Aqueous fluoropolymer dispersion production method and aqueous fluoropolymer dispersion

Abstract

To provide a production method capable of producing an aqueous fluoropolymer dispersion having a reduced fluorine-containing surfactant content.SOLUTION: The present invention provides a method for producing an aqueous fluoropolymer dispersion having a reduced fluorine-containing surfactant content, the 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).SELECTED DRAWING: None

Description

[Technical Field]

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

[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, wherein the fluoroether carboxylic acid or salt is a compound represented by the formula: [R 1 -OL-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) and a fluoroether carboxylic acid or salt having the formula: adding a stabilizer to the aqueous fluoropolymer dispersion to form a stabilized aqueous fluoropolymer dispersion; heating the stabilized aqueous fluoropolymer dispersion to decarboxylate the fluoroether carboxylic acid or salt to form a fluoroether by-product; removing at least a portion of the fluoroether by-products; The method is described, which includes: [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-237842 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorosurfactant, the method comprising heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorosurfactant, a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is 1.00% by mass or more and 2.00% by mass or more relative to the mass of phase (E2); and Phase (E3) in which the content of the fluoropolymer is 1.00% by mass or more relative to the mass of phase (E3), and the content of the nonionic surfactant is 1.00% by mass or more and 2.00% by mass or more relative to the mass of phase (E3), The present invention provides a method for producing an aqueous fluoropolymer dispersion, which comprises at least the step of preparing an aqueous dispersion (E) containing: [Effects of the Invention]

[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. DETAILED DESCRIPTION OF THE INVENTION

[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, fluoroelastomer 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. Fluoroelastomers exhibit 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 fluoropolymer with a crosslinking site 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 polymerized 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 this disclosure, "organic group" means 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" are: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, a heteroaryl group optionally having one or more substituents, cyano group, formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2-, and RaNRbSO2- (In these formulas, Ra independently represents: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents, Rb is independently H or an alkyl group which may have one or more substituents. Includes. The organic group is preferably an alkyl group which may have one or more substituents.

[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 an acylamino group having a total of 2 to 12 carbon atoms, preferably a total of 2 to 8 carbon atoms, and more preferably an alkylcarbonylamino group 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 carbon atoms, 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, 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 2 to 9 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 10 carbon atoms in total, an arylcarbamoylamino group having 7 to 13 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 12 carbon atoms in total, preferably a carbamoylamino group, an alkylcarbamoylamino group having 2 to 7 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 6 carbon atoms in total, an arylcarbamoylamino group having 7 to 11 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 10 carbon atoms in total, 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 (e.g., 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 provides a method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, comprising: by heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant, a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is greater than or equal to 2.00% by mass relative to the mass of phase (E2); and Phase (E3) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (E3) and the content of said nonionic surfactant is 2.00% by mass or more relative to the mass of phase (E3), The method includes at least a step of preparing an aqueous dispersion (E) containing The present invention relates to a method for producing an aqueous fluoropolymer dispersion (hereinafter, sometimes 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 fluorinated surfactant, and in which 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.

[0040] Also, there is provided a method for producing an aqueous fluoropolymer dispersion having a reduced content of a polymer compound (I) having an ionic group, comprising the steps of: By heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a polymeric compound (I) having an ionic group, a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is greater than or equal to 2.00% by mass relative to the mass of phase (E2); and Phase (E3) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (E3) and the content of said nonionic surfactant is 2.00% by mass or more relative to the mass of phase (E3), The method includes at least a step of preparing an aqueous dispersion (E) containing 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 provides a polymeric composition comprising a fluoropolymer and a polymeric compound (I) having an ionic group, It is substantially free of anionic fluorine-containing surfactants, The content of the polymer compound (I) having an ionic group is more than 0 ppm by mass and 500 ppm by mass or less relative to the fluoropolymer, The proportion of hydrogen atoms bonded to carbon atoms in the polymer compound (I) having an ionic group substituted with fluorine atoms is 50% or more. The present invention relates to an aqueous fluoropolymer dispersion (hereinafter, sometimes referred to as a second aqueous fluoropolymer dispersion).

[0042] In the present disclosure, both the first production method and the second production method may be simply referred to as "production methods." Also, in the present 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, thereby producing 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 fluorosurfactant content, and is characterized in that an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorosurfactant 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 fluorosurfactant 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 produce an aqueous fluoropolymer dispersion with a reduced content of the polymer compound (I) having an ionic group by removing the polymer compound (I) having an ionic group at a removal rate that could not be achieved by conventional production methods.

[0046] The second production method of the present disclosure is a method for producing an aqueous fluoropolymer dispersion having a reduced content of the polymeric compound (I) having ionic groups, and is characterized by heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and the polymeric compound (I) having ionic groups, thereby separating 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 and the phase containing the fluoropolymer in a large amount can be recovered, thereby obtaining an aqueous fluoropolymer dispersion having a reduced content of the polymeric compound (I) having ionic groups. Furthermore, when the aqueous dispersion contains a fluorine-containing surfactant in addition to the polymeric compound (I) having ionic groups, it is possible to produce an aqueous fluoropolymer dispersion having a reduced content of the polymeric compound (I) having ionic groups 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 a phase (E1) having a fluoropolymer content of less than 1.00% by weight relative to the weight of phase (E1) and a nonionic surfactant content of less than 2.00% by weight relative to the weight of phase (E1); A phase (E2) having a fluoropolymer content of less than 1.00% by weight, relative to the weight of phase (E2), and a nonionic surfactant content of greater than or equal to 2.00% by weight, relative to the weight of phase (E2), and Phase (E3) in which the content of fluoropolymer is 1.00% by mass or more, relative to the mass of phase (E3), and the content of nonionic surfactant is 2.00% by mass or more, relative to the mass of phase (E3), An aqueous dispersion (E) containing:

[0049] In the first production method, by heating the aqueous dispersion in this way, the aqueous dispersion is separated into at least three phases: phase (E1) containing small amounts of fluoropolymer and nonionic surfactant, phase (E2) containing a relatively large amount of nonionic surfactant, and 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 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 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 a phase (E1) having a fluoropolymer content of less than 1.00% by weight relative to the weight of phase (E1) and a nonionic surfactant content of less than 2.00% by weight relative to the weight of phase (E1); A phase (E2) having a fluoropolymer content of less than 1.00% by weight, relative to the weight of phase (E2), and a nonionic surfactant content of greater than or equal to 2.00% by weight, relative to the weight of phase (E2), and Phase (E3) in which the content of fluoropolymer is 1.00% by mass or more, relative to the mass of phase (E3), and the content of nonionic surfactant is 2.00% by mass or more, relative to the mass of phase (E3), An aqueous dispersion (E) containing:

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

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

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

[0055] In another embodiment, the aqueous dispersion (E) is A phase (E1) having a fluoropolymer content of 0.01% by mass or more and less than 1.00% by mass relative to 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 relative to 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 relative to the mass of phase (E2), and a nonionic surfactant content of 20.00 to 50.00% by mass relative to the mass of phase (E2), and Phase (E3) in which the fluoropolymer content is 30.00 to 75.00% by mass relative to the mass of phase (E3) and the nonionic surfactant content is 2.00 to 5.00% by mass relative to the mass of phase (E3), An aqueous dispersion is prepared containing:

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

[0057] In one embodiment, the aqueous dispersion (E) is a phase (E1) in which the content of fluoropolymer is less than 1.00% by weight, relative to the weight of the aqueous dispersion (E), and the content of nonionic surfactants is less than 2.00% by weight, relative to the weight of the aqueous dispersion (E); a phase (E2) in which the content of fluoropolymer is less than 1.00% by weight, relative to the weight of the aqueous dispersion (E), and the content of nonionic surfactant is greater than or equal to 1.00% by weight, relative to the weight of the aqueous dispersion (E); and a phase (E3) in which the content of fluoropolymer is 10.0% by mass or more, relative to the mass of the aqueous dispersion (E), and the content of nonionic surfactant is 0.50% by mass or more, relative to the mass of the aqueous dispersion (E); An aqueous dispersion is prepared containing:

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

[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 according to the formula: P = Z / X × 100 (mass%) 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.

[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 = [(YZ) / Z] × 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 determined by a known method, for example, by LC / MS analysis. First, methanol is added to the aqueous fluoropolymer dispersion to perform extraction, and the resulting extract is analyzed by LC / MS. To further increase the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. The obtained extract is concentrated by nitrogen purging as needed, 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 confirmed to match the structural formula of the candidate fluorine-containing surfactant. Then, aqueous solutions containing five or more levels of the identified fluorine-containing surfactant are prepared, and LC / MS analysis is performed on the aqueous solutions containing each level. The relationship between the content and the area corresponding to that 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 into the content of the fluorine-containing surfactant. The resulting extract can be concentrated by purging with nitrogen, which allows the lower limit of quantitation of the measurement method to be lowered.

[0062] In the present disclosure, the content of the polymer compound (I) having an ionic group in the aqueous dispersion can be quantified by known methods. 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 the polymer compound (I), the methods for measuring the content of 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 heating the aqueous dispersion to separate it 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 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 6000 ppm by mass, more preferably 5000 ppm by mass or less, even more preferably 4500 ppm by mass or less, still more preferably 4000 ppm by mass or less, particularly preferably 3500 ppm by mass or less, and most preferably 3000 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 separation into three or more phases may not be possible. 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 mass ppb or more, 200 mass ppb or more, 300 mass ppb or more, 400 mass ppb or more, or 500 mass ppb or more, relative to the mass of the aqueous dispersion.

[0069] In the second production method, the content of the polymer compound (I) having ionic groups in the aqueous dispersion 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 polymer compound (I) having ionic groups 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 ionic groups 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 polymeric compound (I) having an ionic group in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the polymeric compound (I) having an ionic group from the aqueous dispersion, such as a method of adjusting the amount of the polymeric 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 to prepare 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 process of separation into three phases 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] A method for producing an aqueous fluoropolymer dispersion containing a reduced content of fluoropolymer surfactant or polymer compound (I) by separating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant or a polymer compound (I) having an ionic group into three phases includes the following steps: (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; (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; Examples include:

[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 fluorine-containing 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 in the first temperature range for 5 minutes or longer, a phase (D1) having a fluoropolymer content of less than 1.00% by weight relative to the weight of phase (D1) and a nonionic surfactant content of greater than or equal to 5.00% by weight relative to the weight 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); preparing an aqueous dispersion (D) containing 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 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) to (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 maintaining the aqueous dispersion (C) 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, and 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, and the upper limit is not particularly limited, but may be 10 hours or less.

[0081] When heating the aqueous dispersion to separate it 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) to (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, the aqueous dispersion (D) a phase (D1) having a fluoropolymer content of less than 1.00% by weight relative to the weight of phase (D1) and a nonionic surfactant content of greater than or equal to 5.00% by weight relative to the weight of phase (D1), and a phase (D2) in which the content of fluoropolymer is equal to or greater than 50.00% by mass relative to the mass of phase (D2) and the content of nonionic surfactant is less than 5.00% by mass relative to the mass of phase (D2); An aqueous dispersion is prepared containing:

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

[0085] In one embodiment, the aqueous dispersion (D) is a phase (D1) in which the content of fluoropolymer is less than 1.00% by weight, relative to the weight of the aqueous dispersion (D), and the content of nonionic surfactant is greater than or equal to 3.00% by weight, relative to the weight of the aqueous dispersion (D); and a phase (D2) in which the content of fluoropolymer is 10.0% by mass or more, relative to the mass of the aqueous dispersion (D), and the content of nonionic surfactant is less than 3.00% by mass, relative to the mass of the aqueous dispersion (D); An aqueous dispersion is prepared containing:

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

[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, even though the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group is reduced.

[0088] A nonionic surfactant is preferably added to the recovered phase (E3) to prepare an aqueous dispersion having a nonionic surfactant content of 4.0 to 12.0% by mass relative to the fluoropolymer. 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 collecting phase (E3), a viscosity adjuster, a pH adjuster, a preservative, a water-soluble polymer, etc. may be added to 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 a temperature that is 10°C 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, 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); adjusting the temperature of the aqueous dispersion (F) 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 35°C or higher, and maintaining the temperature of the aqueous dispersion (F) in the fourth temperature range for 5 minutes or more; a phase (G1) having a fluoropolymer content of less than 1.00% by mass relative to the mass of phase (G1) and a nonionic surfactant content of 5.00% by mass or more relative to the mass of phase (G1); Phase (G2) in which the content of fluoropolymer is 1.00% by mass or more, relative to the mass of phase (G2), and the content of nonionic surfactant is less than 5.00% by mass, relative to the mass of phase (G2); An aqueous dispersion (G) containing:

[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. 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, more preferably 30° C. higher than the cloud point of the nonionic surfactant.

[0094] The time for maintaining the aqueous dispersion (C) 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, and the upper limit is not particularly limited, but may be 10 hours or less.

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

[0096] The time for maintaining the aqueous dispersion (C) 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 aqueous dispersion (E) is stirred 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 aqueous dispersion can be stirred, for example, using a stirring blade provided in a vessel 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 maintaining the aqueous dispersion 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, the aqueous dispersion (G) A phase (G1) having a fluoropolymer content of less than 1.00% by weight, relative to the weight of phase (G1), and a nonionic surfactant content of greater than or equal to 5.00% by weight, relative to the weight of phase (G1), and Phase (G2) in which the content of fluoropolymer is 30.00% by mass or more, relative to the mass of phase (G2), and the content of nonionic surfactant is less than 5.00% by mass, relative to the mass of phase (G2); An aqueous dispersion is prepared containing:

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

[0102] In addition, as the aqueous dispersion (G), a phase (G1) in which the content of fluoropolymer is less than 1.00% by weight, relative to the weight of the aqueous dispersion (G), and the content of nonionic surfactant is greater than or equal to 0.50% by weight, relative to the weight of the aqueous dispersion (G); a phase (G2) in which the content of fluoropolymer is 10.0% by mass or more, relative to the mass of the aqueous dispersion (G), and the content of nonionic surfactant is less than 0.50% by mass, relative to the mass of the aqueous dispersion (G); An aqueous dispersion is prepared containing:

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

[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, even though the content of the fluorine-containing surfactant or the polymer compound (I) having an ionic group is reduced.

[0105] A nonionic surfactant is preferably added to the recovered phase (G2) to prepare an aqueous dispersion having a nonionic surfactant content of 4.0 to 12.0% by mass relative to the fluoropolymer. 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 even more preferably 7.0% by mass or less.

[0106] After collecting phase (G2), a viscosity adjuster, a pH adjuster, a preservative, a water-soluble polymer, etc. may be added to 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, even 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 the aqueous dispersion (E) is preferably 0 to 6000 ppm by mass, more preferably 5000 ppm by mass or less, even more preferably 4500 ppm by mass or less, still more preferably 4000 ppm by mass or less, particularly preferably 3500 ppm by mass or less, and most preferably 3000 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 separation into three or more phases may not be possible. 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 mass ppb or more, 200 mass ppb or more, 300 mass ppb or more, 400 mass ppb or more, or 500 mass ppb or more, relative to the mass of the aqueous dispersion (C).

[0110] The content of the polymer compound (I) having ionic groups 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 ionic groups 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 ionic groups in the aqueous dispersion is too high, the aqueous dispersion may separate into two phases, even when heated at an appropriate temperature, and separation into three or more phases may not be possible. The content of the polymeric compound (I) having an ionic group in the aqueous dispersion can be adjusted using a conventional method for reducing the content of the polymeric compound (I) having an ionic group from the aqueous dispersion, such as a method of adjusting the amount of the polymeric compound (I) used in the polymerization for preparing 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, aqueous dispersion (B) obtained by adding a nonionic surfactant to aqueous dispersion (A) can be used as aqueous dispersion (C) as it is. In the second production method, too, aqueous dispersion (C) may be prepared by subjecting aqueous dispersion (B) containing a nonionic surfactant and a polymeric compound (I) having ionic groups to ion exchange treatment. By subjecting aqueous dispersion (B) to ion exchange treatment and separating the resulting aqueous dispersion (C) into three phases, it is possible to produce an aqueous fluoropolymer dispersion with an even lower content of fluorine-containing surfactant, particularly even when aqueous dispersion (B) contains a fluorine-containing surfactant in addition to the polymeric compound (I) having ionic groups. In the second production method, too, 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. The anion exchange resin is represented by the following general formula (A1): -N + 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 them is an organic group having 3 or more carbon atoms. X represents a counter ion.) or an ion exchange group represented by the following general formula (A2): -NR 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. A resin having an ion exchange group represented by the following formula is preferred.

[0114] In general formula (A1), R1 , 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. The R 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 these, 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, 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 two or more carbon atoms or alkanol groups having one or more carbon atoms, and R 1 , R 2 and R 3 At least one of them 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 two or more carbon atoms or alkanol groups having two or more carbon atoms, and 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 also the same or different and are alkyl groups having two or more carbon atoms or alkanol groups having one or more carbon atoms, and R 1 , R 2 and R 3In 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 two or more carbon atoms or alkanol groups having two or more carbon atoms, and 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.

[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 general formula (A1), X is a counter ion. Examples of X include Cl, OH, Br, I, NO3, and SO4, and Cl or OH is preferred. When X is a divalent anion such as SO4, one counter ion coordinates 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 2 or more carbon atoms, and the other may be a hydrogen atom or an organic group having 1 carbon atom. 4 and R 5 may both be organic groups having 2 or more carbon atoms.

[0131] R 4 and R 5 At 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 is also preferably an organic group having two or more carbon atoms.

[0133] R 4 and R 5 In the formula, 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 the R 4 and R 5 In one of the more preferred embodiments, at least one of the groups is an alkyl group having 2 or more carbon atoms or an alkanol group having 2 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 anion exchange resins include those in which a group represented by general formula (A1) or a group represented by general formula (A2) is bonded to a resin matrix made of a styrene-based or acrylic polymer. 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. The pore diameter 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 anion exchange resin can be measured using the following method. First, accurately measure 10 mL of the standard sample into a measuring cylinder. Wrap the resin in a cloth and centrifuge it to remove any adhering moisture. Then, quickly measure the mass of the resin. Next, dry the resin in a thermostatic oven at 105°C for 4 hours, then allow it to cool in a desiccator for 30 minutes. Weigh the mass of the dried resin and calculate the moisture content 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) × 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 50% of the total 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 Co., Ltd.

[0146] Furthermore, resins having ion exchange groups (excluding the groups represented by the general formula (A1) and the general formula (A2)) can also be used as anion exchange resins. Examples of such anion exchange resins include resins having at least one ion exchange group selected from the group consisting of amino groups and quaternary ammonium groups (excluding the groups represented by the general formula (A1) and the general formula (A2)). ... -N + (CH3)3X - (wherein X represents a counter ion), or a group represented by the following general formula (B2): -N + (CH3)2(C2H4OH)X - (wherein X represents a counter ion) is preferred. Examples of X in general formulas (B1) and (B2) include Cl, OH, Br, I, NO3, and SO4, and Cl or OH is preferred. In the case of a divalent anion such as SO4, one counter ion coordinates to two molecules of the repeating unit 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 5000 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. The pore diameter may also be 1000 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.

[0150] From the viewpoint of removal efficiency, the resin having ion exchange groups (excluding the groups represented by the general formula (A1) and 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, it is 0.5 eq / L-resin or more, and particularly preferably, it is 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, it is 2.0 eq / L-resin or less, and particularly preferably, it is 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] 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 usually spherical. The average particle size of the resin 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, such as 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 0.1 seconds to 100 hours, 1 second to 50 hours, or 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] A conventional method can be used to contact the aqueous dispersion (B) with the ion exchange resin. 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 to prepare 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, relative to 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 to prepare 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 6000 ppm by mass, more preferably 5000 ppm by mass or less, even more preferably 4500 ppm by mass or less, still more preferably 4000 ppm by mass or less, particularly preferably 3500 ppm by mass or less, and most preferably 3000 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 mass ppb or more, 1000 mass ppb or more, 3000 mass ppb or more, 5000 mass ppb or more, or 7000 mass ppb or more, relative to the mass of the aqueous dispersion (B).

[0167] (Fluoromonomer polymerization) In the first production method, the aqueous dispersion (B) can be prepared by a method in which a fluoropolymer-containing aqueous dispersion (A) 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 a fluoropolymer-containing aqueous dispersion (A) 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, an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant or polymeric compound (I) having an ionic group can be produced by recovering phase (E3) or phase (G2). 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 ppm by mass or more, 100 ppm by mass or more, or 1000 ppm by mass or more, or 10% by mass or less, 5% by mass or less, or 1% by 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, or 1000 mass ppm or more, or 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 the fluoromonomer can be carried out by charging a reactor with the 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, 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, the fluoromonomer, polymerization initiator, fluorine-containing surfactant, chain transfer agent, etc. may be added additionally depending on the purpose. The polymerization method of the fluoromonomer is not particularly limited, but emulsion polymerization 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 in the anionic moiety having a molecular weight of 1,000 or less. The "anionic portion" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by the formula (I) described below n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0174] The above-mentioned fluorine-containing surfactant also includes a fluorine-containing surfactant having a LogPOW of 3.5 or less. The LogPOW 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 LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP [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 LogPOW is calculated from the HPLC elution time of the sample solution using standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) with known octanol / water partition coefficients under the following conditions: column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), eluent: acetonitrile / 0.6% by mass HClO₄ / water=1 / 1 (vol / vol%), flow rate: 1.0 mL / min, sample amount: 300 μL, column temperature: 40°C, detection light: UV 210 nm. A calibration curve between each elution time and the known octanol / water partition coefficient is then prepared, and the LogPOW 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. 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 WO 2013 / 189826.

[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 ) (In the formula, 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's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. Y 0 is an anionic group. Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. R 7 As for H or C 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom, or NR 7 4, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 7 4, which may be H, Na, K, Li, or NH4. Above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0177] The general formula (N 0The compound represented by the following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F, m1 is an integer of 3 to 15, and Y 0 is as defined above, a compound represented by the following general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, 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 CF3, and Y 0 is as defined above, a compound represented by the following general formula (N 3 ): Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 ) (In the formula, 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 CF2-Y 0 (N 4 ) (In the formula, Rf n4is 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 n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) and a compound represented by the general formula (N 5 ): [ka] (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 bond. 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 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) include perfluorocarboxylic acids (I) represented by the following general formula (I), ω-H perfluorocarboxylic acids (II) represented by the following general formula (II), perfluoroethercarboxylic acids (III) represented by the following general formula (III), perfluoroalkyl alkylenecarboxylic acids (IV) represented by the following general formula (IV), perfluoroalkoxy fluorocarboxylic acids (V) represented by the following general formula (V), perfluoroalkyl sulfonic acids (VI) represented by the following general formula (VII), ω-H perfluorosulfonic acids (VII) represented by the following general formula (VII), perfluoroalkyl alkylene sulfonic acids (VIII) represented by the following general formula (VIII), alkyl alkylene carboxylic acids (IX) represented by the following general formula (IX), fluorocarboxylic acids (X) represented by the following general formula (X), alkoxy fluorosulfonic acids (XI) represented by the following general formula (XI), compounds (XII) represented by the following general formula (XII), and compounds (XIII) represented by the following general formula (XIII).

[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, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0180] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0181] The perfluoroether carboxylic acid (III) is represented by the following general formula (III): Rf 1-O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, 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): Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, 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 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom, and 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(CF2) n5 SO3M (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(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0186] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (In the formula, 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): Rf 6 (CH2) n8 COOM (IX) (In the formula, 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 of 1 to 3, and M is as defined above.

[0188] The fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, 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 Y2 CF2-SO3M (XI) (In the formula, 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): [ka] (In the formula, X 1 , X 2 and X 3 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; Rf 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. Y 0 may be -COOM, -SO2M, or -SO3M, and may be -SO3M or COOM (wherein M is as defined above). Examples of L include a single bond and a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0191] The compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11is 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. Compound (XIII) is represented by the formula: CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (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 no methylene group (-CH2-), more preferably no C-H bond. By using a fluorine-containing surfactant that does not have a methylene group (-CH2-) or a C-H bond in the molecule, polymerization of the fluoromonomer can proceed smoothly 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 CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, or a fully fluorinated alkyl group (excluding those having -CH2-), 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 ): [ka] (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 partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond (but excluding those having -CH2-), provided that X n3 and X n4 Both Rf and Rf cannot be H. n5 is a linear or branched alkylene group having 1 to 3 carbon atoms, which may contain an ether bond, or a fully fluorinated alkylene group (excluding those having -CH2-), L is a linking group, and Y 0 is as defined above, where X n2 , X n3 , X n4 and Rf n5 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), perfluoroethercarboxylic 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), perfluoroalkyl alkylene sulfonic acid (VIII) represented by general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (In the formula, 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 (excluding those having -CH2-), and Rf 8 is a linear or branched, partially or completely fluorinated alkyl group having 1 to 6 carbon atoms (excluding those having -CH2-), and M is as defined above. 9 -O-CY 1 FCF2-SO3M (In the formula, Rf 9 is a linear or branched alkyl group having 1 to 12 carbon atoms which may contain an ether bond and which is partially or completely fluorinated and may contain chlorine (excluding those having -CH2-), and Y 1 is H or F, and M is as defined above.), an alkoxyfluorosulfonic acid (XI) represented by the general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3may 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 (excluding those having -CH2-), provided that X 2 and X 3 Both of these cannot be H, and 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-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (In the formula, Rf 11 is a chlorine-containing fluoroalkyl group having 1 to 5 carbon atoms (excluding those having -CH2-), 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: The fluorine-containing surfactant may be a mixture of these compounds. F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, [ka] (In each formula, M is H, metal atom, NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 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, 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 Groups) The polymer compound (I) having an ionic group used in the polymerization of the fluoromonomer is a polymer having one or more ionic groups in the molecule, and the ionic group is preferably an anionic group.

[0201] The anionic group possessed by the polymer compound (I) includes functional groups that provide anionic groups, such as sulfate groups and carboxylate groups, as well as acid groups such as -COOH and acid-base groups such as -COONH. Examples of the anionic group include sulfate groups, carboxylate groups, phosphate groups, phosphonate groups, sulfonate groups, and -C(CF)OM (wherein M is -H, a metal atom, or -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7is 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] The polymeric compound (I) preferably comprises an ionic group having a pKa of less than 10, more preferably less than 7. The ionic group of the 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 preferably -SO3M, -COOM, or -P(O)(OM). The "M" in the ionic group (anionic group) is defined as 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 polymeric 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 backbone relative to the ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SOF) are not considered ionic groups for purposes of determining the 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 is preferable. 4 More preferably, 0.3 × 10 4 More preferably, 0.4×10 4 More preferably, 0.5×10 4 More than 1.0 × 10 4 More than 3.0 × 10 is particularly preferable. 4 The above is particularly preferable, and 3.1 × 10 4 More than 75.0×10 4 The following is preferable: 50.0 x 10 4Less than 40.0 x 10 is more preferable. 4 More preferably, 30.0 x 10 4 The following is particularly preferred: 20.0 × 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. Furthermore, 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 0.4 x 10 4 That's 0.6 x 10 4 That's 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 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 Corporation.

[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 polymeric compound (I) is determined by the presence of an anionic group other than the acid functional group, such as -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (where M is a metal atom, NR 74. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 If the compound has a hydroxyl group (H or an organic group), these groups can be converted to acid forms 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). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF; 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 greater.

[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, 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, the hydrogen atom bonded to the 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 -(CH2) a -, -(CF2) a -, -(CF2) a -O-, -O-(CF2) a -, -(CF2) a -O-(CF2) b -, -O(CF2) a -O-(CF2) b -, -(CF2) a -[O-(CF2) b ] c -, -O(CF2) a -[O-(CF2) b ] c -, -[(CF2) a -O] b -[(CF2) c -O] d -, -O[(CF2) a -O] b -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b -, -O-(CF2) a -O-[CF(CF3)CF2O] b -, -O-[CF2CF(CF3)O] a -(CF2) b -O-, -O-[CF2CF(CF3)O] a-(CF2) b -O-[CF(CF3)CF2O] c -, -[CF2CF(CF3)O] a -, -[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -(CF2) b -, -[CF2CF(CF3)] a -CO-(CF2) b - and at least one selected from the 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] R is more preferably at least one selected from -O-CF2-, -O-CF2CF2-, -O-CF2CF2-O-, -O-CF2CF2CF2-, -O-CF2CF2CF2-O-, -O-CF2CF(CF3)-O-, -O-CF2CF2-O-CF(CF3)CF2-O-, -O-CF2CF(CF3)-O-CF2CF2-O-, and -O-CF2CF(CF3)-O-CF2-.

[0230] R is represented by the general formula (r1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6 are each independently H, F or CF3, 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): -CF2-O-(CX 7 2) e -(O) g- (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, and g is 0 or 1), and a divalent group represented by the formula (I) is more preferred.

[0231] Specific examples suitable for R include -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -O-CF2-, -O-CF2CF 2-, -O-CF2CF2CF2-, -O-CF2CF2CF2CF2-, -O-CF2CF(CF3)-O-CF2-, -O-CF2CF(CF3)-O-CF2CF2- , -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3 )CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CH2-, and the like. Among these, R is preferably a perfluoroalkylene group which may contain an oxygen atom, specifically, -CF2-O-, -CF2-O-CF2-, -O-CF2-, -O-CF2CF2-, -O-CF2CF(CF3)-O-CF2-, -O-CF2CF(CF3)-O-CF2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, or -CF2-O-CF(CF3)CF2-O- is preferred.

[0232] -R-CZ of general formula (I) 1 Z 2 - is a compound represented by the general formula (s1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (s1) (In the formula, X 6 are each independently H, F, or CF3, 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 2are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s1), Z 1 and Z 2 More preferably, they are F or CF3, and even more preferably, one is F and the other is CF3.

[0233] In addition, in the general formula (I), -R-CZ 1 Z 2 - as the general formula (s2): -CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (s2) (In the formula, X 7 are each independently H, F, or CF3, 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 More preferably, they are F or CF3, and even more preferably, one is F and the other is CF3.

[0234] -R-CZ of general formula (I) 1 Z 2- as -CF2-O-CF2-, -O-CF2CF2-, -O-CF2CF2CF2-, -O-CF2CF2CF2CF2-, -O-CF2CF(CF3)-O-CF2-, -O-CF2CF(CF3)-O-CF 2CF2-, -O-CF2CF(CF3)-O-CF2CF2CF2-, -CF2-O-CF(CF3)-, -CF2-OC(CF3)2-, -CF2-O-CF2-CF2-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2-C(CF3)2-, -CF2-O-CF2CF2-CF2-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF2CF2-C(CF3)2-, -CF2-O-CF(CF3)- CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2-O-CF(CF3)CF2-CF2-, -CF2-O-CF(CF3)CF2-CF(CF3 )-, -CF2-O-CF(CF3)CF2-C(CF3)2-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, or -CF2-O-CF(CF 3) CF2-OC(CF3)2- is preferred, -O-CF2CF2-, -O-CF2CF2CF2-, -O-CF2CF2CF2CF2-, -O-CF2CF(CF3)-O-CF2-, -O-CF2CF(CF3)-O- CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)CF2-CF(CF3)-, or -CF2-O-CF(CF3)CF2-O-CF(CF3)- are more preferred, with -O-CF2CF2- and -O-CF2CF(CF3)-O-CF2CF2- being even more preferred.

[0235] It is also preferred that the polymeric compound (I) is highly fluorinated. For example, anionic groups (A) such as phosphate group moieties (e.g., CH2OP(O)(OM)2) and sulfate group moieties (e.g., CH2OS(O)2OM) are present. 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 C—F bond, it is also preferable that the compound has no C—H bond. 1 , X 2 , and X 3 are all 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) can be —SO2M, —SO3M, —OSO3M, —COOM, —SONR′CH2COOM, —CH2OP(O)(OM)2, [—CH2O]2P(O)(OM), —CH2CH2OP(O)(OM)2, [—CH2CH2O]2P(O)(OM), —CH2CH2OSO3M, —P(O)(OM)2, —SON2NR′CH2CH2OP(O)(OM)2, [—SON2NR′CH2CH2O]2P(O)(OM), —CH2OSO3M, —SON2NR′CH2CH2OSO3M, or —C(CF3)2OM. Of these, -SO3M, -OSO3M, -COOM, -P(O)(OM)2 or -C(CF3)2OM are preferred, -COOM, -SO3M, -OSO3M, -P(O)(OM)2 or -C(CF3)2OM are more preferred, -SO3M, -COOM or -P(O)(OM)2 are even more preferred, and -SO3M or -COOM is particularly preferred.

[0239] M is H, metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0240] Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferred.

[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, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or -NH4 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 polymerized units (1) based on a monomer represented by general formula (1). CX2=CY(-CZ2-O-Rf-A) (1) (In the formula, X's may be the same or different and each represent -H or F; Y's may be -H, -F, an alkyl group, or a fluorine-containing alkyl group; and Z's may be the same or different and each represent -H, -F, an alkyl group, or a fluoroalkyl group. Rf's each represent a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. A's each represent -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M's each represent -H, a metal atom, or -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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 -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. Y is preferably -H, -F, or CF3, and more preferably -F.

[0248] In general formula (1), Z's may be the same or different and represent -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. Z's are preferably -H, -F, or CF3, and more preferably -F.

[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. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CF2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0252] The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, 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: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is also preferably a divalent group represented by the formula: H, F, or CF3; 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 -CFCF(CF)OCF-, -CF(CF)CF-O-CF(CF)-, -(CF(CF)CF-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) nExamples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0254] In the general formula (1), A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is H, a metal atom, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group).

[0255] R 7 As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula:

[0256] Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferred.

[0257] M is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, H, Na or NH4 is especially preferred, and H or NH4 is most preferred.

[0258] A is preferably -COOM or -SO3M.

[0259] Examples of the monomer represented by general formula (1) include a monomer represented by general formula (1a): CX2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-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) is exemplified.

[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 with 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 general formula (1A). CH2=CF(-CF2-O-Rf-A) (1A) (wherein Rf and A are the same as 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] [ka]

[0266] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4is H, F, or CF3; p1+q1+r1 are integers from 0 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5, except for 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] [ka]

[0268] Among them,

[0269] [ka]

[0270] It is preferable that:

[0271] As the monomer represented by general formula (1A), it is preferable that A in formula (1A) is -COOM, and in particular, at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above) is preferred, with CH2=CFCF2OCF(CF3)COOM being more preferred.

[0272] The monomer (I) is also preferably a monomer (2) represented by the general formula (2). The polymer compound (I) is also preferably a polymer compound (2) containing polymerized units (2) based on a monomer represented by general formula (2). CX2=CY(-O-Rf-A) (2) (In the formula, X's are the same or different and 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 also preferably a monomer (3) represented by the general formula (3). The polymer compound (I) is also preferably a polymer compound (3) containing polymerized units (3) based on a monomer represented by general formula (3). CX2=CY(-Rf-A) (3) (In the formula, X's are the same or different and 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 an ether bond having 2 to 100 carbon atoms; and A is the same as defined above.)

[0274] The polymer compound (I) may be a homopolymer consisting of only polymerized units (I), or a copolymer containing polymerized units (I) and polymerized units based on other monomers copolymerizable with the monomer represented by general formula (I). From the viewpoint of solubility in aqueous media, a homopolymer consisting of only polymerized units (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 general formula (I).

[0275] The polymeric compound (I) typically has terminal groups. The terminal groups are 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 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 are generated 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 preferred 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 preferred 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 the 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, polymerization can also be initiated as a redox reaction in combination with a reducing agent, etc. The concentration of the polymerization initiator is determined appropriately depending on the type of monomer, the molecular weight of the desired 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 di-sec-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-hexafluorobutyryl)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)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; or t-butyl hydroperoxide. 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 low temperatures below 30°C, it is preferable to use a redox initiator, which 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. 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 using potassium permanganate / oxalic acid, 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 the 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 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, more preferably an amount equivalent to 3 to 10 ppm by mass, of the mass of the aqueous medium used.

[0286] (aqueous medium) The aqueous medium used for the polymerization of fluoromonomers 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 water content 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 the polymerization has at least one fluorine atom and at least one double bond. Examples of the fluoromonomer include 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, and compounds represented by the general formula (100): CHX 101 =CX 102 Rf 101 (In the formula, X 101 and X 102 is H on one side and F on the other side, and Rf 101 is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), a fluorinated vinyl heterocycle, and at least one selected from the group consisting of a monomer that provides a crosslinking site is preferred.

[0290] Examples of the fluoroalkyl vinyl ether [FAVE] include: General formula (110): CF2=CF-ORf 111 (In the formula, Rf 111 represents a perfluoroorganic group; General formula (120): CF2=CF-OCH2-Rf 121 (In the formula, Rf 121 is a perfluoroalkyl group having 1 to 5 carbon atoms), General formula (130): CF2=CFOCF2ORf131 (In the formula, Rf 131 is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms, General formula (140): CF2=CFO(CF2CF(Y 141 )O) m (CF2) n F (In the formula, 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. General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A 151 (In the formula, Y 151 represents a fluorine atom, a chlorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain an etheric oxygen and a -SO2F group. n represents an integer of 0 to 3. n Y 151 may be the same or different. 152 represents a fluorine atom, a chlorine atom, or a -SO2F group. m represents an integer of 1 to 5. m Y 152 may be the same or different. 151 -SO2X 151 , -COZ 151 or -POZ 152 Z 153 represents X 151 are 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 are -NR 154 R 155 -OR 156 Represents R 151 , R 152 , R153 , 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. At least one selected from the group consisting of:

[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 the following formula:

[0294] [ka]

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

[0296] [ka]

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

[0298] Among the fluoromonomers represented by the general formula (110), General formula (160): CF2=CF-ORf 161 (In the formula, Rf 161 Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. Fluoromonomers represented by 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 preferably at least one selected from the group consisting of CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF3 and CF2=CFOCF2OCF2CF2OCF3.

[0302] The fluoromonomer represented by general formula (140) is preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)O(CF2)3F, CF2=CFO(CF2CF(CF3)O)2(CF2)3F, and CF2=CFO(CF2CF(CF3)O)2(CF2)2F.

[0303] The fluoromonomer represented by general formula (150) is preferably at least one selected from the group consisting of CF2=CFOCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2SO2F, CF2=CFOCF2CF(CF2CF2SO2F)OCF2CF2SO2F and CF2=CFOCF2CF(SO2F)2.

[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 in the formula (100) is preferably 1 to 6. Examples of the fluoromonomer represented by the formula (100) include CH2=CFCF3, CH2=CFCF2CF3, CH2=CFCF2CF2CF3, CH2=CFCF2CF2CF2H, CH2=CFCF2CF2CF2CF3, CHF=CHCF3 (E-isomer), and CHF=CHCF3 (Z-isomer), and among these, 2,3,3,3-tetrafluoropropylene represented by CH2=CFCF3 is preferred.

[0305] Fluoroalkylethylenes include: General formula (170): CH2=CH-(CF2) n -X 171 (In the formula, X 171 is H or F, and n is an integer of 3 to 10. Fluoroalkylethylenes represented by the formula: CH2=CH-C4F9 and CH2=CH-C6F 13 At least one selected from the group consisting of:

[0306] Examples of the fluoroalkyl allyl ether include: General formula (180): CF2=CF-CF2-ORf 111 (In the formula, Rf 111 represents a perfluoroorganic group.

[0307] Rf of general formula (180) 111 is Rf in general formula (110) 111 is the same as Rf 111 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. As the fluoroalkyl allyl ether represented by general formula (180), at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is preferred, at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is more preferred, and CF2=CF-CF2-O-CF2CF2CF3 is even more preferred.

[0308] The fluorinated vinyl heterocycle includes a compound represented by the general formula (230): [ka] (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] [ka] (In the formula, Z 231 and Z 232 are independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0310] Examples of monomers that provide crosslinking sites include: General formula (180):CX 181 2=CX 182 -R f 181 CHR 181 X 183 (In the formula, X 181 and X 182 are independently a hydrogen atom, a fluorine atom, or CH3, 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 CH3, X 183 is an iodine atom or a bromine atom. 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 CH3, 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. General formula (200): CF2=CFO(CF2CF(CF3)O) m (CF2) n -X 201 (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X 201 is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2I; and General formula (210): CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X 211 (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X 211 is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CHOH; 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 represents a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 3 to 18 carbon atoms, an at least partially fluorinated alkylene group or oxyalkylene group having 1 to 10 carbon atoms, which may have an oxygen atom, or -(Q) p -CF2O-(CF2CF2O) m (CF2O) n -CF2-(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. At least one selected from the group consisting of:

[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. 201is preferably a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH2I. 211 is preferably a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH 2 OH.

[0312] Monomers that provide crosslinking sites include CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2COOH, CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CF2=CFOCF2CF2CH2I, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, CH2=CFCF2OC At least one selected from the group consisting of F(CF3)CF2OCF(CF3)CH2OH, CH2=CHCF2CF2I, CH2=CH(CF2)2CH=CH2, CH2=CH(CF2)6CH=CH2 and CF2=CFO(CF2)5CN is preferred, and at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CN and CF2=CFOCF2CF2CH2I is more preferred.

[0313] In the polymerization, the fluoromonomer and a non-fluorine-containing monomer may be polymerized. Examples of the non-fluorine-containing 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 fluorine-free monomer may also be a functional group-containing hydrocarbon monomer (excluding monomers that provide crosslinking sites). Examples of the 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; and 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 the 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. Polymerization methods using bromine compounds or iodine compounds include, for example, a method of polymerizing fluoromonomers 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 compounds or iodine compounds 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, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2 Examples include CFClBr, CFBrClCFClBr, BrCFCFCFBr, BrCFCFBrOCF, 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. 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 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. Furthermore, in the polymerization of fluoromonomers, radical scavengers and decomposers can be added to adjust the polymerization rate and molecular weight. Furthermore, in the polymerization of fluoromonomers, fluorine-free anionic surfactants, fluorine-free nonionic surfactants, fluorine-free cationic surfactants, and the like can also be used.

[0323] The stabilizing aid is preferably paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. The stabilizing aid may be used alone or in combination of two or more. The stabilizing aid is more preferably paraffin wax. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms. The melting point of the paraffin wax is usually 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 mass % based on the mass of the aqueous medium used, and more preferably 0.1 to 8 mass %. 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) The 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 desired fluoropolymer, the reaction rate, etc.

[0326] (polymerization terminator) In order to terminate the polymerization reaction of the fluoromonomer, a polymerization terminator (radical scavenger) may be added.

[0327] Polymerization terminators are compounds that do not have the ability to restart after addition or chain transfer to free radicals in the polymerization system. Specifically, compounds that readily undergo chain transfer reactions with primary or propagating radicals to generate stable radicals that do not subsequently react with monomers, or compounds that readily undergo addition reactions with primary or propagating radicals to generate stable radicals, are used. The activity of chain transfer agents is generally characterized by the chain transfer constant and reinitiation efficiency, but chain transfer agents with a reinitiation efficiency of almost 0% are referred to as polymerization terminators. Preferred examples of polymerization terminators include at least one selected from the group consisting of aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl). Examples of aromatic hydroxy compounds include unsubstituted phenols, polyhydric phenols, salicylic acid, m- or p-salicylic acid, gallic acid, and naphthol. Examples of the unsubstituted phenol include o-, m-, or p-nitrophenol, o-, m-, or p-aminophenol, and p-nitrosophenol. Examples of polyhydric phenols include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, and naphthresorcinol. Examples of aromatic amines include o-, m-, or p-phenylenediamine and benzidine. Examples of the quinone compound include hydroquinone, o-, m-, or p-benzoquinone, 1,4-naphthoquinone, and alizarin. Examples of thiocyanates include ammonium thiocyanate (NHSCN), potassium thiocyanate (KSCN), and sodium thiocyanate (NaSCN). Among these, quinone compounds are preferred as the polymerization terminator, with hydroquinone being more preferred.

[0328] (nonionic surfactants) A fluoropolymer-containing aqueous dispersion (A) is prepared by polymerizing a fluoromonomer, and then a nonionic surfactant is added to the aqueous dispersion (A) to prepare an aqueous dispersion (B).

[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 the following: Polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl 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 following calculation formula according to the Griffin method. HLB value = 20 × [total chemical formula weight of hydrophilic parts] / 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% by 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 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 the 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; the Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m-22, n-23)), and the Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF.

[0345] The nonionic surfactant is preferably a fluorine-free nonionic surfactant. 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 esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, and polyoxyethylene fatty acid esters; and amine-based nonionic surfactants such as polyoxyethylene alkylamines and alkylalkanolamides.

[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). R 6 -OA 1 -H(i) (In the formula, R6 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 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 general 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, and even more preferably 73°C or lower.

[0354] A 1 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 more 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 oxypropylene group has an average of 0.5 to 1.5, 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-(C2H4O) n -H, C 12 H 25 -O-(C2H4O) n -H, C 10 H 21 CH(CH3)CH2-O-(C2H4O) n -H, C 13 H 27 -O-(C2H4O) n -(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) n -H, HC(CH 11 )(C7H 15 )-O-(C2H4O) 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) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Chemical), 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] The nonionic surfactant is preferably 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 surfactant represented by the general formula (ii): R 7 -C6H4-OA 2 -H (ii) (In the formula, R 7 is a linear or branched alkyl group having 4 to 12 carbon atoms, and A 2 is a polyoxyalkylene chain.) Specific examples of the nonionic surfactant include Triton (registered trademark) X-100 (trade name, manufactured by 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 more 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 If the oxypropylene group has an average of 0.5 to 1.5, low foaming properties are favorable and it is preferable.

[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-chain, branched-chain, 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-chain 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 hydroxyl 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 hydroxyl groups (and / or hydroxyalkyl groups) attached to the carbon ring atoms are replaced with long-chain residues, 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. [ka] (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, typically resulting in a mixture of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, Georg 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 nonionic surfactants 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-(C2H4O) n -H, C 12 H 25 -O-(C2H4O) n -H, C 10 H 21 CH(CH3)CH2-O-(C2H4O) n -H, C 13 H 27 -O-(C2H4O) n -(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) n -H, HC(CH 11 )(C7H 15 )-O-(C2H4O) n -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, 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. A 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 associated with 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. Fluoropolymer aqueous 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 above-mentioned first production method of the present disclosure.

[0372] The second aqueous fluoropolymer dispersion of the present disclosure contains a fluoropolymer and a polymeric compound (I) having an ionic group, is substantially free of anionic fluorine-containing surfactant, has a content of the polymeric compound (I) having an ionic group of more than 0 ppm by mass and not more than 500 ppm by mass relative to the fluoropolymer, and has fluorine atoms substituted for hydrogen atoms bonded to carbon atoms of the polymeric compound (I) having an ionic group at a rate of 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, and 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 aqueous fluoropolymer 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 polymer 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% relative to the fluoropolymer, 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 even more preferably 7.0 mass% or less.

[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 fluorine-free anionic surfactants 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 those represented by the general formula: R 21 -OCOCH(SO3A 21 )CH2COO-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 represents an alkali metal, an alkaline earth metal, or NH4.

[0387] R 21 and R 22 Examples 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 21Preferred examples of the alkyl sulfosuccinate include Na, NH4, etc. 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] The fluorine-free anionic surfactant is preferably an anionic hydrocarbon surfactant having a hydrocarbon main chain. 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; among these, those selected from the group consisting of sulfonic acids, carboxylic acids, and salts thereof are preferred, and aliphatic carboxylic acids or salts thereof are preferred. Examples of the aliphatic carboxylic acids or salts thereof are preferred, for example, saturated or unsaturated aliphatic carboxylic acids having 9 to 13 carbon atoms, which may have terminal H substituted with —OH, or salts thereof. Preferred aliphatic carboxylic acids are monocarboxylic acids, and preferred monocarboxylic acids are 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 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, relative to 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 fluoropolymers include TFE polymers in which the monomer having the largest molar fraction in the polymer (hereinafter referred to as the "most abundant monomer") is TFE, VDF polymers in which the most abundant monomer is VDF, and CTFE polymers in which the most abundant monomer is CTFE.

[0403] The fluoropolymers preferably have 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 preferably 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; and ω-hydroperfluoroolefin.

[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 and 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 even 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 the fluoropolymer 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 structure. 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 may be configured to have two or more layers. For example, the fluoropolymer may have a three-layer structure having 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 suitably 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, TFE polymerization 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. It is more preferably 120°C or lower, and even more preferably 100°C or lower. The polymerization pressure is more preferably 0.3 MPaG or higher, and even more preferably 0.5 MPaG or higher, and 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 the 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 reaction vessel equipped with a stirrer, deoxidizing, then charging TFE, adjusting the temperature to a predetermined level, 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. Once a predetermined amount of TFE has been supplied, the supply is stopped, the TFE in the reaction vessel is purged, and the temperature is returned to room temperature to terminate the reaction. Additional TFE may be continuously or intermittently supplied to prevent a decrease in pressure.

[0424] In the production of the TFE polymer (PTFE), various known modified monomers can also be used in combination. In the present disclosure, the TFE polymer is a concept that includes not only a TFE homopolymer but also a copolymer of TFE and a modified monomer that is not melt-processable (hereinafter referred to as "modified PTFE").

[0425] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include 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 selected from the group consisting of monomers having the general formula: CH2=CR Q1 -LR Q2 (In the formula, R Q1 represents a hydrogen atom or an alkyl group. L represents a single bond, -CO-O-*, -O-CO-* or -O-. * represents R Q2 R represents the bond 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): CF2=CF-ORf (A) (wherein Rf represents a perfluoroorganic group). In the present disclosure, the "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] An example of the perfluorovinyl ether is perfluoro(alkyl vinyl ether) [PAVE], where Rf in general formula (A) 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 ...

[0433] [ka]

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

[0435] CF3CF2CF2-(O-CF(CF3)-CF2) n - (wherein n represents an integer of 1 to 4).

[0436] Examples of hydrogen-containing fluoroolefins include CH2=CF2, CFH=CH2, CFH=CF2, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-isomer), and CHF=CHCF3 (Z-isomer).

[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: General formula: CF2=CF-CF2-ORf (wherein Rf represents a perfluoro organic 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. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0440] A preferred example of the modifying monomer is the modifying monomer (3) having a monomer reactivity ratio of 0.1 to 8. The presence of the modifying monomer (3) makes it possible to obtain PTFE particles having a small particle size and an aqueous dispersion with high dispersion stability.

[0441] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant when the propagating radical reacts with TFE when the propagating radical is less than a repeating unit based on TFE by the rate constant when the propagating radical reacts with the 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 and the modified monomer, determining the composition in the resulting polymer immediately after the start of copolymerization, and using the Feynman-Ross equation.

[0442] The copolymerization was carried out in a 6.0 L stainless steel autoclave using 3600 g of deionized and degassed water, 1000 ppm by mass of ammonium perfluorooctanoate relative to the water, and 100 g of paraffin wax at a pressure of 0.78 MPaG and a temperature of 70°C. 0.05 g, 0.1 g, 0.2 g, 0.5 g, and 1.0 g of the modified monomer were added to the reactor, respectively, and 0.072 g of ammonium persulfate (20 ppm by mass relative to the water) was added. TFE was continuously fed to maintain the polymerization pressure at 0.78 MPaG. When the TFE charge reached 1000 g, 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, which was 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). CH2=CH-Rf 1 (3a) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 10 carbon atoms. CF2=CF-O-Rf 2 (3b) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 2 carbon atoms. CF2=CF-O-(CF2) n CF=CF2(3c) (wherein n is 1 or 2).

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

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

[0446] The content of the modifying monomer (3) units 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 increasing 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, since it can obtain an aqueous dispersion with a small average primary particle diameter, a small aspect ratio of primary particles, and excellent stability, it is preferable to use at least one selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, perfluoro(alkyl vinyl ether), (perfluoroalkyl)ethylene, ethylene, and modified monomers having a functional group capable of reacting by radical polymerization and a hydrophilic group.By using the above-mentioned modified monomer, it is possible to obtain an aqueous dispersion of PTFE with a smaller average primary particle diameter, a small aspect ratio of primary particles, and excellent dispersion stability.In addition, it is possible to obtain an aqueous dispersion with less uncoagulated polymer.

[0448] From the viewpoint of reactivity with TFE, the modifying 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 units, perfluoro(alkyl vinyl ether) units, and (perfluoroalkyl)ethylene units is preferably in the range of 0.00001 to 1% by mass relative to all polymerized 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, in order of decreasing preference, are 0.80%, 0.70%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass.

[0449] The above-mentioned 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] The presence of the above-mentioned modifying monomer (A) can produce PTFE particles with a small primary particle size, and can produce an aqueous dispersion with high dispersion stability. In addition, the amount of uncoagulated polymer can be reduced. Furthermore, the aspect ratio of the primary particles can be reduced.

[0451] The amount of the modified monomer (A) used is preferably more than an 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 size of the obtained PTFE may not be reduced. 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 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 above-mentioned 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 step.

[0453] The above-mentioned modifying monomer (A) is incorporated into the produced polymer during the polymerization process, but since the concentration of the modifying 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] Examples of the hydrophilic group in the modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M represents H, a metal atom, or NR7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, 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. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), with Na, K, or Li being preferred.

[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- (In the formula, X e , X f and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group. The linking group for R can be represented by the formula: a Preferred linking groups include -CH=CH2 and -CF=CH 2、 -CH=CF 2、Examples include groups having an unsaturated bond such as -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CH=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, and -O-CF2-CF=CF2.

[0456] The modified monomer (A) has a functional group capable of reacting by radical polymerization, and therefore, when used in the polymerization, it is presumed that it reacts with the fluorine-containing monomer at the initial stage of the polymerization reaction, and forms highly stable particles having hydrophilic groups derived from the modified monomer (A). Therefore, it is considered that the number of particles increases when polymerization is carried out in the presence of the modified monomer (A).

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

[0459] The modifying monomer (A) is represented by the general formula (4): CX i X k =CX j R a -(CZ 1 Z 2 ) k -Y 3 (4) (In the formula, X i , X j and X k are each independently F, Cl, H, or CF; Y 3 is a hydrophilic group; R a is a linking group; Z 1 and Z 2are each independently H, F or CF3, and k is 0 or 1). Examples of the hydrophilic group include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M represents H, a metal atom, or NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, 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. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the following formula: 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 modifying monomer (A), an aqueous dispersion having a smaller average primary particle size and better stability can be obtained, and the aspect ratio of the primary particles can also be made smaller.

[0460] Above R a is a linking group. In the present disclosure, "linking group" refers to 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. The linking group may be linear or branched, cyclic or acyclic, 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.

[0461] Above R a is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group. R 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 may or may not contain a double bond. a may be either linear or branched, and may be either cyclic or acyclic. a may contain functional groups (e.g., esters, ethers, ketones, amines, halides, etc.). R a may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group. R 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. R a is preferably -(CH2) a -, -(CF2) a -, -O-(CF2) a -, -(CF2) a -O-(CF2) b -, -O(CF2) a -O-(CF2) b -, -(CF2) a -[O-(CF2) b c -, -O(CF2) a -[O-(CF2) b c -, -[(CF2) a -O] b -[(CF2) c -O] d -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b -, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2) a -, -(C=O)-(CF2) a -, -(C=O)-O-(CH2) a -, -(C=O)-O-(CF2) a -, -(C=O)-[(CH2) a -O] b -, -(C=O)-[(CF2) a -O] b -, -(C=O)-O[(CH2) a -O] b -, -(C=O)-O[(CF2) a -O] b -, -(C=O)-O[(CH2) a -O] b -(CH2) c -, -(C=O)-O[(CF2) a -O] b -(CF2) c -, -(C=O)-(CH2)​​​​​​a -O-(CF2) b -, -(C=O)-O-(CH2) a -O-(CH2) b -, -(C=O)-O-(CF2) a -O-(CF2) b At least one selected from -, -(C=O)-O-C6H4-, and 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.

[0463] R a Specific examples suitable as -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3) CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CH2-, -(C=O)-, -(C=O)-O-, -(C=O)- (CH2)-, -(C=O)-(CF2)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CF2)-, -(C=O)-[(CH2)2-O] n -, -(C=O)-[(CF2)2-O] n -, -(C=O)-O[(CH2)2-O] n -, -(C=O)-O[(CF2)2-O] n -, -(C=O)-O[(CH2)2-O] n -(CH2)-, -(C=O)-O[(CF2)2-O] n -(CF2)-, -(C=O)-(CH2)2-O-(CH2)-, -(C=O)-(CF2)2-O-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-, -(C=O)-O-(CF2)2-O-(CF2)-, -(C=O)-O-C6H4-, etc. aSpecifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2-O-CF(CF3)CF2-O-, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2)-, -(C=O)-O-(CH2)-, -(C=O)-O[(CH2)2-O] n -(C=O)-O[(CH2)2-O] n -(CH2)-, -(C=O)-(CH2)2-O-(CH2)-, or -(C=O)-O-C6H4- is preferred. In the above formula, n is an integer from 1 to 10

[0464] -R in the general formula (4) a -(CZ 1 Z 2 ) k As -CF2-O-CF2-, -CF2-O-CF(CF3)-, -CF2-O-C(CF3)2-, -CF2-O-CF2-CF2-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2-C(CF3)2-, -CF2-O-CF2CF2-CF2-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF2CF2-C(CF3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2-O-CF(CF3)CF2-CF2-, -CF2-O-CF(CF3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-C(CF3)2-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-O-C(CF3)2-, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2)-, -(C=O)-(CF2)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CF2)-, -(C=O)-[(CH2)2-O] n -(CH2)-, -(C=O)-[(CF2)2-O] n -(CF2)-, -(C=O)-[(CH2)2-O] n-(CH2)-(CH2)-, -(C=O)-[(CF2)2-O] n -(CF2)-(CF2)-, -(C=O)-O[(CH2)2-O] n -(CF2)-, -(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-, -(C=O)-O[(CF2)2-O] n -(CF2)-, -(C=O)-O[(CF2)2-O] n -(CF2)-(CF2)-, -(C=O)-(CH2)2-O-(CH2)-(CH2)-, -(C=O)-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-(CH2)-, -(C=O )-O-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2-, -(C=O)-O-(CF2)2-O-(CF2)-C(CF3)2-, or -(C=O)-O-C6H4- C(CF3)2- is preferred, -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(C F3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, -(C=O)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CH2)-(CH2)-, -(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2-, or -(C=O)-O-C6H4-C(CF3)2- is more preferred. In the above formula, n is an integer of 1 to 10.

[0465] Specific examples of the compound represented by general formula (4) include: [ka] (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 -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6 are each independently H, F, or CF3, 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 -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1. Divalent groups represented by the following formula are also preferred.

[0467] -R in general formula (4) a -(CZ 1 Z 2 ) k - can also be represented by the following formula (t1): -(C=O) h -(O) i -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (t1) (In the formula, X 6 are each independently H, F, or CF3, 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 1 and Z 2 are each independently F or CF3), and in formula (t1), Z 1 and Z2 More preferably, one is F and the other is CF3. In addition, in the general formula (4), -R a -(CZ 1 Z 2 ) k - is the following formula (t2): -(C=O) h -(O) i -CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (t2) (In the formula, X 7 are each independently H, F, or CF3, 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 CF3), and in formula (t2), Z 1 and Z 2 More preferably, one is F and the other is CF3.

[0468] The compound represented by the general formula (4) is a hydrophilic group (Y 3 ), 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 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). CF2=CF-O-Rf 0 -Y 3 (4a) (In the formula, 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). CH2=CH-O-Rf 0 -Y 3 (4b) (In the formula, Y 3 is a hydrophilic group, and Rf 0 is a perfluorinated divalent linking group defined by formula (4a).

[0472] In general formula (4), Y 3 One of the preferred embodiments is -OSO3M. 3 is -OSO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2SON(CH3)CH2CH2OSO3M), etc. In the above formulas, M is the same as above.

[0473] In general formula (4), Y 3 Another preferred form is -SO3M. 3 is -SO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CH2=CH(CF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH((CF2)3SO3M), etc. In the above formulas, M is the same as above.

[0474] In general formula (4), Y 3 -COOM is also a preferred form. 3 is -COOM, the compounds represented by general formula (4) include CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) n COOM) (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH((CF2)3COOM), CF2=CF(OCF2CF2SO2NR'CH2COOM), CF2=CF(O(CF2)4SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), CH2=CH((CF2)3SO2NR'CH2COOM). In the above formula, R' is H or C 1-4 is an alkyl group, and M is the same as above.

[0475] In general formula (4), Y 3 In another preferred embodiment, Y is -OPO3M or -OP(O)(OM)2. 3 is -OPO3M or -OP(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OP(O)(OM)2), CF2=CF(O(CF2)4CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OP(O)(OM)2), CF2=CF(O CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2, CH2=CH((CF2)4CH2OP(O)(OM)2), CH2=CH((CF2)3CH2OP(O)(OM)2), etc. In the above formula, M is the same as above.

[0476] In general formula (4), Y 3 In another preferred embodiment, Y is -PO3M or -P(O)(OM)2. 3 is -PO3M or -P(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2P(O)(OM)2), CF2=CF(O(CF2)4P(O)(OM)2), CF2=CF(OCF2CF(CF3)P(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)4P(O)(OM)2), CH2=CH((CF2)3P(O)(OM)2), and the like, where M is the same as above.

[0477] The compound represented by general formula (4) includes compounds represented by general formula (5): CX2=CY(-CZ2-O-Rf-Y 3 ) (5) (In the formula, X's may be the same or different and each represent -H or -F; Y's may be -H, -F, an alkyl group or a fluorine-containing alkyl group; and Z's may be the same or different and each represent -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf's may be a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above.), a compound represented by general formula (6): CX2=CY(-O-Rf-Y 3 ) (6) (In the formula, X may be 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 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above.) and a compound represented by general formula (7): CX2=CY(-Rf-Y 3 ) (7) (In the formula, X may be 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 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above. Preferably, the compound is at least one selected from the group consisting of compounds represented by 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.

[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 the 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 a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0480] In general formula (5), Z may be the same or different and is —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 a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[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 the 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, it 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 -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0483] The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The carbon number 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 a group represented by the following formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0484] In the general formula (5), Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, 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. R 7y The organic group in is preferably an alkyl group. R 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. 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, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or -NH4 is most preferred. Above Y 3 As the alkyl group, -COOM or -SO3M 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). CH2=CF(-CF2-O-Rf-Y 3 ) (5a) (Wherein Rf and Y 3 is the same as above.)

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

[0487] [ka]

[0488] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 are integers between 0 and 10; s1 is 0 or 1; t1 is an integer between 0 and 5; Y 3 is the same as above, except for 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] [ka]

[0490] Among them,

[0491] [ka]

[0492] It is preferable that:

[0493] The compound represented by general formula (5a) includes compounds represented by formula (5a) 3 is preferably -COOM, and particularly preferably at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above), and more preferably CH2=CFCF2OCF(CF3)COOM.

[0494] The compound represented by general formula (5) is preferably a compound (5b) represented by general formula (5b). CX 2 2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y3 (5b) (In the formula, each 2 are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, and Y 3 is the same as the definition above.)

[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, from the viewpoint 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 the above M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the obtained molded body is improved.

[0496] Examples of the compound represented by the above formula (5b) include CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above).

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

[0498] CF2=CFCF2-O-Rf-Y 3 (5c) (Wherein Rf and Y 3 is the same as above)

[0499] More specifically, [ka] 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 the 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 a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[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 the 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 -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0504] In the above general formula (6), Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7yare 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. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. 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, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or -NH4 is most preferred. Above Y 3 As the alkyl group, -COOM or -SO3M 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 formulae (6a), (6b), (6c), (6d) and (6e). CF2=CF-O-(CF2) n1 -Y 3 (6a) (wherein n1 represents an integer of 1 to 10, and Y 3 is the same as the definition above.) CF2=CF-O-(CF2C(CF3)F) n2 -Y 3 (6b) (wherein n2 represents an integer of 1 to 5, and Y 3 is the same as the definition above.) CF2=CF-O-(CFX 1 ) n3 -Y 3 (6c) (In the formula, X 1represents F or CF3, n3 represents an integer of 1 to 10, and Y 3 is the same as the definition above.) CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) 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.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-Y 3 (6e) (wherein n5 represents an integer of 0 to 10, and Y 3 and X 1 is the same as the definition above.)

[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 preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0507] Examples of compounds represented by the above formula (6a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF-O-CF2SO3M, CF2=CF(OCF2CF2SO3M), and CF2=CF(OCF2CF2CF2SO3M) (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 3is preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0509] In the formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM or -SO3M in terms of obtaining suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4 in terms of improving dispersion stability.

[0510] In the above formula (6d), the above X 1 is preferably —CF3 from the viewpoint of stability of the aqueous dispersion, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, and Y 3 is preferably —COOM or —SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and the M is preferably H or NH4.

[0511] Examples of the compound represented by the above formula (6d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4, 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 preferably —COOM or —SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and the M is preferably H or NH4.

[0513] Examples of the compound represented by general formula (6e) include CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0514] In general formula (7), Rf is preferably a fluorine-containing alkylene group having a carbon number of 1 to 40. 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): CF2=CF-(CF2) n1 -Y 3 (7a) (wherein n1 represents an integer of 1 to 10, and Y 3 is as defined above.) and a compound represented by general formula (7b): CF2=CF-(CF2C(CF3)F) n2 -Y 3 (7b) (wherein n2 represents an integer of 1 to 5, and Y 3 is as defined above. Preferably, at least one compound selected from the group consisting of compounds represented by Above Y 3 is preferably -SO3M or -COOM, and M is H, a metal atom, NR 7y 4. It is preferably an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 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 preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. Examples of the compound represented by the above formula (7a) include CF2=CFCF2COOM and CF2=CFCF2SO3M (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 preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0518] The above-mentioned 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 the modifying monomer (A) is used as the modifying monomer, the content of the modifying monomer (A) units is preferably in the range of 0.00001 to 1.0% by mass relative to the total polymerized units of the TFE polymer (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 limits are, in order of decreasing preference, 0.90%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass.

[0520] The aqueous dispersion of the TFE polymer is also preferably used for various applications as a composition to which an organic or inorganic filler is added depending on the purpose. By coating the above composition on a substrate made of metal or ceramic, it is possible to form a coating surface that has non-adhesiveness and a low coefficient of friction, and is excellent in gloss, smoothness, abrasion resistance, weather resistance, and heat resistance, and is suitable for painting rolls, cooking utensils, etc., and for impregnating glass cloth.

[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 solvents, ketone solvents, alcohol solvents, amide solvents, ester solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and halogenated hydrocarbon 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 the TFE polymer is also preferably used as a processing aid. When used as a processing aid, the aqueous dispersion is mixed with a host polymer or the like to improve the melt strength of the host polymer during melt processing, and the mechanical strength, electrical properties, flame retardancy, anti-dripping properties during combustion, and sliding properties of the resulting 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 combined with a resin other than the TFE polymer. The aqueous dispersion is suitable as a raw material for PTFE, as described in, for example, JP-A-11-49912, U.S. Pat. No. 5,804,654, JP-A-11-29679, and JP-A-2003-2980. Processing aids using the aqueous dispersion are 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. Examples of the melt-processable fluororesin include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, and EFEP. The aqueous dispersion containing the melt-processable fluororesin can be used as a coating material. The melt-processable fluororesin can sufficiently fuse the TFE polymer particles together, improving film-forming properties and imparting gloss to the resulting coating.

[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 dust from 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, for example, in the dust suppression treatment composition described in WO 2007 / 004250, and can also be suitably used in the dust suppression 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, which is a method in which the aqueous dispersion of the TFE polymer and an 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 also allows for the production of low molecular weight PTFE. Low-molecular-weight PTFE may be produced by polymerization, or by lowering the molecular weight of high-molecular-weight PTFE obtained by polymerization by 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 ppm by mass or more or more than 10 ppm by mass 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 fibrillating properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," a powder made from a TFE polymer. Paste extrusion is usually possible because high molecular weight PTFE has fibrillating 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 fibrillating 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 a water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895-89. In the present disclosure, "high molecular weight" means that the standard specific gravity is within the above range.

[0539] The above low molecular weight PTFE has a melt viscosity of 1×10 at 380°C. 2 ~7×10 5 The molecular weight is Pa·s. 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 2g sample preheated to 380°C for 5 minutes, and maintained at the above temperature under a load of 0.7 MPa.

[0540] The high-molecular-weight PTFE has a melt viscosity significantly higher than that of the low-molecular-weight PTFE, making it difficult to measure its melt viscosity accurately. On the other hand, while the melt viscosity of the low-molecular-weight PTFE can be measured, it is difficult to obtain a molded article from the low-molecular-weight PTFE that can be used to measure its standard gravity, making it difficult to measure its standard gravity accurately. Therefore, in this disclosure, standard 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. There are no known methods for directly determining 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 identified as the temperature corresponding to the maximum value that appears on a differential thermal analysis (DTA) curve obtained by using a TG / DTA (thermogravimetric / differential thermal analyzer) to raise the temperature of PTFE that has no history of being heated to a temperature of 300°C or higher at a rate of 10°C / min.

[0542] The peak temperature of the PTFE may be 322 to 347°C. When the PTFE is a high molecular weight PTFE, the upper limit of the peak temperature of the PTFE may be 347°C or less, 346°C or less, 345°C or less, 344°C or less, 343°C or less, 342°C or less, 341°C or less, or 340°C or less. When the PTFE is a high-molecular-weight PTFE, the lower limit of the peak temperature of the PTFE may be 333°C or higher, or 335°C or higher. When the PTFE is a low-molecular-weight PTFE, the upper limit of the peak temperature of the PTFE may be 333°C or less, or 332°C or less. When the PTFE is a low-molecular-weight PTFE, the lower limit of the peak temperature of the PTFE may be 322°C or higher, or 324°C or higher.

[0543] The average primary particle diameter of the primary particles of the low-molecular-weight PTFE is preferably 10 to 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. A relatively small average primary particle diameter of the primary particles can be obtained, for example, by adding a modifying monomer to the polymerization system at the initial stage of TFE polymerization.

[0544] The average primary particle size of low-molecular-weight PTFE primary particles can be measured by dynamic light scattering. First, an aqueous dispersion of low-molecular-weight PTFE is prepared with a polymer solids concentration of approximately 1.0% by mass. Measurements can then be performed 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 70 cumulative measurements. For dynamic light scattering, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used, for example.

[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 for 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 52 mJ / mg or more. The heat of fusion of PTFE is more preferably 55 mJ / mg or more, and even more preferably 58 mJ / 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 fluorine-free 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 FEP, it is preferable to use cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, or the like as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, or the like 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 represented by the formula: CF2=CFORf4 (In the formula, Rf 4 It is preferable to use one represented by 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 non-fluorine-containing 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% by 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 represented by the formula: CF2=CFCF2ORf 4 (In the formula, Rf 4 It is preferable to use one represented by 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 the other monomers include the above-mentioned fluoromonomers (excluding TFE and perfluoroallyl ether) and non-fluorine-containing monomers. One or more types of other monomers may be used. The content of the 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 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, or the like as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, or the like as a pH buffer.

[0557] Furthermore, a primer composition can be obtained by adding a nonionic surfactant to an aqueous dispersion of a TFE / perfluoro(alkyl vinyl ether) copolymer such as PFA or MFA and a TFE / perfluoroallyl ether copolymer, and, if necessary, dissolving or dispersing polyethersulfone, polyamideimide and / or polyimide, and metal powder in an organic solvent. This primer composition can also be used in a method for coating a metal surface with a fluororesin, which comprises applying the primer composition to a metal surface, applying a melt-processable fluororesin composition onto 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 copolymerizable with these monomers may be polymerized to obtain a copolymer of ethylene, TFE, and other monomers as ETFE.The other monomers include the above-mentioned fluoromonomers (excluding TFE) and fluorine-free monomers (excluding ethylene).One or more types of other monomers can be used.

[0561] Preferred 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 (CH2=CFCF2CF2CF2H), and 2-trifluoromethyl-3,3,3-trifluoropropene ((CF3)2CF=CH2).

[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 monomers=(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) The manufacturing method of the present disclosure can also be used to manufacture an electrolyte polymer precursor. In the manufacturing 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 containing -SO2X 151 , -COZ 151 or -POZ 152 Z 153 (X 151 , Z 151 , Z 152 and Z 153 The ion-exchange polymer is composed of a monomer containing a functional group represented by the formula (which will be described later), and can be converted into an ion-exchange polymer through hydrolysis treatment.

[0565] Monomers used in the electrolyte polymer precursor include: General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A151 (In the formula, Y 151 represents a fluorine atom, a chlorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain an etheric oxygen and a -SO2F group. n represents an integer of 0 to 3. n Y 151 may be the same or different. 152 represents a fluorine atom, a chlorine atom, or a -SO2F group. m represents an integer of 1 to 5. m Y 152 may be the same or different. 151 -SO2X 151 , -COZ 151 or -POZ 152 Z 153 represents X 151 are 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 are -NR 154 R 155 -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, alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group. Examples of the fluorine-containing monomers include those represented by the formula: (I) and (II). Examples of the monomers used in the electrolyte polymer precursor include compounds containing two fluorosulfonyl groups described in WO 2007 / 013532 and perfluoromonomers having a -SOF group and a dioxolane ring described in WO 2014 / 175123. The preferred monomer composition (mol %) of the electrolyte polymer precursor is TFE:vinyl ether = (50-99):(50-1), and more preferably TFE:vinyl ether = (50-93):(50-7).

[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. Examples of the third monomer include 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, resulting in a polymer electrolyte membrane that 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 the dispersed state of the electrolyte polymer precursor. Subsequently, by heating to 120° C. or higher in a pressure vessel, the compound can be dissolved in, for example, a water / alcohol mixed solvent 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 to form a cast film, 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. Preferably, the ratio is TFE:ethylene:third monomer=(30-85):(10-69.9):(0.1-10).

[0570] The third monomer may be: 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 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.) is preferred.

[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 preferable to coat the aqueous dispersion of the TFE / VDF copolymer on a porous substrate made of a polyolefin resin and use it as a composite porous membrane. It is also preferable to disperse inorganic particles and / or organic particles in the aqueous dispersion and 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 a lithium secondary battery, 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, A method for producing an aqueous fluoropolymer dispersion having a reduced content of fluorine-containing surfactant, comprising: by heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant and a fluorine-containing surfactant, a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is greater than or equal to 2.00% by mass relative to the mass of phase (E2); and Phase (E3) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (E3) and the content of said nonionic surfactant is 2.00% by mass or more relative to the mass of phase (E3), The method includes at least a step of preparing an aqueous dispersion (E) containing A method for producing an aqueous fluoropolymer dispersion is provided. <2> According to a second aspect of the present disclosure, As the aqueous dispersion (E), a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is greater than or equal to 20.00% by mass relative to the mass of phase (E2); and Phase (E3) in which the content of said fluoropolymer is 30.00% by mass or more, relative to the mass of phase (E3), and the content of said nonionic surfactant is 2.00% by mass or more, relative to the mass of phase (E3); According to a first aspect, there is provided a method for preparing an aqueous dispersion containing: <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, a phase (D1) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (D1) and the content of said nonionic surfactant is equal to or greater than 5.00% by mass relative to the mass of phase (D1); and a phase (D2) in which the content of said fluoropolymer is 1.00% by mass or more, relative to the mass of phase (D2), and the content of said nonionic surfactant is less than 5.00% by mass, relative to the mass of phase (D2); preparing an aqueous dispersion (D) containing heating the 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 an aqueous dispersion (E) containing phases (E1) to (E3); Phase (E3) is recovered from the aqueous dispersion (E) containing phases (E1) to (E3). According to the first or second aspect, a manufacturing method is provided. <4> According to a fourth aspect of the present disclosure, contacting an aqueous dispersion (B) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant with an ion exchange resin, and recovering an aqueous dispersion (C); heating the aqueous dispersion (C) 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 maintaining the temperature of the heated aqueous dispersion (C) within the first temperature range for 5 minutes or longer, a phase (D1) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (D1) and the content of said nonionic surfactant is equal to or greater than 5.00% by mass relative to the mass of phase (D1); and a phase (D2) in which the content of said fluoropolymer is 1.00% by mass or more, relative to the mass of phase (D2), and the content of said nonionic surfactant is less than 5.00% by mass, relative to the mass of phase (D2); preparing an aqueous dispersion (D) containing heating the 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 an aqueous dispersion (E) containing phases (E1) to (E3); Phase (E3) is recovered from the aqueous dispersion (E) containing phases (E1) to (E3). A manufacturing method according to any one of the first to third aspects is provided. <5> According to a fifth aspect of the present disclosure, an aqueous dispersion (C) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant 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 within 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); adjusting the temperature of the aqueous dispersion (F) 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 35°C or higher, and maintaining the temperature of the aqueous dispersion (F) in the fourth temperature range for 5 minutes or more, a phase (G1) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (G1) and the content of said nonionic surfactant is 5.00% by mass or more relative to the mass of phase (G1); Phase (G2) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (G2) and the content of said nonionic surfactant is less than 5.00% by mass relative to the mass of phase (G2); An aqueous dispersion (G) containing Phase (G2) is recovered from aqueous dispersion (G) containing phases (G1) to (G2). According to the first or second aspect, a manufacturing method is provided. <6> According to a sixth aspect of the present disclosure, contacting an aqueous dispersion (B) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant 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, the aqueous dispersion (E) is stirred 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 lower than a temperature that is 10°C higher than the cloud point of the nonionic surfactant and is 35°C or higher, and maintaining the temperature of the aqueous dispersion (F) in the fourth temperature range for 5 minutes or more, a phase (G1) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (G1) and the content of said nonionic surfactant is 5.00% by mass or more relative to the mass of phase (G1); Phase (G2) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (G2) and the content of said nonionic surfactant is less than 5.00% by mass relative to the mass of phase (G2); An aqueous dispersion (G) containing Phase (G2) is recovered from aqueous dispersion (G) containing phases (G1) to (G2). According to the first, second or fifth aspect there is provided a method of manufacture. <7> According to a seventh aspect of the present disclosure, There is provided a production method according to the fourth or sixth aspect, in which the aqueous dispersion (C) is recovered, a nonionic surfactant is added to the aqueous dispersion (C), and then the aqueous dispersion (C) is heated. <8> According to an eighth aspect of the present disclosure, A fluoromonomer is polymerized in the presence of a fluorine-containing surfactant, a polymerization initiator, and an aqueous medium to prepare an aqueous dispersion (A) containing a fluoropolymer; A nonionic surfactant is added to the aqueous dispersion (A) to prepare an aqueous dispersion (B) containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing surfactant. According to the fourth or sixth aspect, there is provided a manufacturing method. <9> According to a ninth aspect of the present disclosure, There is provided a production process according to an eighth aspect, wherein the content of the fluorinated surfactant in phase (E3) or phase (G2) is reduced to an amount equivalent to 0.001% by 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 a production method according to any one of the first to ninth aspects, wherein after phase (E3) or phase (G2) is recovered, a nonionic surfactant is added to the recovered phase. <11> According to an eleventh aspect of the present disclosure, 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); The fluorine-containing surfactant is an anionic fluorine-containing surfactant having a LogPOW 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). According to any one of the third to ninth aspects, there is provided a production method. <12> According to a twelfth aspect of the present disclosure, It contains a fluoropolymer and an anionic fluorine-containing surfactant, There is provided an aqueous fluoropolymer dispersion having an anionic fluorine-containing surfactant content of 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, The anionic fluorine-containing surfactant is F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and [ka] (In each formula, M is H, metal atom, NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7 is H or an organic group. <14> According to a fourteenth aspect of the present disclosure, According to the twelfth or thirteenth aspect, there is provided an aqueous fluoropolymer dispersion 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, It also contains a nonionic surfactant, According to any one of the twelfth to fourteenth aspects, there is provided an aqueous fluoropolymer dispersion, in which the content of the nonionic surfactant is 4.0 to 12.0 mass % relative to the fluoropolymer. <16> According to a sixteenth aspect of the present disclosure, According to a fifteenth aspect, there is provided an aqueous fluoropolymer dispersion, wherein the nonionic surfactant is represented by general formula (i): R 6 -OA 1 -H(i) (In the formula, R 6 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A 1 is a polyoxyalkylene chain. <17> According to a seventeenth aspect of the present disclosure, According to the fifteenth or sixteenth aspect, there is provided an aqueous fluoropolymer dispersion, wherein the cloud point of the nonionic surfactant is 40 to 80°C. <18> According to an eighteenth aspect of the present disclosure, According to any one of the twelfth to seventeenth aspects, there is provided an aqueous fluoropolymer dispersion, in which the fluoropolymer is polytetrafluoroethylene. <19> According to a nineteenth aspect of the present disclosure, A method for producing an aqueous fluoropolymer dispersion having a reduced content of a polymer compound (I) having an ionic group, comprising: By heating an aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a polymeric compound (I) having an ionic group, a phase (E1) in which the content of said fluoropolymer is less than 1.00% by weight relative to the weight of phase (E1) and the content of said nonionic surfactant is less than 2.00% by weight relative to the weight of phase (E1); a phase (E2) in which the content of said fluoropolymer is less than 1.00% by mass relative to the mass of phase (E2) and the content of said nonionic surfactant is greater than or equal to 2.00% by mass relative to the mass of phase (E2); and Phase (E3) in which the content of said fluoropolymer is 1.00% by mass or more relative to the mass of phase (E3) and the content of said nonionic surfactant is 2.00% by mass or more relative to the mass of phase (E3), The method includes at least a step of preparing an aqueous dispersion (E) containing A method for producing an aqueous fluoropolymer dispersion is provided. <20> According to a twentieth aspect of the present disclosure, According to a nineteenth aspect, there is provided a production method in which the polymer compound (I) having an ionic group contains polymerized units (I) based on a monomer (I) represented by general formula (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF; 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 greater. [Example]

[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 sample was placed in a 5 cm diameter aluminum cup, heated at 110°C for 30 minutes, and then 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 diameter The PTFE aqueous dispersion was diluted with water to a solids concentration of 0.15% by mass, and the transmittance of the resulting diluted aqueous dispersion to a 550 nm incident light per unit length and the number-based average primary particle diameter determined by measuring the unidirectional diameter using a transmission electron microscope photograph were measured to create a calibration curve. Using this calibration curve, the average primary particle diameter was determined from the measured transmittance of the 550 nm incident light for each sample.

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

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

[0580] (5) Measurement of fluorine-containing surfactant content 5.0 g of the aqueous dispersion was weighed, 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, to obtain an extract containing a fluorine-containing surfactant.

[0581] Calibration curve Five standard methanol solutions of fluorosurfactants with known concentrations ranging from 0.1 to 100 ng / mL were prepared and measured 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 fluorine-containing surfactant was measured using a liquid chromatograph mass spectrometer. The peak area of ​​the fluorine-containing surfactant in the extract was determined by MRM, and the content of the fluorine-containing surfactant in the aqueous dispersion was calculated. The quantification limit was 5 ppb by mass. The content of perfluoroethercarboxylic acid D was calculated by converting it to perfluorooctanoic acid using perfluorooctanoic acid as a standard substance.

[0583] Measurement equipment configuration and LC-MS measurement conditions [Table 1]

[0584] MRM measurement parameters [Table 2]

[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 PTFE aqueous dispersion The content of polymer compound (I) relative to PTFE in the PTFE aqueous dispersion obtained in the production example (T A The 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 obtained PTFE aqueous dispersion. T A =W D / [(W W ×PA / 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 supernatant phase A predetermined amount of sodium trifluoroacetate was added to the upper supernatant phase, 19 F NMR measurement was performed. 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 aqueous PTFE dispersion obtained in the experimental example (T D The mass % was calculated using the following formula. T D =T A -W S ×T S / W A T A (% by mass): Content of polymer compound (I) relative to PTFE in the PTFE aqueous dispersion obtained in each production example T S (mass%): content of polymer compound (I) D in the supernatant phase W S (g): Mass of the 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 surfactants> A 0.1% by mass aqueous solution of the nonionic surfactant was prepared, and the surface tension of the resulting 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: Fujifilm Wako Pure Chemical Industries, Ltd., Ammonium perfluoro(2-methyl-3-oxahexanoate), structural formula: CF3CF2CF2OCF(CF3)COONH4

[0592] Perfluoroether carboxylic acid B ammonium salt: Ammonium perfluoro-3,6-dioxaoctanoate, structural formula: CF3CF2OCF2CF2OCF2COONH4, perfluoroether carboxylic acid B was purchased from Apollo Scientific Ltd and converted into the 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: CF3OCF(CF3)CF2OCF(CF3)COONH4

[0594] Perfluoroether carboxylic acid D ammonium salt: Ammonium perfluoro (2,5-dimethyl-3,6-dioxaoctanoate), structural formula: CF3CF2OCF(CF3)CF2OCF(CF3)COONH4

[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: CF3CF2CF2OCF(CF3)CF2OCF(CF3)COONH4

[0596] The following nonionic surfactants were prepared: Surfactant (a): C 13 H 27 O(CH2CH2O)8H, cloud point 60℃ (HLB value 13.3, static surface tension 27.5mN / m) Surfactant (b): C 13 H 27 O(CH2CH2O)9H, cloud point 56°C (HLB value 13.3, static surface tension 27.5mN / m)

[0597] The polymer compounds (I) used in the experimental examples are as follows: Polymer H: A homopolymer of monomer D represented by the formula CH2=CF(CF2OCFCF3COOH) (number average molecular weight 12.2 x 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 Tosoh GPC HLC-8020 column and Shodex columns (one GPC KF-801, one GPC KF-802, and two GPC KF-806M columns connected in series) using tetrahydrofuran (THF) as the solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as the standard.

[0598] Manufacturing Example 1 A PTFE aqueous dispersion (1A) was obtained in accordance with Production Example 1 described in WO 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 Aqueous PTFE dispersion (1B) was prepared by adding surfactant (a) as a nonionic surfactant to the aqueous PTFE dispersion (1A) obtained in Production Example 1 in an amount of 10 parts by mass relative to 100 parts by mass of PTFE. 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. Aqueous PTFE dispersion (1C) was obtained by adding surfactant (a) to the resulting aqueous PTFE dispersion in an amount of 18 parts by mass relative to 100 parts by mass of PTFE. The solids concentration of aqueous PTFE dispersion (1C) was 25.1 mass%, the nonionic surfactant content relative to PTFE was 17.9 mass% relative to PTFE, the pH was 9.70, and the perfluoroethercarboxylic acid A content 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 to the mass of phase (D1). The solids concentration of phase (D2) was 70.0% by mass relative to the mass of phase (D2), the nonionic surfactant content was 2.66% by mass relative to the mass of phase (D2), and the perfluoroethercarboxylic acid A content was 711 ppb by mass relative to PTFE.

[0601] Experimental Example 1 The PTFE aqueous dispersion (1D) obtained in Comparative Example 1 was maintained at 82°C to form three phases (E1, E2, E3). After 5 hours, it was cooled to room temperature, and phase (E3) was recovered. The solids concentration of phase (E1) was 0.01% by mass relative to the mass of phase (E1), and the nonionic surfactant content was 1.05% by mass relative to the mass of phase (E1). The solids concentration of phase (E2) was 0.56% by mass relative to the mass of phase (E2), and the nonionic surfactant content was 24.6% by mass relative to the ma...

Claims

1. It contains a fluoropolymer and an anionic fluorine-containing surfactant, The anionic fluorine-containing surfactant is CF ３ CF ２ CF ２ OCF (CF ３ ) COONH ４ , C.F. ３ CF ２ OCF ２ CF ２ OCF ２ COONH ４ , C.F. ３ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ , C.F. ３ CF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ , and C.F. ３ CF ２ CF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ At least one selected from An aqueous fluoropolymer dispersion having an anionic fluorine-containing surfactant content of more than 0 ppb by mass and less than 100 ppb by mass relative to the fluoropolymer.

2. 2. The aqueous fluoropolymer dispersion according to claim 1, wherein the anionic fluorine-containing surfactant has a Log POW of 3.5 or less.

3. It also contains a nonionic surfactant, 3. The aqueous fluoropolymer dispersion according to claim 1, wherein the content of the nonionic surfactant is 4.0 to 12.0% by mass based on the fluoropolymer.

4. 4. The aqueous fluoropolymer dispersion according to claim 3, wherein the nonionic surfactant is represented by general formula (i): R ６ -O-A １ -H (i) (In the formula, R ６ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain.

5. 4. The aqueous fluoropolymer dispersion according to claim 3, wherein the cloud point of the nonionic surfactant is 40 to 80°C.

6. 3. The aqueous fluoropolymer dispersion according to claim 1, wherein the fluoropolymer is polytetrafluoroethylene.

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