Fluorine-containing copolymer

Abstract

The present application provides 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 9.5 to 12.2 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 0.5 to 1.4 mass% relative to the total monomer units, the melt flow rate at 372°C is 0.8 to 4.0 g / 10 minutes, the number of -CF2H groups is more than 50 per 10 6 main chain carbon atoms.

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 is excellent in extrusion moldability, can be easily molded into a film having a uniform thickness, and can provide a molded product which is excellent in 50°C abrasion resistance, low methane permeability, rigidity at 100°C, 130°C tensile creep resistance, and durability to repeated load.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] According to the present application, there is provided a fluorine-containing copolymer which is a fluorine-containing copolymer containing tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein the content of the hexafluoropropylene units is 9.5% by mass to 12.2% by mass with respect to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 0.5% by mass to 1.4% by mass with respect to the total monomer units, the melt flow rate at 372°C is 0.8 g / 10 minutes to 4.0 g / 10 minutes, the number of -CF2H groups per 10 6 main chain carbon atoms exceeds 50.

[0010] The content of the hexafluoropropylene units with respect to the total monomer units is preferably 10.0% by mass to 11.5% by mass.

[0011] The content of the perfluoro(propyl vinyl ether) units with respect to the total monomer units is preferably 0.6% by mass to 1.3% by mass.

[0012] The melt flow rate at 372°C is preferably 1.0 g / 10 minutes to 3.5 g / 10 minutes.

[0013] The total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH is preferably 50 or less per 10 6 main chain carbon atoms.

[0014] Further, according to the present application, there is provided an extrusion-molded body or a transfer-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 pipe, a film, or a coated electric wire.

[0017] Effects of the Invention

[0018] According to the present application, it is possible to provide a fluorine-containing copolymer which has excellent extrusion moldability, can be easily molded into a film having a uniform thickness, and can provide a molded body which has excellent 50°C abrasion resistance, low methane permeability, rigidity at 100°C, 130°C tensile creep resistance, and durability to repeated load. DETAILED DESCRIPTION

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

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

[0021] 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, compared with the existing fluorine-containing copolymer such as the terpolymer described in Patent Document 1, a fluorine-containing copolymer capable of obtaining a molded body excellent in wear resistance at high temperature and rigidity at high temperature is required. In particular, for a film used as a member of a pipe for supplying a methane gas, a pipe for supplying a methane gas, methane low permeability, high temperature tensile creep resistance, durability to repeated load are required, and in order not to be worn or deformed at a high temperature environment, wear resistance and rigidity are required. Furthermore, for the fluorine-containing copolymer constituting such a film, high moldability capable of easily molding a film having a uniform thickness is also required.

[0023] It was found that by adjusting the content of the HFP unit and the PPVE unit of the fluorine-containing copolymer containing a TFE unit, an HFP unit and a PPVE unit, and the melt flow rate to an extremely limited range, the moldability of the fluorine-containing copolymer is improved, and a molded body excellent in 50°C wear resistance, methane low permeability, 100°C high temperature rigidity, 130°C tensile creep resistance, durability to repeated load can be obtained.

[0024] Furthermore, by molding the fluorine-containing copolymer of the present application by an extrusion molding method, a film having a uniform thickness can be easily obtained.

[0025] The fluorine-containing copolymer of the present application is a melt processable fluororesin. The melt processability means that the polymer can be melted and processed using an existing processing equipment such as an extruder.

[0026] The content of the HFP unit of the fluorine-containing copolymer is 9.5 to 12.2 mass% with respect to the total monomer unit, preferably 9.6 mass% or more, more preferably 9.7 mass% or more, further preferably 9.8 mass% or more, particularly preferably 9.9 mass% or less, most preferably 10.0 mass% or more, preferably 12.0 mass% or less, more preferably 11.8 mass% or less, further preferably 11.6 mass% or less, more further preferably 11.5 mass% or less, particularly preferably 11.2 mass% or less, most preferably 11.1 mass% or less, and 11.0 mass% or less. If the content of the HFP unit is too small, a molded body excellent in 50°C wear resistance cannot be obtained. If the content of the HFP unit is too large, a molded body excellent in 100°C high temperature rigidity, 130°C tensile creep resistance, durability to repeated load cannot be obtained.

[0027] The content of the PPVE unit of the fluorine-containing copolymer is 0.5 to 1.4 mass% with respect to the total monomer unit, preferably 0.6 mass% or more, and preferably 1.3 mass% or less, and more preferably 1.2 mass% or less. If the content of the PPVE unit is too small, a molded body excellent in 50°C wear resistance cannot be obtained. If the content of the PPVE unit is too large, a molded body excellent in 100°C high temperature rigidity cannot be obtained.

[0028] The content of the TFE units of the fluorine-containing copolymer is preferably 90.0% by mass or less, more preferably 89.8% by mass or less, further preferably 89.6% by mass or less, more further preferably 89.4% by mass or less, preferably 86.3% by mass or more, more preferably 86.6% by mass or more, further preferably 86.9% by mass or more, more further preferably 87.1% by mass or more, particularly preferably 87.2% by mass or more, most preferably 87.8% by mass or more, relative to the total monomer units. In addition, the content of the TFE units can be selected so that the total content of the HFP units, the PPVE units, the TFE units, and the other monomer units is 100% by mass.

[0029] The fluorine-containing copolymer of the present application can be a copolymer containing only the above three kinds of monomer units, or a copolymer containing the above three kinds of monomer units and other monomer units, as long as it contains the above three kinds of monomer units.

[0030] As the other monomer, there is no particular limitation as long as it is a monomer copolymerizable 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, 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), 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), alkyl perfluoro vinyl ether derivatives 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] can be used.

[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 used.

[0033] As CF2=CF-ORf 1 Examples of the perfluoro(alkyl vinyl ether) include CF2=CF-OCF3 and CF2=CF-OCF2CF3.

[0034] Examples of the non-fluorinated monomer include hydrocarbon monomers copolymerizable with TFE, HFP, and PPVE. Examples of the hydrocarbon monomer include olefins such as ethylene, propylene, butylene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl p-tert-butylbenzoate, vinyl cyclohexanecarboxylate, and vinyl monochloroacetate. , vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, vinyl hydroxycyclohexanecarboxylate and other vinyl esters; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, cyclohexyl allyl ester, etc.

[0035] The non-fluorinated monomer may be a hydrocarbon monomer containing a functional group copolymerizable with TFE, HFP, and PPVE. Examples of the hydrocarbon monomer containing a functional group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; non-fluorinated monomers containing a glycidyl group such as glycidyl vinyl ether and glycidyl allyl ether; non-fluorinated monomers containing an amino group such as aminoalkyl vinyl ether and aminoalkyl allyl ether; non-fluorinated monomers containing an amide group such as (meth)acrylamide and hydroxymethyl acrylamide; bromine-containing olefins, iodine-containing olefins, bromine-containing vinyl ethers, and iodine-containing vinyl ethers; and non-fluorinated monomers containing a nitrile group.

[0036] The content of other monomer units in the fluorinated copolymer of the present invention is preferably 0 to 3.6 mass %, more preferably 1.0 mass % or less, further preferably 0.5 mass % or less, particularly preferably 0.1 mass % or less, based on the total monomer units.

[0037] The melt flow rate (MFR) of the fluorine-containing copolymer is 0.8 g / 10 min to 4.0 g / 10 min, preferably 0.9 g / 10 min or more, more preferably 1.0 g / 10 min or more, further preferably 1.5 g / 10 min or more, particularly preferably 2.0 g / 10 min or more, most preferably 2.5 g / 10 min or more, and preferably 3.9 g / 10 min or less, more preferably 3.8 g / 10 min or less, further preferably 3.7 g / 10 min or less, particularly preferably 3.6 g / 10 min or less, most preferably 3.5 g / 10 min or less. If the MFR is too high, a molded article having excellent 50°C wear resistance and 130°C tensile creep resistance cannot be obtained. If the MFR is too low, a molded article having excellent low methane permeability and rigidity at 100°C cannot be obtained. Furthermore, if the MFR is too low, the pressure during extrusion molding becomes too high, or a film having a uniform thickness cannot be obtained.

[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 Co., Ltd.) in accordance with ASTM D-1238 as the mass (g / 10 min) of polymer flowing per 10 min 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.

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

[0040] The fluorine-containing copolymer of the present application has -CF2H. The number of -CF2H in the fluorine-containing copolymer is 50 or more, preferably 60 or more, more preferably 70 or more, and further preferably 80 or more, per 10 6 The upper limit of the number of -CF2H is not particularly limited, and can be, for example, 800. If the number of -CF2H is too small, a molded article having excellent low methane permeability cannot be obtained. The number of -CF2H can be adjusted, for example, by appropriately selecting the type of polymerization initiator or chain transfer agent, or by the wet heat treatment or fluorination treatment of the fluorine-containing copolymer described below.

[0041] The fluorine-containing copolymer of the present application can have or not have -COF, -COOH, or -CH2OH. In the fluorine-containing copolymer of the present application, the total number of -COF, -COOH, and -CH2OH is 50 or more, preferably 60 or more, more preferably 70 or more, and further preferably 80 or more, per 10 6The total number of -COF, -COOH, and -CH2OH is preferably 40 or less, 30 or less, in the order of preference. By having the total number of -COF, -COOH, and -CH2OH within the above range, molding defects such as foaming are less likely to occur when the fluorine-containing copolymer is melt-molded, and the fluorine-containing copolymer is excellent in heat resistance. The total number of -COF, -COOH, and -CH2OH can be adjusted, for example, by appropriately selecting the type of polymerization initiator or chain transfer agent, or by the moist heat treatment or fluorination treatment of the fluorine-containing copolymer described later.

[0042] The fluorine-containing copolymer of the present application can have or not have a terminal group containing a carbonyl group, -CF=CF2, or -CH2OH. In the fluorine-containing copolymer of the present application, the total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH is 50 or less per 10 6 The total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH is preferably 50 or less, 40 or less, in the order of preference. By having the total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH within the above range, molding defects such as foaming are less likely to occur when the fluorine-containing copolymer is melt-molded, and the fluorine-containing copolymer is excellent in heat resistance. The total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH can be adjusted, for example, by appropriately selecting the type of polymerization initiator or chain transfer agent, or by the moist heat treatment or fluorination treatment of the fluorine-containing copolymer described later.

[0043] The terminal group containing a carbonyl group is, for example, -COF, -COOH, -COOR (R is an alkyl group), -CONH2, and -0(C=0)0-R (R is an alkyl group). The type of alkyl group (R) possessed by -COOR and -0(C=0)0-R is determined by the polymerization initiator, chain transfer agent, or the like used when the fluorine-containing copolymer is produced, and is, for example, an alkyl group having 1 to 6 carbon atoms such as -CH3.

[0044] The fluorine-containing copolymer of the present application can have or not have -0(C=0)0-R (R is an alkyl group). The fluorine-containing copolymer of the present application preferably has a total number of -0(C=0)0-R (R is an alkyl group) of 50 or less per 10 6 The total number of -0(C=0)0-R (R is an alkyl group) is preferably 40 or less, 30 or less, 20 or less, 15 or less, in the order of preference, and can be less than the quantification limit (ND). The total number of -0(C=0)0-R (R is an alkyl group) can be adjusted, for example, by appropriately selecting the type of polymerization initiator or chain transfer agent, or by the moist heat treatment or fluorination treatment of the fluorine-containing copolymer described later.

[0045] The identification of the types of the functional groups and the measurement of the number of the functional groups can be performed using infrared spectroscopy.

[0046] Regarding the number of functional groups, specifically, the following method is used for determination. First, the above-mentioned fluorinated copolymer is formed by cold pressing to produce a film with a thickness of 0.25 mm to 0.30 mm. The film is analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above-mentioned fluorinated copolymer, and a differential spectrum with the background spectrum of the completely fluorinated functional group without the presence of functional groups is obtained. According to the following formula (A), the number of functional groups in the above-mentioned fluorinated copolymer relative to each 1×10 6 The number of functional groups N per carbon atom.

[0047] N=I×K / t(A)

[0048] I: absorbance

[0049] K: Correction coefficient

[0050] t: film thickness (mm)

[0051] For reference, the absorption frequencies, molar absorptivity coefficients, and correction coefficients for some functional groups are shown in Table 1. The molar absorptivity coefficients were determined from FT-IR measurement data of low-molecular-weight model compounds.

[0052] [Table 1]

[0053] Table 1

[0054]

[0055] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are several tens of kaisekas (cm-1) lower than those of -CF2H, -COF, free -COOH, and bound -COOH, -COOCH3, and -CONH2, respectively, as shown in the table. 1 ).

[0056] For example, the functional group number of -COF refers to the absorption frequency 1883 cm-1 due to -CF2COF. 1 The number of functional groups obtained from the absorption peak at 1840 cm-1 due to the absorption frequency of -CH2COF 1 The total number of functional groups found from the absorption peaks at .

[0057] Alternatively, the number of -CF2H groups can be determined using a nuclear magnetic resonance apparatus at a temperature of (melting point of the polymer + 20)°C. 19 The F-NMR measurement was performed and determined from the peak integration value of the -CF2H group.

[0058] -CF2H group and the like are functional groups present at the terminal of the main chain or the side chain of the fluorine-containing copolymer and functional groups present in the main chain or the side chain. These functional groups are introduced into the fluorine-containing copolymer, for example, by a chain transfer agent used at the time of producing the fluorine-containing copolymer, a polymerization initiator. For example, in the case where an alcohol is used as the chain transfer agent or a peroxide having a -CH2OH structure is used as the polymerization initiator, -CH2OH is introduced into the terminal of the main chain of the fluorine-containing copolymer. In addition, by polymerizing a monomer having a functional group, the above-mentioned functional group is introduced into the terminal of the side chain of the fluorine-containing copolymer.

[0059] By subjecting the fluorine-containing copolymer having such a functional group to a wet heat treatment, a fluorination treatment, or the like, a fluorine-containing copolymer having the number of functional groups within the above-mentioned range can be obtained. The fluorine-containing copolymer of the present application is more preferably subjected to a wet heat treatment.

[0060] The melting point of the fluorine-containing copolymer is preferably 220°C to 290°C, more preferably 240°C to 280°C. By making the melting point within the above-mentioned range, the moldability of the copolymer is further improved, and a molded body having more excellent transparency, wear resistance, air low permeability, 150°C tensile creep resistance, and durability to repeated load can be obtained.

[0061] In the present application, the melting point can be measured using a differential scanning calorimeter [DSC].

[0062] The methane permeation coefficient of the fluorine-containing copolymer is preferably 9.3 cm 3 mm / (m 2 h-atm) or less, more preferably 8.9 cm 3 mm / (m 2 h-atm) or less. The fluorine-containing copolymer of the present application has excellent methane low permeability due to the appropriate adjustment of the contents of the HFP unit and the PPVE unit, the melt flow rate, and the number of -CF2H.

[0063] In the present application, the methane permeation coefficient can be measured under the conditions of a test temperature of 60°C and a test humidity of 0% RH. The specific measurement of the methane permeation coefficient can be performed by the method described in the examples.

[0064] The fluorine-containing copolymer of the present application can be produced by any one of bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and the like. In these polymerization methods, the conditions such as temperature, pressure, a polymerization initiator, a chain transfer agent, a solvent, and other additives can be appropriately set according to the composition and the amount of the fluorine-containing copolymer desired.

[0065] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical initiator can be used.

[0066] As the oil-soluble radical polymerization initiator, a publicly known oil-soluble peroxide can be used, and as representative examples, the following can be given:

[0067] dialkyl peroxides such as di-n-propyl peroxide, diisopropyl peroxide, di-sec-butyl peroxide, and the like;

[0068] peroxy esters such as tert-butyl peroxy isobutyrate, tert-butyl peroxy pivalate, and the like;

[0069] dialkyl peroxides such as di-tert-butyl peroxide, and the like;

[0070] di[(fluoro (or fluoro-chloro) acyl] peroxides; and the like.

[0071] 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.

[0072] 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-decafluorocotanoyl) peroxide, di(ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptyl-ω-hydrohexadecafluorononyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorocotanoyl-peroxide, ω-hydro-dodecafluoroheptyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutyryl) peroxide, di(trichlorooctafluorohexanoyl) peroxide, di(tetrachloro-undecafluorooctanoyl) peroxide, di(pentachloro-tetradecafluorodecanoyl) peroxide, di(undecachlorotriacontadecafluorodocosanoyl) peroxide, and the like can be given.

[0073] As the water-soluble radical polymerization initiator, a publicly known water-soluble peroxide can be used, and as representative examples, the following can be given: ammonium, potassium, and sodium salts of peroxodisulfuric acid, peroxodibasic acid, perchloric acid, peroxodibasic acid, peroxodicarbonic acid, tert-butyl peroxy maleate, tert-butyl hydroperoxide, and the like. 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.

[0074] If an oil-soluble radical polymerization initiator is used as the polymerization initiator, -COF and -COOH can be avoided, and the total number of -COF and -COOH of the fluorine-containing copolymer can be easily adjusted to the above range, and thus is preferred. In addition, if an oil-soluble radical polymerization initiator is used, there is a tendency that the terminal group containing a carbonyl group and -CH2OH are also easily adjusted to the above range. In particular, it is preferred that the fluorine-containing copolymer is produced by suspension polymerization using an oil-soluble radical polymerization initiator. As the oil-soluble radical polymerization initiator, at least one selected from the group consisting of dialkyl peroxycarbonates and di[fluoro (or fluoro-chloro) acyl]peroxides is preferred, and at least one selected from the group consisting of di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate and di(ω-hydro-dodecafluoroheptyl) peroxide is more preferred.

[0075] As the chain transfer agent, for example, hydrocarbons such as ethane, isopentane, n-hexane, cyclohexane, etc.; aromatic compounds such as toluene, xylene, etc.; ketones such as acetone, etc.; acetic acid esters such as ethyl acetate, butyl acetate, etc.; alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, etc.; mercaptans such as methyl mercaptan, etc.; halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane, chloromethane, etc.; 3-fluorobenzotrifluoride, etc. can be exemplified. The amount of addition can vary depending on the magnitude of the chain transfer constant of the compound used, and is usually used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the solvent.

[0076] For example, in the case where dialkyl peroxycarbonates, di[fluoro (or fluoro-chloro) acyl]peroxides, etc. are used as the polymerization initiator, the molecular weight of the obtained fluorine-containing copolymer becomes excessively high, and sometimes it is not easy to adjust to the desired melt flow rate, but the chain transfer agent can be used to adjust the molecular weight. It is particularly preferred that the fluorine-containing copolymer is produced by suspension polymerization using an oil-soluble radical polymerization initiator and a chain transfer agent such as an alcohol.

[0077] As the solvent, water, a mixed solvent of water and an alcohol, etc. can be exemplified. In addition, the monomer used in the polymerization of the fluorine-containing copolymer of the present application can also be used as the solvent.

[0078] In the suspension polymerization, a fluorine-based solvent can also be used in addition to water. As the fluorine-based solvent, there are, for example, hydrochlorofluoroalkanes such as CH3CCIF2, CH3CC12F, CF3CF2CC12H, CF2C1CF2CFHC1, and the like; chlorofluoroalkanes such as CF2C1CFCCF2CF3, CF3CFC1CFCCF3, and the like; perfluoroalkanes such as perfluorocyclobutane, CF3CF2CF2CF3, CF3CF2CF2CF2CF3, CF3CF2CF2CF2CF2CF3, and the like; and the like, among which perfluoroalkanes are preferred. 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 viewpoints of the suspension property and economy.

[0079] The polymerization temperature is not particularly limited and can be 0 to 100°C. In the case where a peroxide such as a dialkyl carbonate peroxide, a di[fluoro (or fluoro-chloro) acyl] peroxide, or the like is used as the polymerization initiator, or in the case where the decomposition rate of the polymerization initiator is excessively fast, it is preferable to use a relatively low polymerization temperature in which the polymerization temperature is in the range of 0 to 35°C.

[0080] 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.

[0081] As the additive in the polymerization, there are, for example, a suspension stabilizer. As the suspension stabilizer, there are no particular limitations as long as it is a publicly known suspension stabilizer, and methylcellulose, polyvinyl alcohol, or the like can be used. When the suspension stabilizer is used, the suspension particles generated by the polymerization reaction are stably dispersed in the aqueous medium, and therefore, even when 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 less likely to adhere 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, when 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 adhere and the production efficiency can be reduced. The concentration of the suspension stabilizer relative to the aqueous medium can be appropriately adjusted depending on the conditions.

[0082] In the case where an aqueous dispersion liquid containing a fluorine-containing polymer is obtained by a polymerization reaction, a dry 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 a fluorine-containing copolymer is obtained in the form of a slurry by a polymerization reaction, a dry fluorine-containing polymer can be recovered by taking out the slurry from a reaction vessel and washing and drying. By drying, the fluorine-containing copolymer can be recovered in the form of a powder.

[0083] The fluorine-containing copolymer obtained by polymerization can be formed into pellets. As a method of forming into pellets, there is no particular limitation, and a publicly known method can be used. For example, a method of melt-extruding the fluorine-containing copolymer using a single-screw extruder, a twin-screw extruder, a tandem extruder, and cutting into a prescribed length to form 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 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 a publicly known method such as a wire-cutting method, a hot-cutting method, an underwater-cutting method, a sheet-cutting method, and the like can be employed. 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 of 30°C to 200°C, water vapor of 100°C to 200°C, or hot air of 40°C to 200°C.

[0084] 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 wet heat treatment, a method of, for example, using an extruder, feeding air and water while melt-extruding the fluorine-containing copolymer obtained by polymerization can be mentioned. By the wet heat treatment, the thermally unstable functional groups such as -COF, -COOH of the fluorine-containing copolymer 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 the terminal groups containing a carbonyl group and -CH2OH 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.

[0085] The fluorinated copolymer obtained by polymerization can or can not be subjected to fluorination treatment. From the viewpoint of obtaining a molded body having excellent low methane permeability, it is preferable that the fluorinated copolymer is not subjected to fluorination treatment. The fluorination treatment can be performed by bringing the fluorinated copolymer not subjected to fluorination treatment into contact with a fluorine compound. By the fluorination treatment, thermally unstable functional groups such as a terminal group containing a carbonyl group and -CH2OH of the fluorinated copolymer and thermally relatively stable functional groups such as -CF2H are converted into a thermally extremely stable functional group, -CF3. As a result, the total number of the terminal groups containing a carbonyl group and -CH2OH of the fluorinated copolymer can be easily adjusted to the above range.

[0086] As the fluorine compound, there is no particular limitation, and a fluorine radical source that generates a fluorine radical under the fluorination treatment conditions can be given. As the above fluorine radical source, F2gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, a fluorinated halogen (e.g., IF5, CIF3), and the like can be given.

[0087] 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% by mass to 50% by mass with an inactive gas, and more preferably to be diluted to 15% by mass to 30% by mass. As the above inactive gas, nitrogen, helium, argon, and the like can be given, and from the viewpoint of economy, nitrogen is preferable.

[0088] 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 fluorine compound, but it is generally performed at a temperature below the melting point of the fluorinated copolymer, preferably at 20°C to 220°C, and more preferably at 100°C to 200°C. The above fluorination treatment is generally performed for 1 hour to 30 hours, and preferably for 5 hours to 25 hours. The fluorination treatment is preferably a treatment in which the fluorinated copolymer not subjected to fluorination treatment is brought into contact with fluorine gas (F2gas).

[0089] The fluorinated copolymer of the present application can 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, weather-resistant stabilizers, electrically conductive agents, antistatic agents, ultraviolet absorbers, antioxidants, blowing agents, perfumes, oils, softening agents, dehydrofluorination agents, and the like can be given.

[0090] Examples of fillers include silicon dioxide, kaolin, clay, organized clay, talc, mica, aluminum oxide, calcium carbonate, calcium terephthalate, titanium oxide, calcium phosphate, calcium fluoride, lithium fluoride, cross-linked polystyrene, potassium titanate, carbon, boron nitride, carbon nanotubes, and glass fiber. Examples of conductive agents include carbon black. Examples of plasticizers include dioctyl phthalate and pentaerythritol. Examples of processing aids include carnauba wax, sulfone compounds, low molecular weight polyethylene, and fluorine-based additives. Examples of dehydrofluorination agents include organic onium and amidines.

[0091] Furthermore, as the other components, polymers other than the above-mentioned fluorinated copolymers may be used. Examples of the other polymers include fluorinated resins other than the above-mentioned fluorinated copolymers, fluorinated rubbers, and non-fluorinated polymers.

[0092] Examples of methods for producing the composition include dry mixing of the fluorinated copolymer and other components; preliminarily mixing the fluorinated copolymer and other components in a mixer and then melt-kneading them in a kneader, melt extruder or the like.

[0093] The fluorinated copolymers or compositions of the present invention can be used as processing aids, molding materials, and are preferably used as molding materials. Furthermore, aqueous dispersions, solutions, suspensions, and copolymer / solvent systems of the fluorinated copolymers of the present invention can also be used for coating, encapsulation, impregnation, or film casting. However, the fluorinated copolymers of the present invention are preferably used as such molding materials due to their aforementioned properties.

[0094] The fluorinated copolymer of the present invention or the above-mentioned composition may be molded to obtain a molded article.

[0095] The method for molding the above-mentioned fluorinated copolymer or the above-mentioned composition is not particularly limited, and injection molding, extrusion molding, compression molding, blow molding, transfer molding, rotational molding, rotolining molding, etc. can be mentioned. As the molding method, extrusion molding, compression molding or transfer molding are preferred. Extrusion molding or transfer molding are more preferred because they can produce molded bodies with high productivity, and extrusion molding is further preferred. That is, as a molded body, extrusion molding, compression molding, injection molding or transfer molding are preferred. Extrusion molding or transfer molding are more preferred because they can be produced with high productivity, and extrusion molding is further preferred. By molding the fluorinated copolymer of the present invention using extrusion molding or transfer molding, a beautiful molded body can be obtained.

[0096] As a molded body containing the fluorine-containing copolymer of the present application, for example, nuts, bolts, joints, films, bottles, gaskets, wire coverings, tubes, hoses, pipes, valves, sheets, seals, gaskets, tanks, rollers, containers, faucets, connectors, filter housings, filter covers, flowmeters, pumps, wafer carriers, wafer cassettes, and the like can be mentioned.

[0097] The fluorine-containing copolymer of the present application, the above-mentioned composition, or the above-mentioned molded body can be used, for example, for the following uses.

[0098] A film for food packaging, a lining material for fluid delivery lines used in a food manufacturing process, a gasket, a sealing material, a sheet, and the like fluid delivery members for food manufacturing apparatuses;

[0099] A packing for chemicals, a packaging film, a lining material for fluid delivery lines used in a chemical manufacturing process, a gasket, a sealing material, a sheet, and the like reagent delivery members;

[0100] An inner lining member for chemical equipment and semiconductor plant liquid tanks and piping;

[0101] An O-ring / tube / gasket, a valve core material, a hose, a sealing material, and the like used in fuel systems and peripheral devices of automobiles, a hose, a sealing material, and the like used in AT devices of automobiles, and fuel delivery members;

[0102] A flange gasket, a shaft seal, a valve stem seal, a sealing material, a hose, and the like used in carburetors of engines and peripheral devices of automobiles, a brake device hose, an air conditioner hose, a radiator hose, a wire covering material, and the like other automobile members;

[0103] An O-ring, a tube, a gasket, a valve core material, a hose, a sealing material, a roller, a gasket, a diaphragm, a joint, and the like used in semiconductor device liquid delivery members;

[0104] A coating roller, a hose, a tube, an ink container, and the like used in coating and ink members of coating equipment;

[0105] A tube, a hose, a belt, a gasket, a joint, and the like food and beverage delivery members, food packaging materials, glass cooking equipment, and the like used in food and beverage delivery members, food packaging materials, and glass cooking equipment;

[0106] A tube, a hose, and the like used in waste liquid delivery members;

[0107] A tube, a hose, and the like used in high-temperature liquid delivery members;

[0108] A tube, a hose, and the like used in steam piping members;

[0109] A belt and the like used in piping anticorrosion belts wound around the decks of ships and the like;

[0110] Various coating materials such as wire coating materials, optical fiber coating materials, transparent surface coating materials provided on the light incident side surface of a photovoltaic element of a solar cell, and back surface agents;

[0111] Diaphragms of diaphragm pumps and various gaskets and the like sliding members;

[0112] Weather resistant covers for agricultural films, various roof materials, and side walls and the like;

[0113] Coating materials for interior materials used in the construction field, glass-based materials such as non-combustible fire safety glass;

[0114] Lining materials for laminated steel sheets and the like used in the field of home electronics and the like.

[0115] As the fuel delivery member used in the fuel system of the above-mentioned automobile, fuel hoses, filler hoses, evaporator hoses, and the like can be further mentioned. The above-mentioned fuel delivery member can also be used as a fuel delivery member for use in acid-resistant gasoline, alcohol-resistant fuel, and fuel to which gasoline additives such as methyl tert-butyl ether-resistant and amine-resistant gasoline additives are added.

[0116] The above-mentioned chemical plug and packaging film have excellent chemical resistance against acids and the like. In addition, as the above-mentioned liquid delivery member, an anticorrosion tape wound around a chemical equipment pipe can be mentioned.

[0117] As the above-mentioned molded body, radiator tanks, liquid tanks, bellows, bulkheads, rollers, gasoline tanks, waste liquid delivery containers, high-temperature liquid delivery containers, fishing and fish farming tanks, and the like of automobiles can be further mentioned.

[0118] As the above-mentioned molded body, members used in bumpers, door trims, instrument panels, food processing devices, cooking machines, water and oil repellent glass, lighting-related instruments, indicator panels and housings of OA instruments, electrically illuminated signs, display screens, liquid crystal display screens, mobile phones, printer chassis, electrical and electronic parts, groceries, garbage cans, bathtubs, whole bathrooms, ventilation fans, lighting frames, and the like can be further mentioned.

[0119] The molded body containing the fluorine-containing copolymer of the present application is excellent in 50°C wear resistance, low methane permeability, rigidity at 100°C, tensile creep resistance at 130°C, and durability to repeated loads, and thus can be suitably used for pipes, films, or wire coatings and the like.

[0120] The molded body containing the fluorine-containing copolymer of the present application can be suitably used as a compressed member such as a gasket or a seal. The compressed member of the present application can be a gasket or a seal.

[0121] 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-like. 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.

[0122] 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 particularly suitable as a member used in a state of 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.

[0123] As the nonaqueous electrolyte battery, any battery having a nonaqueous electrolyte is acceptable, and examples thereof include a lithium ion secondary battery, a lithium ion capacitor, and the like. In addition, as the member for constituting a nonaqueous electrolyte battery, a sealing member, an insulating member, and the like can be given.

[0124] The nonaqueous electrolyte is not particularly limited, and one or two or more kinds of 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 have an electrolyte. The electrolyte is not particularly limited, and LiClO4, LiAsF6, LiPF6, LiBF4, LiCl, LiBr, CH3SO3Li, CF3SO3Li, cesium carbonate, and the like can be used.

[0125] The compressed member of the present application can be preferably used, for example, as a sealing gasket, a sealing pad, or the like sealing member, an insulating gasket, an insulating pad, or the like insulating member. The sealing member is a member used for preventing the leakage of a liquid or a gas or the intrusion of a liquid or a 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.

[0126] The compressed member of the present application can be suitably used as a sealing member for a nonaqueous electrolyte battery 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. Therefore, in the case where 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.

[0127] The fluorine-containing copolymer of the present application can be suitably used as a material for forming a wire covering. A covered wire having a covering layer containing the fluorine-containing copolymer of the present application has almost no variation in the outer diameter, and thus has excellent electrical properties.

[0128] The coated electric wire has a core wire and a coating layer provided around the core wire and containing the fluorine-containing copolymer of the present application. For example, an extruded body in which the fluorine-containing copolymer of the present application is melt-extruded on a core wire can be used as the coating layer. The coated electric wire is suitable for LAN cable (Ethernet Cable), high-frequency transmission cable, flat cable, heat-resistant cable, and the like, and is particularly suitable for transmission cables such as LAN cable (Ethernet Cable) and high-frequency transmission cable.

[0129] As the material of the core wire, a metal conductor material such as copper or aluminum 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.

[0130] 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), and the like can be used.

[0131] The thickness of the coating layer is preferably 0.1 mm to 3.0 mm. The thickness of the coating layer is also preferably 2.0 mm or less.

[0132] As the 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.

[0133] The coating layer can contain bubbles, which are preferably uniformly distributed in the coating layer.

[0134] The average bubble diameter is not limited, and for example, is preferably 60 μm or less, more preferably 45 μm or less, further preferably 35 μm or less, more 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 electric wire, calculating the diameter of each bubble using image processing, and averaging.

[0135] 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 obtained 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 insertion in the extruder described later, or by selecting the type of gas to be dissolved.

[0136] The coated wire can also have another layer between the above-mentioned core wire and the above-mentioned coating layer, and can further have another layer (an outer layer) around the coating layer. In the case where the coating layer contains bubbles, the wire of the present application can also be 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; and further, a three-layer structure (skin-foam-skin) in which a non-foamed layer is 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 copolymer, a TFE / ethylene-based copolymer, a vinylidene fluoride-based polymer, a polyolefin resin such as polyethylene [PE], a resin such as polyvinyl chloride [PVC], or the like.

[0137] The coated wire can be manufactured, for example, by heating the fluorine-containing copolymer using an extruder, and extruding the fluorine-containing copolymer onto the core wire in a molten state to form the coating layer.

[0138] In forming the coating layer, the above-mentioned coating layer containing bubbles can also be formed by heating the fluorine-containing copolymer, and introducing a gas into the fluorine-containing copolymer in a molten state. As the gas, for example, dichlorofluoromethane, nitrogen, carbon dioxide, or the like, 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 molten fluorine-containing copolymer.

[0139] In addition, the fluorine-containing copolymer of the present application can be suitably used as a material for a high-frequency signal transmission product.

[0140] As the above-mentioned high-frequency signal transmission product, there is no particular limitation as long as it is a product for transmission of high-frequency signals, and examples that can be given are (1) an insulating plate for a high-frequency circuit, an insulating material for a connecting member, a molded plate 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 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.

[0141] In the above product for high frequency signal transmission, the fluorine-containing copolymer of the present application can be suitably used as an insulator from the viewpoint of low tangent of dielectric loss angle.

[0142] As the above (1) molded plate, a printed wiring board is preferable from the viewpoint of obtaining good electrical characteristics. As the above printed wiring board, there are no particular limitations, and examples thereof include printed wiring boards of electronic circuits such as mobile phones, various computers, communication devices, and the like. As the above (2) molded body, a radome is preferable from the viewpoint of low dielectric loss.

[0143] The fluorine-containing copolymer of the present application can be suitably used for a film.

[0144] The film of the present application is useful as a release film. The release film can be produced 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 film, the release film can be produced by melt extrusion molding.

[0145] 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, and molded 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 produced by a melt extrusion molding method.

[0146] The fluorine-containing copolymer of the present application can also be suitably used for a tube, a bottle, or the like.

[0147] The above describes the embodiments, but it is understood that various changes can be made to the modes and details without departing from the spirit and scope of the claims.

[0148] Examples

[0149] Next, the embodiments of the present application are described by citing examples, but the present application is not limited to the examples.

[0150] Each numerical value of the examples is measured by the following method.

[0151] (Content of monomer unit)

[0152] The content of each monomer unit of the fluorine-containing copolymer is 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.).

[0153] (Melt flow rate (MFR))

[0154] The MFR of the fluorine-containing copolymer was determined in accordance with ASTM D-1238 using a melt flow indexer G-01 (manufactured by Orient Techno Co., Ltd.) at 372°C under a load of 5 kg, measuring the mass (g / 10 minutes) of the polymer flowing from a die having an inner diameter of 2 mm and a length of 8 mm per 10 minutes, and thereby calculating the MFR.

[0155] (-CF2H)

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

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

[0158] The dry powder or pellets obtained in the examples and comparative examples were cold-pressed to form 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 analyzer [FT-IR (Spectrum One, manufactured by PerkinElmer 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, the number of functional groups per 1 x 10 6 carbon atoms in the sample was calculated from the absorption peak of a specific functional group appearing in the difference spectrum between the obtained infrared absorption spectrum and the infrared absorption spectrum of a known film, according to the following formula (A).

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

[0160] I: absorbance

[0161] K: correction factor

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

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

[0164] [Table 2]

[0165] Table 2

[0166]

[0167] (-OC(=O)O-R (carbonate group))

[0168] The analysis was performed by the method described in International Publication No. 2019 / 220850. The absorption frequency was set to 1817 cm -1 The number of -OC(=O)O-R (carbonate group) was calculated in the same manner as the calculation method of the number of functional groups N, except that the molar absorption coefficient was set to 170 (l / cm / mol) and the correction coefficient was set to 1426.

[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) was used to perform a first temperature increase from 200°C to 350°C at a temperature increase rate of 10°C / min, followed by cooling from 350°C to 200°C at a cooling rate of 10°C / min, and then performing a second temperature increase from 200°C to 350°C at a temperature increase rate of 10°C / min, and the melting point was found from the peak value of the melting curve generated during the second temperature increase.

[0171] Comparative Example 1

[0172] Into a 174-L volume autoclave with a stirrer, deionized water 40.25 kg and methanol 0.085 kg were charged, and the inside of the autoclave was sufficiently subjected to vacuum nitrogen substitution. After that, the inside of the autoclave was vacuum degassed, and into the autoclave in a vacuum state, HFP 40.25 kg and PPVE 0.31 kg were charged, and the autoclave was heated to 32.0°C. Next, TFE was charged until the internal pressure of the autoclave reached 0.923 MPa, and then 8 mass% of di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) 0.31 kg was charged into the autoclave, and polymerization was started. The internal pressure of the autoclave at the start of polymerization was set to 0.923 MPa, and the set pressure was maintained by continuously adding TFE. Methanol 0.085 kg was added after 1.5 hours from the start of polymerization. DHP 0.31 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, and 0.24 kg was added after 6 hours, and the internal pressure was lowered by 0.001 MPa. After that, DHP 0.07 kg was added every 2 hours until the end of the reaction.

[0173] Note that 0.11 kg of PPVE was additionally charged at the time when the additional amount of TFE reached 8.1 kg, 16.2 kg, and 24.3 kg. Also, 0.085 kg of methanol was additionally charged into the autoclave at the time when the additional amount of TFE reached 6.0 kg and 18.1 kg. Furthermore, the polymerization was terminated at the time when the additional amount of TFE reached 40.25 kg. After the termination of the polymerization, unreacted TFE and HFP were released to obtain a wet powder. Subsequently, the wet powder was washed with pure water and then dried at 150°C for 10 hours to obtain 47.3 kg of a dry powder.

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

[0175] Comparative Example 2

[0176] An autoclave with a stirrer having a volume of 174 L was charged with 40.25 kg of deionized water and 0.112 kg of methanol, and the autoclave was sufficiently subjected to vacuum nitrogen substitution. Subsequently, the autoclave was subjected to vacuum degassing, and 40.25 kg of HFP and 0.48 kg of PPVE were charged into the autoclave in a vacuum state, and the autoclave was heated to 25.5°C. Subsequently, TFE was charged until the internal pressure of the autoclave reached 0.843 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 the polymerization was started. The internal pressure of the autoclave at the start of the polymerization was set to 0.843 MPa, and the set pressure was maintained by continuously charging TFE. Methanol was charged 0.112 kg after 1.5 hours from the start of the polymerization. DHP was charged 1.25 kg after 2 hours and 4 hours from the start of the polymerization, and the internal pressure was lowered by 0.002 MPa each time, and 0.96 kg was charged after 6 hours, and the internal pressure was lowered by 0.002 MPa. Subsequently, DHP was charged 0.25 kg every 2 hours until the termination of the reaction, and the internal pressure was lowered by 0.002 MPa each time.

[0177] Note that 0.12 kg of PPVE was additionally charged at the time when the additional amount of TFE reached 8.1 kg, 16.2 kg, and 24.3 kg. Also, 0.122 kg of methanol was additionally charged into the autoclave at the time when the additional amount of TFE reached 6.0 kg and 18.1 kg. Furthermore, the polymerization was terminated at the time when the additional amount of TFE reached 40.25 kg. After the termination of the polymerization, unreacted TFE and HFP were released to obtain a wet powder. Subsequently, the wet powder was washed with pure water and then dried at 150°C for 10 hours to obtain 45.2 kg of a dry powder.

[0178] The obtained powder was melt-extruded using a screw extruder (trade name: PCM46, manufactured by Kobe Steel, Ltd.) at 370°C to obtain pellets of the copolymer. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0179] Comparative Example 3

[0180] An autoclave with a stirrer having a volume of 174 L was charged with 40.25 kg of deionized water and 0.119 kg of methanol, and the autoclave was sufficiently subjected to vacuum nitrogen substitution. Subsequently, the autoclave was subjected to vacuum degassing, and 40.25 kg of HFP and 0.23 kg of PPVE were charged into the autoclave in a vacuum state, and the autoclave was heated to 30.0°C. Next, TFE was charged until the internal pressure of the autoclave reached 0.887 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 the polymerization was started. The internal pressure of the autoclave at the start of the polymerization was set to 0.887 MPa, and the set pressure was maintained by continuously charging TFE. Methanol was charged 0.119 kg after 1.5 hours from the start of the polymerization. DHP was charged 0.63 kg after 2 hours and 4 hours from the start of the polymerization, and the internal pressure was lowered by 0.001 MPa each time, and 0.48 kg was charged after 6 hours, and the internal pressure was lowered by 0.001 MPa. Subsequently, DHP was charged 0.13 kg every 2 hours until the termination of the reaction, and the internal pressure was lowered by 0.001 MPa each time.

[0181] Note that 0.08 kg of PPVE was additionally charged at the time when the additional amount of TFE reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. In addition, 0.119 kg of methanol was additionally charged into the autoclave at the time when the additional amount of TFE reached 6.0 kg and 18.1 kg, respectively. Furthermore, the polymerization was terminated at the time when the additional amount of TFE reached 40.25 kg. After the termination of the polymerization, unreacted TFE and HFP were released to obtain a wet powder. Subsequently, the wet powder was washed with pure water and then dried at 150°C for 10 hours to obtain 46.6 kg of a dry powder.

[0182] The obtained powder was melt-extruded using a screw extruder (trade name: PCM46, manufactured by Kobe Steel, Ltd.) at 370°C to obtain pellets of the copolymer. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0183] Comparative Example 4

[0184] The amount of PPVE charged before the start of the polymerization was changed to 0.30 kg, the amounts of PPVE additionally charged after the start of the polymerization were changed to 0.10 kg each, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.942 MPa, and otherwise, pellets of the copolymer were obtained in the same manner as in Comparative Example 1. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0185] Comparative Example 5

[0186] The amount of methanol charged before the start of the polymerization was changed to 0.133 kg, the amounts of methanol additionally charged after the start of the polymerization were changed to 0.133 kg each, no PPVE was charged before and after the start of the polymerization, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.906 MPa, and otherwise, pellets of the copolymer were obtained in the same manner as in Comparative Example 3. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0187] Comparative Example 6

[0188] The amount of methanol charged before the start of the polymerization was changed to 0.014 kg, the amounts of methanol additionally charged after the start of the polymerization were changed to 0.014 kg each, the amount of PPVE charged before the start of the polymerization was changed to 0.63 kg, the amounts of PPVE additionally charged after the start of the polymerization were changed to 0.19 kg each, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.911 MPa, and otherwise, pellets of the copolymer were obtained in the same manner as in Comparative Example 3. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0189] Comparative Example 7

[0190] Into a 6L autoclave with a stirrer, 1.65 kg of deionized water was charged, and the autoclave was sufficiently subjected to vacuum nitrogen substitution. After that, the autoclave was vacuum degassed, 1.65 kg of HFP and 16.2 g of PPVE were charged into the autoclave in a vacuum state, and the autoclave was heated to 40.0°C. Next, a gas in which TFE and HFP were mixed at a molar ratio of 91:9 was charged until the internal pressure of the autoclave reached 1.290 MPa, and then 3.5 g of a 40 mass% diisopropyl peroxydicarbonate solution was charged into the autoclave, and polymerization was started. The internal pressure of the autoclave at the start of polymerization was set to 1.290 MPa, and a gas in which TFE and HFP were mixed at a molar ratio of 91:9 was continuously added to maintain the set pressure.

[0191] Note that 1.5 g of PPVE was added at the time when the continuous addition amount of the added gas reached 132 g and 264 g, respectively. After that, the polymerization was ended at the time when the addition amount of the added gas reached 343 g. After the polymerization was ended, unreacted TFE and HFP were released, and a wet powder was obtained. After that, the wet powder was washed with pure water, and dried at 110°C for 10 hours and at 140°C for 5 hours using a hot air drier, and then vacuum dried at 140°C for 24 hours using a vacuum drier, and 311 g of a dry powder was obtained.

[0192] Comparative Example 8

[0193] The amount of methanol charged before the start of polymerization was changed to 0.079 kg, the amount of methanol added in portions after the start of polymerization was changed to 0.079 kg, the amount of PPVE charged before the start of polymerization was changed to 0.36 kg, the amount of PPVE added in portions after the start of polymerization was changed to 0.11 kg, and the set pressure in the autoclave before and after the start of polymerization was changed to 0.957 MPa, and otherwise, a copolymer pellet was obtained in the same manner as in Comparative Example 1. Using the obtained pellet, the HFP content and the PPVE content were measured by the above-described method. The results are shown in Table 3.

[0194] 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% by volume with N2 gas was introduced to the atmosphere 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 operation of introducing and releasing the F2 gas was repeated once every 1 hour, and the reaction was carried out at 200°C for 8 hours. After the completion of the reaction, the inside of 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.

[0195] Example 1

[0196] The amount of the methanol introduced before the start of the polymerization was changed to 0.037 kg, the amounts of the methanol introduced in portions after the start of the polymerization were changed to 0.037 kg each, the amount of the PPVE introduced before the start of the polymerization was changed to 0.24 kg, the amounts of the PPVE introduced in portions after the start of the polymerization were changed to 0.07 kg each, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.928 MPa, and otherwise, copolymer pellets were obtained similarly to Comparative Example 3. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0197] Example 2

[0198] The amount of the methanol introduced before the start of the polymerization was changed to 0.049 kg, the amounts of the methanol introduced in portions after the start of the polymerization were changed to 0.049 kg each, the amount of the PPVE introduced before the start of the polymerization was changed to 0.44 kg, the amounts of the PPVE introduced in portions after the start of the polymerization were changed to 0.13 kg each, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.909 MPa, and otherwise, copolymer pellets were obtained similarly to Comparative Example 3. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0199] Example 3

[0200] The amount of the methanol introduced before the start of the polymerization was changed to 0.043 kg, the amounts of the methanol introduced in portions after the start of the polymerization were changed to 0.043 kg each, the amount of the PPVE introduced before the start of the polymerization was changed to 0.45 kg, the amounts of the PPVE introduced in portions after the start of the polymerization were changed to 0.14 kg each, and the set pressure inside the autoclave before and after the start of the polymerization was changed to 0.897 MPa, and otherwise, copolymer pellets were obtained similarly to Comparative Example 3. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0201] Example 4

[0202] Copolymer pellets were obtained in the same manner as in Comparative Example 3, except that the amount of methanol added before the start of polymerization was changed to 0.116 kg, the amount of methanol added in batches after the start of polymerization was changed to 0.116 kg each, the amount of PPVE added before the start of polymerization was changed to 0.36 kg, the amount of PPVE added in batches after the start of polymerization was changed to 0.11 kg each, and the set pressure inside the autoclave before and after the start of polymerization was changed to 0.957 MPa. Various physical properties of the obtained pellets were measured using the above-mentioned methods. The results are shown in Table 3.

[0203] [Table 3]

[0204] Table 3

[0205]

[0206] "Other (pieces / C10 6 The record "<9" in Table 3 means that the number (total) of -CF2H groups is less than 9. The record "<6" in Table 3 means that the number (total) of the target functional groups is less than 6. The record "ND" in Table 3 means that the peak for the target functional group cannot be confirmed to a quantitative extent.

[0207] Next, the following properties were evaluated using the obtained pellets. The results are shown in Table 4.

[0208] (Abrasion test)

[0209] Using pellets and a hot press molding machine, a sheet-like test piece with a thickness of approximately 0.2 mm was produced, from which a 10 cm × 10 cm test piece was cut. The produced test piece was fixed on the test bench of a Taber abrasion tester (No. 101 Special Taber Abrasion Tester, manufactured by Yasuda Seiki Co., Ltd.) and a wear test was conducted using the Taber abrasion tester under the conditions of a test piece surface temperature of 50°C, a load of 500 g, a CS-10 wear wheel (20 turns with abrasive paper #240), and a rotation speed of 60 rpm. The weight of the test piece was measured after 1000 turns, and the weight of the test piece was further measured after 7000 turns using the same test piece. The wear amount was calculated using the following formula.

[0210] Wear loss (mg) = M1 - M2

[0211] M1: Weight of test piece after 1000 revolutions (mg)

[0212] M2: Test piece weight after 7000 revolutions (mg)

[0213] (methane (CH4) transmission coefficient)

[0214] Pellets and a hot press molding machine were used to produce a sheet-shaped test piece having a thickness of about 0.1 mm. Using the obtained test piece, a determination of the methane transmission was performed according to the method described in JIS K7126-1:2006 using a differential pressure type gas permeability meter (L100-5000 type gas permeability meter, manufactured by Systech Illinois, Inc.). The value of the methane transmission at a transmission area of 50.24 cm 2 , a test temperature of 60°C, and a test humidity of 0% RH was obtained. Using the obtained methane transmission and the thickness of the test piece, the methane transmission coefficient was calculated by the following equation.

[0215] methane transmission coefficient (cm 3 / (m 2 ·h·atm)) = GTR x d / 24

[0216] GTR: methane transmission (cm 3 / (m 2 ·24h·atm))

[0217] d: thickness of test piece (mm)

[0218] (100°C load deflection)

[0219] Pellets and a hot press molding machine were used to produce a sheet-shaped test piece having a thickness of about 4 mm, and an 80 x 10 mm test piece was cut therefrom and heated at 100°C for 20 hours using an electric furnace. Except for using the obtained test piece, a test was performed according to the method described in JIS K-K7191-1 using a heat distortion tester (manufactured by Yasuda Seiki Mfg. Co., Ltd.) under 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. The load deflection was found by the following equation. A sheet having a small load deflection at 100°C has excellent rigidity at 100°C.

[0220] load deflection (%) = a2 / a1 x 100

[0221] a1: thickness of test piece before test (mm)

[0222] a2: deflection amount at 100°C (mm)

[0223] (tensile creep test)

[0224] TMA-7100 manufactured by Hitachi High-Technologies Corporation. Pellets and a hot press molding machine were used to produce a sheet having a thickness of about 0.1 mm, and a sample having a width of 2 mm and a length of 22 mm was produced from the sheet. The sample was installed in a measuring jig with a jig distance of 10 mm. The sample was loaded with a crosshead load of 3.71 N / mm 2 at 130°C, and the displacement of the length (mm) of the sample from the time 90 minutes after the start of the test to the time 600 minutes after the start of the test was measured, and the ratio of the displacement of the length (mm) to the initial sample length (10 mm) (tensile creep strain (%)) was calculated. A sheet having a small tensile creep strain (%) measured at 130°C for 600 minutes is less likely to elongate even under a tensile load for a long time in a high-temperature environment, and has excellent high-temperature tensile creep resistance (130°C).

[0225] (6 million cycle tensile strength)

[0226] A 6 million cycle tensile strength was measured using a fatigue tester MMT-250NV-10 manufactured by Shimadzu Corporation. Pellets and a hot press molding machine were used to produce a sheet having a thickness of about 2.4 mm, and a dumbbell-shaped sample (thickness 2.4 mm, width 5.0 mm, and measurement portion length 22 mm) was produced using an ASTM D1708 micro dumbbell. The sample was installed in a measuring jig, and the measuring jig was set in a constant temperature bath at 110°C in a state where the sample was installed. Tensile stretching in a single axis direction was repeatedly performed at a stroke of 0.2 mm and a frequency of 100 Hz, and the tensile strength of each stretching (tensile strength at a stroke of +0.2 mm, unit: N) was measured.

[0227] A sheet having a high 6 million cycle tensile strength maintains a high tensile strength even after being loaded for 6 million times, and has excellent durability to repeated loads (110°C).

[0228] (extrusion pressure)

[0229] An extrusion pressure was measured using a double capillary rheometer RHEOGRAPH 25 (manufactured by Goettfert). A primary die having an inner diameter of 1 mm and L / D = 16 and a secondary die having an inner diameter of 1 mm and L / D < 1 were used, and the pressure value in the cylinder after extruding for 10 minutes at a shear rate of 20 sec -1 at a measurement temperature of 350°C, a remaining heat time of 10 minutes after the pellets were fed was corrected by Bagley, and thereby the extrusion pressure was obtained. A copolymer having a low extrusion pressure has excellent moldability such as extrusion moldability and injection moldability.

[0230] (film moldability)

[0231] A film was produced using An extruder (manufactured by JISU) and a T-die were used to mold the pellets into a film. The extrusion molding conditions were as follows.

[0232] a) winding speed: 0.4 m / min

[0233] b) roll temperature: 120°C

[0234] c) film width: 70 mm

[0235] d) thickness: 0.25 mm

[0236] e) extrusion conditions:

[0237] • single screw extrusion molding machine with a barrel shaft diameter of 14 mm and L / D of 20

[0238] Set temperature of the extruder: barrel section C-1 (330°C), barrel section C-2 (350°C), barrel section C-3 (365°C), T-die section (370°C)

[0239] The extrusion molding of the fluorine-containing copolymer was continued until the fluorine-containing copolymer was stably extruded from the molding machine. Next, a film (width 70 mm) having a length of 5 m or more was produced by extrusion molding the fluorine-containing copolymer in a manner having a thickness of 0.25 mm. A test piece (length 1 m, width 70 mm) for measuring the variation in thickness was produced by cutting a portion of 4 to 5 m from the end of the obtained film. The thickness of a total of three points at the center point in the width direction of the end of the produced film and two points 25 mm apart from the center point in the width direction was measured. Further, the thickness of a total of nine points at three center points arranged at intervals of 25 cm from the center point in the width direction of the end of the film toward the other end and two points 25 mm apart from each center point in the width direction was measured. In a total of 12 measured values, the case where the number of measured values outside the range of ±10% of 0.25 mm was one or less was marked as O, and the case where the number of measured values outside the range of ±10% of 0.25 mm was two or more was marked as X.

[0240] (pipe molding property)

[0241] Using An extruder (manufactured by TANABE PLASTICS MACHINERY) was used to extrusion mold the pellets to obtain a pipe having an outer diameter of 10.0 mm and a wall thickness of 1.0 mm. The extrusion molding conditions were as follows.

[0242] a) die inner diameter: 25 mm

[0243] b) mandrel outer diameter: 13 mm

[0244] c) sizing die inner diameter: 10.5 mm

[0245] d) pulling speed: 0.4 m / min

[0246] e) outer diameter: 10.0 mm

[0247] f) wall thickness: 1.0 mm

[0248] g) extrusion conditions:

[0249] • single screw extruder with barrel shaft diameter = 30 mm, L / D = 22

[0250] Setting temperature of extruder: barrel section C-1 (350°C), barrel section C-2 (370°C), barrel section C-3 (380°C), head section H-1 (390°C), die section D-1 (390°C), die section D-2 (390°C)

[0251] The obtained tube was observed, and evaluated according to the following criteria. The appearance of the tube was confirmed by visual observation.

[0252] O: good appearance

[0253] X: the cross section was not circular, flatness or uneven thickness was observed, and the appearance was poor.

[0254] (Wire coating molding conditions)

[0255] Using A wire coating extruder (manufactured by Tanabe Plastics Machinery Co., Ltd.) was used to extrude a fluorine-containing copolymer onto a copper conductor having a conductor diameter of 1.00 mm at a coating thickness described below, to obtain a coated wire. The wire coating extrusion molding conditions are as follows.

[0256] a) core conductor: conductor diameter 1.00 mm

[0257] b) coating thickness: 0.70 mm

[0258] c) coated wire diameter: 2.40 mm

[0259] d) wire pulling speed: 3 m / min

[0260] e) extrusion conditions:

[0261] • single screw extruder with barrel shaft diameter = 30 mm, L / D = 22

[0262] • die (inner diameter) / sheet (outer shape) = 24.0 mm / 10.0 mm

[0263] Setting temperature of extruder: barrel section C-1 (340°C), barrel section C-2 (375°C), barrel section C-3 (390°C), head section H (400°C), die section D-1 (400°C), die section D-2 (400°C). The core wire preheating was set to 80°C.

[0264] (Variation in outer diameter)

[0265] The outer diameter of the obtained coated electric wire was measured for one hour continuously using an outer diameter measuring device (ODAC 18XY manufactured by Zumbach). The third digit after the decimal point of the outer diameter value deviating most from the prescribed outer diameter value (2.40 mm) was rounded off, and thus the variation in outer diameter was calculated. The proportion of the absolute value of the difference between the prescribed outer diameter and the variation in outer diameter to the prescribed outer diameter (2.40 mm) (variation rate in outer diameter) was calculated, and evaluated according to the following criteria.

[0266] (Variation rate in outer diameter (%)) = |(variation in outer diameter) - (prescribed outer diameter)| / (prescribed outer diameter) x 100

[0267] ±1%: variation rate in outer diameter is 1% or less

[0268] ±2%: variation rate in outer diameter is more than 1% and 2% or less

[0269] x: variation rate in outer diameter is more than 2%

[0270] [Table 4]

[0271] Table 4

[0272]

Claims

1. A fluorinated copolymer comprising tetrafluoroethylene units, hexafluoropropylene units and perfluoro(propyl vinyl ether) units, wherein: The content of tetrafluoroethylene units is 86.6% to 90.0% by mass relative to all monomer units. The content of the hexafluoropropylene unit is 9.5% by mass to 12.2% by mass relative to the total monomer units. The content of the perfluoro(propyl vinyl ether) unit is 0.5% to 1.4% by mass relative to the total monomer units. The melt flow rate at 372°C and 5kg load is 0.8g / 10min to 4.0g / 10min. -The amount of CF2H relative to every 10 6 The number of carbon atoms in the main chain exceeds 50.

2. The fluorinated copolymer according to claim 1, wherein The content of the hexafluoropropylene unit is 10.0% by mass to 11.5% by mass based on the total monomer units.

3. The fluorinated copolymer according to claim 1 or 2, wherein The content of the perfluoro(propyl vinyl ether) unit is 0.6% by mass to 1.3% by mass based on the total monomer units.

4. The fluorinated copolymer according to claim 1 or 2, wherein The melt flow rate at 372° C. and a load of 5 kg is 1.0 g / 10 min to 3.5 g / 10 min.

5. The fluorinated copolymer according to claim 1 or 2, wherein The total number of carbonyl-containing terminal groups, -CF=CF2 and -CH2OH is relative to every 10 6 The number of carbon atoms in the main chain is 50 or less. An extrusion molded product comprising the fluorinated copolymer according to any one of claims 1 to 5.

7. A transfer molded article comprising the fluorinated copolymer according to any one of claims 1 to 5. 8 . A covered electric wire comprising a covering layer comprising the fluorinated copolymer according to claim 1 .

9. A molded article comprising the fluorinated copolymer according to any one of claims 1 to 5, wherein The molded article is a tube, a film, or a wire coating.

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