Copolymer, composition, and molded article

Abstract

Provided are: a copolymer capable of forming a molded body having low nitrogen permeability and yellowness and excellent surface properties; a composition; and a molded body.　The copolymer of the present invention contains TFE units, ethylene units, and either or both units based on a compound represented by formula (1) CZ2=CX(CF2)mY and a compound represented by formula (2) CF2=CF-O-(CF2)nF, wherein the total content of TFE units and ethylene units is 80.0-99.7 mol% relative to all units contained in the copolymer, the content of TFE units is 49.0 mol% to less than 56.0 mol% relative to the total content of TFE units and ethylene units, the content of units based on compounds represented by formula (1) or formula (2) is 0.3-1.3 mol%, and the melt flow rate is 33-50 g / 10 minutes.

Description

Copolymer, composition and molded article

[0001] The present invention relates to a copolymer, a composition, and a molded article.

[0002] Ethylene / tetrafluoroethylene copolymer (hereinafter also referred to as "ETFE") is excellent in heat resistance, weather resistance, electrical insulation, non-stickiness, water and oil repellency, etc., and is characterized by high moldability and mechanical strength among fluororesins. Therefore, a variety of molded articles such as electric wire coverings, tubes, sheets, films, filaments, pump casings, joints, packings, linings, coatings, etc. are produced by melt molding methods such as extrusion molding, blow molding, injection molding, and rotational molding. For example, Patent Document 1 discloses an ethylene / tetrafluoroethylene copolymer containing a copolymer having polymerization units based on tetrafluoroethylene, polymerization units based on ethylene, and polymerization units based on (perfluorobutyl)ethylene.

[0003] Patent No. 5663839

[0004] When ETFE is used as the constituent material of molded body, it is required to have excellent properties in various aspects, and specifically, the molded body etc. that nitrogen permeability and yellowness are low and that surface property is also excellent is required.The present inventors have evaluated the molded body that is formed by using the ETFE described in Patent Document 1, and have found that there is room for improvement at least in terms of nitrogen permeability.

[0005] Therefore, an object of the present invention is to provide a copolymer that can be used to form a molded article having low nitrogen permeability and low yellowness index and excellent surface properties. Another object of the present invention is to provide a composition containing the copolymer and a molded article obtained by molding the copolymer.

[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, units based on ethylene, and units based on a compound represented by formula (1) or a compound represented by formula (2) described below, in which the contents of each unit are within predetermined ranges and the copolymer has a melt flow rate of 33 to 50 g / 10 min, it is possible to form a molded article that has low nitrogen permeability and low yellowness and also excellent surface properties, and have arrived at the present invention.

[0007] That is, the inventors have found that the above-mentioned problems can be solved by the following configuration: [1] A copolymer containing units based on tetrafluoroethylene, units based on ethylene, and either or both of units based on a compound represented by formula (1) and units based on a compound represented by formula (2), wherein the total content of the units based on tetrafluoroethylene and the units based on ethylene is 80.0 to 99.7 mol % based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 49.0 mol % or more and less than 56.0 mol % based on the total content of the units based on tetrafluoroethylene and the units based on ethylene, the content of the units based on the compound represented by formula (1) or the compound represented by formula (2) is 0.3 to 1.3 mol % based on all units contained in the copolymer, and the melt flow rate measured in accordance with ASTM D3159 under conditions of a temperature of 297°C and a load of 49 N is 33 to 50 g / 10 min. CZ ２ =CX(CF ２ ) ｍ Y Formula (1) CF ２ =CF-O-(CF ２ ) ｎF Formula (2) In formula (1), X, Y, and Z each independently represent a hydrogen atom or a fluorine atom, and m represents an integer of 2 to 6. In formula (2), n represents an integer of 1 to 6. [2] A copolymer according to [1], comprising units based on the tetrafluoroethylene, units based on the ethylene, and units based on the compound represented by formula (1), wherein the content of the units based on the compound represented by formula (1) is 0.3 to 1.3 mol% based on all units contained in the copolymer. [3] A composition comprising the copolymer according to [1] or [2]. [4] A molded article obtained by molding the copolymer according to [1] or [2]. [5] A solid composition comprising the copolymer according to [1] or [2], having a water content of 0.02 to 0.8 mass%. [6] A molded article obtained by molding the copolymer according to [1] or [2]. [7] A molded article obtained by molding the composition according to [3]. [8] A molded article obtained by molding the solid composition according to [4].

[0008] According to the present invention, there is provided a copolymer capable of forming a molded article having low nitrogen permeability and low yellowness index and excellent surface properties. Furthermore, according to the present invention, there are provided a composition containing the copolymer and a molded article obtained by molding the copolymer.

[0009] The meanings of terms used in the present invention 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] "Unit" is a general term for 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. Note that, in the following, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit". "TFE unit" is a unit based on tetrafluoroethylene in the copolymer, and "E unit" is a unit based on ethylene in the copolymer. Furthermore, "A unit" is a unit based on a compound represented by formula (1) or formula (2) described below.

[0011] The copolymer of the present invention (hereinafter also referred to as "the copolymer") contains E units, TFE units, and A units within respective predetermined ranges. The copolymer has a melt flow rate of 33 to 50 g / 10 min measured at a temperature of 297°C and a load of 49 N in accordance with ASTM D3159.

[0012] This copolymer can form molded articles with low nitrogen permeability and low yellowness, and excellent surface properties. While the details of the reasons for this are not yet clear, it is believed to be due to the use of a copolymer in which the content of A units, which are either or both of units based on a compound represented by formula (1) and units based on a compound represented by formula (2), described below, is 0.3 to 1.3 mol% relative to the total units contained in the copolymer, and the copolymer has a melt flow rate of 33 to 50 g / 10 min. That is, by having the content of A units be 0.3 mol% or more relative to the total units contained in the copolymer, it is presumed that excessive viscosity increase during molding (particularly during injection molding) is suppressed, and the copolymer is more likely to conform to the mold, resulting in molded articles with excellent surface properties. Here, a molded article with excellent surface properties refers to a molded article with excellent surface smoothness and reduced occurrence of flow marks (flow marks of the copolymer). Furthermore, it is presumed that the content of A units being 1.3 mol% or less relative to the total units contained in the copolymer reduces the free volume of the polymer chains of the copolymer, thereby suppressing nitrogen permeation of the resulting molded article. It is also presumed that the melt flow rate being 33 g / 10 min or more reduces the molecular chains, thereby lowering the refractive index, thereby reducing the yellowness of the resulting molded article. It is also presumed that the melt flow rate being 50 g / 10 min or less suppresses the incorporation of bubbles into the copolymer during molding (especially during injection molding), resulting in a molded article with excellent surface properties.

[0013] The copolymer contains TFE units based on tetrafluoroethylene, E units based on ethylene, and A units based on a compound represented by formula (1) or a compound represented by formula (2).

[0014] CZ ２ =CX(CF ２ ) ｍ Y Formula (1) CF ２ =CF-O-(CF ２ ) ｎ F Formula (2) In formula (1), X, Y, and Z each independently represent a hydrogen atom or a fluorine atom, and m represents an integer of 2 to 6. In formula (2), n represents an integer of 1 to 6.

[0015] In the compound represented by formula (1), X and Z are preferably hydrogen atoms from the viewpoint of polymerizability. Y is preferably a fluorine atom from the viewpoint of heat resistance. m is preferably an integer of 2 to 6, and more preferably 4.

[0016] The compound represented by formula (1) includes CH ２ =CH(CF ２ ) ２ F, CH ２ =CH(CF ２ ) ４ F, CH ２ =CH(CF ２ ) ６ F, CH ２ =CF(CF ２ ) ４ F or CH ２ =CF(CF ２ ) ３ H is preferred, CH ２ =CH(CF ２ ) ４ F (hereinafter also referred to as "PFBE") is more preferred.

[0017] Specific examples of the compound represented by formula (2) include CF ２ =CF-O-(CF ２ ) F, CF ２ =CF-O-(CF ２ ) ２ F, CF ２ =CF-O-(CF ２ ) ３F, CF ２ =CF-O-(CF ２ ) ４ F, CF ２ =CF-O-(CF ２ ) ５ F and CF ２ =CF-O-(CF ２ ) ６ Among them, CF corresponding to the compound where n is 3 ２ =CF-O-(CF ２ ) ３ F is preferred.

[0018] The present copolymer may contain, as A units, either units based on a compound represented by formula (1) (hereinafter also referred to as "A1 units") or units based on a compound represented by formula (2) (hereinafter also referred to as "A2 units"), or may contain both A1 units and A2 units. In other words, when the present copolymer contains both A1 units and A2 units, the "content of A units" means the sum of the content of A1 units and the content of A2 units.

[0019] The content of A units is 0.3 to 1.3 mol% based on all units contained in the copolymer. When the content of A units is 0.3 mol% or more based on all units contained in the copolymer, a molded article with excellent surface properties can be formed. Furthermore, when the content of A units is 1.3 mol% or less based on all units contained in the copolymer, a molded article with suppressed nitrogen permeation and suppressed oxygen permeation can be formed. The content of A units is preferably 0.5 to 1.3 mol% based on all units contained in the copolymer, in order to achieve a good balance between suppression of nitrogen permeation and surface properties.

[0020] The present copolymer is preferably a copolymer containing TFE units, E units, and A1 units, or a copolymer containing TFE units, E units, and A2 units, and from the viewpoint of excellent long-term folding endurance, a copolymer having E units, TFE units, and A1 units is more preferred.When the present copolymer is a copolymer containing TFE units, E units, and A1 units, the content of A1 units is 0.3 to 1.3 mol% based on the total units contained in the present copolymer, and from the above viewpoint, 0.5 to 1.3 mol% is preferred.When the present copolymer is a copolymer containing TFE units, E units, and A2 units, the content of A2 units is 0.3 to 1.3 mol% based on the total units contained in the present copolymer, and from the above viewpoint, 0.6 to 1.3 mol% is preferred.

[0021] In this copolymer, the total content of TFE units and E units is 80.0 to 99.7 mol% based on all units contained in this copolymer. From the viewpoint of excellent long-term heat resistance, the total content of TFE units and E units is preferably 85.0 mol% or more, more preferably 88.0 mol% or more. Furthermore, from the viewpoint of excellent durability against repeated load, the total content of TFE units and E units is preferably 99.5 mol% or less.

[0022] In the copolymer, the content of TFE units is 49.0 mol % or more and less than 56.0 mol % based on the total content of TFE units and E units. From the viewpoint of excellent heat resistance, the content of TFE units is preferably 50.0 to 56.0 mol %, more preferably 52.0 to 56.0 mol %, based on the total content of TFE units and E units.

[0023] The content of TFE units is preferably 40.0 to 54.9 mol%, more preferably 45.0 to 54.5 mol%, and particularly preferably 50.0 to 54.5 mol%, based on the total units contained in the copolymer. If the content is equal to or greater than the lower limit, the heat resistance of the molded article will be superior, and if the content is equal to or less than the upper limit, the mechanical properties of the molded article will be superior.

[0024] The content of E units is preferably 36.0 to 50.0 mol%, more preferably 40.0 to 48.0 mol%, and particularly preferably 42.0 to 47.0 mol%, based on the total units contained in the copolymer. If the content is equal to or greater than the lower limit, the mechanical properties of the molded article will be superior, and if it is equal to or less than the upper limit, the heat resistance of the molded article will be superior.

[0025] The copolymer may contain units based on a monomer other than tetrafluoroethylene, ethylene, the compound represented by formula (1), and the compound represented by formula (2). Specific examples of the other monomers include fluoroolefins (e.g., vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, hexafluoroisobutylene, etc., excluding the compounds represented by formula (1) and formula (2)), CF ２ =CFORf １ SO ２ X １ (However, Rf １ is a perfluoroalkylene group having 1 to 10 carbon atoms which may contain an oxygen atom between the carbon atoms, and X １ is a halogen atom or a hydroxyl group.), CF ２ =CFORf ２ CO ２ X ２ (However, Rf ２ is a perfluoroalkylene group having 1 to 10 carbon atoms which may contain an oxygen atom between the carbon atoms, and X ２ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, CF ２ =CF(CF ２ ) pOCF=CF ２(where p is 1 or 2), fluorine-containing monomers having a ring structure (for example, perfluoro(2,2-dimethyl-1,3-dioxole), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, perfluoro(2-methylene-4-methyl-1,3-dioxolane)), itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride. When the present copolymer contains units based on other monomers, the content of the units based on the other monomers is preferably 2.0 mol % or less, and more preferably 1.0 mol % or less, based on the total units contained in the present copolymer. As the present copolymer, an embodiment consisting of TFE units, E units, and A units is preferred, and an embodiment consisting of TFE units, E units, and A1 units is more preferred.

[0026] <Melt Flow Rate> The melt flow rate (hereinafter also referred to as "MFR") of the present copolymer is 33 to 50 g / 10 min. When the present copolymer has an MFR of 33 g / 10 min or more, a molded article with low yellowness can be formed. Furthermore, when the present copolymer has an MFR of 50 g / 10 min or less, a molded article with excellent surface properties can be formed. The MFR of the present copolymer is preferably 33 to 45 g / 10 min, in terms of achieving a good balance between yellowness and surface properties. 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 present copolymer means the mass of the present 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 297°C and a load of 49 N in accordance with ASTM D3159.

[0027] <Melting Point> The melting point of the present copolymer is preferably 245°C or higher, more preferably 248°C or higher, and particularly preferably 249°C or higher, from the viewpoint of superior crack resistance. The upper limit of the melting point of the present copolymer is preferably 290°C or lower, more preferably 280°C or lower, and particularly preferably 270°C or lower, from the viewpoint of superior moldability of the present copolymer. Specific examples of methods for adjusting the melting point of the present copolymer within the above range include a method of lowering the polymerization temperature during production of the present copolymer and a method of adjusting the content of A units in the present copolymer. The melting point of the present copolymer is the temperature corresponding to the endothermic peak when the present copolymer is heated at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter.

[0028] <Production Method> The present copolymer can be produced by a known method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. using the above-mentioned monomers (ethylene, tetrafluoroethylene, and one or both of the compound represented by formula (1) and the compound represented by formula (2)), and among these, production by 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.

[0029] 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 particularly preferably a radical polymerization initiator having a 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, particularly preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of the amount of the monomer used.

[0030] The polymerization medium may be a perfluorocarbon, a hydrofluorocarbon, a hydrofluoroether, or the like. Specific examples of the polymerization medium include those exemplified in International Publication No. 2013 / 015202. The polymerization medium may be used alone or in combination of two or more. The amount of the polymerization medium used is preferably 5 times or more, more preferably 7 times or more, by mass ratio relative to the amount of the monomer used. The amount is preferably 20 times or less, more preferably 17 times or less.

[0031] 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 ２ H 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 particularly preferred. Among alcohols, methanol or ethanol is particularly preferred. Among these, methanol is particularly preferred from the standpoint 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.

[0032] The polymerization temperature is preferably 15 to 60°C, more preferably 20 to 58°C, and particularly preferably 25 to 55°C. When the polymerization temperature is 15°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, and particularly preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0033] [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 low nitrogen permeability and low yellowness index and excellent surface properties 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 particularly preferably 90% by mass or more and less than 100% by mass, based on the total mass of the present composition.

[0034] [Solid Composition] The solid composition of the present invention (hereinafter also referred to as "the present solid composition") contains the present copolymer, and has a TOC (total organic carbon) elution amount relative to the surface area of ​​the present solid composition of 1,000 to 63,000 μg / cm ２ The TOC elution amount is preferably 50,000 or less, more preferably 30,000 or less, since this increases the adhesive strength after a hot water resistance test. The TOC elution amount is preferably 2,000 or more, more preferably 5,000 or more, since this increases the tensile strength after a heat aging test. Specific examples of methods for keeping the TOC elution amount of the solid composition within the above range include methods of adjusting the purity of the water used during granulation of the copolymer or the water content of the copolymer.

[0035] The present solid composition contains the present copolymer, and the water content relative to the mass of the present solid composition is preferably 0.02 to 0.8% by mass. Since the amount of TOC elution is reduced, the water content is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. Since the tensile strength after a heat aging test is increased, the water content is preferably 0.03% by mass or more, and more preferably 0.04% by mass or more. Specific examples of methods for adjusting the water content of the present solid composition within the above range include methods such as lengthening the time for which the present copolymer is kept at 100°C or higher during drying after granulation.

[0036] <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 particularly preferably 0.000001 to 50 parts by mass, per 100 parts by mass of the present copolymer in the present composition.

[0037] 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.

[0038] [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 low nitrogen permeability and yellowness index, and also has excellent surface properties. Specific molding methods include injection molding, extrusion molding, blow molding, press molding, rotational molding, and electrostatic coating. The molded article is preferably molded by press molding. Injection molding is also preferred because it can produce injection-molded articles with beautiful appearance without corroding the mold used for molding.

[0039] Specific examples of the molded article of the present invention include nuts, bolts, joints, films, bottles, gaskets, wire coatings, tubes, hoses, pipes, valves, sheets, seals, packing, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, pumps, wafer carriers, and wafer boxes.

[0040] 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, square rings, tubes, packings, valve core materials, hoses, and sealing materials used in automobile fuel systems and peripheral devices, and hoses and sealing materials used in automobile automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automobile engines and peripheral devices, as well as other automobile components, such as automobile brake hoses, air conditioner hoses, radiator hoses, and wire coating materials; chemical liquid transfer components for semiconductor manufacturing equipment, such as O-rings, square 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 electrical 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, 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.; carrier films for fuel cells.Among these, the molded article of the present invention is particularly suitable for use as a chemical liquid transport member or coating material for semiconductor devices, because it has low nitrogen permeability and yellowness, and also has excellent surface properties.

[0041] The present invention will be described in detail below with reference to examples. Examples 1 to 11 are working examples, and Examples 12 to 17 are comparative examples. However, the present invention is not limited to these examples. Various measurement methods and evaluation methods are as follows.

[0042] [Proportion of Each Unit] The content (mol %) of each unit in the copolymer is １９ The content of E units in the copolymer was calculated by F-NMR measurement. １ H-NMR measurement and １３ Calculated by C-NMR measurement.

[0043] [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 297°C and a load of 49 N in accordance with ASTM D3159, and this was taken as the MFR (g / 10 min).

[0044] [Melting Point] The melting point (°C) of the copolymer was determined from the endothermic peak observed when the copolymer was heated to 300°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).

[0045] <Film Forming> The copolymer obtained in each example was press-molded in the range of the melting point of the copolymer + 50°C ± 20°C (for example, 280°C to 320°C when the melting point of the copolymer is 250°C) to obtain a film having a thickness of 200 μm and a film having a thickness of 0.1 mm. The press-molding was carried out using a heated press ("SA-301" manufactured by Tester Sangyo Co., Ltd.). The obtained films were subjected to the following evaluation tests.

[0046] <Heat Resistance> A dumbbell-shaped test piece as defined in JIS K6301 No. 3 was cut out from the obtained 1 mm thick film. The test piece was measured for tensile elongation (unit: %) using a Strograph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) in accordance with the method of ASTM D-3159, with the distance between the gripping jigs set to 35 mm and pulled at a pulling rate of 200 mm / min under room temperature (temperature 23±2°C). The test piece was placed in a gear oven (forced circulation air heat aging tester) (manufactured by Toyo Seiki Seisaku-sho, Ltd.) and subjected to heat exposure treatment. The heat exposure treatment was performed at a temperature setting of 250°C, and heat treatment was performed for 24 hours after placement. The tensile elongation of the heat-treated test piece was measured in the same manner as above. The tensile elongation ratio after heat treatment was calculated based on the tensile elongation before heat treatment, which was taken as 100%, and the evaluation was performed according to the following criteria.

[0047] (Evaluation criteria for tensile elongation) ○: Tensile elongation after heat aging test is 50% or more △: Tensile elongation after heat aging test is 15% or more and less than 50% ×: Tensile elongation after heat aging test is less than 15%

[0048] <Yellowness Index> The YI (Yellow Index) value of a 200 μm thick film was measured using a color difference meter (ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.). The yellowness index of each film was evaluated based on the measured YI value according to the following evaluation criteria. A higher YI value indicates a higher yellowness index of the film. (Evaluation Criteria) ○: YI value less than 4.3. ×: YI value 4.3 or more.

[0049] <Oxygen Permeability> Using a film with a thickness of 0.1 mm, the oxygen permeability was measured in accordance with JIS K7126-1:2006 using a differential pressure gas permeability meter (L100-5000 gas permeability meter, manufactured by Systech Illinois). Permeation area: 50.24 cm ２ The oxygen permeability was measured at a test temperature of 70°C and a test humidity of 0% RH. The oxygen permeability coefficient was calculated from the obtained oxygen permeability and the film thickness using the following formula. The larger the oxygen permeability coefficient value, the higher the oxygen permeability. Oxygen permeability coefficient (cm ３ mm / (m ２24h atm)) = GTR x d GTR: oxygen permeability (cm ３ / (m ２ 24h atm)) d: Film thickness (mm) (Evaluation criteria) ○: Oxygen permeability coefficient is 2.6 or less. ×: Oxygen permeability coefficient is more than 2.6.

[0050] <Nitrogen Permeability> Nitrogen permeability was measured using a 0.1 mm thick film in accordance with JIS K7126-1:2006 using a differential pressure gas permeability meter (L100-5000 gas permeability meter, manufactured by Systech Illinois). Permeation area: 50.24 cm ２ The nitrogen permeability was measured at a test temperature of 70°C and a test humidity of 0% RH. The nitrogen permeability coefficient was calculated from the following formula using the obtained nitrogen permeability and the film thickness: ３ mm / (m ２ 24h atm)) = GTR x d GTR: Nitrogen permeability (cm ３ / (m ２ 24h atm) d: Film thickness (mm) The nitrogen permeability of each film was evaluated based on the measured nitrogen permeability value, according to the following evaluation criteria. The higher the nitrogen permeability coefficient value, the higher the nitrogen permeability. (Evaluation criteria) ○: Nitrogen permeability coefficient is less than 0.90. ×: Nitrogen permeability coefficient is 0.90 or more.

[0051] <Surface Texture> An injection molding machine (ROBOSHOT α-50C, manufactured by FANUC Corporation) was used. The mold was engraved to produce 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. The copolymers obtained in each example were molded to obtain molded articles under the following molding conditions: cylinder temperature: 310°C, mold temperature: 150°C, injection speed: 20 mm / sec, dwell pressure: 78.4 MPa, dwell time: 3 sec, and cooling time: 30 sec. The obtained injection-molded articles were observed and evaluated according to the following criteria. The presence or absence of surface roughness was confirmed by touching the surface of the injection-molded article with a finger. (Evaluation Criteria) 3: The entire surface was smooth, and no flow marks were observed throughout the entire molded article. 2: Roughness is observed on the surface within 10 mm from the point where the mold gate was located, but the entire surface is smooth in other areas, and no flow marks are observed on the entire molded product. 1: Roughness is observed on the surface within 10 mm from the point where the mold gate was located, and flow marks are observed within 10 mm from the point where the mold gate was located, but the entire surface is smooth in other areas, and no flow marks are observed. 0: Roughness is observed on the surface within 40 mm from the point where the mold gate was located, and flow marks are observed within 40 mm from the point where the mold gate was located.

[0052] <TOC Elution Amount> The TOC (total organic carbon) elution amount was measured in accordance with SEMI F57 "Specifications for polymeric materials and parts used in ultrapure water and chemical supply systems." 30 g of sample (solid composition obtained in the examples) and the PFA container used were pre-washed with ultrapure water in accordance with SEMI F40. 30 g of the pre-washed sample was placed in a pre-washed PFA container, and 100 mL of ultrapure water was poured into the container to completely immerse it. The container was then sealed and elution was carried out at 85°C ± 3°C for 7 days. The concentration of each component in the eluate was measured using a TOC-L CPH (manufactured by Shimadzu Corporation), and the elution amount relative to the surface area was determined.

[0053] <Moisture Content> The moisture content was measured by the following procedure: Using an infrared moisture meter "FD610" (Kett Electric Laboratory Co., Ltd.), the moisture content was measured from the mass loss rate before and after the test under the conditions of a drying temperature of 140°C, a time static mode of 10 minutes, and a sample (solid composition obtained in the Examples) mass of 100 g.

[0054] [Evaluation Tests] <Production of Coated Test Pieces> A 50 mm long, 150 mm wide, and 2 mm thick SUS304 stainless steel plate was baked at 400°C for 1 hour, and then its surface was sandblasted with alumina particles ("White Fused Alumina 50A (product name)" manufactured by Pacific Random Co., Ltd.). The blasted powder was removed with an air gun to obtain a substrate. The copolymer obtained in the examples was pulverized to an average particle size of 80 to 120 μm, electrostatically coated on the substrate, and baked in an oven at 275°C for 15 minutes. The coating and baking processes were each performed four times to obtain a coated article with a powder coating layer approximately 250 μm thick formed on the substrate. <Hot Water Resistance Test (PCT Peel Test)> A utility knife was used to make horizontal parallel cuts at 10 mm intervals in the coating film formed on the coated test piece. At one end of the coated test piece where the primer layer was not present, the outermost layer and topcoat layer were peeled off from the substrate to create a gripping area. After treating the specimen in a pressure cooker (high-temperature steam pressure cooker) at 130°C for 24 hours, the gripping area was fixed to the chuck of a tensile tester, and the 90-degree peel strength (unit: N / cm) was measured at a pulling rate of 50 mm / min. Based on this value, the adhesive strength was evaluated according to the following criteria.

[0055] (Adhesion strength evaluation criteria) ○: 1.5 N / cm or more ×: less than 1.5 N / cm

[0056] [Example 1] Fluorine-based organic solvent (manufactured by AGC Inc., "ASAHIKLIN (registered trademark) AE-3000", CF ３ CH ２ OCF ２ CF ２ H) 1167 g and CH ２ =CH(CF ２ ) ４3.9 g of F(PFBE) and 5.8 g of methanol were charged into a pre-degassed polymerization vessel equipped with a stirrer and having an internal volume of 1.2 L. The interior of this polymerization vessel was heated to 72°C (polymerization temperature), and 180 g of a monomer mixed gas of TFE / ethylene = 88 / 12 (molar ratio) was further charged, and then the pressure inside the polymerization vessel was increased to 1.5 MPa [gauge]. Initially, 3.8 mL of a polymerization initiator solution in which tert-butyl peroxypivalate was dissolved in AE-3000 at a concentration of 1 mass% was charged, and polymerization was carried out. Furthermore, a monomer mixed gas of TFE / ethylene = 54 / 46 was continuously charged so that the pressure inside the polymerization vessel during the polymerization reaction was maintained at 1.5 MPa [gauge]. Furthermore, PFBE in an amount equivalent to 1.2 mol% relative to the total number of moles of TFE and ethylene charged during polymerization was continuously charged. The polymerization was terminated when the amount of TFE / ethylene introduced reached 110 g, to obtain Copolymer 1 of Example 1. The composition of Copolymer 1 was TFE unit / E unit / PFBE unit (molar ratio) = 54.3 / 44.5 / 1.2. The "PFBE unit" refers to the CH ２ =CH(CF ２ ) ４ The unit is based on F. The MFR of Copolymer 1 was 33 g / 10 min and the melting point was 259°C. Pure water was added to the obtained Copolymer 1, and the mixture was heated with stirring to remove the solvent. Next, water was removed from the mixture of pure water and Copolymer 1, and the mixture was dried at a drying temperature of 100°C or higher for 1.9 hours to obtain Solid Composition 1. The TOC elution amount of Solid Composition 1 after drying was 13,300 μg / cm ２ The moisture content was 0.14% by mass.

[0057] [Example 2] Copolymer 2 of Example 2 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 4.7 g and 7.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 1.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.4 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 2 was TFE unit / E unit / PFBE unit (molar ratio) = 54.8 / 44.8 / 0.4. The MFR of copolymer 2 was 33 g / 10 min and the melting point was 266 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 4.6 hours, thereby obtaining solid composition 2. The TOC elution amount of the solid composition after drying was 5,900 μg / cm ２ The water content was 0.03% by mass.

[0058] [Example 3] Copolymer 3 of Example 3 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 2.9 g and 6.0 g, respectively, the amount of polymerization initiator solution initially charged was changed to 3.1 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.0 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 3 was TFE unit / E unit / PFBE unit (molar ratio) = 54.5 / 44.5 / 1.0. The MFR of copolymer 3 was 35 g / 10 min and the melting point was 260°C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100°C or higher for 4.6 hours, thereby obtaining solid composition 3. The TOC elution amount of the solid composition after drying was 11,600 μg / cm ２ The moisture content was 0.12% by mass.

[0059] [Example 4] Copolymer 4 of Example 4 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 1.5 g and 6.7 g, respectively, the amount of polymerization initiator solution initially charged was changed to 2.2 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.7 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 4 was TFE unit / E unit / PFBE unit (molar ratio) = 54.6 / 44.7 / 0.7. The MFR of copolymer 4 was 37 g / 10 min and the melting point was 263°C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100°C or higher for 3.0 hours, to obtain solid composition 4. The TOC elution amount of the solid composition after drying was 9,100 μg / cm ２ The moisture content was 0.08% by mass.

[0060] [Example 5] Copolymer 5 of Example 5 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 3.9 g and 5.7 g, respectively, the amount of polymerization initiator solution initially charged was changed to 3.8 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.2 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 5 was TFE unit / E unit / PFBE unit (molar ratio) = 54.1 / 44.7 / 1.2. The MFR of copolymer 5 was 39 g / 10 min and the melting point was 259°C. Drying was carried out in the same manner as in Example 1, and solid composition 5 was obtained. The TOC elution amount of the solid composition after drying was 13,400 μg / cm ２ The moisture content was 0.14% by mass.

[0061] [Example 6] Copolymer 6 of Example 6 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 0.6 g and 7.2 g, respectively, the amount of polymerization initiator solution initially charged was changed to 1.6 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.5 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 6 was TFE unit / E unit / PFBE unit (molar ratio) = 54.5 / 45.0 / 0.5. The MFR of copolymer 6 was 40 g / 10 min and the melting point was 265°C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100°C or higher for 1.3 hours, to obtain solid composition 6. The TOC elution amount of the solid composition after drying was 6,000 μg / cm ２ The moisture content was 0.20% by mass.

[0062] [Example 7] Copolymer 7 of Example 7 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 2.0 g and 6.6 g, respectively, the amount of polymerization initiator solution initially charged was changed to 2.5 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.8 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 7 was TFE unit / E unit / PFBE unit (molar ratio) = 54.6 / 44.6 / 0.8. The MFR of copolymer 7 was 42 g / 10 min and the melting point was 262 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 2.7 hours, to obtain solid composition 7. The TOC elution amount of the solid composition after drying was 9,900 μg / cm ２ The water content was 0.09% by mass.

[0063] [Example 8] Copolymer 8 of Example 8 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 3.5 g and 6.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 3.4 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.1 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 8 was TFE unit / E unit / PFBE unit (molar ratio) = 54.4 / 44.5 / 1.1. The MFR of copolymer 8 was 44 g / 10 min and the melting point was 260°C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100°C or higher for 2.1 hours, to obtain solid composition 8. The TOC elution amount of the solid composition after drying was 12,500 μg / cm ２ The water content was 0.13% by mass.

[0064] [Example 9] Copolymer 9 of Example 9 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 0.6 g and 7.4 g, respectively, the amount of polymerization initiator solution initially charged was changed to 1.6 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.5 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 9 was TFE unit / E unit / PFBE unit (molar ratio) = 54.5 / 45.0 / 0.5. The MFR of copolymer 9 was 50 g / 10 min and the melting point was 265°C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100°C or higher for 3.7 hours, to obtain solid composition 9. The TOC elution amount of the solid composition after drying was 7,400 μg / cm ２ The moisture content was 0.06% by mass.

[0065] [Example 10] Fluorine-based organic solvent (manufactured by AGC Inc., "ASAHIKLIN (registered trademark) AE-3000", CF ３ CH ２ OCF ２ CF ２ H) 1167 g and CF ２ = CFO (CF ２41.6 g of )2F(PPVE) and 15.2 g of methanol were charged into a pre-degassed polymerization vessel with an internal volume of 1.2 L and equipped with a stirrer. The solution in this polymerization vessel was heated to 66°C (polymerization temperature), and TFE / ethylene = 76 / 24 (molar ratio) was added until the pressure in the polymerization vessel reached 1.5 MPa [gauge]. Initially, 3.0 mL of a polymerization initiator solution prepared by dissolving tert-butyl peroxypivalate in AE-3000 at a concentration of 1% by mass was charged, and polymerization was carried out. Furthermore, a mixed gas of TFE / ethylene = 54 / 46 (molar ratio) was continuously charged so that the pressure in the polymerization vessel was maintained at 1.5 MPa [gauge] during the polymerization reaction. Furthermore, PPVE was continuously charged in an amount equivalent to 1.0 mol % relative to the total number of moles of TFE and ethylene charged during the polymerization. The polymerization was terminated when the amount of TFE / ethylene introduced reached 110 g, to obtain Copolymer 10 of Example 10. The composition of Copolymer 10 was TFE unit / E unit / PPVE unit (molar ratio) = 53.4 / 45.6 / 1.0. The "PPVE unit" refers to the CF of each copolymer. ２ = CFO (CF ２ )2F. The MFR of copolymer 12 was 35 g / 10 min, and the melting point was 271°C. Pure water was added to the obtained copolymer 10, and the mixture was heated with stirring in the same manner as in Example 1 to remove the solvent. Next, water was removed from the mixture of pure water and copolymer 10, and the mixture was dried by maintaining the drying temperature at 100°C or higher for 2.3 hours. The TOC elution amount of solid composition 10 after drying was 11,500 μg / cm ２ The moisture content was 0.12% by mass.

[0066] [Example 11] Copolymer 11 of Example 11 was obtained in the same manner as in Example 10, except that the amount of PPVE initially charged into the polymerization vessel was changed to 25.3 g, the amount of methanol was changed to 16.8 g, and the amount of PPVE continuously charged during polymerization was changed to an amount equivalent to 0.6 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 11 was TFE unit / E unit / PPVE unit (molar ratio) = 53.3 / 46.1 / 0.6. The MFR of copolymer 11 was 36 g / 10 min and the melting point was 275°C. Drying was performed in the same manner as in Example 1, except that drying was performed so as to maintain a state of 100°C or higher for 3.3 hours, to obtain solid composition 11. The TOC elution amount of the solid composition after drying was 8,250 μg / cm ２ The water content was 0.07% by mass.

[0067] [Example 12] Copolymer 12 of Example 12 was obtained in the same manner as in Example 1, except that the amount of PFBE initially charged into the polymerization vessel was changed to 2.5 g, the amount of methanol was changed to 6.6 g, the amount of polymerization initiator solution initially charged was changed to 2.8 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.9 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 12 was TFE unit / E unit / PFBE unit (molar ratio) = 54.4 / 44.7 / 0.9. The MFR of copolymer 12 was 29 g / 10 min and the melting point was 261 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 3.3 hours, thereby obtaining solid composition 12. The TOC elution amount of the solid composition after drying was 11,400 μg / cm ２ The water content was 0.11% by mass.

[0068] [Example 13] Copolymer 13 of Example 13 was obtained in the same manner as in Example 1, except that the amount of PFBE initially charged into the polymerization vessel was changed to 4.9 g, the amount of methanol was changed to 5.4 g, the amount of polymerization initiator solution initially charged was changed to 4.4 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.4 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 13 was TFE unit / E unit / PFBE unit (molar ratio) = 54.2 / 44.4 / 1.4. The MFR of copolymer 13 was 41 g / 10 min, and the melting point was 257 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 1.6 hours, thereby obtaining solid composition 13. The TOC elution amount of the solid composition after drying was 15,000 μg / cm ２ The water content was 0.17% by mass.

[0069] [Example 14] Copolymer 14 of Example 14 was obtained in the same manner as in Example 1, except that the amount of PFBE initially charged into the polymerization vessel was changed to 3.5 g, the amount of methanol was changed to 6.6 g, the amount of polymerization initiator solution initially charged was changed to 3.4 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.1 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 14 was TFE unit / E unit / PFBE unit (molar ratio) = 54.4 / 44.5 / 1.1. The MFR of copolymer 14 was 64 g / 10 min and the melting point was 260 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 2.1 hours, thereby obtaining solid composition 14. The TOC elution amount of the solid composition after drying was 12,700 μg / cm ２ The water content was 0.13% by mass.

[0070] [Example 15] Copolymer 15 of Example 15 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 0.66 g and 9.9 g, respectively, the amount of polymerization initiator solution initially charged was changed to 1.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.2 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 15 was TFE unit / E unit / PFBE unit (molar ratio) = 54.5 / 45.3 / 0.2. The MFR of copolymer 15 was 40 g / 10 min and the melting point was 268°C. Drying was carried out in the same manner as in Example 1, and solid composition 15 was obtained. The TOC elution amount of the solid composition after drying was 15,000 μg / cm ２ The moisture content was 0.14% by mass.

[0071] [Example 16] Copolymer 16 of Example 16 was obtained in the same manner as in Example 1, except that the amount of PFBE and the amount of methanol initially charged into the polymerization vessel were changed to 3.9 g and 5.7 g, respectively, the amount of polymerization initiator solution initially charged was changed to 3.8 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.2 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 16 was TFE unit / E unit / PFBE unit (molar ratio) = 54.0 / 44.8 / 1.2. The MFR of copolymer 16 was 39 g / 10 min and the melting point was 259 ° C. Drying was also carried out in the same manner as in Example 1, except that drying was carried out so as to maintain a state of 100 ° C or higher for 0.5 hours, thereby obtaining solid composition 16. The TOC elution amount of the solid composition after drying was 64,000 μg / cm ２ The moisture content was 0.89% by mass.

[0072] [Example 17] The amount of PFBE initially charged into the polymerization vessel was changed to 3.9 g, the amount of methanol to 5.7 g, the amount of polymerization initiator solution initially charged to 3.8 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.2 mol% relative to the total moles of TFE and ethylene. Copolymer 17 of Example 17 was obtained in the same manner as in Example 1. The composition of copolymer 17 was TFE unit / E unit / PFBE unit (molar ratio) = 54.2 / 44.6 / 1.2. The MFR of copolymer 17 was 39 g / 10 min and the melting point was 259 ° C. Drying was performed in the same manner as in Example 1, except that drying was performed so as to maintain a state of 100 ° C. or higher for 6.8 hours, to obtain solid composition 17. The TOC elution amount of the solid composition after drying was 980 μg / cm ２ The water content was 0.01% by mass.

[0073] Table 1 shows the composition of the copolymer of each example, as well as the measurement and evaluation results of the copolymer. In the table, the "TFE unit (mol%)" column shows the content (unit: mol%) of TFE units relative to all units contained in the copolymer. The "E unit (mol%)" column shows the content (unit: mol%) of E units relative to all units contained in the copolymer. The "TFE / (TFE+E) (mol%)" column shows the content (unit: mol%) of TFE units relative to the total content of TFE units and E units. The "A unit (mol%)" column shows the content (unit: mol%) of A units relative to all units contained in the copolymer.

[0074]

[0075]

[0076] As shown in Table 1, by using a copolymer that contains TFE units, E units, and A units, the total content of the TFE units and E units is 80.0 to 99.7 mol% based on the total units contained in the copolymer, the content of the TFE units is 49.0 mol% or more and less than 56.0 mol% based on the total content of the TFE units and E units, the content of the A units is 0.3 to 1.3 mol% based on the total units contained in the copolymer, and the MFR is 33 to 50 g / 10 min, it was confirmed that it is possible to form a molded article that has low nitrogen permeability and low yellowness and excellent surface properties (Examples 1 to 11).

[0077] Table 2 shows the measurement results and evaluation results of the solid composition of each example. In the table, the column "TFE units (mol %)" indicates the content (unit: mol %) of TFE units relative to all units contained in the copolymer. The column "E units (mol %)" indicates the content (unit: mol %) of E units relative to all units contained in the copolymer. The column "TFE / (TFE+E) (mol %)" indicates the content (unit: mol %) of TFE units relative to the total content of TFE units and E units. The column "A units (mol %)" indicates the content (unit: mol %) of A units relative to all units contained in the copolymer.

[0078]

[0079]

[0080] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-099108, filed on June 16, 2023, are incorporated herein by reference as part of the disclosure of the present invention.

Claims

1. A copolymer comprising units based on tetrafluoroethylene, units based on ethylene, and either or both of units based on a compound represented by formula (1) and units based on a compound represented by formula (2), wherein the total content of the units based on tetrafluoroethylene and the units based on ethylene is 80.0 to 99.7 mol % based on all units contained in the copolymer, the content of the units based on tetrafluoroethylene is 49.0 mol % or more and less than 56.0 mol % based on the total content of the units based on tetrafluoroethylene and the units based on ethylene, the content of the units based on a compound represented by formula (1) or the compound represented by formula (2) is 0.3 to 1.3 mol % based on all units contained in the copolymer, and the melt flow rate measured in accordance with ASTM D3159 under conditions of a temperature of 297°C and a load of 49 N is 33 to 50 g / 10 min. CZ ２ = CX (CF ２ ) ｍ Y Formula (1) CF ２ =CF-O-(CF ２ ) ｎ F Formula (2) In formula (1), X, Y and Z each independently represent a hydrogen atom or a fluorine atom, and m represents an integer of 2 to 6. In formula (2), n represents an integer of 1 to 6.

2. The copolymer according to claim 1, comprising units based on said tetrafluoroethylene, units based on said ethylene, and units based on the compound represented by formula (1), wherein the content of the units based on the compound represented by formula (1) is 0.3 to 1.3 mol % based on all units contained in said copolymer.

3. A composition comprising the copolymer according to claim 1 or 2.

4. A composition comprising the copolymer according to claim 1 or 2, the amount of TOC (total organic carbon) eluted being 1,000 to 63,000 μg / cm ２ A solid composition comprising:

5. A solid composition comprising the copolymer according to claim 1 or 2, and having a water content of 0.02 to 0.8% by mass.

6. A molded article obtained by molding the copolymer according to claim 1 or 2.

7. A molded article obtained by molding the composition according to claim 3.

8. A molded article obtained by molding the solid composition according to claim 4.