Method for producing an aqueous fluoropolymer dispersion, aqueous fluoropolymer dispersion, and paint composition

Abstract

Provided is a fluoropolymer aqueous dispersion liquid production method for producing a fluoropolymer aqueous dispersion liquid containing a fluoropolymer, the method comprising: preparing an aqueous dispersion liquid containing a fluoropolymer by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium; adding a nonionic surfactant to the obtained aqueous dispersion liquid and adjusting the pH of the aqueous dispersion liquid to 7 or higher; adjusting the temperature of the aqueous dispersion liquid to 35°C or higher; and bringing the aqueous dispersion liquid containing the nonionic surfactant into contact with a treating agent.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing an aqueous fluoropolymer dispersion, an aqueous fluoropolymer dispersion, and a paint composition. [Background technology]

[0002] Patent Document 1 describes a method for removing a fluorine-containing emulsifier from an aqueous fluoropolymer dispersion, the method comprising adding an effective amount of nonionic emulsifier to the dispersion to stabilize it, contacting the stabilized dispersion with an effective amount of anion exchanger to remove a significant amount of the fluorine-containing emulsifier, separating the dispersion from the anion exchanger, and optionally concentrating the thus obtained dispersion.

[0003] Patent Document 2 describes a method for purifying a fluoropolymer dispersion, wherein the method is: (i) A step of providing an aqueous dispersion (D) of at least one fluoropolymer [polymer (F)] having a solids content (SC) of 15% by weight or more and containing at least one fluorinated surfactant [surfactant (FS)]; (ii) Adding at least one nonionic nonfluorinated surfactant [surfactant (NS)] to the aqueous dispersion (D); (iii) A step of adjusting the solid content (SC) to less than 10% by weight to obtain a diluted aqueous dispersion (dD); (iv) A step of contacting the diluted aqueous dispersion (dD) with at least one adsorbent to obtain an aqueous dispersion of polymer (F) having a fluorinated surfactant (FS) content of less than 1 ppm based on the total weight of solids, Methods including this are described. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2002-532583 [Patent Document 2] Special Publication No. 2009-533509 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present disclosure aims to provide a method for producing an aqueous dispersion of fluoropolymer in which the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms is reduced. Furthermore, this disclosure aims to provide an aqueous dispersion of fluoropolymers in which the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms is reduced. [Means for solving the problem]

[0006] According to this disclosure, a method for producing an aqueous fluoropolymer dispersion containing a fluoropolymer is provided, comprising: preparing an aqueous dispersion containing a fluoropolymer by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium; adding a nonionic surfactant to the obtained aqueous dispersion; adjusting the pH of the aqueous dispersion to 7 or higher; adjusting the temperature of the aqueous dispersion to 35°C or higher; and contacting the aqueous dispersion containing the nonionic surfactant with at least one treatment agent selected from the group consisting of ion exchange resins and adsorbents. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a method for producing an aqueous dispersion of fluoropolymer in which the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms is reduced. Furthermore, according to this disclosure, it is possible to provide an aqueous dispersion of fluoropolymers in which the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms is reduced. [Modes for carrying out the invention]

[0008] Before describing this disclosure in detail, we define or explain some of the terms used in this disclosure.

[0009] In this disclosure, fluororesin is a partially crystalline fluoropolymer and is a fluoroplastic. Fluororesin has a melting point and is thermoplastic, but may be melt-processable or non-melt-processable.

[0010] In this disclosure, melt processability means that the polymer can be melted and processed using conventional processing equipment such as extruders and injection molding machines. Therefore, melt processable fluororesins typically have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described later.

[0011] In this disclosure, fluororubber refers to an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) observed in differential scanning calorimetry (DSC) (heating rate 10°C / min) or differential thermal analysis (DTA) (heating rate 10°C / min) of the fluoropolymer is 4.5 J / g or less. Fluororubber exhibits elastomeric properties by crosslinking. Elastomer 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] A monomer that provides crosslinking sites is a monomer (curing site monomer) that has crosslinkable groups that provide crosslinking sites to a fluoropolymer for crosslinking by a curing agent.

[0013] In this disclosure, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer in which the content of tetrafluoroethylene units relative to the total polymerization units is 99 mol% or more.

[0014] In this disclosure, it is preferable that both the fluororesin (excluding polytetrafluoroethylene) and the fluororubber are fluoropolymers in which the content of tetrafluoroethylene units relative to the total polymerization units is less than 99 mol%.

[0015] In this 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 such "organic groups" are: Alkyl molecules which may have one or more substituents, An alkenyl group which may have one or more substituents, An alkynyl group which may have one or more substituents, A cycloalkyl group which may have one or more substituents, A cycloalkenyl group which may have one or more substituents, A cycloalkadienyl group which may have one or more substituents, An aryl group which may have one or more substituents, An aralkyl group which may have one or more substituents, A non-aromatic heterocyclic group which may have one or more substituents, A heteroaryl group which may have one or more substituents, Cyano group, formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2-, and RaNRbSO2- (In these formulas, Ra is independent of, Alkyl molecules which may have one or more substituents, An alkenyl group which may have one or more substituents, An alkynyl group which may have one or more substituents, A cycloalkyl group which may have one or more substituents, A cycloalkenyl group which may have one or more substituents, A cycloalkadienyl group which may have one or more substituents, An aryl group which may have one or more substituents, An aralkyl group which may have one or more substituents, A non-aromatic heterocyclic group which may have one or more substituents, A heteroaryl group which may have one or more substituents, Rb is independently an alkyl group which may have H or one or more substituents. It includes. The above organic group is preferably an alkyl group which may have one or more substituents.

[0017] Furthermore, in this disclosure, “substituent” means a substituteable group. Examples of such “substituent” are aliphatic group, aromatic group, heterocyclic group, acyl group, acyloxy group, acylamino group, aliphatic oxy group, aromatic oxy group, heterocyclic oxy group, aliphatic oxycarbonyl group, aromatic oxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, aliphatic sulfonyl group, aromatic sulfonyl group, heterocyclic sulfonyl group, aliphatic sulfonyloxy group, aromatic sulfonyloxy group, heterocyclic sulfonyloxy group, sulfamoyl group, aliphatic sulfonamide group, aromatic sulfonamide group, heterocyclic sulfonamide group, amino group, aliphatic amino This includes 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, hydroxyl groups, cyano groups, sulfo groups, carboxyl 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 above aliphatic group may be saturated or unsaturated, and may also include a hydroxyl group, aliphatic oxy group, carbamoyl group, aliphatic oxycarbonyl group, aliphatic thio group, amino group, aliphatic amino group, acylamino group, carbamoylamino group, etc. Examples of the above aliphatic group include alkyl groups having a total of 1 to 8 carbon atoms, preferably 1 to 4, such as a methyl group, ethyl group, vinyl group, cyclohexyl group, carbamoylmethyl group, etc.

[0019] The above 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, and the like. Examples of the above aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 total carbon atoms, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0020] The above heterocyclic group may have a halogen atom, a hydroxyl 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, and the like. Examples of the above heterocyclic group include a 5-6 membered heterocycle with a total of 2 to 12 carbon atoms, preferably 2 to 10, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0021] The above acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxyl 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, and the like. Examples of the above acyl group include acyl groups with a total of 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

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

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

[0024] The above carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the above 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 above aliphatic sulfonyl group may be saturated or unsaturated, and may also have a hydroxyl group, aromatic group, aliphatic oxy group, carbamoyl group, aliphatic oxycarbonyl group, aliphatic thio group, amino group, aliphatic amino group, acylamino group, carbamoylamino group, etc. Examples of the above aliphatic sulfonyl group include alkyl sulfonyl groups having a total of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as a methanesulfonyl group.

[0026] The above aromatic sulfonyl group may have a hydroxyl 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, and the like. Examples of the above aromatic sulfonyl group include aryl sulfonyl groups with a total of 6 to 10 carbon atoms, such as a benzenesulfonyl group.

[0027] The above amino group may also have an aliphatic group, an aromatic group, a heterocyclic group, etc.

[0028] The above acylamino group may include, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, or a propanoylamino group. Examples of the above acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably an acylamino group having a total of 2 to 8 carbon atoms, 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, or a propanoylamino group.

[0029] The above-mentioned 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 above-mentioned sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the above-mentioned sulfamoyl group include a sulfamoyl group, an alkyl sulfamoyl group having a total of 1 to 9 carbon atoms, a dialkyl sulfamoyl group having a total of 2 to 10 carbon atoms, an aryl sulfamoyl group having a total of 7 to 13 carbon atoms, a heterocyclic sulfamoyl group having a total of 2 to 12 carbon atoms, more preferably a sulfamoyl group, an alkyl sulfamoyl group having a total of 1 to 7 carbon atoms, a dialkyl sulfamoyl group having a total of 3 to 6 carbon atoms, an aryl sulfamoyl group having a total of 6 to 11 carbon atoms, a heterocyclic sulfamoyl group having a total of 2 to 10 carbon atoms, for example, a sulfamoyl group, a methyl sulfamoyl group, an N,N-dimethyl sulfamoyl group, a phenyl sulfamoyl group, a 4-pyridine sulfamoyl group, etc.

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

[0032] The above 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 total carbon atoms, an aliphatic oxy group having 1 to 4 total carbon atoms, a halogen atom, a carbamoyl group having 1 to 4 total carbon atoms, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 total carbon atoms.

[0033] The above aliphatic thio group may be saturated or unsaturated, and more preferably an alkyl thio group having a total of 1 to 8 carbon atoms, or more preferably 1 to 6 carbon atoms, such as a methyl thio group, an ethyl thio group, a carbamoyl methyl thio group, or a t-butyl thio group.

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

[0035] In this disclosure, the ranges represented by endpoints include all numerical values ​​that fall within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0036] In this disclosure, the phrase "at least 1" includes all numbers greater than or equal to 1 (for example, 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] The following describes specific embodiments of this disclosure in detail, but this disclosure is not limited to the embodiments described below.

[0038] 1. Method for producing an aqueous dispersion of fluoropolymer Aqueous dispersions obtained by polymerizing fluoromonomers may contain hydrophilic fluorine-containing compounds in addition to the fluoropolymer. These hydrophilic fluorine-containing compounds include fluorine-containing surfactants added during polymerization and fluorine-containing compounds produced by the polymerization of fluoromonomers.

[0039] In the manufacturing method of this disclosure, after preparing an aqueous dispersion, a nonionic surfactant is added to the aqueous dispersion, the pH of the aqueous dispersion is adjusted to 7 or higher, and the temperature of the aqueous dispersion is adjusted to 35°C or higher, before performing ion exchange treatment or adsorption treatment on the aqueous dispersion. Next, ion exchange treatment or adsorption treatment is performed. In this way, it has been found that by adding a nonionic surfactant to the aqueous dispersion and adjusting the pH and temperature of the aqueous dispersion to a very limited range before performing ion exchange treatment or adsorption treatment, an aqueous dispersion can be produced in which the content of hydrophilic fluorine-containing compounds is remarkably reduced.

[0040] In other words, the manufacturing method of the present disclosure is a method for producing an aqueous dispersion of a fluoropolymer containing a fluoropolymer, comprising: preparing an aqueous dispersion containing a fluoropolymer by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium; adding a nonionic surfactant to the obtained aqueous dispersion, adjusting the pH of the aqueous dispersion to 7 or higher, adjusting the temperature of the aqueous dispersion to 35°C or higher; and contacting the aqueous dispersion containing the nonionic surfactant with at least one treatment agent selected from the group consisting of ion exchange resins and adsorbents.

[0041] By using the manufacturing method of the present disclosure, the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms in an aqueous dispersion of fluoropolymer can be reduced. Furthermore, by using the manufacturing method of the present disclosure, not only can the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms be reduced, but the content of fluorine-containing compounds having hydrophilic groups in an aqueous dispersion of fluoropolymer can also be reduced.

[0042] The following details each process and the materials used in each process.

[0043] (Polymerization of fluoropolymers) In the manufacturing method of this disclosure, first, an aqueous dispersion containing a fluoropolymer is prepared by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium.

[0044] Polymerization of fluoromonomers can be carried out by charging a reactor with fluoromonomers, a fluorine-containing surfactant, a polymerization initiator, an aqueous medium, and other additives as needed, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to start the polymerization reaction. After the start of the polymerization reaction, additional fluoromonomers, polymerization initiators, fluorine-containing surfactants, chain transfer agents, etc., may be added as needed. The polymerization method for fluoromonomers is not particularly limited, but emulsion polymerization is preferred.

[0045] (Fluorine-containing surfactant) The fluorine-containing surfactant used in the polymerization of fluoromonomers is not particularly limited as long as it contains at least one fluorine atom, and conventionally known fluorine-containing surfactants can be used.

[0046] Examples of fluorine-containing surfactants include anionic fluorine-containing surfactants. Anionic fluorine-containing surfactants may be, for example, surfactants that contain fluorine atoms with a total number of carbon atoms of 20 or less in the part excluding the anionic group.

[0047] The above-mentioned fluorine-containing surfactant may also be a surfactant containing fluorine with a molecular weight of 1000 or less in the anionic portion. The above-mentioned "anionic portion" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by formula (I) described later. n1 In the case of COOM, "F(CF2)" n1 This is the "COO" part.

[0048] The above-mentioned fluorine-containing surfactants also include fluorine-containing surfactants with a LogPOW of 3.5 or less. The above LogPOW is the partition coefficient between 1-octanol and water, and is expressed as LogP [wherein P represents the ratio of the concentration of the fluorine-containing surfactant in octanol to the concentration of the fluorine-containing surfactant in water when a 1:1 mixture of octanol and water containing the fluorine-containing surfactant undergoes phase separation]. The above LogPOW is calculated by performing HPLC on standard substances with known octanol / water partition coefficients (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) under the following conditions: column; TOSOH ODS-120T column (φ4.6 mm × 250 mm, manufactured by Tosoh Corporation), eluent; acetonitrile / 0.6 mass% HClO4 water = 1 / 1 (vol / vol%), flow rate; 1.0 ml / min, sample volume; 300 μL, column temperature; 40°C, detection light; UV 210 nm. A calibration curve is created between the elution time and the known octanol / water partition coefficient, and the LogPOW is calculated from the elution time of the sample solution using this calibration curve.

[0049] Specifically, the above-mentioned fluorine-containing surfactants include U.S. Patent Publication No. 2007 / 0015864, U.S. Patent Publication No. 2007 / 0015865, U.S. Patent Publication No. 2007 / 0015866, U.S. Patent Publication No. 2007 / 0276103, U.S. Patent Publication No. 2007 / 0117914, U.S. Patent Publication No. 2007 / 142541, U.S. Patent Publication No. 2008 / 0015319, and U.S. Patent No. 3250808. Examples include those described in the book, U.S. Patent No. 3,271,341, Japanese Patent Publication No. 2003-119204, International Publication No. 2005 / 042593, International Publication No. 2008 / 060461, International Publication No. 2007 / 046377, Japanese Patent Publication No. 2007-119526, International Publication No. 2007 / 046482, International Publication No. 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, International Publication No. 2013 / 189824, and International Publication No. 2013 / 189826.

[0050] The above anionic fluorine-containing surfactants include those with the following general formula (N0 ): X n0 -Rf n0 -Y 0 (N 0 ) (wherein X n0 is H, Cl or F. Rf n0 is an alkylene group having 3 to 20 carbon atoms, linear, branched or cyclic, in which some or all of the H atoms are substituted by F, and the alkylene group may contain one or more ether bonds and some of the H atoms may be substituted by Cl. Y 0 is an anionic group.) Compounds represented by this formula are exemplified. Y 0 The anionic group of may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, a metal atom, NR 7 4, an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 7 is H or an organic group. Examples of the above metal atom include alkali metals (Group 1), alkaline earth metals (Group 2), etc., for example, Na, K or Li. R 7 may be H or an organic group of C 1-10 may be H or an organic group of C 1-4 may be H or an organic group of C 1-4 and may be an alkyl group. M may be 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, and may be H, Na, K, Li or NH4. The above Rf n0 may be one in which 50% or more of the H atoms are substituted by fluorine.

[0051] Examples of the compound represented by the above general formula (N 0 ) include the following general formula (N 1 ): X n0 -(CF2)m1 -Y 0 (N 1 ) (In the formula, X n0 These are H, Cl, and F, and m1 is an integer from 3 to 15, Y 0 This is 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 m2 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer from 0 to 3, and X n1 is F or CF3, and Y 0 This is 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 m3 is a partially or fully fluorinated alkyl group that may contain ether bonds and / or chlorine atoms with 1 to 13 carbon atoms, m3 is an integer from 1 to 3, and Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, where q is 0 or 1, and Y 0 This is 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 n4 Y is a linear or branched portion that may contain ether bonds with 1 to 12 carbon atoms, or a fully fluorinated alkyl group. n1 and Y n2is the same or different, H or F, p is 0 or 1, Y 0 This refers to the compounds represented by the above definition, and the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf is a linear or branched portion that may contain H, F, or an ether bond having 1 to 6 carbon atoms, or a fully fluorinated alkyl group, and may be the same or different. n5 L is a linear or branched moiety or a fully fluorinated alkylene group that may contain ether bonds with 1 to 3 carbon atoms, L is a linking group, and Y 0 This is defined above. However, X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less. Examples of compounds represented by ) are shown.

[0052] The above general formula (N 0 More specifically, examples of compounds represented by the formula (XII) include perfluorocarboxylic acid (I) represented by the following general formula (I), ω-H perfluorocarboxylic acid (II) represented by the following general formula (II), perfluoroether carboxylic acid (III) represented by the following general formula (III), perfluoroalkylalkylene carboxylic acid (IV) represented by the following general formula (IV), perfluoroalkoxyfluorocarboxylic acid (V) represented by the following general formula (V), perfluoroalkyl sulfonic acid (VI) represented by the following general formula (VII), ω-H perfluorosulfonic acid (VII) represented by the following general formula (VII), perfluoroalkylalkylene sulfonic acid (VIII) represented by the following general formula (VIII), alkylalkylene carboxylic acid (IX) represented by the following general formula (IX), fluorocarboxylic acid (X) represented by the following general formula (X), alkoxyfluorosulfonic acid (XI) represented by the following general formula (XI), compound (XII) represented by the following general formula (XII), compound (XIII) represented by the following general formula (XIII), and so on.

[0053] The above perfluorocarboxylic acid (I) is given by the following general formula (I) F(CF2) n1 COOM (I) (In the formula, n1 is an integer between 3 and 14, and M is H, a metal atom, NR) 7 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, 7 (where is H or an organic group.)

[0054] The above ω-H perfluorocarboxylic acid (II) is given by the following general formula (II) H(CF2) n2 COOM (II) (In the formula, n² is an integer between 4 and 15, and M is as defined above.)

[0055] The above perfluoroether carboxylic acid (III) is given by the following general formula (III) Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 (where n3 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer from 0 to 3, and M is as defined above.)

[0056] The above perfluoroalkylalkylene carboxylic acid (IV) is the following general formula (IV) Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 Rf is a perfluoroalkyl group having 1 to 5 carbon atoms. 3 (where n4 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer from 1 to 3, and M is as defined above.)

[0057] The above 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 or fully fluorinated alkyl group which may contain an ether bond and / or a chlorine atom having 1 to 12 carbon atoms, Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.)

[0058] The above perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI) F(CF2) n5 SO3M (VI) (In the formula, n5 is an integer of 3 to 14, and M is as defined above.)

[0059] The above ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII) H(CF2) n6 SO3M (VII) (In the formula, n6 is an integer of 4 to 14, and M is as defined above.)

[0060] The above perfluoroalkylalkylene 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.)

[0061] The above alkylalkylene carboxylic acid (IX) is represented by the following general formula (IX) Rf 6 (CH2) n8 COOM (IX) (wherein, Rf 6 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond having 1 to 13 carbon atoms, n8 is an integer of 1 to 3, and M is as defined above.) is represented thereby.

[0062] The above fluorocarboxylic acid (X) is represented by the following general formula (X) Rf 7 -O-Rf 8 -O-CF2-COOM (X) (wherein, Rf 7 is a linear or branched or fully fluorinated alkyl group which may contain an ether bond and / or a chlorine atom having 1 to 6 carbon atoms, Rf 8 is a linear or branched or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.) is represented thereby.

[0063] The above alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI) Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (wherein, Rf 9 is a linear or branched group which may contain an ether bond having 1 to​​​​​​​​​​​​​​​​​​​​​10 L is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 It is an anionic group. ) Y 0 may be -COOM, -SO2M, or -SO3M, or -SO3M, or COOM (wherein M is as defined above). Examples of L include single bonds, moieties that may contain ether bonds with 1 to 10 carbon atoms, or fully fluorinated alkylene groups.

[0065] The above compound (XIII) has the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11 This is represented as follows: is a fluoroalkyl group having 1 to 5 carbon atoms and containing chlorine, n9 is an integer from 0 to 3, n10 is an integer from 0 to 3, and M is as defined above. Compound (XIII) is CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 One example is CF2COONH4 (a mixture with an average molecular weight of 750, where n9 and n10 are as defined above).

[0066] As mentioned above, examples of the above-mentioned anionic fluorine-containing surfactants include carboxylic acid-based surfactants and sulfonic acid-based surfactants.

[0067] The fluorine-containing surfactant may be a single fluorine-containing surfactant or a mixture containing two or more fluorine-containing surfactants.

[0068] Fluorine-containing surfactants preferably have a methylene group (-CH2-), and more preferably do not have a CH bond. By using a fluorine-containing surfactant that does not have a methylene group (-CH2-) or a CH bond in its molecule, polymerization of fluoromonomers can proceed smoothly in the presence of an aqueous medium.

[0069] The number of H atoms in the hydrophobic group of a fluorine-containing surfactant is preferably 0 or 1, more preferably 0. By using a fluorine-containing surfactant with a small number of H atoms bonded to the carbon atoms constituting the hydrophobic group, polymerization of fluoromonomers in the presence of an aqueous medium can be facilitated. The number of carbon atoms in the hydrophobic group of a fluorine-containing surfactant having both 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 "part excluding the anionic group" of the molecular structure of the fluorine-containing surfactant described above. As for the hydrophilic group, Y 0 The groups exemplified as anionic groups are shown. The fluorine-containing surfactant may be a saturated fluorinated surfactant in which all carbon atoms bonded to the hydrophobic group are replaced by fluorine atoms.

[0070] Among the anionic fluorine-containing surfactants mentioned above, the general formula (N 1 Compounds represented by the general formula (N 2 Compounds represented by the general formula (N 4 ): Rf n4 -O-(CY n1 F) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 This is a linear or branched portion that may contain ether bonds with 1 to 12 carbon atoms, or a fully fluorinated alkyl group (excluding those having -CH2-), Y n1 is H or F, p is 0 or 1, Y 0 This refers to the compounds represented by the above definition, and the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 These may be the same or different, and may contain H, F, or a linear or branched portion having 1 to 6 carbon atoms in an ether bond, or a fully fluorinated alkyl group (excluding those having -CH2-), provided that X n3 and X n4 Both cannot be H. Rf n5 L is a linear or branched portion that may contain ether bonds with 1 to 3 carbon atoms, or a fully fluorinated alkylene group (excluding those having -CH2-), L is a linking group, and Y 0 This is defined above. However, X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less. Examples of compounds represented by ) are shown.

[0071] Among the anionic fluorine-containing surfactants mentioned above, perfluorocarboxylic acid (I) represented by general formula (I), ω-H perfluorocarboxylic acid (II) represented by general formula (II), perfluoroether carboxylic acid (III) represented by general formula (III), perfluoroalkylalkylene carboxylic acid (IV) represented by general formula (IV), perfluoroalkoxyfluorocarboxylic acid (V) represented by general formula (V), perfluoroalkyl sulfonic acid (VI) represented by general formula (VII), ω-H perfluorosulfonic acid (VII) represented by general formula (VII), perfluoroalkylalkylene sulfonic acid (VIII) represented by general formula (VIII), and general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (In the formula, Rf 7 Rf is a linear or branched moiety containing ether bonds and / or chlorine atoms with 1 to 6 carbon atoms, or a fully fluorinated alkyl group (excluding those having -CH2-), and 8is a linear or branched moiety having 1 to 6 carbon atoms or a fully fluorinated alkyl group (excluding those having -CH2-), and M is as defined above. Fluorocarboxylic acid (X) represented by general formula (XI): Rf 9 -O-CY 1 FCF2-SO3M (In the formula, Rf 9 Y is a linear or branched alkyl group (excluding those having -CH2-) that may contain ether bonds between 1 to 12 carbon atoms and may contain chlorine, and is partially or completely fluorinated. 1 is H or F, and M is as defined above. ) Alkoxyfluorosulfonic acid (XI), general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 These may be the same or different, linear or branched portion containing H, F and ether bonds having 1 to 6 carbon atoms, or a fully fluorinated alkyl group (excluding those having -CH2-), provided that X 2 and X 3 Both cannot be H, Rf 10 L is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 (This is an anionic group.) Compound (XII) represented by the general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (In the formula, Rf 11It is more preferable to select at least one compound from the group consisting of compounds (XIII) represented by (XIII), where n9 is an integer from 0 to 3, n10 is an integer from 0 to 3, and M is as defined above. By using these fluorine-containing surfactants, polymerization of fluoromonomers in the presence of an aqueous medium can be carried out smoothly.

[0072] Examples of fluorine-containing surfactants include compounds represented by the following formulas. Fluorine-containing surfactants may be mixtures 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. Imidazolium, pyridinium, or phosphonium, which may have substituents. 7 (This is either H or an organic group.)

[0073] In the manufacturing method of this disclosure, a fluorine-containing surfactant having 7 or fewer carbon atoms can be particularly preferably used as the fluorine-containing surfactant used for polymerization of fluoromonomers. By using a fluorine-containing surfactant having 7 or fewer carbon atoms, polymerization of fluoromonomers can proceed smoothly, and the content of fluorine-containing compounds having hydrophilic groups of 7 or fewer carbon atoms, such as fluorine-containing surfactants having 7 or fewer carbon atoms, can be efficiently removed from the aqueous dispersion of fluoropolymer by ion exchange treatment or adsorption treatment after polymerization.

[0074] Examples of fluorine-containing surfactants with 7 or fewer carbon atoms include those compounds represented by the general formulas (I) to (XIII) above that have 7 or fewer carbon atoms. In other words, examples of fluorine-containing compounds having a hydrophilic group with 7 or fewer carbon atoms include the following compounds.

[0075] Perfluorocarboxylic acids (I) having 7 or fewer carbon atoms are defined by the following general formula (I) F(CF2) n1 COOM (I) (In the formula, n1 is an integer between 3 and 6, and M is H, a metal atom, NR) 7 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, 7 (where is H or an organic group.)

[0076] ω-H perfluorocarboxylic acids (II) having 7 or fewer carbon atoms are given by the following general formula (II) H(CF2) n2 COOM (II) (In the formula, n² is an integer between 4 and 6, and M is as defined above.)

[0077] Perfluoroether carboxylic acids (III) having 7 or fewer carbon atoms are defined by the following general formula (III) Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 (where is a trifluoromethyl group, n3 is 1, and M is as defined above.)

[0078] Perfluoroalkylalkylenecarboxylic acids (IV) having 7 or fewer carbon atoms are defined by the following general formula (IV) Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 Rf is a perfluoroalkyl group having 1 to 4 carbon atoms. 3 n4 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer from 1 to 3, however Rf 2 , Rf 3 And n4 are combined such that the total number of carbon atoms is 6 or less, and M is as defined above.

[0079] Alkoxyfluorocarboxylic acids (V) having 7 or fewer carbon atoms are defined by the following general formula (V) Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 Y is a linear or branched portion that may contain ether bonds and / or chlorine atoms with 1 to 4 carbon atoms, or a fully fluorinated alkyl group. 1 and Y 2 ) are the same or different, and are represented by H or F, and M is as defined above.

[0080] Perfluoroalkyl sulfonic acid (VI) having 7 or fewer carbon atoms is defined by the following general formula (VI) F(CF2) n5 SO3M (VI) (In the formula, n5 is an integer between 3 and 7, and M is as defined above.)

[0081] ω-H perfluorosulfonic acid (VII) having 7 or fewer carbon atoms is given by the following general formula (VII) H(CF2) n6 SO3M (VII) (In the formula, n6 is an integer between 4 and 7, and M is as defined above.)

[0082] Perfluoroalkylalkylene sulfonic acid (VIII) having 7 or fewer carbon atoms is defined by the following general formula (VIII) Rf 5 (CH2) n7 SO3M (VIII) (In the formula, Rf 5 (where n7 is a perfluoroalkyl group having 1 to 4 carbon atoms, n7 is an integer from 1 to 3, and M is as defined above.)

[0083] Alkylalkylene carboxylic acids (IX) having 7 or fewer carbon atoms are defined by the following general formula (IX) Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6 (where n8 is a linear or branched portion that may contain ether bonds with 1 to 4 carbon atoms, or a fully fluorinated alkyl group, n8 is an integer from 1 to 3, and M is as defined above.)

[0084] Fluorocarboxylic acids (X) having 7 or fewer carbon atoms are given by the following general formula (X) Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, Rf 7 Rf is a linear or branched portion that may contain ether bonds and / or chlorine atoms with 1 to 2 carbon atoms, or a fully fluorinated alkyl group. 8 (where M is a linear or branched portion having 1 to 3 carbon atoms or a fully fluorinated alkyl group, and M is as defined above.)

[0085] Alkoxyfluorosulfonic acids (XI) having 7 or fewer carbon atoms are given by the following general formula (XI) Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (In the formula, Rf 9 Y is a partially or fully fluorinated alkyl group that may contain ether bonds between 1 to 5 carbon atoms, and may contain chlorine. 1 and Y 2 ) are the same or different, and are represented by H or F, and M is as defined above.

[0086] Compounds with 7 or fewer carbon atoms (XII) are defined by the following general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 Rf is a linear or branched portion that may contain H, F and ether bonds having 1 to 3 carbon atoms, or a fully fluorinated alkyl group, and may be the same or different. 10 L is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 It is an anionic group. ) Y 0 may be -COOM, -SO2M, or -SO3M, or -SO3M, or COOM (wherein M is as defined above). Examples of L include single bonds, moieties that may contain ether bonds with 1 to 4 carbon atoms, or fully fluorinated alkylene groups. However, X 1 , X 2 , X 3 , Rf 10 , L and Y 0 The total number of carbon atoms is 7 or less.

[0087] Compounds with 7 or fewer carbon atoms (XIII) are defined by the following general formula (XIII): Rf 11-O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11 (where n is a fluoroalkyl group having 1 to 2 carbon atoms and containing chlorine, n9 is an integer between 0 and 1, n10 is an integer between 0 and 1, and M is as defined above.)

[0088] As a fluorine-containing surfactant having 7 or fewer carbon atoms, at least one selected from the group consisting of compounds represented by general formula (I), general formula (III), general formula (IX), and general formula (X) is preferred, and at least one selected from the group consisting of compounds represented by general formula (I) and general formula (III) is more preferred.

[0089] Examples of fluorine-containing surfactants with 7 or fewer carbon atoms include compounds represented by the following formulas. Fluorine-containing surfactants with 7 or fewer carbon atoms may be mixtures of these compounds. F(CF2)5COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, [ka] (In each formula, M is H, metal atom, NR 7 4. Imidazolium, pyridinium, or phosphonium, which may have substituents. 7 (This is either H or an organic group.)

[0090] The amount of fluorine-containing surfactant added is preferably 10 ppm to 10% by mass relative to the aqueous medium, more preferably 100 ppm or more by mass, even more preferably 300 ppm or more by mass, more preferably 5% or less by mass, and even more preferably 1% or less by mass.

[0091] (Polymerization initiator) The polymerization initiator used for polymerization of fluoromonomers 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 by combining it with a reducing agent or the like. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate.

[0092] As the polymerization initiator mentioned above, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0093] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, such as dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, and dialkyl peroxides such as dit-butyl peroxide. Also, 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 Di[perfluoro(or fluorochloro)acyl]peroxides such as -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(tetrachloroundafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undachlorodotriacontafluorodocosanoyl)peroxide are typical examples.

[0094] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, and sodium salts of persulfuric acid, perborate, perchloric acid, superphosphate, and percarbonate; organic peroxides such as disuccinate peroxide and diglutaric acid peroxide; t-butyl permalate; and t-butyl hydroperoxide. A reducing agent such as sulfites may also be included, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0095] For example, when polymerization is carried out at low temperatures of 30°C or below, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and ammonium cerium 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 copper salts and iron salts to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0096] Examples of the redox initiators mentioned above include potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, ammonium persulfate / bisulfite / ferrous sulfate, manganese triacetate / oxalic acid, ammonium cerium nitrate / oxalic acid, bromate / bisulfite, etc., with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into the polymerization tank beforehand, and then the other may be added continuously or intermittently to initiate polymerization. For example, when using potassium permanganate / oxalic acid, it is preferable to charge oxalic acid into the polymerization tank and then continuously add potassium permanganate thereto.

[0097] There are no particular limitations on the amount of polymerization initiator added, but it is sufficient to add at least an amount that does not significantly reduce the polymerization rate (for example, a few ppm relative to water concentration) in one lump sum at the beginning of polymerization, or sequentially or continuously. The upper limit is a range in which the reaction temperature can be increased while removing heat from the apparatus surface using the heat of the polymerization reaction, and a more preferable upper limit is a range in which the heat of the polymerization reaction can be removed from the apparatus surface.

[0098] During the polymerization of fluoromonomers, the concentration of radicals during polymerization can be adjusted by adding a decomposition agent. Examples of decomposition agents 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 decomposition agent added is in the range of 25 to 300% by mass relative to the amount of oxidizing agent combined as a polymerization initiator (redox initiator). Preferably, the amount of decomposition agent added is 25 to 150% by mass, and more preferably 50 to 100% by mass. Furthermore, it is preferable to add the decomposition agent after 5% by mass of the total fluoromonomers consumed in the polymerization reaction has been polymerized, and more preferably after 10% by mass has been polymerized. Preferably, the amount of decomposition agent added is equivalent to 0.1 to 20 ppm by mass of the mass of the aqueous medium used, and more preferably 3 to 10 ppm by mass.

[0099] (aqueous medium) The aqueous medium used for polymerization of fluoromonomers refers to a reaction medium that causes polymerization and contains 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 ether or ketone, and / or a fluorine-containing organic solvent with a boiling point of 40°C or lower.

[0100] As an aqueous medium, an aqueous medium containing only water, or an aqueous medium containing only water and a fluorine-free organic solvent, is preferred, as it allows for smooth polymerization of fluoromonomers and suppresses a decrease in the removal efficiency of fluorine-containing compounds having hydrophilic groups. An aqueous medium containing only water is more preferred.

[0101] The water content in the aqueous medium is preferably 90% or more, more preferably 95% or more, even more preferably 99.0% or more, even more preferably 99.5% or more, particularly preferably 99.9% or more, and may be 100%, as it allows for smooth polymerization of fluoromonomers and suppresses a decrease in the removal efficiency of fluorine-containing compounds having hydrophilic groups.

[0102] (Fluoropolymer) The fluoromonomers used in polymerization have at least one fluorine atom and at least one double bond. Examples of the above fluoromonomers include tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinyl fluoride, vinylidene fluoride [VdF], trifluoroethylene, fluoroalkyl vinyl ether, fluoroalkylethylene, fluoroalkyl allyl ether, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, and general formula (100):CHX 101 =CX 102 Rf 101 (In the formula, X 101 and X 102 In this case, one side is H, the other is F, and Rf 101 Preferably, at least one selected from the group consisting of fluoromonomers (represented by a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), fluorinated vinyl heterocyclic compounds, and monomers that provide a crosslinking site.

[0103] Examples of the above fluoroalkyl vinyl ether [FAVE] include: General formula (110): CF2=CF-ORf 111 (In the formula, Rf 111 represents a perfluoroorganic group. ) Fluoromers represented by ) General formula (120): CF2=CF-OCH2-Rf 121 (In the formula, Rf 121 These are fluoromonomers represented by perfluoroalkyl groups having 1 to 5 carbon atoms. General formula (130): CF2=CFOCF2ORf 131 (In the formula, Rf 131 These are fluoromonomers represented by ( ), which are linear or branched perfluoroalkyl groups having 1 to 6 carbon atoms, cyclic perfluoroalkyl groups having 5 to 6 carbon atoms, or linear or branched perfluorooxyalkyl groups having 2 to 6 carbon atoms 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 from 1 to 4. n is an integer from 1 to 4. ) Fluoromers represented by ), and General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A 151 (In the formula, Y 151 Y represents a fluorine atom, a chlorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain etheric oxygen and a -SO2F group. n represents an integer from 0 to 3. n Y 151 They may be the same or different. 152 represents a fluorine atom, a chlorine atom, or a -SO2F group. m represents an integer from 1 to 5. m Y 152 They may be the same or they may be different. 151 is, -SO2X 151 ,-COZ 151 or -POZ 152 Z 153 It represents X. 151 F, Cl, Br, I, -OR 151 or -NR 152 R 153 Represents Z 151 , Z 152 and Z 153These are the same or different, -NR 154 R 155 OR 156 Represents R 151 , R 152 , R 153 , R 154 , R 155 and R 156 ) represents a fluoromonomer that may contain the same or different H, ammonium, alkali metal, fluorine atom, alkyl group, aryl group, or sulfonyl-containing group. At least one selected from the group consisting of is preferred.

[0104] In this disclosure, the term "perfluoroorganic group" means an organic group in which all hydrogen atoms bonded to a carbon atom are replaced with fluorine atoms. The perfluoroorganic group may have an ether oxygen atom.

[0105] As a fluoromonomer represented by general formula (110), Rf 111 Examples of fluoromonomers include those in which the perfluoroalkyl group has 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0106] Examples of perfluoroorganic groups in general formula (110) include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl groups. As a fluoromonomer represented by general formula (110), further, in the above general formula (110), Rf 111 Those in which the group is a perfluoro(alkoxyalkyl) group with 4 to 9 carbon atoms, Rf 111 The formula is as follows:

[0107] [ka]

[0108] The base represented by (wherein m represents an integer from 0 to 4) is Rf. 111The formula is as follows:

[0109] [ka]

[0110] Examples include the base represented by (wherein n represents an integer from 1 to 4).

[0111] Among the fluoromonomers represented by general formula (110), General formula (160): CF2=CF-ORf 161 (In the formula, Rf 161 ) represents a perfluoroalkyl group having 1 to 10 carbon atoms. Fluoromonomers represented by ) are preferred. Rf 161 A perfluoroalkyl group having 1 to 5 carbon atoms is preferred.

[0112] As the fluoroalkyl vinyl ether, at least one selected from the group consisting of fluoromonomers represented by general formulas (160), (130), and (140) is preferred.

[0113] Fluoromers represented by general formula (160) are generally called perfluoro(alkyl vinyl ethers). Preferably, the fluoroomer represented by general formula (160) is at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), and more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether).

[0114] As the fluoromonomer represented by general formula (130), at least one selected from the group consisting of CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF3, and CF2=CFOCF2OCF2CF2OCF3 is preferred.

[0115] As the fluoromonomer represented by general formula (140), 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 is preferred.

[0116] As the fluoromonomer represented by general formula (150), at least one selected from the group consisting of CF2=CFOCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2SO2F, CF2=CFOCF2CF(CF2CF2SO2F)OCF2CF2SO2F, and CF2=CFOCF2CF(SO2F)2 is preferred.

[0117] As a fluoromonomer represented by general formula (100), Rf 101 A fluoromonomer that is a straight-chain fluoroalkyl group is preferred, and Rf 101 A fluoromonomer in which the linear perfluoroalkyl group is is more preferred. 101 The carbon number of the compound is preferably 1 to 6. Examples of fluoromonomers represented by general formula (100) include CH2=CFCF3, CH2=CFCF2CF3, CH2=CFCF2CF2CF3, CH2=CFCF2CF2CF2H, CH2=CFCF2CF2CF2CF3, CHF=CHCF3 (E isomer), CHF=CHCF3 (Z isomer), and among these, 2,3,3,3-tetrafluoropropylene represented by CH2=CFCF3 is preferred.

[0118] As for fluoroalkylethylenes, General formula (170): CH2=CH-(CF2) n -X 171 (In the formula, X 171 is H or F, and n is an integer from 3 to 10. Fluoroalkylethylenes represented by ) are preferred, and CH2=CH-C4F9 and CH2=CH-C6F 13 At least one selected from the group consisting of the above is more preferable.

[0119] Examples of the above fluoroalkylallyl ethers include, General formula (180): CF2=CF-CF2-ORf 111 (In the formula, Rf 111 ) represents a perfluoroorganic group. Examples include fluoromonomers represented by ).

[0120] Rf of general formula (180) 111 Rf of general formula (110) 111 It is the same as Rf 111 As such, a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. 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.

[0121] The above fluorinated vinyl heterocyclic material is a general formula (230): [ka] (In the formula, X 231 and X 232 These are independently F, Cl, a methoxy group, or a fluorinated methoxy group, and Y 231 is equation Y 232 or formula Y 233 That is the case.

[0122] [ka] (In the formula, Z 231 and Z 232 A fluorinated vinyl heterocyclic compound represented by )) is independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0123] As monomers that provide crosslinking sites, General formula (180):CX 181 2=CX 182 -R f 181 CHR 181 X 183 (In the formula, X 181 and X 182 These are independently a hydrogen atom, a fluorine atom, or CH3, R f 181 is 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. ) Fluoromers represented by General formula (190):CX 191 2=CX 192 -R f 191 X 193 (In the formula, X 191 and X 192 These are independently a hydrogen atom, a fluorine atom, or CH3, R f 191 X is a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group, or a perfluoropolyoxyalkylene group. 193 ) is an iodine atom or a bromine atom. ) Fluoromers represented by General formula (200): CF2=CFO(CF2CF(CF3)O) m (CF2) n -X 201 (In the formula, m is an integer from 0 to 5, n is an integer from 1 to 3, X 201 ) is a fluoromonomer represented by 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 (In the formula, m is an integer from 0 to 5, n is an integer from 1 to 3, X 211 ) is a fluoromonomer represented by a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2OH, and 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 These are the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms. 221 This includes linear or branched alkylene groups having 1 to 18 carbon atoms, cycloalkylene groups having 3 to 18 carbon atoms, alkylene groups or oxyalkylene groups having 1 to 10 carbon atoms that are at least partially fluorinated, or -(Q) p -CF2O-(CF2CF2O) m (CF2O) n -CF2-(Q) p - A monomer represented by (wherein Q is an alkylene group or an oxyalkylene group, p is 0 or 1, and m / n is 0.2 to 5) and having a molecular weight of 500 to 10000. At least one selected from the group consisting of is preferred.

[0124] X 183 and X 193 It is preferable that R is an iodine atom. f 181 and R f 191 It is preferable that it is a perfluoroalkylene group having 1 to 5 carbon atoms. 181 It is preferably a hydrogen atom. 201It is preferable that this is a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2I. 211 It is preferable that the component is a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2OH.

[0125] The monomers that provide the crosslinking site are 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, and CH2=CFCF2OC It is preferable that it be 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, and more preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CN and CF2=CFOCF2CF2CH2I.

[0126] In the above polymerization, the above fluoromonomer and a fluorine-free monomer may be polymerized. Examples of the above fluorine-free monomer include hydrocarbon monomers that are reactive with the above fluoromonomer. Examples of the above hydrocarbon monomers 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, p-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetic acid, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, and hydroxyacetic acid. Examples include 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.

[0127] The above fluorine-free monomers may also be functional group-containing hydrocarbon monomers (excluding monomers that provide crosslinking sites). Examples of the above functional group-containing hydrocarbon monomers 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.

[0128] In the polymerization described above, particles of a desired fluoropolymer can be obtained by polymerizing one or more of the above-mentioned fluoromonomers.

[0129] (Chain transfer agent) In the manufacturing method of this disclosure, fluoromonomers can be further polymerized in the presence of a chain transfer agent. By using a chain transfer agent, the polymerization rate and molecular weight can be adjusted. Examples of chain transfer agents include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as various halogenated hydrocarbons such as isopentane, methane, ethane, propane, methanol, isopropanol, acetone, various mercaptans, and carbon tetrachloride, and cyclohexane.

[0130] Bromine compounds or iodine compounds may be used as chain transfer agents. A polymerization method using bromine compounds or iodine compounds includes, for example, a method in which fluoromonomers are polymerized in an aqueous medium in the presence of a bromine compound or iodine compound under substantially oxygen-free conditions (iodine transfer polymerization). A typical example of a bromine compound or iodine compound used is, for example, one with the general formula: R a I x Br y (In the formula, x and y are integers from 0 to 2, and satisfy 1 ≤ x + y ≤ 2, R a Examples of compounds represented by 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.

[0131] Examples of bromine 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, and BrCF2. Examples include CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 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 derivatives of benzene, diiodomonobromo substituted derivatives, and (2-iodoethyl) and (2-bromoethyl) substituted derivatives. These compounds may be used individually or in combination with each other.

[0132] Among these, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane are preferred in terms of polymerization reactivity, crosslinking reactivity, and availability.

[0133] The amount of chain transfer agent used is typically 1 to 50,000 ppm by mass, preferably 1 to 20,000 ppm by mass, relative to the total amount of fluoromonomer supplied. The amount of chain transfer agent used is preferably such that it is completely consumed during the polymerization of the fluoromonomer and does not remain in the aqueous dispersion containing the fluoropolymer, so as not to reduce the removal efficiency of fluorine-containing compounds having hydrophilic groups as much as possible. Therefore, the amount of chain transfer agent used is more preferably 10,000 ppm by mass or less, even more preferably 5,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, particularly preferably 500 ppm by mass or less, and most preferably 200 ppm by mass or less, relative to the total amount of fluoromonomer supplied.

[0134] The above-mentioned chain transfer agent may be added to the reaction vessel all at once before polymerization begins, all at once after polymerization begins, added in multiple portions during polymerization, or added continuously during polymerization.

[0135] (Other additives) In the polymerization of fluoromonomers, additives such as buffers, pH adjusters, stabilizing agents, and dispersion stabilizers can be used. Furthermore, radical scavengers and decomposing agents can be added to adjust the polymerization rate and molecular weight. Additionally, fluorine-free anionic surfactants, fluorine-free nonionic surfactants, and fluorine-free cationic surfactants may be used in the polymerization of fluoromonomers.

[0136] Preferred stabilizing agents include paraffin wax, fluorinated oils, fluorinated solvents, and silicone oils. These stabilizing agents may be used individually or in combination of two or more. Paraffin wax is more preferred as a stabilizing agent. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons with 12 or more carbon atoms are preferred. The melting point of paraffin wax is usually preferably 40-65°C, and more preferably 50-65°C.

[0137] The amount of stabilizing agent used is preferably 0.1 to 12% by mass, and more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing agent is sufficiently hydrophobic and completely separates from the aqueous dispersion after polymerization so as not to become a contaminating component.

[0138] (Polymerization conditions) Polymerization of fluoromonomers can be carried out under normal pressure and temperature conditions. Typically, the polymerization temperature is 5–120°C and the polymerization pressure is 0.05–10 MPaG. The polymerization temperature and pressure are appropriately determined depending on the type of monomer, the molecular weight of the target fluoropolymer, the reaction rate, and other factors.

[0139] (Aqueous dispersion obtained by polymerization) Polymerization of fluoromonomers yields an aqueous dispersion containing a fluoropolymer. The fluoropolymer content in the resulting aqueous dispersion is typically 8 to 50% by mass relative to the aqueous dispersion.

[0140] Aqueous dispersions obtained by polymerizing fluoromonomers typically contain, in addition to the fluoropolymer, fluorine-containing surfactants used during the polymerization of the fluoromonomers. Furthermore, aqueous dispersions obtained by polymerizing fluoromonomers may also contain, in addition to the fluoropolymer, fluorine-containing compounds having hydrophilic groups that are generated by the polymerization of fluoromonomers. In this disclosure, the fluorine-containing compounds having hydrophilic groups include fluorine-containing surfactants added during polymerization and fluorine-containing compounds having hydrophilic groups that are generated by the polymerization of fluoromonomers.

[0141] In this disclosure, the hydrophilic group of the fluorine-containing compound is preferably anionic group such as an acid group, for example, -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (where M represents a cation in each formula). Among the above hydrophilic groups, -SO3M or -COOM is preferred, and -COOM is more preferred.

[0142] Typical fluorine-containing compounds having hydrophilic groups in aqueous dispersions obtained by polymerization are fluorine-containing compounds having hydrophilic groups with a molecular weight of 1000 g / mol or less. According to the manufacturing method of this disclosure, it is possible to produce an aqueous fluoropolymer dispersion in which the content of fluorine-containing compounds having hydrophilic groups with a molecular weight of 1000 g / mol or less is reduced.

[0143] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group contains a fluorine-containing surfactant added during polymerization. The fluorine-containing surfactant added during polymerization is as described above for use in the polymerization of fluoromonomers.

[0144] The content of the fluorine-containing surfactant in the aqueous dispersion obtained by polymerization may be 10 ppm or more by mass, 100 ppm or more by mass, 1000 ppm or more by mass, 10% or less by mass, 5% or less by mass, or 1% or less by mass, relative to the fluoropolymer in the aqueous dispersion.

[0145] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group contains a fluorine-containing surfactant with 7 or fewer carbon atoms added during polymerization. The fluorine-containing surfactant with 7 or fewer carbon atoms added during polymerization is as described above for use in the polymerization of fluoromonomers.

[0146] The content of the fluorine-containing surfactant having 7 or fewer carbon atoms in the aqueous dispersion obtained by polymerization may be 10 ppm or more by mass, 100 ppm or more by mass, 1000 ppm or more by mass, 10% or less by mass, 5% or less by mass, or 1% or less by mass, relative to the fluoropolymer in the aqueous dispersion.

[0147] The content of hydrophilic fluorine-containing compounds in the aqueous dispersion obtained by polymerization (the total amount of fluorine-containing surfactants added during polymerization and hydrophilic fluorine-containing compounds produced by polymerization of fluoromonomers) may be 10 ppm by mass or more, 100 ppm by mass or more, 1000 ppm by mass or more, 10% by mass or less, 5% by mass or less, or 1% by mass or less, relative to the fluoropolymer in the aqueous dispersion.

[0148] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group is a compound represented by the following general formula (1). General formula (1): [X-Rf-A - ] i M i+ (wherein X is H, Cl, Br, F or I, Rf is a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain, or a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain interrupted by at least one oxygen atom, A - is an acid group, M i+ (where i is a cation with a valency of i, and i is an integer between 1 and 3)

[0149] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group is a compound represented by the following general formula (2). General formula (2):[C n-1 F 2n-1 COO - ]M + (In the formula, n is an integer between 9 and 14, M + (This represents a cation.)

[0150] Compounds represented by general formula (2) (perfluoroalkanoic acid) are known to be formed during polymerization when perfluoro(alkyl vinyl ether) or the like is used as a fluoromonomer (see International Publication No. 2019 / 161153).

[0151] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group is a compound represented by the following general formula (3). General formula (3):[R 1 -OL-CO2 - ]M + (In the formula, R 1 L is a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain, or a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain interrupted by at least one oxygen atom, L is a non-fluorinated, partially fluorinated or fully fluorinated alkylene group of a linear or branched chain, M + (This represents a cation.)

[0152] In one embodiment of the aqueous dispersion obtained by polymerization, the fluorine-containing compound having a hydrophilic group is a compound represented by general formula (4). General formula (4):[H-(CF2) m CO2 - ]M + (In the formula, m is an integer from 3 to 19, M + (This represents a cation.)

[0153] (Addition of nonionic surfactant to aqueous dispersion) In the manufacturing method of this disclosure, a nonionic surfactant is added to the aqueous dispersion obtained by polymerization. By adding a nonionic surfactant, the dispersibility of the fluoropolymer in the aqueous dispersion can be improved, and the dispersibility of the fluoropolymer can be maintained even during ion exchange treatment or adsorption treatment. As a result, the content of fluorine-containing compounds having hydrophilic groups in the aqueous dispersion can be reduced to a remarkable degree, and an aqueous dispersion with excellent dispersion stability can be produced.

[0154] Nonionic surfactants typically do not contain charged groups and have a hydrophobic moiety that is a long-chain hydrocarbon. The hydrophilic moiety of a nonionic surfactant contains water-soluble functional groups, such as ethylene ether chains derived from polymerization with ethylene oxide.

[0155] 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 their derivatives.

[0156] Specific examples of polyoxyethylene alkyl ethers include: polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyl ether, etc.

[0157] Specific examples of polyoxyethylene alkylphenyl ethers: polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, etc.

[0158] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, polyethylene glycol monostearate, etc.

[0159] Specific examples of sorbitan alkyl esters include: polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, etc.

[0160] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0161] Specific examples of glycerol esters: glycerol monomyristate, glycerol monostearate, glycerol monooleate, etc.

[0162] Specific examples of the above derivatives include: polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, etc.

[0163] The above ethers and esters may have an HLB value of 10 to 18.

[0164] Examples of nonionic surfactants include Dow Chemical's Triton® X series (X15, X45, X100, etc.), Tergitol® 15-S series, Tergitol® TMN series (TMN-6, TMN-10, TMN-100X, etc.), Tergitol® L series, BASF's Pluronic® R series (31R1, 17R2, 10R5, 25R4 (m~22, n~23)), Iconol® TDA series (TDA-6, TDA-9, TDA-10), etc.

[0165] The above nonionic surfactant is preferably a nonionic surfactant that does not contain fluorine. Examples 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 copolymer; ester-type nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, and polyoxyethylene fatty acid ester; and amine-based nonionic surfactants such as polyoxyethylene alkylamine and alkyl alkanolamide.

[0166] In the above-mentioned nonionic surfactant, the hydrophobic group may be an alkylphenol group, a linear alkyl group, or a branched alkyl group.

[0167] As the nonionic surfactant, a nonionic surfactant represented by general formula (i) is preferred. R 6 -OA 1 -H (i) (In the formula, R 6 A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. 1 (This is a polyoxyalkylene chain.)

[0168] In general formula (i), R 6 The number of carbon atoms is preferably 10 to 16, and more preferably 12 to 16. 6 When the number of carbon atoms is 18 or less, excellent sedimentation stability of the aqueous dispersion is easily obtained. 6 When the number of carbon atoms exceeds 18, the fluid temperature is high, making it difficult to handle. 6 If the carbon number is less than 8, the surface tension of the aqueous dispersion increases, which tends to reduce permeability and wettability.

[0169] A 1 The polyoxyalkylene chain may consist of oxyethylene and oxypropylene. It is a polyoxyalkylene chain with an average number of repeating oxyethylene groups of 5 to 20 and an average number of repeating oxypropylene groups of 0 to 2, and is hydrophilic. The number of oxyethylene units may include either a broad or narrow unimodal distribution, or a broader or bimodal distribution obtained by blending. When the average number of repeating oxypropylene groups is greater than 0, the oxyethylene and oxypropylene groups in the polyoxyalkylene chain may be arranged in blocks or randomly. From the viewpoint of viscosity and sedimentation stability of the aqueous dispersion, a polyoxyalkylene chain consisting of an average number of repeating oxyethylene groups of 7 to 12 and an average number of repeating oxypropylene groups of 0 to 2 is preferred. Particularly A 1 It is preferable that the oxypropylene group has an average of 0.5 to 1.5, as this results in good low foaming properties.

[0170] Comfortable, R 6The compound is (R')(R'')HC-, where R' and R'' are the same or different linear, branched, or cyclic alkyl groups, with 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.

[0171] A specific example of the above polyoxyethylene alkyl ether is 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(C5H) 11 )(C7H 15 )-O-(C2H4O) n Examples include -H (where n is an integer greater than or equal to 1 in each formula). Examples of commercially available polyoxyethylene alkyl ethers include the Genapol X series (manufactured by Clariant), such as Genapol X080 (trade name); the Neugen TDS series (manufactured by Daiichi Kogyo Seiyaku), such as Neugen TDS-80 (trade name); the Reocol TD series (manufactured by Lion Corporation), such as Reocol TD-90 (trade name); the Lionol® TD series (manufactured by Lion Corporation); the T-Det A series (manufactured by Harcros Chemicals), such as T-Det A138 (trade name); and the Tergitol® 15-S series (manufactured by Dow Chemical Corporation).

[0172] The above nonionic surfactant may also preferably be 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. This type of nonionic surfactant is also commercially available as, for example, TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all trade names, manufactured by Dow Chemical).

[0173] Furthermore, the hydrophobic group of the nonionic surfactant may be any of alkylphenol groups, linear alkyl groups, or branched alkyl groups. For example, as a nonionic surfactant, for example, general formula (ii) R 7 -C6H4-OA 2 -H (ii) (In the formula, R 7 A is a linear or branched alkyl group having 4 to 12 carbon atoms. 2 A nonionic surfactant represented by is a polyoxyalkylene chain. Specific examples of the above nonionic surfactant include Triton® X-100 (trade name, manufactured by Dow Chemical).

[0174] A 2The polyoxyalkylene chain may consist of oxyethylene and oxypropylene. It is a polyoxyalkylene chain with an average number of repeating oxyethylene groups of 5 to 20 and an average number of repeating oxypropylene groups of 0 to 2, and is hydrophilic. The number of oxyethylene units may include either a broad or narrow unimodal distribution, or a broader or bimodal distribution obtained by blending. When the average number of repeating oxypropylene groups is greater than 0, the oxyethylene and oxypropylene groups in the polyoxyalkylene chain may be arranged in blocks or randomly. From the viewpoint of viscosity and sedimentation stability of the aqueous dispersion, a polyoxyalkylene chain consisting of an average number of repeating oxyethylene groups of 7 to 12 and an average number of repeating oxypropylene groups of 0 to 2 is preferred. Particularly A 2 It is preferable that the oxypropylene group has an average of 0.5 to 1.5, as this results in good low foaming properties.

[0175] Comfortable, R 7 R'(R'') is a primary or secondary alkyl group, more preferably (R')(R'')HC-, where R' and R'' are the same or different linear, branched, or cyclic alkyl groups, with 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.

[0176] Polyol compounds can also be mentioned as nonionic surfactants. Specifically, those described in International Publication No. 2011 / 014715 can be mentioned. 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 portion include, for example, alkyl glycosides, modified alkyl glycosides, sugar esters, and combinations thereof. Examples of sugars include monosaccharides, oligosaccharides, and sorbitan, but are not limited to these. Examples of monosaccharides include pentoses and hexoses. Typical examples of monosaccharides include ribose, glucose, galactose, mannose, fructose, arabinose, and xylose. Examples of oligosaccharides include oligomers of 2 to 10 identical or different monosaccharides. Examples of oligosaccharides include saccharose, maltose, lactose, raffinose, and isomaltose, but are not limited to these.

[0177] Typically, suitable sugars for use as polyol compounds include cyclic compounds containing a five-membered ring of four carbon atoms and one heteroatom (typically oxygen or sulfur, but preferably oxygen), or cyclic compounds containing a six-membered ring of five carbon atoms and one heteroatom as described above, preferably oxygen. These further contain at least two or at least three hydroxyl groups (-OH groups) bonded to the carbocyclic atom. Typically, the sugar is modified in such a way that one or more hydrogen atoms of the hydroxyl group (and / or hydroxyalkyl group) bonded to the carbocyclic atom are substituted by the long-chain residue, so that an ether or ester bond is formed between the long-chain residue and the sugar moiety. Sugar-based polyols may contain one or more sugar units. One or more sugar units may be modified by the long-chain moiety as described above. Specific examples of sugar-based polyol compounds include glycosides, sugar esters, sorbitan esters, and mixtures and combinations thereof.

[0178] Preferred types of polyol compounds are alkyl or modified alkyl glucosides. These types of surfactants contain at least one glucose moiety. [ka] (In the formula, x represents 0, 1, 2, 3, 4, or 5, R 1 and R 2 R independently represents a long-chain unit containing H or at least 6 carbon atoms, however R 1 and R 2 Examples of compounds represented by (at least one of which is not H) include R 1 and R 2 A typical example of this is an aliphatic alcohol residue. 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. The above formula represents a specific example of an alkyl polyglucoside showing glucose in pyranose form, but it is understood that other sugars or sugars that are the same sugar but in different enantiomer or diastereomer forms may also be used. Alkyl glucosides can be obtained, for example, by acid-catalyzed reactions of glucose, starch, or n-butyl glucoside with aliphatic alcohols, typically yielding mixtures 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.

[0179] Other nonionic surfactants include difunctional block copolymers supplied by BASF as the Pluronic® series and tridecyl alcohol alkoxylates supplied by BASF as the Iconol® TDA series.

[0180] The above nonionic surfactant is preferably at least one selected from the group consisting of a nonionic surfactant represented by general formula (i) and a nonionic surfactant represented by general formula (ii), with the nonionic surfactant represented by general formula (i) being more preferred.

[0181] The above-mentioned nonionic surfactant preferably does not contain an aromatic portion.

[0182] Among nonionic surfactants, ethoxylates of 2,6,8-trimethyl-4-nonanol having an average of approximately 4 to 18 ethylene oxide units, and ethoxylates of 2,6,8-trimethyl-4-nonanol having an average of approximately 6 to 12 ethylene oxide units, C13 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(C5H) 11 )(C7H 15 )-O-(C2H4O) n - Preferably, at least one selected from the group consisting of H (where n is an integer of 1 or more).

[0183] It is preferable to prepare an aqueous dispersion in which the content of the nonionic surfactant in the aqueous dispersion is 5% by mass or more relative to the fluoropolymer, by adding a nonionic surfactant to the aqueous dispersion obtained by polymerization. The content of the nonionic surfactant in the aqueous dispersion to which the nonionic surfactant has been added is more preferably 7% by mass or more, even more preferably 9% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0184] The nonionic surfactant content is calculated using the formula: N = [(YZ) / Z] × 100 (mass%), obtained by heating approximately 1 g (X g) of the sample at 110°C for 30 minutes, the resulting residue (Y g), and then heating the obtained residue (Y g) at 300°C for 30 minutes, the resulting residue (Z g).

[0185] (Adjustment of pH and temperature of aqueous dispersion) The pH of the aqueous dispersion obtained by polymerization is usually less than 7, and the temperature is below 35°C. In the manufacturing method of this disclosure, the pH of the aqueous dispersion is adjusted to 7 or higher, and the temperature of the aqueous dispersion is adjusted to 35°C or higher, before contact with the treatment agent. By adding a nonionic surfactant to the aqueous dispersion and adjusting the pH and temperature of the aqueous dispersion before ion exchange treatment or adsorption treatment, the content of hydrophilic fluorine-containing compounds in the final aqueous dispersion can be reduced to a remarkable degree.

[0186] The pH of the aqueous dispersion subjected to ion exchange treatment or adsorption treatment is 7 or higher, preferably 8 or higher, more preferably 9 or higher, preferably 14 or lower, more preferably 13 or lower, and even more preferably 12 or lower.

[0187] pH can be adjusted by adding an alkali such as ammonia to an aqueous dispersion.

[0188] The temperature of the aqueous dispersion subjected to ion exchange treatment or adsorption treatment is 35°C or higher, preferably 37°C or higher, more preferably 39°C or higher, preferably below the cloud point of the nonionic surfactant, and more preferably less than 10°C lower than the cloud point of the nonionic surfactant. The temperature of the aqueous dispersion subjected to ion exchange treatment or adsorption treatment may be, for example, 50°C or lower, or 48°C or lower.

[0189] The content of the fluoropolymer subjected to ion exchange treatment or adsorption treatment is preferably 10% by mass or more, relative to the mass of the aqueous dispersion. The preferred lower limit of the fluoropolymer content is 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more. The upper limit of the fluoropolymer content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0190] (Ion exchange treatment or adsorption treatment) In the manufacturing method of this disclosure, a nonionic surfactant is added, and the pH and temperature of the aqueous dispersion are adjusted. Then, the aqueous dispersion containing the nonionic surfactant and with adjusted pH and temperature is subjected to an ion exchange treatment or an adsorption treatment. The ion exchange treatment or adsorption treatment can be carried out by contacting the aqueous dispersion containing the nonionic surfactant and with adjusted pH and temperature with at least one treatment agent selected from the group consisting of ion exchange resins and adsorbents. By contacting the aqueous dispersion containing the nonionic surfactant and with adjusted pH and temperature with the treatment agent, the content of hydrophilic fluorine-containing compounds in the aqueous dispersion can be reduced to a remarkable degree.

[0191] In the manufacturing method of this disclosure, it is preferable to maintain the temperature of the aqueous dispersion at 35°C or higher during the ion exchange treatment or adsorption treatment. The temperature of the aqueous dispersion during the ion exchange treatment or adsorption treatment is preferably 37°C or higher, more preferably 39°C or higher, preferably below the cloud point of the nonionic surfactant, and more preferably less than 10°C lower than the cloud point of the nonionic surfactant. The temperature of the aqueous dispersion during the ion exchange treatment or adsorption treatment may be, for example, 50°C or lower, or 48°C or lower.

[0192] In the manufacturing method of this disclosure, when the ion exchange treatment or adsorption treatment is repeated, the pH is set to 7 or higher and the temperature to 35°C or higher at least once. When repeating the ion exchange treatment or adsorption treatment, it is preferable to set the pH of the aqueous dispersion subjected to the treatment to 7 or higher and the temperature to 35°C or higher in either the ion exchange treatment or the adsorption treatment.

[0193] The pressure at which the aqueous dispersion and the treatment agent are brought into contact is not particularly limited, but may be, for example, 0.1 to 10 atmospheres, and can be carried out at normal pressure (approximately 1 atmosphere).

[0194] The time for contact between the aqueous dispersion and the treatment agent is not particularly limited and may be 0.1 seconds to 100 hours, 1 second to 50 hours, or 1 second to 20 hours.

[0195] The amount of treatment agent to be brought into contact 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, even more preferably 10 g or more, and particularly preferably 100 g or more, per 1,000 g of fluoropolymer in the aqueous dispersion.

[0196] After bringing the aqueous dispersion into contact with the treatment agent, the aqueous dispersion and the treatment agent can be separated, and the aqueous dispersion can be recovered.

[0197] The method of contacting the aqueous dispersion with the treatment agent may be a batch method or a fluid method.

[0198] The number of times the aqueous dispersion and the treatment agent are brought into contact may be once or two or more times. By repeating the contact between the aqueous dispersion and the treatment agent two or more times, the content of hydrophilic fluorine-containing compounds in the aqueous dispersion can be further reduced. The number of times the aqueous dispersion and the treatment agent are brought into contact may be 10 times or less.

[0199] For contacting the aqueous dispersion with the treatment agent, conventional methods can be employed. For example, this can be done by adding the treatment agent to the aqueous dispersion and stirring, or by the column method, in which the aqueous dispersion is flowed through a column packed with the treatment agent. The packed column used in the column method may be a mobile, fixed-bed, or fluidized-bed type.

[0200] When using a method in which a treatment agent is added to an aqueous dispersion and stirred, the treatment agent and the aqueous dispersion are separated after contact with the aqueous dispersion. The method of separating the treatment agent and the aqueous dispersion is not limited, and methods such as filtration can be used.

[0201] Furthermore, by increasing the contact area between the aqueous dispersion and the treatment agent, or the exchange capacity of the ion exchange resin, the same treatment efficiency as when the contact between the aqueous dispersion and the treatment agent is repeated multiple times can be obtained. In particular, when using a column method in which the aqueous dispersion is flowed through a column packed with the treatment agent, it is preferable to increase the contact area between the aqueous dispersion and the treatment agent, or the exchange capacity of the ion exchange resin.

[0202] The contact area (surface area) of the treatment agent is preferably 0.0020 m² relative to the mass of the fluoropolymer in the aqueous dispersion. 2 It is 1 / g or more, and more preferably 0.0030m 2 It is 1 / g or more, and more preferably 0.0040m 2 It is 1 / g or more, and particularly preferably 0.0050m 2 The value must be at least / g, and there is no particular upper limit, but for example, 5.0m 2 It may be less than or equal to / g.

[0203] The exchange capacity of the ion exchange resin is preferably 0.25 meq / g or more, preferably 0.50 meq / g or more, preferably 1.00 meq / g or more, and preferably 1.50 meq / g or more, relative to the mass of the fluoropolymer in the aqueous dispersion. There is no particular upper limit, but for example, it may be 2500 meq / g or less.

[0204] An anion exchange resin can be suitably used as the ion exchange resin. An anion exchange resin can be expressed using the following general formula (A1): -N + R 1 R 2 R 3 X - (In the formula, R 1 , R 2 and R 3 R is the same or different hydrogen atom or organic group. 1 , R 2 and R 3At least one of them is an organic group with 3 or more carbon atoms. X represents the counterion. An ion exchange group represented by the following general formula (A2): -NR 4 R 5 (In the formula, R 4 and R 5 R is the same or different hydrogen atom or organic group. 4 and R 5 A resin having an ion exchange group represented by (at least one of which is an organic group with 2 or more carbon atoms) is preferred.

[0205] In general formula (A1), R 1 , R 2 and R 3 R is either the same or different hydrogen atom or organic group. 1 , R 2 and R 3 The group may consist entirely of organic groups, or it may consist of one hydrogen atom and two organic groups. Furthermore, it may consist of two hydrogen atoms and one organic group. The above organic groups have one or more carbon atoms. Preferably, the above organic groups have two or more carbon atoms. The above R 1 , R 2 and R 3 One preferred form is an organic group having two or more carbon atoms.

[0206] In general formula (A1), R 1 , R 2 and R 3 At least one of them is an organic group with 3 or more carbon atoms. 1 , R 2 and R 3 Of these, one may be an organic group having 3 or more carbon atoms, and the other two may be hydrogen atoms or organic groups 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. R 1 , R 2 and R 3 All of these may be organic groups having 3 or more carbon atoms.

[0207] R 1 , R 2and R 3 In this case, 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 also be 5 or less.

[0208] In general formula (A1), R 1 , R 2 and R 3 Preferably, at least one of the components is an organic group with four or more carbon atoms. By adopting such a configuration, specific fluorine-containing compounds can be removed more efficiently.

[0209] 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.

[0210] In this disclosure, "alkyl group" is a general term for the remaining groups obtained by removing one hydrogen atom from an aliphatic saturated hydrocarbon, and includes linear or branched alkyl groups having one or more carbon atoms, or cyclic alkyl groups having three or more carbon atoms.

[0211] Furthermore, in this disclosure, "alkanol group" is a general term for the remaining group after removing one hydrogen atom from an alkanol, and includes linear or branched alkanol groups having one or more carbon atoms, or cyclic alkanol groups having three or more carbon atoms.

[0212] R 1 , R 2 and R 3 R is the same or different alkyl group having 2 or more carbon atoms or an alkanol group having 1 or more carbon atoms, 1 , R 2 and R 3 Preferably, at least one of them is an alkyl group having 3 or more carbon atoms.

[0213] R 1 , R 2 and R 3R is the same or different alkyl group having 2 or more carbon atoms or an alkanol group having 2 or more carbon atoms, 1 , R 2 and R 3 A more preferred configuration is one in which at least one of the elements is an alkyl group having 3 or more carbon atoms.

[0214] R 1 , R 2 and R 3 Furthermore, R is either the same or different alkyl group having 2 or more carbon atoms or an alkanol group having 1 or more carbon atoms. 1 , R 2 and R 3 A preferred configuration is that at least one of the elements is an alkyl group having four or more carbon atoms.

[0215] Also, R 1 , R 2 and R 3 These are identical or different alkyl groups having 2 or more carbon atoms or alkanol groups having 2 or more carbon atoms, and R 1 , R 2 and R 3 A preferred configuration is that at least one of the elements is an alkyl group having four or more carbon atoms.

[0216] The alkyl group preferably has 10 or fewer carbon atoms, more preferably 8 or fewer, and even more preferably 6 or fewer. The alkyl group may also have 5 or fewer carbon atoms.

[0217] 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 also be 5 or less.

[0218] In general formula (A1), X is a counterion. Examples of X include Cl, OH, Br, I, NO3, SO4, etc., with Cl or OH being preferred. In the case of a divalent anion such as SO4, one counterion coordinates to two repeating units of general formula (A1).

[0219] In general formula (A2), R 4and R 5 R is the same or different hydrogen atom or organic group. 4 and R 5 At least one of them is an organic group with 2 or more carbon atoms. 4 and R 5 It may be entirely composed of organic groups. Alternatively, one may be a hydrogen atom and one may be an organic group.

[0220] In general formula (A2), R 4 and R 5 At least one of them is an organic group with two or more carbon atoms.

[0221] R 4 and R 5 Of these, 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. Also, R 4 and R 5 Both may be organic groups having 2 or more carbon atoms.

[0222] R 4 and R 5 At least one of these may be an organic group having 3 or more carbon atoms, or an organic group having 4 or more carbon atoms.

[0223] Also, R 4 and R 5 It is also preferable that the organic group has two or more carbon atoms.

[0224] R 4 and R 5 In this case, 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 also be 5 or less.

[0225] The above 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.

[0226] R 4and R 5 The above R is the same or different alkyl group or alkanol group, 4 and R 5 A more preferred form is that at least one of the members is an alkyl group having 2 or more carbon atoms or an alkanol group having 2 or more carbon atoms.

[0227] The alkyl group preferably has 10 or fewer carbon atoms, more preferably 8 or fewer, and even more preferably 6 or fewer. The alkyl group may also have 5 or fewer carbon atoms.

[0228] 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 above alkanol group may also be 5 or less.

[0229] 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 the resin matrix. An example of an anion exchange resin is one 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 as the resin matrix is ​​not limited, but for example, a resin matrix used in known anion exchange resins can be used. From the viewpoint of the removal efficiency of fluorine-containing compounds having hydrophilic groups, the resin matrix of the anion exchange resin is preferably styrene-based.

[0230] The basicity of anion exchange resins can be set in various ways depending on the type of polymer backbone and / or ion exchange group.

[0231] The anion exchange resin preferably has a pore diameter of 1 to 5000 Å. From the viewpoint of removal efficiency, a pore diameter of 50 Å or more is preferable, 100 Å or more is more preferable, and 150 Å or more is even preferable. It may also be 200 Å or more, or 250 Å or more. Furthermore, the pore diameter may be 1000 Å or less. The pore diameter can be calculated, for example, by measuring the specific surface area and total pore volume using a gas adsorption method.

[0232] From the viewpoint of removal efficiency, the anion exchange resin is preferably given a total exchange capacity of 0.1 eq / L-Resin or more. More preferably, it is 0.3 eq / L-Resin or more, even more preferably, 0.5 eq / L-Resin or more, and particularly preferably, 0.7 eq / L-Resin or more. Furthermore, the upper limit is preferably 5.0 eq / L-Resin or less, more preferably 3.0 eq / L-Resin or less, and particularly preferably 2.0 eq / L-Resin or less.

[0233] The moisture content of the anion exchange resin is preferably 20% by mass or more, more preferably 30-70% by mass, and even more preferably 35-65% by mass. A moisture content of 30% by mass or more in the anion exchange resin allows for efficient removal of the fluorine-containing compound. Furthermore, the fluorine-containing compound can easily diffuse into the particles of the anion exchange resin. If the moisture content of the anion exchange resin is 70% by mass or less, the decrease in the strength of the anion exchange resin particles due to insufficient crosslinking can be suppressed.

[0234] The moisture content of anion exchange resin can be measured by the following method. First, accurately measure 10 mL of the standardized sample using a graduated cylinder. Wrap this resin in cloth and centrifuge to remove any adhering moisture, then quickly measure the mass of the resin. Next, dry the resin in a constant temperature drying oven at 105°C for 4 hours, then allow it to cool in a desiccator for 30 minutes. Measure 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

[0235] Anion exchange resins are typically 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 is within the above range, the packed column of the anion exchange resin is less likely to become clogged. The above average particle size is a value obtained by sieving. 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 corresponding to 50% of the residual classifier is determined and this is taken as the average particle size.

[0236] Commercially available anion exchange resins can be used, such as PFA694E and A592E manufactured by Purolite Co., Ltd.

[0237] Furthermore, a resin having an ion exchange group (excluding the group represented by general formula (A1) and general formula (A2) above) can also be used as the anion exchange resin. 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 group represented by general formula (A1) and general formula (A2) above). An example of such an anion exchange resin is the following general formula (B1): -N + (CH3)3X - A group represented by (wherein X represents the counterion) or the following general formula (B2): -N + (CH3)2(C2H4OH)X - A group represented by (wherein X represents a counterion) is preferred. Examples of X in general formulas (B1) and (B2) include Cl, OH, Br, I, NO3, SO4, etc., with Cl or OH being preferred. In the case of a divalent anion such as SO4, one counterion coordinates to two repeating units of general formula (A1).

[0238] The anion exchange resin preferably has ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2)) 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, but for example, resin matrices used in known anion exchange resins can be used. From the viewpoint of removal efficiency of fluorine-containing compounds having hydrophilic groups, it is preferable that the resin matrix of anion exchange resin B is styrene-based.

[0239] The resin having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) may be weakly basic or strongly basic. Preferably, it is a strongly basic anion exchange resin. The basicity of the anion exchange resin can be set in various ways depending on the polymer backbone and / or the type of ion exchange groups.

[0240] Resins having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) preferably have a pore diameter of 1 to 5000 Å. From the viewpoint of removal efficiency, a pore diameter of 50 Å or more is preferable, 100 Å or more is more preferable, and 150 Å or more is even preferable. It may also be 200 Å or more, or 250 Å or more. Furthermore, the pore diameter may be 1000 Å or less. The pore diameter can be calculated, for example, by measuring the specific surface area and total pore volume using the gas adsorption method.

[0241] Resins having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) are preferably given a total exchange capacity of 0.1 eq / L-Resin or more from the viewpoint of removal efficiency. More preferably, it is 0.3 eq / L-Resin or more, even more preferably 0.5 eq / L-Resin or more, and particularly preferably 0.7 eq / L-Resin or more. While a larger total exchange capacity is preferable, for example, the upper limit is preferably 5.0 eq / L-Resin, more preferably 3.0 eq / L-Resin or less, and particularly preferably 2.0 eq / L-Resin or less.

[0242] The moisture content of the resin having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) is preferably 20% by mass or more, more preferably 30-70% by mass, and even more preferably 35-65% by mass.

[0243] Resins having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) are usually spherical. The average particle size of the resin having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above) 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 will be less likely to become clogged. The above average particle size is a value obtained by the 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 corresponding to 50% of the residual classification is determined and this is taken as the average particle size.

[0244] As the resin having ion exchange groups (excluding the groups represented by general formula (A1) and general formula (A2) above), commercially available products may be used. For example, the Diaion® SA series from Mitsubishi Chemical Corporation, A400, A300, etc. from Purolite Corporation, and the Amberlite® series, IRA4002OH, etc. from DuPont, can be used.

[0245] As the ion exchange resin, 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, is preferred. Among these, OH is preferred as X in general formulas (B1) and (B2).

[0246] Synthetic adsorbents can be used as adsorbents. Synthetic adsorbents are porous resins that do not have ion exchange groups, and known synthetic adsorbents can be used. Examples of ion exchange groups include amino groups, quaternary ammonium groups, carboxylic acid groups, sulfonic acid groups, etc. Specific examples of synthetic adsorbents include styrene resins such as styrene-divinylbenzene copolymers, acrylic resins such as (meth)acrylic acid ester-ethylene glycol dimethacrylate copolymers, methacrylic resins, polyvinyl resins, dextran resins, etc. Commercially available synthetic adsorbents include, specifically, styrene-based resins such as Diaion HP10, Diaion HP20, Diaion HP21, Diaion HP40, Diaion HP50, Sepapies SP207, Sepapies SP70, Sepapies SP825, Sepapies SP850, Sepapies SP207 (all manufactured by Mitsubishi Chemical Corporation), Amberlite XAD1180N, Amberlite XAD2000, Amberlite XAD4, Amberlite FPX66 (all manufactured by Organo Corporation), etc.; and acrylic-based resins such as Diaion HP2MG (manufactured by Mitsubishi Chemical Corporation) and Amberlite HXAD-7HP (manufactured by Organo Corporation), etc.

[0247] The synthetic adsorbent preferably has a pore diameter of 1 to 5000 Å. From the viewpoint of removal efficiency, a pore diameter of 50 Å or more is preferable, 100 Å or more is more preferable, and 150 Å or more is even preferable. It may also be 200 Å or more, or 250 Å or more. Furthermore, the pore diameter may be 1000 Å or less. The pore diameter can be calculated, for example, by measuring the specific surface area and total pore volume using a gas adsorption method.

[0248] Synthetic adsorbents have a specific surface area of ​​300 m². 2 It is preferable that the amount is 1 / g or more. The specific surface area is 400 m². 2 More preferably 500m / g or more. 2 More preferably 600m / g or more. 2 A value of 2000 m² or more is particularly preferable. There is no upper limit to the specific surface area, but for example, 2000 m² is preferable. 2 It may be less than or equal to / g, and 1500m 2 It may be less than or equal to / g, and 1000m 2 The amount may be less than / g. Furthermore, the synthetic adsorbent is usually spherical, and the average particle size of the synthetic adsorbent is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.5 mm, even more preferably 0.2 to 1.3 mm, and particularly preferably 0.3 to 1.0 mm, from the viewpoint of removal efficiency. The average particle size of the synthetic adsorbent refers to the 50% mass value obtained by plotting the integrated mass after classification by sieving on a graph.

[0249] From the viewpoint of improving removal efficiency, synthetic adsorbents preferably contain water. The water content is preferably 20 to 80% by mass, more preferably 40 to 75% by mass, and particularly preferably 50 to 70% by mass.

[0250] Activated carbon can be produced from carbonaceous materials. Examples of carbonaceous materials include any material that produces activated carbon through carbonization or activation, such as wood, sawdust, charcoal, fruit shells like coconut shells and walnut shells, plant-based materials like fruit seeds, coal such as peat, lignite, brown coal, bituminous coal, and anthracite, pitch such as petroleum pitch and coal pitch, tar such as coke, coal tar, and petroleum tar, mineral-based materials such as petroleum distillation residues, natural materials such as cotton and rayon cellulose fibers, and synthetic materials such as phenolic resins, polyvinyl alcohol, and polyacrylonitrile. The material can be in powder, granular, or fibrous form, or molded from these forms.

[0251] Activated carbon has a specific surface area of ​​500 m². 2 It is preferable that the amount is 1 / g or more. The specific surface area is 1000 m². 2 More preferably 1500m / g or more, 2 More preferably 1800m / g or more. 2 A value of 2000m or more is particularly preferred. 2 A value of 1 / g or higher is particularly preferred. There is no upper limit to the specific surface area, but for example, 2500 m² is preferable. 2 The amount may be / g. The shape of the activated carbon is not particularly limited and may be, for example, pelletized, granular, powdered, or spherical particles. The activated carbon may be a commercially available product. Examples of commercially available activated carbon include Shirasagi (trademark) from Osaka Gas Chemical Co., Ltd., Filtrasorb (trademark) CAL, Diahope (trademark), Diasorb (trademark) from Calgon Carbon Japan Co., Ltd., and the Evadia (trademark) series from Suing Co., Ltd.

[0252] Activated carbon is preferably equipped with improved adsorption performance through steam activation treatment. In the steam activation treatment, it is preferable to expose the activated carbon to steam at a temperature of 120°C or higher, for example, 130 to 350°C, particularly 150 to 1000°C, and at a pressure of 0.2 MPa or higher, for example, 0.5 to 15 MPa, particularly 1 to 15 MPa. The steam activation treatment time is generally 10 seconds to 50 hours, for example, 10 minutes to 10 hours. Heating in a furnace may be performed during activation.

[0253] Cations may be impregnated onto the surface of activated carbon. Examples of cations include metal ions, metal oxide ions, and ammonium ions. Examples of metals include metal atoms from groups 1 to 13 of the periodic table (e.g., alkali metals (e.g., Li, Na, K), alkaline earth metals (e.g., Mg, Ca), Ti, Zr, V, Cr, Fe, Ni, Cu, Zn).

[0254] (Addition of nonionic surfactant to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment) In one embodiment of the manufacturing method of the present disclosure, a nonionic surfactant is added to the aqueous dispersion obtained after contact with the treatment agent. By adding a nonionic surfactant, the dispersibility of the fluoropolymer in the aqueous dispersion that has undergone ion exchange treatment or adsorption treatment can be improved, and the concentration of the aqueous dispersion can be carried out smoothly. As a result, the content of fluorine-containing compounds having hydrophilic groups in the aqueous dispersion can be reduced to a remarkable degree, and an aqueous dispersion with excellent dispersion stability can be produced.

[0255] Examples of nonionic surfactants to be added to the aqueous dispersion obtained after contact with the treatment agent include those exemplified as nonionic surfactants to be added to the aqueous dispersion obtained by polymerization. Nonionic surfactants that can be suitably used as additives to the aqueous dispersion obtained by polymerization can also be suitably used as nonionic surfactants to be added to the aqueous dispersion obtained after contact with the treatment agent.

[0256] It is preferable to prepare an aqueous dispersion in which the content of the nonionic surfactant in the aqueous dispersion is 1 to 40% by mass relative to the fluoropolymer, by adding a nonionic surfactant to an aqueous dispersion that has been treated with ion exchange or adsorption. More preferably, the content of the nonionic surfactant in the aqueous dispersion that has been treated with ion exchange or adsorption is 5% by mass or more, and more preferably 30% by mass or less.

[0257] (Concentration process) In the manufacturing method of this disclosure, the aqueous dispersion obtained after contact with the treatment agent may be concentrated.

[0258] Concentration methods include phase separation concentration, electrophoresis, ion exchange method, and membrane concentration. Phase separation concentration, ion exchange method, and membrane concentration can be carried out under conventionally known processing conditions and are not particularly limited, but can be carried out by the methods described in International Publication No. 2004 / 050719, Japanese Patent Publication No. 2002-532583, and Japanese Patent Publication No. 55-120630.

[0259] As for the concentration method, a method of separating the aqueous dispersion into two or more phases and recovering the concentrated phase is preferred, and phase separation concentration or concentration by electrophoresis is preferred, with phase separation concentration being more preferred. Phase separation concentration can be performed, for example, by heating the aqueous dispersion to separate it into a fluoropolymer-free phase (supernatant phase) and a fluoropolymer-containing phase (concentrated phase), removing the fluoropolymer-free phase, and recovering the fluoropolymer-containing phase (concentrated phase).

[0260] The recovered fluoropolymer-containing phase (concentrated phase) contains fluoropolymers, nonionic surfactants, and aqueous media, as well as fluorine-containing compounds with hydrophilic groups, but in reduced amounts compared to before concentration.

[0261] The temperature for phase separation and concentration can be selected based on the cloud point of the nonionic surfactant contained in the aqueous dispersion. Preferably, the temperature for phase separation and concentration is 10°C or more lower than the cloud point of the nonionic surfactant, and preferably 10°C or less higher than the cloud point of the nonionic surfactant.

[0262] In the manufacturing method of this disclosure, it is also preferable to repeatedly perform phase separation and concentration. By repeatedly performing phase separation and concentration, the content of the hydrophilic fluorine-containing compound in the aqueous dispersion can be easily reduced to a desired content.

[0263] The number of repetitions is not particularly limited, but is preferably two or more, and more preferably three or more. There is no upper limit to the number of repetitions, but for example, it may be 10 or less. By repeatedly performing phase separation and concentration, the content of fluorine-containing compounds having hydrophilic groups can be further reduced.

[0264] When phase separation and concentration is performed two or more times, it is preferable that the first phase separation and concentration is performed by heating at a temperature at least 10°C below the cloud point of the nonionic surfactant, followed by standing, to separate the supernatant phase and the concentrated phase. Furthermore, it is preferable that the second or subsequent phase separation and concentration is performed by heating at a temperature at least 10°C below the cloud point of the nonionic surfactant, followed by standing, to separate the supernatant phase and the concentrated phase.

[0265] When repeating phase separation and concentration multiple times, except for the final phase separation and concentration, the phase separation and concentration can be stopped when the solid content concentration of the fluoropolymer in the aqueous dispersion reaches 48-52% by mass, an aqueous medium can be added to the concentrated aqueous dispersion, and the phase separation and concentration can be repeated. By stopping the phase separation and concentration when the solid content concentration of the fluoropolymer reaches the above range, each phase separation and concentration can be completed in a short time without reducing the removal efficiency of fluorine-containing compounds with hydrophilic groups in each phase separation and concentration, and as a result, the total time required for phase separation and concentration can be shortened.

[0266] The pH of the aqueous dispersion used for concentration is preferably 4.0 to 12.0, more preferably 7.0 or higher, even more preferably 8.0 or higher, and particularly preferably 9.0 or higher. By adjusting the pH of the aqueous dispersion within the above range, both the rate at which the concentration of the fluoropolymer in the aqueous dispersion is increased and the rate at which the hydrophilic fluorine-containing compounds in the aqueous dispersion are removed can be increased, resulting in a final aqueous dispersion with a high concentration of fluoropolymer.

[0267] The fluoropolymer content in the aqueous fluoropolymer dispersion obtained by concentration is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, preferably 75% by mass or less, more preferably 73% by mass or less, even more preferably 71% by mass or less, and particularly preferably 70% by mass or less, relative to the aqueous dispersion. The higher the fluoropolymer content in the aqueous fluoropolymer dispersion, the easier it is to maintain a high fluoropolymer content even when various additives are added to the aqueous fluoropolymer dispersion. Furthermore, after concentration, the aqueous dispersion may be diluted to adjust the fluoropolymer content.

[0268] The fluoropolymer content in an aqueous dispersion can be determined by measuring the solid content concentration and the nonionic surfactant content of the aqueous dispersion, and then subtracting the nonionic surfactant content from the solid content concentration of the aqueous dispersion. The solid content concentration of the aqueous dispersion is calculated from the residual content (Zg) obtained by heating approximately 1g (Xg) of the sample at 110°C for 30 minutes, and then further heating at 300°C for 30 minutes, according to the formula: P = Z / X × 100 (mass%).

[0269] (Treatment of aqueous dispersion) In the manufacturing method of this disclosure, a nonionic surfactant can be added to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment, or to a concentrated aqueous dispersion. In particular, when an aqueous dispersion is concentrated by phase separation concentration, the content of the nonionic surfactant in the resulting aqueous dispersion may decrease, but by adding a nonionic surfactant to the concentrated aqueous dispersion, the dispersibility of the fluoropolymer in the concentrated aqueous dispersion can be improved.

[0270] It is preferable to add two types of nonionic surfactants with different hydrophilicity to the aqueous dispersion. HLB can be used as an indicator of the difference in hydrophilicity; for example, it is preferable to include a nonionic surfactant with an HLB of 13.00 or more and less than 13.50, and a nonionic surfactant with an HLB of 13.50 or more and 15.00 or less (preferably 14.50 or less, more preferably 14.00 or less). Adding nonionic surfactants with different HLBs can also suppress foaming without the need for an antifoaming agent.

[0271] It is preferable to prepare an aqueous dispersion in which a nonionic surfactant is added to the aqueous dispersion, so that the content of the nonionic surfactant in the aqueous dispersion is 4.0 to 12.0% by mass relative to the fluoropolymer. More preferably, the content of the nonionic surfactant in the aqueous dispersion is 4.5% by mass or more, even more preferably 5.0% by mass or more, even 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.

[0272] In the manufacturing method of this disclosure, a viscosity modifier can be added to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment, or to a concentrated aqueous dispersion.

[0273] As viscosity modifiers, fluorine-free anionic surfactants can be suitably used. Fluorine-free anionic surfactants typically have a hydrophilic portion, such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion, such as a long-chain hydrocarbon portion, such as an alkyl group.

[0274] Examples of fluorine-free anionic surfactants include alkyl sulfates such as lauryl sulfate, alkylaryl sulfonic acids such as dodecylbenzenesulfonic acid, alkyl sulfosuccinates and their salts. The above fluorine-free anionic surfactants may be composed of one or more of these compounds.

[0275] Alkyl sulfosuccinates and their salts may be monoesters, but diesters are preferred.

[0276] Examples of alkyl sulfosuccinates and their salts include, for example, those with the general formula: R 21 -OCOCH(SO3A 21 )CH2COO-R 22 (In the formula, R 21 and R 22 These represent alkyl groups with 4 to 12 carbon atoms, which are the same or different. 21 ) represents alkali metals, alkaline earth metals, or NH4. Examples include alkyl sulfosuccinates and their salts.

[0277] R 21 and R 22 Examples 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.

[0278] A 21 Preferred elements include Na, NH4, etc. Examples of alkyl sulfosuccinates include di-n-octyl sulfosuccinate and di-2-ethylhexyl sulfosuccinate.

[0279] Fluorine-free anionic surfactants may have acidic groups. The acidic groups are preferably selected from the group consisting of carboxyl groups, sulfate groups, sulfonic acid groups, phosphate groups, and their salts, and among these, those selected from the group consisting of carboxyl groups, sulfate groups, and sulfonic acid groups, and their salts, are particularly preferred.

[0280] Fluorine-free anionic surfactants may also have other groups in addition to the acid group mentioned above, such as a polyoxyalkylene group having 2 to 4 carbon atoms, an amino group, etc. The amino group mentioned above is not protonated.

[0281] As a fluorine-free anionic surfactant, anionic hydrocarbon surfactants having a hydrocarbon as the main chain are preferred. Examples of hydrocarbons include those having saturated or unsaturated aliphatic chains with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms. The saturated or unsaturated aliphatic chain may be linear or branched, and may have a cyclic structure. The hydrocarbon may be aromatic or may have aromatic groups. The hydrocarbon may also have heteroatoms such as oxygen, nitrogen, or sulfur.

[0282] Examples of fluorine-free anionic surfactants include alkyl sulfonic acids such as lauryl sulfonic acid and their salts; alkylaryl sulfates and their salts; aliphatic (carbone) acids such as lauric acid and their salts; alkyl phosphates, alkylaryl phosphates, and their salts; and among these, those selected from the group consisting of sulfonic acids, carboxylic acids, and their salts are preferred, with aliphatic carboxylic acids or their salts being preferred. As the above aliphatic carboxylic acids or their salts, for example, saturated or unsaturated aliphatic carboxylic acids having 9 to 13 carbon atoms, or their salts, which may have terminal H substituted with -OH, are preferred, and as the aliphatic carboxylic acid, monocarboxylic acids are preferred, and as monocarboxylic acids, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, and hydroxydecanoic acid are preferred.

[0283] As a fluorine-free anionic surfactant, at least one selected from the group consisting of alkyl sulfosuccinates and their salts, alkyl sulfates and their salts, and monocarboxylic acids and their salts is preferred; at least one selected from the group consisting of dioctyl sulfosuccinate, lauryl sulfate, decanoic acid, and their salts is more preferred; and at least one selected from the group consisting of dioctyl sulfosuccinate, ammonium dioctyl sulfosuccinate, ammonium lauryl sulfate, and ammonium decanoate is even more preferred.

[0284] It is preferable to prepare an aqueous dispersion in which a viscosity modifier is added to the aqueous dispersion, so that the content of the viscosity modifier in the aqueous dispersion is 10 to 5000 ppm by mass relative to the fluoropolymer. More preferably, the content of the viscosity modifier in the aqueous dispersion is 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.

[0285] In the manufacturing method of this disclosure, a pH adjusting agent such as aqueous ammonia can be added to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment, or a concentrated aqueous dispersion, for the purpose of adjusting the pH of the aqueous dispersion. The pH of the aqueous dispersion is preferably 8 to 13, more preferably 9 to 12, and even more preferably 9 to 11.

[0286] The above pH can be measured at 25°C in accordance with JIS K6893.

[0287] In the manufacturing method of this disclosure, a preservative can be added to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment, or to a concentrated aqueous dispersion. By adding a preservative to the aqueous dispersion, even when the aqueous dispersion is stored for a long period of time, the settling of the fluoropolymer is suppressed, and the spoilage of the aqueous dispersion and the growth of bacteria can be suppressed.

[0288] Examples of preservatives include isothiazolone-based, azole-based, pronopol, chlorothalonil, methylsulfonyltetrachlorpyrozine, carbentadium, fluorophorbet, sodium diacetate, and diiodomethylparatolylsulfone.

[0289] It is preferable to prepare an aqueous dispersion in which the preservative content is 0.01 to 0.5% by mass relative to the fluoropolymer by adding a preservative to the aqueous dispersion. More preferably, the preservative content in the aqueous dispersion is 0.05% by mass or more, and more preferably 0.2% by mass or less.

[0290] In the manufacturing method of this disclosure, a water-soluble polymer may be added to an aqueous dispersion that has undergone ion exchange treatment or adsorption treatment, or to a concentrated aqueous dispersion. Examples of water-soluble polymer compounds include methylcellulose, 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.

[0291] 2. Fluoropolymer aqueous dispersion The manufacturing method of the present disclosure provides a fluoropolymer aqueous dispersion in which the content of a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms is reduced. The present disclosure provides a fluoropolymer aqueous dispersion containing a fluoropolymer, a nonionic surfactant, and a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms, wherein the fluoropolymer content is 50 to 75% by mass relative to the fluoropolymer aqueous dispersion, the nonionic surfactant content is 4.0 to 12% by mass relative to the fluoropolymer, and the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms is greater than 0 ppb by mass and less than 300 ppb by mass relative to the fluoropolymer aqueous dispersion.

[0292] The aqueous dispersion of fluoropolymers of this disclosure contains a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms. The content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the aqueous dispersion is greater than 0 ppb by mass and less than 300 ppb by mass relative to the aqueous dispersion. The preferred upper limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the aqueous dispersion is 280 ppb by mass or less, 260 ppb by mass or less, 240 ppb by mass or less, 220 ppb by mass or less, 200 ppb by mass or less, 180 ppb by mass or less, 160 ppb by mass or less, or 140 ppb by mass or less. The preferred lower limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the aqueous dispersion is 0.1 ppb by mass or more, 1 ppb by mass or more, 5 ppb by mass or more, 10 ppb by mass or more, 20 ppb by mass or more, 30 ppb by mass or more, or 40 ppb by mass or more.

[0293] Examples of fluorine-containing compounds having a hydrophilic group with 7 or fewer carbon atoms include those described above as fluorine-containing surfactants having 7 or fewer carbon atoms used in the polymerization of fluoromonomers. That is, in one embodiment of the aqueous dispersion, at least a fluorine-containing surfactant having 7 or fewer carbon atoms is included as a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms.

[0294] Furthermore, the manufacturing method of this disclosure makes it possible to reduce not only the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, but also the content of fluorine-containing compounds having hydrophilic groups in the aqueous dispersion of fluoropolymers.

[0295] In one embodiment of the fluoropolymer aqueous dispersion, a fluorine-containing compound having a hydrophilic group is contained. The content of the fluorine-containing compound having a hydrophilic group in the aqueous dispersion is greater than 0 ppb by mass and less than 300 ppb by mass relative to the aqueous dispersion. The preferred upper limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the aqueous dispersion is 280 ppb by mass or less, 260 ppb by mass or less, 240 ppb by mass or less, 220 ppb by mass or less, 200 ppb by mass or less, 180 ppb by mass or less, 160 ppb by mass or less, or 140 ppb by mass or less. The preferred lower limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the aqueous dispersion is 0.1 ppb by mass or more, 1 ppb by mass or more, 5 ppb by mass or more, 10 ppb by mass or more, 20 ppb by mass or more, 30 ppb by mass or more, or 40 ppb by mass or more.

[0296] Examples of fluorine-containing compounds having hydrophilic groups include those described above as fluorine-containing surfactants used in the polymerization of fluoromonomers. That is, in one embodiment of the aqueous dispersion, at least a fluorine-containing surfactant is contained as the fluorine-containing compound having hydrophilic groups. Typical compounds as fluorine-containing surfactants are fluorine-containing surfactants with a molecular weight of 1000 g / mol or less, preferably 800 g / mol or less.

[0297] In one embodiment of the fluoropolymer aqueous dispersion, the compound represented by the following general formula (1) is substantially not included as a fluorine-containing compound having a hydrophilic group. General formula (1): [X-Rf-A - ] i M i+ (wherein X is H, Cl, Br, F or I, Rf is a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain, or a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain interrupted by at least one oxygen atom, A - is an acid group, M i+ (where i is a cation with a valency of i, and i is an integer between 1 and 3)

[0298] In one embodiment of the fluoropolymer aqueous dispersion, the fluorine-containing compound having a hydrophilic group is substantially free of the compound represented by the following general formula (2). General formula (2):[C n-1 F 2n-1 COO - ]M + (In the formula, n is an integer between 9 and 14, M + (This represents a cation.)

[0299] Compounds represented by general formula (2) (perfluoroalkanoic acid) are known to be formed during polymerization when perfluoroalkyl vinyl ethers or the like are used as modified monomers (see International Publication No. 2019 / 161153).

[0300] In one embodiment of the fluoropolymer aqueous dispersion, the compound represented by the following general formula (3) is substantially not included as a fluorine-containing compound having a hydrophilic group. General formula (3):[R 1 -OL-CO2 - ]M + (In the formula, R 1 L is a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain, or a partially fluorinated or fully fluorinated aliphatic group of a linear or branched chain interrupted by at least one oxygen atom, L is a non-fluorinated, partially fluorinated or fully fluorinated alkylene group of a linear or branched chain, M + (This represents a cation.)

[0301] In one embodiment of the aqueous dispersion of fluoropolymer, the fluorine-containing compound having a hydrophilic group is substantially free of the compound represented by general formula (4). General formula (4):[H-(CF2) m CO2 - ]M + (In the formula, m is an integer from 3 to 19, M + (This represents a cation.)

[0302] In this disclosure, "substantially free of any of the compounds represented by general formulas (1) to (4)" means that the content of any of the compounds represented by general formulas (1) to (4) in the aqueous fluoropolymer dispersion is 50 ppb by mass or less. The content of any of the compounds represented by general formulas (1) to (4) in the aqueous fluoropolymer dispersion is preferably 35 ppb by mass or less, more preferably 25 ppb by mass or less, even more preferably 10 ppb by mass or less, even more preferably 1 ppb by mass or less, and particularly preferably the fluorine-containing surfactant is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0303] The content of hydrophilic, fluorine-containing compounds in aqueous dispersions of fluoropolymers can be quantified by known methods. For example, it can be quantified by LC / MS analysis. First, methanol is added to the aqueous dispersion of fluoropolymer, and extraction is performed. The resulting extract is then analyzed by LC / MS. To further improve extraction efficiency, treatments such as Soxhlet extraction or sonication may be performed. The obtained extract is concentrated by nitrogen purging as appropriate, and fluorine-containing compounds with hydrophilic groups in the concentrated extract are measured by LC / MS. From the obtained LC / MS spectrum, molecular weight information is extracted and its agreement with the structural formula of a candidate fluorine-containing compound having a hydrophilic group is confirmed. Subsequently, aqueous solutions containing five or more levels of the identified hydrophilic fluorine-containing compound were prepared. LC / MS analysis was performed on each aqueous solution with its respective content, and the relationship between the content and the area of ​​the solution was plotted to create a calibration curve. Furthermore, using a calibration curve, the area of ​​the LC / MS chromatogram of the hydrophilic fluorine-containing compound in the extract can be converted to the content of the hydrophilic fluorine-containing compound. Furthermore, since the obtained extract can be concentrated by purging with nitrogen, the lower limit of quantification in the measurement method can be lowered.

[0304] The fluoropolymer contained in the aqueous dispersion of fluoropolymers in this disclosure will be described later.

[0305] The fluoropolymer content in the aqueous fluoropolymer dispersion is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 57% by mass or more, even more preferably 60% by mass or more, preferably 75% by mass or less, more preferably 73% by mass or less, even more preferably 71% by mass or less, even more preferably 70% by mass or less, and particularly preferably 69% by mass or less, relative to the aqueous dispersion.

[0306] Examples of nonionic surfactants include nonionic surfactants that can be used in the manufacturing method of the present disclosure. The content of the nonionic surfactant in the aqueous dispersion of the fluoropolymer is 4.0 to 12% by mass, 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, relative to the fluoropolymer.

[0307] The aqueous fluoropolymer dispersion of the present disclosure may also preferably contain a fluorine-free anionic surfactant. Examples of fluorine-free anionic surfactants include fluorine-free anionic surfactants that can be used in the manufacturing method of the present disclosure. The content of the fluorine-free anionic surfactant 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.

[0308] 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, 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.

[0309] The viscosity of the aqueous dispersion is measured using a Type B rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 2) under the following conditions: rotation speed of 60 rpm, measurement time of 120 seconds, and temperature of 25°C.

[0310] The aqueous fluoropolymer dispersion of the present disclosure may also preferably contain a preservative. Examples of preservatives include those that can be used in the manufacturing method of the present disclosure. 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.

[0311] The pH of the aqueous dispersion of the fluoropolymer according to this disclosure is preferably 8 to 13, more preferably 9 to 12, and even more preferably 9 to 11.

[0312] The above pH can be measured at 25°C in accordance with JIS K6893.

[0313] The aqueous dispersion of fluoropolymers of this disclosure may contain other components. Examples of other components include water-soluble polymer compounds. Examples of water-soluble polymer compounds include methylcellulose, 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.

[0314] The fluoropolymer aqueous dispersion of this disclosure can be used as an aqueous coating by, for example, compounding it with known pigments, thickeners, dispersants, defoamers, antifreezes, film-forming aids, or by further compounding it with other polymer compounds.

[0315] Next, the fluoropolymer in the aqueous dispersion obtained by the manufacturing method of the present disclosure, and the fluoropolymer in the aqueous dispersion of the present disclosure will be described in more detail.

[0316] (Fluoropolymer) Fluoropolymers such as fluororesins and fluororubbers can be obtained by polymerization of fluoromonomers.

[0317] Examples of fluoropolymers include TFE polymers, in which the monomer with the highest mole fraction in the polymer (hereinafter referred to as "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.

[0318] The above fluoropolymer preferably has an ion exchange rate (IXR) higher than 53. Preferred fluoropolymers either have no ionic groups at all or have a limited number of ionic groups that result in an ion exchange rate higher than about 100. The ion exchange rate of the preferred fluoropolymer is preferably 1000 or higher, more preferably 2000 or higher, and even more preferably 5000 or higher.

[0319] The TFE polymer may preferably be a TFE homopolymer, or a copolymer consisting of (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 above (3) other monomers include fluoro(alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms; fluorodioxole; perfluoroalkylethylene; ω-hydroperfluoroolefin, etc.

[0320] 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.

[0321] The VDF polymer may preferably be a VDF homopolymer [PVDF], or a copolymer consisting 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.

[0322] The CTFE polymer may preferably 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.

[0323] The CTFE polymer may also be a copolymer of CTFE and one or more fluorine-free monomers, and examples of the fluorine-free monomers include alkenes such as ethylene and propylene; vinyl esters; vinyl ethers, etc.

[0324] The above-mentioned fluoropolymers may be glassy, ​​plastic, or elastomeric. These may be amorphous or partially crystalline and can be subjected to compression firing, melting, or non-melting processes.

[0325] In the manufacturing method of the present disclosure, it is preferable to produce a fluororesin as the fluoropolymer. The aqueous dispersion of the fluoropolymer of the present disclosure preferably contains a fluororesin as the fluoropolymer.

[0326] In the manufacturing method of the present disclosure, for example, (I) tetrafluoroethylene polymer [TFE polymer (PTFE)] can be suitably produced as a non-melt-processable fluororesin, and (II) ethylene / TFE copolymer [ETFE], TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoroallyl ether copolymer, TFE / VDF copolymer, and electrolyte polymer precursors can be suitably produced as melt-processable fluororesins.

[0327] As the fluoropolymer mentioned above, fluororesins are preferred, and among them, fluororesins with a fluorine substitution rate of 50% or more calculated by the following formula are more preferred, fluororesins with a fluorine substitution rate exceeding 50% are even more preferred, fluororesins with a fluorine substitution rate of 55% or more are even more preferred, fluororesins with a fluorine substitution rate of 60% or more are even more preferred, fluororesins with a fluorine substitution rate of 75% or more are even more preferred, fluororesins with a fluorine substitution rate of 80% or more are particularly preferred, and fluororesins with a fluorine substitution rate of 90-100%, i.e., perfluororesins, are 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 and chlorine atoms bonded to carbon atoms constituting the fluoropolymer)) × 100

[0328] The above-mentioned fluoropolymer may have a core-shell structure. Examples of fluoropolymers having a core-shell structure include modified PTFE, which contains a high molecular weight PTFE core and a lower molecular weight PTFE or modified PTFE shell in the particles. Examples of such modified PTFE include the PTFE described in Japanese Patent Publication No. 2005-527652.

[0329] The above core-shell structure can take the following forms: Core: TFE monopolymer Shell: TFE monopolymer Core: Modified PTFE, Shell: TFE monopolymer Core: Modified PTFE Shell: Modified PTFE Core: TFE monopolymer; Shell: Modified PTFE Core: Low molecular weight PTFE Shell: High molecular weight PTFE Core: High molecular weight PTFE Shell: Low molecular weight PTFE

[0330] In the fluoropolymer having the above-described 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, still 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, still more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0331] In the fluoropolymer having the above-described 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, still 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, still more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0332] In the fluoropolymer having the above-described core-shell structure, the core or the shell may also be composed of two or more layers. For example, a fluoropolymer may have a three-layer structure comprising a core center of modified PTFE, an outer core layer of TFE homopolymer, and a shell of modified PTFE.

[0333] Examples of fluoropolymers having the above-mentioned core-shell structure include those in which a single particle of the fluoropolymer has multiple cores.

[0334] The above-mentioned (I) non-melt-processable fluororesin and (II) melt-processable fluororesin, which are suitably produced by the manufacturing method of the present disclosure, are preferably produced in the following manner.

[0335] (I) Non-melt processable fluororesin In the manufacturing method of this disclosure, polymerization of TFE is usually carried out at a polymerization temperature of 10 to 150°C and a polymerization pressure of 0.05 to 5 MPaG. For example, the polymerization temperature is more preferably 30°C or higher, and even more preferably 50°C or higher. It is also 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, even more preferably 0.5 MPaG or higher, even more preferably 5.0 MPaG or lower, and even more preferably 3.0 MPaG or lower. In particular, from the viewpoint of improving the yield of fluoropolymer, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, even more preferably 1.5 MPaG or higher, and even more preferably 2.0 MPaG or higher.

[0336] In one embodiment, the polymerization is carried out by charging pure water into a pressure-resistant reaction vessel equipped with a stirrer, deoxygenating it, charging TFE, raising it to a predetermined temperature, and adding a polymerization initiator to start the reaction. If the pressure decreases as the reaction progresses, 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 the pressure from decreasing.

[0337] In the production of the above-mentioned TFE polymer (PTFE), various known modified monomers can also be used in combination. In this disclosure, the term "TFE polymer" is a concept that includes not only TFE homopolymers but also copolymers of TFE and modified monomers that are non-melt processable (hereinafter referred to as "modified PTFE").

[0338] The above-mentioned modified monomers are not particularly limited as long as they can copolymerize with TFE, and include fluoromonomers and non-fluoromonomers. Furthermore, one or more modified monomers may be used.

[0339] The non-fluoro monomer is not particularly limited, and the general formula is: CH2=CR Q1 -LR Q2 (In the formula, R Q1 represents a hydrogen atom or alkyl group. L represents a single bond, -CO-O-*, -O-CO-*, or -O-. * is R Q2 This indicates the bond position with R. Q2 Examples of monomers represented by ) are: (where represents a hydrogen atom, an alkyl group, or a nitrile group.)

[0340] Examples of nonfluoro monomers 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, and cyclohexyl vinyl ether. Among these, butyl methacrylate, vinyl acetate, and acrylic acid are preferred as nonfluoro monomers.

[0341] 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)ethylene; and perfluoroallyl ethers.

[0342] The above perfluorovinyl ether is not particularly limited, for example, general formula (A): CF2 = CF - ORf (A) Examples include perfluorounsaturated compounds represented by the formula (wherein Rf represents a perfluoroorganic group). In this disclosure, the term "perfluoroorganic group" means an organic group in which all hydrogen atoms bonded to a carbon atom are replaced with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0343] Examples of the perfluorovinyl ethers mentioned above include perfluoro(alkyl vinyl ether) [PAVE] in which 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.

[0344] Examples of perfluoroalkyl groups in the above-mentioned PAVE include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl groups.

[0345] The above perfluorovinyl ethers are further defined as those in general formula (A) where Rf is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and where Rf is in the following formula:

[0346] [ka]

[0347] (In the formula, m represents an integer from 0 to 4.) The base is represented by the following formula, where Rf is:

[0348] CF3CF2CF2-(O-CF(CF3)-CF2) n - Examples include the base represented by (wherein n represents an integer from 1 to 4).

[0349] 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).

[0350] (Perfluoroalkyl)ethylene (PFAE) is not particularly limited and examples include (perfluorobutyl)ethylene (PFBE), (perfluorohexyl)ethylene, etc.

[0351] Examples of perfluoroallyl ethers include, General formula: CF2=CF-CF2-ORf Examples of fluoromonomers represented by the formula (wherein Rf represents a perfluoroorganic group) include:

[0352] The Rf in the above general formula is the same as the Rf in general formula (A). As Rf, a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. As the perfluoroallyl ether, 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.

[0353] As the above modified monomer, a modified monomer (3) having a monomer reactivity ratio of 0.1 to 8 is also preferably exemplified. By including the modified monomer (3), PTFE particles with a small particle size can be obtained, and an aqueous dispersion with high dispersion stability can be obtained.

[0354] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant when a growing radical reacts with TFE (when the growing radical is less than the repeating unit based on TFE) by the rate constant when the growing radical reacts with the modified monomer. A lower value indicates that the modified monomer is highly reactive with TFE. The monomer reactivity ratio can be calculated by determining the composition of the resulting polymer immediately after copolymerization of TFE and a modified monomer, and then using the Feynman-Ross equation.

[0355] The above copolymerization is 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 modified monomer are added to the reactor, and 0.072 g of ammonium persulfate (20 ppm by mass relative to water) is added. TFE is continuously supplied to maintain the polymerization pressure of 0.78 MPaG. When the amount of TFE added reaches 1000 g, stirring is stopped and the reactor is depressurized until the pressure reaches atmospheric pressure. After cooling, the paraffin wax is separated to obtain an aqueous dispersion containing the resulting polymer. The aqueous dispersion is stirred to coagulate the resulting polymer and dried at 150°C. The composition of the obtained polymer is measured by NMR. The results are calculated by appropriately combining FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0356] 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 (These are perfluoroalkyl groups with 1 to 10 carbon atoms.) CF2 = CF - O - Rf 2 (3b) (In the formula, Rf 2 (It is a perfluoroalkyl group with 1 to 2 carbon atoms.) CF2 = CF - O - (CF2) n CF = CF²(3c) (In the formula, n is either 1 or 2.)

[0357] [ka] (In the formula, X 3 and X 4 (where is F, Cl, or a methoxy group, and Y is formula Y1 or Y2.)

[0358] [ka] (In formula Y2, Z and Z' are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0359] The content of modified monomer (3) units is preferably in the range of 0.00001 to 1.0 mass% relative to the total polymerization units of PTFE. The lower limit is more preferably 0.0001 mass%, more preferably 0.0005 mass%, even more preferably 0.001 mass%, and even more preferably 0.005 mass%. The upper limits are, in order of preference, 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0360] As the above modified monomer, 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 and a hydrophilic group that can react by radical polymerization is preferred, as it allows for the production of an aqueous dispersion with a small average primary particle diameter, a small aspect ratio of primary particles, and excellent stability. By using the above modified monomer, an aqueous dispersion of PTFE with an even smaller average primary particle diameter, a smaller aspect ratio of primary particles, and excellent dispersion stability can be obtained. Furthermore, an aqueous dispersion with a small amount of uncoagulated polymer can be obtained.

[0361] From the viewpoint of reactivity with TFE, the above-mentioned modified monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene. More preferably, it contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. The total amount of the above-mentioned 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 the total polymerization units of PTFE. The lower limit of the above 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 preference, are 0.80% by mass, 0.70% 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.

[0362] The above-mentioned modified monomer may also preferably include a modified monomer having a functional group and a hydrophilic group that can react by radical polymerization (hereinafter referred to as "modified monomer (A)").

[0363] By including the above-mentioned modified monomer (A), PTFE particles with a small primary particle size can be obtained, and an aqueous dispersion with high dispersion stability can be obtained. Furthermore, the amount of uncoagulated polymer can be reduced. In addition, the aspect ratio of the primary particles can be reduced.

[0364] The amount of the modified monomer (A) used is preferably more than the amount equivalent 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 or more by mass, and particularly preferably 10 ppm or more by mass. If the amount of the modified monomer (A) used is too small, the average primary particle size of the resulting PTFE may not be small enough. The amount of the modified monomer (A) used may be within the above range, but for example, the upper limit can be set to 5000 ppm by mass. In addition, in the above manufacturing method, modified monomer (A) may be added to the system during the reaction in order to improve the stability of the aqueous dispersion during or after the reaction.

[0365] Since the above-mentioned modified monomer (A) is highly water-soluble, even if unreacted modified monomer (A) remains in the aqueous dispersion, it can be easily removed in the concentration step or the coagulation / washing step.

[0366] Although the modified monomer (A) is incorporated into the polymer during the polymerization process, the concentration of the modified monomer (A) in the polymerization system is low, and therefore the amount incorporated into the polymer is small. As a result, there are no problems such as a decrease in the heat resistance of PTFE or discoloration after firing.

[0367] Examples of hydrophilic groups in the above-mentioned modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (wherein M is H, a metal atom, or NR). 7y 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7y ) is H or an organic group, and may be the same or different. Any two may bond to each other to form a ring. ) are examples. Among the above hydrophilic groups, -SO3M or -COOM are preferred. R 7y Alkyl groups are preferred as organic groups in R. 7y For example, H or C 1-10 The organic group is preferably H or C 1-4 The organic group is more preferably H or C 1-4 A alkyl group is even more preferred. Examples of the above-mentioned metal atoms include 1- and 2-valent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred.

[0368] Examples of "functional groups that can react by radical polymerization" in the above-mentioned modified monomer (A) include groups having an ethylenically unsaturated bond, such as vinyl groups and allyl groups. Groups having an ethylenically unsaturated bond are given by the following formula: CX e X g =CX f R- (In the formula, X e , X f and X g Each of these is independently F, Cl, H, CF3, CF2H, CFH2, or CH3; R is a linking group. ) This can be represented as follows: The linking group of R will be described later. a Examples of linking groups include -CH=CH2 and -CF=CH 2、 -CH=CF 2、 Examples of groups having unsaturated bonds include -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-CF2-CF=CF2, and -O-CF2-CF=CF2.

[0369] Since the modified monomer (A) has a functional group that can react in radical polymerization, when used in the polymerization described above, it is presumed to react with the fluorine-containing monomer in the initial stages of the polymerization reaction, forming highly stable particles that have hydrophilic groups derived from the modified monomer (A). For this reason, it is thought that the number of particles will increase when polymerization is carried out in the presence of the modified monomer (A).

[0370] The above polymerization may involve the presence of one type of modified monomer (A), or it may involve the presence of two or more types.

[0371] In the polymerization described above, a compound having an unsaturated bond can be used as the modified monomer (A).

[0372] Modified monomer (A) is 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 These are, independently, F, Cl, H, or CF3; Y 3 R is a hydrophilic group; a is a linking group; Z 1 and Z 2 A compound represented by (where each is independently H, F, or CF3, and k is 0 or 1) is preferred. Examples of the above hydrophilic groups include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (wherein M is H, a metal atom, or NR). 7y 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7y ) is H or an organic group, and may be the same or different. Any two may bond to each other to form a ring. ) are examples. Among the above hydrophilic groups, -SO3M or -COOM are preferred. R 7y Alkyl groups are preferred as organic groups in R. 7y For example, H or C 1-10 The organic group is preferably H or C 1-4 The organic group is more preferably H or C 1-4 Alkyl alkyl groups are even more preferred. Examples of the metal atoms 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 above-mentioned modified monomer (A), an aqueous dispersion with a smaller average primary particle size and superior stability can be obtained. Furthermore, the aspect ratio of the primary particles can be reduced.

[0373] The above R a This is a linking group. In this 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, 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, for example, it may be 100 or less, or 50 or less. The above 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 esters, amides, sulfonamides, carbonyls, carbonates, urethanes, ureas, and carbamates. The above linking group may not contain carbon atoms and may contain catenary heteroatoms such as oxygen, sulfur, or nitrogen.

[0374] The above R a Preferably, this is a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group. R a If 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. Also, R a It may be chain-like or branched, and may be cyclic or acyclic. Also, R a It may contain functional groups (e.g., esters, ethers, ketones, amines, halides, etc.). R a It may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group. R aExamples include hydrocarbon groups in which no fluorine atoms are bonded to carbon atoms, hydrocarbon groups in which some of the hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms, hydrocarbon groups in which all of the hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms, -(C=O)-, -(C=O)-O-, or hydrocarbon groups containing ether bonds, which may contain oxygen atoms, double bonds, or functional groups.

[0375] R a It is preferably a hydrocarbon group having 1 to 100 carbon atoms, which may contain -(C=O)-, -(C=O)-O-, or ether bonds, and may also contain a carbonyl group, and in this hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine. R a 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-(CH2) b -, -(C=O)-(CF2) a -O-(CF2) b -, -(C=O)-O-(CH2) a -O-(CH2) b -, -(C=O)-O-(CF2) a -O-(CF2) b -, -(C=O)-O-C6H4-, and at least one selected from combinations thereof. In the formula, a, b, c, and d are independently at least 1. A, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit for a, b, c, and d is, for example, 100.

[0376] R aSpecific 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 Examples include -(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. Among these, the above R a Specifically, -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- are preferred. In the above formula, n is an integer between 1 and 10.

[0377] -R in general formula (4) a -(CZ 1 Z 2 )k -としては、-CF2-O-CF2-、-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-C F(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-OC(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- are more preferred. In the above formula, n is an integer between 1 and 10.

[0378] Specific examples of compounds represented by general formula (4) include: [ka] (In the formula, X j and Y 3 The above is the same. n is an integer from 1 to 10.) Examples include:

[0379] R a For example, 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 6A divalent group represented by the general formula (r2) is preferred, where each is independently H, F, or CF3, e is an integer from 0 to 3, f is an integer from 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1. -(C=O) h -(O) i -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 Each of the elements is independently H, F, or CF3, e is an integer from 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1. A divalent group represented by ( ) is also preferred.

[0380] -R of general formula (4) a -(CZ 1 Z 2 ) k -Also, the following equation (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 Each of these is independently H, F, or CF3, e is an integer from 0 to 3, f is an integer from 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, Z 1 and Z 2 Divalent groups represented by (F or CF3, respectively) are also preferred, and in formula (t1), Z 1 and Z 2 It is more preferable that one is F and the other is CF3. Furthermore, in general formula (4), -R a -(CZ 1 Z 2 ) k -As shown in equation (t2): -(C=O) h -(O) i-CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (t2) (In the formula, X 7 Each of these is independently H, F, or CF3, e is an integer from 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, Z 1 and Z 2 Divalent groups represented by (F or CF3, respectively) are also preferred, and in formula (t2), Z 1 and Z 2 It is more preferable that one is F and the other is CF3.

[0381] Compounds represented by general formula (4) have a hydrophilic group (Y 3 Except for ), it is also preferable that it has CF bonds and does not have CH bonds. That is, in general formula (4), X i , X j , and X k All of them are F, and R a Preferably, the group is a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be linear or branched, 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 4 to 18.

[0382] The compound represented by general formula (4) may be partially fluorinated. That is, the compound represented by general formula (4) may have a hydrophilic group (Y 3 Except for the above, it is preferable to have at least one hydrogen atom bonded to a carbon atom, and also to have at least one fluorine atom bonded to a carbon atom.

[0383] The compound represented by general formula (4) is also preferably the compound shown by the following formula (4a). CF2 = CF - O - Rf 0 -Y 3 (4a) (In the formula, Y3 Rf is a hydrophilic group. 0 This is a perfluorinated divalent linking group that is perfluorinated and may have a linear or branched, cyclic or acyclic structure, be saturated or unsaturated, substituted or unsubstituted, and optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0384] The compound represented by general formula (4) is also preferably the compound shown by formula (4b) below. CH2=CH-O-Rf 0 -Y 3 (4b) (In the formula, Y 3 Rf is a hydrophilic group. 0 This is a perfluorinated divalent linking group defined by formula (4a).

[0385] In general formula (4), Y 3 One preferred form is -OSO3M. 3 When is -OSO3M, examples of compounds 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(OCF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OSO3M), etc. In the above formulas, M is the same as above.

[0386] In general formula (4), Y 3 It is also preferable that it be -SO3M. 3When is -SO3M, examples of compounds 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 formula, M is the same as above.

[0387] In general formula (4), Y 3 Being -COOM is also a preferred form. 3 When is -COOM, the compounds represented by general formula (4) are CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), and CF2=CF(OCF2CF(CF3)O(CF2) n Examples include 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)OCF2CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), CH2=CH((CF2)3SO2NR'CH2COOM), etc. In the above formula, R' is H or C 1-4 It is an alkyl group, and M is the same as above.

[0388] In general formula (4), Y 3 It is also a preferred form that is -OPO3M or -OP(O)(OM)2.3 When is -OPO3M or -OP(O)(OM)2, the compounds represented by general formula (4) are 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 Examples include 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 formulas, M is the same as above.

[0389] In general formula (4), Y 3 It is also a preferred form that is -PO3M or -P(O)(OM)2. 3 When is -PO3M or -P(O)(OM)2, examples of compounds 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), etc., where M is the same as above.

[0390] Compounds represented by general formula (4) include general formula (5): CX2=CY(-CZ2-O-Rf-Y 3 ) (5) (In the formula, X is the same or different -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Z is the same or different -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms. Y 3 The above is the same as above.) Compound represented by general formula (6): CX2=CY(-O-Rf-Y 3 ) (6) (In the formula, X is the same or different -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 having an ether bond. 3 The above is the same as above.) Compounds represented by general formula (7): CX2=CY(-Rf-Y 3 ) (7) (In the formula, X is the same or different -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 having an ether bond. 3 The same applies as described above. Preferably, it is at least one selected from the group consisting of compounds represented by ). Furthermore, the above-mentioned fluorine-containing alkylene groups having ether bonds with 2 to 100 carbon atoms do not include structures where the oxygen atom is at the terminal end, and are alkylene groups that contain ether bonds between carbon atoms.

[0391] In general formula (5), X is either -H or -F. X may be both -F, or at least one of them may be -H. For example, one may be -F and the other -H, or both may be -H.

[0392] In general formula (5), Y is -H, -F, an alkyl group, or a fluorine-containing alkyl group. The alkyl group described above is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. Preferably, the alkyl group has six or fewer carbon atoms, more preferably four or fewer, and even more preferably three or fewer. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have one or more carbon atoms. The above-mentioned fluorine-containing alkyl group preferably has 6 or fewer carbon atoms, more preferably 4 or fewer, and even more preferably 3 or fewer. For Y, -H, -F, or -CF3 are preferred, with -F being more preferred.

[0393] In general formula (5), Z is either the same or different -H, -F, an alkyl group, or a fluoroalkyl group. The alkyl group described above is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. Preferably, the alkyl group has six or fewer carbon atoms, more preferably four or fewer, and even more preferably three or fewer. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have one or more carbon atoms. The above-mentioned fluorine-containing alkyl group preferably has 6 or fewer carbon atoms, more preferably 4 or fewer, and even more preferably 3 or fewer. For Z, -H, -F, or -CF3 are preferred, with -F being more preferred.

[0394] 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.

[0395] In general formula (5), Rf is 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. The number of carbon atoms in the above-mentioned fluorinated alkylene group is preferably 2 or more. It is also preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the above-mentioned fluorinated alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, etc. The above-mentioned fluorinated alkylene group is preferably a perfluoroalkylene group.

[0396] The number of carbon atoms in the fluorinated alkylene group having the ether bond is preferably 3 or more. Furthermore, the number of carbon atoms in the fluorinated alkylene group having the ether bond is preferably 60 or less, more preferably 30 or less, and even more preferably 12 or less. Examples of fluorine-containing alkylene groups having an ether bond include the following formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 H or F;Z respectively 4 It is also preferable that is a divalent base represented by H, F, or CF3; p1+q1+r1 is an integer from 1 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5). Specifically, the fluorine-containing alkylene groups having the above ether linkage include -CF(CF3)CF2-O-CF(CF3)- and -(CF(CF3)CF2-O) n -CF(CF3)- (where n is an integer from 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 from 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2-, and -CF2CF2O-CF2CH2-. The fluorine-containing alkylene group having the above ether linkage is preferably a perfluoroalkylene group.

[0397] In general formula (5), Y 3 -COOM, -SO3M, or -OSO3M (where M is H, a metal atom, NR) 7y 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7y (These are H or an organic group, and may be the same or different. Any two may bond to each other to form a ring.) R 7y Alkyl groups are preferred as the organic groups in this case. R 7y For example, H or C 1-10 The organic group is preferably H or C 1-4 The organic group is more preferably H or C 1-4 A alkyl group is even more preferred. Examples of the above-mentioned metal atoms include alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. For M, this could be -H, a metal atom, or NR. 7 4 is preferred, and -H, alkali metals (Group 1), alkaline earth metals (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 particularly preferred, and -H or NH4 is most preferred. The above Y 3 -COOM or -SO3M is preferred, with -COOM being more preferred.

[0398] The compound represented by general formula (5) is preferably compound (5a) represented by general formula (5a). CH2=CF(-CF2-O-Rf-Y 3 ) (5a) (In the formula, Rf and Y 3 (This is the same as above.)

[0399] Specifically, compounds represented by general formula (5a) include the following formulas:

[0400] [ka]

[0401] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 H or F;Z respectively 4 H, F, or CF3; p1+q1+r1 are integers from 0 to 10; s1 are 0 or 1; t1 are integers from 0 to 5, Y 3 The same as above. However, Z 3 and Z 4 Examples of compounds represented by (where both atoms are H, and p1+q1+r1+s1 is not 0) include,

[0402] [ka]

[0403] These are some of the preferred options, among others

[0404] [ka]

[0405] It is preferable that this be the case.

[0406] Compounds represented by general formula (5a) include Y in formula (5a). 3 It is preferable that the compound 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 the same as defined above), with CH2=CFCF2OCF(CF3)COOM being more preferable.

[0407] The compound represented by general formula (5) is preferably 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 These are identical and represent either F or H. n5 represents 0 or an integer from 1 to 10, and Y 3 (This is the same as the definition above.)

[0408] In the above formula (5b), n5 is preferably 0 or an integer from 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in terms of the stability of the resulting aqueous dispersion. 3 It is preferable that -COOM is used because it provides moderate water solubility and stability of the aqueous dispersion, and it is preferable that M is H or NH4 because it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0409] Examples of compounds represented by the above formula (5b) include CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is the same as defined above).

[0410] Furthermore, compounds represented by general formula (5) include those represented by general formula (5c), etc.

[0411] CF2 = CFCF2 - O - Rf - Y 3 (5c) (In the formula, Rf and Y 3 (This is the same as above)

[0412] More specifically, [ka] These are some examples.

[0413] In general formula (6), X is either -H or -F. X may be both -F, or at least one of them may be -H. For example, one may be -F and the other -H, or both may be -H.

[0414] In general formula (6), Y is -H, -F, an alkyl group, or a fluorine-containing alkyl group. The alkyl group described above is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. Preferably, the alkyl group has six or fewer carbon atoms, more preferably four or fewer, and even more preferably three or fewer. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have one or more carbon atoms. The above-mentioned fluorine-containing alkyl group preferably has 6 or fewer carbon atoms, more preferably 4 or fewer, and even more preferably 3 or fewer. For Y, -H, -F, or -CF3 are preferred, with -F being more preferred.

[0415] 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.

[0416] In general formula (6), Rf is 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. The number of carbon atoms in the above-mentioned fluorinated alkylene group is preferably 2 or more. Furthermore, the number of carbon atoms in the fluorinated alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the above-mentioned fluorinated alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, etc. The above-mentioned fluorinated alkylene group is preferably a perfluoroalkylene group.

[0417] In the above general formula (6), Y 3 -COOM, -SO3M, or -OSO3M (where M is H, a metal atom, NR) 7y 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7y(These are H or an organic group, and may be the same or different. Any two may bond to each other to form a ring.) R 7y An alkyl group is preferred as the organic group. 7y For example, H or C 1-10 The organic group is preferably H or C 1-4 The organic group is more preferably H or C 1-4 A alkyl group is even more preferred. Examples of the above-mentioned metal atoms include alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. For M, this could be -H, a metal atom, or NR. 7 4 is preferred, and -H, alkali metals (Group 1), alkaline earth metals (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 particularly preferred, and -H or NH4 is most preferred. The above Y 3 -COOM or -SO3M is preferred, with -COOM being more preferred.

[0418] The compound represented by general formula (6) is preferably at least one selected from the group consisting of compounds represented by general formulas (6a), (6b), (6c), (6d), and (6e). CF2 = CF - O - (CF2) n1 -Y 3 (6a) (In the formula, n1 represents an integer from 1 to 10, Y 3 (This is the same as the definition above.) CF2 = CF - O - (CF2C(CF3)F) n2 -Y 3 (6b) (In the formula, n² represents an integer from 1 to 5, Y 3 (This 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 from 1 to 10, and Y 3 (This is the same as the definition above.) CF2 = CF - O - (CF2CFX) 1 O) n4 -(CF2) n6 -Y 3 (6d) (In the formula, n4 represents an integer from 1 to 10, n6 represents an integer from 1 to 3, and Y 3 and X 1 (This is the same as the definition above.) CF2 = CF - O - (CF2CF2CFX) 1 O) n5 -CF2CF2CF2-Y 3 (6e) (In the formula, n5 represents an integer from 0 to 10, Y 3 and X 1 (This is the same as the definition above.)

[0419] In the above formula (6a), n1 is preferably an integer less than or equal to 5, and more preferably an integer less than or equal to 2. 3 It is preferable that -COOM or -SO3M is used because it provides adequate water solubility and stability of the aqueous dispersion, and M is preferable to H or NH4 because it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0420] 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 the same as defined above).

[0421] In the above formula (6b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, Y 3It is preferable that -COOM or -SO3M is used because it provides appropriate water solubility and stability of the aqueous dispersion, and M is preferable to H or NH4 because it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0422] In the above formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 It is preferable that the component is -COOM or -SO3M in that it provides appropriate water solubility and stability of the aqueous dispersion, and that M is preferably H or NH4 in that it improves dispersion stability.

[0423] In the above formula (6d), the above X 1 In terms of the stability of the aqueous dispersion, it is preferable that n4 is -CF3, and in terms of water solubility, it is preferable that Y 3 The compound is preferably -COOM or -SO3M, as this provides adequate water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0424] Examples of compounds 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, and CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4, or an alkali metal).

[0425] In general formula (6e), n5 is preferably an integer of 5 or less in terms of water solubility, and Y 3 The compound is preferably -COOM or -SO3M, as this provides adequate water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0426] Examples of compounds represented by general formula (6e) include CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4, or an alkali metal).

[0427] In general formula (7), Rf is preferably a fluorine-containing alkylene group having 1 to 40 carbon atoms. In general formula (7), at least one of X and Y is preferably a fluorine atom.

[0428] Compounds represented by general formula (7) are general formula (7a): CF2 = CF - (CF2) n1 -Y 3 (7a) (In the formula, n1 represents an integer from 1 to 10, Y 3 The same definition as above.) Compounds represented by general formula (7b): CF2 = CF - (CF2C(CF3)F) n2 -Y 3 (7b) (In the formula, n² represents an integer from 1 to 5, Y 3 The definition is the same as above. At least one compound selected from the group consisting of compounds represented by ) is preferred. The above Y 3 The preferred form is -SO3M or -COOM, where M is H, a metal atom, or NR. 7y 4. Preferably, it is imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents. 7y represents H or an organic group.

[0429] In the above formula (7a), n1 is preferably an integer less than or equal to 5, and more preferably an integer less than or equal to 2. 3 It is preferable that -COOM or -SO3M is used because it provides adequate water solubility and stability of the aqueous dispersion, and M is preferable to H or NH4 because it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article. Examples of compounds represented by the above formula (7a) include CF2=CFCF2COOM and CF2=CFCF2SO3M (wherein M is the same as defined above).

[0430] In the above formula (7b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, Y 3 It is preferable that -COOM or -SO3M is used because it provides appropriate water solubility and stability of the aqueous dispersion, and M is preferable to H or NH4 because it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0431] The above-mentioned modified monomer preferably contains modified monomer (A), preferably contains at least one compound 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).

[0432] When a modified monomer (A) is used as the modified monomer, the content of the modified monomer (A) units is preferably in the range of 0.00001 to 1.0 mass% relative to the total polymerization units of the TFE polymer (PTFE). The lower limit is more preferably 0.0001 mass%, more preferably 0.0005 mass%, even more preferably 0.001 mass%, and even more preferably 0.005 mass%. The upper limits are, in order of preference, 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0433] The aqueous dispersion of TFE polymer can also be used in various applications as a composition to which organic or inorganic fillers have been added, depending on the purpose. When the above composition is applied to a substrate made of metal or ceramic, it can create a coating surface that is non-stick, has a low coefficient of friction, and has excellent gloss, smoothness, abrasion resistance, weather resistance, and heat resistance, making it suitable for painting rolls and cooking utensils, impregnation of glass cloth, etc.

[0434] An organosol of the TFE polymer can also be prepared from the above aqueous dispersion. The organosol may contain the above TFE polymer and an organic solvent. Examples of the organic solvent include ether-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ester-based solvents, aliphatic hydrocarbon-based solvents, aromatic hydrocarbon-based solvents, and halogenated hydrocarbon-based solvents, with N-methyl-2-pyrrolidone and dimethylacetamide being suitably used. The preparation of the organosol can be carried out, for example, by the method described in International Publication No. 2012 / 002038.

[0435] The aqueous dispersion of the above TFE polymer is also preferably used as a processing aid. When used as a processing aid, mixing the aqueous dispersion with a host polymer can improve the melt strength during melt processing of the host polymer, as well as the mechanical strength, electrical properties, flame retardancy, drip prevention during combustion, and sliding properties of the resulting polymer.

[0436] The aqueous dispersion of the above TFE polymer is also preferably used as a binder for batteries and for dustproofing purposes.

[0437] The aqueous dispersion of the above TFE polymer is also preferably used as a processing aid after being compounded with a resin other than the TFE polymer. The aqueous dispersion is suitable as a raw material for PTFE as described in, for example, Japanese Patent Publication No. 11-49912, U.S. Patent No. 5,804,654, Japanese Patent Publication No. 11-29679, and Japanese Patent Publication No. 2003-2980. A processing aid using the above aqueous dispersion is in no way inferior to the processing aids described in the above publications.

[0438] The aqueous dispersion of the TFE polymer described above can also be mixed with an aqueous dispersion of a melt-processable fluororesin and allowed to coagulate to form a co-coagulated powder. This co-coagulated powder is suitable as a processing aid.

[0439] Examples of the above-mentioned melt-processable fluororesins include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, and ethylene / TFE / HFP copolymer [EFEP], but PFA or FEP are preferred among them.

[0440] The above aqueous dispersion may also preferably contain the above melt-processable fluororesin. Examples of the above melt-processable fluororesin include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, EFEP, etc. The above aqueous dispersion containing the above melt-processable fluororesin can be used as a paint. The above melt-processable fluororesin can sufficiently fuse the particles of the TFE polymer together, thereby improving film-forming properties and giving gloss to the resulting coating.

[0441] The aqueous dispersion of the above TFE polymer is also preferably used as a dust suppression agent. The above dust suppression agent can be used in methods that suppress dust from dust-generating substances by mixing it with a dust-generating substance and applying compression-shear action to the mixture at a temperature of 20 to 200°C to fibrillate the TFE polymer, such as in the methods described in Japanese Patent Publication No. 2827152 and Japanese Patent Publication No. 2538783. The aqueous dispersion of the above TFE polymer can be suitably used, for example, in the dust suppression agent composition described in International Publication No. 2007 / 004250, and can also be suitably used in the dust suppression treatment method described in International Publication No. 2007 / 000812.

[0442] The above-mentioned dust suppression agent is suitably used in dust suppression treatment for building materials, soil stabilizers, solidifying agents, fertilizers, landfill disposal of incinerated ash and hazardous substances, explosion-proof applications, cosmetics, and pet waste sand such as cat litter.

[0443] The aqueous dispersion of the above-mentioned TFE polymer may also be used as a raw material for obtaining TFE polymer fibers by the dispersion spinning method. The dispersion spinning method involves mixing the aqueous dispersion of the above-mentioned TFE polymer with an aqueous dispersion of a matrix polymer, extruding the mixture to form an intermediate fiber structure, and then firing the intermediate fiber structure to decompose the matrix polymer and sinter the TFE polymer particles in order to obtain TFE polymer fibers.

[0444] The manufacturing method disclosed herein can also be used to produce low molecular weight PTFE. Low molecular weight PTFE can be produced by polymerization, or by reducing the molecular weight of high molecular weight PTFE obtained by polymerization using known methods (thermal decomposition, radiation decomposition, etc.).

[0445] Low molecular weight PTFE (also called PTFE micropowder) with a molecular weight of 600,000 or less has excellent chemical stability, extremely low surface energy, and is less prone to fibrillation. Therefore, it is suitable as an additive for the manufacture of plastics, inks, cosmetics, paints, greases, office automation equipment components, toners, etc., for purposes such as improving slipperiness and the texture of coating surfaces (see, for example, Japanese Patent Publication No. 10-147617).

[0446] Furthermore, low molecular weight PTFE may be obtained by polymerizing TFE, or TFE with a monomer copolymerizable with TFE, in the presence of a chain transfer agent. In this case, at least one selected from the group consisting of alkanes having 2 to 4 carbon atoms is preferred as the chain transfer agent. 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.

[0447] When using the low molecular weight PTFE obtained by the above polymerization as a powder, the above aqueous dispersion can be coagulated to form powder particles.

[0448] In this disclosure, high molecular weight PTFE means PTFE that is non-melt processable and fibrillable. On the other hand, low molecular weight PTFE means PTFE that is melt processable and does not fibrillate.

[0449] The above-mentioned non-meltability refers to the property 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.

[0450] The presence or absence of fibrillation properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," which is a powder made from TFE polymers. Paste extrusion is usually possible because high molecular weight PTFE has fibrillation properties. If the unfired molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it has 0% elongation and breaks when pulled, it can be considered that it does not have fibrillation properties.

[0451] The above high molecular weight PTFE preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The above standard specific gravity is measured using a sample molded in accordance with ASTM D4895-89 and measured by the water displacement method in accordance with ASTM D 792. In this disclosure, "high molecular weight" means that the above standard specific gravity is within the above range.

[0452] The above low molecular weight PTFE has a melt viscosity of 1 × 10⁻⁶ at 380°C. 2 ~7×10 5 The value is Pa·s. In this 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, by preheating a 2g sample at 380°C for 5 minutes and maintaining it at the above temperature under a load of 0.7 MPa.

[0453] The high molecular weight PTFE described above has an extremely high melt viscosity compared to the low molecular weight PTFE described above, making it difficult to accurately measure its melt viscosity. On the other hand, while the melt viscosity of the low molecular weight PTFE can be measured, it is difficult to obtain molded articles from the low molecular weight PTFE that can be used to measure standard specific gravity, making it difficult to accurately measure its standard specific gravity. Therefore, in this disclosure, standard specific gravity is used as an indicator of the molecular weight of the high molecular weight PTFE, and melt viscosity is used as an indicator of the molecular weight of the low molecular weight PTFE. It should be noted that no measurement method is known that can directly determine the molecular weight of either the high molecular weight PTFE or the low molecular weight PTFE.

[0454] The above high molecular weight PTFE preferably has a peak temperature of 333 to 347°C, and more preferably 335 to 345°C. The above low molecular weight PTFE preferably has a peak temperature of 322 to 333°C, and more preferably 324 to 332°C. The peak temperature can be identified as the temperature corresponding to the maximum value appearing in the differential thermal (DTA) curve obtained by heating PTFE that has not been heated to a temperature of 300°C or higher at a rate of 10°C / min using a TG / DTA (Differential Thermogravimetric Analysis) device.

[0455] The peak temperature of PTFE may be between 322 and 347°C. When PTFE is high molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 347°C or lower, 346°C or lower, 345°C or lower, 344°C or lower, 343°C or lower, 342°C or lower, 341°C or lower, or 340°C or lower. When PTFE is high molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 333°C or higher, or 335°C or higher. When PTFE is low molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 333°C or less, or 332°C or less. When PTFE is low molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 322°C or higher, or 324°C or higher.

[0456] The average primary particle diameter of the primary particles of low molecular weight PTFE is preferably 10 to 300 nm, more preferably 50 nm or more, even more preferably 100 nm or more, even more preferably 150 nm or less, and even more preferably 250 nm or less. A relatively small average primary particle diameter of primary particles can be obtained, for example, by adding a modified monomer to the polymerization system in the early stages of TFE polymerization.

[0457] The average primary particle diameter 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 solid content concentration of approximately 1.0 mass%, and then measured using dynamic light scattering with a measurement temperature of 25°C, a refractive index of 1.3328 for the solvent (water), a viscosity of 0.8878 mPa·s for the solvent (water), and 70 cumulative measurements. For dynamic light scattering, for example, the ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used.

[0458] Furthermore, the average primary particle diameter can also be measured by the following method: Dilute the dispersion with water until the solid content concentration reaches 0.15% by mass. Measure the transmittance of 550 nm projected light per unit length of the resulting diluted latex, and the average particle diameter determined by measuring the directional diameter using a transmission electron microscope image. Create a calibration curve. Using this calibration curve, the average particle diameter can be determined from the measured transmittance of 550 nm projected light for each sample.

[0459] The above high molecular weight PTFE is preferably such that, when PTFE that has not been previously heated to temperatures above 300°C is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), at least one endothermic peak appears in the range of 333 to 347°C in the heat of fusion curve, and the heat of fusion amount at 290 to 350°C calculated from the above heat of fusion curve is 52 mJ / mg or more. The heat of fusion amount of PTFE is more preferably 55 mJ / mg or more, and even more preferably 58 mJ / mg or more.

[0460] (II) Melt-processable fluororesins (1) In the manufacturing 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.

[0461] The preferred monomer composition (mass%) of FEP is TFE:HFP = (60-95):(5-40), more preferably (85-92):(8-15).

[0462] In addition to TFE and HFP, a copolymer of TFE, HFP, and other monomers may be obtained as FEP by polymerizing other monomers copolymerizable with these monomers. Examples of other monomers include the fluoromonomers mentioned above (except TFE and HFP) and fluorine-free monomers. One or more types of other monomers can be used. Perfluoro(alkyl vinyl ether) is preferred as the other monomer. The content of other monomer units in FEP may be 0.1 to 2% by mass relative to the total monomer units.

[0463] In the polymerization of FEP described above, it is preferable to use cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, etc. as chain transfer agents, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, etc. as pH buffering agents.

[0464] (2) In the manufacturing method of the present disclosure, polymerization of TFE / perfluoro(alkyl vinyl ether) copolymers such as PFA and MFA and TFE / perfluoroallyl ether copolymers is usually carried out at a polymerization temperature of 10 to 100°C and a polymerization pressure of 0.3 to 6.0 MPaG.

[0465] 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 given by formula: CF2=CFORf4 (In the formula, Rf 4 It is preferable to use a perfluoroalkyl group having 1 to 6 carbon atoms.

[0466] In addition to TFE and perfluoro(alkyl vinyl ether), a copolymer of TFE, perfluoro(alkyl vinyl ether), and other monomers copolymerized with these monomers may be obtained as a TFE / perfluoro(alkyl vinyl ether) copolymer. Examples of other monomers include the fluoromonomers mentioned above (excluding TFE and perfluoro(alkyl vinyl ether)) and fluorine-free monomers. One or more types of other monomers can be used. The content of other monomer units in the TFE / perfluoro(alkyl vinyl ether) copolymer may be 0.1 to 2% by mass relative to the total monomer units.

[0467] 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 given by formula: CF2=CFCF2ORf 4 (In the formula, Rf 4 It is preferable to use a perfluoroalkyl group having 1 to 6 carbon atoms.

[0468] In addition to TFE and perfluoroallyl ether, a copolymer of TFE, perfluoroallyl ether, and other monomers copolymerizable with these monomers may be polymerized to obtain a TFE / perfluoroallyl ether copolymer. Examples of other monomers include the fluoromonomers mentioned above (excluding TFE and perfluoroallyl ether) and fluorine-free monomers. One or more types of other monomers can be used. The content of other monomer units in the TFE / perfluoroallyl ether copolymer may be 0.1 to 2% by mass relative to the total monomer units.

[0469] In the polymerization of the above-mentioned TFE / perfluoro(alkyl vinyl ether) copolymer and TFE / perfluoroallyl ether copolymer, it is preferable to use cyclohexane, methanol, ethanol, propanol, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, methane, ethane, etc. as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, etc. as a pH buffering agent.

[0470] Furthermore, a primer composition can be obtained by appropriately adding a nonionic surfactant to an aqueous dispersion of TFE / perfluoro(alkyl vinyl ether) copolymers and TFE / perfluoroallyl ether copolymers such as PFA and MFA, 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 of coating a metal surface with fluororesin, which involves applying this primer composition to a metal surface, applying a melt-processable fluororesin composition on the thus formed primer layer, and firing the melt-processable fluororesin composition layer together with the primer layer.

[0471] (3) In the manufacturing method of the present disclosure, 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.

[0472] The preferred monomer composition (mol%) of ETFE is TFE:ethylene = (50-99):(50-1).

[0473] In addition to ethylene and TFE, copolymers of ethylene, TFE, and other monomers can be obtained as ETFE by polymerizing other monomers copolymerizable with these monomers. Examples of other monomers include the fluoromonomers (except TFE) and fluorine-free monomers (except ethylene) mentioned above. One or more of these other monomers can be used.

[0474] Other preferred monomers include hexafluoropropylene, perfluorobutylethylene, perfluorohexylethylene, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoroocta-1-ene, 2,3,3,4,4,5,5-heptafluoro-1-pentene (CH2=CFCF2CF2CF2H), and 2-trifluoromethyl-3,3,3-trifluoropropene ((CF3)2CF=CH2).

[0475] The content of other monomer units in ETFE may be 0 to 20% by mass relative to the total number of monomer units. A preferred mass ratio is TFE:ethylene:other monomers = (63 to 94):(27 to 2):(1 to 10).

[0476] In the polymerization of ETFE described above, it is preferable to use cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, etc. as chain transfer agents.

[0477] (4) An electrolyte polymer precursor can also be produced using the manufacturing method of the present disclosure. In the manufacturing method of the present disclosure, 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 -SO2X 151 ,-COZ 151 or -POZ 152 Z 153 (X 151 , Z 151 , Z 152 and Z 153 It consists of monomers containing functional groups (as described below) and can be converted into an ion-exchange polymer through hydrolysis.

[0478] Examples of monomers used in electrolyte polymer precursors 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 from 0 to 3. n Y 151 may be the same or different. Y 152 represents a fluorine atom, a chlorine atom or a -SO2F group. m represents an integer from 1 to 5. m Y 152 may be the same or different. A 151 is -SO2X 151 , -COZ 151 or -POZ 152 Z 153 represents. X 151 is F, Cl, Br, I, -OR 151 or -NR 152 R 153 represents. Z 151 , Z 152 and Z 153 are the same or different and represent -NR 154 R 155 or -OR 156 R 151 , R 152 , R 153 , R 154 , R 155 and R<00009​​​​The electrolyte polymer precursor described above may be modified with a third monomer in a range of 0 to 20% by mass of the total monomer. Examples of third monomers 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-dioxol; and polyfunctional monomers such as divinylbenzene.

[0480] The electrolyte polymer precursor obtained in this way can be formed into a film, for example, and then subjected to hydrolysis with an alkaline solution and treatment with a mineral acid to be used as a polymer electrolyte membrane in fuel cells, electrolytic devices, redox flow batteries, and the like. Furthermore, an electrolyte polymer dispersion can be obtained by hydrolyzing the electrolyte polymer precursor with an alkaline solution while maintaining its dispersion state. By further heating the mixture to over 120°C in a pressurized container, it can be dissolved in, for example, a water / alcohol mixed solvent, thus becoming a solution. The solution obtained in this way can be used, for example, as a binder for electrodes, or combined with various additives to form a cast film which can then be used for applications such as antifouling coatings or organic actuators.

[0481] (5)TFE / VDF copolymer In the manufacturing method of this disclosure, the polymerization temperature of the TFE / VDF copolymer is not particularly limited and may be 0 to 100°C. The polymerization pressure is determined as appropriate depending on other polymerization conditions such as the polymerization temperature, but may usually be 0 to 9.8 MPaG.

[0482] 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 by further using a third monomer, within the range of 0~50 mol% of the total monomer. Preferably, TFE:ethylene:third monomer = (30~85):(10~69.9):(0.1~10).

[0483] The third monomer mentioned above is: Formula: CX 11 X 12 =CX 13 (CX 14 X 15 ) n11 X 16 (In the formula, X 11 ~X 16 represents H, F, or Cl, either identical or distinct, and n11 represents an integer from 0 to 8. However, this excludes TFE and VDF.) Monomers indicated by, or Formula: CX 21 X 22 =CX 23 -O(CX 24 X 25 ) n21 X 26 (In the formula, X 21 ~X 26 The monomers shown are preferred. (where n21 represents an integer from 0 to 8, and the same or different elements represent H, F, or Cl.)

[0484] Furthermore, the third monomer may be a fluorine-free ethylenic monomer. The above fluorine-free ethylenic monomer is preferably selected from ethylenic monomers having 6 or fewer carbon atoms in order to maintain heat resistance and chemical resistance. 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-butenic acid, 4-vinylpentenoate vinylsulfonic acid, acrylic acid, methacrylic acid, etc.

[0485] It is also preferable to coat an aqueous dispersion of the above TFE / VDF copolymer onto a porous substrate made of 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 a porous substrate with the dispersed particles and use it as a composite porous membrane. The composite porous membrane obtained in this way can be used as a separator in lithium secondary batteries, etc.

[0486] The fluoropolymer in the aqueous dispersion obtained by the manufacturing method of this disclosure, and the fluoropolymer in the aqueous dispersion of this disclosure, are preferably at least one melt-processable fluororesin selected from the group consisting of TFE / fluoroalkyl vinyl ether (FAVE) copolymers and TFE / HFP copolymers. When the fluoropolymer is one of these copolymers, for example, when the aqueous dispersion of the fluoropolymer of this disclosure is used as a coating composition described later, a film with excellent appearance and physical properties can be easily obtained.

[0487] The melting point of the melt-processable fluororesin is preferably 200 to 322°C, more preferably 220°C or higher, even more preferably 240°C or higher, even more preferably 315°C or lower, and even more preferably 310°C or lower.

[0488] In this disclosure, the melting point of the melt-processable fluororesin can be measured using a differential scanning calorimeter (DSC).

[0489] The TFE / FAVE copolymer contains at least TFE units and FAVE units.

[0490] The FAVE that constitutes a FAVE unit is given by the general formula (11): CF2 = CFO(CF2CFY 1 O) p -(CF2CF2CF2O) q -Rf (11) (In the formula, Y 1 ) represents F or CF3, and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms. p represents an integer from 0 to 5, and q represents an integer from 0 to 5. ) Monomers represented by general formula (12): CFX=CXOCF2OR 1 (12) (In the formula, X represents the same or different H, F, or CF3, and R represents the same or different H, F, or CF3.) 1This represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms, which may contain 1 to 2 atoms selected from the group consisting of H, Cl, Br, and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms, which may contain 1 to 2 atoms selected from the group consisting of H, Cl, Br, and I.) A possible example is at least one selected from the group consisting of monomers represented by ).

[0491] Among the FAVEs, monomers represented by general formula (11) are preferred, at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE) is more preferred, at least one selected from the group consisting of PEVE and PPVE is even more preferred, and PPVE is particularly preferred.

[0492] The content of FAVE units in the TFE / FAVE copolymer is preferably 1.0 to 10.0% by mass, more preferably 2.0% by mass or more, even more preferably 2.5% by mass or more, still more preferably 3.0% by mass or more, particularly preferably 3.5% by mass or more, most preferably 4.0% by mass or more, more preferably 8.0% by mass or less, even more preferably 7.0% by mass or less, still more preferably 6.5% by mass or less, and particularly preferably 6.0% by mass or less, relative to the total monomer units.

[0493] The TFE unit content in the TFE / FAVE copolymer is preferably 99.0 to 90.0% by mass, more preferably 98.0% by mass or less, even more preferably 97.5% by mass or less, still more preferably 97.0% by mass or less, particularly preferably 96.5% by mass or less, most preferably 96.0% by mass or less, more preferably 92.0% by mass or more, even more preferably 93.0% by mass or more, still more preferably 93.5% by mass or more, and particularly preferably 94.0% by mass or more, based on the total monomer units.

[0494] The TFE / FAVE copolymer may also contain monomer units derived from monomers copolymerizable with TFE and FAVE. In this case, the content of monomers copolymerizable with TFE and FAVE is preferably 0 to 9.0% by mass, and more preferably 0.1 to 2.0% by mass, relative to the total monomer units of the copolymer.

[0495] Monomers copolymerizable with TFE and FAVE include HFP and CZ. 1 Z 2 =CZ 3 (CF2) n Z 4 (In the formula, Z 1 , Z 2 and Z 3 These represent H or F, and Z, which are the same or different. 4 ) represents H, F, or Cl, and n is an integer from 2 to 10. ) and CF2=CF-OCH2-Rf 1 (In the formula, Rf 1 represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples include alkyl perfluorovinyl ether derivatives represented by ). Among these, HFP is preferred.

[0496] The TFE / FAVE copolymer is preferably at least one selected from the group consisting of a copolymer comprising only TFE units and FAVE units, and the TFE / HFP / FAVE copolymer described above, with a copolymer comprising only TFE units and FAVE units being more preferred. Furthermore, one embodiment of the TFE / FAVE copolymer does not contain HFP units.

[0497] The melting point of the TFE / FAVE copolymer is preferably 280 to 322°C, more preferably 290°C or higher, even more preferably 295°C or higher, more preferably 315°C or lower, and even more preferably 310°C or lower.

[0498] The TFE / HFP copolymer contains at least TFE units and HFP units.

[0499] The HFP unit content in the TFE / HFP copolymer is preferably 1.0% to 30.0% by mass, more preferably 2.0% or more by mass, even more preferably 5.0% or more by mass, and more preferably 15.0% or less by mass, relative to the total monomer units.

[0500] The TFE unit content in the TFE / HFP copolymer is preferably 70.0 to 99.0% by mass or more, more preferably 75.0% by mass or more, even more preferably 80.0% by mass or more, even more preferably 85.0% by mass or more, and more preferably 98.0% by mass or less, relative to the total monomer units.

[0501] The above TFE / HFP copolymer preferably has a mass ratio (TFE / HFP) of 70-99 / 1-30 (mass%) of TFE units to HFP units. More preferably, the above mass ratio (TFE / HFP) is 85-95 / 5-15 (mass%).

[0502] The TFE / HFP copolymer may further contain FAVE units. Examples of FAVE units contained in the TFE / HFP copolymer include those similar to those described above.

[0503] When the TFE / HFP copolymer contains FAVE units, the FAVE unit content is preferably 0.1 to 25.0% by mass, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, more preferably 10.0% by mass or less, even more preferably 4.0% by mass or less, and even more preferably 2.0% by mass or less.

[0504] When the TFE / HFP copolymer is a copolymer containing TFE units, HFP units, and FAVE units (hereinafter also referred to as "TFE / HFP / FAVE copolymer"), it is preferable that the mass ratio (TFE / HFP / FAVE) is 70.0~99.0 / 0.1~25.0 / 0.1~25.0 (mass%). It is more preferable that the above mass ratio (TFE / HFP / FAVE) is 75.0~98.0 / 1.0~15.0 / 1.0~10.0 (mass%). It is preferable that the TFE / HFP / FAVE copolymer contains 1% by mass or more of HFP units and FAVE units in total.

[0505] The TFE / HFP copolymer may further contain other ethylenically active monomer (α) units other than TFE units, HFP units, and FAVE units. These other ethylenically active monomer (α) units are not particularly limited as long as they are copolymerizable with TFE, HFP, and FAVE, and include, for example, fluorinated ethylenically active monomers such as vinyl fluoride (VF), vinylidene fluoride (VdF), and chlorotrifluoroethylene (CTFE); and non-fluorinated ethylenically active monomers such as ethylene, propylene, and alkyl vinyl ethers. The content of these other ethylenically active monomer (α) units is preferably 0 to 25.0% by mass, and more preferably 0.1 to 25.0% by mass.

[0506] When the above copolymer is a TFE / HFP / FAVE / other ethylenically active monomer (α) copolymer, the mass ratio (TFE / HFP / FAVE / other ethylenically active monomer (α)) is preferably 70.0~98.0 / 0.1~25.0 / 0.1~25.0 / 0.1~25.0 (mass%). The above TFE / HFP / FAVE / other ethylenically active monomer (α) copolymer preferably contains a total of 1% by mass or more of monomer units other than TFE units.

[0507] The melting point of the TFE / HFP copolymer is preferably 200 to 322°C, more preferably 220°C or higher, even more preferably 240°C or higher, more preferably 300°C or lower, even more preferably 280°C or lower, and particularly preferably 270°C or lower.

[0508] The melt flow rate of the melt-processable fluororesin is preferably 0.1 to 70 g / 10 min, more preferably 1.0 g / 10 min or more, more preferably 60 g / 10 min or less, even more preferably 50 g / 10 min or less, still more preferably 40 g / 10 min or less, and particularly preferably 30 g / 10 min or less.

[0509] In this disclosure, the melt flow rate of the melt-processable fluororesin is a value obtained in accordance with ASTM D1238, using a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) as the mass of polymer flowing out of a nozzle with an inner diameter of 2.1 mm and a length of 8 mm per 10 minutes at 372 °C and a load of 5 kg (g / 10 min).

[0510] The aqueous fluoropolymer dispersion of this disclosure can be suitably used in paint compositions, and can be suitably used in liquid paint compositions. The paint composition of this disclosure contains an aqueous fluoropolymer dispersion in which the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms is reduced, thereby providing a film with a large contact angle and a low coefficient of friction. The reason for this is not clear, but it is presumed that because the aqueous fluoropolymer dispersion contains a low content of fluorine-containing compounds having hydrophilic groups, the dispersion stability of fluoropolymer particles in the paint composition is moderately low, and therefore, during film formation, fluoropolymer particles are more likely to float to the surface of the film than other components, resulting in a higher proportion of fluoropolymer on the film surface.

[0511] The coating composition of this disclosure may contain other components in addition to the above-described aqueous fluoropolymer dispersion. Examples of other components include film-forming agents and binder resins.

[0512] The paint compositions of this disclosure can be prepared by mixing the fluoropolymer aqueous dispersion of this disclosure with other components. Alternatively, the fluoropolymer aqueous dispersion of this disclosure may be mixed with an aqueous medium to prepare a paint composition with an adjusted solids content. Alternatively, the fluoropolymer aqueous dispersion of this disclosure may be mixed with a nonionic surfactant to prepare a paint composition with an adjusted nonionic surfactant content. The paint compositions of this disclosure may have a different fluoropolymer content than the fluoropolymer aqueous dispersion of this disclosure, and may also have a different nonionic surfactant content than the fluoropolymer aqueous dispersion of this disclosure.

[0513] In one embodiment, the paint composition of the present disclosure contains a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms. The content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the paint composition is greater than 0 ppb by mass and less than 300 ppb by mass relative to the paint composition. The preferred upper limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the paint composition is 280 ppb by mass or less, 260 ppb by mass or less, 240 ppb by mass or less, 220 ppb by mass or less, 200 ppb by mass or less, 180 ppb by mass or less, 160 ppb by mass or less, or 140 ppb by mass or less. The preferred lower limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the paint composition is 0.1 ppb by mass or more, 1 ppb by mass or more, 5 ppb by mass or more, 10 ppb by mass or more, 20 ppb by mass or more, 30 ppb by mass or more, or 40 ppb by mass or more.

[0514] Examples of fluorine-containing compounds having a hydrophilic group with 7 or fewer carbon atoms include those described above as fluorine-containing surfactants having 7 or fewer carbon atoms used in the polymerization of fluoromonomers. That is, in one embodiment of the paint composition, at least a fluorine-containing surfactant having 7 or fewer carbon atoms is included as a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms.

[0515] In one embodiment, the paint composition of the present disclosure contains a fluorine-containing compound having a hydrophilic group. The content of the fluorine-containing compound having a hydrophilic group in the paint composition is greater than 0 ppb by mass and less than 300 ppb by mass relative to the paint composition. The preferred upper limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the paint composition is 280 ppb by mass or less, 260 ppb by mass or less, 240 ppb by mass or less, 220 ppb by mass or less, 200 ppb by mass or less, 180 ppb by mass or less, 160 ppb by mass or less, or 140 ppb by mass or less. The preferred lower limit of the content of the fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms in the paint composition is 0.1 ppb by mass or more, 1 ppb by mass or more, 5 ppb by mass or more, 10 ppb by mass or more, 20 ppb by mass or more, 30 ppb by mass or more, or 40 ppb by mass or more.

[0516] Examples of fluorine-containing compounds having hydrophilic groups include those mentioned above as fluorine-containing surfactants used in the polymerization of fluoromonomers.

[0517] <Membrane-forming agent> One embodiment of the paint composition of this disclosure contains a film-forming agent. When a film-forming agent is included, the paint composition can suppress the occurrence of cracks during the drying of the resulting film and has excellent workability.

[0518] Examples of film-forming agents include acrylic resins such as depolymerizable acrylic resins, urethane resins, polyethylene glycol, and polypropylene glycol.

[0519] When the coating composition of this disclosure is applied, dried, and then fired, the depolymerizable acrylic resin gradually decomposes while maintaining its binder effect on the fluoropolymer, thus preventing the occurrence of cracks.

[0520] In one embodiment of the coating composition of this disclosure, a depolymerizable acrylic resin is contained together with PTFE. Preferably, the depolymerizable acrylic resin is one that, even if depolymerization begins below the melting point of PTFE, remains until the temperature at which PTFE begins to melt (melting temperature), and decomposes and volatilizes at the firing (processing) temperature. For example, it is preferable that 5% or more, particularly 10% or more, and at least 50%, preferably at least 20%, remains at the melting temperature of PTFE (usually 240-345°C), and 10% or less, particularly 5% or less, remains at the firing (processing) temperature (usually a temperature above the melting temperature of PTFE and up to 415°C, preferably 360-400°C), and substantially no remains at the completion of firing. From this point of view, it is desirable that the depolymerization (decomposition) temperature of the depolymerizable acrylic resin be about 200°C or higher and below the firing (processing) temperature. In particular, regardless of the type of resin, a depolymerizable acrylic resin that retains approximately 25-50% of its original properties in the temperature range of 300-320°C and approximately 20-10% in the temperature range of 330-345°C is preferable in terms of the balance between its ability to prevent shrinkage cracks and its ability to prevent discoloration. Any depolymerizable acrylic resin that meets these conditions can be used.

[0521] Depolymerizability is generally described in "Polym.Eng.Soi., Vol.6, p273 (1966)", "Plast.Massy., Vol.75, p48 (1971)", and "Degradation of Polymer Materials" Corona Co., Ltd., p. 144 (1958) as the more branches there are in the polymerization chain, the weaker the CC and CH bonds become, making it easier to depolymerize through oxidative decomposition. Examples of depolymerizable acrylic resins include methacrylate resins, specifically, for example, formula (8): CH2=C(CH3)COOR A methacrylate homopolymer or copolymer is preferred, which requires a methacrylate monomer represented by the formula (wherein R is an alkyl group or hydroxyalkyl group having 1 to 5 carbon atoms). Specific examples of methacrylate monomers that are preferably used include methyl methacrylate, ethyl methacrylate, propyl methacrylate, dimethylpropyl methacrylate, butyl methacrylate, and pentyl methacrylate. Of these, a depolymerizable acrylic resin using butyl methacrylate as the monomer is preferred due to its low glass transition temperature and good depolymerizability (degradability).

[0522] Furthermore, while it is acceptable if a stable emulsion can be formed with a homopolymer, from the viewpoint of stabilizing the emulsion, monomers having carboxyl groups or hydroxyl groups may be used as appropriate comonomers.

[0523] Depolymerizable acrylic resins can be used as is, in the form of fine particles (depolymerizable acrylic resin emulsion) produced by methods such as emulsion polymerization, with an average particle size of 0.1 to 100 μm, and particularly preferably 0.2 to 1 μm. Particles with an average particle size of less than 0.1 μm tend to develop mud cracks, while those exceeding 100 μm tend to be difficult to paint.

[0524] In the coating composition of this disclosure, the content of the depolymerizable acrylic resin is preferably 5 to 25 parts, more preferably 7 to 20 parts, and even more preferably 10 to 15 parts per 100 parts of the fluoropolymer, from the viewpoint of film-forming properties and prevention of discoloration of the film.

[0525] Depolymerizable acrylic resins are preferably mixed with other components in the form of an emulsion.

[0526] <Binder resin> One embodiment of the paint composition of this disclosure contains a binder resin. When a binder resin is included, the paint composition can provide a film with excellent adhesion to the substrate. The binder resin has the effect of improving the hardness and gloss of the resulting film.

[0527] Examples of binder resins include polyamide-imide (PAI), polyimide (PI), polyethersulfone (PES), polyarylene sulfide (PAS), polyetherimide, polyetheretherketone, and aromatic polyester. Binder resins may be used individually or in combination of two or more.

[0528] PAI is a resin composed of polymers having amide and imide bonds in their molecular structure. While PAI is not particularly limited, examples include resins composed of high molecular weight polymers obtained by reactions such as: the reaction of an aromatic diamine having an amide bond in its molecule with an aromatic tetravalent carboxylic acid such as pyromellitic acid; the reaction of an aromatic trivalent carboxylic acid such as trimellitic anhydride with a diamine such as 4,4-diaminophenyl ether or a diisocyanate such as diphenylmethane diisocyanate; and the reaction of a dibasic acid having an aromatic imide ring in its molecule with a diamine. As PAI, polymers having aromatic rings in their main chain are preferred due to their excellent heat resistance.

[0529] PI is a resin made of a polymer having imide bonds in its molecular structure. While PI is not particularly limited, examples include resins made of high molecular weight polymers obtained by the reaction of aromatic tetravalent carboxylic acid anhydrides such as pyromellitic anhydride. As PI, those made of polymers having aromatic rings in the main chain are preferred due to their excellent heat resistance.

[0530] PES is given by the following general formula

[0531] [ka]

[0532] The resin is made of a polymer having repeating units represented by . The PES is not particularly limited, but examples include resins made of polymers obtained by polycondensation of dichlorodiphenylsulfone and bisphenol.

[0533] PAS is a resin made of a polymer having repeating units represented by the general formula -[Ar-S]- (wherein Ar represents an arylene group). The above PAS is not particularly limited, but examples include polyphenylene sulfide (PPS).

[0534] As the binder resin, at least one selected from the group consisting of PAI, PI, PES, and PPS is preferred, with PAI being more preferred, because it can provide a film with even better adhesion to the substrate. Furthermore, PES is preferred as the binder resin because it can suppress discoloration during firing and increase the degree of freedom in the color tone of the film. Using a combination of PAI and PES as the binder resin is also one preferred embodiment.

[0535] In the paint composition of this disclosure, the binder resin content is preferably 5% by mass or more, more preferably 8% by mass or more, preferably 15% by mass or less, and more preferably 12% by mass or less, relative to the paint composition. When the binder resin content is within the above range, a film with even better adhesion to the substrate can be obtained.

[0536] In the coating composition of this disclosure, the mass ratio of the fluoropolymer to the binder resin (fluoropolymer / binder resin) is preferably 90 / 10 to 50 / 50, more preferably 85 / 15 to 60 / 40, and even more preferably 80 / 20 to 70 / 30. When the mass ratio of the fluoropolymer to the binder resin is within the above range, a film with even better adhesion to the substrate can be obtained.

[0537] The coating compositions of this disclosure may contain other components. Examples of other components include preservatives, water-soluble polymer compounds, pigments, fillers, defoamers, drying agents, thickeners, organic solvents, leveling agents, anti-repellent agents, dispersants, antifreeze agents, solid lubricants, anti-settling agents, moisture absorbers, surface modifiers, thixotropy-imparting agents, viscosity modifiers, anti-gelling agents, ultraviolet absorbers, HALS (light stabilizers), matting agents, plasticizers, color separation inhibitors, anti-skinning agents, scratch inhibitors, rust inhibitors, antifungal agents, antibacterial agents, antioxidants, flame retardants, anti-sagging agents, antistatic agents, silane coupling agents, various reinforcing agents, various bulking agents, conductive fillers, colloidal silica, and the like.

[0538] The paint composition of this disclosure contains a preservative, which helps to suppress spoilage and bacterial growth of the paint composition even when it is stored for a long period of time.

[0539] Examples of preservatives include isothiazolone-based, azole-based, pronopol, chlorothalonil, methylsulfonyltetrachlorpyrozine, carbentadium, fluorophorbet, sodium diacetate, and diiodomethylparatolylsulfone.

[0540] The preservative content in the coating composition of this disclosure is preferably 0.01 to 0.5% by mass, and more preferably 0.05 to 0.2% by mass, relative to the fluoropolymer.

[0541] Examples of water-soluble polymer compounds include methylcellulose, 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.

[0542] Various conventionally known pigments can be used as pigments, such as titanium dioxide, carbon black, red iron oxide, and extender pigments. In the paint composition of this disclosure, the pigment content is preferably 0.1 to 20.0% by mass, and more preferably 1 to 10% by mass, relative to the paint composition.

[0543] Examples of fillers include inorganic fillers, diamond, fluorinated diamond, and carbon black.

[0544] Inorganic fillers include pigments, as well as mica particles, mica particles coated with pigments, titanium-coated mica, zirconium, tantalum, titanium, tungsten, silicon, aluminum, or beryllium inorganic nitrides, carbides, borides, and oxides (specifically, aluminum oxide, silicon carbide, zirconium oxide, zirconium carbide, etc.), metal flakes, metal powders, clay, talc, tourmaline, jade, germanium, corundum, silica, chrysoberyl, topaz, beryl, garnet, quartz, garnet, barium sulfate, and glass.

[0545] Inorganic fillers provide the function of improving abrasion resistance, and mica is preferred for its aesthetic appeal. The particle size of the mica particles is 10 to 100 μm, preferably 15 to 50 μm. If the particle size is less than 10 μm, abrasion resistance and luster tend to decrease, and if it exceeds 100 μm, non-stick properties tend to decrease. Mica particles coated with pigment can be obtained by attaching pigments such as TiO2·Fe2O3 to the mica particles by a sintering vapor deposition method.

[0546] Examples of metal flakes include titanium, zirconium, aluminum, zinc, antimony, tin, iron, and nickel, but titanium and zirconium are preferred due to their resistance to rust. The flakes can be in sizes that are typically used in paints.

[0547] Examples of metal powders include gold, silver, copper, platinum, and stainless steel powders.

[0548] Various types of water-based defoaming agents can be used, including lower alcohols such as methanol, ethanol, and butanol; higher alcohols such as amyl alcohol, polypropylene glycol, and its derivatives; oils and fats such as oleic acid, tall oil, mineral oil, and soap; surfactants such as sorbitan fatty acid esters, polyethylene glycol fatty acid esters, and pluronic nonionic surfactants; and silicone-based surfactants such as siloxane and silicone resins. These are used alone or in combination. Representative commercially available defoaming agents include the B-series (manufactured by Asahi Denka Kogyo Co., Ltd.), such as Adekanate B and Adekanate B1068; the SN Deformer series, such as Formaster DL, Nopco NXZ, and SN Deformer 113, 325, 308, and 368; Dehydrane 1293 and Dehydrane 1513 (manufactured by Sunopco Co., Ltd.); and Flonon SB-110N, SB-210, 510, 551, Aquarene 800, and 805. Examples include Aqualene 1488 (manufactured by Kyoeisha Chemical Co., Ltd.); Surfinol 104E, 440 (acetylene-based defoaming agent manufactured by Air Products Corporation); KS-607A (manufactured by Shin-Etsu Chemical Co., Ltd.); FS Antifoam (manufactured by Dow Corning); BYK-020, 031, 073, W (manufactured by Big Chemie Corporation); Dehydrane 981 (manufactured by Henkel Hakusui Co., Ltd.); Epan-410, 710, 720 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); Tego Foamex series (manufactured by Tego Goldschmidt); Foamlex-747, TY-10, EP series (manufactured by Nikka Chemical Co., Ltd.). The content of the defoaming agent in the paint composition is preferably 0.01 to 10% by mass, and more preferably 0.05 to 5% by mass.

[0549] Examples of desiccants include cobalt oxide.

[0550] Examples of thickening agents include methylcellulose, polyvinyl alcohol, and carboxylated vinyl polymer. In the coating composition of this disclosure, the content of the thickening agent is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.

[0551] High-boiling point polyhydric alcohols are preferred as organic solvents. High-boiling point polyhydric alcohols can prevent the occurrence of mud cracks when the coating composition of this disclosure is applied and then dries.

[0552] High-boiling-point polyhydric alcohols (hereinafter referred to as polyhydric alcohols) are those having two or more hydroxyl groups and a boiling point of 100°C or higher. Polyhydric alcohols containing nitrogen atoms are undesirable because they cause discoloration due to thermal decomposition during firing. Preferably, the boiling point is above the drying temperature of the paint composition, more preferably 150°C or higher, and particularly 200°C or higher. Polyhydric alcohols preferably have 2 to 3 hydroxyl groups. Substances with one or zero hydroxyl groups and a boiling point of 100°C or higher have poor hydrophilicity, making uniform mixing difficult. Many polyhydric alcohols with four or more hydroxyl groups are solid at room temperature, making it difficult to expect them to prevent mud cracks.

[0553] The polyhydric alcohol must ultimately evaporate or decompose completely through heating during the calcination process described later. Therefore, it is preferable that the boiling point or thermal decomposition temperature of the polyhydric alcohol is below the melting temperature of the fluoropolymer contained in the paint composition, preferably below 340°C.

[0554] Suitable polyhydric alcohols include, for example, one or more of the following: ethylene glycol (boiling point: 198°C), 1,2-propanediol (boiling point: 188°C), 1,3-propanediol (boiling point: 214°C), 1,2-butanediol (boiling point: 190°C), 1,3-butanediol (boiling point: 208°C), 1,4-butanediol (boiling point: 229°C), 1,5-pentanediol (boiling point: 242°C), 2-butene-1,4-diol (boiling point: 235°C), glycerin (boiling point: 290°C), 2-ethyl-2-hydroxymethyl-1,3-propanediol (boiling point: 295°C), and 1,2,6-hexanetriol (boiling point: 178°C under a pressure of 5 mmHg). Glycerin is particularly preferred.

[0555] In the coating composition of this disclosure, the polyhydric alcohol content is generally 5 to 18% by mass, preferably 7 to 15% by mass, and particularly preferably 7 to 12% by mass, relative to the fluoropolymer. By having a polyhydric alcohol content within the above range, it is possible to prevent the occurrence of mud cracks while preventing discoloration of the resulting film.

[0556] Furthermore, if necessary, organic solvents other than high-boiling point polyhydric alcohols may be added to the extent that they do not impair the effects of the present disclosure. Examples of such organic solvents include aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents having 9 to 11 carbon atoms, and aliphatic hydrocarbon solvents having 10 to 12 carbon atoms.

[0557] A coating can be obtained by using the coating composition of this disclosure. The coating obtained from the coating composition of this disclosure has excellent water-repellent and oil-repellent properties and low friction properties.

[0558] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims.

[0559] <1> According to the first aspect of this disclosure, A method for producing an aqueous fluoropolymer dispersion containing a fluoropolymer, An aqueous dispersion containing a fluoropolymer is prepared by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium. A nonionic surfactant is added to the resulting aqueous dispersion, the pH of the aqueous dispersion is adjusted to 7 or higher, and the temperature of the aqueous dispersion is adjusted to 35°C or higher. An aqueous dispersion containing a nonionic surfactant is brought into contact with at least one treatment agent selected from the group consisting of ion exchange resins and adsorbents. A manufacturing method is provided. <2> According to the second aspect of this disclosure, A first method for producing an aqueous dispersion containing a nonionic surfactant is provided, in which the temperature of the aqueous dispersion is adjusted to 35°C or higher and below the cloud point of the nonionic surfactant. <3> According to the third aspect of this disclosure, A manufacturing method is provided according to a first or second aspect, wherein the content of the fluoropolymer in the aqueous dispersion containing a nonionic surfactant when in contact with the processing agent is 10% by mass or more relative to the aqueous dispersion. <4> According to the fourth aspect of this disclosure, A manufacturing method is provided that involves repeating contact between an aqueous dispersion and a treatment agent two or more times, according to any of the first to third viewpoints. <5> According to the fifth aspect of this disclosure, A method for producing a nonionic surfactant, represented by general formula (i), is provided, according to any of the first to fourth aspects. R 6 -OA 1 -H (i) (In the formula, R 6 A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. 1 (This is a polyoxyalkylene chain.) <6> According to the sixth aspect of this disclosure, A manufacturing method is provided according to any of the first to fifth aspects, comprising further adding a nonionic surfactant to an aqueous dispersion obtained after contact with a processing agent, and concentrating the aqueous dispersion containing the nonionic surfactant. <7> According to the seventh aspect of this disclosure, A sixth method of production is provided, which involves separating the aqueous dispersion into two or more phases and recovering the concentrated phase to concentrate the aqueous dispersion. <8> According to the eighth aspect of this disclosure, A manufacturing method according to a sixth or seventh aspect is provided, comprising adding a nonionic surfactant to a concentrated aqueous dispersion. <9> According to the ninth aspect of this disclosure, A manufacturing method is provided that involves adding one or more of a pH adjuster, a viscosity adjuster, and a preservative to a concentrated aqueous dispersion, according to any of the sixth to eighth aspects. <10> According to the tenth aspect of this disclosure, A fluoropolymer aqueous dispersion, It contains a fluoropolymer, a nonionic surfactant, and a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms. The fluoropolymer content is 50-75% by mass relative to the aqueous dispersion of fluoropolymer. The content of the nonionic surfactant is 4.0 to 12% by mass relative to the fluoropolymer. The content of a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms is greater than 0 ppb by mass and less than 300 ppb by mass relative to the aqueous dispersion of the fluoropolymer. A fluoropolymer aqueous dispersion is provided. <11> According to the eleventh aspect of this disclosure, A nonionic surfactant is provided in an aqueous dispersion of a fluoropolymer according to a tenth aspect, represented by general formula (i). R 6 -OA 1 -H (i) (In the formula, R 6 A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. 1 (This is a polyoxyalkylene chain.) <12> According to the 12th aspect of this disclosure, A fluoropolymer aqueous dispersion is provided, in which the fluoropolymer contains perfluoro(alkyl vinyl ether) units, according to a tenth or eleventh aspect. <13> According to the 13th aspect of this disclosure, A fluoropolymer aqueous dispersion according to the twelfth aspect, substantially free of fluorine-containing compounds having a hydrophilic group represented by general formula (2). General formula (2):[C n-1 F 2n-1 COO - ]M + (In the formula, n is an integer between 9 and 14, M + (This represents a cation.) <14> According to the fourteenth aspect of this disclosure, A fluoropolymer aqueous dispersion is provided, in any of the 10th to 13th views, wherein the fluoropolymer is polytetrafluoroethylene. <15> According to the 15th aspect of this disclosure, A fluoropolymer aqueous dispersion is provided, wherein the fluoropolymer is at least one melt-processable fluororesin selected from the group consisting of tetrafluoroethylene / fluoroalkyl vinyl ether copolymers and tetrafluoroethylene / hexafluoropropylene copolymers, according to any 10th to 13th viewpoint. <16> According to the sixteenth aspect of this disclosure, Fluoropolymers A tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (excluding copolymers containing hexafluoropropylene units) comprising tetrafluoroethylene units and fluoroalkyl vinyl ether units, wherein the content of fluoroalkyl vinyl ether units is 1.0 to 10.0% by mass relative to the total monomer units constituting the fluoropolymer. A tetrafluoroethylene / hexafluoropropylene copolymer consisting solely of tetrafluoroethylene units and hexafluoropropylene units, wherein the content of hexafluoropropylene units is 1.0 to 15.0% by mass relative to the total monomer units constituting the fluoropolymer, and A tetrafluoroethylene / hexafluoropropylene / fluoroalkyl vinyl ether copolymer containing at least tetrafluoroethylene units, hexafluoropropylene units, and fluoroalkyl vinyl ether units, wherein the content of hexafluoropropylene units is 1.0 to 15.0% by mass relative to the total monomer units constituting the fluoropolymer, and the content of fluoroalkyl vinyl ether units is 0.1 to 10.0% by mass relative to the total monomer units constituting the fluoropolymer. A fluoropolymer aqueous dispersion is provided, which is at least one melt-processable fluororesin selected from the group consisting of the following, according to any of the 10th to 13th viewpoints. <17> According to the seventeenth aspect of this disclosure, A fluoropolymer aqueous dispersion is provided, according to a 15th or 16th aspect, wherein the melting point of the melt-processable fluororesin is 200 to 322°C. <18> According to the 18th aspect of this disclosure, A paint composition containing an aqueous dispersion of a fluoropolymer according to any of the 10th to 17th aspects is provided. [Examples]

[0560] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to such embodiments.

[0561] Each value in the examples was measured by the following method.

[0562] (1) Solid content concentration (P) Approximately 1 g (X g) of the sample was placed in a 5 cm diameter aluminum cup, heated at 110°C for 30 minutes, and then heated again at 300°C for 30 minutes. Based on the residual volume (Z g), the formula P = Z / X × 100 (mass%) was used to determine the concentration.

[0563] (2) Average primary particle diameter A calibration curve was created by diluting an aqueous dispersion with water until the solid content concentration reached 0.15% by mass. The transmittance of 550 nm projected light per unit length of the resulting diluted aqueous dispersion and the average primary particle diameter determined by measuring the directional diameter using transmission electron microscopy were then measured. Using this calibration curve, the average primary particle diameter was determined from the measured transmittance of 550 nm projected light for each sample.

[0564] (3) pH Using a glass electrode (manufactured by Horiba, Ltd.), the pH was measured at 25°C in accordance with JIS K6893.

[0565] (4) Standard specific gravity (SSG) Samples molded in accordance with ASTM D4895-89 were used, and measurements were performed using the water displacement method in accordance with ASTM D-792.

[0566] (5) Content of modified monomers The perfluoro(propyl vinyl ether) (PPVE) content was determined by creating a thin film disc by press-molding PTFE powder and measuring the infrared absorbance of the thin film disc using FT-IR, resulting in a value of 995 cm⁻¹. -1 Absorbance at 935 cm² -1 The ratio of absorbances in each region was multiplied by 0.14 to determine the result.

[0567] (6) Content of nonionic surfactant (N) Approximately 1 g (X g) of the sample was placed in a 5 cm diameter aluminum cup and heated at 110°C for 30 minutes. The resulting residue (Y g) was then heated at 300°C for 30 minutes. The remaining residue (Z g) was obtained by subtracting the amount of stabilizer from the amount calculated using the formula: N = [(YZ) / Z] × 100 (mass%). The amount of stabilizer was calculated based on the amount added during preparation.

[0568] (7) Viscosity A Type B rotational viscometer (manufactured by Toki Sangyo Co., Ltd., rotor No. 2) was used to measure viscosity at 25°C under the conditions of a rotation speed of 60 rpm and a measurement time of 120 seconds.

[0569] (8) Measurement of the content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms 5.0 g of aqueous dispersion was weighed, 10 g of methanol was added, and the mixture was poured into a cylindrical filter paper. Soxhlet extraction was performed until the total amount of methanol used as the extraction solvent reached 150 g. The resulting extract was then diluted with methanol to a volume of 250 ml to obtain an extract containing a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms.

[0570] Calibration curve Five levels of methanol standard solutions were prepared for fluorine-containing compounds with hydrophilic groups having 7 or fewer carbon atoms, with concentrations ranging from 0.1 to 100 ng / mL. These solutions were measured using a liquid chromatograph-mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). A calibration curve was created using a first-order approximation based on the sample concentration and the integrated peak values.

[0571] The content of fluorinated compounds with hydrophilic groups having 7 or fewer carbon atoms was measured using a liquid chromatography-mass spectrometer. For the extract, the peak area of ​​fluorinated compounds with hydrophilic groups having 7 or fewer carbon atoms was determined by MRM, and the content of these compounds in the aqueous dispersion was then determined. The limit of quantification was 10 mass ppb.

[0572] (9) Measurement of the content of fluorine-containing compounds having a hydrophilic group represented by general formula (2) 5.0 g of aqueous dispersion was weighed, 10 g of methanol was added, and the mixture was poured into a cylindrical filter paper. Soxhlet extraction was performed until the total amount of methanol used as the extraction solvent reached 150 g. The resulting extract was then diluted with methanol to a volume of 250 ml to obtain an extract containing a fluorine-containing compound having a hydrophilic group represented by general formula (2). General formula (2):[C n-1 F 2n-1 COO - ]M + (In the formula, n is an integer between 9 and 14, M + (This represents a cation.)

[0573] Calibration curve Five levels of methanol standard solutions of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotridecanoic acid (PFTrDA), and perfluorotetradecanoic acid (PFTeDA) with known concentrations ranging from 0.1 to 50 ng / mL were prepared and measured using a liquid chromatograph-mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). Calibration curves were created using a first-order approximation based on the concentration of each sample and the integral value of the peak.

[0574] Using a liquid chromatography mass spectrometer, the content of the fluorine-containing compound having a hydrophilic group represented by the general formula (2) was measured. For the extract, the peak area of the fluorine-containing compound having a hydrophilic group represented by the general formula (2) was determined by the MRM method, and the content of the fluorine-containing compound having a hydrophilic group represented by the general formula (2) contained in the aqueous dispersion was determined. The limit of quantification was 10 mass ppb.

[0575] Measuring instrument configuration and LC-MS measurement conditions [Table 1]

[0576] MRM measurement parameters [Table 2]

[0577] The average molecular structures of the surfactants used in the examples and comparative examples are shown below. Surfactant (a): C 13 H 27 O(CH2CH2O)8H (average number of methyl groups per molecule 4.0), HLB 13.30, cloud point 60 °C Surfactant (b): C 13 H 27 O(CH2CH2O) 10 H (average number of methyl groups per molecule 4.0), HLB 13.80, cloud point 71 °C

[0578] Synthesis Example 1 White solid A was obtained by the method described in Synthesis Example 1 of International Publication No. 2021 / 045228. The obtained white solid A was a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms.

[0579] Production Example 1 In a 6L stainless steel reactor equipped with a stirrer, 3580g of deionized water, 160g of paraffin wax, and 4.7g of white solid A obtained in Synthesis Example 1 as a fluorine-containing surfactant were added. The contents of the reactor were then heated to 70°C while being aspirated and simultaneously purged with TFE to remove oxygen from the reactor, and the contents were stirred. 6.5g of PPVE was injected into the reactor under pressure with TFE. 50mg of APS dissolved in 20g of deionized water was injected into the reactor as an initiator, and the pressure was set to 1.5MPaG. TFE was added to maintain a constant pressure of 1.5MPaG. When the amount of TFE consumed in the reaction reached 1543g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated.

[0580] Subsequently, the reactor was evacuated until the pressure reached atmospheric pressure, then the pressure was further reduced to -0.01 MPaG, nitrogen was added to the reactor, and the pressure was adjusted to atmospheric pressure (0.00 MPaG) to obtain PTFE aqueous dispersion 1-1.

[0581] PTFE aqueous dispersion 1-1 was removed from the reactor and cooled to the atmosphere, and the paraffin wax was removed to obtain PTFE aqueous dispersion 1-2. The obtained PTFE aqueous dispersion 1-2 had a solid content concentration of 30.0% by mass, an average primary particle size of 270 nm, and a pH of 3.6.

[0582] The obtained PTFE aqueous dispersions 1-2 were diluted with deionized water to a solid content concentration of approximately 10% by mass, solidified under high-speed stirring conditions, and the solidified wet powder was dried at 150°C for 18 hours. The standard specific gravity of the obtained PTFE powder was 2.163, and the PPVE content was 0.28% by mass.

[0583] Comparative Example 1 To the PTFE aqueous dispersion 1-2 obtained in Production Example 1, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PTFE to prepare PTFE aqueous dispersion C-1.

[0584] To an aqueous PTFE dispersion at a liquid temperature of 20°C, a strongly basic anion exchange resin (DuPont IRA4002OH) was added in a ratio of 60 parts by mass per 100 parts by mass of PTFE. After gentle stirring for 180 minutes, the anion exchange resin was separated by filtration to obtain aqueous PTFE dispersion C-2. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0023 m². 2 The ion exchange capacity of the ion exchange resin was 0.55 meq / g. The obtained PTFE aqueous dispersion C-2 had a solid content concentration of 28.8% by mass, a nonionic surfactant content of 10.1% by mass relative to the PTFE, and a pH of 11.2.

[0585] The perfluorononanoic acid (PFNA) content was below the limit of quantification (10 ppb by mass), and the perfluorotridecanoic acid (PFTrDA) content was 21 ppb by mass in the aqueous dispersion.

[0586] Experimental Example 1 To the PTFE aqueous dispersion 1-2 obtained in Production Example 1, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PTFE, and then aqueous ammonia was added to adjust the pH to 10.0 to prepare PTFE aqueous dispersion 1-3.

[0587] PTFE aqueous dispersions 1-3 were heated to 40°C, and a strongly basic anion exchange resin (DuPont IRA4002OH) was added in a ratio of 60 parts by mass per 100 parts by mass of PTFE. After gentle stirring for 180 minutes, the anion exchange resin was separated by filtration to obtain PTFE aqueous dispersion 1-4. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0023 m². 2 The ion exchange capacity of the ion exchange resin was 0.55 meq / g. The obtained aqueous PTFE dispersions 1-4 had a solid content concentration of 28.9% by mass, a nonionic surfactant content of 10.0% by mass relative to the PTFE, and a pH of 11.3.

[0588] The content of perfluorononanoic acid (PFNA) and perfluorotridecanoic acid (PFTrDA) was below the limit of quantification (10 mass ppb).

[0589] Comparative Example 2 The aqueous PTFE dispersion C-2 obtained in Comparative Example 1 was used. An anion exchange resin was added again to the aqueous PTFE dispersion C-2 at a liquid temperature of 20°C, and after gentle stirring for 180 minutes, the anion exchange resin was separated by filtration to obtain aqueous PTFE dispersion C-3. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0046 m². 2 The exchange capacity of the ion exchange resin was 1.10 meq / g.

[0590] To the obtained PTFE aqueous dispersion C-3, surfactant (a) was added in an amount of 16 parts by mass per 100 parts by mass of PTFE, and the mixture was held at 63°C for 3 hours to separate the supernatant phase from the concentrated phase. Only the concentrated phase was collected to obtain PTFE aqueous dispersion C-4. The obtained PTFE aqueous dispersion C-4 had a solid content concentration of 69.1% by mass and a nonionic surfactant content of 2.7% by mass relative to the PTFE.

[0591] To the obtained PTFE aqueous dispersion C-4, surfactant (b) was added to a concentration of 5.0% by mass relative to the PTFE, ammonium lauryl sulfate was added at 500 ppm relative to the PTFE, an isothiazolone-based preservative was added at 1000 ppm relative to the PTFE, and aqueous ammonia was added to adjust the pH to 9.5. Furthermore, deionized water was added to adjust the solid content to 63% by mass to obtain PTFE aqueous dispersion C-5. The obtained PTFE aqueous dispersion C-5 had a solid content concentration of 62.9% by mass, a nonionic surfactant content of 5.0% by mass relative to the PTFE, a pH of 9.5, and a viscosity of 26.8 mPa·s.

[0592] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 560 ppb by mass in the aqueous dispersion.

[0593] Example 1 The PTFE aqueous dispersions 1-4 obtained in Experimental Example 1 were heated again to 40°C, anion exchange resin was added, and the mixture was gently stirred for 180 minutes. The anion exchange resin was then separated by filtration. The same procedure was repeated two more times to obtain PTFE aqueous dispersions 1-5. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0091 m². 2 The exchange capacity of the ion exchange resin was 2.20 meq / g.

[0594] To the obtained PTFE aqueous dispersions 1-5, surfactant (a) was added in an amount of 16 parts by mass per 100 parts by mass of PTFE, and the mixture was kept at 63°C for 3 hours to separate it into a supernatant phase and a concentrated phase. Only the concentrated phase was recovered to obtain PTFE aqueous dispersion 1-6.

[0595] To the obtained PTFE aqueous dispersions 1-6, surfactant (a) and deionized water were added so that the ratio of nonionic surfactant to PTFE and the ratio of water to PTFE were the same as before phase separation and concentration. The mixture was held at 61°C for 3 hours and separated into a supernatant phase and a concentrated phase. Only the concentrated phase was recovered to obtain PTFE aqueous dispersion 1-7. The obtained PTFE aqueous dispersion 1-7 had a solid content concentration of 70.5% by mass and a nonionic surfactant content of 2.5% by mass relative to PTFE.

[0596] To the obtained PTFE aqueous dispersion 1-7, surfactant (b), ammonium lauryl sulfate, isothiazolone-based preservative, and ammonia water were added in the same manner as in Comparative Example 2. Furthermore, deionized water was added to obtain PTFE aqueous dispersion 1-8 so that the solid content was 63% by mass. The obtained PTFE aqueous dispersion 1-8 had a solid content concentration of 63.0% by mass, a nonionic surfactant content of 5.0% by mass relative to PTFE, a pH of 9.4, and a viscosity of 26.5 mPa·s.

[0597] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 45 ppb by mass in the aqueous dispersion.

[0598] The content of fluorine-containing compounds having a hydrophilic group represented by general formula (2) with 9 to 14 carbon atoms was all below the limit of quantification (10 mass ppb).

[0599] Next, embodiments of the paint compositions containing the PTFE aqueous dispersion obtained in the above examples and comparative examples will be described with reference to examples.

[0600] Each value in the examples was measured by the following method. <Contact angle> The contact angles with water and n-cetane were measured using a CA-DT type contact angle meter manufactured by Kyowa Interface Science Co., Ltd.

[0601] <Coefficient of friction> Using a HEIDON Type 38 surface testing machine manufactured by Shinto Kagaku Co., Ltd., the static and kinetic friction coefficients were measured when a ball indenter was pressed with a load of 1 kg and moved at a speed of 600 mm / min.

[0602] In Comparative Example 3 and Example 2, the following materials were used.

[0603] Aqueous dispersion of polyamide-imide resin: Aqueous dispersion of polyamide-imide resin varnish prepared by the method described in Production Example 1 of International Publication No. 2016 / 147790.

[0604] 50% by mass aqueous solution of nonionic surfactant: 50% by mass aqueous solution of polyoxyethylene alkyl ether

[0605] Carbon black pigment mill base (solids content concentration: 20% by mass): A water-based black pigment paste made by grinding commercially available carbon black pigment (average particle size 100 nm or less) with a sand mill and glass beads as the dispersion medium, along with a nonionic surfactant and water.

[0606] Thickener: Methylcellulose Leveling agent: Acetylene glycol Depolymerizable acrylic resin emulsion: Butyl methacrylate resin, average particle size 0.3 μm, butyl methacrylate resin content 40% by mass Hydrocarbon solvents: Mixtures of C10-C12 aliphatic saturated hydrocarbons.

[0607] Comparative Example 3 Primer composition P-1 was obtained by stirring and mixing the following components. PTFE aqueous dispersion C-5 40.0 parts 39.0 parts of aqueous dispersion of polyamide-imide resin 8.0 parts of a 50% by mass aqueous solution of a nonionic surfactant Carbon black pigment mill base (solid content concentration: 20% by mass) 3.6 parts Thickening agent 7.0 parts Leveling agent 1.0 part 1.4 parts water

[0608] Furthermore, topcoat composition T-1 was obtained by stirring and mixing the following components. PTFE aqueous dispersion C-5 70.0 parts Depolymerizable acrylic resin emulsion 12.6 parts 7.9 parts of a 50% by mass aqueous solution of a nonionic surfactant Glycerin 3.1 parts Hydrocarbon solvent 1.3 parts Water 5.1 parts

[0609] Next, primer composition P-1 was applied to an aluminum substrate and dried at 100°C for 20 minutes. Subsequently, topcoat composition T-1 was applied to the primer film, dried at 100°C for 20 minutes, and then heated at 380°C for 20 minutes. The contact angle and coefficient of friction of the resulting film were measured. The results are shown in Table 3.

[0610] Example 2 A film was obtained using the same procedure as in Comparative Example 3, except that PTFE aqueous dispersion 1-8 was used instead of PTFE aqueous dispersion C-5 to obtain primer composition P-2 and topcoat composition T-2. The contact angle and coefficient of friction of this film were measured. The results are shown in Table 3.

[0611] [Table 3]

[0612] Manufacturing Example 2 Polymerization of the TFE / perfluoro(alkyl vinyl ether) copolymer was carried out using the method described in Preparation Example 1 of Japanese Patent No. 3336839. For polymerization, instead of C3F7OCF(CF3)CF2OCF(CF3)COONH4 as the fluorine-containing surfactant, 3.8 g of the white solid A obtained in Synthesis Example 1 was used.

[0613] Subsequently, the reactor was evacuated until the pressure reached atmospheric pressure, then the pressure was further reduced to -0.01 MPaG, nitrogen was added to the reactor, and the pressure was adjusted to atmospheric pressure (0.00 MPaG) to obtain PFA aqueous dispersion 2-1.

[0614] PFA aqueous dispersion 2-1 was removed from the reactor and cooled to the atmosphere, and the paraffin wax was removed to obtain PFA aqueous dispersion 2-2. The solid content concentration of the obtained PFA aqueous dispersion 2-2 was 15.5% by mass, and the pH was 3.1.

[0615] A portion of the obtained PFA aqueous dispersion 2-2 was mixed with ammonium carbonate as a coagulant, and the mixture was allowed to solidify under high-speed stirring conditions. The solidified wet powder was then dried at 130°C for 16 hours. The PPVE content was 2.5% by mass.

[0616] Comparative Example 4 To the PFA aqueous dispersion 2-2 obtained in Production Example 2, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PFA to prepare PFA aqueous dispersion C-6.

[0617] To a PFA aqueous dispersion C-6 at a liquid temperature of 20°C, a strongly basic anion exchange resin (DuPont IRA4002OH) was added in a ratio of 30 parts by mass per 100 parts by mass of PFA. After gentle stirring for 180 minutes, the anion exchange resin was separated by filtration. The anion exchange resin was again added to the obtained PFA aqueous dispersion, and after gentle stirring for 180 minutes, the anion exchange resin was separated by filtration to obtain PFA aqueous dispersion C-7. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0023 m². 2 The exchange capacity of the ion exchange resin was 0.55 meq / g.

[0618] To the obtained PFA aqueous dispersion C-7, surfactant (a) was added in an amount of 16 parts by mass per 100 parts by mass of PFA, and the mixture was kept at 63°C for 3 hours to separate the supernatant phase from the concentrated phase. Only the concentrated phase was collected, and surfactant (b) was added in an amount of 5.0% by mass relative to the PFA to obtain PFA aqueous dispersion C-8. The obtained PFA aqueous dispersion C-8 had a solid content concentration of 66.7% by mass and a nonionic surfactant content of 5.0% by mass relative to the PFA.

[0619] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 490 ppb by mass in the aqueous dispersion.

[0620] The perfluorononanoic acid (PFNA) content was 200 ppb by mass in the aqueous dispersion.

[0621] Example 3 To the PFA aqueous dispersion 2-2 obtained in Production Example 2, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PFA, and then aqueous ammonia was added to adjust the pH to 7.5 to prepare PFA aqueous dispersion 3-1.

[0622] In the aqueous PFA dispersion 3-1 at a liquid temperature of 35°C, the procedure of contacting the PFA with the treatment agent twice was performed in the same manner as in Comparative Example 4, except that a strongly basic anion exchange resin (A400, manufactured by Purolite Co., Ltd.) was used as the treatment agent. Furthermore, the same procedure was repeated four times to obtain aqueous PFA dispersion 3-2. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0060 m². 2 The exchange capacity of the ion exchange resin was 1.68 meq / g.

[0623] The obtained PFA aqueous dispersion 3-2 was subjected to a concentration procedure in the same manner as in Comparative Example 4, and only the concentrated phase was recovered. Surfactant (b) was added to obtain PFA aqueous dispersion 3-3. The obtained PFA aqueous dispersion 3-3 had a solid content concentration of 67.2% by mass and a nonionic surfactant content of 5.0% by mass relative to the PFA.

[0624] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 68 ppb by mass in the aqueous dispersion.

[0625] The perfluorononanoic acid (PFNA) content was 42 ppb by mass in the aqueous dispersion.

[0626] Example 4 A column packed with 180 parts by mass of A400 manufactured by Purolite Co., Ltd. per 100 parts by mass of PFA was passed through which PFA aqueous dispersion 3-1 at a liquid temperature of 35°C was obtained to obtain PFA aqueous dispersion 4-1. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0060 m². 2 The exchange capacity of the ion exchange resin was 1.68 meq / g.

[0627] The obtained PFA aqueous dispersion 4-1 was subjected to a concentration procedure in the same manner as in Comparative Example 4, and only the concentrated phase was recovered. Surfactant (b) was added to obtain PFA aqueous dispersion 4-2. The obtained PFA aqueous dispersion 4-2 had a solid content concentration of 68.0% by mass and a nonionic surfactant content of 5.1% by mass relative to the PFA.

[0628] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 55 ppb by mass in the aqueous dispersion.

[0629] The perfluorononanoic acid (PFNA) content was 40 ppb by mass in the aqueous dispersion.

[0630] Example 5 To the PFA aqueous dispersion 2-2 obtained in Production Example 2, surfactant (a) was added as a nonionic surfactant in an amount of 10 parts by mass per 100 parts by mass of PFA, and then aqueous ammonia was added to adjust the pH to 11.0 to prepare PFA aqueous dispersion 5-1.

[0631] To a PFA aqueous dispersion 5-1 at a liquid temperature of 45°C, DuPont IRA4002OH was added in a ratio of 60 parts by mass per 100 parts by mass of PFA. After gentle stirring for 180 minutes, the anion exchange resin was separated by filtration. The anion exchange resin was again added to the obtained PFA aqueous dispersion, and after gentle stirring for 180 minutes, the anion exchange resin was separated by filtration to obtain PFA aqueous dispersion 5-2. The contact area of ​​the treatment agent relative to the mass of the fluoropolymer was 0.0091 m². 2 The exchange capacity of the ion exchange resin was 2.20 meq / g.

[0632] The obtained PFA aqueous dispersion 5-2 was subjected to a concentration procedure in the same manner as in Comparative Example 4, and only the concentrated phase was recovered. Surfactant (b) was added to obtain PFA aqueous dispersion 5-3. The obtained PFA aqueous dispersion 5-3 had a solid content concentration of 67.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PFA.

[0633] The content of fluorine-containing compounds having hydrophilic groups with 7 or fewer carbon atoms, such as the fluorine-containing surfactant synthesized in Synthesis Example 1, was 49 ppb by mass in the aqueous dispersion.

[0634] The perfluorononanoic acid (PFNA) content was 36 ppb by mass in the aqueous dispersion.

[0635] Comparative Example 5 Top coat composition T-3 was obtained by stirring and mixing the following components. PFA aqueous dispersion C-8 74.6 parts 4.6 parts of a 50% by mass aqueous solution of a nonionic surfactant Ethylene glycol 5.0 parts Water 15.8 parts

[0636] Next, primer composition P-1 was applied to an aluminum substrate and dried at 100°C for 20 minutes. Subsequently, topcoat composition T-3 was applied to the primer film, dried at 100°C for 20 minutes, and then heated at 380°C for 20 minutes. The contact angle and coefficient of friction of the resulting film were measured. The results are shown in Table 4.

[0637] Example 6 A coating was obtained using the same procedure as in Comparative Example 5, except that topcoat composition T-4 was obtained by using PFA aqueous dispersion 5-3 instead of PFA aqueous dispersion C-8. The contact angle and coefficient of friction of this coating were measured. The results are shown in Table 4.

[0638] [Table 4]

Claims

1. A method for producing an aqueous fluoropolymer dispersion containing a fluoropolymer, An aqueous dispersion containing a fluoropolymer is prepared by polymerizing a fluoromonomer in the presence of a fluorine-containing surfactant and an aqueous medium. A nonionic surfactant is added to the resulting aqueous dispersion, the pH of the aqueous dispersion is adjusted to 7 or higher, and the temperature of the aqueous dispersion is adjusted to 35°C or higher. An aqueous dispersion containing a nonionic surfactant is brought into contact with at least one treatment agent selected from the group consisting of ion exchange resins and adsorbents. Manufacturing method.

2. The manufacturing method according to claim 1, wherein the temperature of an aqueous dispersion containing a nonionic surfactant is adjusted to 35°C or higher and below the cloud point of the nonionic surfactant.

3. The manufacturing method according to claim 1 or 2, wherein the content of the fluoropolymer in the aqueous dispersion containing a nonionic surfactant when in contact with the treatment agent is 10% by mass or more relative to the aqueous dispersion.

4. The manufacturing method according to claim 1 or 2, wherein the aqueous dispersion and the treatment agent are brought into contact two or more times.

5. The manufacturing method according to claim 1 or 2, wherein the nonionic surfactant is represented by general formula (i). R ６ -O-A １ -H (i) (In the formula, R ６ A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. １ (This is a polyoxyalkylene chain.)

6. The manufacturing method according to claim 1 or 2, wherein a nonionic surfactant is further added to the aqueous dispersion obtained after contact with the treatment agent, and the aqueous dispersion containing the nonionic surfactant is concentrated.

7. The manufacturing method according to claim 6, wherein the aqueous dispersion is concentrated by separating the aqueous dispersion into two or more phases and recovering the concentrated phase.

8. The manufacturing method according to claim 6, wherein a nonionic surfactant is added to a concentrated aqueous dispersion.

9. The manufacturing method according to claim 6, wherein one or more of a pH adjuster, a viscosity adjuster, and a preservative are added to a concentrated aqueous dispersion.

10. A fluoropolymer aqueous dispersion, It contains a fluoropolymer, a nonionic surfactant, and a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms. The fluoropolymer content is 50 to 75% by mass relative to the aqueous dispersion of fluoropolymer. The content of the nonionic surfactant is 4.0 to 12% by mass relative to the fluoropolymer. The content of a fluorine-containing compound having a hydrophilic group with 7 or fewer carbon atoms is greater than 0 ppb by mass and less than 300 ppb by mass relative to the aqueous dispersion of the fluoropolymer. The viscosity is 2.0 mPa·s or higher. Aqueous dispersion of fluoropolymer.

11. The fluoropolymer aqueous dispersion according to claim 10, wherein the nonionic surfactant is represented by general formula (i). R ６ -O-A １ -H (i) (In the formula, R ６ A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. １ (This is a polyoxyalkylene chain.)

12. The aqueous dispersion of a fluoropolymer according to claim 10 or 11, wherein the fluoropolymer contains perfluoro(alkyl vinyl ether) units.

13. The aqueous fluoropolymer dispersion according to claim 12, wherein the content of a fluorine-containing compound having a hydrophilic group represented by general formula (2) is 50 ppb by mass or less. General form (2): [C] ｎ－１ F ２ｎ－１ COO － M ＋ (In the formula, n is an integer from 9 to 14, M ＋ (This represents a cation.)

14. The aqueous dispersion of a fluoropolymer according to claim 10 or 11, wherein the fluoropolymer is polytetrafluoroethylene.

15. The aqueous dispersion of a fluoropolymer according to claim 10 or 11, wherein the fluoropolymer is at least one melt-processable fluororesin selected from the group consisting of tetrafluoroethylene / fluoroalkyl vinyl ether copolymers and tetrafluoroethylene / hexafluoropropylene copolymers.

16. Fluoropolymers A tetrafluoroethylene / fluoroalkyl vinyl ether copolymer comprising tetrafluoroethylene units and fluoroalkyl vinyl ether units (excluding copolymers containing hexafluoropropylene units), wherein the content of fluoroalkyl vinyl ether units is 1.0 to 10.0% by mass relative to the total monomer units constituting the fluoropolymer. A tetrafluoroethylene / hexafluoropropylene copolymer consisting solely of tetrafluoroethylene units and hexafluoropropylene units, wherein the content of hexafluoropropylene units is 1.0 to 15.0% by mass relative to the total monomer units constituting the fluoropolymer, and A tetrafluoroethylene / hexafluoropropylene / fluoroalkyl vinyl ether copolymer containing at least tetrafluoroethylene units, hexafluoropropylene units, and fluoroalkyl vinyl ether units, wherein the content of hexafluoropropylene units is 1.0 to 15.0% by mass relative to the total monomer units constituting the fluoropolymer, and the content of fluoroalkyl vinyl ether units is 0.1 to 10.0% by mass relative to the total monomer units constituting the fluoropolymer. The aqueous fluoropolymer dispersion according to claim 10 or 11, which is at least one melt-processable fluororesin selected from the group consisting of the above.

17. The aqueous dispersion of fluoropolymer according to claim 15, wherein the melting point of the melt-processable fluororesin is 200 to 322°C.

18. A paint composition containing the aqueous fluoropolymer dispersion according to claim 10 or 11.

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