Tube and method for manufacturing the tube

Abstract

To provide a tube which is reduced in the number of particles discharged from an inner face of the tube, and also reduced in an elution amount of total organic carbon (TOC) eluted from the inner face of the tube.SOLUTION: In a tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, a functional group number of the copolymer is equal to or smaller than 500 pieces per carbon number 106, a melting point of the copolymer is 280 to 315°C, a content of a fluoroalkyl vinyl ether unit of the copolymer is 3.0 to 12.0 mass% with respect to a total monomer unit, a melt flow rate of the copolymer is 1 to 15 g / 10 min., the number of particles discharged from an inner face of the tube is equal to or smaller than 3,500 pieces per tube inner-face area 1 cm2, and an elution amount of total organic carbon eluted into water from the inner face of the tube is equal to or smaller than 50 ng per tube inner-face area 1 cm2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to tubes and methods for making the tubes. [Background technology]

[0002] Patent Document 1 describes a method for producing a fluororesin tube with reduced particles, which is characterized in that in the method for producing a fluororesin tube by melt-extruding a fluororesin or a resin mixture based on fluororesin into a tubular shape, clean air is flowed into the tube after or during tube formation to purge particles inside the tube.

[0003] Patent Document 2 describes a method for producing a tube in which a melt-processable fluororesin extruded into a tube shape from a die provided in an extrusion molding machine is introduced into a cooling device to cool it, and then the cooled tube is wound up on a take-up reel using a winding device. In this method, gas is supplied to the hollow part of the tube from the tip of the tube wound up on the take-up reel, and the gas in the hollow part is exhausted to the outside through a gas inlet provided in the die and a gas exhaust hole provided in the die, thereby circulating the gas in the hollow part and raising the internal pressure of the hollow part to 0.5 kgf / cm, which is higher than atmospheric pressure. 2 A manufacturing method is described that keeps the pressure lower than [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-233435 A [Patent Document 2] International Publication No. 2022 / 059501 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is 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. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, the copolymer having a functional group of 10 carbon atoms. 6 the copolymer has a melting point of 280 to 315°C, the content of fluoroalkyl vinyl ether units in the copolymer is 3.0 to 12.0 mass% based on the total monomer units, the copolymer has a melt flow rate of 1 to 15 g / 10 min, and the number of particles released from the inner surface of the tube is 1 to 15 g / 10 min per 1 cm of inner surface area of ​​the tube. 2 The amount of total organic carbon eluted from the inner surface of the tube into the water is 3,500 or less per 1 cm of the inner surface area of ​​the tube. 2 Tubes containing 50 ng or less per tube are provided. Effect of the Invention

[0007] According to the present disclosure, it is possible 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) eluted from the inner surface of the tube are both reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an embodiment of a tube with both ends welded together. [Diagram 2] FIG. 2 is a schematic side view of a tube manufacturing apparatus. [Diagram 3] FIG. 3 is a schematic front view of the winding device. [Figure 4] FIG. 1 is a schematic diagram of a system used to measure the number of particles emitted from the inner surface of a tube. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0010] Patent Document 1 describes a method of supplying clean air into the tube from the tip of the tube to perform a purging process. However, the method described in Patent Document 1 makes it difficult to remove contaminants that have adhered to the inner surface of the tube.

[0011] In Patent Document 2, gas is supplied to the hollow part of the tube from the tip of the tube wound on the take-up reel, and the gas in the hollow part is discharged to the outside through a gas inlet provided in the mold and a gas exhaust hole provided in the mold, thereby circulating the gas in the hollow part and raising the internal pressure of the hollow part to 0.5 kgf / cm, which is higher than atmospheric pressure. 2 In the present invention, a manufacturing method has been proposed that enables the production of tubes having clean inner surfaces and excellent dimensional stability with high productivity by manufacturing the tubes while maintaining the pressure lower than the normal pressure.

[0012] The tubes obtained by the manufacturing method described in Patent Document 2 have an extremely high degree of cleanliness. However, by further studying the manufacturing method, it has been newly discovered that it is possible 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) eluted from the inner surface of the tube are further reduced.

[0013] 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 1 cm2 of the inner surface area of ​​the tube. 2 The total organic carbon eluted from the tube into the water is less than 3500 particles per square centimeter of the tube surface area. 2 The tubes contain less than 50 ng per tube.

[0014] The number of particles emitted from the inner surface of the tube of the present disclosure is extremely small. The number of particles emitted from the inner surface of the tube of the present disclosure is 1 cm2 of the inner surface area of ​​the tube. 2 The particle number is 3500 or less, preferably 3200 or less, more preferably 2500 or less, and even more preferably 2000 or less per unit time. The lower limit of the number of particles may be 1. In the present disclosure, the particle number refers to the number of particles with a diameter of 30 nm or more that are released into isopropyl alcohol (IPA) from the inner surface of a tube when IPA is flowed through the tube at a flow rate of 110 mL / min.

[0015] The number of particles emitted from the inner surface of the tube is measured by the following method. This method is a new method, which can measure the number of particles emitted from the inner surface of the tube with higher accuracy than conventional methods.

[0016] 4 is a system diagram of a system used in the present disclosure for measuring the number of particles emitted from the inner surface of a tube. As shown in FIG. 4, the system 9 includes a solvent container 91, a filter 94, and a particle counter 97.

[0017] Solvent container 91 contains isopropyl alcohol (IPA) and is connected to joint 95 via pump 92, valve 93, and filter 94. Joints 95 and 96 are configured so that tube 1, which is the object of measurement, can be connected. The IPA in solvent container 91 is passed through filter 94 (filtration accuracy 3 nm) by pump 92 and supplied to tube 1 connected to joints 95 and 96. A part or all of the IPA that has passed through tube 1 is introduced into particle counter 97, and the number of particles in the solvent is measured.

[0018] 4, a flow meter 98 is installed downstream of a particle counter 97, and a fixed amount of IPA is introduced into the particle counter 97. The flow rate of the remaining IPA is adjusted by a flow control valve attached to the flow meter 99, and the remaining IPA is discharged to the outside via the flow meter 99. A particle counter with a built-in flow meter 98 may be used as the particle counter 97.

[0019] The number of particles released from the inner surface of the tube can be measured by the following method. The system 9 shown in FIG. 4 was constructed, and the liquid-contacting surfaces of each component of the system 9 were cleaned with IPA. Then, the tube 1 to be measured was placed upstream of the particle counter. The inner surface of tube 1 is cleaned by flowing IPA into tube 1 while measuring the number of particles with a diameter of 30 nm or more in the IPA used to clean the inner surface of tube 1 using a particle counter. Confirm that the number of particles in the IPA used to clean the inner surface of tube 1 is 10 particles / mL or less. Stop the supply of IPA into tube 1, and leave tube 1 filled with IPA for 6 hours (at room temperature, no pressure), The supply of IPA into tube 1 is resumed, and IPA is allowed to flow into tube A at a flow rate of 110 mL / min. Using a particle counter, the number of particles with a diameter of 30 nm or more in the IPA that has passed through tube 1 is measured.

[0020] The tube disclosed herein has an extremely low amount of total organic carbon (TOC) eluted from the inner surface of the tube. The amount of total organic carbon eluted from the inner surface of the tube disclosed herein into water is 1 cm2 of the inner surface area of ​​the tube. 2 The lower limit of the amount of eluted total organic carbon may be 1 ng or less, and preferably 50 ng or less, and more preferably 47 ng or less, per unit area.

[0021] The amount of eluted total organic carbon (TOC) released from the inner surface of the tube can be determined by passing ultrapure water through the tube and using a TOC meter to measure the amount of TOC eluted in the ultrapure water that has passed through the tube.

[0022] In one embodiment of the tube of the present disclosure, the amount of potassium, sodium, and iron eluted from the inner surface of the tube into the aqueous nitric acid solution is small. Air contains contaminants including potassium, sodium, and iron, and when air is introduced into the hollow portion formed when extruding the tube using an extruder, the contaminants may adhere to the inner surface of the tube. The amount of potassium, sodium, and iron eluted is a guide to determine the degree of metal contamination on the inner surface of the tube. The amount of potassium, sodium, and iron eluted from the inner surface of the tube of the present disclosure into the aqueous nitric acid solution is preferably 0.50 ng or less, more preferably 0.45 ng or less. The lower limit of the amount of potassium, sodium, and iron eluted may be 0.01 ng.

[0023] The amounts of potassium, sodium, and iron eluted from the inner surface of the tube into the nitric acid aqueous solution can be determined by pouring 15 mL of 1 N nitric acid aqueous solution into the tube, leaving it for 3 days, recovering the nitric acid aqueous solution, and measuring the potassium, sodium, and iron contents in the recovered nitric acid aqueous solution using inductively coupled plasma mass spectrometry.

[0024] In one embodiment of the tube of the present disclosure, the metal content measured by the tube ashing method is low. The metal content measured by the tube ashing method of the present disclosure 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.

[0025] The metal content measured by the ashing method in this disclosure is the total metal content of Fe, Cr, Ni, Cu, Al, Na, Mg and K. The metal content in this disclosure includes the amount of metal components present on the surface of the tube as well as the amount of metal components contained inside the tube. Even if a trace amount of metal components is contained inside the tube, there are minute voids at molecular size that allow the chemical molecules to penetrate in the vicinity of a depth of several nanometers to several microns from the chemical liquid contact surface, and metals contained inside the resin that could not be detected by a short-term metal elution amount analysis method may be eluted over a long period of time. By setting the metal content measured by the ashing method of the tube within the above range, the adverse effects caused by the elution of trace amounts of metal components contained inside the tube can be reduced.

[0026] The metal content of the tube can be measured by cutting the tube to a length of approximately 5 cm, cleaning the surface of the tube with a 1N aqueous solution of nitric acid, cutting it, and ashing the cuttings 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 cuttings prepared in the same manner as above into a platinum crucible, ashing them using a gas burner or electric furnace, dissolving the ash in acid, and then measuring the metal content using an ICP optical emission spectrometer or a frameless atomic absorption spectrophotometer.

[0027] In one embodiment of the tube of the present disclosure, 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 disclosure is preferably 5.0 nm or less, more preferably 4.0 nm or less, even more preferably 3.0 nm or less, and even more preferably 2.9 nm or less. The lower limit of the surface roughness Ra of the inner surface may be 0.1 nm. By setting 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) eluted 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 a method of appropriately selecting the type of FAVE unit in the TFE / FAVE copolymer, a method of appropriately adjusting the content of the FAVE unit, or the like.

[0028] The surface roughness Ra of the inner surface of the tube can be measured using an atomic force microscope (AFM).

[0029] Next, the copolymer that forms the tube of the present disclosure will be described.

[0030] The tubing of the present disclosure contains a tetrafluoroethylene (TFE) / fluoroalkyl vinyl ether (FAVE) copolymer. FAVE includes those having the general formula (1): CF2=CFO(CF2CFY 1 O) p -(CF2CF2CF2O) q -Rf (1) (In the formula, Y 1 represents F or CF3, and 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 general formula (2): CFX=CXOCF2OR 1 (2) (wherein X is the same or different and represents H, F or CF3; 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. 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 particularly preferred.

[0031] 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 conventional processing equipment such as an extruder and an injection molding machine. Therefore, the melt processable fluororesin usually has a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0032] The content of FAVE units in the copolymer is 3.0 to 12.0 mass% relative to the total monomer units, preferably 3.5 mass% or more, more preferably 4.0 mass% or more, even more preferably 4.5 mass% or more, preferably 10.0 mass% or less, more preferably 8.0 mass% or less, even more preferably 7.0 mass% or less, still more preferably 6.5 mass% or less, and particularly preferably 6.0 mass% or less.

[0033] The content of TFE units in the copolymer is preferably 88.0 to 97.0 mass% based on all monomer units, more preferably 90.0 mass% or more, even more preferably 92.0 mass% or more, still more preferably 93.0 mass% or more, particularly preferably 93.5 mass% or more, most preferably 94.0 mass% or more, more preferably 96.5 mass% or less, even more preferably 96.0 mass% or less, and still more preferably 95.5 mass% or less.

[0034] The copolymer may contain monomeric units derived from monomers copolymerizable with TFE and FAVE.

[0035] Monomers that can be copolymerized with TFE and FAVE include hexafluoropropylene (HFP), CZ 3 Z 4 =CZ 5 (CF2) n Z 6 (In the formula, Z 3 , Z 4 and Z 5 are the same or different and represent H or F; Z 6represents H, F or Cl, and n represents an integer of 2 to 10. 7 (In the formula, Rf 7 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) Among these, HFP is preferred.

[0036] The content of monomer units derived from monomers copolymerizable with TFE and FAVE is preferably 0 to 9.0% by mass, more preferably 7.5% by mass or less, and further preferably 1.0% by mass or less.

[0037] The copolymer 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.

[0038] The melt flow rate (MFR) of the copolymer is preferably 0.5 to 100 g / 10 min, more preferably 1 g / 10 min or more, even more preferably 2 g / 10 min or more, more preferably 50 g / 10 min or less, even more preferably 40 g / 10 min or less, and even more preferably 15 g / 10 min or less.

[0039] The 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, at a load of 5 kg and 372°C.

[0040] The melting point of the copolymer is 280 to 315°C, preferably 285°C or higher, more preferably 290°C or higher, and preferably 310°C or lower.

[0041] The melting point 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 using a differential scanning calorimeter (DSC).

[0042] The functional group of the copolymer is 10 carbon atoms. 6The number per molecule is 500 or less, preferably 300 or less, more preferably 200 or less, even more preferably 100 or less, still more preferably 50 or less, and particularly preferably 10 or less.

[0043] In order to set the number of functional groups of the copolymer within the above range, it is usually necessary to carry out a fluorination treatment, which will be described later. Although the reason is unclear, by fluorinating the copolymer, it is possible to easily 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) eluted from the inner surface of the tube are further reduced. Therefore, from the viewpoint of reducing 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, it is important to set the number of functional groups of the copolymer contained in the tube of the present disclosure within the above range.

[0044] The functional group is a functional group present at the end of the main chain or the end of the side chain of the copolymer, and a functional group present in the main chain or the side chain. The functional group is preferably at least one selected from the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH.

[0045] The type of functional group and the number of functional groups can be identified by infrared spectroscopy.

[0046] 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 prepare 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 TFE / FAVE copolymer, and a difference spectrum with a base spectrum that is completely fluorinated and has no functional groups is obtained. From the absorption peaks of specific functional groups that appear in this difference spectrum, the number of carbon atoms in the copolymer is determined according to the following formula (A): 6 Calculate the number of functional groups per unit, N. N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm)

[0047] 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.

[0048] [Table 1]

[0049] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are shown in the table. The absorption frequencies of -CF2H, -COF, -COOH free, -COOH bonded, -COOCH3, and -CONH2 are several tens of Kaiser (cm -1 ) lower. Therefore, for example, the functional group number of -COF is the absorption frequency of 1883 cm due to -CF2COF. -1 The number of functional groups determined from the absorption peak of -CH2COF and the absorption frequency of 1840 cm -1 The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of

[0050] The number of functional groups may be the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH.

[0051] The tube of the present disclosure may contain a fluororesin other than the TFE / FAVE copolymer. An example of the fluororesin other than the TFE / FAVE copolymer is polytetrafluoroethylene. 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.

[0052] The polytetrafluoroethylene may be polytetrafluoroethylene having a crystallization temperature of 305°C or higher as measured by a differential scanning calorimeter (DSC). The crystallization heat of polytetrafluoroethylene may be 50 J / g or higher. When the tube of the present disclosure contains 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 even more preferably 312°C or higher.

[0053] In one embodiment of the tube of the present disclosure, both ends are welded. By welding both ends, the cleanliness of the inner surface of the tube can be maintained.

[0054] Fig. 1 is a schematic cross-sectional view showing an embodiment of a tube 1 with both ends welded. In the tube 1 shown in Fig. 1, welded parts 4 are provided around cut surfaces 3 exposed at both ends, and a hollow part 2 of the tube 1 is sealed.

[0055] In one embodiment of the tube of the present disclosure, both ends are welded, and a 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 period of time.

[0056] The outer diameter of the tube is not particularly limited, and may be 2 to 100 mm, 3 to 100 mm, or 5 to 50 mm. The thickness of the tube may be 0.1 to 10 mm, or 0.3 to 5 mm.

[0057] The tube of the present disclosure can be suitably used as a chemical liquid piping tube for circulating chemical liquids, and can be particularly suitably used as a chemical liquid piping tube used for transporting high-purity chemical liquids for semiconductor device manufacturing.

[0058] In semiconductor factories, tubes are widely used to distribute ultrapure water and high-purity chemicals used in manufacturing semiconductor devices. The inner surface of the tubes can be contaminated by contaminants such as fine particles in the air and polymer fumes generated during melt molding of TFE / FAVE copolymers. In particular, nano-sized contaminants adhere to the inner surface of the polymer due to van der Waals forces and electrostatic forces, making them difficult to remove with cleaning water such as pure water. Therefore, when using new tubes in semiconductor factories, problems arise such as the need for a large amount of ultrapure water or chemicals to clean (flush) the inside of the tube, and the need for long cleaning times.

[0059] Since the tube of the present disclosure has the above-mentioned configuration, contaminants hardly adhere to the inner surface, and the tube is unlikely to contaminate ultrapure water or high-purity chemicals used to manufacture semiconductor devices. Since the tube of the present disclosure has such an effect, it is preferable that the tube is a tube for piping chemicals for distributing chemicals. Examples of the chemicals include chemicals used in semiconductor manufacturing, such as ammonia water, ozone water, hydrogen peroxide water, hydrochloric acid, sulfuric acid, resist liquid, thinner liquid, and developer.

[0060] The tube of the present disclosure can be used as a tube for use in semiconductor manufacturing facilities or semiconductor manufacturing equipment, such as a semiconductor manufacturing chemical supply line, a semiconductor manufacturing chemical supply equipment, a semiconductor cleaning device, and a coater developer. By using the tube of the present disclosure in semiconductor manufacturing facilities or semiconductor manufacturing equipment, a high-purity chemical can be reliably supplied to the use point. By using the tube of the present disclosure, even when manufacturing semiconductor devices with a line width of 5 nm or less, defects due to particles and metal contaminants in the semiconductor device can be reduced, and an improvement in the yield in the manufacture of semiconductor devices can be expected.

[0061] The tube of the present disclosure can be suitably manufactured by the manufacturing method of the present disclosure. Next, the manufacturing method of the tube of the present disclosure will be described.

[0062] In the manufacturing method of the present disclosure, the above-mentioned TFE / FAVE copolymer is fluorinated, and then the fluorinated copolymer is extruded using an extruder to produce a tube.

[0063] The fluorination treatment can be carried out by contacting the copolymer that has not been fluorinated with a fluorine-containing compound. By fluorinating the copolymer, it is possible 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) eluted from the inner surface of the tube are reduced. The reason for this is not clear, but it is speculated that when the copolymer is extruded after being fluorinated, the generation of volatile matter from the copolymer due to heating during extrusion is suppressed, and the number of particles and organic matter that can adhere to the inner surface of the tube is reduced, and the reduction in the number of particles and organic matter that can adhere to the inner surface of the tube is significantly improved in the discharge efficiency of the particles and organic matter by the gas flowing through the tube.

[0064] A functional group is introduced into a copolymer by, for example, a chain transfer agent or a polymerization initiator used in producing 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. Also, a functional group is introduced into the side chain end of the copolymer by polymerizing a monomer having a functional group.

[0065] By subjecting a copolymer having such functional groups to a fluorination treatment, a copolymer having the number of functional groups within the above-mentioned range can be obtained. That is, it is preferable that the TFE / FAVE copolymer is a fluorination-treated one. It is also preferable that the TFE / FAVE copolymer has a -CF3 end group.

[0066] The fluorine-containing compound is not particularly limited, but may be a fluorine radical source that generates fluorine radicals under fluorination treatment conditions, such as F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, halogen fluorides (e.g., IF5, ClF3), etc.

[0067] The fluorine radical source such as F2 gas may be of 100% concentration, but from the viewpoint of safety, it is preferable to mix it with an inert gas and dilute it to 5 to 50 mass%, more preferably to dilute it to 15 to 30 mass%. Examples of the inert gas include nitrogen gas, helium gas, argon gas, etc., and nitrogen gas is preferable from the viewpoint of economy.

[0068] The conditions for the fluorination treatment are not particularly limited, and the copolymer in a molten state may be contacted with a fluorine-containing compound, but the fluorination treatment is usually carried out at a temperature below the melting point of the copolymer, preferably 20 to 220°C, more preferably 100 to 200°C. The fluorination treatment is generally carried out for 1 to 30 hours, preferably 5 to 25 hours. The fluorination treatment is preferably carried out by contacting a non-fluorinated copolymer with fluorine gas (F2 gas).

[0069] The TFE / FAVE copolymer can be produced by a conventional method such as emulsion polymerization or suspension polymerization by appropriately mixing monomers that form the constituent units thereof and additives such as a polymerization initiator.

[0070] In each step of the manufacturing method for producing a copolymer, such as the polymerization step, granulation step, washing step, drying step, transport step, storage step, pelletization step, fluorination step, and product filling step, it is preferable to prevent the materials and copolymer used in the manufacturing from contacting the metal surfaces of each facility and piping as much as possible, to use materials with low metal content as the materials used in the manufacturing, and to use clean and dry air as the air used to dry the obtained copolymer and the air used to transport the copolymer between each facility, thereby manufacturing a TFE / FAVE copolymer. By using such a manufacturing method, a copolymer with a low metal content measured by the ashing method can be manufactured. And, by using such a copolymer, a tube with a low metal content measured by the ashing method can be obtained.

[0071] In the manufacturing method of the present disclosure, when the copolymer is extruded, the gas that has passed through the organic matter removal filter and then the particulate removal filter is passed through the tip of the tube into the tube. By passing the gas through the tip of the tube into the tube in this way, the contaminants contained in the hollow part of the tube can be discharged from the hollow part. In addition, since organic matter and particulates have been removed from the gas supplied into the tube, the organic matter and particulates do not adhere to the inner surface of the tube by passing the gas through the tube. Furthermore, since the gas supplied from the tip of the tube is discharged to the outside through the die of the extruder, metal components generated from the die do not adhere to the inner surface of the tube. Therefore, by using the manufacturing method of the present disclosure, 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 reduced. Furthermore, by using the manufacturing method of the present disclosure, a tube can be manufactured in which the amount of potassium, sodium, and iron eluted is small. In addition, a tube with a low 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.

[0072] As the organic matter filtration filter, a chemical adsorption type filter utilizing hydrogen bonds or acid-base bonds, a physical adsorption type filter utilizing van der Waals forces, etc. can be used. As the organic matter filtration filter, a physical adsorption type filter is particularly preferable. By using a physical adsorption type filter, organic matter such as plasticizers and oil mist present in the gas can be removed with high efficiency.

[0073] As the organic filter, one or more types of filters can be used. A plurality of organic filters may be connected in series or in parallel.

[0074] The organic matter filter may be a filter in which a column is filled with an adsorbent, such as activated carbon, silica gel, or zeolite.

[0075] The adsorbent is preferably activated carbon. The activated carbon may be granular activated carbon or fibrous activated carbon. The activated carbon is preferably activated carbon with a low content of metal components. Examples of the activated carbon include activated carbon made from coconut shell, coal, charcoal, etc., and activated carbon derived from plants is preferable.

[0076] The specific surface area of ​​the activated carbon measured by the BET method is preferably as large as possible, and is preferably 400 m 2 / g or more, and more preferably 1000m 2 / g or more.

[0077] In the manufacturing method of the present disclosure, the gas is passed through an organic matter removal filter, then through a particulate removal filter, and then supplied into the tube. By supplying the gas in this manner, even if particulates generated from the organic matter removal filter are mixed into the gas, the particulates are captured by the particulate removal filter, so that the particulates can be prevented from entering the tube. On the other hand, if the gas is passed through a particulate removal filter, then through an organic matter removal filter, and then supplied into the tube, the introduction of the particulates into the tube cannot be prevented, and the particulates may adhere to the inner surface of the tube.

[0078] 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.

[0079] The collection efficiency of the particulate removal filter is not particularly limited. As the particulate removal filter, a filter that collects 99.99% or more of particles of 30 nm or more is preferable, a filter that collects 99.99% or more of particles of 10 nm or more is more preferable, a filter that collects 99.99% or more of particles of 5 nm or more is even more preferable, and a filter that collects 99.99% or more of particles of 3 nm or more is particularly preferable.

[0080] As the particulate removal filter, one or more types of filters can be used. In addition, a plurality of particulate removal filters may be connected in series or in parallel.

[0081] Next, the manufacturing method of the present disclosure will be described in more detail with reference to the drawings.

[0082] FIG. 2 is a schematic side view of the tube manufacturing apparatus, and FIG. 3 is a schematic front view of the winding apparatus.

[0083] The tube manufacturing apparatus 100 shown in FIG. 2 includes an extrusion molding machine 10 that melts a copolymer and extrudes it into a tube, a sizing 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 take-up machine 60 that takes up the cooled tube, a winding device 70 that winds up the tube sent out from the take-up machine, and a gas supplying device 80 that supplies gas to the winding device 70.

[0084] In the tube manufacturing apparatus 100, the copolymer fed from the hopper 11 of the extrusion molding machine 10 is melted in the cylinder of the extrusion molding machine 10, and the molten copolymer is extruded into a tube shape from the die 20 by rotating the screw. The molten copolymer extruded into a tube shape passes through the sizing die 40, and its outer shape is determined. The copolymer that has passed through the sizing die 40 is cooled in a cooling water tank 50, and then passes through a take-up machine 60 that takes up a tube of the cooled copolymer, and is wound by a winding device 70 onto a take-up reel 75 provided in the winding device. The take-up speed (line speed) at this time is generally 30 to 150 cm / min, and may be 30 to 120 cm / min.

[0085] In one embodiment of the manufacturing method of the present disclosure, the copolymer is melted and extruded into a tube shape from a die provided in an extrusion molding machine, the copolymer extruded into a tube shape from the die provided in the extrusion molding machine is introduced into a cooling device to be cooled, and then the cooled tube is wound up on a take-up reel using a winding device to manufacture a tube. Furthermore, gas is supplied to the hollow part of the tube from the tip of the tube wound up on the take-up reel, and the gas in the hollow part is discharged to the outside through a gas exhaust hole provided in the die from a gas inlet provided in the die. In this way, by supplying gas from the tip of the tube toward the die of the extrusion molding machine, 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 reduced.

[0086] In one embodiment of the manufacturing method of the present disclosure, gas is supplied into the tube at a pressure that can suppress adhesion of contaminants to the inner surface of the tube while suppressing deformation of the tube. The internal pressure (gauge pressure) in the tube is higher than atmospheric pressure and is 0.5 kgf / cm 2 The internal pressure (gauge pressure) in the tube is preferably 0.4 kgf / cm 2 More preferably, it is 0.3 kgf / cm or less. 2 less than or equal to 0.1 kgf / cm 2 More preferably, it is 0.2 kgf / cm 2 That's all.

[0087] The extruder shown in Fig. 2 is equipped with a die 20, and a molten copolymer is extruded from an extrusion port provided in the die 20. The temperature of the copolymer extruded from the die of the extruder is preferably 390°C or lower, more preferably 385°C or lower, even more preferably 380°C or lower, still more preferably 375°C or lower, particularly preferably 370°C or lower, and most preferably 365°C or lower, and is preferably equal to or higher than the melting point of the copolymer, more preferably 330°C or higher, and even more preferably 350°C or higher.

[0088] The temperature of the copolymer extruded from the die of the extruder can be specified by measuring the temperature of the copolymer at the extrusion port of the die with a thermocouple. By lowering the temperature of the copolymer extruded from the die, it is possible to further reduce 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.

[0089] The extruder 10 further includes a backflow prevention device 30, which is connected to a gas exhaust hole of the die 20 and exhausts gas to the outside of the extruder 10 while preventing the backflow of gas. By preventing the backflow of gas, air does not flow into the tube obtained by extrusion from the extruder 10, so that even after the supply of gas from the tip of the tube is stopped, pollutants in the air do not adhere to the inner surface of the tube, and the inner surface remains clean.

[0090] The tube manufacturing apparatus 100 includes a winding device 70. Fig. 3 is a diagram showing an embodiment of the winding device 70. The winding device 70 shown in Fig. 3 is a winding device that winds up the tube 1, and includes a gas supply port 72 that supplies gas to the hollow portion of the tube 1, a filter 73 that is provided downstream of the gas supply port 72 and removes contaminants in the gas supplied from the gas supply port 72, a tube connection port 74 that is provided downstream of the filter 73 and connects the tube 1, and a winding reel 75 around which the tube is wound.

[0091] The take-up reel 75 is rotatably supported (axially supported) on a rotating shaft 77 provided on a support stand pillar 76, and when a drive unit 78 is driven, the take-up reel 75 rotates together with the rotating shaft 77 to take up the tube 1. One end of the tube 1 is connected to a tube connection port 74 via a lead tube 71. Gas is supplied from the tube connection port 74 to the hollow portion of the tube 1. The tube 1 is taken up by the take-up reel 75 while gas is circulating through the hollow portion.

[0092] The gas supply port 72 is connected to a gas supply device 80. The gas supply device 80 may be a gas cylinder filled with high-pressure gas as shown in Fig. 2, or may be a compressor, a blower, or the like. The gas supply device 80 may be provided with a needle valve (not shown) to adjust the gas supply pressure.

[0093] The tube connection port 74 is connected to the gas supply port 72 via a filter 73. By supplying gas that has passed through the filter 73 to the hollow part of the tube 1, a tube having a clean inner surface can be manufactured.

[0094] 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 gas, argon gas, or helium gas, air, oxygen gas, or a halogen gas, etc. From the viewpoint of reducing costs, air is preferable.

[0095] In Fig. 3, an organic matter removal filter 73a and a particulate removal filter 73b are connected in series. In Fig. 3, one organic matter removal filter and one particulate removal filter are provided, but multiple filters may be provided. For example, multiple particulate removal filters can be provided so that gas that has passed through the organic matter removal filter passes through multiple particulate removal filters with different particulate filtering accuracies.

[0096] The winding device 70 further includes a lead tube 71 having one end connected to a tube connection port 74 and the other end connected to the tube 1. Gas is supplied to the hollow portion of the lead tube 71 from the tube connection port 74, and gas is also supplied to the hollow portion of the tube 1 connected to the lead tube 71.

[0097] In the winding device 70 shown in FIG. 3, one end of the lead tube 71 is connected to the tube 1, but before extrusion molding of the copolymer is started, the one end of the lead tube 71 is not connected to the tube 1. Gas is supplied to the lead tube 71, and while the gas is flowing out from the tip of the lead tube 71, the tip of the lead tube 71 is connected to the tip of the copolymer extruded from the die 20, and the gas is supplied to the hollow part of the molten tube 1. After the tip of the lead tube 71 is connected to the tip of the copolymer extruded from the die 20, continuous extrusion of the copolymer from the die 20 and winding of the lead tube 71 and the cooled tube 1 are started. In this way, the tube can be manufactured while maintaining a clean inner surface.

[0098] When a tube of the desired length is produced, extrusion of the copolymer and winding of the tube are stopped. After stopping extrusion of the copolymer, any two points of the tube are welded and cut to produce a tube with both ends sealed and a filtered gas sealed in the hollow portion. The inner surface of the tube obtained by this production method has never come into contact with the air and is extremely clean.

[0099] The tube welding location is not particularly limited, but for example, by welding one location of the tube between the mold 20 and the sizing die 40 and welding one location of the tube near where it is connected to the lead tube 71, the tube can be manufactured without waste. If the tube at the location to be welded is in a molten state, it can be welded by holding it with tweezers or the like. If the tube at the location to be welded has cooled and solidified, it can be heated with a heat gun or the like to partially melt the welding location, and then it can be welded by holding it with tweezers or the like.

[0100] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.

[0101] <1> According to a first aspect of the present disclosure, A tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, The number of functional groups of the copolymer is 10 6 Each piece is 500 or less. The melting point of the copolymer is 280 to 315°C; The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0 to 12.0 mass% based on the total monomer units; The melt flow rate of the copolymer is 1 to 15 g / 10 min; The number of particles released from the inner surface of the tube is determined based on the surface area of ​​the tube (cm2). 2 3,500 or less per The amount of total organic carbon dissolved into water from the inner surface of the tube is 2 per unit, is less than 50 ng. A tube is provided. <2> According to a second aspect of the present disclosure, In the tube according to the first aspect, there is provided a copolymer having a fluoroalkyl vinyl ether unit content of 3.5 to 8.0% by mass based on the total monomer units. <3> According to a third aspect of the present disclosure, The number of functional groups of the copolymer is 10 6 There is provided a tube according to the first or second aspect, the tubes each having 100 or less. <4> According to a fourth aspect of the present disclosure, The amount of potassium, sodium and iron dissolved from the inner surface of the tube into the nitric acid solution is determined based on the surface area of ​​the tube (cm2). 2 The tube according to any one of the first to third aspects is provided, in which the concentration is 0.50 ng or less per unit time. <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 as measured by an ashing method is 40 ng / 1 g or less. <6> According to a sixth aspect of the present disclosure, According to any one of the first to fifth aspects, there is provided a tube, wherein the surface roughness Ra of the inner surface of the tube is 5.0 nm or less. <7> According to a seventh aspect of the present disclosure, According to any one of the first to sixth aspects, there is provided a tube, both ends of which are welded. <8> According to an eighth aspect of the present disclosure, A method for producing a tube, comprising fluorinating a copolymer and then extruding the fluorination-treated copolymer using an extruder, comprising the steps of: the copolymer is a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, The melting point of the copolymer is 280 to 315°C; The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0 to 12.0 mass% based on the total monomer units; The melt flow rate of the copolymer is 1 to 15 g / 10 min; the temperature of the copolymer extruded from the die of the extruder is 390° C. or less; During extrusion molding, the gas is passed through an organic matter removal filter and then through a particulate removal filter, and the gas is passed through the tube from the tip of the tube into the tube. A method of manufacture is provided. <9> According to a ninth aspect of the present disclosure, The organic matter removal filter has a specific surface area of ​​400 m2 as measured by the BET method. 2 According to an eighth aspect, there is provided a production method using a column packed with activated carbon having a mercury content of 100% by mass or more. <10> According to a tenth aspect of the present disclosure, According to an eighth or ninth aspect, there is provided a method for producing the particulate removal filter, wherein the particulate filtration accuracy of the particulate removal filter is 10 nm or less. EXAMPLES

[0102] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0103] The values ​​in the examples were measured by the following methods.

[0104] (composition) 19 The measurements were performed using F-NMR.

[0105] (Melt Flow Rate (MFR)) According to ASTM D1238, the mass (g / 10 min) of the copolymer flowing out from a nozzle with an inner diameter of 2.1 mm and a length of 8 mm per 10 min was measured at 372°C under a load of 5 kg using a melt indexer (manufactured by Yasuda Seiki Seisakusho).

[0106] (Melting Point) It was determined by using a differential scanning calorimeter (DSC) as the temperature corresponding to the maximum value on the heat of fusion curve when the temperature was raised at a rate of 10°C / min.

[0107] (Number of functional groups) The copolymer was melted at 340-350°C for 30 minutes and compression molded to prepare a film with a thickness of 0.05-0.25 mm. This film was scanned 40 times using a Fourier transform infrared spectrometer [FT-IR (Spectrum One, PerkinElmer)] to analyze it and obtain an infrared absorption spectrum, and a difference spectrum with a base spectrum where the material is completely fluorinated and has no functional groups was obtained. From the absorption peaks of specific functional groups that appear in this difference spectrum, the amount of carbon atoms in the sample per 1×10 6 The number of functional groups per unit, N, was calculated. N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm) For reference, the absorption frequencies, molar extinction coefficients, and correction coefficients for the functional groups in this disclosure are shown in Table 2. The molar extinction coefficients were determined from FT-IR measurement data of low molecular weight model compounds.

[0108] [Table 2]

[0109] (Number of particles) In a class 100 clean booth, the tubes produced in the examples and comparative examples were cut to 0.5 m to produce tube A.

[0110] For the measurement, the system 9 shown in Fig. 4 and commercially available high-purity isopropyl alcohol (IPA) were used. An in-line filter (NHM series, filtration accuracy 3 nm) manufactured by Kitz Microfilter was used as the filter 94. A light scattering type liquid-borne particle detector KS-19F manufactured by Rion was used as the particle counter.

[0111] It was confirmed in advance using a particle counter that the number of particles with a diameter of 30 nm or more discharged into IPA from the measurement line was 10 particles / mL or less.

[0112] 4, the tube A was connected to the joints 95 and 96 of the system 9, and then IPA was made to flow into 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.

[0113] Next, the pump 92 was stopped, and tube A was left standing for 6 hours in a state where the tube A was filled with IPA.

[0114] The supply of IPA into tube A was resumed, and IPA was allowed to flow into tube A at a flow rate of 110 mL / min. A portion of the IPA that had passed through tube A was introduced into a light scattering type liquid-borne particle detector (particle counter) at a flow rate of 10 mL / min, and the number of particles in the IPA was measured. The number of particles dropped to the blank level in about 10 minutes, but measurements were continued for 16 minutes. The interval between measurements was set to 2 seconds, and the number of particles was measured 15 times in total. Each of the 15 measured values ​​(particles / mL) was multiplied by 110 and integrated, and the integrated value was divided by the surface area of ​​the inner surface of tube A to determine the number of particles (particles / cm) released into the IPA from tube A. 2 ) was calculated.

[0115] (TOC elution amount) A filter (Kitz Microfilter's Polyfix F50 series (F50 C50TP-C2) with a particle filtration accuracy of 5 nm), a flow meter (Surpass's differential pressure flow controller (Z900M-1 / 4-09-AN531S)), and a TOC meter (T&C Technical's TAC-ACCURA-R, ultraviolet oxidative decomposition conductivity type) were each connected with piping to create a measurement line for measuring the amount of TOC elution.

[0116] The flow rate of ultrapure water flowing through the flowmeter was set to 110 mL / min, and the flow rate of ultrapure water flowing through the TOC measurement cell of the TOC meter was set to 20 mL / min. The remaining ultrapure water that was not introduced into the TOC meter was drained through a separate pipe. Ultrapure water was allowed to flow for one hour, and it was confirmed that the TOC value was 1 ppb or less.

[0117] The tubes produced in the examples and comparative examples were cut to a length of 1 m and placed between the filter and the flow meter of the measurement line.

[0118] The TOC value was measured continuously at 5-second intervals, and the amount of TOC eluted (ng) was calculated from the peak area for 5 minutes after the peak was detected. The calculated value was multiplied by 110 / 20 and then multiplied by the inner surface area of ​​the tube (124 cm 2 ) to obtain the amount of TOC eluted (ng / cm 2 ) was sought.

[0119] (Potassium, sodium and iron elution amount) The tubes produced in the examples and comparative examples were cut to a length of 150 cm, then bent into a U-shape and fixed with a cable tie. 15 mL of a high-purity 1N aqueous nitric acid solution was poured into the tube and left for 3 days, after which the amount of metal in the aqueous nitric acid solution was measured using an inductively coupled plasma mass spectrometer. The amount of eluted metal (ng) was calculated by multiplying the measured value (ng / mL) by the amount of nitric acid used, and the calculated value was divided by the contact area between the inner surface of the tube and nitric acid to determine the amount of eluted potassium, sodium and iron (ng / cm2 ) was sought.

[0120] (Metal content measured by incineration method) The ashing method described in International Publication No. 94 / 28394 was used. The tubes produced in the examples and comparative examples were cut to lengths of about 5 cm, washed with a high-purity 1N aqueous solution of nitric acid, cut, and the cut pieces were precisely weighed in the range of 2 to 6 mg, and heated at 1100°C for 180 seconds in a graphite cuvette to be ashed, and analyzed with an atomic absorption spectrophotometer (polarized Zeeman atomic absorption spectrophotometer (Z-8100), manufactured by Hitachi, Ltd.).

[0121] (Tube inner surface roughness Ra) An atomic force microscope (AFM) topography image of the inner surface of the tubes produced in the examples and comparative examples was subjected to automatic tilt correction processing to calculate the surface roughness Ra of the inner surface of the tube. Surface roughness Ra is the average value (arithmetic mean roughness) obtained by extracting only a reference length L from the roughness curve in the direction of the average line, and adding up the absolute values ​​of the deviations from the average line of this extracted portion to the measurement curve. When the x-axis is taken in the direction of the average line of the extracted portion and the y-axis is taken in the direction of the longitudinal magnification, and the roughness curve is expressed as y=f(x), the calculation formula for surface roughness Ra is as follows:

number

[0122] Example 1 Except for changing the amounts of monomers used, etc., pellets of a 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 WO 2019 / 187859.

[0123] The obtained pellets were heated to 200°C and contacted with a mixed gas containing nitrogen gas and fluorine gas (fluorine gas concentration = 30 volume %). The total number of -CF = CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH in the copolymer in the obtained pellets was 10 carbon atoms. 6 There were five or fewer per piece.

[0124] Using the obtained pellets and the tube manufacturing apparatus shown in FIG. 2, a 1 / 4 inch tube with an outer diameter of 6.35 mm and an inner diameter of 3.95 mm was manufactured. Using an extruder (cylinder shaft diameter 30 mm, L / D=22), extrusion molding was performed at a take-up speed of 0.4 m / min. The screw rotation speed of the extruder was set to 4.2 rpm and the take-up speed was set to 41 cm / min to adjust the tube thickness. The temperatures of the cylinders (C1, C2, C3), adapter (A), die head (D1) and die tip (D2) of the extruder were set to 330 to 360°C. The temperature of the copolymer at the tip of the die (temperature of the copolymer at the die outlet) was 360°C.

[0125] Organic matter removal filter (specific surface area is approximately 1200 (m 2 An in-line filter filled with activated carbon (1000 sq. m. / g) and a particulate removal filter (Kitz Microfilter in-line filter (NHM series, particulate filtration accuracy 3 nm)) were connected in series. Air was passed through the organic matter removal filter and then the particulate removal filter, and then air was supplied into the tube from the tip of the tube.

[0126] The air flow rate was adjusted using a needle valve, and air was continuously supplied at a flow rate such that the pressure inside the tube was higher than atmospheric pressure and the molten copolymer extruded from the die of the extruder was not deformed. Two arbitrary points of the obtained tube were welded using a hand sealer with a hot plate manufactured by Eiko Denki Co., Ltd. to obtain a tube with both ends sealed. The results are shown in Table 3.

[0127] Example 2 A tube with both ends sealed was obtained in the same manner as in Example 1, except that the temperatures of the cylinder, adapter, die head, and die tip of the extruder were changed so that the temperature of the copolymer at the die outlet was 380° C. The results are shown in Table 3.

[0128] Comparative Examples 1 to 6 A tube with both ends sealed was obtained in the same manner as in Example 1, except that the production conditions for the tube were changed as shown in Table 3. The results are shown in Table 3.

[0129] The direction in which air is supplied from the tip of the tube toward the mold, as was done in Example 1, is described as "reverse flow" in Table 3. The direction in which air is supplied from the mold toward the tip of the tube (the opposite direction to the supply direction in Example 1) is described as "forward flow" in Table 3. Even when air was supplied from the mold toward the tip of the tube, the air was passed through an organic matter removal filter and then a particulate removal filter before being supplied into the tube.

[0130] [Table 3] [Explanation of symbols]

[0131] 1 tube 2 Hollow part 100 Tube manufacturing equipment 10 Extrusion molding machine 20 Mold 30 Backflow prevention device 40 Sizing Die 50 Cooling device (cooling water tank) 60 Pick-up Machine 70 Winding device 71 Lead tube 73a Organic matter removal filter 73b Particulate removal filter 80 Gas supply equipment 9. System 91 Solvent Container 92 Pump 93 Valve 94 Filters 95, 96 Joints 97 Particle Counter 98, 99 flowmeter

Claims

1. A tube containing a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, The copolymer has a functional group of 10 carbon atoms. ６ Each piece is 500 or less, The melting point of the copolymer is 280 to 315°C, The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0 to 12.0 mass% based on the total monomer units, The melt flow rate of the copolymer is 1 to 15 g / 10 min; The number of particles released from the inner surface of the tube is determined based on the surface area of ​​the tube (cm2). ２ 2,500 or less per The amount of total organic carbon dissolved into water from the inner surface of the tube is ２ per unit, it is 50ng or less. tube.

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

3. The copolymer has a functional group of 10 carbon atoms. ６ 3. The tube according to claim 1 or 2, wherein each tube contains 100 or less particles.

4. The amount of potassium, sodium and iron eluted from the inner surface of the tube into the nitric acid solution is determined based on the surface area of ​​the tube. ２ 3. The tube according to claim 1 or 2, wherein the concentration is 0.50 ng or less per unit time.

5. 3. The tube according to claim 1, wherein the metal content of the tube as measured by an ashing method is 40 ng / 1 g or less.

6. 3. The tube according to claim 1, wherein the inner surface of the tube has a surface roughness Ra of 5.0 nm or less.

7. 3. The tube according to claim 1, wherein both ends are welded.

8. A method for producing a tube, comprising fluorinating a copolymer and then extruding the fluorination-treated copolymer using an extruder, comprising the steps of: the copolymer is a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, The melting point of the copolymer is 280 to 315°C, The content of the fluoroalkyl vinyl ether unit in the copolymer is 3.0 to 12.0 mass% based on the total monomer units, The melt flow rate of the copolymer is 1 to 15 g / 10 min; the temperature of the copolymer extruded from the die of the extruder is 365° C. or less; During extrusion molding, the gas is passed through an organic matter removal filter and then through a particulate removal filter, and the gas is passed through the tube from the tip of the tube into the tube. Manufacturing method.

9. The organic matter removal filter has a specific surface area of ​​400 m2 as measured by the BET method. ２ 9. The method according to claim 8, wherein a column is packed with activated carbon having a molecular weight of at least 10000 / g.

10. The 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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