Molded body and tube for transferring high purity chemical agent

Abstract

[Problem] The present invention addresses the problem of providing a molded body which can be used as a tube for transferring a high purity chemical agent. [Solution] The present invention provides a molded body which comprises a liquid contact layer (A) having a liquid contact surface, and a liquid non-contact layer (B) having a liquid non-contact surface, wherein: the liquid contact layer (A) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (a), and the total amount of Na, Mg, K, Ca, and Fe dissolved into hydrofluoric acid from the liquid contact layer (A) is 10 ng / cm2 or less; and the liquid non-contact layer (B) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (b), and the total metal content of Na, Mg, K, Ca, and Fe in the liquid non-contact layer (B) measured by an ashing method is higher than the total metal content of Na, Mg, K, Ca, and Fe in the liquid contact layer (A) measured by the ashing method.

Description

Molded products and tubing for transporting high-purity chemicals

[0001] The present disclosure relates to a molded article and a tube for transporting high-purity chemical solutions.

[0002] Patent Document 1 describes a rubber sheet that includes a first polyolefin resin layer constituting the innermost layer and a second polyolefin resin layer disposed on the outer side of the first polyolefin resin layer, and the amount of calcium elution measured in accordance with SEMI F-57 from the material of the first polyolefin resin layer is 30 μg / m ２ and the ratio of the thickness of the first polyolefin resin layer to the total thickness of the first polyolefin resin layer and the second polyolefin resin layer is 0.011 to 0.17.

[0003] International Publication No. 2021 / 066066

[0004] An object of the present disclosure is to provide a molded article that can be used as a tube for transporting high-purity chemical solutions.

[0005] According to the present disclosure, there is provided a molded article comprising a liquid-contacting layer (A) having a liquid-contacting surface and a non-liquid-contacting layer (B) having a non-liquid-contacting surface, wherein the liquid-contacting layer (A) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (a), and the total amount of Na, Mg, K, Ca, and Fe eluted from the liquid-contacting layer (A) into hydrofluoric acid is 10 ng / cm ２ The non-liquid-contacting layer (B) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (b), and the total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B), as measured by an ashing method, is greater than the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A), as measured by the ashing method.

[0006] According to the present disclosure, it is possible to provide a molded article that can be used as a tube for transporting high-purity chemical solutions.

[0007] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0008] Patent Document 1 proposes a multi-layer pipe made of polyolefin resin and having the above-described structure, which is useful as a pipe for a semiconductor cleaning liquid.

[0009] As piping, piping made of fluororesin is also known. However, in general, molded articles made of fluororesin are more expensive than molded articles made of polyolefin-based resin. There is a demand for molded articles made of fluororesin that can utilize the excellent properties of fluororesin while minimizing cost increases.

[0010] The molded article of the present disclosure includes a liquid-contacting layer (A) having a liquid-contacting surface and a non-liquid-contacting layer (B) having a non-liquid-contacting surface. Furthermore, the molded article of the present disclosure is configured such that the total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B) measured by an ashing method is greater than the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A) measured by an ashing method. This configuration makes it possible to utilize the excellent properties inherent to fluororesins while minimizing cost increases. The configuration of the molded article of the present disclosure is described below.

[0011] The molded article of the present disclosure comprises at least a liquid-contacting layer (A) and a non-liquid-contacting layer (B). The molded article of the present disclosure is a molded article used in contact with a liquid, and comprises a liquid-contacting surface provided in the liquid-contacting layer (A) and a non-liquid-contacting surface provided in the non-liquid-contacting layer (B). Both the liquid-contacting surface and the non-liquid-contacting surface form the outer surface of the molded article, and both surfaces are exposed.

[0012] The liquid-contacting layer (A) and the non-liquid-contacting layer (B) may be bonded directly or via another layer, but are preferably bonded directly. The molded article of the present disclosure may be a two-layer molded article consisting of the liquid-contacting layer (A) and the non-liquid-contacting layer (B), or a three- or more-layer molded article comprising the liquid-contacting layer (A), the non-liquid-contacting layer (B), and other layers, but is preferably a two-layer molded article comprising only the two layers of the liquid-contacting layer (A) and the non-liquid-contacting layer (B). The molded article of the present disclosure may be a two-layer molded article or a three- or more-layer molded article, but in either case, the liquid-contacting layer (A) and the non-liquid-contacting layer (B) constitute the outermost layers, and the surfaces of these layers form the exposed surface of the molded article.

[0013] <Liquid-contacting layer (A)> The liquid-contacting layer (A) is a layer having a liquid-contacting surface. The liquid-contacting surface is the surface of the exposed surface of the molded body that comes into contact with the liquid. The liquid that comes into contact with the liquid-contacting surface is not particularly limited, but examples thereof include chemical solutions such as ammonia water, ozone water, hydrogen peroxide water, hydrochloric acid, sulfuric acid, resist solution, thinner solution, and developer. The liquid that comes into contact with the liquid-contacting surface is preferably at least one selected from the group consisting of ozone water, hydrogen peroxide water, hydrochloric acid, hydrofluoric acid, nitric acid, and sulfuric acid.

[0014] The liquid-contacting layer (A) is configured to reduce the amount of metal components eluted into the liquid in contact with the liquid-contacting surface. In one embodiment, the total amount of Na, Mg, K, Ca, and Fe eluted from the liquid-contacting layer (A) into hydrofluoric acid is 10 ng / cm ２ or less, preferably 9.0 ng / cm ２ More preferably, 8.0 ng / cm or less ２ The lower limit is not particularly limited, but is 0.1 ng / cm ２ By configuring the liquid contact layer (A) so as to reduce the amount of metal eluted into hydrofluoric acid, it is possible to suppress the amount of metal components eluted into the liquid from the molded body.

[0015] In the present disclosure, the amount of metal components eluted from the compact into the liquid (metal elution amount) is the total elution amount of Na / Mg / K / Ca / Fe eluted from the compact (layer) into hydrofluoric acid. The amount of metal components eluted from the compact (layer) can be determined by contacting the compact with 50% hydrofluoric acid for 7 days, recovering only the hydrofluoric acid, heating the hydrofluoric acid to recover the evaporation residue, mixing the recovered evaporation residue with 1N nitric acid to prepare a nitric acid solution, and measuring the contents of Na / Mg / K / Ca / Fe in the nitric acid solution by inductively coupled plasma mass spectrometry.

[0016] The total metal content of Na, Mg, K, Ca, and Fe in the liquid contact layer (A) measured by an ashing method is 40 ng / g or less, preferably 40 ng / g or less, more preferably 30 ng / g or less, and preferably 1 ng / g or more. The lower limit of the metal content measured by the ashing method may be 1 ng / g. By ensuring that the metal content in the liquid contact layer (A) is within the above range, the amount of metal components eluted from the liquid contact layer (A) into hydrofluoric acid can be adjusted to within the above range. Furthermore, by ensuring that the metal content in the liquid contact layer (A) is within the above range, the amount of metal components eluted from the molded body into the liquid can be suppressed.

[0017] The metal content in each layer constituting the molded body can be measured by, for example, preparing a test piece from each layer, washing the test piece with a 1N aqueous solution of nitric acid, ashing the test piece in a cuvette in the atomization section of an atomic absorption spectrophotometer, and measuring the metal content using the atomic absorption spectrophotometer; or by weighing the test piece into a platinum crucible, ashing it using a gas burner or an electric furnace, dissolving the ash in acid, and then measuring the metal content using an ICP optical emission analyzer, inductively coupled plasma mass spectrometry, or a frameless atomic absorption spectrophotometer.

[0018] The liquid-contacting layer (A) contains a tetrafluoroethylene (TFE) / fluoroalkyl vinyl ether (FAVE) copolymer (a).

[0019] The total metal content of Na, Mg, K, Ca, and Fe in the copolymer (a) measured by an ashing method is preferably 40 ng / g or less, more preferably 30 ng / g or less, and preferably 1 ng / g or more. The lower limit of the metal content measured by the ashing method may be 1 ng / g. By using the copolymer (a) with a reduced metal content, the amount of metal components eluted from the liquid-contacting layer (A) into hydrofluoric acid can be adjusted to within the above-mentioned range. Furthermore, by using the copolymer (a) with a reduced metal content, the amount of metal components eluted from the molded body into the liquid can be suppressed.

[0020] The metal content of the copolymer can be measured by, for example, a method in which the copolymer is washed with a 1N aqueous solution of nitric acid, then ashed in a cuvette in the atomization section of an atomic absorption spectrophotometer, and the metal content is measured using the atomic absorption spectrophotometer; or a method in which the copolymer is weighed out in a platinum crucible, ashed using a gas burner or an electric furnace, the ash is dissolved in acid, and the metal content is measured using an ICP optical emission analyzer, inductively coupled plasma mass spectrometry, or a flameless atomic absorption spectrophotometer.

[0021] The copolymer (a) is preferably a melt-processable fluororesin. In the present disclosure, melt-processable means that the polymer can be melted and processed using conventional processing equipment such as an extruder or an injection molding machine. Therefore, melt-processable fluororesins usually have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0022] The melt flow rate (MFR) of the copolymer (a) is 1.0 to 3.0 g / 10 min. By setting the MFR of the copolymer (a) within this range, the resistance of the liquid-contacting layer (A) to oxidizing chemicals such as ozone water and hydrogen peroxide water can be improved. Furthermore, even when the liquid-contacting layer (A) comes into contact with an oxidizing chemical, cracks are less likely to occur in the liquid-contacting layer (A), and the chemical resistance and low chemical permeability of the molded article can be further improved.

[0023] The MFR of the copolymer is measured in accordance with ASTM D1238 using a die having a diameter of 2.1 mm and a length of 8 mm, under a load of 5 kg and at 372°C.

[0024] The melting point of the copolymer (a) is 295 to 310°C.

[0025] The melting point of the copolymer is the temperature corresponding to the maximum value on the heat of fusion curve when the temperature is increased at a rate of 10° C. / min (second run) using a differential scanning calorimeter (DSC).

[0026] The TFE / FAVE copolymer (a) contains tetrafluoroethylene (TFE) units and fluoroalkyl vinyl ether (FAVE) units. By forming the liquid-contacting layer (A) from the TFE / FAVE copolymer (a), it is possible to suppress permeation of chemical solutions and further to impart chemical resistance to the liquid-contacting surface.

[0027] The FAVE contained in the copolymer (a) is a FAVE represented by the general formula (1): CF ２ = CFO (CF ２ CFY １ O) ｐ -(CF ２ CF ２ CF ２ O) ｑ -Rf (1) (wherein, Y １ is F or CF ３ where Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms, p represents an integer of 0 to 5, and q represents an integer of 0 to 5.) and a monomer represented by the general formula (2): CFX=CXOCF ２ OR １ (2) (Wherein, X may be the same or different and is H, F or CF ３ represents R １ represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I.

[0028] Among these, as the FAVE, a monomer represented by general formula (1) is preferred, at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE) is more preferred, at least one selected from the group consisting of PEVE and PPVE is even more preferred, and PPVE is even more preferred.

[0029] The content of the FAVE unit in the copolymer (a) is preferably 3.5 to 13.0% by mass, more preferably 4.0% by mass or more, even more preferably 4.5% by mass or more, more preferably 10.0% by mass or less, and even more preferably 7.0% by mass or less, based on the total monomer units.

[0030] The content of TFE units in copolymer (a) is preferably 87.0 to 96.5% by mass, more preferably 90.0% by mass or more, even more preferably 93.0% by mass or more, more preferably 96.0% by mass or less, and even more preferably 95.5% by mass or less, based on the total monomer units.

[0031] The copolymer (a) may contain monomer units derived from a monomer copolymerizable with TFE and FAVE.

[0032] Monomers copolymerizable with TFE and FAVE include hexafluoropropylene (HFP), CZ ３ Z ４ =CZ ５ (CF ２ ) ｎ Z ６ (In the formula, Z ３ , Z ４ and Z ５ are the same or different and represent H or F; Z ６ represents H, F or Cl, and n represents an integer of 2 to 10.) and a vinyl monomer represented by CF ２ =CF-OCH ２ -Rf ７ (wherein, Rf ７represents a perfluoroalkyl group having 1 to 5 carbon atoms. Among these, HFP is preferred.

[0033] The content of monomer units derived from monomers copolymerizable with TFE and FAVE is preferably 0 to 8.0% by mass, more preferably 3.0% by mass or less, and even more preferably 1.0% by mass or less.

[0034] The copolymer (a) is preferably at least one selected from the group consisting of copolymers consisting only of TFE units and FAVE units, and TFE / HFP / FAVE copolymers, and more preferably a copolymer consisting only of TFE units and FAVE units.

[0035] In the present disclosure, the content of each monomer unit in the copolymer is: １９ It is measured by F-NMR.

[0036] The number of functional groups in the copolymer (a) is 10 carbon atoms. ６ The number of functional groups per unit area is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, still more preferably 5 or less, and preferably 0 or more. From the viewpoint of not impairing the purity of the liquid, the number of functional groups in the copolymer (a) is preferably as small as possible.

[0037] The functional groups are those present at the ends of the main chain or side chains of the copolymer, and those present in the main chain or side chains. ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ At least one selected from the group consisting of OH is preferred.

[0038] Infrared spectroscopy can be used to identify the type of functional group and measure the number of functional groups.

[0039] The number of functional groups is specifically measured by the following method. First, the copolymer is melted at 340 to 350°C for 30 minutes and compression molded to produce a film with a thickness of 0.05 to 0.25 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum of the copolymer, and a difference spectrum is obtained from a base spectrum that is completely fluorinated and has no functional groups. From the absorption peaks of specific functional groups that appear in this difference spectrum, the number of carbon atoms in the copolymer is calculated according to the following formula (A): ６ The number of functional groups per particle, N, is calculated as follows: N = I x K / t (A), where I is absorbance, K is correction coefficient, and t is film thickness (mm).

[0040] For reference, the absorption frequencies, molar absorption coefficients, and correction coefficients for the functional groups in this disclosure are shown in Table 1. The molar absorption coefficients were determined from FT-IR measurement data of low molecular weight model compounds.

[0041]

[0042] -CH ２ CF ２ H, —CH ２ COF, -CH ２ COOH, -CH ２ COOCH ３ , -CH ２ CONH ２ The absorption frequencies of -CF are shown in the table. ２ H, -COF, -COOH free and -COOH bonded, -COOCH ３ , -CONH ２ absorption frequency from tens of Kaiser (cm －１ ) is lower. For example, the number of functional groups of -COF is -CF ２ Absorption frequency due to COF: 1883 cm －１ The number of functional groups determined from the absorption peak of -CH ２ Absorption frequency due to COF: 1840 cm －１ The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0043] The number of functional groups is -CF=CF ２ , -CF２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ It may be the total number of OH.

[0044] A functional group is introduced into the copolymer by, for example, a chain transfer agent or a polymerization initiator used in producing the copolymer. For example, an alcohol is used as a chain transfer agent, and a —CH ２ When a peroxide having an OH structure is used, the main chain terminal of the copolymer is formed with -CH ２ Furthermore, by polymerizing a monomer having a functional group, a functional group is introduced into the side chain terminal of the copolymer.

[0045] By subjecting a copolymer having such functional groups to a fluorination treatment, a copolymer having the number of functional groups within the above range can be obtained. That is, the copolymer (a) may be fluorination-treated. The copolymer (a) may also contain -CF ３ It may have a terminal group.

[0046] The liquid-contacting layer (A) may contain various additives, such as a conductive filler, a stabilizer such as a heat stabilizer, a reinforcing agent, a bulking agent, an ultraviolet absorber, a pigment, etc., within the scope of the present disclosure. In one embodiment, the liquid-contacting layer (A) does not contain any additives and contains only the copolymer (a).

[0047] <Non-liquid-contacting layer (B)> The non-liquid-contacting layer (B) is a layer having a non-liquid-contacting surface. The non-liquid-contacting surface is the surface of the exposed surface of the molded body that does not come into contact with the liquid. It is possible that components in the liquid may permeate the liquid-contacting layer (A) and come into contact with the non-liquid-contacting layer (B). Usually, when components in the liquid permeate the liquid-contacting layer (A) and come into contact with the non-liquid-contacting layer, the components in the liquid are in the form of gas. The gas that comes into contact with the non-liquid-contacting layer is not particularly limited, but examples thereof include air, ozone gas, and other oxidizing gases. Since the non-liquid-contacting layer (B) contains a tetrafluoroethylene (TFE) / fluoroalkyl vinyl ether (FAVE) copolymer (b), it is resistant to deterioration even when in contact with an oxidizing gas, and the durability of the molded body can be sufficiently maintained.

[0048] In one embodiment, the non-liquid-contacting layer (B) does not contain a colorant. Examples of the colorant include colorants used to color the molded article to make it easier to identify the molded article. The colorant may be a pigment, a color dye, or the like.

[0049] The non-liquid-contacting layer (B) is a layer that has a non-liquid-contacting surface and does not have a liquid-contacting surface, and therefore may be configured such that metals are eluted into the liquid when it comes into contact with the liquid. In one embodiment, the total amount of Na, Mg, K, Ca, and Fe eluted from the non-liquid-contacting layer (B) into hydrofluoric acid is 10 ng / cm ２ more than 20 ng / cm ２ That is all. When the liquid-contacting layer (A) is configured so as to reduce the amount of metal components eluted into the liquid in contact with the liquid-contacting surface, there is a drawback in that the copolymer (a) forming the liquid-contacting layer (A) is relatively expensive. In the molded article of the present disclosure, a relatively inexpensive copolymer can be selected as the copolymer (b), so by providing the non-liquid-contacting layer (B), the amount of copolymer (a) used can be reduced, and the manufacturing cost of the molded article can be reduced.

[0050] Furthermore, by providing the liquid-non-contacting layer (B), a synergistic effect can be obtained in that the low chemical liquid permeability can be maintained for a longer period of time than in a single-layer molded article containing a TFE / FAVE copolymer.

[0051] The total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B) measured by an ashing method is higher than the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A) measured by an ashing method. Copolymers with reduced metal contents measured by an ashing method have the disadvantage of being relatively expensive. By configuring the liquid-contacting layer (A) and the non-liquid-contacting layer (B) in this way, the non-liquid-contacting layer (B) can be formed from copolymer (b), which is cheaper than copolymer (a). This reduces the amount of copolymer (a) used to form the liquid-contacting layer (A), and reduces the production cost of the molded product.

[0052] The total metal content of Na, Mg, K, Ca and Fe in the non-liquid-contacting layer (B) measured by an ashing method is preferably more than 40 ng / g, preferably 60 ng / g or more, more preferably 80 ng / g or more, and although there is no particular upper limit, it may be 1000 ng / g or less. When the metal content in the non-liquid-contacting layer (B) is within the above range, it is possible to reduce the production cost of the molded body while suppressing the elution of metal components into the liquid.

[0053] The liquid-non-contacting layer (B) contains a TFE / FAVE copolymer (b).

[0054] In one embodiment, the metal content of copolymer (b) measured by the ashing method is higher than the metal content of copolymer (a) measured by the ashing method. Copolymers with reduced metal contents measured by the ashing method have the disadvantage of being relatively expensive. In the molded article of the present disclosure, a copolymer that is cheaper than copolymer (a) can be selected as copolymer (b). Therefore, by providing non-liquid-contacting layer (B), the amount of copolymer (a) used can be reduced, thereby reducing the manufacturing cost of the molded article.

[0055] The total metal content of Na, Mg, K, Ca and Fe in copolymer (b), as measured by an ashing method, is preferably more than 40 ng / g, more preferably 60 ng / g or more, and more preferably 80 ng / g or more, and the upper limit is not particularly limited, but may be 1000 ng / g or less. By using copolymer (b) having a metal content within the above range, it is possible to reduce the production cost of the molded product while suppressing the elution of metal components into the liquid.

[0056] The copolymer (b) is preferably a fluororesin having melt processability.

[0057] The melt flow rate (MFR) of the copolymer (b) is 1.0 to 70 g / 10 min, preferably 5.0 g / 10 min or more, more preferably 9.0 g / 10 min or more, even more preferably 13.0 g / 10 min or more, and preferably 50.0 g / 10 min or less, more preferably 30.0 g / 10 min or less.

[0058] The melting point of the copolymer (b) is 280 to 315°C.

[0059] The TFE / FAVE copolymer (b) contains TFE units and FAVE units. By forming the liquid-contacting layer (B) from the TFE / FAVE copolymer (b), it is possible to suppress permeation of chemical solutions from the liquid-contacting surface, and further to impart resistance to oxidizing gases such as ozone gas to the liquid-contacting layer (B).

[0060] The FAVE contained in the copolymer (b) is a FAVE represented by the general formula (1): CF ２ = CFO (CF ２ CFY １ O) ｐ -(CF ２ CF ２ CF ２ O) ｑ -Rf (1) (wherein, Y １ is F or CF ３ where Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms, p represents an integer of 0 to 5, and q represents an integer of 0 to 5.) and a monomer represented by the general formula (2): CFX=CXOCF ２ OR １ (2) (Wherein, X may be the same or different and is H, F or CF ３ represents R １ represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I.

[0061] Among these, as the FAVE, a monomer represented by general formula (1) is preferred, at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE) is more preferred, at least one selected from the group consisting of PEVE and PPVE is even more preferred, and PPVE is even more preferred.

[0062] The content of FAVE units in copolymer (b) is preferably 3.5 to 13.0% by mass, more preferably 4.0% by mass or more, more preferably 10.0% by mass or less, even more preferably 7.0% by mass or less, and still more preferably 5.0% by mass or less, based on the total monomer units.

[0063] The content of TFE units in copolymer (b) is preferably 87.0 to 96.5% by mass, more preferably 90.0% by mass or more, even more preferably 93.0% by mass or more, still more preferably 95.0% by mass or more, and more preferably 96.0% by mass or less, based on the total monomer units.

[0064] The copolymer (b) may contain monomer units derived from a monomer copolymerizable with TFE and FAVE.

[0065] Monomers copolymerizable with TFE and FAVE include hexafluoropropylene (HFP), CZ ３ Z ４ =CZ ５ (CF ２ ) ｎ Z ６ (In the formula, Z ３ , Z ４ and Z ５ are the same or different and represent H or F; Z ６ represents H, F or Cl, and n represents an integer of 2 to 10.) and a vinyl monomer represented by CF ２ =CF-OCH ２ -Rf ７ (wherein, Rf ７represents a perfluoroalkyl group having 1 to 5 carbon atoms. Among these, HFP is preferred.

[0066] The content of monomer units derived from monomers copolymerizable with TFE and FAVE is preferably 0 to 8.0% by mass, more preferably 3.0% by mass or less, and even more preferably 1.0% by mass or less.

[0067] The copolymer (b) is preferably at least one selected from the group consisting of copolymers consisting only of TFE units and FAVE units, and TFE / HFP / FAVE copolymers, and more preferably a copolymer consisting only of TFE units and FAVE units.

[0068] The number of functional groups in the copolymer (b) is 10 carbon atoms. ６ The number of functional groups per unit area is preferably 600 or less, more preferably 500 or less, even more preferably 400 or less, still more preferably 300 or less, and preferably 0 or more. The number of functional groups in copolymer (b) may be more than 5, more than 10, more than 20, or more than 30. Since copolymer (b) does not form a liquid-contacting surface, it is not a problem if it has functional groups.

[0069] The functional groups are those present at the ends of the main chain or side chains of the copolymer, and those present in the main chain or side chains. ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ At least one selected from the group consisting of OH is preferred.

[0070] The copolymer (b) may be one that has been fluorinated or one that has not been fluorinated.

[0071] The non-liquid-contacting layer (B) may contain various additives, such as a conductive filler, a stabilizer such as a heat stabilizer, a reinforcing agent, a bulking agent, and an ultraviolet absorber, as long as the object of the present disclosure is not impaired. In one embodiment, the non-liquid-contacting layer (B) does not contain a colorant. In one embodiment, the non-liquid-contacting layer (B) does not contain any additives and contains only the copolymer (b).

[0072] <Configuration of Molded Article> The molded article of the present disclosure includes a liquid-contacting layer (A) and a non-liquid-contacting layer (B). In one embodiment, the thickness (t ａ ) and the thickness of the non-wetted layer (B) (t ｂ ) total thickness [(t ａ +t ｂ ) )] is 0.5 to 1.6 mm, and the thickness (t ａ ) and thickness (t ｂ ) to the total thickness (t ａ ) ratio [t ａ / (t ａ +t ｂ ) )] is 0.175 to 0.800.

[0073] The thickness of the liquid-contacting layer (A) (t ａ ) and the thickness of the non-wetted layer (B) (t ｂ ) total thickness [(t ａ +t ｂ The thickness [(t ａ +t ｂ ) )] is equal to the thickness of the molded article when the molded article is a two-layer molded article having only two layers, a liquid-contacting layer (A) and a non-liquid-contacting layer (B).

[0074] The thickness of the molded body [(t ａ +t ｂ If the thickness [(t )] of the formed body is too large, flexibility may decrease, making bending difficult. For example, if the formed body is a tube, cold flaring or inserting a connecting jig such as a sleeve may become difficult when connecting the tube to a fitting. In addition, if the tube is long, the weight tends to increase. ａ +tｂ If the value of [(a) / (b)] is too small, the molded article may buckle and break when bent, the molded article may be easily permeable to liquid, or the mechanical strength may be poor. Furthermore, if the molded article is a tube, the tube may be deformed by the weight of the liquid flowing through the tube.

[0075] Thickness relative to total thickness (t ａ ) ratio [t ａ / (t ａ +t ｂ ) )] is preferably 0.175 to 0.800, more preferably 0.200 or more, even more preferably 0.300 or more, and more preferably 0.500 or less.

[0076] The thickness of the molded body [(t ａ +t ｂ ) )], the thickness of the liquid-contacting layer (A) (t ａ ) is too large, and the thickness (t ｂ If the ratio of (t) is too small, the amount of the relatively expensive copolymer (a) used increases, which may increase the production cost of the molded article. ａ +t ｂ ) )], the thickness of the liquid-contacting layer (A) (t ａ ) is too small, and the thickness (t ｂ If the proportion of ) is too large, it is advantageous in that the manufacturing cost of the molded body can be reduced, but there is a risk that it will not be possible to prevent the elution of metal components from the molded body into hydrofluoric acid.

[0077] The thickness of the liquid-contacting layer (A) (t ａ ) is preferably 200 to 600 μm, more preferably 300 μm or more, even more preferably 400 μm or more, still more preferably 500 μm or more, more preferably 550 μm or less, and even more preferably 500 μm or less. ａ ) is within the above range, it is possible to suppress the production cost of the molded article, and even when the non-liquid-contacting layer (B) is formed using the copolymer (b) containing a relatively large amount of metal components, it is possible to reliably prevent the metal components in the non-liquid-contacting layer (B) from penetrating into the liquid-contacting layer (A) and eluting into the liquid.

[0078] In one embodiment, the molded article is a two-layer tube having a liquid-contacting layer (A) as an inner layer and a non-liquid-contacting layer (B) as an outer layer. This two-layer tube can be used as a tube for transporting liquid, with the liquid-contacting surface of the liquid-contacting layer (A) forming the inner surface and the non-liquid-contacting surface of the non-liquid-contacting layer (B) forming the outer surface. The liquid-contacting layer (A) is configured to reduce the amount of metal components eluted into a liquid that comes into contact with the liquid-contacting surface. Therefore, even when a liquid passes through the two-layer tube, the amount of metal components eluted into the liquid from the inner surface of the two-layer tube is reduced, and the liquid is hardly contaminated.

[0079] The two-layer tube preferably has a hydrochloric acid permeation rate [P2 / P1] calculated by the following formula of 10 or less: Increase rate of hydrochloric acid permeation rate [P2 / P1] = P2 / P1 P1: Hydrochloric acid permeation rate of the two-layer tube after 30 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature P2: Hydrochloric acid permeation rate of the two-layer tube after 150 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature

[0080] The increase rate of the hydrochloric acid permeation amount [P2 / P1] is preferably 10 or less, more preferably 8.0 or less, and although there is no particular lower limit, it may be 7.0 or more.

[0081] The amount of hydrochloric acid permeated through the two-layer tube can be measured by the method described in the Examples.

[0082] In one embodiment, when the liquid-contacting surface of the laminate or the two-layer tube of the present disclosure is observed under an electron microscope, spherulites are confirmed. By forming spherulites on the liquid-contacting surface, the liquid-contacting surface becomes smoother, and contamination of the liquid can be further reduced.

[0083] The spherulites can be formed by adding polytetrafluoroethylene to the liquid-contacting layer (A). The content of polytetrafluoroethylene may be 0.001 to 50% by mass, or 0.001 to 1% by mass, based on the TFE / FAVE copolymer (a).

[0084] The polytetrafluoroethylene may be polytetrafluoroethylene having a crystallization temperature of 305°C or higher as measured by a differential scanning calorimeter (DSC). The heat of crystallization of polytetrafluoroethylene may be 50 J / g or higher. The crystallization temperature of polytetrafluoroethylene is more preferably 310°C or higher, and even more preferably 312°C or higher.

[0085] The molded article of the present disclosure can be produced by laminating the copolymer (a) and the polymer (b) using, for example, injection molding, extrusion molding, blow molding, or the like.

[0086] Examples of methods for laminating copolymer (a) and polymer (b) include: a method of co-extrusion molding copolymer (a) and polymer (b) to thermally fuse (melt-bond) the layers together; a method of separately preparing a layer containing copolymer (a) and a layer containing polymer (b) using an extruder, superimposing the layers, and bonding the layers together by thermal fusion; a method of preparing a monolayer tube containing copolymer (a) and extruding polymer (b) onto the surface of the monolayer tube using an extruder; and a method of preparing a monolayer tube containing copolymer (a), electrostatically coating the surface of the monolayer tube with polymer (b), and then heating the resulting coated product either overall or from the coated side to heat-melt polymer (b).

[0087] Examples of the coextrusion molding include conventionally known multilayer coextrusion manufacturing methods such as a multi-manifold method and a feed block method.

[0088] The molded article or two-layer tube of the present disclosure can be suitably used as a chemical liquid transport tube for circulating chemical liquids, and can be particularly suitably used as a chemical liquid transport tube used to transport high-purity chemical liquids for semiconductor device manufacturing.

[0089] The chemical liquid may be any chemical liquid used in semiconductor manufacturing, such as ammonia water, ozone water, hydrogen peroxide water, hydrochloric acid, sulfuric acid, resist solution, thinner solution, developer, etc. The chemical liquid is preferably at least one selected from the group consisting of ozone water, hydrogen peroxide water, hydrochloric acid, hydrofluoric acid, nitric acid, and sulfuric acid.

[0090] The high-purity chemical transport tube can be suitably used in semiconductor manufacturing equipment such as chemical supply equipment for semiconductor manufacturing, semiconductor cleaning equipment, and coater developers.

[0091] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0092] <1> According to a first aspect of the present disclosure, there is provided a molded article comprising a liquid-contacting layer (A) having a liquid-contacting surface and a non-liquid-contacting layer (B) having a non-liquid-contacting surface, wherein the liquid-contacting layer (A) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (a), and the total amount of Na, Mg, K, Ca, and Fe eluted from the liquid-contacting layer (A) into hydrofluoric acid is 10 ng / cm ２ or less, wherein the non-liquid-contacting layer (B) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (b), and the metal content of the copolymer (b), which is a raw material of the molded article, measured by an ashing method is higher than the metal content of the copolymer (a) measured by the ashing method, or the total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B), measured by the ashing method, is higher than the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A), measured by the ashing method. <2> According to a second aspect of the present disclosure, there is provided a molded article according to the first aspect, which comprises only two layers, the liquid-contacting layer (A) and the non-liquid-contacting layer (B). <3> According to a third aspect of the present disclosure, there is provided a molded article wherein the thickness (t ａ ) and the thickness of the non-wetted layer (B) (t ｂ ) total thickness [(t ａ +t ｂ ) )] is 0.5 to 1.6 mm, and the thickness (t ａ ) and thickness (tｂ ) to the total thickness (t ａ ) ratio [t ａ / (t ａ +t ｂ <4> According to a fourth aspect of the present disclosure, there is provided a molded article according to the first or second aspect, wherein the thickness (t ａ<5> According to a fifth aspect of the present disclosure, there is provided a molded article according to any one of the first to fourth aspects, which is a two-layer tube having a liquid-contacting layer (A) as an inner layer and a non-liquid-contacting layer (B) as an outer layer. <6> According to a sixth aspect of the present disclosure, there is provided a molded article according to the fifth aspect, in which an increase rate [P2 / P1] of hydrochloric acid permeation amount calculated by the following formula is 10 or less: Rate of increase in hydrochloric acid permeation amount [P2 / P1]=P2 / P1 P1: hydrochloric acid permeation amount of the two-layer tube after 30 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature P2: hydrochloric acid permeation amount of the two-layer tube after 150 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature <7> According to a seventh aspect of the present disclosure, there is provided a molded product according to any of the first to sixth aspects, wherein: the melting point of the copolymer (a) is 295 to 310°C, and the melt flow rate of the copolymer (a) is 1.0 to 3.0 g / 10 min; and the melting point of the copolymer (b) is 280 to 315°C, and the melt flow rate of the copolymer (b) is 1.0 to 70.0 g / 10 min. <8> According to an eighth aspect of the present disclosure, there is provided a molded product according to any of the first to seventh aspects, in which the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A) as measured by an ashing method is 40 ng / g or less, and the total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B) as measured by an ashing method is more than 40 ng / g. <9> According to a ninth aspect of the present disclosure, there is provided a molded product according to any of the first to eighth aspects, in which the total metal content of Na, Mg, K, Ca, and Fe in the copolymer (a) as measured by an ashing method is 40 ng / g or less, and the total metal content of Na, Mg, K, Ca, and Fe in the copolymer (b) as measured by an ashing method is more than 40 ng / g.<10> According to a tenth aspect of the present disclosure, there is provided a molded article according to any one of the first to ninth aspects, wherein the content of fluoroalkyl vinyl ether units in copolymer (a) is 3.5 to 13.0 mass% based on all monomer units of copolymer (a), and the content of fluoroalkyl vinyl ether units in copolymer (b) is 3.5 to 13.0 mass% based on all monomer units of copolymer (b). <11> According to an eleventh aspect of the present disclosure, the number of functional groups in copolymer (a) is 10. ６ The number of functional groups in the copolymer (b) is 30 or less per unit area, and the number of functional groups in the copolymer (b) is 10 or less. ６ A molded article according to any one of the first to tenth aspects is provided, in which the number of spherulites per tube is 600 or less. <12> According to a twelfth aspect of the present disclosure, a molded article according to any one of the first to eleventh aspects is provided, in which the non-liquid-contacting layer (B) does not contain a colorant. <13> According to a thirteenth aspect of the present disclosure, a molded article according to any one of the first to twelfth aspects is provided, in which spherulites are confirmed when the liquid-contacting surface is observed with an electron microscope. <14> According to a fourteenth aspect of the present disclosure, a molded article according to any one of the first to thirteenth aspects is provided, which is manufactured using an injection molding method, an extrusion molding method, or a blow molding method. <15> According to a fifteenth aspect of the present disclosure, a molded article according to any one of the first to fourteenth aspects is provided, which is a tube for transporting high-purity chemical solutions.

[0093] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0094] The values ​​in the examples were measured by the following methods.

[0095] (Polymer Composition) １９ Measurement was carried out by F-NMR.

[0096] (Melt Flow Rate (MFR)) According to ASTM D1238, the mass (g / 10 min) of the copolymer flowing out from a nozzle having an inner diameter of 2.1 mm and a length of 8 mm at 372°C under a load of 5 kg per 10 min was determined using a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.).

[0097] (Melting Point) The melting point was determined as the temperature (2nd run) corresponding to the maximum value on the heat of fusion curve when the temperature was increased at a rate of 10° C. / min (second run) using a differential scanning calorimeter (DSC).

[0098] (Number of Functional Groups) The copolymer was melted at 330 to 340°C for 30 minutes and compression molded to prepare a film with a thickness of 0.20 to 0.25 mm. This film was scanned 40 times using a Fourier transform infrared spectrometer [FT-IR (trade name: Model 1760X, manufactured by PerkinElmer Co., Ltd.)] to obtain an infrared absorption spectrum, and a difference spectrum was obtained from a base spectrum in which the copolymer was completely fluorinated and no functional groups were present. From the absorption peaks of specific functional groups appearing in this difference spectrum, the number of carbon atoms in the copolymer was determined according to the following formula (A): ６ The number of functional groups per molecule, N, was calculated.

[0099] N = I x K / t (A) I: absorbance K: correction coefficient t: film thickness (mm)

[0100] For reference, the absorption frequencies, molar absorption coefficients, and correction coefficients for the functional groups in this disclosure are shown in Table 2. The molar absorption coefficients were determined from FT-IR measurement data of low molecular weight model compounds.

[0101]

[0102] (Metal Content) This was carried out using the ashing method described in WO 94 / 28394. Test pieces made from the copolymer (a) and the copolymer (b), or the liquid-contacting layer (A) and the non-liquid-contacting layer (B), respectively, were washed with a 1N aqueous solution of nitric acid, then precisely weighed in the range of 2 to 6 mg, and ashed by heating at 1100°C for 180 seconds in a graphite cuvette, and analyzed with an atomic absorption spectrophotometer (polarized Zeeman atomic absorption spectrophotometer (Z-8100), manufactured by Hitachi, Ltd.).

[0103] (50% HF eluted metal amount (ng / cm ２)) The two-layer tubes prepared in the experimental examples and comparative examples were cut to prepare test pieces with a length of 100 cm. The test pieces were bent into a U-shape and fixed, and 20 ml of 50% by mass hydrofluoric acid was poured into the test pieces and left for 7 days. The hydrofluoric acid was poured into a platinum dish and evaporated. The evaporation residue was mixed with 0.1 N nitric acid to prepare a nitric acid solution.

[0104] This nitric acid solution was measured using a Seiko Electronics SPQ9000 ICP-MS, and the nitric acid value (Na / Mg / K / Ca / Fe = 0.3 / 0.06 / ND / 0.05 / 0.3 ("ND" stands for "Not Detected")) was used as a blank, and the value subtracted was used as the amount of eluted metal per area of ​​the liquid contact part (ng / cm ２ ) was converted.

[0105] The following copolymers were used in the experimental examples and comparative examples: Copolymer (a) TFE / PPVE copolymer TFE / PPVE=94.5 / 5.5 (mass %) MFR (372°C, 5 kg): 2.0 g / 10 min Melting point: 303°C Number of functional groups: 5 / 10 carbon atoms ６ Metal content: Na / Mg / K / Ca / Fe=ND / ND / ND / 0.8 / 5.0 (ng / g)

[0106] Copolymer (b) TFE / PPVE copolymer TFE / PPVE=95.8 / 4.2 (mass%) MFR (372°C, 5 kg): 14.0 g / 10 min Melting point: 305°C Number of functional groups: 284 / 10 carbon atoms ６ Metal content: Na / Mg / K / Ca / Fe=13 / 10 / 9 / 32 / 82 (ng / g)

[0107] Experimental Example 1 Using a two-layer tube extruder, a 1 / 2-inch tube was produced having an inner layer (liquid-contacting layer) formed from copolymer (a) and an outer layer (liquid-non-contacting layer) formed from copolymer (b), with an outer diameter of 12.70 mm, an inner diameter of 9.50 mm, and a thickness of 1600 μm. The screw rotation speed was adjusted so that the thickness of the inner layer was 500 μm and the thickness of the outer layer was 1100 μm. The results are shown in Table 3.

[0108] The liquid-contacting layer (A) and non-liquid-contacting layer (B) of the prepared two-layer tube were peeled off, and test pieces were prepared from each layer. The metal content in the test pieces was measured using the ashing method described above. The results are shown below. Metal content in the liquid-contacting layer (A): Na / Mg / K / Ca / Fe = 0.3 / ND / ND / 1.0 / 6.0 (ng / g) Metal content in the non-liquid-contacting layer (B): Na / Mg / K / Ca / Fe = 15 / 11 / 9 / 35 / 85 (ng / g)

[0109] These results show that the metal contents in the liquid-contacting layer (A) and the non-liquid-contacting layer (B) are equivalent to the metal contents in the copolymer (a) and the copolymer (b). Therefore, when a tube is produced by molding a copolymer while avoiding contamination by metal components as much as possible, the metal contents in the layers can be predicted from the metal contents in the raw copolymer.

[0110] Experimental Examples 2 to 4, Reference Example 1, Comparative Example 1 Tubes were produced and evaluated in the same manner as in Experimental Example 1, except that the copolymers forming the inner and outer layers were changed as shown in Table 3. The results are shown in Table 3.

[0111]

[0112] Experimental Example 5 A single-layer tube (thickness: 1600 μm) was prepared using copolymer (a). Also, a two-layer tube (thickness: 1600 μm (outer layer: 1100 μm / inner layer: 500 μm)) was prepared using copolymer (a) as an inner layer and copolymer (b) as an outer layer.

[0113] Using each tube, a hydrochloric acid permeation test was performed at room temperature using 35% by mass hydrochloric acid according to the method described in International Publication No. 2005 / 108501. The increase in the amount of hydrochloric acid permeated was calculated from the amount of permeated hydrochloric acid after a predetermined time. The increase in the amount of permeated hydrochloric acid after 100 days and 150 days was compared based on the amount of hydrochloric acid permeated after 30 days.

[0114] Table 4 shows the hydrochloric acid permeation amount (μg cm / cm) of each tube. ２ Table 5 also shows the rate of increase in the amount of hydrochloric acid permeation after 100 days and 150 days relative to the amount of hydrochloric acid permeation after 30 days.

[0115]

[0116]

[0117] The results in Tables 4 and 5 show that the two-layer tube suppressed the increase in hydrochloric acid permeation even 150 days after the introduction of hydrochloric acid. On the other hand, the single-layer tube showed a significant increase in hydrochloric acid permeation. This is presumably due to the generation of fine cracks in the tube by hydrochloric acid. It can be seen that the two-layer tube can suppress hydrochloric acid permeation for a longer period of time than the single-layer tube made of the same copolymer, even when the two layers are made of the same copolymer.

[0118] Experimental Example 6 A circular sheet having a thickness of 200 μm was produced by compression molding using copolymer (a). ２ and 200 ppm FeCl ３ was dissolved in 35% hydrochloric acid to prepare a test solution containing the metal component.

[0119] The obtained sheet was sandwiched between two cups each equipped with a chemical solution inlet, one of which was filled with the prepared test solution, and the other with pure water. The diameter of the contact area between the sheet and the test solution and pure water was 75 mm. In this state, the sheet was left at room temperature for 360 days.

[0120] The pure water was collected and analyzed for copper ion and iron ion content by ICP-MS. As a result, neither copper ion nor iron ion was detected in the pure water. This result shows that a 200 μm thick sheet containing a TFE / FAVE copolymer does not allow metal components in the liquid to pass through.

[0121] Therefore, it can be seen that by making the thickness of the liquid-contacting layer (A) containing the copolymer (a) 200 μm or more, even when the non-liquid-contacting layer (B) is formed using the copolymer (b) containing a relatively large amount of metal components, it is possible to reliably prevent the metal components in the non-liquid-contacting layer (B) from penetrating into the liquid-contacting layer (A) and dissolving into the liquid.

Claims

1. A molded article comprising a liquid-contacting layer (A) having a liquid-contacting surface and a non-liquid-contacting layer (B) having a non-liquid-contacting surface, wherein the liquid-contacting layer (A) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (a), and the total amount of Na, Mg, K, Ca, and Fe eluted from the liquid-contacting layer (A) into hydrofluoric acid is 10 ng / cm ２ or less, wherein the non-liquid-contacting layer (B) contains a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (b), and the total metal content of Na, Mg, K, Ca, and Fe in the non-liquid-contacting layer (B), as measured by an ashing method, is greater than the total metal content of Na, Mg, K, Ca, and Fe in the liquid-contacting layer (A), as measured by the ashing method.

2. The molded article according to claim 1, which comprises only two layers: a liquid-contacting layer (A) and a non-liquid-contacting layer (B).

3. Thickness of the liquid-contacting layer (A) (t ａ ) and the thickness of the non-wetted layer (B) (t ｂ ) total thickness [(t ａ +t ｂ ) )] is 0.5 to 1.6 mm, and the thickness (t ａ ) and thickness (t ｂ ) to the total thickness (t ａ ) ratio [t ａ / (t ａ +t ｂ 3. The molded article according to claim 1, wherein the value of [(Ratio of Molecular Weight ...

4. Thickness of the liquid-contacting layer (A) (t ａ 4. The molded article according to claim 1, wherein the thickness of the first and second particles is 200 μm or more.

5. The molded article according to any one of claims 1 to 4, which is a two-layer tube having a liquid-contacting layer (A) as an inner layer and a non-liquid-contacting layer (B) as an outer layer.

6. The molded article according to claim 5, wherein the rate of increase in hydrochloric acid permeation amount [P2 / P1] calculated by the following formula is 10 or less. Rate of increase in hydrochloric acid permeation amount [P2 / P1] = P2 / P1 P1: The amount of hydrochloric acid permeation amount of the two-layer tube after 30 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature P2: The amount of hydrochloric acid permeation amount of the two-layer tube after 150 days measured by conducting a 35% by mass hydrochloric acid permeation test at room temperature 7. A molded article according to any one of claims 1 to 6, wherein the melting point of copolymer (a) is 295 to 310°C, the melt flow rate of copolymer (a) is 1.0 to 3.0 g / 10 min, and the melting point of copolymer (b) is 280 to 315°C, and the melt flow rate of copolymer (b) is 1.0 to 70.0 g / 10 min.

8. A molded body according to any one of claims 1 to 7, wherein the total metal content of Na, Mg, K, Ca and Fe in the liquid-contacting layer (A) measured by an ashing method is 40 ng / g or less, and the total metal content of Na, Mg, K, Ca and Fe in the non-liquid-contacting layer (B) measured by an ashing method is more than 40 ng / g.

9. The molded article according to any one of claims 1 to 8, wherein the total metal content of Na, Mg, K, Ca and Fe in copolymer (a) measured by an ashing method is 40 ng / g or less, and the total metal content of Na, Mg, K, Ca and Fe in copolymer (b) measured by an ashing method is more than 40 ng / g.

10. A molded article according to any one of claims 1 to 9, wherein the content of fluoroalkyl vinyl ether units in copolymer (a) is 3.5 to 13.0 mass% based on the total monomer units of copolymer (a), and the content of fluoroalkyl vinyl ether units in copolymer (b) is 3.5 to 13.0 mass% based on the total monomer units of copolymer (b).

11. The number of functional groups in copolymer (a) is 10 carbon atoms. ６ The number of functional groups in the copolymer (b) is 30 or less per unit area, and the number of functional groups in the copolymer (b) is 10 or less. ６ The molded article according to any one of claims 1 to 10, wherein the number of particles per particle is 600 or less.

12. The molded article according to any one of claims 1 to 11, wherein the liquid-non-contacting layer (B) does not contain a colorant.

13. The molded article according to any one of claims 1 to 12, wherein spherulites are confirmed when the liquid-contacting surface is observed under an electron microscope.

14. The molded article according to any one of claims 1 to 13, which is produced by injection molding, extrusion molding, or blow molding.

15. The molded article according to any one of claims 1 to 14, which is a tube for transporting high-purity chemical solutions.

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