Pipe and method for manufacturing pipe

Abstract

Provided is a tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, in which the number of functional groups per 106 carbon atoms is 500 or less, the melting point of the copolymer is 280-315 DEG C, and the number of functional groups per 106 carbon atoms is 500 or less. The content of fluoroalkyl vinyl ether units in the copolymer is 3.0-12.0 mass% with respect to the total monomer units, the melt flow rate of the copolymer is 1-15 g / 10 min, and the number of particles released from the inner surface of the tube is 3500 or less per 1 cm2 of the inner surface area of the tube. The amount of total organic carbon eluted into water from the inner surface of the tube is 50 ng or less per 1 cm2 of the inner surface area of the tube.

Description

Technical Field

[0001] The present disclosure relates to tubes and methods of making tubes. Background Art

[0002] Patent document 1 describes a method for manufacturing a fluororesin tube with reduced particles, which is characterized in that in the method for manufacturing a fluororesin tube by melt-extruding a fluororesin or a resin mixture based on a fluororesin to form a tube, clean air is flowed in the tube after or during the tube forming to purge the particles in the tube.

[0003] Patent document 2 describes a method for manufacturing a tube, wherein a molten-processable fluororesin extruded into a tube from a die provided in an extrusion molding machine is guided to a cooling device and cooled, and then the cooled tube is wound on a reel using a winding device, wherein gas is supplied from the front end of the tube wound on the reel to a hollow portion of the tube, and the gas in the hollow portion is discharged to the outside through a gas discharge hole provided in the die from a gas inlet provided in the die, thereby allowing the gas to flow in the hollow portion, and the internal pressure of the hollow portion is maintained to be higher than atmospheric pressure and lower than 0.5 kgf / cm 2 pressure.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-233435

[0007] Patent Document 2: International Publication No. 2022 / 059501 Summary of the invention

[0008] Problems to be solved by the invention

[0009] An object of the present disclosure is to provide a tube in which the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube are reduced.

[0010] Means for solving problems

[0011] According to the present disclosure, a tube is provided, which is a tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, wherein the number of functional groups of the copolymer is relative to every 10 6 The number of carbon atoms is 500 or less, the melting point of the copolymer is 280°C to 315°C, the content of the fluoroalkyl vinyl ether unit of the copolymer is 3.0% to 12.0% by mass relative to the total monomer units, the melt flow rate of the copolymer is 1 g / 10 minutes to 15 g / 10 minutes, and the number of particles released from the inner surface of the tube is 1.0 to 1.5 g / 10 minutes relative to 1 cm 2The inner surface area of ​​the tube is 3500 or less, and the amount of total organic carbon eluted into water from the inner surface of the tube is 100% relative to 1 cm 2 The surface area inside the tube is less than 50ng.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to provide a tube in which both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) eluted from the inner surface of the tube are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic cross-sectional view showing an embodiment of a pipe with both ends welded.

[0015] Figure 2 is a schematic side view of a tube manufacturing apparatus.

[0016] Figure 3 It is a schematic front view of the winding device.

[0017] Figure 4 is a system diagram of a system for determining the number of particles emitted from the inner surface of a tube. DETAILED DESCRIPTION

[0018] Hereinafter, specific embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0019] Patent Document 1 describes a method of supplying clean air from the front end of a delivered tube into the tube to perform a purge process. However, the method described in Patent Document 1 makes it difficult to remove pollutants adhering to the inner surface of the tube.

[0020] Therefore, Patent Document 2 proposes the following manufacturing method: gas is supplied from the front end of a tube wound on a reel to the hollow portion of the tube, the gas in the hollow portion is discharged to the outside through a gas discharge hole provided in the mold from a gas inlet provided in the mold, thereby allowing the gas to flow into the hollow portion, and the internal pressure of the hollow portion is maintained at a level higher than atmospheric pressure and lower than 0.5 kgf / cm 2 The pipe is manufactured at a pressure of , thereby being able to manufacture a pipe having a clean inner surface and excellent dimensional stability with high productivity.

[0021] The tube obtained by the manufacturing method described in Patent Document 2 has extremely high cleanliness. However, further research on the manufacturing method has newly discovered that a tube can be manufactured in which both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) eluted from the inner surface of the tube are further reduced.

[0022] That is, the tube of the present disclosure is a tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer having a specific structure, and the number of particles released from the tube is relative to 1 cm 2 The surface area of ​​the tube is less than 3500, and the amount of total organic carbon eluted from the tube into the water is relative to 1cm 2 The surface area inside the tube is less than 50ng.

[0023] The number of particles released from the inner surface of the tube of the present disclosure is extremely small. The number of particles released from the inner surface of the tube of the present disclosure is relatively small per 1 cm 2 The inner surface area of ​​the tube is 3500 or less, preferably 3200 or less, more preferably 2500 or less, and further preferably 2000 or less. The lower limit of the number of particles may be 1. In the present disclosure, the number of particles refers to the number of particles with a diameter of 30 nm or more released from the inner surface of the tube into IPA when isopropyl alcohol (IPA) is allowed to flow in the tube at a flow rate of 110 mL / min.

[0024] The number of particles released from the inner surface of the tube is measured by the following method. This measurement method is a new measurement method and can measure the number of particles released from the inner surface of the tube with higher accuracy than conventional measurement methods.

[0025] Figure 4 is a system diagram of a system used in the present disclosure to measure the number of particles released from the inner surface of a tube. Figure 4 As shown, the system 9 includes a solvent container 91 , a filter 94 , and a particle counter 97 .

[0026] Isopropyl alcohol (IPA) is contained in a solvent container 91, which is connected to a joint 95 via a pump 92, a valve 93, and a filter 94. The joint 95 and the joint 96 are configured to be able to connect a tube 1 as a measurement object. The IPA in the solvent container 91 is supplied to the tube 1 connected to the joint 95 and the joint 96 by the pump 92 through the filter 94 (filtration accuracy 3nm). A part or all of the IPA that has passed through the tube 1 is introduced into a particle counter 97 to measure the number of particles in the solvent.

[0027] exist Figure 4 In the system 9 shown, a flow meter 98 is provided on the downstream side of the particle counter 97, and a certain amount of IPA is introduced into the particle counter 97. The remaining IPA is adjusted in flow rate by a flow regulating valve attached to the flow meter 99, and discharged to the outside through the flow meter 99. As the particle counter 97, a particle counter with a built-in flow meter 98 may be used.

[0028] The amount of particles released from the inner surface of the tube can be measured by the following method.

[0029] Build Figure 4In the system 9 shown in FIG. 1 , after the liquid contact surfaces of the components constituting the system 9 are cleaned with IPA, a tube 1 to be measured is set on the upstream side of the particle counter.

[0030] The inner surface of the tube 1 is cleaned by flowing IPA in the tube 1 while counting the number of particles having a diameter of 30 nm or more in the IPA used for cleaning the inner surface of the tube 1 using a particle counter.

[0031] Confirm that the number of particles in the IPA used to clean the inner surface of the tube 1 is 10 particles / mL or less,

[0032] Stop supplying IPA to tube 1, and leave tube 1 for 6 hours (normal temperature, no pressurization) while filling tube 1 with IPA.

[0033] Supply of IPA into tube 1 was started again, and IPA was allowed to flow into tube A at a flow rate of 110 mL / min. The number of particles having a diameter of 30 nm or more in IPA passing through tube 1 was measured using a particle counter.

[0034] The amount of total organic carbon (TOC) eluted from the inner surface of the tube of the present disclosure is extremely small. The amount of total organic carbon eluted from the inner surface of the tube of the present disclosure into water is 100% relative to 1 cm 2 The inner surface area of ​​the tube is 50 ng or less, preferably 47 ng or less. The lower limit of the elution amount of total organic carbon may be 1 ng.

[0035] The amount of total organic carbon (TOC) released from the inner surface of the tube can be determined by flowing ultrapure water through the tube and measuring the amount of TOC released from the ultrapure water passing through the tube with a TOC meter.

[0036] In one embodiment of the tube disclosed herein, the amount of potassium, sodium, and iron dissolved from the inner surface of the tube into the aqueous nitric acid solution is small. The atmosphere contains pollutants including potassium, sodium, and iron. If the atmosphere is introduced into the hollow portion formed when the tube is extruded using an extruder, the pollutants may sometimes adhere to the inner surface of the tube. The amount of potassium, sodium, and iron dissolved becomes a benchmark for determining the degree of metal contamination on the inner surface of the tube. The amount of potassium, sodium, and iron dissolved from the inner surface of the tube disclosed herein into the aqueous nitric acid solution is preferably less than 0.50 ng, more preferably less than 0.45 ng. The lower limit of the amount of potassium, sodium, and iron dissolved may be 0.01 ng.

[0037] The amount of potassium, sodium and iron dissolved from the inner surface of the tube into the aqueous nitric acid solution can be determined as follows: 15 mL of 1N aqueous nitric acid solution is added into the tube, left for 3 days, the aqueous nitric acid solution is recovered, and the content of potassium, sodium and iron in the recovered aqueous nitric acid solution is measured by inductively coupled plasma mass spectrometry.

[0038] In one embodiment of the tube of the present disclosure, the metal content measured by the ashing method of the tube is low. The metal content of the tube of the present disclosure measured by the ashing method is preferably 40 ng / 1g or less, more preferably 30 ng / 1g 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 / 1g.

[0039] The metal content measured by the ashing method in the present disclosure is the total metal content of Fe, Cr, Ni, Cu, Al, Na, Mg and K. The metal content in the present disclosure includes not only the amount of metal components present on the surface of the tube, but also the amount of metal components contained in the interior of the tube. Even for the trace metal components contained in the interior of the tube, there are fine gaps of molecular size and reagent molecules that can penetrate near the depth of the reagent contact surface of several nanometers to several microns, and the metal contained in the resin that cannot be detected by the short-term metal dissolution analysis method may be dissolved for a long time. By making the metal content measured by the ashing method of the tube within the above range, the adverse effects caused by the dissolution of trace metal components contained in the interior of the tube can be reduced.

[0040] The metal content of the tube can be determined by the following methods: cutting the tube into pieces of about 5 cm in length, cleaning the surface of the tube with a 1N nitric acid aqueous solution, cutting it, ashing the cut material in a small groove located in the atomization part of the atomic absorption spectrophotometer, and using the atomic absorption spectrophotometer to determine the metal content; weighing the cut material prepared in the same way as above in a platinum crucible, ashing it using a gas burner or an electric furnace, dissolving the ash in acid, and then determining the metal content using an ICP emission analyzer or a flameless atomic absorption spectrophotometer; etc.

[0041] In one embodiment of the tube of the present invention, the surface roughness Ra of the inner surface of the tube is small. The surface roughness Ra of the inner surface of the tube of the present invention is preferably less than 5.0 nm, more preferably less than 4.0 nm, further preferably less than 3.0 nm, and further preferably less than 2.9 nm. The lower limit of the surface roughness Ra of the inner surface may be 0.1 nm. By making the surface roughness Ra of the inner surface of the tube within the above range, both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube can be further reduced. The surface roughness Ra of the inner surface of the tube can be adjusted by appropriately selecting the type of FAVE unit in the TFE / FAVE copolymer, appropriately adjusting the content of the FAVE unit, and the like.

[0042] The surface roughness Ra of the inner surface of the tube can be measured using an atomic force microscope (AFM).

[0043] Next, the copolymer forming the tube of the present disclosure will be described.

[0044] The tube of the present disclosure contains a tetrafluoroethylene (TFE) / fluoroalkyl vinyl ether (FAVE) copolymer.

[0045] As FAVE, there can be mentioned those selected from the general formula (1):

[0046] CF2=CFO(CF2CFY 1 O) p -(CF2CF2CF2O) q -Rf (1)

[0047] (In the formula, Y 1 represents F or CF3, 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 the general formula (2):

[0048] CFX=CXOCF2OR 1 (2)

[0049] (wherein, X is the same or different and represents H, F or CF3, R 1 It represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms which may or may not contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may or may not contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I. At least one of the group consisting of monomers represented by ).

[0050] Among them, as FAVE, the monomer represented by the general formula (1) is preferred, more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE), further preferably at least one selected from the group consisting of PEVE and PPVE, and particularly preferably PPVE.

[0051] The copolymer is preferably a fluororesin having melt processability. In the present disclosure, melt processability means that the polymer can be melted and processed using existing processing equipment such as an extruder and an injection molding machine. Therefore, the melt flow rate of the melt processable fluororesin measured by the measurement method described below is usually 0.01 g / 10 minutes to 500 g / 10 minutes.

[0052] The content of the FAVE unit of the copolymer is 3.0% to 12.0% by mass relative to all monomer units, preferably 3.5% by mass or more, more preferably 4.0% by mass or more, further preferably 4.5% by mass or more, preferably 10.0% by mass or less, more preferably 8.0% by mass or less, further preferably 7.0% by mass or less, further preferably 6.5% by mass or less, and particularly preferably 6.0% by mass or less.

[0053] The content of the TFE unit in the copolymer is preferably 88.0% by mass to 97.0% by mass, more preferably 90.0% by mass or more, further preferably 92.0% by mass or more, further preferably 93.0% by mass or more, particularly preferably 93.5% by mass or more, most preferably 94.0% by mass or more, more preferably 96.5% by mass or less, further preferably 96.0% by mass or less, further preferably 95.5% by mass or less, relative to all monomer units.

[0054] The copolymer may contain monomer units derived from monomers copolymerizable with TFE and FAVE.

[0055] Examples of monomers copolymerizable with TFE and FAVE include hexafluoropropylene (HFP), CZ 3 Z 4 =CZ 5 (CF2) n Z 6 (Where Z 3 , Z 4 and Z 5 Same or different, means H or F, Z 6 represents H, F or Cl, n represents an integer from 2 to 10) and CF2=CF-OCH2-Rf 7 (Where Rf 7 The alkyl perfluorovinyl ether derivatives represented by (represents a perfluoroalkyl group having 1 to 5 carbon atoms) are preferred. Among them, HFP is preferred.

[0056] The content of the monomer unit derived from the monomer copolymerizable with TFE and FAVE is preferably 0 to 9.0% by mass, more preferably 7.5% by mass or less, and even more preferably 1.0% by mass or less.

[0057] The copolymer is preferably at least one selected from the group consisting of a copolymer consisting only of a TFE unit and a FAVE unit and a TFE / HFP / FAVE copolymer, and more preferably a copolymer consisting only of a TFE unit and a FAVE unit.

[0058] The melt flow rate (MFR) of the copolymer is preferably 0.5 g / 10 min to 100 g / 10 min, more preferably 1 g / 10 min or more, further preferably 2 g / 10 min or more, more preferably 50 g / 10 min or less, further preferably 40 g / 10 min or less, further preferably 15 g / 10 min or less.

[0059] MFR is measured in accordance with ASTM D-1238 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.

[0060] The melting point of the copolymer is 280°C to 315°C, preferably 285°C or higher, more preferably 290°C or higher, and preferably 310°C or lower.

[0061] The melting point is the temperature corresponding to the maximum value in the heat of fusion curve when the temperature is increased at a rate of 10° C. / min using a differential scanning calorimeter [DSC].

[0062] The number of functional groups in the copolymer is relative to every 10 6 The number of carbon atoms is 500 or less, preferably 300 or less, more preferably 200 or less, further preferably 100 or less, further preferably 50 or less, and particularly preferably 10 or less.

[0063] In order to make the number of functional groups of the copolymer within the above range, it is usually necessary to perform a fluorination treatment described later. The reason is not clear, but by fluorinating the copolymer, it is easy to manufacture a tube in which both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube are further reduced. Therefore, from the perspective of reducing the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube, it is important to set the functional number of the copolymer contained in the tube of the present invention within the above range.

[0064] The functional groups are functional groups present at the main chain ends or side chain ends of the copolymer, and functional groups present in the main chain or in the side chain. As the functional groups, at least one selected from the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH is preferred.

[0065] The identification of the types of the functional groups and the measurement of the number of the functional groups can be performed using infrared spectroscopy.

[0066] Regarding the number of functional groups, specifically, the following method is used for determination. First, the copolymer is melted at 340°C to 350°C for 30 minutes and compression molded to produce a film with a thickness of 0.05mm to 0.25mm. The film is analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above-mentioned TFE / FAVE copolymer, and a differential spectrum with the background spectrum of the fully fluorinated functional group without functional groups is obtained. According to the following formula (A), the number of functional groups in the copolymer relative to each 1×10 6 The number of functional groups N per carbon atom.

[0067] N=I×K / t(A)

[0068] I: Absorbance

[0069] K: Correction coefficient

[0070] t: film thickness (mm)

[0071] For reference, regarding the functional groups in the present disclosure, the absorption frequency, molar absorption coefficient, and correction coefficient are shown in Table 1. The molar absorption coefficient is determined from FT-IR measurement data of a low-molecular model compound.

[0072] [Table 1]

[0073] Table 1

[0074]

[0075] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are several tens of kaise (cm2) lower than the absorption frequencies of -CF2H, -COF, free -COOH, and bound -COOH, -COOCH3, and -CONH2 shown in the table, respectively. -1 ).

[0076] Thus, for example, the functional group number of -COF is the absorption frequency 1883 cm due to -CF2COF. -1 The number of functional groups obtained from the absorption peak at 1840 cm-1 due to -CH2COF -1 The total number of functional groups found from the absorption peak at .

[0077] The above-mentioned number of functional groups may be the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH.

[0078] The tube of the present disclosure may contain fluororesins other than TFE / FAVE copolymers. As fluororesins other than TFE / FAVE copolymers, polytetrafluoroethylene may be cited. The content of polytetrafluoroethylene may be 0.001% to 50% by mass, or 0.001% to 1% by mass relative to the TFE / FAVE copolymer.

[0079] As polytetrafluoroethylene, polytetrafluoroethylene having a crystallization temperature of 305°C or higher measured by a differential scanning calorimeter (DSC) can be cited. The heat of crystallization of polytetrafluoroethylene can be 50 J / g or higher. By making the tube of the present disclosure contain such polytetrafluoroethylene, the inner surface of the tube can be made smoother. The crystallization temperature of polytetrafluoroethylene is more preferably 310°C or higher, and further preferably 312°C or higher.

[0080] In one embodiment of the tube disclosed herein, both ends are welded. By welding both ends, the cleanliness of the inner surface of the tube can be maintained.

[0081] Figure 1 Schematic cross-sectional view showing an embodiment of a pipe 1 with both ends welded. Figure 1 In the shown tube 1, welded portions 4 are provided around cut surfaces 3 exposed at both ends, and the hollow portion 2 of the tube 1 is sealed.

[0082] In one embodiment of the tube disclosed herein, both ends are welded, and gas that has passed through a filter is sealed in the hollow portion. By sealing a highly clean gas in the tube, the high cleanliness of the inner surface of the tube can be maintained for a long time.

[0083] The outer diameter of the tube is not particularly limited, and may be 2 mm to 100 mm, 3 mm to 100 mm, or 5 mm to 50 mm. The thickness of the tube may be 0.1 mm to 10 mm, or 0.3 mm to 5 mm.

[0084] The tube disclosed herein can be suitably used as a reagent piping tube for circulating a reagent, and can be particularly suitably used as a reagent piping tube for conveying a high-purity reagent for semiconductor device manufacturing.

[0085] In semiconductor factories, a large number of tubes are used to circulate ultrapure water or high-purity reagents used to manufacture semiconductor devices. The inner surface of the tube may be contaminated by pollutants such as particles in the air and polymer fumes generated when TFE / FAVE copolymers are melt-molded. In particular, nano-sized pollutants are attached to the inner surface of the polymer through van der Waals forces, electrostatic forces, etc., and are therefore difficult to remove with cleaning water such as pure water. Therefore, when new tubes are used in semiconductor factories, there are the following problems: in order to clean (rinse) the inside of the tube, a large amount of ultrapure water and reagents are required, and long-term cleaning is required.

[0086] Since the tube of the present invention has the above-mentioned structure, pollutants are basically not attached to the inner surface, and it is difficult to contaminate ultrapure water and high-purity reagents used for manufacturing semiconductor devices. Since the tube of the present invention has such an effect, it is preferably used as a reagent piping tube for circulating reagents. As the above-mentioned reagents, reagents used in semiconductor manufacturing can be cited, for example, reagents such as ammonia water, ozone water, hydrogen peroxide, hydrochloric acid, sulfuric acid, resist solution, thinner solution, and developer can be cited.

[0087] The tube disclosed in the present invention can be used as a tube used in semiconductor manufacturing equipment or semiconductor manufacturing devices such as a reagent supply line for semiconductor manufacturing, a reagent supply device for semiconductor manufacturing, a semiconductor cleaning device, and a coating and developing device. By using the tube disclosed in the present invention in semiconductor manufacturing equipment or semiconductor manufacturing devices, high-purity reagents can be reliably supplied to the point of use. By using the tube disclosed in the present invention, even when manufacturing semiconductor devices with a line width of less than 5nm, defects caused by particles or metal contaminants in semiconductor devices can be reduced, and it can be expected to improve the yield rate in the manufacture of semiconductor devices.

[0088] The pipe of the present disclosure can be suitably manufactured by the manufacturing method of the present disclosure. Next, the manufacturing method of the pipe of the present disclosure will be described.

[0089] In the production method disclosed herein, the TFE / FAVE copolymer is subjected to fluorination treatment, and then the fluorinated copolymer is extruded using an extruder to produce a tube.

[0090] Fluorination treatment can be carried out by contacting the copolymer that has not been fluorinated with a fluorine-containing compound. By fluorination treatment of the copolymer, a tube with a reduced number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube can be manufactured. The reason is not clear, but it is speculated that if the copolymer is extruded after fluorination treatment, the generation of volatiles from the copolymer caused by heating during extrusion molding is suppressed, and the number of particles and organic matter that can be attached to the inner surface of the tube is reduced, and due to the reduction in the number of particles, the discharge efficiency of particles and organic matter caused by the gas circulating in the tube is significantly improved.

[0091] The functional group is introduced into the copolymer, for example, by a chain transfer agent or polymerization initiator used when manufacturing the copolymer. For example, when an alcohol is used as a chain transfer agent or a peroxide having a -CH2OH structure is used as a polymerization initiator, -CH2OH is introduced into the main chain end of the copolymer. In addition, by polymerizing a monomer having a functional group, the functional group is introduced into the side chain end of the copolymer.

[0092] By fluorinating the copolymer having such functional groups, a copolymer having the number of functional groups within the above range can be obtained. That is, the TFE / FAVE copolymer is preferably a fluorinated copolymer. In addition, the TFE / FAVE copolymer also preferably has a -CF3 terminal group.

[0093] The fluorine-containing compound is not particularly limited, and a fluorine radical source that generates fluorine radicals under fluorination conditions can be cited. As the fluorine radical source, F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, fluorinated halogens (e.g., IF5, ClF3), etc. can be cited.

[0094] The fluorine radical source such as F2 gas can be 100% concentration, but from the aspect of safety, it is preferably mixed with an inert gas and diluted to 5% to 50% by mass, and more preferably diluted to 15% to 30% by mass. As the above-mentioned inert gas, nitrogen, helium, argon, etc. can be cited, and nitrogen is preferred from the aspect of economy.

[0095] The conditions of the fluorination treatment are not particularly limited, and the copolymer in a molten state may be brought into contact with the fluorine-containing compound, but it may be generally carried out at a temperature below the melting point of the copolymer, preferably at 20°C to 220°C, and more preferably at 100°C to 200°C. The fluorination treatment is generally carried out for 1 hour to 30 hours, preferably for 5 hours to 25 hours. The fluorination treatment is preferably a treatment in which the copolymer that has not been fluorinated is brought into contact with fluorine gas (F2 gas).

[0096] The TFE / FAVE copolymer can be produced, for example, by appropriately mixing monomers serving as its structural units and additives such as a polymerization initiator and performing a conventionally known method such as emulsion polymerization or suspension polymerization.

[0097] Preferably, in each process of the manufacturing method for manufacturing copolymers such as polymerization process, granulation process, cleaning process, drying process, conveying process, storage process, pelletization process, fluorination process, product filling process, etc., the materials and copolymers used in the manufacturing are not allowed to contact the metal surfaces of each device and piping as much as possible, and as the materials used in the manufacturing, materials with low metal content are used, and further, as the air used to dry the obtained copolymer and the air used for conveying between the devices of the copolymer, clean and dry air is used, thereby manufacturing TFE / FAVE copolymers. By using such a manufacturing method, copolymers with less metal content measured by ashing method can be manufactured. Moreover, by using such a copolymer, a tube with less metal content measured by ashing method can be obtained.

[0098] In the manufacturing method disclosed in the present invention, when the copolymer is extruded, the gas that passes through the particle removal filter after passing through the organic matter removal filter is circulated into the tube from the front end of the tube. In this way, by allowing the gas to circulate from the front end of the tube into the tube, the pollutants contained in the hollow part of the tube can be discharged from the hollow part. In addition, since organic matter and particles are removed from the gas supplied to the tube, organic matter and particles will not adhere to the inner surface of the tube by allowing the gas to circulate into the tube. Furthermore, the gas supplied from the front end of the tube is discharged to the outside through the die of the extruder, so the metal components generated by the die will not adhere to the inner surface of the tube. Therefore, by using the manufacturing method disclosed in the present invention, a tube with a reduced number of particles released from the inner surface of the tube and a reduced amount of total organic carbon (TOC) dissolved from the inner surface of the tube can be manufactured. Furthermore, by using the manufacturing method disclosed in the present invention, a tube with a small amount of potassium, sodium and iron dissolved can be manufactured. In addition, a tube with a small metal content measured by an ashing method and a tube with a low surface roughness Ra of the inner surface of the tube can be manufactured.

[0099] As the organic matter filter, a chemical adsorption filter using hydrogen bonds or acid-base bonds, a physical adsorption filter using van der Waals forces, etc. can be used. As the organic matter filter, a physical adsorption filter is preferred. By using a physical adsorption filter, organic matter such as plasticizers and oil mist present in the gas can be removed efficiently.

[0100] As the organic matter filter, one or more filters may be used. In addition, a plurality of organic matter filters may be connected in series or in parallel.

[0101] As the organic matter filter, a filter in which an adsorbent is filled in a column can be used. As the adsorbent, activated carbon, silica gel, zeolite, etc. can be used.

[0102] As the adsorbent, activated carbon is preferred. The activated carbon may be granular activated carbon or fibrous activated carbon. As the activated carbon, activated carbon with a small content of metal components is preferred. As the activated carbon, activated carbon made from coconut shells, coal, charcoal, etc. can be cited, and activated carbon from plants is preferred.

[0103] The larger the specific surface area of ​​the activated carbon measured by the BET method, the better, preferably 400 m 2 / g or more, more preferably 1000m 2 / g or above.

[0104] In the manufacturing method disclosed herein, the gas is passed through an organic matter removal filter, then through a particle removal filter, and then supplied to the tube. By supplying the gas using such a method, even if particles generated by the organic matter removal filter are mixed into the gas, the generated particles are captured by the particle removal filter, thereby preventing the particles from entering the tube. On the other hand, if the gas is passed through a particle removal filter, then through an organic matter removal filter, and then supplied to the tube, the introduction of particles into the tube cannot be prevented, and the particles may adhere to the inner surface of the tube.

[0105] The particle filtration accuracy of the particle removal filter is preferably 30 nm or less, more preferably 10 nm or less, further preferably 5 nm or less, particularly preferably 3 nm or less, and preferably 1 nm or more.

[0106] The capture efficiency of the particle removal filter is not particularly limited. As the particle removal filter, a filter that captures 99.99% or more of particles larger than 30 nm is preferred, a filter that captures 99.99% or more of particles larger than 10 nm is more preferred, a filter that captures 99.99% or more of particles larger than 5 nm is further preferred, and a filter that captures 99.99% or more of particles larger than 3 nm is particularly preferred.

[0107] As the particulate removal filter, one or more filters may be used. Alternatively, a plurality of particulate removal filters may be connected in series or in parallel.

[0108] Next, the production method of the present disclosure will be described in more detail with reference to the drawings.

[0109] Figure 2 is a schematic side view of a tube manufacturing apparatus, Figure 3 It is a schematic front view of the winding device.

[0110] Figure 2 The tube manufacturing device 100 shown includes: an extruder 10 that melts the copolymer and extrude it into a tube; a shaping die 40 that determines the outer diameter of the extruded molten tube; a cooling water tank 50 that cools and solidifies the molten tube; a traction machine 60 that tractions the cooled tube; a winding device 70 that winds up the tube sent out from the traction machine; and a gas supply device 80 that supplies gas to the winding device 70.

[0111] In the tube manufacturing device 100, the copolymer fed from the hopper 11 of the extruder 10 is melted in the barrel of the extruder 10, and the molten copolymer is extruded into a tube from the die 20 by the rotation of the screw. The molten copolymer extruded into a tube passes through the shaping die 40, and its shape is regulated. The copolymer after passing through the shaping die 40 is cooled in the cooling water tank 50, and then the traction machine 60 that tractions the cooled copolymer tube is wound on the reel 75 of the winding device 70. The traction speed (linear speed) at this time is usually 30 cm / min to 150 cm / min, and can also be 30 cm / min to 120 cm / min.

[0112] In one embodiment of the manufacturing method disclosed herein, the copolymer is melted and extruded into a tube from a die provided by an extruder, and the copolymer extruded into a tube from the die provided by the extruder is guided to a cooling device and cooled, and then the cooled tube is wound on a reel using a winding device, thereby manufacturing a tube. Furthermore, gas is supplied to the hollow portion of the tube from the front end of the tube wound on the reel, and the gas in the hollow portion is discharged to the outside through a gas discharge hole provided in the mold from a gas inlet provided in the mold. In this way, by supplying gas from the front end of the tube to the die of the extruder, a tube in which both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube are reduced can be manufactured.

[0113] In one embodiment of the manufacturing method disclosed herein, gas is supplied into the tube at a pressure that can suppress deformation of the tube and prevent contaminants from adhering to the inner surface of the tube. The internal pressure (gauge pressure) in the tube is preferably higher than atmospheric pressure and lower than 0.5 kgf / cm 2 The internal pressure (gauge pressure) in the tube is preferably 0.4 kgf / cm 2 Less than, more preferably 0.3kgf / cm 2 Below, preferably 0.1kgf / cm 2 More preferably, 0.2 kgf / cm 2 above.

[0114] Figure 2 The extrusion molding machine shown has a die 20, and a copolymer in a molten state is extruded from an extrusion port provided in the die 20. The temperature of the copolymer extruded from the die of the extrusion molding machine is preferably 390° C. or less, more preferably 385° C. or less, further preferably 380° C. or less, further preferably 375° C. or less, particularly preferably 370° C. or less, and most preferably 365° C. or less, and is preferably above the melting point of the copolymer, more preferably 330° C. or more, and further preferably 350° C. or more.

[0115] The temperature of the copolymer extruded from the die of the extruder can be determined by measuring the temperature of the copolymer at the extrusion port of the die using a thermocouple. By lowering the temperature of the copolymer extruded from the die, both the number of particles released from the inner surface of the tube and the amount of total organic carbon (TOC) dissolved from the inner surface of the tube can be further reduced.

[0116] The extrusion molding machine 10 is further provided with a backflow prevention device 30, which is connected to the gas discharge hole 23 of the die 20, discharges gas to the outside of the extrusion molding machine 10, and prevents the backflow of gas. By preventing the backflow of gas, the atmosphere does not flow into the tube extruded from the extrusion molding machine 10, so even after the supply of gas from the front end of the tube is stopped, pollutants in the atmosphere do not adhere to the inner surface of the tube, and the clean inner surface can be maintained.

[0117] The pipe manufacturing apparatus 100 includes a winding device 70 . Figure 3 It is a diagram showing an embodiment of the winding device 70. Figure 3 The winding device 70 shown is a winding device for winding the tube 1, and comprises: a gas supply port 72, which supplies gas to the hollow portion of the tube 1; a filter 73, which is arranged at a position downstream of the gas supply port 72 and removes pollutants in the gas supplied from the gas supply port 72; a tube connecting port 74, which is arranged at a position downstream of the filter 73 and is connected to the tube 1; and a reel 75, which winds the tube.

[0118] The reel 75 is rotatably supported (axially supported) by a rotating shaft 77 provided on a support column 76 of a support frame, and is driven by a driving device 78 to rotate together with the rotating shaft 77 to reel up the tube 1. One end of the tube 1 is connected to the tube connection port 74 via a guide tube 71. Gas is supplied from the tube connection port 74 to the hollow portion of the tube 1. The tube 1 is reeled up on the reel 75 while the gas is flowing through the hollow portion.

[0119] The gas supply port 72 is connected to a gas supply device 80. Figure 2 As shown, the gas supply device 80 may be a gas cylinder filled with high-pressure gas, or a compressor, a blower, etc. A needle valve (not shown) may be provided in the gas supply device 80 to adjust the supply pressure of the gas.

[0120] The tube connection port 74 is connected to the gas supply port 72 via the filter 73. By supplying the gas having passed through the filter 73 to the hollow portion of the tube 1, a tube having a clean inner surface can be manufactured.

[0121] The type of gas supplied to the hollow portion of the tube 1 is not particularly limited, and may be an inert gas such as nitrogen, argon, helium, air, oxygen, halogen gas, etc. From the perspective of cost reduction, air is preferred.

[0122] Figure 3 In the embodiment, the organic matter removing filter 73a and the particulate matter removing filter 73b are provided in series connection. Figure 3 In the embodiment, one organic matter removal filter and one particulate removal filter are provided respectively, but a plurality of filters may be provided. For example, a plurality of particulate removal filters may be provided so that the gas passing through the organic matter removal filter passes through a plurality of particulate removal filters having different particulate filtration accuracies.

[0123] Winding device 70 further includes guide tube 71, one end of which is connected to tube connection port 74 and the other end of which is connected to tube 1. Gas is supplied from tube connection port 74 to the hollow portion of guide tube 71, and gas is also supplied to the hollow portion of tube 1 connected to guide tube 71.

[0124] exist Figure 3 In the winding device 70 shown, one end of the guide tube 71 is connected to the tube 1, but before the extrusion molding of the copolymer is started, the one end of the guide tube 71 is not connected to the tube 1. While supplying gas to the guide tube 71 and causing the gas to flow out from the front end of the guide tube 71, the front end of the guide tube 71 is connected to the front end of the copolymer extruded from the die 20, thereby supplying gas to the hollow part of the tube 1 in a molten state. After the front end of the guide tube 71 is connected to the front end of the copolymer extruded from the die 20, continuous extrusion of the copolymer from the die 20 is started, and the guide tube 71 and the cooled tube 1 are wound up. In this way, the tube can be manufactured while keeping the inner surface clean.

[0125] When the desired length of the tube is produced, the extrusion of the copolymer and the winding of the tube are stopped. After the extrusion of the copolymer is stopped, two arbitrary parts of the tube are welded and cut, thereby producing a tube with both ends sealed and the gas passing through the filter sealed in the hollow part. The inner surface of the tube obtained by such a production method will never come into contact with the atmosphere and is extremely clean.

[0126] The welded portion of the tube is not particularly limited. For example, if a portion of the tube is welded between the mold 20 and the shaping mold 40, or a portion of the tube is welded near the connection with the guide tube 71, the tube can be manufactured without waste. When the tube at the portion to be welded is in a molten state, it can be welded by clamping it with tweezers or the like. When the tube at the portion to be welded is cooled and solidified, it can be heated with a hot air gun or the like to locally melt the welded portion, and then clamped with tweezers or the like to weld it.

[0127] Although the embodiments have been described above, it should be understood that various modifications may be made to the embodiments and details without departing from the spirit and scope of the claims.

[0128] <1> According to a first aspect of the present disclosure, there is provided a tube comprising a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, wherein:

[0129] The number of functional groups of the above copolymer is relative to every 10 6 The number of carbon atoms is less than 500.

[0130] The melting point of the above copolymer is 280°C to 315°C.

[0131] The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0% to 12.0% by mass based on the total monomer units.

[0132] The melt flow rate of the copolymer is 1 g / 10 min to 15 g / 10 min.

[0133] The number of particles released from the inner surface of the tube is relative to 1 cm 2 The surface area of ​​the tube is less than 3500.

[0134] The amount of total organic carbon eluted into water from the inner surface of the tube is calculated based on the total organic carbon content per 1 cm 2 The surface area inside the tube is less than 50ng.

[0135] <2> According to a second aspect of the present disclosure, there is provided the tube according to the first aspect, wherein the content of the fluoroalkyl vinyl ether unit in the copolymer is 3.5% by mass to 8.0% by mass based on all monomer units.

[0136] <3> According to a third aspect of the present disclosure, there is provided a tube according to the first aspect or the second aspect, wherein the number of functional groups of the copolymer is 6 The number of carbon atoms is 100 or less.

[0137] <4> According to a fourth aspect of the present disclosure, there is provided a tube according to any one of the first to third aspects, wherein the amount of potassium, sodium, and iron eluted from the inner surface of the tube into the nitric acid aqueous solution is 2 The surface area inside the tube is less than 0.50ng.

[0138] <5> According to a fifth aspect of the present disclosure, there is provided a tube according to any one of the first to fourth aspects, wherein the metal content of the tube measured by an ashing method is 40 ng / 1g or less.

[0139] <6> According to a sixth aspect of the present disclosure, there is provided the tube according to any one of the first to fifth aspects, wherein the surface roughness Ra of the inner surface of the tube is 5.0 nm or less.

[0140] <7> According to a seventh aspect of the present disclosure, there is provided a pipe according to any one of the first to sixth aspects, wherein both ends of the pipe are welded.

[0141] <8> According to an eighth aspect of the present disclosure, there is provided a method for producing a tube, wherein after a copolymer is fluorinated, the fluorinated copolymer is extruded using an extruder, wherein:

[0142] The above copolymer is a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer,

[0143] The melting point of the above copolymer is 280°C to 315°C.

[0144] The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0% to 12.0% by mass based on the total monomer units.

[0145] The melt flow rate of the copolymer is 1 g / 10 min to 15 g / 10 min.

[0146] The temperature of the copolymer extruded from the die of the extruder is 390° C. or less.

[0147] During the extrusion molding, the gas that has passed through the organic matter removing filter and then the particulate matter removing filter is caused to flow into the tube from the front end of the tube.

[0148] <9> According to a ninth aspect of the present disclosure, there is provided a production method based on the eighth aspect, wherein as the organic matter removing filter, a filter filled with a filter having a specific surface area of ​​400 m 2 / g or more activated carbon column.

[0149] <10> According to a tenth aspect of the present disclosure, there is provided the production method according to the eighth aspect or the ninth aspect, wherein the particulate removal filter has a particulate filtration accuracy of 10 nm or less.

[0150] Example

[0151] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to the above examples.

[0152] Each numerical value in the examples was measured by the following method.

[0153] (composition)

[0154] pass 19 The measurement was carried out by F-NMR method.

[0155] (Melt Flow Rate (MFR))

[0156] The molecular weight was determined by measuring 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 and a load of 5 kg using a melt flow indexer (manufactured by Yasuda Seiki Co., Ltd.) in accordance with ASTM D1238.

[0157] (Melting Point)

[0158] The temperature was determined using a differential scanning calorimeter [DSC] as a temperature corresponding to a local maximum value in a heat of fusion curve when the temperature was increased at a rate of 10° C. / min.

[0159] (Number of functional groups)

[0160] The copolymer was melted at 340°C to 350°C for 30 minutes and compression molded to produce a film with a thickness of 0.05 mm to 0.25 mm. The film was scanned 40 times by a Fourier transform infrared spectrometer [FT-IR (Spectrum One, manufactured by PerkinElmer)] and analyzed to obtain an infrared absorption spectrum, and a differential spectrum with a background spectrum of a completely fluorinated functional group without functional groups was obtained. The absorption peak of a specific functional group shown in the differential spectrum was calculated according to the following formula (A) relative to every 1×10 6 The number of functional groups N per carbon atom.

[0161] N=I×K / t(A)

[0162] I: Absorbance

[0163] K: Correction coefficient

[0164] t: film thickness (mm)

[0165] For reference, regarding the functional groups in the present disclosure, the absorption frequency, molar absorption coefficient, and correction coefficient are shown in Table 2. The molar absorption coefficient is determined from FT-IR measurement data of a low-molecular model compound.

[0166] [Table 2]

[0167] Table 2

[0168]

[0169] (Number of particles)

[0170] In a class 100 clean room, the tubes produced in the examples and comparative examples were cut into pieces of 0.5 m to produce tubes A.

[0171] Used in the measurement Figure 4The system 9 shown in the figure and commercially available high-purity isopropyl alcohol (IPA) were used. As the filter 94, an inline filter (NHM series, filtration accuracy 3 nm) manufactured by Kitz Micro Filter was used. As the particle counter, a light scattering liquid particle detector KS-19F manufactured by RION was used.

[0172] Using a particle counter, it was confirmed in advance that the number of particles with a diameter of 30 nm or more released from the measurement line into IPA was 10 particles / mL or less.

[0173] Place tube A with Figure 4 After the connectors 95 and 96 of the system 9 shown were connected, IPA was flowed through the tube A at a flow rate of 10 mL / min for 10 minutes to clean the inner surface of the tube A. It was confirmed that the number of particles in the IPA used for cleaning was 10 particles / mL or less.

[0174] Next, the pump 92 was stopped, and the tube A was left to stand for 6 hours while the tube A was filled with IPA.

[0175] Start supplying IPA into tube A again, and allow IPA to flow into tube A at a flow rate of 110 mL / min. Introduce a portion of the IPA that has passed through tube A into a light scattering liquid particle detector (particle counter) at a flow rate of 10 mL / min to measure the number of particles in IPA. In about 10 minutes, the number of particles drops to the blank level, but the measurement is continued for 16 minutes. The interval between each measurement is set to 2 seconds, and the number of particles is measured 15 times in total. The 15 measured values ​​(pieces / mL) are multiplied by 110 and accumulated, and the accumulated value is divided by the surface area of ​​the inner surface of tube A to calculate the number of particles released from tube A into IPA (pieces / cm 2 ).

[0176] (TOC dissolution amount)

[0177] A filter (Polyfix F50 series (F50C50TP-C2) manufactured by Kitz Micro Filter with a particle filtration accuracy of 5 nm), a flow meter (differential pressure flow controller (Z900M-1 / 4-09-AN531S) manufactured by Surpass), and a TOC meter (TAC-ACCURA-R manufactured by T&C Technical, ultraviolet oxidation decomposition conductivity method) were connected with pipes to prepare a measurement line for measuring the elution amount of TOC.

[0178] Set the flow rate of ultrapure water flowing through the flowmeter to 110 mL / min, and the flow rate of ultrapure water flowing through the TOC measuring unit of the TOC meter to 20 mL / min. Drain the remaining ultrapure water that is not introduced into the TOC meter from other pipes. Continue to pass ultrapure water for 1 hour and confirm that the TOC value is less than 1 ppb.

[0179] The tubes produced in the examples and comparative examples were cut into a length of 1 m and installed between the filter and the flow meter in the measurement line.

[0180] The TOC value was measured continuously at 5-second intervals, and the TOC elution amount (ng) was calculated from the peak area for 5 minutes from the start of the peak detection. The calculated value was multiplied by 110 / 20 and then divided by the inner surface area of ​​the tube (124 cm 2 ), calculate the TOC dissolution amount (ng / cm 2 ).

[0181] (Dissolution of potassium, sodium and iron)

[0182] The tubes prepared in the examples and comparative examples were cut into a length of 150 cm, bent into a U shape, and fixed with a strapping tape. 15 mL of a high-purity 1N nitric acid aqueous solution was added to the tube. After being left for 3 days, the amount of metal in the nitric acid aqueous solution was measured using an inductively coupled plasma mass spectrometer. The measured value (ng / mL) was multiplied by the amount of nitric acid used to calculate the amount of dissolved metal (ng), and the calculated value was divided by the contact area between the inner surface of the tube and the nitric acid to determine the amount of potassium, sodium, and iron dissolved into the nitric acid aqueous solution (ng / cm 2 ).

[0183] (Metal content determined by ashing method)

[0184] The ashing method described in International Publication No. 94 / 28394 was used. The tubes prepared in the Examples and Comparative Examples were cut into a length of about 5 cm, washed with a high-purity 1N nitric acid aqueous solution, and then cut. The cut pieces were accurately weighed in the range of 2 mg to 6 mg, and heated at 1100° C. for 180 seconds in a small graphite tank to ash, and analyzed using an atomic absorption spectrophotometer (polarized Zeeman atomic absorption spectrophotometer (Z-8100), manufactured by Hitachi, Ltd.).

[0185] (Surface roughness Ra of the inner surface of the tube)

[0186] The atomic force microscope (AFM) topography images of the inner surfaces of the tubes produced in the examples and comparative examples were subjected to automatic tilt correction processing, thereby calculating the surface roughness Ra of the inner surfaces of the tubes.

[0187] The surface roughness Ra is the value obtained by extracting only a reference length L from the roughness curve along the direction of its average line, and summing up and averaging the absolute values ​​of the deviations from the average line of the extracted part to the measured curve (arithmetic mean roughness). When the direction of the average line of the extracted part is taken as the x-axis and the direction of the longitudinal magnification is taken as the y-axis, and the roughness curve is expressed by y=f(x), the calculation formula of the surface roughness Ra is as follows.

[0188] [Number 1]

[0189] Number 1

[0190]

[0191] Example 1

[0192] Except for changing the amount of monomer used, pellets of TFE / PPVE copolymer (TFE / PPVE=94.5 / 5.5 (mass %), MFR=2 (g / 10 min), melting point=303 (°C)) were prepared in the same manner as in Example 1 of International Publication No. 2019 / 187859.

[0193] The obtained pellets were heated to 200°C and contacted with a mixed gas containing nitrogen and fluorine (fluorine concentration = 30% by volume). The total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH in the copolymer in the obtained pellets was 10 6 The number of carbon atoms is 5 or less.

[0194] Use the obtained pellets and Figure 2 The tube manufacturing device shown manufactures a 1 / 4 inch tube with an outer diameter of 6.35 mm and an inner diameter of 3.95 mm. An extrusion molding machine (barrel shaft diameter 30 mm, L / D=22) is used to perform extrusion molding at a pulling speed of 0.4 m / min. The screw speed of the extrusion molding machine is 4.2 rpm and the pulling speed is 41 cm / min to adjust the wall thickness of the tube. The temperatures of the barrel (C1, C2, C3), neck (A), head (D1) and front end of the die (D2) of the extrusion molding machine are set to 330°C to 360°C. The temperature of the copolymer at the front end of the die (temperature of the copolymer at the die outlet) is 360°C.

[0195] The organic matter removal filter (filled with a specific surface area of ​​about 1200 (m 2 / g) of activated carbon in-line filter) and a particulate removal filter (Kitz Micro Filter in-line filter (NHM series, particulate filtration accuracy 3nm)) are connected in series. Air is passed through the organic matter removal filter and the particulate removal filter in sequence, and then air is supplied into the tube from the front end of the tube.

[0196] The air flow rate was adjusted using a needle valve, and the air supply was continued at a flow rate such that the pressure in the tube was higher than the atmospheric pressure and the copolymer in a molten state extruded from the die head of the extruder was not deformed. A manual sealer with a hot plate manufactured by Rongguang Electric Co., Ltd. was used to weld two arbitrary locations of the obtained tube to obtain a tube with both ends sealed. The results are shown in Table 3.

[0197] Example 2

[0198] A tube with both ends sealed was obtained in the same manner as in Example 1 except that the temperatures of the cylinder, neck, head and die tip of the extruder were changed so that the temperature of the copolymer at the die outlet became 380°C.

[0199] Comparative Examples 1 to 6

[0200] A tube with both ends sealed was obtained in the same manner as in Example 1 except that the production conditions of the tube were changed as described in Table 3. The results are shown in Table 3.

[0201] As implemented in Example 1, the direction in which air is supplied from the front end of the tube toward the mold is recorded as "counterflow" in Table 3. The direction in which air is supplied from the mold toward the front end of the tube (the opposite direction to the supply direction in Example 1) is recorded as "downstream" in Table 3. When air is supplied from the mold toward the front end of the tube, air that has passed through the organic matter removal filter and then the particulate removal filter is also supplied into the tube.

[0202]

[0203] Description of Reference Numerals

[0204] 1 tube

[0205] 2 Hollow part

[0206] 100 tube manufacturing device

[0207] 10Extrusion molding machine

[0208] 20 molds

[0209] 30 Backflow prevention device

[0210] 40 Plastic Sculpting Mold

[0211] 50 Cooling device (cooling water tank)

[0212] 60 tractor

[0213] 70 Winding device

[0214] 71 guide tube

[0215] 73a Organic matter removal filter

[0216] 73b Particulate Removal Filter

[0217] 80 Gas supply device

[0218] 9 System

[0219] 91 Solvent container

[0220] 92 Pumps

[0221] 93 valve

[0222] 94 Filters

[0223] 95, 96 connector

[0224] 97 Particle Counter

[0225] 98, 99 flow meter

Claims

1. A tube comprising a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, wherein: The number of functional groups of the copolymer is relative to every 10 6 The number of carbon atoms is less than 500. The melting point of the copolymer is 280°C to 315°C. The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0% to 12.0% by mass based on the total monomer units. The melt flow rate of the copolymer is 1 g / 10 minutes to 15 g / 10 minutes, The number of particles released from the inner surface of the tube is relative to the amount per 1 cm 2 The surface area of ​​the tube is less than 3500. The amount of total organic carbon eluted from the inner surface of the tube into the water is relative to 1 cm 2 The surface area inside the tube is less than 50ng.

2. The tube according to claim 1, wherein The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.5% by mass to 8.0% by mass based on the total monomer units.

3. The tube according to claim 1 or 2, wherein: The number of functional groups of the copolymer is relative to every 10 6 The number of carbon atoms is 100 or less.

4. The tube according to any one of claims 1 to 3, wherein The amount of potassium, sodium, and iron eluted from the inner surface of the tube into the nitric acid aqueous solution was calculated based on the amount of potassium, sodium, and iron eluted from the inner surface of the tube into the nitric acid aqueous solution per 1 cm 2 The surface area inside the tube is less than 0.50ng.

5. The tube according to any one of claims 1 to 4, wherein The metal content of the tube measured by an ashing method was 40 ng / 1 g or less.

6. The tube according to any one of claims 1 to 5, wherein The surface roughness Ra of the inner surface of the tube is 5.0 nm or less.

7. The pipe according to any one of claims 1 to 6, wherein both ends thereof are welded.

8. A method for manufacturing a tube, wherein after a copolymer is fluorinated, the fluorinated copolymer is extruded by an extruder, wherein: The copolymer is a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, The melting point of the copolymer is 280°C to 315°C. The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0% to 12.0% by mass based on the total monomer units. The melt flow rate of the copolymer is 1 g / 10 minutes to 15 g / 10 minutes, The temperature of the copolymer extruded from the die of the extruder is 390° C. or less, During the extrusion molding, the gas that has passed through the organic matter removing filter and then the particulate matter removing filter is caused to flow into the tube from the front end of the tube.

9. The manufacturing method according to claim 8, wherein: As the organic matter removal filter, a filter filled with a specific surface area of ​​400 m2 measured by the BET method was used. 2 / g or more activated carbon column.

10. The manufacturing method according to claim 8 or 9, wherein: The particle removal filter has a particle filtration accuracy of 10 nm or less.

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