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 9.4 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 15 to 40 g / 10 minutes.

Description

TECHNICAL FIELD

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

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

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 52-109588 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 form a coating layer having a uniform thickness on a small-diameter core wire by an extrusion molding method, and which can obtain a molded body which is not easily cracked even when in contact with a medicine, has a very excellent low water vapor permeability, has an excellent 140°C wear resistance, has a high rigidity at 100°C, and has an excellent durability to repeated loads.

[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 tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein the content of the hexafluoropropylene units is 7.0% by mass to 9.4% by mass with respect to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5% by mass to 2.9% by mass with respect to the total monomer units, and the melt flow rate at 372°C is 15 g / 10 minutes to 40 g / 10 minutes.

[0010] The content of the hexafluoropropylene units with respect to the total monomer units is preferably 7.2% by mass to 9.2% by mass.

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

[0012] The melt flow rate at 372°C is preferably 15 g / 10 minutes to 40 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 flowmeter member or a pipe member.

[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, which can form a coating layer having a uniform thickness on a small-diameter core wire by an extrusion molding method, and which can obtain a molded body which is not easily cracked even when in contact with a medicine, has a very excellent low water vapor permeability, has an excellent 140°C wear resistance, has an excellent rigidity at 100°C, and has an excellent durability to repeated loads. 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] As fluorine resins, non-melt-processable fluorine resins such as polytetrafluoroethylene (PTFE) and melt-processable fluorine resins are known. PTFE has excellent properties, but has a disadvantage that melt processing is extremely difficult. On the other hand, as melt-processable fluorine resins, TFE / HFP copolymers (FEP), TFE / PPVE copolymers (PFA), and the like are known, but have a disadvantage that the heat resistance and the like are inferior to PTFE. Therefore, in Patent Document 1, the above-mentioned terpolymer is proposed as a fluorocarbon polymer in which these disadvantages are improved.

[0022] However, there is a demand for a fluorine-containing copolymer having excellent wear resistance at 140°C, rigidity at high temperature of 100°C, and durability against repeated load, as compared with conventional terpolymers. For example, for a flowmeter member for measuring the flow rate of a medicinal liquid and a pipe member for transporting a medicinal liquid, water vapor low permeability is required so that moisture does not mix into the medicinal liquid. Furthermore, the pressure of the medicinal liquid by the flowmeter and the pipe frequently changes at the time of start of supply of the medicinal liquid, at the time of stop of supply of the medicinal liquid, at the time of change of the supply pressure of the medicinal liquid, and the like. When a medicinal liquid of high pressure or a medicinal liquid of high temperature is circulated, the medicinal liquid of high pressure or the medicinal liquid of high temperature passes through the flowmeter and the pipe. Therefore, for the material constituting the flowmeter member and the pipe member, a fluorine-containing copolymer having low water vapor permeability, which is not easily subjected to wear and deformation caused by the medicinal liquid of high pressure, and which is not easily subjected to cracking even when in contact with the medicinal liquid of high temperature, is required. Furthermore, in the pipe member and the flowmeter member, there are members having a thin wall portion, and therefore a fluorine-containing copolymer capable of providing a beautiful molded body having a thin wall portion is required.

[0023] It was found that by adjusting the contents of the HFP unit and the PPVE unit of the fluorine-containing copolymer containing TFE units, HFP units, and PPVE units, and the melt flow rate to extremely limited ranges, the moldability of the fluorine-containing copolymer is improved, and a molded body having excellent water vapor low permeability, wear resistance at 140°C, rigidity at high temperature of 100°C, and durability against repeated load, which is not easily subjected to cracking even when in contact with a medicinal liquid, can be obtained.

[0024] Furthermore, by molding the fluorine-containing copolymer of the present application by an extrusion molding method, a coating layer having a uniform thickness can be formed on a core wire having a small diameter. In this way, the fluorine-containing copolymer of the present application can be used not only as a material for a flowmeter member and a pipe member, but also for a wide variety of uses such as wire coating.

[0025] 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 an extruder and an injection molding machine.

[0026] The content of the HFP unit of the fluorine-containing copolymer is preferably 7.0 to 9.4% by mass, more preferably 7.1% by mass or more, further preferably 7.2% by mass or more, still further preferably 7.5% by mass or more, preferably 9.3% by mass or less, more preferably 9.2% by mass or less, further preferably 9.0% by mass, still further preferably 8.7% by mass or less, particularly preferably 8.5% by mass or less, especially preferably 8.3% by mass or less, most preferably 8.1% by mass or less, relative to the total monomer units. If the content of the HFP unit is too large, the permeation of water vapor cannot be sufficiently suppressed, the rigidity at 100°C is poor, and the durability to repeated load is poor, and if the content of the HFP unit is too small, the generation of cracks upon contact with a pharmaceutical agent cannot be sufficiently suppressed, and a molded body excellent in wear resistance at 140°C cannot be obtained.

[0027] 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, still further preferably 1.8% by mass or more, particularly preferably 1.9% by mass or more, most preferably 2.0% by mass or more, preferably 2.8% by mass or less, more preferably 2.7% by mass or less, further preferably 2.6% by mass or less, still further preferably 2.5% by mass or less, particularly preferably 2.4% by mass or less, most preferably 2.2% by mass or less, relative to the total monomer units. By setting the content of the PPVE unit of the fluorine-containing copolymer within the above range, a molded body excellent in the generation of cracks even upon contact with a pharmaceutical agent, low permeation of water vapor, wear resistance at 140°C, rigidity at 100°C, and durability to repeated load can be obtained. If the content of the PPVE unit is too small, the generation of cracks upon contact with a pharmaceutical agent cannot be sufficiently suppressed, and a molded body excellent in wear resistance at 140°C cannot be obtained.

[0028] The content of the TFE unit of the fluorine-containing copolymer is preferably 87.7 to 91.5% by mass, more preferably 87.8% by mass or more, further preferably 88.0% by mass or more, still further preferably 88.3% by mass or more, particularly preferably 88.4% by mass or more, most preferably 88.6% by mass or more, more preferably 91.4% by mass or less, further preferably 91.1% by mass or less, still further preferably 98.8% by mass or less, particularly preferably 98.5% by mass or less, relative to the total monomer units. In addition, 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 other monomer units is 100% by mass.

[0029] The fluorine-containing copolymer of the present application can contain only the above three monomer units, or can contain the above three monomer units and other monomer units.

[0030] As the other monomer, there is no particular limitation as long as it is a monomer capable of copolymerizing with TFE, HFP and PPVE, and it can be a fluorine-containing monomer or a non-fluorine-containing monomer.

[0031] As the fluorine-containing monomer, it is preferable to be at least one selected from the group consisting of trifluorochloroethylene, fluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoroisobutene, CH2=CZ 1 (CF2) n Z 2 (in the formula, Z 1 is H or F, Z 2 is H, F or Cl, and n is an integer of 1 to 10), a perfluoro(alkyl vinyl ether) [PAVE] represented by CF2=CF-ORf 1 (in the formula, Rf 1 is a perfluoroalkyl group having 1 to 8 carbon atoms), an alkyl perfluoro vinyl ether derivative represented by CF2=CF-O-CH2-Rf 2 (in the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms), perfluoro-2,2-dimethyl-1,3-dioxolene [PDD], and perfluoro-2-methylene-4-methyl-1,3-dioxolane [PMD].

[0032] As the monomer represented by CH2=CZ 1 (CF2) n Z 2 , CH2=CH-C4F9, CH2=CH-C6F 13 , CH2=CF-C3F6H, and the like can be given.

[0033] As the perfluoro(alkyl vinyl ether) represented by CF2=CF-ORf 1 , CF2=CF-OCF2CF3, and the like can be given.

[0034] As the non-fluorine-containing monomer, a hydrocarbon-based monomer capable of copolymerizing with TFE, HFP and PPVE can be mentioned. As the hydrocarbon-based monomer, for example, olefins such as ethylene, propylene, butylene, isobutylene and the like; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether and the like; vinyl esters such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pentanoate, vinyl pivalate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl p-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl glycolate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxypentanoate, vinyl hydroxyisobutyrate, vinyl hydroxycyclohexanecarboxylate and the like; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether and the like; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, cyclohexyl allyl ester and the like can be mentioned.

[0035] As the non-fluorine-containing monomer, a hydrocarbon-based monomer capable of copolymerizing with TFE, HFP and PPVE can be mentioned. As the hydrocarbon-based monomer, for example, olefins such as ethylene, propylene, butylene, isobutylene and the like; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether and the like; vinyl esters such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pentanoate, vinyl pivalate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl p-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl glycolate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxypentanoate, vinyl hydroxyisobutyrate, vinyl hydroxycyclohexanecarboxylate and the like; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether and the like; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, cyclohexyl allyl ester and the like can be mentioned.

[0036] The content of the other monomer unit in the fluorine-containing copolymer of the present application is preferably 0 to 3.8 mass% relative to the total monomer units, more preferably 1.0 mass% or less, further preferably 0.5 mass% or less, particularly preferably 0.1 mass% or less.

[0037] The melt flow rate (MFR) of the fluorine-containing copolymer is preferably 15 g / 10 minutes or more, more preferably 15.1 g / 10 minutes or more, further preferably 16 g / 10 minutes or more, still further preferably 17 g / 10 minutes or more, yet further preferably 18 g / 10 minutes or more, especially further preferably 19 g / 10 minutes or more, particularly preferably 20 g / 10 minutes or more, most preferably 24 g / 10 minutes or more, preferably 39.9 g / 10 minutes or less, more preferably 39 g / 10 minutes or less, further preferably 38 g / 10 minutes or less, still further preferably 34 g / 10 minutes or less, yet further preferably 33 g / 10 minutes or less, especially further preferably 32 g / 10 minutes or less, particularly especially preferably 30 g / 10 minutes or less, most preferably 28 g / 10 minutes or less. By setting the MFR of the fluorine-containing copolymer within the above range, the moldability of the copolymer is improved, and even in the case of contact with a pharmaceutical agent, cracking is less likely to occur, and a molded article excellent in 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load can be obtained. If the MFR is too low, a molded article excellent in water vapor low permeability and rigidity at 100°C high temperature cannot be obtained. If the MFR is too high, cracking upon contact with a pharmaceutical agent is not sufficiently suppressed, and a molded article excellent in 140°C wear resistance is also difficult to obtain.

[0038] In the present application, the melt flow rate is a value obtained by using a melt flow indexer G-01 (manufactured by Toyo Seiki Kenki K.K.) as the mass (g / 10 minutes) of polymer flowing per 10 minutes from a die having an inner diameter of 2 mm and a length of 8 mm under a load of 5 kg at 372°C in accordance with ASTM D-1238.

[0039] The MFR can be adjusted by adjusting the kind and amount of polymerization initiator used when polymerizing the monomers, the kind and amount of chain transfer agent, and the like.

[0040] The fluorine-containing copolymer of the present application can have a functional group or can not have a functional group. The functional group is a functional group present at the end of the main chain or the end of the side chain of the fluorine-containing copolymer, and a functional group present in the main chain or the side chain. Typical functional groups are -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH.

[0041] The number of functional groups per 10 6 main chain carbon atoms of the fluorine-containing copolymer is preferably 90 or less, more preferably 70 or less, further preferably 50 or less, still further preferably 40 or less, especially preferably 30 or less, particularly preferably 20 or less, most preferably less than 15. By setting the number of functional groups of the fluorine-containing copolymer within the above range, a molded article in which fluorine ions are less likely to be eluted into a pharmaceutical liquid such as hydrogen peroxide water can be obtained.

[0042] The total number of the functional groups of the fluorine-containing copolymer is the total number of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH.

[0043] The number of -CF2H per 10 6 main chain carbon atoms of the fluorine-containing copolymer is preferably 50 or less, more preferably 40 or less, further preferably 30 or less, still further preferably 20 or less, particularly preferably less than 15, and most preferably 10 or less.

[0044] The total number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2 per 10 6 main chain carbon atoms of the fluorine-containing copolymer is preferably 80 or less, more preferably 70 or less, further preferably 50 or less, still further preferably 40 or less, particularly preferably 30 or less, and most preferably 20 or less.

[0045] The kind of the above-mentioned functional group and the number of the functional group can be identified by infrared spectroscopy.

[0046] As for the number of the functional group, specifically, the following method is used for the measurement. First, the above-mentioned fluorine-containing copolymer is cold-pressed to produce a film having a thickness of 0.25 mm to 0.30 mm. The film is analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum of the above-mentioned fluorine-containing copolymer and a differential spectrum from a background spectrum of a completely fluorinated sample having no functional group. The number of the functional group per 1 x 10 6 carbon atoms in the above-mentioned fluorine-containing copolymer N is calculated from the absorption peak of the specific functional group appearing in the differential spectrum according to the following formula (A).

[0047] N = I x K / t (A)

[0048] I: absorbance

[0049] K: correction factor

[0050] t: thickness of the film (mm)

[0051] For reference, as for some of the functional groups, the absorption frequency, molar absorption coefficient, and correction factor are shown in Table 1. In addition, the molar absorption coefficient is determined from the FT-IR measurement data of a low molecular model compound.

[0052] [Table 1]

[0053] Table 1

[0054]

[0055] 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 ).

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] The melting point of the fluorinated copolymer is preferably 240°C to 285°C, more preferably 252°C to 273°C. By keeping the melting point within the above range, the moldability of the copolymer is further improved, and it is less prone to cracking even when in contact with the agent. This results in a molded body with low water vapor permeability, abrasion resistance at 140°C, rigidity at 100°C, and superior durability under repeated loads.

[0062] In the present application, the melting point can be measured using a differential scanning calorimeter [DSC].

[0063] The water vapor permeability of the fluorine-containing copolymer of the present application is preferably 9.5 g-cm / m 2 More preferably, the water vapor permeability is 9.0 g-cm / m 2 By setting the water vapor permeability within the above range, in the case where the fluorine-containing copolymer of the present application is used to obtain a molded article such as a pipe, a joint, a flowmeter main body, a bottle, etc., the permeation of water vapor and the like in the external gas into the interior of the molded article can be sufficiently suppressed. In addition, in the case where the fluorine-containing copolymer of the present application is used to obtain a molded article such as a gasket, a packing, etc., and is applied to a nonaqueous electrolyte battery, the permeation of water vapor from the outside into the nonaqueous electrolyte battery can be suppressed, and the deterioration and shortening of the life of the nonaqueous electrolyte battery can be suppressed.

[0064] The amount of eluted fluorine ions detected in the immersion test in hydrogen peroxide water of the fluorine-containing copolymer of the present application is preferably 4.0 ppm or less, more preferably 3.0 ppm or less, and further preferably 2.8 ppm or less on a mass basis. By setting the amount of eluted fluorine ions within the above range, in the case where the fluorine-containing copolymer of the present application is used to obtain a molded article, a pipe member used in the delivery of a medical liquid, a flowmeter main body having a medical liquid flow path in a flowmeter, a sealing member that comes into contact with a medical liquid, etc., the elution of fluorine ions into a medical liquid can be suppressed.

[0065] In the present application, the immersion test in hydrogen peroxide water can be performed as follows: using the fluorine-containing copolymer, a test piece having a weight corresponding to that of 10 pieces of molded articles (15 mm x 15 mm x 0.2 mm) is prepared, and a polypropylene-made bottle in which the test piece and 15 g of a 3 mass% hydrogen peroxide water solution are placed is placed in a constant-temperature bath at 95°C and left for 20 hours.

[0066] The fluorine-containing copolymer of the present application can be produced by any one of bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. In these polymerization methods, the conditions such as temperature, pressure, etc., a polymerization initiator, a chain transfer agent, a solvent, other additives can be appropriately set according to the composition, amount, etc. of the fluorine-containing copolymer desired.

[0067] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical initiator can be used.

[0068] As the oil-soluble radical polymerization initiator, a publicly known oil-soluble peroxide can be used, and, for example, the following substances can be mentioned as representative examples:

[0069] dialkyl peroxides such as di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, etc.;

[0070] tert-butyl peroxy isobutyrate, tert-butyl peroxy pivalate, and the like;

[0071] dialkyl peroxides such as di-tert-butyl peroxide;

[0072] di[fluoro (or fluoro-chloro) acyl] peroxides; and the like.

[0073] As the di[fluoro (or fluoro-chloro) acyl] peroxides, diacyl peroxides represented by [(RfCOO)-]2 (Rf is a perfluoroalkyl group, an ω-hydroperfluoroalkyl group, or a fluoro-chloroalkyl group) can be given.

[0074] As the di[fluoro (or fluoro-chloro) acyl] peroxides, for example, di(ω-hydro-dodecafluoroheptyl) peroxide, di(ω-hydro-tetradecafluoroheptyl) peroxide, di(ω-hydro-hexadecafluorononyl) 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-decafluorocaproyl) peroxide, di(ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptyl-ω-hydrohexadecafluorononyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorocaproyl-peroxide, ω-hydro-dodecafluoroheptyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutyryl) peroxide, di(trichlorooctafluorocaproyl) peroxide, di(tetrachloro-undecafluorooctanoyl) peroxide, di(pentachlorotetradecafluorodecanoyl) peroxide, di(undecachlorotriacontadecafluorodocosanoyl) peroxide, and the like can be given.

[0075] As the water-soluble radical polymerization initiator, a publicly known water-soluble peroxide can be used, and for example, ammonium, potassium, or sodium salts of peroxymonosulfuric acid, peroxymonoboric acid, perchloric acid, peroxymonophosphoric acid, peroxymonocarbonic acid, tert-butyl peroxy maleate, tert-butyl hydroperoxide, and the like can be given. A reducing agent such as a sulfite salt can also be contained, and the amount thereof can be 0.1 to 20 times the amount of the peroxide.

[0076] As the chain transfer agent, for example, hydrocarbons such as ethane, isopentane, n-hexane, cyclohexane; aromatic compounds such as toluene, xylene; ketones such as acetone; acetic acid esters such as ethyl acetate, butyl acetate; alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane, chloromethane; 3-fluorobenzotrifluoride; and the like can be given. The amount of addition can vary depending on the magnitude of the chain transfer constant of the compound used, and is usually used in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of the solvent.

[0077] For example, in the case where a dialkyl percarbonate, a di[fluoro (or fluoro-chloro) acyl] peroxide or the like is used as a polymerization initiator, the molecular weight of the obtained fluorine-containing copolymer becomes excessively high, and it is sometimes difficult to adjust to a desired melt flow rate, but the molecular weight can be adjusted using a chain transfer agent. It is particularly preferable to produce the fluorine-containing copolymer by suspension polymerization using a chain transfer agent such as an alcohol and an oil-soluble radical polymerization initiator.

[0078] As the solvent, water, a mixed solvent of water and an alcohol, or the like can be given. In addition, a monomer used in the polymerization of the fluorine-containing copolymer of the present application can also be used as the solvent.

[0079] In the suspension polymerization, a fluorine-based solvent can also be used in addition to water. As the fluorine-based solvent, a hydrochlorofluoroalkane such as CH3CCIF2, CH3CC12F, CF3CF2CC12H, CF2C1CF2CFHC1, and the like; a chlorofluoroalkane such as CF2C1CFCF2CF3, CF3CFCF1CF3, and the like; a perfluoroalkane such as perfluorocyclobutane, CF3CF2CF2CF3, CF3CF2CF2CF2CF3, CF3CF2CF2CF2CF2CF3, and the like; and the like can be given, of which a perfluoroalkane is preferable. The amount of the fluorine-based solvent is preferably 10 to 100 parts by mass relative to 100 parts by mass of the solvent from the aspects of the suspension property and economy.

[0080] The polymerization temperature is not particularly limited, and can be 0 to 100°C. In addition, in the case where a dialkyl percarbonate, a di[fluoro (or fluoro-chloro) acyl] peroxide or the like is used as a polymerization initiator, or in the case where the decomposition rate of the polymerization initiator is excessively fast, it is preferable to adopt a lower polymerization temperature in which the polymerization temperature is in the range of 0 to 35°C.

[0081] The polymerization pressure is appropriately determined depending on the kind of the solvent used, the amount of the solvent, the vapor pressure, other polymerization conditions such as the polymerization temperature, and the like, and can be usually 0 to 9.8 MPaG. The polymerization pressure is preferably 0.1 MPaG to 5 MPaG, more preferably 0.5 MPaG to 2 MPaG, and further preferably 0.5 MPaG to 1.5 MPaG. In addition, when the polymerization pressure is 1.5 MPaG or more, the production efficiency can be improved.

[0082] As an additive in the polymerization, a suspension stabilizer, for example, can be mentioned. As the suspension stabilizer, there is no particular limitation as long as it is a publicly known suspension stabilizer, and methylcellulose, polyvinyl alcohol, or the like can be used. If a suspension stabilizer is used, the suspension particles generated by the polymerization reaction are stably dispersed in the aqueous medium, and therefore, even if a reaction tank made of SUS, which has not been subjected to an anti-adhesion treatment such as glass lining, is used, the suspension particles are not easily adhered to the reaction tank. Therefore, a reaction tank that can withstand high pressure can be used, and thus the polymerization under high pressure can be performed, and the production efficiency can be improved. In contrast, in the case where the polymerization is performed without using a suspension stabilizer, if a reaction tank made of SUS, which has not been subjected to an anti-adhesion treatment, is used, the suspension particles can be adhered to reduce the production efficiency. The concentration of the suspension stabilizer with respect to the aqueous medium can be appropriately adjusted depending on the conditions.

[0083] In the case where the aqueous dispersion liquid containing the fluorine-containing polymer is obtained by the polymerization reaction, the dried fluorine-containing polymer can be recovered by allowing the fluorine-containing copolymer contained in the aqueous dispersion liquid to be coagulated, washed, and dried. In the case where the fluorine-containing copolymer is obtained in the form of a slurry by the polymerization reaction, the dried fluorine-containing polymer can be recovered by taking out the slurry from the reaction vessel and washing and drying. By drying, the fluorine-containing copolymer can be recovered in the form of a powder.

[0084] The fluorine-containing copolymer obtained by the polymerization can be formed into pellets. As the forming method into pellets, there is no particular limitation, and publicly known methods can be used. For example, a method in which the fluorine-containing copolymer is melt-extruded using a single-screw extruder, a twin-screw extruder, a tandem extruder, and the like, and cut into a predetermined length to be formed into pellets, and the like can be mentioned. The extrusion temperature at the time of melt-extrusion needs to be changed depending on the melt viscosity of the fluorine-containing copolymer, the production method, and the like, and is preferably the melting point of the fluorine-containing copolymer + 20°C to the melting point of the fluorine-containing copolymer + 140°C. The cutting method of the fluorine-containing copolymer is not particularly limited, and publicly known methods such as a wire-cutting method, a hot-cutting method, an underwater-cutting method, a sheet-cutting method, and the like can be adopted. The obtained pellets can also be heated to remove volatile components in the pellets (degassing treatment). The obtained pellets can also be treated by being brought into contact with warm water at 30°C to 200°C, water vapor at 100°C to 200°C, or hot air at 40°C to 200°C.

[0085] The fluorine-containing copolymer obtained by polymerization can also be heated to a temperature of 100°C or higher in the presence of air and water (wet heat treatment). As a method of the wet heat treatment, a method in which an extruder is used, and the fluorine-containing copolymer obtained by polymerization is melted and extruded while air and water are supplied can be mentioned. By the wet heat treatment, the thermally unstable functional groups of the fluorine-containing copolymer, -COF, -COOH, etc., can be converted to the relatively thermally stable -CF2H, and the total number of -COF and -COOH of the fluorine-containing copolymer, and the total number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2 can be easily adjusted to the above range. In addition to air and water, by heating the fluorine-containing copolymer in the presence of an alkali metal salt, the conversion reaction to -CF2H can be promoted. However, it should be noted that, depending on the use of the fluorine-containing copolymer, contamination by the alkali metal salt should be avoided.

[0086] The fluorine-containing copolymer obtained by polymerization can also be subjected to fluorination treatment. The fluorination treatment can be performed by bringing the fluorine-containing copolymer not subjected to the fluorination treatment into contact with a fluorine-containing compound. By the fluorination treatment, the thermally unstable functional groups of the fluorine-containing copolymer, -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, etc., and the relatively thermally stable -CF2H, etc., can be converted to the extremely thermally stable -CF3. As a result, the total number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, and -CF2H of the fluorine-containing copolymer can be easily adjusted to the above range.

[0087] As the fluorine-containing compound, there is no particular limitation, and a fluorine radical source that generates a fluorine radical under the fluorination treatment conditions can be mentioned. As the above fluorine radical source, F2gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, fluorinated halogen (e.g., IF5, CIF3), etc. can be mentioned.

[0088] The fluorine radical source such as F2gas can be used at a concentration of 100%, but from the viewpoint of safety, it is preferable to be mixed with and diluted to 5 to 50 mass% with a non-reactive gas, and more preferably to be diluted to 15 to 30 mass%. As the above non-reactive gas, nitrogen, helium, argon, etc. can be mentioned, and from the viewpoint of economy, nitrogen is preferable.

[0089] The conditions of the fluorination treatment are not particularly limited, and the fluorinated copolymer in a molten state can be brought into contact with a fluorinated compound, but generally, the treatment can be performed at a temperature below the melting point of the fluorinated copolymer, preferably at a temperature of 20°C to 220°C, more preferably at a temperature of 100°C to 200°C. The above fluorination treatment is generally performed for 1 hour to 30 hours, preferably for 5 hours to 25 hours. The fluorination treatment is preferably a treatment in which the non-fluorinated copolymer is brought into contact with fluorine gas (F2 gas).

[0090] The fluorinated copolymer of the present application can also be mixed with other components as needed to obtain a composition. As the other components, fillers, plasticizers, processing aids, release agents, pigments, flame retardants, lubricants, light stabilizers, weathering stabilizers, electrically conductive agents, antistatic agents, ultraviolet absorbers, antioxidants, blowing agents, perfumes, oils, softening agents, dehydrofluorination agents, and the like can be given.

[0091] As the fillers, for example, silica, kaolin, clay, organically modified clay, talc, mica, alumina, calcium carbonate, calcium terephthalate, titanium oxide, calcium phosphate, calcium fluoride, lithium fluoride, crosslinked polystyrene, potassium titanate, carbon, boron nitride, carbon nanotubes, glass fibers, and the like can be given. As the electrically conductive agents, carbon black and the like can be given. As the plasticizers, dioctyl phthalate, pentaerythritol, and the like can be given. As the processing aids, carnauba wax, sulfone compounds, low-molecular-weight polyethylene, fluorine-based processing aids, and the like can be given. As the dehydrofluorination agents, organo-oniums, amidines, and the like can be given.

[0092] In addition, as the above other components, other polymers other than the above fluorinated copolymer can also be used. As the other polymers, fluororesins other than the above fluorinated copolymer, fluororubbers, non-fluorinated polymers, and the like can be given.

[0093] As the method for producing the above composition, a method in which the fluorinated copolymer and the other components are mixed in a dry manner, a method in which the fluorinated copolymer and the other components are preliminarily mixed with a mixer, followed by melt-kneading with a kneader, a melt extruder, or the like, and the like can be given.

[0094] The fluorinated copolymer of the present application or the above composition can be used as a processing aid, a molding material, or the like, and is preferably used as a molding material. In addition, an aqueous dispersion, a solution, a suspension, and a copolymer / solvent system of the fluorinated copolymer of the present application can also be used, and they can be applied as a coating material, or used for encapsulation, impregnation, film casting. However, the fluorinated copolymer of the present application is preferably used as the above molding material because of the above characteristics.

[0095] The fluorinated copolymer of the present application or the above composition can also be molded to obtain a molded body.

[0096] The method of molding the above-mentioned fluorine-containing copolymer or the above-mentioned composition is not particularly limited, and injection molding, extrusion molding, compression molding, blow molding, transfer molding, rotational molding, slip-in molding, and the like can be given. Among them, extrusion molding, compression molding, injection molding, or transfer molding is preferred, and injection molding, extrusion molding, or transfer molding is more preferred because a molded body can be produced at a high productivity, and injection molding is further preferred. That is, as the molded body, extrusion molded body, compression molded body, injection molded body, or transfer molded body is preferred because it can be produced at a high productivity, and injection molded body, extrusion molded body, or transfer molded body is more preferred, and injection molded body is further preferred. By molding the fluorine-containing copolymer of the present application using injection molding, a molded body having a thin wall and a beautiful appearance can be obtained at a very high injection speed.

[0097] As the molded body containing the fluorine-containing copolymer of the present application, a nut, a bolt, a joint, a film, a bottle, a gasket, a wire covering, a tube, a hose, a pipe, a valve, a sheet, a seal, a gasket, a tank, a roll, a container, a faucet, a connector, a filter housing, a filter cover, a flow meter, a pump, a wafer carrier, a wafer cassette, and the like can be given.

[0098] The fluorine-containing copolymer of the present application, the above-mentioned composition, or the above-mentioned molded body can be used for, for example, the following uses.

[0099] a film for food packaging, a lining material for a fluid delivery line used in a food manufacturing process, a gasket, a sealing material, a sheet, and the like, a fluid delivery member for a food manufacturing device;

[0100] a plug for a chemical, a packaging film, a lining material for a fluid delivery line used in a chemical manufacturing process, a gasket, a sealing material, a sheet, and the like, a reagent delivery member;

[0101] a lining member for the inner surface of a liquid tank and a pipe for a chemical plant and a semiconductor factory;

[0102] an O-ring / tube / gasket, a valve core material, a hose, a sealing material, and the like, used in a fuel system and a peripheral device for an automobile, a hose, a sealing material, and the like, used in an AT device for an automobile, a fuel delivery member;

[0103] a flange gasket, a shaft seal, a valve stem seal, a sealing material, a hose, and the like, used in a carburetor for an engine and a peripheral device for an automobile, a brake device hose, an air conditioner hose, a radiator hose, a wire covering material, and the like, other automobile members;

[0104] an O-ring, a tube, a gasket, a valve core material, a hose, a sealing material, a roll, a gasket, a diaphragm, a joint, and the like, used as a liquid delivery member for a semiconductor manufacturing device;

[0105] Coating and ink members such as a coating roll, a hose, a tube, an ink container, and the like for a coating apparatus;

[0106] Pipe, hose, belt, gasket, joint, and the like for food and beverage delivery members, food packaging materials, and glass cooking apparatuses;

[0107] Pipe, hose, and the like for waste liquid delivery members;

[0108] Pipe, hose, and the like for high-temperature liquid delivery members;

[0109] Pipe, hose, and the like for steam piping members;

[0110] Anticorrosion tape for piping wound on a deck of a ship or the like;

[0111] Various coating materials such as a wire coating material, an optical fiber coating material, a transparent surface coating material provided on a light incident side surface of a photovoltaic element of a solar cell, and a back agent;

[0112] Diaphragm of a diaphragm pump, various gaskets, and the like;

[0113] Agricultural film, weather-resistant cover for various roof materials and side walls, and the like;

[0114] Coating materials for interior materials used in the construction field, glass-based coating materials such as non-combustible fire safety glass, and the like;

[0115] Lining materials such as laminated steel sheets used in the field of household electric appliances, and the like.

[0116] As the fuel delivery member used in the fuel system of the above-described automobile, a fuel hose, a filler hose, an evaporator hose, and the like can be further mentioned. The above-described fuel delivery member can also be used as a fuel delivery member for use in resistance to acidic gasoline, resistance to alcohol fuel, and resistance to gasoline additives such as methyl tert-butyl ether and amine.

[0117] The above-described chemical medicine plug and packaging film have excellent chemical resistance to acids and the like. In addition, as the above-described liquid medicine delivery member, an anticorrosion tape wound on a chemical device piping can be mentioned.

[0118] As the above-described shaped body, an automobile radiator tank, a liquid medicine tank, a bellows, a partition, a roller, a gasoline tank, a waste liquid delivery container, a high-temperature liquid delivery container, a fishery and fish farming tank, and the like can be further mentioned.

[0119] As the above-mentioned molded body, further, members used in bumpers, door trims, instrument panels of automobiles, food processing devices, cooking machines, water / oil repellent glass, lighting-related instruments, indicator panels and housings of OA instruments, electrically illuminated signs, display screens, liquid crystal display screens, mobile telephones, printer chassis, electrical / electronic parts, groceries, garbage cans, bathtubs, integral bathrooms, ventilation fans, lighting frames, and the like can be mentioned.

[0120] The molded body containing the fluorine-containing copolymer of the present application is less likely to be cracked even when in contact with a pharmaceutical agent, has very excellent low water vapor permeability, has excellent 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load, and thus can be suitably used for nuts, bolts, joints, gaskets, valves, cocks, connectors, filter housings, filter covers, flowmeters, pumps, and the like. Among them, it can be suitably used as a pipe member (particularly, a joint) used in the delivery of a pharmaceutical agent, and a flowmeter main body having a flow path of a pharmaceutical agent in a flowmeter. The pipe member and the flowmeter main body of the present application are less likely to be cracked even when in contact with a pharmaceutical agent, have very excellent low water vapor permeability, have excellent 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load. Thus, the pipe member and the flowmeter main body of the present application can be suitably used for the measurement of the flow rate of a pharmaceutical agent at around 100°C, and are less likely to be damaged even when repeatedly subjected to load stress according to the start of the flow of the pharmaceutical agent, the stop of the flow, and the change of the flow rate. Furthermore, the pipe member and the flowmeter main body of the present application can be manufactured at a very high injection speed even when having a thin wall portion, and have a beautiful appearance.

[0121] The molded body containing the fluorine-containing copolymer of the present application can be manufactured at a very high injection speed even when having a thin wall portion, is less likely to be cracked even when in contact with a pharmaceutical agent, has very excellent low water vapor permeability, has excellent 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load, and thus can be suitably used as a compressed member such as a gasket and a packing. The compressed member of the present application can be a gasket or a packing. The gasket or the packing of the present application can be manufactured at a low cost by an injection molding method, is less likely to be cracked even when in contact with a pharmaceutical agent, has very excellent low water vapor permeability, has excellent 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load. The compressed member of the present application has very excellent low water vapor permeability, has excellent 140°C wear resistance, rigidity at 100°C high temperature, and durability to repeated load, is less likely to be cracked even when in contact with a pharmaceutical agent, and thus can be suitably used as a pipe member for delivering a pharmaceutical agent in which water vapor and the like are not desirably mixed with external air.

[0122] The size and shape of the compressed member of the present application are appropriately set according to the use, and are not particularly limited. The shape of the compressed member of the present application can be, for example, ring-shaped. In addition, the compressed member of the present application can have a circular, elliptical, quadrangular with rounded corners, or the like shape in plan view, and can have a through hole in the center portion thereof.

[0123] The compressed member of the present application is preferably used as a member for constituting a nonaqueous electrolyte battery. The compressed member of the present application is less likely to generate cracks even when in contact with a medicament, has a very excellent water vapor low permeability, and has excellent sealing properties, and thus is particularly suitable as a member used in a state in contact with a nonaqueous electrolyte in a nonaqueous electrolyte battery. That is, the compressed member of the present application can have a liquid-contacting surface with a nonaqueous electrolyte in a nonaqueous electrolyte battery.

[0124] The compressed member of the present application is less likely to allow water vapor to permeate. Therefore, by using the compressed member of the present application, it is possible to suppress the permeation of water vapor from the outside into a secondary battery. As a result, by using the compressed member of the present application, it is possible to suppress the deterioration of the battery performance and the shortening of the life of a nonaqueous electrolyte battery.

[0125] Since it is possible to further suppress the deterioration of the battery performance and the shortening of the life of a nonaqueous electrolyte battery, the water vapor permeation degree of the compressed member of the present application is preferably 9.5 g-cm / m 2 More preferably, it is 9.0 g-cm / m 2 Hereinafter. The water vapor permeation degree of the compressed member can be measured under the conditions of a temperature of 95°C and 30 days.

[0126] As a nonaqueous electrolyte battery, there is no particular limitation as long as it is a battery provided with a nonaqueous electrolyte, and examples thereof can include a lithium ion secondary battery, a lithium ion capacitor, and the like. In addition, as a member constituting a nonaqueous electrolyte battery, examples thereof can include a sealing member, an insulating member, and the like.

[0127] The above nonaqueous electrolyte is not particularly limited, and one or two or more kinds of publicly known solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate can be used. The nonaqueous electrolyte battery can further be provided with an electrolyte. The above electrolyte is not particularly limited, and LiClO4, LiAsF6, LiPF6, LiBF4, LiCl, LiBr, CH3SO3Li, CF3SO3Li, cesium carbonate, and the like can be used.

[0128] The compressed member of the present application can be preferably used as a sealing member such as a gasket, a packing, or the like, an insulating member such as an insulating gasket, or the like. The sealing member is a member used for preventing leakage of liquid or gas or intrusion of liquid or gas from the outside. The insulating member is a member used for electrical insulation. The compressed member of the present application can also be a member used for both sealing and insulation.

[0129] The compressed member of the present application is less likely to be cracked even when it is in contact with a medicine, has very excellent water vapor low permeability, and has excellent sealing properties, and thus can be suitably used as a sealing member or an insulating member for a nonaqueous electrolyte battery. In addition, the compressed member of the present application has excellent insulating properties because it contains the fluorine-containing copolymer described above. Thus, when the compressed member of the present application is used as an insulating member, it is firmly bonded to two or more conductive members, and prevents short circuiting for a long period of time.

[0130] The fluorine-containing copolymer of the present application can form a coating layer having a uniform thickness on a core wire having a small diameter by an extrusion molding method, and thus can be suitably used as a material for forming a wire coating. The coated wire having a coating layer containing the fluorine-containing copolymer of the present application has almost no variation in outer diameter, and thus has excellent electrical properties.

[0131] The coated wire has a core wire and a coating layer containing the fluorine-containing copolymer of the present application provided around the core wire. For example, an extrusion molded body obtained by melt-extrusion molding the fluorine-containing copolymer of the present application on a core wire can be used as the coating layer. The coated wire is suitably used for LAN cable (Ethernet Cable), high-frequency transmission cable, flat cable, heat-resistant cable, and the like, and is suitably used for transmission cables such as LAN cable (Ethernet Cable) and high-frequency transmission cable.

[0132] As a material for the core wire, a metal conductor material such as copper, aluminum, or the like can be used. The core wire preferably has a diameter of 0.02 mm to 3 mm. The diameter of the core wire is more preferably 0.04 mm or more, further preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. The diameter of the core wire is more preferably 2 mm or less.

[0133] As a specific example of the core wire, for example, AWG (American Wire Gauge)-46 (solid copper wire having a diameter of 40 μm), AWG-26 (solid copper wire having a diameter of 404 μm), AWG-24 (solid copper wire having a diameter of 510 μm), AWG-22 (solid copper wire having a diameter of 635 μm), or the like can be used.

[0134] The thickness of the coating layer is preferably 0.1 mm to 3.0 mm. The thickness of the coating layer is also preferably 2.0 mm or less.

[0135] As a high frequency transmission cable, a coaxial cable can be given. The coaxial cable generally has a structure in which an inner conductor, an insulating coating layer, an outer conductor layer, and a protective coating layer are sequentially layered from the core to the outer peripheral portion. The molded body containing the fluorine-containing copolymer of the present application can be suitably used as the insulating coating layer containing the fluorine-containing copolymer. The thickness of each layer in the above structure is not particularly limited, and generally, the diameter of the inner conductor is about 0.1 mm to 3 mm, the thickness of the insulating coating layer 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 coating layer is about 0.5 mm to 2 mm.

[0136] The coating layer can contain bubbles, and the bubbles are preferably uniformly distributed in the coating layer.

[0137] The average bubble diameter is not limited, and for example, it is preferably 60 μm or less, more preferably 45 μm or less, further preferably 35 μm or less, still further preferably 30 μm or less, particularly preferably 25 μm or less, and especially preferably 23 μm or less. In addition, the average bubble diameter is preferably 0.1 μm or more, and more preferably 1 μm or more. The average bubble diameter can be calculated by obtaining an electron microscope image of a cross section of the wire, calculating the diameter of each bubble using image processing, and averaging.

[0138] The foaming ratio of the coating layer can be 20% or more. More preferably, it is 30% or more, further preferably 33% or more, and still further preferably 35% or more. The upper limit is not particularly limited, and for example, it is 80%. The upper limit of the foaming ratio can be 60%. The foaming ratio is a value calculated as ((specific gravity of the wire coating material - specific gravity of the coating layer) / specific gravity of the wire coating material) x 100. The foaming ratio can be adjusted as appropriate according to the use, for example, by adjusting the amount of gas inserted in the extruder described later, or by selecting the type of gas to be dissolved.

[0139] The coated wire can have other layers between the above core wire and the above coating layer, and can further have other layers (outer layers) around the coating layer. In the case where the coating layer contains bubbles, the wire of the present application can have a two-layer structure (skin-foam) in which a non-foamed layer is interposed between the core wire and the coating layer; a two-layer structure (foam-skin) in which a non-foamed layer is coated on the outer layer; or a three-layer structure (skin-foam-skin) in which a non-foamed layer is further coated on the outer layer of the skin-foam. The non-foamed layer is not particularly limited, and can be a resin layer composed of a TFE / HFP-based copolymer, a TFE / PAVE-based copolymer, a TFE / ethylene-based copolymer, a vinylidene fluoride-based polymer, a polyolefin resin such as polyethylene [PE], or a resin such as polyvinyl chloride [PVC].

[0140] The coated electric wire can be manufactured, for example, by heating the fluorine-containing copolymer using an extruder, extruding the fluorine-containing copolymer onto a core wire in a molten state of the fluorine-containing copolymer, and forming a coating layer.

[0141] In forming the coating layer, a gas can also be introduced into the fluorine-containing copolymer in a molten state of the fluorine-containing copolymer by heating the fluorine-containing copolymer, thereby forming the above-mentioned coating layer containing bubbles. As the gas, for example, a gas such as difluorochloromethane, nitrogen, carbon dioxide, or a mixture of the above-mentioned gases can be used. The gas can be introduced into the heated fluorine-containing copolymer in the form of pressurized gas or can be generated by mixing a chemical foaming agent in the fluorine-containing copolymer. The gas is dissolved in the fluorine-containing copolymer in a molten state.

[0142] In addition, the fluorine-containing copolymer of the present application can be suitably used as a material for a high-frequency signal transmission product.

[0143] As the above-mentioned high-frequency signal transmission product, there is no particular limitation as long as it is a product for transmission of a high-frequency signal, and examples thereof can include (1) an insulating board for a high-frequency circuit, an insulating article for a connecting member, a molded board such as a printed wiring board, (2) a base for a vacuum tube for high frequencies, a molded body such as an antenna cover, (3) a coated electric wire such as a coaxial cable, a LAN cable, and the like. The above-mentioned high-frequency signal transmission product can be suitably used for a device utilizing microwaves, particularly microwaves of 3 GHz to 30 GHz, such as a satellite communication device, a mobile phone base station, and the like.

[0144] In the above-mentioned high-frequency signal transmission product, the fluorine-containing copolymer of the present application can be suitably used as an insulating body from the viewpoint of low tangent of dielectric loss.

[0145] As the above-mentioned (1) molded board, a printed wiring board is preferred from the viewpoint of obtaining good electrical properties. As the above-mentioned printed wiring board, there is no particular limitation, and examples thereof can include, for example, a printed wiring board for an electronic circuit such as a mobile phone, various computers, a communication device, and the like. As the above-mentioned (2) molded body, an antenna cover is preferred from the viewpoint of low dielectric loss.

[0146] The fluorine-containing copolymer of the present application is molded, and a film can be obtained. The molded body containing the fluorine-containing copolymer of the present application can be suitably used as a film.

[0147] The film of the present application is useful as a release film. The release film can be manufactured by molding the fluorine-containing copolymer of the present application by melt extrusion molding, calender molding, press molding, flow casting, or the like. From the viewpoint of obtaining a uniform thin film, the release film can be manufactured by melt extrusion molding.

[0148] The film of the present application can be applied to the surface of a roller used in an OA device. In addition, the fluorine-containing copolymer of the present application can be molded into a necessary shape by extrusion molding, compression molding, press molding, or the like, into a sheet shape, a film shape, a tube shape, and used as a surface material for an OA device roller or an OA device belt or the like. In particular, a thin-walled tube or film can be manufactured by a melt extrusion molding method.

[0149] The embodiments have been described above, but it is understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0150] Examples

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

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

[0153] (Content of monomer unit)

[0154] The content of each monomer unit of the fluorine-containing copolymer was measured using an NMR analysis device (for example, AVANCE 300 high temperature probe manufactured by Bruker BioSpin Co., Ltd.) or an infrared absorption measuring device (Spectrum One manufactured by Perkin Elmer Co., Ltd.).

[0155] (Number of -CF2H)

[0156] The number of -CF2H groups of the fluorine-containing copolymer was measured using a nuclear magnetic resonance device AVANCE-300 (manufactured by Bruker BioSpin Co., Ltd.) with a measurement temperature set to (polymer melting point + 20) °C. 19 F-NMR measurement, from the peak integral value of -CF2H groups.

[0157] (Number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2)

[0158] The dry powder or pellets obtained in the examples and comparative examples were cold-pressed to produce a film having a thickness of 0.25 mm to 0.3 mm. The film was scanned 40 times by a Fourier transform infrared spectroscopy analysis device [FT-IR (Spectrum One, manufactured by Perkin Elmer Co., Ltd.)], and analyzed to obtain an infrared absorption spectrum. The obtained infrared absorption spectrum was compared with the infrared absorption spectrum of a known film to determine the type of terminal group. In addition, from the absorption peak of a specific functional group appearing in the differential spectrum of the obtained infrared absorption spectrum and the infrared absorption spectrum of a known film, the number of each 1 x 106 N: number of functional groups of carbon atoms

[0159] N = I x K / t (A)

[0160] I: absorbance

[0161] K: correction coefficient

[0162] t: thickness of the film (mm)

[0163] As a reference, regarding the functional groups in the examples, the absorption frequency, molar absorption coefficient, and correction coefficient are shown in Table 2. In addition, the molar absorption coefficient is determined from the FT-IR measurement data of the low molecular model compound.

[0164] [Table 2]

[0165] Table 2

[0166]

[0167] (Melt Flow Rate (MFR))

[0168] Regarding the MFR of the fluorine-containing copolymer, the mass (g / 10 minutes) of the polymer flowing out from a die of inner diameter 2 mm and length 8 mm per 10 minutes was measured at 372°C under a load of 5 kg using a melt flow indexer G-01 (manufactured by Toyo Seiki Co., Ltd.) in accordance with ASTM D-1238, and the MFR was calculated therefrom.

[0169] (Melting Point)

[0170] Regarding the melting point of the fluorine-containing copolymer, a differential scanning calorimeter (trade name: X-DSC7000, manufactured by Hitachi High-Tech Science Corporation) was used to perform a first temperature rise from 200°C to 350°C at a temperature rise rate of 10°C / minute, then, to cool from 350°C to 200°C at a cooling rate of 10°C / minute, and again to perform a second temperature rise from 200°C to 350°C at a temperature rise rate of 10°C / minute, and the melting point was calculated from the peak value of the melting curve generated during the second temperature rise.

[0171] Example 1

[0172] A 174-L autoclave equipped with a stirrer was charged with 40.25 kg of deionized water and 0.450 kg of methanol, and the autoclave was sufficiently subjected to vacuum nitrogen substitution. Thereafter, the autoclave was vacuum degassed, and 40.25 kg of HFP and 1.06 kg of PPVE were charged into the autoclave which had become vacuum, and the autoclave was heated to 25.5°C. Subsequently, TFE was charged until the internal pressure of the autoclave reached 0.892 MPa, and then 1.25 kg of a 8 mass% solution of di(ω-hydroperfluorohexanoyl) peroxide (hereinafter referred to as DHP) was charged into the autoclave, and polymerization was started. The internal pressure of the autoclave at the start of polymerization was set to 0.892 MPa, and the set pressure was maintained by continuously adding TFE. Methanol 0.450 kg was added after 1.5 hours from the start of polymerization. DHP 1.25 kg was added after 2 hours and after 4 hours from the start of polymerization, and the internal pressure was lowered by 0.002 MPa each time. Thereafter, DHP 0.25 kg was added every 2 hours until the end of the reaction, and the internal pressure was lowered by 0.002 MPa each time.

[0173] Note that 0.22 kg of PPVE was added at the time when the amount of TFE added continuously reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. In addition, 0.450 kg of methanol was added to the autoclave at the time when the amount of TFE added reached 6.0 kg and 18.1 kg, respectively. Furthermore, the polymerization was ended at the time when the amount of TFE added reached 40.25 kg. After the completion of the polymerization, unreacted TFE and HFP were released, and a wet powder was obtained. Thereafter, the wet powder was washed with pure water, and then dried at 150°C for 10 hours, and a dry powder of 44.8 kg was obtained.

[0174] The obtained powder was melt-extruded using a screw extruder (trade name: PCM46, manufactured by Tekurion Co., Ltd.) at 370°C, and a pellet of the copolymer was obtained. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0175] Example 2

[0176] The amount of methanol charged before the start of polymerization was changed to 0.489 kg, the amounts of methanol added separately after the start of polymerization were changed to 0.489 kg each, the amount of PPVE charged before the start of polymerization was changed to 1.21 kg, the amounts of PPVE added separately after the start of polymerization were changed to 0.27 kg each, and the set pressure of the autoclave before and after the start of polymerization was changed to 0.878 MPa, and a pellet of the copolymer was obtained in the same manner as in Example 1 except for the above. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0177] Example 3

[0178] The amount of methanol charged before the start of polymerization was changed to 0.411 kg, the amounts of methanol separately charged after the start of polymerization were changed to 0.411 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.96 kg, the amounts of PPVE separately charged after the start of polymerization were changed to 0.22 kg each, and the set pressure inside the autoclave before and after the start of polymerization was changed to 0.866 MPa, and otherwise the same as in Example 1 to obtain copolymer pellets. The HFP content and the PPVE content were measured by the above-described methods using the obtained pellets. The results are shown in Table 3.

[0179] After the obtained pellets were degassed at 200°C for 8 hours in an electric furnace, they were put into a vacuum vibration-type reaction apparatus VVD-30 (manufactured by Okawara Mfg. Co., Ltd.), and warmed to 200°C. After vacuumizing, F2 gas diluted to 20 vol% with N2 gas was introduced to atmospheric pressure. After 0.5 hours from the start of the introduction of the F2 gas, the vacuum was temporarily released, and the F2 gas was introduced again. Further, after 0.5 hours from the introduction, the vacuum was released again, and the F2 gas was introduced again. Thereafter, the above-described operation of introducing and releasing the F2 gas was continued once for 1 hour, and the reaction was carried out at a temperature of 200°C for 8 hours. After the end of the reaction, the inside of the reactor was sufficiently replaced with N2 gas, and the fluorination reaction was terminated to obtain pellets. The various physical properties were measured by the above-described methods using the obtained pellets. The results are shown in Table 3.

[0180] Example 4

[0181] The amount of methanol charged before the start of polymerization was changed to 0.416 kg, the amounts of methanol separately charged after the start of polymerization were changed to 0.416 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.93 kg, the amounts of PPVE separately charged after the start of polymerization were changed to 0.22 kg each, and the set pressure inside the autoclave before and after the start of polymerization was changed to 0.855 MPa, and otherwise the same as in Example 1 to obtain copolymer pellets. The various physical properties were measured by the above-described methods using the obtained pellets. The results are shown in Table 3.

[0182] Example 5

[0183] The amount of methanol charged before the start of polymerization was changed to 0.385 kg, the amounts of methanol separately charged after the start of polymerization were changed to 0.385 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.79 kg, the amounts of PPVE separately charged after the start of polymerization were changed to 0.19 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.855 MPa, and otherwise the same as in Example 1 to obtain copolymer pellets. The obtained pellets were used to measure various physical properties by the above-described methods. The results are shown in Table 3.

[0184] Example 6

[0185] The amount of methanol charged before the start of polymerization was changed to 0.318 kg, the amounts of methanol separately charged after the start of polymerization were changed to 0.318 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.75 kg, the amounts of PPVE separately charged after the start of polymerization were changed to 0.21 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.843 MPa, and otherwise the same as in Example 1 to obtain copolymer pellets. The obtained pellets were used to measure various physical properties by the above-described methods. The results are shown in Table 3.

[0186] After the obtained pellets were degassed at 200°C for 72 hours in an electric furnace, they were put into a vacuum vibration-type reaction apparatus VVD-30 (manufactured by Okawara Mfg. Co., Ltd.), and warmed to 110°C. After vacuumizing, F2 gas diluted to 20 vol% with N2 gas was introduced to atmospheric pressure. After 0.5 hours from the start of the introduction of F2 gas, the vacuum was temporarily released, and F2 gas was introduced again. Further, after 0.5 hours from the introduction, the vacuum was released again, and F2 gas was introduced again. Thereafter, the above-described operation of introducing and releasing F2 gas was continued once for 1 hour, and the reaction was carried out at a temperature of 110°C for 8 hours. After the end of the reaction, the inside of the reactor was sufficiently replaced with N2 gas, and the fluorination reaction was terminated to obtain pellets. The obtained pellets were used to measure various physical properties by the above-described methods. The results are shown in Table 3.

[0187] Example 7

[0188] The amount of methanol charged before the start of polymerization was changed to 0.333 kg, the amounts of methanol separately charged after the start of polymerization were changed to 0.333 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.86 kg, the amounts of PPVE separately charged after the start of polymerization were changed to 0.22 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.837 MPa, and otherwise the same as in Example 1 to obtain copolymer pellets. The obtained pellets were used to measure HFP content and PPVE content by the above-described methods. The results are shown in Table 3.

[0189] The obtained pellets were fluorinated in the same manner as in Example 3. Using the obtained pellets, various physical properties were measured by the above-mentioned methods. The results are shown in Table 3.

[0190] Comparative Example 1

[0191] Into a 174-L stirred autoclave, 40.25 kg of deionized water and 0.300 kg of methanol were charged, and the autoclave was sufficiently subjected to vacuum-nitrogen replacement. Thereafter, the autoclave was vacuum-deaerated, and 40.25 kg of HFP and 1.03 kg of PPVE were charged into the autoclave, which was vacuumed, and the autoclave was heated to 30.0°C. Next, TFE was charged until the internal pressure of the autoclave reached 0.928 MPa, and then 0.63 kg of a 8-mass% solution of di(ω-hydroperfluorohexanoyl) peroxide (hereinafter referred to as DHP) was charged into the autoclave, and polymerization was started. The internal pressure of the autoclave at the start of polymerization was set to 0.928 MPa, and the set pressure was maintained by continuously adding TFE. Methanol 0.300 kg was added after 1.5 hours from the start of polymerization. DHP 0.63 kg was added after 2 hours and after 4 hours from the start of polymerization, and the internal pressure was lowered by 0.001 MPa each time. Thereafter, DHP 0.13 kg was added every 2 hours until the end of the reaction, and the internal pressure was lowered by 0.001 MPa each time.

[0192] Note that, at the time when the amount of continuously added TFE reached 8.1 kg, 16.2 kg, and 24.3 kg, 0.29 kg of PPVE was added each time. In addition, at the time when the amount of added TFE reached 6.0 kg and 18.1 kg, 0.300 kg of methanol was added each time into the autoclave. Furthermore, the polymerization was ended at the time when the amount of added TFE reached 40.25 kg. After the completion of the polymerization, unreacted TFE and HFP were released, and a wet powder was obtained. Thereafter, the wet powder was washed with pure water, and then dried at 150°C for 10 hours, and 46.4 kg of a dry powder was obtained.

[0193] The obtained powder was melt-extruded using a screw extruder (trade name: PCM46, manufactured by Tekno Process Machinery Co., Ltd.) at 370°C, and pellets of the copolymer were obtained. Using the obtained pellets, various physical properties were measured by the above-mentioned methods. The results are shown in Table 3.

[0194] Comparative Example 2

[0195] The amount of methanol charged before the start of polymerization was changed to 0.393 kg, the amounts of methanol charged in portions after the start of polymerization were each changed to 0.393 kg, the amount of PPVE charged before the start of polymerization was changed to 0.51 kg, the amounts of PPVE charged in portions after the start of polymerization were each changed to 0.13 kg, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.834 MPa, and apart from this, a copolymer pellet was obtained in the same manner as in Example 1. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0196] Comparative Example 3

[0197] The amount of methanol charged before the start of polymerization was changed to 0.452 kg, the amounts of methanol charged in portions after the start of polymerization were each changed to 0.452 kg, the amount of PPVE charged before the start of polymerization was changed to 0.73 kg, the amounts of PPVE charged in portions after the start of polymerization were each changed to 0.14 kg, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.906 MPa, and apart from this, a copolymer pellet was obtained in the same manner as in Example 1. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0198] Comparative Example 4

[0199] The amount of methanol charged before the start of polymerization was changed to 0.276 kg, the amounts of methanol charged in portions after the start of polymerization were each changed to 0.276 kg, the amount of PPVE charged before the start of polymerization was changed to 0.88 kg, the amounts of PPVE charged in portions after the start of polymerization were each changed to 0.22 kg, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.843 MPa, and apart from this, a copolymer pellet was obtained in the same manner as in Example 1. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0200] Comparative Example 5

[0201] The amount of methanol charged before the start of polymerization was changed to 0.625 kg, the amounts of methanol charged in portions after the start of polymerization were each changed to 0.625 kg, the amount of PPVE charged before the start of polymerization was changed to 1.06 kg, the amounts of PPVE charged in portions after the start of polymerization were each changed to 0.22 kg, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.893 MPa, and apart from this, a copolymer pellet was obtained in the same manner as in Example 1. Using the obtained pellet, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0202] Comparative Example 6

[0203] The amount of methanol charged before the start of polymerization was changed to 0.612 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.612 kg each, the amount of PPVE charged before the start of polymerization was changed to 1.19 kg, the amounts of PPVE charged in portions after the start of polymerization were changed to 0.22 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.924 MPa, and otherwise, copolymer pellets were obtained in the same manner as in Example 1. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0204] Comparative Example 7

[0205] An autoclave with a stirrer having a volume of 4 L was charged with deionized water 945 g and methanol 6.9 g, and nitrogen was introduced into the autoclave while the inside of the autoclave was being sufficiently evacuated. After that, the autoclave was vacuum degassed, and HFP 945 g and PEVE 17.5 g were charged into the autoclave in the vacuum state, and the autoclave was heated to 25.5°C. Next, TFE was charged until the internal pressure of the autoclave reached 0.846 MPa, and then 8 mass% of di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) 29.4 g was charged into the autoclave, and polymerization was started. The internal pressure of the autoclave at the start of polymerization was set to 0.846 MPa, and the set pressure was maintained by continuously charging TFE. Methanol 6.9 g was charged after 1.5 hours from the start of polymerization. DHP 29.4 g was charged after 2 hours and after 4 hours from the start of polymerization, and the internal pressure was lowered by 0.002 MPa each time, and 22.6 g was charged after 6 hours, and the internal pressure was lowered by 0.002 MPa. After that, DHP 6.0 g was charged in portions every 2 hours until the end of the reaction, and the internal pressure was lowered by 0.002 MPa each time.

[0206] Note that PEVE 4.4 g was charged in portions at the times when the amount of TFE charged continuously reached 190 g and 380 g. In addition, methanol 7.8 g was charged into the autoclave at the time when the amount of TFE charged reached 140 g. Furthermore, the polymerization was ended at the time when the amount of TFE charged reached 454 g. After the end of the polymerization, unreacted TFE and HFP were released, and a wet powder was obtained. After that, the wet powder was washed with pure water, and then dried at 150°C for 10 hours, and a dried powder 514 g was obtained.

[0207] The obtained powder was used A screw extruder (manufactured by JIMTOU) was used to melt-extrude at 370°C, and copolymer pellets were obtained. Using the obtained pellets, the HFP content and the PEVE content were measured by the above-described methods. The results are shown in Table 3.

[0208] After the obtained pellets were degassed at 200°C for 8 hours in an electric furnace, they were put into a portable reactor Model TVS1 (manufactured by Taitec Corporation) and heated to 200°C. After vacuumizing, F2 gas diluted to 20 vol% with N2 gas was introduced to the atmospheric pressure. After 0.5 hours from the start of the introduction of the F2 gas, the reactor was temporarily vacuumized and the F2 gas was introduced again. Further, after 0.5 hours therefrom, the reactor was vacuumized again and the F2 gas was introduced again. Thereafter, the operation of the introduction and vacuumization of the F2 gas was repeated once every 1 hour, and the reaction was carried out at a temperature of 200°C for 8 hours. After the completion of the reaction, the reactor was sufficiently replaced with N2 gas, and the fluorination reaction was completed to obtain pellets. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0209] [Table 3]

[0210] Table 3

[0211]

[0212] The notation of "<9" in Table 3 means that the number of -CF2H groups is less than 9. The notation of "<6" in Table 3 means that the total number (the number of functional groups N) of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2 is less than 6.

[0213] Next, using the obtained pellets, the following properties were evaluated. The results are shown in Table 4.

[0214] (Abrasion Test)

[0215] Using the pellets and a hot press molding machine, a sheet-shaped test piece having a thickness of about 0.2 mm was produced, and a test piece of 10 cm x 10 cm was cut therefrom. The produced test piece was fixed on a test stage of a Taber abrasion tester (No. 101 Taber-type abrasion tester, manufactured by Anritsu Kikai K.K.), and an abrasion test was carried out using the Taber abrasion tester under conditions of a test piece surface temperature of 140°C, a load of 500 g, an abrasive wheel CS-10 (ground with abrasive paper #240 for 20 turns), and a rotation speed of 60 rpm. The weight of the test piece after 1000 turns was measured, and the weight of the test piece was further measured after 5000 turns of the test using the same test piece. The abrasion amount was calculated by the following equation.

[0216] Abrasion amount (mg) = M1 - M2

[0217] M1: weight of test piece after 1000 turns (mg)

[0218] M2: weight of test piece after 5000 turns (mg)

[0219] (Water Vapor Transmission Rate)

[0220] Using the pellets and a hot press molding machine, a sheet-shaped test piece having a thickness of about 0.2 mm was produced. In a test cup (transmission area 12.56 cm 2 ) was put water 18 g, covered with the sheet-shaped test piece, and fastened and sealed with a PTFE gasket. The sheet-shaped test piece was left in contact with the water for 30 days at a temperature of 95°C, and then taken out. After being left at room temperature for 2 hours, the mass reduction was measured. The water vapor transmission rate (g-cm / m 2 ) was measured by the following equation.

[0221] Water vapor transmission rate (g-cm / m 2 ) = mass reduction (g) x thickness of sheet-shaped test piece (cm) / transmission area (m 2 )

[0222] (100°C load deflection rate)

[0223] Using the pellets and a hot press molding machine, a sheet-shaped test piece having a thickness of about 4 mm was produced, and a test piece of 80 x 10 mm was cut out therefrom, and heated at 100°C for 20 hours using an electric furnace. Except for using the obtained test piece, a heat distortion tester (manufactured by Anritsu Seimitsu Kogyo Co., Ltd.) was used to perform a test under the conditions of a test temperature of 30°C to 150°C, a temperature increase rate of 120°C / hour, a bending stress of 1.8 MPa, and a flatwise method as described in JIS K-K7191-1. The load deflection rate was calculated by the following equation. The sheet having a small load deflection rate at 100°C has excellent rigidity at high temperature of 100°C.

[0224] Load deflection rate (%) = a2 / a1 x 100

[0225] a1: thickness of test piece before test (mm)

[0226] a2: deflection amount at 100°C (mm)

[0227] (Tensile strength after 100,000 cycles)

[0228] The tensile strength after 100,000 cycles was measured using a fatigue tester MMT-250NV-10 manufactured by Shimadzu Corporation. Using the pellets and a hot press molding machine, a sheet having a thickness of about 2.4 mm was produced, and a dumbbell-shaped sample (thickness 2.4 mm, width 5.0 mm, measurement portion length 22 mm) was produced using an ASTM D1708 micro-dumbbell. The sample was mounted to a measurement jig, and the measurement jig was set in a constant temperature tank at 110°C in a state where the sample was mounted. Tensile strength was measured for each of the tensile strengths (tensile strength at a stroke of +0.2 mm, unit: N) by repeatedly performing tensile stretching in a single axis direction at a stroke of 0.2 mm and a frequency of 100 Hz. The tensile strength after 100,000 cycles was calculated from the measured values according to the following equation.

[0229] The sheet having high tensile strength after 100,000 cycles maintains high tensile strength even after 100,000 cycles of load, and is excellent in durability to repeated load (110°C).

[0230] (injection moldability)

[0231] A fluorine-containing copolymer was injection molded using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., SE50EV-A) with a cylinder temperature of 385°C, a mold temperature of 200°C, and an injection speed of 100 mm / s. As the mold, a mold on which Cr plating was performed on HPM38 (4 cavities of 15 mm x 15 mm x 1 mm t, side gate) was used. The four injection molded bodies obtained were observed, and evaluated according to the following criteria. The presence or absence of surface roughness was confirmed by contacting the surface of the injection molded body.

[0232] 3: The surfaces of the four molded bodies were smooth as a whole.

[0233] 2: Roughness was confirmed on the surface of one of the four molded bodies within a range of 1 cm from the part where the gate of the mold was located.

[0234] 1: Roughness was confirmed on the surface of two to four of the four molded bodies within a range of 1 cm from the part where the gate of the mold was located.

[0235] 0: Roughness was confirmed on the surfaces of the four molded bodies as a whole.

[0236] In Comparative Example 5, burrs were observed in the obtained injection molded body, and the molded body could not be used directly.

[0237] (wire coating test)

[0238] Using A wire coating molding machine (manufactured by Nissei Plastic Industrial Co., Ltd.) was used to extrude a fluorine-containing copolymer on a silver-plated conductor of 19 twisted wires each having a diameter of 0.08 mm to obtain a coated wire at a coating thickness of 0.30 mm. The wire coating extrusion molding conditions were as follows.

[0239] a) Core conductor: conductor diameter about 0.40 mm (0.08 mm x 19 twisted)

[0240] b) Coating thickness: 0.30 mm

[0241] c) Coated wire diameter: 1.00 mm

[0242] d) Wire pulling speed: 120 m / min

[0243] e) Extrusion conditions:

[0244] • Single screw extrusion molding machine with a cylinder shaft diameter of 30 mm and L / D of 24

[0245] • Die (inner diameter) / sheet (outer diameter) = 10.0 mm / 4.0 mm

[0246] Setting temperature of extruder: barrel section C-1 (330°C), barrel section C-2 (360°C), barrel section C-3 (365°C), head section H (370°C), die section D-1 (370°C), die section D-2 (370°C). Core wire preheating was set to 80°C.

[0247] (Change in outer diameter)

[0248] The outer diameter of the obtained coated electric wire was measured using an outer diameter measuring device (ODAC18XY manufactured by Zumbach) for 1 hour continuously. The third digit after the decimal point of the outer diameter value deviating the most from the prescribed outer diameter value (1.00 mm) was rounded off, and thus the change in outer diameter was calculated. The proportion of the absolute value of the difference between the prescribed outer diameter and the change in outer diameter with respect to the prescribed outer diameter (1.00 mm) (change rate in outer diameter) was calculated, and evaluated according to the following criteria.

[0249] (Change rate in outer diameter (%)) = | (change in outer diameter) - (prescribed outer diameter) | / (prescribed outer diameter) x 100

[0250] ±1%: Change rate in outer diameter is 1% or less

[0251] ±2%: Change rate in outer diameter exceeds 1% and is 2% or less

[0252] x: Change rate in outer diameter exceeds 2%

[0253] (Drug immersion crack test)

[0254] A molded body having a thickness of about 2 mm was produced by pouring about 50 g of the above-described pellets into a mold (inner diameter 120 mm, height 38 mm), heating at 360°C for 20 minutes using a hot plate press, and then water-cooling while applying pressure of 1 MPa. A 13.5 mm x 38 mm rectangular dumbbell was used to punch out the obtained sheet, and thus three test pieces were obtained. A notch was cut in the center of the long side of each of the obtained test pieces using a 19 mm x 0.45 mm blade according to ASTM D1693. Three notched test pieces and 25 g of a 40 mass% aqueous solution of tetrabutylammonium hydroxide were placed in a 100 mL polypropylene bottle, and after heating at 100°C for 20 hours using an electric furnace, the notched test pieces were removed. The obtained three notched test pieces were installed in a stress cracking test jig according to ASTM D1693, and after heating at 150°C for 24 hours in an electric furnace, the notches and their peripheries were visually observed, and the number of cracks was counted.

[0255] O: Number of cracks is 0

[0256] X: The number of cracks is 1 or more

[0257] XX: The number of cracks generated when the notched test piece is installed in the stress crack test jig is 1 or more

[0258] (In an immersion test in hydrogen peroxide water)

[0259] Using the pellets and a hot press molding machine, a piece having a thickness of about 0.2 mm was produced, and a test piece of 15 mm square was produced. Into a 50 mL polypropylene-made bottle, 10 test pieces and 15 g of a 3 mass% hydrogen peroxide water solution were put, and after heating at 95°C for 20 hours using an electric furnace, it was cooled to room temperature. The test piece was taken out from the hydrogen peroxide water solution, and a TISAB solution (10) (manufactured by Kanto Chemical Co., Inc.) was added to the residual hydrogen peroxide water solution, and the concentration of fluoride ions in the obtained hydrogen peroxide water solution was measured using a fluoride ion meter. From the obtained measured value, the concentration of fluoride ions per unit weight of the test piece (eluted fluoride ion concentration) was calculated according to the following formula.

[0260] Eluted fluoride ion concentration (mass ppm) = Measured value (ppm) x hydrogen peroxide water solution amount (g) / test piece weight (g)

[0261]

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 87.7 to 91.5 mass% relative to the total monomer units, the content of the hexafluoropropylene units is 7.0 to 9.4 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 under a load of 5 kg at 372°C is 15 to 40 g / 10 minutes. The content of the hexafluoropropylene units is 7.2 to 9.2 mass% relative to the total monomer units. The content of the perfluoro(propyl vinyl ether) units is 1.7 to 2.4 mass% relative to the total monomer units. The melt flow rate under a load of 5 kg at 372°C is 16 to 38 g / 10 minutes.

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

2. The fluorocopolymer of claim 1, wherein, 7. A coated electric wire having a coating layer containing the fluorine-containing copolymer according to any one of claims 1 to 5.

3. The fluorocopolymer of claim 1 or 2, wherein, The molded article is a flow meter member or a pipe member.

4. The fluorocopolymer of claim 1 or 2, wherein, The molded article is a flow meter member or a pipe member.

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

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