Method for producing non-melt-processable polytetrafluoroethylene powder and non-melt-processable polytetrafluoroethylene powder

Abstract

Provided is a method for producing a non-melt-processable polytetrafluoroethylene powder, the method comprising: polymerizing tetrafluoroethylene in the presence of an aqueous medium and a hydrocarbon-based surfactant to obtain an aqueous dispersion containing non-melt-processable polytetrafluoroethylene; coagulating the non-melt-processable polytetrafluoroethylene in the aqueous dispersion to obtain a wet powder; washing the wet powder; and heat-treating the wet powder to obtain a non-melt-processable polytetrafluoroethylene powder.

Description

Method for producing non-melt-processable polytetrafluoroethylene powder and non-melt-processable polytetrafluoroethylene powder

[0001] The present disclosure relates to a method for producing non-melt-processible polytetrafluoroethylene powder and to melt-processible polytetrafluoroethylene.

[0002] Patent Document 1 describes a method for producing a fluoropolymer powder, which comprises the steps of: adding an acid to an aqueous fluoropolymer dispersion obtained by polymerization using a carboxylic acid-type hydrocarbon surfactant, adjusting the pH to 4.0 or less, and coagulating the resulting fluoropolymer to obtain a wet fluoropolymer powder containing a fluorine-containing compound represented by the following general formula (1A): (A1); and heat-treating the wet fluoropolymer powder at a temperature higher than 150°C and lower than 240°C: ２ ) ｍ —COOH (wherein m is 3 to 19)

[0003] International Publication No. 2020 / 213691

[0004] An object of the present disclosure is to provide a method for producing non-melt-processible polytetrafluoroethylene powder.

[0005] According to the present disclosure, there is provided a method for producing non-melt-processible polytetrafluoroethylene powder, which comprises polymerizing tetrafluoroethylene in the presence of an aqueous medium and a hydrocarbon surfactant to obtain an aqueous dispersion containing non-melt-processible polytetrafluoroethylene, coagulating the non-melt-processible polytetrafluoroethylene in the aqueous dispersion to obtain a wet powder, washing the wet powder, and heat-treating the wet powder to obtain the non-melt-processible polytetrafluoroethylene powder.

[0006] According to the present disclosure, a method for producing non-melt-processible polytetrafluoroethylene powder 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, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer having a content of tetrafluoroethylene units relative to all polymer units of 99 mol % or more.

[0009] 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.

[0010] 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.

[0011] 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.).

[0012] 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.).

[0013] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0014] Patent Document 1 describes that by using the above-mentioned production method, a fluoropolymer powder having a reduced content of a specific fluorine-containing compound can be produced.

[0015] However, when non-melt-processible polytetrafluoroethylene powder is produced as a fluoropolymer powder by the above-mentioned production method and the resulting powder is molded by paste extrusion, problems have become apparent, such as the need for high extrusion pressure, the extrusion pressure increasing without reaching equilibrium during a single extrusion molding, and the extrusion pressure increasing with each repetition of extrusion molding. High extrusion pressure or unstable extrusion pressure significantly reduces the productivity of molded products and reduces the uniformity of the physical properties of the resulting molded products.

[0016] The production method of the present disclosure is a production method that can produce non-melt-processible polytetrafluoroethylene that has a reduced content of fluorine-containing compounds having hydrophilic groups and can be extruded at low and stable extrusion pressures. The production method and the composition of the melt-processible polytetrafluoroethylene of the present disclosure are described in detail below.

[0017] 1. Manufacturing Method In the manufacturing method of the present disclosure, tetrafluoroethylene (TFE) is polymerized in the presence of an aqueous medium and a hydrocarbon surfactant to obtain an aqueous dispersion containing non-melt-processible polytetrafluoroethylene (PTFE), the non-melt-processible PTFE in the aqueous dispersion is coagulated to obtain a wet powder, the wet powder is washed, and the wet powder is heat-treated to obtain a non-melt-processible PTFE powder.

[0018] (Hydrocarbon-based surfactant) The hydrocarbon-based emulsifier is a non-fluorine-containing hydrocarbon-based emulsifier. Examples of hydrocarbon-based surfactants that can be used include those described in JP-A Nos. 2013-542308, 2013-542309, and 2013-542310.

[0019] The hydrocarbon surfactants may be surfactants having a hydrophilic portion and a hydrophobic portion on the same molecule, and may be cationic, nonionic, or anionic.

[0020] Cationic hydrocarbon surfactants typically have a positively charged hydrophilic portion, such as an alkylated ammonium halide, such as an alkylated ammonium bromide, and a hydrophobic portion, such as a long-chain fatty acid.

[0021] Anionic hydrocarbon surfactants typically have a hydrophilic portion, such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion, which is a long chain hydrocarbon moiety, such as an alkyl.

[0022] Nonionic hydrocarbon surfactants typically contain no charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains a water-soluble functional group, such as an ethylene ether chain derived from polymerization with ethylene oxide.

[0023] Examples of nonionic hydrocarbon surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, glycerol esters, and derivatives thereof.

[0024] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0025] Specific examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0026] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0027] Specific examples of sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0028] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0029] Specific examples of glycerol esters include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[0030] Specific examples of the above derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0031] The ethers and esters may have an HLB value of 10-18.

[0032] Examples of nonionic hydrocarbon surfactants include the Triton (registered trademark) X series (X15, X45, X100, etc.), Tergitol (registered trademark) 15-S series, Tergitol (registered trademark) TMN series (TMN-6, TMN-10, TMN-100, etc.), and Tergitol (registered trademark) L series, all manufactured by The Dow Chemical Company; and the Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m to 22, n to 23) and Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF.

[0033] Examples of anionic hydrocarbon surfactants include Versatic (registered trademark) 10 from Resolution Performance Products and Avanel S series (S-70, S-74, etc.) manufactured by BASF.

[0034] Examples of anionic hydrocarbon surfactants include R Ｚ -(L-M) ｘ (In the formula, R Ｚ is a hydrophobic hydrocarbon moiety containing one or more carbon atoms. L, which may be the same or different in each occurrence, represents an ionic hydrophilic moiety, and M, which may be the same or different in each occurrence, represents one or more counterions of the ionic hydrophilic moiety. x is aｚ R represents the number of groups represented by -LM bonded to the group, and is an integer of 1 to 3. Ｚ As L, a hydrocarbon group having 1 to 100 carbon atoms which may contain a heteroatom is preferred. The heteroatom may be inserted between carbon atoms or may be contained in a substituent bonded to a carbon atom. As L, -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － is preferred. ３ － is an arylsulfonate. M is H, a metal atom, NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium is preferred. ５Ｚ is preferably H or an organic group (preferably an alkyl group having 1 to 3 carbon atoms). More specifically, the anionic surfactants described below can be mentioned.

[0035] The hydrocarbon surfactants include R Ｚ -LM (wherein, R Ｚ is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or may form a ring. ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５Ｚis H or an organic group, -ArSO ３ － is an aryl sulfonate. Specific examples of anionic surfactants include CH ３ - (CH ２ ) ｎ -LM (wherein n is an integer of 6 to 17, and L and M are the same as above). Ｚ is preferably an alkyl group having 3 to 18 carbon atoms. Ｚ Mixtures where L is an alkyl group having 12 to 16 carbon atoms and L-M is sulfate can also be used.

[0036] Other compounds having surface activity include R ６Ｚ (-L-M) ２ (In the formula, R ６Ｚ is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５Ｚ is H or an organic group, -ArSO ３ － is an aryl sulfonate.

[0037] The hydrocarbon surfactants include R ７Ｚ (-L-M) ３ (In the formula, R ７Ｚis a linear or branched alkylidyne group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５Ｚ is H or an organic group. ３ － is an aryl sulfonate. ５ｚ is preferably H or an alkyl group, more preferably H or an alkyl group having 1 to 10 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms.

[0038] In this disclosure, unless otherwise specified, the term "substituent" refers to a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamido group, an aromatic sulfonamido group, a heterocyclic sulfonamido group, an amino group, an aliphatic amino group, an and hydroxy groups, cyano groups, sulfo groups, carboxy groups, aliphatic oxyamino groups, aromatic oxyamino groups, carbamoylamino groups, sulfamoylamino groups, halogen atoms, sulfamoylcarbamoyl groups, carbamoylsulfamoyl groups, dialiphatic oxyphosphinyl groups, and diaromatic oxyphosphinyl groups.

[0039] The hydrocarbon surfactant also includes a siloxane hydrocarbon surfactant. Examples of the siloxane hydrocarbon surfactant include those described in Silicone Surfactants, R. M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of the siloxane hydrocarbon surfactant includes a distinct hydrophobic portion and a hydrophilic portion. The hydrophobic portion includes one or more dihydrocarbylsiloxane units, where the substituents on the silicone atoms are entirely hydrocarbons. These siloxane hydrocarbon surfactants can also be considered hydrocarbon surfactants in the sense that the carbon atoms of the hydrocarbyl groups are entirely substituted with hydrogen atoms, although they may be substituted with halogens such as fluorine, i.e., the monovalent substituents on the carbon atoms of the hydrocarbyl groups are hydrogen.

[0040] The hydrophilic portion of the siloxane hydrocarbon surfactant may contain one or more polar moieties containing ionic groups such as sulfates, sulfonates, phosphonates, phosphate esters, carboxylates, carbonates, sulfosuccinates, taurates (as free acids, salts, or esters), phosphine oxides, betaines, betaine copolyols, and quaternary ammonium salts. The ionic hydrophobic portion may also contain ionically functionalized siloxane grafts. Examples of such siloxane hydrocarbon surfactants include polydimethylsiloxane-grafted (meth)acrylates, polydimethylsiloxane-grafted polyacrylate salts, and polydimethylsiloxane-grafted quaternary amines. The polar portion of the hydrophilic portion of the siloxane hydrocarbon surfactant may contain nonionic groups formed by polyethers such as polyethylene oxide (PEO) and mixed polyethylene oxide / propylene oxide polyethers (PEO / PPO); monosaccharides and disaccharides; and water-soluble heterocycles such as pyrrolidinone. The ratio of ethylene oxide to propylene oxide (EO / PO) can be varied in mixed polyethylene oxide / propylene oxide polyethers.

[0041] The hydrophilic portion of the siloxane hydrocarbon surfactant may also contain a combination of ionic and nonionic moieties. Such moieties include, for example, ionically end-functionalized or randomly functionalized polyethers or polyols. Preferred for the practice of the present disclosure are siloxanes with nonionic moieties, i.e., nonionic siloxane surfactants.

[0042] The arrangement of hydrophobic and hydrophilic moieties in the structure of the siloxane hydrocarbon surfactant may take the form of a diblock polymer (AB), a triblock polymer (ABA) (where "B" represents the siloxane portion of the molecule), or a multiblock polymer. Alternatively, the siloxane surfactant may comprise a graft polymer.

[0043] Siloxane hydrocarbon surfactants are also disclosed in US Pat. No. 6,841,616.

[0044] Siloxane-based anionic hydrocarbon surfactants include SilSense®, available from Noveon® Consumer Specialties of Lubrizol Advanced Materials, Inc. ＴＭ PE-100 silicone, SilSense ＴＭ CA-1 silicone and the like.

[0045] Examples of anionic hydrocarbon surfactants include the sulfosuccinate surfactant Lankropol® K8300 from Akzo Nobel Surface Chemistry LLC. Examples of sulfosuccinate surfactants include diisodecyl sulfosuccinate sodium salt (Emulsogen® SB10 from Clariant) and diisotridecyl sulfosuccinate sodium salt (Polirol® TR / LNA from Cesapinia Chemicals).

[0046] The hydrocarbon surfactant may be PolyFox (registered trademark) surfactant from Omnova Solutions, Inc. ＴＭ PF-156A, PolyFox ＴＭ PF-136A, etc.)

[0047] The hydrocarbon surfactant is preferably an anionic hydrocarbon surfactant. The anionic hydrocarbon surfactants described above can be used, but for example, the following anionic hydrocarbon surfactants can be suitably used.

[0048] Examples of the anionic hydrocarbon surfactant include those represented by the following formula (α): １００ -COOM (α) (wherein, R １００ is a monovalent organic group containing one or more carbon atoms. M is H, a metal atom, NR １０１ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １０１R is H or an organic group, and may be the same or different. １０１ The organic group in R is preferably an alkyl group. １０１ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. １００ The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. １００ The number of carbon atoms in is preferably 29 or less, more preferably 23 or less. The metal atom of M includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M is H, a metal atom, or NR １０１ ４ is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR １０１ 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, Na or NH ４ is particularly preferred, and NH ４ is most preferred.

[0049] The compound (α) may be R １０２ -COOM (in the formula, R １０２ is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above. ) are also included. Specifically, CH ３ - (CH ２ ) ｎ -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0050] From the viewpoint of emulsion stability, the compound (α) may not contain a carbonyl group (excluding the carbonyl group in the carboxyl group). Examples of the hydrocarbon-containing surfactant not containing a carbonyl group include those represented by the following formula (A): １０３ -COO-M (A) (wherein, R １０３ is an alkyl group, an alkenyl group, an alkylene group, or an alkenylene group, which may contain an ether bond; M is H, a metal atom, NR １０１ ４ , an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. １０１ are the same or different and are H or an organic group. １０３ is preferably an alkyl group or an alkenyl group (which may contain an ether group). １０３ The alkyl group or alkenyl group in the above R may be linear or branched. １０３ The number of carbon atoms is not limited, but is, for example, 2 to 29.

[0051] When the alkyl group is linear, R １０３ The number of carbon atoms in R is preferably 3 to 29, and more preferably 5 to 23. When the alkyl group is branched, R １０３ The number of carbon atoms in R is preferably 5 to 35, and more preferably 11 to 23. When the alkenyl group is linear, R １０３ The number of carbon atoms in R is preferably 2 to 29, and more preferably 9 to 23. When the alkenyl group is branched, R １０３ The number of carbon atoms is preferably 4 to 29, and more preferably 9 to 23.

[0052] Examples of the alkyl group and alkenyl group include a methyl group, an ethyl group, an isobutyl group, a t-butyl group, and a vinyl group.

[0053] Examples of the compound (α) (carboxylic acid type hydrocarbon surfactant) include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15)-linolenic acid, (6,9,12)linolenic acid, eleostearic acid, arachidic acid, 8,11-eicosadienoic acid, mead acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, melissic acid, croton Examples of suitable salts include hydroxybenzoates, ... １０１ ４ Examples of the surfactant (α) (carboxylic acid type hydrocarbon surfactant) include, but are not limited to, imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. As the surfactant (α) (carboxylic acid type hydrocarbon surfactant), at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof is preferred, since particles having a small average primary particle size can be obtained by polymerization, and a large number of particles can be generated during polymerization, allowing PTFE to be produced efficiently, and lauric acid and its salts are more preferred, salts of lauric acid are particularly preferred, and sodium laurate and ammonium laurate are most preferred.

[0054] The hydrocarbon surfactant may be a surfactant represented by the general formula (1): (In the formula, R １ ~R ５ represents H or a monovalent substituent, provided that R １ and R ３ At least one of the groups represented by the general formula: -Y-R ６ a group represented by R ２ and R ５ At least one of the groups is a group represented by the general formula: -X-A or a group represented by the general formula: -Y-R ６ In addition, X, which may be the same or different in each occurrence, represents a divalent linking group or a bond; A, which may be the same or different in each occurrence, represents -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 is H or an organic group); Y is the same or different in each occurrence and is —S(═O) ２ -, -O-, -COO-, -OCO-, -CONR ８ - and -NR ８ a divalent linking group selected from the group consisting of CO—, or a bond, R ８ is H or an organic group; R ６ R may be the same or different in each occurrence and represents an alkyl group having one or more carbon atoms which may contain at least one group selected from the group consisting of a carbonyl group, an ester group, an amide group and a sulfonyl group between carbon atoms; １ ~R ５ Any two of these may be bonded to each other to form a ring (hereinafter also referred to as surfactant (1)).

[0055] The surfactant (1) will be explained.

[0056] In the formula, R １ ~R ５ represents H or a monovalent substituent, provided that R １ and R ３At least one of the groups represented by the general formula: -Y-R ６ a group represented by R ２ and R ５ At least one of the groups is a group represented by the general formula: -X-A or a group represented by the general formula: -Y-R ６ R represents a group represented by the formula: １ ~R ５ Any two of these may be bonded to each other to form a ring.

[0057] R １ The substituent that the alkyl group as the group may have is preferably a halogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, or a hydroxy group, and particularly preferably a methyl group or an ethyl group.

[0058] R １ The alkyl group as the alkyl group preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group preferably does not have any substituents.

[0059] R １ As the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent or a cyclic alkyl group having 3 to 10 carbon atoms which may have a substituent is preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not contain a carbonyl group or a cyclic alkyl group having 3 to 10 carbon atoms which does not contain a carbonyl group is more preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not have a substituent is even more preferred, a linear or branched alkyl group having 1 to 3 carbon atoms which does not have a substituent is even more preferred, and a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is particularly preferred, and a methyl group (—CH ３ ) is most preferred.

[0060] The monovalent substituent is a group represented by the general formula: -Y-R ６ a group represented by the general formula: -X-A, -H, optionally substituted C １－２０ an alkyl group of —NH ２ , -NHR ９ (R ９ is an organic group), —OH, —COOR ９ (R ９ is an organic group) or -OR ９ (R ９ The alkyl group preferably has 1 to 10 carbon atoms.

[0061] R ９ As for C １－１０ or an alkyl group of C １－１０ The alkylcarbonyl group represented by the formula C is preferred. １－４ or an alkyl group of C １－４ An alkylcarbonyl group of the formula is more preferred.

[0062] In the formula, X may be the same or different in each occurrence and represents a divalent linking group or a bond. ６ does not contain any of a carbonyl group, an ester group, an amide group, and a sulfonyl group, X is preferably a divalent linking group containing at least one group selected from the group consisting of a carbonyl group, an ester group, an amide group, and a sulfonyl group.

[0063] X is -CO-, -S(=O) ２ -, -O-, -COO-, -OCO-, -S (=O) ２ -O-, -O-S (=O) ２ --, --CONR ８ - and -NR ８ a divalent linking group containing at least one bond selected from the group consisting of CO—, C １－１０ An alkylene group or a bond represented by the formula R ８ represents H or an organic group.

[0064] R ８ The organic group in R is preferably an alkyl group. ８ 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 even more preferred is H.

[0065] In the formula, A is the same or different in each occurrence and 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 is H or an organic group. ７ may be the same or different. In general formula (1), A is preferably -COOM.

[0066] 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 More preferred are alkyl groups of the following formula: Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred.

[0067] M is H, a metal atom, or NR ７ ４ is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR ７ ４ is more preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is even more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred.

[0068] wherein Y in each occurrence is the same or different and is —S(═O) ２ -, -O-, -COO-, -OCO-, -CONR ８ - and -NR ８ a divalent linking group selected from the group consisting of CO—, or a bond, R ８ represents H or an organic group.

[0069] Y is a bond, —O—, —COO—, —OCO—, or —CONR ８ - and -NR ８ A divalent linking group selected from the group consisting of -CO- is preferred, and a divalent linking group selected from the group consisting of a bond, -COO-, and -OCO- is more preferred.

[0070] R ８ The organic group in R is preferably an alkyl group. ８ 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 even more preferred is H.

[0071] In the formula, R ６ In each occurrence, R may be the same or different and represent an alkyl group having one or more carbon atoms which may contain at least one group selected from the group consisting of a carbonyl group, an ester group, an amide group and a sulfonyl group between carbon atoms. ６ The number of carbon atoms in the organic group is preferably 2 or more and 20 or less, more preferably 2 to 20, and even more preferably 2 to 10.

[0072] R ６ When the alkyl group of R has two or more carbon atoms, it may contain one or more groups selected from the group consisting of a carbonyl group, an ester group, an amide group, and a sulfonyl group between carbon atoms, but does not contain these groups at both ends of the alkyl group. ６ The alkyl group may have 75% or less, 50% or less, or 25% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0073] R ６ As the general formula: -R １０ -CO-R １１ a group represented by the general formula: -R １０ -COO-R １１ a group represented by the general formula: -R１１ a group represented by the general formula: -R １０ -NR ８ CO-R １１ or a group represented by the general formula: -R １０ -CONR ８ -R １１ (wherein R ８ represents H or an organic group. １０ is an alkylene group, R １１ is preferably an alkyl group which may have a substituent. ６ As the general formula: -R １０ -CO-R １１ A group represented by the following formula is more preferred.

[0074] R ８ The organic group in R is preferably an alkyl group. ８ 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 even more preferred is H.

[0075] R １０ The number of carbon atoms in the alkylene group of R is preferably 1 or more, more preferably 3 or more, and is preferably 20 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 8 or less. １０ The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 3 to 10 carbon atoms.

[0076] R １１ The number of carbon atoms in the alkyl group of may be 1 to 20, preferably 1 to 15, more preferably 1 to 12, even more preferably 1 to 10, still more preferably 1 to 8, particularly preferably 1 to 6, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1. １１ The alkyl group of R is preferably composed of only primary, secondary and tertiary carbon atoms, and particularly preferably composed of only primary and secondary carbon atoms. １１ As the alkyl group, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group is preferred, and a methyl group is most preferred.

[0077] In general formula (1), R ２ and R ５ In one preferred embodiment, at least one of the above is a group represented by the general formula -XA, and A is -COOM.

[0078] The hydrocarbon surfactant may be a surfactant represented by the following formula (1-0A): (In the formula, R １Ａ ~R ５Ａ represents H, a monovalent hydrocarbon group which may contain an ester group between carbon atoms, or a group represented by the general formula: -X Ａ -A, where R ２Ａ and R ５Ａ At least one of the following is a general formula: -X Ａ represents a group represented by -A. Ａ is the same or different in each occurrence and represents a divalent hydrocarbon group, of the formula: -N(R ６Ａ )-R ７Ａ - (R ６Ａ is H or -CH ２ COOM (M is as described below), R ７Ａ A is a divalent hydrocarbon group) or a bond; A is the same or different in each occurrence and is -COOM (M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ is H or an organic group); R １Ａ ~R ５Ａ Any two of these may be bonded to each other to form a ring.

[0079] In general formula (1-0A), R １Ａ ~R ５Ａ In the formula (R), the number of carbon atoms in the monovalent hydrocarbon group, which may contain an ester group between carbon atoms, is preferably 1 to 50, and more preferably 5 to 20. １Ａ ~R ５Ａ Any two of these may be bonded to each other to form a ring. The monovalent hydrocarbon group which may contain an ester group between carbon atoms is preferably an alkyl group.Ａ In the formula (I), the number of carbon atoms in the divalent hydrocarbon group is preferably 1 to 50, and more preferably 5 to 20. Examples of the divalent hydrocarbon group include an alkylene group and an alkanediyl group, with an alkylene group being preferred.

[0080] In general formula (1-0A), R ２Ａ and R ５Ａ Any one of the above general formula: -X Ａ -A is preferred, and R ２Ａ is represented by the above general formula: -X Ａ A group represented by -A is more preferred.

[0081] In the general formula (1-0A), R ２Ａ is represented by the general formula: -X Ａ -A, and R １Ａ , R ３Ａ , R ４Ａ and R ５Ａ is H. In this case, X Ａ is preferably a bond or an alkylene group having 1 to 5 carbon atoms.

[0082] In the general formula (1-0A), a preferred embodiment is also R ２Ａ is represented by the general formula: -X Ａ -A, and R １Ａ and R ３Ａ Ga-Y Ａ -R ６ and Y Ａ are the same or different in each occurrence and are —COO—, —OCO—, or a bond; R ６ In this embodiment, R is the same or different in each occurrence and is an alkyl group having 1 or more carbon atoms. ４Ａ and R ５Ａ is preferably H.

[0083] Examples of hydrocarbon surfactants represented by general formula (1-0A) include glutaric acid or a salt thereof, adipic acid or a salt thereof, pimelic acid or a salt thereof, suberic acid or a salt thereof, azelaic acid or a salt thereof, and sebacic acid or a salt thereof. The aliphatic carboxylic acid hydrocarbon surfactant represented by general formula (1-0A) may also be a two-chain two-hydrophilic group synthetic surfactant, such as Gemini surfactants, such as Geminisurf (Chukyo Yushi Co., Ltd.), Gemsurf α142 (12 carbon atoms, lauryl group), Gemsurf α102 (10 carbon atoms), and Gemsurf α182 (14 carbon atoms).

[0084] In the general formula (1-0A), a preferred embodiment is also R １Ａ Ga-Y Ａ -R ６ and Y Ａ is a bond, and R ６ is an alkyl group having 1 or more carbon atoms (preferably an alkylene group having 6 to 20 carbon atoms), and R ２Ａ , R ３Ａ , R ４Ａ and R ５Ａ is H and X Ａ is represented by the formula: -N(R ６Ａ )-R ７Ａ - (R ６Ａ is H or -CH ２ COOM (M is as above), R ７Ａ is a group represented by an alkylene group having 1 to 5 carbon atoms (preferably a methylene group). An example of a surfactant in this embodiment is lauryl imine dicarboxylic acid.

[0085] The hydrocarbon surfactant also includes a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). Alternatively, a hydrocarbon surfactant obtained by subjecting a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups) to radical treatment or oxidation treatment can also be used. The radical treatment is any treatment that generates radicals in a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). For example, it is a treatment in which deionized water and a hydrocarbon surfactant are added to a reactor, the reactor is sealed, the system is purged with nitrogen, the reactor is heated and pressurized, a polymerization initiator is added, the mixture is stirred for a certain period of time, and the reactor is depressurized to atmospheric pressure and then cooled. The oxidation treatment is a treatment in which an oxidizing agent is added to a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). Examples of oxidizing agents include oxygen, ozone, hydrogen peroxide, manganese (IV) oxide, potassium permanganate, potassium dichromate, nitric acid, and sulfur dioxide. To promote the radical treatment or oxidation treatment, the radical treatment or oxidation treatment may be carried out in an aqueous solution with an adjusted pH. The pH of the aqueous solution used for the radical treatment or oxidation treatment is preferably less than 7, and the pH of the aqueous solution can be adjusted using sulfuric acid, nitric acid, hydrochloric acid, or the like.

[0086] The hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups) is preferably a surfactant represented by the formula: R Ｘ -X Ｘ (In the formula, R Ｘ is a fluorine-free organic group having 1 to 2000 carbon atoms and one or more carbonyl groups (excluding carbonyl groups in carboxyl groups), and X Ｘ Is -OSO ３ X Ｘ１ , -COOX Ｘ１ or -SO ３ X Ｘ１ (X Ｘ１ represents H, a metal atom, NR Ｘ１ ４, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R Ｘ１ are H or organic groups, and may be the same or different. Ｘ R preferably has 500 or less carbon atoms, more preferably 100 or less, even more preferably 50 or less, and even more preferably 30 or less. Ｘ１ The organic group in R is preferably an alkyl group. Ｘ１ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. The hydrocarbon surfactant is preferably a surfactant represented by the following formula (a): (In the formula, R １ａ R is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond, and when it has 2 or more carbon atoms, it may contain a carbonyl group, and when it has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ａ and R ３ａ are independently a single bond or a divalent linking group. １ａ , R ２ａ and R ３ａ has a total of 6 or more carbon atoms. ａ represents H, a metal atom, NR ４ａ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ａ are H or organic groups and may be the same or different. １ａ , R ２ａ and R ３ａ any two of which may be bonded to each other to form a ring; a surfactant (a) represented by the following formula (b): (In the formula, R １ｂR is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｂ and R ４ｂ are independently H or a substituent. ３ｂ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. n is an integer of 1 or more. p and q are independently integers of 0 or more. X ｂ represents H, a metal atom, NR ５ｂ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｂ are H or organic groups and may be the same or different. １ｂ , R ２ｂ , R ３ｂ and R ４ｂ Any two of the groups may be bonded to each other to form a ring. L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｂ -B-*, -NR ６ｂ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｂ -B-, -NR ６ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｂ is H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. * represents -OSO ３ X ｂ (b) a surfactant represented by the following formula (c): (In the formula, R １ｃR is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond, and when it has 2 or more carbon atoms, it may contain a carbonyl group, and when it has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｃ and R ３ｃ are independently a single bond or a divalent linking group. １ｃ , R ２ｃ and R ３ｃ has a total of 5 or more carbon atoms. ｃ Ha, -COOX ｃ or -SO ３ X ｃ (X ｃ represents H, a metal atom, NR ４ｃ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ｃ are H or organic groups, and may be the same or different. １ｃ , R ２ｃ and R ３ｃ any two of which may be bonded to each other to form a ring; and a surfactant (c) represented by the following formula (d): (In the formula, R １ｄ R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｄ and R ４ｄ are independently H or a substituent. ３ｄ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. n is an integer of 1 or more. p and q are independently integers of 0 or more. A ｄ is -SO ３ X ｄ or -COOX ｄ (X ｄ represents H, a metal atom, NR ５ｄ ４, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｄ are H or organic groups, and may be the same or different. １ｄ , R ２ｄ , R ３ｄ and R ４ｄ Any two of the groups may be bonded to each other to form a ring. L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｄ -B-*, -NR ６ｄ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｄ -B-, -NR ６ｄ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｄ is H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. ｄ It is more preferable that the surfactant (d) is at least one selected from the group consisting of surfactants (d) represented by the formula:

[0087] The surfactant (a) will now be described.

[0088] In formula (a), R １ａ is a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms. When the alkyl group has three or more carbon atoms, it may contain a carbonyl group (-C(=O)-) between two carbon atoms. When the alkyl group has two or more carbon atoms, it may also contain the carbonyl group at the terminal of the alkyl group. That is, CH ３ The alkyl group also includes acyl groups such as an acetyl group represented by -C(=O)-. When the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocyclic ring or may form a ring. The heterocyclic ring is preferably an unsaturated heterocyclic ring, more preferably an oxygen-containing unsaturated heterocyclic ring, such as a furan ring. R １ａIn the above, a divalent heterocycle may be inserted between two carbon atoms, a divalent heterocycle may be located at a terminal and bonded to —C(═O)—, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0089] In the present disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the carbonyl group and the number of carbon atoms constituting the heterocyclic ring. ３ —C(═O)—CH ２ The group represented by - has 3 carbon atoms, and ３ -C(=O)-C ２ H ４ -C(=O)-C ２ H ４ The group represented by - has 7 carbon atoms, and CH ３ The group represented by —C(═O)— has 2 carbon atoms.

[0090] In the alkyl group, a hydrogen atom bonded to a carbon atom may be substituted with a functional group, for example, a hydroxy group (—OH) or a monovalent organic group containing an ester bond, but it is preferable that the alkyl group is not substituted with any functional group. Examples of the monovalent organic group containing an ester bond include a group represented by the formula: —O—C(═O)—R １０１ａ (In the formula, R １０１ａ The alkyl group may be one in which 75% or less, 50% or less, or 25% or less of the hydrogen atoms bonded to carbon atoms are substituted with halogen atoms, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0091] In the formula, R ２ａ and R ３ａ are independently a single bond or a divalent linking group. ２ａ and R ３ａ are preferably each independently a single bond, a linear or branched alkylene group having one or more carbon atoms, or a cyclic alkylene group having three or more carbon atoms. ２ａ and R ３ａThe alkylene group constituting the formula (I) preferably does not contain a carbonyl group.

[0092] In the alkylene group, a hydrogen atom bonded to a carbon atom may be substituted with a functional group, for example, a hydroxy group (—OH) or a monovalent organic group containing an ester bond, but it is preferable that the alkylene group is not substituted with any functional group. Examples of the monovalent organic group containing an ester bond include a group represented by the formula: —O—C(═O)—R １０２ａ (In the formula, R １０２ａ The alkylene group may have 75% or less, 50% or less, or 25% or less of the hydrogen atoms bonded to carbon atoms substituted with halogen atoms, but is preferably a non-halogenated alkylene group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0093] R １ａ , R ２ａ and R ３ａ R has a total number of carbon atoms of 6 or more. The total number of carbon atoms is preferably 8 or more, more preferably 9 or more, and even more preferably 10 or more, and is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. １ａ , R ２ａ and R ３ａ Any two of these may be bonded to each other to form a ring.

[0094] In formula (a), X ａ represents H, a metal atom, NR ４ａ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ａ is H or an organic group. ４ａ may be the same or different. ４ａ The organic group in R is preferably an alkyl group. ４ａX is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. ａ is H, an alkali metal (group 1), an alkaline earth metal (group 2), or NR ４ａ ４ is preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred. ａ NH ４ In this case, the surfactant has excellent solubility in an aqueous medium, and metal components are less likely to remain in the PTFE or the final product.

[0095] Examples of the surfactant (a) include the following surfactants: ａ is as described above.

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] Next, the surfactant (b) will be described.

[0105] In formula (b), R １ｂR is a linear or branched alkyl group having 1 or more carbon atoms, which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms, which may have a substituent. When the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle, or may form a ring. As the heterocycle, an unsaturated heterocycle is preferable, and an oxygen-containing unsaturated heterocycle is more preferable, and examples thereof include a furan ring. １ｂ In the above, a divalent heterocycle may be inserted between two carbon atoms, a divalent heterocycle may be located at a terminal and bonded to —C(═O)—, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0106] In the present disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the heterocycle.

[0107] R １ｂ The substituent that the alkyl group as the group may have is preferably a halogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, or a hydroxy group, and particularly preferably a methyl group or an ethyl group.

[0108] R １ｂ The alkyl group as the alkyl group preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group preferably does not have any substituents.

[0109] R １ｂAs the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent or a cyclic alkyl group having 3 to 10 carbon atoms which may have a substituent is preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not contain a carbonyl group or a cyclic alkyl group having 3 to 10 carbon atoms which does not contain a carbonyl group is more preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not have a substituent is even more preferred, a linear or branched alkyl group having 1 to 3 carbon atoms which does not have a substituent is even more preferred, and a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is particularly preferred, and a methyl group (—CH ３ ) is most preferred.

[0110] In formula (b), R ２ｂ and R ４ｂ are independently H or a substituent. ２ｂ and R ４ｂ may be the same or different.

[0111] R ２ｂ and R ４ｂ The substituent as is preferably a halogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, or a hydroxy group, and particularly preferably a methyl group or an ethyl group.

[0112] R ２ｂ and R ４ｂ The alkyl group as the alkyl group preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group preferably does not have any substituents.

[0113] R ２ｂ and R ４ｂThe alkyl group as the alkyl group is preferably a linear or branched alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, or a cyclic alkyl group having 3 to 10 carbon atoms and not containing a carbonyl group, more preferably a linear or branched alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, still more preferably a linear or branched alkyl group having 1 to 3 carbon atoms and not containing a substituent, and a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is particularly preferred.

[0114] R ２ｂ and R ４ｂ are each independently preferably H or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, more preferably H or a straight-chain or branched-chain alkyl group having 1 to 3 carbon atoms and not containing a substituent, and are each independently preferably H, a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is even more preferred, with H being especially preferred.

[0115] In formula (b), R ３ｂ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. ３ｂ When there are a plurality of, they may be the same or different.

[0116] The alkylene group preferably does not contain a carbonyl group. The alkylene group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkylene group preferably does not have any substituents.

[0117] The alkylene group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms which may have a substituent, or a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, more preferably a linear or branched alkylene group having 1 to 10 carbon atoms which does not contain a carbonyl group, or a cyclic alkylene group having 3 to 10 carbon atoms which does not contain a carbonyl group, and more preferably a linear or branched alkylene group having 1 to 10 carbon atoms which does not have a substituent, and a methylene group (—CH ２ -), ethylene group (-C ２ H ４ -), isopropylene group (-CH(CH ３ ) CH ２ -) or propylene group (-C ３ H ６ -) is more preferred.

[0118] R １ｂ , R ２ｂ , R ３ｂ and R ４ｂ Any two of may be bonded to each other to form a ring, but it is preferable that they do not form a ring.

[0119] In formula (b), n is an integer of 1 or greater. n is preferably an integer of 1 to 40, more preferably an integer of 1 to 30, still more preferably an integer of 5 to 25, and particularly preferably an integer of 5 to 9 or 11 to 25.

[0120] In formula (b), p and q are independently an integer of 0 or greater. p is preferably an integer of 0 to 10, and more preferably 0 or 1. q is preferably an integer of 0 to 10, and more preferably an integer of 0 to 5.

[0121] The sum of n, p, and q is preferably an integer of 5 or greater. The sum of n, p, and q is more preferably an integer of 8 or greater. The sum of n, p, and q is also preferably an integer of 60 or less, more preferably an integer of 50 or less, and even more preferably an integer of 40 or less.

[0122] In formula (b), X ｂ represents H, a metal atom, NR ５ｂ ４, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｂ is H or an organic group. ５ｂ may be the same or different. ５ｂ The organic group in R is preferably an alkyl group. ５ｂ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. X ｂ is a metal atom or NR ５ｂ ４ (R ５ｂ X may be as defined above. ｂ is H, an alkali metal (group 1), an alkaline earth metal (group 2), or NR ５ｂ ４ is preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred. ｂ NH ４ In this case, the surfactant has excellent solubility in an aqueous medium, and metal components are less likely to remain in the PTFE or the final product.

[0123] In formula (b), L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｂ -B-*, -NR ６ｂ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｂ -B-, -NR ６ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｂis H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. The alkylene group more preferably has 1 to 5 carbon atoms. ６ is more preferably H or a methyl group. ３ X ｂ This refers to the side that binds to the

[0124] L is preferably a single bond.

[0125] The surfactant (b) may be, for example, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH２ CH ２ CH ２ OSO ３ Na, (CH ３ ) ３ CC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, (CH ３ ) ２ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, (CH ２ ) ５ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P.S. ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ I'm sorry ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OCH ２ OSO ３ Na, CH３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P.S. ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ H、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Li, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ K、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ NH ４ 、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH２ CH ２ CH ２ CH(CH ３ ) ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH２ OSO ３ Na, (CH ３ ) ３ CC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, (CH ３ ) ２ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, (CH ２ ) ５ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２CH ２ CH ２ P.S. ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ I'm sorry ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OCH ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH２ CH ２ P.S. ２ CH ２ OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OSO ３ Na, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ H、 CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Li, CH ３ CH ２C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ K, CH ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ NH ４ , CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OSO ３ Examples include K, Na, etc.

[0126] Surfactant (c) will be described.

[0127] In formula (c), R １ｃ is a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms. When the alkyl group has three or more carbon atoms, it may contain a carbonyl group (-C(=O)-) between two carbon atoms. When the alkyl group has two or more carbon atoms, it may also contain the carbonyl group at the terminal of the alkyl group. That is, CH ３ The alkyl group also includes acyl groups such as an acetyl group represented by -C(=O)-. When the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocyclic ring or may form a ring. The heterocyclic ring is preferably an unsaturated heterocyclic ring, more preferably an oxygen-containing unsaturated heterocyclic ring, such as a furan ring. R １ｃ In the above, a divalent heterocycle may be inserted between two carbon atoms, a divalent heterocycle may be located at a terminal and bonded to —C(═O)—, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0128] In the present disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the carbonyl group and the number of carbon atoms constituting the heterocyclic ring. ３ —C(═O)—CH ２ The group represented by - has 3 carbon atoms, and ３ -C(=O)-C ２ H ４ -C(=O)-C ２ H ４ The group represented by - has 7 carbon atoms, and CH ３ The group represented by —C(═O)— has 2 carbon atoms.

[0129] In the alkyl group, a hydrogen atom bonded to a carbon atom may be substituted with a functional group, for example, a hydroxy group (—OH) or a monovalent organic group containing an ester bond, but it is preferable that the alkyl group is not substituted with any functional group. Examples of the monovalent organic group containing an ester bond include a group represented by the formula: —O—C(═O)—R １０１ｃ (In the formula, R １０１ｃThe alkyl group may be one in which 75% or less, 50% or less, or 25% or less of the hydrogen atoms bonded to carbon atoms are substituted with halogen atoms, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0130] In formula (c), R ２ｃ and R ３ｃ are independently a single bond or a divalent linking group. ２ｃ and R ３ｃ are preferably each independently a single bond, a linear or branched alkylene group having one or more carbon atoms, or a cyclic alkylene group having three or more carbon atoms. ２ｃ and R ３ｃ The alkylene group constituting the formula (I) preferably does not contain a carbonyl group.

[0131] In the alkylene group, a hydrogen atom bonded to a carbon atom may be substituted with a functional group, for example, a hydroxy group (—OH) or a monovalent organic group containing an ester bond, but it is preferable that the alkylene group is not substituted with any functional group. Examples of the monovalent organic group containing an ester bond include a group represented by the formula: —O—C(═O)—R １０２ｃ (In the formula, R １０２ｃ The alkylene group may have 75% or less, 50% or less, or 25% or less of the hydrogen atoms bonded to carbon atoms substituted with halogen atoms, but is preferably a non-halogenated alkylene group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0132] R １ｃ , R ２ｃ and R ３ｃ R has a total carbon number of 5 or more. The total carbon number is preferably 7 or more, more preferably 9 or more, and is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. １ｃ , R ２ｃ and R ３ｃAny two of these may be bonded to each other to form a ring.

[0133] In formula (c), in the formula, A ｃ Ha, -COOX ｃ or -SO ３ X ｃ (X ｃ represents H, a metal atom, NR ４ｃ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ｃ are H or organic groups, and may be the same or different. ４ｃ The organic group in R is preferably an alkyl group. ４ｃ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. X ｃ is H, an alkali metal (group 1), an alkaline earth metal (group 2), or NR ４ｃ ４ is preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred. ｃ NH ４ In this case, the surfactant has excellent solubility in an aqueous medium, and metal components are less likely to remain in the PTFE or the final product.

[0134] Examples of the surfactant (c) include the following surfactants: ｃ is as described above.

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143] The surfactant (d) will now be described.

[0144] In formula (d), R １ｄ R is a linear or branched alkyl group having 1 or more carbon atoms, which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms, which may have a substituent. When the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle, or may form a ring. As the heterocycle, an unsaturated heterocycle is preferable, and an oxygen-containing unsaturated heterocycle is more preferable, and examples thereof include a furan ring. １ｄ In the above, a divalent heterocycle may be inserted between two carbon atoms, a divalent heterocycle may be located at a terminal and bonded to —C(═O)—, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0145] In the present disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the heterocycle.

[0146] R １ｄ The substituent that the alkyl group as the group may have is preferably a halogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, or a hydroxy group, and particularly preferably a methyl group or an ethyl group.

[0147] R １ｄThe alkyl group as the alkyl group preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group preferably does not have any substituents.

[0148] R １ｄ As the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent or a cyclic alkyl group having 3 to 10 carbon atoms which may have a substituent is preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not contain a carbonyl group or a cyclic alkyl group having 3 to 10 carbon atoms which does not contain a carbonyl group is more preferred, a linear or branched alkyl group having 1 to 10 carbon atoms which does not have a substituent is even more preferred, a linear or branched alkyl group having 1 to 3 carbon atoms which does not have a substituent is even more preferred, and a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is particularly preferred, and a methyl group (—CH ３ ) is most preferred.

[0149] In formula (d), R ２ｄ and R ４ｄ are independently H or a substituent. ２ｄ and R ４ｄ may be the same or different.

[0150] R ２ｄ and R ４ｄ The substituent as is preferably a halogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, or a hydroxy group, and particularly preferably a methyl group or an ethyl group.

[0151] R ２ｄ and R ４ｄThe alkyl group as the alkyl group preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group preferably does not have any substituents.

[0152] R ２ｄ and R ４ｄ The alkyl group as the alkyl group is preferably a linear or branched alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, or a cyclic alkyl group having 3 to 10 carbon atoms and not containing a carbonyl group, more preferably a linear or branched alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, still more preferably a linear or branched alkyl group having 1 to 3 carbon atoms and not containing a substituent, and a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is particularly preferred.

[0153] R ２ｄ and R ４ｄ are each independently preferably H or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms and not containing a carbonyl group, more preferably H or a straight-chain or branched-chain alkyl group having 1 to 3 carbon atoms and not containing a substituent, and are each independently preferably H, a methyl group (—CH ３ ) or an ethyl group (-C ２ H ５ ) is even more preferred, with H being especially preferred.

[0154] In formula (d), R ３ｄ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. ３ｄ When there are a plurality of, they may be the same or different.

[0155] The alkylene group preferably does not contain a carbonyl group. The alkylene group may have 75% or less of the hydrogen atoms bonded to the carbon atoms substituted with halogen atoms, 50% or less, or 25% or less, but is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkylene group preferably does not have any substituents.

[0156] The alkylene group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms which may have a substituent, or a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, more preferably a linear or branched alkylene group having 1 to 10 carbon atoms which does not contain a carbonyl group, or a cyclic alkylene group having 3 to 10 carbon atoms which does not contain a carbonyl group, and more preferably a linear or branched alkylene group having 1 to 10 carbon atoms which does not have a substituent, and a methylene group (—CH ２ -), ethylene group (-C ２ H ４ -), isopropylene group (-CH(CH ３ ) CH ２ -) or propylene group (-C ３ H ６ -) is more preferred.

[0157] R １ｄ , R ２ｄ , R ３ｄ and R ４ｄ Any two of these may be bonded to each other to form a ring.

[0158] In formula (d), n is an integer of 1 or greater. n is preferably an integer of 1 to 40, more preferably an integer of 1 to 30, and even more preferably an integer of 5 to 25.

[0159] In formula (d), p and q are independently an integer of 0 or greater. p is preferably an integer of 0 to 10, and more preferably 0 or 1. q is preferably an integer of 0 to 10, and more preferably an integer of 0 to 5.

[0160] The sum of n, p, and q is preferably an integer of 6 or greater. The sum of n, p, and q is more preferably an integer of 8 or greater. The sum of n, p, and q is also preferably an integer of 60 or less, more preferably an integer of 50 or less, and even more preferably an integer of 40 or less.

[0161] In formula (d), A ｄ is -SO ３ X ｄ or -COOX ｄ (X ｄ represents H, a metal atom, NR ５ｄ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｄ are H or organic groups, and may be the same or different. ５ｄ The organic group in R is preferably an alkyl group. ５ｄ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. X ｄ is a metal atom or NR ５ｄ ４ (R ５ｄ X may be as defined above. ｄ is H, an alkali metal (group 1), an alkaline earth metal (group 2), or NR ５ｄ ４ is preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred. ｄ NH ４ In this case, the surfactant has excellent solubility in an aqueous medium, and metal components are less likely to remain in the PTFE or the final product.

[0162] In formula (d), L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｄ -B-*, -NR ６ｄ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｄ -B-, -NR ６ｄ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｄ is H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. The alkylene group more preferably has 1 to 5 carbon atoms. ６ｄ is more preferably H or a methyl group. ｄ This refers to the side that binds to the

[0163] L is preferably a single bond.

[0164] Examples of the surfactant (d) include CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COOK, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COONa, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COONa, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ COONa, CH ３ C(O)CH２ CH ２ CH ２ CH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COONa, (CH ３ ) ３ CC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COONa, (CH ３ ) ２ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ COONa, (CH ２ )５ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ Yes, yes ３ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ Yes, yes ３ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ Yes, yes ３ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ Yes, yes ３ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ CH ２ Yes, yes ３ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH ２ CH ２ Yes, yes ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ CH２ Yes, yes ３ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)CH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ２ CH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P.S. ２ COOK, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ I'm sorry ２ COOK, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OCH ２ Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P.S. ２Yes, yes ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)COONa, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)COOH、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)COOLi、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P. ４ 、 CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)COONa, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(CH ３ ) ２ COOK, CH ３ C(O)CH ２ CH ２ CH ２ CH２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, (CH ３ ) ３ CC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, (CH ３ ) ２ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, (CH ２ ) ５ CHC(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH２ CH ２ CH ２ SO ２ CH ２ CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ P.S. ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ I'm sorry ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(O)OCH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２CH ２ OC(O)CH ２ SO ３ Na, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ H, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ K, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ Li, CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ SO ３ NH ４ , CH ３ C(O)CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ C(CH ３ ) ２ SO ３ Examples include Na etc.

[0165] The hydrocarbon surfactant may be a compound represented by the following formula I: R-(XZ) ｎ (I) wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of groups is at least about 70%, and the hydrophobic moiety does not include a siloxane unit. Each X, which may be the same or different, represents an ionic hydrophilic moiety. Each Z, which may be the same or different, represents one or more counterions of the ionic hydrophilic moiety. n is 1 to 3.

[0166] Compound I exhibits low reactivity with the polymerization initiator and / or propagating fluoropolymer radical in the polymerization of TFE.

[0167] Compound I has the following formula: (In the formula, Y ＋ is hydrogen, ammonium, quaternary ammonium, nitrogen heterocycle, alkali metal, or alkaline earth.

[0168] Compound I has the following formula II: (In the formula, R ２’ and R ２’’ are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms; R ２’ and R ２’’ CH in the group ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of groups is at least about 70%, or R ２’ and R ２’’ may be joined together to form a saturated or unsaturated aliphatic ring which may contain ether or ester bonds, provided that CH ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of R groups is at least about 70%. １ is hydrogen, methoxy, ethoxy or phenoxy. ＋is hydrogen, ammonium, quaternary ammonium, a nitrogen heterocycle, an alkali metal, or an alkaline earth.

[0169] As Compound II, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0170] Compound I has the following formula III: (In the formula, R ３ , R ４’ , and R ４’’ are the same or different and are hydrogen or a saturated or unsaturated, acyclic or cyclic aliphatic group having 4 to 16 carbon atoms; R ３ , R ４’ , and R ４’’ CH in the group ３ , C.H. ２ and CH for the sum of CH groups ３ The total percentage of R is at least about 70%. ３ , R ４’ , and R ４’’ At least one of R is not hydrogen; ４’ and R ４’’ is hydrogen, R ３ is not hydrogen, but R ３ is hydrogen, R ４’ and R ４’’ is not hydrogen. ＋ is hydrogen, ammonium, quaternary ammonium, a nitrogen heterocycle, an alkali metal, or an alkaline earth.

[0171] As the compound III, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0172] In the production method of the present disclosure, two or more of the above hydrocarbon surfactants may be used simultaneously.

[0173] In addition, as hydrocarbon surfactants, for example, the above-mentioned surfactant (1), the above-mentioned hydrocarbon surfactants having one or more carbonyl groups (but excluding the carbonyl group in carboxyl group), or the specific hydrocarbon surfactants that have undergone radical treatment or oxidation treatment on the hydrocarbon surfactants that have one or more carbonyl groups (but excluding the carbonyl group in carboxyl group).The specific hydrocarbon surfactant is also preferably the above-mentioned hydrocarbon surfactants having one or more carbonyl groups (but excluding the carbonyl group in carboxyl group), or the hydrocarbon surfactants that have undergone radical treatment or oxidation treatment on the hydrocarbon surfactants that have one or more carbonyl groups (but excluding the carbonyl group in carboxyl group).By using the specific hydrocarbon surfactants that have undergone radical treatment or oxidation treatment, primary particles with small average primary particle diameter and aspect ratio can be easily obtained, and therefore, the polymerization of TFE in aqueous medium can proceed smoothly, and PTFE can be easily produced.

[0174] The radical treatment may be any treatment that causes radicals to act on a hydrocarbon surfactant. For example, it is a treatment that involves adding deionized water and a hydrocarbon surfactant to a reactor, sealing the reactor, replacing the atmosphere in the system with nitrogen, raising the temperature and pressure of the reactor, adding a polymerization initiator, stirring for a certain period of time, depressurizing the reactor to atmospheric pressure, and then cooling. The oxidation treatment is a treatment that causes an oxidizing agent to act on a carboxylic acid-type hydrocarbon surfactant. Examples of oxidizing agents include oxygen, ozone, hydrogen peroxide, manganese (IV) oxide, potassium permanganate, potassium dichromate, nitric acid, and sulfur dioxide.

[0175] The specific hydrocarbon surfactant is preferably at least one selected from the group consisting of surfactant (1) represented by the general formula (1), surfactant (a) represented by the formula (a), surfactant (b) represented by the formula (b), surfactant (c) represented by the formula (c), surfactant (d) represented by the formula (d), and surfactants obtained by subjecting these surfactants (a) to (d) to radical treatment or oxidation treatment, and more preferably at least one selected from the group consisting of surfactant (a) represented by the formula (a), surfactant (b) represented by the formula (b), surfactant (c) represented by the formula (c), surfactant (d) represented by the formula (d), and surfactants obtained by subjecting these surfactants (a) to (d) to radical treatment or oxidation treatment.

[0176] The hydrocarbon surfactant used in the manufacturing method of the present disclosure is preferably a carboxylic acid hydrocarbon surfactant. Carboxylic acid hydrocarbon surfactants tend to have a shorter coagulation completion time compared to sulfate ester surfactants. However, according to the manufacturing method of the present disclosure, even when a carboxylic acid hydrocarbon surfactant is used, an aqueous dispersion with a long coagulation completion time can be produced. In other words, the manufacturing method of the present disclosure is particularly suitable when the hydrocarbon surfactant is a carboxylic acid hydrocarbon surfactant. The carboxylic acid hydrocarbon surfactant is typically an anionic hydrocarbon surfactant having a hydrophilic portion of a carboxylate salt and a hydrophobic portion that is a long-chain hydrocarbon portion such as an alkyl. Specifically, the surfactant is not limited as long as it has a carboxyl group (-COOH) or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation (e.g., a metal atom, ammonium, etc.). For example, from the hydrocarbon surfactants described above, a hydrocarbon surfactant having a carboxyl group or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation can be used.

[0177] The carboxylic acid hydrocarbon surfactant may be an aliphatic carboxylic acid hydrocarbon surfactant, or a non-aliphatic carboxylic acid hydrocarbon surfactant. In the present disclosure, "aliphatic carboxylic acid hydrocarbon surfactant" refers to a carboxylic acid hydrocarbon surfactant that does not contain a carbonyl group (excluding carboxyl groups and carbonyl groups in ester groups). The ester group refers to a group represented by -COO- or -OCO-.

[0178] As the carboxylic acid type hydrocarbon surfactant, for example, from among the hydrocarbon surfactants described above, a hydrocarbon surfactant having a carboxyl group or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation can be used.

[0179] The carboxylic acid type hydrocarbon surfactant includes surfactant (1), the surfactant of the above-mentioned formula: R ６ｚ (-L-M) ２ and anionic surfactants represented by the above formula: R ７ｚ (-L-M) ３ Among the anionic surfactants represented by the formula (I), it is preferable to use at least one selected from the group consisting of those having a carboxyl group (-COOH) or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.), compound (α), surfactant (1-0A), and surfactants obtained by radical treatment or oxidation treatment of these surfactants. The above carboxylic acid type hydrocarbon surfactants may be used alone or as a mixture of two or more types.

[0180] The compound (α) has the above-mentioned formula: R １００ -COOM (in the formula, R １００ and M are the same as above.) (preferably, the compound represented by formula (A)), as well as the anionic hydrocarbon surfactant represented by the above formula: R ｚ -LM (wherein, R ｚ, L and M are the same as above), surfactants (c) and (d) which have a carboxyl group (—COOH) or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.).

[0181] The carboxylic acid type hydrocarbon surfactant is preferably the compound (α), and the compound represented by the formula (A) above, ｃ Ga-COOX ｃ a compound represented by the formula (d) ｄ Ga-COOX ｄ a compound represented by the above formula (1) where A is -COOM, a compound represented by the above formula (1-0A) where A is -COOM, and compounds obtained by subjecting these compounds to radical treatment or oxidation treatment, and further preferably at least one selected from the group consisting of a compound represented by the above formula (A) and compounds obtained by subjecting these compounds to radical treatment or oxidation treatment.

[0182] As the carboxylic acid type hydrocarbon surfactant, at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof, and compounds obtained by radical treatment or oxidation treatment of these compounds, is particularly preferred, at least one selected from the group consisting of lauric acid and salts thereof, and compounds obtained by radical treatment or oxidation treatment of these compounds, is more preferred, at least one selected from the group consisting of salts of lauric acid and compounds obtained by radical treatment or oxidation treatment of these, is even more preferred, and at least one selected from the group consisting of sodium laurate and compounds obtained by radical treatment or oxidation treatment of these, is even more preferred. As the above salts, there are preferred salts in which the hydrogen of the carboxyl group is bonded to a metal atom of the above formula M, NR １０１ ４ Examples of the compound include, but are not limited to, imidazolium which may have a substituent, pyridinium which may have a substituent, and phosphonium which may have a substituent.

[0183] The carboxylic acid type hydrocarbon surfactant is preferably at least one selected from the group consisting of surfactant (1-0A) represented by the above general formula (1-0A), compound (α) represented by the above formula (c), surfactant (c) represented by the above formula (c), and surfactant (d) represented by the above formula (d).

[0184] (Aqueous Medium) The aqueous medium used in the production method of the present disclosure refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, an ether, or a ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower.

[0185] The aqueous medium is preferably an aqueous medium containing only water, or an aqueous medium containing only water and a fluorine-free organic solvent, and more preferably an aqueous medium containing only water.

[0186] The water content in the aqueous medium is preferably 90% or more, more preferably 95% or more, even more preferably 99.0% or more, still more preferably 99.5% or more, particularly preferably 99.9% or more, and may be 100%, based on the mass of the aqueous medium.

[0187] (Monomer) In the manufacturing method of the present disclosure, it is also preferred to polymerize TFE and modified monomer.That is, PTFE can be the homo-PTFE that only contains TFE unit, or can be the modified PTFE that contains TFE unit and the modified monomer unit that is based on the modified monomer that can copolymerize with TFE.

[0188] The amount of the modified monomer added when polymerizing TFE is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.03% by mass or more, particularly preferably 0.05% by mass or more, and preferably 1.0% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.5% by mass or less, particularly preferably 0.3% by mass or less, based on the amount of PTFE obtained.

[0189] 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.

[0190] 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.

[0191] The modifying monomer is preferably at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene, and more preferably 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.

[0192] (Polymerization) In the manufacturing method of the present disclosure, polymerization of TFE is usually carried out at a polymerization temperature of 10 to 150 ° C and a polymerization pressure of 0.05 to 5 MPaG. For example, the polymerization temperature is more preferably 30 ° C or higher, and even more preferably 50 ° C or higher. Also, it is more preferably 120 ° C or lower, and even more preferably 100 ° C or lower. Also, the polymerization pressure is more preferably 0.3 MPaG or higher, and even more preferably 0.5 MPaG or higher, and also more preferably 5.0 MPaG or lower, and even more preferably 3.0 MPaG or lower. Particularly, from the viewpoint of improving the yield of PTFE, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, more preferably 1.5 MPaG or higher, and even more preferably 2.0 MPaG or higher.

[0193] In one embodiment, the polymerization is carried out by charging pure water into a pressure-resistant reactor equipped with a stirrer, deoxidizing, then charging TFE, adjusting the temperature to a predetermined value, and adding a polymerization initiator to initiate the reaction. If the pressure decreases as the reaction proceeds, additional TFE is continuously or intermittently supplied to maintain the initial pressure. When a predetermined amount of TFE has been supplied, the supply is stopped, the TFE in the reactor is purged, and the temperature is returned to room temperature to terminate the reaction. Additional TFE may be continuously or intermittently supplied to prevent the pressure from decreasing.

[0194] As the polymerization initiator, persulfates (e.g., ammonium persulfate), or organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide can be used alone or in the form of a mixture thereof. They may also be used in combination with a reducing agent such as sodium sulfite to form a redox system. Furthermore, during polymerization, a radical scavenger such as hydroquinone or catechol, or a peroxide decomposer such as ammonium sulfite, can be added to adjust the radical concentration in the system.

[0195] As the redox polymerization initiator, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of redox initiators. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0196] Examples of the redox initiator include potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, ammonium persulfate / bisulfite / iron sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, and bromate / bisulfite, with potassium permanganate / oxalic acid being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / oxalic acid is used, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate thereto.

[0197] Any known chain transfer agent can be used, including, for example, saturated hydrocarbons such as methane, ethane, propane, and butane; halogenated hydrocarbons such as chloromethane, dichloromethane, and difluoroethane; alcohols such as methanol, ethanol, and isopropanol; and hydrogen. However, those that are in a gaseous state at room temperature and normal pressure are preferred.

[0198] The amount of the chain transfer agent used is usually 1 to 10,000 ppm by mass, preferably 1 to 5,000 ppm by mass, based on the total amount of TFE supplied.

[0199] In the polymerization of TFE, a saturated hydrocarbon having 12 or more carbon atoms, which is substantially inert to the reaction and becomes liquid under the above-mentioned reaction conditions, can also be used as a dispersion stabilizer for the reaction system in an amount of 2 to 10 parts by mass per 100 parts by mass of the aqueous medium. Furthermore, ammonium carbonate, ammonium phosphate, etc. can be added as a buffer for adjusting the pH during the reaction.

[0200] (Aqueous Dispersion Obtained by Polymerization) When the polymerization of TFE is completed, an aqueous dispersion having a solid content concentration of 1.0 to 50 mass % and an average primary particle size of 50 to 500 nm can be obtained.

[0201] The lower limit of the solid content is preferably 5% by mass, more preferably 8% by mass, and the upper limit is not particularly limited, but may be 40% by mass or 35% by mass.

[0202] The lower limit of the average primary particle size is preferably 100 nm, more preferably 150 nm, and the upper limit is preferably 400 nm, more preferably 350 nm. The average primary particle size can be measured by dynamic light scattering.

[0203] (Coagulation) In the production method of the present disclosure, after obtaining an aqueous dispersion containing non-melt-processible PTFE, the non-melt-processible PTFE in the obtained aqueous dispersion is coagulated to obtain a wet powder.

[0204] As coagulation method, preferably at least one coagulation method selected from the group consisting of stirring coagulation method, ultrasonic coagulation method, ultrafine bubble coagulation method, alkali coagulation method, acid coagulation method, oxidizing agent coagulation method, organic solvent coagulation method and radical generator coagulation method.In the manufacturing method of the present disclosure, also preferably, while stirring aqueous dispersion, use ultrasonic coagulation method, ultrafine bubble coagulation method, alkali coagulation method, acid coagulation method, oxidizing agent coagulation method, organic solvent coagulation method and radical generator coagulation method to coagulate non-melt-processable PTFE.

[0205] As will be described later, if heat treatment is carried out at a relatively low temperature, the content of the fluorine-containing compound with hydrophilic group in wet powder cannot be reduced sufficiently, and therefore, the non-melt-processable PTFE that can be extruded under stable extrusion pressure may not be obtained.On the other hand, if heat treatment temperature is too high, although the content of the fluorine-containing compound with hydrophilic group in wet powder can be reduced, the extrusion pressure of the non-melt-processable PTFE that can be obtained becomes too high.By carrying out heat treatment at a relatively low temperature and carrying out coagulation by above-mentioned method, it is possible to completely remove the fluorine-containing compound with hydrophilic group and stabilize the low extrusion pressure.

[0206] The temperature of the aqueous dispersion for coagulating the non-melt-processible PTFE may be 3 to 95°C, may be 5°C or higher, may be 10°C or higher, may be 85°C or lower, may be 75°C or lower, or may be 60°C or lower.

[0207] In the coagulation method by stirring, the aqueous dispersion is strongly stirred to the extent that the non-melt-processible PTFE particles are coagulated. Stirring can be carried out, for example, using a container equipped with a stirrer. Coagulation by the coagulation method by stirring can also be carried out continuously using an in-line mixer or the like.

[0208] In the ultrasonic coagulation method, an aqueous dispersion is irradiated with ultrasonic waves strong enough to coagulate the non-melt-processible PTFE particles.

[0209] The ultrasonic output is preferably 100 W or more, more preferably 200 W or more, even more preferably 300 W or more, still more preferably 400 W or more, particularly preferably 500 W or more, and preferably 3000 W or less, more preferably 1000 W or less, and even more preferably 800 W or less.

[0210] The frequency of the ultrasonic waves is preferably 15 kHz or more, more preferably 20 kHz or more, even more preferably 25 kHz or more, still more preferably 30 kHz or more, particularly preferably 40 kHz or more, and preferably 100 kHz or less, more preferably 80 kHz or less, and even more preferably 50 kHz or less.

[0211] The ultrasonic irradiation time is preferably 60 seconds or more, more preferably 300 seconds or more, and preferably 20 minutes or less.

[0212] Ultrasonic irradiation can be carried out using a commercially available ultrasonic generator, such as a commercially available ultrasonic transmitter (e.g., ultrasonic homogenizer), ultrasonic transmitter, circulating ultrasonic irradiator, ultrasonic vibrator, ultrasonic cleaner, etc.

[0213] Specific methods for irradiating with ultrasonic waves include, for example, a method in which the nozzle of an ultrasonic homogenizer is immersed in the aqueous dispersion, a method in which a throw-in type ultrasonic vibrator is immersed in a container containing a PTFE aqueous dispersion and irradiated, a method in which a container containing a PTFE aqueous dispersion is introduced into an ultrasonic cleaner that has an aqueous medium or the like previously charged therein and irradiated, a method in which the PTFE dispersion is introduced into a tank-type ultrasonic cleaner or ultrasonic oscillator and irradiated, a method in which the PTFE aqueous dispersion is introduced into a tank equipped with a rod-shaped ultrasonic irradiator and irradiated with ultrasonic waves, etc. It is also preferable to irradiate the aqueous dispersion with ultrasonic waves while stirring the aqueous dispersion.

[0214] In the coagulation method using ultrafine bubbles, ultrafine bubbles are generated in an aqueous dispersion in an amount sufficient to coagulate non-melt-processible PTFE particles. Ultrafine bubbles are bubbles with a diameter of 1 μm or less. Ultrafine bubbles can be generated, for example, by irradiating the aqueous dispersion with ultrasonic waves to cause cavitation. It is also preferable to stir the aqueous dispersion in which ultrafine bubbles have been generated.

[0215] The time for the treatment with ultra-fine bubbles is preferably 60 seconds or more, more preferably 300 seconds or more, and preferably 20 minutes or less.

[0216] In the coagulation method using an alkali, an alkali such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia can be used. As the ammonia, ammonium bicarbonate or ammonium carbonate is preferred. As the alkali, at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonia is preferred, and sodium hydroxide is more preferred. It is also preferred to stir the aqueous dispersion containing the alkali.

[0217] When the aqueous dispersion containing the fluorine-containing compound having anionic group as the fluorine-containing compound having hydrophilic group is coagulated using alkali, the anionic group of the fluorine-containing compound is converted into salt type, so that the water solubility of the fluorine-containing compound is increased, and therefore, by washing the wet powder obtained by coagulation, there is an advantage that the fluorine-containing compound can be easily removed from the wet powder.The fluorine-containing compound having salt type anionic group that remains in the wet powder after washing is difficult to volatilize, so that it tends to be difficult to remove even by heat treatment of the wet powder.However, if the wet powder is washed with acid before heat treatment, the content of the fluorine-containing compound can be more smoothly reduced.Therefore, after coagulation using alkali, the obtained wet powder is washed with acid, and the washed wet powder is heat treated, which is also one of the preferred embodiments.

[0218] In the coagulation method using acid, organic acid or inorganic acid can be used.As acid, inorganic acid is preferred from the viewpoint that it is difficult to remain during heat treatment, and particularly, at least one selected from the group consisting of nitric acid, sulfuric acid, fuming sulfuric acid, perchloric acid and hydrochloric acid is preferred, and at least one selected from the group consisting of nitric acid, sulfuric acid and hydrochloric acid is more preferred.As the organic acid, succinic acid, oxalic acid, citric acid, trifluoroacetic acid etc. can be mentioned.The amount of acid to be added is not limited, and can be suitably set according to the pH etc. of aqueous dispersion.It is also preferred to stir the aqueous dispersion containing acid.

[0219] In the coagulation method using an oxidizing agent, at least one selected from the group consisting of inorganic acids and their salts can be used. Examples of inorganic acids include nitrous acid, nitric acid, sulfurous acid, sulfuric acid, persulfuric acid, hydrochloric acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hydrofluoric acid, bromic acid, iodic acid, phosphoric acid, boric acid, chromic acid, dichromate, and permanganic acid. Examples of inorganic acid salts include sodium salts, potassium salts, ammonium salts, magnesium salts, calcium salts, aluminum salts, and silver salts. As the oxidizing agent, at least one selected from the group consisting of nitric acid and its salts and perchloric acid and its salts is more preferred, with at least one selected from the group consisting of nitrates and perchlorates being even more preferred, and at least one selected from the group consisting of sodium nitrate, potassium nitrate, ammonium nitrate, and ammonium perchlorate being particularly preferred. Two or more oxidizing agents may be used in combination. For example, an inorganic acid and an inorganic acid salt may be used in combination, or nitric acid and a nitrate (e.g., sodium nitrate, ammonium nitrate, etc.) may be used in combination. It is also preferable to stir the aqueous dispersion containing the oxidizing agent.

[0220] The amount of the oxidizing agent added is preferably 0.01 to 20% by mass, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the non-melt-processible PTFE in the aqueous dispersion. In one embodiment, the oxidizing agent is added to the aqueous dispersion and stirred to coagulate the non-melt-processible PTFE.

[0221] In the coagulation method using an organic solvent, for example, the following organic solvents can be used: alcohol; carboxylic acids such as acetic acid, propionic acid, ethoxyacetic acid, and valeric acid; esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and dimethyl carbonate; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol, and 3-methyl-2-cyclopentenone; aromatic hydrocarbons such as benzene, toluene, and xylene; and ethers such as diethyl ether, tetrahydrofuran, dioxane, diethylene glycol diethyl ether, and 1,2-dimethoxyethane.

[0222] Of these, alcohol is preferred as the organic solvent. The alcohol may be any of a monohydric alcohol, a dihydric alcohol, and a trihydric alcohol. A monohydric alcohol is preferred as the alcohol. The number of carbon atoms in the alcohol is preferably 2 to 7, more preferably 3 or more, more preferably 5 or less, and even more preferably 4 or less. The organic solvent is preferably at least one selected from the group consisting of methanol, 1-propanol, 2-propanol, 2-butanol, and 1-pentanol, more preferably at least one selected from the group consisting of 1-propanol, 2-propanol, 2-butanol, and 1-pentanol, and even more preferably at least one selected from the group consisting of 1-propanol, 2-butanol, and 1-pentanol.

[0223] The amount of organic solvent added is preferably the weight of more than 1.0% by mass relative to the non-melt-processable PTFE in aqueous dispersion.The amount of organic solvent used for coagulation is more preferably more than 5.0% by mass, more preferably more than 10% by mass, particularly preferably more than 20% by mass, and is the amount of weight less than 50 times, more preferably less than 10 times, more preferably less than 5 times.It is also preferred to stir the aqueous dispersion that contains organic solvent.

[0224] In the coagulation method using a radical generator, a water-soluble radical generator can be suitably used.The radical generator can be an organic peroxide, an inorganic peroxide, an organic azo compound, a combination of an oxidizing agent and a reducing agent, and the like, and at least one selected from the group consisting of an inorganic peroxide, an organic peroxide, and a combination of an oxidizing agent and a reducing agent is preferred.In one embodiment, a radical generator is added to the aqueous dispersion, and the aqueous dispersion is heated to the decomposition temperature of the radical generator or higher, thereby coagulating the non-melt-processable PTFE.It is also preferred to stir the aqueous dispersion containing the radical generator.

[0225] The inorganic peroxide is preferably a water-soluble inorganic peroxide. Examples of the inorganic peroxide include hydrogen peroxide, perchlorates, perborates, perphosphates, percarbonates, and persulfates, with persulfates being preferred. The persulfates are preferably at least one selected from the group consisting of ammonium persulfate, sodium persulfate, and potassium persulfate, with ammonium persulfate being more preferred.

[0226] The organic peroxide is preferably a water-soluble organic peroxide, and examples of the organic peroxide include peroxydicarbonates such as disuccinic acid peroxide and diglutaric acid peroxide.

[0227] The radical generator may be a combination of an oxidizing agent and a reducing agent. By using a combination of an oxidizing agent and a reducing agent, radicals can be generated from the radical generator by a redox reaction between the oxidizing agent and the reducing agent, so that the temperature during heat treatment can be lowered.

[0228] Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and cerium ammonium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. It is also preferable to add a copper salt or an iron salt to increase the decomposition rate of the oxidizing agent. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0229] The heating temperature of the aqueous dispersion containing the radical generator is not particularly limited as long as it is equal to or higher than the temperature at which the radical generator decomposes to generate radicals (decomposition temperature), but is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, particularly preferably 50°C or higher, and preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and particularly preferably 90°C or lower.

[0230] (Washing) In the manufacturing method of the present disclosure, the coagulated material produced by the coagulation of the non-melt-processible PTFE is collected to obtain a wet powder, and then the wet powder is washed. The washing may be performed once or twice or more times.

[0231] The cleaning method is preferably at least one selected from the group consisting of a cleaning method by stirring, an ultrasonic cleaning method, a cleaning method using ultrafine bubbles, a cleaning method using an alkali, a cleaning method using an acid, and a cleaning method using a radical generator.

[0232] As will be described later, if heat treatment is carried out at a relatively low temperature, the content of the fluorine-containing compound with hydrophilic group in wet powder cannot be reduced sufficiently, and therefore, the non-melt-processable PTFE that can be extruded under stable extrusion pressure may not be obtained.On the other hand, if heat treatment temperature is too high, although the content of the fluorine-containing compound with hydrophilic group in wet powder can be reduced, the extrusion pressure of the non-melt-processable PTFE that can be obtained becomes too high.By carrying out heat treatment at a relatively low temperature and carrying out washing by the above-mentioned method, it is possible to completely remove the fluorine-containing compound with hydrophilic group and stabilize the low extrusion pressure.Furthermore, by carrying out heat treatment at a relatively low temperature, carrying out coagulation by the above-mentioned method, and carrying out washing by the above-mentioned method, it is possible to completely remove the fluorine-containing compound with hydrophilic group and stabilize the low extrusion pressure more easily and perfectly.

[0233] The temperature when washing the wet powder may be 3 to 95° C. The temperature when washing the wet powder may be 5° C. or higher, or 10° C. or higher. The temperature when washing the wet powder may be 85° C. or lower, 75° C. or lower, or 60° C. or lower.

[0234] In the agitation washing method, the wet powder is placed in water and the water is agitated. Agitation can be performed, for example, using a container equipped with an agitator. It is preferable to wash multiple times. When washing multiple times, it is more preferable to perform the final wash at 30°C or below.

[0235] In ultrasonic cleaning, the wet powder is placed in a liquid and ultrasonic waves are applied to the liquid. The liquid can be water or an alcohol. The alcohol is preferably at least one selected from the group consisting of methanol, 1-propanol, 2-propanol, 2-butanol, and 1-pentanol, and more preferably methanol.

[0236] The ultrasonic output is preferably 100 W or more, more preferably 200 W or more, even more preferably 300 W or more, still more preferably 400 W or more, particularly preferably 500 W or more, and preferably 3000 W or less, more preferably 1000 W or less, and even more preferably 800 W or less.

[0237] The frequency of the ultrasonic waves is preferably 15 kHz or more, more preferably 20 kHz or more, even more preferably 25 kHz or more, still more preferably 30 kHz or more, particularly preferably 40 kHz or more, and preferably 100 kHz or less, more preferably 80 kHz or less, and even more preferably 50 kHz or less.

[0238] The ultrasonic irradiation time is preferably 60 seconds or more, more preferably 300 seconds or more, and preferably 180 minutes or less, more preferably 150 minutes or less, even more preferably 120 minutes or less, and particularly preferably 20 minutes or less.

[0239] Ultrasonic irradiation can be carried out using a commercially available ultrasonic generator, such as a commercially available ultrasonic transmitter (e.g., ultrasonic homogenizer), ultrasonic transmitter, circulating ultrasonic irradiator, ultrasonic vibrator, ultrasonic cleaner, etc.

[0240] Specific methods for irradiating powders and liquids with ultrasonic waves include, for example, a method in which the nozzle of an ultrasonic homogenizer is immersed in the liquid, a method in which a throw-in type ultrasonic vibrator is immersed in a container containing the liquid and irradiated, a method in which a container containing the liquid is introduced into an ultrasonic cleaner that has been previously charged with an aqueous medium or the like and irradiated, a method in which the liquid is introduced into a tank-type ultrasonic cleaner or ultrasonic oscillator and irradiated, and a method in which the liquid is introduced into a tank equipped with a rod-shaped ultrasonic irradiator and irradiated with ultrasonic waves.

[0241] In cleaning methods using ultrafine bubbles, wet powder is added to water to generate ultrafine bubbles. Ultrafine bubbles are bubbles with a diameter of 1 μm or less. Ultrafine bubbles can be generated, for example, by irradiating water with ultrasonic waves to cause cavitation.

[0242] The time for cleaning with ultra-fine bubbles is preferably 60 seconds or more, more preferably 300 seconds or more, and preferably 20 minutes or less.

[0243] In the cleaning method using an alkali, an alkali such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia can be used. As the ammonia, ammonium bicarbonate or ammonium carbonate is preferred. As the alkali, at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonia is preferred, and sodium hydroxide is more preferred.

[0244] When a wet powder containing a fluorine-containing compound having an anionic group as a fluorine-containing compound having a hydrophilic group is washed with an alkali, the anionic group of the fluorine-containing compound is converted to a salt form, thereby increasing the water solubility of the fluorine-containing compound, which has the advantage that the fluorine-containing compound can be easily removed from the wet powder by washing the resulting wet powder. The fluorine-containing compound having a salt form anionic group that remains in the wet powder even after washing is difficult to volatilize and therefore tends to be difficult to remove even by heat treatment of the wet powder. However, if the wet powder is washed with an acid before heat treatment, the content of the fluorine-containing compound can be reduced more smoothly. Therefore, one preferred embodiment is to wash the wet powder with an alkali, then wash the wet powder with an acid, and then heat treat the washed wet powder.

[0245] In the acid-based cleaning method, organic or inorganic acids can be used, but inorganic acids are preferred because they are less likely to remain after heat treatment. In particular, at least one acid selected from the group consisting of nitric acid, sulfuric acid, fuming sulfuric acid, perchloric acid, and hydrochloric acid is preferred, and at least one acid selected from the group consisting of nitric acid, sulfuric acid, and hydrochloric acid is more preferred. Examples of the organic acid include succinic acid, oxalic acid, citric acid, and trifluoroacetic acid. The amount of acid added is not limited and may be appropriately set depending on the pH of the water containing the powder. In one embodiment, cleaning is performed by adding the wet powder and acid to water and stirring the water.

[0246] In a cleaning method using a radical generator, a water-soluble radical generator can be suitably used. Examples of the radical generator include organic peroxides, inorganic peroxides, organic azo compounds, and combinations of oxidizing agents and reducing agents. At least one selected from the group consisting of inorganic peroxides, organic peroxides, and combinations of oxidizing agents and reducing agents is preferred. In one embodiment, cleaning is performed by adding the wet powder and the radical generator to water, heating the water to the decomposition temperature of the radical generator or higher, and stirring.

[0247] As the radical generator used in the cleaning, a radical generator that can be used in a coagulation method using a radical generator can be used.

[0248] The heating temperature of the water is not particularly limited as long as it is equal to or higher than the temperature at which the radical generator decomposes to generate radicals (decomposition temperature), but is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, particularly preferably 50°C or higher, and preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and particularly preferably 90°C or lower.

[0249] (Heat Treatment) In the manufacturing method of the present disclosure, after the wet powder is washed, the washed wet powder is subjected to heat treatment.

[0250] The moisture content of the wet powder to be heat treated is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 150% by mass or less, and more preferably 100% by mass or less, relative to the wet powder.

[0251] The heat treatment temperature is preferably 10 to 280°C. The heat treatment temperature may be 100°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, or 160°C or higher. The heat treatment temperature may be 230°C or lower, 210°C or lower, 200°C or lower, 190°C or lower, 185°C or lower, or 180°C or lower. In the manufacturing method of the present disclosure, heat treatment is preferably performed at a relatively low temperature. By performing heat treatment at a relatively low temperature, the content of fluorine-containing compounds having hydrophilic groups is reduced, making it possible to produce non-melt-processable PTFE that can be extruded at low and stable extrusion pressures. The heat treatment temperature may be 170°C or higher, 175°C or higher, 180°C or higher, 185°C or higher, 190°C or higher, 195°C or higher, 200°C or higher, 205°C or higher, 210°C or higher, or 220°C or higher. The temperature of the heat treatment may be 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, or 250°C or less.

[0252] The heat treatment time is preferably 5 to 3,000 minutes. The heat treatment time may be 10 minutes or more, 15 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 100 minutes or more, 150 minutes or more, or 200 minutes or more. The heat treatment time may be 2,500 minutes or less, 2,000 minutes or less, or 1,500 minutes or less. In the manufacturing method of the present disclosure, it is preferable to perform heat treatment at a relatively low temperature for a relatively long time. The heat treatment time may be 5 minutes or more, 10 minutes or more, 15 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 60 minutes or more, or 80 minutes or more, or may be 300 minutes or less, 200 minutes or less, 170 minutes or less, 140 minutes or less, 110 minutes or less, or 80 minutes or less. In the manufacturing method of the present disclosure, when heat treatment is performed at a relatively high temperature, it is preferable to shorten the heat treatment time.

[0253] The heat treatment can be carried out in air. Alternatively, if the heat treatment is carried out in an oxygen-rich gas or an ozone-containing gas, the reduction in the content of the fluorine-containing compound having a hydrophilic group can be further promoted.

[0254] As the heat treatment method, it is preferable to contact the wet powder with hot air, or heat the wet powder in the presence of water vapor.If heat treatment is carried out at a relatively low temperature, the content of the fluorine-containing compound with hydrophilic groups in the wet powder cannot be reduced sufficiently, and therefore, it may not be possible to obtain the non-melt-processable PTFE that can be extruded under stable extrusion pressure.On the other hand, if the heat treatment temperature is too high, the content of the fluorine-containing compound with hydrophilic groups in the wet powder can be reduced, but if the heat treatment time is long, the extrusion pressure of the non-melt-processable PTFE obtained tends to be too high.In addition to heat treatment of the wet powder within the above temperature range, by heat treatment with hot air or water vapor, and by appropriately adjusting the heat treatment time, it is possible to completely remove the fluorine-containing compound with hydrophilic groups and stabilize the low extrusion pressure.

[0255] The heat treatment using hot air can be carried out by blowing hot air onto the moist powder. In one embodiment, the moist powder is placed in a container that is open at the top and has air permeability at the bottom and / or sides, and hot air is blown onto the placed moist powder. In another embodiment, the moist powder is placed in a heating furnace, and hot air is circulated within the heating furnace, thereby blowing hot air onto the placed moist powder. In another embodiment, the moist powder is placed in a heating furnace, and hot air is circulated within the heating furnace while hot air is being discharged from the heating furnace, thereby blowing hot air onto the placed moist powder.

[0256] The velocity of the hot air blown onto the moist powder may be 0.01 m / s or more, 0.03 m / s or more, 0.05 m / s or more, 0.10 m / s or more, 0.20 m / s or more, 0.30 m / s or more, 0.40 m / s or more, 0.50 m / s or more, or 0.60 m / s or more. The velocity of the hot air blown onto the moist powder may be 10 m / s or less, 5.0 m / s or less, 3.0 m / s or less, 2.0 m / s or less, or 1.0 m / s or less.

[0257] In one embodiment, a wet powder layer is formed by arranging the wet powder so that when the hot air passes from the surface onto which the hot air is blown toward the surface opposite to the surface onto which the hot air is blown, the air pressure on the surface onto which the hot air is blown is higher than the air pressure on the surface opposite to the surface onto which the hot air is blown; then, the hot air is blown onto the wet powder layer, the hot air is introduced into the wet powder layer from the surface onto which the hot air was blown, and the hot air is exhausted from the surface opposite to the surface onto which the hot air was blown, thereby heat-treating the wet powder (sometimes referred to as "air drying treatment" in the present disclosure).

[0258] According to this method, the hot air passes through the voids in the wet powder layer over a certain period of time, so that the hot air comes into sufficient contact with each particle in the wet powder layer, and the wet powder is uniformly heated. Therefore, a homogeneous fluoropolymer powder can be obtained, and the content of the fluorine-containing compound having a hydrophilic group is reduced, making it possible to produce non-melt-processible polytetrafluoroethylene that can be extruded at a lower and more stable extrusion pressure.

[0259] In the through-air drying process, the particle size of the wet powder, the thickness of the wet powder layer, and the velocity of the hot air are appropriately adjusted so that the hot air passes from the surface onto which the hot air is blown toward the surface opposite to the surface onto which the hot air is blown. For example, when hot air is blown onto the upper surface of the wet powder layer, the hot air may be discharged from the side of the wet powder layer, but since the side of the wet powder layer does not face the surface onto which the hot air is blown (the upper surface of the wet powder layer), it does not correspond to the surface opposite to the surface onto which the hot air is blown.

[0260] The through-air drying process can be carried out, for example, by placing the wet powder in a container with an open top and an air-permeable bottom to form a wet powder layer, and then blowing hot air onto the top surface of the wet powder layer and discharging the hot air from the bottom, or by blowing hot air onto the bottom surface of the wet powder layer and discharging the hot air from the top. In this case, the air pressure on the surface onto which the hot air is blown and the air pressure on the surface opposite to the surface onto which the hot air is blown (the surface through which the hot air passes) can be adjusted by appropriately adjusting the particle size of the wet powder, the thickness of the wet powder layer, and the speed of the hot air. The smaller the particle size of the wet powder, the greater the air pressure difference tends to be. The thicker the wet powder layer, the greater the air pressure difference tends to be. The air pressure difference between the surface onto which the hot air is blown and the surface opposite to the surface onto which the hot air is blown (the surface through which the hot air passes) is preferably 10 Pa or more.

[0261] The treatment time in the aeration drying treatment may be 5 minutes or more, 10 minutes or more, 15 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 60 minutes or more, or 80 minutes or more, and may be 300 minutes or less, 200 minutes or less, 170 minutes or less, 140 minutes or less, 110 minutes or less, or 80 minutes or less.

[0262] The temperature of the hot air blown onto the wet powder is as described above for the heat treatment temperature. The treatment temperature (hot air temperature) in the through-drying treatment may be greater than 150°C, 155°C or higher, 160°C or higher, 165°C or higher, 170°C or higher, 175°C or higher, 180°C or higher, 185°C or higher, 190°C or higher, 195°C or higher, 200°C or higher, 205°C or higher, 210°C or higher, or 220°C or higher. The treatment temperature (hot air temperature) in the through-drying treatment may be 260°C or lower, 235°C or lower, 230°C or lower, 225°C or lower, 220°C or lower, 215°C or lower, or 210°C or lower. The treatment temperature (hot air temperature) in the through-drying treatment may be 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, or 220°C or higher. The treatment temperature (hot air temperature) in the air drying treatment may be 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, or 250°C or less.

[0263] In the through-air drying treatment, for example, the treatment temperature (hot air temperature) can be set to more than 250°C and not more than 280°C, and the treatment time can be set to 50 minutes or less. Also, in the through-air drying treatment, for example, the treatment temperature (hot air temperature) can be set to more than 200°C and not more than 250°C, and the treatment time can be set to 100 minutes or less. Also, in the through-air drying treatment, for example, the treatment temperature (hot air temperature) can be set to more than 150°C and not more than 200°C, and the treatment time can be set to 200 minutes or less.

[0264] The hot air velocity in the ventilation drying treatment may be 0.01 m / s or more, 0.03 m / s or more, 0.05 m / s or more, 0.10 m / s or more, 0.20 m / s or more, 0.30 m / s or more, 0.40 m / s or more, 0.50 m / s or more, or 0.60 m / s or more, and may be 10 m / s or less, 5.0 m / s or less, 3.0 m / s or less, 2.0 m / s or less, or 1.0 m / s or less.

[0265] When a heating furnace such as an electric furnace is used in the heat treatment process, it is possible to adjust the amount of gas, air, or steam supplied into the heating furnace, the amount of gas, air, or steam circulated inside the heating furnace, and the amount of gas, air, or steam exhausted outside the heating furnace. Gas and air are sometimes collectively referred to as hot air.

[0266] The proportion of the amount of gas, air, or steam discharged from the heating furnace relative to the amount circulating in the heating furnace may be 3% by volume or more, 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, or 50% by volume or more, and may be 95% by volume or less, 80% by volume or less, or 75% by volume or less.

[0267] The proportion of the amount of gas, air or steam discharged from the heating furnace in the aeration drying treatment may be 3% by volume or more, 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more or 50% by volume or more, and may be 95% by volume or less, 80% by volume or less, 75% by volume or less, 50% by volume or less, 40% by volume or less or 30% by volume or less, relative to the amount circulating in the heating furnace. The higher the proportion of the amount of gas, air or steam discharged, the higher the removal efficiency of the fluorine-containing compound having a hydrophilic group tends to be, and the lower the proportion of the amount of gas, air or steam discharged, the easier it is to control the temperature in the heating furnace and the lower the costs tend to be.

[0268] The ratio of the amount of gas, air, or steam discharged from the heating furnace in the hot air circulation drying treatment to the amount circulating in the heating furnace may be 10% by volume or more, 20% by volume or more, or 30% by volume or more, and may be 95% by volume or less, 80% by volume or less, or 75% by volume or less.

[0269] When the heat treatment temperature exceeds 200°C, the ratio of the amount of gas, air, or steam discharged from the heating furnace to the amount circulating in the heating furnace may be 3% by volume or more, 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, or 50% by volume or more, and may be 95% by volume or less, 80% by volume or less, 75% by volume or less, 50% by volume or less, 40% by volume or less, or 30% by volume or less.

[0270] When the heat treatment temperature is 200°C or less, the ratio of the amount of gas, air, or steam discharged from the heating furnace to the amount circulating in the heating furnace may be 10% by volume or more, 20% by volume or more, or 30% by volume or more, and may be 95% by volume or less, 80% by volume or less, or 75% by volume or less.

[0271] In one embodiment, a wet powder layer is formed by arranging the wet powder so that when hot air is blown, the hot air is not discharged from the surface opposite the surface onto which the hot air is blown, or so that when hot air passes from the surface onto which the hot air is blown towards the surface opposite the surface onto which the hot air is blown, the air pressure on the surface onto which the hot air is blown is the same as the air pressure on the surface opposite the surface onto which the hot air is blown; then, hot air is blown onto the wet powder layer to heat-treat the wet powder (sometimes referred to as "hot air circulation drying treatment" in the present disclosure).

[0272] In the hot air circulation drying process, hot air may pass through the wet powder layer, but the hot air circulation drying process differs from the ventilation drying process in that the air pressure on the surface onto which the hot air is blown is the same as the air pressure on the surface opposite to the surface onto which the hot air is blown (the surface through which the hot air passes).

[0273] The hot air circulation drying process can be carried out, for example, by placing the wet powder on a non-permeable tray to form a wet powder layer and blowing hot air onto the top surface of the wet powder layer, or by placing the wet powder in a container with an open top and breathable bottom and / or sides to form a wet powder layer and blowing hot air onto the wet powder layer so that the hot air does not pass through the wet powder layer or so that the hot air easily passes through it. When a container with an open top and breathable bottom and / or sides is used, the particle size of the wet powder, the thickness of the wet powder layer in the direction in which the hot air passes, and the speed of the hot air can be appropriately adjusted to prevent the hot air from being discharged from the surface opposite the surface onto which the hot air is blown, or to allow the hot air to easily pass through the wet powder layer so that the air pressure on the surface onto which the hot air is blown is the same as the air pressure on the surface opposite the surface onto which the hot air is blown.

[0274] For example, if a wet powder layer is formed by spreading an extremely thin layer of wet powder in a container that is open on the top and has a breathable bottom, and hot air is blown onto the top surface of the wet powder layer, the hot air is easily expelled from the bottom surface, and there is no loss of pressure due to the hot air passing through the wet powder layer. Therefore, the air pressure on the surface onto which the hot air is blown becomes the same as the air pressure on the surface opposite to the surface onto which the hot air is blown (the surface from which the hot air escapes). The difference in air pressure at this time is less than 10 Pa.

[0275] The treatment time in the hot air circulation drying treatment may be 120 minutes or more, 180 minutes or more, 240 minutes or more, 300 minutes or more, 360 minutes or more, or 420 minutes or more, and may be 1500 minutes or less or 1200 minutes or less. In the hot air circulation drying treatment, the ratio of the amount of gas, air, or steam discharged to the amount circulating in the heating furnace is usually 0% by volume.

[0276] The temperature of the hot air blown onto the wet powder is as described above for the temperature of the heat treatment. The treatment temperature (temperature of the hot air) in the hot air circulation drying treatment may be higher than 150°C, 155°C or higher, 160°C or higher, 165°C or higher, 170°C or higher, 175°C or higher, or 180°C or higher, or may be 250°C or lower, 235°C or lower, 230°C or lower, 225°C or lower, 220°C or lower, 215°C or lower, 210°C or lower, 205°C or lower, 200°C or lower, 195°C or lower, 190°C or lower, or 185°C or lower.

[0277] The wind speed of the hot air in the hot air circulation drying treatment may be 0.10 m / s or more, 0.50 m / s or more, 1.0 m / s or more, 1.5 m / s or more, 2.0 m / s or more, 2.5 m / s or more, or 3.0 m / s or more, and may be 10 m / s or less or 5.0 m / s or less.

[0278] The heat treatment can be carried out in a state where the wet powder is placed in a container that is open at the top and has air permeability at the bottom and / or sides. The container with air permeability at the bottom and / or sides may be any container that can withstand the heat treatment temperature, but is preferably made of a metal such as stainless steel.

[0279] As a container having an open top and breathable bottom and / or sides, a tray (bat) having breathable bottom and / or sides is preferred, and a tray (mesh tray) having a mesh bottom and / or sides is more preferred. The mesh is preferably either a woven mesh or a punched metal. When the mesh is a woven mesh, the weaving method may be, for example, a plain weave, a twill weave, a plain tatami weave, or a twill tatami weave. Furthermore, a method of combining a mesh with a woven fabric may also be used.

[0280] The fabric may be in the form of a perforated pan liner used in tray drying in an oven, or a continuous belt operated in an oven, where the process steps are continuous, i.e., the agglomerates are continuously placed at one end of the belt path and purified PTFE fines are continuously removed from the opposite end of the belt path, where the shallow bed of agglomerates is continuously exposed to heated air as it moves along the path from one end to the other. In either form, the fabric is the immediate support for the agglomerates and can be reused for additional polymer purification.

[0281] The fabric may be of any construction, such as knit, spunbonded, or woven, that provides the required dimensional integrity depending on the fabric configuration used. In the case of knit or woven constructions, the fabric is made from yarns, and in the case of spunbonded constructions, it is generally made from fibers. The yarns or fibers that make up the fabric, as the case may be, provide openings between the yarns or fibers that allow the heated air to pass through during the refining step but retain the PTFE agglomerates / fines particles above (i.e., do not allow the PTFE fines to pass through). The openings in the fabric must be small enough to retain the PTFE fines, but also large enough to allow the heated air and evaporated contaminants to pass through at a rate sufficient to allow refining with a reasonable hot air contact time.

[0282] The mesh size is preferably 2000 μm or less (ASTM standard 10 mesh or more), more preferably 595 μm or less (30 mesh or more), even more preferably 297 μm or less (50 mesh or more), even more preferably 177 μm or less (80 mesh or more), particularly preferably 149 μm or less (100 mesh or more), and particularly preferably 74 μm or less (200 mesh or more). Also, 25 μm or more (500 mesh or less) is preferred.

[0283] When the mesh is a punched metal, the porosity is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more, and is preferably 95% or less.

[0284] The amount of wet powder placed is 10 g / cm ２ Preferably, it is 8 g / cm or less. ２ More preferably, it is 5 g / cm or less. ２ More preferably, it is 3 g / cm or less. ２ It is particularly preferable that the density is 0.01 g / cm or less. ２ It is preferable that the density is 0.05 g / cm or more. ２ More preferably, it is 0.1 g / cm or more. ２ More preferably, it is equal to or greater than this.

[0285] The heat treatment using water vapor can be carried out by blowing high-temperature steam onto the wet powder. In one embodiment, the wet powder is placed in a container that is open at the top and has air permeability at the bottom and / or sides, and high-temperature steam is blown onto the wet powder.

[0286] The heat treatment using water vapor can be carried out under normal pressure or under pressure. The pressure when the heat treatment using water vapor is carried out may be 0.10 to 4.0 MPa. The pressure when the heat treatment is carried out under pressure may be more than 0.10 MPa and may be 0.2 MPa or less.

[0287] The heat treatment using water vapor may be carried out under reduced pressure. The pressure of the heat treatment carried out under reduced pressure may be less than 0.10 MPa or 0.09 MPa or less, or may be 0.01 MPa or more.

[0288] The treatment time in the heat treatment using water vapor may be 5 minutes or more, 10 minutes or more, 15 minutes or more, 30 minutes or more, 40 minutes or more, 1 hour or more, 3 hours or more, 5 hours or more, or 7 hours or more, and may be 10 hours or less, 8 hours or less, 6 hours or less, or 4 hours or less.

[0289] The temperature of the steam sprayed onto the wet powder is as described above for the heat treatment temperature. The treatment temperature (temperature of the steam) in the heat treatment using steam may be 100°C or higher, 120°C or higher, 140°C or higher, 160°C or higher, or 170°C or higher, and may be 350°C or lower, 300°C or lower, 250°C or lower, 230°C or lower, 210°C or lower, 205°C or lower, 200°C or lower, 195°C or lower, 190°C or lower, or 185°C or lower.

[0290] The amount of heating steam generated in the heat treatment using water vapor may be 1 kg / h or more, 3 kg / h or more, 5 kg / h or more, or 10 kg / h or more, and may be 500 kg / h or less, 300 kg / h or less, 100 kg / h or less, 50 kg / h or less, or 30 kg / h or less.

[0291] The heat treatment can be carried out using an electric furnace or a steam furnace. For example, the heat treatment can be carried out using an electric furnace such as a parallel flow box-type electric furnace, a vented box-type electric furnace, a vented conveyor-type electric furnace, a tunnel electric furnace, a band electric furnace, a turbo vertical electric furnace, a radiant conveyor-type electric furnace, a fluidized bed electric furnace, a vented rotary electric furnace, a channeled stirring electric furnace, a multi-stage disk electric furnace, a vacuum electric furnace, a cylindrical electric furnace, a vibration electric furnace, a freezing electric furnace, a drum electric furnace, a channeled electric furnace, an inverted cone-type electric furnace, an extrusion electric furnace, a steam-heated tube bundle rotary electric furnace, an infrared electric furnace, a superheated steam electric furnace, a high-frequency electric furnace, a microwave electric furnace, a stirring electric furnace, an airflow electric furnace, or a hot air circulation electric furnace, or a steam furnace corresponding to the above (an apparatus in which the term "electric furnace" in the apparatus name of each of the above electric furnaces is replaced with "steam furnace").

[0292] It is also preferred to dry the wet powder by heat treatment. When the wet powder is heated under normal pressure or under pressure in the presence of water vapor, the wet powder is usually not dried sufficiently, so it is preferred to dry the wet powder after the heat treatment to obtain a non-melt-processable PTFE powder.

[0293] By heat treating the wet powder, or by heat treating and drying, it is usually possible to obtain a non-melt-processible PTFE powder having a moisture content of 0.01% by mass or less, or 0.005% by mass or less, based on the wet powder.

[0294] After the wet powder has been heat-treated, the heat-treated non-melt-processible PTFE powder may be washed again by the same washing method as the above-mentioned washing method for the wet powder.

[0295] 2. Non-melt-processible PTFE powder By using the manufacturing method of the present disclosure, it is possible to manufacture non-melt-processible PTFE that has a reduced content of a fluorine-containing compound having a hydrophilic group and can be extruded at a low and stable extrusion pressure. The present disclosure also relates to a non-melt-processible PTFE powder that contains a reduced content of a fluorine-containing compound having a hydrophilic group and that can be extruded at a low extrusion pressure measured at a reduction ratio of 100.

[0296] (Extrusion Pressure) The extrusion pressure of the non-melt-processible PTFE powder at a reduction ratio (RR) of 100 may be 5 MPa or more, 10 MPa or more, or 12 MPa or more. The extrusion pressure at RR 100 may also be 50 MPa or less, 40 MPa or less, 30 MPa or less, 25 MPa or less, 23 MPa or less, 21 MPa or less, or 20 MPa or less, in order to improve processability. In the present disclosure, a non-melt-processible PTFE powder whose extrusion pressure cannot be measured because the pressure does not reach equilibrium when measuring the extrusion pressure is considered to be a non-melt-processible PTFE powder that does not have an extrusion pressure within the above-mentioned range.

[0297] The extrusion pressure of the non-melt-processible PTFE powder in RR1600 may be 20 MPa or more, 25 MPa or more, or 30 MPa or more. In terms of improving processability, the extrusion pressure in RR1600 may also be 80 MPa or less, 70 MPa or less, 60 MPa or less, or 50 MPa or less.

[0298] The extrusion pressure at RR100 is measured by the following method. 50 g of non-melt-processible PTFE powder is mixed with 10.25 g of hydrocarbon oil (trade name: Isopar G, manufactured by Exxon Corporation) as an extrusion aid in a polyethylene container for 3 minutes. The mixture is filled into the cylinder of an extruder at room temperature (25±2°C), and a load of 0.47 MPa is applied to the piston inserted in the cylinder and maintained for 1 minute. The mixture is then extruded through the orifice at a ram speed of 18 mm / min. The ratio of the cross-sectional area of ​​the cylinder to the cross-sectional area of ​​the orifice is 100. In the latter half of the extrusion operation, the load (N) when the pressure reaches equilibrium is divided by the cross-sectional area of ​​the cylinder to obtain the extrusion pressure (MPa).

[0299] The extrusion pressure at RR1600 is measured by the following method. 50 g of non-melt-processible PTFE powder is mixed with 10.25 g of hydrocarbon oil (trade name: Isopar G, manufactured by Exxon Corporation) as an extrusion aid in a polyethylene container for 3 minutes. The mixture is filled into the cylinder of an extruder at room temperature (25±2°C), and a load of 1.2 MPa is applied to the piston inserted in the cylinder and maintained for 1 minute. The mixture is then extruded through the orifice at a ram speed of 18 mm / min. The ratio of the cross-sectional area of ​​the cylinder to the cross-sectional area of ​​the orifice is 1600. In the latter half of the extrusion operation, the load (N) when the pressure reaches equilibrium is divided by the cross-sectional area of ​​the cylinder to obtain the extrusion pressure (MPa).

[0300] In one embodiment, the non-melt-processible PTFE powder exhibits little or no increase in extrusion pressure even when repeatedly extruded using the same extruder.For example, when the non-melt-processible PTFE powder is paste-extruded using an extruder equipped with a thoroughly cleaned extrusion die to obtain a 5 m long bead multiple times, the increase in the paste extrusion pressure in the fourth extrusion can be kept to 3.0% or less compared to the paste extrusion pressure in the first extrusion.The increase in the paste extrusion pressure is preferably 2.5% or less, more preferably 2.0% or less.

[0301] The paste extrusion pressure is the extrusion pressure at a reduction ratio of 100 when a mixture is prepared by adding 20.5 g parts by mass of hydrocarbon oil (trade name: Isopar G (registered trademark), manufactured by Exxon Corporation) to 100 parts by mass of non-melt-processible PTFE powder and extruding the mixture using an extruder at 25° C. The rate of increase in paste extrusion pressure can be found as the ratio of the difference between the paste extrusion pressure in the fourth molding and the paste extrusion pressure in the first molding to the paste extrusion pressure in the first molding.

[0302] In one embodiment, the non-melt-processible PTFE powder exhibits a small coefficient of variation in extrusion pressure. The coefficient of variation in extrusion pressure is an index showing extrusion stability when the non-melt-processible PTFE powder is paste extrusion processed. In paste extrusion pressure measurement, the coefficient of variation can be expressed as: the difference between the maximum and minimum values ​​of the paste extrusion pressure in the latter half of the extrusion operation; the ratio of the difference between the maximum and minimum values ​​to the average value of the paste extrusion pressure in the latter half of the extrusion operation; the variance or standard deviation of the paste extrusion pressure in the latter half of the extrusion operation; the ratio of the standard deviation to the average value of the paste extrusion pressure in the latter half of the extrusion operation; the difference between the maximum and minimum values ​​of the extrusion pressure when an equilibrium state is reached in the latter half of the extrusion operation; the ratio of the difference between the maximum and minimum values ​​to the average value of the paste extrusion pressure when an equilibrium state is reached in the latter half of the extrusion operation; the variance or standard deviation of the paste extrusion pressure when an equilibrium state is reached in the latter half of the extrusion operation; or the ratio of the standard deviation to the average value of the paste extrusion pressure when an equilibrium state is reached in the latter half of the extrusion operation.

[0303] The coefficient of variation of the extrusion pressure of RR100 of the non-melt-processible PTFE powder may be 0.20 or less, 0.15 or less, 0.10 or less, 0.050 or less, or 0.030 or less.

[0304] The coefficient of variation of the paste extrusion pressure is measured by the following method. In the above-mentioned measurement of the extrusion pressure for RR100, the extrusion pressure of the paste extrusion is measured in the latter half of the extrusion operation, and the coefficient of variation of the extrusion pressure for RR100 is calculated from the average value and standard deviation of the extrusion pressure. (Coefficient of variation of the extrusion pressure for RR100) = (Standard deviation of the extrusion pressure for RR100) / (Average value of the extrusion pressure for RR100)

[0305] The coefficient of variation of the extrusion pressure of RR1600 of the non-melt-processible PTFE powder may be 0.10 or less, 0.050 or less, 0.030 or less, or 0.020 or less.

[0306] The coefficient of variation of the paste extrusion pressure is measured by the following method. In the above-mentioned measurement of the extrusion pressure for RR1600, the extrusion pressure of the paste extrusion is measured in the latter half of the extrusion operation, and the coefficient of variation of the extrusion pressure for RR1600 is calculated from the average value and standard deviation of the extrusion pressure. (Coefficient of variation of the extrusion pressure for RR1600) = (Standard deviation of the extrusion pressure for RR1600) / (Average value of the extrusion pressure for RR1600)

[0307] The non-melt-processible PTFE powder can be suitably used as a molding material used to obtain molded articles by extrusion molding, particularly as a molding material used to obtain molded articles by paste extrusion molding.

[0308] (Fluorine-containing compound having hydrophilic group) The content of the fluorine-containing compound having a hydrophilic group in the non-melt-processable PTFE powder may be more than 0 mass ppb and less than 100 mass ppb relative to the non-melt-processable PTFE powder. The content of the fluorine-containing compound having a hydrophilic group in the non-melt-processable PTFE powder may be 90 mass ppb or less, 80 mass ppb or less, 70 mass ppb or less, 60 mass ppb or less, 50 mass ppb or less, 25 mass ppb or less, 20 mass ppb or less, 10 mass ppb or less, 5 mass ppb or less, 3 mass ppb or less, or 1 mass ppb or less, or may be more than 0 mass ppb. The content of the fluorine-containing compound having a hydrophilic group is most preferably less than the detection limit when measured by liquid chromatography mass spectrometry (LC / MS).

[0309] The hydrophilic group may be an anionic group, an acid group, or an acid-base group. Examples of the hydrophilic group include -NH ２ , -PO ３ M, -OPO ３ M, -SO ３ M, -OSO ３ M, -COOM (in each formula, M is H, a metal atom, NR ７ｙ ４, optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｙ are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring.) Among the above hydrophilic groups, -PO ３ M, -OPO ３ M, -SO ３ M, -OSO ３ M or -COOM is preferred, and -SO ３ M or -COOM is more preferred, and -COOM is even more preferred. ７ｙ The organic group in R is preferably an alkyl group. ７ｙ 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 are alkyl groups of the formula:

[0310] The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), with Na, K, or Li being preferred.

[0311] Examples of the fluorine-containing compound having a hydrophilic group include those exemplified above as the fluorine-containing surfactant. Typical compounds as the fluorine-containing surfactant are those having a molecular weight of 1000 g / mol or less, preferably 800 g / mol or less.

[0312] In one embodiment of the non-melt-processible PTFE powder, the powder is substantially free of a compound represented by the following general formula (1) as a fluorine-containing compound having a hydrophilic group: － ] ｉ M ｉ＋ (Wherein, X represents H, Cl, Br, F or I; Rf represents a linear or branched partially or fully fluorinated aliphatic group, or a linear or branched partially or fully fluorinated aliphatic group interrupted by at least one oxygen atom; A － is an acid group, M ｉ＋ represents a cation having a valence i, where i is an integer from 1 to 3.

[0313] In one embodiment of the non-melt-processible PTFE powder, the powder is substantially free of a compound represented by the following general formula (2) as a fluorine-containing compound having a hydrophilic group. ｎ－１ F ２ｎ－１ COO － ]M ＋ (wherein n is an integer of 9 to 14, M ＋ represents a cation.)

[0314] The compound represented by general formula (2) (perfluoroalkanoic acid) is known to be formed during polymerization when perfluoroalkyl vinyl ether or the like is used as a modified monomer (see WO 2019 / 161153).

[0315] In one embodiment of the non-melt-processible PTFE powder, the powder is substantially free of a compound represented by the following general formula (3) as a fluorine-containing compound having a hydrophilic group. １ -O-L-CO ２ － ]M ＋ (In the formula, R １ represents a linear or branched partially or fully fluorinated aliphatic group, or a linear or branched partially or fully fluorinated aliphatic group interrupted by at least one oxygen atom; L represents a linear or branched non-fluorinated, partially fluorinated or fully fluorinated alkylene group; M represents a linear or branched non-fluorinated, partially fluorinated or fully fluorinated alkylene group; ＋ represents a cation.)

[0316] In one embodiment of the non-melt-processible PTFE powder, the fluorine-containing compound having a hydrophilic group is substantially free of a compound represented by general formula (4): General formula (4): [H—(CF ２ ) ｍ－１ CO ２ － ]M ＋ (wherein m is an integer of 4 to 20, M ＋ represents a cation.)

[0317] In the present disclosure, "substantially free of any of the compounds represented by general formulas (1) to (4)" means that the content of any of the compounds represented by general formulas (1) to (4) in the non-melt-processible PTFE powder is less than 100 ppb by mass. The content of any of the compounds represented by general formulas (1) to (4) in the fluoropolymer may be 90 ppb by mass or less, 80 ppb by mass or less, 70 ppb by mass or less, 60 ppb by mass or less, 50 ppb by mass or less, 25 ppb by mass or less, 10 ppb by mass or less, 5 ppb by mass or less, or 1 ppb by mass or less, or may be greater than 0 ppb by mass. Most preferably, the content is below the detection limit when measured by liquid chromatography mass spectrometry (LC / MS).

[0318] In one embodiment, the non-melt-processible PTFE powder contains any of the compounds represented by the following general formula (4), and the content of one or more of the compounds represented by the general formula (4) is less than 100 ppb by mass relative to the non-melt-processible PTFE powder. ２ ) ｍ－１ CO ２ － ]M ＋ (wherein m is an integer of 4 to 20, M ＋ represents a cation.)

[0319] The content of one or more of the compounds represented by general formula (4) may be 90 mass ppb or less, 80 mass ppb or less, 70 mass ppb or less, 60 mass ppb or less, 50 mass ppb or less, 25 mass ppb or less, 10 mass ppb or less, 5 mass ppb or less, or 1 mass ppb or less, relative to the non-melt-processible PTFE powder, or may be more than 0 mass ppb. The above content is most preferably below the detection limit when measured by liquid chromatography mass spectrometry (LC / MS).

[0320] In one embodiment, the non-melt-processible PTFE powder contains any of the compounds represented by the following general formula (4), and the total content of the compounds represented by the general formula (4) is less than 100 ppb by mass relative to the non-melt-processible PTFE powder. ２ ) ｍ－１ CO２ － ]M ＋ (wherein m is an integer of 4 to 20, M ＋ represents a cation.)

[0321] The total content of the compounds represented by general formula (4) may be 90 mass ppb or less, 80 mass ppb or less, 70 mass ppb or less, 60 mass ppb or less, 50 mass ppb or less, 25 mass ppb or less, 10 mass ppb or less, 5 mass ppb or less, or 1 mass ppb or less, or may be more than 0 mass ppb, relative to the non-melt-processible PTFE powder. The above content is most preferably below the detection limit when measured by liquid chromatography mass spectrometry (LC / MS).

[0322] In one embodiment, the non-melt-processible PTFE powder contains compounds represented by the following general formula (5), and the total content of the compounds represented by general formula (5) is less than 100 ppb by mass relative to the non-melt-processible PTFE powder. ２ ) ｍ－１ CO ２ － ]M ＋ (wherein m is 12 or 14, M ＋ represents a cation.)

[0323] The total content of the compounds represented by general formula (5) may be 90 mass ppb or less, 80 mass ppb or less, 70 mass ppb or less, 60 mass ppb or less, 50 mass ppb or less, 25 mass ppb or less, 10 mass ppb or less, 5 mass ppb or less, or 1 mass ppb or less, or may be more than 0 mass ppb, relative to the non-melt-processible PTFE powder. The above content is most preferably below the detection limit when measured by liquid chromatography mass spectrometry (LC / MS).

[0324] The content of the fluorine-containing compound having a hydrophilic group in the non-melt-processible PTFE powder can be quantified by known methods. For example, it can be quantified by LC / MS analysis. First, methanol is added to the non-melt-processible PTFE powder, extraction is performed, and the resulting extract is analyzed by LC / MS. To further improve the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. The resulting extract is appropriately concentrated with a nitrogen purge, and the fluorine-containing compound having a hydrophilic group in the concentrated extract is measured by LC / MS. Molecular weight information is extracted from the obtained LC / MS spectrum, and its agreement with the structural formula of the candidate fluorine-containing compound having a hydrophilic group is confirmed. Then, aqueous solutions containing five or more levels of the confirmed fluorine-containing compound having a hydrophilic group are prepared, and LC / MS analysis of the aqueous solutions with each content is performed. The relationship between the content and the area area relative to the content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area area of ​​the LC / MS chromatogram of the fluorine-containing compound having a hydrophilic group in the extract can be converted to the content of the fluorine-containing compound having a hydrophilic group. The resulting extract can be concentrated by purging with nitrogen, which allows the lower limit of quantitation of the measurement method to be lowered.

[0325] (Polymer Constitution) The non-melt-processible PTFE powder may be what is called "fine powder."

[0326] By non-melt processable is meant that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point according to ASTM D 1238 and D 2116.

[0327] Non-melt-processible PTFE powders usually have fibrillating properties. The presence or absence of fibrillating properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," which is a powder made from a TFE polymer. Paste extrusion is usually possible because high molecular weight PTFE has fibrillating properties. If the unsintered molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it breaks when pulled at 0% elongation, it can be considered to have no fibrillating properties.

[0328] The standard specific gravity (SSG) of the non-melt-processible PTFE powder is preferably 2.130 to 2.280. The standard specific gravity is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895-89.

[0329] The non-melt-processible PTFE powder preferably has a peak temperature of 333 to 347° C., more preferably 335 to 345° C. The peak temperature can be specified as the temperature corresponding to the maximum value appearing 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.

[0330] The thermal instability index (TII) of the non-melt-processible PTFE powder is preferably 10 or more, more preferably 20 or more, even more preferably 30 or more, particularly preferably 35 or more, and preferably 60 or less. The thermal instability index (TII) of the non-melt-processible PTFE powder can be adjusted to fall within the above range, for example, by producing PTFE using a hydrocarbon surfactant. The thermal instability index (TII) can be measured in accordance with ASTM D 4895-89.

[0331] The non-melt-processible PTFE powder preferably has an average particle size (average secondary particle size) of 100 to 2000 μm. The lower limit of the average secondary particle size is more preferably 200 μm or more, and even more preferably 300 μm or more. The upper limit of the average secondary particle size is preferably 1000 μm or less, more preferably 800 μm or less, and particularly preferably 700 μm or less. The average particle size is the mass-based average particle size (50% cumulative particle size) d50, and can be determined by measurement in accordance with JIS K6891.

[0332] The non-melt-processable PTFE powder is preferable for molding, and suitable applications include hydraulic and fuel system tubes for aircraft and automobiles, flexible hoses for chemical solutions and steam, and wire coating applications. It can also be used as a binder for batteries and for dust prevention. Furthermore, the PTFE powder can also be used to produce an expanded body.

[0333] 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.

[0334] <1> According to a first aspect of the present disclosure, there is provided a method for producing a non-melt-processible polytetrafluoroethylene powder, comprising: polymerizing tetrafluoroethylene in the presence of an aqueous medium and a hydrocarbon surfactant to obtain an aqueous dispersion containing non-melt-processible polytetrafluoroethylene; coagulating the non-melt-processible polytetrafluoroethylene in the aqueous dispersion to obtain a wet powder; washing the wet powder; and heat-treating the wet powder to obtain the non-melt-processible polytetrafluoroethylene powder. <2> According to a second aspect of the present disclosure, there is provided a production method according to the first aspect, in which the non-melt-processible polytetrafluoroethylene is coagulated using at least one coagulation method selected from the group consisting of a coagulation method by stirring, an ultrasonic coagulation method, a coagulation method using ultrafine bubbles, a coagulation method using an alkali, a coagulation method using an acid, a coagulation method using an oxidizing agent, a coagulation method using an organic solvent, and a coagulation method using a radical generator. <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 the wet powder is washed using at least one cleaning method selected from the group consisting of a cleaning method by stirring, an ultrasonic cleaning method, a cleaning method using ultrafine bubbles, a cleaning method using an alkali, a cleaning method using an acid, and a cleaning method using a radical generator. <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 the heat treatment temperature is 10 to 280°C. <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 the heat treatment is carried out by bringing hot air into contact with the wet powder. <6> According to a sixth aspect of the present disclosure, there is provided a production method according to the fifth aspect, in which the hot air has a velocity of 0.01 to 10 m / s. <7> According to a seventh aspect of the present disclosure, there is provided a production method according to any one of the first to fourth aspects, in which the heat treatment is carried out by heating the wet powder in the presence of water vapor. <8> According to an eighth aspect of the present disclosure, there is provided the production method according to the seventh aspect, wherein the wet powder is heated in the presence of water vapor, and then the wet powder is dried.<9> According to a ninth aspect of the present disclosure, there is provided a production method according to any of the first to fourth aspects, comprising: obtaining the wet powder by coagulating the non-melt-processible polytetrafluoroethylene in the aqueous dispersion using at least one coagulation method selected from the group consisting of a coagulation method by stirring, an ultrasonic coagulation method, and a coagulation method using an acid; washing the wet powder using at least one cleaning method selected from the group consisting of a cleaning method by stirring and an ultrasonic cleaning method; and heat-treating the wet powder by contacting the wet powder with hot air of 160°C or higher at a wind speed of 0.40 m / s or higher for 30 minutes or longer, or by heating the wet powder in the presence of water vapor of 160°C or higher for 200 minutes or longer, to obtain the non-melt-processible polytetrafluoroethylene powder. <10> According to a tenth aspect of the present disclosure, there is provided a production method according to any one of the first to fourth and ninth aspects, comprising: arranging the washed wet powder so that, when hot air passes from the surface onto which the hot air has been blown toward a surface opposite to the surface onto which the hot air has been blown, the air pressure on the surface onto which the hot air has been blown is higher than the air pressure on the surface opposite to the surface onto which the hot air has been blown, thereby forming a wet powder layer; subsequently, blowing hot air of 195°C or higher onto the wet powder layer at a wind speed of 0.50 m / s or more, introducing the hot air into the wet powder layer from the surface onto which the hot air has been blown, and discharging the hot air from the surface opposite to the surface onto which the hot air has been blown, thereby bringing the wet powder into contact with the hot air for 30 to 200 minutes, thereby heat-treating the wet powder. <11> According to an eleventh aspect of the present disclosure, there is provided a production method according to any one of the first to fourth and ninth aspects, comprising: arranging the washed wet powder to form a wet powder layer such that, when hot air is blown onto it, the hot air is not discharged from a surface opposite to the surface onto which the hot air is blown, or such that, when the hot air passes from the surface onto which the hot air is blown towards the surface opposite to the surface onto which the hot air is blown, the air pressure on the surface onto which the hot air is blown becomes the same as the air pressure on the surface opposite to the surface onto which the hot air was blown; and then blowing hot air at a temperature of 170 to 190°C onto the wet powder layer at a wind speed of 2.0 to 5.0 m / s, and keeping the wet powder in contact with the hot air for 420 to 1500 minutes, thereby heat-treating the wet powder.<12> According to a twelfth aspect of the present disclosure, there is provided a non-melt-processible polytetrafluoroethylene powder comprising any one of compounds represented by the following general formula (4), wherein the content of at least one of the compounds is less than 100 ppb by mass relative to the non-melt-processible polytetrafluoroethylene powder, and the extrusion pressure measured at a reduction ratio of 100 is 25 MPa or less. General formula (4): [H-(CF. ２ ) ｍ－１ CO ２ － ]M ＋ (wherein m is an integer of 4 to 20, M ＋ represents a cation.)

[0335] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0336] The values ​​in the examples were measured by the following methods.

[0337] <Polymer solid content concentration> 1 g of the aqueous PTFE 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 solid content concentration.

[0338] <Average primary particle diameter> The PTFE aqueous dispersion was diluted with water until the solid content became 0.15% by mass, and the transmittance of the 550 nm projected light per unit length of the diluted latex obtained and the number-based average primary particle diameter determined by measuring the unidirectional diameter by a transmission electron microscope photograph were measured, and a calibration curve was prepared. Using this calibration curve, the average primary particle diameter was determined from the measured transmittance of the 550 nm projected light of each sample.

[0339] <Moisture Content of PTFE Powder> Approximately 20 g of PTFE powder was heated at 150°C for 2 hours, and the mass was measured before and after, and the moisture content was calculated according to the following formula. Three samples were taken, and the moisture contents of each were calculated, and the average was calculated and used as the moisture content of the PTFE powder. Moisture content (mass%) = [(mass (g) of PTFE powder before heating) - (mass (g) of PTFE powder after heating)] / (mass (g) of PTFE powder before heating) x 100

[0340] <General formula (4): [H-(CF ２ ) ｍ－１ CO ２ － ]M ＋ Measurement of the content of the compound represented by the following formula:> Measurement was carried out using liquid chromatography mass spectrometry under the following conditions.

[0341] Extraction from PTFE powder 10 g (12.6 mL) of methanol was added to 1 g of PTFE powder, and the mixture was subjected to ultrasonic treatment for 60 minutes to extract the supernatant containing the compound represented by general formula (4). The resulting extract was appropriately concentrated with a nitrogen purge to obtain a concentrated extract.

[0342] Measurement of the Content of the Compound Represented by General Formula (4) in the Extract The content of the compound represented by general formula (4) in the extract was determined by converting it into perfluorooctanoic acid.

[0343] Calibration curve of perfluorooctanoic acid Five levels of methanol standard solutions of perfluorooctanoic acid with known concentrations ranging from 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). Using a first-order approximation from the concentration of each sample and the peak integral value, a and b were calculated using the following relational expression (1): A = a × X + b (1) A: peak area of ​​perfluorooctanoic acid X: concentration of perfluorooctanoic acid (ng / mL)

[0344] Measurement equipment configuration and LC-MS measurement conditions

[0345] MRM measurement parameters

[0346] Content of Compounds Represented by General Formula (4) Having 4 to 20 Carbon Numbers in the Extract Using a liquid chromatograph mass spectrometer, the amount of compounds represented by general formula (4) having 4 to 20 carbon atoms was measured. For the extracted liquid phase, the peak areas of the compounds represented by general formula (4) having each carbon number were determined using the MRM method.

[0347] MRM measurement parameters

[0348] The content of the compound represented by general formula (4) and having carbon number m in the extract was calculated using the following formula (3). a and b in formula (3) were determined from formula (1). XCm = ((ACm - b) / a) × ((50 × (m - 1) + 45) / 413) (3) XCm: content (ng / mL) of the compound represented by general formula (4) and having carbon number m in the extract solution ACm: peak area of ​​the compound represented by general formula (4) and having carbon number m in the extract solution The quantitation limit for this measurement is 1 ng / mL.

[0349] Content of Compound Represented by General Formula (4) and Having Carbon Number m in PTFE Powder The content of the compound represented by General Formula (4) and having carbon number m in the PTFE powder was calculated by the following formula (4): YCm = XCm × 12.6 (4) YCm: Content of the compound represented by General Formula (4) and having carbon number m in the PTFE powder (ppb vs. PTFE) The lower limit of quantitation is 10 ppb by mass.

[0350] <Paste Extrusion Molding Conditions> An extruder (reduction ratio 100) was thoroughly cleaned.

[0351] 50 g of non-melt-processible PTFE powder was mixed with 10.25 g of hydrocarbon oil (trade name: Isopar G, manufactured by Exxon Corporation) as an extrusion aid in a polyethylene container for 3 minutes. The mixture was filled into the cylinder of an extruder at room temperature (25±2°C), and a load of 0.47 MPa was applied to the piston inserted into the cylinder and maintained for 1 minute. The mixture was then extruded through the orifice at a ram speed of 18 mm / min. The ratio of the cross-sectional area of ​​the cylinder to the cross-sectional area of ​​the orifice was 100. In the latter half of the extrusion operation, the load (N) when the pressure reached equilibrium was divided by the cross-sectional area of ​​the cylinder, and the resulting value was taken as the extrusion pressure (MPa).

[0352] <Coefficient of variation of extrusion pressure of RR100> In the above-mentioned measurement of the extrusion pressure of RR100, the extrusion pressure of the paste extrusion was measured in the latter half of the extrusion operation, and the coefficient of variation of the extrusion pressure of RR100 was calculated from the average value and standard deviation of the extrusion pressure. (Coefficient of variation of extrusion pressure of RR100) = (Standard deviation of extrusion pressure of RR100) / (Average value of extrusion pressure of RR100)

[0353] Preparation Example 1 10 g of lauric acid was added to 100 g of deionized water and stirred, and 25 g of a 10% aqueous solution of ammonia was gradually added thereto to obtain an aqueous solution B.

[0354] Production Example 1: 3560 g of deionized and degassed water, 180 g of paraffin wax, and 0.180 g of lauric acid were added to a 6 L SUS reactor, the reactor was sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 85°C, 3.9 g of HFP was added, and TFE was further added to the reactor, bringing the reactor pressure to 0.78 MPa. An aqueous solution of 0.61 g of ammonium persulfate (APS) dissolved in 20 g of water was charged as a polymerization initiator into the reactor. TFE was charged so that the reaction pressure was constant at 0.78 MPa.

[0355] When 145 g of TFE was charged, stirring was stopped, and the reactor was depressurized until the pressure in the reactor reached atmospheric pressure. Thereafter, TFE was supplied until the pressure in the reactor reached 0.78 MPaG, and stirring was resumed to continue the reaction. At the same time, aqueous solution B was continuously charged.

[0356] When the amount of TFE consumed in the reaction reached about 650 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure inside the reactor was vented to normal pressure, and the aqueous dispersion was taken out of the reactor. After cooling, the paraffin wax was separated.

[0357] The resulting aqueous PTFE dispersion had a solid content of 15.2 mass % and an average primary particle size of 190 nm.

[0358] Production Example 2: 1780 g of deionized and degassed water, 90 g of paraffin wax, and 0.27 g of sodium laurate were added to a 3 L SUS reactor, the reactor was sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 85 ° C, 2.2 g of HFP was added, and TFE was further added to the reactor, bringing the reactor pressure to 2.7 MPaG. An aqueous solution of 0.31 g of ammonium persulfate (APS) dissolved in 20 g of water was charged as a polymerization initiator into the reactor. TFE was charged so that the reaction pressure was constant at 2.7 MPaG.

[0359] When 50 g of TFE was charged, stirring was stopped, and the reactor was depressurized until the pressure in the reactor reached atmospheric pressure. Thereafter, TFE was supplied until the pressure in the reactor reached 2.7 MPaG, and stirring was resumed to continue the reaction. At the same time, aqueous solution B was continuously charged.

[0360] When the amount of TFE consumed in the reaction reached about 770 g, 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 aqueous dispersion was removed from the reactor. After cooling, the paraffin wax was separated. 25 g of aqueous solution B was charged before the reaction was terminated.

[0361] The resulting aqueous PTFE dispersion had a solid content of 29.6% by mass and an average primary particle size of 214 nm.

[0362] Reference Example 1 Deionized water was added to the PTFE aqueous dispersion obtained in Production Example 1 to prepare 2.5 L of PTFE dispersion, the specific gravity of which (25 ° C) was adjusted to 1.080. 2.5 L of PTFE aqueous dispersion was added to a 6 L coagulation tank equipped with an anchor-type stirring blade and a baffle, and the internal temperature was adjusted to 25 ° C. 16 g of nitric acid (10%) was added, and stirring was started at a stirring speed of 500 rpm. After starting stirring, it was confirmed that the aqueous dispersion had passed through a slurry state and that a wet PTFE powder had been formed, and stirring was continued for another 1 minute.

[0363] Subsequently, the wet PTFE powder was filtered off, and the wet PTFE powder and 2.5 L of deionized water were charged into a coagulation tank, adjusted to 25°C, and the polymer powder was washed at a stirring speed of 500 rpm. This operation was repeated twice. After washing, the wet PTFE powder was filtered off to obtain wet PTFE powder. The obtained wet PTFE powder was placed on a flat tray (a tray with no air permeability on the bottom and sides) (placement amount: 2.0 g / cm). ２ The mixture was dried in a hot air circulation dryer (air velocity: 1.0 m / s) at 180°C for 18 hours to obtain a PTFE powder. The amount of the PTFE discharged from the dryer was set to 25% by volume.

[0364] In Reference Example 1, hot air was blown onto the wet PTFE powder on the flat tray, so the layer of wet powder placed on the flat tray had a surface onto which the hot air was blown, but no surface through which the hot air could escape. Therefore, the heat treatment method in Reference Example 1 was a hot air circulation drying treatment.

[0365] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 4.

[0366] Reference Example 2 A wet PTFE powder was obtained in the same manner as in Reference Example 1, except that the PTFE aqueous dispersion obtained in Production Example 1 was replaced with the PTFE aqueous dispersion obtained in Production Example 2. The moisture content of the obtained wet PTFE powder was approximately 60% by mass. The obtained wet PTFE powder was placed on a metal mesh tray (60 mesh, a container with an open top, impermeable sides, and permeable bottom) (placement amount: 0.5 g / cm). ２ The mixture was then heat-treated at 200°C for 80 minutes in a hot air circulation dryer (air speed 1.0 m / s) to obtain PTFE powder. The amount of PTFE discharged from the dryer was set to 25% by volume. The moisture content of the obtained PTFE powder was 0.2% by mass.

[0367] In Reference Example 2, hot air was blown from the side onto a container with an open top and a breathable bottom, so the hot air flowed separately to the top and bottom of the container (mesh tray). There was no pressure difference between the top and bottom (pressure difference was less than 10 Pa), so the hot air did not pass through the layer of moist powder. Therefore, the heat treatment method in Reference Example 2 was a hot air circulation drying treatment.

[0368] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 5.

[0369] Experimental Example 1 The wet PTFE powder obtained in Reference Example 1 was placed on a metal mesh tray (60 mesh) (amount placed: 1.2 g / cm ２ Superheated steam at 180°C was introduced into an electric furnace equipped with a high-temperature superheated steam generator at a rate of 20 kg / hr, and the mixture was heat-treated in the furnace at 180°C for 7 hours to obtain a PTFE powder.

[0370] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 4.

[0371] Experimental Example 6 A PTFE powder was obtained in the same manner as in Experimental Example 1, except that the heat treatment temperature was changed to 240° C. The moisture content of the obtained PTFE powder was 0.004% by mass.

[0372] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 6.

[0373] Experimental Example 2: Amount of placement: 1.0 g / cm ２ The heat treatment was carried out in the same manner as in Reference Example 1, except that the flat tray was replaced with a metal mesh tray (60 mesh, a container with an open top, no air permeability on the sides, and air permeability on the bottom), and the air velocity was changed to 3.0 m / s, to obtain a PTFE powder. The proportion of the amount discharged from the dryer at this time was set to 50% by volume.

[0374] In Experimental Example 2, the container had an open top, no air permeability on the sides, and an air permeability on the bottom, and hot air was blown from the side, so the hot air flowed separately to the top and bottom of the container (mesh tray). There was no pressure difference between the top and bottom (the pressure difference was less than 10 Pa), so the hot air did not pass through the layer of moist powder. Therefore, the heat treatment method in Experimental Example 2 was a hot air circulation drying treatment.

[0375] The RR100 extrusion pressure of the obtained PTFE powder was 14 MPa, and the coefficient of variation of the RR100 extrusion pressure was 0.09.

[0376] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 4.

[0377] Experimental Example 7 The wet PTFE powder obtained in Reference Example 2 was placed (amount placed: 0.5 g / cm) on a metal mesh tray (60 mesh, a container with an open top, no air permeability on the sides, and air permeability on the bottom) in which a fiber sheet was placed as a woven fabric on a 10-mesh wire net. ２The mixture was then heat-treated at 160°C for 18 hours in a hot air circulation dryer (air speed 1.0 m / s) to obtain PTFE powder. The amount of PTFE discharged from the dryer was set to 25% by volume. The moisture content of the obtained PTFE powder was 0.001% by mass.

[0378] In Experimental Example 7, the container had an open top, no air permeability on the sides, and an air permeability on the bottom, and hot air was blown from the side. Therefore, the hot air flowed separately to the top and bottom of the container (mesh tray). There was no pressure difference between the top and bottom (the pressure difference was less than 10 Pa), and the hot air did not pass through the layer of moist powder. Therefore, the heat treatment method in Experimental Example 7 was a hot air circulation drying treatment.

[0379] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 6.

[0380] The RR100 extrusion pressure of the obtained PTFE powder was 14.9 MPa, and the coefficient of variation of the RR100 extrusion pressure was 0.07.

[0381] Experimental Example 8 The wet PTFE powder obtained in Reference Example 2 was placed (amount placed: 0.5 g / cm) on a metal mesh tray (60 mesh, a container with an open top, no air permeability on the sides, and air permeability on the bottom) in which a fiber sheet was placed as a woven fabric on a 10-mesh wire net. ２ The mixture was then heat-treated at 250°C for 18 hours in a hot air circulation dryer (air speed 1.0 m / s) to obtain PTFE powder. The amount of PTFE discharged from the dryer was set to 25% by volume. The moisture content of the obtained PTFE powder was 0.000% by mass.

[0382] In Experimental Example 8, the container had an open top, no air permeability on the sides, and an air permeability on the bottom, and hot air was blown from the side. Therefore, the hot air flowed separately to the top and bottom of the container (mesh tray). There was no pressure difference between the top and bottom (the pressure difference was less than 10 Pa), and the hot air did not pass through the layer of moist powder. Therefore, the heat treatment method in Experimental Example 8 was a hot air circulation drying treatment.

[0383] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 6.

[0384] Experimental Example 10 A wet PTFE powder was obtained in the same manner as in Reference Example 1, except that the PTFE aqueous dispersion obtained in Production Example 1 was replaced with the PTFE aqueous dispersion obtained in Production Example 2. The moisture content of the obtained wet PTFE powder was approximately 60% by mass. The obtained wet PTFE powder was placed on a tray containing a 10-mesh wire netting on which a fiber sheet was placed as a woven fabric (amount placed: 0.8 g / cm). ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 200°C for 40 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 80% by volume, to obtain PTFE powder.

[0385] In Experimental Example 10, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the wet powder layer placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 10 was a through-air drying treatment.

[0386] The water content of the obtained PTFE powder was 0.001% by mass.

[0387] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0388] The RR100 extrusion pressure of the obtained PTFE powder was 16.2 MPa.

[0389] Experimental Example 11 The wet PTFE powder obtained in Experimental Example 10 was placed on a tray with a 10-mesh wire mesh and a fiber sheet placed on it as a woven fabric (placement amount: 0.8 g / cm ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 225°C for 40 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 80% by volume, to obtain PTFE powder.

[0390] In Experimental Example 11, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the layer of wet powder placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 11 was a through-air drying treatment.

[0391] The water content of the obtained PTFE powder was 0.001% by mass.

[0392] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0393] The RR100 extrusion pressure of the obtained PTFE powder was 17.7 MPa.

[0394] Experimental Example 12 The wet PTFE powder obtained in Experimental Example 10 was placed on a tray with a 10-mesh wire mesh and a fiber sheet placed on it as a woven fabric (placement amount: 0.8 g / cm ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 250°C for 40 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 80% by volume, to obtain PTFE powder.

[0395] In Experimental Example 12, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the wet powder layer placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 12 was aeration drying treatment.

[0396] The water content of the obtained PTFE powder was 0.005% by mass.

[0397] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0398] The RR100 extrusion pressure of the obtained PTFE powder was 20.9 MPa, and the coefficient of variation of the RR100 extrusion pressure was 0.004.

[0399] Experimental Example 13 The wet PTFE powder obtained in Experimental Example 10 was placed on a tray with a 10-mesh wire mesh and a fiber sheet placed on it as a woven fabric (placement amount: 0.8 g / cm ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 250°C for 40 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 50% by volume, to obtain PTFE powder.

[0400] In Experimental Example 13, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the wet powder layer placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 13 was aeration drying treatment.

[0401] The water content of the obtained PTFE powder was 0.000% by mass.

[0402] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0403] Experimental Example 14 The wet PTFE powder obtained in Experimental Example 10 was placed on a tray with a 10-mesh wire mesh and a fiber sheet placed on it as a woven fabric (placement amount: 0.8 g / cm ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 250°C for 40 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 10% by volume, to obtain PTFE powder.

[0404] In Experimental Example 14, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the layer of wet powder placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 14 was aeration drying treatment.

[0405] The water content of the obtained PTFE powder was 0.000% by mass.

[0406] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0407] Experimental Example 15 The wet PTFE powder obtained in Experimental Example 10 was placed on a tray with a 10-mesh wire netting on which a fiber sheet was placed as a woven fabric (amount placed: 0.5 g / cm ２ The wet PTFE powder on the tray was continuously supplied with air adjusted to a wind speed of 0.6 m / s from above the tray, and heat treatment was carried out at 250°C for 80 minutes using an electric furnace (wind speed 0.6 m / s) with the ratio of the amount of air discharged from the electric furnace set to 50% by volume, to obtain PTFE powder.

[0408] In Experimental Example 15, hot air was blown from above onto the wet PTFE powder on the fiber sheet, forming a surface onto which the hot air was blown on the upper surface of the wet powder layer placed on the fiber sheet. Furthermore, the hot air that entered from this surface passed through from the lower surface, forming a surface onto which the hot air escaped on the lower surface of the wet powder layer. The difference in air pressure between the surface onto which the hot air was blown (upper surface) and the surface from which the hot air escaped (lower surface) was 10 Pa or more. Therefore, the heat treatment method in Experimental Example 15 was a through-air drying treatment.

[0409] The water content of the obtained PTFE powder was 0.004% by mass.

[0410] The content of the compound represented by general formula (4) in the resulting PTFE powder was measured, and the results are shown in Table 7.

[0411] The RR100 extrusion pressure of the obtained PTFE powder was 13.7 MPa, and the coefficient of variation of the RR100 extrusion pressure was 0.003.

[0412] Experimental Example 4: Deionized water was added to the PTFE aqueous dispersion obtained in Production Example 1, and deionized water containing 25 g of ammonium persulfate was further added to prepare 2.5 L of PTFE dispersion with a specific gravity (25 ° C) adjusted to 1.080. The PTFE dispersion was treated in a thermostatic bath at 80 ° C for 7 hours and then cooled to room temperature. 2.5 L of the PTFE aqueous dispersion was added to a 6 L coagulation tank equipped with an anchor-type stirring blade and a baffle, and the internal temperature was adjusted to 25 ° C. Stirring was initiated at a stirring speed of 500 rpm. After starting the stirring, it was confirmed that the aqueous dispersion had passed through a slurry state and that a wet PTFE powder had been formed, and stirring was continued for another 1 minute.

[0413] Subsequently, the wet PTFE powder was filtered off, and the wet PTFE powder and 2.5 L of deionized water were charged into a coagulation tank, adjusted to 25° C., and the polymer powder was washed at a stirring speed of 500 rpm. This operation was repeated twice. After washing, the wet PTFE powder was filtered off and left to dry in a hot air circulation dryer at 120° C. for 18 hours, thereby obtaining a PTFE powder.

[0414] Experimental Example 5: Deionized water was added to the PTFE aqueous dispersion obtained in Preparation Example 1, and the specific gravity (25 ° C) was adjusted to 1.080. 4.5 L of the gravity-adjusted PTFE aqueous dispersion was added to a 6 L coagulation tank equipped with an anchor-type stirring blade and a baffle, and the internal temperature was adjusted to 20 ° C. After adjustment, an ultrasonic generator (Shinka Sangyo Co., Ltd. SRK-400) was installed in the coagulation tank, and 41 g of nitric acid (10 wt%) was added. At the same time, stirring was performed at a stirring speed of 500 rpm, and ultrasonic waves were generated at a frequency of 45 kHz and an output of 600 W. After stirring began, it was confirmed that the aqueous dispersion had passed through a slurry state and that wet PTFE powder had been formed, and stirring was continued for another 1 minute.

[0415] Subsequently, the wet PTFE powder was filtered off, 2.5 L of deionized water was added, the internal temperature was adjusted to 25°C, and the mixture was stirred at a stirring speed of 500 rpm while simultaneously being subjected to ultrasonic treatment twice at 45 kHz and 300 W to obtain wet PTFE powder.

[0416] The obtained wet PTFE powder was heat-treated in a hot air circulating drying oven at 120°C for 18 hours to obtain a PTFE powder. Methanol was added in an amount 10 times the mass of the obtained PTFE powder, and ultrasonic cleaning was carried out at 60°C for 2 hours. The methanol and PTFE powder were then filtered off to obtain a PTFE powder.

[0417]

[0418]

[0419]

[0420]

Claims

1. A method for producing non-melt processable polytetrafluoroethylene powder, comprising: polymerizing tetrafluoroethylene in the presence of an aqueous medium and a hydrocarbon surfactant to obtain an aqueous dispersion containing non-melt processable polytetrafluoroethylene; coagulating the non-melt processable polytetrafluoroethylene in the aqueous dispersion to obtain a wet powder; washing the wet powder; and heat-treating the wet powder to obtain the non-melt processable polytetrafluoroethylene powder.

2. The method of claim 1, wherein the non-melt-processable polytetrafluoroethylene is coagulated using at least one coagulation method selected from the group consisting of a coagulation method by stirring, an ultrasonic coagulation method, a coagulation method using ultrafine bubbles, a coagulation method using an alkali, a coagulation method using an acid, a coagulation method using an oxidizing agent, a coagulation method using an organic solvent, and a coagulation method using a radical generator.

3. The manufacturing method according to claim 1 or 2, wherein the wet powder is washed using at least one cleaning method selected from the group consisting of a cleaning method by stirring, an ultrasonic cleaning method, a cleaning method using ultrafine bubbles, a cleaning method using an alkali, a cleaning method using an acid, and a cleaning method using a radical generator.

4. The method according to any one of claims 1 to 3, wherein the heat treatment temperature is 10 to 280°C.

5. The method according to any one of claims 1 to 4, wherein the heat treatment is carried out by contacting the moist powder with hot air.

6. The method according to claim 5, wherein the hot air has a speed of 0.01 to 10 m / s.

7. The method according to any one of claims 1 to 4, wherein the heat treatment is carried out by heating the moist powder in the presence of water vapor.

8. The method according to claim 7, further comprising the steps of heating the wet powder in the presence of water vapor and then drying the wet powder.

9. The method according to any one of claims 1 to 4, comprising obtaining the wet powder by coagulating the non-melt-processible polytetrafluoroethylene in the aqueous dispersion using at least one coagulation method selected from the group consisting of a coagulation method by stirring, an ultrasonic coagulation method, and a coagulation method using an acid; washing the wet powder using at least one cleaning method selected from the group consisting of a cleaning method by stirring and an ultrasonic cleaning method; and heat-treating the wet powder by contacting the wet powder with hot air of 160°C or higher at a wind speed of 0.40 m / s or higher for 30 minutes or more, or by heating the wet powder in the presence of water vapor of 160°C or higher for 200 minutes or more, to obtain the non-melt-processible polytetrafluoroethylene powder.

10. A method for producing a wet powder according to any one of claims 1 to 4 and 9, comprising the steps of: arranging the washed wet powder so that when hot air passes from the surface onto which the hot air has been blown towards the surface opposite to the surface onto which the hot air has been blown, the air pressure on the surface onto which the hot air has been blown is higher than the air pressure on the surface opposite to the surface onto which the hot air has been blown; blowing hot air of 195°C or higher at a wind speed of 0.50 m / s or more onto the wet powder layer; introducing the hot air into the wet powder layer from the surface onto which the hot air has been blown; and discharging the hot air from the surface opposite to the surface onto which the hot air has been blown; thereby heat-treating the wet powder by keeping the wet powder in contact with the hot air for 30 to 200 minutes.

11. A method for producing a wet powder according to any one of claims 1 to 4 and 9, comprising the steps of: arranging the washed wet powder to form a wet powder layer in such a manner that, when hot air is blown onto it, the hot air is not discharged from a surface opposite to the surface against which the hot air is blown; or, when hot air passes from the surface against which the hot air is blown towards the surface against which the hot air is blown, the air pressure on the surface against which the hot air is blown becomes the same as the air pressure on the surface against which the hot air is blown; then blowing hot air at a temperature of 170 to 190°C onto the wet powder layer at a wind speed of 2.0 to 5.0 m / s; and keeping the wet powder in contact with the hot air for 420 to 1500 minutes, thereby heat-treating the wet powder.

12. A non-melt-processable polytetrafluoroethylene powder containing any of the compounds represented by the following general formula (4), in which the content of at least one of the compounds is less than 100 ppb by mass relative to the non-melt-processable polytetrafluoroethylene powder, and the extrusion pressure measured at a reduction ratio of 100 is 25 MPa or less. General formula (4): [H-(CF ２ ) ｍ－１ CO ２ － ]M ＋ (In the formula, m is an integer from 4 to 20; M ＋ represents a cation.)

Images