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 6.0 to 7.6 mass% relative to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5 to 2.4 mass% relative to the total monomer units, and the melt flow rate at 372°C is 4.5 to 9.5 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 is not easily deformed even in a molten state, which can be molded by an injection molding method to obtain a beautiful injection molded body, which can be molded by an extrusion molding method to form a very thick coating layer on a core wire having a very large diameter with a uniform thickness, which can be molded by an extrusion molding method to obtain a beautiful tube, and which can obtain a molded body excellent in wear resistance at 110°C, low oxygen permeability, rigidity at a high temperature of 85°C, tensile creep resistance at 130°C, and 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 6.0% by mass to 7.6% by mass with respect to the total monomer units, the content of the perfluoro(propyl vinyl ether) units is 1.5% by mass to 2.4% by mass with respect to the total monomer units, and the melt flow rate at 372°C is 4.5 g / 10 minutes to 9.5 g / 10 minutes.

[0010] The content of the hexafluoropropylene units with respect to the total monomer units is preferably 6.2% by mass to 7.2% 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 2.2% by mass.

[0012] The melt flow rate at 372°C is preferably 5.0 g / 10 minutes to 8.9 g / 10 minutes.

[0013] The total number of end groups containing a carbonyl group, -CF=CF2, and -CH2OH is preferably 90 or less per 10 6 main chain carbon atoms.

[0014] The number of -CF2H is preferably 90 or less per 10 6 main chain carbon atoms.

[0015] Further, according to the present application, there is provided an injection-molded body containing the above-mentioned fluorine-containing copolymer.

[0016] Further, according to the present application, there is provided a coated electric wire having a coating layer containing the above-mentioned fluorine-containing copolymer.

[0017] 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 an injector, a tube, a film, or a coated electric wire.

[0018] Effects of the Invention

[0019] According to the present application, it is possible to provide a fluorine-containing copolymer which is not easily deformed even in a molten state, can be molded by an injection molding method to obtain a beautiful injection-molded body, can be molded by an extrusion molding method to form a very thick coating layer on a core wire having a very large diameter at a uniform thickness, can be molded by an extrusion molding method to obtain a beautiful tube, and can obtain a molded body which is excellent in 110°C wear resistance, oxygen low permeability, rigidity at 85°C high temperature, 130°C tensile creep resistance, and durability to repeated load. DETAILED DESCRIPTION

[0020] Hereinafter, a specific embodiment of the present application will be described in detail, but the present application is not limited to the following embodiment.

[0021] The fluorine-containing copolymer of the present application contains tetrafluoroethylene (TFE) units, hexafluoropropylene (HFP) units, and perfluoro(propyl vinyl ether) (PPVE) units.

[0022] 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 heat resistance and the like are inferior to PTFE. Therefore, in Patent Document 1, as a fluorocarbon polymer in which these disadvantages are improved, the above-mentioned terpolymer is proposed.

[0023] However, the existing terpolymers are difficult to obtain a molded article excellent in any one of 110°C wear resistance, low oxygen permeability, rigidity at 85°C, 130°C tensile creep resistance, and durability to repeated load. For example, the molded article obtained from the terpolymer described in Patent Document 1 is poor in any one of 110°C wear resistance, low oxygen permeability, and rigidity at high temperature, and it is a problem to balance these properties. Therefore, the existing terpolymers are repeatedly used, and when used as a material for forming a molded article such as a syringe for holding an anaerobic drug solution at a high temperature, the terpolymers do not have sufficiently satisfactory properties.

[0024] It was found that by adjusting the contents of HFP units and PPVE units in the fluorine-containing copolymer containing TFE units, HFP units, and PPVE units, and the melt flow rate to extremely limited ranges, the 110°C wear resistance, low oxygen permeability, rigidity at 85°C, 130°C tensile creep resistance, and durability to repeated load of the molded article obtained from the fluorine-containing copolymer are remarkably improved. Furthermore, by molding the fluorine-containing copolymer of the present application using an injection molding method, a beautiful injection molded article can be obtained.

[0025] Furthermore, by molding the fluorine-containing copolymer of the present application using an extrusion molding method, a very thick coating layer can be formed on a core wire having a very large diameter with a uniform thickness, a beautiful tube can be obtained, and a thin film having a uniform thickness can be molded at a high molding speed. Thus, the fluorine-containing copolymer of the present application can be used not only as a material for a syringe or the like, but also for a tube, a film, or wire coating, and the like.

[0026] Furthermore, the fluorine-containing copolymer of the present application is less deformed by its own weight even in a molten state, and therefore even when molded into a thick tube, the obtained tube has a clean cross section and a uniform thickness.

[0027] 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.

[0028] The content of the HFP unit of the fluorine-containing copolymer is preferably 6.0 to 7.6% by mass, more preferably 6.1% by mass or more, further more preferably 6.2% by mass or more, preferably 7.5% by mass or less, more preferably 7.4% by mass or less, further more preferably 7.3% by mass or less, still further more preferably 7.2% by mass or less, particularly further more preferably 6.9% by mass or less, particularly preferably 6.8% by mass or less, most preferably 6.7% by mass or less, relative to the total monomer units. If the content of the HFP unit is too small, a molded article excellent in 110°C wear resistance cannot be obtained. If the content of the HFP unit is too large, a molded article excellent in rigidity at 85°C, tensile creep resistance at 130°C, and durability to repeated load cannot be obtained.

[0029] The content of the PPVE unit of the fluorine-containing copolymer is preferably 1.5 to 2.4% by mass, more preferably 1.6% by mass or more, further more preferably 1.7% by mass or more, preferably 2.3% by mass or less, more preferably 2.2% by mass or less, further more preferably 2.1% by mass or less, particularly preferably 2.0% by mass or less, relative to the total monomer units. If the content of the PPVE unit is too small, a molded article excellent in 110°C wear resistance cannot be obtained. If the content of the PPVE unit is too large, a molded article excellent in oxygen permeability and rigidity at 85°C cannot be obtained.

[0030] The content of the TFE unit of the fluorine-containing copolymer is preferably 90.0% by mass or more, more preferably 90.2% by mass or more, further more preferably 90.4% by mass or more, still further more preferably 90.5% by mass or more, particularly preferably 90.6% by mass or more, most preferably 91.3% by mass or more, preferably 92.5% by mass or less, more preferably 92.4% by mass or less, further more preferably 92.3% by mass or less, still further more preferably 92.2% by mass or less, particularly preferably 92.1% 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 content of other monomer units is 100% by mass.

[0031] 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.

[0032] 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.

[0033] As the fluorine-containing monomer, it is preferably a monomer selected from the group consisting of chlorotrifluoroethylene, fluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoroisobutylene, CH2=CZ 1(CF2) n Z 2 (incidentally, Z 1 is H or F, Z 2 is H, F or Cl, and n is an integer of 1 to 10), CF2=CF-ORf 1 (incidentally, Rf 1 is a perfluoroalkyl group having 1 to 8 carbon atoms), CF2=CF-O-CH2-Rf 2 (incidentally, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms), perfluoro-2,2-dimethyl-l,3-dioxol [PDD], and perfluoro-2-methylene-4-methyl-l,3-dioxolane [PMD].

[0034] As the monomer represented by CH2=CZ 1 (CF2) n Z 2 , CH2=CH-C4F9, CH2=CH-C6F 13 , CH2=CF-C3F6H, etc. can be given.

[0035] As the perfluoro(alkyl vinyl ether) represented by CF2=CF-ORf 1 , CF2=CF-OCF3, CF2=CF-OCF2CF3, etc. can be given.

[0036] As the non-fluorine-containing monomer, a hydrocarbon-based monomer capable of copolymerizing with TFE, HFP and PPVE can be given. 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 given.

[0037] As the non-fluorine-containing monomer, a hydrocarbon-based monomer capable of copolymerizing with TFE, HFP and PPVE can be given. 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 given.

[0038] As the content of the other monomer unit in the fluorine-containing copolymer of the present application, it is preferably 0 to 2.5 mass% with respect 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.

[0039] The melt flow rate (MFR) of the fluorine-containing copolymer is preferably 4.5 g / 10 minutes or more, more preferably 4.6 g / 10 minutes or more, further more preferably 4.7 g / 10 minutes or more, still further more preferably 4.8 g / 10 minutes or more, yet further more preferably 4.9 g / 10 minutes or more, particularly further more preferably 5.0 g / 10 minutes or more, especially preferably 6.0 g / 10 minutes or more, most preferably 7.0 g / 10 minutes or more, and preferably 9.4 g / 10 minutes or less, more preferably 9.0 g / 10 minutes or less, further more preferably 8.9 g / 10 minutes or less, particularly preferably 7.9 g / 10 minutes or less, most preferably 7.0 g / 10 minutes or less. If the MFR is too low, a molded article having low oxygen permeability, excellent rigidity at a high temperature of 85°C cannot be obtained, and in addition, a beautiful molded article cannot be obtained by injection molding. If the MFR is too high, a molded article having excellent wear resistance at 110°C cannot be obtained. Furthermore, if the MFR is too high, the fluorine-containing copolymer is easily deformed in a molten state, and a thick pipe or the like having a uniform thickness cannot be obtained. Furthermore, a beautiful injection molded article cannot be obtained by injection molding, and a very thick coating layer cannot be formed on a core wire having a very large diameter in a uniform thickness by extrusion molding.

[0040] 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.) as the mass (g / 10 minutes) of a 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.

[0041] The MFR can be adjusted by adjusting the kind and amount of a polymerization initiator used when the monomers are polymerized, the kind and amount of a chain transfer agent, and the like.

[0042] 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 preferably 90 or less per 10 6 main chain carbon atoms. The total number of -COF, -COOH, and -CH2OH is 70 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, or less than 6, in the order of preference. By making the total number of -COF, -COOH, and -CH2OH within the above range, a molded article which is less likely to cause elution of a fluoride ion into a liquid medicine such as hydrogen peroxide water can be obtained. The total number of -COF, -COOH, and -CH2OH can be adjusted, for example, by appropriately selecting the kind of a polymerization initiator or a chain transfer agent, or by a subsequent moisture heat treatment or fluorination treatment of the fluorine-containing copolymer.

[0043] The fluorine-containing copolymer of the present application can or can not have a terminal group containing a carbonyl group, -CF=CF2, or -CH2OH. The total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH in the fluorine-containing copolymer of the present application is preferably 90 or less per 10 6 carbon atoms of the main chain. The total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH is, in order of preference, 70 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, or less than 12. By having the total number of terminal groups containing a carbonyl group, -CF=CF2, and -CH2OH within the above range, a molded body that is not likely to cause elution of fluoride ions into a liquid such as hydrogen peroxide water can be obtained. 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 wet heat treatment or fluorination treatment of the fluorine-containing copolymer described later.

[0044] 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, etc. used in the production of the fluorine-containing copolymer, and is, for example, an alkyl group having 1 to 6 carbon atoms such as -CH3.

[0045] The fluorine-containing copolymer of the present application can or can not have -0(C=0)0-R (R is an alkyl group). The total number of -0(C=0)0-R (R is an alkyl group) in the fluorine-containing copolymer of the present application is preferably 90 or less per 10 6 carbon atoms of the main chain. The total number of -0(C=0)0-R (R is an alkyl group) is, in order of preference, 70 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, or 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 wet heat treatment or fluorination treatment of the fluorine-containing copolymer described later.

[0046] The fluorine-containing copolymer of the present application can or can not have -CF2H. The number of -CF2H in the fluorine-containing copolymer is preferably 90 or less per 10 6The number of main chain carbon atoms is preferably 90 or less. The number of -CF2H groups is 70 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, or less than 9, in the order of preference. By setting the number of -CF2H groups within the above range, a molded body that is less likely to cause elution of fluoride ions into a liquid such as hydrogen peroxide water can be obtained. The number of -CF2H groups 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 later.

[0047] The type of the above functional group can be identified and the number of functional groups can be measured using infrared spectroscopy.

[0048] As for the number of functional groups, specifically, the following method is used for measurement. First, the above fluorine-containing copolymer is cold-pressed to produce a film having a thickness of 0.25 to 0.30 mm. The film is analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above fluorine-containing copolymer, and a differential spectrum from a background spectrum of a completely fluorinated functional group-free sample is obtained. The number of functional groups per 1 x 10 6 carbon atoms N in the above fluorine-containing copolymer is calculated from the absorption peak of a specific functional group appearing in the differential spectrum according to the following formula (A).

[0049] N = I x K / t (A)

[0050] I: absorbance

[0051] K: correction factor

[0052] t: thickness of the film (mm)

[0053] For reference, as for some 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.

[0054] [Table 1]

[0055] Table 1

[0056]

[0057] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2are lower than those of -CF2H, -COF, free -COOH and bonded -COOH, -COOCH3, and -CONH2, respectively, by several tens of Kaysers (cm -1 ).

[0058] For example, the number of functional groups of -COF is the total number of functional groups calculated from the number of functional groups calculated from the absorption peak at an absorption frequency of 1883 cm -1 -1 of -CF2COF and the number of functional groups calculated from the absorption peak at an absorption frequency of 1840 cm -1 -1 of -CH2COF.

[0059] In addition, the number of -CF2H groups can also be determined by 19F-NMR measurement using a nuclear magnetic resonance device with the measurement temperature set to (the melting point of the polymer + 20) °C, and the number of -CF2H groups is calculated from the peak integral value of -CF2H groups.

[0060] -CF2H groups and the like are functional groups present at the terminal end of the main chain or the terminal end of 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 or a polymerization initiator used when the fluorine-containing copolymer is produced. For example, in the case where an alcohol is used as a chain transfer agent or a peroxide having a -CH2OH structure is used as a polymerization initiator, -CH2OH is introduced into the terminal end of the main chain of the fluorine-containing copolymer. In addition, by polymerizing a monomer having a functional group, the above-described functional group is introduced into the terminal end of the side chain of the fluorine-containing copolymer.

[0061] 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 a number of functional groups within the above-described range can be obtained. The fluorine-containing copolymer of the present application is preferably subjected to a wet heat treatment or a fluorination treatment, and more preferably to a fluorination treatment. The fluorine-containing copolymer of the present application also preferably has a -CF3 terminal group.

[0062] The melting point of the fluorine-containing copolymer is preferably 220°C to 290°C, and more preferably 240°C to 280°C. By having the melting point within the above-described range, deformation in the molten state is less likely to occur, a beautiful injection-molded body can be obtained by molding by an injection molding method, a very thick coating layer can be formed at a uniform thickness on a core wire having a very large diameter by molding by an extrusion molding method, a beautiful tube can be obtained by molding by an extrusion molding method, and a molded body having more excellent 110°C wear resistance, oxygen permeability, rigidity at 85°C, 130°C tensile creep resistance, and durability to repeated loads can be obtained.

[0063] In the present application, the melting point can be measured using a differential scanning calorimeter [DSC].

[0064] The oxygen permeability coefficient of the fluorine-containing copolymer is preferably 790 cm 3 -1 mm / (m 2• 24 h • atm) or less. The fluorine-containing copolymer of the present application has excellent oxygen low permeability due to appropriate adjustment of the contents of HFP units and PPVE units, and the melt flow rate (MFR). Therefore, for example, a syringe using the fluorine-containing copolymer of the present application can be appropriately used for a drug solution which is desired to be kept from mixing in oxygen from the outside.

[0065] In the present application, the oxygen permeation coefficient can be measured under the conditions of a test temperature of 70°C and a test humidity of 0% RH. The specific measurement of the oxygen permeation coefficient can be performed by the method described in the examples.

[0066] The amount of dissolved 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 more preferably 2.8 ppm or less on a mass basis. By making the amount of dissolved fluorine ions within the above range, a molded body using the fluorine-containing copolymer of the present application, in the case of using the obtained molded body as a syringe for keeping a drug solution, it is possible to suppress the dissolution of fluorine ions into the drug solution.

[0067] 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 10 pieces of molded bodies (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.

[0068] 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, each condition 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 amount of the fluorine-containing copolymer desired.

[0069] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical initiator can be used.

[0070] 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:

[0071] dialkyl peroxycarbonates such as di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and the like;

[0072] peroxy esters such as tert-butyl peroxyisobutyrate, tert-butyl peroxyneopentanoate, and the like;

[0073] dialkyl peroxides such as di-tert-butyl peroxide, and the like;

[0074] di[fluoro (or fluorochloro) acyl] peroxides; and the like.

[0075] As the di[fluoro (or fluoro-chloro) acyl] peroxide, diacyl peroxide represented by [(RfCOO)-]2 (Rf is perfluoroalkyl, ω-hydroperfluoroalkyl or fluoro-chloroalkyl) can be given.

[0076] As the di[fluoro (or fluoro-chloro) acyl] peroxide, 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(trichloro-octafluorocaproyl) peroxide, di(tetrachloro-undecafluorooctanoyl) peroxide, di(pentachloro-tetradecafluorodecanoyl) peroxide, di(undecachlorotriacontadecafluorodocosanoyl) peroxide, and the like can be given.

[0077] As the water-soluble radical polymerization initiator, a publicly known water-soluble peroxide can be used, and for example, ammonium salt, potassium salt, sodium salt of peroxymonosulfuric acid, peroxymonoboric acid, perchloric acid, peroxymonophosphoric acid, peroxymonocarbonic acid, t-butyl peroxy maleate, t-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.

[0078] 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 it 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 peroxydicarbonate and di[fluoro (or fluoro-chloro) acyl] peroxide 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.

[0079] As the chain transfer agent, there can be mentioned, for example, hydrocarbons such as ethane, isopentane, n-hexane, cyclohexane, etc.; aromatic hydrocarbons 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. The amount of addition can be varied depending on the magnitude of the chain transfer constant of the compound used, and is generally used in the range of 0.01 part by mass to 20 parts by mass with respect to 100 parts by mass of the solvent.

[0080] For example, in the case where peroxide carbonate dialkyl esters, 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 it is sometimes difficult to adjust to the 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.

[0081] As the solvent, there can be mentioned water, a mixed solvent of water and an alcohol, etc. In addition, the monomer used in the polymerization of the fluorine-containing copolymer of the present application can also be used as the solvent.

[0082] In the suspension polymerization, a fluorine-based solvent can also be used in addition to water. As the fluorine-based solvent, there can be mentioned hydrochlorofluoroalkanes such as CH3CCIF2, CH3CC12F, CF3CF2CC12H, CF2C1CF2CFHC1, etc.; chlorofluoroalkanes such as CF2C1CFCF2CF3, CF3CFC1CF1CF3, etc.; perfluoroalkanes such as perfluorocyclobutane, CF3CF2CF2CF3, CF3CF2CF2CF2CF3, CF3CF2CF2CF2CF2CF3, etc., and among them, perfluoroalkanes are preferable. From the aspects of the suspension property and economy, the amount of the fluorine-based solvent is preferably 10 parts by mass to 100 parts by mass with respect to 100 parts by mass of the solvent.

[0083] The polymerization temperature is not particularly limited, and can be 0 to 100°C. In addition, in the case where the decomposition speed of the polymerization initiator is excessively fast such as in the case where peroxide carbonate dialkyl esters, di[fluoro (or fluoro-chloro) acyl] peroxides, etc. are used as the polymerization initiator, it is preferable to adopt a lower polymerization temperature in the range of 0°C to 35°C or the like.

[0084] The polymerization pressure is appropriately determined depending on the kind of solvent used, the amount of solvent, the vapor pressure, other polymerization conditions such as the polymerization temperature, and the like, and can generally be 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.

[0085] As the additive in the polymerization, a suspension stabilizer can be mentioned, for example. 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. When a suspension stabilizer is used, the suspension particles generated by the polymerization reaction are stably dispersed in the aqueous medium, and thus even when a reaction vessel 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 vessel. Thus, a reaction vessel 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 vessel 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 with respect to the aqueous medium can be appropriately adjusted depending on the conditions.

[0086] 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 addition, 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.

[0087] 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.

[0088] 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, for example, an extruder is used, and the fluorine-containing copolymer obtained by polymerization is melted and extruded while air and water are supplied can be given. By the wet heat treatment, thermally unstable functional groups such as -COF, -COOH of the fluorine-containing copolymer can be converted to -CF2H which is relatively thermally stable, and the total number of -COF and -COOH of the fluorine-containing copolymer and the total number of 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 caused by the alkali metal salt should be avoided.

[0089] The fluorine-containing copolymer obtained by polymerization can also be subjected to fluorination treatment, and can also not be subjected to fluorination treatment. From the viewpoint of obtaining a molded body which is less likely to cause elution of fluorine ions into a chemical liquid such as hydrogen peroxide water, it is preferable that the fluorine-containing copolymer be subjected to fluorination treatment. The fluorination treatment can be performed by bringing the fluorine-containing copolymer which has not been subjected to fluorination treatment into contact with a fluorine-containing compound. By the fluorination treatment, thermally unstable functional groups such as terminal groups containing a carbonyl group and -CH2OH of the fluorine-containing copolymer and functional groups such as -CF2H which are relatively thermally stable can be converted to -CF3 which is extremely thermally stable. As a result, the total number of terminal groups containing a carbonyl group and -CH2OH of the fluorine-containing copolymer can be easily adjusted to the above range.

[0090] As the fluorine-containing compound, there is no particular limitation, and a fluorine radical source which generates a fluorine radical under the conditions of the fluorination treatment can be given. As the above fluorine radical source, F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, fluorinated halogen (for example, IF5, ClF3), and the like can be given.

[0091] The fluorine radical source such as F2 gas 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.

[0092] The conditions of the fluorination treatment are not particularly limited, and the fluorine-containing copolymer in a molten state can be brought into contact with the fluorine-containing compound, but it is generally performed at a temperature of 20°C to 220°C, preferably 100°C to 200°C, and more preferably 100°C to 200°C, below the melting point of the fluorine-containing copolymer. 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 fluorine-containing copolymer which has not been subjected to fluorination treatment is brought into contact with fluorine gas (F2 gas).

[0093] The fluorine-containing 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.

[0094] 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 aids, and the like can be given. As the dehydrofluorination agents, organo-oniums, amidines, and the like can be given.

[0095] In addition, as the above other components, other polymers other than the above fluorine-containing copolymer can also be used. As the other polymers, fluororesins other than the above fluorine-containing copolymer, fluororubbers, non-fluorinated polymers, and the like can be given.

[0096] As the method for producing the above composition, a method in which the fluorine-containing copolymer and the other components are mixed in dry form, a method in which the fluorine-containing 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.

[0097] The fluorine-containing 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 fluorine-containing copolymer of the present application can also be used as a coating material, and can be applied by coating, or used for encapsulation, impregnation, film casting. However, the fluorine-containing copolymer of the present application has the above properties, and is preferably used as the above molding material.

[0098] The fluorine-containing copolymer of the present application or the above composition can also be molded to obtain a molded body.

[0099] 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 beautiful molded body can be obtained.

[0100] 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.

[0101] 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.

[0102] 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;

[0103] 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;

[0104] a lining member for the inner surface of a liquid tank and a pipe for a chemical plant and a semiconductor factory;

[0105] 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;

[0106] 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 for an automobile;

[0107] 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 device;

[0108] A coating and ink member such as a coating roll, hose, tube, ink container, and the like for a coating apparatus;

[0109] A pipe, hose, belt, gasket, joint, and the like for food and beverage delivery, a food packaging material, and a glass cooking appliance;

[0110] A pipe, hose, and the like for waste liquid delivery;

[0111] A pipe, hose, and the like for high-temperature liquid delivery;

[0112] A pipe, hose, and the like for steam piping;

[0113] An anticorrosion tape such as a tape wound around piping on a deck of a ship or the like;

[0114] Various coating materials such as a wire covering material, an optical fiber covering material, a transparent surface covering material provided on a light incident side surface of a photovoltaic element of a solar cell, and a back agent;

[0115] A diaphragm of a diaphragm pump, various gaskets, and the like;

[0116] An agricultural film, a weather-resistant cover for various roof materials and side walls, and the like;

[0117] A coating material for interior materials used in the building field, glass-based coating materials such as non-combustible fire safety glass, and the like;

[0118] A lining material such as a laminated steel sheet used in the field of home electronics and the like.

[0119] 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.

[0120] The above-described chemical medicine plug and packaging film have excellent chemical resistance to acids and the like. In addition, as the liquid medicine delivery member, an anticorrosion tape wound around a chemical device piping can be mentioned.

[0121] 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.

[0122] As the above-mentioned molded body, further, members used in bumpers, door trims, instrument panels, 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 phones, printer chassis, electrical / electronic parts, groceries, garbage cans, bathtubs, whole bathrooms, ventilation fans, lighting frames, and the like of automobiles can be mentioned.

[0123] The molded body containing the fluorine-containing copolymer of the present application is excellent in 110°C wear resistance, oxygen low permeability, 85°C high-temperature rigidity, 130°C tensile creep resistance, and durability to repeated load, and thus can be suitably used for syringes, tubes, films, or electric wire coverings, and the like.

[0124] The molded body containing the fluorine-containing copolymer of the present application can be suitably used as a gasket, a packing, or the like compressed member. The compressed member of the present application can be a gasket or a packing.

[0125] The size and shape of the compressed member of the present application can be 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, or quadrangular shape with rounded corners in plan view, and can have a through hole in the central portion thereof.

[0126] 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 suitably used 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.

[0127] As the nonaqueous electrolyte battery, there is no particular limitation as long as it is a battery provided with a nonaqueous electrolyte, and lithium ion secondary batteries, lithium ion capacitors, and the like can be mentioned. In addition, as the member for constituting a nonaqueous electrolyte battery, sealing members, insulating members, and the like can be mentioned.

[0128] The above-mentioned 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-mentioned electrolyte is not particularly limited, and LiClO4, LiAsF6, LiPF6, LiBF4, LiCl, LiBr, CH3SO3Li, CF3SO3Li, cesium carbonate, and the like can be used.

[0129] The compressed member of the present application can be preferably used, for example, as a sealing member such as a gasket, a packing, or the like, an insulating member such as an insulating gasket, an insulating packing, 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.

[0130] 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 short-circuiting is prevented for a long period of time.

[0131] 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 little variation in outer diameter, and thus has excellent electrical properties.

[0132] The covered wire has a core wire and a covering layer containing the fluorine-containing copolymer of the present application provided around the core wire. For example, an extrusion-molded body in which the fluorine-containing copolymer of the present application is melt-extrusion-molded on a core wire can be used as the covering layer. The covered wire is suitably used for a LAN cable (Ethernet Cable), a high-frequency transmission cable, a flat cable, a heat-resistant cable, and the like, and is suitably used for a transmission cable such as a LAN cable (Ethernet Cable), a high-frequency transmission cable, and the like.

[0133] 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.

[0134] 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.

[0135] The thickness of the covering layer is preferably 0.1 mm to 3.0 mm. The thickness of the covering layer is also preferably 2.0 mm or less.

[0136] 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.

[0137] The coating layer can contain bubbles, which are preferably uniformly distributed in the coating layer.

[0138] 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.

[0139] 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.

[0140] 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 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].

[0141] The coated electric wire can be manufactured by, for example, heating the fluorine-containing copolymer by 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.

[0142] 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 a 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.

[0143] In addition, the fluorine-containing copolymer of the present application can be suitably used as a material for a high-frequency signal transmission product.

[0144] 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 plate for a high-frequency circuit, an insulating article 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 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.

[0145] In the above-mentioned high-frequency signal transmission product, the fluorine-containing copolymer of the present application can be suitably used as an insulating article from the viewpoint of low tangent of dielectric loss.

[0146] As the above-mentioned (1) molded plate, 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.

[0147] The fluorine-containing copolymer of the present application can be suitably used for a film.

[0148] 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.

[0149] 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.

[0150] The fluorine-containing copolymer of the present application can also be suitably used for a tube, a bottle, or the like.

[0151] The above describes the embodiments, but it is understood that various changes can be made to the modes and details without departing from the gist and scope of the claims.

[0152] Examples

[0153] Next, the embodiments of the present application are described with examples, but the present application is not limited to the examples.

[0154] Each value of the examples is measured by the following method.

[0155] (Content of monomer unit)

[0156] 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.).

[0157] (Melt flow rate (MFR))

[0158] Regarding the MFR of the fluorine-containing copolymer, the mass (g / 10 minutes) of the polymer flowing out from a die of an inner diameter of 2 mm and a length of 8 mm per 10 minutes is measured at 372°C under a load of 5 kg using a melt flow indexer G-01 (manufactured by Toyo Seiki Jiki K.K.), and thereby the MFR is calculated.

[0159] (Number of -CF2H)

[0160] The number of -CF2H groups of the fluorine-containing copolymer is measured using a nuclear magnetic resonance device AVANCE-300 (manufactured by Bruker BioSpin Co., Ltd.) with a measurement temperature set to (melting point of the polymer + 20) °C. 19 The number of -CF2H groups is calculated from the peak integral value of the -CF2H group by F-NMR measurement.

[0161] (Number of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2)

[0162] The dry powder or pellet obtained in the examples and comparative examples was molded by cold press molding to produce a film having a thickness of 0.25 to 0.3 mm. The film was scanned 40 times by a Fourier transform infrared spectroscopy analyzer [FT-IR (Spectrum One, manufactured by PerkinElmer, Inc.)], and the obtained infrared absorption spectrum was analyzed. 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 specific functional groups appearing in the difference spectrum between the obtained infrared absorption spectrum and the infrared absorption spectrum of a known film was calculated as the number of functional groups N per 1 x 10 6

[0163] N = I x K / t (A)

[0164] I: absorbance

[0165] K: correction factor

[0166] t: thickness of the film (mm)

[0167] As a 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 is determined from the FT-IR measurement data of a low molecular model compound.

[0168] [Table 2]

[0169] Table 2

[0170]

[0171] (-OC(=O)O-R (carbonate group) number)

[0172] The number of -OC(=O)O-R (carbonate group) was calculated by the method described in International Publication No. 2019 / 220850. The absorption frequency was set to 1817 cm -1 , the molar absorption coefficient was set to 170 (l / cm / mol), the correction factor was set to 1426, and otherwise, 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.

[0173] (melting point)

[0174] ​The melting point of the fluorine-containing copolymer was measured using a differential scanning calorimeter (trade name: X-DSC7000, manufactured by Hitachi High-Tech Science Corporation) at a temperature increase rate of 10°C / min from 200°C to 350°C, followed by cooling from 350°C to 200°C at a cooling rate of 10°C / min, and then a second temperature increase from 200°C to 350°C at a temperature increase rate of 10°C / min, and the melting point was determined from the peak value of the melting curve generated during the second temperature increase.

[0175] Comparative Example 1

[0176] A 174-L autoclave equipped with a stirrer was charged with 40.25 kg of deionized water and 0.592 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 1.41 kg of PPVE were charged into the autoclave in a vacuum state, and the autoclave was heated to 25.5°C. Next, TFE was charged until the internal pressure of the autoclave reached 0.979 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 0.979 MPa, and the set pressure was maintained by continuously adding TFE. Methanol 0.592 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.

[0177] Note that 0.22 kg of PPVE was added at the time when the amount of continuously added TFE reached 8.1 kg, 16.2 kg, and 24.3 kg, respectively. In addition, 0.592 kg of methanol was added to the autoclave at the time when the amount of added TFE reached 6.0 kg and 18.1 kg, respectively. 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 43.7 kg of a dry powder was obtained.

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

[0179] Comparative Example 2

[0180] The amount of methanol charged before the start of polymerization was changed to 0.243 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.243 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.93 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 0.855 MPa, and otherwise, copolymer pellets 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.

[0181] Comparative Example 3

[0182] The amount of methanol charged before the start of polymerization was changed to 0.257 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.257 kg each, the amount of PPVE charged before the start of polymerization was changed to 1.12 kg, the amounts of PPVE charged in portions after the start of polymerization were changed to 0.23 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.892 MPa, and otherwise, copolymer pellets 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.

[0183] Comparative Example 4

[0184] The amount of methanol charged before the start of polymerization was changed to 0.423 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.423 kg each, the amount of PPVE charged before the start of polymerization was changed to 1.17 kg, the amounts of PPVE charged in portions after the start of polymerization were changed to 0.24 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.892 MPa, and otherwise, copolymer pellets 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 polymerization was changed to 0.380 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.380 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.69 kg, the amounts of PPVE charged in portions after the start of polymerization were changed to 0.14 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.892 MPa, and otherwise, copolymer pellets 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.

[0187] Comparative Example 6

[0188] The amount of methanol added before polymerization was changed to 0.374 kg, and the amount of methanol added in batches after polymerization began was also changed to 0.374 kg each time. The amount of PPVE added before polymerization was changed to 1.54 kg, and the amount of PPVE added in batches after polymerization began was also changed to 0.29 kg each time. The set pressure inside the autoclave before and after polymerization was changed to 0.924 MPa. Otherwise, copolymer granules were obtained in the same manner as in Comparative Example 1. Various physical properties were measured using the obtained granules according to the above method. The results are shown in Table 3.

[0189] Comparative Example 7

[0190] 945g of deionized water and 7.3g of methanol were added to a 4L autoclave equipped with a stirrer, and the autoclave was thoroughly purged with nitrogen under vacuum. Then, the autoclave was degassed under vacuum, and 945g of HFP and 27.4g of PEVE were added to the vacuum-sealed autoclave. The autoclave was heated to 25.5°C. Next, TFE was added until the internal pressure of the autoclave reached 0.895MPa. Then, 29.4g of 8% by mass di(ω-hydroperfluorohexanoyl) peroxide solution (hereinafter referred to as DHP) was added to the autoclave to begin polymerization. The internal pressure of the autoclave at the start of polymerization was set to 0.895MPa, and this pressure was maintained by continuously adding TFE. 7.3g of methanol was added 1.5 hours after the start of polymerization. Two hours and four hours after the start of polymerization, 29.4 g of DHP was added, and the internal pressure was reduced by 0.002 MPa. Six hours later, 22.6 g of DHP was added, and the internal pressure was reduced by 0.002 MPa each time. Thereafter, 6.0 g of DHP was added every two hours until the reaction was completed, and the internal pressure was reduced by 0.002 MPa each time.

[0191] It should be noted that 5.7g of PEVE was added at the points where TFE was continuously added to 190g and 380g, respectively. Additionally, 7.3g of methanol was added to the autoclave when TFE was added to 140g. The polymerization was terminated when TFE was added to 454g. After polymerization, unreacted TFE and HFP were released, yielding a wet powder. This wet powder was then washed with pure water and dried at 150℃ for 10 hours to obtain 506g of dry powder.

[0192] The obtained powder is used The copolymer granules were obtained by melt extrusion at 370°C using a screw extruder (manufactured by Imoto Manufacturing Co., Ltd.). The HFP and PEVE contents of the obtained granules were determined using the method described above. The results are shown in Table 3.

[0193] The obtained pellets were degassed at 200°C for 8 hours in an electric furnace, and then were put into a portable reactor, Model TVS1 (manufactured by Taikan Glass Industry Co., Ltd.), and heated to 200°C. After vacuumizing, F2 gas diluted with N2 gas to 20 vol% was introduced to the 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 therefrom, the vacuum was released again, and the F2 gas was introduced again. Thereafter, the operation of the introduction and release 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 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.

[0194] Example 1

[0195] The amount of the methanol introduced before the start of the polymerization was changed to 0.400 kg, the amounts of the methanol introduced in portions after the start of the polymerization were changed to 0.400 kg each, the amount of the PPVE introduced before the start of the polymerization was changed to 1.02 kg, the amounts of the PPVE introduced in portions 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 0.928 MPa, and otherwise, pellets of the copolymer were obtained in the same manner as in Comparative Example 1. Using the obtained pellets, the HFP content and the PPVE content were measured by the above-described methods. The results are shown in Table 3.

[0196] The obtained pellets were degassed at 200°C for 72 hours in an electric furnace, and then were put into a vacuum vibration-type reaction device, Model VVD-30 (manufactured by Okawara Mfg. Co., Ltd.), and heated to 120°C. After vacuumizing, F2 gas diluted with N2 gas to 20 vol% was introduced to the 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 therefrom, the vacuum was released again, and the F2 gas was introduced again. Thereafter, the operation of the introduction and release of the F2 gas was repeated once every 1 hour, and the reaction was carried out at a temperature of 120°C for 7 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.

[0197] Example 2

[0198] The amount of methanol charged before the start of polymerization was changed to 0.374 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.374 kg each, the amount of PPVE charged before the start of polymerization was changed to 1.13 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 0.910 MPa, and otherwise, copolymer pellets were obtained in the same manner as in Comparative Example 1. Using the obtained pellets, the HFP content and the PPVE content were measured by the above-described methods. The results are shown in Table 3.

[0199] 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 therefrom, 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, and pellets were obtained. Using the obtained pellets, various physical properties were measured by the above-described methods. The results are shown in Table 3.

[0200] Example 3

[0201] The amount of methanol charged before the start of polymerization was changed to 0.369 kg, the amounts of methanol charged in portions after the start of polymerization were changed to 0.369 kg each, the amount of PPVE charged before the start of polymerization was changed to 0.449 kg, the amounts of PPVE charged in portions after the start of polymerization were changed to 0.24 kg each, the set pressure inside the autoclave before and after the start of polymerization was changed to 0.892 MPa, and otherwise, copolymer pellets 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.

[0202] [Table 3]

[0203] Table 3

[0204]

[0205] "Others (pieces / C10 6The notation of “<9” in Table 3 means the number (total) of -CF2H groups is less than 9. The notation of “<6” in Table 3 means the number (total) of the functional groups of interest is less than 6. The notation of “ND” in Table 3 means that the peak could not be confirmed to a quantifiable degree for the functional group of interest.

[0206] Next, using the obtained pellets, the following properties were evaluated. The results are shown in Table 4.

[0207] (Wear Test)

[0208] 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 10 cm x 10 cm test piece was cut therefrom. The produced test piece was fixed on a test stage of a Taber wear tester (No. 101 Taber-type abrasion tester, manufactured by Asada Seisakusho Co., Ltd.), and a wear test was performed using the Taber wear tester under conditions of a test piece surface temperature of 110°C, a load of 500 g, an abrasion 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 a test of 3000 turns using the same test piece. The amount of wear was calculated by the following equation.

[0209] Amount of wear (mg) = M1 - M2

[0210] M1: Weight of test piece after 1000 turns (mg)

[0211] M2: Weight of test piece after 3000 turns (mg)

[0212] (Oxygen Transmission Coefficient)

[0213] Using the pellets and a hot press molding machine, a sheet-shaped test piece having a thickness of about 0.1 mm was produced. Using the obtained test piece, an oxygen transmission degree was measured using a differential pressure type gas permeability meter (L100-5000 type gas permeability meter, manufactured by Systech Illinois Co.) according to the method described in JIS K7126-1:2006. The value of the oxygen transmission degree under conditions of a permeation area of 50.24 cm 2 , a test temperature of 70°C, and a test humidity of 0% RH was obtained. Using the obtained oxygen transmission degree and the thickness of the test piece, the oxygen transmission coefficient was calculated by the following equation.

[0214] Oxygen transmission coefficient (cm 3 ·mm / (m 2 ·24h·atm)) = GTR x d

[0215] GTR: Oxygen transmission degree (cm 3 / (m2 • 24h • atm)

[0216] d: thickness of test piece (mm)

[0217] (85°C load deflection)

[0218] Using the pellets and a hot press molding machine, a test piece in the form of a sheet having a thickness of about 3 mm was produced, and a test piece of 80 x 10 mm was cut therefrom. Using the obtained test piece, a test was performed in accordance with the method described in JIS K-K7191-1 using a thermal deformation tester (manufactured by Seishin Enterprise 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 calculated by the following formula. The test piece having a small load deflection at 85°C has excellent rigidity at high temperature of 85°C.

[0219] Load deflection (%) = a2 / ai x 100

[0220] ai: thickness of test piece before test (mm)

[0221] a2: deflection amount at 85°C (mm)

[0222] (Tensile creep test)

[0223] The tensile creep strain was measured using a TMA-7100 manufactured by Hitachi High-Technologies Corporation. Using the pellets and a hot press molding machine, a test piece in the form of a sheet having a thickness of about 0.1 mm was produced, and a sample having a width of 2 mm and a length of 22 mm was produced from the test piece. The sample was installed in a measurement jig at a jig distance of 10 mm. For the sample, a load was applied in a manner such that the cross-sectional load was 3.71 N / mm 2 The displacement (mm) of the length of the sample from the time of 90 minutes after the start of the test to the time of 600 minutes after the start of the test was measured while the sample was placed at 130°C, and the ratio of the displacement (mm) of the length to the initial sample length (10 mm) (tensile creep strain (%)) was calculated. The test piece having a small tensile creep strain (%) measured at 130°C for 600 minutes is less likely to elongate even when a tensile load is applied for a long time in a high-temperature environment, and has excellent high-temperature tensile creep resistance (130°C).

[0224] (6 million cycles tensile strength)

[0225] The tensile strength after 60,000 cycles 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 shape (thickness 2.4 mm, width 5.0 mm, length of measurement portion 22 mm) was produced using ASTM D1708 micro dumbbells. The sample was mounted to a measurement jig, and the measurement jig was set in a constant temperature bath 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 in a single axis direction at a stroke of 0.2 mm and a frequency of 100 Hz.

[0226] The sheet having a high tensile strength after 60,000 cycles maintained a high tensile strength even after 60,000 cycles of load, and was excellent in durability to repeated load (110°C).

[0227] (Immersion test in hydrogen peroxide water)

[0228] Pellets and a hot press molding machine were used to produce a sheet having a thickness of about 0.2 mm, and a test piece of 15 mm square was produced. Ten test pieces and 15 g of a 3 mass% hydrogen peroxide aqueous solution were put in a 50 mL polypropylene bottle, and after heating at 95°C for 20 hours using an electric furnace, the temperature was cooled to room temperature. The test pieces were taken out of the hydrogen peroxide aqueous solution, and a TISAB solution (10) (manufactured by Kanto Chemical Co., Inc.) was added to the remaining hydrogen peroxide aqueous solution, and the concentration of fluoride ions in the obtained hydrogen peroxide aqueous solution was measured using a fluoride ion meter. The concentration of fluoride ions per unit weight of the test piece (eluted fluoride ion concentration) was calculated from the obtained measurement value according to the following formula.

[0229] Eluted fluoride ion concentration (mass ppm) = measurement value (ppm) x hydrogen peroxide aqueous solution amount (g) / test piece weight (g)

[0230] (Self-weight deformation test at the time of melting)

[0231] Pellets and a hot press molding machine were used to produce a molded body having a diameter of 13 mm and a height of about 6.5 mm. The obtained molded body was cut, and a test piece having a height of 6.3 mm was produced. The produced test piece was put in a SUS dish, and after heating at 330°C for 30 minutes using an electric furnace, the dish with the test piece put therein was subjected to water cooling. The diameter of the face (bottom face) of the test piece taken out which contacted the dish was measured using a vernier caliper, and the increase rate of the bottom area was calculated according to the following formula.

[0232] Increase rate of bottom area (%) = {bottom area of test piece after heating (mm 2 ) - bottom area of test piece before heating (mm 2 )} / bottom area of test piece before heating (mm 2 ) x 100

[0233] The lower the bottom area increase rate, the more difficult the molded body is to deform due to its own weight when molten. The fluorine-containing copolymer that provides a molded body having a low bottom area increase rate is excellent in that even in the case where a thick sheet or a large tube is produced by molding the fluorine-containing copolymer by an extrusion molding method, the molded body in a molten state is not easily deformed, and a molded body having a desired shape is obtained after cooling and solidification.

[0234] (injection moldability)

[0235] 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-cavity, side gate, 15 mm x 15 mm x 1 mm t) was used. The obtained four injection molded bodies were observed, and evaluated in accordance with the following criteria. The presence or absence of surface roughness was confirmed by contacting the surface of the injection molded body.

[0236] 3: The surfaces of the four molded bodies were smooth as a whole.

[0237] 2: Roughness was confirmed on the surface within 1 cm from the portion where the gate of the mold was located, for one of the four molded bodies.

[0238] 1: Roughness was confirmed on the surface within 1 cm from the portion where the gate of the mold was located, for two to four of the four molded bodies.

[0239] 0: Roughness was observed on the surfaces of the four molded bodies as a whole.

[0240] (wire coating test)

[0241] 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.

[0242] a) Core conductor: conductor diameter about 0.40 mm (0.08 mm x 19 twisted)

[0243] b) Coating thickness: 0.30 mm

[0244] c) Coated wire diameter: 1.00 mm

[0245] d) Wire pulling speed: 120 m / minute

[0246] e) Extrusion conditions:

[0247] • Single screw extrusion molding machine with a cylinder shaft diameter of 30 mm and L / D of 24

[0248] • Die (inner diameter) / piece (outer diameter) = 10.0 mm / 4.0 mm

[0249] Setting temperature of extruder: Cylinder part C-1 (330°C), Cylinder part C-2 (360°C), Cylinder part C-3 (365°C), Head part H (370°C), Die part D-1 (370°C), Die part D-2 (370°C). Core wire preheating was set to 80°C.

[0250] (Outer diameter variation)

[0251] 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 most from the prescribed outer diameter value (1.00 mm) was rounded off, and thus the outer diameter variation value was obtained. The proportion of the absolute value of the difference between the prescribed outer diameter and the outer diameter variation value with respect to the prescribed outer diameter (1.00 mm) (outer diameter variation rate) was calculated, and evaluated according to the following criteria.

[0252] (Outer diameter variation rate (%)) = | (outer diameter variation value) - (prescribed outer diameter) | / (prescribed outer diameter) x 100

[0253] ±1%: Outer diameter variation rate is 1% or less

[0254] ±2%: Outer diameter variation rate exceeds 1% and is 2% or less

[0255] x: Outer diameter variation rate exceeds 2%

[0256] (Tubing formability)

[0257] Using An extruder (Takeda Plastic Machinery) was used to extrude the pellets to form a tube having an outer diameter of 10.0 mm and a wall thickness of 1.0 mm. The extrusion molding conditions were as follows.

[0258] a) Die inner diameter: 25 mm

[0259] b) Mandrel outer diameter: 13 mm

[0260] c) Shaping die inner diameter: 10.5 mm

[0261] d) Drawing speed: 0.4 m / minute

[0262] e) Outer diameter: 10.0 mm

[0263] f) Wall thickness: 1.0 mm

[0264] g) Extrusion conditions:

[0265] • Single screw extrusion molding machine with barrel shaft diameter = 30 mm, L / D = 22

[0266] Setting temperature of extruder: cylinder section C-1 (350°C), cylinder section C-2 (370°C), cylinder section C-3 (380°C), head section H-1 (390°C), die section D-1 (390°C), die section D-2 (390°C)

[0267] The obtained tube was observed, and evaluated according to the following criteria. The appearance of the tube was confirmed by visual observation.

[0268] O: Good appearance

[0269] X: Cross section was not circular, flatness or uneven thickness was observed, and the appearance was poor.

[0270] (Film moldability)

[0271] Using An extruder (manufactured by Miki Pulverizing Co., Ltd.) and a T-die were used to mold the pellets and produce a film. The extrusion molding conditions were as follows.

[0272] a) Winding speed: 1 m / min

[0273] b) Roll temperature: 120°C

[0274] c) Film width: 70 mm

[0275] d) Thickness: 0.10 mm

[0276] e) Extrusion conditions:

[0277] • Single screw extrusion molding machine with barrel shaft diameter = 14 mm, L / D = 20

[0278] Setting temperature of extruder: cylinder section C-1 (330°C), cylinder section C-2 (350°C), cylinder section C-3 (365°C), T-die section (370°C)

[0279] The extrusion molding of the fluorine-containing copolymer was continued until the fluorine-containing copolymer was stably extruded from the molding machine. Subsequently, a film having a length of 11 m or more (width 70 mm) was produced in a manner such that the thickness was 0.10 mm by extrusion molding of the fluorine-containing copolymer. A test piece for measuring variation in thickness (length 1 m, width 70 mm) was produced by cutting a portion of 10 to 11 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 in the width direction from the center point were 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 in the width direction from each center point were measured. In a case where the number of measured values outside the range of ±10% of 0.10 mm was one or less out of a total of 12 measured values, the case was marked as O, and in a case where the number of measured values outside the range of ±10% of 0.10 mm was two or more, the case was marked as X.

[0280]

Claims

1. A fluorinated copolymer, comprising tetrafluoroethylene units, hexafluoropropylene units, and perfluoro(propyl vinyl ether) units, wherein, The content of hexafluoropropylene units relative to all monomer units is 6.0% to 7.6% by mass. The content of perfluoro(propyl vinyl ether) units is 1.5% to 2.4% by mass relative to all monomer units. The content of tetrafluoroethylene units relative to all monomer units is 90.0% to 92.5% by mass. The melt flow rate at 372℃ was 4.5 g / 10 min to 9.5 g / 10 min. The total number of carbonyl-containing terminal groups, -CF=CF2, and -CH2OH relative to 10 6 The main chain has fewer than 90 carbon atoms.

2. The fluorinated copolymer as described in claim 1, wherein, The content of hexafluoropropylene units is 6.2% to 7.2% by mass relative to all monomer units.

3. The fluorinated copolymer as described in claim 1 or 2, wherein, The content of perfluoro(propyl vinyl ether) units is 1.7% to 2.2% by mass relative to all monomer units.

4. The fluorinated copolymer as described in claim 1 or 2, wherein, The melt flow rate at 372℃ is 5.0 g / 10 min to 8.9 g / 10 min.

5. The fluorinated copolymer as described in claim 1 or 2, wherein, The amount of -CF2H relative to every 10 6 The main chain has fewer than 90 carbon atoms.

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

7. A coated wire having a coating layer comprising a fluorinated copolymer according to any one of claims 1 to 5.

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

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