Method for producing copolymer and method for producing molded body

Abstract

The present invention addresses the problem of providing: a method for producing a copolymer, the method being capable of producing a copolymer that changes little in tensile strength through a heat aging test, has a high tensile elongation, and has low oxygen permeability; and a method for producing a molded body.　A method for producing a copolymer according to the present invention is for producing a copolymer by polymerizing monomers including tetrafluoroethylene, ethylene, and a compound represented by formula (1): CZ2 = CX(CF2)mY. The compound represented by formula (1) has a purity of 99.5% or higher. The total content of units based on the tetrafluoroethylene and units based on the ethylene is 80.0-99.5 mol% with respect to all the units contained in the copolymer, and the content of units based on the compound represented by formula (1) is 0.5-3.5 mol% with respect to all the units contained in the copolymer.

Description

Method for producing copolymer and method for producing molded product

[0001] The present invention relates to a method for producing a copolymer and a method for producing 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 excellent moldability and mechanical strength among fluororesins.Therefore, ETFE is melt-molded by methods such as extrusion molding, blow molding, injection molding, and rotational molding to produce a variety of molded articles such as electric wire coverings, tubes, sheets, films, filaments, pump casings, joints, packings, linings, and coatings.For example, Patent Document 1 discloses a polymer composition containing a copolymer having an ethylene repeating unit, a tetrafluoroethylene repeating unit, and other repeating units.

[0003] Chinese Patent Application Publication No. 104151754

[0004] When ETFE is used as a constituent material of a molded article, it is required to have excellent properties such as chemical resistance, heat resistance, mechanical strength, etc. When the present inventors evaluated the molded article formed by using ETFE described in Patent Document 1, they found that there is room for improvement in heat resistance (particularly, the change in tensile strength before and after heat aging test), mechanical strength (particularly, tensile elongation) and oxygen permeability.

[0005] Therefore, an object of the present invention is to provide a method for producing a copolymer that can produce a copolymer that shows little change in tensile strength before and after a heat aging test, has high tensile elongation, and has low oxygen permeability.Another object of the present invention is to provide a method for producing a molded article.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that a copolymer having a small retention rate of tensile strength before and after a heat aging test, a large tensile elongation, and low oxygen permeability can be produced by a copolymer production method in which a monomer containing tetrafluoroethylene, ethylene, and a compound represented by the formula (1) described below is polymerized to produce a copolymer, wherein the purity of the compound represented by the formula (1) is 99.5% or more and the contents of each unit are within predetermined ranges, and thus have arrived at the present invention.

[0007] That is, the inventors have found that the above-mentioned problems can be solved by the following configurations. [1] A method for producing a copolymer, comprising polymerizing monomers containing tetrafluoroethylene, ethylene, and a compound represented by formula (1) described below to produce a copolymer, wherein the purity of the compound represented by formula (1) is 99.5% or higher, the total content of units based on the tetrafluoroethylene and units based on the ethylene is 80.0 to 99.5 mol % based on all units contained in the copolymer, and the content of units based on the compound represented by formula (1) is 0.5 to 3.5 mol % based on all units contained in the copolymer. [2] A method for producing the copolymer according to [1], comprising polymerizing monomers consisting only of tetrafluoroethylene, ethylene, and the compound represented by formula (1). [3] A method for producing the copolymer according to [1] or [2], wherein the melt flow rate of the copolymer, measured in accordance with ASTM D3159 at a temperature of 297°C and a load of 49 N, is 1 to 50 g / 10 min. [4] The method for producing a copolymer according to any one of [1] to [3], wherein the copolymer has a melting point of 244° C. to 280° C. [5] The compound represented by formula (1) is 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 CH２ =CF(CF ２ ) ３ [6] A method for producing the copolymer according to any one of [1] to [4], wherein in the compound represented by formula (1), X and two Z's are hydrogen atoms and Y is a fluorine atom. [7] A method for producing the copolymer according to any one of [1] to [6], wherein the polymerization of the monomers is solution polymerization. [8] A method for producing a molded article, comprising molding a molded article using the copolymer produced by the method for producing a copolymer according to any one of [1] to [7]. [9] A method for producing a molded article according to [8], wherein the molded article is molded by press molding or injection molding.

[0008] According to the present invention, there is provided a method for producing a copolymer that can produce a copolymer that shows little change in tensile strength before and after a heat aging test, has high tensile elongation, and has low oxygen permeability. Furthermore, according to the present invention, there is provided a method for producing a molded article.

[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 upper and lower limits. In the numerical ranges described in stages in this specification, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the examples.

[0010] The term "unit" refers collectively to an atomic group derived from one molecule of the monomer formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a portion of the atomic group. Hereinafter, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit." A "TFE unit" is a unit based on tetrafluoroethylene in the copolymer, and an "E unit" is a unit based on ethylene in the copolymer. An "A unit" is a unit based on the compound represented by formula (1) described below. In this specification, each component may be used alone or in combination with two or more substances corresponding to the component. When two or more substances are used in combination for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0011] [Method for Producing Copolymer] The method for producing a copolymer according to the present invention (hereinafter also referred to as "the present production method") is a method for producing a copolymer by polymerizing monomers containing tetrafluoroethylene, ethylene, and a compound represented by formula (1) (hereinafter also referred to as "compound (1)"), characterized in that the purity of compound (1) is 99.5% or more, the total content of TFE units and E units is 80.0 to 99.5 mol% based on all units contained in the copolymer, and the content of A units is 0.5 to 3.5 mol% based on all units contained in the copolymer.

[0012] This production method can produce copolymers that exhibit small changes in tensile strength before and after heat aging tests, large tensile elongation, and low oxygen permeability. The details of the reasons for this are not yet clear, but the following reasons are presumed to be the cause. In this specification, the rate of change in tensile strength before and after a heat aging test is evaluated by conducting a heat aging test on a molded article formed using the copolymer, and then conducting a tensile test before and after the heat aging test, based on the retention rate of the tensile strength measured after the test relative to the tensile strength measured before the test. One reason for the small change in tensile strength of the copolymer produced by this production method (hereinafter also referred to as "this copolymer") before and after the heat aging test is thought to be due to the use of compound (1) with a purity of 99.5% or higher in the polymerization step of this production method, in which monomers (tetrafluoroethylene, ethylene, compound (1), etc.) are polymerized. It is presumed that the use of such a highly pure compound (1) in the polymerization step can reduce the amount of impurities that have double bonds and inhibit radical migration. As a result, it is presumed that the polymerization rate was increased, the molecular weight of the copolymer produced was increased, and the decrease in tensile strength during heat aging tests was suppressed. Furthermore, it is presumed that the content of A units in this copolymer is 3.5 mol% or less relative to the total units contained in this copolymer, which increases the crystallinity of the copolymer and makes it difficult for oxygen to diffuse into the copolymer, thereby suppressing excessive oxygen permeation. Furthermore, it is presumed that the content of A units in this copolymer is 0.5 mol% or more relative to the total units contained in this copolymer, which reduces the force against deformation of molecular chains containing A units, thereby improving the tensile elongation of molded articles formed using the copolymer. Thus, it is presumed that by specifying the purity of compound (1) and the content of A units in the produced copolymer, a copolymer with excellent heat resistance, mechanical strength, and oxygen permeability was obtained. The production method will be described in more detail below.

[0013] The production method includes a polymerization step of polymerizing a monomer containing tetrafluoroethylene (TFE), ethylene, and a compound represented by the following formula (1) to produce a copolymer: ２ =CX(CF２ ) ｍ Y Formula (1) 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. Two Zs may be the same or different.

[0014] In this production method, by using compound (1) to produce a copolymer containing A units in addition to TFE units and E units, it is possible to produce a copolymer that not only shows a small change in tensile strength before and after a heat aging test and a large tensile elongation of a molded product, but also has excellent folding endurance and excellent high-speed wire moldability.

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

[0016] Compound (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] This production method is characterized in that the purity of compound (1) used in polymerization is 99.5% or more. As described above, by using a raw material monomer that is a compound with a structure different from that of formula (1) and has a small amount of impurities that inhibit polymerization to obtain the copolymer, it is possible to produce a copolymer that shows little change in tensile strength before and after heat aging resistance testing.

[0018] The purity of compound (1) is measured by gas chromatography (GC) using the following method: More specifically, the raw materials used in the copolymerization are measured using a GC apparatus such as a "GC-2025" (Shimadzu Corporation), and the ratio (percentage) of the peak area corresponding to compound (1) to the total area of ​​all peaks corresponding to the detected compounds is calculated from the obtained chart, and the calculated ratio is taken as the purity (percentage) of compound (1).

[0019] The purity of the compound (1) used in the polymerization may be 100.0%.

[0020] In this production method, the monomers used in the polymerization step may contain other monomers (hereinafter also referred to as "other monomers") in addition to TFE, ethylene, and compound (1). Specific examples of other monomers include fluoroolefins (vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, hexafluoroisobutylene, etc., excluding compound (1)); 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(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. In the present production method, it is preferred to produce a copolymer containing only TFE units, E units, and A units using monomers consisting of tetrafluoroethylene, ethylene, and compound (1).

[0021] The contents of TFE, ethylene, and compound (1) contained in the monomers used in polymerization are appropriately adjusted so that the TFE units, E units, and A units contained in the copolymer produced by this production method fall within the above-mentioned specified ranges. The total content of TFE and ethylene is 80.0 to 99.5 mol%, preferably 85 to 99.5 mol%, and more preferably 90 to 99.5 mol%, based on the total molar amount of monomers. The content of compound (1) is 0.5 to 3.5 mol%, preferably 0.6 to 3.2 mol%, and more preferably 0.6 to 3.0 mol%, based on the total molar amount of monomers. Furthermore, the content of TFE, the content of ethylene, and the content of other monomers contained in the monomers are preferably within the ranges described for the content of TFE units, the content of E units, and the content of units based on other monomers contained in the copolymer, respectively.

[0022] <Polymerization Method> In the polymerization step of the present production method, the polymerization method for polymerizing the monomers includes known methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., and among these, solution polymerization is preferred. In the polymerization step, in addition to the above-mentioned monomers, a polymerization initiator, a polymerization medium, a chain transfer agent, etc. can be used.

[0023] The polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100°C, more 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. 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 monomer used.

[0024] 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.

[0025] 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, and at least one selected from the group consisting of alcohols and hydrocarbons is more preferred, with alcohols being particularly preferred, due to their higher chain transfer constant and high stability of the end groups of the copolymer. Among alcohols, methanol or ethanol is particularly preferred. Among these, methanol is particularly preferred due to its 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.

[0026] From the viewpoint of heat resistance, the polymerization temperature is preferably 15 to 75°C, more preferably 15 to 60°C, even more preferably 20 to 58°C, and particularly preferably 25 to 55°C. If the polymerization temperature is 25°C or higher, the polymerizability is excellent. If the polymerization temperature is 75°C or lower, the melting point of the copolymer can be improved. The polymerization pressure is preferably 0.5 to 3.0 MPa, particularly preferably 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0027] [Copolymer] The copolymer produced by the production method of the present invention will now be described. The copolymer contains at least TFE units, E units, and A units.

[0028] In this copolymer, the total content of TFE units and E units is 80.0 to 99.5 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.

[0029] The content of A units is 0.5 to 3.5 mol% relative to all units contained in the copolymer. When the content of A units is 3.5 mol% or less relative to all units contained in the copolymer, the oxygen permeability of the copolymer is reduced. Furthermore, when the content of A units is 0.5 mol% or more relative to all units contained in the copolymer, the copolymer can be used to form a molded article with high tensile elongation and excellent folding endurance. From the viewpoint of achieving a well-balanced oxygen permeability of the copolymer, tensile elongation of the molded article, and folding endurance of the molded article, the content of A units is preferably 0.6 to 3.5 mol% relative to all units contained in the copolymer, more preferably 0.6 to 3.0 mol%, even more preferably 1.0 to 3.0 mol%, even more preferably 1.5 to 3.0 mol%, and particularly preferably 1.5 to 2.9 mol%. From the viewpoint of achieving even better oxygen permeability of the copolymer, the content of A units is preferably 1.4 mol% or more relative to all units contained in the copolymer, more preferably 1.7 mol% or more, and even more preferably 2.5 mol% or more. The content of A units is preferably 1.0 mol% or more, more preferably 1.5 mol% or more, and more preferably 3.3 mol% or less, and more preferably 3.0 mol% or less, based on the total units contained in the copolymer, from the viewpoint of obtaining a molded article with better tensile elongation. The content of A units is preferably 1.9 mol% or more, more preferably 2.1 mol% or more, based on the total units contained in the copolymer, from the viewpoint of obtaining a molded article with better folding resistance. The content of A units is preferably 1.0 mol% or more, more preferably 1.5 mol% or more, based on the total units contained in the copolymer, from the viewpoint of obtaining a molded article with better heat resistance.

[0030] The content of TFE units is preferably 40.0 to 63.0 mol%, more preferably 45.0 to 58.0 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.

[0031] 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 all units contained in the copolymer. If the content is equal to or greater than the lower limit, the molded article will have better mechanical properties, and if it is equal to or less than the upper limit, the molded article will have better heat resistance. From the viewpoint of achieving better oxygen permeability, the content of E units is preferably 44.4 mol% or less, based on all units contained in the copolymer, and more preferably 44.2 mol% or less. From the viewpoint of achieving better folding endurance, the content of E units is preferably 45.9 mol% or less, based on all units contained in the copolymer, and more preferably 44.4 mol% or less.

[0032] When the copolymer contains units derived from other monomers, the content of the units derived from other monomers is preferably 2.0 mol% or less, more preferably 1.0 mol% or less, based on the total units contained in the copolymer.The copolymer preferably comprises TFE units, E units and A units, and does not contain units derived from other monomers.

[0033] <Physical Properties of Copolymer> (Melt Flow Rate) The melt flow rate (hereinafter also referred to as "MFR") of the present copolymer is preferably 1 g / 10 min or more, more preferably 2 g / 10 min or more, and even more preferably 3 g / 10 min or more, from the viewpoint of superior high-speed wire moldability of the copolymer, and is preferably 45 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, and particularly preferably 10 g / 10 min or less. Furthermore, from the viewpoint of being able to form a molded article having excellent folding resistance, the MFR of the present copolymer is preferably 50 g / 10 min or less, preferably 48 g / 10 min or less, and more preferably 47 g / 10 min or less. The MFR of the present copolymer is preferably 1 to 50 g / 10 min, more preferably 2 to 48 g / 10 min, and even more preferably 3 to 47 g / 10 min, from the viewpoint of a well-balanced excellent high-speed wire moldability and folding resistance of the molded article.

[0034] The MFR of a copolymer means the mass of the copolymer flowing out of an orifice having a diameter of 2 mm and a length of 8 mm in 10 minutes, measured under conditions of a temperature of 297° C. and a load of 49 N in accordance with ASTM D3159.

[0035] (Melting Point) The melting point of the present copolymer is preferably 244°C or higher, more preferably 245°C or higher, even more preferably 248°C or higher, and particularly preferably 249°C or higher, from the viewpoint of superior crack resistance. 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. The melting point of the present copolymer is preferably 244°C to 280°C, more preferably 244°C to 270°C, and even more preferably 245°C to 270°C, from the viewpoint of a well-balanced excellent crack resistance and moldability of the present copolymer. The melting point of the present copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter.

[0036] <Uses of the Copolymer> The present copolymer is preferably used for molding a molded article. By molding the present copolymer, a molded article can be obtained that shows little change in tensile strength before and after a heat aging test, has high tensile elongation, and has low oxygen permeability.

[0037] [Method for producing a molded article] A method for producing a molded article using the present copolymer will be described in detail. The method for producing a molded article is characterized by molding a molded article using the present copolymer. Specific examples of 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 an injection-molded article with a beautiful appearance without corroding the mold used for molding.

[0038] In the method for producing a molded article, the present copolymer may be molded, or a composition containing the present copolymer may be molded. By molding a composition containing the present copolymer, a molded article can be produced that shows little change in tensile strength before and after a heat aging test, has high tensile elongation, and has low oxygen permeability.

[0039] The composition may contain components other than the present copolymer. Specific examples of such components include resins other than the present copolymer, heat stabilizers, antioxidants, colorants, UV absorbers, fillers, crosslinking agents, crosslinking aids, and organic peroxides. The content of the present copolymer in the composition is preferably 50% by mass or more but less than 100% by mass, more preferably 70% by mass or more but less than 100% by mass, and particularly preferably 90% by mass or more but less than 100% by mass, relative to the total mass of the composition. When the 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, relative to 100 parts by mass of the present copolymer in the composition. Examples of methods for producing the composition include melt-kneading the present copolymer and other components, if necessary, using a known method.

[0040] [Molded Article] Specific examples of molded articles produced using the present copolymer 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.

[0041] The present copolymer, a composition containing the present copolymer, or the above-mentioned molded article can be used for the following purposes. Fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in food manufacturing processes; chemical liquid transfer components, such as chemical stoppers, packaging films, lining materials, packings, sealing materials, and sheets for fluid transfer lines used in chemical manufacturing processes; inner lining components for chemical liquid tanks and piping in chemical plants or semiconductor factories; fuel transfer components, such as O-rings, tubes, packings, valve core materials, hoses, and sealing materials used in automotive fuel systems and peripheral devices, and hoses and sealing materials used in automotive automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automotive engines and peripheral devices, as well as other automotive components, such as automotive brake hoses, air conditioner hoses, radiator hoses, and wire coating materials; chemical liquid transfer components for semiconductor manufacturing equipment, such as O-rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and fittings; coating and ink components such as paint rolls, hoses, tubes, and ink containers for coating equipment; food and beverage transport components such as tubes, hoses, belts, packing, and joints, such as food and beverage tubes or food and beverage hoses, food packaging materials, and glass cooking equipment; waste liquid transport components such as tubes and hoses for transporting waste liquid; high-temperature liquid transport components such as tubes and hoses for transporting high-temperature liquids; steam piping components such as tubes and hoses for steam piping; anti-corrosion tapes for piping, such as tapes wrapped around piping on ship decks, etc.; various coating materials such as electric wire coating materials, optical fiber coating materials, and transparent surface coating materials and backing agents applied to the light-incident surface of photovoltaic elements in solar cells; sliding components such as diaphragms and various packings for diaphragm pumps; agricultural films, carrier films for fuel cells, and weather-resistant covers for various roofing materials and side walls, etc.; interior materials used in the construction field, and glass coating materials such as non-flammable fire-resistant safety glass; lining materials such as laminated steel sheets used in home appliances, etc.Among these, the molded article is particularly suitable for use as a chemical liquid transport member and a coating material for semiconductor devices, since it shows little change in tensile strength before and after a heat aging test, has high tensile elongation, and has low oxygen permeability.

[0042] The present invention will be described in detail below with reference to examples. Examples 1 to 11 and Examples 25 and 26 are working examples, and Examples 12 to 24 are comparative examples. However, the present invention is not limited to these examples. Various measurement methods and evaluation methods are as follows.

[0043] [Measurement] <Purity of Compound> The purity of Compound (1) used in the production of the copolymer in each example and PPVE described later were measured by the method described above using an apparatus equipped with a gas chromatograph (GC) and a detector (trade name "GC-2025", manufactured by Shimadzu Corporation).

[0044] <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 and １３ Calculated by C-NMR measurement.

[0045] <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).

[0046] <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).

[0047] [Evaluation Tests] <Film Forming> The copolymers obtained in each example were 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 films with thicknesses of 0.1 mm, 0.23 mm, and 1 mm. The press-molding was carried out using a heated press ("SA-301" manufactured by Tester Sangyo Co., Ltd.).

[0048] <Heat Resistance (Rate of Change in Tensile Strength Before and After Heat Aging Test)> 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 obtained test piece was pulled using a Strograph (manufactured by Toyo Seiki Seisaku-Sho, Ltd.) under conditions of a gauge length of 20 mm and a pulling speed of 200 mm / min in a constant temperature and humidity environment controlled at a temperature of 23±2°C and a humidity of 50%±10%, to measure the tensile strength (unit: MPa) before the heat aging test.

[0049] The above test pieces were placed in a gear oven (forced circulation air heat aging tester) (manufactured by Toyo Seiki Seisakusho, Ltd.) and subjected to heat exposure treatment. The heat exposure treatment was performed at a temperature of 250°C, and the heat treatment was performed for 40 hours after placement. The heat-treated test pieces were subjected to a tensile test according to the above method, and the tensile strength (unit: MPa) after the heat aging test was measured. The rate of change in tensile strength due to the heat aging test (unit: %) was calculated from the ratio of the tensile strength after the heat aging test to the tensile strength before the heat aging test. The heat resistance of each film was evaluated based on the calculated rate of change in tensile strength according to the following evaluation criteria. (Evaluation criteria for heat resistance) ○: The rate of change in tensile strength before and after the heat aging test was 45% or more ×: The rate of change in tensile strength before and after the heat aging test was less than 45%

[0050] <Folding Endurance> A folding fatigue test was conducted according to the MIT method, which is known as a method for evaluating stress crack resistance, in accordance with ASTM D2176. First, a rectangular test piece having a width of 12.5 mm and a length of 130 mm was cut out from the obtained film having a thickness of 0.23 mm. The obtained test piece was attached to an MIT folding fatigue tester (manufactured by Toyo Seiki Seisakusho, 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. The folding endurance of each film was evaluated based on the measured folding endurance number according to the following evaluation criteria. A higher folding endurance number indicates better folding endurance. (Evaluation criteria for folding endurance) ○: 40,000 or more folding endurances ×: Less than 40,000 folding endurances

[0051] <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 ２ 24h atm)) = GTR x d GTR: oxygen permeability (cm ３ / (m ２ 24h atm) d: Film thickness (mm) From the obtained oxygen permeability coefficient, the oxygen permeability of each film was evaluated based on the following evaluation criteria. (Evaluation criteria for oxygen permeability) ○: Oxygen permeability coefficient is 4.5 or less ×: Oxygen permeability coefficient is more than 4.5

[0052] <Tensile elongation> Dumbbell-shaped test pieces as specified in JIS K6301 No. 3 were cut out from the obtained 1 mm thick film. The obtained test pieces were pulled in a constant temperature and humidity environment controlled at a temperature of 23±2°C and a humidity of 50%±10% using a Strograph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) under conditions of a gauge length of 20 mm and a pulling speed of 200 mm / min, to measure the tensile elongation (unit: %). From the measured tensile elongation, the tensile elongation of each film was evaluated based on the following evaluation criteria. (Evaluation criteria for tensile elongation) ○: Tensile elongation is 400% or more ×: Tensile elongation is less than 400%

[0053] <High-Speed ​​Wire Formability> An orifice with a diameter of 1 mm and a length of 10 mm was set in a melt flowability measuring device "Capilograph (registered trademark)" (manufactured by Toyo Seiki Seisakusho, Ltd.), and the temperature of the cylinder of the measuring device was set to 320°C. The copolymer obtained in each example was filled into the cylinder of the measuring device and melted. The molten copolymer was extruded at a piston speed of 10 mm / min, and a strand extruded from the orifice was taken up using a roller. The take-up speed was gradually increased from 5 m / min to 200 m / min, and the maximum melt tension measured until the strand was broken was defined as the maximum melt tension (mN), and the take-up speed at which the strand was broken was defined as the maximum take-up speed (m / min). It can be said that the higher the maximum take-up speed, the better the high-speed wire formability. Furthermore, the upper limit of the take-up speed condition is 200 m / min due to the specifications of the machine. When the maximum take-up speed is the same, it can be said that the lower the ratio of the maximum melt tension to the maximum take-up speed, the better the high-speed wire formability. The high-speed wire formability of each copolymer was evaluated based on the measured maximum melt tension and maximum take-up speed, according to the following evaluation criteria: (Evaluation criteria for high-speed wire formability) ○: Maximum take-up speed was 200 m / min, and the ratio (maximum melt tension / maximum take-up speed) was less than 0.08. ×: Maximum take-up speed was less than 200 m / min, or (maximum melt tension / maximum take-up speed) was 0.08 or more.

[0054] [Example 1] Fluorine-based organic solvent (manufactured by AGC Inc., "ASAHIKLIN (registered trademark) AE-3000", CF ３ CH ２OCF ２ CF ２ H) 1,167g and CH ２ =CH(CF ２ ) ４ 1.0 g of F(PFBE) and 8.4 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 solution in this polymerization vessel was heated to 72°C (polymerization temperature), and 180 g of a mixed gas of TFE / ethylene = 88 / 12 (molar ratio) was charged, and then the pressure in the polymerization vessel was increased to 1.5 MPa [gauge]. Initially, 2.0 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 0.6 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 90 g, to obtain Copolymer 1 of Example 1. The composition of Copolymer 1 was TFE unit / E unit / PFBE unit (molar ratio) = 53.4 / 46.0 / 0.6. The "PFBE unit" refers to the CH ２ =CH(CF ２ ) ４ The copolymer 1 had an MFR of 7 g / 10 min and a melting point of 268°C.

[0055] When producing the copolymer, the purified PFBE obtained by distillation purification was used as the raw material for polymerization of the copolymer. More specifically, a commercially available PFBE (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a distillation apparatus, heated, and the initial fraction distilled from the start of distillation until the ratio of the total amount of the distilled fraction to the charged amount (hereinafter also referred to as the "distillation rate") reached 8.1% by mass was discarded. When the distillation rate reached 8.1% by mass, the recovery of the main fraction was started. Next, when the distillation rate reached 90.0% by mass, the recovery of the main fraction was terminated. The purity of the purified PFBE obtained as the main fraction was measured by the above method, and the purity of PFBE was 99.5%.

[0056] [Example 2] Copolymer 2 of Example 2 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 1.5 g, the amount of methanol was changed to 13.0 g, the amount of polymerization initiator solution initially charged was changed to 3.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.7 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 2 was TFE unit / E unit / PFBE unit (molar ratio) = 53.2 / 46.1 / 0.7. The MFR of copolymer 2 was 23 g / 10 min and the melting point was 267 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 8.8% by mass to the time when it reached 90.1% by mass was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.6%.

[0057] [Example 3] Copolymer 3 of Example 3 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 3.9 g, the amount of methanol was changed to 7.4 g, the amount of polymerization initiator solution initially charged was changed to 3.0 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. The composition of copolymer 3 was TFE unit / E unit / PFBE unit (molar ratio) = 53.7 / 45.1 / 1.2. The MFR of copolymer 3 was 5 g / 10 min and the melting point was 262 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 10.9 mass% to the time when it reached 90.4 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.9%.

[0058] [Example 4] Copolymer 4 of Example 4 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 3.4 g, the amount of methanol was changed to 12.8 g, the amount of polymerization initiator solution initially charged was changed to 3.0 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. The composition of copolymer 4 was TFE unit / E unit / PFBE unit (molar ratio) = 54.1 / 44.8 / 1.1. The MFR of copolymer 4 was 22 g / 10 min and the melting point was 263 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 10.2 mass% to the time when it reached 90.3 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.8%.

[0059] [Example 5] Copolymer 5 of Example 5 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 4.4 g, the amount of methanol was changed to 6.1 g, the amount of polymerization initiator solution initially charged was changed to 5.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.3 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 5 was TFE unit / E unit / PFBE unit (molar ratio) = 54.1 / 44.6 / 1.3. The MFR of copolymer 5 was 13 g / 10 min and the melting point was 261 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 10.2 mass% to the time when it reached 90.3 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.8%.

[0060] [Example 6] Copolymer 6 of Example 6 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 5.9 g, the amount of methanol was changed to 6.8 g, the amount of polymerization initiator solution initially charged was changed to 5.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.6 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 6 was TFE unit / E unit / PFBE unit (molar ratio) = 53.9 / 44.5 / 1.6. The MFR of copolymer 6 was 17 g / 10 min and the melting point was 258 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5 mass% to the time when it reached 90.2 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0061] [Example 7] The amount of PFBE initially charged into the polymerization vessel was changed to 5.9 g, the amount of methanol to 10.5 g, the amount of polymerization initiator solution initially charged to 5.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.6 mol% relative to the total moles of TFE and ethylene. Except for this, copolymer 7 of Example 7 was obtained in the same manner as in Example 1. The composition of copolymer 7 was TFE unit / E unit / PFBE unit (molar ratio) = 53.6 / 44.8 / 1.6. The MFR of copolymer 7 was 46 g / 10 min and the melting point was 258 ° C. As in Example 1, the fraction distilled from the time when the distillate ratio reached 8.1 mass% to the time when it reached 90.0 mass% was recovered as the main fraction, and the recovered purified PFBE was used for polymerization. The purity of the purified PFBE was 99.5%.

[0062] [Example 8] Copolymer 8 of Example 8 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 6.8 g, the amount of methanol was changed to 5.3 g, the amount of polymerization initiator solution initially charged was changed to 6.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.8 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) = 53.6 / 44.6 / 1.8. The MFR of copolymer 8 was 10 g / 10 min and the melting point was 256 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 8.8 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.6%.

[0063] [Example 9] Copolymer 9 of Example 9 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 9.2 g, the amount of methanol was changed to 5.0 g, the amount of polymerization initiator solution initially charged was changed to 8.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 2.3 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) = 53.4 / 44.3 / 2.3. The MFR of copolymer 9 was 8 g / 10 min and the melting point was 251 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5 mass% to the time when it reached 90.2 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0064] [Example 10] Copolymer 10 of Example 10 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 11.2 g, the amount of methanol was changed to 6.4 g, the amount of polymerization initiator solution initially charged was changed to 8.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 2.7 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 10 was TFE unit / E unit / PFBE unit (molar ratio) = 53.9 / 43.4 / 2.7. The MFR of copolymer 10 was 18 g / 10 min and the melting point was 246 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 10.9 mass% to the time when it reached 90.4 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.9%.

[0065] [Example 11] The amount of PFBE initially charged into the polymerization vessel was changed to 12.1 g, the amount of methanol to 5.9 g, the amount of polymerization initiator solution initially charged to 10.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 2.9 mol% relative to the total moles of TFE and ethylene. Copolymer 11 of Example 11 was obtained in the same manner as in Example 1. The composition of copolymer 11 was TFE unit / E unit / PFBE unit (molar ratio) = 53.0 / 44.1 / 2.9. The MFR of copolymer 11 was 14 g / 10 min and the melting point was 244 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5% by mass to the time when it reached 90.2% by mass was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0066] [Example 12] 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 ２42.7 g of )2F(PPVE) and 7.9 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]. 2.9 mL of a polymerization initiator solution prepared by dissolving tert-butyl peroxypivalate in AE-3000 at a concentration of 1% by mass was initially 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 90 g, to obtain Copolymer 12 of Example 12. The composition of Copolymer 12 was TFE unit / E unit / PPVE unit (molar ratio) = 50.6 / 48.4 / 1.0. The "PPVE unit" refers to the CF of each copolymer. ２ = CFO (CF ２ )2F. The copolymer 12 had an MFR of 6 g / 10 min and a melting point of 271°C.

[0067] When producing the copolymer, the purified PPVE obtained by distillation purification was used as the copolymer raw material for polymerization. More specifically, a commercially available PPVE (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a distillation apparatus, heated, and the initial fraction distilled until the distillate ratio reached 8.5% by mass was discarded. When the distillate ratio reached 8.5% by mass, recovery of the main fraction was started. Next, when the distillate ratio reached 90.1% by mass, recovery of the main fraction was stopped. The purity of the purified PPVE obtained as the main fraction was measured by the above method, and the purity of the PPVE was 99.6%.

[0068] [Example 13] Copolymer 13 of Example 13 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 42.8 g and the amount of methanol was changed to 12.4 g. The composition of copolymer 13 was TFE unit / E unit / PPVE unit (molar ratio) = 50.6 / 48.4 / 1.0. The MFR of copolymer 13 was 20 g / 10 min and the melting point was 271 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.6 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.7%.

[0069] [Example 14] Copolymer 14 of Example 14 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 67.2 g, the amount of methanol was changed to 4.7 g, the amount of polymerization initiator solution initially charged was changed to 5.3 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 1.6 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 14 was TFE unit / E unit / PPVE unit (molar ratio) = 50.3 / 48.1 / 1.6. The MFR of copolymer 14 was 7 g / 10 min and the melting point was 265 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 9.5 mass% to the time when it reached 90.2 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.3%.

[0070] [Example 15] Copolymer 15 of Example 15 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 67.2 g, the amount of methanol was changed to 5.8 g, the amount of polymerization initiator solution initially charged was changed to 5.3 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount equivalent to 1.6 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 15 was TFE unit / E unit / PPVE unit (molar ratio) = 50.2 / 48.2 / 1.6. The MFR of copolymer 15 was 12 g / 10 min and the melting point was 265 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 9.2 mass% to the time when it reached 90.2 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.5%.

[0071] [Example 16] Copolymer 16 of Example 16 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 67.2 g, the amount of methanol was changed to 9.0 g, the amount of polymerization initiator solution initially charged was changed to 5.3 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 1.6 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 16 was TFE unit / E unit / PPVE unit (molar ratio) = 50.2 / 48.2 / 1.6. The MFR of copolymer 16 was 27 g / 10 min and the melting point was 265 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.7 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.4%.

[0072] [Example 17] Copolymer 17 of Example 17 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 87.2 g, the amount of methanol was changed to 6.0 g, the amount of polymerization initiator solution initially charged was changed to 7.3 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 2.1 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 17 was TFE unit / E unit / PPVE unit (molar ratio) = 49.9 / 48.0 / 2.1. The MFR of copolymer 17 was 10 g / 10 min and the melting point was 260 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.8 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.3%.

[0073] [Example 18] Copolymer 18 of Example 18 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 91.0 g, the amount of methanol was changed to 6.8 g, the amount of polymerization initiator solution initially charged was changed to 7.7 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 2.2 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 18 was TFE unit / E unit / PPVE unit (molar ratio) = 49.9 / 47.9 / 2.2. The MFR of copolymer 18 was 17 g / 10 min and the melting point was 259 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.6 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.8%.

[0074] [Example 19] Copolymer 19 of Example 19 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged to the polymerization vessel was changed to 42.8 g and the amount of methanol was changed to 10.5 g. The composition of copolymer 19 was TFE unit / E unit / PPVE unit (molar ratio) = 50.6 / 48.4 / 1.0. The MFR of copolymer 19 was 12 g / 10 min and the melting point was 271 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.4 mass% to the time when it reached 90.0 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.6%.

[0075] [Example 20] Copolymer 20 of Example 20 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 98.7 g, the amount of methanol was changed to 5.8 g, the amount of polymerization initiator solution initially charged was changed to 8.5 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 2.4 mol% relative to the total number of moles of TFE and ethylene. The composition of copolymer 20 was TFE unit / E unit / PPVE unit (molar ratio) = 49.8 / 47.8 / 2.4. The MFR of copolymer 20 was 15 g / 10 min and the melting point was 257 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.5 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified PPVE was used for polymerization. The purity of the purified PPVE was 99.7%.

[0076] [Example 21] Copolymer 21 of Example 21 was obtained in the same manner as in Example 12, except that the amount of PPVE initially charged into the polymerization vessel was changed to 110.1 g, the amount of methanol was changed to 6.3 g, the amount of polymerization initiator solution initially charged was changed to 9.7 mL, and the amount of PPVE continuously charged during polymerization was changed to an amount corresponding to 2.7 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 21 was TFE unit / E unit / PPVE unit (molar ratio) = 49.6 / 47.7 / 2.7. The MFR of copolymer 21 was 19 g / 10 min, and the melting point was 253 ° C. PPVE was purified by distillation in the same manner as in Example 12, except that the fraction distilled from the time when the distillate ratio reached 8.6 mass% to the time when it reached 90.1 mass% was recovered as the main fraction, and the purified Yochishima sPPVE was used for polymerization. The purity of the purified PPVE was 99.6%.

[0077] [Example 22] The purity of PFBE when initially charged into the polymerization vessel was changed to 99.0%, the amount of PFBE to 9.2 g, the amount of methanol to 10.5 g, the amount of polymerization initiator solution initially charged to 5.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.6 mol% relative to the total moles of TFE and ethylene. Copolymer 22 of Example 22 was obtained in the same manner as in Example 1. The composition of copolymer 22 was TFE unit / E unit / PFBE unit (molar ratio) = 54.1 / 44.3 / 1.6. The MFR of copolymer 22 was 95 g / 10 min and the melting point was 258 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5% by mass to the time when it reached 90.2% by mass was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.0%.

[0078] [Example 23] Copolymer 23 of Example 23 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 16.0 g, the amount of methanol was changed to 4.3 g, the amount of polymerization initiator solution initially charged was changed to 12.0 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 23 was TFE unit / E unit / PFBE unit (molar ratio) = 53.3 / 43.0 / 3.7. The MFR of copolymer 23 was 4 g / 10 min and the melting point was 236 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5% by mass to the time when it reached 90.2% by mass was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0079] [Example 24] Copolymer 24 of Example 24 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 0.43 g, the amount of methanol was changed to 8.4 g, the amount of polymerization initiator solution initially charged was changed to 2.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 0.3 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 24 was TFE unit / E unit / PFBE unit (molar ratio) = 53.5 / 46.2 / 0.3. The MFR of copolymer 24 was 7 g / 10 min and the melting point was 271 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 10.2 mass% to the time when it reached 90.3 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.8%.

[0080] [Example 25] Copolymer 25 of Example 25 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 5.9 g, the amount of methanol was changed to 18.1 g, the amount of polymerization initiator solution initially charged was changed to 5.0 mL, and the amount of PFBE continuously charged during polymerization was changed to an amount equivalent to 1.6 mol% relative to the total moles of TFE and ethylene. The composition of copolymer 25 was TFE unit / E unit / PFBE unit (molar ratio) = 53.6 / 44.8 / 1.6. The MFR of copolymer 25 was 56 g / 10 min and the melting point was 258 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5 mass% to the time when it reached 90.2 mass% was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0081] [Example 26] Copolymer 26 of Example 26 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 3.9 g, the amount of methanol was changed to 3.2 g, the amount of polymerization initiator solution initially charged was changed to 3.0 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. The composition of copolymer 26 was TFE unit / E unit / PFBE unit (molar ratio) = 54.2 / 44.6 / 1.2. The MFR of copolymer 26 was 0.4 g / 10 min and the melting point was 262 ° C. PFBE was purified by distillation in the same manner as in Example 1, except that the fraction distilled from the time when the distillate ratio reached 9.5% by mass until the time when it reached 90.2% by mass was recovered as the main fraction, and the purified PFBE was used for polymerization. The purity of the purified PFBE was 99.7%.

[0082] Tables 1 to 3 show the raw materials used in the polymerization in each example, the composition and physical properties of the copolymer in each example, and the results of each evaluation test. In the tables, the "Third Monomer" column shows the type of monomer copolymerized with TFE and ethylene (hereinafter also referred to as "third monomer"), the purity of the third monomer used in the polymerization, and the distillate yield at the start of recovery as the main fraction during distillation purification. The "TFE (mol %)" column shows the content (unit: mol %) of TFE units relative to all units contained in the copolymer. The "E (mol %)" column shows the content (unit: mol %) of E units relative to all units contained in the copolymer. The "Third Monomer (mol %)" column shows the content (unit: mol %) of PFBE units or PPVE units relative to all units contained in the copolymer. The "TFE + E (mol %)" column shows the total content (unit: mol %) of TFE units and E units relative to all units contained in the copolymer.

[0083]

[0084]

[0085]

[0086] As shown in Tables 1 to 3, it was confirmed that copolymers having a small change in tensile strength before and after a heat aging test, a large tensile elongation, and low oxygen permeability can be produced by a copolymer production method in which a monomer containing TFE, ethylene, and compound (1) is polymerized to produce a copolymer, wherein the purity of compound (1) is 99.5% or more, the total content of TFE units and E units is 80.0 to 99.5 mol% based on all units contained in the copolymer, and the content of units based on compound (1) (A units) is 0.5 to 3.5 mol% based on all units contained in the copolymer (Examples 1 to 11 and 25 to 26).

[0087] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-144360, filed on August 26, 2024, are incorporated herein by reference as part of the disclosure of the present invention.

Claims

1. A method for producing a copolymer by polymerizing monomers containing tetrafluoroethylene, ethylene, and a compound represented by formula (1), wherein the purity of the compound represented by formula (1) is 99.5% or higher, the total content of units based on tetrafluoroethylene and units based on ethylene is 80.0 to 99.5 mol% based on all units contained in the copolymer, and the content of units based on the compound represented by formula (1) is 0.5 to 3.5 mol% based on all units contained in the copolymer. CZ ２ =CX(CF ２ ) ｍ Y Formula (1) 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. Two Zs may be the same or different.

2. A method for producing the copolymer according to claim 1, wherein the copolymer is produced by polymerizing monomers consisting only of tetrafluoroethylene, ethylene, and the compound represented by formula (1).

3. The method for producing the copolymer according to claim 1, wherein the melt flow rate of the copolymer measured in accordance with ASTM D3159 at a temperature of 297°C and a load of 49 N is 1 to 50 g / 10 min.

4. The method for producing the copolymer according to claim 1, wherein the melting point of the copolymer is 244°C to 280°C.

5. The compound represented by formula (1) is 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 The method for producing the copolymer according to claim 1, wherein the copolymer is H.

6. The method for producing a copolymer according to claim 1, wherein in the compound represented by formula (1), X and two Zs are hydrogen atoms, and Y is a fluorine atom.

7. The method for producing the copolymer according to claim 1, wherein the polymerization of the monomers is solution polymerization.

8. A method for producing a molded article, comprising molding a molded article using a copolymer produced by the method for producing a copolymer according to any one of claims 1 to 7.

9. The method for producing a molded article according to claim 8, wherein the molded article is formed by press molding or injection molding.

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