Copolymer, composition, extrusion molded body, blow molded body, transfer molded body, coated wire, and molded body

Abstract

Provided is a copolymer able to form a molded body having excellent heat resistance, crack resistance following crosslinking, tensile strength and low speed tearing strength. Also provided are a composition, an extrusion molded body, a blow molded body, a transfer molded body, a coated wire, and a molded body.　This copolymer includes a unit derived from tetrafluoroethylene and a unit derived from a perfluoro(alkyl vinyl ether). The content of the unit derived from a perfluoro(alkyl vinyl ether) is 0.5-2.5 mol% relative to the total amount of units contained in the copolymer. The content of the unit derived from tetrafluoroethylene is 97.5-99.5 mol% relative to the total amount of units contained in the copolymer. The number of -COF moieties in the copolymer is more than 40 and not more than 200 per 106 carbon atoms in the copolymer.

Description

Copolymers, compositions, extrusion molded articles, blow molded articles, transfer molded articles, coated electric wires, and molded articles

[0001] The present invention relates to a copolymer, a composition, an extrusion molded article, a blow molded article, a transfer molded article, a coated electric wire, and a molded article.

[0002] Tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (hereinafter also referred to as "PFA") is known as a fluororesin that is excellent in mechanical properties, chemical properties, electrical properties, etc., and is also melt-processable. For example, Patent Document 1 discloses a copolymer containing tetrafluoroethylene units and perfluoro(propyl vinyl ether) units, in which the content of perfluoro(propyl vinyl ether) units is 2.0 to 2.8 mass% based on the total monomer units, and which has a melt flow rate of 23 to 30 g / 10 min.

[0003] Japanese Patent Application Laid-Open No. 2022-058290

[0004] When PFA is used as a constituent material of a molded article, the molded article is required to have excellent properties such as heat resistance and mechanical strength. When the present inventors evaluated a molded article molded using the PFA described in Patent Document 1, they found that there was room for improvement in heat resistance and mechanical strength (particularly, crack resistance, tensile strength, and low-speed tear strength after crosslinking).

[0005] Therefore, an object of the present invention is to provide a copolymer capable of forming a molded article excellent in heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength. Another object of the present invention is to provide a composition containing the copolymer, as well as an extrusion-molded article, a blow-molded article, a transfer-molded article, a coated electric wire, and a molded article.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that by using a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), in which the content of each unit is within a predetermined range and the number of specific functional groups is within a predetermined range, it is possible to form a molded product that is excellent in heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength, and have arrived at the present invention.

[0007] That is, the inventors have found that the above problems can be solved by the following constitution: [1] A copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the content of the units based on perfluoro(alkyl vinyl ether) is 0.5 to 2.5 mol % based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 97.5 to 99.5 mol % based on all units contained in the copolymer, and the number of -COFs in the copolymer is 10 to 100 mol % based on all units contained in the copolymer. ６A copolymer characterized by having more than 40 and not more than 200 per unit. [2] The copolymer according to [1], wherein the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether). [3] The copolymer according to [1] or [2], wherein the melting point is 298°C or higher and 310.5°C or lower. [4] The copolymer according to any one of [1] to [3], wherein the content of units based on the perfluoro(alkyl vinyl ether) is 0.80 to 2.40 mol% based on the total units contained in the copolymer. [5] A composition characterized by containing the copolymer according to any one of [1] to [4]. [6] An extrusion-molded article characterized by being obtained by extrusion molding the copolymer according to any one of [1] to [4] or the composition according to [5]. [7] A blow-molded article characterized by being obtained by blow-molding the copolymer according to any one of [1] to [4] or the composition according to [5]. [8] A transfer molded article obtained by transfer molding the copolymer according to any one of [1] to [4] or the composition according to [5]. [9] A coated electric wire comprising a conductor and a coating layer disposed on the surface of the conductor and obtained by molding the copolymer according to any one of [1] to [4] or the composition according to [5].

[10] A molded article obtained by molding the copolymer according to any one of [1] to [4] or the composition according to [5], wherein the molded article is a piping member, an electric wire coating material, a tube, a film, or a compressed member.

[0008] According to the present invention, there is provided a copolymer capable of forming a molded article having excellent heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength. Furthermore, according to the present invention, there is provided a composition containing the copolymer, as well as an extrusion-molded article, a blow-molded article, a transfer-molded article, a coated electric wire, and a molded article.

[0009] The meanings of terms used in this specification are as follows: A numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0010] The term "unit" refers collectively to an atomic group derived from one molecule of the above-mentioned monomer, which is formed directly by polymerizing the monomer, and an atomic group obtained by chemically converting a part of the above-mentioned atomic group. Hereinafter, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit." A "TFE unit" is a unit based on tetrafluoroethylene contained in the copolymer. A "PAVE unit" is a unit based on perfluoro(alkyl vinyl ether) contained in the copolymer, and a "PPVE unit" is a unit based on perfluoro(propyl vinyl ether) contained in the copolymer.

[0011] [Copolymer] The copolymer of the present invention (hereinafter also referred to as "the copolymer") contains TFE units and PAVE units within a predetermined range. In addition, the copolymer contains a group represented by the chemical formula -COF (-C(=O)-F) at a carbon number of 10 in the copolymer. ６ The number of particles per particle is in the range of more than 40 and not more than 200.

[0012] This copolymer can form molded articles that are excellent in heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength. While the details of the reasons for this are not yet clear, it is presumed to be due to the following reasons. Specifically, it is presumed that the content of tetrafluoroethylene-based units is 97.5 to 99.5 mol% relative to all units contained in the copolymer, and the content of PAVE units is 0.5 mol% or more relative to all units contained in the copolymer, resulting in high flexibility and easy elongation, thereby improving the low-speed tear strength of the molded article. It is presumed that the content of tetrafluoroethylene-based units is 97.5 to 99.5 mol% relative to all units contained in the copolymer, and the content of PAVE units is 2.5 mol% or less relative to all units contained in the copolymer, resulting in high crystallinity and resistance to deformation, thereby improving the tensile strength of the molded article. Furthermore, it is presumed that the number of -COFs in this copolymer is 10 or less, and ... ６ It is presumed that the number of -COFs in the copolymer is more than 40 per unit, and therefore crosslinking starting from -COFs proceeds sufficiently, resulting in good crack resistance after crosslinking.６ It is presumed that the heat resistance was improved because the number of PAVE units per unit was 200 or less, which suppressed the progression of thermal degradation during continuous use at high temperatures. It is presumed that by specifying the content of PAVE units and the number of -COFs in this way, the copolymer was able to form a molded product excellent in heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength.

[0013] The copolymer contains TFE units based on TFE and PAVE units based on PAVE.

[0014] As the PAVE, a monomer represented by formula 1 is preferred: CF ２ ═CF—O—Rf １ (1) In formula 1, Rf １ represents a perfluoroalkyl group having 1 to 10 carbon atoms. １ From the viewpoint of superior polymerization reactivity, the number of carbon atoms in the perfluoroalkyl group represented by the formula (I) is preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 5, and particularly preferably 1 to 3. The perfluoroalkyl group may be linear or branched.

[0015] Specific examples of PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE), with PMVE or PPVE being preferred, and PPVE being more preferred.

[0016] The content of PAVE units is 0.5 to 2.5 mol% based on the total units contained in the copolymer. The content of PAVE units is preferably 0.60 mol% or more, more preferably 0.80 mol% or more, and even more preferably 1.00 mol% or more, from the viewpoint of achieving superior low-speed tear strength of the molded article. Furthermore, the content of PAVE units is preferably 2.45 mol% or less, more preferably 2.40 mol% or less, and even more preferably 2.30 mol% or less, from the viewpoint of achieving superior tensile strength of the molded article. The copolymer may contain two or more types of PAVE units. When the copolymer contains two or more types of PAVE units, this means that the total content of the two or more types of PAVE units is within the above range.

[0017] The content of TFE units is 97.5 to 99.5 mol% based on the total units contained in the copolymer. The content of TFE units is preferably 99.40 mol% or less, more preferably 99.20 mol% or less, from the viewpoint of superior low-speed tear strength of the molded article. Furthermore, the content of TFE units is preferably 97.55 mol% or more, more preferably 97.60 mol% or more, from the viewpoint of superior tensile strength of the molded article.

[0018] In the copolymer, the total content of TFE units and PAVE units is 98.0 to 100.0 mol% based on all units contained in the copolymer, and the total content of TFE units and PAVE units is preferably 98.50 to 100.00 mol% based on all units contained in the copolymer, since the resulting molded article is less likely to be easily deformed by compression or tension.

[0019] In addition to TFE and PAVE, the copolymer may contain units based on other monomers copolymerizable with TFE and PAVE. Examples of such other monomers include ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), and CX. １ X ２ =CX ３ (CF ２ ) ｎ X ４ (In the formula, X １ , X ２ and X ３ are the same or different and represent a hydrogen atom or a fluorine atom; X ４ represents a hydrogen atom, a fluorine atom, or a chlorine atom, and n represents an integer of 1 to 10. ２ =CF-OCH ２ -Rf ２ (wherein, Rf ２ represents a perfluoroalkyl group having 1 to 5 carbon atoms. When the present copolymer contains units based on other monomers, the content of the units based on other monomers is 2.0 mol % or less, and preferably 1.50 to 1.80 mol %, based on the total units contained in the present copolymer.

[0020] In order to obtain a more excellent abrasion resistance during repeated use, it is particularly preferred that the copolymer does not contain units derived from the other monomers and contains only TFE units and PAVE units. In this case, the total content of TFE units and PAVE units is 100.0 mol% based on the total units contained in the copolymer.

[0021] The contents of the TFE units, the PAVE units and the units based on other monomers in the copolymer are as follows: １９ It can be measured by a known method such as F-NMR.

[0022] <Number of -COF> The number of -COF in the present copolymer is ６ The number of carbon atoms in the copolymer is more than 40 and not more than 200 per unit. ６ The number of particles per particle is preferably 45 to 200, more preferably 50 to 190.

[0023] -COF is a functional group present at the main chain terminals and side chain terminals of a copolymer, as well as in the main chain and side chain. -COF can be introduced, for example, by mildly subjecting a copolymer having a specific functional group other than -COF to a fluorination treatment (preferably, a tray-type fluorination treatment) as described below, thereby converting the specific functional group other than -COF to -COF. Specifically, the specific functional group other than -COF is introduced into the copolymer by a chain transfer agent or polymerization initiator used in the production of the copolymer, or by polymerizing a monomer having a specific functional group other than -COF as described below. By mildly subjecting the copolymer to a fluorination treatment (preferably, a tray-type fluorination treatment) as described below, the specific functional group other than -COF can be converted and -COF can be introduced into the copolymer. Alternatively, -COF may be introduced into the copolymer by polymerizing a monomer having -COF, or by a chain transfer agent or polymerization initiator used in the production of the copolymer. If the number of -COFs exceeds a predetermined range, the copolymer is fluorinated to convert -COFs to -CF ３By converting them into terminal groups, the number of -COFs can be reduced. In this case, the number of -COFs in the copolymer can be adjusted by changing the conditions of the fluorination treatment (for example, the treatment time) described below.

[0024] The copolymer is -CF=CF ２ , -CF ２ H, -COOH, -COOCH ３ , -CONH ２ and -CH ２ In the present copolymer, from the viewpoint of superior heat resistance of the molded article, it is preferable to use a functional group selected from the group consisting of -COF, -CF ２ H, CF=CF ２ , -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of functional groups (hereinafter also referred to as "specific functional groups") contained in the group consisting of OH is ６ The total number of specific functional groups per unit area is preferably 300 or less, more preferably 250 or less, and even more preferably 200 or less. ６ More than 40 per unit is preferred, more than 50 is more preferred, and more than 60 is even more preferred.

[0025] The specific functional group is a functional group present at the main chain terminal and side chain terminal, as well as in the main chain and side chain of the copolymer. The specific functional group is introduced into the copolymer by, for example, a chain transfer agent or a polymerization initiator used in the production of the copolymer. For example, when an alcohol is used as a chain transfer agent or when a -CH ２ When a peroxide having an OH structure is used, the main chain terminal of the copolymer is formed with -CH ２ OH is introduced. Furthermore, by polymerizing a monomer having a specific functional group, the functional group is introduced into the side chain terminal of the copolymer. Furthermore, as with -COF, the specific functional group can be reduced by fluorinating the copolymer. In this case, the total number of specific functional groups possessed by the copolymer can be adjusted by changing the method and conditions (e.g., treatment time) of the fluorination treatment described below.

[0026] Infrared spectroscopy can be used to identify the type and measure the number of specific functional groups such as -COF in a copolymer. Specifically, the number of -COF is measured by the following method. First, the copolymer is molded by hot pressing at 330°C to prepare a film with a thickness of 0.30 to 0.35 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) of a copolymer that is completely fluorinated and does not contain specific functional groups such as -COF is obtained, and the difference spectrum between the infrared absorption spectrum of the copolymer and the base spectrum is obtained. The -CF that appears in this difference spectrum ３ From the absorption peak of ６ -CF per piece ３ The number N of specific functional groups is calculated according to the above method, and the total number of specific functional groups is obtained by adding up the calculated values.

[0027] N = I x K / t (A) I: absorbance (absorbance at the absorption frequency of each specific functional group) K: correction coefficient t: film thickness (mm)

[0028] The absorption frequency, molar absorption coefficient, and correction factor for specific functional groups such as -COF are shown in Table 1. The molar absorption coefficient of a specific functional group is determined from FT-IR measurement data of a low molecular weight model compound.

[0029]

[0030] In the copolymer, -CH ２ CF ２ H, —CH ２ COF, -CH ２ COOH, -CH ２ COOCH ３ and -CH ２ CONH ２ The absorption frequency of -CF is shown in the table. ２ H, -COF, -COOH (free and bonded), -COOCH ３ and -CONH２ From each absorption frequency, several tens of Kaiser (cm －１ ) becomes lower. For example, the number of -COF becomes lower. ２ Absorption frequency due to COF: 1883 cm －１ The number of functional groups determined from the absorption peak of -CH ２ Absorption frequency due to COF: 1840 cm －１ The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the

[0031] <Melt Flow Rate> The MFR of the present copolymer is preferably 0.4 g / 10 min or more, more preferably 0.6 g / 10 min or more, and even more preferably 1.0 g / 10 min or more, in order to provide a molded article with superior low-speed tear strength. The MFR of the present copolymer is preferably 55 g / 10 min or less, more preferably 50 g / 10 min or less, and even more preferably 47 g / 10 min ° C or less, in order to provide a molded article with superior tensile strength. A specific example of a method for adjusting the MFR of the present copolymer within the above range is a method of adjusting the molecular weight of the present copolymer. The higher the molecular weight of the present copolymer, the smaller the MFR. The MFR of the copolymer refers to the mass of the copolymer flowing out of an orifice with a diameter of 2 mm and a length of 8 mm in 10 minutes, measured at a temperature of 372 ° C and a load of 5 kg in accordance with ASTM D1238.

[0032] <Melting Point> The melting point of the present copolymer is preferably 298°C or higher, more preferably 299°C or higher, and even more preferably 300°C or higher, from the viewpoint of superior crack resistance. The melting point of the present copolymer is preferably 310.5°C or lower, more preferably 310°C or lower, and even more preferably 309.5°C or lower, from the viewpoint of superior low-speed tear strength of the present copolymer. A specific example of a method for adjusting the melting point of the present copolymer within the above range is a method of lowering the polymerization temperature during production of the present copolymer. The melting point of the copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter.

[0033] <Production Method> The present copolymer can be produced using the above-mentioned monomers (TFE and PAVE) by known methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., and among these, solution polymerization is preferred. In the production of the present copolymer, in addition to the above-mentioned monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, etc. can be used.

[0034] The polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100°C, and more preferably a radical polymerization initiator having the temperature of 20 to 90°C. Specific examples of the polymerization initiator include the various polymerization initiators exemplified in WO 2013 / 015202. The polymerization initiator may be used alone or in combination of two or more types. The amount of the polymerization initiator used is preferably 0.01 to 0.9 parts by mass, more preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of the amount of the monomer used.

[0035] Examples of the polymerization medium include water, organic solvents, and mixed solvents of water and organic solvents. Fluorine-based solvents such as perfluorocarbons, hydrofluorocarbons, and hydrofluoroethers can be used as the organic solvent. Specific examples of the organic solvent include the polymerization media exemplified in International Publication No. 2013 / 015202. The polymerization medium may be used alone or in combination of two or more. A mixed solvent of water and a fluorine-based solvent is preferred as the polymerization medium, and a mixed solvent of water and a perfluorocarbon is more preferred. From the standpoints of suspension and economy, the amount of the fluorine-based solvent used is preferably 10 to 100% by mass relative to the mixed solvent. The amount of the polymerization medium used is preferably 3 times or more, more preferably 5 times or more, by mass relative to the amount of the monomer used. Furthermore, the amount is preferably 20 times or less, more preferably 17 times or less.

[0036] The chain transfer agent may be selected from the group consisting of alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, and 2,2,3,3,3-pentafluoropropanol, hydrocarbons such as n-pentane, n-hexane, and cyclohexane, and CF ２H ２ Preferred are hydrofluorocarbons such as acetone, ketones such as acetone, mercaptans such as methyl mercaptan, esters such as methyl acetate and ethyl acetate, and ethers such as diethyl ether and methyl ethyl ether. Among these, at least one selected from the group consisting of alcohols, hydrocarbons, and hydrofluorocarbons is preferred, as they have a higher chain transfer constant and provide high stability to the end groups of the copolymer. At least one selected from the group consisting of alcohols and hydrocarbons is more preferred, and alcohols are even more preferred. Among alcohols, methanol or ethanol is preferred, with methanol being more preferred in terms of reactivity and availability. Two or more chain transfer agents may be used. The amount of chain transfer agent used is preferably 0.001 times or more, more preferably 0.005 times or more, by mass, relative to the amount of monomer used. Also, it is preferably 5 times or less, more preferably 4 times or less.

[0037] The polymerization temperature is preferably 15 to 60°C, more preferably 20 to 58°C, and even more preferably 25 to 55°C. When the polymerization temperature is 25°C or higher, the polymerizability is excellent. When the polymerization temperature is 60°C or lower, the melting point of the copolymer can be improved. The polymerization pressure is preferably 0.5 to 3.0 MPa, more preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0038] When an aqueous dispersion containing the copolymer is obtained by polymerization, 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 polymerization, 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.

[0039] The copolymer obtained by polymerization may be formed into pellets. Copolymer pellets can be formed by conventional methods. Examples of methods for forming pellets include extruding the copolymer while melting it using a single-screw extruder, twin-screw extruder, or tandem extruder, cutting it to a predetermined length, and forming it into pellets. The extrusion temperature during melt extrusion varies depending on the melt viscosity of the copolymer and the production method, but is preferably between the melting point of the copolymer + 20°C and the melting point of the copolymer + 140°C. Conventional methods, such as strand cutting, hot cutting, underwater cutting, and sheet cutting, can be used to cut the copolymer. The resulting pellets may be heated to remove volatile components (degassing treatment). The resulting pellets may also 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.

[0040] The copolymer obtained by polymerization may be subjected to a fluorination treatment. By the fluorination treatment, -COF contained in the copolymer is converted to -CF ３ Alternatively, specific functional groups other than -COF can be converted to -COF. Therefore, the number of -COFs in the copolymer can be easily adjusted to a predetermined range. Furthermore, the fluorination treatment can also convert specific functional groups other than -COFs in the copolymer to -CF ３ Therefore, even if the total number of specific functional groups in the copolymer exceeds a predetermined range, the total number of specific functional groups can be easily reduced by the fluorination treatment.

[0041] The fluorination treatment is carried out by contacting the copolymer that has not been fluorinated with a fluorine-containing compound. The fluorine-containing compound may be a fluorine radical source that generates fluorine radicals under the conditions of the fluorination treatment. The fluorine radical source may be F ２ Gas, N ２ F ２ and halogen fluorides (e.g., IF ５ , ClF ３ ) are listed.

[0042] F ２The concentration of the fluorine radical source such as gas may be 100% by volume. ２ It is preferable to use a mixed gas obtained by diluting with an inert gas so that the gas concentration is 5 to 50% by volume (more preferably 15 to 30% by volume). Examples of the inert gas include nitrogen gas, helium gas, and argon gas, but nitrogen gas is preferable from an economical standpoint.

[0043] As a specific method of the fluorination treatment, for example, a shelf on which copolymer pellets are placed is placed in an oven, and the inside of the oven is heated to F ２ A plate-type fluorination treatment is also possible, in which a column is filled with a gas or the above-mentioned mixed gas and heated for a certain period of time without passing gas through it. ２ Examples of such a method include a flow-through fluorination treatment in which a gas or the above-mentioned mixed gas is passed through for a certain period of time. When comparing the former tray-type treatment with the latter flow-through treatment, the tray-type treatment makes it easier to control the number of -COFs than the flow-through treatment, although the detailed reasons are unclear. Specifically, when a copolymer is subjected to the tray-type treatment, the number of -COFs tends to increase in the initial stage of the fluorination treatment, and then the number of -COFs tends to gradually decrease with the passage of treatment time. On the other hand, when a copolymer is subjected to the flow-through treatment, the number of -COFs tends to be less likely to increase. Therefore, it can be said that the number of -COFs is easier to control with the tray-type treatment.

[0044] The fluorination treatment is usually carried out at a temperature below the melting point of the copolymer, preferably 20 to 240°C, more preferably 100 to 235°C. The fluorination treatment may be carried out by contacting the copolymer in a molten state with a fluorine-containing compound. The treatment time for the fluorination treatment depends on the amount of -CF contained in the copolymer before the fluorination treatment. ２The time period varies depending on the number of specific functional groups such as H, the number of target -COFs, the fluorination treatment method, and the like, but is, for example, 1 to 30 hours, preferably 1 to 24 hours. The reaction pressure for the fluorination treatment may be either atmospheric pressure (1 atm) or elevated pressure, with atmospheric pressure (1 atm) being preferred. In the fluorination treatment, the fluorine-containing compound may be added all at once or in portions. When adding portions in portions, the fluorine-containing compound may be evacuated from the reaction system to remove the fluorine-containing compound and the like, and then a new fluorine-containing compound may be supplied, since this facilitates control of the number of -COFs. The fluorination treatment may be carried out once or twice or more times. The present copolymer is preferably produced by obtaining a copolymer by polymerization and then subjecting the copolymer to the above-mentioned fluorination treatment. In particular, the above-mentioned tray-type fluorination treatment is more preferred, since this facilitates control of the number of -COFs.

[0045] [Composition] The composition of the present invention (hereinafter also referred to as "the present composition") contains the above-described present copolymer. Since the present composition contains the present copolymer, by using the present composition, a molded article having excellent crack resistance, adhesion, heat resistance, tensile strength, and low-speed tear strength after crosslinking can be formed. The content of the present copolymer is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, and even more preferably 90% by mass or more and less than 100% by mass, based on the total mass of the present composition.

[0046] <Other Components> The present composition may contain other components in addition to those described above. Specific examples of such other components include resins other than the present copolymer, heat stabilizers, antioxidants, colorants, UV absorbers, fillers, crosslinking agents, crosslinking aids, and organic peroxides. When the present composition contains other components, the content of the other components is preferably 0.0000001 to 70 parts by mass, more preferably 0.0000005 to 60 parts by mass, and even more preferably 0.000001 to 50 parts by mass, per 100 parts by mass of the present copolymer in the composition.

[0047] The present composition can be produced by melt-kneading the present copolymer and the above-mentioned components, which are used as needed, by a known method.

[0048] [Molded Article] The molded article of the present invention is obtained by molding the present copolymer or the present composition. Since the present molded article contains the present copolymer, it has excellent tensile strength after a chemical resistance test, tensile strength after a heat aging test, and tensile elongation after a heat aging test. Specific examples of molded articles include injection-molded articles obtained by injection molding the present copolymer or the present composition, extrusion-molded articles obtained by extrusion molding, blow-molded articles obtained by blow molding, transfer-molded articles obtained by transfer molding, press-molded articles obtained by press molding, rotation-molded articles obtained by rotation-molding, and coating films obtained by electrostatic coating. The molded article is preferably a press-molded article obtained by press molding. Injection-molded articles are also preferred because they can be obtained with beautiful appearance without corroding the mold used for molding.

[0049] Specific examples of the molded article of the present invention include nuts, bolts, joints, films, bottles, gaskets, wire coating materials, tubes, hoses, pipes, valves, sheets, seals, packing, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, pumps, wafer carriers, and wafer boxes.

[0050] The present copolymer, the present composition, or the above-mentioned molded article can be used for the following purposes. Fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in food manufacturing processes; chemical liquid transfer components, such as chemical stoppers, packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in chemical manufacturing processes; inner lining components for chemical liquid tanks and piping in chemical plants or semiconductor factories; fuel transfer components, such as O-rings, tubes, packings, valve core materials, hoses, and sealing materials used in automotive fuel systems and peripheral devices, and hoses and sealing materials used in automotive automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automotive engines and peripheral devices, as well as other automotive components, such as automotive brake hoses, air conditioner hoses, radiator hoses, and wire coating materials; chemical liquid transfer components for semiconductor manufacturing equipment, such as O-rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and fittings; coating and ink components such as paint rolls, hoses, tubes, and ink containers for coating equipment; food and beverage transport components such as tubes, hoses, belts, packing, and joints, such as food and beverage tubes or food and beverage hoses, food packaging materials, and 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 tubes and hoses for steam piping; anti-corrosion tapes for piping, such as tapes wrapped around piping on ship decks, etc.; various coating materials such as electric wire coating materials, optical fiber coating materials, and transparent surface coating materials and backing agents applied to the light-incident surface of photovoltaic elements in solar cells; sliding components such as diaphragms and various packings for diaphragm pumps; agricultural films, carrier films for fuel cells, and weather-resistant covers for various roofing materials and side walls, etc.; interior materials used in the construction field, and glass coating materials such as non-flammable fire-resistant safety glass; lining materials such as laminated steel sheets used in home appliances, etc.

[0051] In particular, the molded article of the present invention can be suitably used as piping components (e.g., piping, joints, gaskets, and packings), tubes, or films for transporting fluids. The molded article of the present invention can also be suitably used as a wire coating material. A specific example of use is a coated electric wire comprising a conductor and a coating layer made of the molded article of the present invention, disposed on the surface of the conductor. A coated electric wire having a coating layer made of the molded article of the present invention has excellent electrical properties because the conductor is resistant to corrosion and there is little change in outer diameter, and is therefore suitably used as a high-frequency transmission cable, a flat cable, a heat-resistant cable, or the like. Such a coated electric wire can be produced, for example, by melt-extrusion molding the present copolymer or the present composition onto a core wire to form a coating layer.

[0052] The molded article of the present invention can also be suitably used as a compressed member. The compressed member is a member used in a compressed and deformed state, and the size and shape of the compressed member are appropriately set depending on the application. The shape of the compressed member may be, for example, annular. The compressed member 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 its center. The compressed member can be used as a piping member for transporting fluids. The compressed member can also be used as a member for constituting a nonaqueous electrolyte battery, and is particularly suitable as a member used in contact with the nonaqueous electrolyte in the nonaqueous electrolyte battery. The compressed member can also be suitably used as a sealing member such as a sealing gasket and a sealing packing, and as an insulating member such as an insulating gasket and an insulating packing. A sealing member is a member used to prevent the leakage of liquid or gas or the intrusion of liquid or gas from the outside. An insulating member is a member used for electrical insulation. The compressed member may be a member used for both sealing and insulating purposes.

[0053] The present invention will be described in detail below with reference to examples. Examples 1 to 32 are working examples, and Examples 33 to 36 are comparative examples. However, the present invention is not limited to these examples. Various measurement methods and evaluation methods are as follows.

[0054] [Ratio of Each Unit] The contents (mol %) of TFE units and PAVE units in the copolymer are １９ Calculated by F-NMR analysis.

[0055] [MFR (Melt Flow Rate)] Using a melt indexer (manufactured by Techno Seven Co., Ltd.), the mass (g) of the copolymer flowing out of an orifice having a diameter of 2 mm and a length of 8 mm in 10 minutes was measured under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238, and this was taken as the MFR (g / 10 min).

[0056] [Melting Point] The melting point (°C) of the copolymer was determined from the endothermic peak observed when the copolymer was heated to 340°C at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter (trade name "DSC7020", manufactured by Hitachi High-Tech Science Corporation).

[0057] [Number of specific functional groups (-COF, etc.)] Pellets of copolymer F obtained in each example were molded by hot pressing at 330°C to produce a film with a thickness of 0.30 to 0.35 mm. This film was scanned 40 times using a Fourier transform infrared spectrometer (FT-IR, "Spectrum One", manufactured by PerkinElmer) and analyzed to obtain an infrared absorption spectrum. Next, each of the above pellets was subjected to a fluorination treatment described below for a long period of time, and pellets of each base copolymer that were completely fluorinated and had no specific functional groups were separately prepared, and a base film was obtained in the same manner as above. A difference spectrum from the spectrum of the base film (base spectrum) was obtained. From the absorption peaks of the specific functional groups appearing in this difference spectrum, the number of carbon atoms of the copolymer in each sample was calculated according to the above formula A. ６ The number of -COFs per molecule and the total number of specific functional groups were calculated.

[0058] [Evaluation test]

[0059] <Heat Resistance> An injection molding machine (ROBOSHOT α-50C, manufactured by FANUC Corporation) was used. The mold was engraved to obtain molded articles with design dimensions of 12 mm width, 120 mm length, and 3 mm thickness, and a tunnel gate with a gate tip diameter of 1.0 mm was used. Molding of pellets of copolymer F obtained in each example was performed under the following molding conditions: cylinder temperature: 385°C, mold temperature: 190°C, injection speed: 20 mm / sec, dwell pressure: 50 MPa, dwell time: 3 seconds, and cooling time: 30 seconds, to obtain molded articles. The obtained injection-molded articles were observed and evaluated according to the following criteria. (Evaluation Criteria) ∘: No bubbles or voids were observed. ×: Bubbles or voids were observed.

[0060] <Crack Resistance After Crosslinking> Using pellets of copolymer F obtained in each example, test specimens measuring 12.5 mm in width, 130 mm in length, and 0.23 mm in thickness were prepared. The prepared test specimens were irradiated with an electron beam (EB) at 5 kGy in air (in the presence of oxygen) to obtain EB-irradiated test specimens. The EB-irradiated test specimens were mounted on an MIT measuring instrument manufactured by Toyo Seiki Seisakusho, Ltd., and bent under conditions of a load of 1.25 kg, a left-right bending angle of 135 degrees each, and a bending frequency of 175 times / min, and the number of times until the test specimen broke was measured. This test is a bending fatigue test of the copolymer and serves as an index of crack resistance. A higher number of bending times indicates better crack resistance after crosslinking. The crack resistance of each test specimen after crosslinking was evaluated based on the number of bending times according to the following evaluation criteria. (Evaluation criteria for crack resistance after crosslinking) ○: Number of bending times 500 or more ×: Number of bending times less than 500

[0061] <Film Forming> The pellets of copolymer F obtained in each example were press-molded at 340°C to obtain a film having a thickness of 1 mm and a film (molded body) having a thickness of 0.1 mm. The press molding was performed using a heated press ("SA-301" manufactured by Tester Sangyo Co., Ltd.). The obtained films were subjected to the following evaluation tests.

[0062] <Tensile Strength> Dumbbell-shaped test pieces as specified in ASTM-D638 Type V were cut out from the obtained film having a thickness of 1 mm. The obtained test pieces were measured for tensile strength (unit: MPa) by pulling them at a pulling rate of 200 mm / min in a room temperature environment of 23±2°C using a Strograph (manufactured by Toyo Seiki Seisakusho, Ltd.) with the distance between the gripping jigs set to 35 mm. The tensile strength of each test piece was evaluated based on the measured tensile strength values ​​and the following evaluation criteria. (Evaluation criteria for tensile strength) ○: Tensile strength is 15 MPa or more. ×: Tensile strength is less than 15 MPa.

[0063] <Low-Speed ​​Tear Strength> The low-speed tear strength of the molded article was measured with reference to JIS L 1096 A-1 method (single tongue method). A rectangular test piece measuring 50 mm in length and 30 mm in width was cut from the resulting 0.1 mm-thick film, and a 25 mm-long incision was made perpendicular to the short side from the center of one of the short sides. The short sides separated by the incision were attached to a pair of jigs provided on a Tensilon universal testing machine (manufactured by Orientec), and then pulled at a tensile speed of 200 mm / min in an environment at a temperature of 23±2°C. The maximum load at the time the test piece was torn was measured, and this was taken as the low-speed tear strength (unit: N / mm) of the test piece. The low-speed tear strength of each test piece was evaluated based on the measured low-speed tear strength values ​​and the following evaluation criteria: (Evaluation Criteria for Low-Speed ​​Tear Strength) ○: Low-speed tear strength of 8 N / mm or more. ×: Low speed tear strength is less than 8 N / mm.

[0064] [Example 1] A polymerization vessel equipped with a stirrer and having an internal volume of 1.3 L was degassed, and then CF ３ CH ２ OCF ２ CF ２ 899 g of H (AE-3000: product name, manufactured by AGC), 271 g of water, CF ２ = CFO (CF ２ ) ３82.3 g of F(PPVE) and 21.7 g of methanol were charged into the polymerization vessel. Next, the temperature inside the polymerization vessel was raised to 50°C (polymerization temperature), 181 g of tetrafluoroethylene (TFE) was further charged, and the pressure inside the polymerization vessel was increased to 1.28 MPa (gauge pressure). 2 mL of a 0.06 mass% AE-3000 solution of heptafluorobutyroyl peroxide was charged as a polymerization initiator solution, polymerization was initiated, and the above polymerization initiator solution was subsequently continuously added. Furthermore, TFE was continuously charged so that the pressure during polymerization was maintained equal to the pressure at the start of polymerization. 300 minutes after the start of polymerization, 49 mL of the polymerization initiator solution was added, and at this point 160 g of TFE was charged, the temperature inside the polymerization vessel was lowered to 23°C, and the pressure inside the polymerization vessel was purged until it reached 1 atm.

[0065] The resulting copolymer slurry was filtered to separate the polymerization medium, and then dried at 150°C for 15 hours to obtain copolymer 1. From the results of melt NMR analysis and infrared absorption spectroscopy, the composition of copolymer 1 was TFE unit / PPVE unit = 98.45 / 1.55 ​​(mol%). Note that "PPVE unit" refers to the CF of each copolymer. ２ = CFO (CF ２ ) ３ It is a unit based on F.

[0066] A co-rotating twin-screw extruder kneader equipped with a screw having two kneading sections was prepared. Copolymer 1 was introduced into the feeder hopper of the twin-screw extruder kneader, and kneaded while being sucked through the vent with a vacuum pump under conditions of a cylinder temperature of 380°C and a screw rotation speed of 100 rpm. The strands discharged from the vent were slowly cooled and cut with a pelletizer to produce cylindrical untreated pellets 1 having a length of 5 mm or less and a length-to-diameter ratio (length / diameter) of 0.5 or more and less than 1.5.

[0067] Next, the untreated pellets 1 were subjected to a tray-type fluorination treatment in the following manner. The untreated pellets 1 were placed in a dedicated tray and placed in a box-type reaction oven, which was then sealed and evacuated. ２ The gas concentration was adjusted to 20% by volume.２ F diluted with gas ２ / N ２ The mixed gas was introduced and the oven was filled with the mixed gas. The pressure in the oven was maintained at atmospheric pressure (1 atm) and the temperature at 230°C. One hour after the start of the mixed gas introduction, the oven was evacuated, and the mixed gas was introduced again to fill the oven with the mixed gas. Thereafter, the reaction was carried out at 230°C for 4 hours. After the reaction was completed, heating was stopped and the F in the oven was ２ / N ２ Mixed gas is N ２ The atmosphere was replaced with gas, and pellet 1 of copolymer F1 was taken out of the oven and subjected to infrared absorption spectroscopy by the method described above to determine the number of specific functional groups such as -COF in copolymer F1. Furthermore, copolymer F1 had a melting point of 306°C and an MFR of 13 g / 10 min. The composition of each copolymer F after fluorination treatment was the same as that of each copolymer before fluorination treatment.

[0068] [Example 2] Copolymer 2 of Example 2 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 134.6 g and 15.3 g, respectively, and the total amount of polymerization initiator solution continuously charged was changed to 38 mL. The polymerization time was 470 minutes. The composition of copolymer 2 was TFE unit / PPVE unit = 97.70 / 2.30 (mol%). Subsequently, untreated pellets 2 of copolymer 2 were prepared in the same manner as in Example 1, and the untreated pellets 2 were subjected to a fluorination treatment to prepare pellets 2 of copolymer F2. The MFR of copolymer F2 was 11 g / 10 min, and the melting point was 301 ° C.

[0069] [Example 3] Copolymer 3 of Example 3 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 79.0 g, the amount of methanol was changed to 23.8 g, and the total amount of polymerization initiator solution continuously charged was changed to 47 mL. The polymerization time was 345 minutes. The composition of copolymer 3 was TFE unit / PPVE unit = 98.50 / 1.50 (mol%). Subsequently, untreated pellets 3 of copolymer 3 were prepared in the same manner as in Example 1, and the untreated pellets 3 were subjected to a fluorination treatment to prepare pellets 3 of copolymer F3. The MFR of copolymer F3 was 17 g / 10 min, and the melting point was 306 ° C.

[0070] [Example 4] Copolymer 4 of Example 4 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 99.1 g, the amount of methanol was changed to 21.9 g, and the total amount of polymerization initiator solution continuously charged was changed to 45 mL. The polymerization time was 420 minutes. The composition of copolymer 4 was TFE unit / PPVE unit = 98.20 / 1.80 (mol%). Subsequently, untreated pellets 4 of copolymer 4 were prepared in the same manner as in Example 1, and the untreated pellets 4 were fluorinated in the same manner as in Example 1 to prepare pellets 4 of copolymer F4. The MFR of copolymer F4 was 18 g / 10 min, and the melting point was 304 ° C.

[0071] [Example 5] Copolymer 5 of Example 5 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 47.2 g and 27.2 g, respectively, and the total amount of the polymerization initiator solution continuously charged was changed to 46 mL. The polymerization time was 400 minutes. The composition of copolymer 5 was TFE unit / PPVE unit = 99.00 / 1.00 (mol%). Subsequently, untreated pellets 5 of copolymer 5 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 5 of copolymer F5 were prepared by fluorination treatment of untreated pellets 5 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 3.0 hours. The MFR of copolymer F5 was 16 g / 10 min and the melting point was 309°C.

[0072] [Example 6] Copolymer 6 of Example 6 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 79.0 g, the amount of methanol was changed to 25.1 g, and the amount of polymerization initiator solution continuously charged was changed to 45 mL. The polymerization time was 380 minutes. The composition of copolymer 6 was TFE unit / PPVE unit = 98.50 / 1.50 (mol%). Subsequently, untreated pellets 6 of copolymer 6 were prepared in the same manner as in Example 1, and the untreated pellets 6 were subjected to a fluorination treatment to prepare pellets 6 of copolymer F6. The MFR of copolymer F6 was 21 g / 10 min, and the melting point was 306 ° C.

[0073] [Example 7] Copolymer 7 of Example 7 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 127.3 g and 17.9 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 55 mL. The polymerization time was 360 minutes. The composition of copolymer 7 was TFE unit / PPVE unit = 97.80 / 2.20 (mol%). Subsequently, untreated pellets 7 of copolymer 7 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 7 of copolymer F7 were prepared by fluorination treatment of untreated pellets 7 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 8.0 hours. The MFR of copolymer F7 was 15 g / 10 min and the melting point was 302°C.

[0074] [Example 8] Copolymer 8 of Example 8 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 120.1 g, the amount of methanol was changed to 20.3 g, and the amount of polymerization initiator solution continuously charged was changed to 78 mL. The polymerization time was 270 minutes. The composition of copolymer 8 was TFE unit / PPVE unit = 97.90 / 2.10 (mol%). Subsequently, untreated pellets 8 of copolymer 8 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Untreated pellets 8 were subjected to a fluorination treatment in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 7.0 hours, to prepare pellets 8 of copolymer F8. The MFR of copolymer F8 was 20 g / 10 min and the melting point was 302°C.

[0075] [Example 9] Copolymer 9 of Example 9 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 59.7 g, the amount of methanol was changed to 28 g, and the amount of polymerization initiator solution continuously charged was changed to 42 mL. The polymerization time was 455 minutes. The composition of copolymer 9 was TFE unit / PPVE unit = 98.80 / 1.20 (mol%). Subsequently, untreated pellets 9 of copolymer 9 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 9 of copolymer F9 were prepared by fluorination treatment of untreated pellets 9 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 3.0 hours. The MFR of copolymer F9 was 23 g / 10 min and the melting point was 308°C.

[0076] [Example 10] Copolymer 10 of Example 10 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 97.8 g and 23.8 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 40 mL. The polymerization time was 400 minutes. The composition of copolymer 10 was TFE unit / PPVE unit = 98.22 / 1.78 (mol%). Subsequently, F ２ / N ２ Untreated pellets 10 of copolymer 10 were prepared in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 7.0 hours, and the untreated pellets 10 were subjected to a fluorination treatment to prepare pellets 10 of copolymer F10. The MFR of copolymer F10 was 24 g / 10 min and the melting point was 304°C.

[0077] [Example 11] The copolymer 11 of Example 11 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 130.9 g, the amount of methanol was changed to 19.6 g, and the amount of polymerization initiator solution continuously charged was changed to 57 mL. The polymerization time was 390 minutes. The composition of copolymer 11 was TFE unit / PPVE unit = 97.75 / 2.25 (mol%). Subsequently, untreated pellets 11 of copolymer 11 were prepared in the same manner as in Example 1, and the untreated pellets 11 were subjected to a fluorination treatment in the same manner as in Example 1 to prepare pellets 11 of copolymer F11. The MFR of copolymer F11 was 21 g / 10 min, and the melting point was 301 ° C.

[0078] [Example 12] Copolymer 12 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 134.6 g, the amount of methanol was changed to 20.0 g, and the amount of polymerization initiator solution continuously charged was changed to 88 mL. The polymerization time was 265 minutes. The composition of copolymer 12 was TFE unit / PPVE unit = 97.70 / 2.30 (mol%). Subsequently, untreated pellets 12 of copolymer 12 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Except for changing the reaction time after the introduction of the mixed gas to 8.0 hours, untreated pellets 12 were fluorinated to prepare pellets 12 of copolymer F12 in the same manner as in Example 1. The MFR of copolymer F12 was 24 g / 10 min and the melting point was 301°C.

[0079] [Example 13] Copolymer 13 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 113.0 g, the amount of methanol to 22.7 g, and the amount of polymerization initiator solution continuously charged was changed to 47 mL. The polymerization time was 475 minutes. The composition of copolymer 13 was TFE unit / PPVE unit = 98.00 / 2.00 (mol%). Subsequently, untreated pellets 13 of copolymer 13 were prepared in the same manner as in Example 1, and again F ２ / N ２Pellets 13 of copolymer F13 were prepared by fluorination treatment of untreated pellets 13 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 5.0 hours. The MFR of copolymer F13 was 26 g / 10 min and the melting point was 303°C.

[0080] [Example 14] Copolymer 14 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 127.3 g, the amount of methanol was changed to 22.1 g, and the amount of polymerization initiator solution continuously charged was changed to 57 mL. The polymerization time was 430 minutes. The composition of copolymer 14 was TFE unit / PPVE unit = 97.80 / 2.20 (mol%). Subsequently, untreated pellets 14 of copolymer 14 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 14 of copolymer F14 were prepared by fluorination treatment of untreated pellets 14 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 7.0 hours. The MFR of copolymer F14 was 30 g / 10 min and the melting point was 302°C.

[0081] [Example 15] Copolymer 15 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 116.6 g, the amount of methanol was changed to 24.2 g, and the amount of polymerization initiator solution continuously charged was changed to 65 mL. The polymerization time was 375 minutes. The composition of copolymer 15 was TFE unit / PPVE unit = 97.95 / 2.05 (mol%). Subsequently, F ２ / N ２ Untreated pellets 15 of copolymer 15 were prepared in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 6.0 hours, and the untreated pellets 15 were subjected to a fluorination treatment to prepare pellets 15 of copolymer F15. The MFR of copolymer F15 was 35 g / 10 min and the melting point was 303°C.

[0082] [Example 16] Copolymer 16 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 130.9 g, the amount of methanol was changed to 23.4 g, and the amount of polymerization initiator solution continuously charged was changed to 64 mL. The polymerization time was 410 minutes. The composition of copolymer 16 was TFE unit / PPVE unit = 97.75 / 2.25 (mol%). Subsequently, untreated pellets 16 of copolymer 16 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 16 of copolymer F16 were prepared by fluorination treatment of untreated pellets 16 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 8.0 hours. The MFR of copolymer F16 was 39 g / 10 min and the melting point was 301°C.

[0083] [Example 17] Copolymer 17 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 142.0 g, the amount of methanol was changed to 23.1 g, and the amount of polymerization initiator solution continuously charged was changed to 62 mL. The polymerization time was 460 minutes. The composition of copolymer 17 was TFE unit / PPVE unit = 97.60 / 2.40 (mol%). Subsequently, untreated pellets 17 of copolymer 17 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 17 of copolymer F17 were prepared by fluorination treatment of untreated pellets 17 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 5.0 hours. The MFR of copolymer F17 was 45 g / 10 min and the melting point was 300° C.

[0084] [Example 18] Copolymer 18 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 93.7 g, the amount of methanol to 26.1 g, and the amount of polymerization initiator solution continuously charged was changed to 50 mL. The polymerization time was 350 minutes. The composition of copolymer 18 was TFE unit / PPVE unit = 98.28 / 1.72 (mol%). Subsequently, untreated pellets 18 of copolymer 18 were prepared in the same manner as in Example 1, and the untreated pellets 18 were subjected to a fluorination treatment to prepare pellets 18 of copolymer F18. The MFR of copolymer F18 was 32 g / 10 min, and the melting point was 305 ° C.

[0085] [Example 19] Copolymer 19 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 82.3 g, the amount of methanol was changed to 28.3 g, and the amount of polymerization initiator solution continuously charged was changed to 42 mL. The polymerization time was 460 minutes. The composition of copolymer 19 was TFE unit / PPVE unit = 98.45 / 1.55 ​​(mol%). Subsequently, untreated pellets 19 of copolymer 19 were prepared in the same manner as in Example 1, and the untreated pellets 19 were subjected to a fluorination treatment to prepare pellets 19 of copolymer F19. The MFR of copolymer F19 was 37 g / 10 min, and the melting point was 306 ° C.

[0086] [Example 20] Copolymer 20 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 113.0 g, the amount of methanol to 26.0 g, and the amount of polymerization initiator solution continuously charged was changed to 62 mL. The polymerization time was 410 minutes. The composition of copolymer 20 was TFE unit / PPVE unit = 98.00 / 2.00 (mol%). Subsequently, untreated pellets 20 of copolymer 20 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 20 of copolymer F20 were prepared by fluorination treatment of untreated pellets 20 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 6.0 hours. The MFR of copolymer F20 was 44 g / 10 min and the melting point was 303°C.

[0087] [Example 21] Copolymer 21 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 89.0 g, the amount of methanol was changed to 28.4 g, and the amount of polymerization initiator solution continuously charged was changed to 52 mL. The polymerization time was 370 minutes. The composition of copolymer 21 was TFE unit / PPVE unit = 98.35 / 1.65 (mol%). Subsequently, untreated pellets 21 of copolymer 21 were prepared in the same manner as in Example 1, and again F ２ / N ２ Except for changing the reaction time after the introduction of the mixed gas to 3.0 hours, untreated pellets 21 were fluorinated to prepare pellets 21 of copolymer F21 in the same manner as in Example 1. The MFR of copolymer F21 was 42 g / 10 min and the melting point was 305° C.

[0088] [Example 22] Copolymer 22 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 72.5 g, the amount of methanol to 19.8 g, and the amount of polymerization initiator solution continuously charged was changed to 35 mL. The polymerization time was 385 minutes. The composition of copolymer 22 was TFE unit / PPVE unit = 98.60 / 1.40 (mol%). Subsequently, untreated pellets 22 of copolymer 22 were prepared in the same manner as in Example 1, and the untreated pellets 22 were subjected to a fluorination treatment to prepare pellets 22 of copolymer F22. The MFR of copolymer F22 was 8 g / 10 min and the melting point was 307 ° C.

[0089] [Example 23] Copolymer 23 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 75.7 g, the amount of methanol to 27.3 g, and the amount of polymerization initiator solution continuously charged was changed to 50 mL. The polymerization time was 370 minutes. The composition of copolymer 23 was TFE unit / PPVE unit = 98.55 / 1.45 (mol%). Subsequently, untreated pellets 23 of copolymer 23 were prepared in the same manner as in Example 1, and the untreated pellets 23 were subjected to a fluorination treatment to prepare pellets 23 of copolymer F23. The MFR of copolymer F23 was 28 g / 10 min, and the melting point was 306 ° C.

[0090] [Example 24] Copolymer 24 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 41.1 g, the amount of methanol to 33.1 g, and the amount of polymerization initiator solution continuously charged was changed to 53 mL. The polymerization time was 420 minutes. The composition of copolymer 24 was TFE unit / PPVE unit = 99.10 / 0.90 (mol%). Subsequently, untreated pellets 24 of copolymer 24 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 24 of copolymer F24 were prepared by fluorination treatment of untreated pellets 24 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 5.0 hours. The MFR of copolymer F24 was 35 g / 10 min and the melting point was 310°C.

[0091] [Example 25] Copolymer 25 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 35.0 g, the amount of methanol to 32.0 g, and the amount of polymerization initiator solution continuously charged was changed to 62 mL. The polymerization time was 350 minutes. The composition of copolymer 25 was TFE unit / PPVE unit = 99.20 / 0.80 (mol%). Subsequently, untreated pellets 25 of copolymer 25 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 25 of copolymer F25 were prepared by fluorination treatment of untreated pellets 25 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 5.0 hours. The MFR of copolymer F25 was 27 g / 10 min and the melting point was 311° C.

[0092] [Example 26] Copolymer 26 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 53.4 g, the amount of methanol to 33.3 g, and the amount of polymerization initiator solution continuously charged was changed to 54 mL. The polymerization time was 415 minutes. The composition of copolymer 26 was TFE unit / PPVE unit = 98.90 / 1.10 (mol%). Subsequently, untreated pellets 26 of copolymer 26 were prepared in the same manner as in Example 1, and the untreated pellets 26 were subjected to a fluorination treatment to prepare pellets 26 of copolymer F26. The MFR of copolymer F26 was 46 g / 10 min, and the melting point was 309 ° C.

[0093] [Example 27] Copolymer 27 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 59.7 g, the amount of methanol to 31.9 g, and the amount of polymerization initiator solution continuously charged was changed to 60 mL. The polymerization time was 360 minutes. The composition of copolymer 27 was TFE unit / PPVE unit = 98.80 / 1.20 (mol%). Subsequently, untreated pellets 27 of copolymer 27 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 27 of copolymer F27 were prepared by fluorination treatment of untreated pellets 27 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 6.0 hours. The MFR of copolymer F27 was 42 g / 10 min and the melting point was 308°C.

[0094] [Example 28] Copolymer 28 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 75.7 g, the amount of methanol to 16.6 g, and the amount of polymerization initiator solution continuously charged was changed to 26 mL. The polymerization time was 420 minutes. The composition of copolymer 28 was TFE unit / PPVE unit = 98.55 / 1.45 (mol%). Subsequently, untreated pellets 28 of copolymer 28 were prepared in the same manner as in Example 1, and again F ２ / N ２Pellets 28 of copolymer F28 were prepared by fluorination treatment of untreated pellets 28 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 7.0 hours. The MFR of copolymer F28 was 5 g / 10 min and the melting point was 306° C.

[0095] [Example 29] Copolymer 29 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 83.6 g and 19.3 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 30 mL. The polymerization time was 470 minutes. The composition of copolymer 29 was TFE unit / PPVE unit = 98.43 / 1.57 (mol%). Subsequently, untreated pellets 29 of copolymer 29 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 29 of copolymer F29 were prepared by fluorination treatment of untreated pellets 29 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 7.0 hours. The MFR of copolymer F29 was 9 g / 10 min and the melting point was 306° C.

[0096] [Example 30] Copolymer 30 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 127.3 g, the amount of methanol to 8.5 g, and the amount of polymerization initiator solution continuously charged was changed to 21 mL. The polymerization time was 440 minutes. The composition of copolymer 30 was TFE unit / PPVE unit = 97.80 / 2.20 (mol%). Subsequently, untreated pellets 30 of copolymer 30 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 30 of copolymer F30 were prepared by fluorination treatment of untreated pellets 30 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 3.0 hours. The MFR of copolymer F30 was 3 g / 10 min and the melting point was 302°C.

[0097] [Example 31] Copolymer 31 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 82.3 g and 10.6 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 54 mL. The polymerization time was 310 minutes. The composition of copolymer 31 was TFE unit / PPVE unit = 98.45 / 1.55 ​​(mol%). Subsequently, untreated pellets 31 of copolymer 31 were prepared in the same manner as in Example 1, and again F ２ / N ２ Except for changing the reaction time after the introduction of the mixed gas to 7.0 hours, untreated pellets 31 were fluorinated to prepare pellets 31 of copolymer F31 in the same manner as in Example 1. The MFR of copolymer F31 was 2 g / 10 min and the melting point was 306°C.

[0098] [Example 32] Copolymer 32 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 35.0 g, the amount of methanol to 11.8 g, and the amount of polymerization initiator solution continuously charged was changed to 19 mL. The polymerization time was 420 minutes. The composition of copolymer 32 was TFE unit / PPVE unit = 99.20 / 0.80 (mol%). Subsequently, untreated pellets 32 of copolymer 32 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 32 of copolymer F32 were prepared by fluorination treatment of untreated pellets 32 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 3.0 hours. The MFR of copolymer F32 was 1 g / 10 min and the melting point was 311°C.

[0099] [Example 33] Copolymer 33 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 89.0 g, the amount of methanol to 12.2 g, and the amount of polymerization initiator solution continuously charged was changed to 21 mL. The polymerization time was 392 minutes. The composition of copolymer 33 was TFE unit / PPVE unit = 98.35 / 1.65 (mol%). Subsequently, untreated pellets 33 of copolymer 33 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２Pellets 33 of copolymer F33 were prepared by fluorination treatment of untreated pellets 33 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 2.0 hours. The MFR of copolymer F33 was 3 g / 10 min and the melting point was 305° C.

[0100] [Example 34] Copolymer 34 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 53.4 g, the amount of methanol to 33.3 g, and the amount of polymerization initiator solution continuously charged was changed to 27 mL. The polymerization time was 350 minutes. The composition of copolymer 34 was TFE unit / PPVE unit = 98.90 / 1.10 (mol%). Subsequently, untreated pellets 34 of copolymer 34 were prepared in the same manner as in Example 1, and F was again used. ２ / N ２ Pellets 34 of copolymer F34 were prepared by fluorination treatment of untreated pellets 34 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 10.0 hours. The MFR of copolymer F34 was 46 g / 10 min and the melting point was 309°C.

[0101] [Example 35] Copolymer 35 was obtained in the same manner as in Example 1, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 172.7 g and 17.7 g, respectively, and the amount of polymerization initiator solution continuously charged was changed to 29 mL. The polymerization time was 415 minutes. The composition of copolymer 35 was TFE unit / PPVE unit = 97.20 / 2.80 (mol%). Subsequently, untreated pellets 35 of copolymer 35 were prepared in the same manner as in Example 1, and again F ２ / N ２ Pellets 35 of copolymer F35 were prepared by fluorination treatment of untreated pellets 35 in the same manner as in Example 1, except that the reaction time after the introduction of the mixed gas was changed to 3.0 hours. The MFR of copolymer F35 was 30 g / 10 min and the melting point was 298°C.

[0102] [Example 36] Copolymer 36 was obtained in the same manner as in Example 1, except that the amount of PPVE initially charged into the polymerization vessel was changed to 8.8 g, the amount of methanol to 35.5 g, and the amount of polymerization initiator solution continuously charged was changed to 50 mL. The polymerization time was 480 minutes. The composition of copolymer 36 was TFE unit / PPVE unit = 99.65 / 0.35 (mol%). Subsequently, untreated pellets 36 of copolymer 36 were prepared in the same manner as in Example 1, and the untreated pellets 36 were subjected to a fluorination treatment to prepare pellets 36 of copolymer F36. The MFR of copolymer F36 was 26 g / 10 min, and the melting point was 314 ° C.

[0103] Table 2 shows the composition of copolymer F in each example, as well as the measurement and evaluation results of copolymer F. In the table, the column "PPVE units (mol %)" indicates the content (unit: mol %) of PPVE units relative to all units contained in copolymer F. The column "TFE units (mol %)" indicates the content (unit: mol %) of TFE units relative to all units contained in copolymer F. The column "MFR (g / 10g)" indicates the MFR (unit: g / 10g) of copolymer F. The column "-COF number" indicates the number of carbon atoms in copolymer F in each example. ６ The column "Number of specific functional groups" indicates the number of -COF per unit of the copolymer F having 10 carbon atoms. ６ The number of specific functional groups per unit is indicated.

[0104]

[0105]

[0106]

[0107]

[0108] As shown in Table 2, a copolymer containing TFE units and PAVE units, in which the content of PAVE units is 0.5 to 2.5 mol % based on the total units contained in the copolymer, the content of TFE units is 97.5 to 99.5 mol % based on the total units contained in the copolymer, and the number of -COFs in the copolymer is 10 or more and the number of carbon atoms in the copolymer is 10 or more. ６It was confirmed that by using a copolymer having more than 40 and not more than 200 groups per unit, it is possible to form a molded product excellent in heat resistance, crack resistance after crosslinking, tensile strength, and low-speed tear strength (Examples 1 to 32).

[0109] The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2023-141040, filed on August 31, 2023, are incorporated herein by reference as part of the disclosure of the present invention.

Claims

1. A copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), wherein the content of the units based on perfluoro(alkyl vinyl ether) is 0.5 to 2.5 mol % based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 97.5 to 99.5 mol % based on all units contained in the copolymer, and the number of -COFs in the copolymer is 10 to 100 mol % based on the total number of carbon atoms in the copolymer. ６ A copolymer, characterized in that the number of molecules per molecule is more than 40 and not more than 200.

2. The copolymer of claim 1, wherein said perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether).

3. The copolymer according to claim 1, having a melting point of 298°C or higher and 310.5°C or lower.

4. The copolymer according to claim 1, wherein the content of units based on perfluoro(alkyl vinyl ether) is 0.80 to 2.40 mol % based on all units contained in the copolymer.

5. A composition comprising the copolymer of claim 1.

6. An extrusion molded product obtained by extruding the copolymer according to any one of claims 1 to 4 or the composition according to claim 5.

7. A blow molded article obtained by blow molding the copolymer according to any one of claims 1 to 4 or the composition according to claim 5.

8. A transfer molded article, which is obtained by transfer molding the copolymer according to any one of claims 1 to 4 or the composition according to claim 5.

9. A covered electric wire comprising a conductor and a covering layer disposed on the surface of the conductor and obtained by molding the copolymer according to any one of claims 1 to 4 or the composition according to claim 5.

10. A molded article obtained by molding the copolymer according to any one of claims 1 to 4 or the composition according to claim 5, characterized in that the molded article is a piping member, an electric wire covering material, a tube, a film or a compressed member.

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