Copolymer, compression molded body, transfer molded body, and compressed member

Abstract

To provide a copolymer that has a high glass transition temperature, is resistant to corrosion of a mold used for molding, and is excellent in moldability and electrical properties, and further has excellent low water vapor permeability and low electrolyte permeability, is resistant to leakage of electrolyte, has excellent sealing properties at high temperatures while maintaining an appropriate compression set, and can give a molded product that is resistant to elution of fluorine ions into electrolyte. The polymer contains tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, the content of the perfluoro(propyl vinyl ether) units being 2.0 to 2.7 mass% based on the total amount of monomer units, the melt flow rate at 372°C being 0.8 to 7.0 g / 10 min, and the number of functional groups is 10 carbon atoms in the main chain. 6 The copolymer has 50 or less units per unit.

Description

[Technical Field]

[0001] The present disclosure relates to a copolymer, a compression molded body, a transfer molded body, and a compressed member. [Background technology]

[0002] Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) is known as a fluororesin that has excellent mechanical, chemical, and electrical properties and is also melt-processable.

[0003] For example, Patent Document 1 describes a sealing material made of a fluorine-containing polymer having polymerization units based on tetrafluoroethylene and polymerization units based on one or more types of perfluoro(alkyl vinyl ether), wherein the fluorine-containing polymer contains polymerization units based on perfluoro(alkyl vinyl ether) in an amount of 4.0 mass% or less based on the total polymerization units, and has a melt flow rate of 0.1 to 100 g / 10 min. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-177574 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a copolymer that has a high glass transition temperature, is resistant to corrosion of a mold used for molding, and has excellent moldability and electrical properties, and further has excellent low water vapor permeability and low electrolyte permeability, is resistant to leakage of electrolyte, has excellent sealing properties at high temperatures while maintaining appropriate compression set, and can give a molded product that is resistant to elution of fluoride ions into the electrolyte. [Means for solving the problem]

[0006] According to the present disclosure, a fluoropolymer containing tetrafluoroethylene units and perfluoro(propyl vinyl ether) units is provided, the content of the perfluoro(propyl vinyl ether) units being 2.0 to 2.7 mass% relative to the total mass of the monomer units, the melt flow rate at 372°C being 0.8 to 7.0 g / 10 min, and the number of functional groups being 10 main chain carbon atoms. 6 Copolymers are provided in which the number of units per unit is 50 or less.

[0007] The present disclosure also provides a compression molded article containing the above copolymer.

[0008] The present disclosure also provides an extruded article containing the above copolymer.

[0009] The present disclosure also provides a transfer molded article containing the above copolymer.

[0010] The present disclosure also provides a compressed member containing the above copolymer.

[0011] The present disclosure also provides a film containing the above copolymer.

[0012] The present disclosure also provides a tube containing the above copolymer.

[0013] The present disclosure also provides a coated electric wire having a coating layer containing the above-described copolymer. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a copolymer that has a high glass transition temperature, is resistant to corrosion of a mold used for molding, and has excellent moldability and electrical properties, and further has excellent low water vapor permeability and low electrolyte permeability, is resistant to leakage of electrolyte, has excellent sealing properties at high temperatures while maintaining appropriate compression set, and can give a molded product that is resistant to elution of fluoride ions into the electrolyte. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view of a test jig used in an electrolyte leakage test. DETAILED DESCRIPTION OF THE INVENTION

[0016] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0017] The copolymers of the present disclosure contain tetrafluoroethylene (TFE) units and perfluoro(propyl vinyl ether) (PPVE) units.

[0018] Patent Document 1 describes that in-vehicle secondary batteries are sometimes exposed to high temperatures of 85°C or higher in their usage environment, and that in order to maintain airtightness and liquid tightness inside the battery, it is important that the sealing material retains sufficient compression recovery even under such harsh usage conditions and can maintain high adhesion between the battery can and the sealing body.

[0019] However, there is a demand for copolymers that can exhibit excellent sealing properties even in higher temperature environments, particularly at temperatures above the glass transition temperature of the copolymer.

[0020] It has been found that by appropriately adjusting the PPVE unit content, melt flow rate (MFR), and number of functional groups of a copolymer containing TFE units and PPVE units, the glass transition temperature of the copolymer can be sufficiently increased, resulting in excellent heat resistance. The copolymer has excellent moldability and is resistant to corrosion of the mold used for molding, making it suitable for transfer molding, for example. It has also been found that molded articles containing such copolymers have excellent low water vapor permeability and low electrolyte permeability, are resistant to electrolyte leakage, maintain appropriate compression set, have excellent sealing properties at high temperatures, and are resistant to elution of fluoride ions into the electrolyte. Furthermore, it has been found that molded articles containing such copolymers also have excellent electrical properties.

[0021] The copolymers of the present disclosure are melt-processable fluoroplastics, meaning that the polymers can be melted and processed using conventional processing equipment such as extruders and transfer molding machines.

[0022] The PPVE unit content of the copolymer is 2.0 to 2.7% by mass based on the total monomer units. The PPVE unit content of the copolymer is preferably 2.1% by mass or more, more preferably 2.2% by mass or more, even more preferably 2.3% by mass or more, still more preferably 2.4% by mass or more, and preferably 2.6% by mass or less, and more preferably 2.5% by mass or less. When the PPVE unit content of the copolymer is within the above range, it is possible to obtain a copolymer having a higher glass transition temperature, excellent low water vapor permeability and low electrolyte permeability, resistance to electrolyte leakage, and capable of giving a molded article having excellent high-temperature sealing properties while maintaining an appropriate compression set.

[0023] The content of TFE units in the copolymer is preferably 97.3 to 98.0% by mass, more preferably 97.9% by mass or more, even more preferably 97.8% by mass or less, still more preferably 97.7% by mass or less, particularly preferably 97.7% by mass or less, most preferably 97.6% by mass or less, more preferably 97.4% by mass or more, and even more preferably 97.5% by mass or more, based on the total monomer units. By having the TFE unit content in the copolymer within the above range, it is possible to obtain a copolymer with a higher glass transition temperature, and a copolymer that gives a molded product with excellent low water vapor permeability and low electrolyte permeability, is less susceptible to electrolyte leakage, and has excellent high-temperature sealing properties while maintaining an appropriate compression set.

[0024] In the present disclosure, the content of each monomer unit in the copolymer is: 19 Measured by F-NMR.

[0025] The copolymer may also contain monomer units derived from a monomer copolymerizable with TFE and PPVE. In this case, the content of the monomer units copolymerizable with TFE and PPVE is preferably 0 to 4.0 mass%, more preferably 0.05 to 0.7 mass%, and even more preferably 0.1 to 0.5 mass%, based on the total monomer units of the copolymer.

[0026] Monomers that can be copolymerized with TFE and PPVE include hexafluoropropylene (HFP), CZ 1 Z 2 =CZ 3 (CF2) n Z 4 (In the formula, Z 1 , Z 2 and Z 3 are the same or different and represent H or F, and Z 4 represents H, F or Cl, and n represents an integer of 2 to 10.) and a vinyl monomer represented by CF2=CF-OCH2-Rf 1 (In the formula, Rf 1represents a perfluoroalkyl group having 1 to 5 carbon atoms. Among these, HFP is preferred.

[0027] The copolymer is preferably at least one selected from the group consisting of copolymers consisting only of TFE units and PPVE units, and TFE / HFP / PPVE copolymers, and more preferably a copolymer consisting only of TFE units and PPVE units.

[0028] The copolymer has a melt flow rate (MFR) of 0.8 to 7.0 g / 10 min. The MFR of the copolymer is preferably 1.0 g / 10 min or more, more preferably 1.2 g / 10 min or more, particularly preferably 1.5 g / 10 min or more, most preferably 1.8 g / 10 min or more, and preferably 6.0 g / 10 min or less, more preferably 5.5 g / 10 min or less, even more preferably 5.0 g / 10 min or less, and particularly preferably 4.8 g / 10 min or less. When the MFR of the copolymer is within the above range, the copolymer can be obtained, which has excellent low water vapor permeability and low electrolyte permeability, is resistant to electrolyte leakage, and provides a molded article with excellent sealability, especially at high temperatures, while maintaining appropriate compression set. Furthermore, when the MFR of the copolymer is within the above range, the copolymer exhibits high moldability and can be molded by compression molding, transfer molding, extrusion molding, etc.

[0029] Furthermore, by adjusting the MFR of the copolymer to 3.8 g / 10 min or less, preferably 3.4 g / 10 min or less, and more preferably 3.0 g / 10 min or less, it is possible to obtain a copolymer that is less likely to deform even in a molten state. By using such a copolymer, it is possible to easily obtain large-diameter pipes with high dimensional accuracy by extrusion molding.

[0030] In the present disclosure, MFR is a value obtained in accordance with ASTM D1238 using a melt indexer, as the mass of polymer flowing out per 10 minutes (g / 10 min) from a nozzle with an inner diameter of 2.1 mm and a length of 8 mm under a load of 5 kg at 372°C.

[0031] The MFR can be adjusted by adjusting the type and amount of a polymerization initiator used when polymerizing the monomers, the type and amount of a chain transfer agent, and the like.

[0032] In the present disclosure, the copolymer has a main chain carbon number of 10 6 The number of functional groups per unit is 50 or less. The main chain carbon number of the copolymer is 10 6 The number of functional groups per copolymer is preferably 40 or less, more preferably 30 or less, even more preferably 20 or less, even more preferably 15 or less, particularly preferably 10 or less, and most preferably less than 6. By having the number of functional groups of the copolymer within the above range, the copolymer is less likely to corrode a mold during molding using a mold, and the electrical properties of the copolymer can be further improved. In addition, it is possible to obtain a copolymer that gives a molded product that is less likely to leak electrolyte and less likely to elute fluoride ions into the electrolyte. Furthermore, by having the number of functional groups of the copolymer within the above range, it is possible to prevent molding defects such as foaming caused by decomposition of the functional groups of the copolymer and generation of gas.

[0033] Infrared spectroscopy can be used to identify the type of functional group and measure the number of functional groups.

[0034] The number of functional groups is specifically measured by the following method. First, the copolymer is molded by cold pressing to prepare a film having a thickness of 0.25 to 0.3 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum of the copolymer, and a difference spectrum is obtained from the base spectrum, which is completely fluorinated and has no functional groups. From the absorption peaks of specific functional groups that appear in this difference spectrum, the number of carbon atoms in the copolymer (1 × 10) is calculated according to the following formula (A): 6 Calculate the number of functional groups per molecule, N.

[0035] N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm)

[0036] For reference, the absorption frequencies, molar absorption coefficients, and correction factors for several functional groups are shown in Table 1. The molar absorption coefficients were determined from FT-IR measurement data of low-molecular-weight model compounds. [Table 1]

[0037] The absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are shown in the table, and are several tens of Kaiser (cm) from the absorption frequencies of -CF2H, -COF, -COOH free and -COOH bonded, -COOCH3, and -CONH2, respectively. -1 ) becomes lower.

[0038] For example, the number of functional groups of -COF is the absorption frequency of 1883 cm due to -CF2COF. -1 The number of functional groups determined from the absorption peak of -CH2COF and the absorption frequency of 1840 cm -1 The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0039] The functional groups are those present at the ends of the main chain or side chains of the copolymer, and those present in the main chain or side chains. The number of functional groups may be the total number of -CF=CF, -CFH, -COF, -COOH, -COOCH, -CONH, and -CHOH.

[0040] The functional group is introduced into the copolymer by, for example, a chain transfer agent or a polymerization initiator used in producing the copolymer. For example, when an alcohol is used as a chain transfer agent or a peroxide having a -CHOH structure is used as a polymerization initiator, -CHOH is introduced into the main chain terminal of the copolymer. Alternatively, the functional group can be introduced into the side chain terminal of the copolymer by polymerizing a monomer having a functional group.

[0041] By subjecting a copolymer having such functional groups to a fluorination treatment, a copolymer having a number of functional groups within the above range can be obtained. That is, the copolymer of the present disclosure is preferably a fluorination-treated copolymer. The copolymer of the present disclosure also preferably has a -CF3 terminal group.

[0042] The melting point of the copolymer is preferably 305 to 317° C., more preferably 305 to 315° C. When the melting point is within the above range, it is possible to obtain a copolymer that gives a molded article having even more excellent sealability, particularly at high temperatures.

[0043] In this disclosure, melting points can be measured using a differential scanning calorimeter (DSC).

[0044] The glass transition temperature (Tg) of the copolymer is preferably 95.0° C. or higher, more preferably 98.8° C. or higher, more preferably 99.0° C. or higher, and preferably 110.0° C. or lower, more preferably 105.0° C. or lower, and even more preferably 103.0° C. or lower. Because the copolymer of the present disclosure can have such a high glass transition temperature, it is possible to obtain a copolymer that exhibits excellent heat resistance and gives a molded article that has even more excellent sealability, particularly at high temperatures.

[0045] In the present disclosure, the glass transition temperature can be measured by dynamic viscoelasticity measurement.

[0046] The water vapor permeability of the copolymer is preferably 11.0 g cm / m 2 or less, and more preferably 10.0 g cm / m 2 or less, and more preferably 9.8 g cm / m 2 The copolymer of the present disclosure has excellent low water vapor permeability because the PPVE unit content and melt flow rate (MFR) of the copolymer containing TFE units and PPVE units are appropriately adjusted. Therefore, by using a molded article containing the copolymer of the present disclosure as, for example, a compressed member of a secondary battery, it is possible to effectively prevent moisture penetration even under high-temperature and high-humidity conditions.

[0047] In the present disclosure, the water vapor permeability can be measured for 30 days at a temperature of 95° C. The water vapor permeability can be specifically measured by the method described in the examples.

[0048] The electrolyte permeability of the copolymer is preferably 8.8 g cm / m 2 or less, and more preferably 8.6 g cm / m 2 The copolymer of the present disclosure has an excellent low electrolyte permeability because the PPVE unit content, melt flow rate (MFR), and number of functional groups of the copolymer containing TFE units and PPVE units are appropriately adjusted. Therefore, by using a molded article containing the copolymer of the present disclosure as, for example, a compressed member of a secondary battery, permeation of the electrolyte contained in the secondary battery can be effectively prevented.

[0049] In the present disclosure, the electrolyte permeability can be specifically measured by the method described in the Examples.

[0050] The copolymer of the present disclosure preferably has an amount of eluted fluorine ions detected in an electrolyte immersion test of 1.0 ppm or less, more preferably 0.8 ppm or less, and even more preferably 0.7 ppm or less, by mass. When the amount of eluted fluorine ions is within the above range, the generation of gases such as HF in a nonaqueous electrolyte battery can be further suppressed, and the deterioration of battery performance and shortened life of the nonaqueous electrolyte battery can be further suppressed.

[0051] In the present disclosure, the electrolyte immersion test can be performed by preparing a test piece using the copolymer, the test piece having a weight equivalent to 10 molded bodies (15 mm × 15 mm × 0.2 mm), and placing the test piece and 2 g of dimethyl carbonate (DMC) in a glass sample bottle in a thermostatic bath at 80°C and leaving it for 144 hours.

[0052] The copolymer of the present disclosure can maintain appropriate compression set properties, and therefore can provide a molded article with excellent low-temperature sealability. The low-temperature sealability can be evaluated by measuring the compression set rate at 65°C. A copolymer with a low compression set rate at 65°C can provide a molded article with excellent low-temperature sealability.

[0053] The copolymer of the present disclosure preferably has a compression set of 45 to 80%, more preferably 70 to 80%, and even more preferably 72 to 77%, as measured after being left at 65°C for 72 hours under a compression ratio of 50%. When the compression set at 65°C is within the above range, a molded article containing the copolymer can continue to exhibit sufficient impact resilience for a long period of time when used, for example, as a compressed member.

[0054] In the present disclosure, the compression set rate can be measured in accordance with the method described in ASTM D395 or JIS K6262:2013.

[0055] As described above, the copolymer of the present disclosure can provide a molded article with extremely excellent sealability at high temperatures while maintaining appropriate compression set. High-temperature sealability can be evaluated by measuring the storage modulus (E') at 150°C, the recovery at 150°C, and the contact pressure at 150°C. Copolymers with a high storage modulus (E') at 150°C and a large recovery at 150°C can maintain sufficient rebound resilience even at high temperatures for a long period of time. Furthermore, copolymers with high contact pressure at 150°C can provide a molded article with excellent sealability at high temperatures. The copolymer of the present disclosure can provide a molded article that exhibits extremely excellent sealability even at high temperatures exceeding the glass transition temperature of the copolymer.

[0056] The storage modulus (E') of the copolymer at 150°C is preferably 120 MPa or more, more preferably 130 MPa or more, even more preferably 135 MPa or more, and preferably 1000 MPa or less, more preferably 500 MPa or less, and even more preferably 300 MPa or less. When the storage modulus (E') of the copolymer at 150°C is within the above range, it is possible to obtain a copolymer that can continue to exhibit sufficient impact resilience even at high temperatures for a long period of time and that can give a molded product with extremely excellent sealability at high temperatures.

[0057] The storage modulus (E') can be measured by dynamic viscoelasticity measurement in the range of 30 to 250°C under conditions of a temperature rise rate of 2°C / min and a frequency of 10 Hz. The storage modulus (E') at 150°C can be increased by adjusting the PPVE unit content and melt flow rate (MFR) of the copolymer.

[0058] The copolymer has a very high surface pressure at 150°C. The surface pressure of the copolymer at 150°C is preferably 1.80 MPa or more, more preferably 1.85 MPa or more, and even more preferably 1.99 MPa or more. The upper limit is not particularly limited, but may be 3.0 MPa or less. The surface pressure at 150°C can be increased by adjusting the PPVE unit content, melt flow rate (MFR), and number of functional groups of the copolymer.

[0059] A test piece obtained from the copolymer is deformed at a compression deformation rate of 50%, left at 150°C for 18 hours, released from the compressed state, left at room temperature for 30 minutes, and then the height of the test piece (the height of the test piece after compression deformation) is measured, and the surface pressure can be calculated from the height of the test piece after compression deformation and the storage modulus (MPa) at 150°C using the following formula. 150℃ surface pressure (MPa) = (t2-t1) / t1×E' t1: Original height of the test piece before compressive deformation (mm) x 50% t2: Height of the test piece after compressive deformation (mm) E': Storage modulus at 150°C (MPa)

[0060] The recovery of the copolymer at 150°C can be measured using the same method as for measuring surface pressure. The recovery of the molded product at 150°C is the difference (t2 - t1) between the height of the test piece after compression deformation (t2) and the original height of the test piece before compression deformation (t1) when the test piece is deformed at a compression deformation rate of 50%. The recovery of the molded product at 150°C can be increased by adjusting the PPVE unit content, melt flow rate (MFR), and number of functional groups of the copolymer.

[0061] The copolymer of the present disclosure preferably has a dielectric loss tangent at 6 GHz of 6.0×10 -4 or less, and more preferably 5.0 × 10 -4 or less, and more preferably 4.0 × 10 -4 The following is an example. In recent years, with the increase in the amount of information to be transmitted, there has been a trend toward increasingly high-frequency radio waves. For example, microwaves of 3 to 30 GHz are used in high-frequency wireless LANs, satellite communications, mobile phone base stations, and the like. Materials having a low dielectric loss tangent (tan δ) are required for use in communication devices that use such high frequencies. When the dielectric loss tangent of the copolymer of the present disclosure is within the above range, the attenuation rate of high-frequency signals is significantly reduced, which is preferable.

[0062] In the present disclosure, the dielectric loss tangent is a value obtained by measuring the change in resonant frequency and electric field strength in a temperature range of 20 to 25°C using a network analyzer and a cavity resonator manufactured by Agilent Technologies.

[0063] The copolymer of the present disclosure can be produced by a polymerization method such as suspension polymerization, solution polymerization, emulsion polymerization, or bulk polymerization. Emulsion polymerization or suspension polymerization is preferred as the polymerization method. In these polymerizations, various conditions such as temperature and pressure, as well as the polymerization initiator and other additives, can be appropriately set depending on the composition and amount of the copolymer.

[0064] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0065] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example: dialkyl peroxycarbonates such as di-normal propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and di-2-ethoxyethyl peroxydicarbonate; Peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate; Dialkyl peroxides such as di-t-butyl peroxide; Di[fluoro(or fluorochloro)acyl]peroxides; are some of the most representative examples.

[0066] Di[fluoro(or fluorochloro)acyl]peroxides include diacyl peroxides represented by [(RfCOO)-]2 (Rf is a perfluoroalkyl group, an ω-hydroperfluoroalkyl group, or a fluorochloroalkyl group).

[0067] Examples of di[fluoro(or fluorochloro)acyl]peroxides include di(ω-hydro-dodecafluorohexanoyl)peroxide, di(ω-hydro-tetradecafluoroheptanoyl)peroxide, di(ω-hydro-hexadecafluorononanoyl)peroxide, di(perfluoropropionyl)peroxide, di(perfluorobutyryl)peroxide, di(perfluoroparenyl)peroxide, di(perfluorohexanoyl)peroxide, di(perfluoroheptanoyl)peroxide, di(perfluorooctanoyl)peroxide, di(perfluorononanoyl)peroxide, di(ω-chloro-hexafluorobutyryl)peroxide, and di(ω-chloro-decafluorohexa di(ω-chloro-tetradecafluorooctanoyl) peroxide, di(ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl peroxide, di(dichloropentafluorobutanoyl) peroxide, di(trichlorooctafluorohexanoyl) peroxide, di(tetrachloroundecafluorooctanoyl) peroxide, di(pentachlorotetradecafluorodecanoyl) peroxide, di(undecachlorotriacontafluorodocosanoyl) peroxide, and the like.

[0068] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, for example, ammonium salts, potassium salts, sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, percarbonate, etc.; organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide; t-butyl permalate; t-butyl hydroperoxide, etc. A reducing agent such as a sulfite may be used in combination with the peroxide, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0069] In the polymerization, a surfactant, a chain transfer agent, and a solvent can be used, and conventionally known surfactants, chain transfer agents, and solvents can be used.

[0070] As the surfactant, known surfactants can be used, such as nonionic surfactants, anionic surfactants, and cationic surfactants. Among them, fluorine-containing anionic surfactants are preferred, and linear or branched fluorine-containing anionic surfactants having 4 to 20 carbon atoms that may contain ether-bonded oxygen (i.e., oxygen atoms may be inserted between carbon atoms) are more preferred. The amount of surfactant added (relative to the polymerization water) is preferably 50 to 5,000 ppm.

[0071] Examples of chain transfer agents include hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; acetate esters such as ethyl acetate and butyl acetate; alcohols such as methanol and ethanol; mercaptans such as methyl mercaptan; and halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, and methyl chloride. The amount of chain transfer agent added varies depending on the magnitude of the chain transfer constant of the compound used, but is usually used in the range of 0.01 to 20% by mass based on the polymerization solvent.

[0072] Examples of the solvent include water and a mixed solvent of water and alcohol.

[0073] In the suspension polymerization, a fluorine-based solvent may be used in addition to water. Examples of the fluorine-based solvent include hydrochlorofluoroalkanes such as CH3CClF2, CH3CCl2F, CF3CF2CCl2H, and CF2ClCF2CFHCl; chlorofluoroalkanes such as CF2ClCFClCF2CF3 and CF3CFClCFClCF3; hydrofluoroalkanes such as CF3CFHCFHCF2CF2CF3, CF2HCF2CF2CF2CF2H, and CF3CF2CF2CF2CF2CF2CF2H; CH3OC2F5, CH3OC3F5 Examples of suitable fluorine-containing solvents include hydrofluoroethers such as CF3CF2CH2OCHF2, CF3CHFCF2OCH3, CHF2CF2OCH2F, (CF3)2CHCF2OCH3, CF3CF2CH2OCH2CHF2, and CF3CHFCF2OCH2CF3; and perfluoroalkanes such as perfluorocyclobutane, CF3CF2CF2CF3, CF3CF2CF2CF2CF3, and CF3CF2CF2CF2CF2CF3, with perfluoroalkanes being preferred. From the standpoints of suspension property and economy, the amount of the fluorine-containing solvent used is preferably 10 to 100% by mass relative to the aqueous medium.

[0074] The polymerization temperature is not particularly limited and may be 0 to 100° C. The polymerization pressure is determined appropriately depending on the type, amount, and vapor pressure of the solvent used, as well as other polymerization conditions such as the polymerization temperature, but may usually be 0 to 9.8 MPaG.

[0075] When an aqueous dispersion containing a copolymer is obtained by the polymerization reaction, the copolymer can be recovered by coagulating the copolymer contained in the aqueous dispersion, washing, and drying. When the copolymer is obtained as a slurry by the polymerization reaction, the copolymer can be recovered by removing the slurry from the reaction vessel, washing, and drying. By drying, the copolymer can be recovered in powder form.

[0076] The copolymer obtained by polymerization may be formed into pellets. The method for forming the pellets is not particularly limited, and conventionally known methods can be used. For example, the copolymer may be melt-extruded using a single-screw extruder, twin-screw extruder, or tandem extruder, cut to a predetermined length, and then formed into pellets. The extrusion temperature during melt extrusion must be varied depending on the melt viscosity of the copolymer and the production method, and is preferably the melting point of the copolymer + 20°C to the melting point of the copolymer + 140°C. The method for cutting the copolymer is not particularly limited, and conventionally known methods such as strand cutting, hot cutting, underwater cutting, and sheet cutting can be used. The obtained pellets may be heated to remove volatile components therein (degassing treatment). The obtained pellets may be treated by contacting them with hot water at 30 to 200°C, steam at 100 to 200°C, or hot air at 40 to 200°C.

[0077] The copolymer obtained by polymerization may be subjected to a fluorination treatment. Fluorination treatment can be carried out by contacting an unfluorinated copolymer with a fluorine-containing compound. The fluorination treatment converts thermally unstable functional groups of the copolymer, such as -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, and -CONH2, and relatively thermally stable functional groups such as -CF2H, into the thermally extremely stable -CF3. As a result, the total number (number of functional groups) of -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, and -CF2H in the copolymer can be easily adjusted to fall within the above-mentioned range.

[0078] The fluorine-containing compound is not particularly limited, but may be a fluorine radical source that generates fluorine radicals under fluorination treatment conditions, such as F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, or halogen fluorides (e.g., IF5, ClF3).

[0079] A fluorine radical source such as F2 gas may be 100% concentrated, but from a safety standpoint, it is preferably mixed with an inert gas and diluted to 5 to 50 mass %, more preferably 15 to 30 mass % for use. Examples of the inert gas include nitrogen gas, helium gas, and argon gas, with nitrogen gas being preferred from an economical standpoint.

[0080] The conditions for the fluorination treatment are not particularly limited, and the copolymer in a molten state may be contacted with a fluorine-containing compound, but the treatment is usually carried out at a temperature below the melting point of the copolymer, preferably 20 to 240°C, more preferably 100 to 220°C. The fluorination treatment is generally carried out for 1 to 30 hours, preferably 5 to 25 hours. The fluorination treatment is preferably carried out by contacting an unfluorinated copolymer with fluorine gas (F2 gas).

[0081] A composition may be obtained by mixing the copolymer of the present disclosure with other components as needed, such as fillers, plasticizers, processing aids, release agents, pigments, flame retardants, lubricants, light stabilizers, weather stabilizers, conductive agents, antistatic agents, UV absorbers, antioxidants, foaming agents, fragrances, oils, softeners, and dehydrofluorination agents.

[0082] Examples of fillers include silica, kaolin, clay, organoclay, talc, mica, alumina, calcium carbonate, calcium terephthalate, titanium oxide, calcium phosphate, calcium fluoride, lithium fluoride, cross-linked polystyrene, potassium titanate, carbon, boron nitride, carbon nanotubes, and glass fibers. Examples of conductive agents include carbon black. Examples of plasticizers include dioctyl phthalate and pentaerythritol. Examples of processing aids include carnauba wax, sulfone compounds, low-molecular-weight polyethylene, and fluorine-based aids. Examples of dehydrofluorination agents include organic oniums and amidines.

[0083] As the other component, a polymer other than the above-mentioned copolymer may be used, such as a fluororesin, a fluororubber, or a non-fluorinated polymer other than the above-mentioned copolymer.

[0084] Examples of methods for producing the composition include a method of dry mixing the copolymer and other components, and a method of previously mixing the copolymer and other components in a mixer and then melt-kneading them in a kneader, melt extruder, or the like.

[0085] The copolymers of the present disclosure or the above-described compositions can be used as processing aids, molding materials, etc., but are preferably used as molding materials. Aqueous dispersions, solutions, suspensions, and copolymer / solvent systems of the copolymers of the present disclosure are also available, and these can be applied as coatings or used for encapsulation, impregnation, and film casting. However, because the copolymers of the present disclosure have the above-described properties, they are preferably used as molding materials.

[0086] The copolymer of the present disclosure or the above-described composition may be molded to obtain a molded article.

[0087] The method for molding the copolymer or the composition is not particularly limited, and examples thereof include compression molding, transfer molding, extrusion molding, blow molding, roto-molding, and roto-lining molding. Among these, compression molding, extrusion molding, and transfer molding are preferred as molding methods, with extrusion molding and transfer molding being more preferred from the standpoint of ease of production, and transfer molding being even more preferred because it is easy to produce multiple pieces and produces uniform molded products, allowing molded articles to be produced with high productivity. That is, the molded article is preferably an extrusion molded article, a compression molded article, or a transfer molded article, and more preferably a transfer molded article because it can be produced with high productivity.

[0088] The shape of the molded article is not particularly limited, and may be, for example, a hose, a pipe, a tube, a wire coating, a sheet, a seal, a gasket, a packing, a film, a tank, a roller, a bottle, a container, or the like.

[0089] The copolymer of the present disclosure, the above-described composition, or the above-described molded article can be used, for example, in the following applications. Food packaging films, lining materials for fluid transfer lines used in food manufacturing processes, packings, sealing materials, sheets and other fluid transfer components for food manufacturing equipment; Chemical stoppers, packaging films, lining materials for fluid transfer lines used in pharmaceutical manufacturing processes, packings, sealing materials, sheets and other chemical transfer components; Inner lining materials for chemical tanks and pipes in chemical plants and semiconductor factories; O-rings, tubes, packings, valve core materials, hoses, seals, etc. used in automobile fuel systems and peripheral devices; fuel transfer components such as hoses and seals used in automobile automatic transmission systems; Carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, hoses, etc. used in automobile engines and peripheral devices, automobile brake hoses, air conditioner hoses, radiator hoses, electrical wire covering materials, and other automobile parts; Semiconductor manufacturing equipment O-rings, tubes, packing, valve core materials, hoses, seal materials, rolls, gaskets, diaphragms, joints and other chemical liquid transfer components for semiconductor devices; Paint rolls for painting equipment, hoses, tubes, ink containers and other paint and ink components; Food and beverage tubes and food and beverage hoses and other tubes, hoses, belts, packings, joints and other food and beverage transport components, food packaging materials, glass cooking equipment; Waste liquid transport components such as tubes and hoses for transporting waste liquid; High-temperature liquid transport components such as tubes and hoses for transporting high-temperature liquids; Steam piping components such as steam piping tubes and hoses; Anti-corrosion tapes for piping, such as tapes wrapped around piping on ship decks, etc.; Various coating materials such as electrical wire coating materials, optical fiber coating materials, transparent surface coating materials and backing materials to be applied to the light incident surface of photovoltaic elements in solar cells; Sliding parts such as diaphragms for diaphragm pumps and various packings; Agricultural films, weather-resistant covers for various roofing materials and side walls; Interior materials used in the construction industry, and glass covering materials such as non-flammable fire-resistant safety glass; Lining materials such as laminated steel sheets used in the home appliance sector;

[0090] Further examples of the fuel transfer members used in the fuel systems of the above-mentioned automobiles include fuel hoses, filler hoses, evaporation hoses, etc. The above-mentioned fuel transfer members can also be used as fuel transfer members for sour gasoline, alcohol-resistant fuels, and fuels containing gasoline additives such as methyl tertiary butyl ether-resistant and amine-resistant.

[0091] The chemical stoppers and packaging films for chemicals have excellent chemical resistance to acids, etc. Another example of the chemical liquid transfer member is anticorrosion tape that is wrapped around pipes in chemical plants.

[0092] Examples of the molded article include automobile radiator tanks, chemical tanks, bellows, spacers, rollers, gasoline tanks, containers for transporting waste liquids, containers for transporting high-temperature liquids, and tanks for fishing and fish farming.

[0093] Further examples of the molded article include components used for automobile bumpers, door trims, instrument panels, food processing equipment, cooking appliances, water- and oil-repellent glass, lighting-related equipment, display panels and housings for office automation equipment, illuminated signs, displays, liquid crystal displays, mobile phones, printed circuit boards, electric and electronic components, miscellaneous goods, trash cans, bathtubs, modular baths, ventilation fans, lighting frames, etc.

[0094] The molded article containing the copolymer of the present disclosure has excellent heat resistance and moldability, can be produced without corroding the mold when a mold is used, has excellent low water vapor permeability and low electrolyte permeability, is less likely to leak electrolyte, has excellent sealing properties at high temperatures while maintaining appropriate compression set, and is less likely to elute fluorine ions into the electrolyte, and therefore can be suitably used as a compressed member containing the copolymer. As a molding method using the above mold, transfer molding is suitable.

[0095] The compressed member of the present disclosure exhibits an appropriate compression set rate and high surface pressure even when deformed at a high compression deformation rate. The compressed member of the present disclosure can be used in a state compressed and deformed at a compression deformation rate of 10% or more, and can be used in a state compressed and deformed at a compression deformation rate of 20% or more or 25% or more. By using the compressed member of the present disclosure after being deformed at such a high compression deformation rate, a certain level of rebound resilience can be maintained for a long period of time, and sealing and insulating properties can be maintained for a long period of time.

[0096] The compressed member of the present disclosure exhibits a high storage modulus, a high recovery amount, and a very high surface pressure even when deformed at a high compression deformation rate at high temperatures. The compressed member of the present disclosure can be used in a state compressed and deformed at 150°C or higher and a compression deformation rate of 10% or more, or in a state compressed and deformed at 150°C or higher and a compression deformation rate of 20% or more or 25% or more. By using the compressed member of the present disclosure after deforming it at such high temperatures and a high compression deformation rate, it is possible to maintain a certain level of rebound resilience even at high temperatures for a long period of time, and to maintain sealing and insulating properties at high temperatures for a long period of time.

[0097] The above-mentioned compressive deformation ratio is the compressive deformation ratio of the portion with the largest compressive deformation ratio when the compressed member is used in a compressed state. For example, when a flat compressed member is used in a state compressed in its thickness direction, it is the compressive deformation ratio in the thickness direction. Furthermore, for example, when the compressed member is used in a state where only a portion is compressed, it is the compressive deformation ratio of the portion with the largest compressive deformation ratio among the compressed portions.

[0098] The size and shape of the compressible member of the present disclosure may be appropriately set depending on the application and are not particularly limited. The shape of the compressible member of the present disclosure may be, for example, annular. Furthermore, the compressible member of the present disclosure may have a shape such as a circle, an oval, or a rectangle with rounded corners in a plan view, and may have a through hole in the center.

[0099] The compressible member of the present disclosure is preferably used as a member for constituting a nonaqueous electrolyte battery. The compressible member of the present disclosure has excellent low water vapor permeability and low electrolyte permeability, is resistant to electrolyte leakage, maintains appropriate compression set, has excellent sealing properties at high temperatures, and is resistant to elution of fluoride ions into the electrolyte, making it particularly suitable as a member used in contact with the nonaqueous electrolyte in a nonaqueous electrolyte battery. In other words, the compressible member of the present disclosure may have a surface that comes into contact with the nonaqueous electrolyte in a nonaqueous electrolyte battery.

[0100] The compressible member of the present disclosure is less likely to release fluorine ions into the non-aqueous electrolyte. Therefore, by using the compressible member of the present disclosure, it is possible to suppress an increase in the fluorine ion concentration in the non-aqueous electrolyte. As a result, by using the compressible member of the present disclosure, it is possible to suppress the generation of gases such as HF in the non-aqueous electrolyte battery, and to suppress deterioration of the battery performance and shortening of the battery life.

[0101] The compressible member of the present disclosure can further suppress the generation of gases such as HF in nonaqueous electrolyte batteries and can further suppress deterioration of battery performance and shortening of battery life, so the amount of eluted fluorine ions detected in an electrolyte immersion test is preferably 1.0 ppm or less, more preferably 0.8 ppm or less, and more preferably 0.7 ppm or less, by mass. The electrolyte immersion test can be performed by preparing a test piece having a weight equivalent to 10 molded bodies (15 mm × 15 mm × 0.2 mm) using the compressible member, placing the test piece and 2 g of dimethyl carbonate (DMC) in a glass sample bottle, and leaving it in a constant temperature bath at 80°C for 144 hours.

[0102] The compressible member of the present disclosure has excellent liquid-tightness and low electrolyte permeability, making it difficult for electrolyte to leak or penetrate. Therefore, by using the compressible member of the present disclosure, poor battery performance and a shortened lifespan of a non-aqueous electrolyte battery can be suppressed.

[0103] The amount of electrolyte leakage from the compressed member of the present disclosure is preferably 0.0030 g / 1000 hrs or less, and more preferably 0.0025 g / 1000 hrs or less, because this can further suppress poor battery performance and shortened life of the nonaqueous electrolyte battery. The amount of electrolyte leakage from the compressed member can be measured by the method described in the Examples.

[0104] The compressible member of the present disclosure is less permeable to water vapor. Therefore, by using the compressible member of the present disclosure, it is possible to suppress the permeation of water vapor from the outside into the secondary battery. As a result, by using the compressible member of the present disclosure, it is possible to suppress the deterioration of battery performance and the shortening of the lifespan of the nonaqueous electrolyte battery.

[0105] The water vapor permeability of the compressible member of the present disclosure is preferably 11.0 g cm / m because this can further suppress deterioration of the battery performance and shortened life of the nonaqueous electrolyte battery. 2 or less, and more preferably 10.0 g cm / m 2 or less, and more preferably 9.8 g cm / m 2 The water vapor permeability can be measured at 95°C for 30 days.

[0106] The nonaqueous electrolyte battery is not particularly limited as long as it is a battery containing a nonaqueous electrolyte, and examples thereof include a lithium ion secondary battery, a lithium ion capacitor, etc. Furthermore, examples of components constituting the nonaqueous electrolyte battery include a sealing member, an insulating member, etc.

[0107] The nonaqueous electrolyte may be one or more of known solvents, such as, but not limited to, propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyl lactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The nonaqueous electrolyte battery may further include an electrolyte. The electrolyte may be, but is not limited to, LiClO4, LiAsF6, LiPF6, LiBF4, LiCl, LiBr, CH3SO3Li, CF3SO3Li, cesium carbonate, or the like.

[0108] The compressible member of the present disclosure can be suitably used, for example, as a sealing member such as a sealing gasket or sealing packing, or an insulating member such as an insulating gasket or insulating packing. A sealing member is a member used to prevent leakage of liquid or gas or intrusion of liquid or gas from the outside. An insulating member is a member used for electrical insulation. The compressible member of the present disclosure may be a member used for both sealing and insulating purposes.

[0109] The compressible member of the present disclosure has excellent heat resistance and extremely excellent sealing properties at high temperatures, and therefore can be suitably used in high-temperature environments. For example, the compressible member of the present disclosure is suitably used in environments where the maximum temperature is 40°C or higher. For example, the compressible member of the present disclosure is suitably used in environments where the maximum temperature is 150°C or higher. Examples of situations in which the compressible member of the present disclosure may reach such high temperatures include when the compressible member is attached to a battery in a compressed state and then other battery components are attached to the battery by welding, or when a non-aqueous electrolyte battery generates heat.

[0110] The compressible member of the present disclosure has excellent low water vapor permeability and low electrolyte permeability, is resistant to electrolyte leakage, maintains appropriate compression set, exhibits excellent sealing properties at high temperatures, and is resistant to elution of fluoride ions into the electrolyte. Therefore, it can be suitably used as a sealing member or an insulating member for a nonaqueous electrolyte battery. For example, when a battery such as a nonaqueous electrolyte secondary battery is charged, the battery temperature may temporarily reach 40°C or higher, particularly 150°C or higher. The compressible member of the present disclosure does not lose its high resilience even when used in a battery such as a nonaqueous electrolyte secondary battery, where it is deformed at a high compressive deformation rate at high temperatures, or even when it comes into contact with a nonaqueous electrolyte at high temperatures. Therefore, when used as a sealing member, the compressible member of the present disclosure exhibits excellent sealing properties, and these sealing properties are maintained for a long period of time even at high temperatures. Furthermore, the compressible member of the present disclosure, due to the inclusion of the copolymer, exhibits excellent insulating properties. Therefore, when the compressed member of the present disclosure is used as an insulating member, it adheres firmly to two or more conductive members, preventing short circuits for a long period of time.

[0111] The copolymer of the present disclosure has a low dielectric loss tangent at 6 GHz and can therefore be suitably used as a material for high-frequency signal transmission products.

[0112] The high-frequency signal transmission product is not particularly limited as long as it is a product used for transmitting high-frequency signals, and examples include (1) molded plates such as insulating plates for high-frequency circuits, insulators for connecting parts, and printed wiring boards, (2) molded articles such as bases for high-frequency vacuum tubes and antenna covers, and (3) coated electric wires such as coaxial cables and LAN cables. The high-frequency signal transmission product can be suitably used in devices that use microwaves, particularly microwaves of 3 to 30 GHz, such as satellite communication devices and mobile phone base stations.

[0113] In the above-mentioned high-frequency signal transmission product, the copolymer of the present disclosure can be suitably used as an insulator because of its low dielectric loss tangent.

[0114] The (1) molded plate is preferably a printed wiring board because it can provide good electrical properties. Examples of the printed wiring board include, but are not limited to, printed wiring boards for electronic circuits in mobile phones, various computers, communication devices, etc. The (2) molded article is preferably an antenna cover because it has low dielectric loss.

[0115] The above-mentioned (3) coated electric wire is preferably a coated electric wire having a coating layer containing the copolymer of the present disclosure. That is, a molded article containing the copolymer of the present disclosure can be suitably used as the coating layer.

[0116] Commercially available tetrafluoroethylene / fluoro(alkyl vinyl ether) copolymers are known to have a continuous use temperature of 260° C. Continuous use temperature refers to the maximum operating temperature that the polymer can withstand continuously. In recent years, there has been a need for copolymers that can be used in more severe working environments, i.e., have continuous use temperatures exceeding 260° C. In many real-world industrial applications in oil and gas fields, there is an emerging need to have melt-processable polymeric materials with continuous use temperatures exceeding 260° C. to withstand the extremely high operating temperatures encountered in construction work, for example. For example, during deep drilling, data communication cables may be exposed to temperatures of 280° C. or higher in downhole wells. A molded article containing the copolymer of the present disclosure can have a continuous use temperature of 280°C. A molded article containing the copolymer of the present disclosure does not melt even at the extremely high temperature of 280°C, and the coating layer made of the molded article maintains its coating without forming ruptures or cracks due to thermal load, allowing for continuous use. Therefore, a molded article containing the copolymer of the present disclosure is suitable for use as a coating layer of a coated electric wire used in an environment with a maximum temperature of 280°C or higher.

[0117] The coated electric wire includes a core wire and a coating layer surrounding the core wire and containing the copolymer of the present disclosure. For example, the coating layer can be an extrusion molded product obtained by melt-extrusion molding the copolymer of this embodiment onto the core wire. The coated electric wire is suitable for use as a high-frequency transmission cable, a flat cable, a heat-resistant cable, etc., since the coating layer has excellent heat resistance and a low dielectric loss tangent.

[0118] The core wire may be made of a metal conductor material such as copper or aluminum. The core wire preferably has a diameter of 0.02 to 3 mm. The core wire diameter is more preferably 0.04 mm or more, even more preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. The core wire diameter is more preferably 2 mm or less.

[0119] Specific examples of the core wire include AWG (American Wire Gauge)-46 (solid copper wire with a diameter of 40 micrometers), AWG-26 (solid copper wire with a diameter of 404 micrometers), AWG-24 (solid copper wire with a diameter of 510 micrometers), and AWG-22 (solid copper wire with a diameter of 635 micrometers).

[0120] The thickness of the coating layer is preferably 0.1 to 3.0 mm, and more preferably 2.0 mm or less.

[0121] An example of a high-frequency transmission cable is a coaxial cable. A 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 layered in this order from the core to the outer periphery. A molded article containing the copolymer of the present disclosure can be suitably used as an insulating coating layer containing a copolymer. The thickness of each layer in the above structure is not particularly limited, but typically the inner conductor has a diameter of about 0.1 to 3 mm, the insulating coating layer has a thickness of about 0.3 to 3 mm, the outer conductor layer has a thickness of about 0.5 to 10 mm, and the protective coating layer has a thickness of about 0.5 to 2 mm.

[0122] The coating layer may contain bubbles, and it is preferable that the bubbles are uniformly distributed in the coating layer.

[0123] The average bubble diameter of the bubbles is not limited, but is preferably 60 μm or less, more preferably 45 μm or less, even more preferably 35 μm or less, even more preferably 30 μm or less, particularly preferably 25 μm or less, and especially preferably 23 μm or less. The average bubble diameter is preferably 0.1 μm or more, more preferably 1 μm or more. The average bubble diameter can be determined by taking an electron microscope image of the cross section of the wire, calculating the diameter of each bubble through image processing, and averaging the results.

[0124] The coating layer may have an expansion rate of 20% or more, more preferably 30% or more, even more preferably 33% or more, and even more preferably 35% or more. There is no particular upper limit, but it is, for example, 80%. The upper limit of the expansion rate may be 60%. The expansion rate is a value calculated by ((specific gravity of wire coating material - specific gravity of coating layer) / specific gravity of wire coating material) × 100. The expansion rate can be adjusted appropriately depending on the application, for example, by adjusting the amount of gas introduced into the extruder described below, or by selecting the type of gas to be dissolved.

[0125] The covered electric wire may have another layer between the core wire and the covering layer, or may have another layer (outer layer) around the covering layer. When the covering layer contains bubbles, the electric wire of the present disclosure may have a two-layer structure (skin-foam) in which a non-foamed layer is inserted between the core wire and the covering layer, a two-layer structure (foam-skin) in which a non-foamed layer is covered on the outer layer, or even a three-layer structure (skin-foam-skin) in which a non-foamed layer is covered on a skin-foam outer layer. The non-foamed layer is not particularly limited and may be a resin layer made of a resin such as a TFE / HFP copolymer, a TFE / PAVE copolymer, a TFE / ethylene copolymer, a vinylidene fluoride polymer, a polyolefin resin such as polyethylene (PE), or polyvinyl chloride (PVC).

[0126] The coated electric wire can be produced, for example, by using an extruder to heat the copolymer and extrude the molten copolymer onto a core wire to form a coating layer.

[0127] When forming the coating layer, the copolymer may be heated and a gas may be introduced into the molten copolymer to form the coating layer containing bubbles. Examples of the gas that can be used include chlorodifluoromethane, nitrogen, carbon dioxide, and the like, or a mixture of the above gases. The gas may be introduced into the heated copolymer as a pressurized gas, or may be generated by mixing a chemical foaming agent into the copolymer. The gas dissolves in the molten copolymer.

[0128] Molded articles containing the copolymer of the present disclosure have excellent heat resistance and can therefore be suitably used as films or tubes containing the copolymer.

[0129] Copolymers of tetrafluoroethylene and fluoro(alkyl vinyl ether) have excellent chemical and heat resistance and can be melt-molded, making them useful as release films and surface materials for rolls used in office automation equipment. In recent years, the manufacturing of thin-film products has required high heat resistance to withstand thermal lamination processes, and in the office automation equipment field, the trend toward colorization and increased speed has led to a demand for even higher heat resistance in the surface materials of rolls in the fusing unit, creating a severe situation.

[0130] The copolymer of the present disclosure contains TFE units and PPVE units, and the PPVE unit content and melt flow rate (MFR) of the copolymer are appropriately adjusted, so that films or tubes formed from the copolymer have high heat resistance. The above-mentioned thermal lamination process requires the copolymer to be able to withstand a wide range of temperature conditions, from approximately 100 to 300°C. Because of the above-mentioned configuration, the copolymer of the present disclosure can be used suitably even under harsh temperature conditions. Films containing the copolymer of the present disclosure do not melt even at extremely high temperatures, such as 280°C, and due to their high glass transition temperatures, they can withstand softening up to nearly 100°C. Therefore, films and tubes containing the copolymer of the present disclosure are suitable for use as heat-resistant films in environments with maximum temperatures of 280°C or higher.

[0131] The release film can be produced by molding the copolymer of the present disclosure by extrusion molding, calendar molding, press molding, compression molding, casting molding, etc. From the viewpoint of obtaining a uniform thin film, the release film can be produced by melt extrusion molding.

[0132] The copolymer of the present disclosure can be molded into a required shape by extrusion molding, compression molding, press molding, or the like to form a sheet, film, or tube, and used as a surface material for office equipment rolls, office equipment belts, etc. In particular, thin-walled tubes and films can be produced by extrusion molding.

[0133] The copolymer of the present disclosure can be easily formed into a film of uniform thickness by extrusion molding, and a molded article containing the copolymer of the present disclosure can be suitably used as a film or sheet.

[0134] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0135] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0136] The values ​​in the examples and comparative examples were measured by the following methods.

[0137] (Monomer unit content) The content of each monomer unit was measured using an NMR analyzer (for example, AVANCE300 high temperature probe manufactured by Bruker Biospin).

[0138] (Melt flow rate (MFR)) According to ASTM D1238, the mass of polymer flowing out per 10 minutes (g / 10 minutes) from a nozzle with an inner diameter of 2.1 mm and a length of 8 mm under a load of 5 kg at 372°C was determined using a Melt Indexer G-01 (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0139] (Number of functional groups) The copolymer pellets were molded by cold pressing to produce a film with a thickness of 0.25 to 0.30 mm. This film was scanned 40 times using a Fourier transform infrared spectrometer (FT-IR (Spectrum One, manufactured by PerkinElmer)) to obtain an infrared absorption spectrum. A difference spectrum was obtained from the base spectrum, which was completely fluorinated and had no functional groups. From the absorption peaks of specific functional groups that appeared in this difference spectrum, the carbon atom ratio (1 × 10) of the sample was calculated according to the following formula (A): 6 The number of functional groups per molecule, N, was calculated. N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm) For reference, the absorption frequencies, molar extinction coefficients, and correction factors for the functional groups in this disclosure are shown in Table 2. The molar extinction coefficients were determined from FT-IR measurement data of low molecular weight model compounds.

[0140] [Table 2]

[0141] (Melting Point) Using a differential scanning calorimeter (product name: X-DSC7000, manufactured by Hitachi High-Tech Science Corporation), the sample was heated a first time from 200°C to 350°C at a heating rate of 10°C / min, then cooled from 350°C to 200°C at a cooling rate of 10°C / min, and then heated a second time from 200°C to 350°C at a heating rate of 10°C / min. The melting point was determined from the peak of the melting curve that appeared during the second heating process.

[0142] (glass transition temperature (Tg)) Dynamic viscoelasticity was measured using a dynamic viscoelasticity analyzer DVA-220 (manufactured by IT Measurement & Control Co., Ltd.) at a temperature rise rate of 2°C / min and a frequency of 10 Hz, and the temperature at the peak of the tan δ value was determined as the glass transition temperature.

[0143] Example 1 A 174 L autoclave was charged with 53.8 L of purified water and thoroughly purged with nitrogen. Then, 41.7 kg of perfluorocyclobutane, 0.51 kg of perfluoro(propyl vinyl ether) (PPVE), and 0.93 kg of methanol were added. The system temperature was maintained at 35°C and the stirring speed at 200 rpm. Tetrafluoroethylene (TFE) was then introduced to 0.5 MPa, and 0.112 kg of a 50% methanol solution of di-n-propyl peroxydicarbonate was added to initiate polymerization. As the polymerization progressed, the system pressure decreased, so TFE was continuously fed to maintain a constant pressure. PPVE was added at 0.026 kg for every 1 kg of TFE added, and the polymerization was continued for 9 hours. After releasing the TFE and returning the autoclave to atmospheric pressure, the resulting reaction product was washed with water and dried to obtain 30 kg of powder.

[0144] The resulting powder was melt-extruded at 360°C using a screw extruder (product name: PCM46, manufactured by Ikegai Corporation) to obtain pellets of a TFE / PPVE copolymer. The PPVE content of the resulting pellets was measured using the method described above. The results are shown in Table 3.

[0145] The resulting pellets were placed in a vacuum vibration reactor VVD-30 (manufactured by Okawara Manufacturing Co., Ltd.) and heated to 210°C. After evacuation, F2 gas diluted to 20% by volume with N2 gas was introduced until atmospheric pressure was reached. 0.5 hours after the introduction of F2 gas, the reactor was evacuated once and F2 gas was introduced again. 0.5 hours later, the reactor was evacuated again and F2 gas was introduced again. Thereafter, the above F2 gas introduction and evacuation operations were repeated once per hour, and the reaction was carried out at a temperature of 210°C for 10 hours. After the reaction was completed, the atmosphere inside the reactor was thoroughly replaced with N2 gas to terminate the fluorination reaction. Various physical properties of the fluorinated pellets were measured using the methods described above. The results are shown in Table 3.

[0146] Example 2 Fluorinated pellets were obtained in the same manner as in Example 1, except that the amounts of PPVE and methanol were changed to 0.55 kg, 0.31 kg, and 0.028 kg of PPVE was added for every 1 kg of TFE fed, the polymerization time was changed to 10 hours, the temperature rise temperature of the vacuum vibration reactor was changed to 160°C, and the reaction was carried out at 160°C for 5 hours. The results are shown in Table 3.

[0147] Example 3 Fluorinated pellets were obtained in the same manner as in Example 1, except that 0.46 kg of PPVE was added, no methanol was added, 0.100 kg of a 50% methanol solution of di-n-propyl peroxydicarbonate was added, 0.024 kg of PPVE was added for every 1 kg of TFE fed, and the polymerization time was changed to 8 hours. The results are shown in Table 3.

[0148] Example 4 Fluorinated pellets were obtained in the same manner as in Example 1, except that 0.40 kg of PPVE was added, no methanol was added, 0.070 kg of a 50% methanol solution of di-n-propyl peroxydicarbonate was added, 0.020 kg of PPVE was added for every 1 kg of TFE fed, and the polymerization time was changed to 10 hours. The results are shown in Table 3.

[0149] Comparative Example 1 Except for changing the amount of methanol to 1.05 kg, pellets (non-fluorinated pellets) were obtained in the same manner as in Example 1. The results are shown in Table 3.

[0150] Comparative Example 2 A 174 L autoclave was charged with 51.8 L of purified water and thoroughly purged with nitrogen. Then, 40.9 kg of perfluorocyclobutane, 0.37 kg of perfluoro(propyl vinyl ether) (PPVE), and 5.80 kg of methanol were added. The system temperature was maintained at 35°C and the stirring speed at 200 rpm. Tetrafluoroethylene (TFE) was then introduced under pressure to 0.64 MPa, and 0.026 kg of a 50% methanol solution of di-n-propyl peroxydicarbonate was then added to initiate polymerization. As the polymerization progressed, the system pressure decreased, so TFE was continuously fed to maintain a constant pressure. PPVE was added at an additional rate of 0.017 kg for every 1 kg of TFE added. The polymerization was terminated when the amount of TFE added reached 40.9 kg. The unreacted TFE was released, and the autoclave was returned to atmospheric pressure. The resulting reaction product was then washed with water and dried to yield 41.1 kg of powder. The obtained powder was used to carry out a fluorination reaction in the same manner as in Example 1 to obtain fluorinated pellets. The results are shown in Table 3.

[0151] Comparative Example 3 Fluorinated pellets were obtained in the same manner as in Comparative Example 2, except that 0.67 kg of PPVE, 3.81 kg of methanol, 0.013 kg of a 50% methanol solution of di-n-propyl peroxydicarbonate, and 0.022 kg of PPVE were added for every 1 kg of TFE fed. The results are shown in Table 3.

[0152] Comparative Example 4 Fluorinated pellets were obtained in the same manner as in Comparative Example 2, except that the amounts of PPVE and methanol were changed to 1.10 kg, 3.90 kg, and 0.030 kg of PPVE was added for every 1 kg of TFE fed, yielding 41.0 kg of powder. The results are shown in Table 3.

[0153] [Table 3]

[0154] In Table 3, the notation "<6" means that the number of functional groups is less than 6.

[0155] The pellets thus obtained were then evaluated for the following properties, the results of which are shown in Table 4.

[0156] (Water vapor permeability) Using the pellets and a heat press molding machine, a sheet-like test piece with a thickness of approximately 0.2 mm was prepared. The test cup (permeation area 12.56 cm) 2 18g of water was placed in a container, covered with a sheet test piece, and a PTFE gasket was placed between the test pieces and tightened to seal. The sheet test piece was left in contact with the water at a temperature of 95°C for 30 days, then removed and left at room temperature for 2 hours before measuring the mass loss. The water vapor permeability (g·cm / m) was calculated using the following formula: 2 ) was measured. Water vapor permeability (g·cm / m 2 ) = mass loss (g) × thickness of sheet specimen (cm) / permeation area (m 2 )

[0157] (Electrolyte leakage test) Copolymer pellets were placed in a mold (300 mm × 300 mm) and preheated in an electric furnace at 350°C for 1 hour. They were then pressed at 1 MPaG for 1 minute to form a 300 mm × 300 mm × 25 mm thick sheet, which was then allowed to cool to room temperature to obtain a sample sheet (referred to as "HP" (heat press) in Table 4). The sample sheet was then machined to an outer diameter of 17.7 mm, an inner diameter of 14.3 mm, and a thickness of 1.6 mm to obtain a gasket.

[0158] As shown in Figure 1, 2 g of electrolyte 2 was placed in an aluminum alloy cup 1. The electrolyte contained ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC (EC / DEC) of 30 / 70 (volume %). A gasket 7 was placed between the cup 1 and a gasket compression jig 3, and a lid 4 was fastened with bolts 5 to compress the gasket 7. A spacer 6 was placed between the lid 4 and the cup 1, and the compression deformation rate of the gasket 7 was adjusted to 50%. The mass of the test jig 10 thus obtained was measured. The test jig 10 was placed in a thermostatic chamber heated to 60°C and left for 1000 hours, then removed and left at room temperature for 2 hours, after which the mass was measured. The electrolyte leakage amount was calculated using the following formula. This procedure was repeated five times, and the average electrolyte leakage amount was calculated. The average values ​​are shown in Table 4. Electrolyte leakage amount (g / 1000h) = (mass of test jig before heating) - (mass of test jig after heating)

[0159] (Compression set rate (CS)) The compression set rate was measured according to the method described in ASTM D395 or JIS K6262:2013.

[0160] Approximately 2 g of the pellets were placed in a mold (inner diameter 13 mm, height 38 mm) and melted at 370°C for 30 minutes using a hot plate press. After that, the molded body was water-cooled while being pressed at a pressure of 0.2 MPa (resin pressure) to produce a molded body with a height of approximately 8 mm. The molded body was then cut to produce test pieces with an outer diameter of 13 mm and a height of 6 mm. The produced test pieces were compressed at room temperature using a compression device to a compression deformation rate of 50% (i.e., a 6 mm high test piece was compressed to a height of 3 mm).

[0161] Next, the compressed test piece was placed in an electric furnace while still fixed to the compression device and left at 65°C for 72 hours. The compression device was removed from the electric furnace, cooled to room temperature, and the test piece was removed. The recovered test piece was left at room temperature for 30 minutes, after which the height of the recovered test piece was measured and the compression set was calculated using the following formula. Compression set rate (%) = (t0-t2) / (t0-t1) x 100 t0: original height of the specimen (mm) t1: Spacer height (mm) t2: Height of the test piece removed from the compression device (mm) In the above test, t0=6 mm and t1=3 mm.

[0162] (Restored amount) Test specimens were prepared in the same manner as in the measurement of the compression set rate. The prepared test specimens were compressed at room temperature using a compression device to a compression deformation rate of 50% (i.e., a test specimen with a height of 6 mm was compressed to a height of 3 mm). The compressed test specimens were fixed to the compression device and placed in an electric furnace at 150°C for 18 hours. The compression device was removed from the electric furnace, cooled to room temperature, and then the test specimens were removed. The recovered test specimens were left at room temperature for 30 minutes, after which their heights were measured and the recovery amount was calculated using the following formula. Recovery amount (mm) = t2 - t1 t1: Spacer height (mm) t2: Height of the test piece removed from the compression device (mm) In the above test, t1=3 mm.

[0163] (Storage modulus (E')) Dynamic viscoelasticity was measured using a DVA-220 (manufactured by IT Measurement & Control Co., Ltd.) A heat-press molded sheet measuring 25 mm in length, 5 mm in width, and 0.2 mm in thickness was used as a sample test piece. Measurements were performed in the range of 30°C to 250°C at a heating rate of 2°C / min and a frequency of 10 Hz, and the storage modulus (MPa) at 150°C was read.

[0164] (Surface pressure at 150℃) From the results of the compression set test at 150°C and the results of the storage modulus measurement at 150°C, the 150°C surface pressure was calculated using the following formula. 150℃ surface pressure (MPa) = (t2-t1) / t1×E' t1: Spacer height (mm) t2: Height of the test piece removed from the compression device (mm) E': Storage modulus at 150°C (MPa)

[0165] (Electrolyte immersion test) Approximately 5 g of the pellets were placed in a mold (inner diameter 120 mm, height 38 mm) and melted at 370°C for 20 minutes using a hot plate press, then water-cooled while applying a pressure of 1 MPa (resin pressure) to produce a molded body with a thickness of approximately 0.2 mm. Test pieces measuring 15 mm square were then prepared using the molded body.

[0166] Ten of the obtained test pieces and 2 g of electrolyte (dimethyl carbonate (DMC)) were placed in a 20 mL glass sample bottle, and the lid of the sample bottle was closed. The sample bottle was placed in a thermostatic chamber at 80 °C and left for 144 hours to immerse the test pieces in the electrolyte. The sample bottle was then removed from the thermostatic chamber and cooled to room temperature, after which the test pieces were removed from the sample bottle. The remaining electrolyte after removing the test pieces was air-dried in a room controlled at 25 °C for 24 hours, and 2 g of ultrapure water was added. The obtained aqueous solution was transferred to the measurement cell of an ion chromatography system, and the amount of fluoride ions in this aqueous solution was measured using an ion chromatography system (Dionex ICS-2100, manufactured by Thermo Fisher Scientific).

[0167] (Mold corrosion test) 20 g of pellets were placed in a glass container (50 ml screw tube), and a metal pillar (5 mm square, 30 mm long) made of HPM38 (Cr-plated) or HPM38 (Ni-plated) was hung from the glass container so as not to touch the pellets. The glass container was then covered with aluminum foil. The glass container was placed in an oven in this state and heated at 380°C for 3 hours. The heated glass container was then removed from the oven and cooled to room temperature, and the degree of corrosion on the surface of the metal pillar was visually observed. The degree of corrosion was evaluated according to the following criteria. ○: No corrosion observed △: Slight corrosion observed ×: Corrosion is observed

[0168] (dielectric tangent) The pellets were melt-molded to prepare cylindrical test pieces with a diameter of 2 mm. The test pieces were placed in a 6 GHz cavity resonator manufactured by Kanto Electronics Application Development Co., Ltd., and measured using a network analyzer manufactured by Agilent Technologies. The measurement results were analyzed using the analysis software "CPMA" manufactured by Kanto Electronics Application Development Co., Ltd. on a PC connected to the network analyzer, and the dielectric loss tangent (tanδ) at 20°C and 6 GHz was determined.

[0169] (Film heat resistance) Using the pellets obtained in each example, a film was produced using a T-die in a φ14 mm extruder (manufactured by Imoto Machinery Co., Ltd.) under the following extrusion molding conditions. a) Winding speed: 1m / min b) Roll temperature: 120℃ c) Film width: 70mm d) Thickness: 0.10mm e) Extrusion conditions: Single-screw extruder with a cylinder diameter of 14 mm and L / D of 20 Extruder temperature settings: Barrel C-1 (330°C), Barrel C-2 (350°C), Barrel C-3 (370°C), T-die (380°C) The obtained film was cut into a length of 10 cm, ten sheets were stacked, wrapped in aluminum foil, and left in an oven at 280°C for 24 hours. After the heat treatment, the film was removed from the aluminum foil and observed to confirm that the film was not fused. This is indicated by ○ in the table.

[0170] (tube formability) The pellets obtained in each example were extruded using a φ30 mm extruder (manufactured by Tanabe Plastics Machinery) to form a tube having an outer diameter of 10.0 mm and a wall thickness of 1.0 mm. The extrusion molding conditions are as follows. a) Die inner diameter: 20 mm b) Mandrel outer diameter: 13 mm c) Sizing die inner diameter: 10.5 mm d) Take-up speed: 0.4 m / min e)Outer diameter: 10.0mm f) Wall thickness: 1.0mm g) Extrusion conditions: Single-screw extruder with a cylinder diameter of 30 mm and L / D of 22 mm Extruder temperature settings: Barrel section C-1 (330°C), Barrel section C-2 (365°C), Barrel section C-3 (380°C), Head section H-1 (380°C), Die section D-1 (390°C), Die section D-2 (390°C) The obtained tube was cut into a length of 20 cm, 10 pieces were bundled together, wrapped in aluminum foil, and left in an oven at 280°C for 24 hours. After the heat treatment, the tube was removed from the aluminum foil and observed to confirm that the tube was not fused. This is indicated by a circle in the table.

[0171] (Wire coating characteristics) The pellets obtained in each example were extrusion-coated onto a copper conductor having a conductor diameter of 0.812 mm using a 30 mm diameter electric wire coating molding machine (manufactured by Tanabe Plastic Machinery Co., Ltd.) to the following coating thickness to obtain a coated electric wire. The electric wire coating extrusion molding conditions were as follows. a) Core conductor: soft steel wire conductor diameter 0.812 mm (AWG20) b) Coating thickness: 0.9 mm c) Insulated wire diameter: 2.6 mm d) Wire withdrawal speed: 3m / min e) Extrusion conditions: Single-screw extruder with a cylinder diameter of 30 mm and L / D of 22 mm Die (inner diameter) / tip (outer diameter) = 26.0 mm / 8.0 mm Extruder temperature settings: Barrel C-1 (330°C), Barrel C-2 (350°C), Barrel C-3 (370°C), Head H (380°C), Die D-1 (380°C), Die D-2 (380°C). Core wire preheating was set to 80°C.

[0172] The resulting coated electric wires were cut into 20 cm pieces, ten of which were bundled together and wrapped in aluminum foil, and then left in an oven at 280°C for 24 hours. After the heat treatment, the coated electric wires were removed from the aluminum foil and observed to confirm that the coating layer was intact and not fused. This is indicated by a circle in the table.

[0173] (Electrolyte permeability) Using the pellets and a heat press molding machine, a sheet-like test piece with a thickness of approximately 0.2 mm was prepared. The test cup (permeation area 12.56 cm) 2 10 g of dimethyl carbonate (DMC) was placed in a container, covered with a sheet test piece, and a PTFE gasket was placed between them and the container was sealed. The sheet test piece was kept in contact with the DMC at a temperature of 60°C for 30 days, then removed and left at room temperature for 1 hour, after which the mass loss was measured. The DMC permeability (g·cm / m) was calculated using the following formula: 2 ) was sought. Electrolyte permeability (g cm / m 2 ) = mass loss (g) × thickness of sheet specimen (cm) / permeation area (m 2 )

[0174] (extrusion pressure) The extrusion pressure was measured using a twin capillary rheometer RHEOGRAPH 25 (manufactured by Goettfert). The main die had an inner diameter of 1 mm, L / D = 16, and the sub-die had an inner diameter of 1 mm, L / D < 1. The measurement temperature was 390°C, the preheating time after pellet introduction was 10 minutes, and the shear rate was 20 seconds. -1 The extrusion pressure was determined by Burgley correction of the pressure inside the cylinder after 10 minutes of extrusion. Copolymers with low extrusion pressure have excellent moldability, such as extrusion moldability and injection moldability.

[0175] (Self-weight deformation test during melting) Using pellets and a heat press molding machine, a molded body with a diameter of 13 mm and a height of approximately 6.5 mm was produced. The resulting molded body was cut to produce a test piece with a height of 6.3 mm. The produced test piece was placed in a SUS petri dish, heated in an electric furnace at 330°C for 30 minutes, and then water-cooled together with the petri dish containing the test piece. The diameter of the surface (bottom) of the removed test piece that had been in contact with the petri dish was measured with vernier calipers, and the base area increase rate was calculated using the following formula. Base area increase rate (%) = {base area of ​​test piece after heating (mm 2 ) - Base area of ​​test piece before heating (mm 2 )} / base area of ​​test piece before heating (mm 2 ) x 100 The lower the base area increase rate, the less likely the molded product is to deform due to its own weight when melted. A copolymer that gives a molded product with a low base area increase rate is excellent in that even when the copolymer is molded by extrusion molding to produce a thick sheet or a large pipe, the molded product in a molten state is less likely to deform, and a molded product of a desired shape can be obtained after cooling and solidifying.

[0176] [Table 4] [Explanation of symbols]

[0177] 10 Test fixture 1 cup 2 Electrolyte 3 Gasket compression jig 4 Lid 5 volts 6 spacers 7 Gasket

Claims

1. A copolymer consisting of only tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, the content of perfluoro(propyl vinyl ether) units is 2.0 to 2.7 mass% based on the total monomer units; The content of tetrafluoroethylene units is 97.3 to 98.0 mass% based on the total monomer units, A melt flow rate at 372°C is 0.8 to 7.0 g / 10 min, The total number of functional groups, which is the total number of -CF=CF 2 , -CF 2 H, -COF, -COOH, -COOCH 3 , -CONH 2 and -CH 2 OH, is 10 or more when the number of carbon atoms in the main chain is 10. ６ Each piece is 50 or less Copolymer.

2. A compression-molded article comprising the copolymer according to claim 1.

3. An extruded article comprising the copolymer of claim 1.

4. A transfer molding comprising the copolymer according to claim 1.

5. A compressed member comprising the copolymer according to claim 1.

6. A film comprising the copolymer of claim 1.

7. A tube containing the copolymer of claim 1.

8. A coated electric wire having a coating layer containing the copolymer according to claim 1.

9. A pellet containing the copolymer described in claim 1.

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