Multi-layered pipe

Abstract

To provide a multi-layered pipe which can be discriminated before renewal and after renewal.SOLUTION: A multi-layered pipe 2 is a multi-layered pipe 1 for transporting a semi-conductor cleaning fluid, and includes a clean layer 11 and an adhesion layer 13. The clean layer 11 constitutes an innermost layer, and includes polyolefin resin or vinyl chloride resin as a main component. The adhesion layer 13 is provided outside of the clean layer 11 and includes a pigment.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to multi-layer pipes. [Background technology]

[0002] In the manufacture of precision devices such as semiconductor devices and liquid crystal display devices, ultrapure water that has been refined to an extremely high degree of purity is 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, so the amount of impurities in the ultrapure water is strictly limited.

[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] For example, Patent Document 1 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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-234576 A [Patent Document 2] Patent Publication No. 2021-55764 [Patent Document 3] Japanese Patent Application Publication No. 2023-46656 Summary of the Invention [Problem to be solved by the invention]

[0006] Pipes used in semiconductor factories for ultrapure water need to be replaced every 10 to 15 years, faster than regular pipes.

[0007] However, if the pipes were colored with pigments to make it easier to distinguish between before and after replacement, this would affect leaching performance, so conventional PVDF pipes had to be uncolored.As a result, even after replacement, the color remained the same, making it difficult to distinguish between before and after installation.

[0008] The present disclosure aims to provide a multi-layer pipe that allows easy distinction between the pipe before and after renewal. [Means for solving the problem]

[0009] To achieve the above object, the multi-layer pipe according to the first disclosure is a multi-layer pipe used for transporting semiconductor cleaning liquid, and includes a first layer and a second layer. The first layer constitutes the innermost layer and is primarily composed of a polyolefin resin or a vinyl chloride resin. The second layer is disposed outside the first layer and contains a pigment.

[0010] In this way, by including a pigment in the second layer outside the first layer, it is possible to create a color difference between the pipe before and after renewal. This makes it easy to distinguish between pipes before and after renewal. Also, in semiconductor factories and other places, by using different colors for pipes carrying room-temperature water and pipes carrying high-temperature water, it is easy to distinguish between pipes carrying liquids of different temperatures.

[0011] The multi-layer pipe according to the second disclosure is the multi-layer pipe according to the first disclosure, wherein the pigment is selected from any one of an organic pigment, an inorganic pigment, and a fluorescent pigment.

[0012] This allows the second layer to be colored to provide a color difference between the pre-renewal and post-renewal tube.

[0013] The multi-layer pipe according to the third disclosure is the multi-layer pipe according to the first disclosure, and has a calcium elution amount of 30 μg / m as measured in accordance with SEMI F-57. 2 is less than.

[0014] This makes it possible to provide a multi-layer pipe that can be used to transport ultrapure water.

[0015] The multi-layer pipe according to the fourth disclosure is the multi-layer pipe according to the first disclosure, in which the color difference between the first layer and the second layer is 0.5 or more.

[0016] By providing a color difference between the first and second layers and coloring the second layer with a pigment, it is possible to distinguish between the pipe before and after renewal, and the first layer can be made a clean layer that does not contain pigment, making it possible to provide a multi-layer pipe that is suitable for use in ultrapure water.

[0017] The multi-layer pipe according to the fifth disclosure is the multi-layer pipe according to the first disclosure, wherein the second layer is an adhesive polyolefin resin.

[0018] This allows another layer to be provided on the outside of the second layer by using the second layer as an adhesive layer, and also allows a colored multi-layer pipe to be provided without affecting the other layer provided on the outside of the second layer with the pigment.

[0019] The multi-layer pipe according to the sixth disclosure is the multi-layer pipe according to the first disclosure, wherein the thickness of the second layer is 10 μm or more and 300 μm or less.

[0020] This allows the colored second layer to be provided in a predetermined thickness.

[0021] The multi-layer pipe according to the seventh disclosure is the multi-layer pipe according to the first disclosure, further comprising a gas barrier layer disposed on the outside of the second layer.

[0022] This makes it possible to suppress the intrusion of oxygen from the outside into the first layer.

[0023] The multi-layer pipe according to the eighth disclosure is the multi-layer pipe according to the first disclosure, further comprising a core layer disposed between the first and second layers, the core layer containing a polyolefin resin as a main component.

[0024] This can improve the strength of the multi-layer pipe.

[0025] A multi-layer pipe according to the ninth disclosure is the multi-layer pipe according to the eighth disclosure, wherein the core layer contains a pigment.

[0026] This allows for a color difference to be created between the first layer, core layer, and second layer, making it possible to determine whether the thickness of each layer is within a specified range, and facilitating quality control.

[0027] The multi-layer pipe according to the tenth disclosure is the multi-layer pipe according to the first disclosure, wherein the polyolefin resin is polyethylene.

[0028] By using polyethylene as the main component of the first layer, the content of low molecular weight components can be reduced, and the elution of organic components into ultrapure water can be suppressed. [Effects of the Invention]

[0029] According to the present disclosure, it is possible to provide a multi-layer pipe that allows easy distinction between the pipe before and after renewal. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view showing a multi-layer pipe according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is a cross-sectional view showing a multi-layer pipe according to another example of an embodiment of the present disclosure. [Figure 3] FIG. 10 is a cross-sectional view showing a multi-layer pipe according to another example of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0032] The multi-layer pipe of this embodiment is used for transporting semiconductor cleaning liquid and includes a first layer and a second layer. The first layer constitutes the innermost layer and is primarily composed of a polyolefin resin or a vinyl chloride resin. The second layer is disposed outside the first layer and contains a pigment.

[0033] (Double-layer pipes 1, 2, 3) Fig. 1 is a cross-sectional view of a multi-layer pipe 1. Fig. 2 is a cross-sectional view of a multi-layer pipe 2, which is another example of the multi-layer pipe 1. Fig. 3 is a cross-sectional view of a multi-layer pipe 3, which is another example of the multi-layer pipe 1.

[0034] The multi-layer pipe 1 shown in Figure 1 includes a clean layer 11 and a core material layer 12. The clean layer 11 forms the inner surface 1b of the multi-layer pipe 1. The clean layer 11 contains a polyolefin resin as its main component. The core material layer 12 is arranged on the outside of the clean layer 11. The core material layer 12 contains a polyolefin resin as its main component and also contains a pigment. As will be described in detail later, by coloring the core material layer 12 with a pigment, a color difference is provided between the clean layer 11 and the clean layer 11. The outer surface 2c of the multi-layer pipe 2 is formed by the core material layer 12. In the multi-layer pipe 1, the clean layer 11 corresponds to an example of the first layer, and the core material layer 12 corresponds to an example of the second layer.

[0035] The multi-layer pipe 2 shown in Figure 2 includes a clean layer 11, a core material layer 12, an adhesive layer 13, and a gas barrier layer 14. In the multi-layer pipe 2, the gas barrier layer 14 is disposed outside the core material layer 12 of the multi-layer pipe 1 with the adhesive layer 13 interposed therebetween. The adhesive layer 13 is disposed on the outer surface of the core material layer 12, and the gas barrier layer 14 is disposed outside the adhesive layer 13. The clean layer 11 constitutes the innermost layer of the multi-layer pipe 2. The clean layer 11 forms the inner surface 2b of the multi-layer pipe 2. The gas barrier layer 14 forms the outer surface 2c of the multi-layer pipe 2. In the multi-layer pipe 2, the clean layer 11 corresponds to an example of the first layer, and the adhesive layer 13 corresponds to an example of the second layer.

[0036] The multi-layer pipe 3 shown in Figure 3 includes a clean layer 11, an adhesive layer 13, and a gas barrier layer 14. Unlike the multi-layer pipe 2, the multi-layer pipe 3 does not have a core layer 12, and the gas barrier layer 14 is disposed on the outer surface of the clean layer 11 via the adhesive layer 13. The clean layer 11 constitutes the innermost layer of the multi-layer pipe 3. The clean layer 11 forms the inner surface 3b of the multi-layer pipe 3. The gas barrier layer 14 forms the outer surface 3c of the multi-layer pipe 3. In the multi-layer pipe 3, the clean layer 11 corresponds to an example of the first layer, and the adhesive layer 13 corresponds to an example of the second layer.

[0037] Each layer will be described below.

[0038] (Clean layer 11) The clean layer 11 constitutes the innermost layer of the multi-layer pipes 1, 2, and 3. The clean layer 11 forms the inner surfaces 1b, 2b, and 3b of the multi-layer pipes 1, 2, and 3. The clean layer 11 contains a polyolefin resin as a main component. The main component refers to the component with the highest content by mass. The main component refers to a component with a content of at least 50%. The lower limit of the polyolefin resin content in the clean layer 11 is preferably 50% by mass, more preferably 70% by mass, even more preferably 80% by mass, sometimes even more preferably 90% by mass, and sometimes even more preferably 95% by mass.

[0039] The polyolefin-based resin contained as the main component of the clean layer 11 is not particularly limited, and may be a polymer containing a monomer unit derived from an olefin. Examples include polyethylene-based resins, ethylene-alkenyl carboxylic acid ester copolymer resins, ethylene-α-olefin copolymer resins, polypropylene-based resins, polybutene-based resins, and poly(4-methyl-1-pentene)-based resins. These polyolefin-based resins may be used alone or in combination of two or more. Among these polyolefin-based resins, polyethylene-based resins and polypropylene-based resins are preferred from the viewpoint of improving the strength of the semiconductor cleaning liquid pipe. Furthermore, among polyethylene-based resins and polypropylene-based resins, polyethylene-based resins are more preferred from the viewpoint of suppressing the content of low-molecular-weight components and thereby suppressing the elution of organic components into ultrapure water.

[0040] Examples of polypropylene resins include homopolypropylene, block polypropylene, and random polypropylene. Ethylene is usually used as a copolymerization component in block polypropylene and random polypropylene. Examples of polybutene resins include polybutene-1.

[0041] 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.

[0042] The polyethylene resin is polymerized using a catalyst containing one or more transition metal derivatives. From the viewpoint of ensuring long-term durability, in this embodiment, polymerization is carried out using a Ziegler catalyst. When polymerizing the polyethylene resin using a Ziegler catalyst, a chlorine-based catalyst is used in an amount appropriately determined by a person skilled in the art to perform multi-stage polymerization, and then a neutralizing agent for neutralizing the chlorine-based catalyst, and preferably an antioxidant, are added as well. The Ziegler catalyst used in the present invention is well known, and examples of the catalyst systems used include those described in JP-A-53-78287, JP-A-54-21483, JP-A-55-71707, and JP-A-58-225105.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Examples of the neutralizing agent include fatty acid metal salts such as calcium stearate, zinc stearate, and magnesium stearate, and hydrotalcites.

[0049] 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.

[0050] 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.

[0051] High-density polyethylene (HDPE) is preferred as a polyethylene-based resin composition, as it provides sufficient pressure resistance against water pressure during water transport and allows for thin pipe walls. Among high-density polyethylenes (HDPEs), HDPEs classified as PE100 or higher in the pressure-resistant class according to ISO 9080, ISO 1167, and ISO 12162 are more preferred in order to ensure the long-term durability of piping materials for ultrapure water. Even among HDPEs classified as PE100 or higher, HDPEs with high resistance to slow crack growth (slow crack growth resistance) are preferred to further enhance the safety of the pipe system and to have 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.

[0052] 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 FR (MFR) is the ratio of the melt flow rate (MFR5) to MFR21.6 at a temperature of 190℃ and a load of 5kg. 21.6 / MFR5) is 25 or more and 60 or less, and the density is 0.946 g / cm 3 More than 0.960g / cm 3 It is preferable that:

[0053] MFR of polyethylene resin composition 21.6 If the MFR is less than 6g / 10min, the fluidity of the resin material is low, the mold transferability is poor, and the smoothness of the inner surface of the pipe is insufficient. 21.6 If the FR exceeds 25g / 10min, it becomes difficult to design a resin that satisfies PE100. Also, if the FR is less than 25, the molecular weight distribution of the polyethylene resin composition becomes narrow, so it is difficult to achieve the target MFR 21.6 On the other hand, if the FR exceeds 60, the impact resistance of the polyethylene resin composition decreases, and the safety of the piping material may be impaired. 3If 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.

[0054] Furthermore, the resin composition for achieving the above polyethylene-based resin composition is preferably composed of multiple components, specifically, a high molecular weight component (A) and a low molecular weight component (B).

[0055] High molecular weight component (A) is MFR 21.6 The resin composition has a melt flow rate (MFR2.16) of 20 g / 10 min to 500 g / 10 min, preferably 50 g / 10 min to 300 g / 10 min, a melt flow rate (MFR2.16) of 20 g / 10 min to 500 g / 10 min, preferably 50 g / 10 min to 300 g / 10 min at a temperature of 190°C and a load of 2.16 kg.

[0056] MFR of the high molecular weight component (A) constituting the polyethylene resin composition 21.6 If the MFR is less than 0.05g / 10min, 21.6 To achieve this, it is necessary to increase the MFR of the low molecular weight component, but in that case, the difference in viscosity between the high molecular weight component and the low molecular weight component when melted increases, reducing compatibility, resulting in a decrease in various mechanical properties including slow crack resistance and roughening of the inner surface of the pipe due to flow instability. 21.6If the elongation coefficient exceeds 1.0 g / 10 min, various mechanical properties are reduced, and in particular, slow crack growth resistance is significantly reduced. If the α-olefin content is less than 0.8 mol%, slow crack growth resistance is reduced, and if it exceeds 2.0 mol%, the rigidity of the polyethylene resin composition is reduced, making it difficult to design a resin that reaches PE100. If the content of high molecular weight component (A) is less than 35 wt%, the durability of the piping is reduced, and if it exceeds 50 wt%, the rigidity of the polyethylene resin composition is reduced, making it difficult to design a resin that reaches PE100.

[0057] If the MFR2.16 of the low-molecular-weight component (B) constituting the polyethylene resin composition is less than 20 g / 10 min, the flowability of the polyethylene resin composition will be reduced, resulting in poor mold transferability and insufficient smoothness of the inner surface of the pipe. On the other hand, if the MFR2.16 exceeds 500 g / 10 min, various mechanical properties, particularly impact resistance, will be significantly reduced.

[0058] The α-olefin content here includes not only the α-olefins fed to the reactor and copolymerized during polymerization, but also by-produced short-chain branches (e.g., ethyl branches, methyl branches). The α-olefin content is measured by C-NMR. The α-olefin content can be increased or decreased by increasing or decreasing the amount of α-olefin fed to be copolymerized with ethylene.

[0059] The amount of calcium elution measured in accordance with SEMI F-57 for the clean layer 11 is 30 μg / m 2 The calcium concentration in the clean layer 11 is adjusted so that it is less than 360 ppm. The calcium concentration in the clean layer 11 is 360 ppm or less, preferably 55 ppm or less, and more preferably 50 ppm or less. If the calcium concentration exceeds 60 ppm, the amount of calcium eluted into the ultrapure water becomes excessive, making it impossible to satisfy the required quality of ultrapure water.

[0060] From the viewpoint of further suppressing the amount of calcium eluted into ultrapure water, it is preferable that the calcium concentration in the clean layer 11 is as low as possible. However, from the viewpoint of obtaining good thermal stability and long-term strength of the polyethylene resin composition, the inclusion of a small amount of calcium is unavoidable.

[0061] That is, when the amount of neutralizing agent added to a polyethylene resin polymerized using a Ziegler catalyst is insufficient, catalyst residue remains active in the resin, which may result in a decrease in the thermal stability and long-term strength of the polyethylene resin composition.

[0062] Therefore, in this embodiment, it is essential to add the minimum amount of neutralizing agent necessary to neutralize the catalyst residue. In consideration of the above, the calcium concentration in the clean layer 11 is 10 ppm or more, preferably 13 ppm or more, more preferably 15 ppm or more, and even more preferably 20 ppm or more.

[0063] From the viewpoint of ensuring thermal stability, the oxidation induction time (OIT) of the clean layer 11 at 210°C is preferably 20 minutes or more. If the oxidation induction time at 210°C is less than 20 minutes, the polyethylene resin may deteriorate when thermally processed, resulting in a decrease in long-term strength and an increase in particles derived from the deterioration, which is not preferable for this embodiment.

[0064] A hot internal pressure creep test is widely used as a method for evaluating the long-term strength of polyethylene resins used as piping materials. From the viewpoint of ensuring sufficient long-term strength of piping materials for ultrapure water, the hot internal pressure creep performance when the clean layer 11 is molded as a piping material is preferably such that the piping material does not break down for 3,000 hours or more when a circumferential stress of 5.0 MPa is applied to the piping material at 80°C.

[0065] 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.

[0066] The clean layer 11 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] Examples of sulfur-based antioxidants include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, and pentaerythrityl tetrakis(3-laurylthiopropionate).

[0071] 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.

[0072] Diphenylamine compounds include p-(p-toluenesulfonylamido)-diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, and 4,4'-dioctyldiphenylamine derivatives. Quinoline compounds include 2,2,4-trimethyl-1,2-dihydroquinoline polymers.

[0073] Examples of naphthylamine compounds include phenyl-α-naphthylamine and N,N'-di-2-naphthyl-p-phenylenediamine.

[0074] 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.

[0075] Examples of the benzimidazole compound include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, the zinc salt of 2-mercaptobenzimidazole, and the zinc salt of 2-mercaptomethylbenzimidazole.

[0076] Examples of lactone antioxidants include a reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene. From the viewpoint of suppressing the influence of oxygen and ensuring a desirable strength, the content of the antioxidant in the clean layer 11 is, for example, 0.01% by weight or more, preferably 0.03% by weight or more, and more preferably 0.05% by weight or more. 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.

[0077] The clean layer 11 may or may not contain a light stabilizer, but preferably does not contain a light stabilizer from the viewpoint of preventing the elution of total organic carbon (TOC). Examples of light stabilizers include hindered amine light stabilizers (HALS). Furthermore, the clean layer 11 of the present embodiment preferably does not substantially contain a light stabilizer. 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.

[0078] 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.

[0079] 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.

[0080] 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).

[0081] 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).

[0082] The clean layer 11 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.

[0083] Benzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxy-benzophenone.

[0084] 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).

[0085] The density of the polyethylene resin composition of the clean layer 11 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. 3 or less, more preferably 0.957 g / cm 3 or less, more preferably 0.953 g / cm 3 The density is a value established in accordance with JIS K6922-2:1997.

[0086] The melt flow rate (MFR) of the polyethylene resin composition of the clean layer 11 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 established in accordance with JISK6922-2:1997.

[0087] The inner surface smoothness (arithmetic mean roughness Ra) of the clean layer 11 is not particularly limited and may be, for example, 0.50 μm or less. From the viewpoint of obtaining good low elution properties of the pipe, the inner surface smoothness of the clean layer 11 is preferably 0.40 μm or less, more preferably 0.35 μm or less.

[0088] The ratio of the thickness of the clean layer 11 to the total thickness of the clean layer 11 and the core layer 12 is preferably 0.011 or more and 0.500 or less.

[0089] The thickness t1 of the clean layer 11 is preferably 0.3 mm or more and 4 mm or less.

[0090] (Core layer 12) The core layer 12 is disposed on the outside of the clean layer 11. In this embodiment, the core layer 12 is used in the multi-layer pipe 1 and the multi-layer pipe 2. The core layer 12 contains a polyolefin resin as a main component. The polyolefin resin used in the core layer 12 is not particularly limited and can be appropriately selected from the polyolefin resins listed above as being used in the clean layer 11. Among the polyolefin resins listed above, high-density polyethylene (HDPE) is preferred from the viewpoint of suppressing the elution of low-molecular-weight components and / or durability when pipes are cleaned with chemicals. The polyolefin resin used in the core layer 12 may be the same or different from the polyolefin resin used in the clean layer 11. However, when the two layers are laminated in contact with each other, it is more preferred that the two layers be the same type of polyolefin resin in order to improve adhesion between the two layers and achieve desired strength.

[0091] The core layer 12 contains a pigment. Any of conventionally known organic pigments, inorganic pigments, and extender pigments can be used as the pigment, without any particular limitation. Examples of organic pigments include phthalocyanine-based, azo-based, condensed azo-based, anthraquinone-based, perinone-perylene-based, indigo-thioindigo-based, isoindolinone-based, azomethine azo-based, dioxazine-based, quinacridone-based, aniline black-based, and triphenylmethane-based pigments. Examples of inorganic pigments include carbon black-based, titanium oxide-based, iron oxide-based, iron hydroxide-based, chromium oxide-based, spinnel-type calcined pigments, lead chromate-based, vermilion chromate-based, Prussian blue-based, aluminum powder, and bronze powder. Examples of extender pigments include calcium carbonate-based, barium sulfate-based, silicon oxide-based, and aluminum hydroxide-based pigments. Pigments can be used alone or in combination to achieve the desired color for the core layer 12.

[0092] The color of the core layer 12 is set so that the color difference ΔE between the clean layer 11 and the core layer 12 is 0.5 or more. The color difference ΔE is preferably 1.0, and more preferably 2.0 or more. For example, since the clean layer does not contain a pigment, it can be set to the natural color of polyethylene (milky white), and the core layer 12 can be set to blue. Alternatively, the core layer 12 can be set to a yellowish color.

[0093] The pigment content in the core layer 12 is not particularly limited as long as it can provide the above color difference, but it is preferably 0.05 wt% or more and 1.00 wt% or less. If it is less than 0.05 wt%, it may be difficult to distinguish the color of the pipe before and after renewal, and it may also be difficult to distinguish between the clean layer 11 and the core layer 12.

[0094] The amount of calcium elution measured in accordance with EMIF-57 from the material (polyolefin resin composition) of the core layer 12 is preferably 30 μg / m from the viewpoint of ensuring the strength of the semiconductor cleaning liquid piping in a 60° C. environment. 2 More preferably, 50 μg / m 2 More preferably, 70 μg / m 2 More preferably, 80 μg / m 2 More than 90 μg / m 2 More particularly preferably 95 μg / m 2 The above can be mentioned.

[0095] The multi-layer pipes 1 and 2 of the present invention have an excellent effect of suppressing the elution of calcium and organic components, and can effectively suppress the elution of calcium even if the material of the core layer 12 contains a large amount of calcium. From this perspective, a suitable example of the amount of calcium elution is 80 μg / m within the above range. 2 More than 90μg / m 2 or more, or 95 μg / m 2 The upper limit of the amount of calcium elution is not particularly limited, but from the viewpoint of suppressing calcium elution, it is 120 μg / m 2 Below, 110μg / m 2or less, or 100 μg / m 2 Examples include the following. The calcium concentration in the material (polyolefin resin composition) of the core layer 12 is not particularly limited as long as it satisfies the above-mentioned calcium elution amount, but from the viewpoint of ensuring the strength of the semiconductor cleaning liquid piping in an operating environment of 60°C, it can be, for example, 20 ppm or more, preferably 30 ppm or more, more preferably 40 ppm or more, even more preferably 50 ppm or more, and even more preferably 60 ppm or more. The upper limit of the calcium concentration range can be, for example, 200 ppm or less, preferably 150 ppm or less, more preferably 130 ppm or less, and even more preferably 100 ppm or less, from the viewpoint of preventing a lack of strength caused by the contained calcium itself becoming the starting point of fracture and from the viewpoint of preventing the elution of calcium and organic components.

[0096] The amount of organic components (TOC) eluted from the material (polyolefin resin composition) of the core layer 12, as measured in accordance with EMIF-57, is, for example, 30,000 μg / m 2 The multi-layer pipes 2 and 3 of the present invention are excellent in the effect of inhibiting the elution of calcium and organic components, and therefore can effectively inhibit the elution of organic components even if the material of the core layer 12 contains a large amount of organic components. From this perspective, a suitable example of the amount of eluted organic components is 31,000 μg / m 2 or more, preferably 31,500 μg / m 2 The upper limit of the amount of eluted organic components is not particularly limited, but from the viewpoint of suppressing elution of organic components, it is, for example, 35,000 μg / m 2 or less, preferably 34000 μg / m 2 or less, more preferably 33,000 μg / m 2 or less, more preferably 32000 μg / m 2 The following are included:

[0097] The core layer 12 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 core layer 12 is, for example, 0.01% by weight or more, preferably 0.1% by weight or more. 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.

[0098] The thickness t2 of the core layer 12 is preferably 1.7 mm or more and 12 mm or less.

[0099] As shown in Figure 1, when the core material layer 12 forms the outer peripheral surface 1c, the color of the core material layer 12 can be seen from the outside of the multi-layer pipe 1. This makes it possible to distinguish between the pipe before and after renewal by changing the color of the core material layer 12 between the pipe before and after renewal.

[0100] Furthermore, by providing a color difference between the clean layer 11 and the core layer 12, the thickness of each can be easily measured, making it easier to control the quality.

[0101] (adhesive layer 13) As shown in Fig. 2, the adhesive layer 13 is disposed on the outer side of the core layer 12. The adhesive layer 13 bonds the gas barrier layer 14 to the outer side of the core layer 12. From the viewpoint of achieving a desired strength, the adhesive layer 13 is preferably made of the same type of polyolefin resin. For example, maleic anhydride-modified adhesive polyethylene can be used.

[0102] The adhesive layer 13 contains an adhesive polyolefin as a main component and further contains a pigment. Examples of the adhesive polyolefin include modified polyolefins. The adhesive layer 13 can be colored by adding a pigment. The pigment can be selected from organic pigments, inorganic pigments, fluorescent pigments, and combinations thereof. While the pigment is not particularly limited, preferred inorganic pigments include titanium oxide, iron oxide, silica, calcium carbonate, carbon black, and mica. Preferred organic pigments include insoluble azo compounds, phthalocyanine compounds, and copper phthalocyanine blue. Preferred fluorescent pigments include barium, strontium, and zinc sulfides. When mica is used as the pigment, it is preferable to mix mica powder, which is ground into powder, with adhesive polyethylene. The average particle size of the mica powder is preferably 300 μm or less, and more preferably 100 μm or less. The adhesive layer 13 can be colored metallic blue by including, for example, mica or iron oxide in the pigment.

[0103] The thickness t3 of the adhesive layer 13 is preferably 10 μm or more and 300 μm or less.

[0104] The pigment concentration in the adhesive layer 13 is preferably, for example, 0.30 wt% to 3.0 wt%, more preferably 0.8 wt% to 2.5 wt%, and even more preferably 1.0 wt% to 2.0 wt%. If the pigment concentration is less than 0.3 wt%, it may be difficult to distinguish between different colors of the tubes, and if it is more than 3.0 wt%, the adhesive performance may be reduced.

[0105] The color difference between the adhesive layer 13 and the clean layer 11 in the multi-layer pipe 3 shown in Figure 3 is preferably 0.5 or more. In addition, in the case of the multi-layer pipe 2 shown in Figure 2 in which the core layer 12 is disposed between the clean layer 11 and the adhesive layer 13, the color difference ΔE between the adhesive layer 13 and the core layer 12 is preferably 0.5 or more.

[0106] For example, in the case of a four-layer multi-layer pipe 3 as shown in Figure 2, the colors may be darker in the order of clean layer 11, core layer 12, and adhesive layer 13. From the viewpoint of preventing impurities from leaching out, the clean layer 11 does not contain pigment and is milky white. The color difference ΔE between the clean layer 11 and the core layer 12 is preferably 0.5 or more, more preferably 1.0 or more. The color difference ΔE between the core layer 12 and adhesive layer 13 is preferably 0.5 or more.

[0107] (gas barrier layer 14) The provision of the gas barrier layer 14 effectively prevents gas dissolution in ultrapure water. The gas barrier layer 14 also prevents oxygen from penetrating from the outer surfaces 2c, 3c of the multilayer pipes 2, 3 into the innermost clean layer 11 or the core layer 12, thereby improving the long-term strength of the multilayer pipes 2, 3. The provision of the gas barrier layer 14 is also preferable in that it effectively prevents gas dissolution in ultrapure water.

[0108] 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).

[0109] The thickness t4 of the gas barrier layer 14 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 is preferably, for example, 50 μm or more and 300 μm or less.

[0110] The gas barrier layer 14 is transparent, and the color of the adhesive layer 13 can be seen from the outside of the multilayer pipes 2 and 3. This allows the pipes to be distinguished before and after renewal by changing the color of the adhesive layer 13 between the pipes before and after renewal.

[0111] Furthermore, since the clean layer 11, the core layer 12, the adhesive layer 13, and the gas barrier layer 14 have different colors from their adjacent layers, the thickness of each layer can be easily measured, facilitating quality control.

[0112] (Ultrapure water piping applications) The multi-layer pipe of the embodiment of the present invention can be used for transporting ultrapure water. Specifically, the multi-layer pipe of the embodiment of the present invention can be used as piping within an ultrapure water production system, piping for transporting ultrapure water from an ultrapure water production system to a use point, piping for returning ultrapure water from a use point, etc. Note that ultrapure water in this invention is defined as water having a resistivity of 10 MΩ·cm or more at 25°C, more strictly, a resistivity of 15 MΩ·cm or more at 25°C, and even more strictly, a resistivity of 18 MΩ·cm or more at 25°C.

[0113] The multi-layer pipe according to an 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 higher integration density, and more specifically, are more 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.

[0114] Furthermore, the multi-layer pipe according to the embodiment of the present invention has a polyolefin resin layer, which makes it easy to work with, for example, butt fusion welding or electrofusion welding (EF) welding at a relatively low temperature.

[0115] (Manufacturing of multi-layer pipes) The multi-layer pipe of the embodiment of the present invention can be manufactured by preparing a polyolefin-based resin that is the main component of the clean layer 11 that forms the inner surface 2b of the piping material, a polyolefin-based resin that is the main component of the core layer 12, and, if necessary, preparing coating resins that form the outer adhesive layer 13 and the gas barrier layer 64, and co-extrusion molding them so that each layer has a predetermined thickness. Because the multi-layer pipe of the embodiment of the present invention is made of polyolefin-based resin, it can be manufactured inexpensively.

[0116] (Other embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0117] (A) In the above embodiment, the clean layer 11 contains a polyolefin resin as a main component, but it is not limited to polyolefin resin and may contain vinyl chloride resin as a main component. Also, the core layer 12 contains a polyolefin resin as a main component, but it is not limited to polyolefin resin and may contain vinyl chloride resin as a main component.

[0118] (B) In the above embodiment, the clean layer 11 contains a polyolefin resin as the main component, but is not limited to polyolefin resin and may be PVDF. In this case, a layer containing a pigment may be provided on the outside of the clean layer 11 to add color. The main component of the pigment layer may be selected from PVDF, polyolefin resin, vinyl chloride resin, etc.

[0119] (C) In the above embodiment, the core layer 12 contains a pigment. In the above embodiment, the core layer 12 is colored with a pigment to create a color difference between it and the clean layer 11, but the color need not be limited to a pigment, and any color difference can be created between the clean layer 11 and the core layer 12. For example, the core layer 12 may contain a dye or colorant and be colored with the dye or colorant. Furthermore, in the above embodiment, the core layer 12 is colored, but the clean layer 11 may be colored with a pigment, dye, colorant, or the like.

[0120] (D) In the above embodiment, the adhesive layer 13 contains a pigment. In the above embodiment, the adhesive layer 13 is colored with a pigment to provide a color difference between the adhesive layer 13 and the clean layer 11 or the core layer 12, but the material is not limited to a pigment and may be any material as long as it can provide a color difference between the adhesive layer 13 and the clean layer 11 or the core layer 12. For example, the adhesive layer 13 may contain a dye or colorant and be colored by the dye or colorant.

[0121] (E) In the above embodiment, the pigment is contained in the adhesive layer 13, but this is not limited to the adhesive layer 13, and the pigment may also be contained in the gas barrier layer 14. However, if the gas barrier layer 14 contains a pigment, the efficiency of the gas barrier performance may be reduced, so it is preferable not to contain a pigment in the gas barrier layer 14 but to contain a pigment in the adhesive layer 13.

[0122] (F) In the multi-layer pipe 3 in the above embodiment, the core layer 12 and the adhesive layer 13 contain pigment, but from the viewpoint of distinguishing the color from the outside of the multi-layer pipe 3, only one of them may contain pigment.

[0123] (G) In the above embodiment shown in FIG. 3, the multi-layer pipe 3 is a four-layer pipe including a clean layer 11, a core layer 12, an adhesive layer 13, and a gas barrier layer 14, but it is not limited to four layers and may have five or more layers.

[0124] (Example) Next, the multi-layer pipe of this embodiment will be described in detail using examples.

[0125] In this example, we confirmed whether it was possible to distinguish it from an existing pipe made of a single layer of PVDF. The results are shown in Table 1. The existing single layer PVDF pipe is milky white.

[0126] Example 1 In this Example 1, a multi-layer pipe 1 having the configuration shown in FIG. 1 was used. The clean layer 11 of the multi-layer pipe 1 of Example 1 contained clean polyethylene as a main component. HDPE1 was used as the clean layer 11. Novatec HB534N (manufactured by Japan Polyethylene Co., Ltd.) was used as the HDPE1. Novatec HB534N is a completely additive-free high-density polyethylene that does not contain any antioxidants. The core layer 12 contained polyethylene as a main component and was HDPE2. Novatec HE222W (manufactured by Japan Polyethylene Co., Ltd.) was used as the HDPE2. Novatec HE222W is a PE100-grade high-density polyethylene that contains an antioxidant. The pigment contained iron (III) ferrocyanide, which is colored metallic blue, and a pigment containing mica (Toyo Color).

[0127] The color difference ΔE between the clean layer 11 and the core layer 12 was 10. Furthermore, since the existing PVDF pipe and the multi-layer pipe of Example 1 could be visually distinguished from each other, this is indicated as "Good" in Table 1. The color difference between the pressed plate of the material forming the clean layer 11 and the material forming the core layer 12 was measured, and the color difference ΔE between the clean layer 11 and the core layer was measured. A colorimetric color difference meter (ZE-2000, Nippon Denshoku Co., Ltd.) was used to measure ΔE.

[0128] Example 2 In this Example 2, a multi-layer pipe 1 having the configuration shown in Fig. 1 was used. The clean layer 11 of the multi-layer pipe 1 of Example 2 contains clean polyethylene as a main component. The core layer 12 contains polyethylene as a main component and fluorescently colored umbelliferone as a pigment.

[0129] The color difference ΔE between the clean layer 11 and the core layer 12 was measured in the same manner as in Example 1 and was found to be 8, meaning that the existing PVDF pipe and the multi-layer pipe of Example 2 could be visually distinguished from each other from the outside.

[0130] Example 3 In this Example 3, a multi-layer pipe 3 having the configuration shown in Figure 3 was used. The clean layer 11 of the multi-layer pipe 3 of Example 3 contains clean polyethylene as its main component. The adhesive layer 13 contains Admer NF528 (manufactured by Mitsui Chemicals, Inc.), a modified polyethylene, as its main component, and a pigment (Toyo Color) containing iron (III) ferrocyanide and mica, which is colored metallic blue, as a pigment. The material of the gas barrier layer 14 is ethylene-vinyl alcohol copolymer (EVOH).

[0131] The color difference ΔE between the clean layer 11 and the adhesive layer 13 was 10, and the existing PVDF pipe and the multi-layer pipe of Example 3 were visually distinguishable from each other. The color difference ΔE between the clean layer 11 and the adhesive layer 13 was measured by measuring the color difference between the press plate made of the material forming the clean layer 11 and the press plate formed by laminating the clean layer 11, the adhesive layer 13, and the gas barrier layer 14. The color of the adhesive layer 13 was measured from outside the gas barrier layer.

[0132] Example 4 In this Example 4, a multi-layer pipe 3 having the configuration shown in Figure 3 was used. The clean layer 11 of the multi-layer pipe 3 of Example 4 contains clean polyethylene as a main component. The adhesive layer 13 contains Admer NF528 (manufactured by Mitsui Chemicals, Inc.) as a main component and fluorescently colored umbelliferone as a pigment. The material of the gas barrier layer 14 is ethylene vinyl alcohol copolymer (EVOH).

[0133] The color difference ΔE between the clean layer 11 and the adhesive layer 13 was measured in the same manner as in Example 3 and was found to be 8, meaning that the existing PVDF pipe and the multi-layer pipe of Example 4 could be visually distinguished from each other from the outside.

[0134] Example 5 In this Example 5, the multi-layer pipe 2 shown in Figure 2 was used. The clean layer 11 of the multi-layer pipe 2 of Example 5 contains clean polyethylene as its main component. The core layer 12 of the multi-layer pipe 2 of Example 5 contains polyethylene as its main component and a light blue pigment, which is a cyan pigment that is colored light blue. The adhesive layer 13 contains Admer NF528 (manufactured by Mitsui Chemicals, Inc.) as its main component and uses a pigment (Toyo Color) containing iron (III) ferrocyanide and mica that is colored metallic blue. The gas barrier layer 14 is made of ethylene-vinyl alcohol copolymer (EVOH).

[0135] The color difference ΔE between the clean layer 11 and the adhesive layer 13 was measured in the same manner as in Example 3 and was found to be 10, meaning that the existing PVDF pipe and the multi-layer pipe of Example 5 could be visually distinguished from each other. The color difference ΔE between the core layer 12 and the adhesive layer 13 was found to be 7. The color difference ΔE between the core layer 13 and the adhesive layer 13 was measured by measuring the color difference between a press plate made of the material forming the core layer 13 and a press plate formed by laminating the clean layer 11, the adhesive layer 13, and the gas barrier layer 14. The color difference ΔE between the clean layer 11 and the core layer 12 was found to be 1.6 when measured in the same manner as in Example 1.

[0136] Example 6 In Example 6, the multi-layer pipe 2 shown in Figure 2 was used. The clean layer 11 of the multi-layer pipe 2 of Example 5 contains clean polyethylene as its main component. The core layer 12 of the multi-layer pipe 2 of Example 5 contains polyethylene as its main component and does not contain any pigment. The adhesive layer 13 contains Admer NF528 (manufactured by Mitsui Chemicals, Inc.) as its main component, and tin sphene (CaO·SnO2·SiO2) colored cherry blossom metallic and mica as pigments. The material of the gas barrier layer 14 is ethylene vinyl alcohol copolymer (EVOH).

[0137] The color difference ΔE between the clean layer 11 and the adhesive layer 13 was measured in the same manner as in Example 3 and was found to be 6.2, making it possible to visually distinguish the existing PVDF pipe from the multi-layer pipe of Example 6. The color difference ΔE between the core layer 12 and the adhesive layer 13 was measured in the same manner as in Example 5 and was found to be 6. The color difference ΔE between the clean layer 11 and the core layer 12 was measured in the same manner as in Example 1 and was found to be 1.6.

[0138] Example 7 In this Example 7, the multi-layer pipe 2 configuration shown in Figure 2 was used. The clean layer 11 of the multi-layer pipe 2 of Example 7 contains clean polyethylene as a main component. The core layer 12 of the multi-layer pipe 2 of Example 7 contains polyethylene as a main component and does not contain a pigment. The adhesive layer 13 contains Admer NF528 (manufactured by Mitsui Chemicals, Inc.) as a main component and a cyan pigment that is colored blue as a pigment. The material of the gas barrier layer 14 is ethylene vinyl alcohol copolymer (EVOH).

[0139] The color difference ΔE between the clean layer 11 and the adhesive layer 13 was measured in the same manner as in Example 3 and was found to be 9.8, making it possible to visually distinguish the existing PVDF pipe from the multi-layer pipe of Example 7. The color difference ΔE between the core layer 12 and the adhesive layer 13 was measured in the same manner as in Example 5 and was found to be 7.5. The color difference ΔE between the clean layer 11 and the core layer 12 was measured in the same manner as in Example 1 and was found to be 1.6.

[0140] (Comparative Example 1) In Comparative Example 1, a multi-layer pipe having the configuration shown in Fig. 1 was used. The clean layer of the multi-layer pipe of Comparative Example 1 contained clean polyethylene as a main component. The core layer of the multi-layer pipe of Comparative Example 1 contained polyethylene as a main component and did not contain a pigment.

[0141] Measurements were carried out in the same manner as in Example 1, and it was found that there was no color difference between the clean layer and the core layer, and the existing PVDF pipe and the multi-layer pipe of Comparative Example 1 could not be distinguished visually from the outside.

[0142] (Comparative Example 2) In Comparative Example 2, a multi-layer pipe having the configuration shown in Figure 1 was used. The clean layer of the multi-layer pipe of Comparative Example 2 contained clean polyethylene as the main component. The core layer of the multi-layer pipe of Comparative Example 2 contained polyethylene as the main component and no pigment. The adhesive layer of Comparative Example 2 contained Admer NF528 (manufactured by Mitsui Chemicals, Inc.) as the main component and no pigment. The material of the gas barrier layer was ethylene vinyl alcohol copolymer (EVOH).

[0143] As a result of carrying out measurements similar to those in Example 3, the color difference ΔE between the clean layer and the gas barrier layer was 0.4 due to light reflection occurring in the gas barrier layer, but the existing PVDF pipe and the multi-layer pipe of Comparative Example 2 could not be distinguished visually from the outside. As a result of carrying out measurements similar to those in Example 1, no color difference occurred between the clean layer and the core layer. Furthermore, as a result of carrying out measurements similar to those in Example 5, the color difference ΔE between the core layer and the adhesive layer was 0.4 due to light reflection occurring in the gas barrier layer as described above.

[0144] (Table 1) TIFF2025145440000002.tif55170

[0145] As described above, by using multi-layer pipes with a colored core layer or adhesive layer that can be seen from the outside, it is possible to arrange pipes of different colors and distinguish between pipes before and after renewal. For example, by using the blue metallic multi-layer pipe shown in Example 3 before renewal and the fluorescent multi-layer pipe shown in Example 4 after renewal, it is possible to easily distinguish whether the pipe has been renewed.

[0146] Furthermore, since existing PVDF pipes do not contain pigments to prevent the elution of impurities, they have the same natural color (milky white) as the clean layer of the multi-layer pipe of the present disclosure. Therefore, by coloring the core layer or adhesive layer of the multi-layer pipe of the present disclosure so as to create a color difference from the clean layer, it can be distinguished from existing PVDF pipes. [Explanation of symbols]

[0147] 1: Multi-layer pipe 2: Multi-layer pipe 3: Multi-layer pipe 11: Clean layer 12: Core layer 13: Adhesive layer 14: Gas barrier layer

Claims

1. A multi-layer pipe used for transporting a semiconductor cleaning solution, a first layer constituting the innermost layer and containing a polyolefin resin or a vinyl chloride resin as a main component; a second layer disposed outside the first layer and including a pigment; Multi-layer pipe.

2. The pigment is selected from one or more of an organic pigment, an inorganic pigment, or a fluorescent pigment. The multi-layer pipe according to claim 1.

3. The calcium elution amount measured in accordance with SEMI F-57 is 30 μg / m ２ is less than The multi-layer pipe according to claim 1.

4. a color difference between the first layer and the second layer being 0.5 or more; The multi-layer pipe according to claim 1.

5. The second layer is an adhesive polyolefin resin. The multi-layer pipe according to claim 1.

6. The thickness of the second layer is 10 μm or more and 300 μm or less. The multi-layer pipe according to claim 1.

7. Further comprising a gas barrier layer disposed on the outside of the second layer. The multi-layer pipe according to claim 1.

8. further comprising a core layer disposed between the first layer and the second layer; The core layer contains a polyolefin resin as a main component. The multi-layer pipe according to claim 1.

9. The core layer contains a pigment. The multi-layer pipe according to claim 8.

10. The polyolefin resin is polyethylene. The multi-layer pipe according to claim 1.

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