Method for producing aqueous fluoropolymer dispersion

Abstract

Provided is a method for producing an aqueous fluoropolymer dispersion, with which an aqueous dispersion that contains a fluoropolymer is produced by polymerizing a fluoromonomer in the presence of the cyclic compound set forth in the description and an aqueous medium.

Description

Method for producing aqueous fluoropolymer dispersion

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

[0002] Patent Document 1 discloses a method for polymerizing a fluorine-containing monomer in the presence of a compound (1) having an aromatic ring, a hydrophilic group, and an unsaturated double bond, and an aqueous medium, to form a polymer having —CH in the main chain. ２ The present invention describes a method for producing an aqueous dispersion of a fluorine-containing elastomer containing fluoroelastomer.

[0003] International Publication No. 2022 / 019241

[0004] The present disclosure aims to provide a novel manufacturing method for producing an aqueous fluoropolymer dispersion.

[0005] According to the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion, which comprises polymerizing a fluoromonomer in the presence of at least one cyclic compound selected from the group consisting of a compound (1) represented by formula (1), a compound (2) represented by formula (2), and a compound (3) represented by formula (3), and an aqueous medium to produce an aqueous dispersion containing a fluoropolymer. (The symbols in the formula are as described below.) Formula (2): (The symbols in the formula are as described below.) Formula (3): (The symbols in the formula are as described below.)

[0006] According to the present disclosure, a novel production method for producing an aqueous fluoropolymer dispersion can be provided.

[0007] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0008] In the present disclosure, fluororesins are partially crystalline fluoropolymers, or fluoroplastics. Fluororesins have a melting point and are thermoplastic, but may be melt-processable or non-melt-processable.

[0009] In the present disclosure, melt-processable means that the polymer can be melted and processed using conventional processing equipment such as an extruder, an injection molding machine, etc. Therefore, melt-processable fluororesins usually have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0010] In this disclosure, a fluoroelastomer is an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) appearing in differential scanning calorimetry (DSC) (heating rate 10°C / min) or differential thermal analysis (DTA) (heating rate 10°C / min) of the fluoropolymer is 4.5 J / g or less. Fluorine-containing elastomers exhibit elastomeric properties by crosslinking. Elastomeric properties refer to the ability of a polymer to be stretched and to retain its original length when the force required to stretch the polymer is no longer applied.

[0011] In the present disclosure, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer having a content of tetrafluoroethylene units relative to all polymer units of 99 mol % or more.

[0012] In the present disclosure, the fluororesin (excluding polytetrafluoroethylene) and the fluorine-containing elastomer are both preferably fluoropolymers having a tetrafluoroethylene content of less than 99 mol% relative to all polymerized units.

[0013] In the present disclosure, the content of each monomer constituting the fluoropolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0014] In the present disclosure, the term "organic group" refers to a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. The organic group is preferably an alkyl group which may have one or more substituents.

[0015] 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.).

[0016] 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.).

[0017] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0018] In the manufacturing method of the present disclosure, a fluoromonomer is polymerized in the presence of a cyclic compound and an aqueous medium to produce an aqueous fluoropolymer dispersion.

[0019] (Cyclic Compound) In the production method of the present disclosure, at least one cyclic compound selected from the group consisting of Compound (1), Compound (2), and Compound (3) is used. These cyclic compounds are preferred because, due to the condensed rings, they have fewer carbon-hydrogen bonds that may cause chain transfer reactions in the polymerization reaction compared to non-cyclic compounds or non-condensed cyclic compounds having the same number of carbon atoms.

[0020] (Compound (1)) Compound (1) is represented by formula (1). Formula (1):

[0021] In formula (1), R １１ , R １２ and R １３are independently polyvalent linking groups having 1 to 8 atoms which may contain a heteroatom. Examples of polyvalent linking groups include divalent to pentavalent linking groups. Examples of polyvalent linking groups include saturated or unsaturated hydrocarbon groups having 2 to 8 carbon atoms, and saturated or unsaturated hydrocarbon groups having 1 to 7 carbon atoms which contain an ether oxygen atom. Either hydrocarbon group may be a divalent to pentavalent hydrocarbon group. Examples of heteroatoms include an oxygen atom (O), a nitrogen atom (N), a sulfur atom (S), a boron atom (B), and a phosphorus atom (P). Preferred heteroatoms are O or N, and more preferred are O.

[0022] R １１ R is preferably a hydrocarbon group having 1 or 2 carbon atoms. １１ The hydrocarbon group of R may be divalent or trivalent. １２ and R １３ R is preferably a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom. １２ and R １３ The hydrocarbon group may be divalent to pentavalent.

[0023] R １１ , R １２ and R １３ Any two of R may be linked to each other to form one or more rings. １２ and one carbon atom constituting R １３ may be bonded to one carbon atom constituting R to form a ring. １１ and one carbon atom constituting R １３ is bonded to one carbon atom constituting R to form a ring, and １２ and one carbon atom constituting R １３ may be bonded to one of the carbon atoms constituting the ring to form a ring.

[0024] X １１ and X １２ are independently a carbon atom (C) or a nitrogen atom (N). １１ and X １２ In C or N, R １１ , R １２ and R１３ is bonded. X １１ and X １２ When one or both of are C, C may contain R １１ , R １２ and R １３ In addition, a hydrogen atom (H) may be bonded, or a group represented by the formula: -R １４ -Z １１ or a group represented by the formula: -R １４ -Z １１ Any substituent other than the group represented by the formula (I) may be bonded to the alkyl group. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0025] Ring A is R １１ , R １２ , X １１ and X １２ Ring B is a 4- to 18-membered ring formed by linking R １１ , R １３ , X １１ and X １２ are bonded to each other. Ring A and ring B are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring A and ring B is a non-aromatic ring.

[0026] The hydrocarbon ring of ring A and ring B is preferably a 4- to 18-membered saturated or unsaturated non-aromatic hydrocarbon ring, more preferably a 4- to 18-membered cycloalkane ring or a 4- to 18-membered cycloalkene ring, and still more preferably a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cyclobutene ring, a cyclopentene ring, or a cyclohexene ring.

[0027] The heterocycle of ring A and ring B is preferably a 4- to 18-membered saturated or unsaturated non-aromatic heterocycle, more preferably a 4- to 18-membered saturated non-aromatic heterocycle containing an oxygen atom or a 4- to 18-membered saturated non-aromatic heterocycle containing a nitrogen atom, and still more preferably an oxetane ring, a tetrahydrofuran ring, a tetrahydropyran ring, an azetidine ring, a pyrrolidine ring or a piperidine ring.

[0028] Ring A and ring B are each a group represented by the formula: -R １４ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (=O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0029] R forming ring A １２ and R forming ring B １３ may be bonded to another ring that shares at least one carbon-carbon bond with ring A. For example, when ring A is a cycloalkane ring, the cycloalkane ring that shares one carbon-carbon bond with ring A can be bonded to ring A to form a bicycloalkane ring together with ring A.

[0030] Formula: -R １４ -Z １１ is a substituent bonded to either or both of ring A and ring B. That is, in formula (1), a group represented by the formula: -R １４ -Z １１ is a group represented by R １１ , R １２ , R １３ , X １１ and X １２ is bound to one of

[0031] R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms. １４ -Z １１ When a plurality of groups represented by R １４ may be the same or different.

[0032] R １４ is preferably a single bond or an alkylene group. Examples of the alkylene group include linear or branched alkylene groups. The number of carbon atoms in the alkylene group is preferably 1 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 3 or less. Examples of the alkylene group include -CH ２ -, -CH ２CH ２ -, -CH ２ CH ２ CH ２ - or -CH(CH ３ ) CH ２ - is preferred, and -CH ２ - is more preferable.

[0033] R １４ is a single bond or -CH ２ - is preferred, and a single bond is more preferred.

[0034] Z １１ is a hydrophilic group. １４ -Z １１ When a plurality of groups represented by the formula １１ may be the same or different.

[0035] Z １１ As the ３ M, -OSO ３ M, -COOM, -P(=O)(OM) ２ , -OP(O)(OM) ２ , -B(OM) ２ Or -OB (OM) ２ is preferred, and —SO ３ M, -OSO ３ M or -COOM is more preferred, and -SO ３ M or -COOM is more preferred.

[0036] M is H, a metal atom, or NR ６ ４ , imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms.

[0037] R ６ are independently H or an organic group, and R ６ Any two of these may be bonded to each other to form a ring. The organic group is preferably an alkyl group. ６ As the group, H or C １－１０ is preferably an organic group of the formula １－４ More preferred are organic groups of the formula:１－４ More preferred is an alkyl group of the formula (I), and most preferred is H.

[0038] The metal atom may be a monovalent or divalent metal atom, preferably an alkali metal (Group 1) or alkaline earth metal (Group 2), more preferably Na, K or Li.

[0039] M is H, a metal atom, or NR ６ ４ is preferred, and H, Na, K or NR ６ ４ is more preferred, and H, Na, K or NH ４ is more preferable.

[0040] n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more. n is preferably an integer of 1 to 4, more preferably 1 or 2. When n is 2 or more, the formula: -R １４ -Z １１ The group represented by the following formula (I) can be bonded to either one or both of ring A and ring B.

[0041] In one embodiment, compound (1) does not contain a fluorine atom.

[0042] The compound (1) is preferably a compound represented by any one of formulas (1-1), (1-2) and (1-3).

[0043] Formula (1-1):

[0044] In formula (1-1), R １１１ is a hydrocarbon group having 1 or 2 carbon atoms. １１１ The hydrocarbon group may be divalent or trivalent, but is preferably divalent. １１１ The hydrocarbon group of X １１ and X １２ It bonds only with R １１２ and R １１３ It is preferred that the aryl group does not form one or more rings by linking to any of the aryl groups.

[0045] R １１２ and R１１３ are independently a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom. １１２ and R １１３ The hydrocarbon group may be divalent to pentavalent, and is preferably divalent. １１２ and R １１３ The hydrocarbon group of X １１ and X １２ It bonds only with R １１２ and R １１３ It is preferred that the aryl group does not form one or more rings by linking to any of the aryl groups.

[0046] X １１ and X １２ is independently C or N. １１ and X １２ In C or N, R １１１ , R １１２ and R １１３ is bonded. X １１ and X １２ When one or both of are C, C may contain R １１１ , R １１２ and R １１３ In addition, a hydrogen atom (H) may be bonded, or a group represented by the formula: -R １４ -Z １１ or a group represented by the formula: -R １４ -Z １１ Any substituent other than the group represented by the formula: -R １４ -Z １１ Examples of optional substituents other than the group represented by the formula (I) include an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0047] Ring A １ is R １１１ , R １１２ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ is R１１１ , R １１３ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ and ring B １ are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that ring A １ and ring B １ are all non-aromatic rings.

[0048] Ring A １ and ring B １ The hydrocarbon ring is preferably a 5- to 12-membered saturated or unsaturated non-aromatic hydrocarbon ring, more preferably a 5- to 12-membered cycloalkane ring or a 5- to 12-membered cycloalkene ring, and even more preferably a cyclopentane ring, a cyclohexane ring, a cyclopentene ring or a cyclohexene ring.

[0049] Ring A １ and ring B １ The heterocycle is preferably a 5- to 12-membered saturated or unsaturated non-aromatic heterocycle, more preferably a 5- to 12-membered saturated non-aromatic heterocycle containing an oxygen atom or a 5- to 12-membered saturated non-aromatic heterocycle containing a nitrogen atom, and still more preferably a tetrahydrofuran ring, a tetrahydropyran ring, a pyrrolidine ring or a piperidine ring.

[0050] Ring A １ and ring B １ is represented by the formula: -R １４ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (=O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0051] In one embodiment, ring A １ and ring B １ is not bonded to another ring that shares at least one carbon-carbon bond with it.

[0052] Formula: -R １４ -Z １１ is a group represented by ring A １and ring B １ That is, in formula (1-1), the substituent is a group represented by the formula: -R １４ -Z １１ is a group represented by R １１１ , R １１２ , R １１３ , X １１ and X １２ is bound to one of

[0053] R １４ , Z １１ and n is as defined above.

[0054] In one embodiment, the compound represented by formula (1-1) does not contain a fluorine atom.

[0055] Examples of the compound represented by formula (1-1) include (±)-10-camphorsulfonic acid, 2,3-norbornanedicarboxylic acid, norbornane-2-carboxylic acid, (S)-(+)-ketopinic acid, (+)-3-bromocamphor-8-sulfonic acid, (-)-3-bromocamphor-8-sulfonic acid, (-)-camphanic acid, 5-norbornene-2,3-dicarboxylic acid, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, bicyclo[2.2.2]octane-2-carboxylic acid, quinuclidine-3carboxylic acid, and salts thereof (such as sodium salts, potassium salts, and ammonium salts).

[0056] Formula (1-2):

[0057] In formula (1-2), R １１１ , R １１２ , R １１３ , X １１ , X １２ , ring A １ , ring B １ , R １４ , Z １１ and n is as defined above.

[0058] R １１２ and R １１３ are independently a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom.１１２ and R １１３ The hydrocarbon group may be divalent to pentavalent, preferably divalent to trivalent.

[0059] R １１４ is ring A １ R forming １１２ and any carbon atom of ring B １ R forming １１３ In formula (1-2), R is a hydrocarbon group having 1 or 2 carbon atoms that bridges any one of the carbon atoms in １１２ and R １１３ The hydrocarbon group of R １１４ are connected to each other via

[0060] In one embodiment, the compound represented by formula (1-2) does not contain a fluorine atom.

[0061] Examples of the compound represented by formula (1-2) include 1-adamantanecarboxylic acid, 1,3-adamantanediacetic acid, 1-adamantaneacetic acid, 3-noradamantanecarboxylic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0062] Formula (1-3):

[0063] In formula (1-3), R １４ , Z １１ and n is as defined above.

[0064] The compound represented by formula (1-3) has a cubane skeleton and a group represented by the formula: -R １４ -Z １１ and a group represented by the formula: -R １４ -Z １１ is bonded to any of the eight carbon atoms that constitute the cubane skeleton.

[0065] n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more. n is preferably an integer of 1 to 4, and more preferably 1 or 2.

[0066] In formula (1-3), the eight carbon atoms constituting the cubane skeleton, i.e., the six rings constituting the cubane skeleton, are all represented by the formula: -R １４ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0067] In one embodiment, the compound represented by formula (1-3) does not contain a fluorine atom.

[0068] As the compound (1), a compound represented by any one of formulas (1-1-1), (1-1-2), (1-1-3), (1-1-4), (1-1-5), (1-2-1), (1-2-2) and (1-3) is more preferable.

[0069] Formula (1-1-1):

[0070] Formula (1-1-2):

[0071] Formula (1-1-3):

[0072] Formula (1-1-4):

[0073] Formula (1-1-5):

[0074] Formula (1-2-1):

[0075] Formula (1-2-2):

[0076] Formula (1-3):

[0077] In each formula, R １４ , Z １１ and n are as defined above. １４ -Z １１It may have any substituent other than the group represented by the formula (1-1-2). For example, in formula (1-1-2), the hydrogen atom bonded to the carbon atom adjacent to the ether bond may be substituted with an oxo group (═O), thereby forming an ester bond together with the ether bond. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (═O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0078] In one embodiment, the compounds represented by formula (1-1-1), formula (1-1-2), formula (1-1-3), formula (1-1-4), formula (1-1-5), formula (1-2-1), formula (1-2-2), and formula (1-3) do not contain a fluorine atom.

[0079] Examples of the compound represented by formula (1-1-1) include (±)-10-camphorsulfonic acid, norbornane-2-carboxylic acid, (+)-3-bromocamphor-8-sulfonic acid, 2,3-norbornanedicarboxylic acid, (S)-(+)-ketopinic acid, (-)-3-bromocamphor-8-sulfonic acid, and salts thereof (such as sodium salts, potassium salts, and ammonium salts).

[0080] The compound represented by formula (1-1-2) includes (-)-camphanic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0081] Examples of the compound represented by formula (1-1-3) include 5-norbornene-2,3-dicarboxylic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0082] Examples of the compound represented by formula (1-1-4) include bicyclo[2.2.2]octane-1,4-dicarboxylic acid, bicyclo[2.2.2]octane-2-carboxylic acid, and salts thereof (such as sodium salts, potassium salts, and ammonium salts).

[0083] The compound represented by formula (1-1-5) includes quinuclidine-3-carboxylic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0084] Examples of the compound represented by formula (1-2-1) include 1-adamantanecarboxylic acid, 1-adamantaneacetic acid, 1,3-adamantanediacetic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0085] Examples of the compound represented by formula (1-2-2) include 3-noradamantanecarboxylic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0086] Examples of the compound represented by formula (1-3) include (2r,3r,5r,6r,7r,8r)-cubane-1-carboxylic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0087] (Compound (2)) Compound (2) is represented by formula (2). Formula (2):

[0088] In formula (2), R ２１ is a single bond or a polyvalent linking group having 1 to 20 carbon atoms. Examples of the polyvalent linking group include divalent to pentavalent linking groups, with divalent to trivalent linking groups being preferred. Examples of the polyvalent linking group include saturated or unsaturated hydrocarbon groups having 2 to 8 carbon atoms and saturated or unsaturated hydrocarbon groups having 3 to 6 carbon atoms. The hydrocarbon group may be a divalent to pentavalent hydrocarbon group, with divalent to trivalent hydrocarbon groups being preferred.

[0089] Formula: -R ２１ -Z １１ is a substituent bonded to any of the three cyclohexane rings in formula (2). ２１ -Z １１ is bonded to any of the three cyclohexane rings in formula (2).

[0090] R ２１ is a polyvalent linking group having 1 to 20 carbon atoms, R ２１ may form a ring by bonding one or more carbon atoms of any two or more carbon atoms forming three cyclohexane rings. ２１ -Z １１is a group represented by R ２１ By bonding to a ring formed by the hydrocarbon group R, it can be bonded to any of the three cyclohexane rings via the ring. For example, in the structure composed of three cyclohexane rings in formula (2), it may be bonded to two adjacent carbon atoms of the cyclohexane ring at one end to form a cycloalkane ring. For example, ２１ and two adjacent carbon atoms of the cyclohexane ring in formula (2) can be bonded to form a cyclopentane ring. In this way, compound (2) can have, for example, an androstane skeleton.

[0091] The three cyclohexane rings may be bonded to another ring that shares at least one carbon-carbon bond. For example, in the structure composed of three cyclohexane rings in formula (2), a cyclopentane ring that shares one carbon-carbon bond with one cyclohexane ring can be bonded to form an androstane skeleton together with the three cyclohexane rings.

[0092] The three cyclohexane rings are represented by the formula: -R ２１ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (=O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0093] Z １１ is a hydrophilic group. ２１ -Z １１ When a plurality of groups represented by the formula １１ may be the same or different. １１ As mentioned above,

[0094] n is a group of the formula: -R ２１ -Z １１and is an integer of 1 or more. n is preferably an integer of 1 to 4, more preferably 1 or 2. When n is 2 or more, the formula: -R ２１ -Z １１ The group represented by the formula: -R may be bonded to only one of the three cyclohexane rings, or may be bonded to two or more cyclohexane rings. ２１ -Z １１ The number of groups represented by R ２１ and a hydrocarbon group of the formula: -R ２１ -Z １１ The number of groups represented by the formula (I) is also included.

[0095] In one embodiment, compound (2) does not contain a fluorine atom.

[0096] The compound (2) is preferably a compound represented by either formula (2-1) or formula (2-2).

[0097] Formula (2-1):

[0098] In formula (2-1), R ２１１ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group.

[0099] n is a group of the formula: -R ２１１ -Z １１ and is an integer of 1 or more. ２１１ -Z １１ When a plurality of groups represented by R ２１１ may be the same or different. n is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably 1 or 2.

[0100] R ２１１is preferably a single bond or an alkylene group. Examples of the alkylene group include linear or branched alkylene groups. The number of carbon atoms in the alkylene group is preferably 1 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 4 or less. Examples of the alkylene group include -CH ２ -, -CH ２ CH ２ -, -CH ２ CH ２ CH ２ -, -CH(CH ３ ) CH ２ -, -CH ２ CH ２ CH ２ CH ２ - or -CH(CH ３ ) CH ２ CH ２ - is preferred.

[0101] Each of the three cyclohexane rings may have an optional substituent, and may be represented by the formula: -R ２１１ -Z １１ The cyclopentane ring may have a group represented by the formula: -R ２１１ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (=O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0102] Z １１ is as described above.

[0103] In one embodiment, the compound represented by formula (2-1) does not contain a fluorine atom.

[0104] Examples of the compound represented by formula (2-1) include cholic acid, lithocholic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0105] Formula (2-2):

[0106] In formula (2-2), R ２１２is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group.

[0107] n is a group of the formula: -R ２１２ -Z １１ and is an integer of 1 or more. ２１２ -Z １１ When a plurality of groups represented by R ２１２ may be the same or different. n is preferably an integer of 1 to 4, more preferably 1 or 2. When n is 2 or more, the formula: -R ２１２ -Z １１ The group represented by the following formula (I) may be bonded to only one of the three cyclohexane rings, or may be bonded to two or more cyclohexane rings.

[0108] R ２１２ is preferably a single bond or an alkylene group. Examples of the alkylene group include linear or branched alkylene groups. The number of carbon atoms in the alkylene group is preferably 1 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 4 or less. Examples of the alkylene group include -CH ２ -, -CH ２ CH ２ -, -CH ２ CH ２ CH ２ -, -CH(CH ３ ) CH ２ -, -CH ２ CH ２ CH ２ CH ２ - or -CH(CH ３ ) CH ２ CH ２ - is preferred.

[0109] All three cyclohexane rings are represented by the formula: -R ２１２ -Z １１ The cyclopentane ring may have any substituent other than the group represented by the formula: -R ２１１ -Z １１The substituent may be an alkyl group having 1 to 8 carbon atoms, an oxo group (═O), a hydroxyl group, a halogen atom, or the like. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0110] Z １１ is as described above.

[0111] In one embodiment, the compound represented by formula (2-2) does not contain a fluorine atom.

[0112] Examples of the compound represented by formula (2-2) include isosteviol and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0113] (Compound (3)) Compound (3) is represented by formula (3). Formula (3):

[0114] In formula (3), R ３１ represents a single bond or a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; R ３２ and R ３３ are independently polyvalent linking groups having 1 to 8 atoms which may contain a heteroatom. Examples of polyvalent linking groups include divalent to pentavalent linking groups. Examples of polyvalent linking groups include saturated or unsaturated hydrocarbon groups having 2 to 8 carbon atoms, and saturated or unsaturated hydrocarbon groups having 1 to 7 carbon atoms which contain an ether oxygen atom. Either hydrocarbon group may be a divalent to pentavalent hydrocarbon group. Examples of heteroatoms include an oxygen atom (O), a nitrogen atom (N), a sulfur atom (S), a boron atom (B), and a phosphorus atom (P). Preferred heteroatoms are O or N, and more preferred are O.

[0115] R ３１ is preferably a single bond or a hydrocarbon group having 1 or 2 carbon atoms. ３１ The hydrocarbon group of R may be divalent or trivalent, but is preferably divalent. ３２ and R ３３R is preferably a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom. ３２ and R ３３ The hydrocarbon group may be divalent to pentavalent, but is preferably divalent.

[0116] R ３１ , R ３２ and R ３３ Any two of R may be linked to each other to form one or more rings. ３１ , R ３２ and R ３３ are not linked to each other to form one or more rings.

[0117] X ３１ and X ３２ are independently a carbon atom (C) or a nitrogen atom (N). ３１ and X ３２ In C or N, R ３１ , R ３２ and R ３３ are bonded.

[0118] Ring C is R ３１ , R ３２ , X ３１ and X ３２ is a 3- to 18-membered ring formed by linking ３１ , R ３３ , X ３１ and X ３２ are bonded to each other. Ring C and ring D are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring C and ring D is an aromatic ring.

[0119] The hydrocarbon rings of ring C and ring D are preferably unsaturated hydrocarbon rings, such as a benzene ring.

[0120] The heterocycle of ring C and ring D is preferably an unsaturated heterocycle, such as a furan ring, a pyrrole ring, a thiophene ring, an imidazole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a pyran ring, a pyridine ring, or a thiopyran ring.

[0121] Ring C and ring D are each a group represented by the formula: -R ３４ -Z １１ The alkyl group may have any substituent other than the group represented by the formula:

[0033] . Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (=O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0122] R forming ring C ３２ and R forming ring D ３３ may be bonded to another ring that shares at least one carbon-carbon bond with ring C. For example, when ring C is a benzene ring, the benzene ring that shares one carbon-carbon bond with ring C can be bonded to ring C to form a naphthalene ring together with ring C.

[0123] Formula: -R ３４ -Z １１ is a substituent bonded to either or both of ring C and ring D. That is, in formula (3), a group represented by the formula: -R ３４ -Z １１ is a group represented by R ３１ , R ３２ and R ３３ is bound to one of

[0124] R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms. ３４ -Z １１ When a plurality of groups represented by R ３４ may be the same or different.

[0125] R ３４is preferably a single bond or an alkylene group. Examples of the alkylene group include linear or branched alkylene groups. The number of carbon atoms in the alkylene group is preferably 1 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 3 or less. Examples of the alkylene group include -CH ２ -, -CH ２ CH ２ -, -CH ２ CH ２ CH ２ - or -CH(CH ３ ) CH ２ - is preferred, and -CH ２ - is more preferable.

[0126] R ３４ is a single bond or -CH ２ - is preferred, and a single bond is more preferred.

[0127] Z １１ is a hydrophilic group. ３４ -Z １１ When a plurality of groups represented by the formula １１ may be the same or different. １１ As mentioned above,

[0128] n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more. n is preferably an integer of 1 to 4, more preferably 1 or 2. When n is 2 or more, the formula: -R ３４ -Z １１ The group represented by the following formula (I) can be bonded to either one or both of ring C and ring D.

[0129] In one embodiment, compound (3) does not contain a fluorine atom.

[0130] The compound (3) is preferably a compound represented by formula (3-1):

[0131] In formula (3-1), ring D １is a 3- to 18-membered saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring. １ may be an aromatic or non-aromatic ring.

[0132] Ring D １ The hydrocarbon ring is preferably an unsaturated hydrocarbon ring, such as a benzene ring.

[0133] Ring D １ The heterocyclic ring is preferably an unsaturated heterocyclic ring, and examples thereof include a furan ring, a pyrrole ring, a thiophene ring, an imidazole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a pyran ring, a pyridine ring, and a thiopyran ring.

[0134] Ring D １ Among these, a benzene ring or a furan ring is preferable.

[0135] Benzene ring and ring D １ is represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, an oxo group (═O), a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br. In one embodiment, the benzene ring and ring D １ does not have a group containing an unsaturated double bond.

[0136] Benzene ring and ring D １ may be bonded to another ring sharing at least one carbon-carbon bond. １ is not bonded to another ring that shares at least one carbon-carbon bond with it.

[0137] Formula: -R ３４ -Z １１ The group represented by the formula: １ That is, in formula (3-1), a substituent group represented by the formula: -R ３４ -Z １１The group represented by the formula: １ is bound to one of

[0138] R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms. ３４ -Z １１ When a plurality of groups represented by R ３４ may be the same or different. ３４ is as described above.

[0139] n is a benzene ring or ring D １ Formula bonded to: -R ３４ -Z １１ and is an integer of 1 or more. n is preferably an integer of 1 to 4, more preferably 1 or 2. When n is 2 or more, the formula: -R ３４ -Z １１ The group represented by the formula: １ It can be bound to either or both of the following:

[0140] Z １１ is as described above.

[0141] In one embodiment, the compound represented by formula (3-1) does not contain a fluorine atom.

[0142] Examples of the compound represented by formula (3-1) include 2,6-naphthalenedisulfonic acid, 2-naphthalenesulfonic acid, benzofuran-2-carboxylic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0143] The compound (3) is more preferably a compound represented by either formula (3-1-1) or formula (3-1-2).

[0144] Formula (3-1-1):

[0145] In formula (3-1-1), R ３４ , Z １１ and n are as defined above. The two benzene rings are both represented by the formula: -R ３４ -Z １１and a group containing an unsaturated double bond. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0146] In one embodiment, the compound represented by formula (3-1-1) does not contain a fluorine atom.

[0147] Examples of the compound represented by formula (3-1-1) include 2,6-naphthalenedisulfonic acid, 2-naphthalenesulfonic acid, and salts thereof (sodium salts, potassium salts, ammonium salts, etc.).

[0148] Formula (3-1-2):

[0149] In formula (3-1-2), R ３４ , Z １１ and n are as defined above. The benzene ring and the furan ring are represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond. Examples of the substituent include an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, and a halogen atom. The alkyl group is preferably a methyl group. The halogen atom is preferably Cl or Br, and more preferably Br.

[0150] In one embodiment, the compound represented by formula (3-1-2) does not contain a fluorine atom.

[0151] Examples of the compound represented by formula (3-1-2) include benzofuran-2-carboxylic acid and its salts (sodium salt, potassium salt, ammonium salt, etc.).

[0152] Examples of cyclic compounds include (±)-10-camphorsulfonic acid, 2,3-norbornanedicarboxylic acid, norbornane-2-carboxylic acid, (S)-(+)-ketopinic acid, (+)-3-bromocamphor-8-sulfonic acid, (-)-3-bromocamphor-8-sulfonic acid, (-)-camphanic acid, 5-norbornene-2,3-dicarboxylic acid, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, bicyclo[2.2.2]octane-2-carboxylic acid, and quinuclidine. 2r,3r,5r,6r,7r,8r)-cubane-1-carboxylic acid, 1-adamantanecarboxylic acid, 1,3-adamantanediacetic acid, 1-adamantaneacetic acid, 3-noradamantanecarboxylic acid, (2r,3r,5r,6r,7r,8r)-cubane-1-carboxylic acid, cholic acid, lithocholic acid, isosteviol, disodium 2,6-naphthalenedisulfonate, sodium 2-naphthalenesulfonate, benzofuran-2-carboxylic acid, and salts thereof (sodium salt, potassium salt, ammonium salt, etc.).

[0153] (Compound (4)) In the production method of the present disclosure, compound (4) can also be used as the cyclic compound. This cyclic compound is preferable because, since the rings are fused, the number of carbon-hydrogen bonds that may cause chain transfer reactions in the polymerization reaction is reduced compared to non-cyclic compounds or non-fused cyclic compounds having the same number of carbon atoms.

[0154] Compound (4) is represented by formula (4):

[0155] In formula (4), R ４１ is a single bond or a divalent linking group having 1 to 8 atoms which may contain a heteroatom. Examples of the divalent linking group include saturated or unsaturated hydrocarbon groups having 1 to 8 carbon atoms, and saturated or unsaturated hydrocarbon groups having 1 to 7 carbon atoms which contain an ether oxygen atom. Examples of the heteroatom include an oxygen atom (O), a nitrogen atom (N), a sulfur atom (S), a boron atom (B), and a phosphorus atom (P). The heteroatom is preferably O or N, and more preferably O.

[0156] R ４１ is preferably a single bond or a hydrocarbon group having 1 or 2 carbon atoms, and２ -) is more preferred.

[0157] Formula: -R ４２ -Z １１ The group represented by the formula: is a substituent bonded to a naphthalene ring.

[0158] R ４２ is independently in each occurrence a single bond or a divalent linking group having 1 to 20 carbon atoms. The cyclic compounds described above can be represented by the formula: -R ４２ -Z １１ and each R ４２ may be the same or different.

[0159] R ４２ is preferably a single bond or an alkylene group. Examples of the alkylene group include linear or branched alkylene groups. The number of carbon atoms in the alkylene group is preferably 1 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 3 or less. Examples of the alkylene group include -CH ２ -, -CH ２ CH ２ -, -CH ２ CH ２ CH ２ - or -CH(CH ３ ) CH ２ - is preferred, and -CH ２ - is more preferable.

[0160] R ４２ is a single bond or -CH ２ - is preferred, and a single bond is more preferred.

[0161] Z １１ is a hydrophilic group. The cyclic compound is represented by the formula: -R ４２ -Z １１ and each Z １１ may be the same or different. １１ As mentioned above,

[0162] n is a group of the formula: -R ４２ -Z １１and is an integer of 1 or more. n is preferably an integer of 1 to 4, more preferably 1 or 2, and even more preferably 1. When n is 2 or more, the formula: -R ４２ -Z １１ The group represented by the formula: can be attached to either one or both of the naphthalene rings.

[0163] In formula (4), m is an integer of 1 or more, preferably an integer of 1 to 20, and more preferably an integer of 5 to 15.

[0164] (Polymerization) The polymerization in the production method of the present disclosure can be carried out by charging an aqueous medium, a cyclic compound, a monomer, and other additives as necessary into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to initiate the polymerization reaction. After the initiation of polymerization, additional monomers, polymerization initiators, chain transfer agents, cyclic compounds, etc. may be added depending on the purpose. The cyclic compound may also be added after the initiation of the polymerization reaction.

[0165] The amount of the cyclic compound when polymerizing the fluoromonomer is preferably 3 to 5000 ppm by mass relative to the aqueous medium. The amount of the cyclic compound may be 5 ppm by mass or more, 10 ppm by mass or more, 20 ppm by mass or more, or 30 ppm by mass or more. The amount of the cyclic compound may be 4000 ppm by mass or less, 3000 ppm by mass or less, 2000 ppm by mass or less, 1700 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 500 ppm by mass or less, or 200 ppm by mass or less. By setting the amount of the cyclic compound within the above range, the polymerization of the fluoromonomer proceeds more smoothly.

[0166] The amount of the cyclic compound when polymerizing the fluoromonomer to obtain polytetrafluoroethylene is preferably 3 to 5000 mass ppm relative to the aqueous medium. The lower limit of the amount of the cyclic compound may be 5 mass ppm or more, 10 mass ppm or more, 50 mass ppm or more, 100 mass ppm or more, 200 mass ppm or more, 300 mass ppm or more, or 400 mass ppm or more, and the upper limit may be 4000 mass ppm or less, 3000 mass ppm or less, or 2000 mass ppm or less. By setting the amount of the cyclic compound within the above range, the polymerization of the fluoromonomer to obtain polytetrafluoroethylene proceeds more smoothly, and the stability of the resulting aqueous dispersion is improved.

[0167] In the polymerization of fluoromonomer to obtain polytetrafluoroethylene, it is necessary that the stability of the obtained aqueous dispersion and the polymerization reactivity are well balanced, and this can be achieved by using at least one cyclic compound selected from the group consisting of compound (1), compound (2) and compound (3).The reason for this is not clear, but the radical at the polymer end is difficult to attack the cyclic compound, and it selectively reacts with the monomer, and polymerization proceeds.It is presumed that this is due to the steric hindrance of the cyclic structure.

[0168] In the production method of the present disclosure, the polymerization temperature for polymerizing the fluoromonomer is preferably 10 to 120°C, more preferably 20 to 100°C.

[0169] In the production method of the present disclosure, the polymerization pressure for polymerizing the fluoromonomer is preferably 0.5 to 10 MPaG, more preferably 0.7 to 7 MPaG.

[0170] The production method of the present disclosure polymerizes fluoromonomer in the presence of the above-mentioned cyclic compound and aqueous medium, so that it can suppress the adhesion of polymer to the polymerization tank.The polymer adhesion rate to the polymerization tank is preferably 8.0 mass% or less, more preferably 4.0 mass% or less, even more preferably 2.0 mass% or less, even more preferably 1.5 mass% or less, and most preferably 1.0 mass% or less.According to the production method of the present disclosure, when producing an aqueous dispersion containing a fluorine-containing elastomer as the fluoropolymer, it can particularly suppress the adhesion of polymer to the polymerization tank.In addition, according to the production method of the present disclosure, when producing polytetrafluoroethylene as the fluoropolymer, it is possible to obtain an aqueous dispersion in which polytetrafluoroethylene particles are stably dispersed in the aqueous medium and have a certain solid content concentration.

[0171] In one embodiment of the production method, polytetrafluoroethylene is produced using at least TFE as the fluoromonomer. Upon completion of the polymerization of TFE, a polymer dispersion having a solids concentration of 10 to 50% by mass and an average primary particle size of 50 to 500 nm can be obtained. The lower limit of the solids concentration is preferably 12% by mass, more preferably 15% by mass, and even more preferably 20% by mass or more. The upper limit is not particularly limited, but may be 40% by mass or 35% by mass. The lower limit of the average primary particle size is preferably 100 nm, more preferably 150 nm. The upper limit is preferably 400 nm, more preferably 350 nm.

[0172] The polymer adhesion rate is the ratio of the mass of polymer adhesions adhered to the polymerization vessel after the completion of polymerization to the total amount of polymer (fluoroelastomer) after the completion of polymerization (adhesion rate to the polymerization vessel). The polymer adhesions include polymers that adhere to the inside of the polymerization vessel, such as the inner wall of the polymerization vessel and the stirring blades, after the aqueous dispersion is extracted from the polymerization vessel after the completion of polymerization, and polymers that have been released from the aqueous dispersion by aggregation and are floating or settling without being dispersed in the aqueous dispersion. The mass of the polymer adhesions is the mass after the water contained in the polymer adhesions has been removed by drying at 120°C. Polymer adhesion rate (mass%) = mass of polymer adhesions / mass of obtained polymer (including adhesions) × 100 Mass of obtained polymer = mass of aqueous dispersion × solids concentration of aqueous dispersion (mass%) / 100 + mass of polymer adhesions

[0173] The number of fluoropolymer particles contained in the aqueous dispersion is preferably 1.0 × 10 １２ pcs / cc or more, more preferably 5.0 × 10 １２ pcs / cc or more, more preferably 1.0 × 10 １３ The particle number (the number of polymer particles) can be calculated according to the following formula:

[0174] The number of fluoropolymer particles obtained by the above formula is the number per 1 cc of water. The specific gravity is the specific gravity of the fluoropolymer particles. The specific gravity of the fluoropolymer particles can be determined in accordance with JIS Z 8807:2012.

[0175] When producing polytetrafluoroethylene, 0.6 × 10 １３ It is preferable to generate polytetrafluoroethylene particles at a rate of 0.7 × 10 or more per cc. By generating a large number of particles in the polymerization step, primary particles having a small average primary particle size and aspect ratio can be easily obtained, the polymerization of tetrafluoroethylene in an aqueous medium proceeds smoothly, and polytetrafluoroethylene can be easily produced. The number of polytetrafluoroethylene particles to be generated is 0.7 × 10 １３ More preferably, it is 0.8×10 １３More preferably, the number is 0.9×10 １３ It is even more preferable that the number of particles is 1.0×10 １３ The upper limit is not particularly limited, but for example, 7.0 × 10 １４ Pieces / cc.

[0176] (Polymerization initiator) As the polymerization initiator, radical polymerization initiator can be mentioned.The polymerization initiator is not particularly limited as long as it can generate radicals at the temperature at which fluoromonomer is polymerized, and oil-soluble polymerization initiator, water-soluble polymerization initiator, etc. can be used, but water-soluble polymerization initiator is preferred.In addition, the polymerization initiator can be used as a redox initiator by combining with a reducing agent, etc.

[0177] The amount of polymerization initiator used in polymerizing a fluoromonomer is determined appropriately depending on the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate. The amount of polymerization initiator is determined appropriately depending on the molecular weight of the target fluoropolymer and the polymerization reaction rate, and is preferably 0.00001 to 10 mass%, more preferably 0.0001 to 1 mass%, relative to 100 mass% of the total amount of monomers.

[0178] The amount of polymerization initiator used when polymerizing a fluoromonomer to obtain polytetrafluoroethylene is preferably 0.1 mass ppm or more and 1 mass % or less, and more preferably 1 mass ppm or more and 1000 mass ppm or less, relative to the aqueous medium used for polymerization.

[0179] As the polymerization initiator, an oil-soluble radical polymerization initiator, a water-soluble radical polymerization initiator, or an azo compound can be used.

[0180] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, and representative examples thereof include 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 di[perfluoro(or fluorochloro)acyl]peroxides.

[0181] Examples of the azo compound include azodicarboxylate, azodicarboxyldiamide, 2,2'-azobisisobutyronitrile, 2,2'-azobis2,4-dimethylvaleronitrile, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid).

[0182] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate; organic peroxides such as disuccinic acid peroxide or diglutaric acid peroxide; t-butyl permaleate; t-butyl hydroperoxide; etc. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0183] As the water-soluble peroxide, a salt of persulfate is preferred because it is easy to adjust the amount of radicals generated. ２ S ２ O ８ ), ammonium persulfate ((NH ４ ) ２ S ２ O ８ ), sodium persulfate (Na ２ S ２ O ８ ) is preferred, with ammonium persulfate being most preferred.

[0184] When polymerization is carried out using a water-soluble peroxide at a polymerization temperature of 45° C. or higher, it is preferable to carry out the polymerization without using a reducing agent.

[0185] For example, when polymerization is carried out at a low temperature of 60° C. or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. That is, it is preferable to carry out the polymerization in the presence of a redox initiator.

[0186] Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, cerium ammonium nitrate, and bromates. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, oxalic acid, and metal sulfinates. Examples of persulfates include ammonium persulfate, potassium persulfate, and sodium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate. When using copper salts or iron salts, it is particularly preferable to add a chelating agent. A preferred chelating agent is ethylenediaminetetraacetic acid disodium salt dihydrate.

[0187] 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, ammonium persulfate / sodium hydroxymethanesulfinate dihydrate, and the like, with ammonium persulfate / sodium hydroxymethanesulfinate dihydrate being preferred.

[0188] When a redox initiator is used, either the oxidizing agent or the reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when ammonium persulfate / sodium hydroxymethanesulfinate dihydrate is used, it is preferred to charge ammonium persulfate into a polymerization vessel and then continuously add sodium hydroxymethanesulfinate dihydrate thereto.

[0189] The amount of persulfate used in the redox initiator is preferably 0.001 to 2.0% by mass, more preferably 0.01 to 1.5% by mass, and particularly preferably 0.05 to 1.0% by mass, based on the aqueous medium used in the polymerization.

[0190] The amount of the reducing agent used is preferably from 1 to 30% by mass, more preferably from 3 to 25% by mass, and particularly preferably from 5 to 20% by mass, based on the amount of the aqueous medium used in the polymerization.

[0191] The amount of the third component (such as the copper salt or iron salt) used is preferably 0.001 to 0.5% by mass, more preferably 0.005 to 0.4% by mass, and particularly preferably 0.01 to 0.3% by mass, based on the aqueous medium used in the polymerization.

[0192] (Chain Transfer Agent) In the production method of the present disclosure, the fluoromonomer may be polymerized in the presence of a chain transfer agent. As the chain transfer agent, known agents can be used, such as hydrocarbons, esters, ethers, alcohols, ketones, halogen-containing compounds, carbonates, etc. Among them, propane, isopentane, diethyl malonate, and ethyl acetate are preferred from the viewpoint of being less likely to decrease the reaction rate, and I(CF ２ ) ４ I, I (CF ２ ) ６ I, ICH ２ Diiodine compounds such as I are preferred in that they can iodine the polymer terminals and can be used as reactive polymers.

[0193] As the chain transfer agent, it is particularly preferable to use a bromine compound or an iodine compound. Examples of polymerization methods using a bromine compound or an iodine compound include iodine transfer polymerization and bromine transfer polymerization.

[0194] Iodine transfer polymerization is a method that utilizes living radical polymerization by a radical chain reactivation mechanism, which occurs due to the low dissociation energy of carbon-iodine bonds, which are radically active and involve chain transfer reactions during the radical polymerization reaction. Known reaction conditions can be appropriately used and are not particularly limited. For example, conditions described in "Collection of Polymers, Vol. 49, No. 10, pp. 765-783, October 1992" and JP-A-53-3495 can be appropriately adopted. Similar polymerizations can also be performed using bromine compounds instead of iodine compounds; in the present disclosure, such polymerizations are referred to as bromine transfer polymerization.

[0195] Among these, iodine transfer polymerization is preferred from the viewpoints of polymerization reactivity and crosslinking reactivity.

[0196] Representative examples of the bromine compound or iodine compound include compounds represented by the general formula: ８ I ｘ Br ｙ (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R ８ is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom). By using a bromine compound or an iodine compound, iodine or bromine is introduced into the polymer and functions as a crosslinking point.

[0197] Examples of bromine compounds and iodine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, and 1-bromo-4-iodoperfluorobutane. These compounds may be used alone or in combination with one another. Among these, compounds containing only iodine and no bromine are preferred from the standpoints of polymerization reactivity, crosslinking reactivity, and ease of availability, and 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, or 2-iodoperfluoropropane are preferred.

[0198] The amount of the chain transfer agent is preferably 0.2×10 based on the total amount of monomers used in the polymerization. －３ up to 2 mol%, more preferably 1.0 × 10 －３ It is up to 1 mol %.

[0199] The amount of chain transfer agent used when polymerizing a fluoromonomer to obtain polytetrafluoroethylene is preferably 0.001 to 10,000 ppm relative to the aqueous medium. The amount of the chain transfer agent is more preferably 0.01 ppm or more, even more preferably 0.05 ppm or more, and particularly preferably 0.1 ppm or more relative to the aqueous medium. The amount is more preferably 1,000 ppm or less, even more preferably 500 ppm or less, and particularly preferably 100 ppm or less relative to the aqueous medium.

[0200] (Aqueous Medium) The aqueous medium is a reaction medium for polymerization and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an ether or a ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower.

[0201] As the aqueous medium, an aqueous medium containing only water or an aqueous medium containing only water and a fluorine-free organic solvent is preferred, as it allows the polymerization to proceed smoothly, and an aqueous medium containing only water is more preferred.

[0202] The content of water in the aqueous medium is preferably 90% or more, more preferably 95% or more, even more preferably 99.0% or more, still more preferably 99.5% or more, particularly preferably 99.9% or more, and may be 100%, based on the mass of the aqueous medium, in order to allow the polymerization to proceed smoothly.

[0203] (Fluorine-containing compound (A)) In the production method of the present disclosure, a fluorine-containing compound (A) containing a functional group reactive by radical polymerization and a hydrophilic group can be used. By using the fluorine-containing compound (A), the polymerization of the fluoromonomer proceeds more smoothly. The fluorine-containing compound (A) can be particularly suitably used when producing an aqueous dispersion containing a fluorine-containing elastomer as a fluoropolymer.

[0204] The fluorine-containing compound (A) is preferably a compound containing anionic or nonionic hydrophilic groups, and more preferably a compound containing anionic hydrophilic groups.The fluorine-containing compound (A) may contain, for example, only anionic hydrophilic groups, or only nonionic hydrophilic groups.In addition, as the fluorine-containing compound (A), only a compound containing anionic hydrophilic groups may be used, or only a compound containing nonionic hydrophilic groups may be used, or a compound containing anionic hydrophilic groups and a compound containing nonionic hydrophilic groups may be used in combination.

[0205] Examples of the hydrophilic group in the fluorine-containing compound (A) include —NH ２ , -P(O)(OM) ２ , -OP(O)(OM) ２ , -SO ３ M, -OSO ３ M, -COOM, -B (OM) ２ , -OB(OM) ２ (In each formula, M represents H, a metal atom, NR ７４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring.) Among the above hydrophilic groups, -SO ３ M or -COOM is preferred, and -COOM is more preferred. ７ The organic group in R is preferably an alkyl group. ７ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ More preferred is an alkyl group of the formula (I), and most preferred is H. When two M's are included in each formula, the two M's may be the same or different. The metal atom includes a monovalent or divalent metal atom, and is preferably an alkali metal (Group 1) or alkaline earth metal (Group 2), and more preferably Na, K, or Li.

[0206] The "functional group capable of reacting by radical polymerization" in the fluorine-containing compound (A) includes a group containing a radically polymerizable unsaturated bond.

[0207] Examples of the group having a radical polymerizable unsaturated bond include groups having an ethylenically unsaturated bond such as a vinyl group and an allyl group. The group having an ethylenically unsaturated bond is a group represented by the following formula: ｅ X ｇ =CX ｆ R- (wherein, X ｅ , X ｆ and X ｇ are each independently F, Cl, H, or CF ３ , C.F. ２ H, C.F.H. ２ , or CH ３ and R is a linking group. The linking group of R can be represented by the formula: ａ Examples of linking groups include:

[0208] Examples of the group having a radical polymerizable unsaturated bond include —CH═CH ２ , -CF=CH ２、-CH=CF ２、 -CF = CF ２ , -CH ２ -CH=CH ２ , -CF ２ -CF=CH ２ , -CF ２ -CF = CF ２ , -(C=O)-CH=CH ２ , -(C=O)-CF=CH ２ , -(C=O)-CH=CF ２ , -(C=O)-CF=CF ２ , -(C=O)-C(CH ３ ) = CH ２ , -(C=O)-C(CF ３ ) = CH ２ , -(C=O)-C(CH ３ ) = CF ２ , -(C=O)-C(CF ３ ) = CF ２ , —O—CH ２ -CH=CH ２ , —O—CF ２ -CF=CH ２ , —O—CH ２ -CH=CF ２ , —O—CF═CF ２ , —O—CF ２ -CF = CF ２ Examples include:

[0209] In the production method of the present disclosure, a fluoromonomer can be polymerized in the presence of a fluorine-containing compound (A) represented by general formula (A). By using a fluorine-containing compound (A) represented by general formula (A), the polymerization of the fluoromonomer proceeds more smoothly. General formula (A): CX ｉ X ｋ =CX ｊ R ａ - (CZ １ Z ２ ) ｋ -Y ３ (In the formula, X ｉ , X ｊ and X ｋ are each independently F, Cl, H or CF ３ and Y ３ is a hydrophilic group; R ａis a linking group; Z １ and Z ２ are each independently H, F or CF ３ and k is 0 or 1. ｉ , X ｋ , X ｊ , R ａ , Z １ and Z ２ At least one of contains F. However, when k is 0, R ａ is a linking group other than a single bond.

[0210] Y in general formula (A) ３ is a hydrophilic group. For example, the hydrophilic group is -NH ２ , -P(O)(OM) ２ , -OP(O)(OM) ２ , -SO ３ M, -OSO ３ M, -COOM, -B (OM) ２ , -OB(OM) ２ (In each formula, M represents H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ 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.) is preferred. Among the above hydrophilic groups, -SO ３ M or -COOM is more preferred, and -COOM is even more preferred. ７ The organic group in R is preferably an alkyl group. ７ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ More preferred is an alkyl group of the formula (I), and most preferred is H. The metal atom includes monovalent or divalent metal atoms, and is preferably an alkali metal (Group 1) or alkaline earth metal (Group 2), and more preferably Na, K, or Li.

[0211] R in general formula (A) ａ is a linking group. In the present disclosure, the term "linking group" refers to a divalent linking group. The linking group is preferably a single bond or a group containing at least one carbon atom. However, when k is 0, R ａ is a linking group other than a single bond, and is preferably a group containing at least one carbon atom. The number of carbon atoms in the linking group may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit on the number of carbon atoms in the linking group, but it may be, for example, 100 or less, or 50 or less.

[0212] The linking group may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0213] R ａ is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group.

[0214] R ａ When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and the group may or may not contain a double bond. ａ may be either linear or branched, and may be either cyclic or acyclic. ａ may contain functional groups (e.g., esters, ethers, ketones, amines, halides, etc.).

[0215] R ａ may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group.

[0216] R ａExamples of the hydrocarbon group include a hydrocarbon group in which no fluorine atoms are bonded to a carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, a hydrocarbon group in which all of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, -(C=O)-, -(C=O)-O-, or a hydrocarbon group containing an ether bond, which may contain an oxygen atom, a double bond, or a functional group.

[0217] 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.

[0218] Specific examples of the compound represented by general formula (A) include: (In the formula, X ｊ and Y ３ is the same as above. n is an integer of 1 to 10.

[0219] R ａ The following general formula (r1): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O) ｇ - (r1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1), and a divalent group represented by the following general formula (r2): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ - (r2) (wherein, X ７ are each independently H, F or CF３ wherein e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1.) is also preferred.

[0220] -R in general formula (A) ａ - (CZ １ Z ２ ) ｋ - may also be represented by the following formula (t1): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ６ ２ ) ｅ -{O-CF(CF ３ ) ｆ -(O) ｇ -CZ １ Z ２ - (t1) (wherein, X ６ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z １ and Z ２ are each independently F or CF ３ In formula (t1), a divalent group represented by １ and Z ２ is one F and the other CF ３ It is more preferable that:

[0221] In addition, in the above general formula (A), -R ａ - (CZ １ Z ２ ) ｋ - is the following formula (t2): -(C=O) ｈ -(O) ｉ -CF ２ -O-(CX ７ ２ ) ｅ -(O) ｇ -CZ １ Z ２ - (t2) (wherein, X ７ are each independently H, F or CF ３ wherein e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z１ and Z ２ are each independently F or CF ３ In formula (t2), a divalent group represented by １ and Z ２ is one F and the other CF ３ It is more preferable that:

[0222] The compound represented by the general formula (A) has a hydrophilic group (Y ３ It is also preferable that the portion excluding X has a C—F bond and does not have a C—H bond. ｉ , X ｊ , and X ｋ All of the are F and R ａ is preferably a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be cyclic or acyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0223] The compound represented by the general formula (A) may be partially fluorinated. That is, the compound represented by the general formula (A) may have a hydrophilic group (Y ３ It is also preferred that the moiety excluding (a) has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0224] The compound represented by general formula (A) is also preferably a compound represented by the following formula (Aa): CF ２ ═CF—O—Rf ０ -Y ３ (Aa) (wherein, Y ３ is a hydrophilic group, and Rf ０ is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0225] The compound represented by general formula (A) is also preferably a compound represented by the following formula (Ab): CH ２ =CH-O-Rf ０ -Y ３ (Ab) (wherein, Y ３ is a hydrophilic group, and Rf ０ is a perfluorinated divalent linking group defined by formula (Aa).

[0226] In general formula (A), Y ３ Ha-OSO ３ One of the preferred embodiments is Y. ３ Ga-OSO ３ When M is a compound represented by general formula (A), CF ２ =CF(OCF ２ CF ２ CH ２ OSO ３ M), CH ２ =CH((CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(O(CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ OSO ３ M), CH ２ =CH((CF ２ ) ４ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ M), CH２ =CH(CF ２ CF ２ CH ２ OSO ３ M), CF ２ =CF(OCF ２ CF ２ CF ２ CF ２ SO ２ N (CH ３ ) CH ２ CH ２ OSO ３ M), CH ２ =CH(CF ２ CF ２ CH ２ OSO ３ In the above formula, M is the same as above.

[0227] In general formula (A), Y ３ Ha-SO ３ M is also a preferred embodiment. ３ Ga-SO ３ When M is a compound represented by general formula (A), CF ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ =CF(O(CF ２ ) ４ SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ M), CH ２ =CH(CF ２ CF ２ SO ３ M), CF ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ CF ２ SO ３M), CH ２ =CH((CF ２ ) ４ SO ３ M), CH ２ =CH((CF ２ ) ３ SO ３ In the above formula, M is the same as above.

[0228] In general formula (A), Y ３ It is also a preferred embodiment that Y is -COOM. ３ is -COOM, the compound represented by general formula (A) is CF ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(OCF ２ CF ２ CF ２ COOM), C.F. ２ =CF(O(CF ２ ) ５ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) COOM), CF ２ =CF(OCF ２ CF (CF ３ ) O(CF ２ ) ｎ COOM) (n is greater than 1), CH ２ =CH(CF ２ CF ２ COOM), CH ２ =CH((CF ２ ) ４ COOM), CH ２ =CH((CF ２ ) ３ COOM), C.F. ２ =CF(OCF ２ CF ２ SO ２ NR'CH ２ COOM), C.F. ２ =CF(O(CF ２ ) ４ SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF２ CF (CF ３ ) SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH(CF ２ CF ２ SO ２ NR'CH ２ COOM), C.F. ２ =CF(OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH((CF ２ ) ４ SO ２ NR'CH ２ COOM), CH ２ =CH(CF ２ CF ２ SO ２ NR'CH ２ COOM), CH ２ =CH((CF ２ ) ３ SO ２ NR'CH ２ In the above formula, R' is H or C １－４ is an alkyl group, and M is the same as above.

[0229] The compound represented by general formula (A) includes a compound represented by general formula (5): CX ２ =CY(-CZ ２ -O-Rf-Y ３) (5) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z is the same or different and is -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y ３ is the same as above.), a compound represented by general formula (6): CX ２ =CY(-O-Rf-Y ３ ) (6) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. Y ３ is the same as above.) and a compound represented by general formula (7): CX ２ =CY(-Rf-Y ３ ) (7) (In the formula, X is the same or different and is -H or -F, Y is -H, -F, an alkyl group or a fluorine-containing alkyl group, and Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms. Y ３ is the same as above.

[0230] The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0231] In general formula (5), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0232] In general formula (5), Y is -H, -F, an alkyl group, or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Y is -H, -F, or -CF ３ is preferred, and —F is more preferred.

[0233] In general formula (5), Z's may be the same or different and are -H, -F, an alkyl group, or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Z's may be -H, -F, or -CF ３ is preferred, and —F is more preferred.

[0234] In general formula (5), it is preferable that at least one of X, Y, and Z contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0235] In general formula (5), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF ２ -, -CH ２ CF ２ -, -CF ２ CF ２ -, -CF ２ CH ２ -, -CF ２ CF２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0236] 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.

[0237] Examples of the fluorine-containing alkylene group having an ether bond include a group represented by the following formula: (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３ p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0238] Specific examples of fluorine-containing alkylene groups having an ether bond include -CF(CF ３ )CF ２ -O-CF(CF ３ )-,-(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ )-(wherein n is an integer from 1 to 10), -CF(CF ３ )CF ２ -O-CF(CF ３ ) CH ２ -, -(CF(CF ３ )CF ２ -O) ｎ -CF (CF ３ ) CH ２ - (wherein n is an integer of 1 to 10), -CH ２ CF ２ CF ２ O-CH ２ CF ２CH ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ -, -CF ２ CF ２ CF ２ O-CF ２ CF ２ CH ２ -, -CF ２ CF ２ O-CF ２ -, -CF ２ CF ２ O-CF ２ CH ２ The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0239] In the general formula (5), Y ３ is -COOM, -SO ３ M or -OSO ３ M (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ 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.

[0240] R ７ The organic group in R is preferably an alkyl group. ７ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M represents —H, a metal atom, or —NR ７ ４ is preferred, and —H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or —NR ７ ４ is more preferred, and —H, —Na, —K, —Li or —NH ４is more preferred, and —Na, —K or —NH ４ is even more preferred, and —Na or —NH ４ is particularly preferred, and —NH ４ is most preferred. ３ As the group, -COOM or -SO ３ M is preferred, and —COOM is more preferred.

[0241] The compound represented by general formula (5) is preferably a compound (5a) represented by general formula (5a): CH ２ =CF(-CF ２ -O-Rf-Y ３ ) (5a) (wherein Rf and Y ３ is the same as above.)

[0242] Specific examples of the compound represented by general formula (5a) include compounds represented by the following formula:

[0243]

[0244] (In the formula, Z １ is F or CF ３ ;Z ２ and Z ３ are H or F; Z ４ is H, F or CF ３ p1+q1+r1 are integers of 0 to 10; s1 is 0 or 1; t1 is an integer of 0 to 5; Y ３ is the same as above. However, Z ３ and Z ４ are both H, then p1+q1+r1+s1 is not 0). More specifically, compounds represented by the following formula:

[0245]

[0246] Among them,

[0247]

[0248] It is preferable that:

[0249] The compound represented by the general formula (5a) includes compounds represented by the general formula (5a) ３ is preferably -COOM, and in particular CH ２ =CFCF ２ OCF (CF３ ) COOM, and CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ )COOM (wherein M is as defined above), and CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM is more preferred.

[0250] The compound represented by general formula (5) is preferably a compound (5b) represented by general formula (5b): CX ２ ２ =CFCF ２ -O-(CF(CF ３ )CF ２ O) ｎ５ -CF (CF ３ )-Y ３ (5b) (where each X ２ are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, Y ３ is the same as the above definition.)

[0251] In the general 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 M is preferably H or NH in that it is less likely to remain as an impurity and the heat resistance of the resulting molded product is improved. ４ It is preferable that:

[0252] Examples of the compound represented by general formula (5b) include CH ２ =CFCF ２ OCF (CF ３ ) COOM, C.H. ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３) COOM (wherein M is as defined above).

[0253] Further, examples of the compound represented by general formula (5) include compound (5c) represented by general formula (5c): CF ２ =CFCF ２ -O-Rf-Y ３ (5c) (wherein Rf and Y ３ is the same as above)

[0254] More specifically, etc.

[0255] In general formula (6), X is -H or -F. Both Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0256] In general formula (6), Y is -H, -F, an alkyl group, or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Y is -H, -F, or -CF ３ is preferred, and —F is more preferred.

[0257] In general formula (6), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be —H, and Y and Z may be —F.

[0258] In general formula (6), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF ２ -, -CH ２ CF２ -, -CF ２ CF ２ -, -CF ２ CH ２ -, -CF ２ CF ２ CH ２ -, -CF(CF ３ ) -, -CF(CF ３ )CF ２ -, -CF(CF ３ ) CH ２ The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0259] In the above general formula (6), Y ３ is -COOM, -SO ３ M or -OSO ３ M (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ 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.

[0260] R ７ The organic group in R is preferably an alkyl group. ７ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom may be an alkali metal (Group 1) or an alkaline earth metal (Group 2), and preferably Na, K, or Li. The M may be —H, a metal atom, or —NR ７ ４ is preferred, and —H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or —NR ７ ４ is more preferred, and —H, —Na, —K, —Li or —NH ４ is more preferred, and —Na, —K or —NH ４ is even more preferred, and —Na or —NH ４ is particularly preferred, and —NH ４The most preferred is the above Y ３ As the group, -COOM or -SO ３ M is preferred, and —COOM is more preferred.

[0261] The compound represented by general formula (6) is preferably at least one selected from the group consisting of compounds represented by general formulas (6a) to (6f): CF ２ =CF-O-(CF ２ ) ｎ１ -Y ３ (6a) (wherein n1 represents an integer of 1 to 10, and Y ３ is the same as defined above) CF ２ =CF-O-(CF ２ C (CF ３ ) F) ｎ２ -Y ３ (6b) (wherein n2 represents an integer of 1 to 5, and Y ３ is the same as the definition above.) CF ２ =CF-O-(CFX １ ) ｎ３ -Y ３ (6c) (wherein, X １ is F or CF ３ n3 represents an integer of 1 to 10; Y ３ is the same as the definition above.) CF ２ =CF-O-(CF ２ CFX １ O) ｎ４ -(CF ２ ) ｎ６ -Y ３ (6d) (wherein n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and Y ３ and X １ is the same as the definition above.) CF ２ =CF-O-(CF ２ CF ２ CFX １ O) ｎ５ -CF ２ CF ２ CF ２ -Y ３ (6e) (wherein n5 represents an integer of 0 to 10, and Y ３ and X １is the same as the definition above.) CF ２ =CF−O(−CF ２ ) ｎ６ -O-CF ２ -Y ３ (6f) (wherein n6 represents an integer of 1 to 6, and Y ３ and X １ is the same as the above definition.)

[0262] In general formula (6a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. ３ is preferable in that it can provide a suitable water solubility and stability of the aqueous dispersion. ３ M is preferably Na, H, or NH because of ease of synthesis. ４ It is preferable that the compound is H or NH, in that it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0263] Examples of the compound represented by general formula (6a) include CF ２ =CF-O-CF ２ COOM, C.F. ２ =CF(OCF ２ CF ２ COOM), C.F. ２ =CF(OCF ２ CF ２ CF ２ COOM), C.F. ２ =CF(OCF ２ CF ２ SO ３ M), CF ２ =CF(OCF ２ SO ３ M), CF ２ =CF(OCF ２ CF ２ CF ２ SO ３ M) (wherein M is as defined above).

[0264] In the general formula (6b), n2 is preferably an integer of 3 or less from the viewpoint of the stability of the resulting aqueous dispersion, and Y ３is preferable in that it provides suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H or NH, in that M is less likely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0265] In the general formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferable in that it provides suitable water solubility and stability of the aqueous dispersion. ３ M is preferably H, Na or NH in that it improves dispersion stability. ４ It is preferable that:

[0266] In general formula (6d), X １ In terms of the stability of the aqueous dispersion, -CF ３ n4 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferable to -COOM or -SO in that it provides suitable water solubility and stability of the aqueous dispersion. ３ Preferably, M is H, Na or NH ４ It is preferable that:

[0267] Examples of the compound represented by general formula (6d) include CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ COOM, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF３ ) OCF ２ CF ２ SO ３ M., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CF ２ SO ３ M (wherein M is H, NH ４ or an alkali metal.

[0268] In the general formula (6e), n5 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferably -COOM in that it provides adequate water solubility and stability of the aqueous dispersion, and M is H, Na, or NH ４ It is preferable that:

[0269] Examples of the compound represented by general formula (6e) include CF ２ = CFOCF ２ CF ２ CF ２ COOM (wherein M is H, NH ４ or an alkali metal.

[0270] Examples of the compound represented by general formula (6f) include CF ２ = CFOCF ２ CF ２ CF ２ OCF ２ COOM (wherein M is H, NH ４ or an alkali metal.

[0271] In general formula (7), Rf is preferably a fluorine-containing alkylene group having 1 to 40 carbon atoms. In general formula (7), at least one of X and Y preferably contains a fluorine atom.

[0272] The compound represented by general formula (7) is represented by general formula (7a): CF ２ =CF-(CF ２ ) ｎ１ -Y ３ (7a) (wherein n1 represents an integer of 1 to 10, and Y ３is the same as defined above.) and a compound represented by general formula (7b): CF ２ =CF-(CF ２ C (CF ３ ) F) ｎ２ -Y ３ (7b) (wherein n2 represents an integer of 1 to 5, and Y ３ is as defined above.

[0273] Y in general formula (7) ３ is -SO ３ M or -COOM is preferred, where M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. ７ represents H or an organic group.

[0274] In general 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 can provide suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH in that it is less likely to remain as an impurity and the heat resistance of the resulting molded product is improved. ４ It is preferable that:

[0275] Examples of the compound represented by general formula (7a) include CF ２ =CFCF ２ COOM (wherein M is as defined above).

[0276] In the general 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 NH in that it is less likely to remain as an impurity and the heat resistance of the resulting molded product is improved. ４ It is preferable that:

[0277] The fluorine-containing compound (A) is preferably at least one selected from the group consisting of compounds represented by general formula (5), compounds represented by general formula (6), and compounds represented by general formula (7), more preferably at least one selected from the group consisting of compounds represented by general formula (5) and compounds represented by general formula (6), and even more preferably a compound represented by general formula (5).

[0278] The compound represented by general formula (5) is preferably at least one selected from the group consisting of compounds represented by general formula (5a), compounds represented by general formula (5b), and compounds represented by general formula (5c). Among these, at least one selected from the group consisting of compounds represented by general formula (5a) and compounds represented by general formula (5b) is more preferred, and compounds represented by general formula (5a) are even more preferred.

[0279] In the polymerization of the fluoromonomer, the amount of the fluorine-containing compound (A) relative to the aqueous medium is preferably 3 to 5000 ppm by mass, more preferably 5 ppm by mass or more, even more preferably 10 ppm by mass or more, particularly preferably 20 ppm by mass or more, and most preferably 30 ppm by mass or more, and is more preferably 1000 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 200 ppm by mass or less, and most preferably 100 ppm by mass or less.

[0280] It is also preferable to adjust the amount of the fluorine-containing compound (A) depending on the type of polymerization initiator used in the polymerization and the polymerization temperature. When a non-redox polymerization initiator is used as the polymerization initiator and polymerization is carried out at 40 to 70°C, the amount of the fluorine-containing compound (A) is preferably 3 to 300 ppm by mass, more preferably 3 to 150 ppm by mass, even more preferably 5 to 100 ppm by mass, and most preferably 8 to 80 ppm by mass, relative to the aqueous medium. When a non-redox polymerization initiator is used as the polymerization initiator and polymerization is carried out at a temperature higher than 70°C and not higher than 98°C, the amount of the fluorine-containing compound (A) is preferably 3 to 500 ppm by mass, more preferably 3 to 200 ppm by mass, even more preferably 5 to 120 ppm by mass, and most preferably 20 to 110 ppm by mass, relative to the aqueous medium. When a redox polymerization initiator is used as the polymerization initiator and polymerization is carried out at 10°C or higher and lower than 40°C, the amount of the fluorine-containing compound (A) is preferably 3 to 300 ppm by mass, more preferably 3 to 100 ppm by mass, even more preferably 5 to 80 ppm by mass, and most preferably 10 to 70 ppm by mass, relative to the aqueous medium. When a redox polymerization initiator is used as the polymerization initiator and polymerization is carried out at 40 to 70°C, the amount of the fluorine-containing compound (A) is preferably 3 to 500 ppm by mass, more preferably 5 to 300 ppm by mass, even more preferably 10 to 200 ppm by mass, and most preferably 15 to 150 ppm by mass, relative to the aqueous medium. When a redox polymerization initiator is used as the polymerization initiator and polymerization is carried out at a temperature higher than 70°C and not higher than 98°C, the amount of the fluorine-containing compound (A) is preferably 5 to 500 ppm by mass, more preferably 8 to 300 ppm by mass, still more preferably 15 to 200 ppm by mass, and most preferably 20 to 150 ppm by mass, relative to the aqueous medium. By ensuring that the amount of the fluorine-containing compound (A) is within the above range, the adhesion rate can be further reduced and the polymerization time can be shortened.

[0281] The fluorine-containing compound (A) is preferably added before the polymerization initiator is added to start the polymerization reaction, and more preferably added only before the polymerization reaction is started, and not added after the start of the polymerization.

[0282] (Fluorine-containing surfactant) In the production method of the present disclosure, it is preferable to carry out the polymerization of the fluoromonomer substantially in the absence of a fluorine-containing surfactant.In the production method of the present disclosure, since the above-mentioned cyclic compound is used when polymerizing the fluoromonomer, the polymerization of the fluoromonomer proceeds smoothly even without using a fluorine-containing surfactant.

[0283] In the present disclosure, "substantially in the absence of a 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 50 ppb by mass or less, still more preferably 25 ppb by mass or less, still more preferably 10 ppb by mass or less, and still more preferably 1 ppb by mass or less.

[0284] In one embodiment, the fluorine-containing surfactant is a compound that does not have an unsaturated bond and has a fluorine atom and a hydrophilic group. Specific examples of the fluorine-containing surfactant include compounds represented by the following formulas. The fluorine-containing surfactant may be a mixture of these compounds. F(CF ２ ) ７ COOM, F(CF ２ ) ５ COOM, C.F. ３ O (CF ２ ) ３ OCHFCF ２ COOM, C. ３ F ７ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C. ２ F ５ OCF (CF ３ )CF ２OCF (CF ３ ) COOM, C.F. ３ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ２ ClCF ２ CF ２ OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF ２ CF ２ OCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF ２ CF (CF ３ ) OCF ２ COOM, and (In each formula, M is H, metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. １ is H or an organic group.

[0285] (Fluoromonomer) As the fluoromonomer, it is preferable that it has at least one double bond.As the fluoromonomer, tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinyl fluoride, vinylidene fluoride [VDF], trifluoroethylene, fluoroalkyl vinyl ether, fluoroalkyl ethylene, fluoroalkyl allyl ether, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, general formula (100): CHX １０１ =CX １０２ Rf １０１ (In the formula, X １０１and X １０２ is H on one side and F on the other side, and Rf １０１ is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), a fluorinated vinyl heterocycle, and a monomer that provides a crosslinking site.

[0286] In one embodiment, the fluoromonomer used is at least one selected from the group consisting of vinylidene fluoride and tetrafluoroethylene.

[0287] Examples of the fluoroalkyl vinyl ether include those represented by the general formula (110): CF ２ =CF-ORf １１１ (wherein, Rf １１１ represents a perfluoroorganic group.) A fluoromonomer represented by general formula (120): CF ２ =CF-OCH ２ -Rf １２１ (wherein, Rf １２１ is a perfluoroalkyl group having 1 to 5 carbon atoms), a fluoromonomer represented by the general formula (130): CF ２ = CFOCF ２ ORf １３１ (wherein, Rf １３１ is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms.) Fluoromonomers represented by general formula (140): CF ２ = CFO (CF ２ CF (Y １４１ ) O) ｍ (CF ２ ) ｎ F (wherein, Y １４１ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.) and a fluoromonomer represented by the general formula (150): CF ２ =CF-O-(CF ２ CFY １５１ -O) ｎ -(CFY１５２ ) ｍ -A １５１ (In the formula, Y １５１ represents a fluorine atom, a chlorine atom, -SO ２ It represents a F group or a perfluoroalkyl group. The perfluoroalkyl group is an etheric oxygen and -SO ２ The group n may contain an F group. n represents an integer of 0 to 3. １５１ may be the same or different. １５２ represents a fluorine atom, a chlorine atom, or —SO ２ represents an F group, and m represents an integer of 1 to 5. １５２ may be the same or different. １５１ is -SO ２ X １５１ , -COZ １５１ or -POZ １５２ Z １５３ represents. １５１ is F, Cl, Br, I, -OR １５１ or -NR １５２ R １５３ Represents Z. １５１ , Z １５２ and Z １５３ are the same or different and represent -NR １５４ R １５５ Or -OR １５６ Represents R １５１ , R １５２ , R １５３ , R １５４ , R １５５ and R １５６ are the same or different and represent H, ammonium, an alkali metal, an alkyl group which may contain a fluorine atom, an aryl group, or a sulfonyl-containing group.

[0288] In the present disclosure, the term "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen atom.

[0289] The fluoromonomer represented by the general formula (110) is Rf １１１is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0290] Examples of the perfluoroorganic group in the general formula (110) include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. The fluoromonomer represented by the general formula (110) further includes a fluoromonomer represented by the general formula (110) in which Rf １１１ is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf １１１ is of the following formula:

[0291]

[0292] (wherein m represents 0 or an integer of 1 to 4), and Rf is a group represented by the following formula:

[0293] CF ３ CF ２ CF ２ -(O-CF(CF ３ )-CF ２ ) ｎ - (wherein n represents an integer of 1 to 4).

[0294] Among the fluoromonomers represented by the general formula (110), those represented by the general formula (160): CF ２ =CF-ORf １６１ (wherein, Rf １６１ Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. １６１ is preferably a perfluoroalkyl group having 1 to 5 carbon atoms.

[0295] The fluoroalkyl vinyl ether is preferably at least one selected from the group consisting of fluoromonomers represented by the general formulas (160), (130) and (140).

[0296] The fluoromonomer represented by general formula (160) is preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), and more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether).

[0297] The fluoromonomer represented by the general formula (130) is CF ２ = CFOCF ２ OCF ３ , C.F. ２ = CFOCF ２ OCF ２ CF ３ , and CF ２ = CFOCF ２ OCF ２ CF ２ OCF ３ It is preferable that the polymer is at least one selected from the group consisting of:

[0298] The fluoromonomer represented by the general formula (140) is CF ２ = CFOCF ２ CF (CF ３ ) O(CF ２ ) ３ F, CF ２ = CFO (CF ２ CF (CF ３ ) O) ２ (CF ２ ) ３ F and CF ２ = CFO (CF ２ CF (CF ３ ) O) ２ (CF ２ ) ２ It is preferable that the compound is at least one selected from the group consisting of F.

[0299] The fluoromonomer represented by the general formula (150) is CF ２ = CFOCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF３ ) OCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF ２ CF ２ SO ２ F) OCF ２ CF ２ SO ２ F and CF ２ = CFOCF ２ CF (SO ２ F) ２ At least one selected from the group consisting of:

[0300] The fluoromonomer represented by the general formula (100) is Rf １０１ is a linear fluoroalkyl group, and Rf １０１ More preferred is a fluoromonomer in which Rf is a linear perfluoroalkyl group. １０１ The number of carbon atoms of the fluoromonomer represented by the general formula (100) is preferably 1 to 6. ２ =CFCF ３ , C.H. ２ =CFCF ２ CF ３ , C.H. ２ =CFCF ２ CF ２ CF ３ , C.H. ２ =CFCF ２ CF ２ CF ２ H, CH ２ =CFCF ２ CF ２ CF ２ CF ３ , CHF=CHCF ３ (E form), CHF=CHCF ３ (Z-isomer), among which CH ２ =CFCF ３ Preferred is 2,3,3,3-tetrafluoropropylene represented by the following formula:

[0301] The fluoroalkylethylene includes fluoroalkyl ethylenes represented by the general formula (170): CH ２ =CH-(CF２ ) ｎ -X １７１ (In the formula, X １７１ is H or F, and n is an integer of 3 to 10.) is preferred, and CH ２ =CH-C ４ F ９ , and C.H. ２ =CH-C ６ F １３ It is more preferable that the polymer is at least one selected from the group consisting of:

[0302] Examples of the fluoroalkyl allyl ether include those represented by the general formula (180): CF ２ =CF-CF ２ -ORf １１１ (wherein, Rf １１１ represents a perfluoroorganic group.

[0303] Rf of general formula (180) １１１ is Rf in general formula (110). １１１ Rf is the same as １１１ As the fluoroalkyl aryl ether represented by the general formula (180), a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. ２ =CF-CF ２ -O-CF ３ , C.F. ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ At least one selected from the group consisting of CF ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F７ , and CF ２ =CF-CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ =CF-CF ２ -O-CF ２ CF ２ CF ３ is more preferable.

[0304] The fluorinated vinyl heterocycle may be a heterocyclic compound represented by the general formula (230): (In the formula, X ２３１ and X ２３２ are independently F, Cl, a methoxy group, or a fluorinated methoxy group; Y ２３１ is the formula Y ２３２ or formula Y ２３３ is.

[0305] (In the formula, Z ２３１ and Z ２３２ are independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0306] The monomer that provides the crosslinking site is CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ I, CF ２ = CFOCF ２ CF ２ CH ２ I, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CN, CH２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOH, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CH ２ OH, CH ２ = CHCF ２ CF ２ I, CH ２ =CH(CF ２ ) ２ CH=CH ２ , C.H. ２ =CH(CF ２ ) ６ CH=CH ２ , and CF ２ = CFO (CF ２ ) ５ CN, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN and CF ２ = CFOCF ２ CF ２ CH ２ It is more preferable that the compound is at least one selected from the group consisting of I.

[0307] In the polymerization, the fluoromonomer may be polymerized with a non-fluorine-containing monomer, such as a hydrocarbon-based monomer reactive with the fluoromonomer.

[0308] Examples of the hydrocarbon monomer include ethylene and propylene.

[0309] The fluorine-free monomer may also be a hydrocarbon monomer containing a functional group (excluding monomers that provide crosslinking sites).

[0310] In the manufacturing method of the present disclosure, it is preferable to use at least TFE as fluoromonomer.In one embodiment, as fluoromonomer, use only TFE or the combination of TFE and the fluoromonomer other than TFE.As the fluoromonomer other than TFE, among the above-mentioned fluoromonomers, the fluoromonomer other than TFE can be mentioned, and for example, can suitably use at least one selected from the group consisting of HFP, CTFE, fluoroalkyl vinyl ether, fluoroalkyl ethylene and fluoroalkyl allyl ether.

[0311] In the above polymerization, the desired fluoropolymer can be obtained by polymerizing one or more of the above fluoromonomers.

[0312] (Aqueous dispersion containing a fluoropolymer) An aqueous dispersion containing a fluoropolymer can be obtained by the production method of the present disclosure. The concentration of the fluoropolymer in the aqueous dispersion is usually 8 to 50 mass%. The lower limit of the fluoropolymer concentration in the aqueous dispersion is preferably 10 mass%, more preferably 15 mass%, and the upper limit is preferably 40 mass%, more preferably 35 mass%.

[0313] The fluoropolymer content in the aqueous dispersion is a value obtained by drying 1 g of the aqueous dispersion in a blower dryer at 150°C for 60 minutes, measuring the mass of the heating residue, and expressing the ratio of the mass of the heating residue to the mass (1 g) of the aqueous dispersion as a percentage.

[0314] Examples of the fluoropolymer include a TFE polymer in which the monomer having the largest molar fraction in the polymer (hereinafter referred to as "the most abundant monomer") is TFE, and a VDF polymer in which the most abundant monomer is VDF.

[0315] Preferably, the fluoropolymer has an ion exchange ratio (IXR) greater than 53. Preferred fluoropolymers have no ionic groups or a limited number of ionic groups resulting in an ion exchange ratio greater than about 100. Preferred fluoropolymers have an ion exchange ratio of 1000 or greater, more preferably 2000 or greater, and even more preferably 5000 or greater.

[0316] The TFE polymer may suitably be a TFE homopolymer or a copolymer comprising (1) TFE, (2) one or more fluorine-containing monomers other than TFE having 2 to 8 carbon atoms, particularly VDF, HFP, or CTFE, and (3) other monomers. Examples of the (3) other monomers include fluoro(alkyl vinyl ethers) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms; fluorodioxole; perfluoroalkylethylene; ω-hydroperfluoroolefin, etc.

[0317] The TFE polymer may also be a copolymer of TFE and one or more fluorine-free monomers. Examples of the fluorine-free monomers include alkenes such as ethylene and propylene; vinyl esters; and vinyl ethers. The TFE polymer may also be a copolymer of TFE and one or more fluorine-containing monomers having 2 to 8 carbon atoms and one or more fluorine-free monomers.

[0318] The VDF polymer may suitably be a VDF homopolymer [PVDF] or a copolymer of (1) VDF, (2) one or more fluoroolefins other than VDF having 2 to 8 carbon atoms, particularly TFE, HFP, or PMVE, and (3) a perfluoro(alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms.

[0319] The fluoropolymers may be glassy, ​​plastic or elastomeric. They may be amorphous or partially crystalline and may be subject to compression sintering, melt processing or non-melt processing.

[0320] In the production method of the present disclosure, for example, (I) as a non-melt-processable fluororesin, tetrafluoroethylene polymer [TFE polymer (PTFE)] is used, (II) as a melt-processable fluororesin, ethylene / TFE copolymer [ETFE], TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoroallyl ether copolymer, TFE / VDF copolymer, electrolyte polymer precursor is used, and (III) as a fluorine-containing elastomer, TF Suitable examples of the copolymers that can be produced include VDF / propylene copolymers, TFE / propylene / third monomer copolymers (wherein the third monomer is VDF, HFP, CTFE, a fluoroalkyl vinyl ether, or the like), copolymers of TFE and a fluoroalkyl vinyl ether; HFP / ethylene copolymers, HFP / ethylene / TFE copolymers; VDF / HFP copolymers, HFP / ethylene copolymers, VDF / TFE / HFP copolymers; and the fluorine-containing segmented polymers described in JP-B-61-49327.

[0321] The fluoropolymer may have a core-shell structure.

[0322] (Fluorine-Containing Elastomer) In one embodiment, an aqueous dispersion containing a fluorine-containing elastomer as the fluoropolymer is produced using the production method of the present disclosure.

[0323] According to the manufacturing method of the present disclosure, a methylene group (—CH ２ It is possible to produce an aqueous dispersion containing a fluorine-containing elastomer having a methylene group (-CH ２ As the fluorine-containing elastomer (partially fluorinated elastomer) containing —CH ２ There is no particular limitation as long as it contains a chemical structure represented by -, and examples thereof include -CH ２ -CF ２ -, -CH ２ -CH(CH ３ ) -, -CH ２ -CH ２ -, -CH ２ -CF ２ -(CF ３)-, and these can be introduced into the main chain of the fluorine-containing elastomer by polymerizing, for example, vinylidene fluoride, propylene, ethylene, 2,3,3,3-tetrafluoropropylene, etc.

[0324] Examples of fluorine-containing elastomers include tetrafluoroethylene (TFE), vinylidene fluoride (VdF), and fluororesin having the general formula: CF ２ =CF-Rf ａ (wherein, Rf ａ Ha-CF ３ or -ORf ｂ (Rf ｂ It is preferable that the fluorine-containing elastomer contains a structural unit derived from at least one monomer selected from the group consisting of perfluoroethylenically unsaturated compounds represented by the formula (C1-C5 perfluoroalkyl group) (for example, hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE)), etc. Among these, it is preferable that the fluorine-containing elastomer contains a VdF unit or a TFE unit.

[0325] More specific examples of the fluorine-containing elastomer include VdF-based fluorine-containing elastomers, TFE / propylene (Pr)-based fluorine-containing elastomers, TFE / Pr / VdF-based fluorine-containing elastomers, ethylene (Et) / HFP-based fluorine-containing elastomers, Et / HFP / VdF-based fluorine-containing elastomers, Et / HFP / TFE-based fluorine-containing elastomers, Et / TFE / PAVE-based fluorine-containing elastomers, etc. Among these, VdF-based fluorine-containing elastomers, TFE / Pr-based fluorine-containing elastomers, TFE / Pr / VdF-based fluorine-containing elastomers and Et / TFE / PAVE-based fluorine-containing elastomers are more preferred in terms of good heat aging resistance and oil resistance.

[0326] The VdF-based fluorine-containing elastomer is a fluorine-containing elastomer having VdF units. In the VdF-based fluorine-containing elastomer, the VdF units preferably account for 20 mol % or more and 90 mol % or less, more preferably 40 mol % or more and 85 mol % or less, still more preferably 45 mol % or more and 80 mol % or less, and particularly preferably 50 mol % or more and 80 mol % or less, of the total number of moles of the VdF units and monomer units derived from other monomers.

[0327] The other monomer in the VdF-based fluorine-containing elastomer is not particularly limited as long as it is a monomer copolymerizable with VdF, and for example, the above-mentioned fluoromonomers can be used.

[0328] The VdF-based fluorine-containing elastomer is preferably at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, VdF / Et / HFP copolymer, and a copolymer of VdF / a fluoromonomer represented by general formula (100).More preferably, the other monomer besides VdF is at least one monomer selected from the group consisting of TFE, HFP, and PAVE.

[0329] Of these, the VdF-based fluorine-containing elastomer is preferably at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / copolymer of a fluoromonomer represented by general formula (100), VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, and VdF / HFP / TFE / PAVE copolymer, and more preferably at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / HFP / TFE copolymer, VdF / copolymer of a fluoromonomer represented by general formula (100), and VdF / PAVE copolymer.

[0330] The VdF / PAVE copolymer preferably has a VdF / PAVE composition of (65 to 90) / (35 to 10) (mol %). Another preferred embodiment has a VdF / PAVE composition of (50 to 78) / (50 to 22) (mol %).

[0331] The VdF / TFE / PAVE copolymer preferably has a VdF / TFE / PAVE composition of (40-80) / (3-40) / (15-35) (mol %).

[0332] The VdF / HFP / PAVE copolymer preferably has a VdF / HFP / PAVE composition of (65 to 90) / (3 to 25) / (3 to 25) (mol %).

[0333] The VdF / HFP / TFE / PAVE copolymer preferably has a VdF / HFP / TFE / PAVE composition of (40 to 90) / (0 to 25) / (0 to 40) / (3 to 35) (mol %), and more preferably has a VdF / HFP / TFE / PAVE composition of (40 to 80) / (3 to 25) / (3 to 40) / (3 to 25) (mol %).

[0334] As the copolymer of VdF / fluoromonomer represented by general formula (100), the VdF / fluoromonomer unit represented by general formula (100) is (85 to 20) / (15 to 80) (mol%), and other monomer units other than VdF and the fluoromonomer represented by general formula (100) are preferably 0 to 50 mol% of the total monomer units, and the molar ratio of VdF / fluoromonomer unit represented by general formula (100) is more preferably (80 to 20) / (20 to 80). In addition, one preferred embodiment is that the composition of VdF / fluoromonomer unit represented by general formula (100) is (78 to 50) / (22 to 50) (mol%).

[0335] Also preferred as the copolymer of VdF / fluoromonomer represented by general formula (100) is one in which the VdF / fluoromonomer units represented by general formula (100) are (85 to 50) / (15 to 50) (mol%), and the other monomer units other than VdF and the fluoromonomer represented by general formula (100) account for 1 to 50 mol% of all monomer units. Preferred other monomers other than VdF and the fluoromonomer represented by general formula (100) are TFE, HFP, perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), perfluoroethyl propyl ether (PPVE), CTFE, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, Et, Pr, alkyl vinyl ethers, and monomers that provide crosslinkable groups, which are exemplified as other monomers in VdF-based fluorine-containing elastomers, and among these, PMVE, CTFE, HFP, and TFE are more preferred.

[0336] The TFE / Pr-based fluorine-containing elastomer refers to a fluorine-containing copolymer consisting of 45 to 70 mol % of TFE and 55 to 30 mol % of Pr. In addition to these two components, a specific third component may be contained.

[0337] The specific third component may include, for example, fluoromonomers such as fluorine-containing olefins other than TFE (e.g., VdF, HFP, CTFE, perfluoro(butyl ethylene), etc.), fluorine-containing vinyl ethers (perfluoro(propyl vinyl ether), perfluoro(methyl vinyl ether), etc.); hydrocarbon monomers such as α-olefins (ethylene, 1-butene, etc.), vinyl ethers (ethyl vinyl ether, butyl vinyl ether, hydroxybutyl vinyl ether, etc.), and vinyl esters (vinyl acetate, vinyl benzoate, vinyl crotonate, vinyl methacrylate, etc.). The specific third component may be used alone or in combination of two or more.

[0338] The TFE / Pr-based fluorine-containing elastomer preferably contains VdF, and among TFE / Pr-based fluorine-containing elastomers, an elastomer consisting of TFE, Pr and VdF is called a TFE / Pr / VdF-based fluorine-containing elastomer.

[0339] The TFE / Pr / VdF-based fluorine-containing elastomer may further contain the specific third component other than VdF. The specific third component may be one type or a combination of two or more types. The total content of the third components in the TFE / Pr-based fluorine-containing elastomer is preferably 35 mol% or less, more preferably 33 mol% or less, and even more preferably 31 mol% or less.

[0340] The Et / HFP copolymer preferably has an Et / HFP composition of (35 to 80) / (65 to 20) (mol %), more preferably (40 to 75) / (60 to 25) (mol %).

[0341] The Et / HFP / TFE copolymer preferably has an Et / HFP / TFE composition of (35 to 75) / (25 to 50) / (0 to 15) (mol %), more preferably (45 to 75) / (25 to 45) / (0 to 10) (mol %).

[0342] The Et / TFE / PAVE copolymer preferably has an Et / TFE / PAVE composition of (10-40) / (32-60) / (20-40) (mol %), more preferably (20-40) / (40-50) / (20-30) (mol %). PMVE is preferred as the PAVE.

[0343] The fluorine-containing elastomer is preferably a fluorine-containing elastomer containing a VdF unit, more preferably a VdF / HFP copolymer or a VdF / HFP / TFE copolymer, and particularly preferably one having a VdF / HFP / TFE composition of (32-85) / (10-34) / (0-40) (mol%), more preferably (32-85) / (15-34) / (0-34) (mol%), and even more preferably (47-81) / (17-32) / (0-30) (mol%).

[0344] For example, in the above VdF / HFP copolymer, the VdF / HFP composition is preferably (45 to 85) / (15 to 55) (mol%), more preferably (50 to 83) / (17 to 50) (mol%), still more preferably (55 to 81) / (19 to 45) (mol%), and particularly preferably (60 to 80) / (20 to 40) (mol%).

[0345] The above-mentioned structure is the structure of the main monomer of the fluorine-containing elastomer, and in addition to the main monomer, a monomer that provides a crosslinkable group may be copolymerized. The monomer that provides a crosslinkable group may be any monomer that can introduce an appropriate crosslinkable group into the fluorine-containing elastomer depending on the production method and crosslinking system, and examples thereof include known polymerizable compounds containing a crosslinkable group such as an iodine atom, a bromine atom, a carbon-carbon double bond, a cyano group, a carboxyl group, a hydroxyl group, an amino group, or an ester group.

[0346] Preferred examples of the monomer that provides a crosslinkable group include those represented by the general formula (3): CY １ ２ =CY ２ R ｆ ２ X １ (3) (wherein, Y １ , Y ２ is a fluorine atom, a hydrogen atom, or —CH ３ ;R ｆ ２ represents a linear or branched fluorine-containing alkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, which may have one or more ether-bonded oxygen atoms and which may have an aromatic ring; X １ is an iodine atom or a bromine atom).

[0347] Specific examples of the monomer that provides a crosslinkable group include those represented by the general formula (4): CY １ ２ =CY ２ R ｆ ３ CHR １ -X １ (4) (wherein, Y １ , Y ２ , X １is the same as above, and R ｆ ３ is a linear or branched fluorine-containing alkylene group which may have one or more ether-bonded oxygen atoms and in which some or all of the hydrogen atoms have been substituted with fluorine atoms, i.e., a linear or branched fluorine-containing alkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, a linear or branched fluorine-containing oxyalkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, or a linear or branched fluorine-containing polyoxyalkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms; R １ represents a hydrogen atom or a methyl group), iodine- or bromine-containing monomers represented by the general formulas (5) to (22): CY ４ ２ =CY ４ (CF ２ ) ｎ -X １ (5) (wherein, Y ４ are the same or different and are a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8) CF ２ =CFCF ２ R ｆ ４ -X １ (6) (wherein, R ４ is -(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ -, and n is an integer from 0 to 5) CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF ２ -X １ (7) (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) CF ２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３ )CF２ ) ｎ OCF (CF ３ )-X １ (8) (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -X １ (9) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -X １ (10) CF (wherein m is an integer of 1 to 5) ２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-X １ )CF ３ (11) CF (wherein n is an integer from 1 to 4) ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-X １ (12) CF (wherein n is an integer of 2 to 5) ２ = CFO (CF ２ ) ｎ -(C ６ H ４ )-X １ (13) CF (wherein n is an integer from 1 to 6) ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-X １ (14) (wherein n is an integer of 1 to 2) CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３ )-X １ (15) (wherein n is an integer of 0 to 5), CF ２= CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -X １ (16) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-X １ (17) CH ２ =CFCF ２ OCH ２ CF ２ -X １ (18) CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-X １ (19) (wherein m is an integer of 0 or more) CF ２ = CFOCF(CF ３ )CF ２ O (CF ２ ) ｎ -X １ (20) (wherein n is an integer of 1 or more) CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF ２ -X １ (21) CH ２ =CH-(CF ２ ) ｎ X １ (22) (wherein n is an integer of 2 to 8) (in the general formulas (5) to (22), X １ are the same as above), and the like, which can be used alone or in any combination.

[0348] The iodine- or bromine-containing monomer represented by the general formula (4) includes a monomer represented by the general formula (23): (wherein m is an integer of 1 to 5, and n is an integer of 0 to 3), and more specifically, Among these, ICH ２ CF ２ CF ２ OCF = CF ２ is preferred.

[0349] More specifically, the iodine- or bromine-containing monomer represented by the general formula (5) is ICF ２ CF ２ CF=CH ２ , I(CF ２ CF ２ ) ２ CF=CH ２ are preferred.

[0350] More specifically, the iodine- or bromine-containing monomer represented by the general formula (9) is I(CF ２ CF ２ ) ２ OCF = CF ２ are preferred.

[0351] More specifically, the iodine- or bromine-containing monomer represented by the general formula (22) is CH ２ = CHCF ２ CF ２ I, I (CF ２ CF ２ ) ２ CH=CH ２ are preferred.

[0352] Also, the formula: R ２ R ３ C=CR ４ -Z-CR ５ =CR ６ R ７ (In the formula, R ２ , R ３ , R ４ , R ５ , R ６ and R ７are the same or different and are both H or an alkyl group having 1 to 5 carbon atoms; Z is a linear or branched alkylene or cycloalkylene group having 1 to 18 carbon atoms, which may contain an oxygen atom, and is preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene group. In the present disclosure, the term "(per)fluoropolyoxyalkylene group" means a "fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group."

[0353] Z is preferably a (per)fluoroalkylene group having 4 to 12 carbon atoms, and R ２ , R ３ , R ４ , R ５ , R ６ and R ７ is preferably a hydrogen atom.

[0354] When Z is a (per)fluoropolyoxyalkylene group, the formula: -(Q) ｐ -CF ２ O-(CF ２ CF ２ O) ｍ -(CF ２ O) ｎ -CF ２ -(Q) ｐ - (wherein Q is an alkylene group having 1 to 10 carbon atoms or an oxyalkylene group having 2 to 10 carbon atoms, p is 0 or 1, and m and n are integers such that the m / n ratio is 0.2 to 5 and the molecular weight of the (per)fluoropolyoxyalkylene group is in the range of 500 to 10,000, preferably 1,000 to 4,000). In this formula, Q is preferably -CH ２ OCH ２ - and -CH ２ O (CH ２ CH ２ O) ｓ CH ２ -(s=1 to 3).

[0355] Preferred bisolefins are CH ２=CH-(CF ２ ) ２ -CH=CH ２ , C.H. ２ =CH-(CF ２ ) ４ -CH=CH ２ , C.H. ２ =CH-(CF ２ ) ６ -CH=CH ２ , Formula: CH ２ = CH-Z １ -CH=CH ２ (In the formula, Z １ Ha-CH ２ OCH ２ -CF ２ O-(CF ２ CF ２ O) ｍ -(CF ２ O) ｎ -CF ２ -CH ２ OCH ２ - (m / n is 0.5, and the molecular weight is preferably 2000).

[0356] Among them, CH ２ =CH-(CF ２ ) ６ -CH=CH ２ Preferred is 3,3,4,4,5,5,6,6,7,7,8,8-dodecafluoro-1,9-decadiene represented by the following formula:

[0357] The number average molecular weight Mn of the fluorine-containing elastomer is preferably from 1,000 to 1,000,000, more preferably from 10,000 to 500,000, and particularly preferably from 20,000 to 300,000.

[0358] The fluorine content of the fluorine-containing elastomer is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. The upper limit of the fluorine content is preferably 75% by mass or less, and more preferably 73% by mass or less. １９ F-NMR and １ It is calculated based on measurements such as H-NMR and elemental analysis.

[0359] The fluorine-containing elastomer preferably has a Mooney viscosity at 100°C (ML1+10(100°C)) of 130 or less. The Mooney viscosity is more preferably 110 or less, and even more preferably 90 or less. The Mooney viscosity is more preferably 10 or more, and even more preferably 20 or more. The Mooney viscosity here is a value measured in accordance with JIS K 6300-1.2013.

[0360] The fluorine-containing elastomer preferably has a glass transition temperature of -50 to 0°C. The glass transition temperature is more preferably -2°C or lower, and even more preferably -3°C or lower. The glass transition temperature is more preferably -45°C or higher, and even more preferably -40°C or higher. The glass transition temperature may be -10°C or higher, or may be -9°C or higher. Here, the glass transition temperature can be determined from the DSC differential curve in accordance with JIS K6240:2011, using a differential scanning calorimeter (for example, X-DSC7000 manufactured by Hitachi High-Tech Science Corporation) to obtain a DSC curve by heating 10 mg of a sample at a rate of 20°C / min.

[0361] The fluorine-containing elastomer preferably has an iodine content of 0.05 to 1.0% by mass, more preferably 0.08% by mass or more, even more preferably 0.10% by mass or more, and more preferably 0.80% by mass or less, even more preferably 0.60% by mass or less.

[0362] The iodine content can be determined by elemental analysis. ２ SO ３ Mix 5 mg of Na in 20 ml of pure water. ２ CO ３ and K. ２ CO ３ The absorbent solution is prepared by dissolving 30 mg of a 1:1 (mass ratio) mixture of KI and iodine ions in oxygen in a quartz flask, and after leaving it for 30 minutes, the absorbent is measured using a Shimadzu 20A ion chromatograph. For the calibration curve, a KI standard solution containing 0.5 mass ppm of iodine ions and a solution containing 1.0 mass ppm of iodine ions can be used.

[0363] The fluorine-containing elastomer is preferably —CH ２ I structure. ２ The inclusion of the I structure is １ This can be confirmed by H-NMR spectrum. ２ The fluorine-containing elastomer containing the I structure can be obtained by iodine transfer polymerization.

[0364] The fluorine-containing elastomer is —CH ２ -CH relative to 100 mol% of the structure ２ The amount of the I structure is preferably 0.05 to 1.50 mol %. ２ The amount of the I structure is more preferably 0.08 mol % or more, even more preferably 0.12 mol % or more, more preferably 1.20 mol % or less, still more preferably 1.00 mol % or less, and particularly preferably 0.80 mol % or less. ２ The amount of I structure is １ It can be determined by H-NMR spectrum.

[0365] The fluorine-containing elastomer is more preferably —CF ２ CH ２ Contains the I structure. ２ CH ２ The fluorine-containing elastomer containing the I structure can be obtained by producing a VdF-based fluorine-containing elastomer by iodine transfer polymerization.

[0366] The fluorine-containing elastomer is —CH ２ -CF relative to 100 mol% of the structure ２ CH ２ The amount of the I structure is preferably 0.05 to 1.50 mol %. ２ CH ２ The amount of the I structure is more preferably 0.08 mol% or more, even more preferably 0.12 mol% or more, more preferably 1.20 mol% or less, still more preferably 1.00 mol% or less, and particularly preferably 0.80 mol% or less. ２ CH ２ The amount of I structure is １ In the H-NMR spectrum, -CH ２ The integral value A of all peak intensities observed in the chemical shift region of 3.75 to 4.05 ppm derived from I, and -CH２ The integral value B of all peak intensities observed in the chemical shift regions of 2.3 to 2.7 ppm and 2.9 to 3.75 ppm derived from the ion beam is calculated by A / B*100.

[0367] As the fluoromonomer used for producing the fluorine-containing elastomer, the above-mentioned fluoromonomers used for producing the fluoropolymer can be used appropriately.

[0368] The aqueous dispersion of a fluorine-containing elastomer may contain fluorine-containing elastomer particles. The average particle size of the fluorine-containing elastomer particles is preferably 10 to 800 nm, more preferably 50 to 500 nm, and even more preferably 70 to 300 nm. The average particle size of the fluorine-containing elastomer particles is a cumulant average diameter, and can be measured by dynamic light scattering.

[0369] The aqueous dispersion of the fluorine-containing elastomer can be made into a dispersion suitable for rubber molding processing by adding a dispersion stabilizer such as a hydrocarbon surfactant, concentrating the dispersion, etc., as necessary. The dispersion is then treated by pH adjustment, coagulation, heating, etc.

[0370] The aqueous dispersion of the fluorine-containing elastomer may be subjected to treatment such as coagulation or heating.

[0371] The coagulation can be carried out by adding alkaline earth and earth metal salts to the aqueous dispersion, such as sulfates, nitrates, hydrochlorides, and acetates of calcium, magnesium, aluminum, and the like.

[0372] The coagulated fluoroelastomer may be washed with water to remove small amounts of impurities such as buffer solutions and salts present in the fluoroelastomer, and then the washed fluoroelastomer may be dried at a drying temperature of preferably 40 to 200°C, more preferably 60 to 180°C, and even more preferably 80 to 150°C.

[0373] A fluorine-containing elastomer composition can be produced by adding a crosslinking agent, a filler, etc. to the fluorine-containing elastomer obtained by the production method of the present disclosure. The types and amounts of the crosslinking agent and filler are not particularly limited, and known ranges can be used.

[0374] The method for obtaining the fluorine-containing elastomer composition is not particularly limited as long as it is a method that can uniformly mix the fluorine-containing elastomer obtained by the production method of the present disclosure with the crosslinking agent, filler, etc. For example, there can be mentioned a method in which powder obtained by coagulating the fluorine-containing elastomer alone is kneaded with other additives and compounding ingredients as necessary in a kneader such as an open roll mixer.

[0375] Examples of the crosslinking system for the fluorine-containing elastomer include a peroxide crosslinking system, a polyol crosslinking system, a polyamine crosslinking system, etc., and it is preferably at least one selected from the group consisting of a peroxide crosslinking system and a polyol crosslinking system. From the viewpoint of chemical resistance, a peroxide crosslinking system is preferred, and from the viewpoint of heat resistance, a polyol crosslinking system is preferred.

[0376] Therefore, the crosslinking agent is preferably at least one crosslinking agent selected from the group consisting of polyol crosslinking agents and peroxide crosslinking agents, and more preferably a peroxide crosslinking agent.

[0377] The amount of the crosslinking agent to be added may be appropriately selected depending on the type of crosslinking agent, etc., but is preferably 0.2 to 6.0 parts by mass, more preferably 0.3 to 5.0 parts by mass, per 100 parts by mass of the fluorine-containing elastomer composition.

[0378] Peroxide crosslinking can be carried out by using a peroxide-crosslinkable uncrosslinked elastomer as the fluorine-containing elastomer and an organic peroxide as the crosslinking agent.

[0379] The peroxide-crosslinkable uncrosslinked elastomer is not particularly limited as long as it has a peroxide-crosslinkable moiety. The peroxide-crosslinkable moiety is not particularly limited, and examples thereof include a moiety having an iodine atom and a moiety having a bromine atom.

[0380] The organic peroxide may be any organic peroxide that can easily generate peroxy radicals in the presence of heat or a redox system, and examples thereof include 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α,α-bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, benzoyl peroxide, t-butylperoxybenzene, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, and t-butylperoxybenzoate. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3 are preferred.

[0381] The amount of the organic peroxide to be blended is preferably 0.1 to 15 parts by mass, more preferably 0.3 to 5 parts by mass, per 100 parts by mass of the fluorine-containing elastomer.

[0382] When the crosslinking agent is an organic peroxide, the fluorine-containing elastomer composition preferably further contains a crosslinking aid. Examples of the crosslinking aid include triallyl cyanurate and triallyl isocyanurate (TAIC). Among these, triallyl isocyanurate (TAIC) is preferred because of its excellent crosslinkability, mechanical properties, and flexibility.

[0383] The amount of cross-linking aid blended is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 7.0 parts by mass, and even more preferably 0.1 to 5.0 parts by mass, per 100 parts by mass of the fluorine-containing elastomer. If the amount of cross-linking aid is less than 0.01 part by mass, the mechanical properties and flexibility tend to deteriorate. If the amount exceeds 10 parts by mass, the heat resistance tends to deteriorate and the durability of the molded product also tends to deteriorate.

[0384] Polyol crosslinking can be carried out by using a polyol-crosslinkable uncrosslinked elastomer as the fluorine-containing elastomer and a polyhydroxy compound as the crosslinking agent. The amount of polyhydroxy compound in the polyol crosslinking system is preferably 0.01 to 10 parts by mass per 100 parts by mass of the polyol-crosslinkable uncrosslinked elastomer. By using an amount of polyhydroxy compound within this range, polyol crosslinking can be sufficiently promoted. It is more preferably 0.02 to 8 parts by mass. It is even more preferably 0.03 to 4 parts by mass.

[0385] The polyol-crosslinkable uncrosslinked elastomer is not particularly limited as long as it has a polyol-crosslinkable moiety. The polyol-crosslinkable moiety is not particularly limited, and examples thereof include moieties having vinylidene fluoride (VdF) units. Methods for introducing the crosslinkable moiety include copolymerizing a monomer that provides a crosslinkable moiety during polymerization of the uncrosslinked elastomer.

[0386] As the polyhydroxy compound, a polyhydroxy aromatic compound is preferably used because of its excellent heat resistance.

[0387] The polyhydroxy aromatic compound is not particularly limited, and examples thereof include 2,2-bis(4-hydroxyphenyl)perfluoropropane (hereinafter referred to as bisphenol AF. Bisphenol AF is available from, for example, Fujifilm Wako Pure Chemical Industries, Ltd. and Central Glass Co., Ltd.). These polyhydroxy aromatic compounds may be alkali metal salts or alkaline earth metal salts, but when the copolymer is coagulated using an acid, it is preferable not to use the above metal salts. The amount of the polyhydroxy aromatic compound to be blended is 0.1 to 15 parts by mass, preferably 0.5 to 5 parts by mass, per 100 parts by mass of the uncrosslinked elastomer.

[0388] When the crosslinking agent is a polyhydroxy compound, the fluorine-containing elastomer composition preferably further contains a crosslinking accelerator, which accelerates the formation of intramolecular double bonds in the dehydrofluorination reaction of the polymer main chain and the addition of the polyhydroxy compound to the formed double bonds.

[0389] The crosslinking accelerator may be used in combination with an acid acceptor such as magnesium oxide or a crosslinking aid.

[0390] Examples of the crosslinking accelerator include onium compounds, and among the onium compounds, at least one selected from the group consisting of ammonium compounds such as quaternary ammonium salts, phosphonium compounds such as quaternary phosphonium salts, oxonium compounds, sulfonium compounds, cyclic amines, and monofunctional amine compounds is preferred, and at least one selected from the group consisting of quaternary ammonium salts and quaternary phosphonium salts is more preferred.

[0391] The quaternary ammonium salt is not particularly limited, but DBU-B is preferred in terms of crosslinkability, mechanical properties, and flexibility.

[0392] The quaternary phosphonium salt is not particularly limited, but benzyltriphenylphosphonium chloride (BTPPC) is preferred in terms of crosslinkability, mechanical properties, and flexibility.

[0393] Furthermore, as the crosslinking accelerator, a solid solution of a quaternary ammonium salt and bisphenol AF, a solid solution of a quaternary phosphonium salt and bisphenol AF, or the chlorine-free crosslinking accelerator disclosed in JP-A-11-147891 can also be used.

[0394] The amount of crosslinking accelerator blended is preferably 0.01 to 8.00 parts by mass, more preferably 0.02 to 5.00 parts by mass, and even more preferably 0.03 to 3.00 parts by mass, relative to 100 parts by mass of the uncrosslinked elastomer. If the amount of crosslinking accelerator is less than 0.01 part by mass, crosslinking of the uncrosslinked elastomer may not proceed sufficiently, and the heat resistance and other properties of the resulting molded article may decrease. If the amount exceeds 8.00 parts by mass, the molding processability of the fluorine-containing elastomer composition may decrease, and the elongation and flexibility in the mechanical properties may also tend to decrease.

[0395] The acid acceptor is used to neutralize acidic substances generated during polyol crosslinking, and specific examples include magnesium oxide, calcium hydroxide (e.g., NICC5000 (manufactured by Inoue Lime Industry Co., Ltd.), CALDIC#2000, CALDIC#1000 (manufactured by Omi Chemical Industry Co., Ltd.)), calcium oxide, litharge (lead oxide), zinc oxide, dibasic lead phosphite, hydrotalcite, and the like, and is preferably at least one selected from the group consisting of high-activity magnesium oxide and low-activity magnesium oxide.

[0396] The fluorine-containing elastomer composition may, if necessary, be blended with various additives that are commonly blended into elastomers, such as fillers, processing aids, plasticizers, colorants, stabilizers, adhesion aids, mold release agents, electrical conductivity imparting agents, thermal conductivity imparting agents, surface anti-tack agents, flexibility imparting agents, heat resistance improvers, and flame retardants. These additives may be used within the range that does not impair the effects of the present disclosure.

[0397] Furthermore, a molded article can be obtained from the above-mentioned fluorine-containing elastomer composition. The molded article can be obtained by molding and crosslinking the above-mentioned fluorine-containing elastomer composition. The above-mentioned fluorine-containing elastomer composition can be molded by a conventionally known method. The molding and crosslinking methods and conditions may be within the range of known methods and conditions for the molding and crosslinking employed. The order of molding and crosslinking is not limited, and molding may be followed by crosslinking, crosslinking may be followed by molding, or molding and crosslinking may be carried out simultaneously.

[0398] Examples of molding methods include, but are not limited to, pressure molding using a mold or injection molding. Crosslinking methods that can be used include steam crosslinking, conventional methods in which a crosslinking reaction is initiated by heating, and radiation crosslinking, with crosslinking by heating being preferred. Specific crosslinking conditions that are not limited to these are typically a temperature range of 140 to 250°C and a crosslinking time of 1 minute to 24 hours, and can be determined appropriately depending on the type of crosslinking agent used.

[0399] Polytetrafluoroethylene In one embodiment, the manufacturing method of the present disclosure is used to produce an aqueous dispersion containing polytetrafluoroethylene (PTFE) as the fluoropolymer.

[0400] The PTFE may have a core-shell structure. Examples of fluoropolymers having a core-shell structure include modified PTFE particles containing a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE. Examples of such modified PTFE include the PTFE described in JP-A-2005-527652.

[0401] In the fluoropolymer having the core-shell structure, the lower limit of the shell ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 2.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the shell ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0402] PTFE can be produced by polymerizing at least TFE as a fluoromonomer. In the production of PTFE, various known modified monomers can also be used in combination. In this disclosure, PTFE is a concept that includes not only TFE homopolymer but also the copolymer of TFE and modified monomer (hereinafter referred to as "modified PTFE").

[0403] The modifying monomer is not particularly limited as long as it can be copolymerized with TFE, and includes fluoromonomers and non-fluoromonomers. The modifying monomer used may be one type or multiple types.

[0404] The non-fluoromonomer is not particularly limited and may be a monomer represented by the general formula: ２ =CR Ｑ１ -LR Ｑ２ (In the formula, R Ｑ１ represents a hydrogen atom or an alkyl group. L represents a single bond, -CO-O-*, -O-CO-* or -O-. * represents R Ｑ２ represents the bonding position with Ｑ２ represents a hydrogen atom, an alkyl group or a nitrile group.

[0405] 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.

[0406] 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.

[0407] From the viewpoint of reactivity with TFE, the modified monomer preferably comprises at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether) and (perfluoroalkyl)ethylene.More preferably, it comprises 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.

[0408] In the production of PTFE, additives may be used to stabilize each compound, such as buffers, stabilizing aids, and dispersion stabilizers.

[0409] Preferred stabilizing aids include paraffin wax, fluorine-based oil, fluorine-based solvent, and silicone oil. The stabilizing aids may be used alone or in combination of two or more. Paraffin wax is more preferred as the stabilizing aid. Paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons having 12 or more carbon atoms are preferred. The melting point of the paraffin wax is generally preferably 40 to 65°C, more preferably 50 to 65°C.

[0410] 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 be sufficiently hydrophobic so that it is completely separated from the aqueous PTFE emulsion after TFE polymerization and does not become a contaminating component. In addition, ammonia water, ammonium carbonate, ammonium phosphate, etc. may be added as a buffer to adjust the pH during the reaction.

[0411] Fine powder can be produced by coagulating an aqueous dispersion of PTFE. The aqueous dispersion of PTFE can be used for various applications as a fine powder after coagulation, washing, and drying. When coagulating an aqueous dispersion of PTFE, the aqueous dispersion obtained by polymerization of a polymer latex or the like is typically diluted with water to a polymer concentration of 5 to 20% by mass. In some cases, the pH is adjusted to neutral or alkaline, and the mixture is stirred in a vessel equipped with a stirrer with more vigor than during the reaction. The coagulation may be performed while stirring, using a coagulant such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be performed continuously using an in-line mixer or the like.

[0412] The concentration of unaggregated PTFE in the wastewater resulting from the aggregation is preferably low from the viewpoint of productivity, more preferably less than 0.4 mass %, particularly preferably less than 0.3 mass %.

[0413] According to the production method of the present disclosure, low-molecular-weight PTFE can also be produced as PTFE.

[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 resistant to fibrillation. Therefore, it is suitable as an additive for improving the slipperiness and texture of coating surfaces in the production of plastics, inks, cosmetics, paints, greases, office automation equipment components, toners, etc. (see, for example, JP-A-10-147617).

[0415] When the low-molecular-weight PTFE obtained by the above polymerization is used as a powder, the aqueous dispersion can be coagulated to form powder particles.

[0416] The manufacturing method of the present disclosure can also produce high-molecular-weight PTFE as PTFE. In the present disclosure, high-molecular-weight PTFE means PTFE that is not melt-processable and has fibrillating properties. On the other hand, low-molecular-weight PTFE means PTFE that is melt-processable and does not have fibrillating properties.

[0417] The term "non-melt processable" means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point in accordance with ASTM D 1238 and D 2116.

[0418] The high-molecular-weight PTFE preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D 4895-89. In this disclosure, "high molecular weight" means that the standard specific gravity is within the above range.

[0419] The low-molecular-weight PTFE has a melt viscosity of 1×10 at 380° C. ２ ~7 x 10 ５ In the present disclosure, "low molecular weight" means that the melt viscosity is within the above range. The melt viscosity is measured in accordance with ASTM D 1238 using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, with a 2 g sample preheated at 380°C for 5 minutes, and maintained at the above temperature under a load of 0.7 MPa.

[0420] The melt viscosity of the high molecular weight PTFE is much higher than that of the low molecular weight PTFE, making it difficult to measure its melt viscosity accurately. On the other hand, although the melt viscosity of the low molecular weight PTFE can be measured, it is difficult to obtain a molded product from the low molecular weight PTFE that can be used to measure its standard gravity, making it difficult to measure its accurate standard gravity. Therefore, in this disclosure, standard specific gravity is used as an indicator of the molecular weight of the high molecular weight PTFE, and melt viscosity is used as an indicator of the molecular weight of the low molecular weight PTFE. Note that no measurement method is known that can directly determine the molecular weight of either the high molecular weight PTFE or the low molecular weight PTFE.

[0421] The high-molecular-weight PTFE preferably has a peak temperature of 333 to 347° C., more preferably 335 to 345° C. The low-molecular-weight PTFE preferably has a peak temperature of 322 to 333° C., more preferably 324 to 332° C. The peak temperature can be specified as the temperature corresponding to the maximum value that appears on a differential thermal (DTA) curve obtained by using a TG / DTA (thermogravimetric / differential thermal analyzer) to raise the temperature of PTFE that has not been heated to a temperature of 300° C. or higher at a rate of 10° C. / min.

[0422] The high-molecular-weight PTFE preferably exhibits at least one endothermic peak in the range of 333 to 347°C in a heat of fusion curve when PTFE that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the heat of fusion between 290 and 350°C calculated from the heat of fusion curve is 52mJ / mg or more. The heat of fusion of PTFE is more preferably 55mJ / mg or more, and even more preferably 58mJ / mg or more.

[0423] (TFE / HFP Copolymer) In one embodiment, the manufacturing method of the present disclosure is used to manufacture an aqueous dispersion containing TFE / HFP copolymer (FEP) as the fluoropolymer.

[0424] The monomer composition (mass %) of FEP is preferably TFE:HFP=(60-97):(3-40), more preferably (90-97):(3-10).

[0425] In addition to TFE and HFP, other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, HFP, and other monomers as FEP. Examples of the other monomers include the above-mentioned fluoromonomers (excluding TFE and HFP) and fluorine-free monomers. One or more types of other monomers may be used. Perfluoro(alkyl vinyl ether) is preferred as the other monomer. The content of the other monomer units in FEP may be 0.1 to 2% by mass based on the total monomer units.

[0426] (TFE / perfluoro(alkyl vinyl ether) copolymer) In one embodiment, the manufacturing method of the present disclosure is used to produce an aqueous dispersion containing TFE / perfluoro(alkyl vinyl ether) copolymer (PFA) as the fluoropolymer.

[0427] The preferred monomer composition (mol %) of the TFE / perfluoro(alkyl vinyl ether) copolymer is TFE:perfluoro(alkyl vinyl ether)=(90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoro(alkyl vinyl ether) is preferably a compound represented by the formula: CF ２ =CFORf ４ (wherein, Rf ４ is a perfluoroalkyl group having 1 to 6 carbon atoms).

[0428] In addition to TFE and perfluoro(alkyl vinyl ether), other monomers copolymerizable with these monomers may be polymerized to obtain a copolymer of TFE, perfluoro(alkyl vinyl ether) and other monomers as a TFE / perfluoro(alkyl vinyl ether) copolymer. The other monomers include the above-mentioned fluoromonomers (excluding TFE and perfluoro(alkyl vinyl ether)) and fluorine-free monomers. One or more types of other monomers can be used. The content of other monomer units in the TFE / perfluoro(alkyl vinyl ether) copolymer can be 0.1 to 2 mass% based on the total monomer units.

[0429] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0430] <1> According to a first aspect of the present disclosure, there is provided a method for producing an aqueous fluoropolymer dispersion, which comprises polymerizing a fluoromonomer in the presence of at least one cyclic compound selected from the group consisting of compound (1) represented by formula (1), compound (2) represented by formula (2), and compound (3) represented by formula (3), and an aqueous medium, to produce an aqueous dispersion containing a fluoropolymer. Formula (1): (In the formula, R １１ , R １２ and R １３ each independently represents a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; X １１ and X １２ are independently C or N; ring A is R １１ , R １２ , X １１ and X １２ is a 4- to 18-membered ring formed by linking １１ , R １３ , X １１ and X １２ are linked together to form a 4- to 18-membered ring, wherein ring A and ring B are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring A and ring B is a non-aromatic ring; R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more; Ring A and Ring B are each a group represented by the formula: -R １４ -Z １１ and R forming ring A may have any substituent other than the group represented by １２ and R forming ring B １３ may be bonded to another ring sharing at least one carbon-carbon bond; １１ , R １２ and R １３ Any two of the groups may be linked to each other to form one or more rings.) Formula (2): (In the formula, R ２１is a single bond or a polyvalent linking group having 1 to 20 carbon atoms, and R ２１ is a polyvalent linking group having 1 to 20 carbon atoms, R ２１ may form a ring by bonding any two or more carbon atoms forming three cyclohexane rings; １１ is a hydrophilic group; n is a group of the formula: -R ２１ -Z １１ and is an integer of 1 or more; the three cyclohexane rings are each a group represented by the formula: -R ２１ -Z １１ and the three cyclohexane rings may be bonded to another ring sharing at least one carbon-carbon bond.) Formula (3): (In the formula, R ３１ represents a single bond or a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; R ３２ and R ３３ each independently represents a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; X ３１ and X ３２ are independently C or N; ring C is R ３１ , R ３２ , X ３１ and X ３２ is a 3- to 18-membered ring formed by linking ３１ , R ３３ , X ３１ and X ３２ are linked together to form a 3- to 18-membered ring, and ring C and ring D are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring C and ring D is an aromatic ring; R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; Ring C and Ring D are each a group represented by the formula: -R ３４ -Z １１and R forming ring C may have any substituent other than the group represented by ３２ and R forming ring D ３３ may be bonded to another ring sharing at least one carbon-carbon bond; ３１ , R ３２ and R ３３ Any two of them may be linked to each other to form one or more rings.) <2> According to a second aspect of the present disclosure, there is provided a production method according to the first aspect, in which compound (1) is represented by any one of formula (1-1), formula (1-2), and formula (1-3). Formula (1-1): (In the formula, R １１１ is a hydrocarbon group having 1 or 2 carbon atoms, R １１２ and R １１３ each independently represents a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom; X １１ and X １２ are independently C or N; ring A １ is R １１１ , R １１２ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ is R １１１ , R １１３ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ and ring B １ are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that ring A １ and ring B １ are all non-aromatic rings; R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a ring A １ or ring B １ Formula bonded to: -R １４ -Z １１ represents the number of groups represented by the following formula: and is an integer of 1 or more; １ and ring B １ is -R１４ -Z １１ The group represented by formula (1-2): may have any substituent other than the group represented by formula (1-2): (In the formula, R １１１ , R １１２ , R １１３ , X １１ , X １２ , ring A １ , ring B １ , R １４ , Z １１ and n is as defined above; R １１４ is ring A １ R forming １１２ and any carbon atom of ring B １ R forming １１３ Formula (1-3): (In the formula, R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more; the six rings are each a group represented by the formula: -R １４ -Z １１ <3> According to a third aspect of the present disclosure, there is provided a production method according to the first or second aspect, in which compound (1) is represented by any one of formula (1-1-1), formula (1-1-2), formula (1-1-3), formula (1-1-4), formula (1-1-5), formula (1-2-1), formula (1-2-2), and formula (1-3). Formula (1-1-1): Formula (1-1-2): Formula (1-1-3): Formula (1-1-4): Formula (1-1-5): Formula (1-2-1): Formula (1-2-2): Formula (1-3): (In each formula, R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１is a hydrophilic group. n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more. １４ -Z １１ <4> According to a fourth aspect of the present disclosure, there is provided a production method according to any one of the first to third aspects, in which compound (2) is represented by either formula (2-1) or formula (2-2). Formula (2-1): (In the formula, R ２１１ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group. n is a group of the formula: -R ２１１ -Z １１ and is an integer of 1 or more. The three cyclohexane rings may have any substituent. The cyclopentane ring may have any substituent. ２１１ -Z １１ The group represented by formula (2-2): (In the formula, R ２１２ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group. n is a group of the formula: -R ２１２ -Z １１ and is an integer of 1 or more. The three cyclohexane rings are each a group represented by the formula: -R ２１２ -Z １１ The cyclopentane ring may have any substituent other than the group represented by formula (3-1). The cyclopentane ring may have any substituent.) <5> According to a fifth aspect of the present disclosure, there is provided a production method according to any one of the first to fourth aspects, in which compound (3) is represented by formula (3-1): Formula (3-1): (In the formula, ring D １ is a 3- to 18-membered saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, which may be an aromatic ring or a non-aromatic ring; R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a benzene ring or ring D １Formula bonded to: -R ３４ -Z １１ and is an integer of 1 or more; １ is represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond, and the benzene ring and ring D １ may be bonded to another ring that shares at least one carbon-carbon bond.) <6> According to a sixth aspect of the present disclosure, there is provided a production method according to any one of the first to fifth aspects, in which compound (3) is represented by either formula (3-1-1) or formula (3-1-2). Formula (3-1-1): (In the formula, R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; two benzene rings are each a group represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond.) Formula (3-1-2): (In the formula, R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; the benzene ring and the furan ring are each a group represented by the formula: -R ３４ -Z １１and the group containing an unsaturated double bond.) <7> According to a seventh aspect of the present disclosure, there is provided a production method according to any one of the first to sixth aspects, in which the cyclic compound does not contain a fluorine atom. <8> According to an eighth aspect of the present disclosure, there is provided a production method according to any one of the first to seventh aspects, in which the amount of the cyclic compound is 3 to 5000 ppm by mass relative to the aqueous medium. <9> According to a ninth aspect of the present disclosure, there is further provided a production method according to any one of the first to eighth aspects, in which the fluoromonomer is polymerized in the presence of a fluorine-containing compound (A) represented by general formula (A): General formula (A): CX ｉ X ｋ =CX ｊ R ａ - (CZ １ Z ２ ) ｋ -Y ３ (In the formula, X ｉ , X ｊ and X ｋ are each independently F, Cl, H or CF ３ and Y ３ is a hydrophilic group; R ａ is a linking group; Z １ and Z ２ are each independently H, F or CF ３ and k is 0 or 1. ｉ , X ｋ , X ｊ , R ａ , Z １ and Z ２ At least one of contains F. However, when k is 0, R ａ is a linking group other than a single bond.) <10> According to a tenth aspect of the present disclosure, １１ But, -SO ３ M, -OSO ３ M, -COOM, -P(=O)(OM) ２ , -OP(O)(OM) ２ , -B(OM) ２ Or -OB (OM) ２ M is H, a metal atom, NR ６４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, ６ are independently H or an organic group, and R ６ and any two of the groups may be bonded to each other to form a ring. <11> According to an eleventh aspect of the present disclosure, there is provided a production method according to any one of the first to tenth aspects, wherein the fluoromonomer is at least one selected from the group consisting of vinylidene fluoride and tetrafluoroethylene. <12> According to a twelfth aspect of the present disclosure, there is provided a production method according to any one of the first to eleventh aspects, further comprising polymerizing the fluoromonomer in the presence of a chain transfer agent. <13> According to a thirteenth aspect of the present disclosure, there is provided a production method according to any one of the first to twelfth aspects, wherein the fluoromonomer is polymerized at 10 to 120°C. <14> According to a fourteenth aspect of the present disclosure, there is provided a production method according to any one of the first to thirteenth aspects, wherein the fluoromonomer is polymerized at 0.5 to 10 MPaG. <15> According to a fifteenth aspect of the present disclosure, there is provided a production method according to any one of the first to fourteenth aspects, wherein the fluoropolymer is a fluorine-containing elastomer. <16> According to a sixteenth aspect of the present disclosure, there is provided the production method according to the fifteenth aspect, wherein the Mooney viscosity (ML1+10(100°C)) of the fluorine-containing elastomer is 10 to 130. <17> According to a seventeenth aspect of the present disclosure, there is provided the production method according to the fifteenth or sixteenth aspect, wherein the average particle size of the fluorine-containing elastomer is 500 nm or less. <18> According to an eighteenth aspect of the present disclosure, there is provided the production method according to any of the first to fourteenth aspects, wherein the fluoropolymer is polytetrafluoroethylene. <19> According to a nineteenth aspect of the present disclosure, there is provided the production method according to any of the first to fourteenth aspects, wherein the fluoropolymer is low-molecular-weight polytetrafluoroethylene.

[0431] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0432] The values ​​in the examples were measured by the following methods.

[0433] Solids concentration of aqueous dispersion 1 g of the aqueous dispersion was dried in a blower dryer at 150°C for 180 minutes, the mass of the heating residue was measured, and the ratio (mass%) of the mass of the heating residue to the mass (1 g) of the aqueous dispersion was calculated.

[0434] Polymer Adhesion Rate The ratio of the mass of polymer adhering to the polymerization vessel after the completion of polymerization to the total amount of polymer (fluoroelastomer) after the completion of polymerization (adhesion rate to the polymerization vessel) was calculated using the following formula: Polymer Adhesion Rate (% by mass) = Mass of Polymer Adhering / Mass of Obtained Polymer (including Polymer Adhering) × 100 Mass of Obtained Polymer = Mass of Aqueous Dispersion × Solids Concentration of Aqueous Dispersion (% by mass) / 100 + Mass of Polymer Adhering The polymer adhering includes polymer adhering to the interior of the polymerization vessel, such as the inner wall of the polymerization vessel or the stirring blades, after the aqueous dispersion is extracted from the polymerization vessel after the completion of polymerization, and polymer that has been liberated from the aqueous dispersion by aggregation and is floating or settling without being dispersed in the aqueous dispersion. The mass of the polymer adhering is the mass after the water contained in the polymer adhering is removed by drying at 120°C.

[0435] Average Particle Diameter The average particle diameter (cumulant average diameter) of the fluorine-containing elastomer particles in the aqueous dispersion was measured by dynamic light scattering using an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) and calculated by the cumulant method.

[0436] Number of Particles (Number of Fluorine-Containing Elastomer Particles in Aqueous Dispersion) The number of particles was calculated according to the following formula.

[0437]

[0438] In the formula, the average particle size is the cumulant average size calculated by the above-mentioned method, the number of polymer particles (number of fluoroelastomer particles) is the number per cc of water, and the specific gravities of all the fluoroelastomers in the Examples and Comparative Examples were set to 1.8.

[0439] Mooney Viscosity The Mooney viscosity was measured at 100°C using a Mooney viscometer Premier MV manufactured by ALPHA TECHNOLOGIES in accordance with JIS K 6300-1.2013.

[0440] Copolymer composition was determined by NMR analysis.

[0441] Fluorine-containing elastomer -CH ２ -CH relative to 100 mol% of the structure ２ Amount of I structure of fluorine-containing elastomer １ It was determined by H-NMR spectrum.

[0442] In the examples, the following cyclic compounds were used: A: (-)-camphanic acid B: (±)-10-camphorsulfonic acid C: (S)-(+)-ketopinic acid D: 2,3-norbornanedicarboxylic acid E: 5-norbornene-2,3-dicarboxylic acid F: 2,6-naphthalenedisulfonic acid disodium salt G: 2-naphthalenesulfonic acid sodium salt H: benzofuran-2-carboxylic acid I: cholic acid J: sodium naphthalenesulfonate formalin condensate (Labelin FP, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0443] Comparative Example 1: 1500 g of deionized water, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４3.0 g of a 5% by mass aqueous solution of the above was added, the polymerization vessel was sealed, and the system was purged with nitrogen to remove oxygen. The polymerization vessel was heated to 80°C, and while stirring, monomers (initial monomers) vinylidene fluoride [VDF] / hexafluoropropylene [HFP] (=50 / 50 mol%) were injected to 2.00 MPaG. Next, a polymerization initiator aqueous solution prepared by dissolving 0.072 g of ammonium persulfate (APS) in deionized water was injected with nitrogen gas. Thereafter, the reaction was initiated. As the polymerization progressed, when the internal pressure dropped to 1.995 MPaG, a VDF / HFP (=78 / 22 mol%) mixed monomer was charged so that the internal pressure remained constant at 2.00 MPaG. The charging of the mixed monomer was repeated, and when 10 g of the mixed monomer was added, diiodine compound I (CF ２ ) ４ 2.16 g of 1 was injected using nitrogen gas. Three hours after the start of polymerization, 0.072 g of an aqueous polymerization initiator solution of APS was injected. When 500 g of the mixed monomers had been added, stirring was stopped and the pressure in the polymerization vessel was reduced to atmospheric pressure. The polymerization vessel was cooled, and an aqueous dispersion with a solids concentration of 24.6 mass% was obtained. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 1.

[0444] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 54.7. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 1.

[0445] Example 1 A 3 L SUS polymerization vessel was charged with 1,400 g of deionized water, 100 g of an aqueous solution of 1.5 g of sodium salt of Compound A dissolved in deionized water and adjusted to pH 8 with an aqueous NaOH solution, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４3.0 g of a 5% by mass aqueous solution of the above was added, the polymerization vessel was sealed, and the system was purged with nitrogen to remove oxygen. The polymerization vessel was heated to 80°C, and while stirring, monomers (initial monomers) vinylidene fluoride [VDF] / hexafluoropropylene [HFP] (=50 / 50 mol%) were injected to 2.00 MPaG. Next, a polymerization initiator aqueous solution prepared by dissolving 0.072 g of ammonium persulfate (APS) in deionized water was injected with nitrogen gas. Thereafter, the reaction was initiated. As the polymerization progressed, when the internal pressure dropped to 1.995 MPaG, a VDF / HFP (=78 / 22 mol%) mixed monomer was charged so that the internal pressure remained constant at 2.00 MPaG. The charging of the mixed monomer was repeated, and when 10 g of the mixed monomer was added, diiodine compound I (CF ２ ) ４ 2.16 g of APS was injected using nitrogen gas. Three hours after the start of polymerization, 0.072 g of an aqueous polymerization initiator solution was injected. Thereafter, the aqueous polymerization initiator solution was injected whenever the reaction rate decreased. The total amount of APS added (including the amount added at the start of polymerization) was 0.360 g. When 500 g of the mixed monomers had been added, stirring was stopped and the polymerization tank was depressurized until the pressure reached atmospheric pressure. The polymerization tank was cooled to obtain an aqueous dispersion with a solids concentration of 24.8 mass%. The adhesion rate to the polymerization tank, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 2.

[0446] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 49.4. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 2.

[0447] Example 2 Polymerization was carried out in the same manner as in Example 1, except that compound A was changed to compound B and the total amount of APS added was changed to 0.216 g, to obtain an aqueous dispersion with a solid content concentration of 24.7 mass %. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 2.

[0448] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 51.1. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 2.

[0449] Example 3 Polymerization was carried out in the same manner as in Example 1, except that compound A was changed to compound C and the total amount of APS added was changed to 0.504 g, to obtain an aqueous dispersion with a solid content concentration of 25.4 mass%. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 2.

[0450] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 38.5. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 77 / 23 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 2.

[0451] Example 4 Polymerization was carried out in the same manner as in Example 1, except that compound A was changed to compound D and the total amount of APS added was changed to 1.224 g, to obtain an aqueous dispersion with a solid content concentration of 24.4 mass%. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 2.

[0452] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 28.8. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 2.

[0453] Example 5 Polymerization was carried out in the same manner as in Example 1, except that compound A was changed to compound E and the total amount of APS added was changed to 2.088 g, to obtain an aqueous dispersion having a solids concentration of 24.9 mass%. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 2.

[0454] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 41.1. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 76 / 24 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 2.

[0455] Example 6 Into a 3 L SUS polymerization vessel, 1500 g of deionized water, 1.5 g of compound F, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ 3.0 g of a 5% by mass aqueous solution of the above was added, the polymerization vessel was sealed, and the system was purged with nitrogen to remove oxygen. The polymerization vessel was heated to 80°C, and while stirring, monomers (initial monomers) vinylidene fluoride [VDF] / hexafluoropropylene [HFP] (=50 / 50 mol%) were injected to 2.00 MPaG. Next, a polymerization initiator aqueous solution prepared by dissolving 0.072 g of ammonium persulfate (APS) in deionized water was injected with nitrogen gas. Thereafter, the reaction was initiated. As the polymerization progressed, when the internal pressure dropped to 1.995 MPaG, a VDF / HFP (=78 / 22 mol%) mixed monomer was charged so that the internal pressure remained constant at 2.00 MPaG. The charging of the mixed monomer was repeated, and when 10 g of the mixed monomer was added, diiodine compound I (CF ２ ) ４2.16 g of APS was injected using nitrogen gas. Three hours after the start of polymerization, 0.072 g of an aqueous polymerization initiator solution was injected. Thereafter, the aqueous polymerization initiator solution was injected whenever the reaction rate decreased. The total amount of APS added (including the amount added at the start of polymerization) was 0.576 g. When 500 g of the mixed monomers had been added, stirring was stopped and the pressure in the polymerization tank was reduced to atmospheric pressure. The polymerization tank was cooled to obtain an aqueous dispersion with a solids concentration of 24.4 mass%. The adhesion rate to the polymerization tank, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 3.

[0456] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 51.2. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 79 / 21 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 3.

[0457] Example 7 Polymerization was carried out in the same manner as in Example 6, except that compound F was changed to compound G, the amount of compound G was changed to 0.075 g, and the total amount of APS added was changed to 0.360 g, to obtain an aqueous dispersion with a solids concentration of 25.1 mass %. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 3.

[0458] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 49.4. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 3.

[0459] Example 8 Polymerization was carried out in the same manner as in Example 1, except that the sodium salt of compound A was changed to the sodium salt of compound H, the amount of the sodium salt of compound H was changed to 0.075 g, and the total amount of APS added was changed to 0.540 g, to obtain an aqueous dispersion with a solids concentration of 25.2 mass%. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 3.

[0460] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 52.8. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 3.

[0461] Example 9 Polymerization was carried out in the same manner as in Example 1, except that the sodium salt of compound A was changed to the sodium salt of compound I, the amount of the sodium salt of compound I was changed to 0.075 g, and the total amount of APS added was changed to 0.432 g, to obtain an aqueous dispersion with a solids concentration of 24.6 mass%. The adhesion rate to the polymerization vessel, the mass of the aqueous dispersion, the average particle size, and the number of particles are shown in Table 3.

[0462] An aqueous aluminum sulfate solution was added to the aqueous dispersion to carry out coagulation. The obtained coagulation product was washed with water and dried to obtain a rubbery fluorocopolymer. The Mooney viscosity of the rubbery fluorocopolymer was ML1+10 (100°C) = 54.1. The copolymer composition was examined by NMR analysis to find that VDF / HFP = 78 / 22 (mol%). In addition, -CH ２ -CH relative to 100 mol% of the structure ２ The amount of I structure is shown in Table 3.

[0463]

[0464]

[0465]

[0466] Experimental Examples 1 and 2 The rubbery fluorine-containing copolymers (fluorine-containing elastomers) obtained in Examples 1 and 2 were kneaded according to the formulations shown in Table 4 to obtain fluorine-containing elastomer compositions. For the obtained fluorine-containing elastomer compositions, a crosslinking curve was determined using a rubber vulcanization tester MDRH2030 (manufactured by M&K Co., Ltd.) during the first press crosslinking, and the minimum viscosity (ML), maximum torque level (MH), induction time (T10), and optimum crosslinking time (T90) were determined. In Experimental Example 1, the rubbery fluorine-containing copolymer obtained in Example 1 was used. In Experimental Example 2, the rubbery fluorine-containing copolymer obtained in Example 2 was used. Kneading method: Roll kneading Press crosslinking: 10 minutes at 160°C Oven crosslinking: 4 hours at 180°C

[0467] The materials shown in Table 4 are as follows: MT carbon: Thermax N-990 manufactured by Cancarb. Ltd. TAIC: triallyl isocyanurate, manufactured by Taiku Shinryo Corporation Perhexa 25B: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, manufactured by NOF Corporation

[0468] Physical Properties in Ordinary State The 100% modulus (M100), tensile strength at break (TB), and elongation at break (EB) in ordinary state of a crosslinked molded sheet (a test piece in the shape of a No. 6 dumbbell) prepared in accordance with JIS K6251 were measured.

[0469] Hardness According to JIS K6253, the hardness (Shore A) of the crosslinked molded product (test piece in the shape of a No. 6 dumbbell) was measured (peak value, 1 sec, 3 sec).

[0470] Compression Set: The compression set of a P-24O ring prepared in accordance with JIS K6262 was measured at 200° C. for 72 hours under 25% compression.

[0471]

[0472] pH Value The pH value was measured at 25°C using a HORIBA pH / ION METER F-72.

[0473] Solids concentration in PTFE aqueous dispersion 1 g of the aqueous dispersion was dried in a blower dryer at 150°C for 60 minutes, and the ratio of the mass of the heating residue to the mass (1 g) of the aqueous dispersion was expressed as a percentage and used as the solids concentration.

[0474] Number of Particles (Number of PTFE-Containing Particles in Aqueous Dispersion) The number of particles was calculated using the following formula.

[0475]

[0476] In the formula, the average particle size is the average primary particle size of PTFE calculated by the following method, the number of polymer particles (number of PTFE particles) is the number per cc of water, and the specific gravity of all PTFE in the examples was 2.28.

[0477] Average primary particle diameter of PTFE The aqueous dispersion is diluted with water until the solid content becomes 0.15% by mass, and the transmittance of 550 nm projected light per unit length of the diluted latex obtained and the number-based length average primary particle diameter determined by measuring the unidirectional diameter on a transmission electron microscope photograph are measured, and a calibration curve is prepared. Using this calibration curve, the average primary particle diameter is determined from the measured transmittance of 550 nm projected light of each sample.

[0478] Specific surface area of ​​PTFE was measured by the BET method using a surface analyzer (trade name: MONOSORB, manufactured by QUANTA CHLROME). A mixed gas of 30% nitrogen and 70% helium was used as the carrier gas, and liquid nitrogen was used for cooling.

[0479] Melt Viscosity of PTFE According to ASTM D 1238, a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die were used to measure a 2g sample that had been preheated at 380°C for 5 minutes under a load of 0.7 MPa while maintaining the temperature.

[0480] Standard Specific Gravity (SSG) of PTFE: Measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D 4895-89.

[0481] Example 10: 3.2 L of deionized water, 1.65 g of Compound A, and 2.8% aqueous ammonia were added to a 6 L stainless steel reactor equipped with a stirrer, and the pH was adjusted to 8.7. The reactor was sealed, and while heated to 70 ° C, the reactor was evacuated and simultaneously purged with TFE to remove oxygen from the reactor, and the contents were stirred. 0.07 g of propane was injected into the reactor with TFE until the pressure reached 0.78 MPaG. After feeding TFE up to 0.78 MPaG, 1.65 g of APS was charged as a polymerization initiator. Thereafter, TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When 660 g of TFE had been charged, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented to normal pressure, and the contents were removed from the reactor and cooled to obtain an aqueous PTFE dispersion. The particles contained in the obtained PTFE aqueous dispersion had an average primary particle diameter of 210 nm and a particle number of 1.8 × 10 １３ The solid content of the resulting PTFE aqueous dispersion was 17.0% by mass. No polymer adhesion to the polymerization vessel or floating powder in the aqueous dispersion was observed. The resulting PTFE aqueous dispersion was stirred at high speed to coagulate, and the wet polymer and water were separated. The resulting wet polymer was dried at 150°C for 18 hours. The resulting PTFE powder had a specific surface area of ​​11 m ２ The melt viscosity was 184,000 Pa·S, and it was found to be low molecular weight PTFE.

[0482] Example 11: 510 g of deionized water, 30 g of paraffin wax, 0.275 g of Compound A, and 2.8% aqueous ammonia were added to a 1 L glass autoclave, and the pH was adjusted to 8.7. The reactor was sealed and heated to 70°C while evacuating and simultaneously purging with TFE to remove oxygen from the reactor, and the contents were stirred. After feeding TFE up to 0.78 MPaG, 0.275 g of APS was added as a polymerization initiator. Thereafter, TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When 27.5 g of TFE had been charged, 0.275 g of Compound A and 1.14 g of 2.8% aqueous ammonia were added. When 82.5 g of TFE had been added, 0.275 g of Compound A and 1.14 g of 2.8% aqueous ammonia were added. When 110.0 g of TFE was charged, 0.0055 g of hydroquinone was added. When 138 g of TFE was charged, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented to normal pressure, and the contents were removed from the reactor and cooled to obtain a PTFE aqueous dispersion. The average primary particle diameter of the particles contained in the obtained PTFE aqueous dispersion was 210 nm, and the number of particles was 2.4 × 10 １３ The solids content of the resulting PTFE aqueous dispersion was 21.1% by mass. No polymer adhesion to the polymerization vessel was observed. Water was added to the resulting PTFE aqueous dispersion to dilute the solids concentration to 15% by mass, and the mixture was stirred at high speed to coagulate, separating the wet polymer from the water. The resulting wet polymer was dried at 150°C for 18 hours. The resulting PTFE powder did not melt at 380°C, and the SSG was 2.260. This indicated that the resulting PTFE was high-molecular-weight PTFE.

[0483] Example 12 Polymerization was carried out in the same manner as in Example 10, except that compound A was changed to compound C, to obtain an aqueous PTFE dispersion. The average primary particle diameter of the particles contained in the obtained aqueous PTFE dispersion was 217 nm, and the number of particles was 1.7 × 10 １３The solid content of the resulting PTFE aqueous dispersion was 16.8% by mass. No polymer adhesion to the polymerization vessel or floating powder in the aqueous dispersion was observed. The resulting PTFE aqueous dispersion was stirred at high speed to coagulate, and the wet polymer and water were separated. The resulting wet polymer was dried at 150°C for 18 hours. The resulting PTFE powder had a specific surface area of ​​11 m ２ The melt viscosity was 167,000 Pa·S, and it was found to be low molecular weight PTFE.

[0484] Example 13: Polymerization was carried out in the same manner as in Example 10, except that compound A was changed to compound J, the amount added was changed to a total of 3.30 g in divided additions, and the amount added of APS was changed to a total of 2.64 g in divided additions, to obtain a PTFE aqueous dispersion. The average primary particle diameter of the particles contained in the obtained PTFE aqueous dispersion was 193 nm, and the number of particles was 1.6 × 10 １３ The solid content of the resulting PTFE aqueous dispersion was 12.1% by mass. No polymer adhesion to the polymerization vessel or floating powder in the aqueous dispersion was observed. The resulting PTFE aqueous dispersion was stirred at high speed to coagulate, and the wet polymer and water were separated. The resulting wet polymer was dried at 150°C for 18 hours. The resulting PTFE powder had a specific surface area of ​​13.2 m ２ The melt viscosity was 57,000 Pa·S, and it was found to be low molecular weight PTFE.

Claims

1. A method for producing an aqueous fluoropolymer dispersion, comprising polymerizing a fluoromonomer in the presence of at least one cyclic compound selected from the group consisting of a compound (1) represented by formula (1), a compound (2) represented by formula (2), and a compound (3) represented by formula (3), and an aqueous medium, to produce an aqueous dispersion containing a fluoropolymer. Formula (1): (In the formula, R １１ , R １２ and R １３ each independently represents a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; X １１ and X １２ are independently C or N; ring A is R １１ , R １２ , X １１ and X １２ is a 4- to 18-membered ring formed by linking １１ , R １３ , X １１ and X １２ are linked together to form a 4- to 18-membered ring, wherein ring A and ring B are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring A and ring B is a non-aromatic ring; R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more; Ring A and Ring B are each a group represented by the formula: -R １４ -Z １１ and R forming ring A may have any substituent other than the group represented by １２ and R forming ring B １３ may be bonded to another ring sharing at least one carbon-carbon bond; １１ , R １２ and R １３ Any two of the groups may be linked to each other to form one or more rings.) Formula (2): (In the formula, R ２１ is a single bond or a polyvalent linking group having 1 to 20 carbon atoms, and R ２１ is a polyvalent linking group having 1 to 20 carbon atoms, R ２１ may form a ring by bonding any two or more carbon atoms forming three cyclohexane rings; １１ is a hydrophilic group; n is a group of the formula: -R ２１ -Z １１ and is an integer of 1 or more; the three cyclohexane rings are each a group represented by the formula: -R ２１ -Z １１ and the three cyclohexane rings may be bonded to another ring sharing at least one carbon-carbon bond.) Formula (3): (In the formula, R ３１ represents a single bond or a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; R ３２ and R ３３ each independently represents a polyvalent linking group having 1 to 8 atoms which may contain a heteroatom; X ３１ and X ３２ are independently C or N; ring C is R ３１ , R ３２ , X ３１ and X ３２ is a 3- to 18-membered ring formed by linking ３１ , R ３３ , X ３１ and X ３２ are linked together to form a 3- to 18-membered ring, and ring C and ring D are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that at least one of ring C and ring D is an aromatic ring; R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; Ring C and Ring D are each a group represented by the formula: -R ３４ -Z １１ and R forming ring C may have any substituent other than the group represented by ３２ and R forming ring D ３３ may be bonded to another ring sharing at least one carbon-carbon bond; ３１ , R ３２ and R ３３ Any two of may be linked to each other to form one or more rings.) 2. The method according to claim 1, wherein compound (1) is represented by any one of formulas (1-1), (1-2), and (1-3). Formula (1-1): (In the formula, R １１１ is a hydrocarbon group having 1 or 2 carbon atoms, R １１２ and R １１３ each independently represents a saturated or unsaturated hydrocarbon group having 2 to 8 carbon atoms or a saturated or unsaturated hydrocarbon group having 1 to 7 carbon atoms and containing an ether oxygen atom; X １１ and X １２ are independently C or N; ring A １ is R １１１ , R １１２ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ is R １１１ , R １１３ , X １１ and X １２ is a 5- to 12-membered ring formed by linking １ and ring B １ are independently a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, provided that ring A １ and ring B １ are all non-aromatic rings; R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a ring A １ or ring B １ Formula bonded to: -R １４ -Z １１ represents the number of groups represented by the following formula: and is an integer of 1 or more; １ and ring B １ is -R １４ -Z １１ The group represented by formula (1-2): may have any substituent other than the group represented by formula (1-2): (In the formula, R １１１ , R １１２ , R １１３ , X １１ , X １２ , ring A １ , ring B １ , R １４ , Z １１ and n is as defined above; R １１４ is ring A １ R forming １１２ and any carbon atom of ring B １ R forming １１３ Formula (1-3): (In the formula, R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more; the six rings are each a group represented by the formula: -R １４ -Z １１ may have any substituent other than the group represented by 3. The method according to claim 1 or 2, wherein compound (1) is represented by any one of formulas (1-1-1), (1-1-2), (1-1-3), (1-1-4), (1-1-5), (1-2-1), (1-2-2) and (1-3). Formula (1-1-1): Formula (1-1-2): Formula (1-1-3): Formula (1-1-4): Formula (1-1-5): Formula (1-2-1): Formula (1-2-2): Formula (1-3): (In each formula, R １４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group. n is a group of the formula: -R １４ -Z １１ and is an integer of 1 or more. １４ -Z １１ may have any substituent other than the group represented by 4. The method according to any one of claims 1 to 3, wherein compound (2) is represented by either formula (2-1) or formula (2-2). Formula (2-1): (In the formula, R ２１１ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group. n is a group of the formula: -R ２１１ -Z １１ and is an integer of 1 or more. The three cyclohexane rings may have any substituent. The cyclopentane ring may have any substituent. ２１１ -Z １１ The group represented by formula (2-2): (In the formula, R ２１２ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group. n is a group of the formula: -R ２１２ -Z １１ and is an integer of 1 or more. The three cyclohexane rings are each a group represented by the formula: -R ２１２ -Z １１ The cyclopentane ring may have any substituent other than the group represented by the formula:

5. The method according to any one of claims 1 to 4, wherein the compound (3) is represented by formula (3-1): Formula (3-1): (In the formula, ring D １ is a 3- to 18-membered saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring, which may be an aromatic ring or a non-aromatic ring; R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a benzene ring or ring D １ Formula bonded to: -R ３４ -Z １１ and is an integer of 1 or more; １ is represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond, and the benzene ring and ring D １ may be bonded to another ring that shares at least one carbon-carbon bond.) 6. The method according to any one of claims 1 to 5, wherein compound (3) is represented by either formula (3-1-1) or formula (3-1-2). Formula (3-1-1): (In the formula, R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; two benzene rings are each a group represented by the formula: -R ３４ -Z １１ and a group containing an unsaturated double bond.) Formula (3-1-2): (In the formula, R ３４ is a single bond or a divalent linking group having 1 to 20 carbon atoms; Z １１ is a hydrophilic group, and n is a group of the formula: -R ３４ -Z １１ and is an integer of 1 or more; the benzene ring and the furan ring are each a group represented by the formula: -R ３４ -Z １１ and the group containing an unsaturated double bond.) 7. The method according to any one of claims 1 to 6, wherein the cyclic compound does not contain a fluorine atom.

8. The production method according to any one of claims 1 to 7, wherein the amount of the cyclic compound is 3 to 5,000 ppm by mass relative to the aqueous medium.

9. The method according to any one of claims 1 to 8, further comprising polymerizing the fluoromonomer in the presence of a fluorine-containing compound (A) represented by general formula (A): CX ｉ X ｋ =CX ｊ R ａ - (CZ １ Z ２ ) ｋ -Y ３ (In the formula, X ｉ , X ｊ and X ｋ are each independently F, Cl, H or CF ３ and Y ３ is a hydrophilic group; R ａ is a linking group; Z １ and Z ２ are each independently H, F or CF ３ and k is 0 or 1. ｉ , X ｋ , X ｊ , R ａ , Z １ and Z ２ At least one of contains F. However, when k is 0, R ａ is a linking group other than a single bond.

10. Z １１ But, -SO ３ M, -OSO ３ M, -COOM, -P(=O)(OM) ２ , -OP(O)(OM) ２ , -B(OM) ２ Or -OB (OM) ２ M is H, a metal atom, NR ６ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, ６ are independently H or an organic group, and R ６ The method according to any one of claims 1 to 9, wherein any two of the following may be bonded to each other to form a ring.

11. The method according to any one of claims 1 to 10, wherein the fluoromonomer is at least one selected from the group consisting of vinylidene fluoride and tetrafluoroethylene.

12. The method according to any one of claims 1 to 11, wherein the fluoromonomer is polymerized in the presence of a chain transfer agent.

13. The method according to any one of claims 1 to 12, wherein the fluoromonomer is polymerized at 10 to 120°C.

14. The method according to any one of claims 1 to 13, wherein the fluoromonomer is polymerized at 0.5 to 10 MPaG.

15. The method according to any one of claims 1 to 14, wherein the fluoropolymer is a fluorine-containing elastomer.

16. The method according to claim 15, wherein the Mooney viscosity (ML1+10 (100°C)) of the fluorine-containing elastomer is 10 to 130.

17. The method according to claim 15 or 16, wherein the average particle size of the fluorine-containing elastomer is 500 nm or less.

18. The method according to any one of claims 1 to 14, wherein the fluoropolymer is polytetrafluoroethylene.

19. The method of any one of claims 1 to 14, wherein the fluoropolymer is low molecular weight polytetrafluoroethylene.

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