Copolymer, composition, and molded body

Abstract

The present invention provides: a copolymer which is capable of forming a molded body that is excellent in terms of the degree of yellowing, the elongation and the non-defective rate; a composition; and a molded body.　A copolymer according to the present invention contains a unit based on tetrafluoroethylene, a unit based on ethylene, and one or both of a unit based on a compound represented by formula (1) and a unit based on a compound represented by formula (2). The total content of the unit based on tetrafluoroethylene and the unit based on ethylene is 80% by mole to 96.8% by mole with respect to all units contained in the copolymer. The content of the unit based on tetrafluoroethylene is not less than 49.0% by mole but less than 56.0% by mole with respect to the total content of the unit based on tetrafluoroethylene and the unit based on ethylene. The content of the unit based on a compound represented by formula (1) or a compound represented by formula (2) is 3.2% by mole to 4.0% by mole with respect to all units contained in the copolymer. The melt flow rate of the copolymer is 25-50 g / 10 minutes as measured under the conditions of a temperature of 297°C and a load of 49 N in accordance with ASTM D3159.　Formula (1): CZ2=CX(CF2)mY Formula (2): CF2=CF-O-(CF2)nF

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 a polymer composition containing a copolymer having ethylene repeating units, tetrafluoroethylene repeating units, and other repeating units.

[0003] Chinese Patent Application Publication No. 104151754

[0004] When ETFE is used as the constituent material of molded article, it is required that it has excellent properties such as mechanical strength, heat resistance and chemical resistance, and also has excellent appearance and the quality stability of molded article.The present inventors have evaluated the molded article formed by using the ETFE described in Patent Document 1, and have found that there is room for improvement in yellowness, elongation and non-defective rate.

[0005] Therefore, an object of the present invention is to provide a copolymer capable of forming a molded article excellent in yellowness index, elongation, and yield rate, 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 25 to 50 g / 10 min, it is possible to form a molded product excellent in yellowness index, elongation, and yield rate, and have arrived at the present invention.

[0007] That is, the inventors have found that the above 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) described below and units based on a compound represented by formula (2) described below, wherein the total content of the units based on tetrafluoroethylene and the units based on ethylene is 80.0 to 96.8 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) described below or the compound represented by formula (2) described below is 3.2 to 4.0 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 25 to 50 g / 10 min. [2] The copolymer according to [1], which contains 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 3.2 to 4.0 mol% based on all units contained in the copolymer. [3] A composition comprising the copolymer according to [1] or [2]. [4] A composition comprising the copolymer according to [1] or [2], which has an elution amount of TOC (total organic carbon) of 1,000 to 63,000 μg / cm ２ [5] A solid composition comprising the copolymer according to [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 [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 excellent in yellowness index, elongation, and yield rate. Furthermore, according to the present invention, there is 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 25 to 50 g / 10 min measured at a temperature of 297°C and a load of 49 N in accordance with ASTM D3159.

[0012] The present copolymer can form molded articles with excellent yellowness index, elongation, and yield. While the details of the reasons for this are not yet clear, it is presumed to be due to the following reasons. One of the reasons why the present copolymer can form molded articles with excellent properties is thought to be the use of a copolymer in which the content of A units based on the compound represented by formula (1) or formula (2) described below is 3.2 to 4.0 mol% relative to all units contained in the copolymer, and the copolymer has a melt flow rate of 25 to 50 g / 10 min. That is, it is presumed that a melt flow rate of 25 g / 10 min or more is not too low, resulting in good flexibility and less cracking, thereby improving the elongation of the molded article. It is presumed that a melt flow rate of 50 g / 10 min or less is not too high, resulting in less decomposition of the copolymer, thereby suppressing voids in the molded article and improving the yield of the molded article. In addition, it is presumed that the content of A units is 3.2 mol% or more relative to the total units contained in the copolymer, so that the content of A units is not too small in copolymers with relatively high melt flow rates, which can suppress the decrease in transparency due to milky white coloring of the molded body, and the yellowness of the molded body can be suppressed low.In addition, it is presumed that the content of A units is 4.0 mol% or less relative to the total units contained in the copolymer, so that the content of A units is not too high, and the copolymer constituting the molded body is less likely to undergo various decomposition reactions even at high temperatures, which can improve the yield rate of the molded body.In this way, it is presumed that by specifying the content of A units and the melt flow rate, molded bodies with excellent yellowness, elongation, and yield rate can be obtained.

[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 ) 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.

[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 ) ３ F, 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 3.2 to 4.0 mol% based on all units contained in the copolymer. When the content of A units is 3.2 mol% or more based on all units contained in the copolymer, a molded article having excellent yellowness, elongation, and haze can be formed. Furthermore, when the content of A units is 4.0 mol% or less based on all units contained in the copolymer, a molded article having excellent yield rate, suppressed deterioration at high temperatures, and excellent long-term mechanical stability can be formed. The content of A units is preferably 3.4 to 3.9 mol% based on all units contained in the copolymer, in order to achieve a good balance between yellowness and yield rate.

[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 bending resistance, a copolymer having TFE units, E 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 the A1 units is 3.2 to 4.0 mol% based on the total units contained in the present copolymer, and from the above viewpoint, 3.4 to 3.9 mol% is preferred. When the present copolymer is a copolymer containing TFE units, E units, and A2 units, the content of the A2 units is 3.2 to 4.0 mol% based on the total units contained in the present copolymer, and from the above viewpoint, 3.3 to 3.8 mol% is preferred.

[0021] In this copolymer, the total content of TFE units and E units is 80.0 to 96.8 mol% based on all units contained in this copolymer. The total content of TFE units and E units is preferably 85.0 mol% or more, more preferably 88.0 mol% or more, from the viewpoint of excellent durability against repeated load. Furthermore, the total content of TFE units and E units is preferably 96.6 mol% or less, from the viewpoint of excellent surface smoothness of the molded article.

[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 mol% or more and less than 56.0 mol%, more preferably 52.0 mol% or more and less than 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 54.0 mol%, more preferably 45.0 to 53.9 mol%, and particularly preferably 50.0 to 53.5 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 49.0 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 other monomers other than tetrafluoroethylene, ethylene, the compound represented by formula (1), and the compound represented by formula (2). Specific examples of other monomers include fluoroolefins (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, Rf１ 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 (wherein p is 1 or 2); fluorine-containing monomers having a ring structure (perfluoro(2,2-dimethyl-1,3-dioxole), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, perfluoro(2-methylene-4-methyl-1,3-dioxolane), etc.); and 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 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 comprising TFE units, E units, and A units is preferred, and an embodiment comprising 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 25 to 50 g / 10 min. When the present copolymer has an MFR of 25 g / 10 min or more, a molded article having excellent elongation, light transmittance, yellowness index, and yield rate can be formed. Furthermore, when the present copolymer has an MFR of 50 g / 10 min or less, a molded article having excellent yield rate and high-temperature sealability can be formed. The MFR of the present copolymer is preferably 27 to 50 g / 10 min in terms of achieving a good balance between elongation and yield rate. 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 having 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 220°C or higher, more preferably 225°C or higher, and particularly preferably 230°C or higher, from the viewpoint of superior durability against repeated load. Furthermore, the melting point of the present copolymer is preferably 280°C or lower, more preferably 270°C or lower, and particularly preferably 260°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 ２Preferred 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 excellent in yellowness index, elongation, and yield rate 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 ２Since the adhesive strength after the hot water resistance test is high, the TOC elution amount is 50,000 μg / cm ２ Preferably, it is 30,000 μg / cm or less. ２ It is more preferable that the TOC elution amount is 2,000 μg / cm or less, since the tensile strength after the heat aging test is high. ２ It is preferable that the concentration is 5,000 μg / cm or more. ２ Specific examples of methods for controlling the TOC elution amount of the present solid composition within the above range include methods of adjusting the purity of water used in granulating the present 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 is excellent in yellowness index, elongation, and yield rate. Specific molding methods include injection molding, extrusion molding, blow molding, press molding, rotational molding, and electrostatic coating. As a molding method for the molded article, press molding or injection molding is preferred. Injection molding is more preferred because it can produce an injection-molded article with a 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 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.Among these, the molded article is particularly suitable for use as a chemical liquid transport member or industrial film because of its excellent yellowness index, elongation and yield rate.

[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 18 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 a temperature 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. 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 (excluding the evaluation test for the yield rate).

[0046] <Heat Resistance> A dumbbell-shaped test piece as defined in JIS K6301 No. 3 was cut out from the obtained film having a thickness of 1 mm. The test piece was measured for tensile elongation (unit: %) in accordance with the method of ASTM D-3159 using a Strograph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) by setting the distance between the gripping jigs to 35 mm and pulling the test piece at a pulling rate of 200 mm / min in a room temperature environment (temperature 23±2°C).

[0047] The test piece was placed in a gear oven (forced circulation air heating aging tester) (manufactured by Toyo Seiki Seisakusho, Ltd.) and subjected to a heat exposure treatment. The temperature was set to 250°C, and the heat treatment was carried out for 24 hours after placement. The tensile elongation of the test piece after the heat treatment was measured in the same manner as above. The tensile elongation ratio after the heat treatment was calculated, assuming that the tensile elongation before the heat treatment was 100%, and was evaluated according to the following criteria.

[0048] (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%

[0049] <Light transmittance> The light transmittance of a 200 μm thick film was measured at a wavelength of 300 nm using a spectrophotometer (Shimadzu Corporation's "UV-2200") The light transmittance of each film was evaluated based on the measured light transmittance values ​​and the following evaluation criteria.

[0050] (Light transmittance evaluation criteria) ◯: Light transmittance is more than 91%. Δ: Light transmittance is 90% or more and 91% or less. ×: Light transmittance is less than 90%.

[0051] <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.

[0052] (Evaluation Criteria for Yellowness Index) ◯: YI value is less than 2.0. ×: YI value is 2.0 or more.

[0053] <Haze> According to JIS K7105, the haze (cloudiness, unit: %) of a 200 μm thick film was measured using a haze meter (manufactured by Nippon Seimitsu Kogaku Co., Ltd., model: SEP-T). From the measured haze value, the haze of each film was evaluated based on the following evaluation criteria.

[0054] (Haze evaluation criteria) ◯: Haze is less than 3.0%. Δ: Haze is 3.0% or more and less than 4.0%. ×: Haze is 4.0% or more.

[0055] <Elongation> A 1 mm thick film was press-molded according to the above molding method, and a dumbbell-shaped test piece as defined in ASTM-D638 Type V was cut from the obtained film. A tensile creep test was performed on the obtained test piece using a Strograph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) in an environment of 175°C, with the test piece being pulled at an initial gauge length of 25.4 mm and a pulling speed of 200 mm / min. The tensile creep test was continued until the test piece broke, and the value of the gauge length (unit: mm) when the test piece broke was measured. The elongation of each film was evaluated based on the measured gauge length at break, based on the following evaluation criteria.

[0056] (Evaluation criteria for elongation) ○: The gauge length at break was 190 mm or more ×: The gauge length at break was less than 190 mm

[0057] <Folding endurance> A folding fatigue test was carried out according to the MIT method, which is known as a method for evaluating stress crack resistance, in accordance with ASTM D2176. First, a film having a thickness of 0.23 mm was press-molded according to the above molding method, and a rectangular test piece having a width of 12.5 mm and a length of 130 mm was cut out from the obtained film. The obtained test piece was mounted on an MIT folding fatigue tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the test piece was bent under conditions of a load of 1.25 kg, a left and right bending angle of 135 degrees each, and a bending frequency of 175 times / min, and the number of times the test piece was bent until it broke (folding endurance) was measured. From the measured folding endurance, the folding endurance of each film was evaluated based on the following evaluation criteria. A higher number of folding endurance indicates better folding endurance.

[0058] (Evaluation criteria for folding endurance) ○: Number of folding times is 200,000 or more △: Number of folding times is 100,000 or more but less than 200,000 ×: Number of folding times is less than 100,000

[0059] <Quality Rate> An injection molding machine (FANUC Corporation, "ROBOSHOT α-50C") was prepared for producing injection-molded articles. The mold used for the injection molding machine was a mold engraved to obtain cylindrical molded articles with design dimensions of an outer diameter of 25 mm, an inner diameter of 20 mm, and a height of 20 mm. A tunnel gate with a gate tip diameter of 1.0 mm was used as the gate. Using the injection molding machine, the copolymers obtained in each example were injection molded to obtain molded articles under molding conditions of a cylinder temperature of 350°C, a mold temperature of 150°C, an injection speed of 20 mm / sec, a dwell pressure of 78.4 MPa, a dwell time of 3 sec, and a cooling time of 30 sec. The surfaces of the obtained molded articles were visually observed, and molded articles in which neither irregularities nor holes were found on the surface were judged to be good products, while molded articles in which at least one of irregularities and holes was found on the surface were judged to be defective products. The above injection molding was performed 1000 times, and the resulting 1000 injection-molded articles for evaluation were visually observed and judged as described above. The ratio of the number of molded articles judged to be defective to the total number of injection-molded articles for evaluation (non-defective product rate, unit: %) was calculated, and the non-defective product rate was evaluated based on the following criteria.

[0060] (Evaluation criteria for non-defective rate) ○: Non-defective rate is 97% or more △: Non-defective rate is 95% or more and less than 97% ×: Non-defective rate is less than 95%

[0061] <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.

[0062] <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.

[0063] [Evaluation Test] <Production of Coated Test Piece> A SUS304 stainless steel plate measuring 50 mm in length, 150 mm in width, and 2 mm in thickness was baked at 400°C for 1 hour, and then its surface was sandblasted using alumina particles ("White Fused Alumina 50A (trade name)" manufactured by Pacific Random Co., Ltd.), and the blasted powder was removed with an air gun to obtain a substrate. The copolymer obtained in the example was pulverized to an average particle size of 80 to 120 μm, and this was electrostatically coated on the substrate, which was then baked in an oven at 275°C for 15 minutes. The painting step and the baking step were each performed four times, yielding a coated article in which a coating film layer made of powder with a thickness of approximately 250 μm was formed on the substrate.

[0064] <Hot Water Resistance Test (PCT Peel Test)> Using a cutter knife, horizontal parallel cuts were made at 10 mm intervals in the coating film formed on a coated test piece. At one end of the coated test piece, where the primer layer was not present, the outermost layer and the top coat layer were peeled off from the substrate to form a gripping area. After treating at 130°C for 24 hours in a pressure cooker (high-temperature steam pressure cooker), 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.

[0065] (Adhesion strength evaluation criteria) ○: 1.5 N / cm or more ×: less than 1.5 N / cm

[0066] [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 ) ４12.8 g of F(PFBE) and 1.8 g of methanol were charged into a previously degassed polymerization vessel equipped with a stirrer and having an internal volume of 1.2 L. The solution in this polymerization vessel was heated to 72 ° C (polymerization temperature), and 180 g of a mixed gas of TFE / ethylene = 89 / 11 (molar ratio) was further charged, and then the pressure in the polymerization vessel was increased to 1.5 MPa [gauge]. Initially, 12.2 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 mixed gas of TFE / ethylene = 54 / 46 (molar ratio) was continuously charged so that the pressure in the polymerization vessel during the polymerization reaction was maintained at 1.5 MPa [gauge]. Furthermore, PFBE in an amount equivalent to 3.9 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) = 52.4 / 43.7 / 3.9. The "PFBE unit" refers to the CH ２ =CH(CF ２ ) ４ The unit is based on F. The MFR of Copolymer 1 was 25 g / 10 min and the melting point was 234°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 3.0 hours to obtain Solid Composition 1. The TOC elution amount of Solid Composition 1 after drying was 8,300 μg / cm ２ The moisture content was 0.08% by mass.

[0067] [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 11.5 g and 2.7 g, respectively, the amount of polymerization initiator solution initially charged was changed to 10.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.3 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) = 52.7 / 44.0 / 3.3. The MFR of copolymer 2 was 27 g / 10 min, and the melting point was 240 ° 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 2.3 hours, thereby obtaining solid composition 2. The TOC elution amount of the solid composition after drying was 11,700 μg / cm ２ The water content was 0.13% by mass.

[0068] [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 12.4 g and 2.4 g, respectively, the amount of polymerization initiator solution initially charged was changed to 11.6 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.7 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 3 was TFE unit / E unit / PFBE unit (molar ratio) = 53.0 / 43.3 / 3.7. The MFR of copolymer 3 was 30 g / 10 min, and the melting point was 236 ° 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 2.4 hours, thereby obtaining solid composition 3. The TOC elution amount of the solid composition after drying was 11,100 μg / cm ２ The moisture content was 0.12% by mass.

[0069] [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 11.7 g and 3.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 10.6 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.4 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) = 53.1 / 43.5 / 3.4. The MFR of copolymer 4 was 34 g / 10 min and the melting point was 239 ° 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, thereby obtaining solid composition 4. The TOC elution amount of the solid composition after drying was 9,600 μg / cm ２ The water content was 0.10% by mass.

[0070] [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 11.2 g and 3.5 g, respectively, the amount of polymerization initiator solution initially charged was changed to 10.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.2 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) = 53.0 / 43.8 / 3.2. The MFR of copolymer 5 was 38 g / 10 min and the melting point was 241 ° 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 2.8 hours, to obtain solid composition 5. The TOC elution amount of the solid composition after drying was 8900 μg / cm ２ The water content was 0.09% by mass.

[0071] [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 12.8 g and 2.5 g, respectively, the amount of polymerization initiator solution initially charged was changed to 12.2 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.9 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) = 52.8 / 43.3 / 3.9. The MFR of copolymer 6 was 36 g / 10 min and the melting point was 234 ° 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 2.0 hours, to obtain solid composition 6. The TOC elution amount of the solid composition after drying was 13,700 μg / cm ２ The water content was 0.16% by mass.

[0072] [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 12.7 g and 3.0 g, respectively, the amount of polymerization initiator solution initially charged was changed to 11.9 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.8 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) = 52.8 / 43.4 / 3.8. The MFR of copolymer 7 was 45 g / 10 min and the melting point was 235°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 3.2 hours, to obtain solid composition 7. The TOC elution amount of the solid composition after drying was 7,600 μg / cm ２ The water content was 0.07% by mass.

[0073] [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 12.2 g and 3.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 11.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.6 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) = 53.1 / 43.3 / 3.6. The MFR of copolymer 8 was 41 g / 10 min and the melting point was 237 ° 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 13,000 μg / cm ２ The moisture content was 0.15% by mass.

[0074] [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 11.2 g and 4.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 10.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.2 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) = 53.2 / 43.6 / 3.2. The MFR of copolymer 9 was 50 g / 10 min and the melting point was 241 ° 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 2.3 hours, thereby obtaining solid composition 9. The TOC elution amount of the solid composition after drying was 11,700 μg / cm ２ The water content was 0.13% by mass.

[0075] [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 ２124.6 g of )2F(PPVE) and 8.4 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, 12.0 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 during the polymerization reaction was maintained at 1.5 MPa [gauge]. Furthermore, PPVE was continuously charged in an amount equivalent to 3.2 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) = 52.6 / 44.2 / 3.2. The "PPVE unit" refers to the CF of each copolymer. ２ = CFO (CF ２ )2F. The MFR of copolymer 12 was 45 g / 10 min, and the melting point was 253°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 drying was carried out by maintaining a drying temperature of 100°C or higher for 3.2 hours. The TOC of solid composition 10 after drying was 7,700 μg / cm ２ The water content was 0.07% by mass.

[0076] [Example 11] Copolymer 11 of Example 11 was obtained in the same manner as in Example 10, except that the amount of PPVE and the amount of methanol initially charged into the polymerization vessel were changed to 135.2 g and 7.8 g, respectively, the amount of polymerization initiator solution initially charged was changed to 13.0 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount equivalent to 3.5 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 11 was TFE unit / E unit / PPVE unit (molar ratio) = 52.4 / 44.1 / 3.5. The MFR of copolymer 11 was 35 g / 10 min and the melting point was 252 ° 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 2.8 hours, to obtain solid composition 11. The TOC elution amount of the solid composition after drying was 88.00 μg / cm ２ The water content was 0.09% by mass.

[0077] [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 12.2 g, the amount of methanol to 3.0 g, the amount of polymerization initiator solution initially charged to 11.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.6 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) = 52.8 / 43.6 / 3.6. The MFR of copolymer 12 was 23 g / 10 min and the melting point was 237 ° 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, thereby obtaining solid composition 12. The TOC elution amount of the solid composition after drying was 6,280 μg / cm ２ The water content was 0.05% by mass.

[0078] [Example 13] Copolymer 13 of Example 13 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 10.4 g and 3.1 g, respectively, the amount of polymerization initiator solution initially charged was changed to 9.1 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 2.9 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) = 53.1 / 44.0 / 2.9. The MFR of copolymer 13 was 29 g / 10 min and the melting point was 243 ° 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 4.5 hours, to obtain solid composition 13. The TOC elution amount of the solid composition after drying was 4,900 μg / cm ２ The water content was 0.03% by mass.

[0079] [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 9.8 g, the amount of methanol to 3.9 g, the amount of polymerization initiator solution initially charged to 8.4 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 2.7 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) = 53.5 / 43.8 / 2.7. The MFR of copolymer 14 was 38 g / 10 min and the melting point was 245 ° 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, thereby obtaining solid composition 14. The TOC elution amount of the solid composition after drying was 6,300 μg / cm ２ The water content was 0.05% by mass.

[0080] [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 13.2 g and 4.6 g, respectively, the amount of polymerization initiator solution initially charged was changed to 13.2 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.2 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) = 53.2 / 43.6 / 3.2. The MFR of copolymer 15 was 65 g / 10 min and the melting point was 241 ° 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 2.5 hours, and solid composition 15 was obtained. The TOC elution amount of the solid composition after drying was 10,000 μg / cm ２ The water content was 0.11% by mass.

[0081] [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 14.9 g and 14 g, respectively, the amount of polymerization initiator solution initially charged was changed to 15.6 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 5.0 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) = 52.5 / 42.5 / 5.0. The MFR of copolymer 16 was 36.0 g / 10 min and the melting point was 224 ° 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 2.4 hours, thereby obtaining solid composition 16. The TOC elution amount of the solid composition after drying was 11,000 μg / cm ２ The moisture content was 0.12% by mass.

[0082] [Example 17] Copolymer 17 of Example 17 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 12.2 g, the amount of methanol was changed to 3.0 g, the amount of polymerization initiator solution initially charged was changed to 11.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.6 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 17 was TFE unit / E unit / PFBE unit (molar ratio) = 53.0 / 43.4 / 3.6. The MFR of copolymer 17 was 40 g / 10 min, and the melting point was 237 ° 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 17. The TOC elution amount of the solid composition after drying was 66,000 μg / cm ２ The water content was 0.98% by mass.

[0083] [Example 18] The amount of PFBE initially charged into the polymerization vessel was changed to 12.2 g, the amount of methanol to 3.1 g, the amount of polymerization initiator solution initially charged to 11.3 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 3.6 mol% relative to the total moles of TFE and ethylene. Except for this, copolymer 18 of Example 18 was obtained in the same manner as in Example 1. The composition of copolymer 18 was TFE unit / E unit / PFBE unit (molar ratio) = 53.2 / 43.1 / 3.6. The MFR of copolymer 18 was 41 g / 10 min, and the melting point was 237 ° 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 6.1 hours, to obtain solid composition 18. The TOC elution amount of the solid composition after drying was 960 μg / cm ２ The water content was 0.01% by mass.

[0084] 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.

[0085]

[0086]

[0087]

[0088] 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 the E units is 80.0 to 96.8 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 the E units, the content of the A units is 3.2 to 4.0 mol% based on the total units contained in the copolymer, and MFR is 25 to 50 g / 10 min, it was confirmed that it is possible to form a molded product that is excellent in yellowness index, elongation, and non-defective rate (Examples 1 to 11).

[0089] 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.

[0090]

[0091]

[0092]

[0093] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-098962, 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), characterized in that the total content of the units based on tetrafluoroethylene and the units based on ethylene is 80.0 to 96.8 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 3.2 to 4.0 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 25 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 3.2 to 4.0 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.

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