Production method of fluoropolymer, production method of polytetrafluoroethylene, and composition

Abstract

To provide a production method of a fluoropolymer by using a polymer having many sulfonic acid groups or sulfonate groups, the fluoropolymer containing essentially no dimer and trimer of a monomer constituting the polymer but containing a polymerization unit derived from a perfluoromonomer in high content.SOLUTION: Provided is a production method of a fluoropolymer by polymerizing a perfluoromonomer polymerize in an aqueous medium in the presence of polymer (1), in which a content of a polymerization unit derived from the perfluoromonomer in the fluoropolymer is 90 mol% or more based on the total polymerization units of the fluoropolymer, the polymer (1) is a polymer of monomer (1) represented by general formula (1): CF2=CF-O-R-(Rf-SO3M)m, a polymerization unit (1) based on the monomer (1) in the polymer (1) is 50 mass% or more based on the total polymerization units of the polymer (1), and contents of the dimer and trimer of the monomer (1) in the polymer (1) is 1.0 mass% or less based on the polymer (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to methods for producing fluoropolymers, methods for producing polytetrafluoroethylene, and compositions. [Background technology]

[0002] Patent Document 1 describes a method for producing a fluoropolymer, which comprises emulsion polymerizing one or more fluorinated monomers in an aqueous medium, wherein the aqueous emulsion polymerization is carried out in an aqueous medium in the presence of at least one radical initiator and at least one polyfunctional dispersant [dispersant (D)], and the dispersant (D) is: - a backbone chain containing repeat units derived from one or more ethylenically unsaturated monomers, - the dispersant (D) has a molecular weight and a molecular weight distribution such that it is substantially free of fractions with molecular weights below 3000, -SO3X in an amount of at least 1.75 meq / g relative to the weight of the dispersant (D), a , -PO3X a , and -COOX a (X a is H, an ammonium group, or a monovalent metal; A method is described in which the dispersant (D) is used in an amount of 0.01% by weight and 5.00% by weight based on the total weight of the aqueous medium.

[0003] Patent Document 2 describes a method for producing a fluoropolymer, which includes a step of obtaining a fluoropolymer by polymerizing a fluoromonomer in an aqueous medium in the presence of a polymer (1) containing polymerized units (1) based on a monomer represented by the following general formula (1): CX2=CY(-CZ2-O-Rf-A) (1) (In the formula, X's are the same or different and are -H or -F; Y's are -H, -F, an alkyl group or a fluorine-containing alkyl group; Z's are the same or different and are -H, -F, an alkyl group or a fluoroalkyl group; Rf's are fluorine-containing alkylene groups having 1 to 40 carbon atoms or fluorine-containing alkylene groups having 2 to 100 carbon atoms and an ether bond; A's are -COOM, -SO3M or -OSO3M (M's are -H, a metal atom, -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group, provided that at least one of X, Y, and Z contains a fluorine atom.

[0004] Patent Document 3 describes a method for producing an aqueous fluoropolymer dispersion, which comprises a step A of carrying out ultrafiltration, microfiltration, or dialysis membrane treatment, or a combination thereof, on a pre-treatment aqueous dispersion containing a fluoropolymer (excluding the polymer (I)) obtained by polymerization in the presence of a polymer (I) containing polymerization units (I) based on a monomer represented by the following general formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H, or CF; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2020-510737 [Patent Document 2] International Publication No. 2019 / 168183 [Patent Document 3] International Publication No. 2020 / 218620 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure aims to provide a method for producing a fluoropolymer using a polymer having a large number of sulfonic acid groups or sulfonate salt groups, which method is capable of producing a fluoropolymer that is substantially free of dimers and trimers of the monomers that constitute the polymer and that contains a high content of polymerization units based on perfluoromonomers.

[0007] Another object of the present disclosure is to provide a method for producing polytetrafluoroethylene using a polymer having sulfonic acid groups or sulfonate salt groups, which method is capable of producing polytetrafluoroethylene that is substantially free of dimers and trimers, which are the monomers that constitute the polymer, and has a high molecular weight.

[0008] Another object of the present disclosure is to provide a composition that contains a polymer having a large number of sulfonic acid groups or sulfonate groups and a fluoropolymer that contains a high content of polymerized units based on perfluoromonomers, and that is substantially free of dimers and trimers of the monomers that constitute the polymer.

[0009] Another object of the present disclosure is to provide a composition that contains a polymer having a sulfonic acid group or a sulfonate salt group and polytetrafluoroethylene having a high molecular weight, and that is substantially free of dimers and trimers of the monomers that constitute the polymer. [Means for solving the problem]

[0010] According to the present disclosure, there is provided a method for producing a fluoropolymer, in which a fluoropolymer is obtained by polymerizing a perfluoromonomer in an aqueous medium in the presence of a polymer (1), wherein the content of polymerization units based on the perfluoromonomer in the fluoropolymer is 90 mol % or more relative to all polymerization units of the fluoropolymer, the polymer (1) is a polymer of a monomer (1) represented by general formula (1), the content of polymerization units (1) based on the monomer (1) in the polymer (1) is 50 mass % or more relative to all polymerization units of the polymer (1), and the content of dimers and trimers of the monomer (1) in the polymer (1) is 1.0 mass % or less relative to the polymer (1). CF2=CF-OR-(Rf-SO3M) m (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR 7 4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R 7 is H or an organic group; and m is an integer of 1 or greater.

[0011] In the production method of the present disclosure, the monomer (1) is preferably a monomer (2) represented by general formula (2). CF2=CF-O-Rf-SO3M (2) (In the formula, Rf and M are as defined above.) In the manufacturing method of the present disclosure, the fluoropolymer is preferably polytetrafluoroethylene. In the production method of the present disclosure, the fluoropolymer is preferably a perfluoroelastomer.

[0012] The present disclosure also provides a method for producing polytetrafluoroethylene, in which polytetrafluoroethylene is obtained by polymerizing tetrafluoroethylene in an aqueous medium in the presence of polymer (1), wherein the polytetrafluoroethylene is high-molecular-weight polytetrafluoroethylene, polymer (1) is a polymer of monomer (1) represented by general formula (1), and the content of dimers and trimers of monomer (1) in polymer (1) is 1.0 mass% or less relative to polymer (1). CF2=CF-OR-(Rf-SO3M) m (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR 7 4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R 7 is H or an organic group; and m is an integer of 1 or greater.

[0013] In the production method of the present disclosure, the monomer (1) is preferably a monomer (2) represented by general formula (2). CF2=CF-O-Rf-SO3M (2) (In the formula, Rf and M are as defined above.)

[0014] The present disclosure also provides a composition containing a polymer (1) and a fluoropolymer, wherein the fluoropolymer contains polymerization units based on a perfluoromonomer, and the content of polymerization units based on the perfluoromonomer in the fluoropolymer is 90 mol % or more based on all polymerization units of the fluoropolymer, the polymer (1) is a polymer of a monomer (1) represented by general formula (1), and the content of polymerization units (1) based on the monomer (1) in the polymer (1) is 50 mass % or more based on all polymerization units of the polymer (1), and the content of dimers and trimers of the monomer (1) in the polymer (1) is 1.0 mass % or less based on the polymer (1). CF2=CF-OR-(Rf-SO3M) m (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR 7 4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R 7 is H or an organic group; and m is an integer of 1 or greater.

[0015] In the composition of the present disclosure, the monomer (1) is preferably a monomer (2) represented by general formula (2). CF2=CF-O-Rf-SO3M (2) (In the formula, Rf and M are as defined above.) In the composition of the present disclosure, the polymer (1) is a compound of the monomer (1) and the general formula CFR 11 =CR 11 2 (wherein, R 11 are preferably copolymers of monomers represented by the formula (I) and (II), each independently representing H, F or a perfluoroalkyl group having 1 to 4 carbon atoms. In the composition of the present disclosure, the content of polymerized units (1) based on the monomer (1) is 50 to 94 mass% based on all polymerized units constituting the polymer (1), and the polymer (1) is represented by the general formula CFR 11 =CR 11 2 (wherein, R 11 are independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms), the content of polymerized units (M) based on the monomer represented by the formula (I) is preferably 6 to 50 mass % based on the total polymerized units constituting the polymer (1). In the composition of the present disclosure, the alternation ratio of polymerized units (1) and polymerized units (M) is preferably 40% or more. In the composition of the present disclosure, the fluoropolymer is preferably polytetrafluoroethylene. In the composition of the present disclosure, the fluoropolymer is preferably a perfluoroelastomer. In the composition of the present disclosure, when the fluoropolymer is the polytetrafluoroethylene or the perfluoroelastomer, the metal content in the composition is preferably 10 ppm by mass or less.

[0016] The present disclosure also provides a composition containing polymer (1) and polytetrafluoroethylene, wherein the polytetrafluoroethylene is high-molecular-weight polytetrafluoroethylene, the polymer (1) is a polymer of monomer (1) represented by general formula (1), and the content of dimers and trimers of monomer (1) in polymer (1) is 1.0 mass% or less relative to polymer (1). CF2=CF-OR-(Rf-SO3M) m (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR 7 4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R 7 is H or an organic group; and m is an integer of 1 or greater.

[0017] In the composition of the present disclosure, the monomer (1) is preferably a monomer (2) represented by general formula (2). CF2=CF-O-Rf-SO3M (2) (In the formula, Rf and M are as defined above.) [Effects of the Invention]

[0018] According to the present disclosure, there can be provided a production method for producing a fluoropolymer using a polymer having a large number of sulfonic acid groups or sulfonate salt groups, which is capable of producing a fluoropolymer that is substantially free of dimers and trimers of the monomers that constitute the polymer and that contains a high content of polymerization units based on perfluoromonomers.

[0019] Another object of the present disclosure is to provide a method for producing polytetrafluoroethylene using a polymer having sulfonic acid groups or sulfonate salt groups, which method is capable of producing polytetrafluoroethylene that is substantially free of dimers and trimers, which are the monomers that constitute the polymer, and has a high molecular weight.

[0020] Furthermore, according to the present disclosure, it is possible to provide a composition that contains a polymer having a large number of sulfonic acid groups or sulfonate groups and a fluoropolymer that contains a high content of polymerized units based on a perfluoromonomer, and that is substantially free of dimers and trimers of the monomers that constitute the polymer.

[0021] Furthermore, according to the present disclosure, it is possible to provide a composition that contains a polymer having a sulfonic acid group or a sulfonate group and polytetrafluoroethylene having a high molecular weight, and that is substantially free of dimers and trimers of the monomers that constitute the polymer. DETAILED DESCRIPTION OF THE INVENTION

[0022] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0023] In the present disclosure, fluororesins are partially crystalline fluoropolymers, or fluoroplastics. Fluororesins have a melting point and are thermoplastic, but may be melt-processable or non-melt-processable.

[0024] In the present disclosure, melt-processable means that the polymer can be melted and processed using conventional processing equipment such as an extruder, an injection molding machine, etc. Therefore, melt-processable fluororesins usually have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0025] In this disclosure, fluoroelastomer refers to an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) appearing in differential scanning calorimetry (DSC) (heating rate 10°C / min) or differential thermal analysis (DTA) (heating rate 10°C / min) of the fluoropolymer is 4.5 J / g or less. Fluoroelastomers exhibit elastomeric properties through crosslinking. Elastomeric properties refer to the ability of a polymer to be stretched and to retain its original length when the force required to stretch the polymer is no longer applied.

[0026] In the present disclosure, the partially fluorinated rubber is a fluoropolymer that contains fluoromonomer units and has a perfluoromonomer unit content of less than 90 mol% relative to all polymerized units, and has a glass transition temperature of 20°C or lower and a melting peak (ΔH) magnitude of 4.5 J / g or lower.

[0027] In this disclosure, perfluororubber (perfluoroelastomer) is a fluoropolymer having a perfluoromonomer unit content of 90 mol% or more, preferably 91 mol% or more, relative to all polymerized units, a glass transition temperature of 20°C or less, a melting peak (ΔH) magnitude of 4.5 J / g or less, and a fluorine atom concentration of 71 mass% or more, preferably 71.5 mass% or more. In this disclosure, the fluorine atom concentration in the fluoropolymer is determined by calculation from the type and content of each monomer constituting the fluoropolymer.

[0028] In the present disclosure, a perfluoromonomer is a monomer that does not contain a carbon atom-hydrogen atom bond in the molecule. The perfluoromonomer may be a monomer containing carbon atoms and fluorine atoms, or a monomer in which some of the fluorine atoms bonded to the carbon atoms are substituted with chlorine atoms, or may contain nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, boron atoms, or silicon atoms in addition to carbon atoms. The perfluoromonomer is preferably a monomer in which all hydrogen atoms are substituted with fluorine atoms. The perfluoromonomer does not include monomers that provide crosslinking sites.

[0029] The monomer that provides a crosslinking site is a monomer (cure site monomer) having a crosslinkable group that provides a crosslinking site to the fluoropolymer for forming a crosslink with a curing agent.

[0030] In the present disclosure, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer having a content of tetrafluoroethylene units relative to all polymerized units of 99 mol % or more.

[0031] In the present disclosure, both the fluororesin (excluding polytetrafluoroethylene) and the fluororubber are preferably fluoropolymers having a tetrafluoroethylene content of less than 99 mol% relative to all polymerized units.

[0032] In the present disclosure, the content of each monomer constituting the fluoropolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0033] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, a heteroaryl group optionally having one or more substituents; cyano group, formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2-, and RaNRbSO2- (In these formulas, Ra independently represents: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents; Rb is independently H or an alkyl group which may have one or more substituents. Includes. The organic group is preferably an alkyl group which may have one or more substituents.

[0034] In the present disclosure, the term "substituent" refers to a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamido group, an aromatic sulfonamido group, a heterocyclic sulfonamido group, an amino group, and an aliphatic amino group. groups, aromatic amino groups, heterocyclic amino groups, aliphatic oxycarbonylamino groups, aromatic oxycarbonylamino groups, heterocyclic oxycarbonylamino groups, aliphatic sulfinyl groups, aromatic sulfinyl groups, aliphatic thio groups, aromatic thio groups, hydroxy groups, cyano groups, sulfo groups, carboxy groups, aliphatic oxyamino groups, aromatic oxyamino groups, carbamoylamino groups, sulfamoylamino groups, halogen atoms, sulfamoylcarbamoyl groups, carbamoylsulfamoyl groups, dialiphatic oxyphosphinyl groups, and diaromatic oxyphosphinyl groups.

[0035] The aliphatic group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic group include alkyl groups having a total of 1 to 8, preferably 1 to 4, carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, and a carbamoylmethyl group.

[0036] The aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in total, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0037] The heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the heterocyclic group include 5- or 6-membered heterocycles having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0038] The acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the acyl group include acyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

[0039] The acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include acylamino groups having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and alkylcarbonylamino groups having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0040] The aliphatic oxycarbonyl group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a (t)-butoxycarbonyl group.

[0041] The carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 9 carbon atoms, preferably an unsubstituted carbamoyl group, or an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, or an N-phenylcarbamoyl group.

[0042] The aliphatic sulfonyl group may be saturated or unsaturated and may have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as a methanesulfonyl group.

[0043] The aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms, such as a benzenesulfonyl group.

[0044] The amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.

[0045] The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably a total of 2 to 8 carbon atoms, and more preferably an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0046] The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, or a 2-pyridinesulfonamide group.

[0047] The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the sulfamoyl group include a sulfamoyl group, an alkylsulfamoyl group having 1 to 9 carbon atoms in total, a dialkylsulfamoyl group having 2 to 10 carbon atoms in total, an arylsulfamoyl group having 7 to 13 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 12 carbon atoms in total, more preferably a sulfamoyl group, an alkylsulfamoyl group having 1 to 7 carbon atoms in total, a dialkylsulfamoyl group having 3 to 6 carbon atoms in total, an arylsulfamoyl group having 6 to 11 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 10 carbon atoms in total, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[0048] The aliphatic oxy group may be saturated or unsaturated and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. Examples of the aliphatic oxy group include alkoxy groups having a total of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, and a methoxyethoxy group.

[0049] The aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group fused with the aryl group, an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0050] The aliphatic thio group may be saturated or unsaturated and includes alkylthio groups having a total of 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, and a t-butylthio group.

[0051] The carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having 2 to 9 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 10 carbon atoms in total, an arylcarbamoylamino group having 7 to 13 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 12 carbon atoms in total, preferably a carbamoylamino group, an alkylcarbamoylamino group having 2 to 7 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 6 carbon atoms in total, an arylcarbamoylamino group having 7 to 11 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 10 carbon atoms in total, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0052] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (eg, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0053] In this disclosure, the term "at least 1" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0054] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0055] The production method of the present disclosure is a fluoropolymer production method in which a perfluoromonomer is polymerized in an aqueous medium in the presence of polymer (1) to obtain a fluoropolymer (hereinafter, sometimes referred to as the first production method of the present disclosure).

[0056] <Polymer (1)> The polymer (1) used in the first production method of the present disclosure is a polymer of a monomer (1) represented by general formula (1), in which the polymerized units (1) based on the monomer (1) in the polymer (1) account for 50 mass% or more of the total polymerized units of the polymer (1), and the content of dimers and trimers of the monomer (1) in the polymer (1) is 1.0 mass% or less of the polymer (1).

[0057] The monomer (1) is represented by the following general formula (1). CF2=CF-OR-(Rf-SO3M) m (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR 7 4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R 7 is H or an organic group; and m is an integer of 1 or greater.

[0058] In the production method of the present disclosure, one or more types of monomers can be used as the monomer (1).

[0059] The polymer (1) may be a homopolymer of the monomer (1) or a copolymer with other monomers.

[0060] R is a single bond or a linking group. In the present disclosure, a "linking group" is an (m+1)-valent linking group, and when m is 1, it is a divalent linking group. The linking group preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less.

[0061] The linking group may be linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0062] m is an integer of 1 or more, preferably 1 or 2, and more preferably 1. When m is an integer of 2 or more, Rf and M may be the same or different.

[0063] Next, a preferred structure when m is 1 in general formula (1) will be described.

[0064] In general formula (1), when m is 1, R is preferably a single bond. That is, the monomer (1) is preferably a monomer (2) represented by the general formula (2). The polymer (1) is also preferably a polymer (2) containing polymerized units (2) based on a monomer (2) represented by general formula (2). CF2=CF-O-Rf-SO3M (2) (In the formula, Rf and M are as defined above.)

[0065] The above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. The above fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0066] The number of carbon atoms in the fluorine-containing alkylene group of Rf is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 5 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, -CF(CF3)CH2-, -CF2CF2CF2-, -CF2CF2CF2CF2-, and the like. The fluorine-containing alkylene group is preferably a perfluoroalkylene group, and more preferably an unbranched linear perfluoroalkylene group.

[0067] The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms in the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, and particularly preferably 5 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0068] Specific examples of the fluorine-containing alkylene group having an ether bond include -CF2CF(CF3)OCF2-, -CF2CF(CF3)OCF2CF2-, -CF2CF(CF3)OCF2CF2CF2-, -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0069] The carbon number of the fluorine-containing alkylene group having a keto group is preferably 3 or more. The carbon number of the fluorine-containing alkylene group having a keto group is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, and particularly preferably 5 or less.

[0070] Specific examples of the fluorine-containing alkylene group having a keto group include -CF2CF(CF3)CO-CF2-, -CF2CF(CF3)CO-CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2-, etc. The fluorine-containing alkylene group having a keto group is preferably a perfluoroalkylene group.

[0071] Water may be added to the keto group in the fluorine-containing alkylene group. Therefore, the monomer (1) may be a hydrate. Examples of the fluorine-containing alkylene group in which water is added to the keto group include -CFCF(CF)C(OH)-CF-, -CFCF(CF)C(OH)-CFCF-, -CFCF(CF)C(OH)-CFCFCF-, and -CFCF(CF)C(OH)-CFCFCFCF-.

[0072] M, which may be the same or different in each occurrence, is H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0073] R 7 As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula:

[0074] Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferred.

[0075] M may be the same or different in each occurrence and is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, and H, Na or NH4 is especially preferred.

[0076] The monomer represented by general formula (1) is preferably at least one selected from the group consisting of monomers represented by general formulas (1a), (1b), (1c), (1d) and (1e). CF2=CF-O-(CF2) n1 -SO3M (1a) (wherein n1 represents an integer of 1 to 10, and M is as defined above.) CF2=CF-O-(CF2C(CF3)F) n2 -SO3M (1b) (wherein n2 represents an integer of 1 to 5, and M is as defined above.) CF2=CF-O-(CFX 1 ) n3 -SO3M (1c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and M is as defined above. CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -SO3M (1d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and M and X 1 is the same as the definition above.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-SO3M (1e) (wherein n5 represents an integer of 0 to 10, M and X 1 is the same as the definition above.)

[0077] In general formula (1a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. M is preferably H, Na, K or NH4.

[0078] Examples of the monomer represented by general formula (1a) include CF2=CF(OCF2CF2SO3M), CF2=CF(OCF2SO3M), CF2=CF(OCF2CF2CF2SO3M), and CF2=CFO(CF2CF2CF2CF2)SO3M (wherein M is as defined above).

[0079] In general formula (1b), n2 is preferably an integer of 3 or less, from the viewpoint of dispersion stability of the resulting composition. The above M is preferably H, Na, K or NH4.

[0080] In the general formula (1c), n3 is preferably an integer of 5 or less from the viewpoint of water solubility, and the above M is preferably H, Na, K or NH4.

[0081] In general formula (1d), X 1 is preferably —CF3 from the viewpoint of dispersion stability of the composition, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, and M is preferably H, Na, K or NH4.

[0082] Examples of the monomer represented by general formula (1d) include CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, and CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M is as defined above).

[0083] In general formula (1e), n5 is preferably an integer of 5 or less from the viewpoint of water solubility, and M is preferably H, Na, K or NH4.

[0084] An example of the monomer represented by general formula (1e) is CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0085] The monomer (1) is preferably CF2=CF(OCF2CF2SO3M) (wherein M is as defined above).

[0086] Next, a preferred configuration when m in general formula (1) is an integer of 2 or more will be described.

[0087] When m is 2 in general formula (1), R is preferably a linking group containing at least one carbon atom. The monomer (1) is also preferably a monomer (3) represented by the general formula (3). The polymer (1) is also preferably a polymer (3) containing polymerized units (3) based on a monomer (3) represented by general formula (3). CF2=CF-OQ F1 -CF(-Rf-SO3M)2(3) (wherein Rf and M are as defined above, Q F is a single bond, a fluorine-containing alkylene group which may contain an ether bond between carbon atoms, or a fluorine-containing oxyalkylene group which may contain an ether bond between carbon atoms).

[0088] The monomer (3) represented by the general formula (3) is [ka] etc.

[0089] The polymer (1) may be a homopolymer consisting of only the polymerized unit (1), or may be a copolymer containing the polymerized unit (1) and a polymerized unit based on another monomer copolymerizable with the monomer (1) represented by the general formula (1). From the viewpoint of solubility in an aqueous medium, a homopolymer consisting of only the polymerized unit (1) is preferred. The polymerized units (1) may be the same or different in each occurrence, and the polymer (1) may contain polymerized units (1) based on two or more different monomers represented by the general formula (1).

[0090] Other monomers copolymerizable with the monomer (1) include monomers represented by the following general formula: General formula: CX2=CX-O-Rf-COOM (wherein X is independently F or CF3, and Rf and M are as defined in general formula (1)).

[0091] The other monomers also include those of the general formula CFR 11 =CR 11 2 (wherein, R 11are independently H, F, or a perfluoroalkyl group having 1 to 4 carbon atoms. As the other monomer, a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms is preferred. Examples of the other monomer include CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-isomer), CHF=CHCF3 (Z-isomer), etc.

[0092] Among the other monomers, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and vinylidene fluoride (CH2=CF2) is preferred in terms of good copolymerizability, at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride is more preferred, and vinylidene fluoride is even more preferred. Therefore, the polymerized units based on the other monomer are preferably at least one selected from the group consisting of polymerized units based on tetrafluoroethylene and polymerized units based on vinylidene fluoride, and polymerized units based on vinylidene fluoride are even more preferred. The polymerized units based on the other monomers may be the same or different in each occurrence, and the fluoropolymer may contain polymerized units based on two or more different other monomers.

[0093] When polymer (1) contains polymerized units (1) and polymerized units based on other monomers copolymerizable with monomer (1), the content of polymerized units (1) based on monomer (1) is preferably 50 to 94 mass%, more preferably 63 to 90 mass%, and even more preferably 67 to 87 mass%, based on all polymerized units constituting polymer (1), and the content of polymerized units based on other monomers is preferably 6 to 50 mass%, more preferably 10 to 37 mass%, and even more preferably 13 to 33 mass%, based on all polymerized units constituting polymer (1). Such a configuration is achieved when the polymerized units based on other monomers copolymerizable with monomer (1) are represented by the general formula CFR 11 =CR 11It is particularly suitable when the polymerized units (M) are based on a monomer represented by the formula CX2=CX-O-Rf-COOM. When the fluoropolymer contains polymerized units (1) and polymerized units (M), the total content of the polymerized units (1) and polymerized units (M) is preferably 80 to 100 mass%, more preferably 85 mass% or more, even more preferably 90 mass% or more, and particularly preferably 99 mass% or more, based on all polymerized units constituting the fluoropolymer. When the fluoropolymer contains polymerized units (1) and polymerized units (M1) based on a monomer represented by the formula CX2=CX-O-Rf-COOM, the total content of the polymerized units (1) and polymerized units (M1) is preferably 80 to 100 mass%, more preferably 85 mass% or more, even more preferably 90 mass% or more, and particularly preferably 99 mass% or more, based on all polymerized units constituting the fluoropolymer.

[0094] When polymer (1) contains polymerized units (1) and polymerized units based on other monomers copolymerizable with monomer (1), the alternation ratio of polymerized units (1) and polymerized units based on other monomers copolymerizable with monomer (1) is preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. The alternation ratio may be, for example, 40 to 99%. Such a configuration is achieved when the polymerized units based on other monomers copolymerizable with monomer (1) are represented by the general formula CFR 11 =CR 11 It is particularly preferred that the polymerized units (M) are based on the monomer represented by formula (2).

[0095] The alternating ratio of the polymerized unit (1) and the polymerized unit based on another monomer copolymerizable with the monomer (1) in the polymer (1) is 19 It can be determined by F-NMR analysis.

[0096] The other monomers also include those represented by the general formula (n1-2):

[0097] [ka]

[0098] (In the formula, X 1 , X 2 are the same or different H or F;X 3 is H, F, Cl, CH3 or CF3; X 4 , X 5 are the same or different and are H or F; a and c are the same or different and are 0 or 1. Rf 3 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0099] Specifically, CH2=CFCF2-O-Rf 3 , CF2=CF-O-Rf 3 , CF2=CFCF2-O-Rf 3 , CF2=CF-Rf 3 , CH2=CH-Rf 3 , CH2=CH-O-Rf 3 (In the formula, Rf 3 is the same as the above formula (n1-2)).

[0100] Examples of the other monomers include those of formula (n2-1):

[0101] [ka]

[0102] (In the formula, X 9 is H, F or CH3; Rf 4 Also included are fluorine-containing acrylate monomers represented by Rf (a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and an ether bond). 4 The base is

[0103] [ka]

[0104] (wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10).

[0105] Examples of the other monomers include those of formula (n2-2): CH2=CHO-Rf 5 (n2-2) (In the formula, Rf 5 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0106] Specific examples of the monomer of general formula (n2-2) include:

[0107] [ka]

[0108] (wherein e6 is an integer of 1 to 10) are preferred.

[0109] More specifically,

[0110] [ka]

[0111] Examples include:

[0112] Others include those of general formula (n2-3): CH2=CHCH2O-Rf 6 (n2-3) (In the formula, Rf 6 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond), a fluorine-containing allyl ether represented by the general formula (n2-4): CH2=CH-Rf 7 (n2-4) (In the formula, Rf 7is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond), and the like.

[0113] Specific examples of the monomers represented by general formulas (n2-3) and (n2-4) include:

[0114] [ka]

[0115] Examples of such monomers include:

[0116] In the polymer (1), the content of the polymerized units (1) relative to all polymerized units is, in order of preference, 50% by mass or more, more than 50% by mass, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 99% by mass or more. The content of the polymerized units (1) is particularly preferably substantially 100% by mass, and the polymer (1) is most preferably composed solely of the polymerized units (1).

[0117] In polymer (1), the content of polymerization units based on other monomers copolymerizable with the monomer represented by general formula (1) is, in order of preference, 50% by mass or less, less than 50% by mass, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, and 1% by mass or less, based on all polymerization units. It is particularly preferred that the content of polymerization units based on other monomers copolymerizable with the monomer represented by general formula (1) is substantially 0% by mass, and it is most preferred that polymer (1) does not contain polymerization units based on other monomers.

[0118] The lower limit of the number average molecular weight of the polymer (1) is, in order of preference, 0.3 × 10 4 That's 0.4 x 10 4 Above, 0.5 x 10 4 That's 0.7 x 10 4 That's 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 104 , 1.6×10 4 That's it, 1.8 x 10 4 That's it, 2.0 x 10 4 That's it, 3.0 x 10 4 The upper limit of the number average molecular weight of the polymer (1) is, in order of preference, 75.0 × 10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 Below, 20.0 x 10 4 The following is the result.

[0119] The lower limit of the weight average molecular weight of the polymer (1) is, in order of preference, 0.4×10 4 Above, 0.5 x 10 4 That's 0.6 x 10 4 That's 0.8 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 10 4 That's 1.7 x 10 4 That's it, 1.9 x 10 4 That's it, 2.1 x 10 4 That's it, 2.3 x 10 4 That's it, 2.7 x 10 4 That's it, 3.1 x 10 4 That's it, 3.5 x 10 4 That's it, 3.9 x 10 4 That's it, 4.3 x 10 4 That's it, 4.7 x 10 4 That's it, 5.1 x 10 4 That's it, 10.0 x 10 4 That's it, 15.0 x 10 4 That's it, 20.0 x 10 4 That's it, 25.0 x 10 4 The upper limit of the weight average molecular weight of the polymer (1) is, in order of preference, 150.0 × 10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 The following is the result.

[0120] The molecular weight distribution (Mw / Mn) of the polymer (1) is preferably 3.0 or less, 2.7 or less, 2.4 or less, 2.2 or less, 2.0 or less, 1.9 or less, 1.7 or less, 1.5 or less, 1.4 or less, and 1.3 or less.

[0121] The number average molecular weight and weight average molecular weight are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards. When GPC measurement is not possible, the number average molecular weight of polymer (1) can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0122] The polymer (1) typically has terminal groups. The terminal groups are generated during polymerization, and typical terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used to form the polymer (1) or during the chain transfer reaction.

[0123] Preferably, polymer (1) has an ion exchange ratio (IXR) of 53 or less, where IXR is defined as the number of carbon atoms in the polymer backbone relative to the ionizable group. Precursor groups that become ionic upon hydrolysis (e.g., -SOF) are not considered ionic groups for purposes of determining IXR.

[0124] IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and particularly preferably 8 or more. IXR is more preferably 43 or less, more preferably 33 or less, and particularly preferably 23 or less.

[0125] The ion exchange capacity of polymer (1) is, in order of preference, 0.80 meq / g or more, 1.50 meq / g or more, 1.75 meq / g or more, 2.00 meq / g or more, 2.20 meq / g or more, more than 2.20 meq / g, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, 3.20 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in polymer (1) and is calculated from the composition of polymer (1).

[0126] In polymer (1), the ionic (anionic) groups are typically distributed along the polymer backbone. Polymer (1) comprises a polymer backbone with recurring side chains attached to the backbone, and the side chains preferably carry ionic groups.

[0127] The polymer (1) is preferably water-soluble. Water-soluble means the property of being easily dissolved or dispersed in an aqueous medium. The particle size of a water-soluble polymer cannot be measured by dynamic light scattering (DLS), for example, or the particle size is 10 nm or less.

[0128] It is preferable that polymer (1) has sufficient water solubility. Generally, the higher the content of polymer (1) in an aqueous solution, the more difficult it becomes for polymer (1) to be sufficiently dissolved or dispersed in an aqueous medium. Therefore, polymer (1) whose particle size cannot be measured by dynamic light scattering (DLS) even when the content of polymer (1) in the aqueous solution is high can be said to have high water solubility. It is preferable that the particle size of polymer (1) cannot be measured even when it is contained in an aqueous solution at a content of 1.0% by mass. It is more preferable that the particle size cannot be measured even when polymer (1) is contained in an aqueous solution at a content of 1.5% by mass, and even more preferably at a content of 2.0% by mass.

[0129] The viscosity of an aqueous solution of polymer (1) is preferably 5.0 mPa s or more, more preferably 8.0 mPa s or more, even more preferably 10.0 mPa s or more, particularly preferably 12.0 mPa s or more, and most preferably 14.0 mPa s or more, and is preferably 100.0 mPa s or less, more preferably 50.0 mPa s or less, even more preferably 25.0 mPa s or less, and especially preferably 20.0 mPa s or less.

[0130] The viscosity of an aqueous solution of polymer (1) can be determined by adjusting the content of polymer (1) in the aqueous solution to 33 mass % based on the amount of the aqueous solution, and measuring the viscosity of the resulting aqueous solution at 20°C using a tuning fork vibro viscometer (model number: SV-10) manufactured by A&D Corporation.

[0131] The critical micelle concentration (CMC) of polymer (1) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less.

[0132] The critical micelle concentration of polymer (1) can be determined by measuring the surface tension, for example, using a surface tensiometer CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd.

[0133] The acid value of polymer (1) is preferably 60 or more, more preferably 90 or more, even more preferably 120 or more, particularly preferably 150 or more, and most preferably 180 or more. The upper limit is not particularly limited, but is preferably 300 or less.

[0134] The acid value of the polymer (1) is determined by the following formula: The polymer (1) contains -SO3M other than -SO3H, i.e., -SO3M (M is a metal atom, -NR 74, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. If -SO3M has -SO3H, it can be measured by converting -SO3M to -SO3H and then performing acid-base titration of -SO3H.

[0135] The polymer (1) can be produced by a production method for producing the polymer (1) by polymerizing the polymer (1).

[0136] The oxygen concentration in the polymerization reaction system is preferably 1500 ppm by volume or less, more preferably 500 ppm by volume or less, even more preferably 100 ppm by volume or less, and particularly preferably 50 ppm by volume or less, since this facilitates the production of a polymer (1) having a higher molecular weight. The oxygen concentration in the reaction system is usually 0.01 ppm by volume or more. In the above-mentioned production method, it is preferred that the oxygen concentration in the reaction system be maintained within the above-mentioned range throughout the entire polymerization period of the polymer (1).

[0137] The oxygen concentration in the polymerization reaction system can be controlled, for example, by flowing an inert gas such as nitrogen or argon, or, when a gaseous monomer is used, the gaseous monomer, through the liquid or gas phase in the reactor. The oxygen concentration in the polymerization reaction system can be determined by measuring and analyzing the gas coming out of the exhaust gas line of the polymerization system with a low-concentration oxygen analyzer.

[0138] The polymerization temperature of polymer (1) is preferably 70°C or lower, more preferably 65°C or lower, even more preferably 60°C or lower, even more preferably 55°C or lower, especially preferably 50°C or lower, particularly preferably 45°C or lower, most preferably 40°C or lower, preferably 10°C or higher, more preferably 15°C or higher, and even more preferably 20°C or higher, since polymer (1) having a higher molecular weight can be easily produced.

[0139] In the above production method, the polymer (1) may be copolymerized with the other monomers mentioned above.

[0140] In the above production method, the polymerization may be carried out in the presence of a pH adjuster, which may be added before or after the initiation of polymerization.

[0141] Examples of pH adjusters that can be used include ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, and ammonium gluconate. The pH can be measured using a pH meter manufactured by Orion.

[0142] The polymerization pressure is usually from atmospheric pressure to 10 MPaG and is appropriately determined depending on the type of monomer used, the molecular weight of the target polymer (1), and the reaction rate.

[0143] The polymerization time is usually 1 to 200 hours, and may be 5 to 100 hours.

[0144] In the above-mentioned production method, the polymerization of the monomer (1) may be carried out in an aqueous medium or in the absence of an aqueous medium. Alternatively, the polymerization of the monomer (1) may be carried out in the absence of an aqueous medium but in the presence of a non-aqueous medium (e.g., an organic solvent such as toluene) in an amount of less than 10 mass% based on the amount of the monomers containing the monomer (1). The polymerization of the monomer (1) may be emulsion polymerization, suspension polymerization, or bulk polymerization.

[0145] The aqueous medium is a reaction medium for polymerization and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower. Water is preferred as the aqueous medium.

[0146] In the above production method, the polymerization of polymer (1) can be carried out in the presence of a polymerization initiator. The polymerization initiator is not particularly limited as long as it can generate radicals within the above polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, the polymerization can also be initiated as a redox reaction by combining it with a reducing agent or the like. The concentration of the polymerization initiator is determined appropriately depending on the type of monomer, the molecular weight of the target polymer (1), and the reaction rate. When the polymerization of monomer (1) is carried out in an aqueous medium, it is preferable to use a water-soluble polymerization initiator such as a persulfate. When the polymerization of monomer (1) is carried out in the absence of an aqueous medium, it is preferable to use an oil-soluble polymerization initiator such as a peroxide.

[0147] As the polymerization initiator, persulfates (e.g., ammonium persulfate), or organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0148] As the polymerization initiator, persulfates are particularly preferred because they can easily produce a polymer (1) with a higher molecular weight. Examples of persulfates include ammonium persulfate, potassium persulfate, and sodium persulfate, with ammonium persulfate being preferred.

[0149] As the polymerization initiator, an oil-soluble radical polymerization initiator may be used. The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. Also usable are di(ω-hydro-dodecafluorohexanoyl) peroxide, di(ω-hydro-tetradecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluorovaleryl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as di(ω-hexafluorobutyryl)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0150] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously at the beginning of polymerization in an amount (for example, several ppm relative to the water concentration) that does not significantly decrease the polymerization rate. The upper limit is a range in which the reaction temperature can be increased while removing heat from the equipment using the heat of polymerization reaction, and a more preferred upper limit is a range in which the heat of polymerization reaction can be removed from the equipment.

[0151] In the above production method, the polymerization initiator can be added not only at the start of polymerization but also during polymerization. The ratio of the amount of polymerization initiator added at the start of polymerization to the amount of polymerization initiator added during polymerization is preferably 95 / 5 to 5 / 95, more preferably 60 / 40 to 10 / 90, and even more preferably 30 / 70 to 15 / 85. The method of adding the polymerization initiator during polymerization is not particularly limited, and the entire amount may be added at once, or may be added in two or more divided portions, or may be added continuously.

[0152] In the above production method, since a polymer (1) having a higher molecular weight can be easily produced, the total amount of polymerization initiators used in the polymerization is preferably 0.00001 to 10% by mass relative to the aqueous medium. The total amount of polymerization initiators used in the polymerization is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, and preferably 5% by mass or less, more preferably 2% by mass or less.

[0153] In the above production method, since a polymer (1) having a higher molecular weight can be easily produced, the total amount of polymerization initiator used in the polymerization is preferably 0.001 to 10 mol% based on the total amount of monomers used in the polymerization. The total amount of polymerization initiator used in the polymerization is more preferably 0.005 mol% or more, even more preferably 0.01 mol% or more, especially preferably 0.1 mol% or more, most preferably 0.5 mol% or more, more preferably 10 mol% or less, even more preferably 5.0 mol% or less, especially more preferably 2.5 mol% or less, particularly most preferably 2.2 mol% or less, and preferably 2.0 mol% or less.

[0154] In the above production method, since a polymer (1) having a higher molecular weight can be easily produced, the amount of the monomer containing polymer (1) present at the start of polymerization is preferably 20% by mass or more relative to the amount of the aqueous medium present. The amount of the monomer present is more preferably 30% by mass or more, and even more preferably 40% by mass or more. There are no particular restrictions on the upper limit of the amount of the monomer present, but from the viewpoint of smoothly progressing the polymerization, it may be 200% by mass or less. The amount of the monomer present at the start of polymerization refers to the total amount of polymer (1) and, if present, other monomers present in the reactor at the start of polymerization.

[0155] When the polymerization of monomer (1) is carried out in the absence of an aqueous medium, the total amount of polymerization initiators such as peroxides added is preferably 0.001 to 10 mol% based on the total amount of monomers (monomer mixture) containing monomer (1). The total amount of polymerization initiators used in the polymerization is more preferably 0.005 mol% or more, even more preferably 0.01 mol% or more, more preferably 10 mol% or less, even more preferably 5.0 mol% or less, particularly preferably 2.5 mol% or less, particularly most preferably 2.2 mol% or less, and preferably 2.0 mol% or less.

[0156] Polymerization of polymer (1) can be carried out by charging polymer (1) and, if necessary, an aqueous medium, other monomers, and, if necessary, other additives into a reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to initiate the polymerization reaction. After the start of the polymerization reaction, monomers, polymerization initiators, and other additives may be added depending on the purpose.

[0157] The polymer (1) used in the production method of the present disclosure is substantially free of dimers and trimers of the monomer (1). The dimers and trimers of the monomer (1) are usually generated when the monomer (1) is polymerized to obtain the polymer (1). The content of the dimers and trimers in the polymer (1) is 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, based on the polymer (1).

[0158] The polymer (1) used in the production method of the present disclosure may be substantially free of dimers and trimers composed of polymerization units (1) derived from the monomer (1) and polymerization units derived from other monomers copolymerizable with the monomer (1). Dimers and trimers composed of polymerization units (1) and polymerization units derived from other monomers are typically generated when the polymer (1) is obtained by polymerizing the monomer (1) and other monomers copolymerizable with the monomer (1). The content of dimers and trimers composed of polymerization units (1) and polymerization units derived from other monomers in the polymer (1) is 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, based on the polymer (1).

[0159] The contents of dimers and trimers in polymer (1) can be determined by subjecting polymer (1) to gel permeation chromatography (GPC) analysis and calculating the ratio (area percentage) of the total peak area of ​​the dimers and trimers to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0160] Furthermore, when the content of dimers and trimers in polymer (1) is less than 0.5% by mass relative to polymer (1), it can be identified by measurement using liquid chromatography-mass spectrometry (LC / MS). Specifically, aqueous solutions containing five or more levels of monomer (1) are prepared, and LC / MS analysis is performed for each content. The relationship between the content and the area (peak integral value) for each content is plotted to create a calibration curve for monomer (1). Furthermore, calibration curves for the dimer and trimer of monomer (1) are created from the calibration curve for monomer (1). Methanol is added to the polymer (1) to prepare a mixture, which is then filtered using an ultrafiltration disk (molecular weight cutoff: 3000 Da), and the resulting recovered liquid is subjected to LC / MS analysis. Then, using the calibration curve, the area (integrated value of the peak) of the chromatogram of the dimer and trimer of the monomer (1) can be converted into the content of the dimer and trimer.

[0161] The content of the fraction having a molecular weight of 3000 or less in polymer (1) may be 3.7% or less, preferably 3.2% or less, more preferably 2.7% or less, even more preferably 1.7% or less, especially preferably 1.2% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less, based on the content of polymer (1). The lower limit of the content of the fraction having a molecular weight of 3000 or less is not limited, but is, for example, 0.01%. The content of the fraction having a molecular weight of 3000 or less can be calculated from the peak area of ​​GPC. The fraction having a molecular weight of 3000 or less includes all compounds having a molecular weight of 3000 or less.

[0162] The content of the fraction having a molecular weight of 2000 or less in polymer (1) may be 3.2% or less, preferably 2.7% or less, more preferably 2.2% or less, even more preferably 1.7% or less, especially preferably 1.2% or less, and particularly preferably 0.6% or less, based on the content of polymer (1). The lower limit of the content of the fraction having a molecular weight of 2000 or less is not limited, but is, for example, 0.01%. The content of the fraction having a molecular weight of 2000 or less can be calculated from the peak area of ​​GPC. The fraction having a molecular weight of 2000 or less includes all compounds having a molecular weight of 2000 or less.

[0163] The content of the fraction having a molecular weight of 1500 or less in polymer (1) may be 2.7% or less, preferably 2.2% or less, more preferably 1.7% or less, even more preferably 1.2% or less, and especially preferably 0.6% or less, based on the content of polymer (1). The lower limit of the content of the fraction having a molecular weight of 1500 or less is not limited, but is, for example, 0.01%. The content of the fraction having a molecular weight of 1500 or less can be calculated from the peak area of ​​GPC. The fraction having a molecular weight of 1500 or less includes all compounds having a molecular weight of 1500 or less.

[0164] The content of the fraction having a molecular weight of 1000 or less in polymer (1) may be 2.2% or less, preferably 1.7% or less, more preferably 1.2% or less, and even more preferably 0.6% or less, based on the content of polymer (1). The lower limit of the content of the fraction having a molecular weight of 1000 or less is not limited, but is, for example, 0.01%. The content of the fraction having a molecular weight of 1000 or less can be calculated from the peak area of ​​GPC. The fraction having a molecular weight of 1000 or less includes all compounds having a molecular weight of 1000 or less.

[0165] By using a polymer (1) that is substantially free of dimers and trimers of the monomer (1) during polymerization of a perfluoromonomer in an aqueous medium, a fluoropolymer that is substantially free of dimers and trimers of the monomer (1) can be produced.

[0166] Polymer (1) is a polymer containing polymerized units (1) based on monomer (1). Polymer (1) used in the present disclosure is a polymer from which dimers (polymers containing two polymerized units (1)) and trimers (polymers containing three polymerized units (1)) have been substantially removed from polymer (1) containing two or more polymerized units (1).

[0167] When polymerizing a perfluoromonomer in an aqueous medium, by using a polymer (1) that is substantially free of dimers and trimers composed of polymerization units (1) based on monomer (1) and polymerization units based on other monomers copolymerizable with monomer (1), even when a polymer (1) containing polymerization units (1) and polymerization units based on other monomers is used as polymer (1), a fluoropolymer that is substantially free of dimers and trimers composed of polymerization units (1) and polymerization units based on other monomers can be produced.

[0168] The molecular weight of the monomer (1) is preferably 500 or less, more preferably 400 or less. That is, the polymer (1) preferably does not substantially contain dimers and trimers having a molecular weight of 1,500 or less, more preferably does not substantially contain dimers and trimers having a molecular weight of 1,200 or less.

[0169] Therefore, the production method of the present disclosure preferably includes a step of polymerizing a monomer (1) represented by general formula (1) to obtain a crude composition containing a polymer of the monomer (1), and a step of removing the dimer and trimer of the monomer (1) contained in the crude composition from the crude composition to obtain a polymer (1) having a content of the dimer and trimer of the monomer (1) of 1.0 mass% or less, based on the polymer (1).

[0170] The polymerization of the monomer (1) can be carried out by the method described above. By producing a crude composition by such a method, a crude composition in which the polymer (1) is dispersed or dissolved in an aqueous medium can be obtained.

[0171] The polymerization of the monomer (1) is preferably carried out in an aqueous medium substantially in the absence of a fluorine-containing surfactant (excluding the monomer (1) represented by the general formula (1)).

[0172] In the present disclosure, "substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant relative to the aqueous medium is 10 ppm by mass or less. The amount of the fluorine-containing surfactant relative to the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and still more preferably 1 ppb by mass or less.

[0173] The fluorine-containing surfactant will be described later in the explanation regarding the polymerization of perfluoromonomers.

[0174] The crude composition thus obtained typically contains more than 1.0 mass% of dimers and trimers of monomer (1) in total, relative to the mass of the polymer. The content of dimers and trimers of monomer (1) in the polymer may be, for example, 2.0 mass% or more, 3.0 mass% or more, 30.0 mass% or less, or 20.0 mass% or less, relative to the mass of the polymer of monomer (1).

[0175] Furthermore, when polymerizing monomer (1) with another monomer copolymerizable with monomer (1), the resulting crude composition typically contains dimers and trimers composed of polymerization units (1) based on monomer (1) and polymerization units based on the other monomer copolymerizable with monomer (1), in a total amount of more than 1.0 mass% based on the mass of the polymer. The content of dimers and trimers composed of polymerization units (1) and polymerization units based on the other monomer may be, for example, 2.0 mass% or more, 3.0 mass% or more, 30.0 mass% or less, or 20.0 mass% or less, based on the mass of the polymer.

[0176] The contents of dimers and trimers in the crude composition can be determined by subjecting the crude composition to gel permeation chromatography (GPC) analysis and calculating the ratio (area percentage) of the total peak area of ​​the dimers and trimers to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0177] Next, dimers and trimers of monomer (1) contained in the crude composition obtained by polymerization of monomer (1), or dimers and trimers composed of polymerized units (1) and polymerized units based on other monomers, are removed from the crude composition. The means for removing dimers and trimers is not particularly limited, but at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid-liquid separation, and reprecipitation is preferred, at least one means selected from the group consisting of ultrafiltration, microfiltration, liquid-liquid separation, and reprecipitation is more preferred, at least one means selected from the group consisting of ultrafiltration and liquid-liquid separation is even more preferred, and ultrafiltration is particularly preferred.

[0178] By appropriately selecting the means for removing dimers and trimers, it is also possible to remove fractions with molecular weights of 3,000 or less, fractions with molecular weights of 2,000 or less, fractions with molecular weights of 1,500 or less, and fractions with molecular weights of 1,000 or less.

[0179] It was not previously known that dimers and trimers of monomer (1) are produced by polymerization of monomer (1), and as a result, the dimers and trimers of monomer (1) are contained in polymer (1). The mechanism by which dimers and trimers of monomer (1) are produced is not entirely clear, but it is speculated that dimerization and trimerization of monomer (1) occur with considerable frequency due to the polymerization reaction in a polymerization system in which monomer (1) accounts for the majority of the monomers present in the polymerization system.

[0180] When removing the dimer and trimer, unreacted monomer (1) is usually also removed from the crude composition. Even if unreacted monomer (1) is incorporated into PTFE during polymerization, it does not necessarily adversely affect the functionality of PTFE, so it is not necessary to remove the unreacted monomer (1). However, by removing the unreacted monomer (1) simultaneously with the dimer and trimer, the amount of monomer to be used in the polymerization can be calculated without considering the presence of unreacted monomer (1), which has the advantage of facilitating the production of a fluoropolymer with the desired monomer composition. Even when monomer (1) remains in the polymer (1) or when monomer (1) is newly added as a comonomer, the dimerization and trimerization of monomer (1) hardly progresses during the polymerization reaction in a polymerization system in which TFE accounts for the majority of the monomers present in the polymerization system, and therefore almost no dimer or trimer of monomer (1) remains in the resulting fluoropolymer.

[0181] The crude composition obtained by polymerization of the monomer (1) may be a composition obtained by polymerization as is, or may be a composition obtained by diluting or concentrating the composition obtained by polymerization, or may be a composition that has been subjected to a dispersion stabilization treatment, etc. In order to facilitate ultrafiltration, microfiltration, or dialysis membrane treatment, it is also preferable to adjust the viscosity of the crude composition by these treatments.

[0182] The content of the polymer of monomer (1) in the crude composition is not particularly limited and may be, for example, 0.1 to 20% by mass. From the viewpoint of the efficiency of removing dimers and trimers, the content of the polymer of monomer (1) in the crude composition is preferably 18.0% by mass or less, more preferably 15.0% by mass or less, even more preferably 12.0% by mass or less, particularly preferably 10.0% by mass or less, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, particularly preferably 1.5% by mass or more, and most preferably 2.0% by mass or more. The content of the polymer of monomer (1) in the crude composition can be adjusted, for example, by adding water to the crude composition obtained by polymerization of monomer (1) or by concentrating the crude composition obtained by polymerization of monomer (1).

[0183] The pH of the crude composition is preferably -7.0 to 11.0, more preferably -6.0 to 8.0, and even more preferably -5.0 to 7.0. The pH of the crude composition can be adjusted by adding a pH adjuster to the crude composition obtained by polymerization of the monomer (1). The pH adjuster may be an acid or an alkali, and examples thereof include phosphates, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0184] When ultrafiltration, microfiltration, or dialysis membrane treatment is performed, the viscosity of the crude composition is preferably 25 mPa s or less, since this allows these treatments to proceed smoothly. The viscosity of the crude composition can be adjusted, for example, by adjusting the number average molecular weight of the polymer of monomer (1), by adjusting the concentration of the polymer of monomer (1) in the crude composition, or by adjusting the temperature of the crude composition.

[0185] The ultrafiltration or microfiltration may be performed by either a cross-flow method or a dead-end method, but is not limited thereto. From the viewpoint of reducing clogging of the membrane, the cross-flow method is preferred.

[0186] The ultrafiltration can be carried out using an ultrafiltration membrane, for example, an ultrafiltration device having an ultrafiltration membrane, and methods such as centrifugal ultrafiltration, batch ultrafiltration, and circulating ultrafiltration can be used.

[0187] The molecular weight cutoff of the ultrafiltration membrane is usually 0.1 × 10 4 ~30×10 4 The above ultrafiltration membrane can suppress clogging of the membrane and efficiently reduce dimers and trimers, so the molecular weight cutoff is about 0.3 × 10 4 The molecular weight cutoff is preferably 0.5×10 Da or more. 4 Da or more is more preferable, 0.6 × 10 4 Da or more is particularly preferable, and 0.8 × 10 4 The molecular weight cutoff is most preferably 1.0 × 10 Da or more. 4 From the viewpoint of the efficiency of removing dimers and trimers, the molecular weight cutoff may be 20×10 Da or more. 4 Da or less is preferable, 10 × 10 4 Da or less is more preferable.

[0188] The molecular weight cutoff of the ultrafiltration membrane can be determined by, for example, passing polystyrene with a known weight-average molecular weight through the membrane and determining the molecular weight at which 90% of the polystyrene is rejected. Quantitative determination of polystyrene can be performed using gel permeation chromatography.

[0189] The shape of the ultrafiltration membrane may be any of the conventionally known types, including, but not limited to, hollow fiber, flat membrane, spiral, tubular, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and preferably 0.05 to 2 m.

[0190] The material of the ultrafiltration membrane is not particularly limited, but examples thereof include organic materials such as cellulose, cellulose ester, polysulfone, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, chlorinated polyethylene, polypropylene, polyolefin, polyvinyl alcohol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, and polytetrafluoroethylene; metals such as stainless steel; and inorganic materials such as ceramics. The material of the ultrafiltration membrane is preferably an organic material, more preferably chlorinated polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylnitrile, polysulfone, or polyethersulfone, and even more preferably polyacrylnitrile, polysulfone, or polyvinylidene fluoride.

[0191] Specific examples of the ultrafiltration membrane include DESAL's G-5 type, G-10 type, G-20 type, G-50 type, PW type, and HWS UF type; KOCH's HFM-180, HFM-183, HFM-251, HFM-300, HFM-116, HFM-183, HFM-300, HFK-131, HFK-328, MPT-U20, MPS-U20P, and MPS-U20S; Synder's SPE1, SPE3, SPE5, SPE10, SPE30, SPV5, SPV50, and SOW30; Asahi Kasei's Microza (registered trademark) UF series; and Nitto Denko's NTR7410.

[0192] From the viewpoint of dimer and trimer removal efficiency, the ultrafiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0193] From the viewpoint of the efficiency of removing dimers and trimers, the ultrafiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0194] The microfiltration can be carried out using a microfiltration membrane, which typically has an average pore size of 0.05 to 1.0 μm. The microfiltration membrane preferably has an average pore diameter of 0.1 μm or more, more preferably 0.075 μm or more, and even more preferably 0.1 μm or more, to efficiently remove dimers and trimers. The average pore diameter is preferably 1.00 μm or less, more preferably 0.50 μm or less, and even more preferably 0.25 μm or less. The average pore size of the microfiltration membrane can be measured in accordance with ASTM F 316-03 (bubble point method).

[0195] The shape of the microfiltration membrane is not limited to any particular shape, and examples thereof include hollow fiber, flat membrane, spiral, tubular, etc. From the viewpoint of preventing clogging, hollow fiber membranes are preferred. The inner diameter of the hollow fiber microfiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and preferably 0.8 to 1.4 mm. The length of the hollow fiber microfiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and preferably 0.05 to 2 m.

[0196] Examples of materials for the microfiltration membrane include cellulose-based materials, aromatic polyamides, polyvinyl alcohol, polysulfone, polyethersulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, metals, etc. Among these, aromatic polyamides, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, and polytetrafluoroethylene are preferred, and polyacrylonitrile or polyvinylidene fluoride is particularly preferred.

[0197] Specific examples of microfiltration membranes include Cefilt manufactured by NGK Insulators, Ltd.; Microza U series and Microza P series manufactured by Asahi Kasei Corporation; Poreflon SPMW, Poreflon OPMW, and Poreflon PM manufactured by Sumitomo Electric Industries, Ltd.; Trefil manufactured by Toray Industries, Inc.; NADIR MP005 and NADIR MV020 manufactured by Microdyne-Nadia; and X-flow manufactured by Norit.

[0198] From the viewpoint of dimer and trimer removal efficiency, the microfiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0199] From the viewpoint of the efficiency of removing dimers and trimers, the microfiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0200] The dialysis membrane treatment is carried out using a dialysis membrane. 4 ~100×10 4 It has a molecular weight cutoff of 100 Da. The above dialysis membrane can suppress clogging of the membrane and efficiently remove dimers and trimers, resulting in a molecular weight cutoff of 0.3 × 10 4 The molecular weight cutoff is preferably 0.5×10 Da or more. 4 Da or more is more preferable, 1.0 × 10 4 Da or more is more preferable, and 1.5 × 10 4 Da or more is even more preferable, and 2.0 × 10 4 Da or more is particularly preferred, and 3.0 × 10 4 Da or more is particularly preferable, and 5.0 × 10 4 The molecular weight cutoff is most preferably 8.0 × 10 Da or more. 4 It may be more than Da. In addition, the above molecular weight cutoff is set to 20×10 from the viewpoint of the efficiency of removing dimers and trimers. 4 Da or less is preferable, 10 × 10 4 Da or less is more preferable. The molecular weight cutoff of the dialysis membrane can be measured, for example, by the same method as that for the ultrafiltration membrane.

[0201] The material of the dialysis membrane is not particularly limited, but examples thereof include cellulose, polyacrylonitrile, polymethyl methacrylate, ethylene vinyl alcohol copolymer, polysulfone, polyamide, and polyester polymer alloy.

[0202] Specific examples of dialysis membranes include Spectra / Por (registered trademark) Float-A-Lyzer, Tube-A-Lyzer, Dialysis tubing, 6Dialysis tubing, and 7Dialysis tubing manufactured by Spectrum Laboratories.

[0203] The ultrafiltration, microfiltration, or dialysis membrane treatment is preferably carried out at a temperature of 10°C or higher, more preferably 15°C or higher, even more preferably 20°C or higher, and particularly preferably 30°C or higher. By setting the temperature within the above range, dimers and trimers can be reduced more efficiently. The temperature is preferably 90°C or lower, more preferably 80°C or lower, even more preferably 70°C or lower, and particularly preferably 60°C or lower.

[0204] The ultrafiltration, microfiltration, or dialysis membrane treatment can be carried out while adding water to the crude composition or while adjusting the pH of the crude composition. Water may be added to the crude composition intermittently or continuously.

[0205] The endpoint of the ultrafiltration, microfiltration, or dialysis membrane treatment may be appropriately determined and is not limited. In addition, the ultrafiltration, microfiltration, or dialysis membrane treatment may be backwashed with water approximately once every 1 to 24 hours of filtration time to improve the durability of the filtration membrane.

[0206] The separation can be carried out, for example, by adding an organic solvent to the composition, separating it into two phases, an aqueous phase and an organic solvent phase, and recovering the aqueous phase.

[0207] The reprecipitation can be carried out, for example, by adding the composition dropwise to a poor solvent to precipitate a polymer, recovering the precipitated polymer, dissolving the recovered polymer in a good solvent, adding the obtained solution dropwise to a poor solvent to precipitate the polymer again, and recovering the precipitated polymer.

[0208] By removing the dimers and trimers of monomer (1) from a crude composition containing a polymer of monomer (1), an aqueous solution containing polymer (1) substantially free of dimers and trimers is typically obtained. The polymer (1) used in the production method of the present disclosure may be the polymer (1) contained in the resulting aqueous solution, or may be the polymer (1) obtained by separating it from the aqueous solution. The method for separating polymer (1) from the aqueous solution is not particularly limited. For example, polymer (1) can be separated by methods such as coagulation, washing, and drying of polymer (1) in the aqueous solution.

[0209] An aqueous solution containing polymer (1) can be used as polymer (1). The preferred content of dimers and trimers of monomer (1) relative to polymer (1) in the aqueous solution, or the preferred content of dimers and trimers composed of polymer units (1) and polymer units based on other monomers, is as described above.

[0210] <Polymerization of perfluoromonomers> In the first production method of the present disclosure, a fluoropolymer is obtained by polymerizing a perfluoromonomer in an aqueous medium in the presence of polymer (1). The content of polymerized units based on the perfluoromonomer in the obtained fluoropolymer is 90 mol % or more based on the total polymerized units of the fluoropolymer.

[0211] The perfluoromonomer preferably has at least one double bond and is preferably at least one selected from the group consisting of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether), and perfluoro(alkyl allyl ether).

[0212] Examples of perfluoro(alkyl vinyl ether) include: General formula (110): CF2=CF-ORf 111 (In the formula, Rf 111represents a perfluoroorganic group; General formula (130): CF2=CFOCF2ORf 131 (In the formula, Rf 131 is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms, General formula (140): CF2=CFO(CF2CF(Y 141 )O) m (CF2) n F (In the formula, Y 141 represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4. General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A 151 (In the formula, Y 151 represents a fluorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain an etheric oxygen and a -SO2F group. n represents an integer of 0 to 3. n Y 151 may be the same or different. 152 represents a fluorine atom or a -SO2F group, and m represents an integer of 1 to 5. 152 may be the same or different. 151 -SO2X 151 , -COZ 151 or -POZ 152 Z 153 represents X 151 are F, Cl, Br, I, -OR 151 or -NR 152 R 153 represents Z. 151 , Z 152 and Z 153 are the same or different and are -NR 154 R 155-OR 156 Represents R 151 , R 152 , R 153 , R 154 , R 155 and R 156 are the same or different and represent H, ammonium, an alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group. It is preferable that the material is at least one selected from the group consisting of:

[0213] In the present disclosure, the term "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen atom.

[0214] The fluoromonomer represented by the general formula (110) is Rf 111 is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0215] Examples of the perfluoroorganic group in the general formula (110) include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. The fluoromonomer represented by the general formula (110) further includes a fluoromonomer represented by the general formula (110) in which Rf 111 is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf 111 is the following formula:

[0216] [ka]

[0217] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0218] CF3CF2CF2-(O-CF(CF3)-CF2) n - (wherein n represents an integer of 1 to 4).

[0219] Among the fluoromonomers represented by the general formula (110), General formula (160): CF2=CF-ORf 161 (In the formula, Rf 161 Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. Fluoromonomers represented by 161 is preferably a perfluoroalkyl group having 1 to 5 carbon atoms.

[0220] The perfluoro(alkyl vinyl ether) is preferably at least one selected from the group consisting of fluoromonomers represented by the general formulas (160), (130) and (140).

[0221] The fluoromonomer represented by general formula (160) is preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether), and even more preferably perfluoro(methyl vinyl ether).

[0222] The fluoromonomer represented by the general formula (130) is preferably at least one selected from the group consisting of CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF3, and CF2=CFOCF2OCF2CF2OCF3.

[0223] The fluoromonomer represented by general formula (140) is preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)O(CF2)3F, CF2=CFO(CF2CF(CF3)O)2(CF2)3F, and CF2=CFO(CF2CF(CF3)O)2(CF2)2F.

[0224] The fluoromonomer represented by general formula (150) is preferably at least one selected from the group consisting of CF2=CFOCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2SO2F, CF2=CFOCF2CF(CF2CF2SO2F)OCF2CF2SO2F and CF2=CFOCF2CF(SO2F)2.

[0225] Examples of perfluoro(alkylaryl ether) include: General formula (180): CF2=CF-CF2-ORf 111 (In the formula, Rf 111 represents a perfluoroorganic group.

[0226] Rf of general formula (180) 111 is Rf in general formula (110) 111 is the same as Rf 111 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoro(alkylaryl ether) represented by general formula (180) is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0227] A partially fluorinated monomer may be polymerized together with the perfluoromonomer. The partially fluorinated monomer preferably has at least one double bond. Examples of the partially fluorinated monomer include chlorotrifluoroethylene (CTFE), vinyl fluoride, vinylidene fluoride (VDF), trifluoroethylene, fluoroalkyl vinyl ether, fluoroalkyl ethylene, fluoroalkyl allyl ether, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, and compounds represented by the general formula (100): CHX 101 =CX 102 Rf 101 (In the formula, X 101 and X 102 is H on one side and F on the other side, and Rf 101 is preferably at least one selected from the group consisting of a fluoromonomer represented by (a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), a fluorinated vinyl heterocyclic compound, and a monomer that provides a crosslinking site.

[0228] Examples of the fluoroalkyl vinyl ether include: General formula (120): CF2=CF-OCH2-Rf 121 (In the formula, Rf 121 is a perfluoroalkyl group having 1 to 5 carbon atoms).

[0229] The fluoromonomer represented by the general formula (100) is Rf 101 is a linear fluoroalkyl group, and Rf 101 More preferred is a fluoromonomer in which Rf is a linear perfluoroalkyl group. 101The number of carbon atoms in the formula (100) is preferably 1 to 6. Examples of the fluoromonomer represented by the formula (100) include CH2=CFCF3, CH2=CFCF2CF3, CH2=CFCF2CF2CF3, CH2=CFCF2CF2CF2H, CH2=CFCF2CF2CF2CF3, CHF=CHCF3 (E-isomer), and CHF=CHCF3 (Z-isomer), and among these, 2,3,3,3-tetrafluoropropylene represented by CH2=CFCF3 is preferred.

[0230] Fluoroalkylethylenes include: General formula (170): CH2=CH-(CF2) n -X 171 (In the formula, X 171 is H or F, and n is an integer of 3 to 10.) is preferred, and fluoroalkylethylenes represented by CH2=CH-C4F9 and CH2=CH-C6F 13 It is more preferable that the material is at least one selected from the group consisting of:

[0231] The fluorinated vinyl heterocycle includes a compound represented by the general formula (230): [ka] (In the formula, X 231 and X 232 are independently F, Cl, a methoxy group, or a fluorinated methoxy group; Y 231 is the formula Y 232 or formula Y 233 is.

[0232] [ka] (In the formula, Z 231 and Z 232 are independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0233] Examples of monomers that provide crosslinking sites include: General formula (181):CX 181 2=CX182 -R f 181 CHR 181 X 183 (In the formula, X 181 and X 182 are independently a hydrogen atom, a fluorine atom, or CH3, R f 181 represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, R 181 is a hydrogen atom or CH3, X 183 is an iodine atom or a bromine atom. General formula (190):CX 191 2=CX 192 -R f 191 X 193 (In the formula, X 191 and X 192 are independently a hydrogen atom, a fluorine atom, or CH3, R f 191 represents a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group, X 193 is an iodine atom or a bromine atom. General formula (200): CF2=CFO(CF2CF(CF3)O) m (CF2) n -X 201 (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X 201 is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2I; and General formula (210): CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X 211 (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X 211is a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CHOH; General formula (220):CR 221 R 222 =CR 223 -Z 221 -CR 224 =CR 225 R 226 (In the formula, R 221 , R 222 , R 223 , R 224 , R 225 and R 226 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. 221 represents a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 3 to 18 carbon atoms, an at least partially fluorinated alkylene group or oxyalkylene group having 1 to 10 carbon atoms, which may have an oxygen atom, or -(Q) p -CF2O-(CF2CF2O) m (CF2O) n -CF2-(Q) p - (wherein Q is an alkylene group or an oxyalkylene group, p is 0 or 1, and m / n is 0.2 to 5), and is a (per)fluoropolyoxyalkylene group having a molecular weight of 500 to 10,000. It is preferable that the material is at least one selected from the group consisting of:

[0234] X 183 and X 193 is preferably an iodine atom. f 181 and R f 191 is preferably a perfluoroalkylene group having 1 to 5 carbon atoms. 181 is preferably a hydrogen atom. 201 is preferably a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH2I. 211is preferably a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH 2 OH.

[0235] Monomers that provide crosslinking sites include CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2COOH, CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CF2=CFOCF2CF2CH2I, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, CH2=CFCF2OCF( It is preferably at least one selected from the group consisting of 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.

[0236] In the polymerization, the perfluoromonomer and a non-fluorine-containing monomer may be polymerized. Examples of the non-fluorine-containing monomer include hydrocarbon-based monomers reactive with the fluoromonomer. Examples of the hydrocarbon-based monomer include alkenes such as ethylene, propylene, butylene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl para-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, and vinyl hydroxybenzoates. vinyl esters such as vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, and vinyl hydroxycyclohexanecarboxylate; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, and cyclohexyl allyl ester; and (meth)acrylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, and vinyl methacrylate.

[0237] The fluorine-free monomer may also be a functional group-containing hydrocarbon monomer (excluding the monomer that provides a crosslinking site). Examples of the functional group-containing hydrocarbon monomer include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; fluorine-free monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, and perfluorobutenoic acid; fluorine-free monomers having a sulfo group such as vinyl sulfonic acid; fluorine-free monomers having a glycidyl group such as glycidyl vinyl ether and glycidyl allyl ether; fluorine-free monomers having an amino group such as aminoalkyl vinyl ether and aminoalkyl allyl ether; fluorine-free monomers having an amide group such as (meth)acrylamide and methylolacrylamide; fluorine-free monomers having a nitrile group such as acrylonitrile and methacrylonitrile.

[0238] In the above polymerization, one or more types of monomers such as perfluoromonomers are polymerized to obtain particles of the desired fluoropolymer.

[0239] The amount of polymer (1) added in the polymerization is preferably more than 0.0001% by mass and not more than 20% by mass, more preferably 0.001% by mass or more, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the aqueous medium. By adjusting the amount of polymer (1) added within the above range, the polymerization of perfluoromonomers in the aqueous medium can proceed smoothly. The amount of polymer (1) added is the total amount of polymer (1) added in the polymerization.

[0240] In the polymerization, the polymer (1) may be added all at once, or may be added continuously. Continuous addition of the polymer (1) means, for example, adding the polymer (1) over time, without interruption, or in portions, rather than all at once. In the polymerization, an aqueous solution containing the polymer (1) and water may be prepared, and the aqueous solution may be added.

[0241] In the above polymerization, the use of at least one polymer (1) allows efficient production of a fluoropolymer. Two or more compounds included in the polymer (1) may be used simultaneously, and other surfactant compounds other than the polymer (1) may be used simultaneously, as long as they are volatile or may remain in a molded product or the like made of a fluoropolymer.

[0242] A nucleating agent may be used in the polymerization. The amount of the nucleating agent added can be appropriately selected depending on the type of nucleating agent. The amount of the nucleating agent added may be 5000 ppm by mass or less, preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, particularly preferably 50 ppm by mass or less, and most preferably 10 ppm by mass or less, relative to the aqueous medium.

[0243] In the above polymerization, it is preferable to add a nucleating agent to the aqueous medium before the start of polymerization or before the solid content of the fluoropolymer formed in the aqueous medium reaches 5.0 mass %. By adding the nucleating agent at the early stage of polymerization, an aqueous dispersion having a small average primary particle size and excellent stability can be obtained.

[0244] The amount of the nucleating agent added at the beginning of polymerization is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more, based on the fluoropolymer to be obtained. The upper limit of the amount of the nucleating agent added at the beginning of polymerization is not limited, but is, for example, 2000% by mass.

[0245] The use of a nucleating agent results in a fluoropolymer having a smaller primary particle size compared to polymerization carried out in the absence of said nucleating agent.

[0246] Examples of the nucleating agent include dicarboxylic acids, perfluoropolyether (PFPE) acids or salts thereof, hydrocarbon-containing surfactants, etc. The nucleating agent preferably does not contain an aromatic ring and is preferably an aliphatic compound.

[0247] The nucleating agent is preferably added before or simultaneously with the addition of the polymerization initiator, but the particle size distribution can also be adjusted by adding it during the polymerization.

[0248] The amount of the dicarboxylic acid is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 100 ppm by mass or less, relative to the aqueous medium.

[0249] The perfluoropolyether (PFPE) acid or salt thereof may have any chain structure in which oxygen atoms in the main chain of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. Two or more types of fluorocarbon groups may be present in the molecule. A typical structure has a repeating unit represented by the following formula: (-CFCF3-CF2-O-) n (VII) (-CF2-CF2-CF2-O-) n (VIII) (-CF2-CF2-O-) n -(-CF2-O-) m (IX) (-CF2-CFCF3-O-)n-(-CF2-O-) m (X)

[0250] These structures are described by Kasai in J. Appl. Polymer Sci. 57, 797 (1995). As disclosed therein, the PFPE acid or its salt may have a carboxylic acid group or its salt at one or both ends. The PFPE acid or its salt may also have a sulfonic acid or phosphonic acid group or their salt at one or both ends. The PFPE acid or its salt may also have a different group at each end. For monofunctional PFPEs, the other end of the molecule is usually perfluorinated but may contain a hydrogen or chlorine atom. The PFPE acid or its salt has at least two ether oxygens, preferably at least four ether oxygens, and even more preferably at least six ether oxygens. Preferably, at least one of the fluorocarbon groups separating the ether oxygens, and more preferably at least two of such fluorocarbon groups, has two or three carbon atoms. Even more preferably, at least 50% of the fluorocarbon groups separating the ether oxygens have two or three carbon atoms. Also, preferably, the PFPE acid or salt thereof has a total of at least 15 carbon atoms, for example, the preferred minimum value of n or n+m in the repeating unit structure is at least 5. Two or more of the PFPE acids or salts thereof having acid groups at one or both ends can be used in the manufacturing method of the present disclosure. The PFPE acid or salt thereof preferably has a number average molecular weight of less than 6000 g / mol.

[0251] The amount of the hydrocarbon-containing surfactant added is preferably 40 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 20 ppm by mass or less, relative to the aqueous medium. It is estimated that the ppm amount of lipophilic nucleation sites present in the aqueous medium is less than the amount added. Therefore, the amount of lipophilic nucleation sites is less than the above-mentioned 40 ppm by mass, 30 ppm by mass, and 20 ppm by mass. Since the lipophilic nucleation sites are thought to exist as molecules, even a small amount of the hydrocarbon-containing surfactant can generate a large amount of lipophilic nucleation sites. Therefore, beneficial effects can be obtained even by adding about 1 ppm by mass of the hydrocarbon-containing surfactant to the aqueous medium. The preferred lower limit is 0.01 ppm by mass.

[0252] The hydrocarbon-containing surfactants include nonionic and cationic surfactants, including siloxane surfactants such as those disclosed in U.S. Pat. No. 7,897,682 (Brothers et al.) and U.S. Pat. No. 7,977,438 (Brothers et al.).

[0253] The hydrocarbon-containing surfactant is preferably a nonionic surfactant (for example, a nonionic hydrocarbon surfactant), that is, a nonionic surfactant is preferred as a nucleating agent.

[0254] (nonionic surfactants) The nonionic surfactants used in the manufacturing method of the present disclosure typically do not contain charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains water-soluble functional groups, such as ethylene ether chains derived from polymerization with ethylene oxide.

[0255] Examples of nonionic surfactants include the following: Polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, glycerol esters, and derivatives thereof.

[0256] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0257] Specific examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0258] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0259] Specific examples of sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0260] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0261] Specific examples of glycerol esters include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[0262] Specific examples of the above derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0263] The ethers and esters may have an HLB value of 10-18.

[0264] Examples of nonionic surfactants include the Triton (registered trademark) X series (X15, X45, X100, etc.), the Tergitol (registered trademark) 15-S series, the Tergitol (registered trademark) TMN series (TMN-6, TMN-10, TMN-100, etc.), and the Tergitol (registered trademark) L series, all manufactured by The Dow Chemical Company; the Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m-22, n-23)) and the Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF.

[0265] The nonionic surfactant is preferably a fluorine-free nonionic surfactant. Examples thereof include ether-type nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and polyoxyethylene alkylene alkyl ether; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, and polyoxyethylene fatty acid esters; and amine-based nonionic surfactants such as polyoxyethylene alkylamines and alkylalkanolamides.

[0266] In the above nonionic surfactants, the hydrophobic group may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group.

[0267] The nonionic surfactant is preferably a nonionic surfactant represented by general formula (i). R 6 -OA 1 -H(i) (In the formula, R 6is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A 1 is a polyoxyalkylene chain.

[0268] In general formula (i), R 6 The number of carbon atoms in R is preferably 10 to 16, and more preferably 12 to 16. 6 When the carbon number of R is 18 or less, the composition tends to have excellent sedimentation stability. 6 If the carbon number exceeds 18, the flow temperature is high and it is difficult to handle. 6 If the number of carbon atoms is less than 8, the surface tension of the composition increases, and the permeability and wettability tend to decrease.

[0269] A 1 The polyoxyalkylene chain may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of 5 to 20 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is more than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of the viscosity and sedimentation stability of the composition, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. In particular, A 1 If the oxypropylene group has an average of 0.5 to 1.5, low foaming properties are favorable and it is preferable.

[0270] More preferably, R 6 is (R')(R")HC-, where R' and R" are the same or different straight, branched, or cyclic alkyl groups having a total of at least 5, preferably 7 to 17 carbon atoms. Preferably, at least one of R' or R" is a branched or cyclic hydrocarbon group.

[0271] Specific examples of the polyoxyethylene alkyl ether include C 13 H 27 -O-(C2H4O) n -H, C 12 H 25 -O-(C2H4O) n -H, C 10 H 21 CH(CH3)CH2-O-(C2H4O) n -H, C 13 H 27 -O-(C2H4O) n -(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) n -H, HC(CH 11 )(C7H 15 )-O-(C2H4O) n -H (in each formula, n is an integer of 1 or more). Commercially available polyoxyethylene alkyl ethers include, for example, the Genapol X series (manufactured by Clariant) such as Genapol X080 (trade name), the Noigen TDS series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) such as Noigen TDS-80 (trade name), the Leocol TD series (manufactured by Lion Chemical) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Chemical), the T-Det A series (manufactured by Harcros Chemicals) such as T-Det A138 (trade name), and the Tergitol (registered trademark) 15S series (manufactured by The Dow Chemical Company).

[0272] The nonionic surfactant is preferably an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, or a mixture thereof. Nonionic surfactants of this type are also commercially available, for example, under the trade names TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all trade names, manufactured by The Dow Chemical Company).

[0273] The hydrophobic group of the nonionic surfactant may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group. For example, the nonionic surfactant may be a surfactant represented by the general formula (ii): R 7 -C6H4-OA 2 -H (ii) (In the formula, R 7 is a linear or branched alkyl group having 4 to 12 carbon atoms, and A 2 is a polyoxyalkylene chain.) Specific examples of the nonionic surfactant include Triton (registered trademark) X-100 (trade name, manufactured by Dow Chemical Company).

[0274] A 2 The polyoxyalkylene chain may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of 5 to 20 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is more than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of the viscosity and sedimentation stability of the composition, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. In particular, A 2 If the oxypropylene group has an average of 0.5 to 1.5, low foaming properties are favorable and it is preferable.

[0275] More preferably, R 7is a primary or secondary alkyl group, more preferably (R')(R")HC-, where R' and R" are the same or different straight-chain, branched-chain, or cyclic alkyl groups having a total of at least 5, preferably 7 to 17 carbon atoms. Preferably, at least one of R' or R" is a branched-chain or cyclic hydrocarbon group.

[0276] The nonionic surfactant also includes polyol compounds. Specific examples include those described in International Publication No. 2011 / 014715. Typical examples of polyol compounds include compounds having one or more sugar units as polyol units. The sugar units may be modified to contain at least one long chain. Suitable polyol compounds containing at least one long chain moiety include, for example, alkyl glycosides, modified alkyl glycosides, sugar esters, and combinations thereof. Sugars include, but are not limited to, monosaccharides, oligosaccharides, and sorbitan. Monosaccharides include pentoses and hexoses. Typical examples of monosaccharides include ribose, glucose, galactose, mannose, fructose, arabinose, and xylose. Oligosaccharides include oligomers of 2 to 10 identical or different monosaccharides. Examples of oligosaccharides include, but are not limited to, sucrose, maltose, lactose, raffinose, and isomaltose.

[0277] Typically, sugars suitable for use as polyol compounds include cyclic compounds containing a five-membered ring with four carbon atoms and one heteroatom (typically oxygen or sulfur, but preferably oxygen), or a six-membered ring with five carbon atoms and one heteroatom, preferably oxygen, as described above. These further contain at least two or at least three hydroxyl groups (-OH groups) attached to the carbon ring atoms. Typically, the sugars are modified in that one or more of the hydrogen atoms of the hydroxyl groups (and / or hydroxyalkyl groups) attached to the carbon ring atoms are replaced with long-chain residues, such that an ether or ester bond is created between the long-chain residue and the sugar moiety. Sugar-based polyols may contain one sugar unit or multiple sugar units. One sugar unit or multiple sugar units may be modified with a long-chain moiety as described above. Specific examples of sugar-based polyol compounds include glycosides, sugar esters, sorbitan esters, and mixtures and combinations thereof.

[0278] A preferred class of polyol compounds are the alkyl or modified alkyl glucosides. These classes of surfactants contain at least one glucose moiety. [ka] (wherein x represents 0, 1, 2, 3, 4, or 5; R 1 and R 2 independently represent H or a long chain unit containing at least 6 carbon atoms, with the proviso that R 1 and R 2 and at least one of R is not H. 1 and R 2Typical examples of alkyl polyglucosides include fatty alcohol residues. Examples of fatty alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. While the above formula represents a specific example of an alkyl polyglucoside showing glucose in the pyranose form, it is understood that other sugars or sugars of the same sugar but in different enantiomeric or diastereomeric forms may also be used. Alkyl glucosides can be obtained, for example, by the acid-catalyzed reaction of glucose, starch, or n-butyl glucoside with aliphatic alcohols, typically resulting in a mixture of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, Georg Thieme Verlag, 1999). Examples of aliphatic alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. Alkyl glucosides are also commercially available from Cognis GmbH, Dusseldorf, Germany, under the trade names GLUCOPON or DISPONIL.

[0279] Other nonionic surfactants include difunctional block copolymers supplied by BASF as part of the Pluronic® R series, and tridecyl alcohol alkoxylates supplied by BASF as part of the Iconol® TDA series.

[0280] The nonionic surfactant is preferably at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii), and more preferably nonionic surfactants represented by general formula (i).

[0281] The nonionic surfactant preferably does not contain an aromatic moiety.

[0282] In the above polymerization, a compound having a functional group capable of reacting by radical polymerization and a hydrophilic group may be used together with the polymer (1). As the compound having a functional group capable of reacting by radical polymerization and a hydrophilic group, the same compounds as the modifying monomer (A) described below can be used.

[0283] In the polymerization, in addition to the polymer (1) and, if desired, other surfactant compounds, additives for stabilizing each compound may be used, such as buffers, pH adjusters, stabilizing aids, and dispersion stabilizers.

[0284] The stabilizing aid is preferably paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. The stabilizing aid may be used alone or in combination of two or more. The stabilizing aid is more preferably paraffin wax. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms. The melting point of the paraffin wax is usually preferably 40 to 65°C, more preferably 50 to 65°C.

[0285] The amount of the stabilizing aid used is preferably 0.1 to 12 mass % based on the mass of the aqueous medium used, and more preferably 0.1 to 8 mass %. It is desirable that the stabilizing aid is sufficiently hydrophobic so that it is completely separated from the aqueous dispersion after polymerization and does not become a contaminating component.

[0286] The polymerization is carried out by charging an aqueous medium, the polymer (1), a monomer, and other additives as necessary into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of a polymerization initiator to initiate the polymerization reaction. After the polymerization reaction has started, additional monomers, polymerization initiators, chain transfer agents, polymer (1), and the like may be added depending on the purpose. Polymer (1) may also be added after the polymerization reaction has started.

[0287] Usually, the polymerization temperature is 5 to 120° C. and the polymerization pressure is 0.05 to 10 MPaG. The polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0288] The polymerization initiator is not particularly limited as long as it can generate radicals within the polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, polymerization can also be initiated as a redox reaction in combination with a reducing agent, etc. The concentration of the polymerization initiator is determined appropriately depending on the type of monomer, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0289] As the polymerization initiator, an oil-soluble radical polymerization initiator, a water-soluble radical polymerization initiator, or an azo compound can be used.

[0290] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. Also usable are di(ω-hydro-dodecafluorohexanoyl) peroxide, di(ω-hydro-tetradecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluorovaleryl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as di(ω-hexafluorobutyryl)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0291] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate; organic peroxides such as disuccinic acid peroxide or diglutaric acid peroxide; t-butyl permaleate; or t-butyl hydroperoxide. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0292] For example, when polymerization is carried out at low temperatures below 30°C, it is preferable to use a redox initiator, which combines an oxidizing agent and a reducing agent, as the polymerization initiator. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate, potassium persulfate, and sodium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0293] Examples of the redox initiator include potassium permanganate / oxalic acid, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, and bromate / bisulfite, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate thereto.

[0294] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously at the beginning of polymerization in an amount (for example, several ppm relative to the water concentration) that does not significantly decrease the polymerization rate. The upper limit is a range in which the reaction temperature can be increased while removing heat from the equipment using the heat of polymerization reaction, and a more preferred upper limit is a range in which the heat of polymerization reaction can be removed from the equipment.

[0295] The aqueous medium is a reaction medium for polymerization and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower.

[0296] In the above polymerization, known chain transfer agents, radical scavengers and decomposers may be added depending on the purpose to adjust the polymerization rate and molecular weight.

[0297] Examples of the chain transfer agent include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, methanol, isopropanol, acetone, various mercaptans, various halogenated hydrocarbons such as carbon tetrachloride, and cyclohexane.

[0298] Bromine compounds or iodine compounds may be used as chain transfer agents. Polymerization methods using bromine compounds or iodine compounds include, for example, a method of polymerizing fluoromonomers in an aqueous medium in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the bromine compounds or iodine compounds used include, for example, compounds represented by the general formula: R a I x Br y (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R ais 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.

[0299] Examples of bromine compounds or iodine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2 Examples include CFClBr, CFBrClCFClBr, BrCFCFCFBr, BrCFCFBrOCF, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl) substituted benzenes. These compounds may be used alone or in combination with each other.

[0300] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0301] The amount of the chain transfer agent used is usually 1 to 50,000 ppm by mass, and preferably 1 to 20,000 ppm by mass, based on the total amount of fluoromonomers supplied.

[0302] The chain transfer agent may be added all at once to the reaction vessel before the initiation of polymerization, may be added all at once after the initiation of polymerization, may be added in multiple divided portions during the polymerization, or may be added continuously during the polymerization.

[0303] As the polymerization initiator, persulfates (e.g., ammonium persulfate), or organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0304] In the above polymerization, a perfluoromonomer may be polymerized in an aqueous medium in the presence of polymer (1) to produce an aqueous dispersion of fluoropolymer particles, and the perfluoromonomer may be seed-polymerized to the fluoropolymer particles in the aqueous dispersion of fluoropolymer particles to obtain a fluoropolymer.

[0305] The polymerization is preferably carried out by polymerizing a perfluoromonomer substantially in the absence of a fluorine-containing surfactant (excluding compounds having a functional group reactive in radical polymerization and a hydrophilic group). Conventionally, a fluorine-containing surfactant has been used for the polymerization of a perfluoromonomer in an aqueous medium, but according to the production method of the present disclosure, a fluoropolymer can be obtained even without using a fluorine-containing surfactant.

[0306] In the present disclosure, "substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant relative to the aqueous medium is 10 ppm by mass or less. The amount of the fluorine-containing surfactant relative to the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and still more preferably 1 ppb by mass or less.

[0307] Examples of the fluorine-containing surfactant include anionic fluorine-containing surfactants, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms and having a total carbon number of 20 or less excluding the anionic group.

[0308] The fluorine-containing surfactant may also be a surfactant containing fluorine in the anionic moiety having a molecular weight of 1,000 or less, preferably 800 or less. The "anionic portion" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by the formula (I) below n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0309] The above-mentioned fluorine-containing surfactant also includes a fluorine-containing surfactant having a LogPOW of not more than 3.5. The LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP (where P represents the ratio of the fluorine-containing surfactant concentration in octanol to the fluorine-containing surfactant concentration in water when a 1:1 octanol / water mixture containing the fluorine-containing surfactant undergoes phase separation). The LogPOW is calculated from the HPLC elution time of the sample solution using standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) with known octanol / water partition coefficients under the following conditions: column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), eluent: acetonitrile / 0.6% by mass HClO₄ / water=1 / 1 (vol / vol%), flow rate: 1.0 mL / min, sample amount: 300 μL, column temperature: 40°C, detection light: UV 210 nm. A calibration curve between each elution time and the known octanol / water partition coefficient is then prepared, and the LogPOW is calculated from the HPLC elution time of the sample solution based on this calibration curve.

[0310] Specific examples of the fluorine-containing surfactants include those described in U.S. Patent Application Publication Nos. 2007 / 0015864, 2007 / 0015865, 2007 / 0015866, 2007 / 0276103, 2007 / 0117914, 2007 / 142541, 2008 / 0015319, and U.S. Pat. No. 3,250,808. No. 3,271,341, JP 2003-119204 A, WO 2005 / 042593, WO 2008 / 060461, WO 2007 / 046377, JP 2007-119526 A, WO 2007 / 046482, WO 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, WO 2013 / 189824, and WO 2013 / 189826.

[0311] The anionic fluorine-containing surfactant may be a compound represented by the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. Y 0 is an anionic group. Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. R 7 As for H or C 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom, or NR 7 4, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 7 4, which may be H, Na, K, Li, or NH4. Above Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0312] The general formula (N 0 ) as a compound represented by The following general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F, m1 is an integer of 3 to 15, and Y 0is as defined above, a compound represented by the following general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X n1 is F or CF3, and Y 0 is as defined above, a compound represented by the following general formula (N 3 ): Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 ) (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, m3 is an integer of 1 to 3, and Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is as defined above, a compound represented by the following general formula (N 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) and a compound represented by the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched partially or fully fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y 0 is as defined above, where X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less.

[0313] The general formula (N 0 ) More specifically, the compounds represented by the formula (I) include perfluorocarboxylic acids (I) represented by the following general formula (I), ω-H perfluorocarboxylic acids (II) represented by the following general formula (II), perfluoroethercarboxylic acids (III) represented by the following general formula (III), perfluoroalkyl alkylenecarboxylic acids (IV) represented by the following general formula (IV), perfluoroalkoxy fluorocarboxylic acids (V) represented by the following general formula (V), perfluoroalkyl sulfonic acids (VI) represented by the following general formula (VII), ω-H perfluorosulfonic acids (VII) represented by the following general formula (VII), perfluoroalkyl alkylene sulfonic acids (VIII) represented by the following general formula (VIII), alkyl alkylene carboxylic acids (IX) represented by the following general formula (IX), fluorocarboxylic acids (X) represented by the following general formula (X), alkoxy fluorosulfonic acids (XI) represented by the following general formula (XI), compounds (XII) represented by the following general formula (XII), and compounds (XIII) represented by the following general formula (XIII).

[0314] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF2) n1 COOM (I) (wherein n1 is an integer of 3 to 14, and M is H, a metal atom, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0315] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0316] The perfluoroether carboxylic acid (III) is represented by the following general formula (III): Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.

[0317] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, and Rf 3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.

[0318] The alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0319] The perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI): F(CF2) n5 SO3M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0320] The ω-H perfluorosulfonic acid (VII) is represented by the following general formula (VII): H(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0321] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (In the formula, Rf 5 is a perfluoroalkyl group having 1 to 13 carbon atoms, n7 is an integer of 1 to 3, and M is as defined above.

[0322] The alkyl alkylene carboxylic acid (IX) is represented by the following general formula (IX): Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6 is a linear or branched partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer of 1 to 3, and M is as defined above.

[0323] The fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, Rf 7 is a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond and / or a chlorine atom, and Rf 8 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0324] The alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI): Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (In the formula, Rf 9 is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, and which may contain chlorine, and which is partially or completely fluorinated; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0325] The compound (XII) is represented by the following general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 may be the same or different and are H, F and linear or branched partially or fully fluorinated alkyl groups having 1 to 6 carbon atoms which may contain ether bonds; Rf 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. Y 0may be -COOM, -SO2M, or -SO3M, and may be -SO3M or COOM (wherein M is as defined above). Examples of L include a single bond and a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0326] The compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11 is a fluoroalkyl group containing chlorine and having 1 to 5 carbon atoms, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above. Compound (XIII) is represented by the formula: CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, wherein n9 and n10 are defined above).

[0327] As mentioned above, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0328] The fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0329] Examples of the fluorine-containing surfactant include compounds represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds: In one embodiment of the above polymerization, the fluoromonomer is polymerized substantially in the absence of a compound represented by the following formula: F(CF2)7COOM, F(CF2)5COOM, H(CF2)6COOM, H(CF2)7COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, [ka] (In each formula, M is H, metal atom, NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7 is H or an organic group.

[0330] The polymerization can produce an aqueous dispersion containing the fluoropolymer. The fluoropolymer usually has a concentration of 8 to 50 mass% in the aqueous dispersion obtained by the polymerization. In the aqueous dispersion, the lower limit of the fluoropolymer concentration is preferably 10 mass%, more preferably 15 mass%, and the upper limit is preferably 40 mass%, more preferably 35 mass%.

[0331] The fluoropolymer content in the aqueous dispersion is a value obtained by drying 1 g of the aqueous dispersion in a blower dryer at 150°C for 60 minutes, measuring the mass of the heating residue, and calculating the percentage of the mass of the heating residue relative to the mass (1 g) of the aqueous dispersion.

[0332] <Fluoropolymer> The first production method of the present disclosure provides a fluoropolymer in which the content of polymerized units based on perfluoromonomer is 90 mol% or more relative to the total polymerized units of the fluoropolymer. The fluoropolymer in which the content of polymerized units based on perfluoromonomer is 90 mol% or more does not contain partially fluorinated rubber.

[0333] The fluoropolymers preferably have an ion exchange ratio (IXR) greater than 53. Preferred fluoropolymers have no ionic groups or a limited number of ionic groups resulting in an ion exchange ratio greater than about 100. Preferred fluoropolymers preferably have an ion exchange ratio of 1000 or greater, more preferably 2000 or greater, and even more preferably 5000 or greater.

[0334] The fluorine substitution rate of the fluoropolymer obtained by the first production method of the present disclosure is preferably 90 to 100 mass %, more preferably 95 mass % or more. The fluoropolymer may be a perfluororesin or a perfluoroelastomer.

[0335] The fluorine substitution rate can be calculated by the following formula. Fluorine substitution rate (%) = (number of fluorine atoms bonded to carbon atoms constituting the fluoropolymer) / ((number of hydrogen atoms bonded to carbon atoms constituting the fluoropolymer) + (number of fluorine atoms and chlorine atoms bonded to carbon atoms constituting the fluoropolymer)) × 100

[0336] Fluoropolymers obtainable by the first production method of the present disclosure include melt-processable fluororesins such as polytetrafluoroethylene [PTFE], TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoro(alkyl allyl ether) copolymer, and electrolyte polymer precursors; and perfluoroelastomers.

[0337] Of these, the fluoropolymer is preferably at least one selected from the group consisting of PTFE and perfluoroelastomer.

[0338] The fluoropolymer may have a core-shell structure. Examples of the fluoropolymer having a core-shell structure include PTFE particles containing a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE. Examples of such PTFE include the PTFE described in JP-A-2005-527652.

[0339] The core-shell structure may have the following structure. Core: TFE homopolymer Shell: TFE homopolymer Core: Modified PTFE Shell: TFE homopolymer Core: Modified PTFE Shell: Modified PTFE Core: TFE homopolymer Shell: Modified PTFE Core: Low molecular weight PTFE Shell: High molecular weight PTFE Core: High molecular weight PTFE Shell: Low molecular weight PTFE

[0340] In the fluoropolymer having the core-shell structure, the lower limit of the core ratio is preferably 0.5 mass%, more preferably 1.0 mass%, even more preferably 3.0 mass%, particularly preferably 5.0 mass%, and most preferably 10.0 mass%. The upper limit of the core ratio is preferably 99.5 mass%, more preferably 99.0 mass%, even more preferably 98.0 mass%, even more preferably 97.0 mass%, particularly preferably 95.0 mass%, and most preferably 90.0 mass%.

[0341] In the fluoropolymer having the core-shell structure, the lower limit of the shell ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the shell ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0342] In the fluoropolymer having the core-shell structure, the core or the shell may be configured to have two or more layers. For example, the fluoropolymer may have a three-layer structure having a core center portion of modified PTFE, a core outer layer portion of TFE homopolymer, and a shell of modified PTFE.

[0343] The fluoropolymer having the core-shell structure also includes a particle of the fluoropolymer having multiple cores.

[0344] The above-mentioned (I) PTFE, (II) melt-processable fluororesin, and (III) perfluoroelastomer, which are suitably produced by the production method of the present disclosure, are preferably produced in the following manner.

[0345] (I) PTFE In the first production method of the present disclosure, PTFE (TFE polymer) can be produced as a fluoropolymer by polymerizing TFE as a perfluoromonomer. The PTFE is preferably non-melt-processible PTFE.

[0346] In the production method of the present disclosure, TFE polymerization is usually carried out at a polymerization temperature of 10 to 150°C and a polymerization pressure of 0.05 to 5 MPaG. For example, the polymerization temperature is more preferably 30°C or higher, and even more preferably 50°C or higher. It is more preferably 120°C or lower, and even more preferably 100°C or lower. The polymerization pressure is more preferably 0.3 MPaG or higher, and even more preferably 0.5 MPaG or higher, and more preferably 5.0 MPaG or lower, and even more preferably 3.0 MPaG or lower. In particular, from the viewpoint of improving the yield of the fluoropolymer, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, more preferably 1.5 MPaG or higher, and even more preferably 2.0 MPaG or higher.

[0347] In one embodiment, the polymerization is carried out by charging pure water into a pressure-resistant reaction vessel equipped with a stirrer, deoxidizing, then charging TFE, adjusting the temperature to a predetermined level, and adding a polymerization initiator to initiate the reaction. If the pressure decreases as the reaction proceeds, additional TFE is continuously or intermittently supplied to maintain the initial pressure. Once a predetermined amount of TFE has been supplied, the supply is stopped, the TFE in the reaction vessel is purged, and the temperature is returned to room temperature to terminate the reaction. Additional TFE may be continuously or intermittently supplied to prevent the pressure from decreasing.

[0348] In the production of the TFE polymer (PTFE), various known modified monomers can also be used in combination. In the present disclosure, the TFE polymer is a concept that includes not only a TFE homopolymer but also a copolymer of TFE and a modified monomer that is not melt-processable (hereinafter referred to as "modified PTFE").

[0349] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include fluoromonomers and non-fluoromonomers. The modifying monomer used may be one type or multiple types.

[0350] The non-fluoromonomer is not particularly limited and may be selected from the group consisting of monomers having the general formula: CH2=CR Q1 -LR Q2 (In the formula, R Q1 represents a hydrogen atom or an alkyl group. L represents a single bond, -CO-O-*, -O-CO-* or -O-. * represents R Q2 R represents the bond position with Q2 represents a hydrogen atom, an alkyl group or a nitrile group.

[0351] Examples of non-fluoromonomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, vinyl methacrylate, vinyl acetate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, ethyl vinyl ether, cyclohexyl vinyl ether, etc. Of these, butyl methacrylate, vinyl acetate, and acrylic acid are preferred as non-fluoromonomers.

[0352] Examples of fluoromonomers include perfluoroolefins such as hexafluoropropylene (HFP); hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF); perhaloolefins such as chlorotrifluoroethylene; perfluorovinyl ethers; (perfluoroalkyl)ethylenes; and perfluoroallyl ethers.

[0353] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoroorganic group). In the present disclosure, the "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0354] An example of the perfluorovinyl ether is perfluoro(alkyl vinyl ether) [PAVE], where Rf in general formula (A) is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0355] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0356] The perfluorovinyl ether further includes those in which Rf in the general formula (A) is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf ...

[0357] [ka]

[0358] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0359] CF3CF2CF2-(O-CF(CF3)-CF2) n - (wherein n represents an integer of 1 to 4).

[0360] 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).

[0361] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0362] Examples of perfluoroallyl ethers include: General formula: CF2=CF-CF2-ORf (wherein Rf represents a perfluoro organic group).

[0363] Rf in the above general formula is the same as Rf in general formula (A). Rf is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0364] A preferred example of the modifying monomer is the modifying monomer (3) having a monomer reactivity ratio of 0.1 to 8. The presence of the modifying monomer (3) makes it possible to obtain PTFE particles having a small particle size and an aqueous dispersion with high dispersion stability.

[0365] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant when the propagating radical reacts with TFE when the propagating radical is less than a repeating unit based on TFE by the rate constant when the propagating radical reacts with the modified monomer. The lower this value, the higher the reactivity of the modified monomer with TFE. The monomer reactivity ratio can be calculated by copolymerizing TFE and the modified monomer, determining the composition in the resulting polymer immediately after the start of copolymerization, and using the Feynman-Ross equation.

[0366] The copolymerization was carried out in a 6.0 L stainless steel autoclave using 3600 g of deionized and degassed water, 1000 ppm by mass of ammonium perfluorooctanoate relative to the water, and 100 g of paraffin wax at a pressure of 0.78 MPaG and a temperature of 70°C. 0.05 g, 0.1 g, 0.2 g, 0.5 g, and 1.0 g of the modified monomer were added to the reactor, respectively, and 0.072 g of ammonium persulfate (20 ppm by mass relative to the water) was added. TFE was continuously fed to maintain the polymerization pressure at 0.78 MPaG. When the TFE charge reached 1000 g, stirring was stopped and the reactor was depressurized until atmospheric pressure was reached. After cooling, the paraffin wax was separated to obtain an aqueous dispersion containing the resulting polymer. The aqueous dispersion was stirred to coagulate the resulting polymer, which was then dried at 150°C. The composition of the resulting polymer is calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0367] The modified monomer (3) having a monomer reactivity ratio of 0.1 to 8 is preferably at least one selected from the group consisting of modified monomers represented by formulas (3a) to (3d). CH2=CH-Rf 1 (3a) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 10 carbon atoms. CF2=CF-O-Rf 2 (3b) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 2 carbon atoms. CF2=CF-O-(CF2) n CF=CF2(3c) (wherein n is 1 or 2).

[0368] [ka] (In the formula, X 3 and X 4 is F, Cl or a methoxy group, and Y is of formula Y1 or Y2.

[0369] [ka] (In formula Y2, Z and Z′ are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0370] The content of the modifying monomer (3) units is preferably in the range of 0.00001 to 1.0% by mass relative to the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass.

[0371] As the above-mentioned modified monomer, since it can obtain an aqueous dispersion with a small average primary particle diameter, a small aspect ratio of primary particles, and excellent stability, it is preferable to use at least one selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, perfluoro(alkyl vinyl ether), (perfluoroalkyl)ethylene, ethylene, and modified monomers having a functional group capable of reacting by radical polymerization and a hydrophilic group.By using the above-mentioned modified monomer, it is possible to obtain an aqueous dispersion of PTFE with a smaller average primary particle diameter, a small aspect ratio of primary particles, and excellent dispersion stability.In addition, it is possible to obtain an aqueous dispersion with less uncoagulated polymer.

[0372] From the viewpoint of reactivity with TFE, the modifying monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene. More preferably, it contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. The total amount of the hexafluoropropylene units, perfluoro(alkyl vinyl ether) units, and (perfluoroalkyl)ethylene units is preferably in the range of 0.00001 to 1% by mass relative to all polymerized units of PTFE. The lower limit of the total amount is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limits are, in order of preference, 0.80%, 0.70%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass.

[0373] The above-mentioned modified monomer preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group (hereinafter referred to as "modified monomer (A)").

[0374] The presence of the above-mentioned modifying monomer (A) can produce PTFE particles with a small primary particle size, and can produce an aqueous dispersion with high dispersion stability. It can also reduce the amount of uncoagulated polymer. Furthermore, it can reduce the aspect ratio of the primary particles.

[0375] The amount of the modified monomer (A) used is preferably more than an amount corresponding to 0.1 ppm by mass of the aqueous medium, more preferably more than 0.5 ppm by mass, even more preferably more than 1.0 ppm by mass, even more preferably 5 ppm by mass or more, and particularly preferably 10 ppm by mass or more. If the amount of the modified monomer (A) used is too small, the average primary particle size of the obtained PTFE may not be reduced. The amount of the modified monomer (A) used may be within the above range, but the upper limit can be, for example, 5000 ppm by mass. In the above production method, the modified monomer (A) may be added to the system during the reaction to improve the stability of the aqueous dispersion during or after the reaction.

[0376] The above-mentioned modified monomer (A) is highly water-soluble, so even if unreacted modified monomer (A) remains in the aqueous dispersion, it can be easily removed in the concentration step or the coagulation and washing step.

[0377] The above-mentioned modifying monomer (A) is incorporated into the produced polymer during the polymerization process, but since the concentration of the modifying monomer (A) itself in the polymerization system is low and the amount incorporated into the polymer is small, there are no problems such as a decrease in the heat resistance of PTFE or coloration after baking.

[0378] Examples of the hydrophilic group in the modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M represents H, a metal atom, or NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7y are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), with Na, K, or Li being preferred.

[0379] Examples of the "functional group capable of reacting by radical polymerization" in the modifying monomer (A) include groups having an ethylenically unsaturated bond, such as a vinyl group and an allyl group. The group having an ethylenically unsaturated bond is a group represented by the following formula: CX e X g =CX f R- (In the formula, X e , X f and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group. The linking group for R can be represented by the formula: a Preferred linking groups include -CH=CH2 and -CF=CH 2、 -CH=CF 2、 Examples include groups having an unsaturated bond such as -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CH=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, and -O-CF2-CF=CF2.

[0380] The modified monomer (A) has a functional group capable of reacting by radical polymerization, and therefore, when used in the polymerization, it is presumed that it reacts with the fluorine-containing monomer at the initial stage of the polymerization reaction, and forms highly stable particles having hydrophilic groups derived from the modified monomer (A). Therefore, it is considered that the number of particles increases when polymerization is carried out in the presence of the modified monomer (A).

[0381] The polymerization may be carried out in the presence of one type of the modifying monomer (A), or in the presence of two or more types of the modifying monomer (A).

[0382] In the polymerization, a compound having an unsaturated bond can be used as the modifying monomer (A).

[0383] The modifying monomer (A) is represented by the general formula (4): CX i X k =CX j R a -(CZ 1 Z 2 ) k -Y 3 (4) (In the formula, X i , X j and X k are each independently F, Cl, H, or CF; Y 3 is a hydrophilic group; R a is a linking group; Z 1 and Z 2 are each independently H, F or CF3, and k is 0 or 1). Examples of the hydrophilic group include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M represents H, a metal atom, or NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7y are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the following formula: Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K or Li being preferred. By using the modifying monomer (A), an aqueous dispersion having a smaller average primary particle size and better stability can be obtained, and the aspect ratio of the primary particles can also be made smaller.

[0384] Above R a is a linking group. In the present disclosure, "linking group" refers to a divalent linking group. The linking group may be a single bond and preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less. The linking group may be linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0385] Above R a is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group. R a When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and may or may not contain a double bond. a may be either linear or branched, and may be either cyclic or acyclic. a may contain functional groups (e.g., esters, ethers, ketones, amines, halides, etc.). R a may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group. R aExamples of the hydrocarbon group include a hydrocarbon group in which no fluorine atoms are bonded to a carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, a hydrocarbon group in which all of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, -(C=O)-, -(C=O)-O-, or a hydrocarbon group containing an ether bond, which may contain an oxygen atom, a double bond, or a functional group.

[0386] R a is preferably —(C═O)—, —(C═O)—O—, or a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond and may contain a carbonyl group, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine. R a 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 At least one selected from -, -(C=O)-O-C6H4-, and combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0387] 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 -(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. 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- is preferred. In the above formula, n is an integer of 1 to 10.

[0388] -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- is more preferred. In the above formula, n is an integer of 1 to 10.

[0389] Specific examples of the compound represented by general formula (4) include: [ka] (In the formula, X j and Y 3 is the same as above. n is an integer of 1 to 10.

[0390] R a As the general formula (r1): -(C=O) h -(O) i -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6are each independently H, F, or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1), and a divalent group represented by the general formula (r2): -(C=O) h -(O) i -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1. Divalent groups represented by the following formula are also preferred.

[0391] -R in general formula (4) a -(CZ 1 Z 2 ) k - can also be represented by the following formula (t1): -(C=O) h -(O) i -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (t1) (In the formula, X 6 are each independently H, F, or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z 1 and Z 2 are each independently F or CF3), and in formula (t1), Z 1 and Z 2 More preferably, one is F and the other is CF3. In addition, in the general formula (4), -R a -(CZ 1 Z 2 ) k - is the following formula (t2): -(C=O) h -(O) i-CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (t2) (In the formula, X 7 are each independently H, F, or CF3, e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z 1 and Z 2 are each independently F or CF3), and in formula (t2), Z 1 and Z 2 More preferably, one is F and the other is CF3.

[0392] The compound represented by the general formula (4) is a hydrophilic group (Y 3 ), it is also preferable that the compound has a C—F bond and does not have a C—H bond. i , X j , and X k All of the are F and R a is preferably a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be cyclic or acyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0393] The compound represented by the general formula (4) may be partially fluorinated. That is, the compound represented by the general formula (4) may have a hydrophilic group (Y 3 ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0394] The compound represented by general formula (4) is also preferably a compound represented by the following formula (4a). CF2=CF-O-Rf 0 -Y 3 (4a) (In the formula, Y3 is a hydrophilic group, and Rf 0 is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0395] The compound represented by general formula (4) is also preferably a compound represented by the following formula (4b). CH2=CH-O-Rf 0 -Y 3 (4b) (In the formula, Y 3 is a hydrophilic group, and Rf 0 is a perfluorinated divalent linking group defined by formula (4a).

[0396] In general formula (4), Y 3 One of the preferred embodiments is -OSO3M. 3 is -OSO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2SON(CH3)CH2CH2OSO3M), etc. In the above formulas, M is the same as above.

[0397] In general formula (4), Y 3 Another preferred form is -SO3M. 3is -SO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CH2=CH(CF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH((CF2)3SO3M), etc. In the above formulas, M is the same as above.

[0398] In general formula (4), Y 3 -COOM is also a preferred form. 3 is -COOM, the compounds represented by general formula (4) include CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) n COOM) (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH((CF2)3COOM), CF2=CF(OCF2CF2SO2NR'CH2COOM), CF2=CF(O(CF2)4SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), CH2=CH((CF2)3SO2NR'CH2COOM). In the above formula, R' is H or C 1-4 is an alkyl group, and M is the same as above.

[0399] In general formula (4), Y 3 In another preferred embodiment, Y is -OPO3M or -OP(O)(OM)2.3 is -OPO3M or -OP(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OP(O)(OM)2), CF2=CF(O(CF2)4CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OP(O)(OM)2), CF2=CF(O CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2, CH2=CH((CF2)4CH2OP(O)(OM)2), CH2=CH((CF2)3CH2OP(O)(OM)2), etc. In the above formula, M is the same as above.

[0400] In general formula (4), Y 3 In another preferred embodiment, Y is -PO3M or -P(O)(OM)2. 3 is -PO3M or -P(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2P(O)(OM)2), CF2=CF(O(CF2)4P(O)(OM)2), CF2=CF(OCF2CF(CF3)P(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)4P(O)(OM)2), CH2=CH((CF2)3P(O)(OM)2), and the like, where M is the same as above.

[0401] The compound represented by general formula (4) includes compounds represented by general formula (5): CX2=CY(-CZ2-O-Rf-Y 3 ) (5) (In the formula, X's may be the same or different and each represent -H or -F; Y's may be -H, -F, an alkyl group or a fluorine-containing alkyl group; and Z's may be the same or different and each represent -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf's may be a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above.), a compound represented by general formula (6): CX2=CY(-O-Rf-Y 3 ) (6) (In the formula, X may be the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above.) and a compound represented by general formula (7): CX2=CY(-Rf-Y 3 ) (7) (In the formula, X may be the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above. Preferably, the compound is at least one selected from the group consisting of compounds represented by The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0402] In general formula (5), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0403] In the general formula (5), Y is —H, —F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0404] In general formula (5), Z may be the same or different and is —H, —F, an alkyl group or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[0405] 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.

[0406] In the general formula (5), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. Also, it is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0407] The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, and even more preferably 12 or less. Examples of the fluorine-containing alkylene group having an ether bond include a group represented by the following formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0408] In the general formula (5), Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7y are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. R 7y The organic group in is preferably an alkyl group. R 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. M is -H, a metal atom, or NR 7 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or -NH4 is most preferred. Above Y 3 As the alkyl group, -COOM or -SO3M is preferred, and -COOM is more preferred.

[0409] The compound represented by general formula (5) is preferably a compound (5a) represented by general formula (5a). CH2=CF(-CF2-O-Rf-Y 3 ) (5a) (Wherein Rf and Y 3 is the same as above.)

[0410] Specific examples of the compound represented by general formula (5a) include compounds represented by the following formula:

[0411] [ka]

[0412] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 are integers between 0 and 10; s1 is 0 or 1; t1 is an integer between 0 and 5; Y 3 is the same as above, except for Z 3 and Z 4 are both H, then p1+q1+r1+s1 is not 0). More specifically, compounds represented by the following formula are exemplified:

[0413] [ka]

[0414] Among them,

[0415] [ka]

[0416] It is preferable that:

[0417] The compound represented by general formula (5a) includes compounds represented by formula (5a) 3 is preferably -COOM, and particularly preferably at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above), and more preferably CH2=CFCF2OCF(CF3)COOM.

[0418] The compound represented by general formula (5) is preferably a compound (5b) represented by general formula (5b). CX 2 2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y3 (5b) (In the formula, each 2 are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, and Y 3 is the same as the definition above.)

[0419] In the formula (5b), n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in terms of the stability of the resulting aqueous dispersion. 3 is preferably -COOM in that it provides adequate water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the obtained molded body is improved.

[0420] Examples of the compound represented by the above formula (5b) include CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above).

[0421] Further, examples of the compound represented by general formula (5) include a compound represented by general formula (5c).

[0422] CF2=CFCF2-O-Rf-Y 3 (5c) (Wherein Rf and Y 3 is the same as above)

[0423] More specifically, [ka] etc.

[0424] In general formula (6), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0425] In the general formula (6), Y is —H, —F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0426] 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.

[0427] In the general formula (6), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0428] In the above general formula (6), Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7yare H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. M is -H, a metal atom, or NR 7 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, -H, -Na, -K, -Li or NH4 is even more preferred, -H, -Na, -K or NH4 is even more preferred, -H, -Na or NH4 is especially preferred, and -H or -NH4 is most preferred. Above Y 3 As the alkyl group, -COOM or -SO3M is preferred.

[0429] The compound represented by general formula (6) is preferably at least one selected from the group consisting of compounds represented by general formulae (6a), (6b), (6c), (6d) and (6e). CF2=CF-O-(CF2) n1 -Y 3 (6a) (wherein n1 represents an integer of 1 to 10, and Y 3 is the same as the definition above.) CF2=CF-O-(CF2C(CF3)F) n2 -Y 3 (6b) (wherein n2 represents an integer of 1 to 5, and Y 3 is the same as the definition above.) CF2=CF-O-(CFX 1 ) n3 -Y 3 (6c) (In the formula, X 1represents F or CF3, n3 represents an integer of 1 to 10, and Y 3 is the same as the definition above.) CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -Y 3 (6d) (wherein n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and Y 3 and X 1 is the same as the definition above.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-Y 3 (6e) (wherein n5 represents an integer of 0 to 10, and Y 3 and X 1 is the same as the definition above.)

[0430] In the formula (6a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. 3 is preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0431] Examples of compounds represented by the above formula (6a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF-O-CF2SO3M, CF2=CF(OCF2CF2SO3M), and CF2=CF(OCF2CF2CF2SO3M) (wherein M is as defined above).

[0432] In the formula (6b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, and Y 3is preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0433] In the formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM or -SO3M in terms of obtaining suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4 in terms of improving dispersion stability.

[0434] In the above formula (6d), the above X 1 is preferably —CF3 from the viewpoint of stability of the aqueous dispersion, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, and Y 3 is preferably —COOM or —SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and the M is preferably H or NH4.

[0435] Examples of the compound represented by the above formula (6d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4, or an alkali metal).

[0436] In the general formula (6e), n5 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably —COOM or —SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and the M is preferably H or NH4.

[0437] Examples of the compound represented by general formula (6e) include CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0438] In general formula (7), Rf is preferably a fluorine-containing alkylene group having a carbon number of 1 to 40. In general formula (7), at least one of X and Y preferably contains a fluorine atom.

[0439] The compound represented by general formula (7) is represented by general formula (7a): CF2=CF-(CF2) n1 -Y 3 (7a) (wherein n1 represents an integer of 1 to 10, and Y 3 is as defined above.) and a compound represented by general formula (7b): CF2=CF-(CF2C(CF3)F) n2 -Y 3 (7b) (wherein n2 represents an integer of 1 to 5, and Y 3 is as defined above. Preferably, at least one compound selected from the group consisting of compounds represented by Above Y 3 is preferably -SO3M or -COOM, and M is H, a metal atom, NR 7y 4. It is preferably an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7y represents H or an organic group.

[0440] In the formula (7a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. 3 is preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. Examples of the compound represented by the above formula (7a) include CF2=CFCF2COOM and CF2=CFCF2SO3M (wherein M is as defined above).

[0441] In the formula (7b), n2 is preferably an integer of 3 or less in terms of the stability of the resulting aqueous dispersion, and Y 3 is preferably -COOM or -SO3M in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0442] The above-mentioned modified monomer preferably contains modified monomer (A), and preferably contains at least one selected from the group consisting of compounds represented by general formula (5a), general formula (5c), general formula (6a), general formula (6b), general formula (6c), and general formula (6d), and more preferably contains a compound represented by general formula (5a) or general formula (5c).

[0443] When the modifying monomer (A) is used as the modifying monomer, the content of the modifying monomer (A) units is preferably in the range of 0.00001 to 1.0% by mass relative to the total polymerized units of the TFE polymer (PTFE). The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass.

[0444] In producing the TFE polymer, polymer (1) can be used within the range of use in the production method of the present disclosure described above. The concentration of polymer (1) is not particularly limited as long as it is within the above range. If the amount added is too large, acicular particles with a large aspect ratio are formed, the aqueous dispersion becomes gel-like, and stability is impaired. The lower limit of the amount of polymer (1) used is preferably 0.0001% by mass, more preferably 0.001% by mass, even more preferably 0.01% by mass, and particularly preferably 0.02% by mass, based on the aqueous medium. The upper limit of the amount of polymer (1) used is preferably 10% by mass, more preferably 5% by mass, based on the aqueous medium.

[0445] The polymer (1) may be added to a reaction vessel all at once before the initiation of polymerization, all at once after the initiation of polymerization, or divided into several portions during the polymerization, or may be added continuously during the polymerization.

[0446] In the production of the TFE polymer, persulfates (e.g., ammonium persulfate) and organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used as polymerization initiators, either alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0447] As the redox polymerization initiator, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of redox initiators. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0448] Examples of the redox initiator include potassium permanganate / oxalic acid, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, and bromate / bisulfite, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate thereto.

[0449] In the production of the TFE polymer, known chain transfer agents can be used, including, for example, saturated hydrocarbons such as methane, ethane, propane, and butane; halogenated hydrocarbons such as chloromethane, dichloromethane, and difluoroethane; alcohols such as methanol, ethanol, and isopropanol; and hydrogen. However, those that are in a gaseous state at room temperature and normal pressure are preferred.

[0450] The amount of the chain transfer agent used is usually 1 to 10,000 ppm by mass, and preferably 1 to 5,000 ppm by mass, based on the total amount of TFE supplied.

[0451] In the production of the TFE polymer, a saturated hydrocarbon having 12 or more carbon atoms that is substantially inert to the reaction and becomes liquid under the reaction conditions can also be used as a dispersion stabilizer for the reaction system in an amount of 2 to 10 parts by mass per 100 parts by mass of the aqueous medium. Furthermore, ammonium carbonate, ammonium phosphate, or the like can be added as a buffer to adjust the pH during the reaction.

[0452] When the polymerization of TFE is completed, a polymer dispersion having a solid content of 1.0 to 50 mass % and an average primary particle size of 50 to 500 nm can be obtained. The lower limit of the solid content is preferably 5% by mass, more preferably 8% by mass, and the upper limit is not particularly limited, but may be 40% by mass or 35% by mass. The lower limit of the average primary particle size is preferably 100 nm, more preferably 150 nm, and the upper limit is preferably 400 nm, more preferably 350 nm. The average primary particle size can be measured by dynamic light scattering. An aqueous dispersion adjusted to a solids concentration of approximately 1.0% by mass is prepared, and the average primary particle size is measured by dynamic light scattering at 25°C, with a refractive index of 1.3328 and a viscosity of 0.8878 mPa·s for the solvent (water), and 70 cumulative measurements. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method. The average primary particle diameter can be determined from the measured transmittance of 550 nm projected light for each sample using a calibration curve prepared by measuring the transmittance of 550 nm projected light per unit length of an aqueous dispersion adjusted to a solid content of 0.15% by mass and the number-average primary particle diameter determined by measuring the unidirectional diameter using a transmission electron microscope photograph.

[0453] Fine powders can be produced by coagulating aqueous dispersions of TFE polymers. The aqueous dispersions of TFE polymers can be used for various applications as fine powders after coagulation, washing, and drying. When coagulating the aqueous dispersions of TFE polymers, the aqueous dispersion obtained by polymerization of a polymer latex or the like is typically diluted with water to a polymer concentration of 5 to 20% by mass. In some cases, the pH is adjusted to neutral or alkaline, and the mixture is stirred in a vessel equipped with a stirrer with more vigor than during the reaction. The coagulation may be performed while stirring, using a coagulant such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be performed continuously using an in-line mixer or the like.

[0454] The concentration of the unaggregated TFE polymer in the wastewater resulting from the aggregation is preferably low from the viewpoint of productivity, more preferably less than 0.4% by mass, and particularly preferably less than 0.3% by mass.

[0455] By adding pigments for coloring or various fillers for improving mechanical properties before or during the coagulation, it is possible to obtain a pigmented or filled TFE polymer fine powder in which the pigments and fillers are uniformly mixed.

[0456] The wet powder obtained by coagulating the aqueous dispersion of the TFE polymer is usually dried by means of vacuum, high frequency, hot air, or the like, while keeping the wet powder in a state where it is not fluidized much, preferably in a static state. Friction between powders, particularly at high temperatures, generally has an undesirable effect on fine powder-type TFE polymers. This is because particles made of this type of TFE polymer tend to easily fibrillate even with a small shear force, losing their original stable particle structure.

[0457] The drying is carried out at a drying temperature of 10 to 300°C, preferably 100 to 300°C.

[0458] The TFE polymer in the aqueous dispersion may be coagulated using a metal-free acid or by stirring, and the coagulated TFE polymer may be washed with a liquid medium having a reduced metal element content. The washed TFE polymer may then be dried. By this production method, a TFE polymer having a metal content of 10 mass ppm or less can be produced. The liquid medium is preferably water, and more preferably ultrapure water. The metal content of the liquid medium is preferably 2 mass ppm or less, more preferably 1 mass ppm or less, and even more preferably 0.5 mass ppm or less.

[0459] The resulting TFE polymer fine powder is suitable for molding, and suitable applications include tubes for hydraulic and fuel systems in aircraft and automobiles, flexible hoses for chemical solutions, steam, etc., and for electrical wire coating.

[0460] The aqueous dispersion of the TFE polymer can also be stabilized and further concentrated by adding a nonionic surfactant, and used in various applications as a composition to which an organic or inorganic filler is added depending on the purpose. By coating the composition on a substrate made of metal or ceramic, it is possible to form a coating surface that has non-adhesiveness and a low coefficient of friction, and is excellent in gloss, smoothness, abrasion resistance, weather resistance, and heat resistance, and is suitable for painting rolls, cooking utensils, etc., and for impregnating glass cloth.

[0461] An organosol of a TFE polymer can also be prepared from the aqueous dispersion. The organosol can contain the TFE polymer and an organic solvent. Examples of the organic solvent include ether solvents, ketone solvents, alcohol solvents, amide solvents, ester solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and halogenated hydrocarbon solvents. N-methyl-2-pyrrolidone, dimethylacetamide, and the like are preferably used. The organosol can be prepared, for example, by the method described in International Publication No. 2012 / 002038.

[0462] The aqueous dispersion of the TFE polymer or the fine powder of the TFE polymer is also preferably used as a processing aid. When used as a processing aid, the aqueous dispersion or the fine powder is mixed with a host polymer or the like to improve the melt strength during melt processing of the host polymer, and the mechanical strength, electrical properties, flame retardancy, anti-dripping property during combustion, and sliding properties of the resulting polymer.

[0463] The above-mentioned aqueous dispersion of the TFE polymer or the above-mentioned TFE polymer fine powder is also preferably used as a binder for batteries and for dust prevention purposes.

[0464] The aqueous dispersion of the TFE polymer or the fine powder of the TFE polymer may also be preferably used as a processing aid after being compounded with a resin other than the TFE polymer. The aqueous dispersion or the fine powder is suitable as a raw material for PTFE, as described in, for example, JP-A-11-49912, U.S. Pat. No. 5,804,654, JP-A-11-29679, and JP-A-2003-2980. Processing aids using the aqueous dispersion or the fine powder are in no way inferior to the processing aids described in the above publications.

[0465] Also preferably, the aqueous dispersion of above-mentioned TFE polymer is mixed with the aqueous dispersion of melt-processable fluororesin to be coagulated, and form coprecipitated powder.Above-mentioned coprecipitated powder is suitable as processing aid.

[0466] Examples of the melt-processable fluororesin include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, ethylene / TFE / HFP copolymer [EFEP], etc., with PFA or FEP being preferred.

[0467] The aqueous dispersion preferably contains the melt-processable fluororesin. Examples of the melt-processable fluororesin include FEP, PFA, TFE / perfluoroallyl ether copolymer, ETFE, and EFEP. The aqueous dispersion containing the melt-processable fluororesin can be used as a coating material. The melt-processable fluororesin can sufficiently fuse the TFE polymer particles together, improving film-forming properties and imparting gloss to the resulting coating.

[0468] The fluorine-free resin that adds above-mentioned coprecipitated powder can be powder, can be pellet, can be emulsion.In order to thoroughly mix each resin, it is preferable to add above-mentioned by known method such as extrusion kneading, roll kneading, etc., while applying shearing force.

[0469] The aqueous dispersion of the TFE polymer is also preferably used as a dust-suppressing treatment. The dust-suppressing treatment can be used in a method of mixing the TFE polymer with a dust-generating substance and subjecting the mixture to a compression-shear action at a temperature of 20 to 200°C to fibrillate the TFE polymer and suppress dust from the dust-generating substance, such as the methods described in Japanese Patent No. 2827152 and Japanese Patent No. 2538783. The aqueous dispersion of the TFE polymer can be suitably used, for example, in the dust suppression treatment composition described in WO 2007 / 004250, and can also be suitably used in the dust suppression treatment method described in WO 2007 / 000812.

[0470] The dust suppression treatment agent is suitable for use in the fields of building materials, soil stabilization materials, solidification materials, fertilizers, landfill disposal of incineration ash and hazardous substances, explosion prevention, cosmetics, and dust suppression treatment of sand for pet excretion, such as cat litter.

[0471] The aqueous dispersion of the TFE polymer is also preferably used as a raw material for obtaining TFE polymer fibers by the dispersion spinning method, which is a method in which the aqueous dispersion of the TFE polymer and an aqueous dispersion of a matrix polymer are mixed, the mixture is extruded to form an intermediate fiber structure, and the intermediate fiber structure is fired to decompose the matrix polymer and sinter the TFE polymer particles, thereby obtaining TFE polymer fibers.

[0472] The high molecular weight PTFE powder obtained by polymerization has extensibility and non-melt processability, and is also useful as a raw material for extruded bodies (porous bodies). When this stretched body is a membrane (a stretched PTFE membrane or a porous PTFE membrane), it can be stretched by a known PTFE stretching method. By stretching, the high-molecular-weight PTFE is easily fibrillated, forming a porous PTFE body (membrane) consisting of nodes and fibers. Preferably, a sheet-like or rod-like paste extrudate is roll-stretched in the extrusion direction to obtain a uniaxially stretched film. Furthermore, a biaxially stretched film can also be obtained by stretching the film in the width direction using a tenter or the like. It is also preferable to carry out a semi-baking treatment before stretching.

[0473] This expanded PTFE body is a porous body with high porosity and can be suitably used as a filter medium for various precision filters such as air filters and chemical filters, a support material for polymer electrolyte membranes, and the like. It is also useful as a material for products used in the fields of textiles, medicine, electrochemicals, sealing materials, air filtration, ventilation / internal pressure adjustment, liquid filtration, and general consumer goods. Specific examples of applications are given below.

[0474] Electrochemical field Dielectric material prepreg, EMI shielding material, heat transfer material, etc. More specifically, printed wiring boards, electromagnetic shielding materials, insulating heat transfer materials, insulating materials, etc. Sealing materials field Gaskets, packing, pump diaphragms, pump tubes, aircraft sealing materials, etc.

[0475] Air Filtration ULPA filters (for semiconductor manufacturing), HEPA filters (for hospitals and semiconductor manufacturing), cylindrical cartridge filters (for industrial use), bag filters (for industrial use), heat-resistant bag filters (for exhaust gas treatment), heat-resistant pleated filters (for exhaust gas treatment), SINBRAN filters (for industrial use), catalytic filters (for exhaust gas treatment), adsorbent filters (for HDD integration), adsorbent vent filters (for HDD integration), vent filters (for HDD integration and others), vacuum cleaner filters (for vacuum cleaners), general-purpose multi-layer felt material, GT cartridge filters (for GT compatible products), cooling filters (for electronic equipment housings), etc.

[0476] Ventilation / internal pressure regulation field Freeze-drying materials such as freeze-drying containers, automotive ventilation materials for electronic circuits and lamps, container applications such as container caps, protective ventilation applications for electronic devices including small terminals such as tablet devices and mobile phones, medical ventilation applications, etc.

[0477] Liquid Filtration Semiconductor liquid filtration filters (for semiconductor manufacturing), hydrophilic PTFE filters (for semiconductor manufacturing), chemical filters (for chemical liquid treatment), filters for pure water production lines (for pure water production), backwash type liquid filtration filters (for industrial wastewater treatment), etc.

[0478] General consumer goods Clothing, cable guides (movable wires for motorcycles), motorcycle clothing, cast liners (medical supporters), vacuum cleaner filters, bagpipes (musical instruments), cables (guitar signal cables, etc.), strings (for stringed instruments), etc.

[0479] Textile field PTFE fiber (textile material), sewing thread (textile), weaving thread (textile), rope, etc.

[0480] Medical field Implants (extended products), artificial blood vessels, catheters, general surgery (tissue reinforcement materials), head and neck products (dura mater replacement), oral health (tissue regenerative medicine), orthopedics (bandages), etc.

[0481] The manufacturing method of the present disclosure also allows for the production of low molecular weight PTFE. Low-molecular-weight PTFE may be produced by polymerization, or by lowering the molecular weight of high-molecular-weight PTFE obtained by polymerization by a known method (thermal decomposition, decomposition by irradiation, etc.).

[0482] Low-molecular-weight PTFE (also called PTFE micropowder) having a molecular weight of 600,000 or less has excellent chemical stability, extremely low surface energy, and is resistant to fibrillation. Therefore, it is suitable as an additive for improving the slipperiness and texture of coating surfaces in the production of plastics, inks, cosmetics, paints, greases, office automation equipment components, toners, etc. (see, for example, JP-A-10-147617).

[0483] Furthermore, a low-molecular-weight PTFE may be obtained by dispersing a polymerization initiator and polymer (1) in an aqueous medium in the presence of a chain transfer agent, and polymerizing TFE with TFE or a monomer copolymerizable with TFE. In this case, the chain transfer agent is preferably at least one selected from the group consisting of alkanes having 2 to 4 carbon atoms. Specifically, methane, ethane, propane, butane, and isobutane are more preferred, and ethane and propane are even more preferred. In this case, the amount of chain transfer agent is preferably 10 ppm by mass or more or more than 10 ppm by mass relative to the aqueous medium.

[0484] When the low-molecular-weight PTFE obtained by the above polymerization is used as a powder, the aqueous dispersion can be coagulated to form powder particles.

[0485] In the present disclosure, high molecular weight PTFE is preferably non-melt processible and fibrillating, while low molecular weight PTFE is preferably melt processible and non-fibrillating.

[0486] The term "non-melt processable" means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point in accordance with ASTM D 1238 and D 2116.

[0487] The presence or absence of fibrillating properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," a powder made from a TFE polymer. Paste extrusion is usually possible because high molecular weight PTFE has fibrillating properties. If the unsintered molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it breaks when pulled at 0% elongation, it can be considered to have no fibrillating properties.

[0488] The high-molecular-weight PTFE preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by a water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895-89. In the present disclosure, "high molecular weight" means that the standard specific gravity is within the above range.

[0489] The above low molecular weight PTFE has a melt viscosity of 1×10 at 380°C. 2 ~7×10 5 The molecular weight is Pa·s. In the present disclosure, "low molecular weight" means that the melt viscosity is within the above range. The melt viscosity is measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2g sample preheated to 380°C for 5 minutes, and maintained at the above temperature under a load of 0.7 MPa.

[0490] The high-molecular-weight PTFE has a melt viscosity significantly higher than that of the low-molecular-weight PTFE, making it difficult to measure its melt viscosity accurately. On the other hand, while the melt viscosity of the low-molecular-weight PTFE can be measured, it is difficult to obtain a molded article from the low-molecular-weight PTFE that can be used to measure its standard gravity, making it difficult to measure its standard gravity accurately. Therefore, in this disclosure, standard gravity is used as an indicator of the molecular weight of the high-molecular-weight PTFE, and melt viscosity is used as an indicator of the molecular weight of the low-molecular-weight PTFE. There are no known methods for directly determining the molecular weight of either the high-molecular-weight PTFE or the low-molecular-weight PTFE.

[0491] The high-molecular-weight PTFE preferably has a peak temperature of 333 to 347°C, more preferably 335 to 345°C. The low-molecular-weight PTFE preferably has a peak temperature of 322 to 333°C, more preferably 324 to 332°C. The peak temperature can be identified as the temperature corresponding to the maximum value that appears on a differential thermal analysis (DTA) curve obtained by using a TG / DTA (thermogravimetric / differential thermal analyzer) to raise the temperature of PTFE that has no history of being heated to a temperature of 300°C or higher at a rate of 10°C / min.

[0492] The peak temperature of the PTFE may be 322 to 347°C. When the PTFE is a high molecular weight PTFE, the upper limit of the peak temperature of the PTFE may be 347°C or less, 346°C or less, 345°C or less, 344°C or less, 343°C or less, 342°C or less, 341°C or less, or 340°C or less. When the PTFE is a high-molecular-weight PTFE, the lower limit of the peak temperature of the PTFE may be 333°C or higher, or 335°C or higher. When the PTFE is a low-molecular-weight PTFE, the upper limit of the peak temperature of the PTFE may be 333°C or less, or 332°C or less. When the PTFE is a low-molecular-weight PTFE, the lower limit of the peak temperature of the PTFE may be 322°C or higher, or 324°C or higher.

[0493] The average primary particle diameter of the primary particles of the low-molecular-weight PTFE is preferably 10 to 200 nm, more preferably 20 nm or more, more preferably 150 nm or less, even more preferably 140 nm or less, and particularly preferably 90 nm or less. A relatively small average primary particle diameter of the primary particles can be obtained, for example, by adding a modifying monomer to the polymerization system at the initial stage of TFE polymerization.

[0494] The average primary particle size of low-molecular-weight PTFE primary particles can be measured by dynamic light scattering. First, an aqueous dispersion of low-molecular-weight PTFE is prepared with a polymer solids concentration of approximately 1.0% by mass. Measurements can then be performed using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and 70 cumulative measurements. For dynamic light scattering, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used, for example.

[0495] The high-molecular-weight PTFE preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when PTFE that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 52 mJ / mg or more. The heat of fusion of PTFE is more preferably 55 mJ / mg or more, and even more preferably 58 mJ / mg or more.

[0496] An unsintered tape (green tape) can also be obtained from the PTFE fine powder obtained above.

[0497] (II) Melt-processable fluororesin In the first production method of the present disclosure, by polymerizing a perfluoromonomer such as TFE, it is possible to produce melt-processable fluororesins as fluoropolymers, such as TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoro(alkyl allyl ether) copolymer, and electrolyte polymer precursor.

[0498] (1) In the production method of the present disclosure, the polymerization of FEP is preferably carried out at a polymerization temperature of 10 to 150° C. and a polymerization pressure of 0.3 to 6.0 MPaG.

[0499] The monomer composition (mass %) of FEP is preferably TFE:HFP=(60-95):(5-40), more preferably (85-92):(8-15).

[0500] In addition to TFE and HFP, other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, HFP, and other monomers as FEP. Examples of the other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and HFP) and non-fluorine-containing monomers. One or more types of other monomers may be used. Perfluoro(alkyl vinyl ether) is preferred as the other monomer. The content of the other monomer units in FEP may be 0.1 to 2% by mass based on the total monomer units.

[0501] In the polymerization of FEP, the polymer (1) can be used within the range of use in the production method of the present disclosure, but is usually added in an amount of 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium.

[0502] In the polymerization of FEP, it is preferable to use cyclohexane, methanol, ethanol, propanol, ethane, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, or the like as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, or the like as a pH buffer.

[0503] The aqueous dispersion of FEP obtained by the manufacturing method of the present disclosure may be subjected to post-treatment such as concentration as necessary, dried, powdered, and then melt-extruded into pellets. The aqueous medium in the aqueous dispersion of FEP may contain additives such as a nonionic surfactant as necessary, and may also contain a water-soluble organic solvent such as a water-soluble alcohol, or may not contain a water-soluble organic solvent.

[0504] Furthermore, melt extrusion can be carried out by appropriately setting extrusion conditions as long as the extrusion conditions are generally such that pelletization is possible.

[0505] In the manufacturing method of the present disclosure, the obtained FEP may have terminal groups such as -CF3, -CF2H on at least one of the polymer main chain and polymer side chains, but it is preferable that the content of thermally unstable groups such as -COOH, -CH2OH, -COF, -CF=CF-, -CONH2, and -COOCH3 (hereinafter referred to as "unstable terminal groups") is low or absent.

[0506] The unstable terminal groups are chemically unstable and therefore not only reduce the heat resistance of the resin but also cause an increase in the attenuation of the resulting electric wire.

[0507] In the production method of the present disclosure, the polymer at the end of polymerization is prepared by subjecting the polymer to a polymerization reaction in which the total number of unstable terminal groups and -CFH terminal groups is 1×10 carbon atoms. 6 It is preferable to produce the carbon atoms so that the number of carbon atoms is 50 or less per unit. 6 The number of terminal groups per unit is preferably less than 20, and more preferably not more than 5. The unstable terminal groups and -CF2H terminal groups may be absent, and all may be -CF3 terminal groups.

[0508] Unstable terminal groups and -CF2H terminal groups can be stabilized by converting them to -CF3 terminal groups through fluorination treatment. The fluorination treatment method is not particularly limited, but examples include a method in which the polymer is exposed to a fluorine radical source that generates fluorine radicals under fluorination treatment conditions. Examples of the fluorine radical source include fluorine gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, and halogen fluorides such as IF5 and ClF3. Among these, a method in which fluorine gas is directly contacted with the FEP obtained by the production method of the present disclosure is preferred. From the viewpoint of reaction control, the contact is preferably carried out using diluted fluorine gas having a fluorine gas concentration of 10 to 50 mass%. The diluted fluorine gas can be obtained by diluting fluorine gas with an inert gas such as nitrogen gas or argon gas. The fluorine gas treatment can be carried out at a temperature of, for example, 100 to 250°C. The treatment temperature is not limited to the above range and can be appropriately set depending on the circumstances. The fluorine gas treatment is preferably carried out by continuously or intermittently supplying diluted fluorine gas into a reactor. This fluorination treatment may be carried out on a dry powder after polymerization or on melt-extruded pellets.

[0509] The FEP obtained by the manufacturing method of the present disclosure has good moldability and is less likely to produce molding defects, and also has good heat resistance, chemical resistance, solvent resistance, insulating properties, electrical properties, etc.

[0510] The method for producing the above-mentioned FEP powder is a method for obtaining powder by drying and pulverizing the FEP obtained by the above-mentioned production method of the present disclosure.

[0511] The powder may be fluorinated. The method for producing the fluorinated powder is a method for obtaining the fluorinated powder by supplying fluorine gas to the powder obtained by the method for producing the powder described above to fluorinate the powder.

[0512] The method for producing FEP pellets is a method for obtaining pellets by pelletizing the FEP obtained by the production method of the present disclosure described above.

[0513] The pellets may be fluorinated. The method for producing fluorinated pellets is a method for obtaining fluorinated pellets by supplying fluorine gas to the pellets obtained by the above-described method for producing pellets, thereby fluorinating the pellets.

[0514] Therefore, this FEP can be used to produce various molded products such as covering materials for electric wires, foamed electric wires, cables, wires, etc., as well as tubes, films, sheets, filaments, etc.

[0515] (2) In the production method of the present disclosure, the polymerization of TFE / perfluoro(alkyl vinyl ether) copolymers such as PFA and MFA and TFE / perfluoro(alkyl allyl ether) copolymers is preferably carried out at a polymerization temperature of 10 to 100°C and a polymerization pressure of 0.3 to 6.0 MPaG.

[0516] The preferred monomer composition (mol %) of the TFE / perfluoro(alkyl vinyl ether) copolymer is TFE:perfluoro(alkyl vinyl ether)=(90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoro(alkyl vinyl ether) is represented by the formula: CF2=CFORf 4 (In the formula, Rf 4 It is preferable to use one represented by a perfluoroalkyl group having 1 to 6 carbon atoms.

[0517] In addition to TFE and perfluoro(alkyl vinyl ether), other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, perfluoro(alkyl vinyl ether), and other monomers as a TFE / perfluoro(alkyl vinyl ether) copolymer. Examples of the other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and perfluoro(alkyl vinyl ether)) and fluorine-free monomers. One or more types of other monomers may be used. The content of the other monomer units in the TFE / perfluoro(alkyl vinyl ether) copolymer may be 0.1 to 2% by mass based on the total monomer units.

[0518] The preferred monomer composition (mol %) of the TFE / perfluoro(alkyl allyl ether) copolymer is TFE:perfluoro(alkyl allyl ether)=(90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoro(alkyl allyl ether) is a compound represented by the formula: CF2=CFCF2ORf 4 (In the formula, Rf 4 It is preferable to use one represented by a perfluoroalkyl group having 1 to 6 carbon atoms.

[0519] In addition to TFE and perfluoro(alkyl allyl ether), other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, perfluoro(alkyl allyl ether), and other monomers as a TFE / perfluoro(alkyl allyl ether) copolymer. Examples of the other monomers include the above-mentioned fluorine-containing monomers (excluding TFE and perfluoro(alkyl allyl ether)) and fluorine-free monomers. One or more types of other monomers may be used. The content of the other monomer units in the TFE / perfluoro(alkyl allyl ether) copolymer may be 0.1 to 2% by mass based on the total monomer units.

[0520] In the polymerization of the above TFE / perfluoro(alkyl vinyl ether) copolymer and TFE / perfluoro(alkyl allyl ether) copolymer, polymer (1) can be used within the range of use in the production method of the present disclosure, but it is usually preferable to add it in an amount of 0.0001 to 10 mass % relative to 100 mass % of the aqueous medium.

[0521] In the polymerization of the above TFE / perfluoro(alkyl vinyl ether) copolymer and TFE / perfluoro(alkyl allyl ether) copolymer, it is preferable to use cyclohexane, methanol, ethanol, propanol, propane, butane, pentane, hexane, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, methane, ethane, or the like as a chain transfer agent, and it is preferable to use ammonium carbonate, disodium hydrogen phosphate, or the like as a pH buffer.

[0522] The aqueous dispersions of TFE / perfluoro(alkyl vinyl ether) copolymers such as PFA and MFA and TFE / perfluoro(alkyl allyl ether) copolymers obtained by the production method of the present disclosure may be subjected to post-treatment such as concentration as necessary, dried, powdered, and then melt-extruded to form pellets. The aqueous medium in the aqueous dispersion may contain additives such as a nonionic surfactant as necessary, and may also contain a water-soluble organic solvent such as a water-soluble alcohol, or may not contain a water-soluble organic solvent.

[0523] Furthermore, melt extrusion can be carried out by appropriately setting extrusion conditions as long as the extrusion conditions are generally such that pelletization is possible.

[0524] The copolymer is preferably treated with fluorine gas in order to improve its heat resistance and further enhance the effect of inhibiting the permeation of chemical solutions into the molded article.

[0525] The fluorine gas treatment is carried out by contacting the copolymer with fluorine gas. However, because the reaction with fluorine is highly exothermic, it is preferable to dilute the fluorine with an inert gas such as nitrogen. The fluorine content in the fluorine gas / inert gas mixture is 1 to 100% by mass, preferably 10 to 25% by mass. The treatment temperature is 150 to 250°C, preferably 200 to 250°C, and the fluorine gas treatment time is 3 to 16 hours, preferably 4 to 12 hours. The gas pressure for the fluorine gas treatment ranges from 1 to 10 atmospheres, but atmospheric pressure is preferably used. When using a reactor at atmospheric pressure, the fluorine gas / inert gas mixture can be continuously passed through the reactor. As a result, the unstable terminals of the copolymer are converted to -CF3 terminals, making the copolymer thermally stable.

[0526] As a molding method for the copolymer and its composition, molding methods such as compression molding, transfer molding, extrusion molding, injection molding, and blow molding can be applied, as with conventional PFA.

[0527] Desired molded products can be obtained by such molding methods, and examples of molded products include sheets, films, packing, round bars, square bars, pipes, tubes, round tanks, square tanks, tanks, wafer carriers, wafer boxes, beakers, filter housings, flow meters, pumps, valves, cocks, connectors, nuts, electric wires, and heat-resistant electric wires.

[0528] Among these, it can be suitably used for tubes, pipes, tanks, connectors, etc. used in various chemical reaction equipment, semiconductor manufacturing equipment, and acid or alkaline chemical supply equipment, which require impermeability to chemicals.

[0529] Furthermore, a primer composition can be obtained by adding a nonionic surfactant to an aqueous dispersion of a TFE / perfluoro(alkyl vinyl ether) copolymer such as PFA or MFA and a TFE / perfluoro(alkyl allyl ether) copolymer, and, if necessary, dissolving or dispersing polyethersulfone, polyamideimide and / or polyimide, and a metal powder in an organic solvent. This primer composition can also be used in a method for coating a metal surface with a fluororesin, which involves applying the primer composition to a metal surface, applying a melt-processable fluororesin composition onto the primer layer thus formed, and baking the melt-processable fluororesin composition layer together with the primer layer.

[0530] (4) The manufacturing method of the present disclosure can also be used to manufacture an electrolyte polymer precursor. In the manufacturing method of the present disclosure, the polymerization of the electrolyte polymer precursor is preferably carried out at a polymerization temperature of 10 to 100°C and a polymerization pressure of 0.1 to 2.0 MPaG. The electrolyte polymer precursor is a polymer containing -SO2X 151 , -COZ 151 or -POZ 152 Z 153 (X 151 , Z 151 , Z 152 and Z 153 The ion-exchange polymer is composed of a monomer containing a functional group represented by the formula (which will be described later), and can be converted into an ion-exchange polymer through hydrolysis treatment.

[0531] Monomers used in the electrolyte polymer precursor include: General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A 151 (In the formula, Y 151 represents a fluorine atom, a chlorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain an etheric oxygen and a -SO2F group. n represents an integer of 0 to 3. n Y 151 may be the same or different. 152represents a fluorine atom, a chlorine atom, or a -SO2F group. m represents an integer of 1 to 5. m Y 152 may be the same or different. 151 -SO2X 151 , -COZ 151 or -POZ 152 Z 153 represents X 151 are F, Cl, Br, I, -OR 151 or -NR 152 R 153 represents Z. 151 , Z 152 and Z 153 are the same or different and are -NR 154 R 155 -OR 156 Represents R 151 , R 152 , R 153 , R 154 , R 155 and R 156 are the same or different and represent H, ammonium, alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group. Examples of the fluorine-containing monomers include those represented by the formula: (I) and (II). Examples of the monomers used in the electrolyte polymer precursor include compounds containing two fluorosulfonyl groups described in WO 2007 / 013532 and perfluoromonomers having a -SOF group and a dioxolane ring described in WO 2014 / 175123. The preferred monomer composition (mol %) of the electrolyte polymer precursor is TFE:vinyl ether = (50-99):(50-1), and more preferably TFE:vinyl ether = (50-93):(50-7).

[0532] The electrolyte polymer precursor may be modified with a third monomer in an amount of 0 to 20% by mass of the total monomers. Examples of the third monomer include CTFE, vinylidene fluoride, perfluoroalkyl vinyl ether, perfluorobutenyl vinyl ether, cyclic monomers such as perfluoro-2,2-dimethyl-1,3-dioxolane and perfluoro-2-methylene-4-methyl-1,3-dioxole, and polyfunctional monomers such as divinylbenzene.

[0533] The electrolyte polymer precursor thus obtained can be formed into a membrane, for example, and then subjected to hydrolysis with an alkaline solution and treatment with a mineral acid, resulting in a polymer electrolyte membrane that can be used in fuel cells, electrolysis devices, redox flow batteries, and the like. Alternatively, an electrolyte polymer dispersion can be obtained by subjecting the electrolyte polymer precursor to hydrolysis with an alkaline solution while maintaining the dispersed state of the electrolyte polymer precursor. Subsequently, by heating to 120° C. or higher in a pressure vessel, the compound can be dissolved in, for example, a water / alcohol mixed solvent to form a solution. The solution thus obtained can be used, for example, as a binder for electrodes, or can be combined with various additives to form a cast film, which can be used, for example, as an antifouling coating film or an organic actuator.

[0534] The melt-processible fluororesin powder can be suitably used as a powder coating. When a powder coating made of the melt-processible fluororesin powder is applied to a substrate, a coating with a smooth surface can be obtained. Melt-processible fluororesin powders having an average particle size of 1 μm or more and less than 100 μm are particularly suitable as powder coatings to be used in electrostatic coating, and melt-processible fluororesin powders having an average particle size of 100 μm or more and 1000 μm or less are particularly suitable as powder coatings to be used in spin coating or spin molding.

[0535] The melt-processible fluororesin powder can be produced by drying and powdering the melt-processible fluororesin obtained by the production method of the present disclosure. The production method for producing the melt-processible fluororesin powder also constitutes part of the present disclosure.

[0536] (III) Perfluoroelastomer In the first production method of the present disclosure, a perfluoroelastomer can be produced as the fluoropolymer by polymerizing a perfluoromonomer such as TFE.

[0537] The perfluoromonomers used in the polymerization of perfluoroelastomers include: Tetrafluoroethylene (TFE), Hexafluoropropylene (HFP), General formula: CF2=CF-ORf 13 (In the formula, Rf 13 represents a perfluoroalkyl group having 1 to 8 carbon atoms; General formula: CF2=CFOCF2ORf 14 (In the formula, Rf 14 is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms), and General formula: CF2=CFO(CF2CF(Y 15 )O) m (CF2) n F (In the formula, Y 15 represents a fluorine atom or a trifluoromethyl group; m is an integer of 1 to 4; and n is an integer of 1 to 4. At least one selected from the group consisting of:

[0538] In the polymerization of perfluoromonomers, a monomer that provides a crosslinking site may be polymerized together with the perfluoromonomers.

[0539] The polymerization of the perfluoromonomer may be carried out in the presence of a polymerization initiator. The polymerization initiator is as described above. The amount of the polymerization initiator added is preferably 0.0001 to 10% by mass, more preferably 0.01 to 5% by mass, relative to 100% by mass of the perfluoromonomer. By setting the amount of the polymerization initiator added (amount present) in the polymerization to be within the above range, the polymerization reaction of the perfluoromonomer proceeds smoothly, and the perfluoroelastomer can be produced efficiently. If the amount of the polymerization initiator added is too small, a sufficient polymerization rate or a sufficient yield may not be obtained.

[0540] The polymerization of perfluoromonomers may be carried out in the presence of a pH adjuster. By carrying out the polymerization in the presence of a pH adjuster, it is possible to generate a sufficient number of perfluoroelastomer particles at a sufficient polymerization rate while further suppressing adhesion of the perfluoroelastomer to the polymerization vessel. The pH adjuster may be added before or after the start of polymerization.

[0541] Examples of pH adjusters that can be used include ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium phosphate, potassium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, and ammonium gluconate.

[0542] The perfluoroelastomer is preferably at least one selected from the group consisting of perfluoroelastomers containing TFE, such as TFE / fluoromonomer copolymers represented by general formula (160), (130) or (140) and TFE / fluoromonomer copolymers represented by general formula (160), (130) or (140) / monomer copolymers that provide cross-linking moieties.

[0543] In the case of a TFE / PMVE copolymer, the composition is preferably 45-90 / 10-55 (mol %), more preferably 55-80 / 20-45, still more preferably 55-70 / 30-45, and most preferably 56-69.5 / 30.5-44.

[0544] In the case of a copolymer of TFE / PMVE / a monomer that provides a crosslinking site, the ratio is preferably 45 to 89.9 / 10 to 54.9 / 0.01 to 4 (mol %), more preferably 55 to 77.9 / 20 to 49.9 / 0.1 to 3.5, even more preferably 55 to 69.8 / 30 to 44.8 / 0.2 to 3, and most preferably 55.3 to 69.5 / 30.3 to 44.5 / 0.2 to 2.8.

[0545] In the case of TFE / fluoromonomer copolymers having 4 to 12 carbon atoms and represented by general formula (160), (130) or (140), the ratio is preferably 50 to 90 / 10 to 50 (mol %), more preferably 60 to 88 / 12 to 40, even more preferably 65 to 85 / 15 to 35, and most preferably 66 to 84 / 16 to 34.

[0546] In the case of TFE / fluoromonomer having 4 to 12 carbon atoms represented by general formula (160), (130) or (140) / monomer copolymer providing a crosslinking site, the ratio is preferably 50 to 89.9 / 10 to 49.9 / 0.01 to 4 (mol %), more preferably 60 to 87.9 / 12 to 39.9 / 0.1 to 3.5, even more preferably 65 to 84.8 / 15 to 34.8 / 0.2 to 3, and most preferably 66 to 84.3 / 15.5 to 33.8 / 0.2 to 2.8.

[0547] If the composition is outside these ranges, the rubber elastic properties will be lost and the properties will tend to become more like those of a resin.

[0548] The perfluoroelastomer is preferably at least one selected from the group consisting of TFE / fluoromonomer copolymer represented by general formula (140) / crosslinkable moiety-providing fluoromonomer, TFE / perfluorovinyl ether copolymer represented by general formula (140), TFE / fluoromonomer copolymer represented by general formula (160), and TFE / fluoromonomer copolymer represented by general formula (160) / crosslinkable moiety-providing monomer copolymer.

[0549] Examples of the perfluoroelastomer include those described in International Publication No. 97 / 24381, Japanese Patent Publication No. 61-57324, Japanese Patent Publication No. 4-81608, and Japanese Patent Publication No. 5-13961.

[0550] The perfluoroelastomer preferably has a glass transition temperature of −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, in order to have excellent compression set properties at high temperatures. In addition, in order to have good cold resistance, the glass transition temperature is preferably 5° C. or lower, more preferably 0° C. or lower, and even more preferably −3° C. or lower.

[0551] The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (Mettler-Toledo, DSC822e) by heating 10 mg of a sample at a rate of 10°C / min, and determining the maximum value of the differential curve of the DSC curve during the second-order transition as the glass transition temperature.

[0552] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+20) at 170°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 150 or less, more preferably 120 or less, and even more preferably 110 or less.

[0553] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+20) at 140°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 180 or less, more preferably 150 or less, and even more preferably 110 or less.

[0554] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+10) at 100°C of 10 or more, more preferably 20 or more, and even more preferably 30 or more. In terms of good processability, the Mooney viscosity ML(1+10) is preferably 120 or less, more preferably 100 or less, and even more preferably 80 or less.

[0555] The Mooney viscosity can be measured using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES at 170°C, 140°C or 100°C in accordance with JIS K6300.

[0556] According to the first production method of the present disclosure, an aqueous dispersion of a perfluoroelastomer can be obtained as a fluoropolymer. The solids concentration (perfluoroelastomer content) of the resulting aqueous perfluoroelastomer dispersion is preferably 10 to 50 mass %, more preferably 15 to 40 mass %, and even more preferably 20 to 30 mass % at the time of completion of polymerization.

[0557] The solids concentration (perfluoroelastomer content) of the aqueous perfluoroelastomer dispersion can be determined by drying 1 g of the aqueous dispersion at 150°C for 60 minutes, measuring the mass of the heating residue, and calculating the ratio of the mass of the heating residue to the mass of the aqueous dispersion.

[0558] The aqueous dispersion of the perfluoroelastomer may be subjected to treatment such as coagulation or heating.

[0559] The coagulation can be carried out by adding a coagulant to the aqueous dispersion. Examples of the coagulant include acids such as hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, and trifluoroacetic acid, and preferably at least one selected from the group consisting of nitric acid and hydrochloric acid.

[0560] The coagulated perfluoroelastomer may be washed with water to remove small amounts of impurities such as buffer solutions and salts present in the perfluoroelastomer, and then the washed perfluoroelastomer may be dried at a drying temperature of preferably 40 to 200°C, more preferably 50 to 180°C, and even more preferably 70 to 150°C.

[0561] The form of the perfluoroelastomer obtained after coagulation is not particularly limited, but may be gum, crumb, powder, pellets, etc., with gum or crumb being preferred. Gum is a small granular mass of perfluoroelastomer, and crumb is an amorphous mass formed when perfluoroelastomer cannot maintain its granular shape as a gum at room temperature and instead fuses together. Gum or crumb is preferably obtained by coagulating and drying the aqueous dispersion obtained by the production method of the present disclosure using a conventionally known method.

[0562] In the production method of the present disclosure, the perfluoroelastomer in the aqueous dispersion may be coagulated using a metal-free acid, and the coagulated perfluoroelastomer may be washed with a liquid medium having a reduced metal element content. Furthermore, in the production method of the present disclosure, the washed perfluoroelastomer may be dried. This production method can produce a perfluoroelastomer having a metal content of 10 ppm by mass or less. The liquid medium is preferably water, and more preferably ultrapure water. The metal content of the liquid medium is preferably 2 ppm by mass or less, more preferably 1 ppm by mass or less, and even more preferably 0.5 ppm by mass or less. The production method of the present disclosure may also use the production method described in International Publication No. 2018 / 225586. This production method can produce a perfluoroelastomer with a reduced metal content, making it suitable for use in semiconductor manufacturing equipment components.

[0563] Polymer (1), decomposition products and by-products of polymer (1), and residual monomers produced as by-products of polymer (1) may be recovered and purified from the wastewater generated by the coagulation or washing and / or the off-gas generated during drying, thereby allowing the polymer (1), decomposition products and by-products of polymer (1), and residual monomers produced as by-products of polymer (1). The recovery and purification methods are not particularly limited, and can be carried out by known methods. For example, the method described in JP-A-2011-520020 can be used.

[0564] In the production method of the present disclosure, coagulation, washing, drying, etc. of the fluoropolymer generates wastewater and off-gas. The polymer (1), decomposition products, by-products, and residual monomers produced as by-products of the polymer (1), may be recovered and purified from the wastewater generated by the coagulation or washing and / or the off-gas generated by drying, thereby allowing the polymer (1), decomposition products, by-products, and residual monomers produced as by-products of the polymer (1), and residual monomers may be reused. The recovery and purification methods are not particularly limited, and can be carried out by known methods. For example, the methods described in JP-A-2011-520020 and the methods described in U.S. Patent Application Publication Nos. 2007 / 15937, 2007 / 25902, and 2007 / 27251 are examples. Specific examples include the following methods.

[0565] Examples of a method for recovering the polymer (1), decomposition products and by-products of the polymer (1), and residual monomers from the wastewater include contacting the wastewater with adsorbent particles such as ion exchange resin, activated carbon, silica gel, clay, and zeolite to adsorb the polymer (1), and then separating the wastewater from the adsorbent particles. Incineration of the adsorbent particles that have adsorbed the polymer (1) can prevent the release of the polymer (1) into the environment.

[0566] Alternatively, the polymer (1) or the like can be recovered by desorbing and eluting it from ion exchange resin particles that have adsorbed the polymer (1) or the like using a known method. For example, when the ion exchange resin particles are anion exchange resin particles, the polymer (1) or the like can be eluted by contacting a mineral acid with the anion exchange resin. Subsequently, when a water-soluble organic solvent is added to the resulting eluate, the mixture usually separates into two phases. The lower phase containing the polymer (1) or the like can be recovered and neutralized to recover the polymer (1) or the like. Examples of the water-soluble organic solvent include polar solvents such as alcohols, ketones, and ethers.

[0567] Other methods for recovering the polymer (1) from the ion-exchange resin particles include the use of an ammonium salt and a water-soluble organic solvent, and the use of an alcohol and, optionally, an acid. In the latter method, an ester derivative of the polymer (1) is produced, which can be easily separated from the alcohol by distillation.

[0568] If the wastewater contains fluoropolymer particles or other solids, it is preferable to remove them before contacting the wastewater with the adsorbent particles. Methods for removing the fluoropolymer particles and other solids include a method in which they are precipitated by adding an aluminum salt or the like, and then the precipitate is separated from the wastewater, or electrocoagulation. Mechanical methods, such as crossflow filtration, depth filtration, and precoat filtration, may also be used for removal. The concentration of the unagglomerated fluoropolymer in the wastewater is preferably low from the viewpoint of productivity, more preferably less than 0.4 mass %, particularly preferably less than 0.3 mass %.

[0569] One method for recovering the polymer (1) and the like from the off-gas is to use a scrubber to contact the off-gas with deionized water, an aqueous alkali solution, an organic solvent such as a glycol ether solvent, or the like to obtain a scrubber solution containing the polymer (1) and the like. When a highly concentrated aqueous alkali solution is used as the aqueous alkali solution, the scrubber solution can be recovered in a state in which the polymer (1) and the like are phase-separated, facilitating the recovery and reuse of the polymer (1) and the like. Examples of the alkali compound include alkali metal hydroxides and quaternary ammonium salts.

[0570] The scrubber solution containing the polymer (1) and the like may be concentrated using a reverse osmosis membrane or the like. The concentrated scrubber solution usually contains fluoride ions, but by adding alumina after concentration to remove the fluoride ions, it is possible to facilitate the reuse of the polymer (1) and the like. Alternatively, the scrubber solution may be brought into contact with adsorbent particles to adsorb the polymer (1) and the like, and the polymer (1) and the like may be recovered by the method described above.

[0571] The polymer (1) etc. recovered by any of the above methods can be reused for the production of fluoropolymers.

[0572] The production method of the present disclosure is a production method for PTFE in which PTFE is obtained by polymerizing TFE in an aqueous medium, wherein the PTFE is high-molecular-weight PTFE, the polymer (1) is a polymer of a monomer (1) represented by general formula (1), and the content of dimers and trimers of the monomer (1) in the polymer (1) is 1.0 mass% or less relative to the polymer (1) (hereinafter, this production method may be referred to as a second production method of the present disclosure).

[0573] The second production method of the present disclosure involves polymerizing TFE in the presence of polymer (1), and therefore can produce PTFE that is substantially free of dimers and trimers, which are the monomers that constitute polymer (1).Furthermore, the production method of the present disclosure can produce PTFE with a high molecular weight.

[0574] In the second production method of the present disclosure, as in the first production method of the present disclosure, a polymer (1) having a content of polymerization units (1) of 50 mass% or more may be used as the polymer (1), or a polymer (1) having a content of polymerization units (1) of less than 50 mass% may be used.

[0575] In the polymer (1) used in the second production method of the present disclosure, the content of the polymerized units (1) relative to all polymerized units is, in order of preference, 1.0% by mass or more, 3.0% by mass or more, 5.0% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, and 90% by mass or more. It is particularly preferable that the content of the polymerized units (1) is substantially 100% by mass, and it is most preferable that the polymer (1) consists solely of the polymerized units (1).

[0576] In the polymer (1) used in the second production method of the present disclosure, the content of polymerized units based on other monomers copolymerizable with monomer (1) is, in order of preference, 99.0% by mass or less, 97.0% by mass or less, 95.0% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, and 10% by mass or less, based on all polymerized units. It is particularly preferred that the content of polymerized units based on other monomers copolymerizable with monomer (1) is substantially 0% by mass, and it is most preferred that polymer (1) does not contain polymerized units based on other monomers.

[0577] The structure of the polymer (1) used in the second production method of the present disclosure is the same as that of the polymer (1) used in the first production method of the present disclosure, except that the content of the polymerized unit (1) can be selected from a wide range.

[0578] The second production method of the present disclosure preferably includes a step of polymerizing monomer (1) to obtain a crude composition containing a polymer of monomer (1), and a step of removing dimers and trimers of monomer (1) contained in the crude composition from the crude composition to obtain polymer (1) having a content of dimers and trimers of monomer (1) of 1.0 mass% or less, based on polymer (1).

[0579] In the second production method of the present disclosure, when a crude composition is obtained by polymerizing monomer (1) with another monomer copolymerizable with monomer (1), the obtained crude composition typically contains dimers and trimers composed of polymerization units (1) based on monomer (1) and polymerization units based on the other monomer copolymerizable with monomer (1). By removing the dimers and trimers composed of polymerization units (1) and polymerization units based on the other monomer contained in the crude composition from the crude composition, a polymer (1) in which the content of dimers and trimers composed of polymerization units (1) and polymerization units based on the other monomer is 1.0 mass% or less relative to polymer (1) may be obtained.

[0580] The polymerization of the monomer (1) can be carried out by the method described in the first production method of the present disclosure.

[0581] In the second production method of the present disclosure, the polymerization of the monomer (1) is preferably carried out in an aqueous medium substantially in the absence of a fluorine-containing surfactant (excluding the monomer (1)).

[0582] The fluorine-containing surfactant is as described above.

[0583] After the polymerization of the monomer (1), the dimer and trimer of the monomer (1) contained in the crude composition obtained by the polymerization of the monomer (1) are removed from the crude composition by the means described above.

[0584] By appropriately selecting the means for removing dimers and trimers, it is also possible to remove fractions with molecular weights of 3,000 or less, fractions with molecular weights of 2,000 or less, fractions with molecular weights of 1,500 or less, and fractions with molecular weights of 1,000 or less.

[0585] The polymerization of TFE can be carried out by the method described above. As described above, a modifying monomer may be polymerized together with TFE.

[0586] The present disclosure also relates to a composition containing polymer (1) and a fluoropolymer, wherein the fluoropolymer contains polymerization units based on a perfluoromonomer, and the content of polymerization units based on the perfluoromonomer in the fluoropolymer is 90 mol % or more based on all polymerization units of the fluoropolymer, the polymer (1) is a polymer of monomer (1) represented by general formula (1), the content of polymerization units (1) based on monomer (1) in polymer (1) is 50 mass % or more based on all polymerization units of polymer (1), and the content of dimers and trimers of monomer (1) in polymer (1) is 1.0 mass % or less based on polymer (1) (hereinafter, this composition may be referred to as the first composition of the present disclosure).

[0587] The first composition of the present disclosure can be produced by the first production method of the present disclosure.

[0588] The form of the first composition of the present disclosure is not particularly limited, and may be, for example, an aqueous dispersion, a coagulate, a dried product, a gum, a crumb, a powder, a pellet, etc. An aqueous dispersion is a dispersion system in which an aqueous medium is the dispersion medium and a fluoropolymer is the dispersoid. The aqueous medium is not particularly limited as long as it is a liquid containing water, and may contain, in addition to water, an organic solvent such as alcohol, ether, ketone, or paraffin wax.

[0589] The first composition of the present disclosure may be an aqueous fluoropolymer dispersion in which primary particles of a fluoropolymer are dispersed in an aqueous medium. The aqueous dispersion may be any of the aqueous dispersions obtained by carrying out the polymerization described above, dispersions obtained by concentrating or subjecting the aqueous dispersion to a dispersion stabilization treatment, and those obtained by dispersing a powder of a fluoropolymer in an aqueous medium in the presence of the surfactant described above. The composition of the present disclosure may also be a fluoropolymer powder. The fluoropolymer powder can be obtained, for example, by coagulating the fluoropolymer in the aqueous fluoropolymer dispersion using a known method.

[0590] The content of polymer (1) in the composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, even more preferably 0.01% by mass or more, particularly preferably 0.05% by mass or more, and most preferably 0.10% by mass or more, relative to the fluoropolymer. The content of polymer (1) in the composition is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.0% by mass or less, and most preferably 0.50% by mass or less, relative to the fluoropolymer.

[0591] The content of polymer (1) can be determined by solid-state NMR measurement. Further, WO 2014 / 099453, WO 2010 / 075497, WO 2010 / 075496, WO 2011 / 008381, WO 2009 / 055521, WO 1987 / 007619, JP 61-293476 A, WO 2010 / 075494, WO 2010 / 075359, WO 2006 / 119224, WO 2013 / 085864, WO 2012 / 082707, WO 2013 / 082708, WO 2014 / 099453, WO 2014 / 099496, WO 2014 / 099497, WO 2014 / 099496 ... Methods for measuring the content of each polymer are described in JP-A No. 2012 / 082703, WO 2012 / 082454, WO 2012 / 082451, WO 2006 / 135825, WO 2004 / 067588, WO 2009 / 068528, JP-A No. 2004-075978, JP-A No. 2001-226436, WO 1992 / 017635, WO 2014 / 069165, and JP-A No. 11-181009. The method for measuring the content of polymer (1) can be the method for measuring the content of each polymer described therein.

[0592] When the fluoropolymer is a perfluoroelastomer, the content of polymer (1) may be measured by the following method: the composition is mixed with a solvent capable of dissolving the perfluoroelastomer, deionized water is added to the resulting mixture to extract polymer (1) from the mixture, the upper phase (aqueous phase) containing polymer (1) is recovered, and the recovered upper phase is dried by heating to obtain a residue (polymer (1)). The mass of the resulting residue is measured, and the content of polymer (1) can be calculated.

[0593] As a solvent for dissolving a perfluoroelastomer, a perhalogen solvent in which all hydrogen atoms are substituted with halogen atoms is preferred, and a perfluoro solvent in which all hydrogen atoms are substituted with fluorine atoms is particularly preferred. Specific examples of perfluoro solvents include perfluoro tertiary amines such as perfluorotri-n-butylamine and perfluorotriethylamine, perfluoro-substituted tetrahydrofuran, perfluorobenzene, Fluorinert FC-77 (manufactured by 3M), and Demnum Solvent (manufactured by Daikin Industries, Ltd., main component: CF 14 ), R-318 (manufactured by Daikin Industries, Ltd., main component: C4F8Cl2), Fluorinert FC-43 (manufactured by 3M, main component: (C4F9)3N), etc., but among these, perfluorotri-n-butylamine and Fluorinert FC-77 are preferred from the viewpoint of ease of handling.

[0594] In addition to the above-mentioned solvents, various fluorine-based solvents are preferably used as the solvent for dissolving the perfluoroelastomer. Specific examples include perfluoroalkanes, HFCs (hydrofluorocarbons), HFEs (hydrofluoroethers), and HCFCs (hydrochlorofluorocarbons). Specific examples include HFE-7100 (manufactured by 3M, main component: C4F9OCH3), HFE-7200 (manufactured by 3M, main component: C4F9OC2H5), and Vertrel XF (manufactured by Chemours, main component: C5H2F 10 ) can be mentioned.

[0595] In the first composition of the present disclosure, the content of dimers and trimers of monomer (1) in polymer (1) is preferably 1.0% by mass or less, relative to polymer (1). The content of dimers and trimers in the first composition of the present disclosure is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, relative to polymer (1).

[0596] In the first composition of the present disclosure, the content of dimers and trimers composed of polymerization units (1) based on monomer (1) and polymerization units based on other monomers copolymerizable with monomer (1) in polymer (1) is preferably 1.0 mass% or less, relative to polymer (1). The content of dimers and trimers composed of polymerization units (1) and polymerization units based on other monomers in the first composition of the present disclosure is preferably 0.1 mass% or less, more preferably 0.01 mass% or less, even more preferably 0.001 mass% or less, and particularly preferably 0.0001 mass% or less, relative to polymer (1).

[0597] The dimer and trimer contents in the first composition of the present disclosure can be measured by the same method as for the dimer and trimer contents in polymer (1).

[0598] The polymer (1) in the first composition of the present disclosure may contain or may not contain a fraction having a molecular weight of 3000 or less, a fraction having a molecular weight of 2000 or less, a fraction having a molecular weight of 1500 or less, or a fraction having a molecular weight of 1000 or less, in the same content as the polymer (1) used in the first production method of the present disclosure.

[0599] The polymer (1) in the first composition of the present disclosure may have the same structure as the polymer (1) used in the first production method of the present disclosure.

[0600] The fluoropolymer in the first composition of the present disclosure contains polymerized units based on perfluoromonomer, and the content of polymerized units based on perfluoromonomer in the fluoropolymer is 90 mol% or more based on the total polymerized units of the fluoropolymer. The fluoropolymer in the first composition of the present disclosure may have the same structure as the fluoropolymer obtained by the first manufacturing method of the present disclosure. The fluoropolymer in the first composition of the present disclosure may be, for example, PTFE or a perfluoroelastomer. The PTFE may be a TFE homopolymer containing only TFE units, or may be a modified PTFE containing TFE units and modified monomer units.

[0601] When the fluoropolymer is PTFE or a perfluoroelastomer, the first composition of the present disclosure preferably contains little or no metal components. The metal content in the composition is preferably 10 mass ppm or less, more preferably 7 mass ppm or less, even more preferably 5 mass ppm or less, and particularly preferably 1 mass ppm or less. The composition with a reduced metal content may be a coagulated product or a dried product. The coagulated product is obtained by coagulating the fluoropolymer in an aqueous dispersion, and the dried product is obtained by drying the coagulated product.

[0602] The metal content in the composition can be determined by placing the composition in a platinum crucible, washing with dilute nitric acid and ultrapure water, ashing with a burner and an electric furnace, decomposing by heating with sulfuric acid and hydrofluoric acid, and dissolving in dilute nitric acid to prepare a measurement solution, measuring the content of 30 types of metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, Bi, Th) in the obtained measurement solution using an ICP mass spectrometer (Agilent Technologies, Agilent 8800), and adding up the measured values.

[0603] When the fluoropolymer is a perfluoroelastomer, the first composition of the present disclosure may further contain a curing agent (crosslinking agent), a filler, etc. Examples of the curing agent include polyol, polyamine, organic peroxide, organotin, bis(aminophenol)tetraamine, bis(thioaminophenol), etc.

[0604] The perfluoroelastomer composition of the present disclosure preferably contains at least one selected from the group consisting of inorganic nitrides, organotin compounds, ammonia-generating compounds, and crosslinking agents.

[0605] Examples of the crosslinking agent include crosslinking agents used in peroxide crosslinking, polyol crosslinking, polyamine crosslinking, triazine crosslinking, oxazole crosslinking, imidazole crosslinking, and thiazole crosslinking.

[0606] As the crosslinking agent, 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane (AFTA-Ph) is preferred in terms of heat resistance, steam resistance, amine resistance, and good crosslinking properties.

[0607] The content of the crosslinking agent is preferably 0.05 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the perfluoroelastomer.

[0608] Examples of fillers include organic fillers made of engineering plastics such as polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyoxybenzoate, and polytetrafluoroethylene powder; metal oxide fillers such as aluminum oxide, silicon oxide, yttrium oxide, and titanium oxide; metal carbide fillers such as silicon carbide and aluminum carbide, and metal nitride fillers such as silicon nitride and aluminum nitride; and inorganic fillers such as aluminum fluoride, carbon fluoride, barium sulfate, carbon black, silica, clay, and talc.

[0609] The content of the filler is preferably 0.5 to 100 parts by mass, more preferably 5 to 50 parts by mass, based on 100 parts by mass of the perfluoroelastomer.

[0610] In particular, in fields where high purity and non-staining properties are not required, ordinary additives that are compounded in perfluoroelastomers, such as processing aids, plasticizers, colorants, etc., may be compounded as needed, and one or more commonly used crosslinking agents or crosslinking aids different from those mentioned above may also be compounded.

[0611] The present disclosure also relates to a composition containing polymer (1) and PTFE, wherein the PTFE is high-molecular-weight PTFE, the polymer (1) is a polymer of monomer (1) represented by general formula (1), and the content of dimers and trimers of monomer (1) in polymer (1) is 1.0 mass% or less relative to polymer (1) (hereinafter, this composition may be referred to as the second composition of the present disclosure).

[0612] The second composition of the present disclosure can be produced by the second production method of the present disclosure.

[0613] The second composition of the present disclosure may be a PTFE aqueous dispersion in which PTFE primary particles are dispersed in an aqueous medium. The aqueous dispersion may be any of the aqueous dispersions obtained by carrying out the polymerization described above, dispersions obtained by concentrating or subjecting the aqueous dispersion to a dispersion stabilization treatment, and dispersions in which a powder of PTFE is dispersed in an aqueous medium in the presence of the surfactant described above. The composition of the present disclosure may also be a PTFE powder. The PTFE powder can be obtained, for example, by coagulating PTFE in the PTFE aqueous dispersion using a known method.

[0614] The content of polymer (1) in the composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, even more preferably 0.01% by mass or more, particularly preferably 0.05% by mass or more, and most preferably 0.10% by mass or more, relative to PTFE. The content of polymer (1) in the composition is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.0% by mass or less, and most preferably 0.50% by mass or less, relative to PTFE.

[0615] The content of polymer (1) can be determined by solid-state NMR measurement. Further, WO 2014 / 099453, WO 2010 / 075497, WO 2010 / 075496, WO 2011 / 008381, WO 2009 / 055521, WO 1987 / 007619, JP 61-293476 A, WO 2010 / 075494, WO 2010 / 075359, WO 2006 / 119224, WO 2013 / 085864, WO 2012 / 082707, WO 2013 / 082708, WO 2014 / 099453, WO 2014 / 099496, WO 2014 / 099497, WO 2014 / 099496 ... Methods for measuring the content of each polymer are described in JP-A No. 2012 / 082703, WO 2012 / 082454, WO 2012 / 082451, WO 2006 / 135825, WO 2004 / 067588, WO 2009 / 068528, JP-A No. 2004-075978, JP-A No. 2001-226436, WO 1992 / 017635, WO 2014 / 069165, and JP-A No. 11-181009. The method for measuring the content of polymer (1) can be the method for measuring the content of each polymer described therein.

[0616] In the second composition of the present disclosure, the content of dimers and trimers of monomer (1) in polymer (1) is preferably 1.0% by mass or less, relative to polymer (1). The content of dimers and trimers in the second composition of the present disclosure is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, relative to polymer (1).

[0617] In the second composition of the present disclosure, the content of dimers and trimers composed of polymerization units (1) based on monomer (1) and polymerization units based on other monomers copolymerizable with monomer (1) in polymer (1) is preferably 1.0 mass% or less, relative to polymer (1). The content of dimers and trimers composed of polymerization units (1) and polymerization units based on other monomers in the second composition of the present disclosure is preferably 0.1 mass% or less, more preferably 0.01 mass% or less, even more preferably 0.001 mass% or less, and particularly preferably 0.0001 mass% or less, relative to polymer (1).

[0618] The dimer and trimer contents in the second composition of the present disclosure can be measured by the same method as for the dimer and trimer contents in polymer (1).

[0619] The polymer (1) in the second composition of the present disclosure may contain a fraction having a molecular weight of 3000 or less, a fraction having a molecular weight of 2000 or less, a fraction having a molecular weight of 1500 or less, or a fraction having a molecular weight of 1000 or less, in the same content as the polymer (1) used in the second production method of the present disclosure.

[0620] The polymer (1) in the second composition of the present disclosure may have the same structure as the polymer (1) used in the second production method of the present disclosure.

[0621] The PTFE in the second composition of the present disclosure may have the same structure as the PTFE (high molecular weight PTFE) obtained by the second production method of the present disclosure. The PTFE may be a TFE homopolymer containing only TFE units, or may be a modified PTFE containing TFE units and modified monomer units.

[0622] In the first composition and the second composition of the present disclosure, the modified PTFE preferably has a content of polymerized units based on a modified monomer (hereinafter also referred to as "modified monomer units") in the range of 0.00001 to 1% by mass relative to the total polymerized units of PTFE. The lower limit of the content of the modified monomer units is more preferably 0.0001% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limits of the content of the modified monomer units are, in order of preference, 0.80% by mass, 0.70% by mass, 0.50% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, and 0.05% by mass. In the present disclosure, the modified monomer units refer to a portion of the molecular structure of PTFE that is derived from the modified monomer.

[0623] In the present disclosure, the content of each monomer unit constituting PTFE can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. The content of each monomer unit constituting PTFE can also be calculated from the amount of modified monomer added used in polymerization.

[0624] When the modifying monomer includes the modifying monomer (A), the content of polymerized units based on the modifying monomer (A) is preferably in the range of 0.00001 to 1.0% by mass relative to the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The preferred amounts are 0.90%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, and 0.01% by mass, in descending order of preference.

[0625] The average primary particle diameter of the primary particles of the PTFE is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 350 nm or less. Primary particles having a relatively small average primary particle diameter can be obtained by the manufacturing method of the present disclosure. Furthermore, an even smaller average primary particle diameter of the primary particles can be obtained, for example, by adding a modifying monomer to the polymerization system at the initial stage of TFE polymerization. The lower limit of the average primary particle diameter is not particularly limited, but may be, for example, 50 nm or 100 nm. From the viewpoint of molecular weight, it is preferably 100 nm or more, and more preferably 150 nm or more.

[0626] The average primary particle size of PTFE primary particles can be measured by dynamic light scattering. First, an aqueous PTFE dispersion is prepared with a polymer solids concentration adjusted to approximately 1.0% by mass. Measurements can then be performed using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and 70 cumulative measurements. For dynamic light scattering, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used, for example.

[0627] The PTFE preferably has an aspect ratio of less than 2.00. The aspect ratio is the aspect ratio of the primary particles of PTFE. The upper limit of the aspect ratio of the primary particles of PTFE is, in order of preference, 1.90 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.50 or less, 1.45 or less, 1.40 or less, 1.35 or less, 1.30 or less, 1.20 or less, and 1.10 or less. Primary particles having a relatively small aspect ratio can be obtained by the manufacturing method of the present disclosure. Furthermore, an even smaller aspect ratio of the primary particles can be obtained, for example, by adding a modifying monomer to the polymerization system at the early stage of TFE polymerization.

[0628] When measuring the aspect ratio of PTFE using an aqueous PTFE dispersion, an aqueous PTFE dispersion adjusted to a polymer solids concentration of approximately 1.0% by mass is prepared, observed with a scanning electron microscope (SEM), and images of 400 or more randomly selected particles are processed. The aspect ratio can be determined from the average ratio of their major axis to minor axis. When measuring the aspect ratio of PTFE using PTFE powder, the PTFE powder is irradiated with an electron beam, added to an aqueous solution of a fluorine-containing surfactant, and redispersed in the aqueous solution under ultrasonic irradiation to prepare an aqueous PTFE dispersion. The aspect ratio can be determined using the aqueous dispersion prepared in this manner using the method described above.

[0629] The standard specific gravity (SSG) of the PTFE is preferably 2.280 or less, more preferably 2.200 or less, even more preferably 2.190 or less, and even more preferably 2.180 or less. Preferably, it is 2.130 or more. The SSG is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895-89.

[0630] The PTFE may have a thermal instability index (TII) of 20 or more. The thermal instability index (TII) of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using polymer (1). The TII is preferably 25 or more, more preferably 30 or more, and even more preferably 35 or more. It is particularly preferably 40 or more. The TII is measured in accordance with ASTM D 4895-89.

[0631] The 0.1% mass loss temperature of PTFE may be 400° C. or lower. The 0.1% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using polymer (1).

[0632] The 0.1% mass loss temperature can be measured by precisely weighing out approximately 10 mg of PTFE powder that has not been heated to temperatures above 300°C, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer).The 0.1% mass loss temperature can be determined as the temperature at which the mass has decreased by 0.1% by mass when the aluminum pan is heated in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C / min.

[0633] The 1.0% mass loss temperature of PTFE may be 492° C. or lower. The 1.0% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using polymer (1).

[0634] The 1.0% mass loss temperature can be measured by precisely weighing out approximately 10 mg of PTFE powder that has not been heated to temperatures above 300°C, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer). The 1.0% mass loss temperature can be determined as the temperature at which the mass has decreased by 1.0% by mass when the aluminum pan is heated in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C / min.

[0635] The peak temperature of PTFE is preferably 347° C. or lower, more preferably 346° C. or lower, and even more preferably 345° C. or lower. The lower limit of the peak temperature of PTFE may be 333° C. or higher, or 335° C. or higher.

[0636] The peak temperature of PTFE can be measured using a TG / DTA (thermogravimetric / differential thermal analyzer) by precisely weighing out approximately 10 mg of PTFE powder that has not been heated to temperatures above 300°C, placing it in a dedicated aluminum pan, and measuring it. The peak temperature can be identified as the temperature corresponding to the maximum value that appears on the differential thermal (DTA) curve obtained by using a TG / DTA (thermogravimetric / differential thermal analyzer) to heat PTFE that has not been heated to temperatures above 300°C at a rate of 10°C / min.

[0637] In one embodiment of the first composition and the second composition of the present disclosure, a fluorine-containing surfactant is contained. The composition containing a fluorine-containing surfactant has the advantage that it can be produced stably with high productivity using the fluorine-containing surfactant.

[0638] In one embodiment of the first composition and the second composition of the present disclosure, the composition is substantially free of a fluorine-containing surfactant. A composition substantially free of a fluorine-containing surfactant must be produced by polymerizing a perfluoromonomer such as TFE without using a fluorine-containing surfactant, but the production method of the present disclosure using polymer (1) makes it possible to produce such a composition.

[0639] In the present disclosure, "substantially free of fluorine-containing surfactant" means that the content of fluorine-containing surfactant in the composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, still more preferably 1 ppb by mass or less, and particularly preferably below the detection limit of fluorine-containing surfactant when measured by liquid chromatography-mass spectrometry (LC / MS).

[0640] The content of the fluorine-containing surfactant can be determined by a known method, for example, by LC / MS analysis. First, methanol is added to the composition to perform extraction, and the resulting extract is analyzed by LC / MS. To further increase the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. Molecular weight information is extracted from the obtained LC / MS spectrum and confirmed to match the structural formula of the candidate fluorine-containing surfactant. Then, aqueous solutions containing five or more levels of the identified fluorine-containing surfactant are prepared, and LC / MS analysis is performed on the aqueous solutions containing each level. The relationship between the content and the area corresponding to that content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing surfactant in the extract can be converted into the content of the fluorine-containing surfactant.

[0641] The first composition of the present disclosure and the second composition of the present disclosure can be suitably used for the above-mentioned applications.

[0642] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0643] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0644] The values ​​in the examples were measured by the following methods.

[0645] <Oxygen concentration in the reactor> The gas coming out of the exhaust gas line of the reactor under N2 flow was measured and analyzed using a low-concentration oxygen analyzer (product name "PS-820-L", manufactured by Iijima Electronics Co., Ltd.) to determine the oxygen concentration during the reaction.

[0646] <Method for measuring weight average molecular weight (Mw), number average molecular weight (Mn), and content of fractions with molecular weights of 3000 or less> The Mw and Mn of the polymers (polymers K, L, etc.) were determined by gel permeation chromatography (GPC) using an Agilent Technologies 1260 Infinity II column and a Tosoh column (TSKgel G3000PW). XL and TSG gel GMPW XLTwo connected columns (one column) were used, and a mixed solvent of Tris buffer and acetonitrile (Tris buffer:acetonitrile = 8:2 (v / v)) was run at a flow rate of 0.5 ml / min for measurement. The molecular weight was calculated using monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) as standards.

[0647] <Alternating rate> polymer 19 F-NMR measurement was performed and the "OCF2 * The total integrals of the two peaks (the peak appearing between -75 ppm and -80 ppm and the peak appearing between -80 ppm and -84 ppm) derived from the " were calculated according to the following formula: Alternating rate (%)≧(b×2) / (a+b)×100 a: Total integral value of peaks in the -75 ppm to -80 ppm area b: Total integral value of peaks in the -80 ppm to -84 ppm area

[0648] The alternating ratio calculated above is the ratio of polymerized units adjacent to polymerized units based on VdF among polymerized units based on CF2=CFOCF2CF2SO3Na in the polymer. CF2=C * The carbon atoms (C * ) for VdF(C * Carbon atoms (C) in the polymerization units based on H2=CF2 * The ratio of bonded ) can be calculated using the following formula: Ratio (%)=(b×2) / (a+b)×100 CF2=C * The carbon atoms (C * ) for VdF(C * Carbon atoms (C) in the polymerization units based on H2=CF2 * ) other than carbon atoms (C ** F2=C ** The carbon atoms (C **) and VdF(CH2=C ** Carbon atoms (C) in the polymerized units based on F2 ** The ratio of bonded )) can be calculated using the following formula: Ratio (%)=(ab) / (a+b)×100

[0649] <Method for measuring the content of dimers and trimers of monomers (monomers K and L) in polymers (polymers K, L, etc.)> (1) Extraction from aqueous solution The solid content of the polymer aqueous solution was measured, and an amount of the aqueous solution equivalent to 0.2 g of polymer solid content was weighed. Then, water and methanol were added to the aqueous solution so that the volume ratio of water to methanol was 50 / 50 (volume %), and a mixture containi...

Claims

[Claim 1] A method for producing a fluoropolymer, comprising polymerizing a perfluoromonomer in an aqueous medium in the presence of a polymer (1) to obtain a fluoropolymer, comprising: the content of polymerized units based on the perfluoromonomer in the fluoropolymer is 90 mol% or more based on the total polymerized units of the fluoropolymer, The polymer (1) is a polymer of a monomer (1) represented by general formula (1), the polymer (1) contains polymerized units (1) based on the monomer (1) in an amount of 50 mass% or more based on the total amount of polymerized units of the polymer (1); The production method, wherein the content of dimers and trimers of the monomer (1) in the polymer (1) is 1.0 mass % or less based on the polymer (1). CF ２ =CF-O-R-(Rf-SO ３ M) ｍ (1) (wherein R is a single bond or a linking group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond or a keto group; M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; R ７ is H or an organic group; and m is an integer of 1 or greater.

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