Fluorine-containing copolymer

Abstract

Provided is a fluorine-containing copolymer which is a fluorine-containing copolymer containing tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein the content of the hexafluoropropylene units is 7.0 to 12.0 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5 to 2.9 mass% relative to the total monomer units, and the melt flow rate at 372°C is 40 to 60 g / 10 minutes.

Description

TECHNICAL FIELD

[0001] The present application relates to a fluorine-containing copolymer. BACKGROUND

[0002] In Patent Literature 1, as a fluorine-containing copolymer, a fluorine-containing copolymer containing a polymerization unit derived from tetrafluoroethylene, a polymerization unit derived from hexafluoropropylene, and a polymerization unit derived from perfluoro(alkyl vinyl ether) is disclosed, which has a melt flow rate measured at 372°C, a swell, and a total number of -CF2H groups and unstable terminal groups in a prescribed range.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent No. 6134818 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] An object of the present application is to provide a fluorine-containing copolymer which can be molded at a very high injection speed by an injection molding method to obtain a thin-walled and beautiful molded product, which can easily form an extremely thin and less-defective coating layer on a core wire having a very small diameter by an extrusion molding method, which is less likely to be cracked even in the case of contact with a medicine, and which can obtain a molded body excellent in 65°C wear resistance, 140°C tensile creep resistance, and durability to repeated load.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] According to the present application, there is provided a fluorine-containing copolymer which is a fluorine-containing copolymer containing a tetrafluoroethylene unit, a hexafluoropropylene unit, and a perfluoro(propyl vinyl ether) unit, wherein the content of the hexafluoropropylene unit is 7.0 mass% to 12.0 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) unit is 1.5 mass% to 2.9 mass% relative to the total monomer units, and the melt flow rate at 372°C is 40 g / 10 minutes to 60 g / 10 minutes.

[0010] The content of the hexafluoropropylene unit relative to the total monomer units is preferably 7.7 mass% to 11.5 mass%.

[0011] The content of the perfluoro(propyl vinyl ether) unit relative to the total monomer units is preferably 1.7 mass% to 2.4 mass%.

[0012] The melt flow rate at 372°C is preferably 46 g / 10 minutes to 60 g / 10 minutes.

[0013] The number of functional groups per 10 6The number of main chain carbon atoms is preferably 90 or less.

[0014] Further, according to the present application, there is provided an injection-molded body containing the above-mentioned fluorine-containing copolymer.

[0015] Further, according to the present application, there is provided a coated electric wire having a coating layer containing the above-mentioned fluorine-containing copolymer.

[0016] Further, according to the present application, there is provided a molded body which is a molded body containing the above-mentioned fluorine-containing copolymer, wherein the molded body is a coated electric wire.

[0017] Effects of the Invention

[0018] According to the present application, it is possible to provide a fluorine-containing copolymer which can be molded at a very high injection speed by an injection molding method to obtain a thin-walled and beautiful molded product, can easily form a very thin, defect-free coating layer on a very small-diameter core wire by an extrusion molding method, is less likely to be cracked even in the case of contact with a medicine, and can obtain a molded body which is excellent in 65°C wear resistance, 140°C tensile creep resistance, and durability to repeated load. DETAILED DESCRIPTION

[0019] Hereinafter, a specific embodiment of the present application will be described in detail, but the present application is not limited to the following embodiment.

[0020] The fluorine-containing copolymer of the present application contains tetrafluoroethylene (TFE) units, hexafluoropropylene (HFP) units, and perfluoro(propyl vinyl ether) (PPVE) units.

[0021] In Patent Literature 1, it is described that, in a fluorine-containing copolymer having the above-mentioned units, the melt flow rate measured at 372°C, the expansion, and the total number of -CF2H groups and unstable terminal groups are within a prescribed range.

[0022] However, there is a demand for a fluorine-containing copolymer which can form a coating layer in which defect generation is sufficiently suppressed even in the case where a very small-diameter core wire is used and the coating layer is made very thin.

[0023] It was found that, by adjusting the contents of HFP units and PPVE units and the melt flow rate of a fluorine-containing copolymer containing TFE units, HFP units, and PPVE units to extremely limited ranges, according to such a fluorine-containing copolymer, a very thin, defect-free coating layer can be easily formed on a very small-diameter core wire by an extrusion molding method. It was further found that, by using such a copolymer, a molded body which is less likely to be cracked even in the case of contact with a medicine, is excellent in 65°C wear resistance, 140°C tensile creep resistance, and durability to repeated load can be obtained.

[0024] The fluorine-containing copolymer of the present application is a melt-processable fluororesin. Melt-processability means that the polymer can be melted and processed using existing processing equipment such as extruders and injection molding machines.

[0025] The content of the HFP unit of the fluorine-containing copolymer is 7.0 to 12.0 mass% with respect to the total monomer units, preferably 7.3 mass% or more, more preferably 7.4 mass% or more, further preferably 7.5 mass% or more, particularly preferably 7.7 mass% or more, most preferably 8.2 mass% or more, preferably 11.7 mass% or less, more preferably 11.5 mass% or less, further preferably 11.0 mass% or less, more further preferably 10.8 mass% or less, particularly preferably 10.5 mass% or less, especially preferably 10.2 mass% or less, more especially preferably 9.8 mass% or less, and most especially preferably 9.5 mass% or less, 9.0 mass% or less. By having the content of the HFP unit of the fluorine-containing copolymer within the above range, an extremely thin, defect-free coating layer can be easily formed on a core wire having an extremely small diameter by an extrusion molding method, cracking is less likely to occur even when in contact with a medicine, and a molded body having excellent 65°C wear resistance, 140°C tensile creep resistance, and durability to repeated load can be obtained. If the content of the HFP unit is too small, a molded body having excellent 65°C wear resistance cannot be obtained, and the occurrence of cracking when the molded body is in contact with a medicine cannot be sufficiently suppressed. If the content of the HFP unit is too large, a molded body having excellent 140°C tensile creep resistance and durability to repeated load cannot be obtained.

[0026] The content of the PPVE unit of the fluorine-containing copolymer is preferably 1.5 to 2.9% by mass, more preferably 1.6% by mass or more, further preferably 1.7% by mass or more, particularly preferably 1.8% by mass or more, most preferably 1.9% by mass or more, relative to the total monomer units, and is preferably 2.8% by mass or less, more preferably 2.7% by mass or less, further preferably 2.6% by mass or less, more further preferably 2.5% by mass, particularly preferably 2.4% by mass or less, most preferably 2.2% by mass or less. By setting the content of the PPVE unit of the fluorine-containing copolymer within the above range, an extremely thin coating layer with few defects can be easily formed on a core wire with an extremely small diameter by an extrusion molding method, cracking is less likely to occur even when the coating layer is in contact with a medicament, and a molded body excellent in 65°C wear resistance, 140°C tensile creep resistance, and durability to repeated load can be obtained. If the content of the PPVE unit is too small, the formation of an extremely thin coating layer on a core wire with an extremely small diameter by an extrusion molding method cannot sufficiently suppress the occurrence of defects in the coating layer, and furthermore, a molded body excellent in 65°C wear resistance cannot be obtained, and the occurrence of cracking when the molded body is in contact with a medicament cannot be sufficiently suppressed. If the content of the PPVE unit is too large, a molded body excellent in 140°C tensile creep resistance cannot be obtained.

[0027] The content of the TFE unit of the fluorine-containing copolymer is preferably 85.1 to 91.5% by mass, more preferably 85.6% by mass or more, further preferably 86.1% by mass or more, particularly preferably 86.4% by mass or more, most preferably 86.6% by mass or more, relative to the total monomer units, and is more preferably 91.2% by mass or less, further preferably 90.8% by mass or less, particularly preferably 90.6% by mass or less, most preferably 89.9% by mass or less. Note that the content of the TFE unit can be selected so that the total of the contents of the HFP unit, the PPVE unit, the TFE unit, and the content of other monomer units is 100% by mass.

[0028] The fluorine-containing copolymer of the present application can be a copolymer containing only the above three kinds of monomer units, or a copolymer containing the above three kinds of monomer units and other monomer units.

[0029] The other monomer is not particularly limited as long as it is a monomer copolymerizable with TFE, HFP, and PPVE, and can be a fluorine-containing monomer or a non-fluorine-containing monomer.

[0030] The fluorine-containing monomer is preferably a monomer selected from the group consisting of chlorotrifluoroethylene, fluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoroisobutene, CH2=CZ 1 (CF2) n Z 2 (in the formula, Z 1For H or F, Z 2 The monomer shown is represented by H, F, or Cl, where n is an integer from 1 to 10, CF2 = CF - ORf 1 (where Rf) 1 Perfluoro(alkyl vinyl ether) [PAVE] (except for PPVE) represented by perfluoroalkyl groups having 1 to 8 carbon atoms, CF2=CF-O-CH2-Rf 2 (where Rf) 2 It is at least one of the following groups: alkyl perfluorovinyl ether derivatives (represented by a perfluoroalkyl group having 1 to 5 carbon atoms), perfluoro-2,2-dimethyl-1,3-dioxacyclopentene [PDD], and perfluoro-2-methylene-4-methyl-1,3-dioxacyclopentane [PMD].

[0031] As CH2=CZ 1 (CF2) n Z 2 Examples of the monomers shown include CH2=CFCF3, CH2=CH-C4F9, and CH2=CH-C6F. 13 CH2=CF-C3F6H, etc.

[0032] As CF2 = CF - ORf 1 Examples of perfluorinated (alkyl vinyl ethers) include CF2=CF-OCF3 and CF2=CF-OCF2CF3.

[0033] Examples of non-fluorinated monomers include hydrocarbon monomers capable of copolymerizing with TFE, HFP, and PPVE. Examples of hydrocarbon monomers include: olefins such as ethylene, propylene, butene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl pentanoate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl tert-carbonate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, p-tert-butylbenzoate, vinyl cyclohexanecarboxylate, and vinyl monochloroacetate. Vinyl esters such as vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecenoate, vinyl glycolate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, and vinyl hydroxycyclohexanecarboxylate; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether; and alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, and cyclohexyl allyl ester.

[0034] As non-fluorinated monomers, they can also be hydrocarbon monomers containing functional groups capable of copolymerizing with TFE, HFP, and PPVE. Examples of hydrocarbon monomers containing functional groups include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; non-fluorinated monomers with glycidyl groups such as glycidyl vinyl ether and glycidyl allyl ether; non-fluorinated monomers with amino groups such as aminoalkyl vinyl ether and aminoalkyl allyl ether; non-fluorinated monomers with amide groups such as (meth)acrylamide and hydroxymethylacrylamide; bromine-containing alkenes, iodine-containing alkenes, bromine-containing vinyl ethers, and iodine-containing vinyl ethers; and non-fluorinated monomers with nitrile groups.

[0035] The content of other monomer units in the fluorinated copolymer of the present invention is preferably 0 to 6.4% by mass relative to all monomer units, more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

[0036] The melt flow rate (MFR) of the fluorinated copolymer is 40 g / 10 min to 60 g / 10 min, preferably 40.1 g / 10 min or more, more preferably 41 g / 10 min or more, further preferably 43 g / 10 min or more, even more preferably 45 g / 10 min or more, particularly preferably 46 g / 10 min or more, especially preferably 48 g / 10 min or more, most preferably 50 g / 10 min or more, preferably 57 g / 10 min or less, and more preferably 55 g / 10 min or less. If the melt flow rate of the fluorinated copolymer is too high, burrs will be generated in the molded article when it is molded at an extremely high injection speed by injection molding, and the generation of cracks when the molded article comes into contact with the agent cannot be sufficiently suppressed. In addition, if the melt flow rate of the fluorinated copolymer is too high, it is impossible to obtain a molded article with excellent abrasion resistance at 65°C. If the melt flow rate of the fluorinated copolymer is too low, the extrusion pressure will be high, resulting in poor moldability. Furthermore, when molding at extremely high injection speeds using injection molding, it is impossible to obtain aesthetically pleasing molded products. Additionally, when forming an extremely thin coating on a core wire with a very small diameter, it is impossible to adequately suppress the generation of defects in the coating.

[0037] In this invention, the melt flow rate is the value obtained according to ASTM D-1238 using a melt flow index tester G-01 (manufactured by Toyo Seiki Co., Ltd.) as the mass (g / 10 min) of polymer flowing out of a die with an inner diameter of 2 mm and a length of 8 mm every 10 minutes under a load of 5 kg at 372 °C.

[0038] MFR can be adjusted by modifying the type and amount of polymerization initiator and the type and amount of chain transfer agent used in monomer polymerization.

[0039] The fluorinated copolymers of the present invention may or may not have functional groups. Functional groups are those present at the ends of the main chain or side chains of the fluorinated copolymer, or those present in the main chain or side chains. Typical functional groups are -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH.

[0040] 10 of fluorinated copolymers 6 The number of functional groups per carbon atom in the main chain is preferably 90 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, particularly preferably 30 or less, especially preferably 20 or less, and most preferably less than 15. By ensuring that the number of functional groups in the fluorinated copolymer is within the above range, it is possible to obtain a molded article in which fluoride ions are difficult to dissolve in pharmaceutical solutions such as hydrogen peroxide water.

[0041] The number of functional groups in a fluorinated copolymer is the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH.

[0042] 10 of fluorinated copolymers 6 The number of -CF2H atoms per main chain carbon atom is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, even more preferably 20 or less, particularly preferably less than 15, and most preferably less than 10.

[0043] 10 of fluorinated copolymers 6 The total number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2 and -CONH2 with a number of carbon atoms in the main chain is preferably 80 or less, more preferably 70 or less, further preferably 50 or less, even more preferably 40 or less, especially preferably 30 or less, particularly preferably 20 or less, and most preferably less than 15.

[0044] The identification of the types of functional groups and the determination of the number of functional groups mentioned above can be achieved using infrared spectroscopy.

[0045] Regarding the number of functional groups, specifically, it was determined using the following method. First, the above-mentioned fluorinated copolymer was cold-pressed to produce a film with a thickness of 0.25 mm to 0.30 mm. The film was analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above-mentioned fluorinated copolymer, and a differential spectrum was obtained compared with the background spectrum of a fully fluorinated copolymer without functional groups. The number of functional groups in the above-mentioned fluorinated copolymer was calculated from the absorption peaks of specific functional groups shown in the differential spectrum according to the following formula (A). 6 The number of functional groups N per carbon atom.

[0046] N = I × K / t(A)

[0047] I: Absorbance

[0048] K: Correction coefficient

[0049] t: Membrane thickness (mm)

[0050] For reference, the absorption frequencies, molar absorptivity, and correction factors for some functional groups are shown in Table 1. Furthermore, the molar absorptivity was determined using FT-IR measurements of low-molecular-weight model compounds.

[0051] [Table 1]

[0052] Table 1

[0053]

[0054] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are tens of Kaiser (cm) lower than those of -CF2H, -COF, free -COOH, and bonded -COOH, -COOCH3, and -CONH2, respectively, as shown in the table. -1 ).

[0055] For example, the number of functional groups in -COF refers to the number of functional groups originating from the absorption frequency of -CF2COF, which is 1883 cm⁻¹. -1 The number of functional groups derived from the absorption peak at 1840 cm⁻¹ and the absorption frequency originating from -CH₂COF were also analyzed. -1 The total number of functional groups obtained from the absorption peak at the given location.

[0056] Alternatively, the number of -CF2H groups can also be determined using a nuclear magnetic resonance (NMR) apparatus, with the measurement temperature set to (the polymer's melting point + 20) °C. 19 The value was determined by F-NMR analysis and obtained from the peak integral of the -CF2H group.

[0057] Functional groups are those present at the ends of the main chain or side chains of fluorinated copolymers, and those present in the main chain or side chains. The number of functional groups can be the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH.

[0058] The aforementioned functional groups are introduced into the fluorinated copolymer, for example, through chain transfer agents or polymerization initiators used in the manufacture of the fluorinated copolymer. For instance, when an alcohol is used as a chain transfer agent, or when a peroxide having a -CH2OH structure is used as a polymerization initiator, -CH2OH is introduced to the ends of the main chain of the fluorinated copolymer. Alternatively, the aforementioned functional groups are introduced to the ends of the side chains of the fluorinated copolymer by polymerizing monomers containing functional groups.

[0059] By subjecting the fluorinated copolymer having such functional groups to wet heat treatment, fluorination treatment, or other treatments, a fluorinated copolymer having the number of functional groups within the aforementioned range can be obtained. The fluorinated copolymer of the present invention preferably underwent wet heat treatment or fluorination treatment, and more preferably fluorination treatment. The fluorinated copolymer of the present invention also preferably has a -CF3 terminal group.

[0060] The melting point of the fluorinated copolymer is preferably 230°C to 280°C, more preferably 240°C to 268°C. By keeping the melting point within the above range, the moldability of the copolymer is improved, and it is less prone to cracking even when in contact with the agent, resulting in molded articles with better abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads.

[0061] In this invention, the melting point can be determined using a differential scanning calorimeter (DSC).

[0062] The amount of fluoride ions dissolved in hydrogen peroxide water by the fluoride-containing copolymer of the present invention is preferably 8.0 ppm or less by mass, more preferably 3.0 ppm or less, and even more preferably 2.8 ppm or less. By keeping the amount of fluoride ions dissolved within the above range, when a molded body is obtained using the fluoride-containing copolymer of the present invention, it is possible to suppress the dissolution of fluoride ions into the drug solution when used in piping components for drug delivery, flow meter bodies with drug solution flow paths in flow meters, sealing components in contact with drug solution, etc.

[0063] In this invention, the immersion test in hydrogen peroxide water can be carried out as follows: using a fluorinated copolymer, a test piece with a weight equivalent to 10 molded pieces (15mm×15mm×0.2mm) is prepared. A polypropylene bottle containing the test piece and 15g of 3% hydrogen peroxide aqueous solution is placed in a constant temperature bath at 95°C and left for 20 hours.

[0064] The fluorinated copolymers of the present invention can be manufactured by any of the polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. In these polymerization methods, the conditions such as temperature and pressure, the polymerization initiator, chain transfer agent, solvent, and other additives can be appropriately set according to the desired composition and amount of the fluorinated copolymer.

[0065] Oil-soluble free radical polymerization initiators or water-soluble free radical initiators can be used as polymerization initiators.

[0066] As an oil-soluble free radical polymerization initiator, it can be a known oil-soluble peroxide, and the following substances can be cited as representative examples:

[0067] Dialkyl percarbonate esters, such as di-n-propyl percarbonate, diisopropyl percarbonate, and disec-butyl percarbonate;

[0068] Peroxide esters such as tert-butyl peroxide isobutyrate and tert-butyl perpentyl peroxide;

[0069] Dialkyl peroxides such as di-tert-butyl peroxide;

[0070] Di[fluoro(or fluorochloro)acyl] peroxides; etc.

[0071] Examples of diacyl peroxides include those represented by [(RfCOO)-]2 (where Rf is a perfluoroalkyl, ω-hydroperfluoroalkyl, or fluorochloroalkyl).

[0072] Examples of di[fluoro(or fluorochloro)acyl]peroxides include, for example, di(ω-hydro-dodecanoyl)peroxide, di(ω-hydro-tetradecanoyl)peroxide, di(ω-hydro-hexadecanoyl)peroxide, di(perfluorobutyryl)peroxide, di(perfluoropentanoyl)peroxide, di(perfluorohexanoyl)peroxide, di(perfluoroheptanoyl)peroxide, di(perfluorooctanoyl)peroxide, di(perfluorononanoyl)peroxide, di(ω-chloro-hexafluorobutyryl)peroxide, di(ω-chloro-decanoyl)peroxide, and di(ω-decanoyl)peroxide. Fluorohexyl peroxide, di(ω-chloro-tetrafluorooctanoyl) peroxide, ω-hydro-dodecanoyl-ω-hydrohexadecanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydro-dodecanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutyryl) peroxide, di(trichlorooctafluorohexanoyl) peroxide, di(tetrachloroundecanoyl) peroxide, di(pentachlorotetrafluorodecanoyl) peroxide, di(undecatrifluorotetrafluorodienoyl) peroxide, etc.

[0073] As a water-soluble free radical polymerization initiator, it can be a known water-soluble peroxide, such as ammonium salts, potassium salts, sodium salts of persulfate, perboric acid, perchloric acid, superphosphoric acid, and percarbonate, as well as tert-butyl maleate peroxide and tert-butyl hydroperoxide. It may also contain reducing agents such as sulfites, in amounts ranging from 0.1 to 20 times that of the peroxide.

[0074] Examples of chain transfer agents include hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; acetates such as ethyl acetate and butyl acetate; alcohols such as methanol, ethanol, and 2,2,2-trifluoroethanol; thiols such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane, and chloromethane; and 3-fluorobenzotrifluoride. The amount added varies depending on the chain transfer constant of the compound used, and is typically used in the range of 0.01 to 20 parts by mass relative to 100 parts by mass of solvent.

[0075] For example, when using dialkyl peroxide carbonates, di[fluoro(or fluorochloro)acyl]peroxides, etc., as polymerization initiators, the resulting fluorinated copolymers have excessively high molecular weights, sometimes making it difficult to adjust to the desired melt flow rate. However, chain transfer agents can be used to adjust the molecular weight. Fluorinated copolymers are particularly preferably manufactured by suspension polymerization using chain transfer agents such as alcohols and oil-soluble free radical polymerization initiators.

[0076] Examples of solvents include water and mixtures of water and alcohol. Alternatively, the monomers used in the polymerization of the fluorinated copolymers of this invention can also be used as solvents.

[0077] In suspension polymerization, fluorinated solvents can be used in addition to water. Examples of fluorinated solvents include hydrochlorofluorocarbons such as CH3CClF2, CH3CCl2F, CF3CF2CCl2H, and CF2ClCF2CFHCl; chlorofluorocarbons such as CF2ClCFClCF2CF3 and CF3CFClCFClCF3; and perfluoroalkyl hydrocarbons such as perfluorocyclobutane, CF3CF2CF2CF3, CF3CF2CF2CF2CF3, and CF3CF2CF2CF2CF2CF3, with perfluoroalkyl hydrocarbons being preferred. From the perspectives of suspension performance and economy, the amount of fluorinated solvent used is preferably 10 to 100 parts by mass relative to 100 parts by mass of the solvent.

[0078] There is no particular limitation on the polymerization temperature, which can be 0 to 100°C. However, if the decomposition rate of the polymerization initiator is too fast, such as when using dialkyl peroxide carbonate, di[fluoro(or fluorochloro)acyl]peroxide, etc., as the polymerization initiator, it is preferable to use a lower polymerization temperature, such as a polymerization temperature range of 0°C to 35°C.

[0079] The polymerization pressure is appropriately determined based on the type and amount of solvent used, vapor pressure, polymerization temperature, and other polymerization conditions, and is typically 0–9.8 MPaG. The polymerization pressure is preferably 0.1 MPaG–5 MPaG, more preferably 0.5 MPaG–2 MPaG, and even more preferably 0.5 MPaG–1.5 MPaG. Furthermore, a polymerization pressure of 1.5 MPaG or higher can improve production efficiency.

[0080] Examples of additives used in polymerization include suspension stabilizers. There are no particular limitations on existing, well-known suspension stabilizers; methylcellulose, polyvinyl alcohol, etc., can be used. When a suspension stabilizer is used, the suspended particles generated by the polymerization reaction are stably dispersed in the aqueous medium. Therefore, even when using a SUS-made reaction tank without anti-adhesion treatment such as a glass liner, the suspended particles are less likely to adhere to the reaction tank. This allows the use of a high-pressure-resistant reaction tank, enabling polymerization under high pressure and improving production efficiency. Conversely, if polymerization is carried out without a suspension stabilizer, and a SUS-made reaction tank without anti-adhesion treatment is used, suspended particles may adhere, reducing production efficiency. The concentration of the suspension stabilizer relative to the aqueous medium can be adjusted appropriately according to the conditions.

[0081] When an aqueous dispersion containing a fluoropolymer is obtained through polymerization, the dried fluoropolymer can be recovered by precipitating, washing, and drying the fluoropolymer contained in the aqueous dispersion. Alternatively, when a fluoropolymer is obtained in slurry form through polymerization, the dried fluoropolymer can be recovered by removing the slurry from the reaction vessel and washing and drying it. Drying allows the fluoropolymer to be recovered in powder form.

[0082] Fluorinated copolymers obtained through polymerization can be granulated. There are no particular limitations on the granulation method; existing known methods can be used. For example, methods such as melt extruding the fluorinated copolymer using a single-screw extruder, twin-screw extruder, or tandem extruder, and then cutting it into granules of a specified length, can be used. The extrusion temperature during melt extrusion needs to be varied depending on the melt viscosity of the fluorinated copolymer and the manufacturing method; preferably, it is between the melting point of the fluorinated copolymer and 20°C to 140°C. There are no particular limitations on the cutting method of the fluorinated copolymer; existing known methods such as wire cutting, thermal cutting, underwater cutting, and sheet cutting can be used. The volatile components in the granules can also be removed by heating (degassing treatment). Alternatively, the granules can be treated by contacting them with warm water at 30°C to 200°C, steam at 100°C to 200°C, or hot air at 40°C to 200°C.

[0083] Fluorinated copolymers obtained through polymerization can also be heated to temperatures above 100°C in the presence of air and water (wetting heat treatment). Examples of wetting heat treatment methods include: using an extruder, supplying air and water while melting and extruding the fluorinated copolymer obtained through polymerization. Wetting heat treatment can convert thermally unstable functional groups such as -COF and -COOH in the fluorinated copolymer into the more thermally stable -CF2H, easily adjusting the total number of -COF and -COOH, as well as the total number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2 in the fluorinated copolymer to the ranges described above. Besides air and water, heating the fluorinated copolymer in the presence of alkali metal salts can promote the conversion reaction to -CF2H. However, it should be noted that contamination from alkali metal salts should be avoided depending on the intended use of the fluorinated copolymer.

[0084] Fluorinated copolymers obtained by polymerization can also be fluorinated. Fluorination can be carried out by contacting the unfluorinated copolymer with a fluorinated compound. Through fluorination, thermally unstable functional groups such as -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2, as well as the more thermally stable functional groups such as -CF2H, can be converted into the extremely thermally stable -CF3. As a result, the total number of COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, and -CF2H groups in the fluorinated copolymer can be adjusted to the range described above.

[0085] As for fluorine-containing compounds, there are no particular limitations; any fluorine radical source that generates fluorine radicals under fluorination conditions can be cited. Examples of such fluorine radical sources include F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, and fluorinated halogens (e.g., IF5, ClF3).

[0086] Fluorine radical sources such as F2 gas can be 100% concentrated, but from a safety perspective, it is preferable to mix them with an inert gas and dilute them to 5% to 50% by mass before use, and more preferably to 15% to 30% by mass. Examples of such inert gases include nitrogen, helium, and argon; from an economic perspective, nitrogen is preferred.

[0087] The conditions for fluorination are not particularly limited; the molten fluorinated copolymer can be brought into contact with the fluorinated compound. However, it is generally carried out at a temperature below the melting point of the fluorinated copolymer, preferably between 20°C and 220°C, and more preferably between 100°C and 200°C. The fluorination treatment is typically carried out for 1 hour to 30 hours, preferably 5 hours to 25 hours. The preferred method of fluorination treatment is to bring the unfluorinated fluorinated copolymer into contact with fluorine gas (F2 gas).

[0088] The fluorinated copolymer of the present invention can also be mixed with other components as needed to obtain a composition. Other components include fillers, plasticizers, processing aids, mold release agents, pigments, flame retardants, lubricants, light stabilizers, weather stabilizers, conductive agents, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, fragrances, oils, softeners, defluorinated hydrogen agents, etc.

[0089] Examples of fillers include silica, kaolin, clay, organoclay, talc, mica, alumina, calcium carbonate, calcium terephthalate, titanium dioxide, calcium phosphate, calcium fluoride, lithium fluoride, cross-linked polystyrene, potassium titanate, carbon, boron nitride, carbon nanotubes, and glass fiber. Examples of conductive agents include carbon black. Examples of plasticizers include dioctyl phthalate and pentaerythritol. Examples of processing aids include carnauba wax, sulfone compounds, low molecular weight polyethylene, and fluorinated additives. Examples of defluorinating agents include organonium and amidines.

[0090] In addition, other polymers besides the fluorinated copolymers mentioned above can also be used as other components. Examples of other polymers include fluoropolymers, fluororubbers, and non-fluorinated polymers, in addition to the fluorinated copolymers mentioned above.

[0091] Examples of methods for manufacturing the above composition include: dry mixing of the fluorinated copolymer with other components; pre-mixing the fluorinated copolymer with other components using a mixer, followed by melt mixing using a kneader, melt extruder, etc.; etc.

[0092] The fluorinated copolymers or the above-described compositions of the present invention can be used as processing aids, molding materials, etc., and are preferably used as molding materials. Additionally, aqueous dispersions, solutions, suspensions, and copolymer / solvent systems of the fluorinated copolymers of the present invention can be used as coatings, or for encapsulation, impregnation, and film casting. However, due to the aforementioned properties, the fluorinated copolymers of the present invention are preferably used as the above-described molding materials.

[0093] The fluorinated copolymer of the present invention or the above composition can also be molded to obtain a molded body.

[0094] The method for molding the above-mentioned fluorinated copolymer or composition is not particularly limited, and examples include injection molding, extrusion molding, compression molding, blow molding, transfer molding, rotational molding, and roll forming. Among these molding methods, extrusion molding, compression molding, injection molding, or transfer molding are preferred, and injection molding, extrusion molding, or transfer molding are more preferred because they can produce molded articles with high productivity; injection molding is even more preferred. That is, as the molded article, an extruded molded article, a compression molded article, an injection molded article, or a transfer molded article is preferred, and injection molded articles, extruded molded articles, or transfer molded articles are more preferred because they can be produced with high productivity; injection molded articles are even more preferred. By using injection molding to mold the fluorinated copolymer of the present invention, molding can be achieved at extremely high injection speeds, resulting in thin-walled and aesthetically pleasing molded articles.

[0095] As molded bodies containing the fluorinated copolymer of the present invention, they can be, for example, nuts, bolts, joints, membranes, bottles, washers, wire sheaths, tubes, hoses, pipes, valves, plates, seals, gaskets, cans, rollers, containers, stopcocks, connectors, filter housings, filter covers, flow meters, pumps, wafer carriers, wafer boxes, etc.

[0096] The fluorinated copolymers, the above-described compositions, or the above-described molded articles of the present invention can be used for, for example, the following applications.

[0097] Food packaging films, lining materials for fluid transport pipelines used in food manufacturing processes, gaskets, sealing materials, thin sheets, and other fluid transport components for food manufacturing equipment;

[0098] Chemical stoppers, packaging films, lining materials for fluid delivery pipelines used in chemical manufacturing processes, gaskets, sealing materials, thin plates, and other reagent delivery components;

[0099] Inner lining components for chemical equipment and semiconductor plants' liquid tanks and piping;

[0100] O-rings / pipes / gaskets, valve core materials, hoses, sealing materials, etc. used in the fuel system and peripheral devices of automobiles; hoses, sealing materials, and other fuel delivery components used in the AT system of automobiles.

[0101] The carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, hoses, etc. used in the engine and peripheral devices of automobiles; brake hoses, air conditioning hoses, radiator hoses, wire sheathing materials, and other automobile components.

[0102] O-rings, tubes, gaskets, valve core materials, hoses, sealing materials, rollers, washers, diaphragms, connectors and other chemical delivery components for semiconductor manufacturing equipment;

[0103] Coating and ink components for coating equipment, such as coating rollers, hoses, tubes, and ink containers;

[0104] Food and beverage conduits, hoses, belts, gaskets, connectors and other food and beverage conveying components, food packaging materials, and glass cooking equipment;

[0105] Pipes, hoses, and other components used for waste liquid transportation;

[0106] Pipes, hoses, and other components used for high-temperature liquid transfer;

[0107] Pipes, hoses and other components used in steam piping;

[0108] Corrosion-resistant tape for piping, such as tape wrapped around the deck of a ship;

[0109] Various coating materials, such as wire coating materials, optical fiber coating materials, transparent surface coating materials and backing agents applied to the light incident side of photovoltaic elements in solar cells;

[0110] The diaphragm and various sliding components such as gaskets in a diaphragm pump;

[0111] Weather-resistant covers for agricultural films, various roofing materials, and sidewalls;

[0112] Interior materials used in the construction industry, and glass-like covering materials such as non-combustible fire-resistant safety glass;

[0113] Lining materials such as laminated steel sheets used in the home appliance industry.

[0114] Further examples of fuel delivery components used in the fuel systems of the aforementioned automobiles include fuel hoses, filler hoses, and evaporator hoses. These fuel delivery components can also be used for fuels resistant to acidic gasoline, alcohol-based fuels, and fuels containing gasoline additives such as those resistant to methyl tert-butyl ether and amines.

[0115] The aforementioned chemical stoppers and packaging films exhibit excellent chemical resistance to acids and other chemicals. Additionally, anti-corrosion tape wrapped around the piping of chemical equipment can also be cited as a component for transporting the aforementioned chemical solutions.

[0116] Examples of the aforementioned molded bodies include automobile radiator water chambers, medicine tanks, bellows, partitions, rollers, gasoline tanks, waste liquid conveying containers, high-temperature liquid conveying containers, and fish farming and aquaculture tanks.

[0117] Further examples of the molded bodies mentioned above include components used in automobile bumpers, door panels, dashboards, food processing devices, cooking machines, waterproof and oil-proof glass, lighting-related instruments, indicator panels and housings of OA instruments, electrically illuminated signboards, displays, LCD screens, mobile phones, printer chassis, electrical and electronic components, groceries, trash cans, bathtubs, prefabricated bathrooms, exhaust fans, lighting frames, etc.

[0118] Molded articles containing the fluorinated copolymer of the present invention are not prone to cracking even when in contact with pharmaceutical agents. They exhibit excellent abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads. Therefore, they are suitable for use in nuts, bolts, joints, gaskets, valves, stopcocks, connectors, filter housings, filter covers, flow meters, pumps, etc.

[0119] The molded articles containing fluorinated copolymers of the present invention can be manufactured at extremely high injection speeds using injection molding, even in the case of thin-walled portions. They are also less prone to cracking even when in contact with pharmaceuticals, exhibiting excellent abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads. Therefore, they are suitable for use as gaskets, seals, and other compressed components. The compressed components of the present invention can be gaskets or seals. The gaskets or seals of the present invention can be manufactured at low cost using injection molding, are less prone to cracking even when in contact with pharmaceuticals, and exhibit excellent abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads.

[0120] The size and shape of the compressed member of the present invention can be appropriately set according to the application and are not particularly limited. The shape of the compressed member of the present invention can be, for example, ring-shaped. In addition, the compressed member of the present invention can have a circular, elliptical, or quadrilateral shape with rounded corners when viewed from above, and has a through hole in its central part.

[0121] The compressed member of the present invention is preferably used as a component for constructing a non-aqueous electrolyte battery. The compressed member of the present invention is not prone to cracking even when in contact with a pharmaceutical agent, and exhibits excellent abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads. Therefore, it is particularly suitable as a component for use in contact with the non-aqueous electrolyte in a non-aqueous electrolyte battery. That is, the compressed member of the present invention can have a liquid-contacting surface with the non-aqueous electrolyte in a non-aqueous electrolyte battery.

[0122] As for non-aqueous electrolyte batteries, there are no particular limitations as long as the battery contains a non-aqueous electrolyte; examples include lithium-ion secondary batteries and lithium-ion capacitors. Furthermore, components constituting non-aqueous electrolyte batteries include sealing components and insulating components.

[0123] The non-aqueous electrolyte is not particularly limited and can be one or more of the following known solvents: propylene carbonate, ethylene carbonate, butyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The non-aqueous electrolyte battery may further include an electrolyte. The electrolyte is not particularly limited and can be LiClO4, LiAsF6, LiPF6, LiBF4, LiCl, LiBr, CH3SO3Li, CF3SO3Li, cesium carbonate, etc.

[0124] The compressed component of the present invention can preferably be used as a sealing component such as a sealing gasket or sealing pad, or an insulating component such as an insulating gasket or insulating pad. A sealing component is used to prevent leakage of liquid or gas or intrusion of liquid or gas from the outside. An insulating component is used for electrical insulation. The compressed component of the present invention can also be used for both sealing and insulation purposes.

[0125] The compressed component of the present invention is not prone to cracking even when in contact with pharmaceutical agents, exhibits excellent abrasion resistance at 65°C, tensile creep resistance at 140°C, and durability under repeated loads, making it suitable for use as a sealing component or insulating component for non-aqueous electrolyte batteries. Furthermore, the compressed component of the present invention, containing the aforementioned fluorinated copolymer, possesses excellent insulating properties. Therefore, when the compressed component of the present invention is used as an insulating component, it provides a secure seal with two or more conductive components, preventing short circuits over a long period.

[0126] The fluorinated copolymer of the present invention can be easily formed into an extremely thin, defect-free coating layer on a core wire with a very small diameter by extrusion molding, and is therefore suitable as a material for forming wire coatings. Wires with a coating layer containing the fluorinated copolymer of the present invention have almost no spark defects, and therefore exhibit excellent electrical properties.

[0127] The coated wire has a core wire and a coating layer disposed around the core wire containing the fluorinated copolymer of the present invention. For example, the coating layer can be an extruded body formed by melt extrusion molding of the fluorinated copolymer of the present invention onto the core wire. The coated wire is suitable for LAN cables (Ethernet cables), high-frequency transmission cables, flat cables, heat-resistant cables, etc., and is particularly suitable for transmission cables such as LAN cables (Ethernet cables) and high-frequency transmission cables.

[0128] The core wire material can be a metallic conductor such as copper or aluminum. The core wire diameter is preferably 0.02 mm to 3 mm. More preferably, the core wire diameter is 0.04 mm or more, even more preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. Even more preferably, the core wire diameter is 2 mm or less.

[0129] Specific examples of core wires include AWG (American wire gauge)-46 (solid copper wire with a diameter of 40μm), AWG-26 (solid copper wire with a diameter of 404μm), AWG-24 (solid copper wire with a diameter of 510μm), and AWG-22 (solid copper wire with a diameter of 635μm).

[0130] The thickness of the coating layer is preferably 0.1 mm to 3.0 mm. The thickness of the coating layer is also preferably less than 2.0 mm.

[0131] Coaxial cables are an example of high-frequency transmission cables. Coaxial cables typically have a structure consisting of an inner conductor, an insulating sheath, an outer conductor layer, and a protective sheath layer layered sequentially from the core to the outer periphery. Molded bodies containing the copolymers of this invention can be suitable as insulating sheaths containing fluorinated copolymers. The thickness of each layer in the above structure is not particularly limited; typically, the diameter of the inner conductor is about 0.1 mm to 3 mm, the thickness of the insulating sheath is about 0.3 mm to 3 mm, the thickness of the outer conductor layer is about 0.5 mm to 10 mm, and the thickness of the protective sheath is about 0.5 mm to 2 mm.

[0132] The coating may contain air bubbles, which are preferably evenly distributed in the coating.

[0133] The average bubble diameter is not limited, but is preferably 60 μm or less, more preferably 45 μm or less, even more preferably 35 μm or less, even more preferably 30 μm or less, particularly preferably 25 μm or less, and especially preferably 23 μm or less. Furthermore, the average bubble diameter is preferably 0.1 μm or more, more preferably 1 μm or more. The average bubble diameter can be obtained by acquiring an electron microscope image of the wire cross-section, calculating the diameter of each bubble using image processing, and then averaging the results.

[0134] The foaming rate of the coating layer can be 20% or more. More preferably, it is 30% or more, further preferably 33% or more, and even more preferably 35% or more. There is no particular upper limit, for example, 80%. The upper limit of the foaming rate can be 60%. The foaming rate is calculated as ((specific gravity of wire coating material - specific gravity of coating layer) / specific gravity of wire coating material) × 100. The foaming rate can be adjusted appropriately according to the application, for example, by adjusting the gas insertion amount in the extruder described later, or by selecting the type of dissolved gas.

[0135] The coated wire may also have other layers between the core wire and the coating layer, and may further have other layers (outer layers) around the coating layer. If the coating layer contains air bubbles, the wire of the present invention may also be a two-layer structure (outer sheath-foam) with a non-foamed layer inserted between the core wire and the coating layer; a two-layer structure (foam-outer sheath) with a non-foamed layer on the outer layer; and a three-layer structure (outer sheath-foam-outer sheath) with a non-foamed layer on the outer layer of the outer sheath-foam. The non-foamed layer is not particularly limited and may be a resin layer composed of TFE / HFP copolymers, TFE / PAVE copolymers, TFE / ethylene copolymers, vinylidene fluoride polymers, polyolefin resins such as polyethylene [PE], and resins such as polyvinyl chloride [PVC].

[0136] Coated wires can be manufactured, for example, by heating a fluorinated copolymer using an extruder and extruding it onto the core wire while the fluorinated copolymer is in a molten state to form a coating.

[0137] During the formation of the coating layer, the fluorinated copolymer can also be heated, and a gas can be introduced into the fluorinated copolymer while it is in a molten state to form the aforementioned coating layer containing bubbles. The gas can be, for example, dichlorofluoromethane, nitrogen, carbon dioxide, or a mixture of these gases. The gas can be introduced into the heated fluorinated copolymer as a pressurized gas, or it can be generated by mixing a chemical foaming agent into the fluorinated copolymer. The gas dissolves in the molten fluorinated copolymer.

[0138] In addition, the fluorinated copolymer of the present invention is suitable for use as a material in products for high-frequency signal transmission.

[0139] As for the aforementioned high-frequency signal transmission products, there are no particular limitations as long as the product is used for high-frequency signal transmission. Examples include (1) molded boards such as insulating boards for high-frequency circuits, insulating materials for connecting components, and printed wiring boards; (2) molded bodies such as bases and radomes for high-frequency vacuum tubes; and (3) covered wires such as coaxial cables and LAN cables. The aforementioned high-frequency signal transmission products are suitable for use in satellite communication equipment, mobile phone base stations, and other equipment that utilizes microwaves, especially microwaves from 3 GHz to 30 GHz.

[0140] In the aforementioned high-frequency signal transmission products, the fluorinated copolymer of the present invention is suitable for use as an insulator due to its low dielectric loss tangent.

[0141] As for the molded plate described in (1) above, a printed wiring substrate is preferred from the perspective of obtaining good electrical characteristics. There are no particular limitations on the printed wiring substrate described above; examples include printed wiring substrates for electronic circuits in mobile phones, various computers, and communication devices. As for the molded body described in (2) above, an antenna radome is preferred from the perspective of low dielectric loss.

[0142] A film can be obtained by molding the fluorinated copolymer of the present invention. The molded body containing the fluorinated copolymer of the present invention is suitable for use as a film.

[0143] The film of the present invention is useful as a release film. The release film can be manufactured by molding the fluorinated copolymer of the present invention through melt extrusion molding, calendering, compression molding, casting, etc. From the viewpoint of obtaining a uniform film, the release film can be manufactured by melt extrusion molding.

[0144] The membrane of this invention can be applied to the surface of rollers used in OA equipment. Furthermore, the fluorinated copolymer of this invention can be molded into necessary shapes, such as sheets, films, or tubes, through extrusion molding, compression molding, or pressing, for use as a surface material for OA equipment rollers or belts. In particular, thin-walled tubes and membranes can be manufactured using melt extrusion molding.

[0145] The embodiments have been described above, but it should be understood that various changes can be made to the manner and details without departing from the spirit and scope of the claims.

[0146] Example

[0147] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described herein.

[0148] The values ​​in the examples were measured using the following methods.

[0149] (Monomer content)

[0150] The content of each monomer unit in the fluorinated copolymer was determined using an NMR analyzer (e.g., Bruker BioSpin, AVANCE300 high-temperature probe) or an infrared absorption analyzer (Perkin Elmer, Spectrum One).

[0151] (Quantity of -CF2H)

[0152] The number of -CF2H groups in the fluorinated copolymer was determined using an AVANCE-300 nuclear magnetic resonance (NMR) system (manufactured by Bruker BioSpin) at a temperature set to (polymer melting point + 20) °C. 19 The value was determined by F-NMR analysis and obtained from the peak integral of the -CF2H group.

[0153] (The number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2)

[0154] The dried powders or granules obtained in the examples and comparative examples were cold-pressed to form films with a thickness of 0.25 mm to 0.3 mm. The films were analyzed by scanning them 40 times using a Fourier transform infrared spectroscopy (FT-IR) device (Spectrum One, PerkinElmer) to obtain infrared absorption spectra. The obtained infrared absorption spectra were compared with those of known films to determine the types of terminal groups. Furthermore, based on the absorption peaks of specific functional groups appearing in the differential spectrum between the obtained infrared absorption spectra and those of known films, the concentration of each 1 × 10⁻⁶ functional group in the sample was calculated according to the following formula (A). 6 The number of functional groups N per carbon atom.

[0155] N = I × K / t(A)

[0156] I: Absorbance

[0157] K: Correction coefficient

[0158] t: Membrane thickness (mm)

[0159] For reference, the absorption frequencies, molar absorptivity, and correction factors for the functional groups in the examples are shown in Table 2. Furthermore, the molar absorptivity was determined using FT-IR measurement data from the low-molecular-weight model compounds.

[0160] [Table 2]

[0161] Table 2

[0162]

[0163] (Mel flow rate (MFR))

[0164] Regarding the MFR of fluorinated copolymers, according to ASTM D-1238, the mass (g / 10 min) of polymer flowing out of a die with an inner diameter of 2 mm and a length of 8 mm is measured every 10 minutes using a melt flow index tester G-01 (manufactured by Toyo Seiki Co., Ltd.) at 372°C and a load of 5 kg, and the MFR is calculated accordingly.

[0165] (Melting point)

[0166] Regarding the melting point of the fluorinated copolymer, a differential scanning calorimeter (trade name: X-DSC7000, manufactured by Hitachi High-Tech Science) was used to perform a first heating from 200°C to 350°C at a heating rate of 10°C / min. Then, the temperature was cooled from 350°C to 200°C at a cooling rate of 10°C / min. A second heating was then performed from 200°C to 350°C at a heating rate of 10°C / min. The melting point was determined from the peak value of the melting curve generated during the second heating process.

[0167] Example 1

[0168] 40.25 kg of deionized water and 0.533 kg of methanol were added to a 174 L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen. Afterward, the autoclave was degassed under vacuum, and 40.25 kg of HFP and 1.21 kg of PPVE were added to the vacuum-sealed autoclave. The autoclave was then heated to 25.5 °C. Next, TFE was added until the internal pressure of the autoclave reached 0.878 MPa. Then, 1.25 kg of 8% by mass di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) was added to the autoclave to begin polymerization. The internal pressure of the autoclave at the start of polymerization was set to 0.878 MPa, and this pressure was maintained by continuously adding TFE. 0.533 kg of methanol was added 1.5 hours after the start of polymerization. Two hours after the start of polymerization, 1.25 kg of DHP was added, and four hours later, with the internal pressure reduced by 0.002 MPa. Six hours later, 0.96 kg of DHP was added, with the internal pressure reduced by 0.002 MPa each time. Thereafter, 0.25 kg of DHP was added every two hours until the reaction was complete, with the internal pressure reduced by 0.002 MPa each time.

[0169] It should be noted that 0.27 kg of PPVE was added at the points when the TFE addition reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. Additionally, 0.533 kg of methanol was added to the autoclave at the points when the TFE addition reached 6.0 kg and 18.1 kg, respectively. The polymerization was terminated when the TFE addition reached 40.25 kg. After polymerization, unreacted TFE and HFP were released, yielding a wet powder. This wet powder was then washed with pure water and dried at 150°C for 10 hours to obtain 45.2 kg of dry powder.

[0170] The obtained powder was melt-extruded at 370°C using a screw extruder (trade name: PCM46, manufactured by Chibei Co., Ltd.) to obtain copolymer granules. The obtained granules were then used to determine various physical properties using the method described above. The results are shown in Table 3.

[0171] Example 2

[0172] The amount of methanol added before polymerization was changed to 0.461 kg, and the amount of methanol added separately after polymerization started was also changed to 0.461 kg each time. The amount of PPVE added before polymerization was changed to 0.93 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.855 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0173] The obtained granules were degassed in an electric furnace at 200°C for 8 hours, then placed in a VVD-30 vacuum vibratory reactor (manufactured by Okawahara Seisakusho Co., Ltd.), and heated to 200°C. After evacuation, F2 gas diluted to 20% by volume with N2 gas was introduced to atmospheric pressure. 0.5 hours after the introduction of F2 gas, a temporary vacuum was applied, and F2 gas was introduced again. This process was repeated 0.5 hours later, followed by another vacuum and introduction of F2 gas. This process of introducing F2 gas and evacuating the vacuum was repeated every hour, and the reaction was carried out at 200°C for 8 hours. After the reaction, the reactor was completely replaced with N2 gas to terminate the fluorination reaction, yielding granules. Various physical properties of the obtained granules were measured using the above method. The results are shown in Table 3.

[0174] Example 3

[0175] The amount of methanol added before polymerization was changed to 0.390 kg, and the amount of methanol added separately after polymerization started was also changed to 0.390 kg each time. The amount of PPVE added before polymerization was changed to 0.83 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.830 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0176] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0177] Example 4

[0178] 40.25 kg of deionized water and 0.384 kg of methanol were added to a 174 L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen under vacuum. Then, the autoclave was degassed under vacuum, and 40.25 kg of HFP and 0.63 kg of PPVE were added to the vacuum-sealed autoclave. The autoclave was then heated to 30.0 °C. Next, TFE was added until the internal pressure of the autoclave reached 0.911 MPa. Then, 0.63 kg of 8% (w / w) di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) was added to the autoclave to begin polymerization. The internal pressure of the autoclave at the start of polymerization was set to 0.911 MPa, and this pressure was maintained by continuously adding TFE. 0.384 kg of methanol was added 1.5 hours after the start of polymerization. Two hours and four hours after the start of polymerization, 0.63 kg of DHP was added, and the internal pressure was reduced by 0.001 MPa. Six hours later, 0.48 kg of DHP was added, and the internal pressure was reduced by 0.001 MPa. Thereafter, 0.13 kg of DHP was added every two hours until the reaction was completed, and the internal pressure was reduced by 0.001 MPa each time.

[0179] It should be noted that 0.19 kg of PPVE was added at the points when the TFE addition reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. Additionally, 0.384 kg of methanol was added to the autoclave at the points when the TFE addition reached 6.0 kg and 18.1 kg, respectively. The polymerization was terminated when the TFE addition reached 40.25 kg. After polymerization, unreacted TFE and HFP were released, yielding a wet powder. This wet powder was then washed with pure water and dried at 150°C for 10 hours to obtain 46.6 kg of dry powder.

[0180] The obtained powder was melt-extruded at 370°C using a screw extruder (trade name: PCM46, manufactured by Chibei Co., Ltd.) to obtain copolymer granules. The HFP and PPVE contents of the obtained granules were determined using the method described above. The results are shown in Table 3.

[0181] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0182] Example 5

[0183] The amount of methanol added before polymerization was changed to 0.353 kg, and the amount of methanol added separately after polymerization started was also changed to 0.353 kg each time. The amount of PPVE added before polymerization was changed to 0.59 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.19 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.897 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0184] The obtained granules were degassed in an electric furnace at 200°C for 72 hours, then placed in a VVD-30 vacuum vibratory reactor (manufactured by Okawahara Manufacturing Co., Ltd.), and heated to 110°C. After evacuation, F2 gas diluted to 20% by volume with N2 gas was introduced to atmospheric pressure. 0.5 hours after the introduction of F2 gas, a temporary vacuum was applied, and F2 gas was introduced again. This process was repeated 0.5 hours later, followed by another vacuum and introduction of F2 gas. This process of introducing F2 gas and evacuating the vacuum was repeated every hour, and the reaction was carried out at 110°C for 8 hours. After the reaction was completed, the reactor was completely replaced with N2 gas to stop the fluorination reaction and obtain the granules. Various physical properties of the obtained granules were measured using the above method. The results are shown in Table 3.

[0185] Example 6

[0186] The amount of methanol added before polymerization was changed to 0.428 kg, and the amount of methanol added separately after polymerization started was changed to 0.428 kg each time. The amount of PPVE added before polymerization was changed to 0.62 kg, and the amount of PPVE added separately after polymerization started was changed to 0.18 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.923 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. Various physical properties were measured using the obtained granules according to the above method. The results are shown in Table 3.

[0187] Comparative Example 1

[0188] The amount of methanol added before polymerization was changed to 0.376 kg, and the amount of methanol added separately after polymerization started was also changed to 0.376 kg each time. The amount of PPVE added before polymerization was changed to 0.35 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.11 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.897 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0189] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0190] Comparative Example 2

[0191] The amount of methanol added before polymerization was changed to 0.725 kg, and the amount of methanol added separately after polymerization started was also changed to 0.725 kg each time. The amount of PPVE added before polymerization was changed to 1.23 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.936 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The obtained granules were used without fluorination, and various physical properties were measured using the above method. The results are shown in Table 3.

[0192] Comparative Example 3

[0193] The amount of methanol added before polymerization was changed to 0.186 kg, and the amount of methanol added separately after polymerization started was also changed to 0.186 kg each time. The amount of PPVE added before polymerization was changed to 0.83 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.27 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.897 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. The obtained granules were used without fluorination, and various physical properties were measured using the above method. The results are shown in Table 3.

[0194] Comparative Example 4

[0195] The amount of methanol added before polymerization was changed to 0.355 kg, and the amount of methanol added separately after polymerization started was also changed to 0.355 kg each time. The amount of PPVE added before polymerization was changed to 0.35 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.11 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.897 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0196] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0197] Comparative Example 5

[0198] 945g of deionized water and 7.8g of methanol were added to a 4L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen. Afterward, the autoclave was degassed, and 945g of HFP and 13.9g of PEVE were added to the now vacuum-sealed autoclave. The autoclave was then heated to 30.0°C. Next, TFE was added until the internal pressure of the autoclave reached 0.900MPa. Then, 14.7g of an 8wt% di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) was added to the autoclave to begin polymerization. The internal pressure of the autoclave at the start of polymerization was set to 0.900MPa, and this pressure was maintained by continuously adding TFE. 7.8g of methanol was added 1.5 hours after the start of polymerization. Two hours and four hours after the start of polymerization, 14.7 g of DHP was added, and the internal pressure was reduced by 0.001 MPa. Six hours later, 11.3 g of DHP was added, and the internal pressure was reduced by 0.001 MPa. Thereafter, 3.0 g of DHP was added every two hours until the reaction was completed, and the internal pressure was reduced by 0.001 MPa each time.

[0199] It should be noted that 4.4g of PEVE was added at the points where TFE was continuously added to 190g and 380g, respectively. Additionally, 7.8g of methanol was added to the autoclave when TFE was added to 140g. The polymerization was terminated when TFE was added to 454g. After polymerization, unreacted TFE and HFP were released, yielding a wet powder. This wet powder was then washed with pure water and dried at 150℃ for 10 hours to obtain 528g of dry powder.

[0200] The obtained powder is used The copolymer granules were obtained by melt extrusion at 370°C using a screw extruder (manufactured by Imoto Manufacturing Co., Ltd.). The HFP and PEVE contents of the obtained granules were determined using the method described above. The results are shown in Table 3.

[0201] The obtained granules were degassed in an electric furnace at 200°C for 8 hours, then placed in a portable TVS1 type reactor (manufactured by a pressure-resistant glass industry company) and heated to 200°C. After evacuation, F2 gas diluted to 20% by volume with N2 gas was introduced to atmospheric pressure. 0.5 hours after the introduction of F2 gas, a temporary vacuum was applied, and F2 gas was introduced again. Then, after another 0.5 hours, a vacuum was applied again, and F2 gas was introduced again. This process of introducing F2 gas and evacuating vacuum was repeated every hour, and the reaction was carried out at 200°C for 8 hours. After the reaction was completed, the reactor was completely replaced with N2 gas to stop the fluorination reaction, yielding granules. Various physical properties of the obtained granules were determined using the above method. The results are shown in Table 3.

[0202] Comparative Example 6

[0203] 40.25 kg of deionized water and 0.352 kg of methanol were added to a 174 L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen under vacuum. Then, the autoclave was degassed under vacuum, and 40.25 kg of HFP and 0.78 kg of PPVE were added to the vacuum-sealed autoclave. The autoclave was then heated to 32.0 °C. Next, TFE was added until the internal pressure of the autoclave reached 0.926 MPa. Then, 0.31 kg of 8% by mass di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) was added to the autoclave to begin polymerization. The internal pressure of the autoclave at the start of polymerization was set to 0.926 MPa, and this pressure was maintained by continuously adding TFE. 0.352 kg of methanol was added 1.5 hours after the start of polymerization. Two hours and four hours after the start of polymerization, additional 0.31 kg of DHP was added, and the internal pressure was reduced by 0.001 MPa. Six hours later, 0.24 kg of DHP was added, and the internal pressure was reduced by 0.001 MPa. Thereafter, 0.07 kg of DHP was added every two hours until the reaction was complete.

[0204] It should be noted that 0.28 kg of PPVE was added at the points when the TFE addition reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. Additionally, 0.352 kg of methanol was added to the autoclave at the points when the TFE addition reached 6.0 kg and 18.1 kg, respectively. The polymerization was terminated when the TFE addition reached 40.25 kg. After polymerization, unreacted TFE and HFP were released, yielding a wet powder. This wet powder was then washed with pure water and dried at 150°C for 10 hours to obtain 47.9 kg of dry powder.

[0205] The obtained powder was melt-extruded at 370°C using a screw extruder (trade name: PCM46, manufactured by Chibei Co., Ltd.) to obtain copolymer granules. The obtained granules were then used to determine various physical properties using the method described above. The results are shown in Table 3.

[0206] Comparative Example 7

[0207] The amount of methanol added before polymerization was changed to 0.464 kg, and the amount of methanol added separately after polymerization started was also changed to 0.464 kg each time. The amount of PPVE added before polymerization was changed to 0.88 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.843 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0208] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0209] Comparative Example 8

[0210] The amount of methanol added before polymerization was changed to 0.224 kg, and the amount of methanol added separately after polymerization started was also changed to 0.224 kg each time. The amount of PPVE added before polymerization was changed to 1.32 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.41 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.902 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 4. The HFP and PPVE contents of the obtained granules were determined using the above method. The results are shown in Table 3.

[0211] The obtained granules were fluorinated in the same manner as in Example 2. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0212] [Table 3]

[0213] Table 3

[0214]

[0215] The "<9" in Table 3 refers to the number of -CF2H groups being less than 9. The "<6" in Table 3 refers to the total number (functional group number N) of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2 being less than 6.

[0216] Next, the obtained granules were used to evaluate the following properties. The results are shown in Table 4.

[0217] (Abrasion test)

[0218] Using a granulation and hot-press molding machine, sheet-shaped test pieces with a thickness of approximately 0.2 mm were prepared, from which 10 cm × 10 cm test pieces were cut. The prepared test pieces were fixed on the test bench of a Tiber abrasion testing machine (No. 101 Special Type Tiber Abrasion Testing Machine, manufactured by Yasuda Seiki Co., Ltd.). Abrasion tests were conducted using the Tiber abrasion testing machine under the following conditions: test piece surface temperature 65°C, load 500 g, abrasion wheel CS-10 (grinding with #240 abrasive paper for 20 revolutions), and rotation speed 60 rpm. The weight of the test piece was measured after 1000 revolutions, and the same test piece was further tested after 5500 revolutions, and the weight of the test piece was measured again. The amount of abrasion was calculated using the following formula.

[0219] Wear amount (mg) = M1 - M2

[0220] M1: Weight of the test piece after 1000 revolutions (mg)

[0221] M2: Weight of the test piece after 5500 revolutions (mg)

[0222] (Tensile creep test)

[0223] Tensile creep strain was determined using a Hitachi High-Tech TMA-7100. Sheets approximately 0.1 mm thick were prepared using a granulator and thermoforming machine. Samples 2 mm wide and 22 mm long were then fabricated from these sheets. The samples were mounted in the measuring fixture with a 10 mm gap between the clamps. A cross-sectional load of 3.32 N / mm² was applied to the samples. 2 The sample was subjected to a load at 140°C, and the displacement (mm) of its length was measured from 90 minutes to 450 minutes after the start of the test. The ratio of the displacement (mm) to the initial sample length (10mm) was calculated (tensile creep strain (%)). Samples with low tensile creep strain (%) measured at 140°C for 450 minutes do not easily elongate even under prolonged tensile loads in high-temperature environments, demonstrating excellent high-temperature tensile creep resistance (140°C).

[0224] (Tensile strength after 100,000 cycles)

[0225] Tensile strength after 100,000 cycles was determined using a Shimadzu MMT-250NV-10 fatigue testing machine. A pellet approximately 2.4 mm thick was prepared using a granulator and thermoforming machine. A dumbbell-shaped sample (2.4 mm thickness, 5.0 mm width, and 22 mm measuring section length) was fabricated using ASTM D1708 micro dumbbells. The sample was mounted in the testing fixture, which was then placed in a 110°C thermostatic bath with the sample mounted. Uniaxial tension was repeatedly applied at a stroke of 0.2 mm and a frequency of 100 Hz, and the tensile strength (tensile strength at a stroke of +0.2 mm, unit: N) was measured for each tension.

[0226] The sheet with high tensile strength after 100,000 cycles maintains high tensile strength even after being subjected to 100,000 loads, and has excellent durability under repeated loads (110°C).

[0227] (Extrusion pressure)

[0228] Extrusion pressure was measured using a RHEOGRAPH 25 dual capillary rheometer (manufactured by Goettfert). A main die inner diameter of 1 mm, L / D = 16, and a secondary die inner diameter of 1 mm, L / D < 1, were used. The measurement temperature was 350°C, the residual heat time after pellet feeding was 10 minutes, and the shear rate was 20 sec. -1 Extrusion was performed for 10 minutes, and the pressure value inside the barrel after extrusion was Bagley corrected, which was then used as the extrusion pressure. Copolymers with low extrusion pressure exhibit excellent extrusion molding properties, injection molding properties, and other molding properties.

[0229] (Wire Covering Test)

[0230] use A wire coating extrusion molding machine (manufactured by Mitsuba Corporation) extrudes a fluorinated copolymer onto a copper conductor with a conductor diameter of 0.079 mm to obtain a coated wire at the following coating thickness. The wire coating extrusion molding conditions are as follows.

[0231] a) Core conductor: Conductor diameter 0.079mm (AWG40)

[0232] b) Coating thickness: 0.040mm

[0233] c) Diameter of the covered wire: 0.16mm

[0234] d) Wire pulling speed: 50m / minute

[0235] e) Extrusion conditions:

[0236] • Single-screw extruder with a barrel diameter of 20mm and an L / D ratio of 24

[0237] • Die head (inner diameter) / piece (outer diameter) = 2.3mm / 1.2mm

[0238] Extruder temperature settings: Barrel section C-1 (330℃), Barrel section C-2 (350℃), Barrel section C-3 (365℃), Neck (365℃), Head (370℃), Die head D (370℃). Core wire preheating is set to 150℃.

[0239] For the covered wires in the wire covering test, the following evaluation is performed to assess the number of sparks and the presence or absence of covering breaks.

[0240] (The presence or absence of a disconnected covering)

[0241] If the wire coating process is continuous and the coating breaks more than once in 1 hour, it is considered that continuous forming is not possible (×), and if no coating breaks occur, it is considered that continuous forming is possible (○).

[0242] (Number of sparks)

[0243] An online spark tester (Clinton HF-15AC) is used to evaluate the presence of defects in the wire sheath at a voltage of 500V. Zero sparks after one hour of continuous forming are considered acceptable (○), while the presence of sparks is considered unacceptable (×).

[0244] (Injection molding)

[0245] ·condition

[0246] An injection molding machine (Sumitomo Heavy Industries, SE50EV-A) was used, with a barrel temperature of 385°C, a mold temperature of 180°C, and a copolymer injection speed of 100 mm / s. A Cr-plated mold (50 mm × 35 mm × 0.5 mm, 4-cavity, side gate) was used for HPM38. The four resulting injection molded parts were observed and evaluated according to the following criteria. The presence or absence of surface roughness was confirmed by examining the surfaces in contact with the injection molded parts.

[0247] 2: The surfaces of all four molded bodies are smooth.

[0248] 1: For a portion of the four molded bodies, roughness was confirmed on the surface within 1 cm of the location of the mold gate.

[0249] 0: Roughness was confirmed on the surface of all four molded bodies.

[0250] (Crack test due to chemical impregnation)

[0251] With approximately 50g of the aforementioned granules placed in a mold (120mm inner diameter, 38mm height), the mixture was heated at 360°C for 20 minutes using a hot plate press, followed by water cooling under pressure of 1MPa to produce a molded body approximately 2mm thick. A 13.5mm × 38mm rectangular dumbbell was used to punch-cut the resulting sheet, yielding three test pieces. A 19mm × 0.45mm notch was cut at the center of the long side of each test piece according to ASTM D1693. The three notched test pieces and 25g of a 30% by weight sodium hydroxide aqueous solution were placed in a 100mL polypropylene bottle, and the mixture was heated at 100°C for 20 hours. The notched test pieces were then removed. The three notched test pieces were mounted on a stress cracking test fixture according to ASTM D1693, and the notches and their surrounding areas were visually observed to count the number of cracks.

[0252] ○: The number of cracks is 0

[0253] ×: The number of cracks is more than 1.

[0254] (Immersion test in hydrogen peroxide water)

[0255] Using granulation and a hot press molding machine, sheets with a thickness of approximately 0.2 mm were made, and test sheets with a square diameter of 15 mm were prepared. Ten test sheets and 15 g of 3% (w / w) hydrogen peroxide aqueous solution were placed in a 50 mL polypropylene bottle. The mixture was heated at 95°C for 20 hours and then cooled to room temperature. The test sheets were removed from the hydrogen peroxide aqueous solution, and TISAB solution (10) (manufactured by Kanto Chemical Co., Ltd.) was added to the remaining hydrogen peroxide aqueous solution. The fluoride ion concentration in the resulting hydrogen peroxide aqueous solution was measured using a fluoride ion meter. The fluoride ion concentration per unit weight of sheet (dissolved fluoride ion concentration) was calculated from the measured values ​​according to the following formula.

[0256] Dissolved fluoride ion concentration (ppm) = Measured value (ppm) × Volume of hydrogen peroxide aqueous solution (g) / Weight of test piece (g)

[0257]

Claims

1. A fluorine-containing copolymer which is a fluorine-containing copolymer containing tetrafluoroethylene units, hexafluoropropylene units and perfluoro(propyl vinyl ether) units, wherein the content of the tetrafluoroethylene units is 85.1 to 91.5 mass% relative to the total monomer units, the content of the hexafluoropropylene units is 7.0 to 12.0 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5 to 2.9 mass% relative to the total monomer units, the content of the tetrafluoroethylene units is 85.1 to 91.5 mass% relative to the total monomer units, the melt flow rate under a load of 5 kg at 372°C is 40 to 60 g / 10 min.

2. The fluorocopolymer of claim 1, wherein, the content of the hexafluoropropylene units is 7.7 to 11.5 mass% relative to the total monomer units.

3. The fluorocopolymer of claim 1 or 2, wherein, the content of the perfluoro(propyl vinyl ether) units is 1.6 to 2.4 mass% relative to the total monomer units.

4. The fluorocopolymer of claim 1 or 2, wherein, the melt flow rate under a load of 5 kg at 372°C is 46 to 60 g / 10 min.

5. The fluorocopolymer of claim 1 or 2, wherein, - the number of functional groups of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH is 90 or less per 10 6 main chain carbon atoms.

6. An injection-molded article containing the fluorine-containing copolymer according to any one of claims 1 to 5.

7. A coated electric wire having a coating layer containing the fluorine-containing copolymer according to any one of claims 1 to 5.

8. A molded article which is a molded article containing the fluorine-containing copolymer according to any one of claims 1 to 5, wherein The molded article is a wire coating.

Images