Piping member

Abstract

The purpose of the present invention is to provide a piping member with which it is possible to suppress a change in the composition of a liquid due to elution of calcium and zinc from an inner surface of the piping member that mostly comes into contact with the liquid at room temperature (below 30°C). A piping member 1 according to the present invention has an inner surface that comes into contact with the liquid, the inner surface having a portion 3 composed of a resin composition containing a polyphenylene ether-based resin, wherein the amounts of calcium and zinc eluted after bringing the inner surface into contact with an elution solution for 6 days under the condition of 23°C are 5 μg / m2 or less, respectively. The polyphenylene ether-based resin is preferably an alloy resin of a polyphenylene ether resin and a styrene resin.

Description

Piping components

[0001] The present invention relates to a piping member having a portion of its inner surface, which comes into contact with a liquid, made of a resin composition containing a polyphenylene ether resin.

[0002] Conventionally, in the manufacturing of semiconductor-related products, for example, in wet processes such as cleaning, ultrapure water purified to an extremely high degree of purity, or ultra-high-purity cleaning solutions purified to an extremely high degree of purity according to the required composition, have been used. If metal ions and / or organic substances are present in the semiconductor cleaning solution at a concentration above a certain level, the adsorption of metals and / or organic substances onto the wafer surface, etc., will adversely affect the quality of the resulting product. Therefore, efforts are being made to suppress the inclusion of impurities in semiconductor cleaning solutions such as ultrapure water and high-purity cleaning solutions.

[0003] As a resin material for piping used in semiconductor cleaning solutions, fluororesins are used that are chemically inert, possess gas barrier properties, and have extremely low elution into semiconductor cleaning solutions. For example, Patent Document 1 discloses a double-walled fluororesin tube, which is made of two layers of fluororesin, as piping used in semiconductor manufacturing equipment. The inner layer tube is made of a fluororesin with excellent corrosion resistance and chemical resistance (for example, 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 (for example, polyvinylidene fluoride (PVDF)). Patent Document 2 also discloses a multilayer tube for ultrapure water piping, which is made of fluororesin and comprises a first resin layer that comes into contact with ultrapure water, and a second resin layer made of a gas-impermeable resin and provided on the outer surface of the first resin layer. Furthermore, it is disclosed that a third resin layer is provided on the outer surface of the second resin layer to protect the second resin layer, and that polyethylene is used as the third resin layer.

[0004] Among the resins used as materials for semiconductor cleaning fluid piping, PVDF is used in all applications in the semiconductor field, including piping within semiconductor cleaning fluid manufacturing equipment and piping for transporting semiconductor cleaning fluid from the manufacturing equipment to the point of use, and has become the technical standard for semiconductor cleaning fluid piping.

[0005] Japanese Patent Publication No. 2006-112507 Japanese Patent Publication No. 2010-234576

[0006] The object of the present invention is to provide a piping member that can suppress changes in the composition of liquids due to the elution of calcium and zinc from the inner surface of the piping member through which liquids mainly at room temperature (below 30°C) are transported.

[0007] The present invention is as follows: 1. A piping member comprising a portion of a resin composition containing a polyphenylene ether resin on an inner surface that comes into contact with a liquid, wherein the amount of calcium and zinc eluted after contacting the inner surface with an eluent for 6 days under conditions of 23°C is 5 μg / m². ２ A piping member characterized by the following: 2. Under conditions of 23°C, the amount of iron eluted after contacting the inner surface with the eluent for 6 days is 5 μg / m³. ２ The piping member described in item 1 above, which is as follows: 3. The piping member described in item 1 or 2 above, wherein the zinc content in the portion made of the resin composition is less than 0.1% by mass. 4. The piping member described in any of items 1 to 3 above, wherein the polyphenylene ether resin is an alloy resin of polyphenylene ether resin and styrene resin. 5. The piping member described in any of items 1 to 4 above, wherein the resin composition further contains a styrene elastomer. 6. The piping member described in item 5 above, wherein the styrene elastomer content is 3 to 25% by mass relative to the resin composition. 7. The piping member described in any of items 1 to 6 above, wherein the inner surface has a portion with a surface roughness Rz of 0.5 μm or less. 8. The piping member described in any of items 1 to 7 above, wherein the piping member is a pipe, tube, fitting, flange, or valve.

[0008] The piping member of the present invention can suppress changes in the composition of liquids due to the leaching of calcium and zinc from the inner surface of the piping member, which mainly carries liquids at room temperature (below 30°C). Therefore, it is useful in industries that utilize liquids at room temperature via piping.

[0009] This is a schematic diagram showing an example of the cross-sectional structure of the piping member of the present invention. This is a schematic diagram showing another example of the cross-sectional structure of the piping member of the present invention.

[0010] The piping member of the present invention is, for example, a pipe, tube, fitting, flange, or valve, and comprises a portion (hereinafter referred to as the "first pipe portion") whose inner surface in contact with the liquid is made of a resin composition containing a polyphenylene ether resin. Under conditions of 23°C, the amount of calcium and zinc eluted after contacting the inner surface of the first pipe portion with an eluent for 6 days was 5 μg / m³. ２ A cylindrical or tubular article characterized by the following:

[0011] The piping member of the present invention may consist only of a first pipe section, or it may include a first pipe section and an exterior section, a reinforcing section, etc., formed on at least a part of its outer surface.

[0012] Figures 1 and 2 are schematic diagrams illustrating the cross-sectional structure of the piping member of the present invention. The piping member 1 in Figure 1 is a multi-layered piping member comprising a first pipe section 3 and an outer covering section 5 formed on at least a part of its outer surface. The piping member 1 in Figure 2 is a piping member consisting only of the first pipe section 3. Thus, the piping member of the present invention has a structure in which the liquid flowing through it comes into contact with the inner surface of the first pipe section 3, that is, the surface where the resin composition containing polyphenylene ether resin is exposed.

[0013] The resin composition according to the present invention contains a polyphenylene ether resin and may further contain other components (described later).

[0014] The polyphenylene ether-based resin according to the present invention is a resin component capable of manufacturing a resin molded product, and preferably, it is composed of a polyphenylene ether resin and another resin. When the polyphenylene ether-based resin is composed of a polyphenylene ether resin and another resin, it may be a simple mixture in which both can be easily separated, or it may be a composite in which both are intertwined and not easily separated. In addition, the content ratio of the polyphenylene ether-based resin in the resin composition is preferably 60% or more, and more preferably 70% or more.

[0015] The polyphenylene ether resin is a resin containing at least one kind of structural unit represented by the following general formula (1). (In the formula, R １ , R ２ , R ３ and R ４ may be the same as or different from each other, and are selected from a hydrogen atom, a halogen atom, an unsubstituted or substituted hydrocarbon group, an alkoxy group, a cyano group, a phenoxy group, and a nitro group.)

[0016] In the above general formula (1), when R １ , R ２ , R ３ or R ４ is an unsubstituted hydrocarbon group, it can be an alkyl group, a phenyl group, etc. In the above general formula (1), when R １ , R ２ , R ３ or R ４ is a halogen atom, it may be any of Cl, Br, and I. In the above general formula (1), when R １ , R ２ , R ３ or R ４When R is an unsubstituted or substituted hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 1 to 8, more preferably 1 to 4. The unsubstituted hydrocarbon group may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Examples of substituted hydrocarbon groups include halogenated hydrocarbon groups, hydrocarbon groups having an amino group, hydrocarbon groups having an alkoxy group, hydrocarbon groups having a cyano group, hydrocarbon groups having a phenoxy group, hydrocarbon groups having a nitro group, and the like. In the above general formula (1), R １ , R ２ , R ３ or R ４ When the group is an alkoxy group, the number of carbon atoms in the hydrocarbon group constituting the alkoxy is preferably 1 to 8, more preferably 1 to 4.

[0017] The polyphenylene ether resin consists of only one type of structural unit represented by the general formula (1) above: poly(2,6-dimethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-ethyl-6-n-propyl-1,4-phenylene) ether, and poly(2,6-di-n-propyl-1,4-phenylene) ether. , poly(2-methyl-6-n-butyl-1,4-phenylene) ether, poly(2-ethyl-6-isopropyl-1,4-phenylene) ether, poly(2-methyl-6-chloroethyl-1,4-phenylene) ether, poly(2-methyl-6-hydroxyethyl-1,4-phenylene) ether, poly(2-methyl-6-chloroethyl-1,4-phenylene) ether, poly(2,6-dimethoxy-1,4-phenylene) ether Examples include homopolymers such as poly(2,6-dichloromethyl-1,4-phenylene) ether, poly(2,6-dibromomethyl-1,4-phenylene) ether, poly(2,6-diphenyl-1,4-phenylene) ether, poly(2,6-ditril-1,4-phenylene) ether, poly(26-dichloro-1,4-phenylene) ether, poly(2,6-dibenzyl-1,4-phenylene) ether, and poly(2,5-dimethyl-1,4-phenylene) ether; and copolymers such as 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer, 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer, 2,6-diethylphenol / 2,3,6-trimethylphenol copolymer, and 2,6-dipropylphenol / 2,3,6-trimethylphenol copolymer, which consist of multiple types of structural units represented by the above general formula (1).

[0018] The molecular weight of the polyphenylene ether resin is not particularly limited. The number-average molecular weight determined by gel permeation chromatography (GPC) is preferably 10,000 to 100,000, more preferably 30,000 to 60,000.

[0019] Other resins constituting the polyphenylene ether resin according to the present invention include resins containing structural units derived from aromatic vinyl compounds (hereinafter referred to as "styrene resin"), polyamides, polyolefins, polyphenylene sulfide, polyphthalamides, and resins containing structural units derived from unsaturated acid anhydrides. The other resins included may be one or two or more. The content ratio of the polyphenylene ether resin and the other resins is preferably 30 to 70% by mass and 70 to 30% by mass, respectively, when the total of both is 100% by mass, and more preferably 40 to 60% by mass and 60 to 40% by mass. In the present invention, it is preferable that the polyphenylene ether resin and the other resins constitute an alloy resin.

[0020] In the present invention, the other resin is preferably a styrene resin. The styrene resin can be at least one selected from homopolymers, copolymers, and graft polymers obtained using aromatic vinyl compounds such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, and 1,3-dimethylstyrene. For example, polystyrene, rubber-modified polystyrene, ABS resin, styrene-acrylonitrile copolymer, styrene-acrylonitrile-methyl methacrylate copolymer, styrene-butadiene block copolymer, and hydrogenated styrene-butadiene block copolymer can be used.

[0021] When the polyphenylene ether-based resin according to the present invention consists of a polyphenylene ether resin and a styrene resin, it is preferable that the styrene resin is a graft polymer and forms a composite (alloy resin) that intertwines with the polyphenylene ether resin.

[0022] The resin composition according to the present invention may consist solely of a polyphenylene ether resin, or, as described above, may consist of a polyphenylene ether resin and other components.

[0023] Other components include polymer elastomers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, lubricants, antistatic agents, antibacterial agents, fillers, colorants, etc. In addition, the resin composition according to the present invention may contain, for example, fibrous fillers in a proportion of 1 to 25% by mass according to the application. However, if the filler is contained in a proportion of 10% or more, the impact resistance of the first pipe portion may be inferior. Therefore, the filler may not be contained, or may be contained in a proportion of less than 2% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass.

[0024] When the resin composition according to the present invention contains a polymer elastomer, the impact resistance of the piping member including the first pipe portion can be improved without being limited to its type and structure. The upper limit of the content ratio of the polymer elastomer is usually 1 to 40% by mass, preferably 3 to 30% by mass, based on the resin composition.

[0025] The structure of the polymer elastomer may be either linear or branched, and may further have a multilayer structure such as a core-shell type.

[0026] The polymer elastomer is preferably a thermoplastic elastomer, and examples include styrene-based elastomers, olefin-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, urethane-based elastomers, vinyl chloride-based elastomers, silicone-based elastomers, etc. The polymer elastomer contained in the resin composition may be one type or two or more types.

[0027] In the present invention, the polymer elastomer is preferably a styrene-based elastomer. This styrene-based elastomer contains at least one kind of structural unit represented by the following general formula (2), and is usually a copolymer further containing structural units derived from other monomers (conjugated dienes, vinyl cyanide compounds, unsaturated acid anhydrides, etc.). (In the formula, R １１ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R １２ is an alkyl group having 1 to 20 carbon atoms, and m is an integer of 0 to 5.)

[0028] The styrene-based elastomer is particularly preferably a copolymer containing a structural unit represented by the above general formula (2) and a structural unit derived from a conjugated diene such as 1,3-butadiene, isoprene, 1,3-pentadiene, or 2,3-dimethyl-1,3-butadiene. Examples of such copolymers include styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-isobutylene-styrene copolymer (SIBS), styrene-butadiene / butylene-styrene copolymer (SBBS), styrene-ethylene / butylene-styrene copolymer (SEBS), styrene-ethylene / propylene-styrene copolymer (SEPS), and styrene-ethylene / ethylene / propylene-styrene (SEEPS) copolymer.

[0029] When the resin composition according to the present invention contains a styrene-based elastomer, its content is preferably 3 to 25% by mass, more preferably 5 to 20% by mass, from the viewpoint of impact resistance of the piping member including the first pipe section.

[0030] The Charpy impact strength (with notch) of the resin composition according to the present invention is 10 kJ / m², from the viewpoint of resistance to water hammer and external impacts. ２ The above is the standard, preferably 15 to 40 kJ / m ２ That is the case.

[0031] In the piping member of the present invention, when an elution test was performed by contacting the inner surface of the first pipe section, which is in contact with the liquid, with an eluent at 23°C for 6 days, the amount of calcium and zinc eluted was very small. Therefore, it is possible to suppress changes in the liquid composition due to the elution of calcium and zinc from the inner surface of the first pipe section of the piping member, which will carry liquid at temperatures below 30°C. The amount of calcium eluted was 5 μg / m³. ２ The following is preferable: 3 μg / m³ ２ More preferably, 1 μg / m ２ More preferably, 0.5 μg / m ２ The following applies. Furthermore, the amount of zinc eluted is 5 μg / m³. ２ Preferably, 3 μg / m³ ２ More preferably, 1 μg / m ２ More preferably, 0.5 μg / m２ The following applies: In this invention, according to the same dissolution test, the amount of iron eluted is preferably 5 μg / m³. ２ More preferably, 3 μg / m ２ More preferably, 1 μg / m ２ The following is particularly preferred: 0.5 μg / m² ２ The following applies:

[0032] Furthermore, the eluent used in the elution test is not particularly limited and may be water (distilled water, ultrapure water, etc.), an acidic solution, or an alkaline solution. The specific method of the elution test is as described in the [Examples] section below.

[0033] The first tube section is typically a molded article obtained by subjecting a molten resin composition to injection molding, extrusion molding, press molding, multilayer molding, etc., and the metal component content is very low. In the present invention, since zinc-based additives may be used in polyphenylene ether resins in particular, the zinc content is preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass. Similarly, the calcium and iron content is also preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass. The content of these metal components can be determined by any method or apparatus that allows for quantitative determination; for example, X-ray fluorescence analysis is a preferred method.

[0034] The piping components of the present invention are mainly applicable to all piping materials that carry liquids at room temperature (usually 20°C or higher and less than 30°C), but can be pipes, tubes, fittings, flanges, or valves. The line connecting one end of the piping component to the other end may be straight or curved (including wavy or spiral shapes). In addition, in the piping component 1 shown in Figures 1 and 2, the cross-sectional shape of the piping component through which the liquid flows (the shape depicted by the outline of the inner surface of the first pipe section) is a perfect circle, but is not limited to this, and can be an ellipse, polygon, etc. Furthermore, the inner surface of the first pipe section may have grooves in the longitudinal direction of the piping component. The average value of the inner diameter (bore diameter) of the cross-sectional shape of the piping component through which the liquid flows is preferably 10 to 500 mm.

[0035] In the present invention, the wall thickness of the first pipe section is preferably 2 mm or more, more preferably 2 to 25 mm, and even more preferably 2.5 to 20 mm, in the case of a single layer consisting only of the first pipe section. In the case of two or more layers, from the viewpoint of elution, it is preferably 1 mm or more, more preferably 1 to 20 mm, and even more preferably 1.5 to 15 mm. Furthermore, the wall thickness from one end to the other end of the piping member may be either uniform or non-uniform.

[0036] In the piping member of the present invention, it is preferable that the inner surface of the first pipe section has a portion with a surface roughness Rz of 0.5 μm or less. From the viewpoint of the fluidity of the liquid inside the piping member, it is particularly preferable that the surface roughness Rz of the entire inner surface is 0.5 μm or less. This surface roughness Rz is even more preferably 0.3 μm or less.

[0037] As described above, the piping member of the present invention may be provided with an outer covering, reinforcing part, etc., on at least a portion of the outer surface of the first pipe section. The constituent material of this outer covering 5 can be selected according to the purpose and may be resin, metal, etc. Furthermore, the outer covering and reinforcing part may consist of multiple layers.

[0038] The piping member of the present invention exhibits low elution of Ca and Zn when liquid is brought into contact with its inner surface, thus providing high yield when various liquids are passed through it during product manufacturing (including treatments such as washing, acid washing, alkaline washing, sterilization, and disinfection). For example, it is suitable for applications such as cleaning semiconductors by supplying highly purified water, such as ultrapure water, or liquids containing predetermined components with controlled concentrations, using the piping member of the present invention.

[0039] The present invention will be specifically described below with reference to examples.

[0040] 1. Raw materials for resin compositions for piping components The raw materials for resin compositions for piping components used in the manufacture of pipes are shown below.

[0041] 1-1. Polyphenylene ether resins (1) "Noryl 731S-780F" (product name) manufactured by SHPP Japan LLC is an alloy resin containing polystyrene. (2) "Zylon W5002" (product name) manufactured by Asahi Kasei Corporation is an alloy resin containing less than 40% by mass of polyphenylene ether and more than 40% by mass of polystyrene. (3) "Yupiace AH60" (product name) manufactured by Mitsubishi Gas Chemical Company is an alloy resin containing polystyrene. (4) "Zylon AT600" (product name) manufactured by Asahi Kasei Corporation is an alloy resin containing less than 40% by mass of polyphenylene ether and more than 45% by mass of polyamide. (5) "Zylon A0210" (product name) manufactured by Asahi Kasei Corporation is an alloy resin containing less than 35% by mass of polyphenylene ether and more than 50% by mass of polyamide. (6) "Yupiace GH20" (product name) manufactured by Mitsubishi Gas Chemical Company is a resin composition consisting of an alloy resin containing polyphenylene ether and polystyrene, and 20% by mass of glass fibers. (7) "Zylon 500H" (product name) manufactured by Asahi Kasei Corporation is an alloy resin containing less than 40% by mass of polyphenylene ether and more than 50% by mass of polystyrene.

[0042] 1-2. Styrene-based elastomer: A styrene-butadiene copolymer with a styrene unit content of 40% by mass.

[0043] 2. Manufacturing of resin compositions and pipes for piping components and their evaluation Examples 1-7 and Comparative Examples 1-4 The above raw materials were kneaded and pelletized using a twin-screw extruder in the proportions shown in Table 1 to obtain resin compositions for piping components. When polyphenylene ether resin was used alone, the pelletized resin was used as is without kneading. Subsequently, quantitative analysis of Ca, Zn, and Fe was performed by fluorescent X-ray analysis, and Charpy impact strength (with notch) was measured in accordance with JIS K 7111. These results are also shown in Table 1. Furthermore, pipes (thickness: 3.1 mm, outer diameter: 32 mm, length: 1000 mm) were manufactured by the method described below, and then the inner surface roughness Rz measurement (average value of 10 measurements) was performed using a roughness analyzer equipped with a diamond stylus (tip radius 2 mm), and elution tests for Ca, Zn, and Fe were performed using ultrapure water at 23°C.

[0044] <Pipe Manufacturing Method> Using a single-screw extruder at a cylinder temperature of 250°C, pipes made from a polyphenylene ether resin composition with a wall thickness of 3.1 mm and an outer diameter of 32 mm were formed from pellets of polyphenylene ether resin, or pellets made by kneading polyphenylene ether resin and styrene elastomer as described in the examples.

[0045] <Leaching Test Using Ultrapure Water> In accordance with the UC standard "Leaching Test Method for Piping Materials for Ultrapure Water," a sample pipe was prepared by fusing a cap to one end of the above-mentioned pipe. The inner surface of the sample pipe was washed for one hour while ultrapure water was flowed through it at a rate of 1 L / min. Then, with the inside of the pipe filled with ultrapure water, the end face of the pipe was covered with a pre-cleaned PTFE sheet, and the cap was fitted to seal it. Next, the sample pipe was left to stand for 6 days in an atmosphere of 23°C ± 2°C to allow elution, and the eluate was quantitatively analyzed for calcium, zinc, and iron using an Agilent Technologies ICP-mass spectrometer (MS) "Agilent 8900" (model name).

[0046] For reference, commercially available polyvinylidene fluoride pipes were subjected to the same analysis or evaluation as described above, and the results are shown in Table 1. Table 1 shows the calculated leaching amounts of Ca, Zn, and Fe from the pipes of Examples 1 to 7 and Comparative Examples 1 to 4 relative to the leaching amounts of Ca, Zn, and Fe in the reference example, and is shown as the "metal reduction rate." It is desirable that this metal reduction rate be lower than 1, with the leaching amount when tested against a standard polyvinylidene fluoride pipe being set to 1 (reference).

[0047]

[0048] The following is clear from Table 1: In Examples 1 to 7, when ultrapure water was brought into contact with the inner surface of the pipe for 6 days, the elution amounts of Ca, Zn, and Fe were 5 μg / m³. ２The following results were obtained, and the amount of these substances leached out was less than that of conventional polyvinylidene fluoride products. As a result, when supplying liquid through pipes, tubes, fittings, flanges, or valves obtained by molding the resin compositions of Examples 1 to 7, and manufacturing, for example, semiconductor-related products, electronic material-related products, liquid crystal-related products, pharmaceutical-related products, etc., the yield reduction due to leached Ca, Zn, or Fe is suppressed. In addition, when a styrene-based elastomer was added to the polyphenylene ether-based resin, the Charpy impact strength was improved, resulting in improved impact resistance.

[0049] The piping member of the present invention exhibits low elution of Ca, Zn, and Fe when liquid is brought into contact with its inner surface, thus providing high yield when various liquids are passed through it during product manufacturing (including various processes). For example, it is suitable as a piping member in equipment for manufacturing semiconductor-related products, electronic material-related products, liquid crystal-related products, pharmaceutical-related products, etc., or as a piping member for liquids supplied to such equipment.

[0050] 1: Piping component 3: First pipe section 5: Outer casing

Claims

1. A piping member comprising a portion of a resin composition containing a polyphenylene ether resin on an inner surface that comes into contact with a liquid, wherein the amount of calcium and zinc eluted after contacting the inner surface with an eluent for 6 days under conditions of 23°C is 5 μg / m². ２ A piping member characterized by the following:

2. Under conditions of 23°C, the amount of iron eluted after contacting the eluent with the inner surface for 6 days was 5 μg / m². ２ The piping member according to claim 1, which is as follows:

3. The piping member according to claim 1, wherein the zinc content in the portion made of the resin composition is less than 0.1% by mass.

4. The piping member according to claim 1, wherein the polyphenylene ether resin is an alloy resin of a polyphenylene ether resin and a styrene resin.

5. The piping member according to claim 1, wherein the resin composition further comprises a styrene-based elastomer.

6. The piping member according to claim 5, wherein the content of the styrene-based elastomer is 3 to 25% by mass relative to the resin composition.

7. The piping member according to claim 1, wherein the inner surface has a portion having a surface roughness Rz of 0.5 μm or less.

8. The piping member according to claim 1, wherein the piping member is a pipe, tube, fitting, flange, or valve.

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