Fluorine-containing copolymer, injection-molded body, electric wire coating material, and electric wire

Abstract

This invention provides a fluorinated copolymer containing tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein the content of hexafluoropropylene units is 5.0 to 7.0% by mass relative to all monomer units, the content of perfluoro(propyl vinyl ether) units is 1.5% to 2.6% by mass relative to all monomer units, and the melt flow rate at 372°C is 9 g / 10 min to 40 g / 10 min.

Description

Technical Field

[0001] This invention relates to fluorinated copolymers, injection molded articles, wire coating materials, and wires. Background Technology

[0002] Patent document 1 describes a terpolymer containing (a) tetrafluoroethylene, (b) hexafluoropropylene in a weight of about 4 to about 12 wt% based on the terpolymer, and (c) perfluoro(ethyl vinyl ether) or perfluoro(n-propyl vinyl ether) in a weight of about 0.5 to about 3 wt% based on the terpolymer.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 52-109588 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this invention is to provide a fluorinated copolymer that can be molded at high injection speed to obtain a beautiful injection molded body, can form a thin coating layer on a small diameter core wire at high speed through extrusion molding, can obtain a beautiful tube through extrusion molding, and can obtain a molded body with excellent abrasion resistance at 125°C, low water vapor permeability, low carbon dioxide permeability, creep resistance, durability under repeated loads, and crack resistance.

[0008] In addition, the present invention aims to provide a wire coating material that can easily form a coating layer with few defects on the core wire, can suppress the penetration of water vapor from the outside of the wire to a very low level, is not prone to cracking of the coating layer even when in contact with chemicals, and has excellent shape stability of the coating layer, thus enabling the generation of wires that suppress cracks during winding.

[0009] [Methods used to solve problems]

[0010] According to the present invention, a fluorinated copolymer is provided, comprising tetrafluoroethylene units, hexafluoropropylene units and perfluoro(propyl vinyl ether) units, wherein the content of hexafluoropropylene units is 5.0 to 7.0% by mass relative to all monomer units, the content of perfluoro(propyl vinyl ether) units is 1.5% to 2.6% by mass relative to all monomer units, and the melt flow rate at 372°C is 9 g / 10 min to 40 g / 10 min.

[0011] The content of hexafluoropropylene units relative to all monomer units is preferably 5.2 to 6.8% by mass.

[0012] The content of perfluoro(propyl vinyl ether) units is preferably 1.7% to 2.4% by mass relative to all monomer units.

[0013] The melt flow rate at 372°C is preferably 11–38 g / 10 min.

[0014] Every 10 6 The number of main chain carbon atoms and the number of functional groups are less than 90.

[0015] In addition, according to the present invention, an injection-molded article containing the above-mentioned fluorinated copolymer is provided.

[0016] In addition, according to the present invention, a wire coating material containing the above-mentioned fluorinated copolymer is provided.

[0017] In addition, according to the present invention, an electric wire is provided, which has a core wire and a coating layer disposed around the core wire and obtained by the above-described wire coating material.

[0018] Invention Effects

[0019] According to the present invention, a fluorinated copolymer can be provided, which can be molded at high injection speed by injection molding to obtain a beautiful injection molded body, can form a thin coating layer on a small diameter core wire at high speed by extrusion molding, can obtain a beautiful tube by extrusion molding, and can obtain a molded body with excellent abrasion resistance at 125°C, low water vapor permeability, low carbon dioxide permeability, creep resistance, durability under repeated loads, and crack resistance.

[0020] In addition, according to the present invention, a wire coating material can be provided that can easily form a coating layer with few defects on the core wire, can suppress the penetration of water vapor from the outside of the wire to a very low level, is not prone to cracking of the coating layer even when in contact with chemicals, and has excellent shape stability of the coating layer, thus enabling the generation of wires that suppress cracks during winding. Detailed Implementation

[0021] The following describes specific embodiments of the present invention in detail, but the present invention is not limited to the following embodiments.

[0022] The fluorinated copolymer of the present invention contains tetrafluoroethylene (TFE) units, hexafluoropropylene (HFP) units, and perfluoro(propyl vinyl ether) (PPVE) units.

[0023] As fluoropolymers, non-melt-processable fluoropolymers such as polytetrafluoroethylene (PTFE) and melt-processable fluoropolymers are known. PTFE has excellent properties, but suffers from the disadvantage of being extremely difficult to melt-process. On the other hand, melt-processable fluoropolymers include TFE / HFP copolymers (FEP) and TFE / PPVE copolymers (PFA), but these have disadvantages such as poorer heat resistance compared to PTFE. Therefore, in Patent Document 1, the aforementioned terpolymer was proposed as a fluorocarbon polymer that improves upon these disadvantages.

[0024] However, there is a need for a fluorinated copolymer that can be injection molded and, compared to conventional fluorinated copolymers such as the terpolymer described in Patent Document 1, can produce molded articles with superior abrasion resistance at 125°C, low water vapor permeability, low carbon dioxide permeability, creep resistance, durability under repeated loads, and crack resistance.

[0025] It was discovered that by adjusting the content of HFP and PPVE units in fluorinated copolymers containing TFE, HFP, and PPVE units, as well as the melt flow rate, to extremely limited ranges, the injection molding properties of fluorinated copolymers are significantly improved. Furthermore, by using such fluorinated copolymers, molded articles exhibiting excellent abrasion resistance at 125°C, low water vapor permeability, low carbon dioxide permeability, creep resistance, durability under repeated loads, and crack resistance can be obtained. By using fluorinated copolymers with these excellent properties as bushings for applications such as piping, valves, and containers, bushings that are difficult to permeate with water vapor and carbon dioxide gases, and that are less prone to cracking and deformation even when in contact with high-temperature chemicals, can be obtained.

[0026] Furthermore, when conventional terpolymers are used to coat the core wire in order to form coated wires, the resulting coated wires suffer from problems such as the coating layer being prone to defects and insufficient crack resistance during winding. In addition, conventional terpolymers also have problems such as low water vapor permeability and the coating layer being prone to cracking when in contact with chemicals.

[0027] It has been discovered that by adjusting the content of HFP and PPVE units in fluorinated copolymers containing TFE, HFP, and PPVE units, as well as the melt flow rate, to extremely limited ranges, a defect-free coating layer can be easily formed on the core wire using a wire coating material containing such a fluorinated copolymer, resulting in wires that suppress the formation of cracks during winding. Furthermore, it has also been found that by using a wire coating material containing such a fluorinated copolymer, wires that exhibit extremely low suppression of water vapor penetration from the outside of the wire, are less prone to coating cracking even in contact with chemicals, and possess excellent coating shape stability can be obtained.

[0028] Furthermore, by using extrusion molding to form the fluorinated copolymer of the present invention, a film of uniform thickness can be formed at a high molding speed. Thus, the fluorinated copolymer of the present invention can be used not only as bushing material and wire coating, but also for a wide range of applications such as films.

[0029] The fluorinated copolymer of the present invention is a melt-processable fluoropolymer. Melt processability means that the polymer can be melted and processed using conventional processing equipment such as extruders and injection molding machines.

[0030] The content of HFP units in the fluorinated copolymer is 5.0 to 7.0% by mass relative to all monomer units, preferably 5.1% by mass or more, more preferably 5.2% by mass or more, further preferably 5.5% by mass or more, preferably 6.9% by mass or less, more preferably 6.8% by mass or less, further preferably 6.6% by mass or less, and most preferably 6.5% by mass or less. When the content of HFP units is too high, it is impossible to obtain a molded article with excellent low water vapor permeability, creep resistance, and durability under repeated loads; when the content of HFP units is too low, it is impossible to obtain a molded article with excellent abrasion resistance and crack resistance at 125°C. In particular, when the content of HFP units is too high, the suppression of water vapor permeation required as a wire coating material is insufficient, and the shape stability required as a coating layer is insufficient, therefore, the effect of suppressing the flattening of the coating layer is insufficient; when the content of HFP units is too low, the crack resistance during winding becomes insufficient when making wires, and the suppression of cracking of the coating layer when in contact with chemicals becomes insufficient.

[0031] The content of PPVE units in the fluorinated copolymer is 1.5% to 2.6% by mass relative to all monomer units, preferably 1.6% by mass or more, more preferably 1.7% by mass or more, further preferably 1.8% by mass or more, particularly preferably 1.9% by mass or more, preferably 2.5% by mass or less, more preferably 2.4% by mass or less, and further preferably 2.2% by mass or less. If the content of PPVE units is too high, a molded article with excellent low water vapor permeability cannot be obtained; if the content of PPVE units is too low, a molded article with excellent abrasion resistance and crack resistance at 125°C cannot be obtained. In particular, if the content of PPVE units is too high, the low water vapor permeability is poor; if the content of PPVE units is too low, the crack resistance during winding becomes insufficient when making wires, and the suppression of cracking of the coating layer when in contact with the agent becomes insufficient.

[0032] The content of TFE units in the fluorinated copolymer is preferably 90.4 to 93.5% by mass relative to all monomer units, more preferably 90.6% by mass or more, 90.8% by mass or more, further preferably 91.0% by mass or more, particularly preferably 91.2% by mass or more, more preferably 93.4% by mass or less, further preferably 93.2% by mass or less, even more preferably 93.0% by mass or less, and particularly preferably 92.8% by mass or less. Alternatively, the content of TFE units can be selected such that the total content of HFP units, PPVE units, TFE units, and other monomer units is 100% by mass.

[0033] Fluorinated copolymers can be copolymers containing only the above three monomer units, or copolymers containing the above three monomer units and other monomer units, as long as they contain the above three monomer units.

[0034] As for other monomers, there are no particular limitations as long as they can copolymerize with TFE, HFP, and PPVE. They can be either fluorinated or non-fluorinated monomers.

[0035] As a fluorinated monomer, it is preferably selected from trifluorochloroethylene, vinylidene fluoride, vinylidene fluoride, trifluoroethylene, hexafluoroisobutylene, CH2=CZ. 1 (CF2) n Z 2 (where Z) 1 For 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].

[0036] 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.

[0037] As CF2 = CF - ORf 1Examples of perfluorinated (alkyl vinyl ethers) include CF2=CF-OCF3 and CF2=CF-OCF2CF3.

[0038] 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.

[0039] 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.

[0040] The content of other monomer units in the fluorinated copolymer, relative to all monomer units, can be 0 to 3.1% by mass, preferably 0 to 3.0% by mass, 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.

[0041] The melt flow rate (MFR) of the fluorinated copolymer is 9–40 g / 10 min, preferably 9.1 g / 10 min or more, more preferably 10 g / 10 min or more, further preferably 11 g / 10 min or more, even more preferably 12 g / 10 min or more, particularly more preferably 13 g / 10 min or more, especially preferably 18 g / min or more, most preferably 20 g / 10 min or more, preferably 39.9 g / 10 min or less, more preferably 39 g / 10 min or less, further preferably 38 g / 10 min or less, even more preferably 34 g / 10 min or less, especially more preferably 33 g / 10 min or less, particularly preferably 32 g / 10 min or less, and most preferably 30.0 g / 10 min or less. If the MFR is too high, the moldability is poor, and it is impossible to obtain a molded article with excellent abrasion resistance and crack resistance at 125°C. If the MFR is too low, it is impossible to obtain a molded article with excellent low water vapor permeability and low carbon dioxide permeability. Furthermore, if the MFR is too low, it is difficult to form a thin coating at high speed on a small-diameter core wire. In particular, when the MFR of the fluorinated copolymer is too high, defects in the formed coating are easily generated when the coating is formed on the core wire, and when the wire is manufactured, the suppression of crack formation during winding becomes insufficient. When the MFR of the fluorinated copolymer is too low, the water vapor permeability and carbon dioxide permeability are poor, and the formation of defects in the formed coating becomes significant when the coating is formed on the core wire.

[0042] 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 / 10min) of polymer flowing out of a die with an inner diameter of 2mm and a length of 8mm every 10 minutes under a load of 5kg at 372°C.

[0043] 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.

[0044] Fluorinated copolymers may or may not have functional groups. Functional groups can be located at the ends of the main chain or side chains of the fluorinated copolymer, or they can be located in the main chain or side chains. Typical functional groups are -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH.

[0045] 10 of fluorinated copolymers 6The number of functional groups per carbon atom in the main chain is preferably 90 or less, more preferably 70 or less, further 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 molded articles such as wire coatings that are difficult to dissolve fluoride ions in reagents such as hydrogen peroxide water.

[0046] The number of functional groups in a fluorinated copolymer is the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH.

[0047] 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, further preferably 30 or less, even more preferably 20 or less, particularly preferably less than 15, and most preferably less than 10.

[0048] 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, particularly more preferably 30 or less, particularly preferably 20 or less, and most preferably less than 15.

[0049] 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.

[0050] 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.

[0051] N = I × K / t(A)

[0052] I: Absorbance

[0053] K: Correction coefficient

[0054] t: Membrane thickness (mm)

[0055] 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.

[0056] [Table 1]

[0057] Table 1

[0058]

[0059] 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 ).

[0060] 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 determined. -1 The total number of functional groups obtained from the absorption peak at the given location.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The melting point of the fluorinated copolymer is preferably 260–290°C, more preferably 269–288°C. With a melting point within the above range, it is easier to form a coating on the core wire, and even when in contact with a pharmaceutical agent, the coating is less prone to cracking, resulting in a coating with superior low water vapor permeability.

[0066] In this invention, the melting point can be determined using a differential scanning calorimeter (DSC).

[0067] The water vapor permeability of the fluorinated copolymer is preferably 8.0 g·cm / m. 2 The following is more preferred: 7.8 g·cm / m 2 The following measures are taken: By ensuring that the water vapor permeability is within the above-mentioned range, the penetration of water vapor and other moisture from the external gas into the wire can be minimized, thereby inhibiting the corrosion of the core wire.

[0068] The carbon dioxide permeability of the fluorinated copolymer is preferably 1260 cm⁻¹. 3 ·mm / (m 2 The fluorinated copolymer of the present invention exhibits excellent low carbon dioxide permeability due to the appropriate adjustment of the content of HFP and PPVE units and the melt flow rate.

[0069] In this invention, the carbon dioxide transmission coefficient can be determined under test conditions of 70°C and 0% RH. The specific determination of the carbon dioxide transmission coefficient can be performed using the methods described in the examples.

[0070] The amount of fluoride ions dissolved in the fluorine-containing copolymer of the present invention, as measured by mass, is preferably 7.5 ppm or less, 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, fluoride ion dissolution from the coating layer can be suppressed even when in contact with reagents.

[0071] 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.

[0072] The fluorinated copolymers and wire coatings of the present invention may include other components as needed. Examples of such other components include fillers, stabilizers, plasticizers, pigments, colorants, antioxidants, ultraviolet absorbers, flame retardants, anti-aging agents, antistatic agents, and antibacterial agents.

[0073] Among the other components mentioned above, fillers are preferred. Examples of fillers include graphite, carbon fiber, coke, silica, zinc oxide, magnesium oxide, tin oxide, antimony oxide, calcium carbonate, magnesium carbonate, glass, talc, mica, mica, aluminum nitride, calcium phosphate, sericite, diatomaceous earth, silicon nitride, fine silica, alumina, zirconium oxide, quartz powder, kaolin, bentonite, titanium dioxide, amorphous silica, carbon black, and boron nitride. The shape of the filler is not particularly limited, and examples include fibrous, needle-like, powdered, granular, and bead-like forms.

[0074] The fluorinated copolymers and wire coatings of the present invention may contain other polymers besides the aforementioned fluorinated copolymers as additional components. Examples of other polymers include fluoropolymers, fluororubbers, and non-fluorinated polymers, in addition to the aforementioned fluorinated copolymers.

[0075] Fluorinated copolymers can be manufactured using any polymerization method, such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization. In these polymerization methods, conditions such as temperature and pressure, polymerization initiators, chain transfer agents, solvents, and other additives can be appropriately set according to the desired composition and amount of the fluorinated copolymer.

[0076] Oil-soluble free radical polymerization initiators or water-soluble free radical initiators can be used as polymerization initiators.

[0077] 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:

[0078] Dialkyl percarbonate esters, such as di-n-propyl percarbonate, diisopropyl percarbonate, and disec-butyl percarbonate;

[0079] Peroxide esters such as tert-butyl peroxide isobutyrate and tert-butyl perpentyl peroxide;

[0080] Dialkyl peroxides such as di-tert-butyl peroxide;

[0081] Di[fluoro(or fluorochloro)acyl] peroxides; etc.

[0082] Examples of diacyl peroxides include those represented by [(RfCOO)-]2 (where Rf is a perfluoroalkyl, ω-hydroperfluoroalkyl, or fluorochloroalkyl).

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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 thermally stable functional groups such as -CF2H, in the fluorinated copolymer 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 easily adjusted to the range described above.

[0096] 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).

[0097] 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.

[0098] 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).

[0099] 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.

[0100] 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.

[0101] The fluorinated copolymer of the present invention or the above composition can also be molded to obtain a molded body.

[0102] 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, extrusion 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 molding the fluorinated copolymer of the present invention using injection molding, a beautiful molded article can be obtained.

[0103] As molded bodies containing the fluorinated copolymer of the present invention, they can be, for example, bushings, nuts, bolts, joints, membranes, bottles, gaskets, wire sheaths, tubes, hoses, pipes, valves, sheets, seals, gaskets, cans, rollers, containers, stopcocks, connectors, filter housings, filter covers, flow meters, pumps, wafer carriers, wafer boxes, etc.

[0104] 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.

[0105] 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;

[0106] 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;

[0107] Inner lining components for reagent containers and piping in chemical equipment and semiconductor plants;

[0108] 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.

[0109] 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.

[0110] O-rings, tubes, gaskets, valve core materials, hoses, sealing materials, rollers, washers, diaphragms, connectors and other reagent delivery components for semiconductor manufacturing equipment;

[0111] Coating and ink components for coating equipment, such as coating rollers, hoses, tubes, and ink containers;

[0112] Food and beverage conduits, hoses, belts, gaskets, connectors and other food and beverage conveying components, food packaging materials, and glass cooking equipment;

[0113] Pipes, hoses, and other components used for waste liquid transportation;

[0114] Pipes, hoses, and other components used for high-temperature liquid transfer;

[0115] Pipes, hoses and other components used in steam piping;

[0116] Corrosion-resistant tape for piping, such as tape wrapped around the deck of a ship;

[0117] 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;

[0118] The diaphragm and various sliding components such as gaskets in a diaphragm pump;

[0119] Weather-resistant covers for agricultural films, various roofing materials, and sidewalls;

[0120] Interior materials used in the construction industry, and glass-like covering materials such as non-combustible fire-resistant safety glass;

[0121] Lining materials such as laminated steel sheets used in the home appliance industry.

[0122] 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.

[0123] The stoppers and packaging films used for the aforementioned chemicals exhibit excellent 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 reagents.

[0124] Examples of such molded bodies include radiator water chambers for automobiles, reagent tanks, bellows, partitions, rollers, gasoline tanks, waste liquid conveying containers, high-temperature liquid conveying containers, and fish farming and aquaculture tanks.

[0125] 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.

[0126] The method for molding the wire coating material of the present invention is not particularly limited, and examples include injection molding, extrusion molding, compression molding, and blow molding. As a molding method, extrusion molding is more preferred because it allows for high-productivity production of the wire coating material. That is, since the wire coating material of the present invention can be produced with high productivity, it is more preferably an extruded product.

[0127] The wire sheathing material of the present invention has excellent heat resistance and low dielectric loss tangent, and is therefore suitable for use in LAN cables (Ethernet cables), high-frequency transmission cables, flat cables, heat-resistant cables, etc., and is particularly suitable for use in transmission cables such as LAN cables (Ethernet cables) and high-frequency transmission cables.

[0128] The wire of the present invention comprises a core wire and a coating layer disposed around the core wire and obtained by the aforementioned wire coating material. The coating layer of the wire of the present invention has few defects, can suppress the penetration of water vapor from the outside of the wire to a very low level, is not prone to cracking even when in contact with chemicals, and exhibits excellent shape stability, suppressing the formation of cracks during winding. Therefore, it 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.

[0129] As the material for the core wire, metallic conductor materials such as copper and aluminum can be used. 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. More preferably, the core wire diameter is 2 mm or less.

[0130] As specific examples of the aforementioned core wires, AWG-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) can be used.

[0131] 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.

[0132] 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 fluorinated copolymer of the present invention can be suitable as insulating sheaths containing the fluorinated copolymer. 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.

[0133] The coating may contain air bubbles, which are preferably evenly distributed in the coating.

[0134] 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.

[0135] 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.

[0136] 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].

[0137] The wire of the present invention can be manufactured, for example, by heating the wire coating material and, while the fluorinated copolymer contained in the wire coating material is molten, extruding it onto the core wire using an extruder to form the coating layer.

[0138] In manufacturing the wire of the present invention, the wire coating material can be heated, and while the fluorinated copolymer contained in the wire coating material is molten, a gas is introduced into the fluorinated copolymer to form the coating layer containing the aforementioned bubbles. Examples of gases that can be used include dichlorofluoromethane, nitrogen, carbon dioxide, or mixtures thereof. The gas can be introduced into the heated wire coating material as a pressurized gas, or it can be generated by mixing a chemical foaming agent into the wire coating material. The gas dissolves in the molten fluorinated copolymer contained in the heated wire coating material.

[0139] The embodiments have been described above, but it is understood that various changes can be made to the methods and details without departing from the spirit and scope of the claims.

[0140] Example

[0141] Next, embodiments will be given to illustrate the implementation of the present invention, but the present invention is not limited to the embodiments described herein.

[0142] The values ​​in the examples were measured using the following methods.

[0143] 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).

[0144] (Quantity of -CF2H)

[0145] 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.

[0146] (The number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2)

[0147] 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.

[0148] N = I × K / t(A)

[0149] I: Absorbance

[0150] K: Correction coefficient

[0151] t: Membrane thickness (mm)

[0152] 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.

[0153] [Table 2]

[0154] Table 2

[0155]

[0156] (Mel flow rate (MFR))

[0157] 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.

[0158] (Melting point)

[0159] 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.

[0160] Example 1

[0161] 40.25 kg of deionized water and 0.603 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 1.17 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 0.970 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 0.970 MPa, and this pressure was maintained by continuously adding TFE. 0.603 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.

[0162] 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, 0.603 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 43.7 kg of dry powder.

[0163] 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.

[0164] 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 Manufacturing 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 once 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 the granules. Various physical properties of the obtained granules were measured using the above method. The results are shown in Table 3.

[0165] Example 2

[0166] The amount of methanol added before polymerization was changed to 0.570 kg, and the amount of methanol added separately after polymerization started was also changed to 0.570 kg each time. The amount of PPVE added before polymerization was changed to 1.09 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 0.948 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.

[0167] 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.

[0168] Example 3

[0169] The amount of methanol added before polymerization was changed to 0.685 kg, and the amount of methanol added separately after polymerization started was also changed to 0.685 kg each time. The amount of PPVE added before polymerization was changed to 1.17 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.19 kg each time. 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 method described above. The results are shown in Table 3.

[0170] The obtained granules were fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0171] Example 4

[0172] The amount of methanol added before polymerization was changed to 0.727 kg, and the amount of methanol added separately after polymerization started was also changed to 0.727 kg each time. The amount of PPVE added before polymerization was changed to 1.65 kg, and the amount of PPVE added separately after polymerization started was also changed to 0.27 kg each time. 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 fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0174] Example 5

[0175] The amount of methanol added before polymerization was changed to 0.647 kg, and the amount of methanol added separately after polymerization started was also changed to 0.647 kg each time. The amount of PPVE added before polymerization was changed to 1.09 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 0.948 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents were determined using the obtained granules according to the above method. The results are shown in Table 3.

[0176] The obtained granules were fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0177] Example 6

[0178] The amount of methanol added before polymerization was changed to 0.612 kg, and the amount of methanol added separately after polymerization started was also changed to 0.612 kg each time. The amount of PPVE added before polymerization was changed to 1.19 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 0.924 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.

[0179] Example 7

[0180] The amount of methanol added before polymerization was changed to 0.555 kg, and the amount of methanol added separately after polymerization started was also changed to 0.555 kg each time. The amount of PPVE added before polymerization was changed to 0.95 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 0.906 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents were determined using the obtained granules according to the above method. The results are shown in Table 3.

[0181] The obtained granules were fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0182] Comparative Example 1

[0183] The amount of methanol added before polymerization was changed to 0.754 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.754 kg each time. The amount of PPVE added before polymerization was changed to 2.26 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.32 kg each time. The internal temperature of the autoclave at the start of polymerization was changed to 25.0°C, and the set pressure inside the autoclave before and after polymerization was changed to 0.999 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 methods described above. The results are shown in Table 3.

[0184] Comparative Example 2

[0185] The amount of methanol added before polymerization was changed to 0.813 kg, and the amount of methanol added in batches after polymerization began was changed to 0.754 kg each time. The amount of PPVE added before polymerization was changed to 1.29 kg, and the amount of PPVE added in batches after polymerization began was changed to 0.19 kg each time. The internal temperature of the autoclave at the start of polymerization was changed to 25.0°C, and the set pressure inside the autoclave before and after polymerization was changed to 0.990 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 methods. The results are shown in Table 3.

[0186] Comparative Example 3

[0187] The amount of methanol added before polymerization was changed to 0.546 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.546 kg each time. The amount of PPVE added before polymerization was changed to 0.73 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.14 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.906 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 methods described above. The results are shown in Table 3.

[0188] Comparative Example 4

[0189] The amount of methanol added before polymerization was changed to 0.374 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.374 kg each time. The amount of PPVE added before polymerization was changed to 1.54 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.29 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.924 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.

[0190] Comparative Example 5

[0191] The amount of methanol added before polymerization was changed to 0.769 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.769 kg each time. The amount of PPVE added before polymerization was changed to 1.28 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.948 MPa. Otherwise, copolymer granules were obtained in the same manner as in Example 1. The HFP and PPVE contents were determined using the obtained granules according to the above method. The results are shown in Table 3.

[0192] The obtained granules were fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0193] Comparative Example 6

[0194] The amount of methanol added before polymerization was changed to 0.411 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.411 kg each time. The amount of PPVE added before polymerization was changed to 0.96 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.22 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.866 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.

[0195] The obtained granules were fluorinated in the same manner as in Example 1. Using the obtained granules, various physical properties were determined by the methods described above. The results are shown in Table 3.

[0196] Comparative Example 7

[0197] 945g of deionized water and 13.7g of methanol were added to a 4L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen under vacuum. Then, the autoclave was degassed under vacuum, and 945g of HFP and 27.8g of PEVE were added. The autoclave was then heated to 25.5°C. Next, TFE was added until the internal pressure of the autoclave reached 0.927MPa. Then, 29.4g 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 0.927MPa, and this pressure was maintained by continuously adding TFE. 13.7g of methanol was added 1.5 hours after the start of polymerization. Two hours after the start of polymerization, 29.4 g of DHP was added, and four hours later, with the internal pressure reduced by 0.002 MPa. Six hours later, 22.6 g of DHP was added, with the internal pressure reduced by 0.002 MPa each time. Thereafter, 6.0 g of DHP was added every two hours until the reaction was complete, with the internal pressure reduced by 0.002 MPa each time.

[0198] It should be noted that 5.2g of PPVE was added at the points where TFE was continuously added to 190g and 380g, respectively. Additionally, 13.7g 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 501g of dry powder.

[0199] 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.

[0200] 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 once 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 the granules. Various physical properties of the obtained granules were determined using the above method. The results are shown in Table 3.

[0201] [Table 3]

[0202] Table 3

[0203]

[0204] 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.

[0205] Next, the obtained granules were used to evaluate the following properties. The results are shown in Table 4.

[0206] (Abrasion test)

[0207] Using a granulation and hot-press molding machine, sheet-like 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 125°C, load 500 g, abrasion wheel CS-10 (ground 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 4000 revolutions, and the weight of the test piece was measured again. The abrasion amount was calculated using the following formula.

[0208] Wear amount (mg) = M1 - M2

[0209] M1: Weight of the test piece after 1000 revolutions (mg)

[0210] M2: Weight of the test piece (mg) after 4000 revolutions.

[0211] (Water vapor transmission rate)

[0212] Using granulation and a thermoforming machine, sheet-like test pieces with a thickness of approximately 0.2 mm were prepared. These were then placed in a test cup (with a transparency area of ​​12.56 cm²). 2 Place 18g of water inside a container, cover it with a sheet-like test piece, and secure it tightly with a PTFE gasket. Allow the sheet-like test piece to remain in contact with the water. After maintaining this temperature at 95℃ for 30 days, remove it and allow it to stand at room temperature for 2 hours to measure the mass loss. Measure the water vapor transmission rate (g·cm / m) using the following formula. 2 ).

[0213] Water vapor transmission rate (g·cm / m) 2 = Mass reduction (g) × Thickness of sheet test piece (cm) / Transmitting area (m²) 2 )

[0214] (Carbon dioxide permeability coefficient)

[0215] Using granulation and a hot press molding machine, sheet-like test pieces with a thickness of approximately 0.1 mm were prepared. Using the obtained test pieces, the carbon dioxide transmittance was measured using a differential pressure gas permeability meter (L100-5000 type gas permeability meter, manufactured by Systech Illinois) according to the method described in JIS K7126-1:2006. The permeability was measured at a permeability area of ​​50.24 cm². 2 The carbon dioxide transmittance was obtained under test conditions of 70℃ and 0%RH. Using the obtained carbon dioxide transmittance and the thickness of the test piece, the carbon dioxide transmittance coefficient was calculated using the following formula.

[0216] Carbon dioxide permeability (cm) 3 ·mm / (m 2 ·24h·atm))=GTR×d

[0217] GTR: Carbon dioxide transmittance (cm) 3 / (m 2 ·24h·atm))

[0218] d: Thickness of the test piece (mm)

[0219] (Creep Resistance Evaluation)

[0220] Creep resistance was determined according to the methods described in ASTM D395 or JISK 6262:2013. A 13mm outer diameter and 8mm height molded body was prepared using granulation and a hot press. Test pieces with an outer diameter of 13mm and a height of 6mm were fabricated from the molded body by cutting. The test pieces were compressed at room temperature to a compression set of 25% using a compression device. The compressed test pieces were then placed in an electric furnace at 40°C for 72 hours while still attached to the compression device. After removing the compression device from the furnace and cooling to room temperature, the test pieces were removed. The recovered test pieces were left at room temperature for 30 minutes, and their height was measured. The recovery ratio was calculated using the following formula.

[0221] Recovery rate (%) = (t2-t1) / t3 × 100

[0222] t1: Height of the spacer (mm)

[0223] t2: Height of the test piece removed from the compression device (mm)

[0224] t3: Height of compression deformation (mm)

[0225] In the above experiment, t1 = 4.5 mm and t3 = 1.5 mm.

[0226] (Tensile strength after 60,000 cycles)

[0227] Tensile strength after 60,000 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 tensile tests were repeatedly performed with 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 stretch.

[0228] The sheet with high tensile strength after 60,000 cycles maintains high tensile strength even after being subjected to 60,000 loads, and has excellent durability under repeated loads (110°C).

[0229] (Wire Covering Test)

[0230] use A wire coating molding machine (manufactured by Tanabe Plastics Machinery Co., Ltd.) extrudes a fluorinated copolymer onto a copper conductor with a conductor diameter of 0.50 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 0.50mm

[0232] b) Coating thickness: 0.20mm

[0233] c) Diameter of the covered wire: 0.90mm

[0234] d) Wire pulling speed: 70m / min

[0235] e) Extrusion conditions:

[0236] • Single-screw extrusion molding machine with a barrel shaft diameter of 30mm and an L / D ratio of 22

[0237] • Die head (inner diameter) / piece (outer diameter) = 9.0mm / 5.0mm

[0238] Extruder set temperatures: Barrel section C-1 (320℃), Barrel section C-2 (350℃), Barrel section C-3 (370℃), Head H (380℃), Die head D-1 (380℃), Die head D-2 (380℃). Core wire preheating is set to 80℃.

[0239] (Crack test)

[0240] Ten 20cm long wires were cut from the obtained coated wires to serve as test pieces for the winding crack test. The test pieces were then heat-treated at 180°C for 96 hours while remaining straight.

[0241] Remove the test piece and allow it to cool at room temperature. Then, wind the test piece onto a wire of the same diameter as the test piece. Heat the resulting sample again at 180°C for 1 hour. Remove the sample and allow it to cool at room temperature. Unwind the wire and, using a visual inspection and magnifying glass, count the number of cracked wires. A single crack in any wire is considered a crack. Mark fewer than one cracked wire out of ten as ○, and more than two cracked wires as ×.

[0242] In addition, in Comparative Example 4, when the coated wire was obtained, the cone fracture became significant, and the desired coating thickness could not be obtained, making it impossible to obtain a wire that could be tested.

[0243] (Number of sparks)

[0244] A spark tester (DENSOK HIGH FREQ SPARK TESTER) is installed online on the wire coating production line to evaluate the presence of defects in the wire coating at 1500V. The process is repeated for 1 hour, and the number of sparks is counted.

[0245] It should be noted that in Comparative Example 4, the cone fracture became significant when the coated wire was obtained, making it impossible to obtain a wire with the desired coating thickness and thus, a testable wire. Furthermore, Comparative Example 5 yielded a very high number of sparks.

[0246] (Injection molding)

[0247] ·condition

[0248] Using an injection molding machine (Sumitomo Heavy Industries, SE50EV-A), the barrel temperature was set to 385°C, the mold temperature to 180°C, and the injection speed to 20 mm / s. A Cr-plated mold (100 mm × 100 mm × 2.0 mm, film gate, flow length 100 mm from the gate) was used for HPM38. The resulting injection-molded body was observed and evaluated according to the following criteria: Visual inspection was performed to check for any cloudiness. The presence or absence of surface roughness was confirmed by contacting the surface of the injection-molded body.

[0249] 3: The injection-molded part is transparent throughout and has a smooth surface.

[0250] 2: A white opacity was observed within 1 cm of the gate of the mold, and the surface was generally smooth.

[0251] 1. A white opacity was observed within 1 cm of the gate location on the mold, and a rough surface was confirmed within 1 cm of the gate location on the mold surface.

[0252] 0: The copolymer was not fully filled into the mold, and the desired molded shape could not be obtained.

[0253] In Comparative Example 5, burrs were observed in the obtained injection molded article, making it unsuitable for direct use as a molded article.

[0254] (Membrane forming properties)

[0255] use An extruder (manufactured by Imoto Manufacturing Co., Ltd.) and a T-die are used to shape the granules into a film. The extrusion molding conditions are as follows.

[0256] a) Winding speed: 1m / minute

[0257] b) Roller temperature: 120℃

[0258] c) Membrane width: 70mm

[0259] d) Thickness: 0.10mm

[0260] e) Extrusion conditions:

[0261] • Single-screw extruder with a barrel diameter of 14mm and an L / D ratio of 20

[0262] Extruder set temperatures: Barrel section C-1 (330℃), Barrel section C-2 (350℃), Barrel section C-3 (365℃), T-die head (370℃)

[0263] The extrusion molding of the fluorinated copolymer was continued until the fluorinated copolymer was stably extruded from the molding machine. Next, a film with a length of 11 m or more (70 mm wide) was produced by extruding the fluorinated copolymer to a thickness of 0.10 mm. A 10-11 m section was cut from the end of the obtained film to prepare a test piece (1 m long, 70 mm wide) for measuring thickness variation. The thickness was measured at three locations: the center point in the width direction at the end of the film and two locations 25 mm away from that center point in the width direction. Furthermore, the thickness was measured at nine locations: three center points spaced 25 cm apart from the center point at one end of the film towards the other end, and two locations 25 mm away from each center point in the width direction. Of the total 12 measurements, one or fewer measurements outside the ±10% range of 0.10 mm were recorded as 0, and two or more measurements outside the ±10% range of 0.10 mm were recorded as ×.

[0264] (Crack test due to chemical impregnation)

[0265] Approximately 50g of the above-mentioned granules were placed into a mold (120mm inner diameter, 38mm height). Under this condition, the material was heated to 360°C for 20 minutes using a hot plate press, followed by water cooling while applying pressure of 1MPa to produce a molded body approximately 2mm thick. A rectangular dumbbell (13.5mm × 38mm) was used to punch the resulting sheet, yielding three test pieces. A notch was made at the center of the long side of each test piece according to ASTM D1693 using a 19mm × 0.45mm blade. The three notched test pieces and 25g of 40% (w / w) tetrabutylammonium hydroxide aqueous solution were placed in a 100mL PP bottle. The bottle was heated at 100°C for 20 hours, and the notched test pieces were removed. The three notched test pieces were then mounted in a stress cracking test fixture according to ASTM D1693. The notches and their surrounding area were visually observed, and the number of cracks was counted.

[0266] ○: The number of cracks is 0

[0267] ×: The number of cracks is more than 1.

[0268] (Immersion test in hydrogen peroxide water)

[0269] 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.

[0270] Dissolved fluoride ion concentration (ppm) = Measured value (ppm) × Volume of hydrogen peroxide aqueous solution (g) / Weight of test piece (g)

[0271]

Claims

1. A fluorinated copolymer comprising tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein, The content of hexafluoropropylene units is 5.0–7.0% by mass relative to all monomer units, and the content of perfluoro(propyl vinyl ether) units is 1.5%–2.6% by mass relative to all monomer units. The content of tetrafluoroethylene units relative to all monomer units is 90.4%–93.5% by mass. The melt flow rate at a load of 5 kg and a temperature of 372 °C is 9 g / 10 min to 40 g / 10 min.

2. The fluorinated copolymer as described in claim 1, wherein, The content of hexafluoropropylene units is 5.2% to 6.8% by mass relative to all monomer units.

3. The fluorinated copolymer as described in claim 1 or 2, wherein, The content of perfluoro(propyl vinyl ether) units is 1.7% to 2.4% by mass relative to all monomer units.

4. The fluorinated copolymer as described in claim 1 or 2, wherein, The melt flow rate at a load of 5 kg and a temperature of 372 °C is 11 g / 10 min to 38 g / 10 min.

5. The fluorinated copolymer as described in claim 1 or 2, wherein, Every 10 6 The number of main chain carbon atoms and the number of functional groups -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2 and -CH2OH are less than 90.

6. An injection-molded article comprising any one of claims 1 to 5.

7. A wire sheathing material comprising any one of claims 1 to 5.

8. An electrical wire having a core wire and a sheath, the sheath being disposed around the core wire and obtained from an electrical wire sheath material containing a fluorinated copolymer according to any one of claims 1 to 5.

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