Aqueous fluoropolymer dispersion production method and aqueous fluoropolymer dispersion

Abstract

Provided is a method for producing an aqueous fluoropolymer dispersion having a reduced fluorine-containing surfactant content, said method comprising at least a step for heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant to prepare an aqueous dispersion (E) that contains a phase (E1), a phase (E2), and a phase (E3).

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] As a method for producing a fluoropolymer, a method of emulsion polymerization of a fluoromonomer is known. The aqueous dispersion of the fluoropolymer obtained by emulsion polymerization contains components other than the fluoropolymer, such as surfactants used in the emulsion polymerization. Various studies have been conducted on methods for reducing or removing such components other than the fluoropolymer.

[0003] Patent Document 1 discloses a method for reducing the fluoroether carboxylic acid or salt content of an aqueous fluoropolymer dispersion, in which the fluoroether carboxylic acid or salt is a compound represented by the formula: １ -O-L-COO － ]Y ＋ (In the formula, R １ is a partially or fully fluorinated linear, branched or cyclic aliphatic group which may contain an ether bond; L is a partially or fully fluorinated branched alkylene group which may contain an ether bond; Y ＋ is a hydrogen, ammonium, or alkali metal cation), adding a stabilizer to the fluoropolymer aqueous dispersion to form a stabilized fluoropolymer aqueous dispersion; heating the stabilized fluoropolymer aqueous dispersion to decarboxylate the fluoroether carboxylic acid or salt to form a fluoroether by-product; and removing at least a portion of the fluoroether by-product.

[0004] JP 2014-237842 A

[0005] An object of the present disclosure is to provide a production method capable of producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant.

[0006] According to the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, the method comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant to prepare an aqueous dispersion (E) containing: a phase (E1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E1), and the nonionic surfactant content is less than 2.00 mass% relative to the mass of phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E2), and the nonionic surfactant content is 1.00 mass% or more and 2.00 mass% or more relative to the mass of phase (E2); and a phase (E3) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of phase (E3), and the nonionic surfactant content is 1.00 mass% or more and 2.00 mass% or more relative to the mass of phase (E3).

[0007] According to the present disclosure, it is possible to provide a production method capable of producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant.

[0008] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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. Examples of the "organic group" include an alkyl group which may have one or more substituents, an alkenyl group which may have one or more substituents, an alkynyl group which may have one or more substituents, a cycloalkyl group which may have one or more substituents, a cycloalkenyl group which may have one or more substituents, a cycloalkadienyl group which may have one or more substituents, an aryl group which may have one or more substituents, an aralkyl group which may have one or more substituents, a non-aromatic heterocyclic group which may have one or more substituents, a heteroaryl group which may have one or more substituents, a cyano group, a formyl group, RaO-, RaCO-, and RaSO. ２ -, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO ２ -, and RaNRbSO ２ - (In these formulas, Ra is independently an alkyl group which may have one or more substituents, an alkenyl group which may have one or more substituents, an alkynyl group which may have one or more substituents, a cycloalkyl group which may have one or more substituents, a cycloalkenyl group which may have one or more substituents, a cycloalkadienyl group which may have one or more substituents, an aryl group which may have one or more substituents, an aralkyl group which may have one or more substituents, a non-aromatic heterocyclic group which may have one or more substituents, or a heteroaryl group which may have one or more substituents; and Rb is independently H or an alkyl group which may have one or more substituents). As the organic group, an alkyl group which may have one or more substituents is preferred.

[0017] In the present disclosure, the term "substituent" refers to a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamido group, an aromatic sulfonamido group, a heterocyclic sulfonamido group, an amino group, and an aliphatic amino group. groups, aromatic amino groups, heterocyclic amino groups, aliphatic oxycarbonylamino groups, aromatic oxycarbonylamino groups, heterocyclic oxycarbonylamino groups, aliphatic sulfinyl groups, aromatic sulfinyl groups, aliphatic thio groups, aromatic thio groups, hydroxy groups, cyano groups, sulfo groups, carboxy groups, aliphatic oxyamino groups, aromatic oxyamino groups, carbamoylamino groups, sulfamoylamino groups, halogen atoms, sulfamoylcarbamoyl groups, carbamoylsulfamoyl groups, dialiphatic oxyphosphinyl groups, and diaromatic oxyphosphinyl groups.

[0018] The aliphatic group may be saturated or unsaturated and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic group include alkyl groups having a total of 1 to 8, preferably 1 to 4, carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, and a carbamoylmethyl group.

[0019] The aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in total, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0020] The heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the heterocyclic group include 5- or 6-membered heterocycles having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0021] The acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the acyl group include acyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

[0022] The acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include acylamino groups having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and alkylcarbonylamino groups having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0023] The aliphatic oxycarbonyl group may be saturated or unsaturated and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a (t)-butoxycarbonyl group.

[0024] The carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 9 carbon atoms, preferably an unsubstituted carbamoyl group, or an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, or an N-phenylcarbamoyl group.

[0025] The aliphatic sulfonyl group may be saturated or unsaturated and may have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as a methanesulfonyl group.

[0026] The aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms, such as a benzenesulfonyl group.

[0027] The amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.

[0028] The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include acylamino groups having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and more preferably alkylcarbonylamino groups having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0029] The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, or a 2-pyridinesulfonamide group.

[0030] The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the sulfamoyl group include a sulfamoyl group, an alkylsulfamoyl group having 1 to 9 carbon atoms in total, a dialkylsulfamoyl group having 2 to 10 carbon atoms in total, an arylsulfamoyl group having 7 to 13 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 12 carbon atoms in total, more preferably a sulfamoyl group, an alkylsulfamoyl group having 1 to 7 carbon atoms in total, a dialkylsulfamoyl group having 3 to 6 carbon atoms in total, an arylsulfamoyl group having 6 to 11 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 10 carbon atoms in total, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[0031] The aliphatic oxy group may be saturated or unsaturated and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. Examples of the aliphatic oxy group include alkoxy groups having a total of 1 to 8, preferably 1 to 6, carbon atoms, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, and a methoxyethoxy group.

[0032] The aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group fused with the aryl group, or an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0033] The aliphatic thio group may be saturated or unsaturated and includes alkylthio groups having a total of 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, and a t-butylthio group.

[0034] The carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 9 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 10 carbon atoms, an arylcarbamoylamino group having a total of 7 to 13 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 12 carbon atoms, preferably a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 7 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 6 carbon atoms, an arylcarbamoylamino group having a total of 7 to 11 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 10 carbon atoms, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0035] 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.).

[0036] 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.).

[0037] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0038] The present disclosure relates to a method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, the method comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant to prepare an aqueous dispersion (E) containing: a phase (E1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E1), and the nonionic surfactant content is less than 2.00 mass% relative to the mass of phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E2), and the nonionic surfactant content is 2.00 mass% or more relative to the mass of phase (E2); and a phase (E3) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of phase (E3), and the nonionic surfactant content is 2.00 mass% or more relative to the mass of phase (E3). (Hereinafter, this method may be referred to as a first production method.)

[0039] The present disclosure also relates to an aqueous fluoropolymer dispersion (hereinafter sometimes referred to as a first aqueous fluoropolymer dispersion) which contains a fluoropolymer and an anionic fluorine-containing surfactant, and in which the content of the anionic fluorine-containing surfactant is more than 0 ppb by mass and less than 100 ppb by mass, relative to the fluoropolymer.

[0040] Also, a method for producing an aqueous fluoropolymer dispersion having a reduced content of a polymer compound (I) having an ionic group comprises at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and the polymer compound (I) having an ionic group to prepare an aqueous dispersion (E) containing: a phase (E1) in which the content of the fluoropolymer is less than 1.00 mass% relative to the mass of the phase (E1), and the content of the nonionic surfactant is less than 2.00 mass% relative to the mass of the phase (E1); a phase (E2) in which the content of the fluoropolymer is less than 1.00 mass% relative to the mass of the phase (E2), and the content of the nonionic surfactant is 2.00 mass% or more relative to the mass of the phase (E2); and a phase (E3) in which the content of the fluoropolymer is 1.00 mass% or more relative to the mass of the phase (E3), and the content of the nonionic surfactant is 2.00 mass% or more relative to the mass of the phase (E3). The present invention relates to a method for producing an aqueous fluoropolymer dispersion (hereinafter, sometimes referred to as a second production method).

[0041] The present disclosure also relates to an aqueous fluoropolymer dispersion (hereinafter sometimes referred to as a second aqueous fluoropolymer dispersion) which contains a fluoropolymer and a polymeric compound (I) having an ionic group, is substantially free of anionic fluorine-containing surfactant, the content of the polymeric compound (I) having an ionic group is more than 0 ppm by mass and not more than 500 ppm by mass, based on the fluoropolymer, and the proportion of hydrogen atoms bonded to carbon atoms of the polymeric compound (I) having an ionic group that have been substituted with fluorine atoms is 50% or more.

[0042] In this disclosure, both the first production method and the second production method may be simply referred to as "production methods". Also, in this disclosure, both the first fluoropolymer aqueous dispersion and the second fluoropolymer aqueous dispersion may be simply referred to as "fluoropolymer aqueous dispersion".

[0043] 1. Method for producing aqueous fluoropolymer dispersion The first aqueous fluoropolymer dispersion can be produced by polymerizing a fluoromonomer in an aqueous medium using a fluorine-containing surfactant. The first production method of the present disclosure can remove the fluorine-containing surfactant at a removal rate that could not be achieved by conventional production methods, and can produce an aqueous fluoropolymer dispersion with a reduced fluorine-containing surfactant content.

[0044] The first production method of the present disclosure is a method for producing an aqueous fluoropolymer dispersion with a reduced fluorine-containing surfactant content, and is characterized in that an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant is heated to separate the aqueous dispersion into at least three phases. After separation into three phases, the phase containing the fluoropolymer in a large amount is recovered, or an additional step of separating the dispersion into at least two phases is carried out and the phase containing the fluoropolymer in a large amount is recovered, thereby obtaining an aqueous fluoropolymer dispersion with a reduced fluorine-containing surfactant content.

[0045] The second aqueous fluoropolymer dispersion can be produced by polymerizing a fluoromonomer in an aqueous medium using a polymer compound (I) having an ionic group. The second production method of the present disclosure can remove the polymer compound (I) having an ionic group at a removal rate that could not be achieved by conventional production methods, and can produce an aqueous fluoropolymer dispersion with a reduced content of the polymer compound (I) having an ionic group.

[0046] The second production method of the present disclosure is a method for producing an aqueous fluoropolymer dispersion having a reduced content of the polymer compound (I) having an ionic group, and is characterized in that an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and the polymer compound (I) having an ionic group is heated to separate the aqueous dispersion into at least three phases. After separation into three phases, the phase containing the fluoropolymer in a large amount can be recovered, or an additional step of separating the dispersion into at least two phases can be performed to recover the phase containing the fluoropolymer in a large amount, thereby obtaining an aqueous fluoropolymer dispersion having a reduced content of the polymer compound (I) having an ionic group. Furthermore, when the aqueous dispersion contains a fluorine-containing surfactant in addition to the polymer compound (I) having an ionic group, it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of the polymer compound (I) having an ionic group and a reduced content of the fluorine-containing surfactant.

[0047] Each step and the materials used in each step will be described in detail below.

[0048] (Heating of aqueous dispersion) In the first production method of the present disclosure, an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant is heated to prepare an aqueous dispersion (E) containing: a phase (E1) in which the fluoropolymer content is less than 1.00% by mass, based on the mass of phase (E1), and the nonionic surfactant content is less than 2.00% by mass, based on the mass of phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00% by mass, based on the mass of phase (E2), and the nonionic surfactant content is 2.00% by mass or more, based on the mass of phase (E2); and a phase (E3) in which the fluoropolymer content is 1.00% by mass or more, based on the mass of phase (E3), and the nonionic surfactant content is 2.00% by mass or more, based on the mass of phase (E3).

[0049] In the first production method, by heating the aqueous dispersion in this way, the aqueous dispersion is separated into at least three phases: a phase (E1) containing small amounts of fluoropolymer and nonionic surfactant, a phase (E2) containing a relatively large amount of nonionic surfactant, and a phase (E3) containing a relatively large amount of fluoropolymer, thereby making it possible to produce an aqueous fluoropolymer dispersion with a reduced content of fluorine-containing surfactant.

[0050] In the first production method, when a fluorosurfactant having a carboxylic acid is used, the formation of a phase (E2) consisting mainly of the nonionic surfactant promotes the decarboxylation reaction of the fluorosurfactant. Nonionic surfactants usually have a distribution in the number of oxyethylene units, which are the hydrophilic moieties, and a distribution in their hydrophilicity. By heating to a temperature higher than the cloud point of the nonionic surfactant, the nonionic surfactant with a small number of oxyethylene units and low hydrophilicity separates from the aqueous phase (E1) and forms phase (E2) (this can be confirmed by NMR). The decarboxylation reaction of the fluorosurfactant hardly occurs in the aqueous phase (E1) or phase (E3), but is more likely to occur in the phase (E2) formed by heating. This allows the content of the fluorosurfactant to be reduced.

[0051] In the second production method of the present disclosure, an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a polymer compound (I) having an ionic group is heated to prepare an aqueous dispersion (E) containing: a phase (E1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of the phase (E1) and the nonionic surfactant content is less than 2.00 mass% relative to the mass of the phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of the phase (E2) and the nonionic surfactant content is 2.00 mass% or more relative to the mass of the phase (E2); and a phase (E3) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of the phase (E3) and the nonionic surfactant content is 2.00 mass% or more relative to the mass of the phase (E3).

[0052] In the second production method, by heating the aqueous dispersion in this way, the aqueous dispersion is separated into at least three phases: a phase (E1) containing a small amount of fluoropolymer and nonionic surfactant, a phase (E2) containing a relatively large amount of nonionic surfactant, and a phase (E3) containing a relatively large amount of fluoropolymer, thereby making it possible to produce an aqueous fluoropolymer dispersion having a reduced content of the polymer compound (I) having an ionic group.Furthermore, when the aqueous dispersion contains a fluorine-containing surfactant in addition to the polymer compound (I) having an ionic group, it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of the polymer compound (I) having an ionic group and a reduced content of the fluorine-containing surfactant.

[0053] The composition of each of the phases (E1) to (E3) in the aqueous dispersion (E) can vary depending on the composition of the aqueous dispersion subjected to heating and the heating conditions.

[0054] In one embodiment, an aqueous dispersion (E) is prepared, which comprises: a phase (E1) having a fluoropolymer content of less than 1.00% by mass relative to the mass of the phase (E1) and a nonionic surfactant content of less than 2.00% by mass relative to the mass of the phase (E1); a phase (E2) having a fluoropolymer content of less than 1.00% by mass relative to the mass of the phase (E2) and a nonionic surfactant content of 20.00% by mass or more relative to the mass of the phase (E2); and a phase (E3) having a fluoropolymer content of 30.00% by mass or more relative to the mass of the phase (E3) and a nonionic surfactant content of 2.00% by mass or more relative to the mass of the phase (E3).

[0055] In another embodiment, an aqueous dispersion containing: a phase (E1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (E1), and a nonionic surfactant content of 0.01% by mass or more and less than 2.00% by mass, based on the mass of the phase (E1); a phase (E2) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (E2), and a nonionic surfactant content of 20.00 to 50.00% by mass, based on the mass of the phase (E2); and a phase (E3) having a fluoropolymer content of 30.00 to 75.00% by mass, based on the mass of the phase (E3), and a nonionic surfactant content of 2.00 to 5.00% by mass, based on the mass of the phase (E3), is prepared.

[0056] Furthermore, in another embodiment, an aqueous dispersion containing: a phase (E1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (E1), and a nonionic surfactant content of 0.01 to 1.50% by mass, based on the mass of the phase (E1); a phase (E2) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (E2), and a nonionic surfactant content of 20.00 to 40.00% by mass, based on the mass of the phase (E2); and a phase (E3) having a fluoropolymer content of 50.00 to 75.00% by mass, based on the mass of the phase (E3), and a nonionic surfactant content of 2.00 to 5.00% by mass, based on the mass of the phase (E3), is prepared.

[0057] In one embodiment, an aqueous dispersion containing the following is prepared: a phase (E1) in which the fluoropolymer content is less than 1.00% by mass, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is less than 2.00% by mass, based on the mass of the aqueous dispersion (E); a phase (E2) in which the fluoropolymer content is less than 1.00% by mass, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is 1.00% by mass or more, based on the mass of the aqueous dispersion (E); and a phase (E3) in which the fluoropolymer content is 10.0% by mass or more, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is 0.50% by mass or more, based on the mass of the aqueous dispersion (E).

[0058] In another embodiment, an aqueous dispersion containing: a phase (E1) in which the fluoropolymer content is 0.00% by mass or more and less than 1.00% by mass, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is 0.01% by mass or more and less than 2.00% by mass, based on the mass of the aqueous dispersion (E); a phase (E2) in which the fluoropolymer content is 0.00% by mass or more and less than 1.00% by mass, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is 1.00 to 10.0% by mass, based on the mass of the aqueous dispersion (E); and a phase (E3) in which the fluoropolymer content is 10.0 to 50.0% by mass, based on the mass of the aqueous dispersion (E), and the nonionic surfactant content is 0.50 to 2.00% by mass, based on the mass of the aqueous dispersion (E), is prepared.

[0059] In the present disclosure, the content of fluoropolymer in the aqueous dispersion can be determined by measuring the solids concentration of the aqueous dispersion and the content of nonionic surfactant in the aqueous dispersion, and subtracting the content of nonionic surfactant from the solids concentration of the aqueous dispersion. The solids concentration of the aqueous dispersion is a value calculated from the heating residue (Zg) obtained by heating about 1 g (Xg) of a sample at 110°C for 30 minutes and then at 300°C for 30 minutes according to the formula: P = Z / X × 100 (mass%).

[0060] In the present disclosure, the content of nonionic surfactant relative to the fluoropolymer in the aqueous dispersion is a value calculated according to the formula: N = [(Y-Z) / Z] x 100 (mass%), using 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.

[0061] In the present disclosure, the content of the fluorine-containing surfactant in the aqueous dispersion can be quantified by known methods. For example, it can be quantified by LC / MS analysis. First, methanol is added to the fluoropolymer aqueous dispersion to perform extraction, and the resulting extract is analyzed by LC / MS. To further improve the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. The resulting extract is concentrated using an appropriate nitrogen purge, and the fluorine-containing surfactant in the concentrated extract is measured by LC / MS. 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. Thereafter, aqueous solutions containing five or more levels of the identified fluorine-containing surfactant are prepared, and LC / MS analysis is performed on each aqueous solution. The relationship between the content and the area relative to the content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing surfactant in the extract can be converted to the fluorine-containing surfactant content. Note that the resulting extract can be concentrated by nitrogen purging, which lowers the lower limit of quantitation of the measurement method.

[0062] In the present disclosure, the content of the polymer compound (I) having an ionic group in the aqueous dispersion can be quantified by a known method. For example, it can be quantified by LC / MS analysis. It can be determined by solid-state NMR measurement or melt NMR measurement. When the polymer compound (I) contains a carbonyl group, it can also be determined by a Fourier transform infrared spectrometer. Further, WO 2014 / 099453, WO 2010 / 075497, WO 2010 / 075496, WO 2011 / 008381, WO 2009 / 055521, WO 1987 / 007619, JP 61-293476 A, WO 2010 / 075494, WO 2010 / 075359, WO 2012 / 082454, WO 2006 / 119224, WO 2013 / 085864, Methods for measuring the content of each polymer are described in JP-A-2012 / 082707, JP-A-2012 / 082703, JP-A-2012 / 082451, JP-A-2006 / 135825, JP-A-2004 / 067588, JP-A-2009 / 068528, JP-A-2004-075978, JP-A-2001-226436, JP-A-1992 / 017635, JP-A-2014 / 069165, JP-A-11-181009, etc. As a method for measuring the content of polymer compound (I), the methods for measuring each polymer described therein can be used.

[0063] In the production method according to the present disclosure, the heating means for heating the aqueous dispersion is not particularly limited. For example, the aqueous dispersion may be heated by placing a container containing the aqueous dispersion in a thermostatic bath, or the aqueous dispersion may be heated by placing the aqueous dispersion in a container equipped with a heater.

[0064] In the production method of the present disclosure, the pressure under which the aqueous dispersion is heated is not particularly limited and may be atmospheric pressure. For example, when the temperature of the aqueous dispersion is relatively high and it is necessary to suppress boiling of the aqueous dispersion, the pressure under which the aqueous dispersion is heated may be a pressure exceeding atmospheric pressure.

[0065] When the aqueous dispersion is heated to separate into phases (E1) to (E3), it is preferable to leave the aqueous dispersion at rest without stirring, or to weakly stir the aqueous dispersion to the extent that it separates into at least three or more phases.

[0066] The content of the fluoropolymer in the aqueous dispersion to be heated to prepare the aqueous dispersion (E) is preferably 10.0 to 50.0 mass%, more preferably 15.0 mass% or more, even more preferably 20.0 mass% or more, more preferably 45.0 mass% or less, even more preferably 40.0 mass% or less, and particularly preferably 35.0 mass% or less, based on the mass of the aqueous dispersion.

[0067] The content of the nonionic surfactant in the aqueous dispersion to be heated to prepare the aqueous dispersion (E) is preferably 2.00 to 10.0 mass%, more preferably 2.20 mass% or more, even more preferably 2.50 mass% or more, still more preferably 2.70 mass% or more, particularly preferably 3.00 mass% or more, more preferably 9.0 mass% or less, even more preferably 8.0 mass% or less, still more preferably 7.0 mass% or less, particularly preferably 6.0 mass% or less, and most preferably 5.0 mass% or less, relative to the mass of the aqueous dispersion.

[0068] In the first production method, the content of the fluorine-containing surfactant in the aqueous dispersion to be heated to prepare the aqueous dispersion (E) is preferably 0 to 6,000 ppm by mass, more preferably 5,000 ppm by mass or less, even more preferably 4,500 ppm by mass or less, still more preferably 4,000 ppm by mass or less, particularly preferably 3,500 ppm by mass or less, and most preferably 3,000 ppm by mass or less, based on the mass of the aqueous dispersion. By heating an aqueous dispersion having a fluorine-containing surfactant content within the above range, an aqueous dispersion (E) separated into at least three phases can be easily prepared. If the content of the fluorine-containing surfactant in the aqueous dispersion is too high, even if the aqueous dispersion is heated at an appropriate temperature, it may separate into two phases and not be possible to separate into three or more phases. The content of the fluorine-containing surfactant in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the fluorine-containing surfactant from an aqueous dispersion, such as a method of subjecting the aqueous dispersion to ion exchange treatment. In the first production method, the content of the fluorine-containing surfactant in the aqueous dispersion to be heated to prepare the aqueous dispersion (E) may be 100 ppb by mass or more, 200 ppb by mass or more, 300 ppb by mass or more, 400 ppb by mass or more, or 500 ppb by mass or more, relative to the mass of the aqueous dispersion.

[0069] In the second production method, the content of the polymeric compound (I) having an ionic group in the aqueous dispersion to be heated to prepare the aqueous dispersion (E) is preferably 0 to 6,000 ppm by mass, more preferably 5,000 ppm by mass or less, even more preferably 4,500 ppm by mass or less, still more preferably 4,000 ppm by mass or less, particularly preferably 3,500 ppm by mass or less, and most preferably 3,000 ppm by mass or less, based on the mass of the aqueous dispersion. By heating an aqueous dispersion having a content of the polymeric compound (I) having an ionic group within the above range, an aqueous dispersion (E) separated into at least three phases can be easily prepared. If the content of the polymeric compound (I) having an ionic group in the aqueous dispersion is too high, the aqueous dispersion may separate into two phases, and it may not be possible to separate the aqueous dispersion into three or more phases, even if the aqueous dispersion is heated at an appropriate temperature. The content of the polymer compound (I) having an ionic group in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the polymer compound (I) having an ionic group from the aqueous dispersion, such as a method of adjusting the amount of the polymer compound (I) used in the polymerization for preparing the aqueous dispersion. In the second production method, the content of the polymer compound (I) having an ionic group in the aqueous dispersion to be heated for preparing the aqueous dispersion (E) may be 10 ppm by mass or more, 100 ppm by mass or more, more than 500 ppm by mass, or 1000 ppm by mass or more, relative to the mass of the aqueous dispersion.

[0070] The aqueous dispersion and aqueous dispersion (E) to be heated usually contain an aqueous medium. Furthermore, the aqueous dispersions (A), (B), (C), (D), (F), and (G) described below also usually contain an aqueous medium. 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 ether or a ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower. The aqueous medium is preferably an aqueous medium containing only water, or an aqueous medium containing only water and a fluorine-free organic solvent, and more preferably an aqueous medium containing only water.

[0071] In the manufacturing method of the present disclosure, an aqueous dispersion is separated into at least three phases. Patent Document 1 describes that when an aqueous dispersion is heated to a temperature above the cloud point of a nonionic surfactant and then cooled to the cloud point range of the nonionic surfactant to cause thermal phase separation, thermal phase separation (concentrated phase / supernatant phase) occurs. Thus, conventional heating methods can only separate into two phases. However, it has been discovered that when an aqueous dispersion is heated under special conditions, it separates into three phases, and that by undergoing a three-phase separation process and recovering the phase containing a large amount of fluoropolymer, an aqueous fluoropolymer dispersion with a reduced content of fluorine-containing surfactant or polymer compound (I) having an ionic group can be produced.

[0072] Examples of methods for producing an aqueous fluoropolymer dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant or a polymer compound (I) having an ionic group by separating the aqueous dispersion into three phases and reducing the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group include: (1) a method of heating the aqueous dispersion to a temperature close to the cloud point of the nonionic surfactant, and then further heating the aqueous dispersion to a temperature sufficiently higher than the cloud point of the nonionic surfactant in the aqueous dispersion; and (2) a method of heating the aqueous dispersion to a temperature sufficiently higher than the cloud point of the nonionic surfactant in the aqueous dispersion, and then adjusting the temperature of the aqueous dispersion to a temperature close to the cloud point of the nonionic surfactant.

[0073] Next, the above methods (1) and (2) will be explained in more detail.

[0074] (Regarding method (1)) In one embodiment, an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant, and a fluorinated surfactant or a polymer compound (I) having an ionic group is heated to a first temperature range that is less than a temperature 10°C higher than the cloud point of the nonionic surfactant and is 35°C or higher, and the temperature of the heated aqueous dispersion (C) is maintained within the first temperature range for 5 minutes or longer, thereby preparing an aqueous dispersion (D) containing: a phase (D1) having a fluoropolymer content of less than 1.00% by mass relative to the mass of phase (D1) and a nonionic surfactant content of 5.00% by mass or more relative to the mass of phase (D1); and a phase (D2) having a fluoropolymer content of 1.00% by mass or more relative to the mass of phase (D2) and a nonionic surfactant content of less than 5.00% by mass relative to the mass of phase (D2); The aqueous dispersion (D) is heated to a second temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and the temperature of the heated aqueous dispersion (D) is maintained within the second temperature range for 5 minutes or longer, thereby preparing an aqueous dispersion (E) containing phases (E1) to (E3).

[0075] In this way, aqueous dispersion (C) is heated at a relatively low temperature to prepare aqueous dispersion (D) containing phases (D1) and (D2), and then aqueous dispersion (D) is heated at a relatively high temperature to prepare aqueous dispersion (E) containing phases (E1) to (E3).

[0076] Furthermore, by recovering phase (E3) from aqueous dispersion (E) containing phases (E1) to (E3), it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant or polymeric compound (I) having an ionic group.

[0077] The first temperature range is less than 10° C. higher than the cloud point of the nonionic surfactant, and is equal to or higher than 35° C. The upper limit of the first temperature range is preferably 5° C. higher than the cloud point of the nonionic surfactant, more preferably the cloud point of the nonionic surfactant. The lower limit of the first temperature range is preferably 40° C., more preferably 45° C., and even more preferably 50° C.

[0078] The time for which the aqueous dispersion (C) is maintained in the first temperature range is 5 minutes or more, preferably 15 minutes or more, more preferably 30 minutes or more, and even more preferably 45 minutes or more. The upper limit is not particularly limited, but may be 100 hours or less, or may be 50 hours or less.

[0079] The second temperature range is at least 10° C. higher than the cloud point of the nonionic surfactant. The lower limit of the second temperature range is preferably 12° C. higher than the cloud point of the nonionic surfactant. The upper limit of the second temperature range is preferably 50° C. higher, more preferably 30° C. higher than the cloud point of the nonionic surfactant.

[0080] The time for maintaining the aqueous dispersion (C) in the second temperature range is 5 minutes or more, preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more. The upper limit is not particularly limited, but may be 10 hours or less.

[0081] When the aqueous dispersion is heated to separate into phase (D1) and phase (D2), it is preferable to leave the aqueous dispersion at rest without stirring, or to weakly stir the aqueous dispersion to the extent that it separates into at least two or more phases.

[0082] The compositions of the phases (D1) and (D2) in the aqueous dispersion (D) can vary depending on the composition of the aqueous dispersion (C) subjected to heating and the heating conditions.

[0083] In one embodiment, an aqueous dispersion (D) containing a phase (D1) having a fluoropolymer content of less than 1.00% by mass relative to the mass of the phase (D1) and a nonionic surfactant content of 5.00% by mass or more relative to the mass of the phase (D1) and a phase (D2) having a fluoropolymer content of 50.00% by mass or more relative to the mass of the phase (D2) and a nonionic surfactant content of less than 5.00% by mass relative to the mass of the phase (D2) is prepared.

[0084] In another embodiment, an aqueous dispersion containing: a phase (D1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (D1), and a nonionic surfactant content of 5.00 to 20.00% by mass, based on the mass of the phase (D1); and a phase (D2) having a fluoropolymer content of 50.00 to 75.0% by mass, based on the mass of the phase (D2), and a nonionic surfactant content of 0.01% by mass or more and less than 5.00% by mass, based on the mass of the phase (D2), is prepared as the aqueous dispersion (D).

[0085] In one embodiment, an aqueous dispersion containing: a phase (D1) having a fluoropolymer content of less than 1.00% by mass, based on the mass of the aqueous dispersion (D), and a nonionic surfactant content of 3.00% by mass or more, based on the mass of the aqueous dispersion (D); and a phase (D2) having a fluoropolymer content of 10.0% by mass or more, based on the mass of the aqueous dispersion (D), and a nonionic surfactant content of less than 3.00% by mass, based on the mass of the aqueous dispersion (D), is prepared as the aqueous dispersion (D).

[0086] In another embodiment, an aqueous dispersion containing: a phase (D1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the aqueous dispersion (D), and a nonionic surfactant content of 3.00 to 10.0% by mass, based on the mass of the aqueous dispersion (D); and a phase (D2) having a fluoropolymer content of 10.0 to 50.0% by mass, based on the mass of the aqueous dispersion (D), and a nonionic surfactant content of 0.01% by mass or more and less than 3.00% by mass, based on the mass of the aqueous dispersion (D), is prepared as the aqueous dispersion (D).

[0087] After preparing the aqueous dispersion (E) containing the phases (E1) to (E3), the phase (E3) may be recovered and a nonionic surfactant may be added to the phase (E3). By adding the nonionic surfactant to the phase (E3), an aqueous fluoropolymer dispersion having excellent dispersion stability can be obtained, despite the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group being reduced.

[0088] It is preferable to prepare an aqueous dispersion having a nonionic surfactant content of 4.0 to 12.0% by mass relative to the fluoropolymer by adding a nonionic surfactant to the recovered phase (E3). The content of the nonionic surfactant in the aqueous dispersion is more preferably 4.5% by mass or more, even more preferably 5.0% by mass or more, more preferably 10% by mass or less, even more preferably 8.0% by mass or less, and still more preferably 7.0% by mass or less.

[0089] After the phase (E3) is recovered, a viscosity adjuster, a pH adjuster, a preservative, a water-soluble polymer, etc. may be added to the phase (E3).

[0090] (Regarding method (2)) In one embodiment, an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant or a polymer compound (I) having an ionic group is heated to a third temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and the temperature of the heated aqueous dispersion (C) is maintained in the third temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (E) containing phases (E1) to (E3); next, the aqueous dispersion (E) is stirred until the boundaries between the phases disappear, thereby preparing an aqueous dispersion (F); and the temperature of the aqueous dispersion (F) is adjusted to a fourth temperature range that is lower than a temperature that is 10°C higher than the cloud point of the nonionic surfactant and is at least 35°C, and the temperature of the aqueous dispersion (F) is maintained in the fourth temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (F) containing phases (E1) to (E3). An aqueous dispersion (G) containing a phase (G2) is prepared, the phase (G2) having a fluoropolymer content of 1.00% by mass or more and a nonionic surfactant content of less than 5.00% by mass, based on the mass of the phase (G2).

[0091] In this way, aqueous dispersion (C) is heated at a relatively high temperature to prepare aqueous dispersion (E) containing phases (E1) to (E3), and then aqueous dispersion (E) is stirred until the boundaries between the phases disappear, and then aqueous dispersion (E) is maintained at a relatively low temperature, whereby aqueous dispersion (G) containing phases (G1) to (G2) can be prepared.

[0092] Furthermore, by recovering phase (G2) from aqueous dispersion (G) containing phases (G1) to (G2), it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant or polymeric compound (I) having an ionic group.

[0093] The third temperature range is at least 10° C. higher than the cloud point of the nonionic surfactant. The lower limit of the third temperature range is 12° C. higher than the cloud point of the nonionic surfactant. The upper limit of the third temperature range is preferably 50° C. higher than the cloud point of the nonionic surfactant, more preferably 30° C. higher than the cloud point of the nonionic surfactant.

[0094] The time for which the aqueous dispersion (C) is maintained in the third temperature range is 5 minutes or more, preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more. The upper limit is not particularly limited, but may be 10 hours or less.

[0095] The fourth temperature range is less than a temperature 10° C. higher than the cloud point of the nonionic surfactant, and is equal to or higher than 35° C. The upper limit of the fourth temperature range is preferably a temperature 5° C. higher than the cloud point of the nonionic surfactant, more preferably the cloud point of the nonionic surfactant. The lower limit of the fourth temperature range is preferably 40° C., more preferably 45° C., and even more preferably 50° C.

[0096] The time for which the aqueous dispersion (C) is maintained in the fourth temperature range is 5 minutes or more, preferably 15 minutes or more, more preferably 30 minutes or more, and even more preferably 45 minutes or more, and the upper limit is not particularly limited, but may be 100 hours or less, or may be 50 hours or less.

[0097] After preparing the aqueous dispersion (E), the aqueous dispersion (E) is stirred until the boundaries between the phases disappear. The stirring of the aqueous dispersion (E) is carried out until the boundaries between phases (E1) to (E3) in the aqueous dispersion (E) disappear. Stirring may be continued even after the boundaries between the phases disappear. The stirring is carried out to the extent that a shear force sufficient to cause the boundaries between the phases to disappear is applied to the aqueous dispersion, but it is necessary to stir to the extent that the fluoropolymer in the aqueous dispersion does not aggregate. The stirring of the aqueous dispersion can be carried out, for example, using a stirring blade provided in a tank containing the aqueous dispersion.

[0098] The aqueous dispersion (E) is stirred until the boundaries between the phases disappear, and then the aqueous dispersion (E) is maintained at a relatively low temperature. When the aqueous dispersion is maintained at a relatively low temperature to separate into phases (G1) and (G2), it is preferable to leave the aqueous dispersion at rest without stirring, or to weakly stir the aqueous dispersion to the extent that it separates into at least two or more phases.

[0099] The compositions of the phases (G1) to (G2) in the aqueous dispersion (G) can vary depending on the composition of the aqueous dispersion (E) subjected to heating and the heating conditions.

[0100] In one embodiment, an aqueous dispersion (G) containing a phase (G1) having a fluoropolymer content of less than 1.00% by mass and a nonionic surfactant content of 5.00% by mass or more, based on the mass of the phase (G1), and a phase (G2) having a fluoropolymer content of 30.00% by mass or more and a nonionic surfactant content of less than 5.00% by mass, based on the mass of the phase (G2), is prepared.

[0101] In another embodiment, an aqueous dispersion containing: a phase (G1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass, based on the mass of the phase (G1), and a nonionic surfactant content of 5.00 to 20.00% by mass, based on the mass of the phase (G1); and a phase (G2) having a fluoropolymer content of 30.00 to 75.0% by mass, based on the mass of the phase (G2), and a nonionic surfactant content of 2.00% by mass or more and less than 5.00% by mass, based on the mass of the phase (G2), is prepared as the aqueous dispersion (G).

[0102] Further, as the aqueous dispersion (G), an aqueous dispersion containing: a phase (G1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of the aqueous dispersion (G) and a nonionic surfactant content of 0.50 mass% or more relative to the mass of the aqueous dispersion (G); and a phase (G2) having a fluoropolymer content of 10.0 mass% or more relative to the mass of the aqueous dispersion (G) and a nonionic surfactant content of less than 0.50 mass% relative to the mass of the aqueous dispersion (G) is prepared.

[0103] In another embodiment, an aqueous dispersion containing: a phase (G1) having a fluoropolymer content of 0.00% by mass or more and less than 1.00% by mass, based on the mass of the aqueous dispersion (G), and a nonionic surfactant content of 0.50 to 10.0% by mass, based on the mass of the aqueous dispersion (G); and a phase (G2) having a fluoropolymer content of 10.0 to 50.0% by mass, based on the mass of the aqueous dispersion (G), and a nonionic surfactant content of 0.50% by mass or more and less than 2.00% by mass, based on the mass of the aqueous dispersion (G), is prepared.

[0104] After preparing the aqueous dispersion (G) containing the phases (G1) to (G2), the phase (G2) may be recovered and a nonionic surfactant may be added to the phase (G2). By adding the nonionic surfactant to the phase (G2), an aqueous fluoropolymer dispersion having excellent dispersion stability can be obtained, despite the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group being reduced.

[0105] It is preferable to prepare an aqueous dispersion having a nonionic surfactant content of 4.0 to 12.0% by mass relative to the fluoropolymer by adding a nonionic surfactant to the recovered phase (G2). The content of the nonionic surfactant in the aqueous dispersion is more preferably 4.5% by mass or more, even more preferably 5.0% by mass or more, more preferably 10% by mass or less, even more preferably 8.0% by mass or less, and still more preferably 7.0% by mass or less.

[0106] After the phase (G2) is recovered, a viscosity adjuster, a pH adjuster, a preservative, a water-soluble polymer, etc. may be added to the phase (G2).

[0107] (Aqueous Dispersion (C)) The content of the fluoropolymer in the aqueous dispersion (C) to be heated to prepare the aqueous dispersion (D) or the aqueous dispersion (E) is preferably 10.0 to 50.0 mass%, more preferably 15.0 mass% or more, even more preferably 20.0 mass% or more, more preferably 45.0 mass% or less, even more preferably 40.0 mass% or less, and particularly preferably 35.0 mass% or less, based on the mass of the aqueous dispersion (C).

[0108] The content of the nonionic surfactant in the aqueous dispersion (C) to be heated to prepare the aqueous dispersion (D) or the aqueous dispersion (E) is preferably 2.00 to 20.0 mass% or more, even more preferably 2.70 mass% or more, particularly preferably 3.00 mass% or more, more preferably 9.0 mass% or less, even more preferably 8.0 mass% or less, still more preferably 7.0 mass% or less, particularly preferably 6.0 mass% or less, and most preferably 5.0 mass% or less.

[0109] The content of the fluorine-containing surfactant in the aqueous dispersion (C) to be heated to prepare the aqueous dispersion (D) or (E) is preferably 0 to 6,000 ppm by mass, more preferably 5,000 ppm by mass or less, even more preferably 4,500 ppm by mass or less, still more preferably 4,000 ppm by mass or less, particularly preferably 3,500 ppm by mass or less, and most preferably 3,000 ppm by mass or less, based on the mass of the aqueous dispersion (C). By heating an aqueous dispersion having a fluorine-containing surfactant content within the above range, an aqueous dispersion (E) separated into at least three phases can be easily prepared. If the content of the fluorine-containing surfactant in the aqueous dispersion is too high, even if the aqueous dispersion is heated at an appropriate temperature, it may separate into two phases and not be possible to separate into three or more phases. The content of the fluorine-containing surfactant in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the fluorine-containing surfactant from an aqueous dispersion, such as a method of subjecting the aqueous dispersion to ion exchange treatment. The content of the fluorine-containing surfactant in the aqueous dispersion (C) may be 100 ppb by mass or more, 200 ppb by mass or more, 300 ppb by mass or more, 400 ppb by mass or more, or 500 ppb by mass or more, relative to the mass of the aqueous dispersion (C).

[0110] The content of the polymer compound (I) having an ionic group in the aqueous dispersion (C) to be heated to prepare the aqueous dispersion (D) or (E) is preferably 0 to 6,000 ppm by mass, more preferably 5,000 ppm by mass or less, even more preferably 4,500 ppm by mass or less, still more preferably 4,000 ppm by mass or less, particularly preferably 3,500 ppm by mass or less, and most preferably 3,000 ppm by mass or less, based on the mass of the aqueous dispersion (C). By heating an aqueous dispersion having a content of the polymer compound (I) having an ionic group within the above range, an aqueous dispersion (E) separated into at least three phases can be easily prepared. If the content of the polymer compound (I) having an ionic group in the aqueous dispersion is too high, the aqueous dispersion may separate into two phases, and separation into three or more phases may not be possible, even when heated at an appropriate temperature. The content of the polymer compound (I) having an ionic group in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the polymer compound (I) having an ionic group from the aqueous dispersion, such as a method of adjusting the amount of the polymer compound (I) used in polymerization to prepare the aqueous dispersion. Furthermore, the content of the polymer compound (I) having an ionic group in the aqueous dispersion (C) may be 10 ppm by mass or more, 100 ppm by mass or more, more than 500 ppm by mass, or 1000 ppm by mass or more, relative to the mass of the aqueous dispersion (C).

[0111] (Ion exchange treatment) In the first production method, the aqueous dispersion (C) can be prepared by subjecting the aqueous dispersion (B) containing a nonionic surfactant and a fluorine-containing surfactant to an ion exchange treatment. The ion exchange treatment can be carried out by contacting the aqueous dispersion (B) with an ion exchange resin. By subjecting the aqueous dispersion (B) to the ion exchange treatment and separating the resulting aqueous dispersion (C) into three phases, an aqueous fluoropolymer dispersion with a further reduced fluorine-containing surfactant content can be produced.

[0112] In the second production method, the aqueous dispersion (B) obtained by adding a nonionic surfactant to the aqueous dispersion (A) can be used as the aqueous dispersion (C) as it is. In the second production method, too, the aqueous dispersion (C) may be prepared by subjecting the aqueous dispersion (B) containing the nonionic surfactant and the polymer compound (I) having an ionic group to an ion exchange treatment. By subjecting the aqueous dispersion (B) to an ion exchange treatment and separating the resulting aqueous dispersion (C) into three phases, it is possible to produce an aqueous fluoropolymer dispersion with a further reduced fluorine-containing surfactant content, especially even when the aqueous dispersion (B) contains a fluorine-containing surfactant in addition to the polymer compound (I) having an ionic group. In the second production method, too, the ion exchange treatment can be carried out in the same manner as in the first production method.

[0113] As the ion exchange resin, an anion exchange resin can be suitably used. ＋ R １ R ２ R ３ X － (In the formula, R １ , R ２ and R ３ are the same or different and are a hydrogen atom or an organic group, and R １ , R ２ and R ３ At least one of the groups is an organic group having 3 or more carbon atoms. X represents a counter ion. ４ R ５ (In the formula, R ４ and R ５ are the same or different and are a hydrogen atom or an organic group, and R ４ and R ５ At least one of the groups is an organic group having two or more carbon atoms.

[0114] In general formula (A1), R １ , R ２ and R ３ are the same or different and each represents a hydrogen atom or an organic group. １, R ２ and R ３ may all be organic groups, or one may be a hydrogen atom and two may be organic groups. Furthermore, two may be hydrogen atoms and one may be an organic group. The organic group has one or more carbon atoms. The organic group preferably has two or more carbon atoms. １ , R ２ and R ３ is a preferred embodiment in which the group is an organic group having two or more carbon atoms.

[0115] In general formula (A1), R １ , R ２ and R ３ At least one of R is an organic group having 3 or more carbon atoms. １ , R ２ and R ３ Among R, one may be an organic group having 3 or more carbon atoms, and two may be a hydrogen atom or an organic group having 1 or 2 carbon atoms. Alternatively, two may be organic groups having 3 or more carbon atoms, and one may be a hydrogen atom or an organic group having 1 or 2 carbon atoms. １ , R ２ and R ３ All of the groups may be organic groups having 3 or more carbon atoms.

[0116] R １ , R ２ and R ３ In the formula (I), the number of carbon atoms in the organic group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the organic group may be 5 or less.

[0117] In general formula (A1), R １ , R ２ and R ３ At least one of the groups is preferably an organic group having a carbon number of 4 or more. By adopting such a structure, the specific fluorine-containing compound can be removed more efficiently.

[0118] R １ , R ２ and R ３ The organic group in is preferably an alkyl group, an alkanol group, or an alkenyl group, more preferably an alkyl group or an alkanol group, and even more preferably an alkyl group.

[0119] In the present disclosure, the term "alkyl group" is a general term for a group remaining after removing one hydrogen atom from an aliphatic saturated hydrocarbon, and includes a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms.

[0120] In addition, in the present disclosure, the term "alkanol group" is a general term for the group remaining after removing one hydrogen atom from an alkanol, and includes linear or branched alkanol groups having one or more carbon atoms and cyclic alkanol groups having three or more carbon atoms.

[0121] R １ , R ２ and R ３ are the same or different and are alkyl groups having 2 or more carbon atoms or alkanol groups having 1 or more carbon atoms, and R １ , R ２ and R ３ At least one of these is preferably an alkyl group having 3 or more carbon atoms.

[0122] R １ , R ２ and R ３ are the same or different and are alkyl groups having 2 or more carbon atoms or alkanol groups having 2 or more carbon atoms, R １ , R ２ and R ３ In one of the more preferred embodiments, at least one of the groups is an alkyl group having 3 or more carbon atoms.

[0123] R １ , R ２ and R ３ are the same or different and are an alkyl group having 2 or more carbon atoms or an alkanol group having 1 or more carbon atoms; R １ , R ２ and R ３ In one preferred embodiment, at least one of the groups is an alkyl group having 4 or more carbon atoms.

[0124] Also, R １ , R ２ and R ３ are the same or different and are alkyl groups having 2 or more carbon atoms or alkanol groups having 2 or more carbon atoms, R １ , R ２and R ３ In one preferred embodiment, at least one of the groups is an alkyl group having 4 or more carbon atoms.

[0125] The number of carbon atoms in the alkyl group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the alkyl group may be 5 or less.

[0126] The alkanol group preferably has 10 or less carbon atoms, more preferably 8 or less carbon atoms, and even more preferably 6 or less carbon atoms. The alkanol group may have 5 or less carbon atoms.

[0127] In the general formula (A1), X is a counter ion. Examples of X include Cl, OH, Br, I, and NO. ３ , S.O. ４ and the like, and Cl or OH is preferable. ４ In the case of a divalent anion such as the above, one counter ion is coordinated to two molecules of the repeating units of general formula (A1).

[0128] In general formula (A2), R ４ and R ５ are the same or different and are a hydrogen atom or an organic group, and R ４ and R ５ At least one of R is an organic group having two or more carbon atoms. ４ and R ５ may all be organic groups, or one may be a hydrogen atom and the other an organic group.

[0129] In general formula (A2), R ４ and R ５ At least one of the groups is an organic group having two or more carbon atoms.

[0130] R ４ and R ５ Among R, one may be an organic group having two or more carbon atoms, and the other may be a hydrogen atom or an organic group having one carbon atom. ４ and R ５ may both be organic groups having two or more carbon atoms.

[0131] R ４ and R ５At least one of the groups may be an organic group having 3 or more carbon atoms, or may be an organic group having 4 or more carbon atoms.

[0132] Also, R ４ and R ５ It is also preferred that is an organic group having two or more carbon atoms.

[0133] R ４ and R ５ In the formula (I), the number of carbon atoms in the organic group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the organic group may be 5 or less.

[0134] R ４ and R ５ The organic group in is preferably an alkyl group, an alkanol group, or an alkenyl group, more preferably an alkyl group or an alkanol group, and even more preferably an alkyl group.

[0135] R ４ and R ５ are the same or different and are alkyl groups or alkanol groups, and ４ and R ５ In one of the more preferred embodiments, at least one of the groups is an alkyl group having two or more carbon atoms or an alkanol group having two or more carbon atoms.

[0136] The number of carbon atoms in the alkyl group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the alkyl group may be 5 or less.

[0137] The number of carbon atoms in the alkanol group is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the alkanol group may be 5 or less.

[0138] The anion exchange resin is preferably one in which a group represented by general formula (A1) or a group represented by general formula (A2) is bonded to a resin matrix. Examples of the anion exchange resin include a resin matrix made of a styrene-based or acrylic polymer to which a group represented by general formula (A1) or a group represented by general formula (A2) is bonded. The styrene-based or acrylic polymer used as the resin matrix is ​​not limited, and for example, a resin matrix used in a known anion exchange resin can be used. From the viewpoint of the removal efficiency of fluorine-containing compounds having a hydrophilic group, the anion exchange resin is preferably one in which the resin matrix is ​​styrene-based.

[0139] The basicity of the anion exchange resin can be varied depending on the type of polymer backbone and / or ion exchange group.

[0140] The anion exchange resin preferably has a pore diameter of 1 to 5,000 Å. From the viewpoint of removal efficiency, the pore diameter is preferably 50 Å or more, more preferably 100 Å or more, and even more preferably 150 Å or more. It may also be 200 Å or more, or 250 Å or more. It may also be 1,000 Å or less. The pore diameter can be calculated, for example, by measuring the specific surface area and total pore volume by gas adsorption method.

[0141] From the viewpoint of removal efficiency, the anion exchange resin preferably has a total exchange capacity of 0.1 eq / L-resin or more, more preferably 0.3 eq / L-resin or more, even more preferably 0.5 eq / L-resin or more, and particularly preferably 0.7 eq / L-resin or more. The upper limit is preferably 5.0 eq / L-resin or less, more preferably 2.0 eq / L-resin or less, and particularly preferably 1.5 eq / L-resin or less.

[0142] The water content of the anion exchange resin is preferably 20% by mass or more, more preferably 30 to 70% by mass, and even more preferably 35 to 65% by mass. When the water content of the anion exchange resin is 30% by mass or more, the fluorine-containing compound can be efficiently removed. Furthermore, the fluorine-containing compound easily diffuses within the anion exchange resin particles. When the water content of the anion exchange resin is 70% by mass or less, a decrease in the strength of the anion exchange resin particles due to insufficient cross-linking can be suppressed.

[0143] The moisture content of an anion exchange resin can be measured by the following method. First, 10 mL of a sample in the standard form is accurately weighed out using a measuring cylinder, the resin is wrapped in a cloth and centrifuged to remove any adhering moisture, and the mass of the resin is then quickly measured. Next, the resin is dried in a thermostatic oven at 105°C for 4 hours, and then allowed to cool in a desiccator for 30 minutes. The mass of the dried resin is then weighed and the moisture content is calculated using the following formula: Moisture content (mass%) = (mass of resin before drying (g) - mass of resin after drying (g)) / mass of resin before drying (g) x 100

[0144] Anion exchange resins are usually spherical. The average particle size of the anion exchange resin is preferably 0.1 to 5 mm, more preferably 0.2 to 2 mm, and particularly preferably 0.3 to 1.5 mm. If the average particle size of the anion exchange resin falls within the above range, the packed column of the anion exchange resin is less likely to clog. The average particle size is a value determined by a sieving method. Specifically, the anion exchange resin is first placed in a sieve shaker, and the particle size distribution is measured by sieving. Then, the diameter of the sieve opening corresponding to a total of 50% of the residual classification is determined, and this is taken as the average particle size.

[0145] As the anion exchange resin, a commercially available product may be used, for example, PFA694E, A592E manufactured by Purolite Corporation.

[0146] Furthermore, a resin having an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)) can also be used as the anion exchange resin. Such anion exchange resins include resins having at least one ion exchange group selected from the group consisting of an amino group and a quaternary ammonium group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)). Such anion exchange resins include resins having an ion exchange group represented by the following general formula (B1): -N ＋ (CH ３ ) ３ X － (wherein X represents a counter ion), or a group represented by the following general formula (B2): ＋ (CH ３ ) ２ (C ２ H ４ OH)X － (wherein X represents a counter ion) is preferred. X in general formulas (B1) and (B2) is preferably Cl, OH, Br, I, NO ３ , S.O. ４ and the like, and Cl or OH is preferable. ４ In the case of a divalent anion such as the above, one counter ion is coordinated to two molecules of the repeating units of general formula (A1).

[0147] The anion exchange resin is preferably one in which an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)) is bonded to a resin matrix, and examples of the resin matrix include styrene-based or acrylic polymers. The styrene-based or acrylic polymer used as the resin matrix is ​​not limited, and for example, a resin matrix used in a known anion exchange resin can be used. From the viewpoint of the removal efficiency of fluorine-containing compounds having a hydrophilic group, it is preferable that the resin matrix of the anion exchange resin B is styrene-based.

[0148] The resin having an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)) may be weakly basic or strongly basic. A strongly basic anion exchange resin is preferred. The basicity of the anion exchange resin can be varied depending on the type of polymer skeleton and / or ion exchange group.

[0149] The resin having an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)) preferably has a pore diameter of 1 to 5,000 Å. From the viewpoint of removal efficiency, the pore diameter is preferably 50 Å or more, more preferably 100 Å or more, and even more preferably 150 Å or more. It may also be 200 Å or more, or 250 Å or more. It may also be 1,000 Å or less. The pore diameter can be calculated, for example, by measuring the specific surface area and the total pore volume by a gas adsorption method.

[0150] From the viewpoint of removal efficiency, the resin having ion exchange groups (excluding the groups represented by the general formula (A1) and the groups represented by the general formula (A2)) preferably has a total exchange capacity of 0.1 eq / L-resin or more. More preferably, it is 0.3 eq / L-resin or more, even more preferably 0.5 eq / L-resin or more, and particularly preferably 0.7 eq / L-resin or more. Furthermore, the larger the total exchange capacity, the better, but for example, the upper limit is preferably 5.0 eq / L-resin, more preferably 2.0 eq / L-resin or less, and particularly preferably 1.5 eq / L-resin or less.

[0151] The water content of the resin having an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)) is preferably 20% by mass or more, more preferably 30 to 70% by mass, and even more preferably 35 to 65% by mass.

[0152] Resins having ion exchange groups (excluding the groups represented by the general formula (A1) and the groups represented by the general formula (A2)) are usually spherical. The average particle size of resins having ion exchange groups (excluding the groups represented by the general formula (A1) and the groups represented by the general formula (A2)) is preferably 0.1 to 5 mm, more preferably 0.2 to 2 mm, and particularly preferably 0.3 to 1.5 mm. If the average particle size is within the above range, the packed column of the anion exchange resin is less likely to clog. The average particle size is a value determined by a sieving method. Specifically, first, the anion exchange resin is placed in a sieve shaker and the particle size distribution is measured by sieving. Then, the diameter of the sieve opening corresponding to 50% of the total residual classification is determined and this is taken as the average particle size.

[0153] As the resin having an ion exchange group (excluding the group represented by the general formula (A1) and the group represented by the general formula (A2)), a commercially available product may be used, and examples thereof include the Diaion (trademark) SA series manufactured by Mitsubishi Chemical Corporation, A400, A300, etc. manufactured by Purolite, the Amberlite (trademark) series manufactured by DuPont, and the Amberjet (trademark) series such as IRA4002OH.

[0154] The ion exchange resin is preferably at least one selected from the group consisting of a resin in which a group represented by general formula (B1) is bonded to a styrene-based polymer and a resin in which a group represented by general formula (B2) is bonded to a styrene-based polymer. Of these, OH is preferred as X in general formulas (B1) and (B2).

[0155] The pressure when the aqueous dispersion is brought into contact with the ion exchange resin is not particularly limited, but may be, for example, 0.1 to 10 atmospheres, and the contact can be carried out at normal pressure (about 1 atmosphere).

[0156] The time for contacting the aqueous dispersion with the ion exchange resin is not particularly limited, and may be from 0.1 seconds to 100 hours, from 1 second to 50 hours, or from 1 second to 10 hours.

[0157] The amount of ion exchange resin to be contacted with the aqueous dispersion is preferably 10,000 g or less, preferably 0.1 g or more, more preferably 1 g or more, even more preferably 5 g or more, still more preferably 10 g or more, and particularly preferably 100 g or more, relative to 1,000 g of the fluoropolymer in the aqueous dispersion.

[0158] After the aqueous dispersion (B) is brought into contact with the ion exchange resin, the aqueous dispersion and the ion exchange resin are separated, and the aqueous dispersion (C) can be recovered.

[0159] The method for contacting the aqueous dispersion (B) with the ion exchange resin may be a batch method or a flow method.

[0160] The aqueous dispersion (B) may be contacted with the ion exchange resin once or twice or more times.

[0161] The aqueous dispersion (B) can be contacted with the ion exchange resin by a conventional method. For example, the method can be carried out by adding an ion exchange resin to the aqueous dispersion (B) and stirring, or by a column method in which the aqueous dispersion (B) is passed through a column packed with an ion exchange resin. The packed column used in the column method can be any of a moving type, a fixed bed type, or a fluidized bed type.

[0162] When the method of adding an ion exchange resin to the aqueous dispersion (B) and stirring is used, the aqueous dispersion (B) is contacted with the ion exchange resin, and then the ion exchange resin is separated from the aqueous dispersion. The method for separating the ion exchange resin from the aqueous dispersion is not limited, and for example, a method such as filtration can be used.

[0163] After the ion exchange treatment, a nonionic surfactant may be added to the recovered aqueous dispersion (C).

[0164] (Aqueous Dispersion (B)) In the first production method, the content of the fluoropolymer in the aqueous dispersion (B) to be subjected to the ion exchange treatment for preparing the aqueous dispersion (C) is preferably 10.0 to 50.0 mass%, more preferably 15.0 mass% or more, even more preferably 20.0 mass% or more, more preferably 15.0 mass% or less, even more preferably 40.0 mass% or less, and particularly preferably 35.0 mass% or less, based on the mass of the aqueous dispersion (B).

[0165] In the first production method, the content of the nonionic surfactant in the aqueous dispersion (B) to be subjected to the ion exchange treatment for preparing the aqueous dispersion (C) is preferably 1.00 to 10.0 mass%, more preferably 1.50 mass% or more, even more preferably 2.00 mass% or more, more preferably 8.0 mass% or less, even more preferably 7.0 mass% or less, particularly preferably 6.0 mass% or less, and most preferably 5.0 mass% or less, relative to the mass of the aqueous dispersion (B).

[0166] In the first production method, the content of the fluorine-containing surfactant in the aqueous dispersion (B) to be subjected to the ion exchange treatment for preparing the aqueous dispersion (C) is preferably 0 to 6,000 ppm by mass, more preferably 5,000 ppm by mass or less, even more preferably 4,500 ppm by mass or less, still more preferably 4,000 ppm by mass or less, particularly preferably 3,500 ppm by mass or less, and most preferably 3,000 ppm by mass or less, relative to the mass of the aqueous dispersion (B). The content of the fluorine-containing surfactant in the aqueous dispersion (B) may be 100 ppb by mass or more, 1,000 ppb by mass or more, 3,000 ppb by mass or more, 5,000 ppb by mass or more, or 7,000 ppb by mass or more, relative to the mass of the aqueous dispersion (B).

[0167] (Polymerization of fluoromonomer) In the first production method, the aqueous dispersion (B) can be prepared by a method in which an aqueous dispersion (A) containing a fluoropolymer is prepared by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant, a polymerization initiator and an aqueous medium, and a nonionic surfactant is added to the aqueous dispersion (A) to prepare the aqueous dispersion (B). In the second production method, the aqueous dispersion (B) can be prepared by a method in which an aqueous dispersion (A) containing a fluoropolymer is prepared by polymerizing a fluoromonomer in the presence of a polymer compound (I) having an ionic group, a polymerization initiator and an aqueous medium, and a nonionic surfactant is added to the aqueous dispersion (A) to prepare the aqueous dispersion (B).

[0168] According to the production method of the present disclosure, by recovering phase (E3) or recovering phase (G2), it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant or polymer compound (I) having an ionic group. In one embodiment, the content of fluorine-containing surfactant in the aqueous fluoropolymer dispersion obtained by the first production method of the present disclosure is not more than an amount corresponding to 0.001% by mass of the content of fluorine-containing surfactant contained in the aqueous dispersion (A).

[0169] The content of the fluorine-containing surfactant in the aqueous dispersion (A) obtained by polymerization may be 10 mass ppm or more, 100 mass ppm or more, 1000 mass ppm or more, and 10 mass% or less, 5 mass% or less, or 1 mass% or less, relative to the fluoropolymer in the aqueous dispersion (A). The content of the polymer compound (I) having an ionic group in the aqueous dispersion (A) obtained by polymerization may be 10 mass ppm or more, 100 mass ppm or more, more than 500 mass ppm, 1000 mass ppm or more, and 10 mass% or less, 5 mass% or less, or 1 mass% or less, relative to the fluoropolymer in the aqueous dispersion (A).

[0170] The polymerization of fluoromonomer can be carried out by charging a reactor with fluoromonomer, a fluorine-containing surfactant or a polymer compound (I) having an ionic group, a polymerization initiator, an aqueous medium and, if necessary, other additives, stirring the contents of the reactor, and maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to initiate the polymerization reaction.After the start of the polymerization reaction, fluoromonomer, polymerization initiator, fluorine-containing surfactant, chain transfer agent, etc. may be additionally added depending on the purpose.The polymerization method of fluoromonomer is not particularly limited, but emulsion polymerization method is preferred.

[0171] (Fluorine-containing surfactant) The fluorine-containing surfactant used in the polymerization of the fluoromonomer is not particularly limited as long as it is a surfactant containing at least one fluorine atom, and any conventionally known fluorine-containing surfactant can be used.

[0172] 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.

[0173] 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" means the part 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.

[0174] The fluorine-containing surfactant also includes a fluorine-containing surfactant having a Log POW of 3.5 or less. The Log POW of the fluorine-containing surfactant is preferably 3.4 or less, more preferably 2.0 or more, and even more preferably 2.5 or more. The Log POW is a 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 calculated 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.

[0175] 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.

[0176] 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 ７ is H or an organic group. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., 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.

[0177] 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 and / or a chlorine atom, 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 an ether bond; Y ｎ１ and Y ｎ２are 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.

[0178] 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.

[0179] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF２ ) 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.

[0180] 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).

[0181] The perfluoroethercarboxylic acid (III) is a compound represented by the following general formula (III): １ -O-(CF(CF ３ )CF ２ O) ｎ３ CF (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.

[0182] 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.

[0183] 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.

[0184] 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).

[0185] The ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII): H(CF ２ ) ｎ６ SO ３ M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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 ９ is 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.

[0190] 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 ３M or COOM (wherein M is as defined above). Examples of L include a single bond, a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0191] 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) ｎ１０ CF ２ COONH ４ (a mixture having an average molecular weight of 750, wherein n9 and n10 are defined above).

[0192] As mentioned above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0193] The fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0194] The fluorine-containing surfactant preferably has a methylene group (—CH ２ -), and more preferably, does not have a C-H bond. ２ By using a fluorine-containing surfactant having no - or C--H bond, the polymerization of the fluoromonomer can be smoothly carried out in the presence of an aqueous medium.

[0195] The number of H atoms in the hydrophobic group of the fluorine-containing surfactant is preferably 0 or 1, more preferably 0. By using a fluorine-containing surfactant having a small number of H atoms bonded to the carbon atoms constituting the hydrophobic group, the polymerization of the fluoromonomer can be smoothly carried out in the presence of an aqueous medium. The number of carbon atoms in the hydrophobic group of the fluorine-containing surfactant having a hydrophobic group and a hydrophilic group is preferably 1 to 50, more preferably 3 to 20, and even more preferably 6 to 12. The hydrophobic group usually constitutes the above-mentioned "portion excluding the anionic group" of the molecular structure of the fluorine-containing surfactant. As the hydrophilic group, Y ０ Examples of the anionic group include the groups exemplified above for the anionic group of the formula (I). The fluorine-containing surfactant may be a saturated fluorinated surfactant in which all of the carbon atoms bonded to the hydrophobic group have been substituted with fluorine atoms.

[0196] As the fluorine-containing surfactant, among the above-mentioned anionic fluorine-containing surfactants, those represented by the general formula (N １ ), a compound represented by the general formula (N ２ ), a compound represented by the general formula (N ４ ): Rf ｎ４ -O-(CY ｎ１ F) ｐ CF ２ -Y ０ (N ４ ) (wherein, Rf ｎ４ is a linear or branched or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether linkage (provided that -CH ２ -), and Y ｎ１ is 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 may be the same or different and are H, F, or a linear or branched alkyl group having 1 to 6 carbon atoms, which may contain an ether bond, or a fully fluorinated alkyl group (provided that -CH ２ -), except that X ｎ３ and Xｎ４ Both of Rf cannot be H. ｎ５ is a linear or branched or fully fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond (provided that -CH ２ -), L is a linking group, and 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.

[0197] As the fluorine-containing surfactant, among the above-mentioned anionic fluorine-containing surfactants, perfluorocarboxylic acid (I) represented by general formula (I), ω-H perfluorocarboxylic acid (II) represented by general formula (II), perfluoroether carboxylic acid (III) represented by general formula (III), perfluoroalkyl alkylene carboxylic acid (IV) represented by general formula (IV), perfluoroalkoxy fluorocarboxylic acid (V) represented by general formula (V), perfluoroalkyl sulfonic acid (VI) represented by general formula (VII), ω-H perfluoro sulfonic acid (VII) represented by general formula (VII), perfluoroalkyl alkylene sulfonic acid (VIII) represented by general formula (VIII), general formula (X): Rf ７ -O-Rf ８ -O-CF ２ -COOM (where Rf ７ is a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain ether bonds and / or chlorine atoms (provided that -CH ２ -), and Rf ８ is a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms (provided that -CH ２ Fluorocarboxylic acid (X) represented by general formula (XI): Rf ９ -O-CY １ FCF ２ -SO ３ M (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 (provided that -CH ２ -), and Y １ is H or F, and M is as defined above.) an alkoxyfluorosulfonic acid (XI) represented by the general formula (XII): (In the formula, X １ , X ２ and X ３ may be the same or different and are H, F and straight or branched chain alkyl groups having 1 to 6 carbon atoms which may contain ether bonds or fully fluorinated alkyl groups (provided that -CH ２ -), except that X ２ and X ３ Both of Rf １０ is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y ０ is an anionic group.) and a compound (XII) represented by the general formula (XIII): Rf １１ -O-(CF ２ CF (CF ３ ) O) ｎ９ (CF ２ O) ｎ１０ CF ２ COOM (where Rf １１ represents a fluoroalkyl group having 1 to 5 carbon atoms and containing chlorine (wherein -CH ２ n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above. The use of these fluorine-containing surfactants allows the polymerization of fluoromonomers to proceed smoothly in the presence of an aqueous medium.

[0198] Examples of the fluorine-containing surfactant include compounds represented by the following formula: F(CF ２ ) ７ COOM, F(CF ２ ) ５COOM, H(CF ２ ), ６ COOM, H(CF ２ ), ７ COOM, CF ３ O(CF ２ ), ３ OCHFCF ２ COOM, C ３ F ７ OCF(CF ３ ),CF ２ OCF(CF ３ ),COOM, CF ３ CF ２ CF ２ OCF(CF ３ ),COOM, CF ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C ２ F ５ OCF(CF ３ ),CF ２ OCF(CF ３ ),COOM, CF ３ OCF(CF ３ ),CF ２ OCF(CF ３ ),COOM, CF ２ ClCF ２ CF ２ OCF(CF ３ ),CF ２ OCF ２ COOM, CF ２ ClCF ２ CF ２ OCF ２ CF(CF ３ ),OCF ２ COOM, CF ２ ClCF(CF ３ ),OCF(CF ３ ),CF ２ OCF ２ COOM, CF ２ ClCF(CF ３ ),OCF ２ CF(CF ３ ),OCF ２ COOM, (In each formula, M is H, a metal atom, NR ７４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. ７ is H or an organic group.

[0199] The amount of the fluorine-containing surfactant added is preferably 10 ppm by mass to 10% by mass, more preferably 100 ppm by mass or more, even more preferably 300 ppm by mass or more, and more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to the aqueous medium.

[0200] (Polymer Compound (I) Having Ionic Group) The polymer compound (I) having an ionic group used in the polymerization of a fluoromonomer is a polymer having one or more ionic groups in the molecule. The ionic group is preferably an anionic group.

[0201] The anionic groups contained in the polymer compound (I) include anionic groups such as sulfate groups and carboxylate groups, as well as acid groups such as —COOH, —COONH ４ The 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.

[0202] The ion exchange capacity of the polymer compound (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 compound (I) and is calculated from the composition of the polymer compound (I).

[0203] In the polymeric compound (I), the ionic (anionic) groups are typically distributed along the polymer backbone. The polymeric compound (I) comprises a polymer backbone with recurring side chains attached to the backbone, which preferably carry ionic groups.

[0204] Preferably, polymeric compound (I) comprises an ionic group having a pKa of less than 10, more preferably less than 7. The ionic group of polymeric compound (I) is preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, and phosphate.

[0205] 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.

[0206] The ionic group is —SO ３ M, -COOM or -P(O)(OM) ２ The "M" in the ionic group (anionic group) is preferably an anionic group (A) as described below. ０ ) is the same as the "M" in

[0207] The polymer compound (I) is preferably a polymer compound in which the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or more. The "proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms" is calculated as the proportion of the number of fluorine atoms to the total number of hydrogen atoms bonded to carbon atoms and halogen atoms (including fluorine atoms) bonded to carbon atoms.

[0208] The polymer compound (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 main chain relative to the ionic group. ２ F) is not considered an ionizable group for purposes of determining IXR.

[0209] 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.

[0210] The polymer compound (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 compound (I) cannot be measured by dynamic light scattering (DLS), for example, or the particle size is 10 nm or less.

[0211] The number average molecular weight of the polymer compound (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 ４More 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 the polymer compound (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.

[0212] The lower limit of the weight average molecular weight of the polymer compound (I) is, in order of preference, 0.2×10 ４ That's it, 0.4 x 10 ４ 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 compound (I) is, in order of preference, 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.

[0213] The viscosity of an aqueous solution of polymer compound (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.

[0214] The viscosity of the aqueous solution of polymer compound (I) can be determined by adjusting the content of polymer compound (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.

[0215] The critical micelle concentration (CMC) of the polymer compound (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.

[0216] The critical micelle concentration of the polymer compound (I) can be determined by measuring the surface tension, for example, using a surface tensiometer DY-300 manufactured by Kyowa Interface Science Co., Ltd.

[0217] The acid value of the polymer compound (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.

[0218] The acid value of the polymer compound (I) is determined by the amount of anionic groups other than the acid functional groups of the polymer compound (I), 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.

[0219] The polymer compound (I) is preferably a polymer containing polymerized units (I) based on the monomer (I) represented by the general formula (I): １ X ３ =CX ２R (-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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] R is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group.

[0224] 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.).

[0225] R may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group.

[0226] 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.

[0227] 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.

[0228] 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(CF３ )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.

[0229] 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.

[0230] 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, X６ 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.

[0231] 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(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 )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.

[0232] -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 ６are 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:

[0233] 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:

[0234] -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 CF ２ -, -O-CF２ 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(CF ３ )CF２ -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 )-, or, -CF ２ -O-CF(CF ３ )CF ２ -O-C(CF ３ ) ２ - is preferred, -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(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 )-, or, -CF ２ -O-CF(CF ３ )CF２ -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.

[0235] It is also preferred that the polymeric compound (I) is highly fluorinated. For example, a phosphate group moiety (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 the polymer compound (I) are substituted with C—F bonds.

[0236] The monomer (I) and the polymer compound (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.

[0237] The monomer (I) and the polymer compound (I) may be partially fluorinated. That is, the monomer (I) and the polymer compound (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.

[0238] Anionic group (A ０ ) is -SO ２ M, -SO３ 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.

[0239] M is H, a metal atom, or NR ７４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group.

[0240] The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li.

[0241] 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.

[0242] In the polymer compound (I), each polymer unit (I) may have a different anionic group or may have the same anionic group.

[0243] The monomer (I) is preferably a monomer (1) represented by the general formula (1). The polymer compound (I) is preferably a polymer compound (1) containing a polymer 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 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.)

[0244] The polymer compound (1) may be a homopolymer of the monomer (1) represented by the general formula (1), or may be a copolymer with other monomers.

[0245] 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.

[0246] 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.

[0247] 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.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] 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.

[0252] 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 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).

[0253] 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 ２O-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 CF ２ O-CF ２ CH ２ The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0254] 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).

[0255] 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:

[0256] The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li.

[0257] 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 ４is 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.

[0258] A is -COOM or -SO ３ M is preferred.

[0259] 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).

[0260] 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.

[0261] The polymer compound (1) may be a homopolymer of the monomer represented by the general formula (1a) or a copolymer with other monomers.

[0262] 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.)

[0263] The polymer compound (1) may be a homopolymer of the monomer represented by the general formula (1A) or a copolymer with other monomers.

[0264] Specific examples of the monomer represented by formula (1A) include the monomer represented by the general formula:

[0265]

[0266] (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 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,

[0267]

[0268] Among them,

[0269]

[0270] It is preferable that:

[0271] 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.

[0272] The monomer (I) is preferably a monomer (2) represented by the general formula (2). The polymer compound (I) is preferably a polymer compound (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.)

[0273] The monomer (I) is preferably a monomer (3) represented by the general formula (3). The polymer compound (I) is preferably a polymer compound (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.)

[0274] The polymer compound (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 the 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 compound (I) may contain polymerized units (I) based on two or more different monomers represented by the general formula (I).

[0275] The polymeric compound (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 to form the polymeric compound (I) or during the chain transfer reaction.

[0276] In the polymer compound (I), the content of the polymerized units (I) relative to all 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 compound (I) is most preferably composed only of the polymerized units (I).

[0277] In the polymer compound (I), the content of polymerized 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 polymerized units. It is particularly preferable that the content of polymerized 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 compound (I) does not contain polymerized units based on other monomers.

[0278] (Polymerization initiator) The polymerization initiator used for the polymerization of fluoromonomer 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.

[0279] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0280] 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-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetradecafluorooctanoyl) 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.

[0281] 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, perboric acid, 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.

[0282] 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 redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0283] 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.

[0284] 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.

[0285] The radical concentration during polymerization of fluoromonomers can be adjusted by adding a decomposer. Examples of decomposers include sulfites, bisulfites, bromates, diimines, oxalic acid, copper salts, and iron salts. Examples of sulfites include sodium sulfite and ammonium sulfite. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate. The amount of decomposer added is in the range of 25 to 300% by mass relative to the amount of oxidizing agent combined as a polymerization initiator (redox initiator). The amount of decomposer added is preferably 25 to 150% by mass, more preferably 50 to 100% by mass. The decomposer is preferably added after 5% by mass of the total fluoromonomer consumed in the polymerization reaction has been polymerized, and more preferably after 10% by mass has been polymerized. The amount of decomposer added is preferably an amount equivalent to 0.1 to 20 ppm by mass of the aqueous medium used, and more preferably an amount equivalent to 3 to 10 ppm by mass.

[0286] (Aqueous medium) The aqueous medium used for the polymerization of the fluoromonomer 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 ether or a ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less.

[0287] The aqueous medium is preferably an aqueous medium containing only water, or an aqueous medium containing only water and a fluorine-free organic solvent, and more preferably an aqueous medium containing only water.

[0288] The content of water in the aqueous medium is preferably 90% or more, more preferably 95% or more, even more preferably 99.0% or more, still more preferably 99.5% or more, particularly preferably 99.9% or more, and may be 100%, based on the mass of the aqueous medium.

[0289] (Fluoromonomer) The fluoromonomer used in polymerization has at least one fluorine atom and 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 heterocyclic compound, and a monomer that provides a crosslinking site.

[0290] The fluoroalkyl vinyl ether [FAVE] is, for example, a compound represented by the general formula (110): CF ２ =CF-ORf １１１ (wherein, Rf １１１ represents a perfluoroorganic group.) A fluoromonomer represented by general formula (120): CF ２ =CF-OCH ２ -Rf １２１ (wherein, 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 (wherein, Rf １３１is 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 (CF ２ 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 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.

[0291] 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.

[0292] 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.

[0293] 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:

[0294]

[0295] (wherein m represents 0 or an integer of 1 to 4), Rf １１１ is of the following formula:

[0296]

[0297] (wherein n represents an integer of 1 to 4).

[0298] Among the fluoromonomers represented by the general formula (110), those represented by the general formula (160): CF ２=CF-ORf １６１ (wherein, Rf １６１ Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. １６１ is preferably a perfluoroalkyl group having 1 to 5 carbon atoms.

[0299] The fluoroalkyl vinyl ether is preferably at least one selected from the group consisting of fluoromonomers represented by the general formulae (160), (130) and (140).

[0300] The fluoromonomer represented by the general formula (160) is generally called perfluoro(alkyl vinyl ether). As the fluoromonomer represented by the general formula (160), at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether) is preferred, and at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether) is more preferred.

[0301] 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 C.F. ２ = CFOCF ２ OCF ２ CF ２ OCF ３ At least one selected from the group consisting of:

[0302] 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 (CF ３ ) O) ２ (CF ２ ) ２ At least one selected from the group consisting of F is preferred.

[0303] 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:

[0304] 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 CF２ H, CH ２ =CFCF ２ CF ２ CF 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:

[0305] The fluoroalkylethylene includes fluoroalkyl ethylenes 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 At least one selected from the group consisting of:

[0306] The fluoroalkyl allyl ether is, for example, a compound represented by the general formula (180): CF ２ =CF-CF ２ -ORf １１１ (wherein, Rf １１１ represents a perfluoroorganic group.

[0307] 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 F５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ and C.F. 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 C.F. 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 preferred.

[0308] 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.

[0309] (In the formula, Z ２３１ and Z ２３２ are independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0310] 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 １８２are independently a hydrogen atom, a fluorine atom, or CH ３ , R ｆ １８１ 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 ２OH.) and a fluoromonomer represented by the general formula (220): CR ２２１ R ２２２ =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.

[0311] 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 —CH２ It is preferably OH.

[0312] 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 C.F. ２ = CFO (CF ２ ) ５ CN, and CF ２ = CFOCF ２CF (CF ３ ) OCF ２ CF ２ CN and CF ２ = CFOCF ２ CF ２ CH ２ I is more preferred.

[0313] 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, vinyl hydroxybenzo ... vinyl esters such as vinyl hydroxypropioate, 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.

[0314] The above-mentioned fluorine-free monomer may also be a functional group-containing hydrocarbon monomer (excluding the monomer that provides a crosslinking site).Examples of the above-mentioned functional group-containing hydrocarbon monomer include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; fluorine-free monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, and perfluorobutenoic acid; fluorine-free monomers having a sulfo group such as vinyl sulfonic acid; fluorine-free monomers having a glycidyl group such as glycidyl vinyl ether and glycidyl allyl ether; fluorine-free monomers having an amino group such as aminoalkyl vinyl ether and aminoalkyl allyl ether; fluorine-free monomers having an amide group such as (meth)acrylamide and methylolacrylamide; fluorine-free monomers having a nitrile group such as acrylonitrile and methacrylonitrile.

[0315] In the above polymerization, one or more of the above fluoromonomers are polymerized to obtain particles of the desired fluoropolymer.

[0316] (Chain Transfer Agent) In the production method of the present disclosure, the fluoromonomer can be polymerized in the presence of a chain transfer agent. The use of a chain transfer agent can adjust the polymerization rate and molecular weight. 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 chain transfer agent used is usually 1 to 50,000 mass ppm, preferably 1 to 20,000 mass ppm, based on the total amount of fluoromonomer supplied. The amount of chain transfer agent used is preferably an amount that is completely consumed during the polymerization of the fluoromonomer and does not remain in the aqueous dispersion containing the fluoropolymer, so as not to reduce the removal efficiency of the fluorine-containing compound having a hydrophilic group as much as possible. Therefore, the amount of chain transfer agent used is more preferably 10,000 mass ppm or less, even more preferably 5,000 mass ppm or less, still more preferably 1,000 mass ppm or less, particularly preferably 500 mass ppm or less, and most preferably 200 mass ppm or less, based on the total amount of fluoromonomer 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] (Other Additives) In the polymerization of fluoromonomers, additives such as buffers, pH adjusters, stabilizing aids, and dispersion stabilizers can be used. In addition, in the polymerization of fluoromonomers, radical scavengers and decomposers can be added to adjust the polymerization rate and molecular weight. In addition, in the polymerization of fluoromonomers, fluorine-free anionic surfactants, fluorine-free nonionic surfactants, fluorine-free cationic surfactants, etc. may be used.

[0323] 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.

[0324] 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.

[0325] (Polymerization conditions) Polymerization of fluoromonomers can be carried out under normal pressure and temperature. 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, the molecular weight of the target fluoropolymer, the reaction rate, etc.

[0326] (Polymerization Terminator) A polymerization terminator (radical scavenger) may be added to terminate the polymerization reaction of the fluoromonomer.

[0327] As the polymerization terminator, a compound that does not have the ability to re-initiate after addition or chain transfer to a free radical in the polymerization system is used. Specifically, a compound that easily undergoes a chain transfer reaction with a primary radical or a propagating radical to generate a stable radical that does not subsequently react with a monomer, or a compound that easily undergoes an addition reaction with a primary radical or a propagating radical to generate a stable radical, is used. The activity of what is generally called a chain transfer agent is characterized by the chain transfer constant and the re-initiation efficiency, and among chain transfer agents, those with a re-initiation efficiency of almost 0% are called polymerization terminators. Examples of polymerization terminators include aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl ２ ) is preferred. Examples of aromatic hydroxy compounds include unsubstituted phenol, polyhydric phenol, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, etc. Examples of the unsubstituted phenol include o-, m-, or p-nitrophenol, o-, m-, or p-aminophenol, p-nitrosophenol, etc. Examples of polyhydric phenols include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, naphthresorcinol, etc. Examples of aromatic amines include o-, m-, or p-phenylenediamine, benzidine, etc. Examples of the quinone compounds include hydroquinone, o-, m-, or p-benzoquinone, 1,4-naphthoquinone, alizarin, etc. Examples of thiocyanates include ammonium thiocyanate (NH ４ Examples of the polymerization terminator include potassium thiocyanate (KSCN), sodium thiocyanate (NaSCN), etc. Among these, quinone compounds are preferred, and hydroquinone is more preferred.

[0328] (Nonionic surfactant) After preparing an aqueous dispersion (A) containing a fluoropolymer by polymerizing a fluoromonomer, an aqueous dispersion (B) is prepared by adding a nonionic surfactant to the aqueous dispersion (A).

[0329] In the manufacturing method of the present disclosure, a nonionic surfactant can be added to the aqueous dispersion as appropriate.

[0330] 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 water-soluble functional groups, such as ethylene ether chains derived from polymerization with ethylene oxide.

[0331] 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.

[0332] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0333] Specific examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0334] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0335] Specific examples of sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0336] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0337] Specific examples of glycerol esters include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[0338] Specific examples of the above derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0339] The ethers and esters may have an HLB value of 10-18.

[0340] The HLB value of the nonionic surfactant is preferably 10 to 18, more preferably 11 to 15, and even more preferably 12 to 14. The HLB value of the nonionic surfactant is a value defined by the Griffin method using the following calculation formula: HLB value = 20 x [sum of chemical formula weights of hydrophilic moieties] / molecular weight

[0341] The static surface tension of the nonionic surfactant is preferably less than 30 mN / m, more preferably less than 29 mN / m, and even more preferably less than 28 mN / m. The static surface tension of the nonionic surfactant can be measured by preparing a 0.1 mass % aqueous solution of the nonionic surfactant and measuring the aqueous solution at 25°C by the Wilhelmy method.

[0342] The molecular weight of the nonionic surfactant is preferably 200 g / mol or more, more preferably 300 g / mol or more, and is preferably 800 g / mol or less, more preferably 700 g / mol or less, and even more preferably 600 g / mol or less. When the molecular weight of the nonionic surfactant is within the above range, phase formation is likely to occur.

[0343] The nonionic surfactant may be a surfactant that is liquid at 25°C or a surfactant that is solid at room temperature, but a surfactant that is liquid at 25°C is preferred because it is easier to handle.

[0344] 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.

[0345] 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.

[0346] In the above nonionic surfactants, the hydrophobic group may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group.

[0347] 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.

[0348] 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 aqueous dispersion 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 aqueous dispersion increases, and the permeability and wettability tend to decrease.

[0349] The HLB value of the nonionic surfactant represented by formula (i) is preferably 10-18, more preferably 11-15, and even more preferably 12-14.

[0350] The static surface tension of the nonionic surfactant represented by general formula (i) is preferably less than 30 mN / m, more preferably less than 29 mN / m, and even more preferably less than 28 mN / m.

[0351] The molecular weight of the nonionic surfactant represented by general formula (i) is preferably 200 g / mol or more, more preferably 300 g / mol or more, and is preferably 800 g / mol or less, more preferably 700 g / mol or less, and even more preferably 600 g / mol or less. When the molecular weight of the nonionic surfactant is within the above range, phase formation is likely to occur.

[0352] The nonionic surfactant represented by general formula (i) may be a surfactant that is liquid at 25°C or a surfactant that is solid at room temperature, but a surfactant that is liquid at 25°C is preferred because it is easier to handle.

[0353] The cloud point of the nonionic surfactant represented by general formula (i) is preferably 40 to 80°C, more preferably 45°C or higher, even more preferably 50°C or higher, more preferably 76°C or lower, even more preferably 73°C or lower.

[0354] 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 the viscosity and sedimentation stability of the aqueous dispersion, 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 It is preferable that the number of oxypropylene groups is 0.5 to 1.5 on average, since this results in good low foaming properties. １ The polyoxyalkylene chain of A is preferably a polyoxyalkylene chain having 4 to 18, preferably 7 to 12, more preferably 8 to 11 alkylene oxide units. １ The polyoxyalkylene chain is preferably a polyoxyethylene chain having 4 to 18, preferably 7 to 12, more preferably 8 to 11 ethylene oxide units.

[0355] 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.

[0356] 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).

[0357] 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).

[0358] 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, R ７ 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).

[0359] 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 the viscosity and sedimentation stability of the aqueous dispersion, 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.

[0360] More preferably, R ７is 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.

[0361] 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.

[0362] 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.

[0363] 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 ２Typical 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. 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.

[0364] 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.

[0365] 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).

[0366] The nonionic surfactant preferably does not contain an aromatic moiety.

[0367] Nonionic surfactants include, among others, ethoxylates of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, ethoxylates of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, 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 At least one selected from the group consisting of —H (wherein n is an integer of 1 or more) is preferred.

[0368] The cloud point of the nonionic surfactant is preferably 40 to 80°C, more preferably 45°C or higher, even more preferably 50°C or higher, and more preferably 76°C or lower, even more preferably 73°C or lower.

[0369] In one embodiment of the manufacturing method of the present disclosure, after preparing an aqueous dispersion by polymerization of a fluoromonomer, no radical generator is added to the aqueous dispersion in any step. The radical generator is a compound that can decompose at the temperature of the aqueous dispersion after heating to generate radicals. Examples of radical generators include organic peroxides, inorganic peroxides, organic azo compounds, and combinations of oxidizing agents and reducing agents. According to the manufacturing method of the present disclosure, the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group can be reduced without adding a radical generator to the aqueous dispersion. Therefore, disadvantages caused by adding a radical generator, such as the occurrence of aggregation of the fluoropolymer, can be avoided.

[0370] As described above, by using the production method of the present disclosure, an aqueous fluoropolymer dispersion having a reduced content of the fluorine-containing surfactant or the polymeric compound (I) having an ionic group can be produced.

[0371] 2. Aqueous fluoropolymer dispersion The first aqueous fluoropolymer dispersion of the present disclosure contains a fluoropolymer and an anionic fluorine-containing surfactant, and the content of the anionic fluorine-containing surfactant is more than 0 ppb by mass and less than 100 ppb by mass relative to the fluoropolymer. The first aqueous fluoropolymer dispersion of the present disclosure can be suitably produced by the first production method of the present disclosure described above.

[0372] The second aqueous fluoropolymer dispersion of the present disclosure contains a fluoropolymer and a polymer compound (I) having an ionic group, is substantially free of anionic fluorine-containing surfactant, the content of the polymer compound (I) having an ionic group is more than 0 ppm by mass and not more than 500 ppm by mass relative to the fluoropolymer, and the proportion of hydrogen atoms bonded to carbon atoms of the polymer compound (I) having an ionic group substituted with fluorine atoms is 50% or more. The second aqueous fluoropolymer dispersion of the present disclosure can be suitably produced by the second production method of the present disclosure described above.

[0373] The content of the fluoropolymer in the aqueous fluoropolymer dispersion may be 30% by mass or more, preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 57% by mass or more, still more preferably 60% by mass or more, and preferably 70% by mass or less, more preferably 68% by mass or less, even more preferably 67% by mass or less, still more preferably 65% ​​by mass or less, based on the mass of the aqueous dispersion.

[0374] The fluoropolymer contained in the aqueous fluoropolymer dispersion of the present disclosure will be described later.

[0375] The content of the anionic fluorine-containing surfactant in the first fluoropolymer aqueous dispersion is more than 0 ppb by mass and less than 100 ppb by mass, based on the mass of the aqueous dispersion.

[0376] The second aqueous fluoropolymer dispersion is substantially free of anionic fluorine-containing surfactants.

[0377] In the present disclosure, "substantially free of anionic fluorine-containing surfactant" means that the content of anionic 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 anionic fluorine-containing surfactant as measured by liquid chromatography-mass spectrometry (LC / MS).

[0378] The anionic fluorine-containing surfactant contained in the aqueous fluoropolymer dispersion of the present disclosure is the same as the anionic fluorine-containing surfactant used in the production method of the present disclosure, and the same is preferred. The content of the anionic fluorine-containing surfactant in the aqueous fluoropolymer dispersion can be measured by the above-mentioned method for measuring the content of the fluorine-containing surfactant in the aqueous dispersion.

[0379] The content of the polymeric compound (I) having an ionic group in the second aqueous fluoropolymer dispersion is preferably 800 ppm by mass or less, more preferably 600 ppm by mass or less, even more preferably 500 ppm by mass or less, still more preferably 400 ppm by mass or less, particularly preferably 350 ppm by mass or less, preferably more than 0 ppm by mass, more preferably 0.1 ppm by mass or more, based on the fluoropolymer.

[0380] The polymer compound (I) having an ionic group contained in the aqueous fluoropolymer dispersion of the present disclosure is the same as the polymer compound (I) having an ionic group used in the production method of the present disclosure, and the same is preferable. The content of the polymer compound (I) having an ionic group in the aqueous fluoropolymer dispersion can be measured by the above-mentioned method for measuring the content of the polymer compound (I) having an ionic group in the aqueous dispersion.

[0381] The aqueous fluoropolymer dispersion of the present disclosure preferably contains a nonionic surfactant. The nonionic surfactant is the same as the nonionic surfactant that can be used in the production method of the present disclosure, and the same is preferred. The content of the nonionic surfactant in the aqueous fluoropolymer dispersion is 4.0 to 12.0 mass%, more preferably 4.5 mass% or more, even more preferably 5.0 mass% or more, more preferably 10 mass% or less, even more preferably 8.0 mass% or less, and still more preferably 7.0 mass% or less, based on the fluoropolymer.

[0382] The aqueous fluoropolymer dispersion of the present disclosure also preferably contains a viscosity modifier. The content of the viscosity modifier in the aqueous fluoropolymer dispersion is preferably 10 to 5000 ppm by mass, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, more preferably 4000 ppm by mass or less, and even more preferably 3000 ppm by mass or less, relative to the fluoropolymer.

[0383] As the viscosity modifier, a non-fluorine-containing anionic surfactant can be suitably used. The non-fluorine-containing anionic surfactant typically has a hydrophilic portion such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion which is a long-chain hydrocarbon portion such as an alkyl.

[0384] Examples of the fluorine-free anionic surfactant include alkyl sulfates such as lauryl sulfate, alkylaryl sulfonic acids such as dodecylbenzenesulfonic acid, alkyl sulfosuccinates, and salts thereof. The fluorine-free anionic surfactant may be composed of one or more of these compounds in combination.

[0385] The sulfosuccinic acid alkyl ester and its salts may be monoesters, but are preferably diesters.

[0386] Examples of sulfosuccinic acid alkyl esters and salts thereof include sulfosuccinic acid alkyl esters represented by the general formula: R ２１ -OCOCH(SO ３ A ２１ ) CH ２ COO-R ２２ (In the formula, R ２１ and R ２２ are the same or different and represent an alkyl group having 4 to 12 carbon atoms; A ２１ is an alkali metal, alkaline earth metal or NH ４ and alkyl sulfosuccinates represented by the following formula (I):

[0387] R ２１ and R ２２Examples of the alkyl group include linear or branched alkyl groups such as n-butyl, iso-butyl, sec-butyl, n-pentyl, iso-pentyl, neopentyl, tert-pentyl, n-hexyl, iso-hexyl, tert-hexyl, n-heptyl, iso-heptyl, tert-heptyl, n-octyl, iso-octyl, tert-octyl, n-nonyl, iso-nonyl, tert-nonyl, n-decyl, and 2-ethylhexyl.

[0388] A ２１ Examples include Na, NH ４ Examples of the alkyl sulfosuccinate include di-n-octyl sulfosuccinate and di-2-ethylhexyl sulfosuccinate.

[0389] The fluorine-free anionic surfactant may have an acid group. The acid group is preferably selected from the group consisting of a carboxyl group, a sulfate group, a sulfonic acid group, a phosphate group, and salts thereof, and more preferably selected from the group consisting of a carboxyl group, a sulfate group, a sulfonic acid group, and salts thereof.

[0390] The fluorine-free anionic surfactant may have, in addition to the acid group, other groups such as a polyoxyalkylene group having an oxyalkylene group having 2 to 4 carbon atoms, an amino group, etc. The amino group is not protonated.

[0391] As the fluorine-free anionic surfactant, an anionic hydrocarbon surfactant having a hydrocarbon as the main chain is preferred. Examples of hydrocarbons include those having a saturated or unsaturated aliphatic chain having 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms. The saturated or unsaturated aliphatic chain may be either a straight chain or a 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.

[0392] Examples of fluorine-free anionic surfactants include alkyl sulfonic acids such as lauryl sulfonic acid and salts thereof; alkylaryl sulfates and salts thereof; aliphatic (carboxylic) acids such as lauric acid and salts thereof; alkyl phosphates, alkylaryl phosphates, and salts thereof; and the like. Among these, preferred are those selected from the group consisting of sulfonic acids, carboxylic acids, and salts thereof, and more preferred are aliphatic carboxylic acids or salts thereof. Examples of the aliphatic carboxylic acids or salts thereof include saturated or unsaturated aliphatic carboxylic acids having 9 to 13 carbon atoms, in which the terminal H may be replaced with —OH, or salts thereof. Preferred examples of the aliphatic carboxylic acids or salts thereof include monocarboxylic acids, and preferred examples of the monocarboxylic acids include decanoic acid, undecanoic acid, undecenoic acid, lauric acid, and hydroxydodecanoic acid.

[0393] The fluorine-free anionic surfactant is preferably at least one selected from the group consisting of alkyl sulfosuccinates and salts thereof, alkyl sulfates and salts thereof, and monocarboxylic acids and salts thereof, more preferably at least one selected from the group consisting of dioctyl sulfosuccinate, lauryl sulfate, decanoic acid and salts thereof, and even more preferably at least one selected from the group consisting of dioctyl sulfosuccinate, ammonium dioctyl sulfosuccinate, ammonium lauryl sulfate, and ammonium decanoate.

[0394] The viscosity of the aqueous fluoropolymer dispersion of the present disclosure is preferably 2.0 mPa·s or more, more preferably 5.0 mPa·s or more, even more preferably 10.0 mPa·s or more, particularly preferably 15.0 mPa·s or more, and is preferably 100 mPa·s or less, more preferably 80 mPa·s or less, even more preferably 70 mPa·s or less, and still more preferably 60 mPa·s or less.

[0395] The viscosity of the aqueous dispersion is measured using a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 1) at a rotation speed of 60 rpm, a measurement time of 120 seconds, and at 25°C.

[0396] The aqueous fluoropolymer dispersion of the present disclosure also preferably contains a preservative. The content of the preservative in the aqueous fluoropolymer dispersion is preferably 0.01 to 0.5% by mass, more preferably 0.05% by mass or more, and more preferably 0.2% by mass or less, based on the fluoropolymer.

[0397] Examples of preservatives include isothiazolones, azoles, pronopol, chlorothalonil, methylsulfonyltetrachloropyrrolidin, carbentazim, fluorophorbet, sodium diacetate, and diiodomethyl-paratolylsulfone.

[0398] The aqueous fluoropolymer dispersion of the present disclosure may contain other components. Examples of the other components include water-soluble polymer compounds. Examples of the water-soluble polymer compounds include methyl cellulose, alumina sol, polyvinyl alcohol, carboxylated vinyl polymer, 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, and polyurethane resin.

[0399] The aqueous fluoropolymer dispersion of the present disclosure can be used as an aqueous coating material by blending it with known compounding agents such as pigments, thickeners, dispersants, antifoaming agents, antifreezing agents, and film-forming aids, or by further combining it with other polymer compounds.

[0400] Next, the fluoropolymer in the aqueous dispersion obtained by the production method of the present disclosure and the fluoropolymer in the aqueous dispersion of the present disclosure will be described in more detail.

[0401] (Fluoropolymer) Fluoropolymers such as fluororesins and fluororubbers can be obtained by polymerization of fluoromonomers.

[0402] Examples of the fluoropolymer include a TFE polymer in which the monomer having the largest molar fraction in the polymer (hereinafter referred to as the "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.

[0403] 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.

[0404] The fluoropolymer is preferably a fluoropolymer different from the polymer compound (I) having an ionic group. In one embodiment, the fluoropolymer does not have any ionic groups.

[0405] 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.

[0406] 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.

[0407] 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.

[0408] 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.

[0409] 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.

[0410] 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.

[0411] In the production method of the present disclosure, it is preferable to produce a fluororesin as the fluoropolymer. The aqueous fluoropolymer dispersion of the present disclosure preferably contains a fluororesin as the fluoropolymer.

[0412] In the production method of the present disclosure, for example, (I) a tetrafluoroethylene polymer [TFE polymer (PTFE)] can be suitably produced as a non-melt-processable fluororesin, and (II) an ethylene / TFE copolymer [ETFE], a TFE / HFP copolymer [FEP], a TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], a TFE / perfluoroallyl ether copolymer, a TFE / VDF copolymer, or an electrolyte polymer precursor can be suitably produced as a melt-processable fluororesin.

[0413] 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

[0414] The perfluororesin is more preferably a fluororesin having a fluorine substitution rate of 95 to 100%, further preferably polytetrafluoroethylene (PTFE), FEP or PFA, still more preferably PTFE or PFA, and particularly preferably PTFE.

[0415] 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.

[0416] 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

[0417] 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.

[0418] 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.

[0419] 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.

[0420] The fluoropolymer having the core-shell structure also includes a particle of the fluoropolymer having multiple cores.

[0421] The above-mentioned (I) non-melt-processible fluororesin and (II) melt-processible fluororesin, which are preferably produced by the production method of the present disclosure, are preferably produced in the following manner.

[0422] (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.

[0423] 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.

[0424] 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").

[0425] 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.

[0426] 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 Ｑ１represents 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.

[0427] 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] 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.

[0432] 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:

[0433]

[0434] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0435] CF ３ CF ２ CF ２ -(O-CF(CF ３ )-CF ２ ) ｎ - (wherein n represents an integer of 1 to 4).

[0436] 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.

[0437] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0438] Examples of perfluoroallyl ethers include those represented by the general formula: CF ２ =CF-CF ２Examples of the fluoromonomer include those represented by —ORf (wherein Rf represents a perfluoroorganic group).

[0439] 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-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 preferred.

[0440] 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.

[0441] 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.

[0442] 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.

[0443] 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.)

[0444] (In the formula, X ３ and X ４ is F, Cl or a methoxy group, and Y is of formula Y1 or Y2.

[0445] (In formula Y2, Z and Z′ are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0446] 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.

[0447] 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.

[0448] 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%.

[0449] 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)").

[0450] 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.

[0451] 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.

[0452] 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.

[0453] 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.

[0454] 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.

[0455] 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.

[0456] 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.

[0457] 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.

[0458] In the polymerization, a compound having an unsaturated bond can be used as the modifying monomer (A).

[0459] 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.

[0460] 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.

[0461] 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.

[0462] 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.

[0463] 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 exemplified. Among them, the above R ａ is specifically, -CF ２ -O-, -CF ２ -O-CF ２ -, -CF ２ -O-CF ２ CF ２ -, -CF 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.

[0464] -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.

[0465] 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.

[0466] 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.

[0467] -R in general formula (4) ａ - (CZ １ Z ２ ) ｋ - also includes 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:

[0468] 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.

[0469] 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.

[0470] 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.

[0471] 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).

[0472] 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((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(CF 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.

[0473] 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), CF ２=CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M), CH ２ =CH(CF 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((CF ２ ) ４ SO ３ M), CH ２ =CH((CF ２ ) ３ SO ３ In the above formula, M is the same as above.

[0474] 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(CF ２ CF ２ COOM), CH ２ =CH((CF ２) ４ COOM), CH ２ =CH((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(CF 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((CF ２ ) ４ SO ２ NR'CH ２ COOM), CH ２ =CH((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.

[0475] In the general formula (4), Y ３ Ha-OPO３ 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(CF ２ CF ２ CH ２ OP (O) (OM) ２ , C.H. ２ =CH((CF ２ ) ４ CH ２ OP (O) (OM)２ ), C.H. ２ =CH((CF ２ ) ３ CH ２ OP (O) (OM) ２ In the above formula, M is the same as above.

[0476] 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(CF ２ CF ２ P(O)(OM) ２ ), C.H. ２ =CH((CF ２ ) ４ P(O)(OM) ２ ), C.H. ２ =CH((CF ２ ) ３ P(O)(OM) ２ ) and the like, in which M is the same as above.

[0477] 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.

[0478] 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.

[0479] 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.

[0480] 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.

[0481] 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.

[0482] 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.

[0483] 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.

[0484] 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.

[0485] 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.)

[0486] Specific examples of the compound represented by general formula (5a) include compounds represented by the following formula:

[0487]

[0488] (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:

[0489]

[0490] Among them,

[0491]

[0492] It is preferable that:

[0493] 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.

[0494] 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.)

[0495] 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:

[0496] 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).

[0497] Further, examples of the compound represented by the general formula (5) include a compound represented by the general formula (5c).

[0498] CF ２ =CFCF ２ -O-Rf-Y ３ (5c) (wherein Rf and Y ３ is the same as above)

[0499] More specifically, etc.

[0500] 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.

[0501] 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.

[0502] 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.

[0503] 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.

[0504] 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.

[0505] 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.)

[0506] 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 unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0507] 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).

[0508] 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 unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0509] 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:

[0510] 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:

[0511] 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.

[0512] 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:

[0513] 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.

[0514] 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.

[0515] 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.

[0516] 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 unlikely 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).

[0517] 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 unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0518] 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).

[0519] 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%.

[0520] According to purpose, the aqueous dispersion of TFE polymer can also be preferably used as the composition that organic or inorganic filler is added to in various applications.By coating above-mentioned composition on the substrate that is made of metal or ceramic, it can make the coating surface that has 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., the impregnation processing of glass cloth, etc.

[0521] 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.

[0522] The aqueous dispersion of above-mentioned TFE polymer is also preferably used as processing aid.When used as processing aid, by mixing the aqueous dispersion 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.

[0523] The aqueous dispersion of the TFE polymer is also preferably used as a binder for batteries and for dust prevention purposes.

[0524] The aqueous dispersion 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 is suitable as a raw material for the PTFE described in, for example, JP-A-11-49912, U.S. Pat. No. 5,804,654, JP-A-11-29679, and JP-A-2003-2980.The processing aid using the aqueous dispersion is in no way inferior to the processing aids described in the above publications.

[0525] 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.

[0526] 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.

[0527] 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.

[0528] 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.

[0529] 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.

[0530] 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.

[0531] 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.).

[0532] 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).

[0533] Furthermore, low-molecular-weight PTFE may be obtained by polymerizing TFE or a monomer copolymerizable with TFE with TFE in the presence of a chain transfer agent. 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.

[0534] 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.

[0535] 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.

[0536] 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.

[0537] 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.

[0538] 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.

[0539] 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.

[0540] 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.

[0541] 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.

[0542] 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.

[0543] The average primary particle diameter of the primary particles of low molecular weight PTFE is preferably 10-300 nm, more preferably 50 nm or more, even more preferably 100 nm or more, still more preferably 150 nm or more, and 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.

[0544] 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.

[0545] The average primary particle diameter can also be measured by the following method. The dispersion is diluted with water to a solid content of 0.15% by mass, and the transmittance of 550 nm incident light per unit length of the diluted latex obtained and the number-average particle diameter determined by measuring the unidirectional diameter using a transmission electron microscope photograph are measured to prepare a calibration curve. Using this calibration curve, the average particle diameter can be calculated from the measured transmittance of 550 nm incident light of each sample.

[0546] 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.

[0547] (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.

[0548] The monomer composition (mass %) of FEP is preferably TFE:HFP=(60-95):(5-40), more preferably (85-92):(8-15).

[0549] 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 fluoromonomers (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.

[0550] 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.

[0551] (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.

[0552] 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 (wherein, Rf ４ is a perfluoroalkyl group having 1 to 6 carbon atoms).

[0553] 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 fluoromonomers (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.

[0554] 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 (wherein, Rf ４ is a perfluoroalkyl group having 1 to 6 carbon atoms).

[0555] 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 fluoromonomers (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.

[0556] 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.

[0557] 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.

[0558] (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.

[0559] The preferred monomer composition (mol %) of ETFE is TFE:ethylene=(50 to 99):(50 to 1).

[0560] 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 fluoromonomers (but excluding TFE) and non-fluorine-containing monomers (but excluding ethylene).As other monomers, one or more kinds can be used.

[0561] 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.

[0562] 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).

[0563] 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.

[0564] (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 (X１５１ , 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.

[0565] 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 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. ) Examples of the monomer used for the electrolyte polymer precursor include a compound containing two fluorosulfonyl groups described in WO 2007 / 013532, and -SO ２ Examples 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).

[0566] 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.

[0567] 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.

[0568] (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.

[0569] 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).

[0570] 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.

[0571] 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.

[0572] 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.

[0573] 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.

[0574] <1> According to a first aspect of the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, the method comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant to prepare an aqueous dispersion (E) containing: a phase (E1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E1) and the nonionic surfactant content is less than 2.00 mass% relative to the mass of phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (E2) and the nonionic surfactant content is 2.00 mass% or more relative to the mass of phase (E2); and a phase (E3) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of phase (E3) and the nonionic surfactant content is 2.00 mass% or more relative to the mass of phase (E3). <2> According to a second aspect of the present disclosure, there is provided a production method according to the first aspect for preparing an aqueous dispersion containing, as the aqueous dispersion (E), a phase (E1) in which the content of the fluoropolymer is less than 1.00% by mass relative to the mass of the phase (E1) and the content of the nonionic surfactant is less than 2.00% by mass relative to the mass of the phase (E1), a phase (E2) in which the content of the fluoropolymer is less than 1.00% by mass relative to the mass of the phase (E2) and the content of the nonionic surfactant is 20.00% by mass or more relative to the mass of the phase (E2), and a phase (E3) in which the content of the fluoropolymer is 30.00% by mass or more relative to the mass of the phase (E3), and the content of the nonionic surfactant is 2.00% by mass or more relative to the mass of the phase (E3).<3> According to a third aspect of the present disclosure, an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant is heated to a first temperature range that is less than a temperature 10°C higher than the cloud point of the nonionic surfactant and is 35°C or higher, and the temperature of the heated aqueous dispersion (C) is maintained within the first temperature range for 5 minutes or longer, thereby preparing an aqueous dispersion (D) containing: a phase (D1) in which the fluoropolymer content is less than 1.00% by mass, relative to the mass of phase (D1), and the nonionic surfactant content is 5.00% by mass or more, relative to the mass of phase (D1); and a phase (D2) in which the fluoropolymer content is 1.00% by mass or more, relative to the mass of phase (D2), and the nonionic surfactant content is less than 5.00% by mass, relative to the mass of phase (D2); The first or second aspect provides a production method comprising: heating aqueous dispersion (D) to a second temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (D) within the second temperature range for 5 minutes or more, thereby preparing aqueous dispersion (E) containing phases (E1) to (E3); and recovering phase (E3) from aqueous dispersion (E) containing phases (E1) to (E3).<4> According to a fourth aspect of the present disclosure, an aqueous dispersion (D) containing a fluoropolymer, a nonionic surfactant, and a fluorinated surfactant is contacted with an ion exchange resin to recover an aqueous dispersion (C), and the aqueous dispersion (C) is heated to a first temperature range that is less than a temperature 10°C higher than the cloud point of the nonionic surfactant and not less than 35°C, and the temperature of the heated aqueous dispersion (C) is maintained within the first temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (D) containing: a phase (D1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (D1) and the nonionic surfactant content is 5.00 mass% or more relative to the mass of phase (D1); and a phase (D2) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of phase (D2) and the nonionic surfactant content is less than 5.00 mass% relative to the mass of phase (D2), The present invention provides a production method according to any one of the first to third aspects, which comprises heating aqueous dispersion (D) to a second temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (D) within the second temperature range for 5 minutes or more, thereby preparing aqueous dispersion (E) containing phases (E1) to (E3); and recovering phase (E3) from aqueous dispersion (E) containing phases (E1) to (E3).<5> According to a fifth aspect of the present disclosure, an aqueous dispersion (E) containing phases (E1) to (E3) is prepared by heating an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant to a third temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (C) in the third temperature range for 5 minutes or more, and then stirring the aqueous dispersion (E) until the boundaries between the phases disappear, thereby preparing an aqueous dispersion (F); and adjusting the temperature of the aqueous dispersion (F) to a fourth temperature range that is less than a temperature that is at least 10°C higher than the cloud point of the nonionic surfactant and is at least 35°C, and maintaining the temperature of the aqueous dispersion (F) in the fourth temperature range for 5 minutes or more, thereby producing a phase (G1) in which the fluoropolymer content is less than 1.00% by mass, relative to the mass of the phase (G1), and the nonionic surfactant content is 5.00% by mass or more, relative to the mass of the phase (G1). The present invention provides a production method according to the first or second aspect, which comprises preparing an aqueous dispersion (G) containing a phase (G2), wherein the content of the fluoropolymer is 1.00% by mass or more, based on the mass of the phase (G2), and the content of the nonionic surfactant is less than 5.00% by mass, based on the mass of the phase (G2); and recovering the phase (G2) from the aqueous dispersion (G) containing the phases (G1) to (G2).<6> According to a sixth aspect of the present disclosure, a method for producing a dispersion liquid (F) comprising: contacting an aqueous dispersion (B) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant with an ion exchange resin to recover an aqueous dispersion (C); heating the aqueous dispersion (C) to a third temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (C) in the third temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (E) containing phases (E1) to (E3); next, stirring the aqueous dispersion (E) until the boundaries between the phases disappear, thereby preparing an aqueous dispersion (F); adjusting the temperature of the aqueous dispersion (F) to a fourth temperature range that is less than a temperature that is at least 10°C higher than the cloud point of the nonionic surfactant and is at least 35°C, and maintaining the temperature of the aqueous dispersion (F) in the fourth temperature range for 5 minutes or more, thereby producing a dispersion liquid (F) comprising phases (E1) to (E3). A production method according to the first, second or fifth aspect is provided, which comprises preparing an aqueous dispersion (G) containing: a phase (G1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (G1) and a nonionic surfactant content of 5.00 mass% or more relative to the mass of phase (G1); and a phase (G2) having a fluoropolymer content of 1.00 mass% or more relative to the mass of phase (G2) and a nonionic surfactant content of less than 5.00 mass% relative to the mass of phase (G2), and recovering phase (G2) from aqueous dispersion (G) containing phases (G1) to (G2). <7> According to a seventh aspect of the present disclosure, there is provided a production method according to the fourth or sixth aspect, which comprises recovering aqueous dispersion (C), adding a nonionic surfactant to aqueous dispersion (C), and then heating aqueous dispersion (C). <8> According to an eighth aspect of the present disclosure, there is provided a production method according to the fourth or sixth aspect, comprising: preparing an aqueous dispersion (A) containing a fluoropolymer by polymerizing a fluoromonomer in the presence of a fluorinated surfactant, a polymerization initiator, and an aqueous medium; and preparing an aqueous dispersion (B) containing the fluoropolymer, the nonionic surfactant, and the fluorinated surfactant by adding a nonionic surfactant to the aqueous dispersion (A).<9> According to a ninth aspect of the present disclosure, there is provided the production method according to the eighth aspect, in which the content of the fluorinated surfactant in phase (E3) or phase (G2) is reduced to an amount equivalent to 0.001 mass % or less of the content of the fluorinated surfactant contained in the aqueous dispersion (A). <10> According to a tenth aspect of the present disclosure, there is provided the production method according to any of the first to ninth aspects, in which phase (E3) or phase (G2) is recovered, and then a nonionic surfactant is added to the recovered phase. <11> According to an eleventh aspect of the present disclosure, there is provided a production method according to any of the third to ninth aspects, wherein the aqueous dispersion (C) contains a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant, the fluoropolymer is polytetrafluoroethylene, and the content of the polytetrafluoroethylene is 20.0 to 35.0 mass% relative to the mass of the aqueous dispersion (C), the cloud point of the nonionic surfactant is 40 to 80°C, and the content of the nonionic surfactant is 2.00 to 10.0 mass% relative to the mass of the aqueous dispersion (C), and the fluorine-containing surfactant is an anionic fluorine-containing surfactant having a Log POW of 3.5 or less, and the content of the fluorine-containing surfactant is 100 ppb by mass or more and 3000 ppm by mass or less relative to the mass of the aqueous dispersion (C). <12> According to a twelfth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion containing a fluoropolymer and an anionic fluorinated surfactant, wherein the content of the anionic fluorinated surfactant is more than 0 ppb by mass and less than 100 ppb by mass relative to the fluoropolymer. <13> According to a thirteenth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion containing a fluoropolymer and an anionic fluorinated surfactant, the content of the anionic fluorinated surfactant being more than 0 ppb by mass and less than 100 ppb by mass relative to the fluoropolymer. 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 F７ 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 ２ OCF (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, and (In each formula, M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. ７is H or an organic group.) is provided an aqueous fluoropolymer dispersion according to a twelfth aspect, in which the anionic fluorine-containing surfactant has a LogPOW of 3.5 or less. <14> According to a fourteenth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion according to the twelfth or thirteenth aspect, in which the anionic fluorine-containing surfactant has a LogPOW of 3.5 or less. <15> According to a fifteenth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion according to any of the twelfth to fourteenth aspects, further comprising a nonionic surfactant, the content of the nonionic surfactant being 4.0 to 12.0 mass% based on the fluoropolymer. <16> According to a sixteenth aspect of the present disclosure, there is provided an aqueous fluoropolymer dispersion according to the fifteenth aspect, in which the nonionic surfactant is represented by general formula (i). 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 １is a polyoxyalkylene chain.) <17> According to a seventeenth aspect of the present disclosure, there is provided the aqueous fluoropolymer dispersion according to the fifteenth or sixteenth aspect, wherein the cloud point of the nonionic surfactant is 40 to 80° C. <18> According to an eighteenth aspect of the present disclosure, there is provided the aqueous fluoropolymer dispersion according to any one of the twelfth to seventeenth aspects, wherein the fluoropolymer is polytetrafluoroethylene. <19> According to a nineteenth aspect of the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion having a reduced content of a polymer compound (I) having an ionic group, the method comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and the polymer compound (I) having an ionic group to prepare an aqueous dispersion (E) containing: a phase (E1) in which the content of the fluoropolymer is less than 1.00 mass% relative to the mass of the phase (E1), and the content of the nonionic surfactant is less than 2.00 mass% relative to the mass of the phase (E1); a phase (E2) in which the content of the fluoropolymer is less than 1.00 mass% relative to the mass of the phase (E2), and the content of the nonionic surfactant is 2.00 mass% or more relative to the mass of the phase (E2); and a phase (E3) in which the content of the fluoropolymer is 1.00 mass% or more relative to the mass of the phase (E3), and the content of the nonionic surfactant is 2.00 mass% or more relative to the mass of the phase (E3). A method for producing an aqueous fluoropolymer dispersion is provided. <20> According to a twentieth aspect of the present disclosure, there is provided a production method according to a nineteenth aspect, in which the polymer compound (I) having an ionic group 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; A０ 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.

[0575] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0576] (1) Solid content concentration (P) Approximately 1 g (X g) of a sample was placed in an aluminum cup with a diameter of 5 cm, heated at 110°C for 30 minutes, and further heated at 300°C for 30 minutes. Based on the heating residue (Z g), P was determined using the formula: P = Z / X × 100 (mass%).

[0577] (2) Average primary particle size The PTFE aqueous dispersion was diluted with water to a solid content of 0.15% by mass, and the transmittance of the 550 nm incident light per unit length of the diluted aqueous dispersion was measured, and the number-based average primary particle size was determined by measuring the unidirectional diameter using a transmission electron microscope photograph, to create a calibration curve. Using this calibration curve, the average primary particle size was determined from the measured transmittance of the 550 nm incident light of each sample.

[0578] (3) pH Using a glass electrode (manufactured by Horiba, Ltd.), the pH at 25° C. was measured in accordance with JIS K6893.

[0579] (4) Nonionic surfactant content (N) Approximately 1 g (X g) of a sample was placed in an aluminum cup having a diameter of 5 cm and heated at 110°C for 30 minutes to obtain a heating residue (Y g). The heating residue (Y g) was then further heated at 300°C for 30 minutes to obtain a heating residue (Z g). The nonionic surfactant content (N) was calculated from the formula: N = [(Y - Z) / Z] x 100 (mass%).

[0580] (5) Measurement of Fluorine-Containing Surfactant Content 5.0 g of the aqueous dispersion was weighed out, 10 g of methanol was added, and the mixture was poured into a cylindrical filter paper. Soxhlet extraction was performed so that the total amount of methanol used as the extraction solvent became 150 g, and the resulting extract was made up to volume with methanol to 250 ml, thereby obtaining an extract containing a fluorine-containing surfactant.

[0581] Five levels of methanol standard solutions of fluorine-containing surfactants with known concentrations ranging from 0.1 to 100 ng / mL were prepared, and measurements were carried out using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). A calibration curve was created using a first-order approximation from each sample concentration and peak integral value.

[0582] The content of the fluorine-containing surfactant was measured using a liquid chromatograph mass spectrometer. The peak area of ​​the fluorine-containing surfactant was determined for the extract by MRM, and the content of the fluorine-containing surfactant contained in the aqueous dispersion was determined. The quantification limit was 5 mass ppb. The content of perfluoroethercarboxylic acid D was determined by converting it to perfluorooctanoic acid using perfluorooctanoic acid as a standard substance.

[0583] Measurement equipment configuration and LC-MS measurement conditions

[0584] MRM measurement parameters

[0585] (6) Viscosity The viscosity was measured at 25° C. using a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 1) at a rotation speed of 60 rpm for a measurement time of 120 seconds.

[0586] (7) Content of polymer compound (I) in aqueous PTFE dispersion The content of polymer compound (I) relative to PTFE in the aqueous PTFE dispersion obtained in the production example (T Ａ The T mass % was calculated using the following formula from the mass of water added to the reactor in the production example, the mass of polymer compound (I), and the PTFE solids concentration in the resulting PTFE aqueous dispersion. Ａ =W Ｄ / [(W Ｗ ×P Ａ / 100) / (1-P Ａ / 100)]×100 (mass%) W Ｗ (g): Mass of water added to the reactor W Ｄ (g): Mass of polymer compound (I) added to the reactor P Ａ (mass%): PTFE solids concentration in PTFE aqueous dispersion

[0587] (8) Content of polymer compound (I) in the upper supernatant phase A predetermined amount of sodium trifluoroacetate is added to the upper supernatant phase, １９ F NMR measurement was carried out. From the peak area values ​​of sodium trifluoroacetate and polymer compound (I), the content of polymer compound (I) in the upper supernatant phase (T Ｓ The mass % was calculated.

[0588] (9) Content of polymer compound (I) in PTFE aqueous dispersion The content of polymer compound (I) relative to PTFE in the PTFE aqueous dispersion obtained in the experimental example (T Ｄ The mass % was calculated by the following formula: Ｄ =T Ａ -W Ｓ ×T Ｓ / W Ａ T Ａ (mass %): the content of polymer compound (I) relative to PTFE in the aqueous PTFE dispersion obtained in each production example Ｓ (mass%): content of polymer compound (I) D in the upper supernatant phase W Ｓ (g): Mass of upper supernatant phase W Ａ (g): Mass of PTFE in the aqueous dispersion before concentration (i.e., mass of PTFE in the concentrated phase)

[0589] <Static Surface Tension of Nonionic Surfactant> A 0.1% by mass aqueous solution of a nonionic surfactant was prepared, and the surface tension of the obtained aqueous solution was measured at 25°C by the Wilhelmy method using a surface tensiometer DY-300 manufactured by Kyowa Interface Science Co., Ltd.

[0590] The following fluorine-containing surfactants were prepared.

[0591] Perfluoroether carboxylic acid A ammonium salt: Ammonium perfluoro(2-methyl-3-oxahexanoate), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., structural formula: CF ３ CF ２ CF ２ OCF (CF ３ ) COONH ４

[0592] Perfluoroether carboxylic acid B ammonium salt: Ammonium perfluoro-3,6-dioxaoctanoate, structural formula: CF ３ CF ２ OCF ２ CF ２ OCF ２ COONH ４ Perfluoroethercarboxylic acid B was purchased from Apollo Scientific Ltd. and converted into an ammonium salt.

[0593] Perfluoroether carboxylic acid C ammonium salt: Ammonium 2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-(trifluoromethoxy)propoxy]-propionate, structural formula: CF ３ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４

[0594] Perfluoroether carboxylic acid D ammonium salt: Ammonium perfluoro (2,5-dimethyl-3,6-dioxaoctanoate), structural formula: CF ３ CF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４

[0595] Perfluoroether carboxylic acid E ammonium salt: Ammonium 2,3,3,3-tetrafluoro-2-{1,1,2,3,3,3-hexafluoro-2-(heptafluoropropoxy)propoxy}propanoate, structural formula: CF ３ CF ２ CF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４

[0596] The following nonionic surfactants were prepared: Surfactant (a): C １３ H ２７ O (CH ２ CH ２ O) ８ H, cloud point 60°C (HLB value 13.3, static surface tension 27.5 mN / m) Surfactant (b): C １３ H ２７ O (CH ２ CH ２ O) ９ H, cloud point 56°C (HLB value 13.3, static surface tension 27.5mN / m)

[0597] The polymer compound (I) used in the experimental examples is as follows: Polymer H: Formula: CH ２ =CF(CF ２ OCFCF ３ COOH) (number average molecular weight 12.2 × 10 ４ , weight average molecular weight 46.0×10 ４ The number average molecular weight and weight average molecular weight were measured by gel permeation chromatography (GPC) using a GPC HLC-8020 manufactured by Tosoh Corporation and Shodex columns (one GPC KF-801, one GPC KF-802, and two GPC KF-806M columns connected in series) using tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as a standard.

[0598] Production Example 1 A PTFE aqueous dispersion (1A) was obtained according to Production Example 1 described in International Publication No. 2023 / 054723. The average primary particle diameter of the obtained PTFE aqueous dispersion (1A) was 295 nm, the solid content was 26.5 mass%, and the content of perfluoroethercarboxylic acid A was 12,372 mass ppm relative to PTFE.

[0599] Comparative Example 1: To the PTFE aqueous dispersion (1A) obtained in Production Example 1, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PTFE to prepare an aqueous PTFE dispersion (1B). Subsequently, a 20 mm diameter column was filled with 250 ml of OH-type anion exchange resin (trade name Amberjet AMJ4002, manufactured by Rohm and Haas), and the dispersion was passed through at SV = 1. To the obtained aqueous PTFE dispersion, surfactant (a) was added in an amount of 18 parts by mass per 100 parts by mass of PTFE to obtain an aqueous PTFE dispersion (1C). The solids concentration of the aqueous PTFE dispersion (1C) was 25.1 mass%, the content of the nonionic surfactant relative to PTFE was 17.9 mass%, the pH was 9.70, and the content of perfluoroethercarboxylic acid A relative to PTFE was 2,417 ppb by mass.

[0600] The aqueous PTFE dispersion (1C) was maintained at 63°C for 1 hour to obtain an aqueous PTFE dispersion (1D) containing two phases (D1, D2). The solids concentration of phase (D1) was 0.04% by mass relative to the mass of phase (D1), and the nonionic surfactant content was 10.2% by mass relative...

Claims

1. A method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant to prepare an aqueous dispersion (E) containing: a phase (E1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (E1) and a nonionic surfactant content of less than 2.00 mass% relative to the mass of phase (E1); a phase (E2) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (E2) and a nonionic surfactant content of 2.00 mass% or more relative to the mass of phase (E2); and a phase (E3) having a fluoropolymer content of 1.00 mass% or more relative to the mass of phase (E3) and a nonionic surfactant content of 2.00 mass% or more relative to the mass of phase (E3).

2. The method according to claim 1, comprising preparing an aqueous dispersion containing: a phase (E1) in which the fluoropolymer content is less than 1.00% by mass relative to the mass of the phase (E1) and the nonionic surfactant content is less than 2.00% by mass relative to the mass of the phase (E1); a phase (E2) in which the fluoropolymer content is less than 1.00% by mass relative to the mass of the phase (E2) and the nonionic surfactant content is 20.00% by mass or more relative to the mass of the phase (E2); and a phase (E3) in which the fluoropolymer content is 30.00% by mass or more relative to the mass of the phase (E3) and the nonionic surfactant content is 2.00% by mass or more relative to the mass of the phase (E3).

3. Heating an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant to a first temperature range that is less than 10°C higher than the cloud point of the nonionic surfactant and is 35°C or higher, and maintaining the temperature of the heated aqueous dispersion (C) within the first temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (D) containing: a phase (D1) in which the fluoropolymer content is less than 1.00 mass% relative to the mass of phase (D1) and the nonionic surfactant content is 5.00 mass% or more relative to the mass of phase (D1); and a phase (D2) in which the fluoropolymer content is 1.00 mass% or more relative to the mass of phase (D2), and the nonionic surfactant content is less than 5.00 mass% relative to the mass of phase (D2); 3. The method according to claim 1 or 2, further comprising: heating aqueous dispersion (D) to a second temperature range that is at least 10° C. higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (D) within the second temperature range for 5 minutes or more, thereby preparing aqueous dispersion (E) containing phases (E1) to (E3); and recovering phase (E3) from aqueous dispersion (E) containing phases (E1) to (E3).

4. Contacting an aqueous dispersion (B) containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant with an ion exchange resin to recover an aqueous dispersion (C); heating the aqueous dispersion (C) to a first temperature range that is less than 10°C higher than the cloud point of the nonionic surfactant and not less than 35°C; and maintaining the temperature of the heated aqueous dispersion (C) within the first temperature range for 5 minutes or more to prepare an aqueous dispersion (D) containing: a phase (D1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (D1) and a nonionic surfactant content of 5.00 mass% or more relative to the mass of phase (D1); and a phase (D2) having a fluoropolymer content of 1.00 mass% or more relative to the mass of phase (D2), and a nonionic surfactant content of less than 5.00 mass% relative to the mass of phase (D2); 4. The method according to claim 1, further comprising: heating aqueous dispersion (D) to a second temperature range that is at least 10° C. higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (D) within the second temperature range for 5 minutes or more, thereby preparing aqueous dispersion (E) containing phases (E1) to (E3); and recovering phase (E3) from aqueous dispersion (E) containing phases (E1) to (E3).

5. An aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant is heated to a third temperature range that is equal to or higher than the cloud point of the nonionic surfactant, and the temperature of the heated aqueous dispersion (C) is maintained within the third temperature range for 5 minutes or more to prepare an aqueous dispersion (E) containing phases (E1) to (E3); next, the aqueous dispersion (E) is stirred until the boundaries between the phases disappear to prepare an aqueous dispersion (F); and the temperature of the aqueous dispersion (F) is adjusted to a fourth temperature range that is lower than a temperature that is higher than the cloud point of the nonionic surfactant and is equal to or higher than 35°C, and the temperature of the aqueous dispersion (F) is maintained within the fourth temperature range for 5 minutes or more to prepare a phase (G1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of the phase (G1), and a nonionic surfactant content of 5.00 mass% or more relative to the mass of the phase (G1); 3. The method according to claim 1, further comprising the steps of: preparing an aqueous dispersion (G) containing a phase (G2) in which the content of the fluoropolymer is 1.00 mass% or more, and the content of the nonionic surfactant is less than 5.00 mass% based on the mass of the phase (G2); and recovering the phase (G2) from the aqueous dispersion (G) containing the phases (G1) to (G2).

6. A method for producing a dispersion (B) containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant, by contacting the aqueous dispersion (B) with an ion exchange resin and recovering an aqueous dispersion (C); heating the aqueous dispersion (C) to a third temperature range that is at least 10°C higher than the cloud point of the nonionic surfactant, and maintaining the temperature of the heated aqueous dispersion (C) within the third temperature range for 5 minutes or more, thereby preparing an aqueous dispersion (E) containing phases (E1) to (E3); next, stirring the aqueous dispersion (E) until the boundaries between the phases disappear, thereby preparing an aqueous dispersion (F); adjusting the temperature of the aqueous dispersion (F) to a fourth temperature range that is less than a temperature 10°C higher than the cloud point of the nonionic surfactant and at least 35°C, and maintaining the temperature of the aqueous dispersion (F) within the fourth temperature range for 5 minutes or more, thereby The method according to claim 1, 2 or 5, comprising: preparing an aqueous dispersion (G) containing: a phase (G1) in which the content of the fluoropolymer is less than 1.00% by mass relative to the mass of the phase (G1), and the content of the nonionic surfactant is 5.00% by mass or more relative to the mass of the phase (G1); a phase (G2) in which the content of the fluoropolymer is 1.00% by mass or more relative to the mass of the phase (G2), and the content of the nonionic surfactant is less than 5.00% by mass relative to the mass of the phase (G2); and recovering the phase (G2) from the aqueous dispersion (G) containing the phases (G1) to (G2).

7. The method according to claim 4 or 6, further comprising recovering the aqueous dispersion (C), adding a nonionic surfactant to the aqueous dispersion (C), and then heating the aqueous dispersion (C).

8. The method according to claim 4 or 6, comprising the steps of: preparing an aqueous dispersion (A) containing a fluoropolymer by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant, a polymerization initiator and an aqueous medium; and preparing an aqueous dispersion (B) containing the fluoropolymer, the nonionic surfactant and the fluorine-containing surfactant by adding a nonionic surfactant to the aqueous dispersion (A).

9. The production method according to claim 8, wherein the content of the fluorine-containing surfactant in phase (E3) or phase (G2) is reduced to an amount equivalent to 0.001 mass% or less of the content of the fluorine-containing surfactant contained in the aqueous dispersion (A).

10. The method according to any one of claims 1 to 9, wherein after phase (E3) or phase (G2) is recovered, a nonionic surfactant is added to the recovered phase.

11. The method according to any one of claims 3 to 9, wherein the aqueous dispersion (C) contains a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant, the fluoropolymer is polytetrafluoroethylene, and the content of the polytetrafluoroethylene is 20.0 to 35.0 mass% based on the mass of the aqueous dispersion (C), the cloud point of the nonionic surfactant is 40 to 80°C and the content of the nonionic surfactant is 2.00 to 10.0 mass% based on the mass of the aqueous dispersion (C), and the fluorine-containing surfactant is an anionic fluorine-containing surfactant having a Log POW of 3.5 or less, and the content of the fluorine-containing surfactant is 100 ppb by mass or more and 3000 ppm by mass or less based on the mass of the aqueous dispersion (C).

12. An aqueous fluoropolymer dispersion comprising a fluoropolymer and an anionic fluorine-containing surfactant, the content of the anionic fluorine-containing surfactant being more than 0 ppb by mass and less than 100 ppb by mass relative to the fluoropolymer.

13. The anionic fluorine-containing surfactant is F(CF ２ ), ７ COOM, F(CF ２ ), ５ COOM, H(CF ２ ), ６ COOM, H(CF ２ ), ７ COOM, CF ３ O(CF ２ ), ３ OCHFCF ２ COOM, C ３ F ７ OCF(CF ３ ), ２ OCF(CF ３ ), ３ CF ２ CF ２ OCF(CF ３ ), ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C ２ F ５ OCF(CF ３ ), ２ OCF(CF ３ ), ３ OCF(CF ３ ), ２ OCF(CF ３ ), ２ ClCF ２ CF ２ OCF(CF ３ ), ２ OCF ２ COOM, CF ２ ClCF ２ CF ２ OCF ２ CF(CF ３ ), ２ OCF ２ COOM, CF ３ ClCF(CF ３ ), ２ OCF ２ COOM, CF ２ ClCF(CF ３ ), OCF ２ CF (CF ３ ) O.C.F. ２ COOM, and (In each formula, M is H, metal atom, NR ７ ４ , imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. ７ The fluoropolymer aqueous dispersion according to claim 12, wherein the compound is represented by the formula:

14. The aqueous fluoropolymer dispersion according to claim 12 or 13, wherein the anionic fluorine-containing surfactant has a Log POW of 3.5 or less.

15. The aqueous fluoropolymer dispersion according to any one of claims 12 to 14, further comprising a nonionic surfactant, the content of the nonionic surfactant being 4.0 to 12.0 mass % based on the fluoropolymer.

16. The fluoropolymer aqueous dispersion according to claim 15, wherein the nonionic surfactant is represented by the 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; A １ is a polyoxyalkylene chain.

17. The aqueous fluoropolymer dispersion according to claim 15 or 16, wherein the cloud point of the nonionic surfactant is 40 to 80°C.

18. The aqueous fluoropolymer dispersion according to any one of claims 12 to 17, wherein the fluoropolymer is polytetrafluoroethylene.

19. A method for producing an aqueous fluoropolymer dispersion having a reduced content of a polymer compound (I) having an ionic group, comprising at least a step of heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a polymer compound (I) having an ionic group to prepare an aqueous dispersion (E) containing: a phase (E1) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (E1) and a nonionic surfactant content of less than 2.00 mass% relative to the mass of phase (E1); a phase (E2) having a fluoropolymer content of less than 1.00 mass% relative to the mass of phase (E2) and a nonionic surfactant content of 2.00 mass% or more relative to the mass of phase (E2); and a phase (E3) having a fluoropolymer content of 1.00 mass% or more relative to the mass of phase (E3), and a nonionic surfactant content of 2.00 mass% or more relative to the mass of phase (E3).

20. The method according to claim 19, wherein the polymer compound (I) having an ionic group contains polymerized units (I) based on the monomer (I) represented by the general formula (I). １ X ３ = C.X. 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.

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