Method for producing polytetrafluoroethylene and composition containing polytetrafluoroethylene

Abstract

To provide a production method capable of producing an aqueous dispersion of polytetrafluoroethylene that is substantially free from dimers and trimers of monomers constituting a polymer.SOLUTION: A method for producing a polytetrafluoroethylene is provided which includes polymerizing tetrafluoroethylene in an aqueous medium in the presence of a polymer (1) to obtain the polytetrafluoroethylene. The polymer (1) is a polymer of a monomer (1) represented by the general formula (1), CF2=CF(-O-Rf-A), and has a weight average molecular weight of 1.0×104 or more. The content of polymerization units (1) based on the monomer (1) is 40 mol% or more based on all polymerization units constituting the polymer (1), and the content of dimers and trimers of the monomer (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 polytetrafluoroethylene and compositions containing polytetrafluoroethylene. [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 multifunctional dispersant [dispersant (D)], and the dispersant (D) is: - a backbone chain containing repeat units derived from one or more ethylenically unsaturated monomers, - said dispersant (D) has a molecular weight and a molecular weight distribution such that it is substantially free of a fraction with a molecular weight below 3000, -SO3X in an amount of at least 1.75 meq / g based on the weight of the dispersant (D); a , -PO3X a , and -COOX a (X a is H, an ammonium group, or a monovalent metal; A process is described in which the dispersant (D) is used in an amount of 0.01% and 5.00% by weight based on the total weight of the aqueous medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-510737 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a production method capable of producing an aqueous dispersion of polytetrafluoroethylene that is substantially free of dimers and trimers, which are monomers that constitute the polymer used in the polymerization of polytetrafluoroethylene. [Means for solving the problem]

[0005] According to the present disclosure, there is provided a method for producing polytetrafluoroethylene, comprising polymerizing tetrafluoroethylene in an aqueous medium in the presence of a polymer (1), to obtain polytetrafluoroethylene, the polymer (1) being a polymer of a monomer (1) represented by general formula (1) and having a weight average molecular weight of 1.0×10 4 The production method is as described above, in which the content of polymerization units (1) based on monomer (1) is 40 mol % or more based on all polymerization units constituting polymer (1), and the content of dimers and trimers of monomer (1) is 1.0 mass % or less based on polymer (1). CF2=CF(-O-Rf-A) (1) (In the formula, 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. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M 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.

[0006] In the production method of the present disclosure, the weight average molecular weight of the polymer (1) is 1.4 × 10 4 More preferably, it is equal to or greater than this. In the production method of the present disclosure, A is preferably -COOM. In the production method of the present disclosure, it is preferable to further polymerize the modifying monomer. In the production method of the present disclosure, it is preferable to obtain a crude composition containing a polymer of monomer (1) by polymerizing monomer (1), and to obtain polymer (1) having a content of dimer and trimer of monomer (1) of 1.0 mass% or less, based on polymer (1), by removing dimer and trimer of monomer (1) contained in the crude composition from the crude composition.

[0007] According to the present disclosure, there is provided a polymer (1) comprising polytetrafluoroethylene having a primary particle aspect ratio of less than 2.00 and a monomer (1) represented by general formula (1), the weight average molecular weight of the polymer (1) being 1.0×10 4 The composition is as described above, and the content of polymerized units (1) based on the monomer (1) is 40 mol % or more based on all polymerized units constituting the polymer (1). CF2=CF(-O-Rf-A) (1) (In the formula, 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. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M 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.

[0008] In the composition of the present disclosure, the weight average molecular weight of the polymer (1) is 1.4 × 10 4 More preferably, it is equal to or greater than this. In the compositions of the present disclosure, it is preferred that A is -COOM. In the composition of the present disclosure, the polytetrafluoroethylene preferably contains tetrafluoroethylene units and modified monomer units. In the composition of the present disclosure, the content of dimers and trimers of monomer (1) in polymer (1) is preferably 1.0 mass % or less, based on polymer (1).

[0009] According to the present disclosure, there is provided a polymer (2) comprising polytetrafluoroethylene having a primary particle aspect ratio of less than 2.00 and a monomer (2) represented by general formula (2), the weight average molecular weight of the polymer (2) being 1.0×10 4 The composition is provided in which the ion exchange capacity of the polymer (2) is 2.2 meq / g or more, and the content of the polymerized units (2) based on the monomer (2) is 40 mol % or more based on all the polymerized units constituting the polymer (2). CX2=CY(-O-Rf-A) (2) (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; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond or a keto group; A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M 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.

[0010] In the composition of the present disclosure, the weight average molecular weight of the polymer (2) is 1.4 × 10 4 More preferably, it is equal to or greater than this. In the compositions of the present disclosure, it is preferred that A is -COOM. In the composition of the present disclosure, the polytetrafluoroethylene preferably contains tetrafluoroethylene units and modified monomer units. In the composition of the present disclosure, the content of dimers and trimers of monomer (2) in polymer (2) is preferably 1.0 mass % or less, based on polymer (2). Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a production method capable of producing an aqueous dispersion of polytetrafluoroethylene that is substantially free of dimers and trimers, which are monomers that constitute the polymer used in the polymerization of polytetrafluoroethylene. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0013] In the present disclosure, melt processability means that the polymer can be melted and processed using conventional processing equipment such as an extruder, an injection molding machine, etc. Therefore, a melt processable fluororesin usually has a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0014] In the present disclosure, the polytetrafluoroethylene is preferably a fluoropolymer having a content of tetrafluoroethylene units relative to all polymerized units of 99 mol % or more.

[0015] In the present disclosure, the content of each monomer constituting polytetrafluoroethylene can be calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0016] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing a hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group which may have 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 which may have 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 is independently an alkyl group which may have 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 which may have one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents, Rb is independently H or an alkyl group which may have one or more substituents. Includes: The organic group is preferably an alkyl group which may have one or more substituents.

[0017] In the present disclosure, a "substituent" means 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 sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino These include an aromatic amino group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, and a diaromatic oxyphosphinyl group.

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

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

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

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

[0022] The 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 an acylamino group having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

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

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

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

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

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

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

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

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

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

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

[0033] The aliphatic thio group may be saturated or unsaturated and is an alkylthio group 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, or a t-butylthio group.

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

[0035] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (eg, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0036] In this disclosure, the term "at least 1" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

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

[0038] The production method of the present disclosure is a PTFE production method in which polytetrafluoroethylene (PTFE) is obtained by polymerizing tetrafluoroethylene (TFE) in an aqueous medium in the presence of polymer (1) (hereinafter, may be referred to as the first production method of the present disclosure).

[0039] <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) and has a weight average molecular weight of 1.0 × 10 4 or more, the content of polymerization units (1) based on monomer (1) is 40 mol % or more based on all polymerization units constituting polymer (1), and the content of dimers and trimers of monomer (1) is 1.0 mass % or less based on polymer (1).

[0040] The monomer (1) is represented by the following general formula (1). CF2=CF(-O-Rf-A) (1) (In the formula, 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. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M 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.

[0041] The 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 monomers that constitute polymer (1). Furthermore, the production method of the present disclosure can produce primary particles of PTFE with a small aspect ratio.

[0042] The polymer (1) may be a homopolymer of the monomer (1) represented by the general formula (1) or a copolymer with other monomers.

[0043] In general formula (1), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not include a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0044] The carbon number of the fluorine-containing alkylene group of Rf is preferably 2 or more. Also, it 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-, and CF2CF2CF2CF2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group, and more preferably an unbranched linear perfluoroalkylene group.

[0045] 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 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).

[0046] Specific examples of the fluorine-containing alkylene group having an ether bond include -CF2CF(CF3)OCF2CF2-, -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-CF2CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0047] 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.

[0048] 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.

[0049] A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M 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).

[0050] R 7 As for the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group of H or C 1-4 More preferred are alkyl groups of the formula:

[0051] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[0052] M is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, H, Na or NH4 is especially preferred, and H or NH4 is most preferred.

[0053] A is preferably -COOM or -SO3M, more preferably -COOM. The polymer (1) may be a polymer containing both the polymerization unit (1) in which A is -COOM and the polymerization unit (1) in which A is -SO3M.

[0054] 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), (1f) and (1g). CF2=CF-O-(CF2) n1 -A (1a) (In the formula, n1 represents an integer of 1 to 10, and A is the same as defined above.) CF2=CF-O-(CF2C(CF3)F)n2 -A (1b) (In the formula, n2 represents an integer of 1 to 5, and A is as defined above.) CF2=CF-O-(CFX 1 ) n3 -A (1c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and A is as defined above. CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -A (1d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and A and X 1 is the same as the above definition.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-A (1e) (In the formula, n5 represents an integer of 0 to 10; A and X 1 is the same as the above definition.) CF2=CF-O-(CF2) n7 -O-(CF2) n8 -A (1f) (In the formula, n7 represents an integer of 1 to 10, n8 represents an integer of 1 to 3, and A is as defined above.) CF2=CF[OCF2CF(CF3)] n9 O(CF2) n10 O[CF(CF3)CF2O] n11 CF(CF3)-A (1g) (In the formula, n9 represents an integer of 0 to 5, n10 represents an integer of 1 to 8, and n11 represents an integer of 0 to 5. A is as defined above.)

[0055] In the general formula (1a), n1 is preferably an integer of 5 or less, more preferably an integer of 2 or less. A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K or NH4, more preferably H or NH4.

[0056] Examples of the monomer represented by general formula (1a) include CF2=CF-O-CF2COOM, CF2=CF-O-CF2SO3M, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)3COOM), CF2=CF(O(CF2)3SO3M), and CF2=CFO(CF)4SO3M (wherein M is as defined above).

[0057] In the general formula (1b), n2 is preferably an integer of 3 or less in terms of the dispersion stability of the resulting composition. The above A is preferably -COOM or -SO3M, more preferably -COOM. The above M is preferably H, Na, K or NH4, more preferably H or NH4.

[0058] In the general formula (1c), n3 is preferably an integer of 5 or less from the viewpoint of water solubility, and A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K or NH4, more preferably H or NH4.

[0059] In general formula (1d), X 1 is preferably -CF3 in terms of dispersion stability of the composition, n4 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0060] Examples of the monomer represented by general formula (1d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0061] In the general formula (1e), n5 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, and M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0062] Examples of the monomer represented by general formula (1e) include CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0063] In the general formula (1f), n7 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, and M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0064] An example of the monomer represented by general formula (1f) is CF2=CF-O-(CF2)3-O-CF2-COOM (wherein M represents H, NH4 or an alkali metal).

[0065] In the general formula (1g), n9 is preferably an integer of 3 or less in terms of water solubility, n10 is preferably an integer of 3 or less, n11 is preferably an integer of 3 or less, A is preferably -COOM or -SO3M, and more preferably -COOM. M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0066] Examples of the monomer represented by general formula (1g) include CF2=CFO(CF2)2OCF(CF3)COOM, CF2=CFOCF2CF2OCF(CF3)CF2OCF(CF3)COOM, CF2=CFOCF2CF(CF3)OCF2CF2OCF(CF3)COOM, CF2=CF[OCF2CF(CF3)]2O(CF2)2O[CF(CF3)CF2O]CF(CF3)COOM, and CF2=CF[OCF2CF(CF3)]3O(CF2)2O[CF(CF3)CF2O]3CF(CF3)COOM (wherein M represents H, NH4 or an alkali metal).

[0067] The polymer (1) may be a homopolymer consisting of only the polymerization unit (1), or may be a copolymer containing the polymerization unit (1) and a polymerization 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 polymerization unit (1) is preferred. The polymerization unit (1) may be the same or different in each occurrence, and the polymer (1) may contain polymerization units (1) based on two or more different monomers represented by the general formula (1).

[0068] The other monomer is preferably a monomer represented by the general formula CFR=CR2 (wherein R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms). In addition, the other monomer is preferably a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms. 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 form), CHF=CHCF3 (Z form), etc. Among them, in terms of good copolymerizability, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and vinylidene fluoride (CH2=CF2) is preferred, and at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride is more preferred. Therefore, the polymerization units based on the other monomer are preferably polymerization units based on at least one selected from the group consisting of tetrafluoroethylene and vinylidene fluoride. The polymerization units based on the other monomers may be the same or different in each occurrence, and the polymer (1) may contain polymerization units based on two or more different other monomers.

[0069] When the polymer (1) contains the polymerization units (1) and the polymerization units based on other monomers copolymerizable with the monomer (1), the content of the polymerization units (1) based on the monomer (1) is preferably 40 to 60 mol %, more preferably 45 to 55 mol %, based on all the polymerization units constituting the polymer (1), and the content of the polymerization units based on other monomers is preferably 60 to 40 mol %, more preferably 55 to 45 mol %, based on all the polymerization units constituting the polymer (1). Such a constitution is particularly suitable when the polymerization units based on other monomers copolymerizable with the monomer (1) are polymerization units based on monomers represented by the general formula CFR=CR2.

[0070] When the polymer (1) contains the polymerization unit (1) and the polymerization unit based on the other monomer copolymerizable with the monomer (1), the alternation ratio between the polymerization unit (1) and the polymerization unit based on the other monomer copolymerizable with the 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 constitution is particularly suitable when the polymerization unit based on the other monomer copolymerizable with the monomer (1) is a polymerization unit based on a monomer represented by the general formula CFR=CR2.

[0071] The alternation 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.

[0072] For example, when the monomer (1) is CF2=CFOCF2CF2COOH and the other monomer is vinylidene fluoride (CH2=CF2), the alternating ratio of the polymer (1) can be calculated by the following method. 19 F-NMR measurement was performed to determine the “OCF2 * The total integral value of each of the two peaks (the peak appearing at -79 ppm to -83 ppm and the peak appearing at -83 ppm to -87 ppm) derived from " is calculated according to the following formula. Alternating rate (%)≧(b×2) / (a+b)×100 a: Total integral value of peaks in the -79ppm to -83ppm area b: Total integral value of peaks in the -83ppm to -87ppm area

[0073] The other monomers include those represented by the general formula (n1-2):

[0074] [ka]

[0075] (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 ether bonds having 2 to 100 carbon atoms).

[0076] 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)).

[0077] As the other monomer, there may be mentioned a monomer represented by the formula (n2-1):

[0078] [ka]

[0079] (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

[0080] [ka]

[0081] (wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10), etc. can be mentioned.

[0082] As the other monomer, there may be mentioned a monomer represented by the formula (n2-2): CH2=CHO-Rf 5 (n2-2) (In the formula, Rf 5 Also included are fluorine-containing vinyl ethers represented by the formula (I) (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).

[0083] Specific examples of the monomer of general formula (n2-2) include:

[0084] [ka]

[0085] (wherein e6 is an integer of 1 to 10) are preferred.

[0086] More specifically,

[0087] [ka]

[0088] etc.

[0089] Others, 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 an ether bond having 2 to 100 carbon atoms), a fluorine-containing allyl ether represented by the general formula (n2-4): CH2=CH-Rf 7 (n2-4) (In the formula, Rf 7Also included are fluorine-containing vinyl monomers represented by the formula (I) being 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.

[0090] Specific examples of the monomers represented by the general formulas (n2-3) and (n2-4) include:

[0091] [ka]

[0092] and the like monomers.

[0093] In the polymer (1), the content of the polymerization unit (1) is, in order of preference, 40 mol% or more, 50 mol% or more, more than 50%, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and 99 mol% or more based on the total polymerization units. It is particularly preferable that the content of the polymerization unit (1) is substantially 100 mol%, and it is most preferable that the polymer (1) is composed only of the polymerization unit (1). By having the content of the polymerization unit (1) within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0094] In the polymer (1), the content of polymerization units based on other monomers copolymerizable with the monomer represented by formula (1) is, in order of preference, 60 mol % or less, 50 mol % or less, less than 50%, 40 mol % or less, 30 mol % or less, 20 mol % or less, 10 mol % or less, and 1 mol % or less, based on the total polymerization units. It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer represented by formula (1) is substantially 0 mol %, and it is most preferable that the polymer (1) does not contain polymerization units based on other monomers.

[0095] The lower limit of the weight average molecular weight (Mw) of the polymer (1) is, in order of preference, 1.0×10 4 That's it, 1.4 x 10 4 That's it, 1.9 x 10 4 That's it, 1.9 x 10 4That'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 The upper limit of the weight average molecular weight (Mw) 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 When the weight average molecular weight (Mw) of the polymer (1) is within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0096] The lower limit of the number average molecular weight (Mn) of the polymer (1) is, in order of preference, 0.5×10 4 That's it, 0.7 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 it, 1.6 x 10 4 That's it, 1.8 x 10 4 The upper limit of the number average molecular weight (Mn) 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 When the number average molecular weight (Mn) of the polymer (1) is within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0097] The molecular weight distribution (Mw / Mm) of the polymer (1) is preferably 3.0 or less, more preferably 2.7 or less, even more preferably 2.4 or less, still more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.9 or less. By having the molecular weight distribution (Mw / Mm) of the polymer (1) within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0098] 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 measurement by GPC is not possible, the number average molecular weight of the 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.

[0099] The polymer (1) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and representative terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used in the formation of the polymer (1), or are generated during the chain transfer reaction.

[0100] The polymer (1) preferably 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 ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR.

[0101] 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.

[0102] The ion exchange capacity of the 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, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (1) and is calculated from the composition of the polymer (1).

[0103] 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, which side chains preferably carry ionic groups.

[0104] Polymer (1) preferably comprises an ionizable group having a pKa of less than 10, more preferably less than 7. The ionizable group of polymer (1) is preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, and phosphate.

[0105] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or to the respective acids capable of forming salts. When salts are used, preferably the salts are alkali metal or ammonium salts. A preferred ionic group is the sulfonate group.

[0106] 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, for example, by dynamic light scattering (DLS). On the other hand, the particle size of a water-insoluble polymer can be measured, for example, by dynamic light scattering (DLS).

[0107] The polymer (1) has a weight average molecular weight (Mw) of 1.4×10 4 The above polymer is a novel polymer, and can be produced by a production method (1) for producing a polymer (1) from a monomer (1) by polymerizing a monomer (1) represented by general formula (1), in which the oxygen concentration in the polymerization reaction system is maintained at 1500 ppm by volume or less.

[0108] In the production method (1), the oxygen concentration in the polymerization reaction system is 1500 ppm by volume or less. In the production method (1), the oxygen concentration in the reaction system is maintained at 1500 ppm by volume or less throughout the entire polymerization period of the monomer (1). The oxygen concentration in the reaction system is preferably 500 ppm by volume or less, more preferably 100 ppm by volume or less, and even more preferably 50 ppm by volume or less. The oxygen concentration in the reaction system is usually 0.01 ppm by volume or more.

[0109] In the production method (1), the polymerization temperature of the monomer (1) is preferably 70°C or lower, more preferably 65°C or lower, even more preferably 60°C or lower, particularly preferably 55°C or lower, even more 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 a polymer (1) having a higher molecular weight can be easily produced.

[0110] In the production method (1), the monomer (1) may be copolymerized with the other monomers described above.

[0111] In the production method (1), the polymerization pressure is usually from atmospheric pressure to 10 MPaG. The polymerization pressure is appropriately determined depending on the type of monomer used, the molecular weight of the target polymer, and the reaction rate.

[0112] In the production method (1), the polymerization time is usually from 1 to 200 hours, and may be from 5 to 100 hours.

[0113] In the production method (1), 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.

[0114] In the production method of the present disclosure, the polymerization of monomer (1) may be carried out in an aqueous medium or in the absence of an aqueous medium. Also, the polymerization of monomer (1) may be carried out in the absence of an aqueous medium and 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 monomers containing monomer (1). The polymerization of monomer (1) may be emulsion polymerization or suspension polymerization, or may be bulk polymerization.

[0115] In the production method (1), the aqueous medium is a reaction medium for polymerization, and means 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 alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less. The aqueous medium is preferably water.

[0116] In the production method (1), the polymerization of the monomer 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 in the above-mentioned polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, the polymerization can be initiated as a redox reaction by combining with a reducing agent or the like. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target polymer, and the reaction rate. When the polymerization of the 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 the 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.

[0117] As the polymerization initiator, persulfates (e.g., ammonium persulfate), disuccinic acid peroxide, diglutaric acid peroxide, and other organic peroxides 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.

[0118] As the polymerization initiator, a persulfate is particularly preferred because it can easily produce a polymer having a higher molecular weight. Examples of the persulfate include ammonium persulfate, potassium persulfate, and sodium persulfate, and ammonium persulfate is preferred.

[0119] 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 disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. In addition, 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 of perfluoro(or fluorochloro)acyl]peroxides include 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.

[0120] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously in an amount (for example, several ppm relative to water concentration) at least at which the polymerization rate does not drop significantly. The upper limit is a range in which the reaction temperature may be increased while removing heat from the equipment side by the polymerization reaction heat, and a more preferable upper limit is a range in which the polymerization reaction heat can be removed from the equipment side.

[0121] In the production method (1), 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 further 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 portions, or may be added continuously.

[0122] In the production method (1), since a polymer having a higher molecular weight can be easily produced, the total amount of the polymerization initiator used in the polymerization is preferably 0.00001 to 10% by mass relative to the aqueous medium. The total amount of the polymerization initiator used in the polymerization is preferably 0.00005% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, particularly preferably 0.01% by mass or more, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

[0123] In the production method (1), since a polymer having a higher molecular weight can be easily produced, the total amount of the polymerization initiator used in the polymerization is preferably 0.001 to 10 mol% based on the monomer. The total amount of the polymerization initiator used in the polymerization is more preferably 0.005 mol% or more, even more preferably 0.01 mol% or more, more preferably 5 mol% or less, even more preferably 2.5 mol% or less, particularly preferably 2.2 mol% or less, and most preferably 2.0 mol% or less.

[0124] In the production method (1), since a monomer having a higher molecular weight can be easily produced, the amount of monomers containing monomer (1) present at the start of polymerization is preferably 30% by mass or more relative to the amount of aqueous medium present. The amount of monomer present is more preferably 35% by mass or more, and even more preferably 40% by mass or more. The upper limit of the amount of monomer present is not particularly limited, but may be 200% by mass or less from the viewpoint of smoothly progressing the polymerization. The amount of monomer present at the start of polymerization refers to the total amount of monomer (1) and, if present, other monomers present in the reactor at the start of polymerization.

[0125] When the polymerization of the monomer (1) is carried out in the absence of an aqueous medium, the total amount of polymerization initiators such as peroxides is preferably 0.001 to 10 mol% based on the total amount of monomers (monomer mixture) containing the 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.

[0126] In the production method (1), the polymerization may be carried out in the presence of a pH adjuster, which may be added before or after the initiation of the polymerization.

[0127] 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.

[0128] In the production method (1), the polymerization of the monomer (1) can be carried out by charging the monomer (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 a polymerization initiator to start the polymerization reaction. After the start of the polymerization reaction, monomers, polymerization initiators, and other additives may be added depending on the purpose.

[0129] The polymer (1) used in the production method of the present disclosure does not substantially contain 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).

[0130] The contents of dimer and trimer 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 dimer and trimer to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0131] When the content of dimers and trimers in polymer (1) is less than 0.5% by mass based on polymer (1), it can be identified by measurement using liquid chromatography-mass spectrometry (LC / MS). Specifically, aqueous solutions with five or more levels of monomer (1) content are prepared, LC / MS analysis is performed for each content, and the relationship between the content and the area (peak integral value) for that content is plotted to create a calibration curve for monomer (1). Furthermore, from the calibration curve for monomer (1), calibration curves for the dimer and trimer of monomer (1) are created. 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 (peak integral value) of the chromatogram of the dimer and trimer of the monomer (1) can be converted into the content of the dimer and trimer.

[0132] The content of the fraction having a molecular weight of 3000 or less in the 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 0.6% or less, based on the 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 by 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.

[0133] The content of the fraction having a molecular weight of 2000 or less in the 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 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.

[0134] The content of the fraction having a molecular weight of 1500 or less in the 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 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.

[0135] The content of the fraction having a molecular weight of 1000 or less in the 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 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.

[0136] By using a polymer (1) that is substantially free of dimers and trimers during polymerization of TFE in an aqueous medium, PTFE that is substantially free of dimers and trimers of the monomer (1) can be produced.

[0137] The polymer (1) is a polymer containing a polymerization unit (1) based on the monomer (1). The polymer (1) used in the present disclosure is a polymer from which dimers (polymers containing two polymerization units (1)) and trimers (polymers containing three polymerization units (1)) have been substantially removed from the polymer (1) containing two or more polymerization units (1).

[0138] 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.

[0139] Therefore, the production method of the present disclosure preferably includes a step of obtaining a crude composition containing a polymer of monomer (1) by polymerizing monomer (1) represented by general formula (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).

[0140] The polymerization of the monomer (1) can be carried out by the method described above. By producing a crude composition by such a method, it is possible to obtain a crude composition in which the polymer (1) is dispersed or dissolved in an aqueous medium.

[0141] When the polymerization of monomer (1) is carried out in the absence of an aqueous medium, polymer (1) or a composition containing polymer (1) or the like is obtained after the completion of the polymerization. Therefore, polymer (1) or the composition is mixed with an aqueous medium, and the resulting composition containing the aqueous medium and polymer (1) can be treated by at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation.

[0142] 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)).

[0143] 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 even more preferably 1 ppb by mass or less.

[0144] The fluorine-containing surfactant will be described later in the explanation regarding the polymerization of TFE.

[0145] The crude composition thus obtained contains, as the polymer of monomer (1), a total of more than 1.0 mass% of dimers and trimers relative to the mass of the polymer of monomer (1). The content of dimers and trimers in the polymer of monomer (1) 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 polymer of monomer (1). The content 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 ​​dimers and trimers to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0146] Next, the dimer and trimer of the monomer (1) contained in the crude composition obtained by polymerization of the monomer (1) are removed from the crude composition. The means for removing the dimer and trimer is not particularly limited, but is preferably at least one means selected from the group consisting of ultrafiltration, microfiltration, dialysis membrane treatment, liquid separation, and reprecipitation, more preferably at least one means selected from the group consisting of ultrafiltration, microfiltration, liquid separation, and reprecipitation, even more preferably at least one means selected from the group consisting of ultrafiltration and liquid separation, and particularly preferably ultrafiltration.

[0147] By appropriately selecting the means for removing dimers and trimers, it is also possible to remove fractions having a molecular weight of 3000 or less, fractions having a molecular weight of 2000 or less, fractions having a molecular weight of 1500 or less, and fractions having a molecular weight of 1000 or less.

[0148] 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) occurs with a non-negligible 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.

[0149] When removing the dimer and trimer, the unreacted monomer (1) is usually removed from the crude composition at the same time. Even if the unreacted monomer (1) is incorporated into PTFE by polymerization, it does not necessarily have a negative effect on the function of PTFE, so the unreacted monomer (1) does not necessarily need to be removed. However, by removing the unreacted monomer (1) together with the dimer and trimer, the amount of monomer to be used for polymerization can be calculated without considering the presence of the unreacted monomer (1), and PTFE having the desired monomer composition can be easily produced. Even if the monomer (1) remains in the polymer (1) or the monomer (1) is newly added as a comonomer, the dimerization and trimerization of the monomer (1) hardly progresses due to the polymerization reaction in the polymerization system in which TFE occupies the majority of the monomers present in the polymerization system, and the dimer and trimer of the monomer (1) hardly remain in the obtained PTFE.

[0150] The crude composition obtained by polymerization of the monomer (1) may be a composition obtained by polymerization as-polymerized, or may be a composition obtained by diluting or concentrating the composition obtained by polymerization as-polymerized, 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.

[0151] 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 a method of adding water to the crude composition obtained by polymerization of monomer (1), a method of concentrating the crude composition obtained by polymerization of monomer (1), or the like.

[0152] The pH of the crude composition is preferably 0 to 11, more preferably 0.5 to 8.0, and further preferably 1.0 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 of the pH adjuster include phosphates, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0153] When ultrafiltration, microfiltration or dialysis membrane treatment is performed, the viscosity of the crude composition is preferably 25 mPa s or less in order to facilitate the smooth progress of the treatment. 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, by adjusting the temperature of the crude composition, or the like.

[0154] The above-mentioned ultrafiltration or microfiltration may be performed by either a cross-flow system or a dead-end system without any particular limitation, but the cross-flow system is preferred from the viewpoint of reducing clogging of the membrane.

[0155] The ultrafiltration can be carried out using an ultrafiltration membrane. For example, the ultrafiltration can be carried out using an ultrafiltration device having an ultrafiltration membrane, and centrifugal ultrafiltration, batch ultrafiltration, circulation ultrafiltration, etc. can be adopted.

[0156] 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 preferable, and 0.6×10 4 Da or more is particularly preferable, and 0.8.0×10 4 Da or more is most preferable. The molecular weight cutoff is 1.0×10 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.

[0157] 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.

[0158] The shape of the ultrafiltration membrane may be any of the conventionally known shapes, but is not limited thereto. For example, hollow fiber type, flat membrane type, spiral type, tubular type, 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 is 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 is preferably 0.05 to 2 m.

[0159] 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, polyacrylonitrile, polysulfone, or polyethersulfone, and even more preferably polyacrylonitrile, polysulfone, or polyvinylidene fluoride.

[0160] Specific examples of the ultrafiltration membrane include G-5 type, G-10 type, G-20 type, G-50 type, PW type, and HWS UF type manufactured by DESAL; 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 manufactured by KOCH; SPE1, SPE3, SPE5, SPE10, SPE30, SPV5, SPV50, and SOW30 manufactured by Synder; Microza (registered trademark) UF series manufactured by Asahi Kasei Corporation; and NTR7410 manufactured by Nitto Denko Corporation.

[0161] From the viewpoint of the efficiency of removing dimers and trimers, 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.

[0162] 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.

[0163] The above-mentioned microfiltration can be carried out using a microfiltration membrane. The microfiltration membrane usually has an average pore size of 0.05 to 1.0 μm. The microfiltration membrane preferably has an average pore size of 0.1 μm or more, more preferably 0.075 μm or more, and even more preferably 0.1 μm or more, in order to efficiently remove dimers and trimers. The average pore size 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).

[0164] The shape of the microfiltration membrane is not limited to any particular one and may be any of the conventionally known shapes, such as hollow fiber type, flat membrane type, spiral type, tubular type, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber microfiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and is 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 is preferably 0.05 to 2 m.

[0165] Examples of materials for the microfiltration membrane include cellulose-based, aromatic polyamide, polyvinyl alcohol, polysulfone, polyethersulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, metals, etc. Among these, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, or polytetrafluoroethylene is preferred, and polyacrylonitrile or polyvinylidene fluoride is particularly preferred.

[0166] 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.; Torayfil manufactured by Toray Industries, Inc.; NADIR MP005 and NADIR MV020 manufactured by Microdyne Nadia, Inc.; and X-flow manufactured by Norit.

[0167] From the viewpoint of the efficiency of removing dimers and trimers, 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.

[0168] From the viewpoint of the efficiency of removing dimers and trimers, the above-mentioned 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.

[0169] The dialysis membrane treatment is carried out using a dialysis membrane. 4 ~100×10 4 It has a molecular weight cutoff of Da. The above dialysis membrane suppresses clogging of the membrane and can efficiently remove dimers and trimers, so the molecular weight cutoff is 0.3 × 10 4 The molecular weight cutoff is preferably 0.5×10 Da or more. 4 Da or more is 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 Da or more is most preferable. The above molecular weight cutoff is 8.0 × 10 4 It may be more than Da. From the viewpoint of the efficiency of removing dimers and trimers, the above molecular weight cutoff is set to 20×10 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, in the same manner as that for the ultrafiltration membrane.

[0170] 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-based polymer alloy.

[0171] 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.

[0172] The ultrafiltration, microfiltration or dialysis membrane treatment is preferably carried out at a temperature of 10° C. or higher. More preferably, it is 15° C. or higher, even more preferably, it is 20° C. or higher, and particularly preferably, it is 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.

[0173] 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 can be added to the crude composition intermittently or continuously.

[0174] The end point 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 about once every 1 to 24 hours of filtration time to improve the durability of the filtration membrane.

[0175] 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.

[0176] The reprecipitation can be carried out, for example, by dropping the composition into a poor solvent to precipitate a polymer, recovering the precipitated polymer, dissolving the recovered polymer in a good solvent, dropping the obtained solution into a poor solvent to precipitate the polymer again, and recovering the precipitated polymer.

[0177] By removing the dimer and trimer of the monomer (1) from a crude composition containing a polymer of the monomer (1), an aqueous solution containing the polymer (1) that is substantially free of dimer and trimer is usually obtained. The polymer (1) used in the production method of the present disclosure may be the polymer (1) contained in the obtained aqueous solution, or may be the polymer (1) obtained by separating it from the aqueous solution. The method for separating the polymer (1) from the aqueous solution is not particularly limited. For example, the polymer (1) can be separated by a method such as coagulation, washing, or drying of the polymer (1) in the aqueous solution.

[0178] An aqueous solution containing the polymer (1) can be used as the polymer (1). The preferred content of the dimer and trimer of the monomer (1) relative to the polymer (1) in the aqueous solution is as described above.

[0179] <Polymerization of Tetrafluoroethylene (TFE)> In the manufacturing method of the present disclosure, polytetrafluoroethylene (PTFE) is obtained by polymerizing tetrafluoroethylene (TFE) in an aqueous medium. The PTFE obtained by polymerization of TFE in an aqueous medium is usually obtained in the form of primary particles dispersed in an aqueous dispersion.

[0180] The polymerization can be started by adding TFE, polymer (1) and an aqueous medium to a polymerization reactor, and then adding a polymerization initiator. After the start of the polymerization, TFE, a polymerization initiator, a chain transfer agent and polymer (1) may be added depending on the purpose. During the polymerization, it is preferable to stir the contents in the polymerization reactor. During the polymerization, only TFE may be polymerized, or TFE and a modifying monomer may be polymerized.

[0181] The polymerization temperature and polymerization pressure in the above polymerization are appropriately determined depending on the type of monomer used, the desired molecular weight of PTFE, and the reaction rate.

[0182] The polymerization temperature is preferably 10 to 150°C, more preferably 30°C or higher, further preferably 50°C or higher, more preferably 120°C or lower, further preferably 100°C or lower.

[0183] The polymerization pressure is preferably 0.05 to 10 MPaG, more preferably 0.3 MPaG or more, even more preferably 0.5 MPaG or more, more preferably 5.0 MPaG or less, and even more preferably 3.0 MPaG or less. In particular, from the viewpoint of improving the yield of PTFE, the polymerization pressure is preferably 1.0 MPaG or more, more preferably 1.2 MPaG or more, even more preferably 1.5 MPaG or more, particularly preferably 1.8 MPaG or more, and most preferably 2.0 MPaG or more.

[0184] The total amount of polymer (1) added is preferably 0.0001 to 15% by mass relative to 100% by mass of the aqueous medium. A more preferred lower limit is 0.001% by mass, and a more preferred upper limit is 1% by mass. If the amount is less than 0.0001% by mass, the dispersing power may be insufficient, and if the amount is more than 15% by mass, the effect commensurate with the amount added cannot be obtained. The amount of polymer (1) added is appropriately determined depending on the type of monomer used, the molecular weight of the desired PTFE, etc.

[0185] The polymerization of TFE is carried out in an aqueous medium in the presence of the polymer (1). It is also preferable to continuously add the polymer (1) during the polymerization of TFE. The continuous addition of the polymer (1) means, for example, that the polymer (1) is added over time, without interruption or in portions, rather than all at once. By continuously adding the polymer (1), primary particles having a smaller average primary particle size and aspect ratio can be obtained.

[0186] When the polymer (1) is added continuously, the amount of the polymer (1) added is preferably 0.001 to 10% by mass relative to 100% by mass of the aqueous medium, more preferably 0.005% by mass, even more preferably 0.01% by mass, more preferably 5% by mass, and even more preferably 2% by mass.

[0187] The polymerization of TFE can be efficiently carried out by using at least one type of polymer (1). In addition, in the polymerization of TFE, two or more types of polymer (1) may be used simultaneously to produce TFE, and a surfactant may be used simultaneously as long as it is volatile or may remain in the final product.

[0188] In the production method of the present disclosure, it is also preferable to polymerize TFE and a modifying monomer. By polymerizing TFE and a modifying monomer, primary particles having an even smaller average primary particle size and aspect ratio can be obtained.

[0189] The total amount of modified monomers added during polymerization of TFE is preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more, based on the PTFE obtained. The total amount of modified monomers added during polymerization is, in order of preference, 1.0% by mass or less, 0.90% by mass or less, 0.50% by mass or less, 0.40% by mass or less, 0.30% by mass or less, 0.20% by mass or less, 0.15% by mass or less, 0.10% by mass or less, and 0.05% by mass or less, based on the PTFE obtained.

[0190] In the above polymerization, it is preferable to add a modified monomer copolymerizable with TFE before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, preferably before it reaches 5.0% by mass. The modified monomer is usually added to a reactor. By adding the modified monomer at the beginning of the polymerization, more particles can be generated during the polymerization, and primary particles having a smaller average primary particle size and aspect ratio can be obtained. The modified monomer may be added before the start of the polymerization, may be added at the same time as the start of the polymerization, or may be added during the period in which the nuclei of PTFE particles are formed after the start of the polymerization. The modified monomer may be added at least before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, and further modified monomer may be added after the concentration of PTFE exceeds 10.0% by mass. For example, the modified monomer may be added before the concentration of PTFE reaches 10.0% by mass, and the modified monomer may be added continuously even after the concentration exceeds 10.0% by mass. Alternatively, the modified monomer may be added at least once before the PTFE concentration reaches 10.0% by mass, and then added at least once more after the PTFE concentration exceeds 10.0% by mass. The method of adding the modified monomer may be to push the modified monomer into the reactor by TFE.

[0191] Before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass, preferably before it reaches 5.0% by mass, the amount of the modified monomer added is preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, and particularly preferably 0.003% by mass or more, based on the total polymerized units of the PTFE obtained, based on the total polymerized units of the PTFE obtained, in order of preference, 1.0% by mass or less, 0.90% by mass or less, 0.50% by mass or less, 0.40% by mass or less, 0.30% by mass or less, 0.20% by mass or less, 0.15% by mass or less, 0.10% by mass or less, 0.05% by mass or less.

[0192] The above-mentioned modified monomer is not particularly limited as long as it is copolymerizable with TFE, and includes fluoromonomers and non-fluoromonomers. The modified monomer used may be one type or multiple types.

[0193] The non-fluoromonomer is not particularly limited and may be represented by 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. Q2 represents a hydrogen atom, an alkyl group or a nitrile group.

[0194] 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.

[0195] 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.

[0196] The perfluorovinyl ether is not particularly limited, and may be, for example, a perfluorovinyl ether represented by the general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoro organic group). In the present disclosure, the "perfluoro organic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms. The perfluoro organic group may have an ether oxygen.

[0197] 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.

[0198] 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.

[0199] 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 is the following formula:

[0200] [ka]

[0201] (wherein m represents 0 or an integer of 1 to 4), Rf is a group represented by the following formula:

[0202] [ka]

[0203] (wherein n represents an integer of 1 to 4).

[0204] Examples of hydrogen-containing fluoroolefins include CH2=CF2, CFH=CH2, CFH=CF2, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-form), and CHF=CHCF3 (Z-form).

[0205] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0206] Examples of perfluoroallyl ethers include General formula: CF2=CF-CF2-ORf (wherein Rf represents a perfluoro organic group).

[0207] 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. As the perfluoroallyl ether, at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is preferable, at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is more preferable, and CF2=CF-CF2-O-CF2CF2CF3 is even more preferable.

[0208] A preferred example of the modifying monomer is the modifying monomer (3) having a monomer reactivity ratio of 0.1 to 8. By allowing the modifying monomer (3) to exist, primary particles having a small average primary particle size and aspect ratio can be obtained.

[0209] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant of the reaction of the growing radical with TFE by the rate constant of the reaction of the growing radical with the modified monomer when the growing radical is less than the repeating unit based on TFE. The lower this value, the higher the reactivity of the modified monomer with TFE. The monomer reactivity ratio can be calculated by the composition in the polymer produced immediately after the start of copolymerization of TFE with the modified monomer and using the Feynman-Ross equation.

[0210] The copolymerization is carried out in a 6.0L stainless steel autoclave using 3600g of deionized degassed water, 1000 mass ppm of ammonium perfluorooctanoate relative to the water, and 100g of paraffin wax at a pressure of 0.78 MPaG and a temperature of 70°C. 0.05g, 0.1g, 0.2g, 0.5g, and 1.0g of modified monomer are added to the reactor, respectively, and 0.072g of ammonium persulfate (20 mass ppm relative to water) is added, and TFE is continuously fed to maintain the polymerization pressure of 0.78 MPaG. When the amount of TFE charged reaches 1000g, stirring is stopped and the reactor is depressurized until atmospheric pressure is reached. After cooling, the paraffin wax is separated to obtain an aqueous dispersion containing the produced polymer. The aqueous dispersion is stirred to coagulate the produced polymer, and then dried at 150°C. The composition of the resulting polymer is calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0211] The modifying monomer (3) having a monomer reactivity ratio of 0.1 to 8 is preferably at least one selected from the group consisting of the modifying monomers represented by the 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) (In the formula, n is 1 or 2.)

[0212] [ka] (In the formula, X 3 and X 4 is F, Cl or a methoxy group, and Y is of formula Y1 or Y2.

[0213] [ka] (In formula Y2, Z and Z' are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0214] The content of the modified monomer (3) unit is preferably in the range of 0.00001 to 1.0% by mass based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90% by mass, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0215] The modified monomer is preferably 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 with radical polymerization and a hydrophilic group.By using the modified monomer, more particles can be generated during polymerization, and primary particles having smaller average primary particle size and aspect ratio can be obtained.In addition, an aqueous dispersion with less uncoagulated polymer can be obtained.

[0216] 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 unit, the perfluoro(alkyl vinyl ether) unit and the (perfluoroalkyl)ethylene unit is preferably in the range of 0.00001 to 1% by mass based on the total 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 limit is, in order of preference, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0217] 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)").

[0218] By making the above-mentioned modified monomer (A) exist, more particles can be generated during polymerization, and furthermore, primary particles having smaller average primary particle size and aspect ratio can be obtained, and the amount of uncoagulated polymer can be reduced.

[0219] The amount of the modified monomer (A) used is preferably more than an amount equivalent to 0.1 ppm by mass of the aqueous medium, more preferably more than 0.5 ppm by mass, even more preferably more than 1.0 ppm by mass, even more preferably 5 ppm 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 may be, for example, 5000 mass ppm. In the above production method, the modified monomer (A) may be added to the system during the reaction in order to improve the stability of the aqueous dispersion during or after the reaction.

[0220] Since the above-mentioned modifying monomer (A) is highly water-soluble, even if unreacted modifying monomer (A) remains in the aqueous dispersion, it can be easily removed in the concentration step or the coagulation and washing steps.

[0221] The above-mentioned modifying monomer (A) is incorporated into the produced polymer during the polymerization process. However, 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 is no problem of a decrease in the heat resistance of PTFE or coloration after baking.

[0222] Examples of the hydrophilic group in the modified monomer (A) include -NH2, -P(O)(OM)2, -OP(O)(OM)2, -SO3M, -OSO3M, and -COOM (in each formula, M is 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. Of these, -SO3M or -COOM is preferred as the hydrophilic group. R 7y The organic group in R is preferably an alkyl group. 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 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.

[0223] 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 represented by the following formula: CX e X g =CX f R- (In the formula, X e , Xf and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group. The linking group of R can be represented by the formula: a Preferred are -CH=CH2 and -CF=CH 2、 -CH=CF 2、 Examples of groups having unsaturated bonds include -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CF=CH2, -(C=O)-CF=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.

[0224] The modified monomer (A) has a functional group that can react by radical polymerization, so it is assumed that when used in the polymerization, it reacts with the fluorine-containing monomer at the initial stage of the polymerization reaction, and forms highly stable particles that have 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).

[0225] The above polymerization may be carried out in the presence of one type of the modifying monomer (A), or in the presence of two or more types thereof.

[0226] In the above polymerization, a compound having an unsaturated bond can be used as the modifying monomer (A).

[0227] 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, -P(O)(OM)2, -OP(O)(OM)2, -SO3M, -OSO3M, and -COOM (in each formula, M is 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. Of these, -SO3M or -COOM is preferred as the hydrophilic group. R 7y The organic group in R is preferably an alkyl group. 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4 The above metal atom is preferably 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. By using the modifying monomer (A), a larger number of particles can be generated during polymerization, and furthermore, primary particles having a smaller average primary particle size and aspect ratio can be obtained.

[0228] Above R ais a linking group. In the present disclosure, the "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 in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of esters, amides, sulfonamides, carbonyls, carbonates, urethanes, ureas, and carbamates. The linking group may not contain carbon atoms, but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0229] Above R a is preferably, for example, 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 atom 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 noncyclic. a may contain functional groups (eg, 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 having no fluorine atoms 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.

[0230] 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 the group consisting of -, -(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 be independently 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.

[0231] 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-(CH2)-, -(C=O)-O-(CF2)2-O-(CF2)-, -(C=O)-O-C6H4- and the like. 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 Preferred are -(CH2)-, -(C=O)-(CH2)2-O-(CH2)-, or -(C=O)-O-C6H4-. In the above formula, n is an integer of 1-10.

[0232] -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)-CF(CF3)-、-CF2-O-CF(CF3)-C(CF3)2-、-CF2-O-C F(CF3)CF2-CF2-、-CF2-O-CF(CF3)CF2-CF(CF3)-、-CF2-O-CF(CF3)CF2-C(CF3)2-、-CF2-O-CF(CF3)CF2-O-CF2-、-CF2-O-CF(CF3)CF2-O-CF(CF3)-、 -CF2-O-CF(CF3)CF2-OC(CF3)2-、-(C=O)-、-(C=O)-O-、-(C=O)-(CH2)-、- (C=O)-(CF2)-、-(C=O)-O-(CH2)-、-(C=O)-O-(CF2)-、-(C=O)-[(CH2)2-O] n -(CH2)-、-(C=O)-[(CF2)2-O] n -(CF2)-、-(C=O)-[(CH2)2-O] n -(CH2)-(CH2)-、-(C=O)-[(CF2)2-O] n -(CF2)-(CF2)-、-(C=O)-O[(CH2)2-O] n -(CF2)-、-(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-、-(C=O)-O[(CF2)2-O] n -(CF2)-、-(C=O)-O[(CF2)2-O] n-(CF2)-(CF2)-, -(C=O)-(CH2)2-O-(CH2)-(CH2)-, -(C=O)-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-(CH2)-, -(C=O )-O-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2-, -(C=O)-O-(CF2)2-O-(CF2)-C(CF3)2-, or -(C=O)-O-C6H4- C(CF3)2- is preferred, -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(C F3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, -(C=O)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CH2)-(CH2)-, -(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2- or -(C=O)-O-C6H4-C(CF3)2- are more preferred. In the above formula, n is an integer of 1-10.

[0233] Specific examples of the compound represented by 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.

[0234] 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.) is also preferred.

[0235] -R in general formula (4) a -(CZ 1 Z 2 ) k - may also be represented by the following formula (t1): -(C=O) h -(O) i -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 represented by 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 the formula (t2), Z 1 and Z 2 More preferably, one is F and the other is CF3.

[0236] 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. That is, in the general formula (4), i , X j , and X k All of the are F and R a is preferably a perfluoroalkylene group having 1 or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be either cyclic or noncyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0237] The 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.

[0238] The compound represented by the 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.

[0239] The compound represented by the 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).

[0240] In the general formula (4), Y 3 In one preferred embodiment, Y 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(OCF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OSO3M), etc. In the above formula, M is the same as above.

[0241] In the general formula (4), Y 3 Another preferred form is -SO3M. 3When is -SO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CH2=CH(CF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH((CF2)3SO3M), etc. In the above formula, M is the same as above.

[0242] In the general formula (4), Y 3 It is also a preferred form for Y to be -COOM. 3 is -COOM, the compound represented by the general formula (4) is, for example, 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.

[0243] In the general formula (4), Y 3 In another preferred embodiment, Y is -OP(O)(OM). 3is -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(OCF2CF 2SO2N(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.

[0244] In the general formula (4), Y 3 In another preferred embodiment, Y is -P(O)(OM)2. 3 is -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.

[0245] The compound represented by the general formula (4) includes the compound represented by the general formula (5): CX2=CY(-CZ2-O-Rf-Y 3 ) (5) (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; Z may be the same or different and is -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms. Y3 is the same as above.) A compound represented by general formula (6): CX2=CY(-O-Rf-Y 3 ) (6) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; 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 is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above. The above-mentioned fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0246] In general formula (5), X is -H or -F. Both X's 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 X's may be -H.

[0247] In formula (5), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0248] In 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 containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[0249] In the 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.

[0250] In the general formula (5), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. Also, the number 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.

[0251] 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 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.

[0252] 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 an organic group and may be the same or different. Any two of them may be bonded to each other to form a ring. R 7yThe organic group in is preferably an alkyl group. R 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 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. The above M is -H, a metal atom, or -NR 7y 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7y 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 preferable, and -COOM is more preferable.

[0253] The compound represented by the general formula (5) is preferably a compound (5a) represented by the general formula (5a). CH2=CF(-CF2-O-Rf-Y 3 ) (5a) (Wherein, Rf and Y 3 is the same as above.)

[0254] Specific examples of the compound represented by the general formula (5a) include compounds represented by the following formula:

[0255] [ka]

[0256] (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 Z3 and Z 4 are both H, then p1+q1+r1+s1 is not 0). More specifically,

[0257] [ka]

[0258] The following are preferred:

[0259] [ka]

[0260] It is preferable that:

[0261] The compound represented by the general formula (5a) is, for example, 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.

[0262] The compound represented by the general formula (5) is preferably a compound (5b) represented by the general formula (5b). CX 2 2 = CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y 3 (5b) (In the formula, each 2 are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, Y 3 is the same as the above definition.)

[0263] In the above 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 suitable 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 improves the heat resistance of the obtained molded article.

[0264] 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).

[0265] Further, examples of the compound represented by the general formula (5) include a compound represented by the general formula (5c).

[0266] CF2=CFCF2-O-Rf-Y 3 (5c) (Wherein, Rf and Y 3 is the same as above)

[0267] More specifically, [ka] etc.

[0268] In general formula (6), X is -H or -F. Both X's 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 X's may be -H.

[0269] In formula (6), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0270] In the 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.

[0271] In the general formula (6), the above 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.

[0272] 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 7y are H or an organic group 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 of R is preferably an alkyl group. 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4More 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. The above M is -H, a metal atom, or -NR 7y 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7y 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 preferable, and -COOM is more preferable.

[0273] 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) (In the formula, n1 represents an integer of 1 to 10, and Y 3 is the same as the above definition.) CF2=CF-O-(CF2C(CF3)F) n2 -Y 3 (6b) (In the formula, n2 represents an integer of 1 to 5; Y 3 is the same as the above definition.) CF2=CF-O-(CFX 1 ) n3 -Y 3 (6c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, Y 3 is the same as the above definition.) CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -Y 3 (6d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and Y3 and X 1 is the same as the above definition.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-Y 3 (6e) (In the formula, n5 represents an integer of 0 to 10, and Y 3 and X 1 is the same as the above definition.)

[0274] 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 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 improves the heat resistance of the resulting molded article.

[0275] Examples of the compound represented by the above formula (6a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), and CF2=CF(OCF2CF2CF2COOM) (wherein M is as defined above).

[0276] In the above formula (6b), n2 is preferably an integer of 3 or less from the viewpoint of the stability of the resulting aqueous dispersion, and Y 3 is preferably -COOM 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 improves the heat resistance of the resulting molded article.

[0277] In the above formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM 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.

[0278] In the above formula (6d), 1is 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 in that it provides suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0279] Examples of the compound represented by the above formula (6d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, and CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM (wherein M represents H, NH4, or an alkali metal).

[0280] In the general formula (6e), the n5 is preferably an integer of 5 or less in terms of water solubility, and the Y 3 is preferably -COOM in that it provides suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0281] An example of the compound represented by general formula (6e) is CF2=CFOCF2CF2CF2COOM (wherein M represents H, NH4 or an alkali metal).

[0282] 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.

[0283] The compound represented by general formula (7) is represented by general formula (7a): CF2=CF-(CF2) n1 -Y 3 (7a) (In the formula, 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) (In the formula, n2 represents an integer of 1 to 5; 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, where M is H, a metal atom, NR 7y 4. It is preferable that the R is 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.

[0284] 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 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 improves the heat resistance of the resulting molded article. An example of the perfluorovinyl alkyl compound represented by the above formula (7a) is CF2=CFCF2COOM (wherein M is as defined above).

[0285] In the above formula (7b), n2 is preferably an integer of 3 or less from the viewpoint of the stability of the resulting aqueous dispersion, and Y 3 is preferably -COOM 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 improves the heat resistance of the resulting molded article.

[0286] The above-mentioned modified monomer preferably includes modified monomer (A), and preferably includes 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 includes a compound represented by general formula (5a) or general formula (5c).

[0287] When the modified monomer (A) is used as the modified monomer, the content of the modified monomer (A) unit is preferably in the range of 0.00001 to 1.0 mass% based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001 mass%, more preferably 0.0005 mass%, even more preferably 0.001 mass%, and even more preferably 0.005 mass%. The upper limit is, in order of preference, 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0288] <Aqueous medium> The aqueous medium means 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.

[0289] <Polymerization initiator> The polymerization initiator is not particularly limited as long as it can generate radicals in the above polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, it can also be combined with a reducing agent or the like to initiate polymerization as a redox. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the desired PTFE, and the reaction rate.

[0290] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0291] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. In addition, 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 of perfluoro(or fluorochloro)acyl]peroxides include 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.

[0292] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, and sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, and percarbonic acid, organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide, t-butyl permaleate, t-butyl hydroperoxide, etc. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times that of the peroxide.

[0293] For example, when polymerization is carried out at a low temperature of 30° C. or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of the oxidizing agent include persulfates, organic peroxides, potassium permanganate, manganese triacetate, cerium ammonium nitrate, and bromates. Examples of the reducing agent include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of the persulfates include ammonium persulfate and potassium persulfate. Examples of the sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of the redox initiator. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate.

[0294] Examples of the redox initiator include potassium permanganate / oxalic acid, ammonium persulfate / bisulfite / iron(II) sulfate, ammonium persulfate / sulfite / iron(II) sulfate, ammonium persulfate / sulfite, ammonium persulfate / iron(II) sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, bromate / sulfite, bromate / bisulfite, and the like, with potassium permanganate / oxalic acid and ammonium persulfate / sulfite / iron(II) sulfate being preferred. When using a redox initiator, either the oxidizing agent or the reducing agent may be charged in advance into a reactor, 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 reactor and continuously add potassium permanganate thereto.

[0295] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously in an amount (for example, several ppm relative to water concentration) at least at which the polymerization rate does not drop significantly. The upper limit is a range in which the reaction temperature may be increased while removing heat from the equipment side by the polymerization reaction heat, and a more preferable upper limit is a range in which the polymerization reaction heat can be removed from the equipment side.

[0296] <Chain transfer agent> In the polymerization of TFE, a chain transfer agent may be used. As the chain transfer agent, a known one can be used, for example, methane, ethane, propane, butane, etc. of saturated hydrocarbons, chloromethane, dichloromethane, difluoroethane, etc. of halogenated hydrocarbons, methanol, ethanol, isopropanol, etc. of alcohols, hydrogen, etc., and the like, but those in a gaseous state at normal temperature and normal pressure are preferred.

[0297] 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.

[0298] <Nucleating agent> In the polymerization of TFE, a nucleating agent may be used. The amount of the nucleating agent added can be appropriately selected depending on the type of the nucleating agent. The amount of the nucleating agent added may be 5000 ppm by mass or less, preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, particularly preferably 50 ppm by mass or less, and most preferably 10 ppm by mass or less, based on the aqueous medium.

[0299] 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 PTFE formed in the aqueous medium reaches 5.0 mass %. By adding the nucleating agent at the beginning of polymerization, an aqueous dispersion having a small average primary particle size and excellent stability can be obtained.

[0300] 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 PTFE 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.

[0301] The use of a nucleating agent results in PTFE having a smaller primary particle size compared to polymerization carried out in the absence of said nucleating agent.

[0302] 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.

[0303] The nucleating agent is preferably added before or simultaneously with the addition of the polymerization initiator, but by adding it during the polymerization, the particle size distribution can also be adjusted.

[0304] 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.

[0305] The perfluoropolyether (PFPE) acid or salt thereof may have any chain structure in which oxygen atoms in the backbone of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. Also, two or more types of fluorocarbon groups may be present in the molecule. A representative structure has a repeat 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)

[0306] 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, 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 hydrogen or chlorine atoms. 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 above is at least 5. Two or more of the PFPE acids or salts thereof having an acid group at one or both termini may be used in the manufacturing method of the present disclosure. The PFPE acid or salt thereof preferably has a number average molecular weight of less than 6000 g / mol.

[0307] 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 presumed that the ppm amount of lipophilic nucleation sites present in the aqueous medium is less than the amount added. Therefore, the amount of the lipophilic nucleation sites is less than the above 40 ppm by mass, 30 ppm by mass, and 20 ppm by mass. Since the lipophilic nucleation sites are considered to exist as molecules, even a small amount of the hydrocarbon-containing surfactant can generate a large amount of lipophilic nucleation sites. Therefore, even if the hydrocarbon-containing surfactant is added to the aqueous medium at about 1 ppm by mass, a beneficial effect can be obtained. The preferred lower limit is 0.01 ppm by mass, and the more preferred lower limit is 0.1 ppm by mass.

[0308] 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.).

[0309] The hydrocarbon-containing surfactant is preferably a non-ionic surfactant (e.g., a non-ionic hydrocarbon surfactant). That is, the nucleating agent is preferably a non-ionic surfactant. The non-ionic surfactant preferably does not contain an aromatic moiety.

[0310] The nonionic surfactant may be, for example, a surfactant represented by the following general formula (i): R 3 -OA 1 -H(i) (In the formula, R 3 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms; A 1 is a polyoxyalkylene chain. R 3 R preferably has 10 to 16 carbon atoms, more preferably 12 to 16 carbon atoms. 3When the carbon number of R is 18 or less, good dispersion stability of the aqueous dispersion is easily obtained. 3 If the carbon number of R exceeds 18, the flow temperature is high and it is difficult to handle. 3 If the number of carbon atoms is less than 8, the surface tension of the aqueous dispersion becomes high, and the permeability and wettability tend to decrease.

[0311] A 1 The polyoxyalkylene chain may be composed of oxyethylene and oxypropylene. The polyoxyalkylene chain is composed of an average number of repeats of oxyethylene groups of 5 to 20 and an average number of repeats of oxypropylene groups of 0 to 2, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution, which is usually provided, or a broader or bimodal distribution, which is obtained by blending. When the average number of repeats of oxypropylene groups is more than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block shape or a random shape. From the viewpoint of viscosity and stability of the aqueous dispersion, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. 1 It is preferable that the oxypropylene group has an average of 0.5 to 1.5, since this results in good low foaming properties.

[0312] More preferably, R 3 is (R')(R'')HC-, where R' and R'' are the same or different linear, 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.

[0313] 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 10H 21 CH(CH3)CH2-O-(C2H4O) n -H, C 13 H 27 -O-(C2H4O) n -(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) n -H, HC(C5H 11 )(C7H 15 )-O-(C2H4O) n -H (wherein 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 Daiichi Kogyo Seiyaku) such as Noigen TDS-80 (trade name), the Leocol TD series (manufactured by Lion) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion), 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 Dow Chemical).

[0314] 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).

[0315] The hydrophobic group of the nonionic surfactant may be any one of an alkylphenol group, a linear alkyl group, and a branched alkyl group. For example, the polyoxyethylene alkylphenyl ether nonionic compound may be a compound represented by the following general formula (ii): R4 -C6H4-OA 2 -H (ii) (In the formula, R 4 is a linear or branched alkyl group having 4 to 12 carbon atoms; A 2 is a polyoxyalkylene chain.) Specific examples of the polyoxyethylene alkylphenyl ether nonionic compounds include Triton (registered trademark) X-100 (trade name, manufactured by Dow Chemical Company).

[0316] A 2 The polyoxyalkylene chain of may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of oxyethylene groups of 5 to 20 and an average repeat number of oxypropylene groups of 0 to 2, 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 form or random form. From the viewpoint of the viscosity and sedimentation stability of the composition, a polyoxyalkylene chain composed of an average repeat number of oxyethylene groups of 7 to 12 and an average repeat number of oxypropylene groups of 0 to 2 is preferred. In particular, A 2 It is preferable that the oxypropylene group has an average of 0.5 to 1.5, since this results in good low foaming properties.

[0317] More preferably, R 4 is a primary or secondary alkyl group, more preferably (R')(R'')HC-, where R' and R'' are the same or different linear, branched, or cyclic alkyl groups having a total of at least 5 carbon atoms, preferably 7 to 17. Preferably, at least one of R' or R'' is a branched or cyclic hydrocarbon group.

[0318] The nonionic surfactant also includes a polyol compound, specifically, those described in WO 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, saccharose, maltose, lactose, raffinose, and isomaltose.

[0319] Typically, suitable sugars 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 an oxygen atom), or a six-membered ring with five carbon atoms and one heteroatom, preferably an oxygen atom, as described above. These further contain at least two or at least three hydroxy groups (-OH groups) attached to the carbon ring atoms. Typically, the sugars are modified in that one or more of the hydrogen atoms of the hydroxy groups (and / or hydroxyalkyl groups) attached to the carbon ring atoms are replaced by a long-chain residue, such that an ether or ester bond is created between the long-chain residue and the sugar moiety. The sugar-based polyol may contain one or more sugar units. The sugar unit or units may be modified with long chain moieties as described above. Specific examples of sugar-based polyol compounds include glycosides, sugar esters, sorbitan esters, and mixtures and combinations thereof.

[0320] A preferred class of polyol compounds are the alkyl or modified alkyl glucosides. These classes of surfactants contain at least one glucose moiety. [ka] (In the formula, x represents 0, 1, 2, 3, 4, or 5; R 1 and R 2 independently represent H or a long chain unit containing at least 6 carbon atoms, with the proviso that R 1 and R 2 At least one of R is not H. 1 and R 2 Representative examples of the fatty alcohol 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. The above formula represents a specific example of an alkyl polyglucoside showing glucose in the pyranose form, however, it is understood that other sugars or the same sugar but in a different enantiomeric or diastereomeric form may be used. Alkyl glucosides can be obtained, for example, by acid-catalyzed reaction of glucose, starch, or n-butyl glucoside with fatty alcohols, which typically results in a mixture of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, Georg Thieme Verlag, 1999). 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. Alkyl glucosides are also commercially available from Cognis GmbH, Dusseldorf, Germany under the trade name GLUCOPON or DISPONIL.

[0321] Other nonionic surfactants include difunctional block copolymers supplied by BASF as their Pluronic® R series, tridecyl alcohol alkoxylates supplied by BASF as their Iconol® TDA series, hydrocarbon-containing siloxane surfactants, preferably hydrocarbon surfactants, in which the hydrocarbyl groups, which may be substituted by halogens such as fluorine, are fully substituted by hydrogen atoms, whereby these siloxane surfactants can also be considered as hydrocarbon surfactants, i.e., the monovalent substituents on the hydrocarbyl groups are hydrogen.

[0322] <Additives> In the production method of the present disclosure, in addition to the polymer (1) and other compounds having surface activity that are used as desired, additives for stabilizing each compound can be used, such as a buffering agent, a pH adjusting agent, a stabilizing assistant, and a dispersion stabilizer.

[0323] As the stabilizing aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. are preferable. The stabilizing aid may be used alone or in combination of two or more. As the stabilizing aid, paraffin wax is more preferable. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms. The melting point of the paraffin wax is usually preferably 40 to 65°C, more preferably 50 to 65°C.

[0324] The amount of the stabilizing aid used is preferably 0.1 to 12% by mass, more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing aid is sufficiently hydrophobic and completely separated from the aqueous dispersion obtained after the polymerization reaction is completed, so as not to become a contaminating component. In addition, it is preferable that the stabilizing aid is removed from the aqueous dispersion obtained by polymerization.

[0325] Examples of pH adjusters that can be used include ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, ammonium gluconate, etc. The pH can be measured using a pH meter manufactured by Orion.

[0326] The pH of the aqueous medium during polymerization of TFE may be acidic or basic, and the pH of the aqueous medium may be adjusted by adding a pH adjuster to the aqueous medium.

[0327] <Anionic hydrocarbon surfactants> In one embodiment of the polymerization of TFE, TFE is polymerized in the presence of an anionic hydrocarbon surfactant. By using the anionic hydrocarbon surfactant, the stability of the aqueous dispersion produced by the polymerization is improved, and the polymerization of TFE proceeds smoothly.

[0328] In another embodiment of the polymerization of TFE, TFE is polymerized substantially in the absence of an anionic hydrocarbon surfactant. In the polymerization of TFE carried out in the presence of polymer (1), the polymerization of TFE proceeds smoothly even without the use of an anionic hydrocarbon surfactant.

[0329] In the present disclosure, "substantially in the absence of anionic hydrocarbon surfactant" means that the anionic hydrocarbon surfactant is present in an amount of 10 ppm by mass or less relative to the aqueous medium, 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 even more preferably 1 ppb by mass or less.

[0330] Anionic hydrocarbon surfactants have a hydrophilic portion, typically a carboxylate, sulfonate or sulfate, and a hydrophobic portion which is a long chain hydrocarbon moiety such as an alkyl.

[0331] Examples of anionic hydrocarbon surfactants include Versatic (registered trademark) 10 manufactured by Resolution Performance Products and Avanel S series (S-70, S-74, etc.) manufactured by BASF.

[0332] The anionic hydrocarbon surfactant includes RLM (wherein R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 -is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0333] Specifically, CH3-(CH2) such as lauric acid and lauryl sulfate n -LM (wherein n is an integer of 6 to 17, and L and M are the same as above). Mixtures in which R is an alkyl group having 12 to 16 carbon atoms and LM is sulfate or sodium dodecyl sulfate (SDS) can also be used.

[0334] In addition, the anionic hydrocarbon surfactant R 6 (-LM)2(wherein, R 6 is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3 - or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 - is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0335] In addition, the anionic hydrocarbon surfactant R 7 (-LM)3(wherein, R 7 is a linear or branched alkylidyne group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3- or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group. -ArSO3 - is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0336] The anionic hydrocarbon surfactant also includes siloxane hydrocarbon surfactant. The siloxane hydrocarbon surfactant includes those described in Silicone Surfactants, RM Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of siloxane hydrocarbon surfactant includes a distinct hydrophobic portion and a hydrophilic portion. The hydrophobic portion includes one or more dihydrocarbylsiloxane units, where the substituents on the silicone atom are completely hydrocarbon. These siloxane surfactants can also be considered as hydrocarbon surfactants in the sense that the carbon atoms of the hydrocarbyl group are completely replaced by hydrogen atoms, i.e., the monovalent substituents on the carbon atoms of the hydrocarbyl group are hydrogen, where they may be replaced by halogens such as fluorine.

[0337] The hydrophilic portion of the siloxane hydrocarbon surfactant may include one or more polar moieties that include ionic groups such as sulfates, sulfonates, phosphonates, phosphate esters, carboxylates, carbonates, sulfosuccinates, taurates (as free acids, salts or esters), phosphine oxides, betaines, betaine copolyols, quaternary ammonium salts, etc. The ionic hydrophobic portion may also include ionically functionalized siloxane grafts. Such siloxane hydrocarbon surfactants include, for example, polydimethylsiloxane-graft-(meth)acrylates, polydimethylsiloxane-graft-polyacrylate salts, and polydimethylsiloxane-grafted quaternary amines. The polar portion of the hydrophilic portion of the siloxane hydrocarbon surfactant may include nonionic groups formed by polyethers such as polyethylene oxide (PEO) and mixed polyethylene oxide / propylene oxide polyethers (PEO / PPO); monosaccharides and disaccharides; and water-soluble heterocycles such as pyrrolidinone. The ratio of ethylene oxide to propylene oxide (EO / PO) can be varied in mixed polyethylene oxide / propylene oxide polyethers.

[0338] The hydrophilic portion of the siloxane hydrocarbon surfactant may also contain a combination of ionic and non-ionic moieties, such as ionically end-functionalized or randomly functionalized polyethers or polyols. Preferred are siloxanes with non-ionic moieties, i.e., non-ionic siloxane surfactants.

[0339] The arrangement of hydrophobic and hydrophilic moieties in the structure of the siloxane hydrocarbon surfactant may take the form of a diblock polymer (AB), a triblock polymer (ABA) (where "B" represents the siloxane portion of the molecule), or a multiblock polymer. Alternatively, the siloxane surfactant may comprise a graft polymer.

[0340] Siloxane hydrocarbon surfactants are also disclosed in US Pat. No. 6,841,616.

[0341] Siloxane-based anionic hydrocarbon surfactants include SilSense, available from Noveon® Consumer Specialties of Lubrizol Advanced Materials, Inc. TM PE-100 Silicone, SilSense TM CA-1 silicone and the like.

[0342] Anionic hydrocarbon surfactants include the sulfosuccinate surfactant Lankropol® K8300 from Akzo Nobel Surface Chemistry LLC. Examples of sulfosuccinate surfactants include diisodecyl sodium sulfosuccinate (Emulsogen® SB10 from Clariant) and diisotridecyl sodium sulfosuccinate (Polirol® TR / LNA from Cesapinia Chemicals).

[0343] Anionic hydrocarbon surfactants include PolyFox (registered trademark) surfactants from Omnova Solutions, Inc. TM PF-156A, PolyFox TM PF-136A, etc.)

[0344] Examples of the anionic hydrocarbon surfactant include those represented by the general formula (α): R 10 -COOM (α) (In the formula, R 10 is a monovalent organic group containing one or more carbon atoms. M is H, a metal atom, NR 11 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 11R is H or an organic group, and may be the same or different. 11 As H or C 1-10 is preferably an organic group represented by the formula: 1-4 From the viewpoint of surface activity, the organic group R 10 The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. 10 The number of carbon atoms in is preferably 29 or less, more preferably 23 or less. The metal atom of M may be an alkali metal (group 1) or an alkaline earth metal (group 2), and is preferably Na, K or Li. M may be H, a metal atom or NR 11 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 11 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.

[0345] Compound (α) includes R 12 -COOM(in the formula, R 12 is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms, which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms, which may have a substituent, and these may contain an ether bond. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle, or may form a ring. M is the same as above. ) is also included. Specifically, CH3-(CH2) n -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0346] From the viewpoint of emulsion stability, the compound (α) may be one that does not contain a carbonyl group (excluding the carbonyl group in a carboxyl group). Examples of the hydrocarbon-containing surfactant that does not contain a carbonyl group include a surfactant represented by the following formula (A): R-COO-M(A) (wherein R is an alkyl group, an alkenyl group, an alkylene group, or an alkenylene group having 6 to 17 carbon atoms, which may contain an ether bond. M is H, a metal atom, NR 11 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 11 are the same or different and are H or an organic group having 1 to 10 carbon atoms.) is a preferred example. In the above formula (A), R is preferably an alkyl group or an alkenyl group (which may contain an ether group). The alkyl group or alkenyl group in the above R may be linear or branched. The number of carbon atoms in the above R is not limited, but is, for example, 2 to 29.

[0347] When the alkyl group is linear, R preferably has 3 to 29 carbon atoms, and more preferably has 5 to 23 carbon atoms. When the alkyl group is branched, R preferably has 5 to 35 carbon atoms, and more preferably has 11 to 23 carbon atoms. When the alkenyl group is linear, R preferably has 2 to 29 carbon atoms, and more preferably has 9 to 23 carbon atoms. When the alkenyl group is branched, R preferably has 2 to 29 carbon atoms, and more preferably has 9 to 23 carbon atoms.

[0348] Examples of the alkyl group and the alkenyl group include a methyl group, an ethyl group, an isobutyl group, a t-butyl group, and a vinyl group.

[0349] The anionic hydrocarbon surfactant also includes a carboxylic acid type hydrocarbon surfactant. Examples of the carboxylic acid type hydrocarbon surfactant include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15)-linolenic acid, (6,9,12) linolenic acid, eleostearic acid, arachidic acid, 8,11-eicosadienoic acid, mead acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, melissic acid, crotonic acid, myrisic acid, methyl methacrylate ... Examples of the salts include oleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, linoleic acid, eicosadienoic acid, docosadienoic acid, linolenic acid, pinolenic acid, α-eleostearic acid, β-eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, eicosapentaenoic acid, osbondoic acid, sardine acid, tetracosapentaenoic acid, docosahexaenoic acid, herring acid, and salts thereof. In particular, at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof is preferred. As the salts, those in which the hydrogen of the carboxyl group is a metal atom of the above formula M, NR 11 4. Examples include, but are not limited to, imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent.

[0350] In addition, as the anionic hydrocarbon surfactant, for example, anionic hydrocarbon surfactants described in WO 2013 / 146950 and WO 2013 / 146947 can be used. For example, anionic hydrocarbon surfactants having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, more preferably 9 to 13 carbon atoms can be used. The saturated or unsaturated aliphatic chain may be either a straight chain or a branched chain, or may have a cyclic structure. The hydrocarbon may be aromatic or may have an aromatic group. The hydrocarbon may have a heteroatom such as oxygen, nitrogen, or sulfur.

[0351] Examples of anionic hydrocarbon surfactants include alkyl sulfonates, alkyl sulfates, alkylaryl sulfates, and salts thereof; aliphatic (carboxylic) acids and salts thereof; alkyl phosphates, alkylaryl phosphates, and salts thereof; and among these, alkyl sulfonates, alkyl sulfates, aliphatic carboxylic acids, and salts thereof are preferred.

[0352] As the alkyl sulfate or its salt, ammonium lauryl sulfate and sodium lauryl sulfate are preferred. As the aliphatic carboxylic acid or a salt thereof, succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or a salt thereof is preferred.

[0353] <Fluorosurfactant> In one embodiment of the polymerization of TFE, TFE is polymerized in the presence of a fluorine-containing surfactant (excluding compounds having a functional group capable of reacting by radical polymerization and a hydrophilic group). By using the fluorine-containing surfactant, the stability of the aqueous dispersion produced by the polymerization is improved, and the polymerization of TFE proceeds smoothly.

[0354] In another embodiment of the polymerization of TFE, TFE is polymerized substantially in the absence of a fluorine-containing surfactant (excluding compounds having a functional group capable of reacting in radical polymerization and a hydrophilic group). The polymerization of TFE carried out in the presence of polymer (1) smoothly proceeds even without the use of a fluorine-containing surfactant.

[0355] In the present disclosure, "substantially in the absence of a fluorinated surfactant" means that the fluorinated surfactant is present at 10 ppm by mass or less relative to the aqueous medium, 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 even more preferably 1 ppb by mass or less.

[0356] The fluorine-containing surfactant may be an anionic fluorine-containing surfactant, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms having a total carbon number of 20 or less excluding the anionic group.

[0357] The fluorine-containing surfactant may be a surfactant containing fluorine, the molecular weight of the anionic portion of which is 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) described below may be used. n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0358] The above-mentioned fluorosurfactant also includes a fluorosurfactant having a LogPOW of 3.5 or less. The LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP [wherein P represents the ratio of the fluorosurfactant concentration in octanol to the fluorosurfactant concentration in water when a 1:1 octanol / water mixture containing the fluorosurfactant undergoes phase separation]. The LogPOW is calculated from the HPLC elution time of the sample solution using a calibration curve of each elution time and the known octanol / water partition coefficient, which is prepared by performing HPLC on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) having 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.

[0359] Specific examples of the fluorine-containing surfactant include those described in U.S. Patent Application Publication No. 2007 / 0015864, U.S. Patent Application Publication No. 2007 / 0015865, U.S. Patent Application Publication No. 2007 / 0015866, U.S. Patent Application Publication No. 2007 / 0276103, U.S. Patent Application Publication No. 2007 / 0117914, U.S. Patent Application Publication No. 2007 / 142541, U.S. Patent Application Publication No. 2008 / 0015319, U.S. Patent No. 3,250,808, and the like. No. 3,271,341, JP 2003-119204 A, WO 2005 / 042593 A, WO 2008 / 060461 A, WO 2007 / 046377 A, JP 2007-119526 A, WO 2007 / 046482 A, WO 2007 / 046345 A, U.S. Patent Application Publication No. 2014 / 0228531 A, WO 2013 / 189824 A, and WO 2013 / 189826 A can be mentioned.

[0360] The anionic fluorine-containing surfactant may be represented by the general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 Y is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. 0 is an anionic group.

[0361] Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, where M 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. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., such as Na, K, or Li. R 7 As for the 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 M may be H, a metal atom or NR 7 4, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 4, and may be H, Na, K, Li or NH4. n0 may be one in which 50% or more of H is substituted with fluorine.

[0362] General formula (N 0 As the compound represented by the 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 from 3 to 15; Y 0 is as defined above.) 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.) 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, 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.) 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; Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0is as defined above.) 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 completely fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched, partially or completely 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.

[0363] General formula (N 0 More specifically, the compounds represented by the formula (I) include perfluorocarboxylic acids (I), ω-H perfluorocarboxylic acids (II), perfluoroether carboxylic acids (III), perfluoroalkyl alkylene carboxylic acids (IV), perfluoroalkoxy fluorocarboxylic acids (V), perfluoroalkyl sulfonic acids (VI), perfluoroalkyl sulfonic acids (VII), perfluoroalkyl alkylene sulfonic acids (VIII), perfluoroalkyl alkylene sulfonic acids (IX), fluorocarboxylic acids (X), alkoxy fluorosulfonic acids (XI), compounds (XII), and compounds (XIII) represented by the following formula (XIII).

[0364] The perfluorocarboxylic acid (I) is represented by the general formula (I): F(CF2) n1 COOM (I) (In the formula, 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.

[0365] The ω-H perfluorocarboxylic acid (II) is represented by the general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0366] The perfluoroether carboxylic acid (III) is represented by the 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.

[0367] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the 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.

[0368] The alkoxyfluorocarboxylic acid (V) is represented by the general formula (V): Rf 4 -O-CY1 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; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0369] The perfluoroalkylsulfonic acid (VI) is represented by the general formula (VI): F(CF2) n5 SO3M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0370] The ω-H perfluorosulfonic acid (VII) is represented by the general formula (VII): H(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0371] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the 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.

[0372] The alkyl alkylene carboxylic acid (IX) is represented by the general formula (IX): Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6is a linear or branched partially or completely fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer from 1 to 3, and M is as defined above.

[0373] The fluorocarboxylic acid (X) is represented by the 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 completely fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0374] The alkoxyfluorosulfonic acid (XI) is represented by the 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.

[0375] The compound (XII) is represented by the general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 Rf may be the same or different and are H, F and linear or branched partially or completely fluorinated alkyl groups having 1 to 6 carbon atoms, which may contain ether bonds; 10is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. 0 may be -COOM, -SO2M, or -SO3M, and may be -SO3M or COOM (wherein M is as defined above). Examples of L include a single bond, or a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0376] 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 CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, where n9 and n10 are defined above).

[0377] Thus, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0378] The fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0379] The fluorine-containing surfactant may be a compound represented by the following formula: The fluorine-containing surfactant may be a mixture of these compounds. In one embodiment of the above polymerization, TFE 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.

[0380] <Polymerization terminators and decomposers> After the polymerization of TFE has progressed sufficiently, a polymerization terminator (radical scavenger) may be added to terminate the polymerization of TFE, thereby obtaining an aqueous dispersion.

[0381] As the polymerization terminator, a compound that does not have the ability to restart after addition or chain transfer to the free radical in the polymerization system is used. Specifically, a compound that easily undergoes a chain transfer reaction with a primary radical or a growing radical, and then generates a stable radical that does not react with a monomer, or a compound that easily undergoes an addition reaction with a primary radical or a growing radical to generate a stable radical is used. The activity of a chain transfer agent is generally characterized by the chain transfer constant and the restart efficiency, and among chain transfer agents, a chain transfer agent with a restart efficiency of almost 0% is called a polymerization terminator. As the polymerization terminator, at least one selected from the group consisting of aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl2) is preferable. As the aromatic hydroxy compounds, unsubstituted phenols, polyhydric phenols, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, etc. can be mentioned. Examples of the unsubstituted phenol include o-, m-, or p-nitrophenol, o-, m-, or p-aminophenol, and p-nitrosophenol. Examples of the polyhydric phenol include catechol, resorcin, hydroquinone, pyrogallol, phloroglucin, and naphthresorcinol. Examples of the aromatic amine include o-, m-, or p-phenylenediamine, and benzidine. Examples of the quinone compound include hydroquinone, o-, m-, or p-benzoquinone, 1,4-naphthoquinone, and alizarin. Examples of the thiocyanate include ammonium thiocyanate (NH4SCN), potassium thiocyanate (KSCN), and sodium thiocyanate (NaSCN). Among these, the polymerization terminator is preferably a quinone compound, and more preferably hydroquinone.

[0382] From the viewpoint of reducing the standard specific gravity, the polymerization terminator is preferably added before 90 mass% of the total TFE consumed in the polymerization reaction is polymerized. More preferably, it is added before 85 mass% of the total TFE, and even more preferably, it is added before 80 mass% of the total TFE is polymerized. Also, it is preferably added after 5 mass% of the total TFE consumed in the polymerization reaction is polymerized, and more preferably after 10 mass% is polymerized. The amount of the polymerization terminator added is preferably an amount equivalent to 0.1 to 20 mass ppm of the mass of the aqueous medium used, and more preferably an amount equivalent to 3 to 10 mass ppm.

[0383] When TFE is polymerized, the radical concentration during polymerization can be adjusted by adding a decomposer. Examples of the decomposer include sulfite, bisulfite, bromate, diimine, oxalic acid, copper salt, and iron salt. Examples of the sulfite include sodium sulfite and ammonium sulfite. Examples of the copper salt include copper (II) sulfate, and examples of the iron salt include iron (II) sulfate. The amount of the decomposer added is in the range of 25 to 300 mass% based on the amount of the oxidizing agent combined as a polymerization initiator (redox initiator). The amount of the decomposer added is preferably 25 to 150 mass%, more preferably 50 to 100 mass%. In addition, it is preferable to add the decomposer after 5 mass% of the total TFE consumed in the polymerization reaction is polymerized, and more preferably after 10 mass% is polymerized. The amount of the decomposer added is preferably an amount equivalent to 0.1 to 20 mass ppm of the mass of the aqueous medium used, and more preferably an amount equivalent to 3 to 10 mass ppm.

[0384] <Polytetrafluoroethylene> The manufacturing method of the present disclosure provides polytetrafluoroethylene (PTFE). PTFE obtained by polymerization of TFE in an aqueous medium is usually in the form of primary particles dispersed in an aqueous dispersion.

[0385] The PTFE generally has extensibility, fibrillation properties, and non-melt fabrication properties. The non-melt fabrication properties mean that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point according to ASTM D 1238 and D 2116, that is, that the PTFE does not flow easily even in the melting temperature range.

[0386] The PTFE obtained by the production method of the present disclosure may be a TFE homopolymer containing only TFE units, or may be a modified PTFE containing TFE units and modified monomer units.

[0387] The content of the modified PTFE in the polymerized units based on the modified monomer (hereinafter also referred to as "modified monomer units") is preferably in the range of 0.00001 to 1 mass% based on the total polymerized units of PTFE. The lower limit of the content of the modified monomer units is more preferably 0.0001 mass%, further preferably 0.001 mass%, and further more preferably 0.005 mass%. The upper limit of the content of the modified monomer units is, in order of preference, 0.80 mass%, 0.70 mass%, 0.50 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, and 0.05 mass%. In the present disclosure, the modified monomer units refer to a part of the molecular structure of PTFE that is derived from the modified monomer.

[0388] 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. In addition, the content of each monomer unit constituting PTFE can also be calculated from the amount of modified monomer added used in polymerization.

[0389] When the modified monomer includes the modified monomer (A), the content of the polymerized units based on the modified monomer (A) is preferably in the range of 0.00001 to 1.0% by mass based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90% by mass, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0390] The PTFE may have a core-shell structure. The core-shell structure is a conventionally known structure, and is a structure of primary particles in an aqueous dispersion that can be produced by the method described in U.S. Patent No. 6,841,594 or the like. Examples of PTFE having a core-shell structure include a core-shell structure comprising a core portion of a TFE homopolymer and a shell portion of a modified PTFE, a core-shell structure comprising a core portion of a modified PTFE and a shell portion of a TFE homopolymer, and a core-shell structure comprising a core portion of modified PTFE and a shell portion of modified PTFE having a different monomer composition from the modified PTFE constituting the core portion. The PTFE having the core-shell structure can be obtained, for example, by first polymerizing TFE and, if necessary, a modified monomer to produce a core portion (TFE homopolymer or modified PTFE), and then polymerizing TFE and, if necessary, a modified monomer to produce a shell portion (TFE homopolymer or modified PTFE). The above-mentioned shell portion means a portion constituting a predetermined thickness from the surface of the PTFE primary particle to the inside of the particle, and the core portion means a portion constituting the inside of the shell portion.

[0391] In the present disclosure, the core-shell structure includes all of the following: (1) a core portion and a shell portion having different monomer compositions; (2) a core portion and a shell portion having the same monomer composition and different number average molecular weights; and (3) a core portion and a shell portion having different monomer compositions and different number average molecular weights.

[0392] When the shell portion is modified PTFE, the content of the modifying monomer in the shell portion is preferably 0.0001 to 1% by mass, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more, and more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less.

[0393] When the core part is modified PTFE, the content of the modifying monomer in the core part is preferably 0.00001 to 1.0% by mass, more preferably 0.0001% by mass or more, and even more preferably 0.001% by mass or more, and more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less.

[0394] The PTFE has an average primary particle diameter of 500 nm or less, more preferably 400 nm or less, and even more preferably 350 nm or less. The relatively small average primary particle diameter of the primary particles allows the polymerization of TFE in an aqueous medium to proceed smoothly, and PTFE can be easily produced. The production method of the present disclosure can obtain primary particles having a relatively small average primary particle diameter. Furthermore, an even smaller average primary particle diameter of the primary particles can be obtained, for example, by adding a modified monomer to the polymerization system at the beginning of the polymerization of TFE. 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.

[0395] The average primary particle size of the PTFE primary particles can be measured by dynamic light scattering. First, a PTFE aqueous dispersion with a polymer solids concentration adjusted to about 1.0 mass% is prepared, and the average primary particle size can be measured using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and an accumulation number of 70. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method.

[0396] The upper limit of the aspect ratio of the primary particles of PTFE is, in order of preference, less than 2.00, 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. The relatively small aspect ratio allows the polymerization of TFE in an aqueous medium to proceed smoothly, and PTFE can be easily produced. The production method of the present disclosure can obtain primary particles having a relatively small aspect ratio. Furthermore, an even smaller aspect ratio of the primary particles can be obtained, for example, by adding a modified monomer to the polymerization system at the beginning of the polymerization of TFE.

[0397] When the aspect ratio of PTFE is measured using an aqueous PTFE dispersion, an aqueous PTFE dispersion adjusted to a polymer solids concentration of about 1.0% by mass is prepared, observed with a scanning electron microscope (SEM), and randomly selected 400 or more particles are subjected to image processing, and the aspect ratio can be calculated from the average ratio of the long diameter to the short diameter. When the aspect ratio of PTFE is measured using a powder of PTFE, the PTFE powder is irradiated with an electron beam, then added to an aqueous solution of a fluorine-containing surfactant, and ultrasonic waves are applied to redisperse the powder in the aqueous solution to prepare an aqueous PTFE dispersion. The aspect ratio can be calculated by the above-mentioned method using the aqueous dispersion prepared in this way.

[0398] 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. Also, it is preferably 2.130 or more. By having the SSG within the above range, it is possible to achieve both excellent moldability and excellent physical properties of the molded body obtained by molding. The SSG is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895-89.

[0399] The PTFE may have a thermal instability index (TII) of 20 or more. The thermal instability index (TII) of PTFE can be adjusted to 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.

[0400] The 0.1% mass loss temperature of PTFE may be equal to or lower than 400° C. The 0.1% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using the polymer (1).

[0401] The 0.1% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, 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 the air in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0402] The 1.0% mass loss temperature of PTFE may be equal to or lower than 492° C. The 1.0% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using the polymer (1).

[0403] The 1.0% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, 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 in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0404] The peak temperature of the PTFE may be from 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.

[0405] The peak temperature of PTFE can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer). The peak temperature can be identified as the temperature that corresponds to the maximum value that appears on a differential thermal (DTA) curve obtained by heating PTFE that has not been heated to a temperature of 300°C or higher at a rate of 10°C / min using a TG / DTA (thermogravimetric / differential thermal analyzer).

[0406] The extrusion pressure of PTFE is preferably 50.0 MPa or less, more preferably 40.0 MPa or less, and is preferably 5.0 MPa or more, more preferably 10.0 MPa or more, and even more preferably 15.0 MPa or more.

[0407] The above extrusion pressure is a value obtained by the following method according to the method described in JP 2002-201217 A. The extrusion pressure of PTFE can be specified by the following method. 21.7 g of a lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon Corp.) is added to 100 g of PTFE powder and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste-extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead (beading; extrusion molded body). The extrusion speed, i.e., the ram speed, is 20 inches / min (51 cm / min). The extrusion pressure is determined by measuring the load when the extrusion load reaches equilibrium in the paste extrusion and dividing the value by the cross-sectional area of ​​the cylinder used for the paste extrusion.

[0408] The breaking strength A of PTFE is, in order of preference, 10.0 N or more, 13.0 N or more, 15.0 N or more, 18.0 N or more, 20.0 N or more, 22.0 N or more, 25.0 N or more, 28.0 N or more, and 30.0 N or more. The higher the breaking strength A, the better, but the upper limit of the breaking strength A may be, for example, 100 N or less, 80.0 N or less, or 50.0 N or less.

[0409] The breaking strength A is a value determined by the following method in accordance with the method described in JP-A-2002-201217. The breaking strength A of PTFE can be specified by the following method. First, an extrusion bead stretching test A is carried out by the following method to prepare a sample for measuring breaking strength A. 21.7 g of lubricant is added to 100 g of the obtained PTFE powder and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste extruded through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at room temperature with a reduction ratio of 100:1 to obtain a uniform beading (extrusion molded product). The extrusion speed, i.e., the ram speed, is 20 inches / minute (51 cm / minute). The bead obtained by the above paste extrusion is heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) is then cut to the appropriate length, clamped at each end with a clamp distance of 1.5 inches (38 mm) apart, and heated to 300°C in an air circulating oven. The clamps are then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) is achieved, and a stretch test is performed. This stretching method essentially follows the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. In the above preparation method, the stretch rate is 1000% / sec and the total stretch is 2400%.

[0410] The stretched bead (produced by stretching the bead) obtained in the above stretching test A is clamped and fixed in a movable jaw having a gauge length of 5.0 cm, and a tensile test is performed at 25°C and a speed of 300 mm / min. The strength at which it breaks is defined as breaking strength A.

[0411] The stress relaxation time of PTFE is preferably 50 seconds or more, more preferably 80 seconds or more, further preferably 100 seconds or more, and may be 150 seconds or more.

[0412] The stress relaxation time is a value determined by the following method in accordance with the method described in JP-A-2002-201217. The stress relaxation time of PTFE can be determined by the following method: A bead sample with a total length of 8 inches (20 cm) held taut is attached to a fixture at both ends of the expanded bead from Expansion Test A above. The oven is maintained at 390°C and the fixture is inserted into the oven through a (covered) slit in the side of the oven. The time it takes for the bead sample to break from the point of insertion into the oven is the stress relaxation time.

[0413] The manufacturing method of the present disclosure also allows the production of low molecular weight PTFE. The low molecular weight PTFE may be produced by polymerization, or it may be produced by lowering the molecular weight of the high molecular weight PTFE obtained by polymerization by a known method (thermal decomposition, decomposition by irradiation, etc.).

[0414] 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 not prone 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, and the like (see, for example, JP-A-10-147617).

[0415] Further, in the presence of a chain transfer agent, a polymerization initiator and the polymer (1) may be dispersed in an aqueous medium, and TFE or a monomer copolymerizable with TFE may be polymerized with TFE to obtain a low molecular weight PTFE. 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 preferable, and ethane and propane are even more preferable. In this case, the amount of the chain transfer agent is preferably 10 ppm by mass or more or more than 10 ppm by mass relative to the aqueous medium.

[0416] When the low-molecular-weight PTFE obtained by the above polymerization is used as a powder, the above aqueous dispersion can be coagulated to form powder particles.

[0417] In the present disclosure, high molecular weight PTFE refers to non-melt processable and fibrillating PTFE, whereas low molecular weight PTFE refers to melt processable and non-fibrillating PTFE.

[0418] The term "non-melt processable" means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point according to ASTM D 1238 and D 2116.

[0419] The presence or absence of fibrillation properties can be judged 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 fibrillation properties. If the unsintered molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it breaks when pulled with an elongation of 0%, it can be considered to have no fibrillation properties.

[0420] 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.

[0421] The low molecular weight PTFE has a melt viscosity of 1×10 at 380° C. 2 ~7×10 5 In the present disclosure, "low molecular weight" means that the melt viscosity is within the above range. The melt viscosity is measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2g sample preheated at 380°C for 5 minutes, and maintained at the above temperature under a load of 0.7 MPa.

[0422] The high molecular weight PTFE has a melt viscosity much higher than that of the low molecular weight PTFE, and it is difficult to measure the melt viscosity accurately. On the other hand, although the melt viscosity of the low molecular weight PTFE can be measured, it is difficult to obtain a molded product that can be used to measure the standard specific gravity from the low molecular weight PTFE, and it is difficult to measure the standard specific gravity accurately. Therefore, in this disclosure, the standard specific gravity is adopted as an index of the molecular weight of the high molecular weight PTFE, and the melt viscosity is adopted as an index of the molecular weight of the low molecular weight PTFE. Note that there is no known measurement method that can directly specify the molecular weight of either the high molecular weight PTFE or the low molecular weight PTFE.

[0423] The average primary particle diameter of the low-molecular-weight PTFE primary particles is preferably 10 to 200 nm, more preferably 20 nm or more, more preferably 140 nm or less, further preferably 150 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 modified monomer to the polymerization system at the initial stage of TFE polymerization.

[0424] The average primary particle size of the primary particles of low molecular weight PTFE can be measured by dynamic light scattering. First, a low molecular weight PTFE aqueous dispersion with a polymer solid concentration adjusted to about 1.0 mass% is prepared, and the average primary particle size can be measured using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and an accumulation number of 70 times. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method.

[0425] A PTFE aqueous dispersion can be obtained by the manufacturing method of the present disclosure. The solid content concentration of the PTFE aqueous dispersion is not limited, but may be, for example, 1.0 to 70 mass%. The solid content concentration is preferably 8.0 mass% or more, more preferably 10.0 mass% or more, and is preferably 60.0 mass% or less, more preferably 50.0 mass% or less.

[0426] In the PTFE production method of the present disclosure, the adhesion amount is preferably 3.0 mass% or less, more preferably 2.0 mass% or less, more preferably 1.0 mass% or less, even more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.6 mass% or less, based on the finally obtained PTFE.

[0427] Next, applications of the PTFE obtained by the production method of the present disclosure will be described in more detail.

[0428] The PTFE may be an aqueous PTFE dispersion in which primary particles of PTFE are dispersed in an aqueous medium.

[0429] The use of the PTFE aqueous dispersion is not particularly limited, and examples of applications of the aqueous dispersion as it is include coating, which involves applying the dispersion onto a substrate, drying, and optionally baking; impregnation, which involves impregnating a porous support such as a nonwoven fabric or a resin molded product, drying, and preferably baking; and cast film formation, which involves applying the dispersion onto a substrate such as glass, drying, and optionally immersing the substrate in water and peeling the substrate off to obtain a thin film. Examples of these applications include aqueous dispersion-type paints, tent films, conveyor belts, printed circuit boards (CCL), electrode binders, and electrode water repellents.

[0430] The PTFE aqueous dispersion can be used as an aqueous coating material by blending it with known compounding agents such as pigments, thickeners, dispersants, antifoaming agents, antifreezing agents, and film-forming assistants, or by further combining it with other polymer compounds. As additive applications, it can be used as a binding agent to prevent the active material of an electrode from falling off, as a binder, as a compound such as an anti-drip agent, and as a dust suppression treatment to prevent the scattering of soil, sand, dust, etc.

[0431] The PTFE aqueous dispersion is also preferably used as a dust suppressant treatment. The dust suppressant treatment can be used in a method of suppressing dust from a dust-generating substance by mixing the dust suppressant treatment 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 PTFE, for example, in the method described in Japanese Patent No. 2827152, Japanese Patent No. 2538783, etc. The above-mentioned PTFE aqueous dispersion can be suitably used in the dust suppressive treatment composition described in, for example, WO 2007 / 004250, and can also be suitably used in the dust suppressive treatment method described in WO 2007 / 000812.

[0432] The above-mentioned dust suppression treatment agent is suitably used for dust suppression treatment in the fields of building materials, soil stabilization materials, solidification materials, fertilizers, landfill disposal of incineration ash and harmful substances, explosion prevention, cosmetics, and sand for pet excretion, such as cat litter.

[0433] The manufacturing method of the present disclosure may further include at least one of the steps of recovering the PTFE aqueous dispersion obtained by the above-mentioned method, coagulating PTFE in the PTFE aqueous dispersion, recovering the coagulated PTFE, and drying the recovered PTFE at 100 to 300° C. The manufacturing method of the present disclosure may include such steps, thereby making it possible to obtain a PTFE powder.

[0434] Powder can be produced by coagulating the PTFE contained in the aqueous dispersion. The aqueous dispersion of PTFE can be used for various applications as a powder after coagulation, washing, and drying, after post-treatment such as concentration as necessary. When coagulation is performed on the aqueous dispersion of PTFE, the aqueous dispersion obtained by polymerization of polymer latex or the like is usually diluted with water to a polymer concentration of 10 to 25% by mass, and in some cases, the pH is adjusted to neutral or alkaline, and then the mixture is stirred more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be performed while stirring the mixture, while adding water-soluble organic compounds such as methanol and acetone, inorganic salts such as potassium nitrate and ammonium carbonate, and inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid as a coagulant. The coagulation may also be performed continuously using an in-line mixer or the like.

[0435] The aqueous dispersion may be any of an aqueous dispersion obtained by carrying out the above-mentioned polymerization, a dispersion obtained by concentrating this aqueous dispersion or subjecting it to a dispersion stabilization treatment, and a dispersion obtained by dispersing a powder made of PTFE in an aqueous medium in the presence of the above-mentioned surfactant.

[0436] As a method for producing the above-mentioned aqueous dispersion, a purified aqueous dispersion can be produced by (I) contacting the aqueous dispersion obtained by the polymerization with an anion exchange resin or a mixed bed containing an anion exchange resin and a cation exchange resin in the presence of a nonionic surfactant, and / or (II) concentrating the aqueous dispersion so that the solid content is 30 to 70 mass% relative to 100 mass% of the aqueous dispersion. The nonionic surfactant is not particularly limited, but a known one can be used. The anion exchange resin is not particularly limited, but a known one can be used. In addition, the method of contacting with the anion exchange resin can be a known method. As a method for producing the aqueous dispersion, the aqueous dispersion obtained by the polymerization is subjected to step (I), and the aqueous dispersion obtained in step (I) is subjected to step (II) to produce a purified aqueous dispersion. Alternatively, the purified aqueous dispersion can be produced by performing step (II) without performing step (I). Steps (I) and (II) can be performed repeatedly or in combination.

[0437] The anion exchange resin may, for example, have a functional group of -N + X - A strongly basic anion exchange resin having (CH3)3 groups (X represents Cl or OH), -N + X - Examples of the resin include well-known strong basic anion exchange resins having a (CH3)3(C2H4OH) group (X is the same as above). Specific examples include those described in WO 99 / 62858, WO 03 / 020836, WO 2004 / 078836, WO 2013 / 027850, and WO 2014 / 084399.

[0438] The cation exchange resin is not particularly limited, and may be, for example, a resin having a functional group of -SO3 - Strongly acidic cation exchange resin with -COO functional group - Examples of the cation exchange resin include well-known weakly acidic cation exchange resins having a cation group, etc. Among them, from the viewpoint of removal efficiency, strongly acidic cation exchange resins are preferred, and H + Strongly acidic cation exchange resins of the type are more preferred.

[0439] The above-mentioned "mixed bed consisting of a cation exchange resin and an anion exchange resin" is not particularly limited, and includes a case in which both are packed in the same column, a case in which both are packed in different columns, a case in which both are dispersed in an aqueous dispersion, etc.

[0440] A known method is used as the concentration method. Specific examples include those described in International Publication No. 2007 / 046482 and International Publication No. 2014 / 084399. Examples include phase separation, centrifugal sedimentation, cloud point concentration, electric concentration, electrophoresis, filtration using ultrafiltration, filtration using a reverse osmosis membrane (RO membrane), nanofiltration, etc. The concentration can be adjusted to a PTFE concentration of 30 to 70% by mass depending on the application. The stability of the dispersion may be impaired by concentration, in which case a dispersion stabilizer may be further added. As the dispersion stabilizer, the above-mentioned nonionic surfactants and various other surfactants may be added. The nonionic surfactant is the same as the nonionic surfactant exemplified as the nucleating agent described above, and the nonionic surfactant described above can be appropriately used. The nonionic surfactant preferably does not contain an aromatic moiety. The cloud point of a nonionic surfactant is a measure of the solubility of the surfactant in water. The surfactant used in the aqueous dispersion of the present disclosure has a cloud point of about 30°C to about 90°C, preferably about 35°C to about 85°C.

[0441] The total amount of the dispersion stabilizer is a concentration of 0.5 to 20% by mass based on the solid content of the dispersion. If it is less than 0.5% by mass, the dispersion stability may be poor, and if it exceeds 20% by mass, the dispersion effect is not commensurate with the amount present, making it impractical. The more preferred lower limit of the dispersion stabilizer is 2% by mass, and the more preferred upper limit is 12% by mass.

[0442] The surfactant may be removed by the above concentration procedure.

[0443] The aqueous dispersion obtained by carrying out the above polymerization can also be prepared into an aqueous dispersion having a long pot life by subjecting it to a dispersion stabilization treatment without being concentrated depending on the application. The dispersion stabilizer used can be the same as those mentioned above.

[0444] An anionic surfactant may be preferably contained for the purpose of adjusting the viscosity of the aqueous dispersion or for the purpose of improving the miscibility of pigments, fillers, etc. The anionic surfactant may be appropriately added within a range that does not cause problems in terms of economy or the environment.

[0445] The anionic surfactant may be a non-fluorinated anionic surfactant or a fluorine-containing anionic surfactant, with a non-fluorinated anionic surfactant not containing fluorine, that is, a hydrocarbon anionic surfactant being preferred.

[0446] For the purpose of adjusting the viscosity, the type of anionic surfactant is not particularly limited as long as it is a known anionic surfactant, and for example, anionic surfactants described in International Publication No. 2013 / 146950 and International Publication No. 2013 / 146947 can be used. For example, anionic surfactants having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, more preferably 9 to 13 carbon atoms can be used. The saturated or unsaturated aliphatic chain may be either a straight chain or a branched chain, or may have a cyclic structure. The hydrocarbon may be aromatic or may have an aromatic group. The hydrocarbon may have a heteroatom such as oxygen, nitrogen, or sulfur. Examples of anionic surfactants include alkyl sulfonates, alkyl sulfates, alkylaryl sulfates, and salts thereof; aliphatic (carboxylic) acids and salts thereof; alkyl phosphates, alkylaryl phosphates, and salts thereof; and among these, alkyl sulfonates, alkyl sulfates, aliphatic carboxylic acids, and salts thereof are preferred. As the alkyl sulfate or its salt, ammonium lauryl sulfate, sodium lauryl sulfate, etc. are preferred. As the aliphatic carboxylic acid or a salt thereof, succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or a salt thereof is preferred.

[0447] The amount of the anionic surfactant added varies depending on the type of the anionic surfactant and other compounding ingredients, but is preferably 10 ppm by mass to 5000 ppm by mass relative to the solid content mass of PTFE. The lower limit of the amount of the anionic surfactant added is more preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more. If the amount added is too small, the viscosity adjusting effect is poor. The upper limit of the amount of the anionic surfactant added is more preferably 3000 ppm by mass or less, and even more preferably 2000 ppm by mass or less. If the amount added is too large, the mechanical stability and storage stability of the aqueous dispersion may be impaired.

[0448] For the purpose of adjusting the viscosity of the above-mentioned aqueous dispersion, in addition to the anionic surfactant, for example, methyl cellulose, alumina sol, polyvinyl alcohol, carboxylated vinyl polymer, etc. can also be blended. For the purpose of adjusting the pH of the above aqueous dispersion, a pH adjuster such as aqueous ammonia may be added.

[0449] If necessary, the aqueous dispersion may contain other water-soluble polymer compounds within a range that does not impair the characteristics of the aqueous dispersion. The other water-soluble polymer compounds are not particularly limited, and examples thereof include polyethylene oxide (dispersion stabilizer), polyethylene glycol (dispersion stabilizer), polyvinylpyrrolidone (dispersion stabilizer), phenol resin, urea resin, epoxy resin, melamine resin, polyester resin, polyether resin, acrylic silicone resin, silicone resin, silicone polyester resin, polyurethane resin, etc. Furthermore, preservatives such as isothiazolone, azole, pronopol, chlorothalonil, methylsulfonyltetrachloropyrrolidone, carbentazim, fluorophorbet, sodium diacetate, and diiodomethyl-paratolylsulfone may be contained.

[0450] In the present disclosure, the PTFE aqueous dispersion used for coagulation stirring (hereinafter referred to as PTFE dispersion for coagulation) preferably has a PTFE solid content concentration of 10 to 25% by mass. The PTFE solid content concentration is preferably 10 to 22% by mass, more preferably 10 to 20% by mass. In order to increase the bulk density of the PTFE fine powder, it is preferable that the PTFE solid content concentration in the PTFE aqueous dispersion for coagulation is high. When the PTFE solid content concentration in the PTFE aqueous dispersion for coagulation is high, the degree of association of the primary particles of PTFE increases, and the primary particles of PTFE are densely associated and coagulated to form granules. When the PTFE solid content concentration in the PTFE aqueous dispersion for coagulation is less than 10% by mass, the coagulation density of the primary particles of PTFE tends to be sparse, making it difficult to obtain a PTFE fine powder with a high bulk density. On the other hand, if the PTFE solid content concentration in the PTFE aqueous dispersion for coagulation is too high, the amount of uncoagulated PTFE increases, and the concentration of uncoagulated PTFE solid content in the coagulation wastewater increases. If the concentration of uncoagulated PTFE solid content in the coagulation wastewater is high, pipe clogging and wastewater treatment costs and labor are required. In addition, the yield of PTFE fine powder decreases. The concentration of uncoagulated PTFE solid content in the coagulation wastewater is preferably low from the viewpoint of productivity of PTFE fine powder, more preferably less than 0.4 mass%, further preferably less than 0.3 mass%, and particularly preferably less than 0.2 mass%. If the PTFE solid content concentration of the PTFE aqueous dispersion for coagulation exceeds 25 mass%, it is difficult to make the concentration of uncoagulated PTFE solid content in the coagulation wastewater less than 0.4 mass%. In addition, since the PTFE solid content concentration in the PTFE aqueous dispersion obtained in the above step l is about 10 to 45 mass%, if the PTFE solid content concentration is high, a diluting solvent such as water is added to adjust it to 10 to 25 mass%. When the PTFE solids concentration in the PTFE aqueous dispersion after polymerization is 10 to 25 mass %, the PTFE aqueous dispersion can be used as it is as the PTFE aqueous dispersion for coagulation.

[0451] By adding pigments for coloring or various fillers for improving mechanical properties before or during the coagulation, it is possible to obtain pigmented or filled PTFE powder in which the pigments and fillers are uniformly mixed.

[0452] The wet powder obtained by coagulating the PTFE is usually dried by using a vacuum, high frequency, hot air, or other means while keeping the wet powder in a state where it is not very fluid, preferably in a state where it is left stationary. Friction between powders, especially at high temperatures, generally has an undesirable effect on fine powder-type PTFE. This is because particles made of this type of PTFE have the property of easily fibrillating even with a small shear force and losing the original stable particle structure. The drying can be performed at a drying temperature of preferably 10 to 300°C, more preferably 100 to 300°C.

[0453] The PTFE powder preferably has an average particle size (average secondary particle size) of 100 to 2000 μm. The lower limit of the average secondary particle size is more preferably 200 μm or more, and even more preferably 300 μm or more. The upper limit of the average secondary particle size is preferably 1000 μm or less, more preferably 800 μm or less, and particularly preferably 700 μm or less. The average particle size is a value measured in accordance with JIS K 6891.

[0454] The PTFE powder is preferably used for molding, and suitable applications include hydraulic and fuel system tubes for aircraft and automobiles, flexible hoses for chemicals and steam, and wire coating. It can also be used as a binder for batteries and for dust prevention. An elongated body can also be produced from the PTFE powder.

[0455] The stretched body can be obtained, for example, by paste extruding the PTFE powder obtained by the manufacturing method of the present disclosure to obtain an extrudate such as a sheet-like extrudate or a rod-like extrudate, and then by roll-stretching the obtained extrudate in the extrusion direction to obtain a uniaxially stretched film as a stretched body. Furthermore, the obtained uniaxially stretched film can be stretched in the width direction by a tenter or the like to obtain a biaxially stretched film as a stretched body. Before stretching, the extrudate may be subjected to a semi-sintering treatment. As stretching conditions, a speed of 5 to 2000% / sec and a stretch ratio of 200% or more are preferably adopted. By stretching, the PTFE in the powder is easily fibrillated, and a stretched body consisting of nodes and fibers is obtained. Specific applications are given below as examples.

[0456] Electrochemical Field Dielectric material prepreg, EMI shielding material, heat transfer material, etc. More specifically, printed wiring board, electromagnetic shielding material, insulating heat transfer material, insulating material, etc. Sealing materials field Gaskets, packing, pump diaphragms, pump tubes, aircraft sealing materials, etc.

[0457] Air Filtration Field ULPA filters (for semiconductor manufacturing), HEPA filters (for hospitals and semiconductor manufacturing), cylindrical cartridge filters (for industrial use), bag filters (for industrial use), heat-resistant bag filters (for exhaust gas treatment), heat-resistant pleated filters (for exhaust gas treatment), SINBRAN filters (for industrial use), catalyst filters (for exhaust gas treatment), adsorbent filters (for HDD installation), adsorbent vent filters (for HDD installation), vent filters (for HDD installation 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 device housings), etc.

[0458] 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 terminals and mobile phones, medical ventilation applications, etc.

[0459] Liquid Filtration Semiconductor liquid filtration filters (for semiconductor manufacturing), hydrophilic PTFE filters (for semiconductor manufacturing), chemical filters (for chemical liquid treatment), pure water production line filters (for pure water production), backwash type liquid filtration filters (for industrial wastewater treatment), etc.

[0460] General consumer goods field Clothing, cable guides (movable wires for motorcycles), motorcycle clothing, cast liners (medical supporters), vacuum cleaner filters, bagpipes (musical instruments), cables (signal cables for guitars, etc.), strings (for stringed instruments), etc.

[0461] Textiles PTFE fiber (textile material), sewing thread (textile), weaving thread (textile), rope, etc.

[0462] Medical field Internal implants (extended products), artificial blood vessels, catheters, general surgery (tissue reinforcement materials), head and neck products (dura substitutes), oral health (tissue regenerative medicine), orthopedics (bandages), etc.

[0463] The production method of the present disclosure is a PTFE production method in which polytetrafluoroethylene (PTFE) is obtained by polymerizing tetrafluoroethylene (TFE) in an aqueous medium in the presence of polymer (2) (hereinafter, sometimes referred to as the second production method of the present disclosure).

[0464] The polymer (2) used in the second production method of the present disclosure is a polymer (2) of a monomer (2) represented by general formula (2), and has a weight average molecular weight of 1.0×10 4 or more, the ion exchange capacity is 2.2 meq / g or more, and the content of polymerized units (2) based on monomer (2) is 40 mol % or more based on all polymerized units constituting polymer (2).

[0465] The monomer (2) is represented by the following general formula (2). CX2=CY(-O-Rf-A) (2) (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; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond or a keto group having 2 to 100 carbon atoms; A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M 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.

[0466] The production method of the present disclosure involves polymerizing TFE in the presence of polymer (2), and therefore can produce PTFE that is substantially free of dimers and trimers, which are monomers that constitute polymer (2). Furthermore, the production method of the present disclosure can produce primary particles of PTFE with a small aspect ratio.

[0467] The polymer (2) may be a homopolymer of the monomer (2) represented by the general formula (2) or a copolymer with other monomers.

[0468] In general formula (2), X is H or F. Both X's may be F, or at least one X may be H. For example, one X may be F and the other H, or both X's may be H.

[0469] In the general formula (2), Y is H, F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. Y is preferably H, F or CF3, and more preferably F.

[0470] In the general formula (2), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be H and Y may be F.

[0471] In general formula (2), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not include a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0472] The carbon number of the fluorine-containing alkylene group of Rf is preferably 2 or more. Also, it 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-, and CF2CF2CF2CF2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group, and more preferably an unbranched linear perfluoroalkylene group.

[0473] 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 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).

[0474] 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-CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0475] 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.

[0476] 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.

[0477] A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM (M 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).

[0478] R 7 As for the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group of H or C 1-4 More preferred are alkyl groups of the formula:

[0479] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[0480] M is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, H, Na or NH4 is especially preferred, and H or NH4 is most preferred.

[0481] A is preferably -COOM or -SO3M, and more preferably -COOM.

[0482] The monomer represented by general formula (2) is preferably at least one selected from the group consisting of monomers represented by general formulae (2a), (2b), (2c), (2d), (2f) and (2g). CF2=CF-O-(CF2) n1 -A (2a) (In the formula, n1 represents an integer of 1 to 10, and A is the same as defined above.) CF2=CF-O-(CF2C(CF3)F) n2 -A (2b) (In the formula, n2 represents an integer of 1 to 5, and A is as defined above.) CF2=CF-O-(CFX 1 ) n3 -A (2c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and A is as defined above. CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -A (2d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and A and X 1 is the same as the above definition.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-A (2e) (In the formula, n5 represents an integer of 0 to 10; A and X 1 is the same as the above definition.) CF2=CF-O-(CF2) n7 -O-(CF2) n8 -A (2f) (In the formula, n7 represents an integer of 1 to 10, n8 represents an integer of 1 to 3, and A is as defined above.) CF2=CF[OCF2CF(CF3)] n9 O(CF2) n10 O[CF(CF3)CF2O] n11 CF(CF3)-A (2g) (In the formula, n9 represents an integer of 0 to 5, n10 represents an integer of 1 to 8, and n11 represents an integer of 0 to 5. A is as defined above.)

[0483] In the general formula (2a), the above n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less.

[0484] Examples of the monomer represented by general formula (2a) include CF2=CF-O-CF2COOM, CF2=CF-O-CF2SO3M, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)3COOM), CF2=CF(O(CF2)3SO3M), and CF2=CFO(CF)4SO3M (wherein M is as defined above).

[0485] In general formula (2b), n2 is preferably an integer of 3 or less from the viewpoint of the dispersion stability of the resulting composition.

[0486] In the general formula (2c), n3 is preferably an integer of 5 or less from the viewpoint of water solubility, and A is preferably -COOM or -SO3M, more preferably -COOM. M is preferably H, Na, K or NH4, more preferably H or NH4.

[0487] In the general formula (2d), X 1 is preferably -CF3 in terms of dispersion stability of the composition, n4 is preferably an integer of 5 or less in terms of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0488] Examples of the monomer represented by general formula (2d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0489] In the general formula (2e), n5 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, and M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0490] Examples of the monomer represented by general formula (2e) include CF2=CFOCF2CF2CF2COOM and CF2=CFOCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal).

[0491] In the general formula (2f), n7 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM or -SO3M, and more preferably -COOM, and M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0492] An example of the monomer represented by the general formula (2f) is CF2=CF-O-(CF2)3-O-CF2-COOM (wherein M represents H, NH4 or an alkali metal).

[0493] In the general formula (2g), n9 is preferably an integer of 3 or less in terms of water solubility, n10 is preferably an integer of 3 or less, n11 is preferably an integer of 3 or less, A is preferably -COOM or -SO3M, and more preferably -COOM. M is preferably H, Na, K, or NH4, and more preferably H or NH4.

[0494] Examples of the monomer represented by general formula (2g) include CF2=CFO(CF2)2OCF(CF3)COOM, CF2=CFOCF2CF2OCF(CF3)CF2OCF(CF3)COOM, CF2=CFOCF2CF(CF3)OCF2CF2OCF(CF3)COOM, CF2=CF[OCF2CF(CF3)]2O(CF2)2O[CF(CF3)CF2O]CF(CF3)COOM, and CF2=CF[OCF2CF(CF3)]3O(CF2)2O[CF(CF3)CF2O]3CF(CF3)COOM (wherein M represents H, NH4 or an alkali metal).

[0495] The polymer (2) may be a homopolymer consisting of only the polymerization unit (2), or may be a copolymer containing the polymerization unit (2) and a polymerization unit based on another monomer copolymerizable with the monomer (2) represented by the general formula (2). From the viewpoint of solubility in an aqueous medium, a homopolymer consisting of only the polymerization unit (2) is preferred. The polymerization units (2) may be the same or different in each occurrence, and the polymer (2) may contain polymerization units (2) based on two or more different monomers represented by the general formula (2).

[0496] The other monomer is preferably the same as the other monomer constituting the polymerized unit that the polymer (1) may contain.

[0497] In the polymer (2), the content of the polymerized units (2) is, in order of preference, 40 mol% or more, 50 mol% or more, more than 50 mol%, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and 99 mol% or more based on the total polymerized units. The content of the polymerized units (2) is particularly preferably substantially 100 mol%, and the polymer (2) is most preferably composed only of the polymerized units (2). By having the content of the polymerized units (2) within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0498] In the polymer (2), the content of polymerization units based on other monomers copolymerizable with the monomer represented by formula (2) is, in order of preference, 60 mol% or less, 50 mol% or less, less than 50 mol%, 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, and 1 mol% or less, based on the total polymerization units. It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer represented by formula (2) is substantially 0 mol%, and it is most preferable that the polymer (2) does not contain polymerization units based on other monomers.

[0499] The lower limit of the weight average molecular weight (Mw) of the polymer (2) is, in order of preference, 1.0×10 4 That's it, 1.4 x 10 4 That's it, 1.9 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 The upper limit of the weight average molecular weight (Mw) of the polymer (2) 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 4Below, 40.0 x 10 4 When the weight average molecular weight (Mw) of the polymer (2) is within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0500] The lower limit of the number average molecular weight (Mn) of the polymer (2) is, in order of preference, 0.5×10 4 That's it, 0.7 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 it, 1.6 x 10 4 That's it, 1.8 x 10 4 The upper limit of the number average molecular weight (Mn) of the polymer (2) 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 , 20.0×10 4 By having the number average molecular weight (Mn) of the polymer (2) within the above range, it is possible to obtain primary particles of PTFE having a smaller aspect ratio.

[0501] The molecular weight distribution (Mw / Mm) of the polymer (2) is preferably 3.0 or less, more preferably 2.7 or less, even more preferably 2.4 or less, still more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.9 or less. By having the molecular weight distribution (Mw / Mm) of the polymer (2) within the above range, primary particles of PTFE having a smaller aspect ratio can be obtained.

[0502] 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 measurement by GPC is not possible, the number average molecular weight of the polymer (2) 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.

[0503] The polymer (2) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and representative terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used in the formation of the polymer (2), or are generated during the chain transfer reaction.

[0504] The polymer (2) preferably 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 ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR.

[0505] 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.

[0506] The ion exchange capacity of the polymer (2) 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, 2.50 meq / g or more, 2.60 meq / g or more, 3.00 meq / g or more, and 3.50 meq / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (2) and is calculated from the composition of the polymer (2).

[0507] In polymer (2), the ionic (anionic) groups are typically distributed along the polymer backbone. Polymer (2) comprises a polymer backbone with recurring side chains attached to the backbone, which side chains preferably carry ionic groups.

[0508] Polymer (2) preferably comprises an ionizable group having a pKa of less than 10, more preferably less than 7. The ionizable group of polymer (2) is preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, and phosphate.

[0509] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or to the respective acids capable of forming salts. When salts are used, preferably the salts are alkali metal or ammonium salts. A preferred ionic group is the sulfonate group.

[0510] The polymer (2) 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, for example, by dynamic light scattering (DLS). On the other hand, the particle size of a water-insoluble polymer can be measured, for example, by dynamic light scattering (DLS).

[0511] The polymer (2) has a weight average molecular weight (Mw) of 1.4×10 4The above polymer is a novel polymer, and can be produced in the same manner as in the production of polymer (1), except that monomer (1) is replaced with monomer (2).

[0512] As the polymer (2), the polymer (1) is preferable.

[0513] It is preferable that the polymer (2) used in the second production method of the present disclosure does not substantially contain dimers and trimers of the monomer (2). The dimers and trimers of the monomer (2) are usually generated when the monomer (2) is polymerized to obtain the polymer (2). The content of the dimers and trimers in the polymer (2) 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 (2).

[0514] The dimer and trimer contents in the polymer (2) can be measured in the same manner as in the measurement of the dimer and trimer contents in the polymer (1).

[0515] The content of the fraction having a molecular weight of 3000 or less in the polymer (2) 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 0.6% or less, based on the polymer (2). 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 by 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.

[0516] The content of the fraction having a molecular weight of 2000 or less in the polymer (2) 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 polymer (2). 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 by 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.

[0517] The content of the fraction having a molecular weight of 1500 or less in the polymer (2) 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 polymer (2). 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.

[0518] The content of the fraction having a molecular weight of 1000 or less in the polymer (2) 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 polymer (2). 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.

[0519] By using a polymer (2) that is substantially free of dimers and trimers during polymerization of TFE in an aqueous medium, PTFE that is substantially free of dimers and trimers of the monomer (2) can be produced.

[0520] The polymer (2) is a polymer containing a polymerization unit (2) based on the monomer (2). The polymer (2) used in the present disclosure is preferably a polymer from which a dimer (a polymer containing two polymerization units (2)) and a trimer (a polymer containing three polymerization units (2)) have been substantially removed from the polymer (2) containing two or more polymerization units (2).

[0521] The molecular weight of the monomer (2) is preferably 500 or less, and more preferably 400 or less. That is, the polymer (2) preferably does not substantially contain dimers and trimers having a molecular weight of 1,500 or less, and more preferably does not substantially contain dimers and trimers having a molecular weight of 1,200 or less.

[0522] The second production method of the present disclosure preferably includes a step of polymerizing a monomer (2) represented by general formula (2) to obtain a crude composition containing a polymer of monomer (2), and a step of removing dimers and trimers of monomer (2) contained in the crude composition from the crude composition to obtain a polymer (2) having a content of dimers and trimers of monomer (2) of 1.0 mass% or less, based on polymer (2).

[0523] The polymerization of the monomer (2) can be carried out by the same method as the polymerization of the monomer (1) described above. In the method for producing PTFE of the present disclosure, the monomer (2) may be copolymerized with another monomer. The other monomer is as described above as the other monomer to be copolymerized with the monomer (1). The constitution of the copolymer obtained as the polymer (2) is also the same as that of the polymer (1).

[0524] In the second production method of the present disclosure, the polymerization of the monomer (2) is preferably carried out in an aqueous medium substantially in the absence of a fluorine-containing surfactant (excluding the monomer (2) represented by general formula (2)).

[0525] 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 even more preferably 1 ppb by mass or less.

[0526] The fluorine-containing surfactant is as described above in the explanation of the polymerization of TFE.

[0527] After the polymerization of the monomer (2), the dimer and trimer of the monomer (2) contained in the crude composition obtained by the polymerization of the monomer (2) are removed from the crude composition. The means for removing the dimer and trimer are as described above.

[0528] By appropriately selecting the means for removing dimers and trimers, it is also possible to remove fractions having a molecular weight of 3000 or less, fractions having a molecular weight of 2000 or less, fractions having a molecular weight of 1500 or less, and fractions having a molecular weight of 1000 or less.

[0529] The polymerization of TFE can be carried out by the above-mentioned method, except for using the polymer (2). As mentioned above, a modified monomer may be polymerized together with TFE. By using the modified monomer, PTFE having a small aspect ratio can be easily produced. In particular, it is preferable to add the modified monomer to the polymerization system at the beginning of the polymerization of TFE. In the above polymerization, it is preferable to add a modified monomer copolymerizable with TFE before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, preferably before it reaches 5.0% by mass.

[0530] The present disclosure also provides a polymer (1) comprising polytetrafluoroethylene having a primary particle aspect ratio of less than 2.00 and a monomer (1) represented by general formula (1), the weight average molecular weight of the polymer (1) being 1.0×10 4The present disclosure also relates to a composition having the above-mentioned polymerized units (1) based on monomer (1) in an amount of 40 mol % or more relative to all polymerized units constituting polymer (1) (hereinafter, sometimes referred to as the first composition of the present disclosure).

[0531] The first composition of the present disclosure can be produced by the first production method of the present disclosure using polymer (1).

[0532] The first composition of the present disclosure may be a PTFE aqueous dispersion in which primary particles of PTFE are dispersed in an aqueous medium. The aqueous dispersion may be any of the aqueous dispersion obtained by carrying out the above-mentioned polymerization, the dispersion obtained by concentrating the aqueous dispersion or subjecting it to a dispersion stabilization treatment, and the dispersion obtained by dispersing a powder made of PTFE in an aqueous medium in the presence of the above-mentioned surfactant. The composition of the present disclosure may also be a PTFE powder. The PTFE powder is obtained, for example, by coagulating PTFE in the PTFE aqueous dispersion by a known method.

[0533] 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, based on 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, based on PTFE.

[0534] 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 ... The measurement methods of each polymer described in JP 2012 / 082703 A, WO 2012 / 082454 A, WO 2012 / 082451 A, WO 2006 / 135825 A, WO 2004 / 067588 A, WO 2009 / 068528 A, JP 2004-075978 A, JP 2001-226436 A, WO 1992 / 017635 A, WO 2014 / 069165 A, JP 11-181009 A, etc. are described. As a method for measuring the content of the polymer (1), the measurement methods of each polymer described therein can be used.

[0535] In the first composition of the present disclosure, the content of dimers and trimers of monomer (1) in polymer (1) is preferably 1.0 mass% or less relative to polymer (1). The content of dimers and trimers in the first composition of the present disclosure is 1.0 mass% or less relative to polymer (1), 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.

[0536] The contents of dimer and trimer of polymer (1) in the first composition of the present disclosure can be measured by the same method as for the contents of dimer and trimer in polymer (1).

[0537] Polymer (1) in the first composition of the present disclosure may contain, or may not contain, a fraction having a molecular weight of 3,000 or less, a fraction having a molecular weight of 2,000 or less, a fraction having a molecular weight of 1,500 or less, or a fraction having a molecular weight of 1,000 or less, in the same content as polymer (1) used in the first production method of the present disclosure.

[0538] The present disclosure also provides a polymer (2) comprising PTFE having a primary particle aspect ratio of less than 2.00 and a monomer (2) represented by general formula (2), the weight average molecular weight of the polymer (2) being 1.0×10 4 The present disclosure also relates to a composition (hereinafter, sometimes referred to as the second composition of the present disclosure) in which the ion exchange capacity of polymer (2) is 2.2 meq / g or more, and the content of polymerization units (2) based on monomer (2) is 40 mol % or more based on all polymerization units constituting polymer (2).

[0539] The second composition of the present disclosure can be produced by the second production method of the present disclosure using polymer (2).

[0540] The second composition of the present disclosure may be a PTFE aqueous dispersion in which primary particles of PTFE are dispersed in an aqueous medium. The aqueous dispersion may be any of the aqueous dispersion obtained by carrying out the above-mentioned polymerization, the dispersion obtained by concentrating the aqueous dispersion or subjecting it to a dispersion stabilization treatment, and the powder made of PTFE dispersed in an aqueous medium in the presence of the above-mentioned surfactant. The composition of the present disclosure may also be a PTFE powder. The PTFE powder is obtained, for example, by coagulating PTFE in the PTFE aqueous dispersion by a known method.

[0541] The content of polymer (2) 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, based on PTFE. The content of polymer (2) 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, based on PTFE.

[0542] The content of polymer (2) 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 ... The measurement methods of the respective polymers described in JP 2012 / 082703 A, WO 2012 / 082454 A, WO 2012 / 082451 A, WO 2006 / 135825 A, WO 2004 / 067588 A, WO 2009 / 068528 A, JP 2004-075978 A, JP 2001-226436 A, WO 1992 / 017635 A, WO 2014 / 069165 A, and JP 11-181009 A are described. As a method for measuring the content of the polymer (2), the measurement methods of the respective polymers described therein can be used.

[0543] In the second composition of the present disclosure, the content of dimers and trimers of monomer (2) in polymer (2) is preferably 1.0 mass% or less relative to polymer (2). The content of dimers and trimers in the second composition of the present disclosure is 1.0 mass% or less relative to polymer (2), 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.

[0544] The dimer and trimer contents of polymer (2) 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).

[0545] Polymer (2) in the second 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 polymer (2) used in the second production method of the present disclosure.

[0546] In one embodiment of the first composition of the present disclosure and the second composition of the present disclosure, a fluorine-containing surfactant is contained. The composition containing a fluorine-containing surfactant has an advantage that it can be stably produced with high productivity using the fluorine-containing surfactant.

[0547] In one embodiment of the first composition of the present disclosure 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 needs to be produced by polymerizing TFE without using a fluorine-containing surfactant, but the production method of the present disclosure using the polymer (2) makes it possible to produce the composition.

[0548] In the present disclosure, "substantially free of fluorinated surfactant" means that the content of fluorinated surfactant in the composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, still more preferably 1 ppb by mass or less, and particularly preferably below the detection limit of the fluorinated surfactant as measured by liquid chromatography-mass spectrometry (LC / MS).

[0549] The content of the fluorine-containing surfactant can be quantified 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 a match with the structural formula of the candidate fluorine-containing surfactant is confirmed. Then, aqueous solutions containing five or more levels of the confirmed 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 for each 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.

[0550] The first composition of the present disclosure and the second composition of the present disclosure contain primary particles of PTFE having an aspect ratio of less than 2.00.

[0551] The aspect ratio is the aspect ratio of the primary particle of PTFE. The upper limit of the aspect ratio of the primary particle 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. The manufacturing method of the present disclosure can obtain primary particles having a relatively small aspect ratio. In addition, an even smaller aspect ratio of the primary particle can be obtained, for example, by adding a modified monomer to the polymerization system at the beginning of the polymerization of TFE.

[0552] When the aspect ratio of PTFE is measured using an aqueous PTFE dispersion, an aqueous PTFE dispersion adjusted to a polymer solids concentration of about 1.0% by mass is prepared, observed with a scanning electron microscope (SEM), and randomly selected 400 or more particles are subjected to image processing, and the aspect ratio can be calculated from the average ratio of the long diameter to the short diameter. When the aspect ratio of PTFE is measured using a powder of PTFE, the PTFE powder is irradiated with an electron beam, then added to an aqueous solution of a fluorine-containing surfactant, and ultrasonic waves are applied to redisperse the powder in the aqueous solution to prepare an aqueous PTFE dispersion. The aspect ratio can be calculated by the above-mentioned method using the aqueous dispersion prepared in this way.

[0553] The PTFE in the second composition of the present disclosure may have the same structure as the PTFE obtained by the first manufacturing 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.

[0554] The content of the modified PTFE in the polymerized units based on the modified monomer (hereinafter also referred to as "modified monomer units") is preferably in the range of 0.00001 to 1 mass% based on the total polymerized units of PTFE. The lower limit of the content of the modified monomer units is more preferably 0.0001 mass%, further preferably 0.001 mass%, and further more preferably 0.005 mass%. The upper limit of the content of the modified monomer units is, in order of preference, 0.80 mass%, 0.70 mass%, 0.50 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, and 0.05 mass%. In the present disclosure, the modified monomer units refer to a part of the molecular structure of PTFE that is derived from the modified monomer.

[0555] 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. In addition, the content of each monomer unit constituting PTFE can also be calculated from the amount of modified monomer added used in polymerization.

[0556] When the modified monomer includes the modified monomer (A), the content of the polymerized units based on the modified monomer (A) is preferably in the range of 0.00001 to 1.0 mass% based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001 mass%, more preferably 0.0005 mass%, even more preferably 0.001 mass%, and even more preferably 0.005 mass%. The preferred order is 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0557] The PTFE has an average primary particle diameter of 500 nm or less, preferably 400 nm or less, and more preferably 350 nm or less. The manufacturing method of the present disclosure can obtain primary particles having a relatively small average primary particle diameter. Furthermore, an even smaller average primary particle diameter of the primary particles can be obtained, for example, by adding a modified monomer to the polymerization system at the initial stage of polymerization of TFE. 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.

[0558] The average primary particle size of the PTFE primary particles can be measured by dynamic light scattering. First, a PTFE aqueous dispersion with a polymer solids concentration adjusted to about 1.0 mass% is prepared, and the average primary particle size can be measured using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and an accumulation number of 70. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method.

[0559] 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. Also, it is preferably 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.

[0560] 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) or polymer (2). 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.

[0561] 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) or polymer (2).

[0562] The 0.1% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, 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 the air in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0563] 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) or polymer (2).

[0564] The 1.0% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, 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 in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0565] The peak temperature of PTFE is preferably 347°C or less, more preferably 346°C or less, and further preferably 345°C or less.

[0566] The peak temperature of PTFE can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer). The peak temperature can be identified as the temperature that corresponds to the maximum value that appears on a differential thermal (DTA) curve obtained by heating PTFE that has not been heated to a temperature of 300°C or higher at a rate of 10°C / min using a TG / DTA (thermogravimetric / differential thermal analyzer).

[0567] The PTFE composition of the present disclosure can be suitably used for the above-mentioned applications.

[0568] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0569] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0570] The values ​​in the examples were measured by the following methods.

[0571] <Oxygen concentration in 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.

[0572] <Method of measuring weight average molecular weight (Mw) and number average molecular weight (Mn)> The Mw and Mn of the polymers (e.g., polymer I) were determined by gel permeation chromatography (GPC) using an Agilent Technologies 1260 Infinity II column (Tosoh TSKgel G3000PW XLThe measurement was performed using a column of 1000 µL ...

[0573] <Method for measuring the content of dimers and trimers of monomers (e.g., monomer I) in polymers (e.g., polymer I)> (1) Extraction from aqueous solution The solid content of the aqueous solution of the polymer was measured, and an amount of the aqueous solution equivalent to 0.2 g of the solid content of the polymer was weighed. Then, the aqueous solution was combined with the water contained in the aqueous solution, and water and methanol were added so that the volume ratio of water to methanol was 50 / 50 (volume %) to obtain a mixed solution containing the polymer, water, and methanol. Then, the obtained mixed solution was filtered using an ultrafiltration disk (molecular weight cutoff 3000 Da), and a recovery liquid containing the polymer was collected. The recovered liquid was analyzed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD) to obtain a chromatogram of the recovered liquid. The contents of dimer and trimer of the monomer contained in the recovered solution were determined by converting the integral values ​​of the peaks derived from dimer and trimer of the monomer appearing in the chromatogram of the recovered solution into the contents of dimer and trimer of the monomer using a calibration curve.

[0574] (2) Monomer calibration curve Five levels of methanol standard solutions of monomers with known contents ranging from 1 ng / mL to 100 ng / mL were prepared, and measurements were performed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The relationship between the content of each monomer and the peak integral value for that content was plotted to create a calibration curve (first order approximation) for each monomer. Next, the calibration curves (first order approximation) for each monomer were used to create calibration curves for the dimers and trimers of each monomer.

[0575] Measurement equipment configuration and LC-MS measurement conditions

Table 1

[0576] The limit of quantification in this measuring instrument configuration is 1 ng / mL.

[0577] <Concentration of aqueous solution of polymer (such as Polymer I) (solid content concentration)> Approximately 1 g of the polymer aqueous solution was dried in a vacuum dryer under the conditions of 60 °C for 60 minutes, the mass of the heat residue was measured, and the value obtained by expressing the ratio of the mass of the heat residue to the mass of the polymer aqueous solution (1 g) as a percentage was adopted.

[0578] <Content of modified monomer unit> The content of the HFP unit was determined by multiplying the ratio of the absorbance at 982 cm -1 to the absorbance at 935 cm -1 by 0.3 based on the infrared absorbance obtained by preparing a thin film disk by pressing PTFE powder and performing FT-IR measurement of the thin film disk.

[0579] <Solid content concentration of aqueous dispersion containing PTFE> 1 g of the aqueous dispersion was dried in a blower dryer under the conditions of 150 °C for 60 minutes, and the value obtained by expressing the ratio of the mass of the heat residue to the mass of the aqueous dispersion (1 g) as a percentage was adopted.

[0580] <Average primary particle size> An aqueous PTFE dispersion with a solid content concentration adjusted to approximately 1.0 mass% was prepared and measured at 25 °C for 70 integrations using an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.). The refractive index of the solvent (water) was 1.3328 and the viscosity of the solvent (water) was 0.8878 mPa·s.

[0581] <Standard specific gravity (SSG)> Measurement was carried out by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895-89.

[0582] <Aspect ratio> An aqueous dispersion diluted to a solid content concentration of about 1% by mass was observed with a scanning electron microscope (SEM), and image processing was performed on more than 400 randomly extracted particles, and it was determined from the average of the ratio of the major axis to the minor axis.

[0583] <Peak temperature> The peak temperature was measured using a TG / DTA (simultaneous differential thermal and thermogravimetric analyzer) by accurately weighing about 10 mg of PTFE powder without a heating history at a temperature of 300 °C or higher and storing it in a dedicated aluminum pan. The peak temperature was obtained by heating the aluminum pan from 25 °C to 600 °C at a rate of 10 °C / min in an air atmosphere to obtain a differential thermal (DTA) curve, and the temperature corresponding to the maximum value in the obtained differential thermal (DTA) curve was taken.

[0584] <Content of polymer (such as Polymer I) in PTFE powder> The content of the polymer contained in the PTFE powder is solid 19 It was determined from the spectrum obtained by F-MAS NMR measurement.

[0585] <Extrusion pressure> The extrusion pressure was determined by the following method in accordance with the method described in JP-A-2002-201217. To 100 g of PTFE powder, 21.7 g of a lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon) was added and mixed in a glass bottle at room temperature for 3 minutes. Then, the glass bottle was left at room temperature (25 °C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin was paste extruded through an orifice (diameter 2.5 mm, land length 11 mm, lead angle 30°) at room temperature with a reduction ratio of 100:1 to obtain a uniform bead (extruded molded body). The extrusion speed, that is, the ram speed, was 20 inches / min (51 cm / min). The load at the time when the extrusion load reached an equilibrium state in the paste extrusion was measured and divided by the cross-sectional area of the cylinder used for the paste extrusion to calculate the extrusion pressure.

[0586] <Elongation test> The elongation test and the measurement of the breaking strength A were performed in accordance with the method described in JP-A-2002-201217, as described below. The bead obtained by the above paste extrusion was heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) was then cut to the appropriate length, clamped at each end with a clamp distance of 1.5 inches (38 mm) apart, and heated to 300°C in an air circulating oven. The clamps were then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) was achieved, and a stretch test (stretch test) was performed. The stretch method essentially followed the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. The stretch rate in the stretch method was 1000% / sec, and the total stretch was 2400%.

[0587] <Breaking strength A> The stretched bead (produced by stretching the bead) obtained in the above stretching test was clamped and fixed between movable jaws with a gauge length of 5.0 cm, and a tensile test was performed at 25°C and a speed of 300 mm / min, and the strength at the time of break was measured as breaking strength A.

[0588] <Stress relaxation time> It was determined by the following method in accordance with the method described in JP-A-2002-201217. Both ends of the stretched bead obtained in the stretch test above were connected to a fixture to produce a taut bead sample with a total length of 8 inches (20 cm). The oven was maintained at 390°C and the fixture was inserted into the oven through a (covered) slit in the side of the oven. The time required for the bead sample to break from the point of insertion into the oven was measured as the stress relaxation time.

[0589] <Appearance of stretched body> The appearance of the stretched bead (produced by stretching the bead) obtained in the above stretching test was visually observed and evaluated according to the following criteria. Uniform: The appearance of the stretched bead was uniform. Non-uniformity: The appearance of the stretched bead was non-uniform, with cracks, ripples, and uneven density being observed in the stretched bead.

[0590] Preparation Example 1 Into a reactor, 10 g of CF2=CFOCF2CF2COOH (monomer I), 20 g of water, and ammonium persulfate (APS) in an amount equivalent to 0.5 mol% relative to the amount of monomer I were added, and stirred at 52°C under N2 flow. 24 hours after the addition of APS, an amount of APS equivalent to 1.0 mol% was added, and 48 hours after the addition, an amount of APS equivalent to 1.5 mol% was further added, and the mixture was stirred at 52°C for a total of 72 hours to obtain an aqueous polymer I solution I-1 containing polymer I, which is a homopolymer of monomer I. The oxygen concentration in the reactor was in the range of 15 ppm by volume to 40 ppm by volume.

[0591] Water was added to the obtained aqueous solution I-1 containing polymer I to adjust the concentration of polymer I to 2.0% by mass, and then ultrafiltration was performed by contacting the ultrafiltration membrane (molecular weight cutoff 6000 Da, made of polysulfone) at 25°C and a water pressure of 0.1 MPa. Ultrafiltration was continued while appropriately injecting water until the filtrate was finally dissolved in an amount of water 7 times the amount of the aqueous solution, and an aqueous solution I-2 of polymer I was obtained. The concentration of the obtained aqueous solution was 2.1% by mass.

[0592] The aqueous solution obtained by ultrafiltration was analyzed. The weight average molecular weight (Mw) of the obtained polymer I was 1.7×10 4 , number average molecular weight (Mn) is 1.1×10 4 The content of dimers and trimers in the aqueous solution obtained by carrying out ultrafiltration was 0.1% by mass or less, based on Polymer I. The content of fractions having a molecular weight of 3000 or less in the aqueous solution obtained by carrying out ultrafiltration was 0.1% by mass or less.

[0593] Example 1 In a 1 L glass reactor equipped with a stirrer, 504 g of deionized water, 30 g of paraffin wax, and 26.2 g of the aqueous solution of polymer I-2 were placed. The reactor contents were then heated to 70°C while being aspirated and purged with TFE monomer at the same time to remove oxygen from the reactor. The contents were then stirred at 540 rpm. 0.54 g of HFP was added to the reactor, and then TFE monomer was added until the pressure reached 0.73 MPaG. 2.75 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor, and the reactor was brought to a pressure of 0.83 MPaG. After the initiator was injected, a drop in pressure occurred and the start of polymerization was observed. TFE monomer was added to the reactor to maintain the pressure, and polymerization was continued until about 140 g of TFE monomer had reacted. The reactor was then vented until the pressure in the reactor reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the aqueous PTFE dispersion. The solid content of the resulting PTFE aqueous dispersion was 21.6% by mass, and the average primary particle size was 176 nm. The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, and coagulated under high-speed stirring conditions. The coagulated wet powder was dried at 210°C for 18 hours. The results are shown in Table 2.

[0594] Example 2 Polymerization was carried out in the same manner as in Example 1, except that after the aqueous solution of polymer I I-2 was added to the reactor, aqueous ammonia was further added to adjust the pH to 8.9 before heating the content of the reactor. The solids concentration of the resulting PTFE aqueous dispersion was 21.4% by mass, and the average primary particle size was 222 nm. The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, and coagulated under high-speed stirring conditions. The coagulated wet powder was dried at 210°C for 18 hours. The results are shown in Table 2.

[0595] Example 3 In a 6L SUS reactor equipped with a stirrer, 3223g of deionized water, 104g of paraffin wax, 341g of polymer I aqueous solution I-2, and 3.58g of 0.1% by mass aqueous isopropanol solution were placed. The reactor contents were then heated to 70°C while being aspirated and purged with TFE to remove oxygen from the reactor, and the contents were stirred. After adding 3.2g of HFP to the reactor, TFE was added until the pressure reached 0.73MPaG. 17.9mg of ammonium persulfate (APS) initiator dissolved in 20g of deionized water was injected into the reactor, and the reactor was brought to a pressure of 0.83MPaG. After the injection of the initiator, a drop in pressure occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 0.78MPaG. When the amount of TFE consumed in the reaction reached about 180g, the supply of TFE and stirring were stopped.

[0596] The gas in the reactor was then slowly released until the pressure in the reactor reached 0.02 MPaG. TFE was then fed until the pressure in the reactor reached 0.78 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 1250 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented until it reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solid content concentration of the obtained PTFE aqueous dispersion was 26.0 mass%, and the average primary particle size was 175 nm.

[0597] The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, coagulated under high-speed stirring conditions, and the coagulated wet powder was dried at 210° C. for 18 hours. Various physical properties of the resulting PTFE powder were measured. The results are shown in Table 2.

[0598] The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, coagulated under high-speed stirring conditions, and the coagulated wet powder was dried at 240° C. for 18 hours. The various physical properties of the resulting PTFE powder were measured. The results are shown in Table 3.

[0599] Preparation Example 2 30 g of CF2=CFOCF2CF(CF3)OCF2CF2COOH (monomer J), 60 g of water, ammonia in an amount equivalent to 0.5 mol % relative to the amount of monomer J, and ammonium persulfate (APS) in an amount equivalent to 2.0 mol % relative to the amount of monomer J were added to a reactor, and the mixture was stirred at 52°C for 72 hours under N2 flow. The oxygen concentration in the reactor was in the range of 20 ppm by volume to 50 ppm by volume. An aqueous solution of polymer J J-1 containing polymer J, which is a homopolymer of monomer J, was obtained.

[0600] The obtained aqueous solution of polymer J-1 was added with water and an amount of ammonia equivalent to 0.4 equivalents relative to the amount of polymer J to adjust the concentration of polymer J to 3.0 mass %. The solution was then contacted with an ultrafiltration membrane (molecular weight cutoff 6000 Da, made of polysulfone) at 25°C and a water pressure of 0.1 MPa to perform ultrafiltration, thereby obtaining aqueous solution of polymer J-2.

[0601] The weight average molecular weight (Mw) of the obtained polymer J was 1.4 × 10 4 , number average molecular weight (Mn) is 0.9×10 4 The concentration of polymer J in the aqueous solution of polymer J-2 obtained by ultrafiltration was 1.9% by mass. The content of dimers and trimers in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less, based on polymer J. The content of fractions having a molecular weight of 3000 or less in the aqueous solution obtained by ultrafiltration was 0.1% by mass or less.

[0602] Example 4 Polymerization was carried out in the same manner as in Example 1, except that 26.2 g of the polymer I aqueous solution I-2 in Example 1 was replaced with 57.9 g of the polymer J aqueous solution J-2, 504 g was replaced with 473 g of deionized water, and about 140 g of the TFE monomer was replaced with about 80 g of the TFE monomer. The solid content concentration of the obtained PTFE aqueous dispersion was 13.0 mass%, and the average primary particle size was 119 nm. The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, and coagulated under high-speed stirring conditions. The coagulated wet powder was dried at 210°C for 18 hours. The results are shown in Table 2.

[0603] [Table 2]

[0604] [Table 3]

Claims

1. A method for producing polytetrafluoroethylene, comprising the steps of: polymerizing tetrafluoroethylene in an aqueous medium in the presence of a polymer (1) to obtain polytetrafluoroethylene, The polymer (1) is a polymer of a monomer (1) represented by general formula (1) and has a weight average molecular weight of 1.0×10 ４ or more, the content of polymerization units (1) based on the monomer (1) is 40 mol % or more based on all polymerization units constituting the polymer (1), and the content of dimers and trimers of the monomer (1) is 1.0 mass % or less based on the polymer (1). CF ２ =CF(-O-Rf-A) (1) (In the formula, 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. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ is H or an organic group.

2. The weight average molecular weight of the polymer (1) is 1.4×10 ４ The method according to claim 1, wherein

3. The method according to claim 1 or 2, wherein A is -COOM.

4. The method according to any one of claims 1 to 3, further comprising polymerizing a modifying monomer.

5. A crude composition containing a polymer of the monomer (1) is obtained by polymerizing the monomer (1), The production method according to any one of claims 1 to 4, wherein a polymer (1) having a content of dimers and trimers of the monomer (1) of 1.0 mass% or less, based on the polymer (1), is obtained by removing dimers and trimers of the monomer (1) contained in the crude composition from the crude composition.

6. The present invention comprises polytetrafluoroethylene having a primary particle aspect ratio of less than 2.00 and a polymer (1) of a monomer (1) represented by general formula (1), The weight average molecular weight of the polymer (1) is 1.0×10 ４ That's all. A composition, wherein the content of polymerized units (1) based on monomer (1) is 40 mol % or more based on all polymerized units constituting polymer (1). CF ２ =CF(-O-Rf-A) (1) (In the formula, 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. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ is H or an organic group.

7. The weight average molecular weight of the polymer (1) is 1.4×10 ４ The composition according to claim 6, wherein

8. The composition according to claim 6 or 7, wherein A is -COOM.

9. The composition according to any one of claims 6 to 8, wherein the polytetrafluoroethylene contains tetrafluoroethylene units and modified monomer units.

10. The composition according to any one of claims 6 to 9, 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).

11. The polymer (2) contains polytetrafluoroethylene having a primary particle aspect ratio of less than 2.00 and a monomer (2) represented by general formula (2), The weight average molecular weight of the polymer (2) is 1.0×10 ４ That's all. The ion exchange capacity of the polymer (2) is 2.2 meq / g or more, A composition, wherein the content of polymerized units (2) based on the monomer (2) is 40 mol % or more based on all polymerized units constituting the polymer (2). CX ２ =CY(-O-Rf-A) (2) (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; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond or a keto group having 2 to 100 carbon atoms; A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ is H or an organic group.

12. The weight average molecular weight of the polymer (2) is 1.4×10 ４ The composition according to claim 11,

13. The composition according to claim 11 or 12, wherein A is -COOM.

14. The composition according to any one of claims 11 to 13, wherein the polytetrafluoroethylene contains tetrafluoroethylene units and modified monomer units.

15. The composition according to any one of claims 11 to 14, wherein the content of dimers and trimers of the monomer (2) in the polymer (2) is 1.0 mass% or less based on the polymer (2).

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