concentration of the solution was measured using an ICP apparatus (SPS5100 manufactured by SII Technology), and the calcium concentration of the polyethylene resin composition sheet was calculated.

[0193] (6) Evaluation of calcium elution amount Three samples of 30 mm x 50 mm were prepared from the above sheet and washed with ultrapure water according to the method based on the SEMI F40 standard. The samples were then sealed in a PFA container with 100 mL of ultrapure water. The PFA container was then left to stand at 85°C ± 5°C for 7 days to allow for elution. The amount of calcium elution was then measured using an ICP-MS system (Agilent Technologies, model number Agilent 7500cs). The standard value for calcium elution was 15 μg / m 2 The following is the result.

[0194] The calcium elution characteristics were evaluated in Examples 1, 6 to 8, and Comparative Example 4 by using the same polyethylene resin composition as in Example 1 but changing the calcium concentration and the type of phenolic antioxidant. The results are shown in Table 2.

[0195] (Table 2) TIFF0007724070000002.tif34151

[0196] As shown in Table 2 above, when the calcium concentration of the polyethylene resin composition sheet was 100 ppm or less (Examples 1, 6 to 8), the amount of calcium elution was 15 μg / m 2 The calcium elution was effectively suppressed.

[0197] On the other hand, when the calcium concentration of the polyethylene resin composition sheet was more than 100 ppm (Comparative Example 4), the amount of calcium elution was 15 μg / m 2 exceeded.

[0198] Furthermore, as shown by the comparison between Example 1 and Example 3, and between Example 2 and Example 4, even when the calcium concentration in the polyethylene resin is approximately the same, the amount of calcium elution is suppressed more when Irganox 1330 is added as a phenolic antioxidant than when Irganox 1010 is added. The following factors are presumed to be the cause of this.

[0199] In other words, Irganox 1010 has oxygen atoms other than those derived from phenolic groups in its molecules, making it highly polar and prone to leaching out of polyethylene resins. Furthermore, due to its high polarity, Irganox 1010 is prone to intermolecular forces acting between it and calcium components, which may lead to calcium components leaching out when Irganox 1010 leaches out. For this reason, it is thought that adding Irganox 1010 makes calcium components more likely to leach out.

[0200] On the other hand, Irganox 1330 is a molecule with low polarity that does not contain oxygen other than that derived from phenol groups, and is therefore presumed not to be involved in the elution of calcium components.

[0201] From the above results, when a phenolic antioxidant is added, it is preferable that the antioxidant does not contain oxygen derived from any group other than the phenol group, in order to reduce the amount of calcium elution.

[0202] Furthermore, when a phenolic antioxidant having oxygen derived from a group other than the phenol group is used as the antioxidant, it is found that the calcium concentration in the polyethylene resin is preferably 50 ppm or less. [Explanation of symbols]

[0203] 10,11 tube 10a, 11a inner surface 10b, 11b outer surface 21 Polyethylene resin layer (example of layer) 22 Coating resin layer

Claims

1. A polyethylene-based resin composition for use in a piping material for ultrapure water, the polyethylene-based resin composition comprising a polyethylene-based resin and an antioxidant, wherein the antioxidant is 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, and the polyethylene-based resin composition for use in a piping material for ultrapure water satisfies the following properties (1) to (6): Property (1): Melt flow rate (MFR) at a temperature of 190°C and a load of 21.6 kg ２１．６ ) is 6 g / 10 min or more and 25 g / 10 min or less. Property (2): Density is 0.946 g / cm ３ 0.960g / cm or more ３ The following is the result. Property (3): In the molecular weight distribution measured by GPC, Mz / Mw, which is an index showing the breadth of the molecular weight distribution, is 2.5 or more and 5.5 or less. Property (4): The calcium concentration contained in the polyethylene resin composition is 100 ppm or less. Property (5): MFR as a high molecular weight component ２１．６ is 0.2 g / 10 min or more and 1.0 g / 10 min or less, and the density is 0.910 g / cm ３ 0.935g / cm or more ３ The composition contains 20% by weight or more and 50% by weight or less of an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, which is as follows: Property (6): In the molecular weight distribution measured by GPC, components having a molecular weight of 3,000,000 or more account for 2% or less of the total.

2. The time to fracture in FNCT (measured at 80°C and 5 MPa) is 100 hours or more. The polyethylene resin composition for use as a piping material for ultrapure water according to claim 1.

3. Substantially free of light stabilizers The polyethylene resin composition for use as a piping material for ultrapure water according to claim 1 or 2.

4. A piping material for ultrapure water, characterized by being molded from the polyethylene resin composition according to any one of claims 1 to 3.

5. The thickness of the layer containing a polyethylene resin as a main component is 0.3 mm or more. The piping material for ultrapure water according to claim 4.

6. The thickness of the layer containing a polyethylene resin as a main component is 2.0 mm or less. The piping material for ultrapure water according to claim 4.

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