Method for producing aqueous fluoropolymer dispersion, and aqueous fluoropolymer dispersion

Abstract

The present invention provides a method for producing an aqueous fluoropolymer dispersion, wherein: a fluoromonomer is polymerized in an aqueous medium in the presence of a polymer (I) that contains a polymerization unit (I) based on a monomer (I) represented by general formula (I) CX1X3=CX2R(-CZ1Z2-A0)m, thereby obtaining a polymerization dispersion liquid that contains a fluoropolymer (excluding the polymer (I)), the polymer (I), and the aqueous medium; subsequently, the polymerization dispersion liquid, a nonionic surfactant, and a fluorine-free water-soluble electrolyte are mixed with each other so as to prepare a pre-concentration composition; and an aqueous dispersion which contains the fluoropolymer is obtained by concentrating of the pre-concentration composition.

Description

Method for producing aqueous fluoropolymer dispersion and aqueous fluoropolymer dispersion

[0001] The present disclosure relates to a method for producing an aqueous fluoropolymer dispersion and to an aqueous fluoropolymer dispersion.

[0002] Patent Document 1 describes a method for producing an aqueous fluoropolymer dispersion, which comprises concentrating a composition containing a polymer (I) containing polymerized units (I) based on a monomer (I) represented by general formula (I), a fluoropolymer (excluding the polymer (I)), a nonionic surfactant, a fluorine-free anionic surfactant, and an aqueous medium to obtain an aqueous dispersion containing the fluoropolymer. １ X ３ =CX ２ R (-CZ １ Z ２ -A ０ ) ｍ (I) (wherein, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

[0003] International Publication No. 2022 / 191286

[0004] An object of the present disclosure is to provide a method for producing an aqueous fluoropolymer dispersion that can rapidly increase the concentration of a fluoropolymer in a composition containing a fluoropolymer, a specific polymer, and an aqueous medium.

[0005] According to the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion, which comprises polymerizing a fluoromonomer in an aqueous medium in the presence of a polymer (I) comprising polymerized units (I) based on a monomer (I) represented by general formula (I) to obtain a polymer dispersion containing a fluoropolymer (excluding the polymer (I)), the polymer (I), and an aqueous medium, then mixing the polymer dispersion, a nonionic surfactant, and a fluorine-free water-soluble electrolyte to prepare a pre-concentration composition, and concentrating the pre-concentration composition to obtain an aqueous dispersion containing the fluoropolymer. １ X ３ =CX ２ R (-CZ １ Z ２ -A ０ ) ｍ (I) (wherein, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

[0006] According to the present disclosure, it is possible to provide a method for producing an aqueous fluoropolymer dispersion that can rapidly increase the concentration of a fluoropolymer in a composition containing a fluoropolymer, a specific polymer, and an aqueous medium.

[0007] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0008] In the present disclosure, fluororesins are partially crystalline fluoropolymers, or fluoroplastics. Fluororesins have a melting point and are thermoplastic, but may be melt-processable or non-melt-processable.

[0009] In the present disclosure, melt-processable means that the polymer can be melted and processed using conventional processing equipment such as an extruder, an injection molding machine, etc. Therefore, melt-processable fluororesins usually have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0010] In this disclosure, fluororubber refers to an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) appearing in differential scanning calorimetry (DSC) (heating rate 10°C / min) or differential thermal analysis (DTA) (heating rate 10°C / min) of the fluoropolymer is 4.5 J / g or less. Fluororubber exhibits elastomeric properties through crosslinking. Elastomeric properties refer to the ability of a polymer to be stretched and to retain its original length when the force required to stretch the polymer is no longer applied.

[0011] In the present disclosure, the partially fluorinated rubber is a fluoropolymer that contains fluoromonomer units and has a perfluoromonomer unit content of less than 90 mol% relative to all polymerized units, and has a glass transition temperature of 20°C or less and a melting peak (ΔH) magnitude of 4.5 J / g or less.

[0012] In the present disclosure, perfluororubber (perfluoroelastomer) is a fluoropolymer having a perfluoromonomer unit content of 90 mol% or more, preferably 91 mol% or more, relative to all polymerized units, a glass transition temperature of 20°C or less, a melting peak (ΔH) magnitude of 4.5 J / g or less, and a fluorine atom concentration of 71 mass% or more, preferably 71.5 mass% or more. In the present disclosure, the fluorine atom concentration in the fluoropolymer is determined by calculation of the concentration (mass%) of fluorine atoms in the fluoropolymer from the type and content of each monomer constituting the fluoropolymer.

[0013] In the present disclosure, a perfluoromonomer is a monomer that does not contain a carbon atom-hydrogen atom bond in the molecule. The perfluoromonomer may be a monomer containing carbon atoms and fluorine atoms, or a monomer in which some of the fluorine atoms bonded to carbon atoms have been substituted with chlorine atoms, or may contain nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, boron atoms, or silicon atoms in addition to carbon atoms. The perfluoromonomer is preferably a monomer in which all hydrogen atoms have been substituted with fluorine atoms. The perfluoromonomer does not include monomers that provide crosslinking sites.

[0014] The monomer that provides a crosslinking site is a monomer (cure site monomer) having a crosslinkable group that provides a crosslinking site to the fluoropolymer for forming a crosslink with a curing agent.

[0015] In the present disclosure, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer having a content of tetrafluoroethylene units relative to all polymer units of 99 mol % or more.

[0016] In the present disclosure, both the fluororesin (excluding polytetrafluoroethylene) and the fluororubber are preferably fluoropolymers having a tetrafluoroethylene unit content of less than 99 mol% relative to all polymerized units.

[0017] In the present disclosure, the content of each monomer constituting the fluoropolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0018] In the present disclosure, the term "organic group" refers to a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. The organic group is preferably an alkyl group which may have one or more substituents.

[0019] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (eg, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0020] In this disclosure, the term "at least 1" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0021] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0022] In the production method of the present disclosure, a fluoromonomer is polymerized in the presence of polymer (I) to obtain a polymer dispersion, and then the polymer dispersion, a nonionic surfactant, and a fluorine-free water-soluble electrolyte are mixed to prepare a pre-concentration composition, and the pre-concentration composition is concentrated to obtain an aqueous dispersion containing a fluoropolymer.

[0023] In relation to a technique for concentrating a composition containing polymer (I), Patent Document 1 describes that the concentration of the fluoropolymer can be rapidly increased by concentrating a composition containing polymer (I), a fluoropolymer, and an aqueous medium in the presence of a nonionic surfactant and a fluorine-free anionic surfactant in the composition.

[0024] In the present disclosure, a composition containing polymer (I), a fluoropolymer, and an aqueous medium is concentrated in the presence of a nonionic surfactant and a fluorine-free water-soluble electrolyte in the composition. This concentration method allows the concentration of the fluoropolymer to be rapidly increased. In addition, the pH of the resulting aqueous fluoropolymer dispersion is resistant to decrease even after long-term storage.

[0025] (Fluorine-free water-soluble electrolyte) The fluorine-free water-soluble electrolyte is a compound that does not contain fluorine atoms and dissolves in water to ionize into cations and anions. The fluorine-free water-soluble electrolyte may be an organic compound or an inorganic compound. The fluorine-free water-soluble electrolyte has a water solubility such that, for example, 1 g or more of the electrolyte dissolves in 100 g of water at 25°C.

[0026] The fluorine-free water-soluble electrolyte used in the production method of the present disclosure does not have surface activity. In one embodiment, the surface tension of a 0.1 mass % aqueous solution of the fluorine-free water-soluble electrolyte is greater than 60 mN / m. The surface tension of the fluorine-free water-soluble electrolyte can be measured by the Wilhelmy method at 25°C.

[0027] The fluorine-free water-soluble electrolyte is preferably at least one selected from the group consisting of acids and salts thereof, more preferably at least one selected from the group consisting of monovalent to trivalent acids and salts thereof, and even more preferably at least one selected from the group consisting of divalent to trivalent acids and salts thereof.

[0028] Examples of cations constituting the salt include metal ions such as sodium and potassium, and non-metal ions such as ammonium ions. Non-metal ions are preferred, and ammonium ions are more preferred, as this allows for avoiding the inclusion of metals in the aqueous fluoropolymer dispersion.

[0029] The fluorine-free water-soluble electrolyte is more preferably at least one selected from the group consisting of carbonic acid, carbonates, sulfuric acid, sulfates, oxalic acid, oxalates, carboxylic acids represented by general formula (11) and salts thereof, and sulfonic acids represented by general formula (12) and salts thereof, and even more preferably carbonic acid, carbonates, sulfuric acid, sulfates, oxalic acid, oxalates, and carboxylic acids represented by general formula (11) and salts thereof. １ -(COOH) ｎ (In the formula, R １ represents a monovalent to trivalent organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3) General formula (12): R ２ - (SO ３ H) ｚ (In the formula, R ２ is a monovalent to trivalent organic group having 1 to 10 carbon atoms, and z is an integer of 1 to 3.

[0030] The thermal decomposition temperature of the carboxylic acid represented by general formula (11) and its salt is preferably lower than 220°C, more preferably 210°C or lower, even more preferably 200°C or lower, particularly preferably 190°C or lower, and preferably 80°C or higher, more preferably 100°C or higher.

[0031] The thermal decomposition temperature is the temperature at which the weight loss reaches 1% of the initial weight in thermogravimetric analysis (TG) of carboxylic acid and its salt (heating rate 10° C. / min, in dry air).

[0032] In the general formula (11), n ​​is preferably 2 or 3. １ is preferably a divalent or trivalent organic group having 1 to 10 carbon atoms.

[0033] R in general formula (11) １ The number of carbon atoms is preferably 2 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0034] R in general formula (11) １ is preferably a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atoms may be substituted with hydroxy groups. １ The number of carbon atoms in the hydrocarbon group is preferably 1 or more, more preferably 2 or more, and is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0035] The thermal decomposition temperature of the sulfonic acid represented by general formula (12) and its salt is preferably lower than 220°C, more preferably 210°C or lower, even more preferably 200°C or lower, particularly preferably 190°C or lower, and preferably 80°C or higher, more preferably 100°C or higher.

[0036] The thermal decomposition temperature is the temperature at which the weight loss reaches 1% of the initial weight in thermogravimetric analysis (TG) of sulfonic acid and its salts (heating rate 10° C. / min, in dry air).

[0037] In the general formula (12), z is preferably 2 or 3. ２is preferably a divalent or trivalent organic group having 1 to 10 carbon atoms.

[0038] R in general formula (12) ２ The number of carbon atoms is preferably 2 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0039] R in general formula (12) ２ is preferably a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atoms may be substituted with hydroxy groups. ２ The number of carbon atoms in the hydrocarbon group is preferably 1 or more, more preferably 2 or more, and is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0040] Among these, the fluorine-free water-soluble electrolyte is preferably at least one selected from the group consisting of sulfuric acid, citric acid, succinic acid, carbonic acid, tartaric acid, maleic acid, malic acid, oxalic acid, malonic acid, and salts thereof, and more preferably at least one selected from the group consisting of ammonium sulfate and ammonium citrate, because this can further increase the concentration rate.

[0041] Nonionic surfactants: Nonionic surfactants typically contain no charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains a water-soluble functional group, such as an ethylene ether chain derived from polymerization with ethylene oxide.

[0042] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, glycerol esters, and derivatives thereof.

[0043] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0044] Specific examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0045] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0046] Specific examples of sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0047] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0048] Specific examples of glycerol esters include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[0049] Specific examples of the above derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0050] The ethers and esters may have an HLB value of 10-18.

[0051] Examples of nonionic surfactants include Triton (registered trademark) X series (X15, X45, X100, etc.), Tergitol (registered trademark) 15-S series, Tergitol (registered trademark) TMN series (TMN-6, TMN-10, TMN-100X, etc.), and Tergitol (registered trademark) L series, all manufactured by The Dow Chemical Company; and Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m to 22, n to 23) and Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF.

[0052] The nonionic surfactant is preferably a nonionic surfactant that does not contain fluorine. Examples thereof include ether-type nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and polyoxyethylene alkylene alkyl ether; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, and polyoxyethylene fatty acid ester; and amine-based nonionic surfactants such as polyoxyethylene alkylamine and alkylalkanolamide.

[0053] In the above nonionic surfactants, the hydrophobic group may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group.

[0054] The nonionic surfactant is preferably a nonionic surfactant represented by general formula (i): ６ -O-A １ -H (i) (wherein, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain.

[0055] In general formula (i), R ６ The number of carbon atoms in R is preferably 10 to 16, and more preferably 12 to 16. ６ When the carbon number of R is 18 or less, the composition tends to have excellent sedimentation stability. ６ If the carbon number of R exceeds 18, the flow temperature is high and it is difficult to handle. ６ If the number of carbon atoms is less than 8, the surface tension of the composition increases, and the permeability and wettability tend to decrease.

[0056] A １The polyoxyalkylene chain of A may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of 5 to 20 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is greater than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of viscosity and sedimentation stability of the composition, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. In particular, A １ When the number of oxypropylene groups is 0.5 to 1.5 on average, low foaming properties are favorable, and this is preferred.

[0057] More preferably, R ６ is (R')(R'')HC-, where R' and R'' are the same or different straight, branched, or cyclic alkyl groups having a total of at least 5, preferably 7 to 17, carbon atoms. Preferably, at least one of R' or R'' is a branched or cyclic hydrocarbon group.

[0058] Specific examples of the polyoxyethylene alkyl ether include C １３ H ２７ -O-(C ２ H ４ O) ｎ -H, C １２ H ２５ -O-(C ２ H ４ O) ｎ -H, C １０ H ２１ CH (CH ３ ) CH ２ -O-(C ２ H ４ O) ｎ -H, C １３ H ２７ -O-(C ２ H ４ O) ｎ-(CH(CH ３ ) CH ２ O) -H,C １６ H ３３ -O-(C ２ H ４ O) ｎ -H, HC(C ５ H １１ ) (C ７ H １５ )—O—(C ２ H ４ O) ｎ —H (in each formula, n is an integer of 1 or more). Commercially available polyoxyethylene alkyl ethers include, for example, the Genapol X series (manufactured by Clariant) such as Genapol X080 (trade name), the Noigen TDS series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) such as Noigen TDS-80 (trade name), the Leocol TD series (manufactured by Lion Chemical Industries, Ltd.) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Chemical Industries, Ltd.), the T-Det A series (manufactured by Harcros Chemicals) such as T-Det A138 (trade name), and the Tergitol (registered trademark) 15-S series (manufactured by The Dow Chemical Company).

[0059] Also preferred is an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, or a mixture thereof. Nonionic surfactants of this type are also commercially available, for example, under the trade names TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all trade names, manufactured by The Dow Chemical Company).

[0060] The hydrophobic group of the nonionic surfactant may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group. For example, the nonionic surfactant may be a nonionic surfactant represented by the general formula (ii): ７ -C ６ H ４ -O-A ２ -H (ii) (wherein, R７ is a linear or branched alkyl group having 4 to 12 carbon atoms, and A ２ is a polyoxyalkylene chain. Specific examples of the nonionic surfactant include Triton (registered trademark) X-100 (trade name, manufactured by The Dow Chemical Company).

[0061] A ２ The polyoxyalkylene chain of A may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of 5 to 20 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is greater than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of viscosity and sedimentation stability of the composition, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. In particular, A ２ When the number of oxypropylene groups is 0.5 to 1.5 on average, low foaming properties are favorable, and this is preferred.

[0062] More preferably, R ７ is a primary or secondary alkyl group, more preferably (R')(R")HC-, where R' and R" are the same or different straight, branched, or cyclic alkyl groups having a total of at least 5, preferably 7 to 17 carbon atoms. Preferably, at least one of R' or R" is a branched or cyclic hydrocarbon group.

[0063] The nonionic surfactant also includes polyol compounds. Specific examples include those described in International Publication No. 2011 / 014715. Typical examples of polyol compounds include compounds having one or more sugar units as polyol units. The sugar units may be modified to contain at least one long chain. Suitable polyol compounds containing at least one long chain moiety include, for example, alkyl glycosides, modified alkyl glycosides, sugar esters, and combinations thereof. Sugars include, but are not limited to, monosaccharides, oligosaccharides, and sorbitan. Monosaccharides include pentoses and hexoses. Typical examples of monosaccharides include ribose, glucose, galactose, mannose, fructose, arabinose, and xylose. Oligosaccharides include oligomers of 2 to 10 identical or different monosaccharides. Examples of oligosaccharides include, but are not limited to, sucrose, maltose, lactose, raffinose, and isomaltose.

[0064] Typically, sugars suitable for use as polyol compounds include cyclic compounds containing a five-membered ring with four carbon atoms and one heteroatom (typically oxygen or sulfur, but preferably oxygen), or a six-membered ring with five carbon atoms and one heteroatom, preferably oxygen, as described above. These further contain at least two or at least three hydroxy groups (—OH groups) attached to the carbon ring atoms. Typically, the sugars are modified in that one or more of the hydrogen atoms of the hydroxy groups (and / or hydroxyalkyl groups) attached to the carbon ring atoms are replaced with a long-chain residue such that an ether or ester bond is created between the long-chain residue and the sugar moiety. Sugar-based polyols may contain one sugar unit or multiple sugar units. One sugar unit or multiple sugar units may be modified with a long-chain moiety as described above. Specific examples of sugar-based polyol compounds include glycosides, sugar esters, sorbitan esters, and mixtures and combinations thereof.

[0065] A preferred class of polyol compounds are the alkyl or modified alkyl glucosides. These classes of surfactants contain at least one glucose moiety. (wherein x represents 0, 1, 2, 3, 4, or 5; R １ and R ２ independently represent H or a long chain unit containing at least 6 carbon atoms, with the proviso that R １ and R ２ and at least one of R is not H. １ and R ２ Typical examples of alkyl polyglucosides include fatty alcohol residues. Examples of fatty alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. While the above formula represents a specific example of an alkyl polyglucoside showing glucose in the pyranose form, it is understood that other sugars or sugars of the same sugar but in different enantiomeric or diastereomeric forms may also be used.

[0066] Alkyl glucosides can be obtained, for example, by the acid-catalyzed reaction of glucose, starch, or n-butyl glucoside with aliphatic alcohols, which typically results in a mixture of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, George Thieme Verlag, 1999). Examples of aliphatic alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. Alkyl glucosides are also commercially available from Cognis GmbH, Dusseldorf, Germany under the trade names GLUCOPON or DISPONIL.

[0067] Other nonionic surfactants include difunctional block copolymers supplied by BASF as part of the Pluronic® R series, and tridecyl alcohol alkoxylates supplied by BASF as part of the Iconol® TDA series.

[0068] The nonionic surfactant is preferably at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii), and more preferably a nonionic surfactant represented by general formula (i).

[0069] The nonionic surfactant preferably does not contain an aromatic moiety.

[0070] (Pre-concentration composition) In the production method of the present disclosure, a polymer dispersion is obtained by polymerizing a fluoromonomer, and then the obtained polymer dispersion is mixed with a nonionic surfactant and a fluorine-free water-soluble electrolyte to prepare a pre-concentration composition.

[0071] The content of the fluorine-free water-soluble electrolyte in the pre-concentration composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and still more preferably 1.5% by mass or less, relative to the fluoropolymer. By adjusting the content of the fluorine-free water-soluble electrolyte within the above range, the concentration of the fluoropolymer in the composition can be increased at a higher rate. If the content of the fluorine-free water-soluble electrolyte is too low, concentration may not proceed at a sufficient rate. If the content of the fluorine-free water-soluble electrolyte is too high, concentration may become difficult.

[0072] The content of the non-fluorine-containing water-soluble electrolyte in the composition can be calculated from the amount of the non-fluorine-containing water-soluble electrolyte added that was used to prepare the pre-concentration composition.

[0073] The content of the nonionic surfactant in the composition before concentration is preferably 1.0% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the fluoropolymer. If the content of the nonionic surfactant is too low, concentration may become difficult, and if the content of the nonionic surfactant is too high, economic efficiency may be impaired.

[0074] The content (N mass %) of the nonionic surfactant relative to the fluoropolymer is a value calculated from the heating residue (Yg) obtained by heating about 1 g (Xg) of a sample at 110°C for 30 minutes, and the heating residue (Zg) obtained by further heating the obtained heating residue (Yg) at 300°C for 30 minutes, according to the formula: N = [(Y-Z) / Z] x 100 (mass %).

[0075] The content of the fluoropolymer in the composition before concentration (solids concentration) is usually 8 to 50% by mass, preferably 10% by mass or more, more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less.

[0076] The fluoropolymer content (P mass %) in the composition before concentration is a value calculated from the heating residue (Yg) obtained by heating about 1 g (Xg) of a sample at 110°C for 30 minutes and the heating residue (Zg) obtained by further heating the obtained heating residue (Yg) at 300°C for 30 minutes, according to the formula: P = [Z / X] × 100 (mass %).

[0077] The pH of the pre-concentration composition is preferably 4.0 to 11.5, more preferably 7.0 or higher, even more preferably 8.0 or higher, and particularly preferably 9.0 or higher. By adjusting the pH of the pre-concentration composition to fall within the above range, the concentration rate can be further increased.

[0078] In one embodiment of the pre-concentration composition, it contains a fluorine-containing surfactant. Even when the composition contains a fluorine-containing surfactant, the fluorine-containing surfactant can be removed from the composition by concentrating it, thereby obtaining an aqueous fluoropolymer dispersion with a reduced fluorine-containing surfactant content.

[0079] In one embodiment of the pre-concentration composition, the composition is substantially free of a fluorine-containing surfactant. In the present disclosure, "substantially free of a fluorine-containing surfactant" means that the content of the fluorine-containing surfactant in the composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, still more preferably 1 ppb by mass or less, and particularly preferably below the detection limit of the fluorine-containing surfactant as measured by liquid chromatography-mass spectrometry (LC / MS).

[0080] The content of the fluorine-containing surfactant can be measured, for example, by adding methanol to the composition, extracting, and subjecting the obtained extract to LC / MS analysis. To further increase the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. Molecular weight information is extracted from the obtained LC / MS spectrum, and its agreement with the structural formula of the candidate fluorine-containing surfactant is confirmed. Then, aqueous solutions containing five or more levels of the identified fluorine-containing surfactant are prepared, and LC / MS analysis is performed on the aqueous solutions containing each level. The relationship between the content and the area relative to the content is plotted, and a calibration curve is drawn. Using the calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing surfactant in the extract can be converted to the content of the fluorine-containing surfactant.

[0081] (Concentration) In the production method of the present disclosure, after preparing a pre-concentration composition, the pre-concentration composition is concentrated to obtain an aqueous dispersion containing a fluoropolymer.

[0082] An aqueous medium such as water or alcohol may be added to the composition before or during the concentration of the pre-concentrated composition. The aqueous medium may be a single component such as water or alcohol, or a mixture of water and alcohol.

[0083] Concentration methods include phase separation concentration, electrophoresis, ion exchanger method, membrane concentration, etc. Phase separation concentration, ion exchanger method, and membrane concentration can be carried out under conventionally known treatment conditions, and are not particularly limited, but can be carried out by the methods described in WO 2004 / 050719, JP-A 2002-532583, and JP-A 55-120630.

[0084] The concentration method is preferably concentration by phase separation, which can be carried out, for example, by heating the pre-concentration composition to cause phase separation into a fluoropolymer-free phase (supernatant phase) and a fluoropolymer-containing phase (concentrated phase), removing the fluoropolymer-free phase, and recovering the fluoropolymer-containing phase (concentrated phase).

[0085] The recovered fluoropolymer-containing phase (concentrated phase) contains the fluoropolymer, the non-ionic surfactant, the fluorine-free water-soluble electrolyte and the aqueous medium.

[0086] The temperature for the phase separation concentration can be selected based on the cloud point of the nonionic surfactant contained in the pre-concentration composition, and is preferably at least 10°C lower than the cloud point of the nonionic surfactant, and is preferably not higher than 10°C higher than the cloud point of the nonionic surfactant.

[0087] In the production method of the present disclosure, it is also preferable to repeatedly carry out phase separation concentration.

[0088] The number of repetitions is not particularly limited, but is preferably 2 or more, more preferably 3 or more. The upper limit of the number of repetitions is not limited, but may be, for example, 10 or less.

[0089] When the phase separation concentration is performed two or more times, the first phase separation concentration is preferably performed by heating at a temperature at least 10°C lower than the cloud point of the nonionic surfactant and then allowing to stand, resulting in separation into an upper supernatant phase and a concentrated phase. The second or subsequent phase separation concentration is preferably performed by heating at a temperature at least 10°C lower than the cloud point of the nonionic surfactant and then allowing to stand, resulting in separation into an upper supernatant phase and a concentrated phase.

[0090] When the phase separation concentration is repeated multiple times in the production method of the present disclosure, the first phase separation concentration is also preferably carried out in the presence of a fluorine-free water-soluble electrolyte.

[0091] When the phase separation concentration is repeated multiple times, except for the final phase separation concentration, the phase separation concentration can be stopped when the solids concentration of the fluoropolymer in the composition reaches 48 to 52 mass%, an aqueous medium can be added to the concentrated composition, and then the phase separation concentration can be repeated. By stopping the phase separation concentration when the solids concentration of the fluoropolymer reaches the above range, each phase separation concentration can be completed in a short time, and as a result, the total time required for the phase separation concentration can be shortened.

[0092] An anionic surfactant may be added to the aqueous fluoropolymer dispersion obtained by concentration. Examples of the anionic surfactant include fluorine-free anionic surfactants that do not contain fluorine and fluorine-containing anionic surfactants, but fluorine-free anionic surfactants that do not contain fluorine (i.e., hydrocarbon-based anionic surfactants) are preferred.

[0093] For the purpose of adjusting viscosity, there is no particular limitation on the type of anionic surfactant as long as it is a known anionic surfactant. For example, the fluorine-free anionic surfactants described in WO 2013 / 146950 and WO 2013 / 146947 can be used. Examples include those having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, and more preferably 9 to 13 carbon atoms. The saturated or unsaturated aliphatic chain may be either a linear or branched chain, or may have a cyclic structure. The hydrocarbon may be aromatic or may have an aromatic group. The hydrocarbon may have a heteroatom such as oxygen, nitrogen, or sulfur.

[0094] Examples of the fluorine-free anionic surfactant include alkyl sulfonates, alkyl sulfates, alkylaryl sulfates, and salts thereof; fatty acids (aliphatic carboxylic acids) and salts thereof; alkyl phosphates, alkylaryl phosphates, and salts thereof; and among these, alkyl sulfonates, alkyl sulfates, aliphatic carboxylic acids, and salts thereof are preferred.

[0095] The alkyl sulfate or its salt is preferably ammonium lauryl sulfate or sodium lauryl sulfate.

[0096] As the fatty acid (aliphatic carboxylic acid) or a salt thereof, succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or a salt thereof is preferred.

[0097] The fluorine-free anionic surfactant is preferably at least one selected from the group consisting of alkyl sulfates and salts thereof, and fatty acids and salts thereof.

[0098] The content of the fluorine-free anionic surfactant varies depending on the type of the fluorine-free anionic surfactant and other compounding ingredients, but is preferably 10 ppm to 5000 ppm based on the solid mass of the fluoropolymer.

[0099] The lower limit of the amount of the fluorine-free anionic surfactant added is more preferably 50 ppm or more, and even more preferably 100 ppm or more. If the amount added is too small, the viscosity adjusting effect is poor.

[0100] The upper limit of the amount of the fluorine-free anionic surfactant to be added is preferably 4000 ppm or less, and more preferably 3000 ppm or less. If the amount is too large, the viscosity may increase, particularly at high temperatures. In addition, there is a risk of excessive foaming.

[0101] For the purpose of adjusting the viscosity of the aqueous fluoropolymer dispersion obtained by concentration, in addition to the fluorine-free anionic surfactant, for example, methyl cellulose, alumina sol, polyvinyl alcohol, carboxylated vinyl polymer, etc. may also be blended.

[0102] For the purpose of adjusting the pH of the aqueous fluoropolymer dispersion obtained by concentration, a pH adjuster such as aqueous ammonia may be added.

[0103] The pH of the aqueous fluoropolymer dispersion obtained by concentration is preferably 8 to 13, more preferably 9 to 12, and even more preferably 9 to 11.

[0104] The pH is a value measured at 25°C in accordance with JIS K6893.

[0105] If necessary, other water-soluble polymer compounds may be added to the aqueous fluoropolymer dispersion obtained by concentration.

[0106] Other water-soluble polymer compounds are not particularly limited and include, for example, polyethylene oxide (dispersion stabilizer), polyethylene glycol (dispersion stabilizer), polyvinylpyrrolidone (dispersion stabilizer), phenol resin, urea resin, epoxy resin, melamine resin, polyester resin, polyether resin, acrylic silicone resin, silicone resin, silicone polyester resin, polyurethane resin, etc. Furthermore, preservatives such as isothiazolones, azoles, pronopol, chlorothalonil, methylsulfonyltetrachloropyrrolidone, carbentazim, fluorophorbet, sodium diacetate, and diiodomethyl-paratolyl sulfone may be contained.

[0107] A defoaming agent may be added to the concentrated aqueous fluoropolymer dispersion as long as it does not cause any economic or environmental problems.

[0108] As the defoaming agent, various aqueous defoaming agents can be used, and examples thereof include lower alcohols such as methanol, ethanol, butanol, etc.; higher alcohols such as amyl alcohol, polypropylene glycol and derivatives thereof; oils and fats such as oleic acid, tall oil, mineral oil, soap, etc.; surfactants such as sorbitan fatty acid esters, polyethylene glycol fatty acid esters, Pluronic (registered trademark) type nonionic surfactants, etc.; silicone-based surfactants such as siloxanes, silicone resins, etc.; and surfactants such as alkanediol-based and acetylene diol-based surfactants, etc., which can be used alone or in combination. Representative commercially available defoaming agents include B-series products such as Adekanate B and Adekanate B1068 (manufactured by Asahi Denka Kogyo Co., Ltd.); SN Defoamer series products such as Formaster DL, Nopco NXZ, and SN Defoamer 113, 325, 308, and 368; Dehydran 1293 and Dehydran 1513 (manufactured by San Nopco Ltd.); Flonone SB-110N, SB-210, 510, and 551; and Aqualene 80. 0, 805, Aqualene 1488 (manufactured by Kyoeisha Chemical Co., Ltd.); Surfynol 104E, 440 (manufactured by Evonik Co., Ltd.); KS-607A (manufactured by Shin-Etsu Chemical Co., Ltd.); FS Antifoam (manufactured by Dow Corning Corporation); BYK-020, 031, 073, W (manufactured by BYK-Chemie); Dehydran 981 (manufactured by Henkel Hakusui Chemical Co., Ltd.); Epan-410, 710, 720 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.); Tego Foamex series (manufactured by Tego Goldschmidt); Foamrex-747, TY-10, EP series (manufactured by Nicca Chemical Co., Ltd.). The content of the antifoaming agent is preferably 0.01 to 10% by mass, particularly preferably 0.05 to 5% by mass, based on the fluoropolymer aqueous dispersion.

[0109] Although an antifoaming agent may be added to the aqueous fluoropolymer dispersion obtained by concentration, it is preferable not to add it. Not adding it is advantageous in terms of cost. Furthermore, adding an antifoaming agent may cause coloration when the aqueous fluoropolymer dispersion is formed into a coating film.

[0110] (Polymerization dispersion) The polymerization dispersion used in the manufacturing method of the present disclosure can be produced by polymerizing a fluoromonomer in an aqueous medium in the presence of the polymer (I). The polymerization dispersion obtained by polymerization contains a fluoropolymer (excluding the polymer (I)), the polymer (I), and an aqueous medium.

[0111] The content of the fluoropolymer in the polymer dispersion (solid content concentration) is usually 10 to 50% by mass, more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less.

[0112] The fluoropolymer content in the polymer dispersion is a value obtained by drying 1 g of the polymer dispersion in a blower dryer at 150°C for 60 minutes, measuring the mass of the heating residue, and calculating the mass of the heating residue relative to the mass (1 g) of the polymer dispersion as a percentage.

[0113] (Polymer (I)) The polymer (I) used in the production method of the present disclosure contains polymerized units (I) based on the monomer (I) represented by general formula (I). CX １ X ３ =CX ２ R (-CZ １ Z ２ -A ０ ) ｍ (I) (wherein, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

[0114] In the present disclosure, anionic groups include anionic groups such as sulfate groups, carboxylate groups, and acid groups such as —COOH, —COONH ４The anionic group includes a functional group that provides an anionic group such as an acid-base group, such as a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or a -C(CF ３ ) ２ OM (wherein M is —H, a metal atom, —NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.

[0115] In the production method of the present disclosure, one or more types of monomers can be used as the monomer (I) represented by general formula (I).

[0116] R is a linking group. In the present disclosure, a "linking group" is an (m+1)-valent linking group, and when m is 1, it is a divalent linking group. The linking group may be a single bond and preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less.

[0117] The linking group may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0118] m is an integer of 1 or more, preferably 1 or 2, and more preferably 1. When m is an integer of 2 or more, Z １ , Z ２ and A ０ may be the same or different. Next, a preferred structure when m is 1 in general formula (I) will be described.

[0119] R is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group.

[0120] When R is a divalent organic group, a hydrogen atom bonded to a carbon atom may be replaced with a halogen atom other than fluorine, such as chlorine, and may or may not contain a double bond. R may be either linear or branched, and may be cyclic or acyclic. R may also contain a functional group (e.g., ester, ether, ketone (keto group), amine, halide, etc.).

[0121] R may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group.

[0122] R may be, for example, a hydrocarbon group in which no fluorine atoms are bonded to the carbon atoms, a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms, or a hydrocarbon group in which all of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms, and these may contain an oxygen atom, a double bond, or a functional group.

[0123] R is preferably a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond or a keto group, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine.

[0124] R is preferably —(CH ２ ) ａ -, - (CF ２ ) ａ -, - (CF ２ ) ａ -O-, -O-(CF ２ ) ａ -, - (CF ２ ) ａ -O-(CF ２ ) ｂ -, -O(CF ２ ) ａ -O-(CF ２ ) ｂ -, - (CF ２ )ａ -[O-(CF ２ ) ｂ ] ｃ -、-O(CF ２ ) ａ -[O-(CF ２ ) ｂ ] ｃ -、-[(CF ２ ) ａ -O] ｂ -[(CF ２ ) ｃ -O] ｄ -、-O[(CF ２ ) ａ -O] ｂ -、-O[(CF ２ ) ａ -O] ｂ -[(CF ２ ) ｃ -O] ｄ -、-O-[CF ２ CF(CF ３ )O] ａ -(CF ２ ) ｂ -、-O-(CF ２ ) ａ -O-[CF(CF ３ )CF ２ O] ｂ -、-O-[CF ２ CF(CF ３ )O] ａ -(CF ２ ) ｂ -O-、-O-[CF ２ CF(CF ３ )O] ａ -(CF ２ ) ｂ -O-[CF(CF ３ )CF ２ O] ｃ -、-[CF ２ CF(CF ３ )O] ａ -、-[CF(CF ３ )CF ２ O] ａ -、-(CF ２ ) ａ -O-[CF(CF ３ )CF ２ O] ａ -、-(CF ２) ａ -O-[CF(CF ３ )CF ２ O] ａ -(CF ２ ) ｂ -, -[CF ２ CF (CF ３ )] ａ -CO-(CF ２ ) ｂ - and at least one selected from combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0125] More preferably, R is —O—CF ２ -, -O-CF ２ CF ２ -, -O-CF ２ CF ２ —O—, —O—CF ２ CF ２ CF ２ -, -O-CF ２ CF ２ CF ２ —O—, —O—CF ２ CF (CF ３ ) -O-, -O-CF ２ CF ２ -O-CF(CF ３ )CF ２ —O—, —O—CF ２ CF (CF ３ )-O-CF ２ CF ２ —O— and —O—CF ２ CF (CF ３ )-O-CF ２ - At least one selected from the following.

[0126] R is a group represented by the general formula (r1): -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O)ｇ - (r1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, and g is 0 or 1), and a divalent group represented by the general formula (r2): -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ - (r2) (wherein, X ７ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, and g is 0 or 1) is more preferred.

[0127] A specific example of a suitable R is —CF ２ —O—, —CF ２ -O-CF ２ -, -CF ２ -O-CH ２ -, -CF ２ -O-CH ２ CF ２ -, -O-CF ２ -, -O-CF ２ CF ２ -, -O-CF ２ CF ２ CF ２ -, -O-CF ２ CF ２ CF ２ CF ２ -, -O-CF ２ CF (CF ３ )-O-CF ２ -, -O-CF ２ CF (CF ３ )-O-CF ２ CF ２ -, -CF ２ -O-CF ２ CF ２ -, -CF ２ -O-CF ２ CH ２ -, -CF ２ -O-CF ２ CF ２ CH ２ -, -CF ２ -O-CF(CF３ ) -, -CF ２ -O-CF(CF ３ )CF ２ -, -CF ２ -O-CF(CF ３ )CF ２ —O—, —CF ２ -O-CF(CF ３ )CF ２ -O-CF ２ -, -CF ２ -O-CF(CF ３ ) CH ２ Among these, R is preferably a perfluoroalkylene group which may contain an oxygen atom, specifically, —CF ２ —O—, —CF ２ -O-CF ２ -, -O-CF ２ -, -O-CF ２ CF ２ -, -O-CF ２ CF (CF ３ )-O-CF ２ -, -O-CF ２ CF (CF ３ )-O-CF ２ CF ２ -, -CF ２ -O-CF ２ CF ２ -, -CF ２ -O-CF(CF ３ ) -, -CF ２ -O-CF(CF ３ )CF ２ - or -CF ２ -O-CF(CF ３ )CF ２ —O— is preferred.

[0128] -R-CZ of general formula (I) １ Z ２ - is a group represented by the general formula (s1): -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O) ｇ -CZ １ Z ２- (s1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, and Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s1), Z １ and Z ２ is F or CF ３ is more preferred, one of which is F and the other is CF ３ It is more preferable that:

[0129] In addition, in the general formula (I), -R-CZ １ Z ２ - is a group represented by the general formula (s2): -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ -CZ １ Z ２ - (s2) (wherein, X ７ are each independently H, F or CF ３ where e is an integer of 0 to 3, g is 0 or 1, and Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s2), Z １ and Z ２ is F or CF ３ is more preferred, one of which is F and the other is CF ３ It is more preferable that:

[0130] -R-CZ of general formula (I) １ Z ２ - is -CF ２ -O-CF ２ -, -O-CF ２ CF ２ -, -O-CF ２ CF ２ CF ２ -, -O-CF ２ CF ２ CF ２ CF２ -、-O-CF ２ CF(CF ３ )-O-CF ２ -、-O-CF ２ CF(CF ３ )-O-CF ２ CF ２ -、-O-CF ２ CF(CF ３ )-O-CF ２ CF ２ CF ２ -、-CF ２ -O-CF(CF ３ )-、-CF ２ -O-C(CF ３ ) ２ -、-CF ２ -O-CF ２ -CF ２ -、-CF ２ -O-CF ２ -CF(CF ３ )-、-CF ２ -O-CF ２ -C(CF ３ ) ２ -、-CF ２ -O-CF ２ CF ２ -CF ２ -、-CF ２ -O-CF ２ CF ２ -CF(CF ３ )-、-CF ２ -O-CF ２ CF ２ -C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )-CF ２ -、-CF ２ -O-CF(CF ３ )-CF(CF ３ )-、-CF ２ -O-CF(CF ３ )-C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )CF ２ -CF ２ -、-CF ２ -O-CF(CF３ ) CF ２ -CF(CF ３ )-、-CF ２ -O-CF(CF ３ )CF ２ -C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )CF ２ -O-CF ２ -、-CF ２ -O-CF(CF ３ )CF ２ -O-CF(CF ３ )-、または、-CF ２ -O-CF(CF ３ )CF ２ -O-C(CF ３ ) ２ -が好ましく、-O-CF ２ CF ２ -、-O-CF ２ CF ２ CF ２ -、-O-CF ２ CF ２ CF ２ CF ２ -、-O-CF ２ CF(CF ３ )-O-CF ２ -、-O-CF ２ CF(CF ３ )-O-CF ２ CF ２ -、-CF<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​３ )CF ２ -O-CF(CF ３ )- is more preferred, and —O—CF ２ CF ２ -, -O-CF ２ CF (CF ３ )-O-CF ２ CF ２ - is more preferred.

[0131] It is also preferred that the polymer (I) is highly fluorinated. For example, the polymer (I) contains phosphate group moieties (e.g., CH ２ OP (O) (OM) ２ ) and sulfate group moieties (e.g., CH ２ OS (O) ２ anionic groups (A) such as ０ ), it is preferred that 80% or more, 90% or more, 95% or more, or 100% of the C—H bonds in polymer (I) are substituted with C—F bonds.

[0132] The monomer (I) and the polymer (I) contain an anionic group (A ０ ) except for the above, it is also preferable that the compound has a C—F bond and does not have a C—H bond. １ , X ２ , and X ３ is preferably F, and R is a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be cyclic or acyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0133] The monomer (I) and the polymer (I) may be partially fluorinated. That is, the monomer (I) and the polymer (I) may have an anionic group (A ０ ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0134] Anionic group (A ０ ) is -SO ２M, -SO ３ M, -OSO ３ M, -COOM, -SO ２ NR'CH ２ COOM, -CH ２ OP (O) (OM) ２ , [-CH ２ O] ２ P(O)(OM), -CH ２ CH ２ OP (O) (OM) ２ , [-CH ２ CH ２ O] ２ P(O)(OM), -CH ２ CH ２ OSO ３ M, -P(O)(OM) ２ , -SO ２ NR'CH ２ CH ２ OP (O) (OM) ２ , [-SO ２ NR'CH ２ CH ２ O] ２ P(O)(OM), -CH ２ OSO ３ M, -SO ２ NR'CH ２ CH ２ OSO ３ M, or -C(CF ３ ) ２ Among them, -SO ３ M, -OSO ３ M, -COOM, -P(O)(OM) ２ or -C(CF ３ ) ２ -OM is preferred, -COOM and -SO ３ M, -OSO ３ M, -P(O)(OM) ２ or -C(CF ３ ) ２ OM is more preferred, and —SO ３ M, -COOM or -P(O)(OM) ２ is more preferred, and —SO ３ M or -COOM is particularly preferred.

[0135] M is H, a metal atom, or NR７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.

[0136] The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li.

[0137] M is —H, a metal atom, or NR ７ ４ is preferred, and —H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR ７ ４ is more preferred, and —H, —Na, —K, —Li or NH ４ is more preferred, and —H, —Na, —K or NH ４ is even more preferred, -H, -Na or NH ４ is particularly preferred, and —H or —NH ４ is most preferred.

[0138] In the polymer (I), each polymer unit (I) may have a different anionic group or may have the same anionic group.

[0139] The monomer (I) is preferably a monomer represented by the general formula (Ia). The polymer (I) is preferably a polymer containing a polymerized unit (Ia) based on the monomer represented by the general formula (Ia). CF ２ ═CF—O—Rf ０ -A ０ (Ia) (wherein A ０ is an anionic group, and Rf ０ is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0140] The monomer (I) is preferably a monomer represented by the general formula (Ib). The polymer (I) is preferably a polymer containing a polymerized unit (Ib) based on the monomer represented by the general formula (Ib). CH ２ =CH-O-Rf ０ -A ０ (Ib) (wherein, A ０ is an anionic group, and Rf ０ is a perfluorinated divalent linking group as defined in formula Ia.

[0141] In general formula (I), A ０ is a sulfate group. ０ is, for example, -CH ２ OSO ３ M, -CH ２ CH ２ OSO ３ M or -SO ２ NR'CH ２ CH ２ OSO ３ M, where R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0142] A ０ is a sulfate group, examples of the monomer represented by general formula (I) include CF ２ =CF(OCF ２ CF ２ CH ２ OSO ３ M), CF ２ =CF(O(CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ OSO ３ M), CH ２ =CH(O(CF２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ M), CH ２ =CH(OCF ２ CF ２ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ CF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ M), CH ２ =CH(OCF ２ CF ２ CF ２ CH ２ OSO ３ In the above formula, M is the same as above.

[0143] In general formula (I), A ０ In one preferred embodiment, A is a sulfonate group. ０ For example, -SO ３ M, where M is the same as above.

[0144] A ０ is a sulfonate group, the monomer represented by general formula (I) is ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ =CF(O(CF ２ ) ３ SO ３ M), CF ２ =CF(O(CF ２ ) ４ SO ３ M), CF ２ =CF(OCF２ CF (CF ３ ) SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M), CH ２ =CH(OCF ２ CF ２ SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ CF ２ SO ３ M), CH ２ =CH(O(CF ２ ) ４ SO ３ M), CH ２ =CH(O(CF ２ ) ３ SO ３ In the above formula, M is the same as above.

[0145] In general formula (I), A ０ In one preferred embodiment, A is a carboxylate group. ０ Examples of the ２ NR'CH ２ COOM, where R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above. ０ is a carboxylate group, the monomer represented by general formula (I) is ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(O(CF ２ ) ３ COOM), C.F. ２ =CF(O(CF ２ ) ４ COOM), C.F. ２ =CF(O(CF ２ ) ５ COOM), C.F. ２ =CF(OCF２ CF(CF ３ )(COOM), CF ２ =CF(OCF ２ CF(CF ３ )(OCF ２ )(n is greater than 1), CH ｎ =CH(OCF ２ CF ２ COOM), CH ２ =CH(O(CF ２ )(COOM), CH ２ )(COOM), CH ４ =CH(O(CF ２ )(COOM), CF ２ )(COOM), CF ３ =CF(OCF ２ CF ２ SO ２ NR'CH ２ COOM), CF ２ =CF(O(CF ２ )(SO ２ NR'CH ４ COOM), CF ２ =CF(OCF ２ CF(CF ２ )(SO ２ NR'CH ３ COOM), CF ２ =CF(OCF ２ CF(CF ２ )(OCF ２ CF ３ SO ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH(OCF ２ CF ２ SO ２ NR'CH ２ COOM), CF ２ =CF(OCF ２ CF(CF ３ )(OCF ２ CF ２ CF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH(O(CF ２ )(SO ４ SO２ NR'CH ２ COOM), CH ２ =CH(O(CF ２ ) ３ SO ２ NR'CH ２ In the above formula, R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0146] In general formula (I), A ０ In one preferred embodiment, A is a phosphate group. ０ Examples of the group include -CH ２ OP (O) (OM) ２ , [-CH ２ O] ２ P(O)(OM), -CH ２ CH ２ OP (O) (OM) ２ , [-CH ２ CH ２ O] ２ P(O)(OM), [-SO ２ NR'CH ２ CH ２ O] ２ P(O)(OM) or SO ２ NR'CH ２ CH ２ OP (O) (OM) ２ wherein R' is an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0147] A ０ is a phosphate, the monomer represented by general formula (I) is CF ２ =CF(OCF ２ CF ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(O(CF ２ ) ４ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) CH ２ OP (O) (OM) ２ ), CF２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF ２ CF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OP (O) (OM) ２ ), C.H. ２ =CH(OCF ２ CF ２ CH ２ OP (O) (OM) ２ ), C.H. ２ =CH(O(CF ２ ) ４ CH ２ OP (O) (OM) ２ ), C.H. ２ =CH(O(CF ２ ) ３ CH ２ OP (O) (OM) ２ In the above formula, M is the same as above.

[0148] In general formula (I), A ０ In one preferred embodiment, A is a phosphonate group. ０ is a phosphonate group, the monomer represented by general formula (I) is ２ =CF(OCF ２ CF ２ P(O)(OM) ２ ), CF ２ =CF(O(CF ２ ) ４ P(O)(OM) ２ ), CF ２=CF(OCF ２ CF (CF ３ ) P (O) (OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ P(O)(OM) ２ ), C.H. ２ =CH(OCF ２ CF ２ P(O)(OM) ２ ), C.H. ２ =CH(O(CF ２ ) ４ P(O)(OM) ２ ), C.H. ２ =CH(O(CF ２ ) ３ P(O)(OM) ２ ) wherein M is the same as above.

[0149] The monomer (I) is preferably a monomer (1) represented by the general formula (1). The polymer (I) is preferably a polymer (1) containing a polymerized unit (1) based on the monomer represented by the general formula (1). CX ２ =CY(-CZ ２ -O-Rf-A) (1) (In the formula, X is the same or different and represents -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z is the same or different and represents -H, -F, an alkyl group or a fluoroalkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is -H, metal atom, -NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.) However, at least one of X, Y, and Z contains a fluorine atom.)

[0150] In the production method of the present disclosure, the monomer (1) represented by the general formula (1) may be copolymerized with another monomer. The polymer (1) may be a homopolymer of the monomer (1) represented by the general formula (1), or may be a copolymer with another monomer.

[0151] The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0152] In general formula (1), X is —H or F. Both Xs may be —F, or at least one X may be —H. For example, one X may be —F and the other may be —H, or both Xs may be —H.

[0153] In general formula (1), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The Y may be -H, -F or CF ３ is preferred, and —F is more preferred.

[0154] In general formula (1), Z's may be the same or different and are -H, -F, an alkyl group, or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The Z's may be -H, -F, or CF ３ is preferred, and —F is more preferred.

[0155] In general formula (1), at least one of X, Y, and Z contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0156] In the general formula (1), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond.

[0157] The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, particularly preferably 6 or less, and most preferably 3 or less. The fluorine-containing alkylene group includes, for example, —CF ２ -, -CH ２ CF ２ -, -CF ２ CF ２ -, -CF ２ CH ２ -, -CF ２ CF ２ CF ２ -, -CF ２ CF ２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0158] The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, particularly preferably 9 or less, and most preferably 6 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0159] Specific examples of the fluorine-containing alkylene group having an ether bond include —CF ２ CF (CF ３ ) OCF ２ -, -CF(CF ３ )CF ２ -O-CF(CF ３ )-,-(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ )-(wherein n is an integer from 1 to 10), -CF(CF ３ )CF ２ -O-CF(CF ３ ) CH ２ -, -(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ ) CH ２ - (wherein n is an integer of 1 to 10), -CH ２ CF ２ CF ２ O-CH ２ CF ２ CH ２ -, -CF ２ CF ２ CF ２ O-CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ CH ２ -, -CF ２ CF ２ O-CF ２ -, -CF ２ CF２ O-CF ２ CH ２ The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0160] In the general formula (1), A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group).

[0161] R ７ As the group, H or C １－１０ is preferably an organic group of the formula １－４ More preferred are organic groups of the formula: １－４ More preferred are alkyl groups of the formula:

[0162] The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li.

[0163] M is H, a metal atom, or NR ７ ４ is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR ７ ４ is more preferred, and H, Na, K, Li or NH ４ is more preferred, and H, Na, K or NH ４ is even more preferred, H, Na or NH ４ is particularly preferred, and H or NH ４ is most preferred.

[0164] A is -COOM or -SO ３ M is preferred.

[0165] Examples of the monomer represented by the general formula (1) include a monomer represented by the general formula (1a): CX ２ =CFCF ２-O-(CF(CF ３ )CF ２ O) ｎ５ -CF (CF ３ )-A (1a) (wherein each X is the same and represents F or H, n5 represents 0 or an integer of 1 to 10, and A is as defined above).

[0166] In general formula (1a), n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in that particles having a small primary particle size can be obtained.

[0167] In the production method of the present disclosure, the monomer represented by general formula (1a) may be copolymerized with another monomer, and the polymer (1) may be a homopolymer of the monomer represented by general formula (1a) or a copolymer with another monomer.

[0168] The monomer (1) is preferably a monomer represented by the general formula (1A). The polymerized unit (1) is preferably a polymerized unit (1A) based on a monomer represented by the general formula (1A). CH ２ =CF(-CF ２ —O—Rf-A) (1A) (wherein Rf and A are the same as defined above.)

[0169] In the production method of the present disclosure, the monomer represented by general formula (1A) may be copolymerized with another monomer, and the polymer (1) may be a homopolymer of the monomer represented by general formula (1A) or a copolymer with another monomer.

[0170] Specific examples of the monomer represented by formula (1A) include the monomer represented by the general formula:

[0171]

[0172] (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３p1+q1+r1 is an integer of 0 to 10; s1 is 0 or 1; t1 is an integer of 0 to 5, provided that Z ３ and Z ４ are both H, then p1+q1+r1+s1 is not 0; A is the same as defined above). More specifically,

[0173]

[0174] Among them,

[0175]

[0176] It is preferable that:

[0177] In the monomer represented by the general formula (1A), A in the formula (1A) is preferably -COOM, and particularly preferably CH ２ =CFCF ２ OCF (CF ３ ) COOM, and CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ )COOM (wherein M is as defined above), and CH ２ =CFCF ２ OCF (CF ３ ) COOM is more preferred.

[0178] Further, examples of the monomer represented by general formula (1) include a monomer represented by the following formula: CF ２ =CFCF ２ -O-Rf-A (wherein Rf and A are the same as above)

[0179] More specifically, etc.

[0180] The monomer (I) is preferably a monomer (2) represented by the general formula (2). The polymer (I) is preferably a polymer (2) containing a polymer unit (2) based on the monomer represented by the general formula (2). CX ２=CY(-O-Rf-A) (2) (In the formula, X's may be the same or different and each represent -H or F; Y represents -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf represents a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group; and A is the same as defined above.)

[0181] In the production method of the present disclosure, the monomer (2) represented by general formula (2) may be copolymerized with another monomer. The polymer (2) may be a homopolymer of the monomer represented by general formula (2) or a copolymer with another monomer.

[0182] In general formula (2), X is —H or F. Both Xs may be —F, or at least one X may be —H. For example, one X may be —F and the other may be —H, or both Xs may be —H.

[0183] In general formula (2), Y is -H, -F, an alkyl group, or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Y is -H, -F, or -CF ３ is preferred, and —F is more preferred.

[0184] In general formula (2), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0185] In general formula (2), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0186] The carbon number of the fluorine-containing alkylene group of Rf is preferably 2 or more, and more preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 5 or less. Examples of the fluorine-containing alkylene group include -CF ２ -, -CH ２ CF ２ -, -CF ２ CF ２ -, -CF ２ CH ２ -, -CF ２ CF ２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ -, -CF ２ CF ２ CF ２ -, CF ２ CF ２ CF ２ CF ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group, more preferably an unbranched linear perfluoroalkylene group.

[0187] The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, and particularly preferably 5 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: (In the formula, Z １ is F or CF ３ ;Z ２ and Z３ are H or F; Z ４ is H, F or CF ３ p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0188] Specific examples of the fluorine-containing alkylene group having an ether bond include —CF ２ CF (CF ３ ) OCF ２ -, -CF ２ CF (CF ３ ) OCF ２ CF ２ -, -CF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ -, -CF(CF ３ )CF ２ -O-CF(CF ３ )-,-(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ )-(wherein n is an integer from 1 to 10), -CF(CF ３ )CF ２ -O-CF(CF ３ ) CH ２ -, -(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ ) CH ２ - (wherein n is an integer of 1 to 10), -CH ２ CF ２ CF ２ O-CH ２ CF ２ CH ２ -, -CF ２ CF ２ CF ２ O-CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF２ CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ CH ２ -, -CF ２ CF ２ O-CF ２ -, -CF ２ CF ２ O-CF ２ CH ２ The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0189] The number of carbon atoms in the fluorine-containing alkylene group having a keto group is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having a keto group is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, and particularly preferably 5 or less.

[0190] Specific examples of the fluorine-containing alkylene group having a keto group include: ２ CF (CF ３ )CO-CF ２ -, -CF ２ CF (CF ３ )CO-CF ２ CF ２ -, -CF ２ CF (CF ３ )CO-CF ２ CF ２ CF ２ -, -CF ２ CF (CF ３ )CO-CF ２ CF ２ CF ２ CF ２ The fluorine-containing alkylene group having a keto group is preferably a perfluoroalkylene group.

[0191] Water may be added to the keto group in the fluorine-containing alkylene group. Therefore, the monomer (2) may be a hydrate. Examples of the fluorine-containing alkylene group in which water is added to the keto group include —CF ２ CF (CF ３ )C(OH)２ -CF ２ -, -CF ２ CF (CF ３ )C(OH) ２ -CF ２ CF ２ -, -CF ２ CF (CF ３ )C(OH) ２ -CF ２ CF ２ CF ２ -, -CF ２ CF (CF ３ )C(OH) ２ -CF ２ CF ２ CF ２ CF ２ - etc.

[0192] The monomer represented by general formula (2) is preferably at least one selected from the group consisting of monomers represented by general formulas (2a), (2b), (2c), (2d), (2e), (2f) and (2g). ２ =CF-O-(CF ２ ) ｎ１ -A (2a) (wherein n1 represents an integer of 1 to 10, and A is the same as defined above) CF ２ =CF-O-(CF ２ C (CF ３ ) F) ｎ２ -A (2b) (wherein n2 represents an integer of 1 to 5, and A is as defined above) CF ２ =CF-O-(CFX １ ) ｎ３ -A (2c) (wherein, X １ is F or CF ３ wherein n3 represents an integer of 1 to 10, and A is as defined above. ２ =CF-O-(CF ２ CFX １ O) ｎ４ -(CF ２ ) ｎ６ -A (2d) (wherein n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and A and X １ is the same as the definition above.) CF ２=CF-O-(CF ２ CF ２ CFX １ O) ｎ５ -CF ２ CF ２ CF ２ -A (2e) (wherein n5 represents an integer of 0 to 10, and A and X １ is the same as the definition above.) CF ２ =CF-O-(CF ２ ) ｎ７ -O-(CF ２ ) ｎ８ -A (2f) (wherein n7 represents an integer of 1 to 10, n8 represents an integer of 1 to 3, and A is as defined above.) CF ２ =CF[OCF ２ CF (CF ３ )] ｎ９ O (CF ２ ) ｎ１０ O[CF(CF ３ )CF ２ O] ｎ１１ CF (CF ３ )-A (2g) (wherein n9 represents an integer of 0 to 5, n10 represents an integer of 1 to 8, and n11 represents an integer of 0 to 5. A is as defined above.)

[0193] In the general formula (2a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less.

[0194] Examples of the monomer represented by general formula (2a) include CF ２ =CF-O-CF ２ COOM, C.F. ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(O(CF ２ ) ３ COOM), C.F. ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ = CFOCF ２ SO ３ M., C.F. ２ = CFOCF ２ CF２ CF ２ SO ３ M (wherein M is as defined above).

[0195] In general formula (2b), n2 is preferably an integer of 3 or less, from the viewpoint of the dispersion stability of the resulting composition.

[0196] In the general formula (2c), n3 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM, and M is preferably H, Na, or NH ４ It is preferable that:

[0197] In general formula (2d), X １ In terms of dispersion stability of the composition, -CF ３ n4 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM, and M is H, Na, or NH ４ It is preferable that:

[0198] Examples of the monomer represented by general formula (2d) include CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF３ ) OCF ２ CF ２ CF ２ SO ３ M (wherein M is H, NH ４ or an alkali metal.

[0199] In the general formula (2e), n5 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM, and M is preferably H or NH ４ It is preferable that:

[0200] Examples of the monomer represented by general formula (2e) include CF ２ = CFOCF ２ CF ２ CF ２ COOM (wherein M is H, Na, NH ４ or an alkali metal.

[0201] In the general formula (2f), n7 is preferably an integer of 5 or less in terms of water solubility, and A is -COOM or -SO ３ M is preferred, and -COOM is more preferred. M is H, Na, K or NH ４ It is preferable that:

[0202] Examples of the monomer represented by general formula (2f) include CF ２ =CF-O-(CF ２ ) ３ -O-CF ２ -COOM (wherein M is H, NH ４ or an alkali metal.

[0203] In the general formula (2g), n9 is preferably an integer of 3 or less in terms of water solubility, n10 is preferably an integer of 3 or less, n11 is preferably an integer of 3 or less, and A is -COOM or -SO ３ M is preferred, and -COOM is more preferred. M is H, Na, K or NH ４ It is preferable that:

[0204] Examples of the monomer represented by general formula (2g) include CF ２= CFO (CF ２ ) ２ OCF (CF ３ ) COOM, C.F. ２ = CFOCF ２ CF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ OCF (CF ３ ) COOM, C.F. ２ =CF[OCF ２ CF (CF ３ )] ２ O (CF ２ ) ２ O[CF(CF ３ )CF ２ O]CF(CF ３ ) COOM, C.F. ２ =CF[OCF ２ CF (CF ３ )] ３ O (CF ２ ) ２ O[CF(CF ３ )CF ２ O] ３ CF (CF ３ ) COOM (wherein M is H, NH ４ or an alkali metal.

[0205] The monomer (I) is preferably a monomer (3) represented by the general formula (3). The polymer (I) is preferably a polymer (3) containing a polymer unit (3) based on the monomer represented by the general formula (3). CX ２ =CY(-Rf-A) (3) (In the formula, X is the same or different and represents -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond; and A is the same as defined above.)

[0206] In the production method of the present disclosure, the monomer (3) represented by general formula (3) may be copolymerized with another monomer. The polymer (3) may be a homopolymer of the monomer represented by general formula (3) or a copolymer with another monomer.

[0207] The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0208] In general formula (3), Rf is preferably a fluorine-containing alkylene group having 1 to 40 carbon atoms. In general formula (3), at least one of X and Y preferably contains a fluorine atom.

[0209] The monomer represented by the general formula (3) is represented by the general formula (3a): CF ２ =CF-(CF ２ ) ｎ１ -A (3a) (wherein n1 represents an integer of 1 to 10, and A is as defined above), and a monomer represented by the general formula (3b): CF ２ =CF-(CF ２ C (CF ３ ) F) ｎ２ -A (3b) (wherein n2 represents an integer of 1 to 5, and A is as defined above) is preferred.

[0210] In the general formula (3a) and the general formula (3b), A is —SO ３ M or COOM is preferred, where M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. ７ represents H or an organic group.

[0211] In the general formula (3a), n1 is preferably an integer of 5 or less, more preferably an integer of 2 or less. A is preferably -COOM, and M is preferably H or NH. ４ It is preferable that:

[0212] Examples of the monomer represented by general formula (3a) include CF ２ =CFCF ２ COOM (wherein M is as defined above).

[0213] In the general formula (3b), n2 is preferably an integer of 3 or less from the viewpoint of dispersion stability of the resulting composition, A is preferably -COOM, and M is preferably H or NH ４ It is preferable that:

[0214] Next, a preferred structure when m in general formula (I) is an integer of 2 or more will be described.

[0215] It is also preferred that the monomer (I) is at least one selected from the group consisting of monomers represented by general formula (4a) and general formula (4b). It is also preferred that the polymer (I) is a polymer (4) containing polymerization units (4) based on at least one monomer selected from the group consisting of monomers represented by general formula (4a) and general formula (4b). CF ２ =CF-CF ２ -O-Q Ｆ１ -CF(-Q Ｆ２ -CZ １ Z ２ -A) ２ (4a) (wherein, Z １ , Z ２ and A is the same as defined above, Q Ｆ１ and Q Ｆ２ are the same or different and are a single bond, a fluorine-containing alkylene group which may contain an ether bond between carbon atoms, or a fluorine-containing oxyalkylene group which may contain an ether bond between carbon atoms. ２ =CF-O-Q Ｆ１ -CF(-Q Ｆ２ -CZ １ Z ２ -A) ２ (4b) (wherein, Z １ , Z ２ , A, Q Ｆ１ and Q Ｆ２ is the same as above)

[0216] The monomers represented by general formula (4a) and general formula (4b) include: etc.

[0217] The monomer (I) is preferably at least one selected from the group consisting of the monomer (1), the monomer (2), and the monomer (3), more preferably the monomer (1) or the monomer (2), and even more preferably the monomer (2). The polymer (I) is preferably at least one selected from the group consisting of the polymer (1), the polymer (2), and the polymer (3), more preferably the polymer (1) or the polymer (2), and even more preferably the polymer (2).

[0218] In the production method of the present disclosure, the monomer (I) may be copolymerized with another monomer. The polymer (I) may be a homopolymer consisting of only the polymerized unit (I), or may be a copolymer containing the polymerized unit (I) and a polymerized unit based on another monomer copolymerizable with the monomer represented by general formula (I). From the viewpoint of solubility in an aqueous medium, a homopolymer consisting of only the polymerized unit (I) is preferred. The polymerized units (I) may be the same or different in each occurrence, and the polymer (I) may contain polymerized units (I) based on two or more different monomers represented by general formula (I).

[0219] The other monomers include those represented by the general formula CFR=CR ２ (wherein R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms) is preferred. As the other monomer, a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms is preferred. As the other monomer, for example, CF ２ =CF ２ , C.F. ２ = CFCl, CH ２ =CF ２ , CFH=CH ２ , CFH=CF ２ , C.F. ２ =CFCF ３ , C.H. ２ =CFCF ３ , C.H. ２ = CHCF ３ , CHF=CHCF ３ (E form), CHF=CHCF ３Among them, tetrafluoroethylene (CF ２ =CF ２ ), chlorotrifluoroethylene (CF ２ =CFCl) and vinylidene fluoride (CH ２ =CF ２ ), and more preferably at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride. Therefore, the polymerized units based on the other monomer are preferably polymerized units based on tetrafluoroethylene. The polymerized units based on the other monomer may be the same or different in each occurrence, and polymer (I) may contain polymerized units based on two or more different other monomers.

[0220] The other monomers also include those represented by the general formula (n1-2):

[0221]

[0222] (In the formula, X １ , X ２ are the same or different and are H or F; X ３ are H, F, Cl, CH ３ or CF ３ ;X ４ , X ５ are the same or different and are H or F; a and c are the same or different and are 0 or 1. ３ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0223] Specifically, CH ２ =CFCF ２ -O-Rf ３ , C.F. ２ ═CF—O—Rf ３ , C.F. ２ =CFCF ２ -O-Rf ３ , C.F. ２ =CF-Rf ３ , C.H. ２ =CH-Rf ３ , C.H. ２=CH-O-Rf ３ (In the formula, Rf ３ is the same as the above formula (n1-2).

[0224] Examples of the other monomer include a monomer of the formula (n2-1):

[0225]

[0226] (In the formula, X ９ is H, F or CH ３ ; Rf ４ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond). ４ The base is

[0227]

[0228] (wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10).

[0229] Examples of the other monomer include a monomer represented by formula (n2-2): CH ２ =CHO-Rf ５ (n2-2) (wherein, Rf ５ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond), and

[0230] Specific examples of the monomer of general formula (n2-2) include:

[0231]

[0232] (wherein e6 is an integer of 1 to 10) are preferred.

[0233] More specifically,

[0234]

[0235] Examples include:

[0236] Others include those represented by the general formula (n2-3): CH ２ =CHCH ２ O-Rf ６ (n2-3) (wherein, Rf６ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and an ether bond), a fluorine-containing allyl ether represented by the general formula (n2-4): CH ２ =CH-Rf ７ (n2-4) (wherein, Rf ７ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond), and the like.

[0237] Specific examples of the monomers represented by general formulas (n2-3) and (n2-4) include:

[0238]

[0239] Examples of such monomers include:

[0240] The polymer (I) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and typical terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used in forming the polymer (I) or during the chain transfer reaction.

[0241] In the polymer (I), the content of the polymerized units (I) relative to the total polymerized units is, in order of preference, 1.0 mol% or more, 3.0 mol% or more, 5.0 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, and 90 mol% or more. The content of the polymerized units (I) is particularly preferably substantially 100 mol%, and the polymer (I) is most preferably composed only of the polymerized units (I).

[0242] In the polymer (I), the content of polymerization units based on other monomers copolymerizable with the monomer represented by general formula (I) is, in order of preference, 99.0 mol% or less, 97.0 mol% or less, 95.0 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, and 10 mol% or less, based on all polymerization units. It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer represented by general formula (I) is substantially 0 mol%, and it is most preferable that the polymer (I) does not contain polymerization units based on other monomers.

[0243] The number average molecular weight of the polymer (I) is 0.1 × 10 ４ More than 0.2 × 10 ４ More preferably, 0.3 × 10 ４ More preferably, 0.4 × 10 ４ More preferably, 0.5 × 10 ４ More preferably, 1.0 x 10 ４ More preferably, 3.0 × 10 ４ More particularly, 3.1 × 10 ４ More than 75.0×10 is most preferable. ４ Preferably, 50.0 x 10 ４ More preferably, 40.0 x 10 ４ More preferably, 30.0 x 10 ４ The following is particularly preferred: 20.0 x 10 ４ The following are particularly preferred. The number average molecular weight and weight average molecular weight are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. When measurement by GPC is not possible, the number average molecular weight of polymer (I) can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0244] The lower limit of the weight average molecular weight of the polymer (I) is, in order of preference, 0.2 × 10 ４ That's it, 0.4 x 10４ That's it, 0.6 x 10 ４ That's it, 0.8 x 10 ４ That's it, 1.0 x 10 ４ That's it, 2.0 x 10 ４ That's it, 5.0 x 10 ４ That's it, 10.0 x 10 ４ That's it, 15.0 x 10 ４ That's it, 20.0 x 10 ４ That's it, 25.0 x 10 ４ The upper limit of the weight average molecular weight of the polymer (I) is preferably 150.0×10 ４ Below, 100.0 x 10 ４ Below, 60.0 x 10 ４ Below, 50.0 x 10 ４ Below, 40.0 x 10 ４ The following is the result.

[0245] The polymer (I) preferably has an ion exchange ratio (IXR) of 53 or less. The IXR is defined as the number of carbon atoms in the polymer backbone relative to the ionic group. ２ F) is not considered an ionizable group for purposes of determining IXR.

[0246] IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and particularly preferably 8 or more. IXR is more preferably 43 or less, more preferably 33 or less, and particularly preferably 23 or less.

[0247] The ion exchange capacity of the polymer (I) is, in order of preference, 0.80 meq / g or more, 1.50 meq / g or more, 1.75 meq / g or more, 2.00 meq / g or more, 2.20 meq / g or more, more than 2.20 meq / g, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (I) and is calculated from the composition of the polymer (I).

[0248] In polymer (I), the ionic (anionic) groups are typically distributed along the polymer backbone. The polymer (I) comprises a polymer backbone with recurring side chains attached to the backbone, which preferably carry ionic groups.

[0249] Preferably, polymer (I) comprises ionizable groups having a pKa of less than 10, more preferably less than 7. The ionizable groups of polymer (I) are preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, and phosphate.

[0250] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or the respective acids capable of forming salts. When salts are used, the salts are preferably alkali metal or ammonium salts. Preferred ionic groups are carboxylate and sulfonate groups.

[0251] The polymer (I) is preferably water-soluble. Water-soluble means the property of being easily dissolved or dispersed in an aqueous medium. The particle size of the water-soluble polymer (I) cannot be measured by dynamic light scattering (DLS), for example, or the particle size is 10 nm or less.

[0252] The viscosity of an aqueous solution of polymer (I) is preferably 5.0 mPa.s or more, more preferably 8.0 mPa.s or more, even more preferably 10.0 mPa.s or more, particularly preferably 12.0 mPa.s or more, and most preferably 14.0 mPa.s or more, and is preferably 100.0 mPa.s or less, more preferably 50.0 mPa.s or less, even more preferably 25.0 mPa.s or less, and especially preferably 20.0 mPa.s or less.

[0253] The viscosity of the aqueous solution of polymer (I) can be determined by adjusting the content of polymer (I) in the aqueous solution to 33 mass % based on the aqueous solution, and measuring the viscosity of the obtained aqueous solution at 20°C using a tuning fork vibro viscometer (model number: SV-10) manufactured by A&D Co., Ltd.

[0254] The critical micelle concentration (CMC) of the polymer (I) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less.

[0255] The critical micelle concentration of the polymer (I) can be determined by measuring the surface tension, for example, using a surface tensiometer DY-300 manufactured by Kyowa Interface Science Co., Ltd.

[0256] The acid value of the polymer (I) is preferably 60 or more, more preferably 90 or more, even more preferably 120 or more, particularly preferably 150 or more, and most preferably 180 or more. The upper limit is not particularly limited, but is preferably 300 or less.

[0257] The acid value of the polymer (I) is determined by the amount of anionic groups other than the acid functional groups, such as —COOM and —SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ When the compound has a group (H or an organic group), these groups can be converted into acid groups and then measured by acid-base titration.

[0258] (Aqueous Medium) The aqueous medium is a reaction medium for polymerization and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less. Water is preferred as the aqueous medium.

[0259] (Fluoromonomer) The fluoromonomer used in the manufacturing method of the present disclosure is preferably one that has at least one double bond.As the fluoromonomer, tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinyl fluoride, vinylidene fluoride [VDF], trifluoroethylene, fluoroalkyl vinyl ether, fluoroalkyl ethylene, fluoroalkyl allyl ether, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, general formula (100): CHX １０１ =CX １０２ Rf １０１ (In the formula, X １０１ and X １０２ is H on one side and F on the other side, and Rf １０１ is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), a fluorinated vinyl heterocycle, and a monomer that provides a crosslinking site.

[0260] Examples of the fluoroalkyl vinyl ether include those represented by the general formula (110): CF ２ =CF-ORf １１１ (In the formula, Rf １１１ represents a perfluoroorganic group.) A fluoromonomer represented by general formula (120): CF ２ =CF-OCH ２ -Rf １２１ (In the formula, Rf １２１ is a perfluoroalkyl group having 1 to 5 carbon atoms), a fluoromonomer represented by the general formula (130): CF ２ = CFOCF ２ ORf １３１ (In the formula, Rf １３１ is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms.) Fluoromonomers represented by general formula (140): CF ２ = CFO (CF２ CF (Y １４１ ) O) ｍ (CF ２ ) ｎ F (wherein, Y １４１ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.) and a fluoromonomer represented by the general formula (150): CF ２ =CF-O-(CF ２ CFY １５１ -O) ｎ -(CFY １５２ ) ｍ -A １５１ (In the formula, Y １５１ represents a fluorine atom, a chlorine atom, -SO ２ It represents a F group or a perfluoroalkyl group. The perfluoroalkyl group is an etheric oxygen and -SO ２ The group n may contain an F group. n represents an integer of 0 to 3. １５１ may be the same or different. １５２ represents a fluorine atom, a chlorine atom, or —SO ２ represents an F group, and m represents an integer of 1 to 5. １５２ may be the same or different. １５１ is -SO ２ X １５１ , -COZ １５１ or -POZ １５２ Z １５３ represents. １５１ is F, Cl, Br, I, -OR １５１ or -NR １５２ R １５３ Represents Z. １５１ , Z １５２ and Z １５３ are the same or different and represent -NR １５４ R １５５ Or -OR １５６ Represents R １５１ , R １５２ , R １５３ , R １５４ , R １５５ and R １５６are the same or different and represent H, ammonium, an alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group.

[0261] In the present disclosure, the term "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen atom.

[0262] The fluoromonomer represented by the general formula (110) is Rf １１１ is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0263] Examples of the perfluoroorganic group in the general formula (110) include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. The fluoromonomer represented by the general formula (110) further includes a fluoromonomer represented by the general formula (110) in which Rf １１１ is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf １１１ is of the following formula:

[0264]

[0265] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0266] CF ３ CF ２ CF ２ -(O-CF(CF ３ )-CF ２ ) ｎ - (wherein n represents an integer of 1 to 4).

[0267] Among the fluoromonomers represented by the general formula (110), those represented by the general formula (160): CF ２ =CF-ORf １６１ (In the formula, Rf１６１ Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. １６１ is preferably a perfluoroalkyl group having 1 to 5 carbon atoms.

[0268] The fluoroalkyl vinyl ether is preferably at least one selected from the group consisting of fluoromonomers represented by the general formulas (160), (130) and (140).

[0269] The fluoromonomer represented by general formula (160) is preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), and more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether).

[0270] The fluoromonomer represented by the general formula (130) is CF ２ = CFOCF ２ OCF ３ , C.F. ２ = CFOCF ２ OCF ２ CF ３ , and CF ２ = CFOCF ２ OCF ２ CF ２ OCF ３ It is preferable that the polymer is at least one selected from the group consisting of:

[0271] The fluoromonomer represented by the general formula (140) is CF ２ = CFOCF ２ CF (CF ３ ) O(CF ２ ) ３ F, CF ２ = CFO (CF ２ CF (CF ３ ) O) ２ (CF ２ ) ３ F and CF ２ = CFO (CF ２ CF (CF３ ) O) ２ (CF ２ ) ２ It is preferable that the compound is at least one selected from the group consisting of F.

[0272] The fluoromonomer represented by the general formula (150) is CF ２ = CFOCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF ２ CF ２ SO ２ F) OCF ２ CF ２ SO ２ F and CF ２ = CFOCF ２ CF (SO ２ F) ２ At least one selected from the group consisting of:

[0273] The fluoromonomer represented by the general formula (100) is Rf １０１ is a linear fluoroalkyl group, and Rf １０１ More preferred is a fluoromonomer in which Rf is a linear perfluoroalkyl group. １０１ The number of carbon atoms of the fluoromonomer represented by the general formula (100) is preferably 1 to 6. ２ =CFCF ３ , C.H. ２ =CFCF ２ CF ３ , C.H. ２ =CFCF ２ CF ２ CF ３ , C.H. ２ =CFCF ２ CF ２ CF ２ H, CH ２ =CFCF ２ CF ２CF ２ CF ３ , CHF=CHCF ３ (E form), CHF=CHCF ３ (Z-isomer), among which CH ２ =CFCF ３ Preferred is 2,3,3,3-tetrafluoropropylene represented by the following formula:

[0274] The fluoroalkylethylene includes those represented by the general formula (170): CH ２ =CH-(CF ２ ) ｎ -X １７１ (In the formula, X １７１ is H or F, and n is an integer of 3 to 10.) is preferred, and CH ２ =CH-C ４ F ９ , and C.H. ２ =CH-C ６ F １３ It is more preferable that the polymer is at least one selected from the group consisting of:

[0275] The fluoroalkyl allyl ether is, for example, a compound represented by the general formula (180): CF ２ =CF-CF ２ -ORf １１１ (In the formula, Rf １１１ represents a perfluoroorganic group.

[0276] Rf of general formula (180) １１１ is Rf in general formula (110). １１１ Rf is the same as １１１ As the fluoroalkyl aryl ether represented by the general formula (180), a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. ２ =CF-CF ２ -O-CF ３ , C.F. ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ At least one selected from the group consisting of CF ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ =CF-CF ２ -O-CF ２ CF ２ CF ３ is more preferable.

[0277] The fluorinated vinyl heterocycle may be a heterocyclic compound represented by the general formula (230): (In the formula, X ２３１ and X ２３２ are independently F, Cl, a methoxy group, or a fluorinated methoxy group; Y ２３１ is the formula Y ２３２ or formula Y ２３３ is.

[0278] (In the formula, Z ２３１ and Z ２３２ are independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0279] The monomer that provides the crosslinking site is represented by the general formula (180): CX １８１ ２ =CX １８２ -R ｆ １８１ CHR １８１ X １８３ (In the formula, X １８１ and X １８２ are independently a hydrogen atom, a fluorine atom, or CH ３ , R ｆ１８１ represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, R １８１ is a hydrogen atom or CH ３ , X １８３ is an iodine atom or a bromine atom.) A fluoromonomer represented by the general formula (190): CX １９１ ２ =CX １９２ -R ｆ １９１ X １９３ (In the formula, X １９１ and X １９２ are independently a hydrogen atom, a fluorine atom, or CH ３ , R ｆ １９１ represents a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group, X １９３ is an iodine atom or a bromine atom.) A fluoromonomer represented by the general formula (200): CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -X ２０１ (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X ２０１ represents a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ I.) and a fluoromonomer represented by the general formula (210): CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｍ (CF (CF ３ )) ｎ -X ２１１ (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X ２１１ represents a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ OH.) and a fluoromonomer represented by the general formula (220): CR ２２１ R２２２ =CR ２２３ -Z ２２１ -CR ２２４ =CR ２２５ R ２２６ (In the formula, R ２２１ , R ２２２ , R ２２３ , R ２２４ , R ２２５ and R ２２６ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ２２１ -(Q) is a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 3 to 18 carbon atoms, or an at least partially fluorinated alkylene or oxyalkylene group having 1 to 10 carbon atoms, which may contain an oxygen atom; ｐ -CF ２ O-(CF ２ CF ２ O) ｍ (CF ２ O) ｎ -CF ２ -(Q) ｐ - (wherein Q is an alkylene group or an oxyalkylene group, p is 0 or 1, and m / n is 0.2 to 5), and is a (per)fluoropolyoxyalkylene group having a molecular weight of 500 to 10,000.

[0280] X １８３ and X １９３ is preferably an iodine atom. ｆ １８１ and R ｆ １９１ is preferably a perfluoroalkylene group having 1 to 5 carbon atoms. １８１ is preferably a hydrogen atom. ２０１ represents a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ Preferably, X is I. ２１１ represents a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ It is preferably OH.

[0281] The monomer that provides the crosslinking site is CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ I, CF ２ = CFOCF ２ CF ２ CH ２ I, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CN, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOH, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CH ２ OH, CH ２ = CHCF ２ CF ２ I, CH ２ =CH(CF ２ ) ２ CH=CH ２ , C.H. ２ =CH(CF ２ ) ６ CH=CH ２ , and CF ２ = CFO (CF ２ ) ５ CN, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF２ CN and CF ２ = CFOCF ２ CF ２ CH ２ It is more preferable that the compound is at least one selected from the group consisting of I.

[0282] In the polymerization, the fluoromonomer and a fluorine-free monomer may be polymerized. Examples of the fluorine-free monomer include hydrocarbon-based monomers reactive with the fluoromonomer. Examples of the hydrocarbon-based monomer include alkenes such as ethylene, propylene, butylene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl para-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, and vinyl hydroxybenzoates. vinyl esters such as vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, and vinyl hydroxycyclohexanecarboxylate; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, and cyclohexyl allyl ester; and (meth)acrylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, and vinyl methacrylate.

[0283] The above-mentioned fluorine-free monomer may also be a functional group-containing hydrocarbon monomer (however, excluding the monomer that provides crosslinking site).The above-mentioned functional group-containing hydrocarbon monomer may be, for example, hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, hydroxycyclohexyl vinyl ether, etc.; fluorine-free monomers having carboxyl groups such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, perfluorobutenoic acid, etc.; fluorine-free monomers having sulfo groups such as vinyl sulfonic acid, etc.; fluorine-free monomers having glycidyl groups such as glycidyl vinyl ether, glycidyl allyl ether, etc.; fluorine-free monomers having amino groups such as aminoalkyl vinyl ether, aminoalkyl allyl ether, etc.; fluorine-free monomers having amide groups such as (meth)acrylamide, methylol acrylamide, etc.; fluorine-free monomers having nitrile groups such as acrylonitrile, methacrylonitrile, etc.

[0284] In the above polymerization, one or more of the above fluoromonomers are polymerized to obtain particles of the desired fluoropolymer.

[0285] (Polymerization) The polymerization of fluoromonomer is carried out in the presence of polymer (I). The amount of polymer (I) added in the polymerization is preferably more than 0.02 mass% and not more than 10 mass% relative to the aqueous medium, and the more preferred upper limit is not more than 1 mass%. By setting the amount of polymer (I) added within the above range, the polymerization of fluoromonomer in the aqueous medium can be smoothly carried out. The amount of polymer (I) added is the total amount of polymer (I) added in the polymerization.

[0286] In the polymerization, the polymer (I) may be added all at once, or the polymer (I) may be added continuously. Continuous addition of the polymer (I) means, for example, adding the polymer (I) over time, without interruption, or in portions, rather than all at once. In the polymerization, an aqueous solution containing the polymer (I) and water may be prepared, and the aqueous solution may be added.

[0287] In the above polymerization, it is preferable to start adding polymer (I) before the solid content of the fluoropolymer formed in the aqueous medium reaches 0.5 mass%, and then continue to add polymer (I) continuously.The timing of starting adding polymer (I) is preferably before the solid content of the fluoropolymer reaches 0.3 mass%, more preferably before it reaches 0.2 mass%, even more preferably before it reaches 0.1 mass%, and particularly preferably at the same time as the start of polymerization.The above solid content is the content of the fluoropolymer relative to the total of the aqueous medium and the fluoropolymer.

[0288] In the above polymerization, if at least one polymer (I) is used, it is possible to efficiently produce a fluoropolymer. In addition, two or more compounds included in the polymer (I) may be used simultaneously, and other surfactant compounds other than the polymer (I) may be used simultaneously, as long as they are volatile or may remain in a molded product made of the fluoropolymer.

[0289] In the polymerization, a nucleating agent may be used. The amount of the nucleating agent added can be appropriately selected depending on the type of the nucleating agent. The amount of the nucleating agent added may be 5000 ppm by mass or less, preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, particularly preferably 50 ppm by mass or less, and most preferably 10 ppm by mass or less, relative to the aqueous medium.

[0290] In the above polymerization, it is preferable to add a nucleating agent to the aqueous medium before the start of polymerization or before the solid content of the fluoropolymer formed in the aqueous medium reaches 5.0 mass %. By adding the nucleating agent at the early stage of polymerization, an aqueous dispersion having a small average primary particle size and excellent stability can be obtained.

[0291] The amount of the nucleating agent added at the beginning of polymerization is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more, based on the amount of the fluoropolymer to be obtained. The upper limit of the amount of the nucleating agent added at the beginning of polymerization is not limited, but is, for example, 2000% by mass.

[0292] The use of a nucleating agent results in a fluoropolymer having a smaller primary particle size compared to polymerization carried out in the absence of said nucleating agent.

[0293] Examples of the nucleating agent include dicarboxylic acids, perfluoropolyether (PFPE) acids or salts thereof, hydrocarbon-containing surfactants, etc. The nucleating agent preferably does not contain an aromatic ring and is preferably an aliphatic compound.

[0294] The nucleating agent is preferably added before or simultaneously with the addition of the polymerization initiator, but the particle size distribution can also be adjusted by adding it during the polymerization.

[0295] The amount of the dicarboxylic acid is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 100 ppm by mass or less, relative to the aqueous medium.

[0296] The perfluoropolyether (PFPE) acid or salt thereof may have any chain structure in which oxygen atoms in the main chain of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. Also, two or more types of fluorocarbon groups may be present in the molecule. A representative structure has a repeating unit represented by the following formula: (-CFCF ３ -CF ２ -O-) ｎ(VII) (-CF ２ -CF ２ -CF ２ -O-) ｎ (VIII) (-CF ２ -CF ２ -O-) ｎ -(-CF ２ -O-) ｍ (IX) (-CF ２ -CFCF ３ -O-)n-(-CF ２ -O-) ｍ (X)

[0297] These structures are described by Kasai in J. Appl. Polymer Sci. 57, 797 (1995). As disclosed therein, the PFPE acid or its salt may have a carboxylic acid group or its salt at one or both termini. The PFPE acid or its salt may also have a sulfonic acid or phosphonic acid group or their salt at one or both termini. The PFPE acid or its salt may also have a different group at each terminus. For monofunctional PFPEs, the other terminus of the molecule is usually perfluorinated but may contain a hydrogen or chlorine atom. The PFPE acid or its salt has at least two ether oxygens, preferably at least four ether oxygens, and even more preferably at least six ether oxygens. Preferably, at least one of the fluorocarbon groups separating the ether oxygens, more preferably at least two of such fluorocarbon groups, has two or three carbon atoms. Even more preferably, at least 50% of the fluorocarbon groups separating the ether oxygens have 2 or 3 carbon atoms. Also preferably, the PFPE acid or salt thereof has a total of at least 15 carbon atoms, for example, the preferred minimum value of n or n+m in the repeating unit structure is at least 5. Two or more of the PFPE acids or salts thereof having acid groups at one or both termini may be used in the manufacturing method of the present disclosure. The PFPE acid or salt thereof preferably has a number average molecular weight of less than 6,000 g / mol.

[0298] The amount of the hydrocarbon-containing surfactant added is preferably 40 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 20 ppm by mass or less, relative to the aqueous medium. It is estimated that the ppm amount of lipophilic nucleation sites present in the aqueous medium is less than the amount added. Therefore, the amount of lipophilic nucleation sites is less than the above-mentioned 40 ppm by mass, 30 ppm by mass, and 20 ppm by mass. Since the lipophilic nucleation sites are thought to exist as molecules, even a small amount of the hydrocarbon-containing surfactant can generate a large amount of lipophilic nucleation sites. Therefore, beneficial effects can be obtained by adding only about 1 ppm by mass of the hydrocarbon-containing surfactant to the aqueous medium. The preferred lower limit is 0.01 ppm by mass.

[0299] The hydrocarbon-containing surfactants include nonionic and cationic surfactants, including siloxane surfactants such as those disclosed in U.S. Pat. No. 7,897,682 (Brothers et al.) and U.S. Pat. No. 7,977,438 (Brothers et al.).

[0300] The hydrocarbon-containing surfactant is preferably a nonionic surfactant (e.g., a nonionic hydrocarbon surfactant). That is, the nucleating agent is preferably a nonionic surfactant. The nonionic surfactant preferably does not contain an aromatic moiety.

[0301] Examples of the nonionic surfactant include nonionic surfactants that may be contained in the pre-concentration composition.

[0302] In the polymerization, a compound having a functional group capable of reacting by radical polymerization and a hydrophilic group may be used together with the polymer (I). As the compound having a functional group capable of reacting by radical polymerization and a hydrophilic group, the same compound as the modifying monomer (A) described below can be used.

[0303] In the polymerization, in addition to the polymer (I) and other surfactant compounds used as desired, additives for stabilizing each compound can be used, such as buffers, pH adjusters, stabilizing aids, and dispersion stabilizers.

[0304] Preferred stabilizing aids include paraffin wax, fluorine-based oil, fluorine-based solvent, and silicone oil. The stabilizing aids may be used alone or in combination of two or more. Paraffin wax is more preferred as the stabilizing aid. Paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons having 12 or more carbon atoms are preferred. The melting point of the paraffin wax is generally preferably 40 to 65°C, more preferably 50 to 65°C.

[0305] The amount of the stabilizing aid used is preferably 0.1 to 12% by mass, more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing aid is sufficiently hydrophobic so that it is completely separated from the aqueous dispersion after polymerization and does not become a contaminating component.

[0306] The polymerization is carried out by charging an aqueous medium, the polymer (I), a monomer, and other additives as necessary into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of a polymerization initiator to initiate the polymerization reaction. After the polymerization reaction has started, additional monomers, polymerization initiators, chain transfer agents, polymer (I), etc. may be added depending on the purpose. The polymer (I) may also be added after the polymerization reaction has started.

[0307] Usually, the polymerization temperature is 5 to 120° C., and the polymerization pressure is 0.05 to 10 MPaG. The polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0308] The polymerization initiator is not particularly limited as long as it can generate radicals within the polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, it can also be combined with a reducing agent or the like to initiate polymerization as a redox. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate.

[0309] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0310] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. Also usable are di(ω-hydro-dodecafluorohexanoyl) peroxide, di(ω-hydro-tetradecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluorovaleryl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as di(ω-chlorohexafluorobutyryl)peroxide, di(ω-chlorodecafluorohexanoyl)peroxide, di(ω-chlorotetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0311] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate; organic peroxides such as disuccinic acid peroxide or diglutaric acid peroxide; t-butyl permaleate; t-butyl hydroperoxide; etc. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0312] For example, when polymerization is carried out at a low temperature of 30°C or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of redox initiators. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0313] Examples of the redox initiator include potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, and bromate / bisulfite, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate thereto.

[0314] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously at the beginning of polymerization in an amount (for example, several ppm relative to water concentration) that does not significantly decrease the polymerization rate. The upper limit is a range in which the reaction temperature can be increased while removing heat from the equipment using the heat of polymerization reaction, and a more preferred upper limit is a range in which the heat of polymerization reaction can be removed from the equipment.

[0315] In the above polymerization, known chain transfer agents, radical scavengers and decomposers may be added depending on the purpose to adjust the polymerization rate and molecular weight.

[0316] Examples of the chain transfer agent include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, methanol, isopropanol, acetone, various mercaptans, various halogenated hydrocarbons such as carbon tetrachloride, and cyclohexane.

[0317] Bromine compounds or iodine compounds may be used as chain transfer agents. The polymerization method using a bromine compound or an iodine compound may, for example, be a method of polymerizing a fluoromonomer in an aqueous medium in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the bromine compound or iodine compound to be used include, for example, compounds represented by the general formula: R ａ I ｘ Br ｙ (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R ａ is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom). By using a bromine compound or an iodine compound, iodine or bromine is introduced into the polymer and functions as a crosslinking point.

[0318] Examples of bromine compounds or iodine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF ２ Br ２ , BrCF ２ CF ２ Br, CF ３ CFBrCF ２ Br, CFClBr ２ , BrCF ２ CFClBr, CFBrClCFClBr, BrCF ２ CF ２ CF ２ Br, BrCF ２ CFBrOCF ３ , 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl) substituted benzenes, and these compounds may be used alone or in combination with each other.

[0319] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0320] The amount of the chain transfer agent used is usually 1 to 50,000 ppm by mass, preferably 1 to 20,000 ppm by mass, based on the total amount of fluoromonomers supplied.

[0321] The chain transfer agent may be added all at once to the reaction vessel before the initiation of polymerization, may be added all at once after the initiation of polymerization, may be added in multiple divided portions during the polymerization, or may be added continuously during the polymerization.

[0322] As the polymerization initiator, persulfates (e.g., ammonium persulfate), or organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0323] In the above polymerization, a fluoromonomer may be polymerized in an aqueous medium in the presence of polymer (I) to produce an aqueous dispersion of fluoropolymer particles, and the fluoromonomer may be seed-polymerized to the fluoropolymer particles in the aqueous dispersion of fluoropolymer particles to obtain a fluoropolymer.

[0324] The polymerization is preferably carried out by polymerizing a fluoromonomer in the substantial absence of a fluorine-containing surfactant (excluding compounds having a functional group capable of reacting by radical polymerization and a hydrophilic group). Conventionally, a fluorine-containing surfactant has been used for the polymerization of a fluoromonomer in an aqueous medium, but according to the production method of the present disclosure, a fluoropolymer can be obtained even without using a fluorine-containing surfactant.

[0325] In the present disclosure, "substantially in the absence of a fluorinated surfactant" means that the amount of the fluorinated surfactant relative to the aqueous medium is 10 ppm by mass or less. The amount of the fluorinated surfactant relative to the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and still more preferably 1 ppb by mass or less.

[0326] Examples of the fluorine-containing surfactant include anionic fluorine-containing surfactants, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms and having a total carbon number of 20 or less excluding the anionic group.

[0327] The fluorine-containing surfactant may also be a surfactant containing fluorine, the molecular weight of the anionic moiety of which is 1,000 or less. The "anionic moiety" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF) represented by the formula (I) below may be used. ２ ) ｎ１ In the case of COOM, "F(CF ２ ) ｎ１ This is the "COO" part.

[0328] The fluorine-containing surfactant also includes a fluorine-containing surfactant having a Log POW of 3.5 or less. The Log POW is the partition coefficient between 1-octanol and water, and is expressed as Log P [where P represents the ratio of the fluorine-containing surfactant concentration in octanol to the fluorine-containing surfactant concentration in water when a 1:1 octanol / water mixture containing the fluorine-containing surfactant undergoes phase separation]. The Log POW can be measured using a column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), an eluent: acetonitrile / 0.6% by mass HClO ４ HPLC is performed on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) with known octanol / water partition coefficients under conditions of water=1 / 1 (vol / vol %), flow rate: 1.0 ml / min, sample amount: 300 μL, column temperature: 40°C, and detection light: UV 210 nm. A calibration curve is prepared between each elution time and the known octanol / water partition coefficient, and the elution time is calculated from the HPLC elution time of the sample solution based on this calibration curve.

[0329] Specific examples of the fluorine-containing surfactants include those described in U.S. Patent Application Publication Nos. 2007 / 0015864, 2007 / 0015865, 2007 / 0015866, 2007 / 0276103, 2007 / 0117914, 2007 / 142541, 2008 / 0015319, and U.S. Pat. No. 3,250,808. , U.S. Patent No. 3,271,341, JP 2003-119204 A, WO 2005 / 042593, WO 2008 / 060461, WO 2007 / 046377, JP 2007-119526 A, WO 2007 / 046482, WO 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, WO 2013 / 189824, and those described in WO 2013 / 189826, and the like.

[0330] The anionic fluorine-containing surfactant may be a compound represented by the following general formula (N ０ ): X ｎ０ -Rf ｎ０ -Y ０ (N ０ ) (wherein, X ｎ０ is H, Cl or F. ｎ０ is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H atoms are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H atoms may be substituted with Cl. ０ is an anionic group. ０ The anionic group is -COOM, -SO ２ M or -SO ３ M, -COOM or -SO ３ M. M may be H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７is H or an organic group. The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. ７ As the group, H or C １－１０ and may be an organic group of the formula: １－４ and may be an organic group of the formula: １－４ M may be H, a metal atom, or an alkyl group of the formula NR ７ ４ may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR ７ ４ may be H, Na, K, Li or NH ４ The above Rf ｎ０ may be one in which 50% or more of H is substituted with fluorine.

[0331] The general formula (N ０ The compound represented by the following general formula (N １ ): X ｎ０ -(CF ２ ) ｍ１ -Y ０ (N １ ) (wherein, X ｎ０ is H, Cl, and F, m1 is an integer from 3 to 15, and Y ０ is as defined above), a compound represented by the following general formula (N ２ ): Rf ｎ１ -O-(CF(CF ３ )CF ２ O) ｍ２ CFX ｎ１ -Y ０ (N ２ ) (wherein, Rf ｎ１ is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X ｎ１ is F or CF ３ and Y ０ is as defined above), a compound represented by the following general formula (N ３ ): Rf ｎ２ (CH ２ ) ｍ３ -(Rf ｎ３ ) ｑ-Y ０ (N ３ ) (wherein, Rf ｎ２ is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, m3 is an integer of 1 to 3, and Rf ｎ３ is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y ０ is as defined above), a compound represented by the following general formula (N ４ ): Rf ｎ４ -O-(CY ｎ１ Y ｎ２ ) ｐ CF ２ -Y ０ (N ４ ) (wherein, Rf ｎ４ is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain ether bonds and / or chlorine atoms; Y ｎ１ and Y ｎ２ are the same or different and are H or F, p is 0 or 1, and Y ０ is as defined above.) and a compound represented by the general formula (N ５ ): (In the formula, X ｎ２ , X ｎ３ and X ｎ４ Rf may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether linkage. ｎ５ is a linear or branched partially or fully fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y ０ is as defined above, where X ｎ２ , X ｎ３ , X ｎ４ and Rf ｎ５ wherein the total number of carbon atoms is 18 or less.

[0332] The general formula (N ０) More specifically, the compounds represented by the formula (I) below include perfluorocarboxylic acids (I), ω-H perfluorocarboxylic acids (II), perfluoroether carboxylic acids (III), perfluoroalkyl alkylene carboxylic acids (IV), perfluoroalkoxy fluorocarboxylic acids (V), perfluoroalkyl sulfonic acids (VI), ω-H perfluoro sulfonic acids (VII), perfluoroalkyl alkylene sulfonic acids (VIII), alkyl alkylene carboxylic acids (IX), fluorocarboxylic acids (X), alkoxy fluorosulfonic acids (XI), alkoxy fluorosulfonic acids (XI), and the like.

[0333] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF ２ ) ｎ１ COOM (I) (wherein n1 is an integer of 3 to 14, and M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.

[0334] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF ２ ) ｎ２ COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0335] The perfluoroethercarboxylic acid (III) is a compound represented by the following general formula (III): １ -O-(CF(CF ３ )CF ２ O) ｎ３CF (CF ３ ) COOM (III) (wherein, Rf １ is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.

[0336] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): ２ (CH ２ ) ｎ４ Rf ３ COOM (IV) (wherein, Rf ２ is a perfluoroalkyl group having 1 to 5 carbon atoms, and Rf ３ is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.

[0337] The alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf ４ -O-CY １ Y ２ CF ２ -COOM (V) (wherein, Rf ４ is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain ether bonds and / or chlorine atoms; Y １ and Y ２ are the same or different and are H or F, and M is as defined above.

[0338] The perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI): F(CF ２ ) ｎ５ SO ３ M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0339] The ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII): H(CF ２ ) ｎ６ SO ３M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0340] The perfluoroalkyl alkylene sulfonic acid (VIII) is a compound represented by the following general formula (VIII): ５ (CH ２ ) ｎ７ SO ３ M (VIII) (wherein, Rf ５ is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer of 1 to 3, and M is as defined above.

[0341] The alkyl alkylene carboxylic acid (IX) is represented by the following general formula (IX): ６ (CH ２ ) ｎ８ COOM (IX) (wherein, Rf ６ is a linear or branched partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer from 1 to 3, and M is as defined above.

[0342] The fluorocarboxylic acid (X) is represented by the following general formula (X): ７ -O-Rf ８ -O-CF ２ -COOM (X) (wherein, Rf ７ is a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Rf ８ is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0343] The alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI): Rf ９ -O-CY １ Y ２ CF ２ -SO ３ M (XI) (wherein, Rf ９is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, and which may contain chlorine, and which is partially or completely fluorinated; Y １ and Y ２ are the same or different and are H or F, and M is as defined above.

[0344] The compound (XII) is represented by the following general formula (XII): (In the formula, X １ , X ２ and X ３ Rf may be the same or different and are H, F and linear or branched partially or fully fluorinated alkyl groups having 1 to 6 carbon atoms, which may contain ether bonds; １０ is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y ０ is an anionic group. ０ is -COOM, -SO ２ M or -SO ３ M, and -SO ３ M or COOM (wherein M is as defined above). Examples of L include a single bond and a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0345] The compound (XIII) has the following general formula (XIII): １１ -O-(CF ２ CF (CF ３ ) O) ｎ９ (CF ２ O) ｎ１０ CF ２ COOM (XIII) (wherein, Rf １１ is a fluoroalkyl group containing chlorine and having 1 to 5 carbon atoms, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above. ２ ClO(CF ２ CF (CF ３ ) O) ｎ９ (CF ２ O) ｎ１０CF ２ COONH ４ (a mixture having an average molecular weight of 750, wherein n9 and n10 are defined above).

[0346] As mentioned above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0347] The fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0348] Examples of the fluorine-containing surfactant include compounds represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds. In one embodiment of the above polymerization, the fluoromonomer is polymerized substantially in the absence of a compound represented by the following formula: F(CF ２ ) ７ COOM, F(CF ２ ) ５ COOM, H(CF ２ ) ６ COOM, H(CF ２ ) ７ COOM, C.F. ３ O (CF ２ ) ３ OCHFCF ２ COOM, C. ３ F ７ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C. ２ F ５ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ OCF (CF ３ )CF ２OCF (CF ３ ) COOM, C.F. ２ ClCF ２ CF ２ OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF ２ CF ２ OCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF ２ CF (CF ３ ) OCF ２ COOM, (In each formula, M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.

[0349] Polymerization of the fluoromonomer in the aqueous medium results in a polymerization dispersion containing the fluoropolymer, polymer (I), and the aqueous medium.

[0350] (Aqueous fluoropolymer dispersion) The present disclosure also relates to an aqueous fluoropolymer dispersion containing polymer (I), a fluoropolymer, a nonionic surfactant, and an aqueous medium. The aqueous fluoropolymer dispersion of the present disclosure can be suitably produced by the production method of the present disclosure.

[0351] In the aqueous fluoropolymer dispersion of the present disclosure, the content of polymer (I) is 500 ppm by mass or less relative to the aqueous fluoropolymer dispersion, the viscosity of the aqueous fluoropolymer dispersion at 25°C is 100 mPa s or less, the anionic charge density of the polymer particles of the fluoropolymer is 8.0 to 40 μeq / g, the content of the fluoropolymer is 50% by mass or more and 75% by mass or less relative to the aqueous fluoropolymer dispersion, and the content of the nonionic surfactant is 1.0% by mass or more and 12% by mass or less relative to the fluoropolymer. Because the aqueous fluoropolymer dispersion of the present disclosure has such a configuration, its pH is less likely to decrease even when stored for a long period of time.

[0352] The content of polymer (I) in the aqueous fluoropolymer dispersion of the present disclosure is 500 ppm by mass or less, preferably 450 ppm by mass or less, more preferably 400 ppm by mass or less, even more preferably 350 ppm by mass or less, and preferably 0.1 ppm by mass or more, more preferably 1.0 ppm by mass or more, even more preferably 10.0 ppm by mass or more, based on the aqueous fluoropolymer dispersion.

[0353] The content of polymer (I) is １９ The content of polymer (I) can be adjusted, for example, by adjusting the degree of concentration of the pre-concentration composition or the number of concentration steps in the production method of the present disclosure.

[0354] The fluoropolymer content of the aqueous fluoropolymer dispersion of the present disclosure is 50% by mass or more and 75% by mass or less, preferably more than 50% by mass, more preferably 55% by mass or more, even more preferably 57% by mass or more, still more preferably 60% by mass or more, preferably 70% by mass or less, more preferably 67% by mass or less, and even more preferably 65% ​​by mass or less, based on the aqueous fluoropolymer dispersion.

[0355] The fluoropolymer content in the aqueous fluoropolymer dispersion of the present disclosure can be measured by the same method as the fluoropolymer content in the pre-concentration composition. The fluoropolymer content can be adjusted, for example, by adjusting the concentration level or number of times of concentration of the pre-concentration composition in the production method of the present disclosure.

[0356] The content of the nonionic surfactant in the aqueous fluoropolymer dispersion of the present disclosure is 1.0 mass% or more and 12 mass% or less, preferably 2.5 mass% or more, more preferably 4.0 mass% or more, even more preferably 5.0 mass% or more, particularly preferably 5.5 mass% or more, and preferably 10 mass% or less, more preferably 8.0 mass% or less, even more preferably 7.0 mass% or less, based on the fluoropolymer.

[0357] The content of the nonionic surfactant in the aqueous fluoropolymer dispersion of the present disclosure can be measured by the same method as that for the content of the nonionic surfactant in the pre-concentration composition.

[0358] The viscosity at 25°C of the aqueous fluoropolymer dispersion of the present disclosure is 100 mPa·s or less, preferably 70.0 mPa·s or less, more preferably 60.0 mPa·s or less, even more preferably 50.0 mPa·s or less, preferably 5.0 mPa·s or more, more preferably 10.0 mPa·s or more, even more preferably 15.0 mPa·s or more, and particularly preferably 20.0 mPa·s or more.

[0359] The viscosity of the aqueous fluoropolymer dispersion of the present disclosure at 25° C. can be measured using a B-type rotational viscometer (Rotor No. 2, manufactured by Toki Sangyo Co., Ltd.) at a rotation speed of 60 rpm for a measurement time of 120 seconds at 25° C. The viscosity of the aqueous fluoropolymer dispersion can be adjusted by a method such as adjusting the contents of the fluoropolymer and nonionic surfactant, or by adding an anionic surfactant, a pH adjuster, or the like.

[0360] The anionic charge density of the polymer particles of the fluoropolymer is 8.0 to 40 μeq / g, more preferably 8.5 μeq / g or more, even more preferably 9.0 μeq / g or more, more preferably 30 μeq / g or less, even more preferably 20 μeq / g or less, and particularly preferably 15 μeq / g or less.

[0361] When the anionic charge density of the polymer particles in the aqueous dispersion is within the above range, the pH of the aqueous dispersion is less likely to decrease even when stored for a long period of time. This is thought to be because the charge on the surface of the polymer particles acts to mitigate changes in the pH of the aqueous dispersion. The anionic charge density of the polymer particles can be adjusted by adding a fluorine-free water-soluble electrolyte to an aqueous dispersion containing fluoropolymer particles. The presence of a fluorine-free water-soluble electrolyte in the aqueous dispersion increases the anionic charge density of the polymer particles compared to normal, resulting in long-term pH stability of the aqueous dispersion. If the anionic charge density of the polymer particles exceeds the upper limit of the above range, the viscosity of the aqueous dispersion at 25°C increases, impairing dispersion stability and handling.

[0362] The anionic charge density of the polymer particles of the fluoropolymer in the aqueous dispersion can be measured using a particle charge analyzer.

[0363] The aqueous fluoropolymer dispersion of the present disclosure preferably contains a fluorine-free water-soluble electrolyte. As the fluorine-free water-soluble electrolyte, the fluorine-free water-soluble electrolyte that can be used in the production method of the present disclosure can be used as well.

[0364] The surface tension of a 0.1 mass % aqueous solution of the fluorine-free water-soluble electrolyte is preferably greater than 60 mN / m, from the viewpoint of easily adjusting the anion charge density of the polymer particles to fall within the above range.

[0365] From the viewpoint of easily adjusting the anion charge density of the polymer particles within the above range, the fluorine-free water-soluble electrolyte is preferably a carboxylic acid or a salt thereof having a surface tension within the above range and represented by general formula (11): General formula (11): R １ -(COOH)ｎ (In the formula, R １ is a monovalent to trivalent organic group having 1 to 10 carbon atoms, and n is an integer of 1 to 3.

[0366] Furthermore, from the viewpoint of easily adjusting the anion charge density of the polymer particles within the above range, the fluorine-free water-soluble electrolyte is preferably at least one selected from the group consisting of sulfuric acid, citric acid, succinic acid, carbonic acid, tartaric acid, maleic acid, malic acid, oxalic acid, malonic acid, and salts thereof, and more preferably at least one selected from the group consisting of ammonium sulfate and ammonium citrate.

[0367] The content of the fluorine-free water-soluble electrolyte in the aqueous fluoropolymer dispersion of the present disclosure is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, still more preferably 0.3 mass% or more, and preferably 5.0 mass% or less, more preferably 3.0 mass% or less, even more preferably 2.0 mass% or less, and still more preferably 1.5 mass% or less, based on the fluoropolymer. When the content of the fluorine-free water-soluble electrolyte is within the above range, the anion charge density of the polymer particles can be easily adjusted within the above range. The higher the content of the fluorine-free water-soluble electrolyte, the higher the anion charge density of the polymer particles and the viscosity of the aqueous dispersion tend to be.

[0368] In one embodiment, the aqueous fluoropolymer dispersion of the present disclosure has a pH drop of less than 1.0 after 6 months from the initial pH.

[0369] The pH of the aqueous fluoropolymer dispersion is a value measured at 25°C in accordance with JIS K6893. The initial pH of the aqueous dispersion and the pH after 6 months are measured, and the range of pH decrease can be calculated using the following formula using the measured values: Range of pH decrease = (initial pH) - (pH after 6 months)

[0370] The initial pH of the aqueous fluoropolymer dispersion is the pH of the aqueous dispersion whose pH drop is to be measured, and may be the pH of the aqueous dispersion measured immediately after preparation, or may be the pH of the aqueous dispersion that has been stored for a long period of time since preparation. When the pH of the aqueous dispersion whose pH drop is to be measured is less than 9.0, the pH of the aqueous dispersion is adjusted to 9.0, and pH = 9.0 is adopted as the value of the initial pH.

[0371] The pH of the aqueous fluoropolymer dispersion after 6 months is the pH of the aqueous fluoropolymer dispersion at the time when the aqueous dispersion whose pH decrease is to be measured (initial pH) is measured and the dispersion is left to stand for 6 months (180 days) at 25° C. When the pH of the aqueous dispersion is adjusted to 9.0 and pH = 9.0 is the initial pH, the pH of the aqueous fluoropolymer dispersion is measured at the time when the dispersion is left to stand for 6 months (180 days) from the time when the pH was adjusted to 9.0.

[0372] The aqueous fluoropolymer dispersion of the present disclosure can contain the components described above as components that can be added to the aqueous fluoropolymer dispersion obtained by concentration, such as anionic surfactants, pH adjusters, water-soluble polymer compounds, and antifoaming agents.

[0373] In one embodiment of the aqueous fluoropolymer dispersion of the present disclosure, the dispersion is substantially free of a fluorine-containing surfactant. In the present disclosure, "substantially free of a fluorine-containing surfactant" means that the content of the fluorine-containing surfactant in the aqueous dispersion is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, still more preferably 1 ppb by mass or less, and particularly preferably below the detection limit of the fluorine-containing surfactant as measured by liquid chromatography-mass spectrometry (LC / MS).

[0374] Next, the fluoropolymer in the aqueous dispersion obtained by the manufacturing method of the present disclosure and the fluoropolymer in the aqueous dispersion of the present disclosure will be described in more detail.

[0375] (Fluoropolymer) Examples of the fluoropolymer include a TFE polymer in which the monomer having the largest molar fraction in the polymer (hereinafter referred to as "most abundant monomer") is TFE, a VDF polymer in which the most abundant monomer is VDF, and a CTFE polymer in which the most abundant monomer is CTFE.

[0376] Preferably, the fluoropolymer has an ion exchange ratio (IXR) greater than 53. Preferred fluoropolymers have no ionic groups or a limited number of ionic groups resulting in an ion exchange ratio greater than about 100. Preferred fluoropolymers have an ion exchange ratio of 1000 or greater, more preferably 2000 or greater, and even more preferably 5000 or greater.

[0377] The TFE polymer may suitably be a TFE homopolymer or a copolymer comprising (1) TFE, (2) one or more fluorine-containing monomers other than TFE having 2 to 8 carbon atoms, particularly VDF, HFP, or CTFE, and (3) other monomers. Examples of the (3) other monomers include fluoro(alkyl vinyl ethers) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms; fluorodioxole; perfluoroalkylethylene; ω-hydroperfluoroolefin, etc.

[0378] The TFE polymer may also be a copolymer of TFE and one or more fluorine-free monomers. Examples of the fluorine-free monomers include alkenes such as ethylene and propylene; vinyl esters; and vinyl ethers. The TFE polymer may also be a copolymer of TFE and one or more fluorine-containing monomers having 2 to 8 carbon atoms and one or more fluorine-free monomers.

[0379] The VDF polymer may suitably be a VDF homopolymer [PVDF] or a copolymer of (1) VDF, (2) one or more fluoroolefins other than VDF having 2 to 8 carbon atoms, particularly TFE, HFP, or CTFE, and (3) a perfluoro(alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms.

[0380] The CTFE polymer may suitably be a CTFE homopolymer or a copolymer consisting of (1) CTFE, (2) one or more fluoroolefins other than CTFE having 2 to 8 carbon atoms, particularly TFE or HFP, and (3) a perfluoro(alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms.

[0381] The CTFE polymer may also be a copolymer of CTFE with one or more non-fluorine-containing monomers, and the non-fluorine-containing monomers include alkenes such as ethylene and propylene; vinyl esters; and vinyl ethers.

[0382] The fluoropolymers may be glassy, ​​plastic or elastomeric. They may be amorphous or partially crystalline and may be subject to compression sintering, melt processing or non-melt processing.

[0383] In the production method of the present disclosure, for example, (I) as a non-melt-processable fluororesin, tetrafluoroethylene polymer [TFE polymer (PTFE)] is used, (II) as a melt-processable fluororesin, ethylene / TFE copolymer [ETFE], TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoroallyl ether copolymer, TFE / VDF copolymer, electrolyte polymer precursor is used, and (III) as a fluororubber, TFE / pro Suitable examples of copolymers that can be produced include propylene copolymers, TFE / propylene / third monomer copolymers (wherein the third monomer is VDF, HFP, CTFE, a fluoroalkyl vinyl ether, or the like), copolymers of TFE and a fluoroalkyl vinyl ether; HFP / ethylene copolymers, HFP / ethylene / TFE copolymers; VDF / HFP copolymers, HFP / ethylene copolymers, VDF / TFE / HFP copolymers; and the fluorine-containing segmented polymers described in JP-B-61-49327.

[0384] The fluoropolymer is preferably a fluororesin, and particularly, a fluororesin having a fluorine substitution rate of 50% or more as calculated by the following formula is more preferred, a fluororesin having a fluorine substitution rate of more than 50% is even more preferred, a fluororesin having a fluorine substitution rate of 55% or more is even more preferred, a fluororesin having a fluorine substitution rate of 60% or more is even more preferred, a fluororesin having a fluorine substitution rate of 75% or more is still more preferred, a fluororesin having a fluorine substitution rate of 80% or more is particularly preferred, and a fluororesin having a fluorine substitution rate of 90 to 100%, i.e., a perfluororesin, is most preferred. (Formula) Fluorine substitution rate (%) = (number of fluorine atoms bonded to carbon atoms constituting the fluoropolymer) / ((number of hydrogen atoms bonded to carbon atoms constituting the fluoropolymer) + (number of fluorine atoms and chlorine atoms bonded to carbon atoms constituting the fluoropolymer)) × 100

[0385] The perfluororesin is more preferably a fluororesin having a fluorine substitution rate of 95 to 100%, further preferably PTFE, FEP or PFA, and particularly preferably PTFE.

[0386] The fluoropolymer may have a core-shell structure. Examples of fluoropolymers having a core-shell structure include modified PTFE particles containing a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE. Examples of such modified PTFE include the PTFE described in JP-A-2005-527652.

[0387] The core-shell structure may have the following structures: Core: TFE homopolymer Shell: TFE homopolymer Core: Modified PTFE Shell: TFE homopolymer Core: Modified PTFE Shell: Modified PTFE Core: TFE homopolymer Shell: Modified PTFE Core: Low molecular weight PTFE Shell: High molecular weight PTFE Core: High molecular weight PTFE Shell: Low molecular weight PTFE

[0388] In the fluoropolymer having the core-shell structure, the lower limit of the core ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 2.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the core ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0389] In the fluoropolymer having the core-shell structure, the lower limit of the shell ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 2.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the shell ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0390] In the fluoropolymer having the core-shell structure, the core or the shell can be configured to have two or more layers. For example, it may be a fluoropolymer having a three-layer structure with a core center portion of modified PTFE, a core outer layer portion of TFE homopolymer, and a shell of modified PTFE.

[0391] The fluoropolymer having the core-shell structure also includes a particle of the fluoropolymer having multiple cores.

[0392] The above-mentioned (I) non-melt-processable fluororesin, (II) melt-processable fluororesin, and (III) fluororubber, which are suitably produced by the production method of the present disclosure, are preferably produced in the following manner.

[0393] (I) Non-melt-processable fluororesin In the production method of the present disclosure, the polymerization of TFE is usually carried out at a polymerization temperature of 10 to 150 ° C and a polymerization pressure of 0.05 to 5 MPaG. For example, the polymerization temperature is more preferably 30 ° C or higher, and even more preferably 50 ° C or higher. Also, it is more preferably 120 ° C or lower, and even more preferably 100 ° C or lower. Also, the polymerization pressure is more preferably 0.3 MPaG or higher, and even more preferably 0.5 MPaG or higher, and also more preferably 5.0 MPaG or lower, and even more preferably 3.0 MPaG or lower. In particular, from the viewpoint of improving the yield of fluoropolymer, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, more preferably 1.5 MPaG or higher, and even more preferably 2.0 MPaG or higher.

[0394] In one embodiment, the polymerization is carried out by charging pure water into a pressure-resistant reactor equipped with a stirrer, deoxidizing, then charging TFE, adjusting the temperature to a predetermined value, and adding a polymerization initiator to initiate the reaction. If the pressure decreases as the reaction proceeds, additional TFE is continuously or intermittently supplied to maintain the initial pressure. When a predetermined amount of TFE has been supplied, the supply is stopped, the TFE in the reactor is purged, and the temperature is returned to room temperature to terminate the reaction. Additional TFE may be continuously or intermittently supplied to prevent the pressure from decreasing.

[0395] In the production of above-mentioned TFE polymer (PTFE), also can use various known modified monomers together.In this disclosure, above-mentioned TFE polymer is not only TFE homopolymer, but also the concept of TFE and modified monomer copolymer, which is non-melt processable (hereinafter referred to as "modified PTFE").

[0396] The modifying monomer is not particularly limited as long as it can be copolymerized with TFE, and includes fluoromonomers and non-fluoromonomers. The modifying monomer used may be one type or multiple types.

[0397] The non-fluoromonomer is not particularly limited and may be a monomer represented by the general formula: ２ =CR Ｑ１ -LR Ｑ２ (In the formula, R Ｑ１ represents a hydrogen atom or an alkyl group. L represents a single bond, -CO-O-*, -O-CO-* or -O-. * represents R Ｑ２ represents the bonding position with Ｑ２ represents a hydrogen atom, an alkyl group or a nitrile group.

[0398] Examples of non-fluoromonomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, vinyl methacrylate, vinyl acetate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, ethyl vinyl ether, cyclohexyl vinyl ether, etc. Of these, butyl methacrylate, vinyl acetate, and acrylic acid are preferred as non-fluoromonomers.

[0399] Examples of fluoromonomers include perfluoroolefins such as hexafluoropropylene (HFP); hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF); perhaloolefins such as chlorotrifluoroethylene; perfluorovinyl ethers; (perfluoroalkyl)ethylenes; and perfluoroallyl ethers.

[0400] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the general formula (A): CF ２ ═CF-ORf (A) (wherein Rf represents a perfluoroorganic group). In the present disclosure, the term "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0401] Examples of the perfluorovinyl ether include perfluoro(alkyl vinyl ether) [PAVE], which is represented by general formula (A) and in which Rf is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0402] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0403] The perfluorovinyl ether further includes those in which Rf in the general formula (A) is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf ... the following formula:

[0404]

[0405] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0406] CF ３ CF ２ CF ２ -(O-CF(CF ３ )-CF２ ) ｎ - (wherein n represents an integer of 1 to 4).

[0407] Hydrogen-containing fluoroolefins include CH ２ =CF ２ , CFH=CH ２ , CFH=CF ２ , C.H. ２ =CFCF ３ , C.H. ２ = CHCF ３ , CHF=CHCF ３ (E form), CHF=CHCF ３ (Z-isomer), etc.

[0408] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0409] Examples of perfluoroallyl ethers include those represented by the general formula: CF ２ =CF-CF ２ Examples of the fluoromonomer include those represented by —ORf (wherein Rf represents a perfluoroorganic group).

[0410] Rf in the above general formula is the same as Rf in general formula (A). Rf is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. Examples of perfluoroallyl ethers include CF ２ =CF-CF ２ -O-CF ３ , C.F. ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ At least one selected from the group consisting of CF ２ =CF-CF２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ =CF-CF ２ -O-CF ２ CF ２ CF ３ is more preferable.

[0411] A preferred example of the modifying monomer is the modified monomer (3) having a monomer reactivity ratio of 0.1 to 8. The presence of the modified monomer (3) makes it possible to obtain PTFE particles having a small particle size and an aqueous dispersion having high dispersion stability.

[0412] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant of the reaction of the growing radical with TFE when the growing radical is less than the repeating unit based on TFE by the rate constant of the reaction of the growing radical with modified monomer.The lower this value, the higher the reactivity of the modified monomer with TFE.The monomer reactivity ratio can be calculated by copolymerizing TFE with modified monomer, determining the composition in the produced polymer immediately after the start, and using the Feynman-Ross equation.

[0413] The copolymerization was carried out in a 6.0L stainless steel autoclave using 3600g of deionized and degassed water, 1000 mass ppm of ammonium perfluorooctanoate relative to the water, and 100g of paraffin wax at a pressure of 0.78 MPaG and a temperature of 70 ° C. 0.05g, 0.1g, 0.2g, 0.5g, and 1.0g of modified monomer were added to the reactor, respectively, and 0.072g of ammonium persulfate (20 mass ppm relative to water) was added. TFE was continuously supplied to maintain the polymerization pressure at 0.78 MPaG. When the amount of TFE charged reached 1000g, stirring was stopped and the reactor was depressurized until atmospheric pressure was reached. After cooling, the paraffin wax was separated to obtain an aqueous dispersion containing the resulting polymer. The aqueous dispersion was stirred to coagulate the resulting polymer, and then dried at 150 ° C. The composition of the resulting polymer is calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0414] The modified monomer (3) having a monomer reactivity ratio of 0.1 to 8 is preferably at least one selected from the group consisting of modified monomers represented by formulas (3a) to (3d): CH ２ =CH-Rf １ (3a) (wherein, Rf １ is a perfluoroalkyl group having 1 to 10 carbon atoms.) CF ２ ═CF—O—Rf ２ (3b) (wherein, Rf ２ is a perfluoroalkyl group having 1 to 2 carbon atoms.) CF ２ =CF-O-(CF ２ ) ｎ CF = CF ２ (3c) (Wherein, n is 1 or 2.)

[0415] (In the formula, X ３ and X ４ is F, Cl or a methoxy group, and Y is of formula Y1 or Y2.

[0416] (In formula Y2, Z and Z′ are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0417] The content of the modified monomer (3) unit is preferably in the range of 0.00001 to 1.0% by mass relative to the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90% by mass, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0418] As the above-mentioned modified monomer, because it can obtain the aqueous dispersion of the average primary particle diameter of primary particle is small, the aspect ratio of primary particle is small, and excellent stability, it is preferred to be selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, perfluoro(alkyl vinyl ether), (perfluoroalkyl)ethylene, ethylene, and the modified monomer of the functional group and hydrophilic group that can react by radical polymerization.By using the above-mentioned modified monomer, it can obtain the aqueous dispersion of PTFE that has the average primary particle diameter smaller, the aspect ratio of primary particle is small, and excellent dispersion stability.In addition, it can obtain the aqueous dispersion of less uncoagulated polymer.

[0419] From the viewpoint of reactivity with TFE, the modified monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene. More preferably, it contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. The total amount of the hexafluoropropylene unit, perfluoro(alkyl vinyl ether) unit, and (perfluoroalkyl)ethylene unit is preferably in the range of 0.00001 to 1% by mass relative to the total polymerization units of PTFE. The lower limit of the total amount is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limits are, in order of preference, 0.80 mass%, 0.70 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0420] The modified monomer preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group (hereinafter referred to as "modified monomer (A)").

[0421] By making the above-mentioned modified monomer (A) exist, it is possible to obtain the PTFE particles with small primary particle diameter, and obtain the aqueous dispersion with high dispersion stability.In addition, it is also possible to reduce the amount of uncoagulated polymer.Furthermore, it is possible to reduce the aspect ratio of primary particle.

[0422] The amount of the modified monomer (A) used is preferably more than the amount corresponding to 0.1 ppm by mass of the aqueous medium, more preferably more than 0.5 ppm by mass, even more preferably more than 1.0 ppm by mass, even more preferably 5 ppm by mass or more, and particularly preferably 10 ppm by mass or more. If the amount of the modified monomer (A) used is too small, the average primary particle diameter of the resulting PTFE may not be small. The amount of the modified monomer (A) used may be within the above range, but the upper limit can be, for example, 5000 ppm by mass. In addition, in the above production method, the modified monomer (A) may be added to the system during the reaction to improve the stability of the aqueous dispersion during or after the reaction.

[0423] The modified monomer (A) is highly water-soluble, so even if unreacted modified monomer (A) remains in the aqueous dispersion, it can be easily removed in the concentration step or the coagulation and washing steps.

[0424] The above-mentioned modified monomer (A) is incorporated into the produced polymer during the polymerization process, but since the concentration of the modified monomer (A) itself in the polymerization system is low and the amount incorporated into the polymer is small, there are no problems such as a decrease in the heat resistance of PTFE or coloration after baking.

[0425] The hydrophilic group in the modified monomer (A) is, for example, —NH ２ , -PO ３ M, -OPO ３ M, -SO ３ M, -OSO ３ M, -COOM (in each formula, M is H, a metal atom, NR ７ｙ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｙ are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring.) Among the above hydrophilic groups, -SO ３ M or -COOM is preferred. ７ｙ The organic group in R is preferably an alkyl group. ７ｙAs the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom is preferably a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), and more preferably Na, K, or Li.

[0426] Examples of the "functional group capable of reacting by radical polymerization" in the modifying monomer (A) include groups having an ethylenically unsaturated bond, such as a vinyl group and an allyl group. The group having an ethylenically unsaturated bond is a group represented by the following formula: CX ｅ X ｇ =CX ｆ R- (wherein, X ｅ , X ｆ and X ｇ are each independently F, Cl, H, or CF ３ , C.F. ２ H, C.F.H. ２ , or CH ３ and R is a linking group. The linking group of R can be represented by the formula: ａ Preferably, the linking group is -CH=CH ２ , -CF=CH ２、 -CH=CF ２、 -CF = CF ２ , -CH ２ -CH=CH ２ , -CF ２ -CF=CH ２ , -CF ２ -CF = CF ２ , -(C=O)-CH=CH ２ , -(C=O)-CF=CH ２ , -(C=O)-CH=CF ２ , -(C=O)-CF=CF ２ , -(C=O)-C(CH ３ ) = CH ２ , -(C=O)-C(CF ３ ) = CH ２ , -(C=O)-C(CH ３ ) = CF ２ , -(C=O)-C(CF ３ ) = CF ２, —O—CH ２ -CH=CH ２ , —O—CF ２ -CF=CH ２ , —O—CH ２ -CH=CF ２ , —O—CF ２ -CF = CF ２ Examples of groups having an unsaturated bond include the following.

[0427] The modified monomer (A) has a functional group that can react by radical polymerization, so when used in the polymerization, it is assumed that it will react with the fluorine-containing monomer at the initial stage of the polymerization reaction, and form particles that have hydrophilic groups derived from the modified monomer (A) and have high stability.Therefore, it is thought that when polymerization is carried out in the presence of the modified monomer (A), the number of particles will increase.

[0428] The polymerization may be carried out in the presence of one type of the modifying monomer (A), or in the presence of two or more types thereof.

[0429] In the polymerization, a compound having an unsaturated bond can be used as the modifying monomer (A).

[0430] The modifying monomer (A) is a compound represented by the general formula (4): ｉ X ｋ =CX ｊ R ａ - (CZ １ Z ２ ) ｋ -Y ３ (4) (wherein, X ｉ , X ｊ and X ｋ are each independently F, Cl, H or CF ３ and Y ３ is a hydrophilic group; R ａ is a linking group; Z １ and Z ２ are each independently H, F or CF ３ and k is 0 or 1. Examples of the hydrophilic group include —NH ２ , -PO ３ M, -OPO ３ M, -SO ３ M, -OSO３ M, -COOM (in each formula, M is H, a metal atom, NR ７ｙ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｙ are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring.) Among the above hydrophilic groups, -SO ３ M or -COOM is preferred. ７ｙ The organic group in R is preferably an alkyl group. ７ｙ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The alkyl group represented by the formula (I) is more preferred. Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. By using the modified monomer (A), an aqueous dispersion having a smaller average primary particle size and better stability can be obtained. Furthermore, the aspect ratio of the primary particles can be made smaller.

[0431] The above R ａ is a linking group. In the present disclosure, a "linking group" refers to a divalent linking group. The linking group may be a single bond and preferably contains at least one carbon atom. The number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less. The linking group may have a linear or branched, cyclic or acyclic structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms, but may contain a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0432] The above R ａ is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group. ａ When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and the group may or may not contain a double bond. ａ may be either linear or branched, and may be either cyclic or acyclic. ａ R may contain functional groups (e.g., esters, ethers, ketones, amines, halides, etc.). ａ R may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group. ａ Examples of the hydrocarbon group include a hydrocarbon group in which no fluorine atoms are bonded to a carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, a hydrocarbon group in which all of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, -(C=O)-, -(C=O)-O-, or a hydrocarbon group containing an ether bond, which may contain an oxygen atom, a double bond, or a functional group.

[0433] R ａ is preferably -(C=O)-, -(C=O)-O-, or a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond and may contain a carbonyl group, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine. ａ is preferably —(CH ２ ) ａ -, - (CF ２ ) ａ -, -O-(CF ２ ) ａ -, - (CF ２ ) ａ -O-(CF ２ ) ｂ -, -O(CF ２ ) ａ -O-(CF ２ ) ｂ -, - (CF ２ ) ａ-[O-(CF ２ ) ｂ ] ｃ -、-O(CF ２ ) ａ -[O-(CF ２ ) ｂ ] ｃ -、-[(CF ２ ) ａ -O] ｂ -[(CF ２ ) ｃ -O] ｄ -、-O[(CF ２ ) ａ -O] ｂ -[(CF ２ ) ｃ -O] ｄ -、-O-[CF ２ CF(CF ３ )O] ａ -(CF ２ ) ｂ -、-(C=O)-、-(C=O)-O-、-(C=O)-(CH ２ ) ａ -、-(C=O)-(CF ２ ) ａ -、-(C=O)-O-(CH ２ ) ａ -、-(C=O)-O-(CF ２ ) ａ -、-(C=O)-[(CH ２ ) ａ -O] ｂ -、-(C=O)-[(CF ２ ) ａ -O] ｂ -、-(C=O)-O[(CH ２ ) ａ -O] ｂ -、-(C=O)-O[(CF ２ ) ａ -O] ｂ -、-(C=O)-O[(CH ２ ) ａ -O] ｂ -(CH ２ ) ｃ -、-(C=O)-O[(CF ２ ) ａ -O] ｂ -(CF ２ ) ｃ-, -(C=O)-(CH ２ ) ａ -O-(CH ２ ) ｂ -, -(C=O)-(CF ２ ) ａ -O-(CF ２ ) ｂ -, -(C=O)-O-(CH ２ ) ａ -O-(CH ２ ) ｂ -, -(C=O)-O-(CF ２ ) ａ -O-(CF ２ ) ｂ -, -(C=O)-OC ６ H ４ - and at least one selected from combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limits of a, b, c, and d are, for example, 100.

[0434] R ａ A specific example of a suitable group is —CF ２ —O—, —CF ２ -O-CF ２ -, -CF ２ -O-CH ２ -, -CF ２ -O-CH ２ CF ２ -, -CF ２ -O-CF ２ CF ２ -, -CF ２ -O-CF ２ CH ２ -, -CF ２ -O-CF ２ CF ２ CH ２ -, -CF ２ -O-CF(CF ３ ) -, -CF ２ -O-CF(CF ３ )CF ２ -, -CF ２ -O-CF(CF ３ )CF ２-O-, -CF ２ -O-CF(CF ３ )CH ２ -, -(C=O)-, -(C=O)-O-, -(C=O)-(CH ２ )-, -(C=O)-(CF ２ )-, -(C=O)-O-(CH ２ )-, -(C=O)-O-(CF ２ )-, -(C=O)-[(CH ２ ) ２ -O] ｎ -, -(C=O)-[(CF ２ ) ２ -O] ｎ -, -(C=O)-O[(CH ２ ) ２ -O] ｎ -, -(C=O)-O[(CF ２ ) ２ -O] ｎ -, -(C=O)-O[(CH ２ ) ２ -O] ｎ -(CH ２ )-, -(C=O)-O[(CF ２ ) ２ -O] ｎ -(CF ２ )-, -(C=O)-(CH ２ ) ２ -O-(CH ２ )-, -(C=O)-(CF ２ ) ２ -O-(CF ２ )-, -(C=O)-O-(CH ２ ) ２ -O-(CH ２ )-, -(C=O)-O-(CF ２ ) ２ -O-(CF ２ )-, -(C=O)-O-C ６ H ４ - etc. are included. Among them, the above R ａ is specifically, -CF ２ -O-, -CF ２ -O-CF ２ - etc. are included. Among them, the above R ２ -O-CF ２ CF ２ - etc. are included. Among them, the above R ２-O-CF(CF ３ ) -, -CF ２ -O-CF(CF ３ )CF ２ -, -CF ２ -O-CF(CF ３ )CF ２ -O-, -(C=O)-, -(C=O)-O-, -(C=O)-(CH ２ )-,-(C=O)-O-(CH ２ )-,-(C=O)-O[(CH ２ ) ２ -O] ｎ -, -(C=O)-O[(CH ２ ) ２ -O] ｎ - (CH ２ )-,-(C=O)-(CH ２ ) ２ -O-(CH ２ )-, or -(C=O)-O-C ６ H ４ In the above formula, n is an integer of 1 to 10.

[0435] -R in general formula (4) ａ - (CZ １ Z ２ ) ｋ - is -CF ２ -O-CF ２ -, -CF ２ -O-CF(CF ３ ) -, -CF ２ -O-C(CF ３ ) ２ -, -CF ２ -O-CF ２ -CF ２ -, -CF ２ -O-CF ２ -CF (CF ３ ) -, -CF ２ -O-CF ２ -C(CF ３ ) ２ -, -CF ２ -O-CF ２ CF ２ -CF ２ -, -CF ２ -O-CF ２ CF ２ -CF (CF３ )-、-CF ２ -O-CF ２ CF ２ -C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )-CF ２ -、-CF ２ -O-CF(CF ３ )-CF(CF ３ )-、-CF ２ -O-CF(CF ３ )-C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )CF ２ -CF ２ -、-CF ２ -O-CF(CF ３ )CF ２ -CF(CF ３ )-、-CF ２ -O-CF(CF ３ )CF ２ -C(CF ３ ) ２ -、-CF ２ -O-CF(CF ３ )CF ２ -O-CF ２ -、-CF ２ -O-CF(CF ３ )CF ２ -O-CF(CF ３ )-、-CF ２ -O-CF(CF ３ )CF ２ -O-C(CF ３ ) ２ -、-(C=O)-、-(C=O)-O-、-(C=O)-(CH ２ )-、-(C=O)-(CF ２ )-、-(C=O)-O-(CH ２ )-、-(C=O)-O-(CF ２ )-、-(C=O)-[(CH ２ ) ２ -O] ｎ -(CH ２ )-、-(C=O)-[(CF ２ ) ２ -O]ｎ -(CF ２ )-、-(C=O)-[(CH ２ ) ２ -O] ｎ -(CH ２ )-(CH ２ )-、-(C=O)-[(CF ２ ) ２ -O] ｎ -(CF ２ )-(CF ２ )-、-(C=O)-O[(CH ２ ) ２ -O] ｎ -(CF ２ )-、-(C=O)-O[(CH ２ ) ２ -O] ｎ -(CH ２ )-(CH ２ )-、-(C=O)-O[(CF ２ ) ２ -O] ｎ -(CF ２ )-、-(C=O)-O[(CF ２ ) ２ -O] ｎ -(CF ２ )-(CF ２ )-、-(C=O)-(CH ２ ) ２ -O-(CH ２ )-(CH ２ )-、-(C=O)-(CF ２ ) ２ -O-(CF ２ )-(CF ２ )-、-(C=O)-O-(CH ２ ) ２ -O-(CH ２ )-(CH ２ )-、-(C=O)-O-(CF ２ ) ２ -O-(CF ２ )-(CF ２ )-、-(C=O)-O-(CH ２ ) ２ -O-(CH ２ )-C(CF ３ ) ２ -、-(C=O)-O-(CF ２ ) ２ -O-(CF２ )-C(CF ３ ) ２ - or -(C=O)-O-C ６ H ４ -C(CF ３ ) ２ - is preferred, and -CF ２ -O-CF(CF ３ ) -, -CF ２ -O-CF ２ -CF (CF ３ ) -, -CF ２ -O-CF ２ CF ２ -CF (CF ３ ) -, -CF ２ -O-CF(CF ３ )-CF(CF ３ ) -, -CF ２ -O-CF(CF ３ )CF ２ -CF (CF ３ ) -, -CF ２ -O-CF(CF ３ )CF ２ -O-CF(CF ３ )-, -(C=O)-, -(C=O)-O-(CH ２ )-,-(C=O)-O-(CH ２ )-(CH ２ )-,-(C=O)-O[(CH ２ ) ２ -O] ｎ - (CH ２ )-(CH ２ )-,-(C=O)-O-(CH ２ ) ２ -O-(CH ２ )-C(CF ３ ) ２ - or -(C=O)-O-C ６ H ４ -C(CF ３ ) ２ In the above formula, n is an integer of 1 to 10.

[0436] Specific examples of the compound represented by formula (4) include: (In the formula, X ｊ and Y ３ is the same as above. n is an integer of 1 to 10.

[0437] R ａ As the general formula (r1): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O) ｇ - (r1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1), and a divalent group represented by the general formula (r2): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ - (r2) (wherein, X ７ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1.) is also preferred.

[0438] -R in general formula (4) ａ - (CZ １ Z ２ ) ｋ - may also be represented by the following formula (t1): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O) ｇ -CZ １ Z ２ - (t1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z １and Z ２ are each independently F or CF ３ In formula (t1), a divalent group represented by １ and Z ２ is one F and the other CF ３ In addition, in the general formula (4), -R ａ - (CZ １ Z ２ ) ｋ - is the following formula (t2): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ -CZ １ Z ２ - (t2) (wherein, X ７ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z １ and Z ２ are each independently F or CF ３ In formula (t2), a divalent group represented by １ and Z ２ is one F and the other CF ３ It is more preferable that:

[0439] The compound represented by the general formula (4) is a compound having a hydrophilic group (Y ３ ) except for the above, it is also preferable that the compound has a C—F bond and does not have a C—H bond. ｉ , X ｊ , and X ｋ All of the are F and R ａ is preferably a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be either cyclic or acyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0440] The compound represented by the general formula (4) may be partially fluorinated. That is, the compound represented by the general formula (4) may have a hydrophilic group (Y ３ ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0441] The compound represented by general formula (4) is also preferably a compound represented by the following formula (4a): CF ２ ═CF—O—Rf ０ -Y ３ (4a) (wherein, Y ３ is a hydrophilic group, and Rf ０ is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0442] The compound represented by general formula (4) is also preferably a compound represented by the following formula (4b): CH ２ =CH-O-Rf ０ -Y ３ (4b) (wherein, Y ３ is a hydrophilic group, and Rf ０ is a perfluorinated divalent linking group defined by formula (4a).

[0443] In the general formula (4), Y ３ Ha-OSO ３ One of the preferred embodiments is Y. ３ Ga-OSO ３ When M is a compound represented by general formula (4), CF ２ =CF(OCF ２ CF ２ CH ２ OSO ３ M), CF ２ =CF(O(CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) CH２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ OSO ３ M), CH ２ =CH(O(CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ M), CH ２ =CH(OCF ２ CF ２ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ CF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ In the above formula, M is the same as above.

[0444] In the general formula (4), Y ３ Ha-SO ３ M is also a preferred embodiment. ３ Ga-SO ３ When M is a compound represented by general formula (4), CF ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ =CF(O(CF ２ ) ４ SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) SO ３ M), CF２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M), CH ２ =CH(OCF ２ CF ２ SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ CF ２ SO ３ M), CH ２ =CH(O(CF ２ ) ４ SO ３ M), CH ２ =CH(O(CF ２ ) ３ SO ３ In the above formula, M is the same as above.

[0445] In the general formula (4), Y ３ It is also a preferred embodiment that Y is -COOM. ３ is -COOM, the compound represented by general formula (4) is CF ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(OCF ２ CF ２ CF ２ COOM), C.F. ２ =CF(O(CF ２ ) ５ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) COOM), CF ２ =CF(OCF ２ CF (CF ３ ) O(CF ２ ) ｎ COOM) (n is greater than 1), CH ２ =CH(OCF ２ CF ２ COOM), CH ２=CH(O(CF ２ ) ４ COOM), CH ２ =CH(O(CF ２ ) ３ COOM), C.F. ２ =CF(OCF ２ CF ２ SO ２ NR'CH ２ COOM), C.F. ２ =CF(O(CF ２ ) ４ SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH(OCF ２ CF ２ SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH(O(CF ２ ) ４ SO ２ NR'CH ２ COOM), CH ２ =CH(O(CF ２ ) ３ SO ２ NR'CH ２ In the above formula, R' is H or C １－４ is an alkyl group, and M is the same as above.

[0446] In the general formula (4), Y ３ Ha-OPO ３ M or -OP(O)(OM) ２ It is also a preferred embodiment that ３ Ga-OPO ３ M or -OP(O)(OM) ２ In this case, the compound represented by the general formula (4) is CF ２ =CF(OCF ２ CF ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(O(CF ２ ) ４ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OP (O) (OM) ２ ), CF ２ =CF(OCF ２ CF ２ CF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OP (O) (OM) ２ ), C.H. ２ =CH(OCF ２ CF ２ CH ２ OP (O) (OM) ２ , C.H. ２ =CH((OCF ２ )４ CH ２ OP (O) (OM) ２ ), C.H. ２ =CH(O(CF ２ ) ３ CH ２ OP (O) (OM) ２ In the above formula, M is the same as above.

[0447] In the general formula (4), Y ３ Ha-PO ３ M or -P(O)(OM) ２ It is also a preferred embodiment that ３ Ga-PO ３ M or -P(O)(OM) ２ In this case, the compound represented by the general formula (4) is CF ２ =CF(OCF ２ CF ２ P(O)(OM) ２ ), CF ２ =CF(O(CF ２ ) ４ P(O)(OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) P (O) (OM) ２ ), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ P(O)(OM) ２ ), C.H. ２ =CH(OCF ２ CF ２ P(O)(OM) ２ ), C.H. ２ =CH(O(CF ２ ) ４ P(O)(OM) ２ ), C.H. ２ =CH(O(CF ２ ) ３ P(O)(OM) ２ ) and the like, in which M is the same as above.

[0448] The compound represented by the general formula (4) includes a compound represented by the general formula (5): CX ２=CY(-CZ ２ -O-Rf-Y ３ ) (5) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z is the same or different and is -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y ３ is the same as above.), a compound represented by general formula (6): CX ２ =CY(-O-Rf-Y ３ ) (6) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. Y ３ is the same as above.) and a compound represented by general formula (7): CX ２ =CY(-Rf-Y ３ ) (7) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. Y ３ is the same as above.) The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0449] In general formula (5), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0450] In general formula (5), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Y may be -H, -F or -CF ３ is preferred, and —F is more preferred.

[0451] In general formula (5), Z's may be the same or different and are -H, -F, an alkyl group, or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The Z's may be -H, -F, or -CF ３ is preferred, and —F is more preferred.

[0452] In general formula (5), it is preferable that at least one of X, Y, and Z contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0453] In general formula (5), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. Also, the number of carbon atoms is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF ２ -, -CH ２ CF ２ -, -CF ２ CF ２ -, -CF ２ CH ２ -, -CF２ CF ２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0454] The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, and even more preferably 12 or less. Examples of the fluorine-containing alkylene group having an ether bond include those represented by the following formula: (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３ ; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF ３ )CF ２ -O-CF(CF ３ )-,-(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ )-(wherein n is an integer from 1 to 10), -CF(CF ３ )CF ２ -O-CF(CF ３ ) CH ２ -, -(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ ) CH ２ - (wherein n is an integer of 1 to 10), -CH ２ CF ２ CF ２ O-CH ２ CF ２ CH ２ -, -CF ２ CF２ CF ２ O-CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ CH ２ -, -CF ２ CF ２ O-CF ２ -, -CF ２ CF ２ O-CF ２ CH ２ The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0455] In the general formula (5), Y ３ is -COOM, -SO ３ M or -OSO ３ M (M is H, metal atom, NR ７ｙ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｙ are H or organic groups, and may be the same or different. Any two of them may be bonded to each other to form a ring. ７ｙ The organic group in R is preferably an alkyl group. ７ｙ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M represents —H, a metal atom, or NR ７ ４ is preferred, and —H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR ７ ４ is more preferred, and —H, —Na, —K, —Li or NH ４ is more preferred, and —H, —Na, —K or NH ４is even more preferred, -H, -Na or NH ４ is particularly preferred, and —H or —NH ４ The most preferred is the above Y ３ As the group, -COOM or -SO ３ M is preferred, and —COOM is more preferred.

[0456] The compound represented by general formula (5) is preferably a compound (5a) represented by general formula (5a): CH ２ =CF(-CF ２ -O-Rf-Y ３ ) (5a) (wherein Rf and Y ３ is the same as above.)

[0457] Specific examples of the compound represented by general formula (5a) include compounds represented by the following formula:

[0458]

[0459] (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３ p1+q1+r1 are an integer of 0 to 10; s1 is 0 or 1; t1 is an integer of 0 to 5; Y ３ is the same as above. However, Z ３ and Z ４ are both H, then p1+q1+r1+s1 is not 0). More specifically, compounds represented by the following formula are exemplified:

[0460]

[0461] Among them,

[0462]

[0463] It is preferable that:

[0464] The compound represented by general formula (5a) includes compounds represented by formula (5a) ３ is preferably -COOM, and in particular CH ２ =CFCF ２ OCF (CF ３ ) COOM, and CH２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ )COOM (wherein M is as defined above), and CH ２ =CFCF ２ OCF (CF ３ ) COOM is more preferred.

[0465] The compound represented by general formula (5) is preferably a compound (5b) represented by general formula (5b): CX ２ ２ =CFCF ２ -O-(CF(CF ３ )CF ２ O) ｎ５ -CF (CF ３ )-Y ３ (5b) (where each X ２ are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, Y ３ is the same as the above definition.)

[0466] In the formula (5b), n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in terms of the stability of the resulting aqueous dispersion. ３ is preferably -COOM in that it provides adequate water solubility and stability of the aqueous dispersion, and M is preferably H or NH in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0467] Examples of the compound represented by the formula (5b) include CH ２ =CFCF ２ OCF (CF ３ ) COOM, C.H. ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM (wherein M is as defined above).

[0468] Further, examples of the compound represented by the general formula (5) include a compound represented by the general formula (5c).

[0469] CF ２ =CFCF ２ -O-Rf-Y ３ (5c) (wherein Rf and Y ３ is the same as above)

[0470] More specifically, etc.

[0471] In general formula (6), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0472] In general formula (6), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The Y may be -H, -F or -CF ３ is preferred, and —F is more preferred.

[0473] In general formula (6), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0474] In general formula (6), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF ２ -, -CH ２ CF ２ -, -CF２ CF ２ -, -CF ２ CH ２ -, -CF ２ CF ２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0475] In the above general formula (6), Y ３ is -COOM, -SO ３ M or -OSO ３ M (M is H, metal atom, NR ７ｙ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｙ are H or organic groups, and may be the same or different. Any two of them may be bonded to each other to form a ring. ７ｙ The organic group in R is preferably an alkyl group. ７ｙ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M represents —H, a metal atom, or NR ７ ４ is preferred, and —H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR ７ ４ is more preferred, and —H, —Na, —K, —Li or NH ４ is more preferred, and —H, —Na, —K or NH ４ is even more preferred, -H, -Na or NH ４ is particularly preferred, and —H or —NH ４ The most preferred is the above Y ３As the group, -COOM or -SO ３ M is preferred, and —COOM is more preferred.

[0476] The compound represented by general formula (6) is preferably at least one selected from the group consisting of compounds represented by general formulas (6a), (6b), (6c), (6d), and (6e). ２ =CF-O-(CF ２ ) ｎ１ -Y ３ (6a) (wherein n1 represents an integer of 1 to 10, and Y ３ is the same as the definition above.) CF ２ =CF-O-(CF ２ C (CF ３ ) F) ｎ２ -Y ３ (6b) (wherein n2 represents an integer of 1 to 5, and Y ３ is the same as the definition above.) CF ２ =CF-O-(CFX １ ) ｎ３ -Y ３ (6c) (wherein, X １ is F or CF ３ n3 represents an integer of 1 to 10; Y ３ is the same as the definition above.) CF ２ =CF-O-(CF ２ CFX １ O) ｎ４ -(CF ２ ) ｎ６ -Y ３ (6d) (wherein n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and Y ３ and X １ is the same as the definition above.) CF ２ =CF-O-(CF ２ CF ２ CFX １ O) ｎ５ -CF ２ CF ２ CF ２ -Y ３ (6e) (wherein n5 represents an integer of 0 to 10, and Y ３ and X １ is the same as the above definition.)

[0477] In the formula (6a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. ３ is preferable in that it can provide a suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H or NH, in that M is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0478] Examples of the compound represented by the formula (6a) include CF ２ =CF-O-CF ２ COOM, C.F. ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(OCF ２ CF ２ CF ２ COOM), C.F. ２ =CF-O-CF ２ SO ３ M., C.F. ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ =CF(OCF ２ CF ２ CF ２ SO ３ M) (wherein M is as defined above).

[0479] In the formula (6b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, and Y ３ is preferable in that it provides suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H or NH, in that M is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0480] In the formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferable in that it provides suitable water solubility and stability of the aqueous dispersion.３ M is preferably H or NH in that dispersion stability is improved. ４ It is preferable that:

[0481] In the formula (6d), the X １ In terms of the stability of the aqueous dispersion, -CF ３ In terms of water solubility, n4 is preferably an integer of 5 or less, and Y ３ is preferable to -COOM or -SO in that it provides suitable water solubility and stability of the aqueous dispersion. ３ Preferably, M is H or NH. ４ It is preferable that:

[0482] Examples of the compound represented by the formula (6d) include CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ SO ３ M (wherein M is H, NH ４ or an alkali metal.

[0483] In the general formula (6e), n5 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferable to -COOM or -SO in that it provides suitable water solubility and stability of the aqueous dispersion. ３ Preferably, M is H or NH. ４ It is preferable that:

[0484] Examples of the compound represented by general formula (6e) include CF ２ = CFOCF ２ CF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF ２ CF ２ SO ３ M (wherein M is H, NH ４ or an alkali metal.

[0485] In general formula (7), Rf is preferably a fluorine-containing alkylene group having 1 to 40 carbon atoms. In general formula (7), at least one of X and Y preferably contains a fluorine atom.

[0486] The compound represented by general formula (7) is represented by general formula (7a): CF ２ =CF-(CF ２ ) ｎ１ -Y ３ (7a) (wherein n1 represents an integer of 1 to 10, and Y ３ is the same as defined above.) and a compound represented by general formula (7b): CF ２ =CF-(CF ２ C (CF ３ ) F) ｎ２ -Y ３ (7b) (wherein n2 represents an integer of 1 to 5, and Y ３ is as defined above. ３ is -SO ３ M or -COOM is preferred, where M is H, a metal atom, NR ７ｙ ４, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. ７ｙ represents H or an organic group.

[0487] In the formula (7a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. ３ is preferable in that it can provide a suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H or NH, in that M is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ The compound represented by the formula (7a) is preferably, for example, CF ２ =CFCF ２ COOM, C.F. ２ =CFCF ２ SO ３ M (wherein M is as defined above).

[0488] In the formula (7b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, and Y ３ is preferable in that it provides suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H or NH, in that M is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0489] The modified monomer preferably contains modified monomer (A), and preferably contains at least one selected from the group consisting of compounds represented by general formula (5a), general formula (5c), general formula (6a), general formula (6b), general formula (6c), and general formula (6d), and more preferably contains a compound represented by general formula (5a) or general formula (5c).

[0490] When using a modified monomer (A) as the modified monomer, the content of the modified monomer (A) unit is preferably in the range of 0.00001 to 1.0 mass% relative to the total polymerized units of the TFE polymer (PTFE).The lower limit is more preferably 0.0001 mass%, more preferably 0.0005 mass%, even more preferably 0.001 mass%, and even more preferably 0.005 mass%.The upper limit is, in order of preference, 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0491] In the production of the above-mentioned TFE polymer, polymer (I) can be used within the range of use in the production method of the present disclosure described above.The concentration of polymer (I) is not particularly limited as long as it is within the above-mentioned range.If the added amount is too large, needle-shaped particles with a large aspect ratio will be generated, and the aqueous dispersion will become gel-like, resulting in loss of stability.The lower limit of the amount of polymer (I) used is preferably 0.0001% by mass, more preferably 0.001% by mass, even more preferably 0.01% by mass, particularly preferably 0.02% by mass, based on the aqueous medium.The upper limit of the amount of polymer (I) used is preferably 10% by mass, more preferably 5% by mass, based on the aqueous medium.

[0492] The polymer (I) may be added all at once to a reaction vessel before the initiation of polymerization, may be added all at once after the initiation of polymerization, may be added in multiple divided portions during polymerization, or may be added continuously during polymerization.

[0493] In the production of the above-mentioned TFE polymer, as the polymerization initiator, persulfates (e.g., ammonium persulfate), organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used alone or in the form of a mixture thereof.Also, they can be used in combination with a reducing agent such as sodium sulfite to form a redox system.Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol can be added, or a peroxide decomposer such as ammonium sulfite can be added, to adjust the radical concentration in the system.

[0494] As the redox polymerization initiator, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of redox initiators. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0495] Examples of the redox initiator include potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, and bromate / bisulfite, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate thereto.

[0496] In the production of the TFE polymer, known chain transfer agents can be used, including, for example, saturated hydrocarbons such as methane, ethane, propane, and butane; halogenated hydrocarbons such as chloromethane, dichloromethane, and difluoroethane; alcohols such as methanol, ethanol, and isopropanol; and hydrogen. However, those that are in a gaseous state at normal temperature and pressure are preferred.

[0497] The amount of the chain transfer agent used is usually 1 to 10,000 ppm by mass, preferably 1 to 5,000 ppm by mass, based on the total amount of TFE supplied.

[0498] In the production of the TFE polymer, a saturated hydrocarbon having 12 or more carbon atoms, which is substantially inert to the reaction and becomes liquid under the above reaction conditions, can also be used as a dispersion stabilizer for the reaction system in an amount of 2 to 10 parts by mass per 100 parts by mass of the aqueous medium. Furthermore, ammonium carbonate, ammonium phosphate, etc. can be added as a buffer for adjusting the pH during the reaction.

[0499] Upon completion of the TFE polymerization, a polymer dispersion having a solid content of 1.0 to 50% by mass and an average primary particle size of 50 to 500 nm can be obtained. The lower limit of the solid content is preferably 5% by mass, more preferably 8% by mass. The upper limit is not particularly limited, but may be 40% by mass or even 35% by mass. The lower limit of the average primary particle size is preferably 100 nm, more preferably 150 nm. The upper limit is preferably 400 nm, more preferably 350 nm. The average primary particle size can be measured by dynamic light scattering. The average primary particle size can be measured by preparing an aqueous dispersion having a solid content of approximately 1.0% by mass, using dynamic light scattering at 25°C, with a refractive index of 1.3328 for the solvent (water) and a viscosity of 0.8878 mPa·s, and measuring 70 times in total. For dynamic light scattering, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used, for example.

[0500] Fine powders can be produced by coagulating aqueous dispersions of TFE polymers. The aqueous dispersions of TFE polymers can be used for various applications as fine powders after coagulation, washing, and drying. When coagulating the aqueous dispersions of TFE polymers, the aqueous dispersion obtained by polymerization of a polymer latex or the like is usually diluted with water to a polymer concentration of 5 to 20% by mass, and the pH is adjusted to neutral or alkaline, as needed, followed by stirring more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be carried out while stirring while adding a coagulant such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be carried out continuously using an in-line mixer or the like.

[0501] The concentration of the unaggregated TFE polymer in the wastewater resulting from the aggregation is preferably low from the viewpoint of productivity, more preferably less than 0.4% by mass, particularly preferably less than 0.3% by mass.

[0502] By adding a pigment for coloring or various fillers for improving mechanical properties before or during the coagulation, a pigmented or filled TFE polymer fine powder in which the pigment and filler are uniformly mixed can be obtained.

[0503] The drying of the wet powder obtained by coagulating the aqueous dispersion of the above-mentioned TFE polymer is usually carried out by using the means such as vacuum, high frequency, hot air, etc., while keeping the above-mentioned wet powder in a state where it is not very fluid, preferably in a state where it is left standing.The friction between powders, especially at high temperature, generally has an undesirable effect on the fine powder type TFE polymer.This is because the particle made up of this kind of TFE polymer has the property that it is easily fibrillated by small shear force, and loses the state of original stable particle structure.

[0504] The drying is carried out at a drying temperature of 10 to 300°C, preferably 100 to 300°C.

[0505] The resulting TFE polymer fine powder is preferable for molding, and suitable applications include tubes for hydraulic and fuel systems in aircraft and automobiles, flexible hoses for chemical solutions, steam, etc., and for electrical wire coating.

[0506] The aqueous dispersion of TFE polymer can also be stabilized and further concentrated by adding nonionic surfactant, and can be used in various applications as the composition of adding organic or inorganic filler according to purpose.By coating the above-mentioned composition on the substrate made of metal or ceramic, it can make the coating surface of non-adhesiveness and low friction coefficient, and has excellent gloss, smoothness, abrasion resistance, weather resistance and heat resistance, and is suitable for the coating of rolls, cooking utensils, etc., and the impregnation processing of glass cloth, etc.

[0507] An organosol of a TFE polymer can also be prepared from the aqueous dispersion. The organosol can contain the TFE polymer and an organic solvent. Examples of the organic solvent include ether-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ester-based solvents, aliphatic hydrocarbon-based solvents, aromatic hydrocarbon-based solvents, and halogenated hydrocarbon-based solvents. N-methyl-2-pyrrolidone, dimethylacetamide, and the like are preferably used. The organosol can be prepared, for example, by the method described in International Publication No. 2012 / 002038.

[0508] The aqueous dispersion of above-mentioned TFE polymer or the fine powder of above-mentioned TFE polymer can also be preferably used as processing aid.When used as processing aid, by mixing the aqueous dispersion or the fine powder with host polymer etc., it can improve the melt strength during the melt processing of host polymer, and can improve the mechanical strength, electrical properties, flame retardancy, anti-dripping property during burning and sliding property of the obtained polymer.

[0509] The above-mentioned aqueous dispersion of the TFE polymer or the above-mentioned TFE polymer fine powder is also preferably used as a binder for batteries and for dust prevention purposes.

[0510] The aqueous dispersion of the TFE polymer or the fine powder of the TFE polymer is also preferably used as a processing aid after being compounded with a resin other than the TFE polymer.The aqueous dispersion or the fine powder is suitable as a raw material for PTFE, for example, as described in JP-A-11-49912, U.S. Pat. No. 5,804,654, JP-A-11-29679, and JP-A-2003-2980.Processing aids using the aqueous dispersion or the fine powder are in no way inferior to the processing aids described in the above publications.

[0511] The aqueous dispersion of above-mentioned TFE polymer can also be mixed with the aqueous dispersion of melt-processable fluororesin to be coagulated, and be made into coprecipitated powder.Above-mentioned coprecipitated powder is suitable as processing aid.

[0512] Examples of the melt-processable fluororesin include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, ethylene / TFE / HFP copolymer [EFEP], etc., with PFA or FEP being preferred.

[0513] The aqueous dispersion preferably contains the melt-processable fluororesin.The melt-processable fluororesin can be exemplified by FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, EFEP, etc.The aqueous dispersion containing the melt-processable fluororesin can be used as coating material.The melt-processable fluororesin can sufficiently fuse the particles of the TFE polymer together, so that it can improve film-forming property and make the obtained coating film glossy.

[0514] The fluorine-free resin that adds above-mentioned coprecipitated powder can be powder, can be pellet, can be emulsion.In order to thoroughly mix each resin, it is preferable to add above-mentioned by known method such as extrusion kneading, roll kneading, etc., while applying shearing force.

[0515] The aqueous dispersion of the TFE polymer is also preferably used as a dust-suppressing treatment. The dust-suppressing treatment can be used in a method of mixing the TFE polymer with a dust-generating substance and subjecting the mixture to a compression-shear action at a temperature of 20 to 200°C to fibrillate the TFE polymer and suppress the dust of the dust-generating substance, such as the methods described in Japanese Patent No. 2827152 and Japanese Patent No. 2538783. The aqueous dispersion of the TFE polymer can be suitably used in the dust-suppressing treatment composition described in WO 2007 / 004250, for example, and can also be suitably used in the dust-suppressing treatment method described in WO 2007 / 000812.

[0516] The dust suppression treatment agent is suitable for use in the fields of building materials, soil stabilization materials, solidification materials, fertilizers, landfill disposal of incineration ash and hazardous substances, explosion prevention, cosmetics, and dust suppression treatment of sand for pet excretion, such as cat litter.

[0517] The aqueous dispersion of the TFE polymer is also preferably used as a raw material for obtaining TFE polymer fibers by the dispersion spinning method. The dispersion spinning method is a method in which the aqueous dispersion of the TFE polymer and the aqueous dispersion of a matrix polymer are mixed, the mixture is extruded to form an intermediate fiber structure, and the intermediate fiber structure is fired to decompose the matrix polymer and sinter the TFE polymer particles, thereby obtaining TFE polymer fibers.

[0518] The high molecular weight PTFE powder obtained by polymerization has extensibility and non-melt processability, and is also useful as a raw material for an extruded body (porous body). When this extruded body is a membrane (PTFE extruded membrane or PTFE porous membrane), it can be extruded by a known PTFE extrusion method. By stretching, the high molecular weight PTFE is easily fibrillated, forming a PTFE porous body (membrane) consisting of nodes and fibers. Preferably, a uniaxially stretched membrane can be obtained by roll-stretching a sheet-shaped or rod-shaped paste extrudate in the extrusion direction. Furthermore, a biaxially stretched membrane can also be obtained by stretching in the width direction using a tenter or the like. It is also preferable to perform a semi-baking treatment before stretching.

[0519] This expanded PTFE is a porous body with high porosity and can be suitably used as a filter medium for various precision filtration filters such as air filters and chemical filters, a support material for polymer electrolyte membranes, etc. It is also useful as a material for products used in the fields of textiles, medicine, electrochemicals, sealing materials, air filtration, ventilation / internal pressure adjustment, liquid filtration, general consumer goods, etc. Specific uses are exemplified below.

[0520] Electrochemical field: Dielectric material prepreg, EMI shielding material, heat transfer material, etc. More specifically, printed wiring boards, electromagnetic shielding materials, insulating heat transfer materials, insulating materials, etc. Sealing material field: Gaskets, packings, pump diaphragms, pump tubes, aircraft sealing materials, etc.

[0521] Air filtration field ULPA filters (for semiconductor manufacturing), HEPA filters (for hospitals and semiconductor manufacturing), cylindrical cartridge filters (for industrial use), bag filters (for industrial use), heat-resistant bag filters (for exhaust gas treatment), heat-resistant pleated filters (for exhaust gas treatment), SINBRAN filters (for industrial use), catalytic filters (for exhaust gas treatment), adsorbent filters (for HDD integration), adsorbent vent filters (for HDD integration), vent filters (for HDD integration, etc.), vacuum cleaner filters (for vacuum cleaners), general-purpose multi-layer felt material, GT cartridge filters (for GT compatible products), cooling filters (for electronic equipment housings), etc.

[0522] Ventilation / internal pressure regulation field: Freeze-drying materials such as freeze-drying containers, automotive ventilation materials for electronic circuits and lamps, container applications such as container caps, protective ventilation applications for electronic devices including small terminals such as tablet devices and mobile phones, medical ventilation applications, etc.

[0523] Liquid filtration field: Semiconductor liquid filtration filters (for semiconductor manufacturing), hydrophilic PTFE filters (for semiconductor manufacturing), filters for chemicals (for chemical liquid treatment), filters for pure water production lines (for pure water production), backwash type liquid filtration filters (for industrial wastewater treatment), etc.

[0524] General consumer goods: Clothing, cable guides (movable wires for motorcycles), motorcycle clothing, cast liners (medical supporters), vacuum cleaner filters, bagpipes (musical instruments), cables (signal cables for guitars, etc.), strings (for stringed instruments), etc.

[0525] Textile field: PTFE fiber (textile material), sewing thread (textile), weaving thread (textile), rope, etc.

[0526] Medical field: Implants (stretched products), artificial blood vessels, catheters, general surgery (tissue reinforcement materials), head and neck products (dura mater replacement), oral health (tissue regenerative medicine), orthopedics (bandages), etc.

[0527] The manufacturing method of the present disclosure can also be used to manufacture low-molecular-weight PTFE. Low-molecular-weight PTFE can be manufactured by polymerization, or by lowering the molecular weight of high-molecular-weight PTFE obtained by polymerization using a known method (thermal decomposition, decomposition by irradiation, etc.).

[0528] Low-molecular-weight PTFE (also called PTFE micropowder) having a molecular weight of 600,000 or less has excellent chemical stability, extremely low surface energy, and is resistant to fibrillation. Therefore, it is suitable as an additive for improving the slipperiness and texture of coating surfaces in the production of plastics, inks, cosmetics, paints, greases, office automation equipment components, toners, etc. (see, for example, JP-A-10-147617).

[0529] Furthermore, a low-molecular-weight PTFE may be obtained by dispersing a polymerization initiator and polymer (I) in an aqueous medium in the presence of a chain transfer agent, and polymerizing TFE with TFE or a monomer copolymerizable with TFE. In this case, the chain transfer agent is preferably at least one selected from the group consisting of alkanes having 2 to 4 carbon atoms. Specifically, methane, ethane, propane, butane, and isobutane are more preferred, and ethane and propane are even more preferred. In this case, the amount of chain transfer agent is preferably 10 mass ppm or more or more than 10 mass ppm relative to the aqueous medium.

[0530] When the low-molecular-weight PTFE obtained by the above polymerization is used as a powder, the aqueous dispersion can be coagulated to form powder particles.

[0531] In this disclosure, high molecular weight PTFE refers to non-melt-processible and fibrillating PTFE, while low molecular weight PTFE refers to melt-processible and non-fibrillating PTFE.

[0532] The term "non-melt processable" means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point in accordance with ASTM D 1238 and D 2116.

[0533] The presence or absence of fibrillation properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," which is a powder made from a TFE polymer. Paste extrusion is usually possible because high molecular weight PTFE has fibrillation properties. If the unsintered molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it breaks when pulled at 0% elongation, it can be considered to have no fibrillation properties.

[0534] The high-molecular-weight PTFE preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D 4895-89. In this disclosure, "high molecular weight" means that the standard specific gravity is within the above range.

[0535] The low-molecular-weight PTFE has a melt viscosity of 1×10 at 380° C. ２ ~7 x 10 ５ In the present disclosure, "low molecular weight" means that the melt viscosity is within the above range. The melt viscosity is measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2 g sample preheated at 380°C for 5 minutes, and maintained at the above temperature under a load of 0.7 MPa.

[0536] The melt viscosity of the high molecular weight PTFE is much higher than that of the low molecular weight PTFE, making it difficult to measure its melt viscosity accurately. On the other hand, although the melt viscosity of the low molecular weight PTFE can be measured, it is difficult to obtain a molded product from the low molecular weight PTFE that can be used to measure its standard gravity, making it difficult to measure its accurate standard gravity. Therefore, in this disclosure, standard specific gravity is used as an indicator of the molecular weight of the high molecular weight PTFE, and melt viscosity is used as an indicator of the molecular weight of the low molecular weight PTFE. Note that no measurement method is known that can directly determine the molecular weight of either the high molecular weight PTFE or the low molecular weight PTFE.

[0537] The high-molecular-weight PTFE preferably has a peak temperature of 333 to 347° C., more preferably 335 to 345° C. The low-molecular-weight PTFE preferably has a peak temperature of 322 to 333° C., more preferably 324 to 332° C. The peak temperature can be specified as the temperature corresponding to the maximum value that appears on a differential thermal (DTA) curve obtained by using a TG / DTA (thermogravimetric / differential thermal analyzer) to raise the temperature of PTFE that has not been heated to a temperature of 300° C. or higher at a rate of 10° C. / min.

[0538] The peak temperature of PTFE may be 322 to 347°C. When PTFE is high molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 347°C or lower, 346°C or lower, 345°C or lower, 344°C or lower, 343°C or lower, 342°C or lower, 341°C or lower, or 340°C or lower. When PTFE is high molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 333°C or higher or 335°C or higher. When PTFE is low molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 333°C or lower or 332°C or lower. When PTFE is low molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 322°C or higher or 324°C or higher.

[0539] The average primary particle diameter of the primary particles of low molecular weight PTFE is preferably 10 to 300 nm, more preferably 50 nm or more, even more preferably 100 nm or more, particularly preferably 150 nm or more, more preferably 250 nm or less.The relatively small average primary particle diameter of the primary particles can be obtained, for example, by adding a modified monomer to the polymerization system at the initial stage of TFE polymerization.

[0540] The average primary particle size of the primary particles of low-molecular-weight PTFE can be measured by dynamic light scattering. First, an aqueous dispersion of low-molecular-weight PTFE with a polymer solids concentration adjusted to about 1.0% by mass is prepared, and the average primary particle size can be measured using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa s, and an accumulation number of 70. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method.

[0541] The high-molecular-weight PTFE preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when PTFE that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 52mJ / mg or more. The heat of fusion of PTFE is more preferably 55mJ / mg or more, and even more preferably 58mJ / mg or more.

[0542] An unsintered tape (green tape) can also be obtained from the PTFE fine powder obtained above.

[0543] (II) Melt-processable fluororesin (1) In the production method of the present disclosure, the polymerization of FEP is preferably carried out at a polymerization temperature of 10 to 150° C. and a polymerization pressure of 0.3 to 6.0 MPaG.

[0544] The monomer composition (mass %) of FEP is preferably TFE:HFP=(60-95):(5-40), more preferably (85-92):(8-15).

[0545] In addition to TFE and HFP, other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, HFP, and other monomers as FEP. Examples of the other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and HFP) and non-fluorine-containing monomers. One or more types of other monomers may be used. Perfluoro(alkyl vinyl ether) is preferred as the other monomer. The content of the other monomer units in FEP may be 0.1 to 2% by mass based on the total monomer units.

[0546] In the polymerization of the above-mentioned FEP, the polymer (I) can be used within the range of use in the production method of the present disclosure, but is usually added in an amount of 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium.

[0547] In the polymerization of the above-mentioned FEP, it is preferable to use cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, etc. as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, etc. as a pH buffer.

[0548] The aqueous dispersion of FEP obtained by the manufacturing method of the present disclosure may be subjected to post-treatment such as concentration as necessary, dried, powdered, and then melt-extruded to form pellets. The aqueous medium in the aqueous dispersion of FEP may contain additives such as a nonionic surfactant as necessary, but may also contain a water-soluble organic solvent such as a water-soluble alcohol, or may not contain a water-soluble organic solvent.

[0549] Furthermore, melt extrusion can be carried out by appropriately setting extrusion conditions as long as the extrusion conditions are generally such that pelletization is possible.

[0550] In the manufacturing method of the present disclosure, the obtained FEP has -CF ３ , -CF ２ It may have a terminal group such as -COOH, -CH ２ OH, -COF, -CF=CF-, -CONH ２ , -COOCH ３ It is preferable that the content of thermally unstable groups such as those mentioned above (hereinafter referred to as "unstable terminal groups") is low or absent.

[0551] The unstable terminal groups are chemically unstable and therefore not only reduce the heat resistance of the resin but also cause an increase in the attenuation of the resulting electric wire.

[0552] In the production method of the present disclosure, the polymer at the end of polymerization is treated by removing the unstable terminal group and -CF ２ The total number of carbon atoms is 1 x 10 ６ It is preferable to produce the carbon atoms so that the number of carbon atoms is 50 or less per unit. More preferably, the number of carbon atoms is 1×10 ６The number of unstable terminal groups and —CF ２ No H terminal groups, all -CF ３ It may also be a terminal group.

[0553] Unstable end groups and -CF ２ The H terminal group is converted to -CF by fluorination treatment. ３ The fluorination treatment method is not particularly limited, but an example is a method in which the polymer is exposed to a fluorine radical source that generates fluorine radicals under fluorination treatment conditions. Examples of the fluorine radical source include fluorine gas and CoF ３ , AgF ２ , U.F. ６ , OF ２ , N ２ F ２ , C.F. ３ OF and halogen fluorides, such as IF ５ , ClF ３ and the like. Among these, a method of directly contacting fluorine gas with FEP obtained by the production method of the present disclosure is preferred, and from the viewpoint of reaction control, the contact is preferably carried out using diluted fluorine gas having a fluorine gas concentration of 10 to 50 mass%. The diluted fluorine gas can be obtained by diluting fluorine gas with an inert gas such as nitrogen gas or argon gas. The fluorine gas treatment can be carried out at a temperature of, for example, 100 to 250°C. The treatment temperature is not limited to the above range and can be set appropriately depending on the situation. The fluorine gas treatment is preferably carried out by continuously or intermittently supplying diluted fluorine gas into a reactor. This fluorination treatment may be carried out on either a dry powder after polymerization or melt-extruded pellets.

[0554] The FEP obtained by the manufacturing method of the present disclosure has good moldability and is less likely to produce molding defects, and also has good heat resistance, chemical resistance, solvent resistance, insulating properties, electrical properties, etc.

[0555] The method for producing the FEP powder is a method for obtaining the powder by drying and powdering the FEP obtained by the above-described production method of the present disclosure.

[0556] The powder may be fluorinated. The method for producing the fluorinated powder is a method for obtaining the fluorinated powder by supplying fluorine gas to the powder obtained by the method for producing the powder described above to fluorinate the powder.

[0557] The method for producing FEP pellets is a method for obtaining pellets by pelletizing the FEP obtained by the above-described production method of the present disclosure.

[0558] The pellets may be fluorinated. The method for producing fluorinated pellets is a method for obtaining fluorinated pellets by supplying fluorine gas to the pellets obtained by the above-described method for producing pellets, thereby fluorinating the pellets.

[0559] Therefore, this FEP can be used to produce various molded products such as covering materials for electric wires, foamed electric wires, cables, wires, etc., as well as tubes, films, sheets, filaments, etc.

[0560] (2) In the production method of the present disclosure, the polymerization of TFE / perfluoro(alkyl vinyl ether) copolymers such as PFA and MFA and TFE / perfluoroallyl ether copolymers is preferably carried out at a polymerization temperature of 10 to 100°C and a polymerization pressure of 0.3 to 6.0 MPaG.

[0561] The preferred monomer composition (mol %) of the TFE / perfluoro(alkyl vinyl ether) copolymer is TFE:perfluoro(alkyl vinyl ether)=(90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoro(alkyl vinyl ether) is preferably a compound represented by the formula: CF ２ =CFORf ４ (In the formula, Rf ４ is a perfluoroalkyl group having 1 to 6 carbon atoms).

[0562] In addition to TFE and perfluoro(alkyl vinyl ether), other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, perfluoro(alkyl vinyl ether), and other monomers as a TFE / perfluoro(alkyl vinyl ether) copolymer. Examples of the other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and perfluoro(alkyl vinyl ether)) and fluorine-free monomers. One or more types of other monomers may be used. The content of the other monomer units in the TFE / perfluoro(alkyl vinyl ether) copolymer may be 0.1 to 2 mass% based on the total monomer units.

[0563] The preferred monomer composition (mol %) of the TFE / perfluoroallyl ether copolymer is TFE:perfluoroallyl ether=(90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoroallyl ether is a compound represented by the formula: CF ２ =CFCF ２ ORf ４ (In the formula, Rf ４ is a perfluoroalkyl group having 1 to 6 carbon atoms).

[0564] In addition to TFE and perfluoroallyl ether, other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, perfluoroallyl ether, and other monomers as a TFE / perfluoroallyl ether copolymer. Examples of other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and perfluoroallyl ether) and fluorine-free monomers. One or more types of other monomers may be used. The content of other monomer units in the TFE / perfluoroallyl ether copolymer may be 0.1 to 2 mass% based on the total monomer units.

[0565] In the polymerization of the TFE / perfluoro(alkyl vinyl ether) copolymer and the TFE / perfluoroallyl ether copolymer, the polymer (I) can be used within the range of use in the production method of the present disclosure, but it is usually preferable to add it in an amount of 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium.

[0566] In the polymerization of the above-mentioned TFE / perfluoro(alkyl vinyl ether) copolymer and TFE / perfluoroallyl ether copolymer, it is preferable to use cyclohexane, methanol, ethanol, propanol, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, methane, ethane, etc. as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, etc. as a pH buffer.

[0567] The aqueous dispersion of TFE / perfluoro(alkyl vinyl ether) copolymer such as PFA or MFA and TFE / perfluoroallyl ether copolymer obtained by the manufacturing method of the present disclosure can be subjected to post-treatment such as concentration as required, dried, powdered, and then melt-extruded to form pellets.The aqueous medium in the above-mentioned aqueous dispersion can contain additives such as nonionic surfactants as required, but can also contain water-soluble organic solvents such as water-soluble alcohols, or can also not contain water-soluble organic solvents.

[0568] Furthermore, melt extrusion can be carried out by appropriately setting extrusion conditions as long as the extrusion conditions are generally such that pelletization is possible.

[0569] The copolymer is preferably treated with fluorine gas in order to improve its heat resistance and further enhance the effect of inhibiting the permeation of chemical solutions into the molded article.

[0570] The fluorine gas treatment is carried out by bringing fluorine gas into contact with the copolymer. However, since the reaction with fluorine is highly exothermic, it is preferable to dilute the fluorine with an inert gas such as nitrogen. The fluorine content in the fluorine gas / inert gas mixture is 1 to 100% by mass, preferably 10 to 25% by mass. The treatment temperature is 150 to 250°C, preferably 200 to 250°C, and the fluorine gas treatment time is 3 to 16 hours, preferably 4 to 12 hours. The gas pressure for the fluorine gas treatment ranges from 1 to 10 atmospheres, but atmospheric pressure is preferably used. When a reactor is used at atmospheric pressure, the fluorine gas / inert gas mixture may be continuously passed through the reactor. As a result, the unstable ends of the copolymer are converted to -CF ３ It is converted to a terminal end and becomes thermally stable.

[0571] As for molding the copolymer and its composition, molding methods such as compression molding, transfer molding, extrusion molding, injection molding, and blow molding can be applied in the same manner as conventional PFA.

[0572] Desired molded products can be obtained by such molding methods, and examples of molded products include sheets, films, packing, round bars, square bars, pipes, tubes, round tanks, square tanks, tanks, wafer carriers, wafer boxes, beakers, filter housings, flow meters, pumps, valves, cocks, connectors, nuts, electric wires, and heat-resistant electric wires.

[0573] Among these, it can be suitably used for tubes, pipes, tanks, connectors, etc. used in various chemical reaction equipment, semiconductor manufacturing equipment, and acid or alkaline chemical supply equipment, which require impermeability to chemicals.

[0574] Furthermore, a primer composition can be obtained by adding a nonionic surfactant to the aqueous dispersion of TFE / perfluoro(alkyl vinyl ether) copolymer such as PFA or MFA and TFE / perfluoroallyl ether copolymer, and dissolving or dispersing polyethersulfone, polyamideimide and / or polyimide and metal powder in an organic solvent as required.This primer composition can also be used in the method for coating a metal surface with a fluororesin, which comprises applying this primer composition to a metal surface, applying a melt-processable fluororesin composition on the primer layer thus formed, and baking the melt-processable fluororesin composition layer together with the primer layer.

[0575] (3) In the production method of the present disclosure, the polymerization of ETFE is preferably carried out at a polymerization temperature of 10 to 100° C. and a polymerization pressure of 0.3 to 2.0 MPaG.

[0576] The preferred monomer composition (mol %) of ETFE is TFE:ethylene=(50 to 99):(50 to 1).

[0577] In addition to ethylene and TFE, other monomers that can be copolymerized with these monomers can also be polymerized to obtain the copolymer of ethylene, TFE and other monomers as ETFE.Other monomers can include the above-mentioned fluorine-containing monomers (but excluding TFE) and fluorine-free monomers (but excluding ethylene).Other monomers can use one or more kinds.

[0578] Other monomers include hexafluoropropylene, perfluorobutylethylene, perfluorohexylethylene, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooct-1-ene, 2,3,3,4,4,5,5-heptafluoro-1-pentene (CH ２ =CFCF ２ CF ２ CF ２ H), 2-trifluoromethyl-3,3,3-trifluoropropene ((CF ３ ) ２ CF=CH ２ ) is preferred.

[0579] The content of other monomer units in ETFE may be 0 to 20% by mass based on the total monomer units. A preferred mass ratio is TFE:ethylene:other monomer=(63 to 94):(27 to 2):(1 to 10).

[0580] In the polymerization of ETFE, the polymer (I) can be used within the range of use in the production method of the present disclosure, but is usually added in an amount of 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium.

[0581] In the above polymerization of ETFE, it is preferable to use, as a chain transfer agent, cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, or the like.

[0582] The aqueous dispersion of ETFE obtained by the production method of the present disclosure may be subjected to post-treatment such as concentration as necessary, dried, powdered, and then melt-extruded to form pellets.The aqueous medium in the above-mentioned aqueous dispersion may contain additives such as nonionic surfactants as necessary, but may also contain a water-soluble organic solvent such as a water-soluble alcohol, or may not contain a water-soluble organic solvent.

[0583] Furthermore, melt extrusion can be carried out by appropriately setting extrusion conditions as long as the extrusion conditions are generally such that pelletization is possible.

[0584] The ETFE sheet can be extrusion molded into a sheet. That is, ETFE powder or pellets can be melted, continuously extruded through a die, and cooled to obtain a sheet-like molded product. Additives may be added to ETFE.

[0585] As the additive, known additives can be used as appropriate. Specific examples include ultraviolet absorbers, light stabilizers, antioxidants, infrared absorbers, flame retardants, flame-retardant fillers, organic pigments, inorganic pigments, dyes, etc. Inorganic additives are preferred from the viewpoint of excellent weather resistance. The content of the additive in the ETFE sheet is preferably 20% by mass or less, particularly preferably 10% by mass or less, relative to the total mass of the ETFE sheet.

[0586] The ETFE sheet has excellent mechanical strength and appearance, and is therefore suitable as a membrane material (roofing material, ceiling material, exterior wall material, interior wall material, covering material, etc.) for membrane structure buildings (sports facilities, horticultural facilities, atriums, etc.). Furthermore, in addition to membrane materials for membrane-structured buildings, the present invention is also useful for, for example, outdoor-use board materials (soundproof walls, windbreak fences, wave fences, garage canopies, shopping malls, walkway walls, roofing materials), glass shatterproof films, heat-resistant and water-resistant sheets, building materials (tent materials for tent warehouses, sunshade membrane materials, partial roof materials for lighting, window materials in place of glass, fire-retardant partition membrane materials, curtains, exterior wall reinforcement, waterproof membranes, smoke-proof membranes, non-flammable transparent partitions, road reinforcement, interiors (lighting, walls, brands, etc.), exteriors (tents, signs, etc.), etc.), lifestyle and leisure goods (fishing rods, rackets, golf clubs, projection screens, etc.), automotive materials (canopies, vibration-damping materials, bodies, etc.), aircraft materials, ship materials, home appliance exteriors, tanks, inner walls of containers, filters, construction membrane materials, electronic materials (printed circuit boards, wiring boards, insulating films, release films, etc.), surface materials for solar cell modules, mirror protective materials for solar thermal power generation, surface materials for solar water heaters, etc.

[0587] (4) An electrolyte polymer precursor can also be produced using the production method of the present disclosure. In the production method of the present disclosure, the polymerization of the electrolyte polymer precursor is preferably carried out at a polymerization temperature of 10 to 100°C and a polymerization pressure of 0.1 to 2.0 MPaG. The electrolyte polymer precursor is a polymer having a -SO ２ X １５１ , -COZ １５１ or -POZ １５２ Z １５３ (X １５１ , Z １５１ , Z １５２ and Z １５３ The ion-exchange polymer is composed of a monomer containing a functional group represented by the formula (which will be described later), and can be converted into an ion-exchange polymer through hydrolysis treatment.

[0588] The monomer used for the electrolyte polymer precursor is represented by the general formula (150): CF ２ =CF-O-(CF ２ CFY １５１ -O) ｎ -(CFY １５２) ｍ -A １５１ (In the formula, Y １５１ represents a fluorine atom, a chlorine atom, -SO ２ It represents a F group or a perfluoroalkyl group. The perfluoroalkyl group is an etheric oxygen and -SO ２ The group n may contain an F group. n represents an integer of 0 to 3. １５１ may be the same or different. １５２ represents a fluorine atom, a chlorine atom, or —SO ２ represents an F group, and m represents an integer of 1 to 5. １５２ may be the same or different. １５１ is -SO ２ X １５１ , -COZ １５１ or -POZ １５２ Z １５３ represents. １５１ is F, Cl, Br, I, -OR １５１ or -NR １５２ R １５３ Represents Z. １５１ , Z １５２ and Z １５３ are the same or different and represent -NR １５４ R １５５ Or -OR １５６ Represents R １５１ , R １５２ , R １５３ , R １５４ , R １５５ and R １５６ are the same or different and represent H, ammonium, an alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group. ) Examples of the monomer used for the electrolyte polymer precursor include a compound containing two fluorosulfonyl groups described in WO 2007 / 013532, and -SO ２Examples also include perfluoromonomers having an F group and a dioxolane ring. The preferred monomer composition (mol %) of the electrolyte polymer precursor is TFE:vinyl ether=(50 to 99):(50 to 1), more preferably TFE:vinyl ether=(50 to 93):(50 to 7).

[0589] The electrolyte polymer precursor may be modified with a third monomer in an amount of 0 to 20% by mass of the total monomers, such as CTFE, vinylidene fluoride, perfluoroalkyl vinyl ether, perfluorobutenyl vinyl ether, cyclic monomers such as perfluoro-2,2-dimethyl-1,3-dioxolane and perfluoro-2-methylene-4-methyl-1,3-dioxole, and polyfunctional monomers such as divinylbenzene.

[0590] The electrolyte polymer precursor thus obtained can be formed into a membrane, for example, and then subjected to hydrolysis with an alkaline solution and treatment with a mineral acid to form a polymer electrolyte membrane, which can be used in fuel cells, electrolysis devices, redox flow batteries, and the like. Alternatively, an electrolyte polymer dispersion can be obtained by subjecting the electrolyte polymer precursor to hydrolysis with an alkaline solution while maintaining its dispersed state. Subsequently, the electrolyte polymer precursor can be dissolved in, for example, a water / alcohol mixed solvent by heating to 120°C or higher in a pressure vessel to form a solution. The solution thus obtained can be used, for example, as a binder for electrodes, or can be combined with various additives and cast into a membrane, which can be used, for example, as an antifouling coating film or an organic actuator.

[0591] (5) TFE / VDF Copolymer In the production method of the present disclosure, the polymerization temperature for the TFE / VDF copolymer is not particularly limited and may be 0 to 100° C. The polymerization pressure is determined appropriately depending on other polymerization conditions such as the polymerization temperature, but may usually be 0 to 9.8 MPaG.

[0592] The preferred monomer composition (mol %) of the TFE / VDF copolymer is TFE:VDF=(5-90):(95-10). The TFE / VDF copolymer may also be modified with a third monomer within the range of 0-50 mol % of the total monomers. The preferred ratio is TFE:ethylene:third monomer=(30-85):(10-69.9):(0.1-10).

[0593] The third monomer may be a compound represented by the formula: CX １１ X １２ =CX １３ (CX １４ X １５ ) ｎ１１ X １６ (In the formula, X １１ ~X １６ are the same or different and represent H, F or Cl, and n11 represents an integer of 0 to 8, excluding TFE and VDF, or a monomer represented by the formula: CX ２１ X ２２ =CX ２３ -O(CX ２４ X ２５ ) ｎ２１ X ２６ (In the formula, X ２１ ~X ２６ are the same or different and represent H, F or Cl, and n21 represents an integer of 0 to 8.

[0594] The third monomer may also be a fluorine-free ethylenic monomer. In order to maintain heat resistance and chemical resistance, the fluorine-free ethylenic monomer is preferably selected from ethylenic monomers having 6 or less carbon atoms. Examples include ethylene, propylene, 1-butene, 2-butene, vinyl chloride, vinylidene chloride, alkyl vinyl ethers (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, etc.), maleic acid, itaconic acid, 3-butenoic acid, 4-pentenoic acid vinyl sulfonic acid, acrylic acid, and methacrylic acid.

[0595] In the polymerization of the TFE / VDF copolymer, the polymer (I) can be used within the range of use in the production method of the present disclosure, but is usually added in an amount of 0.0001 to 5% by mass relative to 100% by mass of the aqueous medium.

[0596] The TFE / VDF copolymer may be amidated by contacting it with aqueous ammonia, ammonia gas, or a nitrogen compound capable of producing ammonia.

[0597] The TFE / VDF copolymer obtained by the above-mentioned method is also preferably used as a raw material for obtaining a TFE / VDF copolymer fiber by a spinning and drawing method. The spinning and drawing method is a method in which the TFE / VDF copolymer is melt-spun, cooled and solidified to obtain an undrawn yarn, and then the undrawn yarn is run through a heated cylinder to be drawn, thereby obtaining a TFE / VDF copolymer fiber.

[0598] The TFE / VDF copolymer can also be dissolved in an organic solvent to obtain a solution of the TFE / VDF copolymer. Examples of the organic solvent include nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and dimethylformamide; ketone-based solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ester-based solvents such as ethyl acetate and butyl acetate; ether-based solvents such as tetrahydrofuran and dioxane; and mixtures thereof. The solution can be used as a binder for batteries.

[0599] It is also preferred to coat the aqueous dispersion of the TFE / VDF copolymer on a porous substrate made of polyolefin resin and use it as a composite porous membrane.It is also preferred to disperse inorganic particles and / or organic particles in the aqueous dispersion, coat it on a porous substrate and use it as a composite porous membrane.The composite porous membrane obtained in this way can be used as a separator for lithium secondary batteries, etc.

[0600] The melt-processible fluororesin powder can be suitably used as a powder coating. When a powder coating made of the melt-processible fluororesin powder is applied to a substrate, a coating with a smooth surface can be obtained. Melt-processible fluororesin powders having an average particle size of 1 μm or more and less than 100 μm are particularly suitable as powder coatings to be used in electrostatic coating, and melt-processible fluororesin powders having an average particle size of 100 μm or more and 1000 μm or less are particularly suitable as powder coatings to be used in spin coating or spin molding.

[0601] The melt-processible fluororesin powder can be produced by drying and powdering the melt-processible fluororesin obtained by the production method of the present disclosure. The production method for producing the melt-processible fluororesin powder also constitutes part of the present disclosure.

[0602] (III) Fluororubber In the production method of the present disclosure, the polymerization of the fluororubber is carried out by charging pure water and polymer (I) into a pressure-resistant reaction vessel equipped with a stirrer, deoxidizing, charging monomers, adjusting the temperature to a predetermined level, and adding a polymerization initiator to start the reaction. As the pressure decreases as the reaction progresses, additional monomers are continuously or intermittently supplied to maintain the initial pressure. Once a predetermined amount of monomer has been supplied, the supply is stopped, the monomers in the reaction vessel are purged, and the temperature is returned to room temperature to terminate the reaction. In this case, the polymer latex can be continuously removed from the reaction vessel.

[0603] In particular, when producing the above-mentioned fluororubber, as disclosed in International Publication No. 00 / 01741, it is possible to use a method in which fluoropolymer fine particles are first synthesized at a high concentration as described above, then diluted and further polymerized, thereby making it possible to increase the final polymerization rate compared to normal polymerization.

[0604] The polymerization conditions for the fluororubber are appropriately selected from the viewpoints of the desired properties of the polymer and control of the polymerization rate, and the polymerization is carried out at a temperature of usually −20 to 200° C., preferably 5 to 150° C., and a pressure of usually 0.5 to 10 MPaG, preferably 1 to 7 MPaG. The pH of the polymerization medium is preferably maintained at 2.5 to 13 by a known method or the like using a pH adjuster described below.

[0605] Monomers used in the polymerization of the fluororubber include, in addition to vinylidene fluoride, fluorine-containing ethylenically unsaturated monomers that have at least the same number of fluorine atoms as the carbon atoms and are copolymerizable with vinylidene fluoride. Examples of the fluorine-containing ethylenically unsaturated monomers include trifluoropropene, tetrafluoropropene, pentafluoropropene, hexafluoropropene, 2,3,3,3-tetrafluoropropene, hexafluorobutene, and octafluorobutene. Among these, hexafluoropropene and 2,3,3,3-tetrafluoropropene are particularly suitable due to the properties of the elastomer obtained when they block the crystal growth of the polymer. Examples of the fluorine-containing ethylenically unsaturated monomers include trifluoroethylene, TFE, and CTFE. Fluorine-containing monomers having one or more chlorine and / or bromine substituents can also be used. Perfluoro(alkyl vinyl ethers), such as perfluoro(methyl vinyl ether), can also be used. TFE and HFP are preferred for producing fluororubbers.

[0606] The preferred monomer composition (mass %) of the fluororubber is vinylidene fluoride:HFP:TFE=(20-70):(30-48):(0-36). The fluororubber of this composition exhibits good elastomeric properties, chemical resistance, and thermal stability.

[0607] In the polymerization of the fluororubber, the polymer (I) can be used within the range of use in the production method of the present disclosure, but is usually added in an amount of 0.0001 to 20% by mass relative to 100% by mass of the aqueous medium, preferably 10% by mass or less, and more preferably 2% by mass or less.

[0608] In the polymerization of the fluororubber, known inorganic radical polymerization initiators can be used as the polymerization initiator. As the inorganic radical polymerization initiator, conventionally known water-soluble inorganic peroxides, such as sodium, potassium, and ammonium persulfates, perphosphates, perborates, percarbonates, or permanganates, are particularly useful. The radical polymerization initiator can be further activated with a reducing agent, such as sodium, potassium, or ammonium sulfites, bisulfites, metabisulfites, hyposulfites, thiosulfates, phosphites, or hypophosphites, or with easily oxidizable metal compounds, such as ferrous salts, cuprous salts, or silver salts. A preferred inorganic radical polymerization initiator is ammonium persulfate, and it is more preferred to use ammonium persulfate and sodium bisulfite in a redox system.

[0609] The concentration of the polymerization initiator added is appropriately determined depending on the molecular weight of the target fluoropolymer and the polymerization reaction rate, but is set to an amount of 0.0001 to 10% by mass, preferably 0.01 to 5% by mass, relative to 100% by mass of the total amount of monomers.

[0610] In the polymerization of the fluororubber, known chain transfer agents can be used, including hydrocarbons, esters, ethers, alcohols, ketones, chlorine compounds, carbonates, iodine compounds, etc. Among these, isopentane, diethyl malonate, and ethyl acetate are preferred from the viewpoint of being less likely to decrease the reaction rate, and I(CF ２ ) ４ I, I (CF ２ ) ６ I, ICH ２ Diiodine compounds such as I are preferred in that they can iodine the polymer terminals and can be used as reactive polymers.

[0611] The amount of the chain transfer agent used is usually 0.5×10 －３ ~5 x 10 －３ mol%, preferably 1.0×10 －３ ~3.5 x 10 －３ It is preferably expressed as mole percent.

[0612] In the polymerization of the fluororubber, phosphates, sodium hydroxide, potassium hydroxide, etc. can be preferably used as a pH adjuster.

[0613] The aqueous dispersion of fluororubber obtained by the production method of the present disclosure has a solids concentration of 1.0 to 40 mass%, an average particle size of 0.03 to 1 μm, preferably 0.05 to 0.5 μm, and a number average molecular weight of 1,000 to 2,000,000 at the time of completion of polymerization.

[0614] The aqueous dispersion of fluororubber obtained by the production method of the present disclosure may be subjected to treatments such as coagulation and heating. The coagulation can be carried out by adding alkaline earth and earth metal salts to the aqueous dispersion. Examples of alkaline earth and earth metal salts include sulfates, nitrates, hydrochlorides, and acetates of calcium, magnesium, aluminum, and the like. The coagulated fluoroelastomer may be washed with water to remove small amounts of impurities such as buffer solutions and salts present in the fluoroelastomer, and then the washed fluoroelastomer may be dried. The drying temperature is preferably 40 to 200°C, more preferably 60 to 180°C, and even more preferably 80 to 150°C.

[0615] Among the fluororubbers, perfluororubber (perfluoroelastomer) can be obtained by polymerizing a perfluoromonomer in an aqueous medium in the presence of polymer (I).

[0616] Perfluoromonomers include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and compounds represented by the general formula: CF ２ =CF-ORf １３ (In the formula, Rf １３ represents a perfluoroalkyl group having 1 to 8 carbon atoms, a fluoromonomer represented by the general formula: CF ２ = CFOCF ２ ORf １４ (In the formula, Rf １４is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms), and ２ = CFO (CF ２ CF (Y １５ ) O) ｍ (CF ２ ) ｎ F (wherein, Y １５ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.

[0617] In the polymerization of perfluoromonomers, a monomer that provides a crosslinking site may be polymerized together with the perfluoromonomers.

[0618] The polymer (I) used in the method for producing a perfluoroelastomer preferably has an ion exchange capacity of 1.50 meq / g or more. The ion exchange capacities of the polymer (I) are, in order of increasing preference, 1.75 meq / g or more, 2.00 meq / g or more, 2.40 meq / g or more, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (I) and can be calculated from the composition of the polymer (I). The ion exchange capacity is determined by the content of precursor groups (for example, -COOCH ３ ) are not considered ionic groups for the purpose of determining the ion exchange capacity. It is presumed that the higher the ion exchange capacity of polymer (I), the more anionic groups there are in polymer (I), which leads to the formation of highly stable particles, and also leads to a higher number of particles per unit amount of water due to the high particle forming power, resulting in a higher polymerization rate.

[0619] The amount of polymer (I) added is preferably 0.01 to 20% by mass relative to 100% by mass of the aqueous medium. By setting the amount of polymer (I) added (abundance) in the polymerization within the above range, the polymerization reaction of the perfluoromonomer proceeds smoothly, and the perfluoroelastomer can be produced efficiently.

[0620] The amount of polymer (I) added is more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, particularly preferably 0.75% by mass or more, and most preferably 1.0% by mass or more, relative to 100% by mass of the aqueous medium, because this allows the polymerization reaction of the perfluoromonomer to proceed more smoothly.

[0621] Furthermore, if the amount of polymer (I) added is too large, an effect commensurate with the amount added will not be obtained, which is economically disadvantageous, and there is also the possibility that post-treatment after polymerization will become complicated. Therefore, the amount of polymer (I) added is more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 5% by mass or less, relative to 100% by mass of the aqueous medium.

[0622] The polymerization of the perfluoromonomer may be carried out in the presence of a polymerization initiator. The polymerization initiator is as described above. The amount of polymerization initiator added is preferably 0.0001 to 10% by mass, and more preferably 0.01 to 5% by mass, relative to 100% by mass of the perfluoromonomer. By setting the amount of polymerization initiator added (amount present) in the polymerization to be within the above range, the polymerization reaction of the perfluoromonomer proceeds smoothly, and the perfluoroelastomer can be produced efficiently. If the amount of polymerization initiator added is too small, a sufficient polymerization rate or a sufficient yield may not be obtained.

[0623] The polymerization of perfluoromonomer may be carried out in the presence of a pH adjuster. By carrying out the polymerization in the presence of a pH adjuster, it is possible to generate a sufficient number of perfluoroelastomer particles at a sufficient polymerization rate while further suppressing the adhesion of the perfluoroelastomer to the polymerization vessel. The pH adjuster may be added before or after the start of polymerization.

[0624] Examples of pH adjusters that can be used include ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, and ammonium gluconate.

[0625] Among the fluororubbers, the partially fluorinated rubber can be obtained by polymerizing a fluoromonomer in an aqueous medium in the presence of the polymer (I).

[0626] Fluoromonomers for obtaining partially fluorinated rubber include vinylidene fluoride (VdF), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), chlorotrifluoroethylene (CTFE), trifluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, vinyl fluoride, iodine-containing fluorinated vinyl ethers, and fluorinated vinyl ethers represented by the general formula: CHX １ =CX ２ Rf (wherein, X １ and X ２ and Rf are each a straight-chain or branched fluoroalkyl group having 1 to 12 carbon atoms.

[0627] In the method for producing the partially fluorinated rubber, it is preferable to polymerize at least vinylidene fluoride or tetrafluoroethylene as the fluoromonomer, and it is more preferable to polymerize vinylidene fluoride.

[0628] The amount of polymer (I) added is preferably 0.01 to 20% by mass relative to 100% by mass of the aqueous medium. By setting the amount of polymer (I) added (abundance) in the polymerization within the above range, the polymerization reaction of the fluoromonomer proceeds smoothly, and the partially fluorinated rubber can be produced efficiently. If the amount of polymer (I) added is too small, a sufficient polymerization rate or a sufficient yield may not be obtained.

[0629] The amount of polymer (I) added is more preferably 0.0001% by mass or more, still more preferably 0.0005% by mass or more, still more preferably 0.001% by mass or more, particularly preferably 0.005% by mass or more, and most preferably 0.01% by mass or more, relative to 100% by mass of the aqueous medium, because this allows the polymerization reaction of the fluoromonomer to proceed more smoothly.

[0630] Furthermore, if the amount of polymer (I) added is too large, an effect commensurate with the amount added will not be obtained, which is economically disadvantageous. Therefore, the amount of polymer (I) added is more preferably 2% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, relative to 100% by mass of the aqueous medium.

[0631] The polymerization of the fluoromonomer may be carried out in the presence of a polymerization initiator. The polymerization initiator is as described above. The amount of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target partially fluorinated rubber, and the reaction rate. The amount of the polymerization initiator is appropriately determined depending on the molecular weight of the target partially fluorinated rubber and the polymerization reaction rate, and is preferably 0.00001 to 10% by mass, and more preferably 0.0001 to 1% by mass, relative to 100% by mass of the total amount of monomers.

[0632] The fluororubber may be a partially fluorinated rubber or a perfluororubber.

[0633] Partially fluorinated rubber has a methylene group (-CH ２ It is preferable that the main chain contains -CH ２ The partially fluorinated rubber containing - includes -CH ２There is no particular limitation as long as it contains a chemical structure represented by -, and examples thereof include -CH ２ -CF ２ -, -CH ２ -CH(CH ３ ) -, -CH ２ -CH ２ -, -CH ２ -CF (CF ３ These can be introduced into the main chain of the partially fluorinated rubber by polymerizing, for example, vinylidene fluoride, propylene, ethylene, 2,3,3,3-tetrafluoropropylene, etc. The content of tetrafluoroethylene units in the partially fluorinated rubber (the content of polymerized units based on tetrafluoroethylene relative to the total polymerized units of the partially fluorinated rubber) may be less than 40 mol%.

[0634] Partially fluorinated rubbers include, for example, tetrafluoroethylene (TFE), vinylidene fluoride (VdF), and rubbers of the general formula: CF ２ =CF-Rf ａ (In the formula, Rf ａ Ha-CF ３ or -ORf ｂ (Rf ｂ It is preferable that the partially fluorinated rubber contains a monomer unit based on at least one monomer selected from the group consisting of perfluoroethylenically unsaturated compounds represented by the formula (I) (where I is a perfluoroalkyl group having 1 to 5 carbon atoms) (for example, hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), etc.). Of these, it is preferable that the partially fluorinated rubber contains a VdF unit or a TFE unit.

[0635] Examples of partially fluorinated rubbers include vinylidene fluoride (VdF)-based fluororubbers, tetrafluoroethylene (TFE) / propylene (Pr)-based fluororubbers, tetrafluoroethylene (TFE) / propylene / vinylidene fluoride (VdF)-based fluororubbers, ethylene / hexafluoropropylene (HFP)-based fluororubbers, ethylene / hexafluoropropylene (HFP) / vinylidene fluoride (VdF)-based fluororubbers, ethylene / hexafluoropropylene (HFP) / tetrafluoroethylene (TFE)-based fluororubbers, Et / TFE / PAVE-based fluororubbers, etc. Among these, at least one selected from the group consisting of vinylidene fluoride-based fluororubbers and tetrafluoroethylene / propylene-based fluororubbers is preferred.

[0636] The vinylidene fluoride-based fluororubber is preferably a copolymer consisting of 45 to 85 mol % of vinylidene fluoride and 55 to 15 mol % of at least one other monomer copolymerizable with vinylidene fluoride, and more preferably a copolymer consisting of 50 to 80 mol % of vinylidene fluoride and 50 to 20 mol % of at least one other monomer copolymerizable with vinylidene fluoride.

[0637] Examples of at least one other monomer copolymerizable with the vinylidene fluoride include tetrafluoroethylene [TFE], hexafluoropropylene [HFP], fluoroalkyl vinyl ether, chlorotrifluoroethylene [CTFE], trifluoroethylene, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, vinyl fluoride, and a compound represented by the general formula (100): CHX １０１ =CX １０２ Rf １０１ (In the formula, X １０１ and X １０２ is H on one side and F on the other side, and Rf １０１ is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), a fluoromonomer represented by the general formula (170): CH ２ =CH-(CF ２ ) ｎ -X１７１ (In the formula, X １７１ is H or F, and n is an integer of 3 to 10. Examples of the fluoromonomer include a fluoromonomer represented by the general formula (160), a monomer that provides a crosslinking site, and a non-fluorinated monomer such as ethylene, propylene, or an alkyl vinyl ether. These can be used alone or in any combination. Among these, it is preferable to use at least one selected from the group consisting of TFE, HFP, 2.3.3.3-tetrafluoropropene, a fluoroalkyl vinyl ether, and CTFE. As the fluoroalkyl vinyl ether, a fluoromonomer represented by the general formula (160) is preferred.

[0638] Specific examples of vinylidene fluoride-based fluororubbers include VdF / HFP-based rubbers, VdF / HFP / TFE-based rubbers, VdF / CTFE-based rubbers, VdF / CTFE / TFE-based rubbers, VdF / fluoromonomer-based rubbers represented by general formula (100), VdF / fluoromonomer-based rubbers represented by general formula (100) / TFE-based rubbers, VdF / perfluoro(methyl vinyl ether) [PMVE]-based rubbers, VdF / PMVE / TFE-based rubbers, VdF / PMVE / TFE / HFP-based rubbers, etc. Examples of VdF / fluoromonomer-based rubbers represented by general formula (100) include VdF / CH ２ =CFCF ３ The VdF / fluoromonomer represented by the general formula (100) / TFE rubber is preferably VdF / TFE / CH ２ =CFCF ３ Rubbers based on ethylenediaminetetraacetic acid are preferred.

[0639] The vinylidene fluoride-based fluororubber is preferably a VdF / HFP copolymer or a VdF / HFP / TFE copolymer, and more preferably a VdF / HFP / TFE copolymer having a composition of (32-85) / (10-34) / (0-40) (mol%). The VdF / HFP / TFE composition is more preferably (32-85) / (15-34) / (0-34) (mol%), and even more preferably (47-81) / (17-32) / (0-28) (mol%).

[0640] For example, in the above VdF / HFP copolymer, the VdF / HFP composition is preferably (45 to 85) / (15 to 55) (mol%), more preferably (50 to 83) / (17 to 50) (mol%), still more preferably (55 to 81) / (19 to 45) (mol%), and particularly preferably (60 to 80) / (20 to 40) (mol%).

[0641] The above VdF / CH ２ =CFCF ３ The rubber is a rubber containing 40 to 99.5 mol% of VdF and CH ２ =CFCF ３ It is preferable that the copolymer is composed of 0.5 to 60 mol % of VdF, 50 to 85 mol % of CH ２ =CFCF ３ A copolymer consisting of 20 to 50 mol % is more preferred.

[0642] The VdF / TFE / PMVE rubber is preferably a copolymer having a VdF / TFE / PMVE composition of (32 to 85) / (3 to 40) / (10 to 34) mol %, and more preferably a copolymer having a VdF / TFE / PMVE composition of (45 to 81) / (4 to 30) / (16 to 28) mol %.

[0643] The Et / TFE / PAVE fluororubber preferably has an Et / TFE / PAVE composition of (10-40) / (32-60) / (20-40) (mol%), more preferably (20-40) / (40-50) / (20-30) (mol%). PMVE is preferred as the PAVE.

[0644] The tetrafluoroethylene / propylene-based fluororubber is preferably a copolymer consisting of 45 to 70 mol % of tetrafluoroethylene, 55 to 30 mol % of propylene, and 0 to 5 mol % of a fluoromonomer that provides a crosslinking site.

[0645] The fluororubber may be a perfluororubber. The perfluororubber is preferably at least one selected from the group consisting of perfluororubbers containing TFE, such as TFE / fluoromonomer copolymers represented by general formula (160), (130) or (140) and TFE / fluoromonomer copolymers represented by general formula (160), (130) or (140) / monomer copolymers that provide crosslinking sites.

[0646] In the case of a TFE / PMVE copolymer, the composition is preferably 45-90 / 10-55 (mol %), more preferably 55-80 / 20-45, and even more preferably 55-70 / 30-45.

[0647] In the case of a copolymer of TFE / PMVE / monomer that provides a crosslinking site, the ratio is preferably 45 to 89.9 / 10 to 54.9 / 0.01 to 4 (mol%), more preferably 55 to 77.9 / 20 to 49.9 / 0.1 to 3.5, and even more preferably 55 to 69.8 / 30 to 44.8 / 0.2 to 3.

[0648] In the case of TFE / fluoromonomer copolymer having 4 to 12 carbon atoms and represented by general formula (160), (130) or (140), it is preferably 50 to 90 / 10 to 50 (mol%), more preferably 60 to 88 / 12 to 40, and even more preferably 65 to 85 / 15 to 35.

[0649] In the case of TFE / fluoromonomer having 4 to 12 carbon atoms represented by general formula (160), (130) or (140) / monomer copolymer that provides crosslinking moieties, it is preferably 50 to 89.9 / 10 to 49.9 / 0.01 to 4 (mol%), more preferably 60 to 87.9 / 12 to 39.9 / 0.1 to 3.5, and even more preferably 65 to 84.8 / 15 to 34.8 / 0.2 to 3.

[0650] If the composition is outside these ranges, the rubber elastic properties will be lost and the properties will tend to become more like those of a resin.

[0651] The perfluororubber is preferably at least one selected from the group consisting of TFE / fluoromonomer copolymer represented by general formula (140) / crosslinkable moiety-providing fluoromonomer, TFE / perfluorovinyl ether copolymer represented by general formula (140), TFE / fluoromonomer copolymer represented by general formula (160), and TFE / fluoromonomer copolymer represented by general formula (160) / crosslinkable moiety-providing monomer copolymer.

[0652] Examples of the perfluororubber include those described in International Publication No. 97 / 24381, Japanese Patent Publication No. 61-57324, Japanese Patent Publication No. 4-81608, and Japanese Patent Publication No. 5-13961.

[0653] The fluororubber has a glass transition temperature of preferably −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, from the viewpoint of excellent compression set at high temperatures. Also, from the viewpoint of good cold resistance, the glass transition temperature is preferably 5° C. or lower, more preferably 0° C. or lower, and even more preferably −3° C. or lower.

[0654] The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (DSC822e, manufactured by Mettler Toledo) by heating 10 mg of a sample at a rate of 10°C / min, and determining the maximum value of the differential curve of the DSC curve at the time of second-order transition as the glass transition temperature.

[0655] In terms of good heat resistance, the fluororubber preferably has a Mooney viscosity ML(1+20) at 170°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 150 or less, more preferably 120 or less, and even more preferably 110 or less.

[0656] In terms of good heat resistance, the fluororubber preferably has a Mooney viscosity ML(1+20) at 140°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 180 or less, more preferably 150 or less, and even more preferably 110 or less.

[0657] In terms of good heat resistance, the fluororubber preferably has a Mooney viscosity ML(1+10) at 100°C of 10 or more, more preferably 20 or more, and even more preferably 30 or more. In terms of good processability, the Mooney viscosity ML(1+10) is preferably 120 or less, more preferably 100 or less, and even more preferably 80 or less.

[0658] The Mooney viscosity can be measured using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES at 170°C, 140°C, or 100°C in accordance with JIS K6300.

[0659] The fluororubber obtained by the production method of the present disclosure may be in any form as long as it is obtained from the above polymerization, and may be an aqueous dispersion after polymerization, or may be used as a gum or crumb obtained by coagulating, drying, etc., the aqueous dispersion after polymerization by a conventionally known method. The polymer (I) used in the production method of the present disclosure can improve the stability of the aqueous dispersion, and is more preferably used in a polymerization method in which a poorly water-soluble substance, such as an initiator such as an organic peroxide or a chain transfer agent such as an iodine or bromine compound, is added during the polymerization, as described above.

[0660] The gum is a small granular mass made of fluororubber, and the crumb is an amorphous mass formed when the fluororubber cannot maintain its granular shape as a gum at room temperature and instead fuses together.

[0661] The above fluororubber can be processed into a fluororubber composition by adding a curing agent, a filler, etc.

[0662] Examples of the curing agent include polyols, polyamines, organic peroxides, organotin compounds, bis(aminophenol)tetraamines, and bis(thioaminophenols).

[0663] A fluororubber molded article can be obtained by molding the above-mentioned fluororubber. The molding method is not particularly limited, and includes known methods using the above-mentioned curing agents. Examples of molding methods include compression molding, casting, injection molding, extrusion molding, and rotocure molding, but are not limited to these.

[0664] When the fluororubber composition contains a curing agent (crosslinking agent), a crosslinked product can be obtained as a fluororubber molded article by crosslinking the fluororubber composition. Examples of crosslinking methods that can be used include steam crosslinking, heat crosslinking, and radiation crosslinking, with steam crosslinking and heat crosslinking being preferred. Specific crosslinking conditions, which are not limited to these, are typically a temperature range of 140 to 250°C, a crosslinking time of 1 minute to 24 hours, and can be determined appropriately depending on the types of crosslinking accelerator, crosslinking agent, acid acceptor, etc.

[0665] The fluororubber molded article is suitable for use as a seal, a gasket, a wire coating, a hose, a tube, a laminate, an accessory, etc., and is particularly suitable for use as a part for semiconductor manufacturing equipment, an automobile part, etc.

[0666] In the production method of the present disclosure, when the fluoropolymer is coagulated, washed, dried, or the like, wastewater and off-gas are generated. The polymer (I), decomposition products and by-products produced from the polymer (I), residual monomers, and the like may be recovered and purified from the wastewater generated by the coagulation or washing and / or the off-gas generated by drying, thereby allowing the polymer (I), decomposition products and by-products produced from the polymer (I), residual monomers, and the like to be reused. The method for the recovery and purification is not particularly limited, but can be carried out by known methods. For example, the method described in JP-A-2011-520020, the method described in U.S. Patent Application Publication No. 2007 / 15937, U.S. Patent Application Publication No. 2007 / 25902, and U.S. Patent Application Publication No. 2007 / 27251, and specifically the following method may be used.

[0667] Examples of a method for recovering the polymer (I), decomposition products and by-products of the polymer (I), residual monomers, etc., from the wastewater include a method of contacting the wastewater with adsorption particles such as ion exchange resin, activated carbon, silica gel, clay, zeolite, etc., to adsorb the polymer (I), etc., and then separating the wastewater from the adsorption particles. Incineration of the adsorption particles having the polymer (I), etc., can prevent the release of the polymer (I), etc., into the environment.

[0668] Alternatively, the polymer (I) or the like can be recovered by desorbing and eluting it from ion exchange resin particles that have adsorbed the polymer (I) or the like using a known method. For example, when the ion exchange resin particles are anion exchange resin particles, the polymer (I) or the like can be eluted by contacting a mineral acid with the anion exchange resin. Subsequently, when a water-soluble organic solvent is added to the resulting eluate, the mixture usually separates into two phases. The lower phase containing the polymer (I) or the like can be recovered and neutralized to recover the polymer (I) or the like. Examples of the water-soluble organic solvent include polar solvents such as alcohols, ketones, and ethers.

[0669] Other methods for recovering the polymer (I) and the like from the ion exchange resin particles include a method using an ammonium salt and a water-soluble organic solvent, and a method using an alcohol and, if desired, an acid. In the latter method, an ester derivative of the polymer (I) and the like is produced, which can be easily separated from the alcohol by distillation.

[0670] If the wastewater contains fluoropolymer particles or other solids, it is preferable to remove them before contacting the wastewater with the adsorbent particles. Methods for removing the fluoropolymer particles and other solids include a method in which they are precipitated by adding an aluminum salt or the like, and then separating the wastewater from the precipitate, and electrocoagulation. Mechanical methods, such as crossflow filtration, depth filtration, and precoat filtration, may also be used for removal. From the viewpoint of productivity, the concentration of the unaggregated fluoropolymer in the wastewater is preferably low, more preferably less than 0.4% by mass, and particularly preferably less than 0.3% by mass.

[0671] Examples of a method for recovering the polymer (I) and the like from the off-gas include a method in which a scrubber is used to contact the off-gas with deionized water, an aqueous alkali solution, an organic solvent such as a glycol ether solvent, or the like to obtain a scrubber solution containing the polymer (I) and the like. When a highly concentrated aqueous alkali solution is used as the aqueous alkali solution, the scrubber solution can be recovered in a state in which the polymer (I) and the like are phase-separated, facilitating the recovery and reuse of the polymer (I) and the like. Examples of the alkali compound include alkali metal hydroxides and quaternary ammonium salts.

[0672] The scrubber solution containing the polymer (I) and the like may be concentrated using a reverse osmosis membrane or the like. The concentrated scrubber solution usually contains fluoride ions, but by further adding alumina after concentration to remove the fluoride ions, it is possible to facilitate the reuse of the polymer (I) and the like. Alternatively, the scrubber solution may be brought into contact with adsorbent particles to adsorb the polymer (I) and the like, and the polymer (I) and the like may be recovered by the method described above.

[0673] The polymer (I) and the like recovered by any of the above methods can be reused in the production of a fluoropolymer.

[0674] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0675] <1> According to a first aspect of the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion, which comprises polymerizing a fluoromonomer in an aqueous medium in the presence of a polymer (I) comprising polymerized units (I) based on a monomer (I) represented by general formula (I) to obtain a polymer dispersion containing a fluoropolymer (excluding the polymer (I)), the polymer (I), and an aqueous medium, then mixing the polymer dispersion, a nonionic surfactant, and a fluorine-free water-soluble electrolyte to prepare a pre-concentration composition, and concentrating the pre-concentration composition to obtain an aqueous dispersion containing the fluoropolymer. CX １ X ３ =CX ２ R (-CZ １ Z ２ -A ０ ) ｍ (I) (wherein, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or greater.) <2> According to a second aspect of the present disclosure, there is provided the production method according to the first aspect, in which the surface tension of a 0.1% by mass aqueous solution of the fluorine-free water-soluble electrolyte is greater than 60 mN / m. <3> According to a third aspect of the present disclosure, there is provided the production method according to the first or second aspect, in which the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of monovalent to trivalent acids and salts thereof. <4> According to a fourth aspect of the present disclosure, there is provided the production method according to any of the first to third aspects, in which the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of carbonic acid, carbonates, sulfuric acid, sulfates, oxalic acid, oxalates, carboxylic acids represented by general formula (11) and salts thereof, and sulfonic acids represented by general formula (12) and salts thereof. General Formula (11): R １ -(COOH) ｎ (In the formula, R １ represents a monovalent to trivalent organic group having 1 to 10 carbon atoms, and n represents an integer of 1 to 3) General formula (12): R ２ - (SO ３ H) ｚ (In the formula, R ２(wherein π represents a monovalent to trivalent organic group having 1 to 10 carbon atoms, and z represents an integer of 1 to 3.) <5> According to a fifth aspect of the present disclosure, there is provided the production method according to the fourth aspect, in which the thermal decomposition temperatures of the carboxylic acid represented by general formula (11) and its salt, and the sulfonic acid represented by general formula (12) and its salt are less than 220°C. <6> According to a sixth aspect of the present disclosure, there is provided the production method according to any of the first to fifth aspects, in which the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of sulfuric acid, citric acid, succinic acid, carbonic acid, tartaric acid, maleic acid, malic acid, oxalic acid, malonic acid, and salts thereof. <7> According to a seventh aspect of the present disclosure, there is provided the production method according to any of the first to sixth aspects, in which the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of ammonium sulfate and ammonium citrate. <8> According to an eighth aspect of the present disclosure, there is provided the production method according to any one of the first to seventh aspects, wherein the content of the non-fluorine-containing water-soluble electrolyte in the pre-concentration composition is 0.01 mass % or more and 5.0 mass % or less relative to the fluoropolymer. <9> According to a ninth aspect of the present disclosure, there is provided the production method according to any one of the first to eighth aspects, wherein the nonionic surfactant is at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii). R ６ -O-A １ -H (i) (wherein, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain. ７ -C ６ H ４ -O-A ２ -H (ii) (wherein, R ７ is a linear or branched alkyl group having 4 to 12 carbon atoms, and A ２is a polyoxyalkylene chain.) <10> According to a tenth aspect of the present disclosure, there is provided the production method according to any one of the first to ninth aspects, in which the pre-concentration composition is concentrated by phase separation concentration. <11> According to an eleventh aspect of the present disclosure, there is provided the production method according to any one of the first to tenth aspects, in which the fluoromonomer is polymerized substantially in the absence of a fluorine-containing surfactant. <12> According to a twelfth aspect of the present disclosure, there is provided the production method according to any one of the first to eleventh aspects, in which the fluoropolymer is polytetrafluoroethylene. <13> According to a thirteenth aspect of the present disclosure, there is provided a production method according to any one of the first to twelfth aspects, wherein the polymer (I) is a polymer (1) containing polymerization units (1) based on a monomer represented by general formula (1), the nonionic surfactant is a nonionic surfactant represented by general formula (i), the content of the nonionic surfactant in the pre-concentration composition is 1.0 to 40 mass% relative to the fluoropolymer, the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of ammonium sulfate and ammonium citrate, the content of the fluorine-free water-soluble electrolyte in the pre-concentration composition is 0.2 mass% or more and 5.0 mass% or less relative to the fluoropolymer, the fluoropolymer is polytetrafluoroethylene, the content of the fluoropolymer in the pre-concentration composition is 8 to 50 mass%, and the pre-concentration composition is concentrated by phase separation concentration. CX ２ =CY(-CZ ２ -O-Rf-A) (1) (In the formula, X is the same or different and represents -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z is the same or different and represents -H, -F, an alkyl group or a fluoroalkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is -H, metal atom, -NR ７４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.) However, at least one of X, Y, and Z contains a fluorine atom.) R ６ -O-A １ -H (i) (wherein, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain.) <14> According to a fourteenth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion containing a polymer (I) containing polymerized units (I) based on a monomer (I) represented by general formula (I), a fluoropolymer, a nonionic surfactant, and an aqueous medium, wherein the content of polymer (I) is 500 ppm by mass or less relative to the aqueous fluoropolymer dispersion, the viscosity of the aqueous fluoropolymer dispersion at 25°C is 100 mPa·s or less, the anionic charge density of polymer particles of the fluoropolymer is 8.0 to 40 μeq / g, the content of the fluoropolymer is 50% by mass or more and 75% by mass or less relative to the aqueous fluoropolymer dispersion, and the content of the nonionic surfactant is 1.0% by mass or more and 12% by mass or less relative to the fluoropolymer. CX １ X ３ =CX ２ R (-CZ １ Z ２ -A ０ ) ｍ (I) (wherein, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.) <15> According to a fifteenth aspect of the present disclosure, there is provided the aqueous fluoropolymer dispersion according to th...

Claims

1. A fluoromonomer is polymerized in an aqueous medium in the presence of a polymer (I) containing polymerized units (I) based on a monomer (I) represented by general formula (I) to obtain a polymerization dispersion containing a fluoropolymer (excluding the polymer (I)), the polymer (I), and an aqueous medium, and then preparing a pre-concentration composition by mixing the polymer dispersion, a nonionic surfactant, and a fluorine-free water-soluble electrolyte; A method for producing an aqueous fluoropolymer dispersion, comprising concentrating the pre-concentration composition to obtain an aqueous dispersion containing the fluoropolymer. CX １ X ３ =CX ２ R(-CZ １ Z ２ -A ０ ) ｍ (I) (In the formula, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

2. The method according to claim 1 , wherein a surface tension of a 0.1% by mass aqueous solution of the fluorine-free water-soluble electrolyte is greater than 60 mN / m.

3. 3. The method according to claim 1, wherein the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of monovalent to trivalent acids and salts thereof.

4. 3. The method according to claim 1, wherein the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of carbonic acid, carbonates, sulfuric acid, sulfates, oxalic acid, oxalates, carboxylic acids represented by general formula (11) and salts thereof, and sulfonic acids represented by general formula (12) and salts thereof. General form (11): R １ - (COOH) ｎ (In the formula, R １ is a monovalent to trivalent organic group having 1 to 10 carbon atoms, and n is an integer of 1 to 3. General form (12): R ２ - (SO) ３ H) ｚ (In the formula, R ２ is a monovalent to trivalent organic group having 1 to 10 carbon atoms, and z is an integer of 1 to 3.

5. 5. The method according to claim 4, wherein the thermal decomposition temperatures of the carboxylic acid represented by the general formula (11) and its salt, and the sulfonic acid represented by the general formula (12) and its salt are lower than 220°C.

6. 3. The method according to claim 1, wherein the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of sulfuric acid, citric acid, succinic acid, carbonic acid, tartaric acid, maleic acid, malic acid, oxalic acid, malonic acid, and salts thereof.

7. 3. The method according to claim 1, wherein the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of ammonium sulfate and ammonium citrate.

8. 3. The method according to claim 1, wherein the content of the non-fluorine-containing water-soluble electrolyte in the pre-concentration composition is 0.01% by mass or more and 5.0% by mass or less relative to the fluoropolymer.

9. 3. The method according to claim 1, wherein the nonionic surfactant is at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii): R ６ -O-A １ -H (i) (In the formula, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain. ( ７  ６ H ４ - ２  ( ) ) (In the formula, R ７ is a linear or branched alkyl group having 4 to 12 carbon atoms, and A ２ is a polyoxyalkylene chain.

10. The method according to claim 1 or 2, wherein the pre-concentrated composition is concentrated by phase separation concentration.

11. 3. The production method according to claim 1, wherein the fluoromonomer is polymerized substantially in the absence of a fluorine-containing surfactant.

12. 3. The method according to claim 1, wherein the fluoropolymer is polytetrafluoroethylene.

13. The polymer (I) is a polymer (1) containing polymerization units (1) based on a monomer represented by general formula (1), The nonionic surfactant is a nonionic surfactant represented by general formula (i), the content of the nonionic surfactant in the pre-concentration composition is 1.0 to 40% by mass relative to the fluoropolymer; the fluorine-free water-soluble electrolyte is at least one selected from the group consisting of ammonium sulfate and ammonium citrate, the content of the non-fluorine-containing water-soluble electrolyte in the pre-concentration composition is 0.2% by mass or more and 5.0% by mass or less relative to the fluoropolymer, the fluoropolymer is polytetrafluoroethylene; the content of the fluoropolymer in the pre-concentration composition is 8 to 50% by mass, The method according to claim 1 or 2, wherein the pre-concentrated composition is concentrated by phase separation concentration. CX ２ =CY(-CZ ２ -O-Rf-A) (1) (In the formula, X's may be the same or different and each represent -H or F; Y's may be -H, -F, an alkyl group or a fluorine-containing alkyl group; Z's may be the same or different and each represent -H, -F, an alkyl group or a fluoroalkyl group; Rf's may be a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond; A's may be -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is -H, metal atom, -NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.) However, at least one of X, Y, and Z contains a fluorine atom.) R ６ -O-A １ -H (i) (In the formula, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain.

14. A polymer (I) containing polymerized units (I) based on a monomer (I) represented by general formula (I), fluoropolymers, a nonionic surfactant, and aqueous medium An aqueous fluoropolymer dispersion comprising: The content of the polymer (I) is 500 ppm by mass or less relative to the fluoropolymer aqueous dispersion, The viscosity of the aqueous fluoropolymer dispersion at 25°C is 100 mPa s or less, the anionic charge density of the polymer particles of the fluoropolymer is 8.0 to 40 μeq / g; The content of the fluoropolymer is 50% by mass or more and 75% by mass or less relative to the fluoropolymer aqueous dispersion, The content of the nonionic surfactant is 1.0% by mass or more and 12% by mass or less relative to the fluoropolymer. Aqueous fluoropolymer dispersion. CX １ X ３ =CX ２ R(-CZ １ Z ２ -A ０ ) ｍ (I) (In the formula, X １ and X ３ are each independently F, Cl, H or CF ３ and X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

15. The aqueous fluoropolymer dispersion according to claim 14, wherein the drop in pH from the initial pH of the aqueous fluoropolymer dispersion after 6 months is less than 1.0.