Composition and stretched body

Abstract

To provide a polytetrafluoroethylene composition excellent in stretchability and a stretched body.SOLUTION: The composition contains polytetrafluoroethylene and a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I) and has a standard specific gravity of 2.200 or less. CX1X3=CX2R(-CZ1Z2-A0)m (I) (where X1 and X3 each independently represent F, Cl, H or CF3; A0 represents an anionic group; X2 represents H, F, an alkyl group or a fluorine-containing alkyl group; R represents a linking group; Z1 and Z2 each independently represent H, F, an alkyl group or a fluorine-containing alkyl group; and m represents an integer of 1 or more).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to compositions and extruded bodies. [Background technology]

[0002] When a composition containing polytetrafluoroethylene is molded and highly stretched in an unsintered state, a porous polytetrafluoroethylene film is obtained. This porous film allows gases such as water vapor to pass through, but does not allow water droplets to pass through due to the strong water repellency of polytetrafluoroethylene. Taking advantage of this unique property, it is used in clothing, separation membranes, etc.

[0003] Various methods for producing polytetrafluoroethylene have been investigated. For example, Patent Document 1 describes a method for producing an aqueous dispersion containing rod-shaped microparticles of polytetrafluoroethylene having an average aspect ratio of 2 or more, which is characterized by polymerizing tetrafluoroethylene in the presence of a polymer consisting of polymerization units represented by formula 1, or a copolymer consisting of polymerization units represented by formula 1 and polymerization units represented by formula 2 (with the proviso that the polymerization units represented by formula 1 account for 40 mol % or more of the total polymerization units). [ka] -CF2CFX- ...Formula 2 However, in formula 1, R f represents a perfluoroperfluoroalkylene group having 1 to 6 carbon atoms, M represents an alkali metal ion or an ammonium ion, and in formula 2, X represents a fluorine atom or a chlorine atom.

[0004] Also, Patent Document 2 describes particles containing a bulk of a fluoropolymer and a core of a fluorinated ionomer. Patent Document 3 describes a method for preparing an aqueous dispersion of fluoropolymer particles, which includes the steps of providing dispersed fine particles of a fluorinated ionomer in an aqueous polymerization medium, and polymerizing at least one fluorinated monomer in the aqueous polymerization medium in the presence of the dispersed fine particles of the fluorinated ionomer and an initiator to form an aqueous dispersion of fluoropolymer particles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-181009 [Patent Document 2] Special Publication No. 2012-513532 [Patent Document 3] Special Publication No. 2012-513530 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a composition having excellent extensibility. [Means for solving the problem]

[0007] The present disclosure relates to a composition comprising a polymer (I) containing polytetrafluoroethylene and polymerization units (I) based on a monomer represented by the following general formula (I), and having a standard specific gravity of 2.200 or less. CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; A 0is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. The composition of the present disclosure preferably has a breaking strength of 10.0 N or more. The composition of the present disclosure preferably has a stress relaxation time of 50 seconds or longer. The composition of the present disclosure is preferably extruded at a pressure of 10.0 MPa or more and 30.0 MPa or less. The polytetrafluoroethylene preferably has an endothermic peak temperature in the range of 333 to 347°C. The anionic group may be a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or a -C(CF3)2OM (wherein M is -H, a metal atom, -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The composition of the present disclosure is preferably substantially free of fluorine-containing surfactant. The compositions of the present disclosure are preferably in the form of a powder. The present disclosure also relates to an extruded body made from the above composition.

[0008] The present disclosure further relates to an extruded body comprising a polymer (I) containing polytetrafluoroethylene and polymerization units (I) based on a monomer represented by the following general formula (I): CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3are each independently F, Cl, H or CF3; A 0 is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. The stretched body of the present disclosure preferably has a breaking strength of 10.0 N or more. The stretched body of the present disclosure preferably has a stress relaxation time of 50 seconds or longer. The stretched body of the present disclosure preferably has an endothermic peak temperature between 325 and 350°C. The anionic group may be a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or a -C(CF3)2OM (wherein M is -H, a metal atom, -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The stretched body of the present disclosure preferably does not substantially contain a fluorine-containing surfactant. Effect of the Invention

[0009] The composition of the present disclosure has excellent extensibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0011] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0012] In the present disclosure, melt processability means that the polymer can be melted and processed using conventional processing equipment such as an extruder, an injection molding machine, etc. Therefore, melt processable fluororesin usually has a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described below.

[0013] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing a hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group which may have one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents, a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group which may have one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, a heteroaryl group optionally having one or more substituents, Cyano group, Formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2- and RaNRbSO2- (In these formulas, Ra is independently an alkyl group which may have one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents, a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group which may have one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents, Rb is independently H or an alkyl group which may have one or more substituents. Includes: The organic group is preferably an alkyl group which may have one or more substituents.

[0014] In the present disclosure, a "substituent" means a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino ... an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, an aromatic oxycarbonyl group, a hetero These include an aryl group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, and a diaromatic oxyphosphinyl group.

[0015] The aliphatic group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic group include alkyl groups having a total of 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, and a carbamoylmethyl group.

[0016] The aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in total, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0017] The heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the heterocyclic group include a 5- or 6-membered heterocycle having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0018] The acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the acyl group include acyl groups having a total of 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

[0019] The acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0020] The aliphatic oxycarbonyl group may be saturated or unsaturated, and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total of 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a (t)-butoxycarbonyl group.

[0021] The carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 9 carbon atoms, preferably an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, and an N-phenylcarbamoyl group.

[0022] The aliphatic sulfonyl group may be saturated or unsaturated, and may have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total of 1 to 6 carbon atoms, preferably a total of 1 to 4 carbon atoms, such as methanesulfonyl.

[0023] The aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms, such as benzenesulfonyl.

[0024] The amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.

[0025] The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably a total of 2 to 8 carbon atoms, and more preferably an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0026] The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, or a 2-pyridinesulfonamide group.

[0027] The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the sulfamoyl group include a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 9 carbon atoms, a dialkylsulfamoyl group having a total of 2 to 10 carbon atoms, an arylsulfamoyl group having a total of 7 to 13 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 12 carbon atoms, more preferably a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 7 carbon atoms, a dialkylsulfamoyl group having a total of 3 to 6 carbon atoms, an arylsulfamoyl group having a total of 6 to 11 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 10 carbon atoms, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[0028] The aliphatic oxy group may be saturated or unsaturated and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. Examples of the aliphatic oxy group include alkoxy groups having a total of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc.

[0029] The aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group condensed with the aryl group, or an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0030] The aliphatic thio group may be saturated or unsaturated and is an alkylthio group having a total of 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, or a t-butylthio group.

[0031] The carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 9 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 10 carbon atoms, an arylcarbamoylamino group having a total of 7 to 13 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 12 carbon atoms, preferably a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 7 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 6 carbon atoms, an arylcarbamoylamino group having a total of 7 to 11 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 10 carbon atoms, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0032] 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.).

[0033] 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.).

[0034] The composition of the present disclosure contains polytetrafluoroethylene (hereinafter also referred to as "PTFE").

[0035] The PTFE generally has extensibility, fibrillation properties, and non-melt fabrication properties. The non-melt fabrication properties mean that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point according to ASTM D 1238 and D 2116, that is, that the PTFE does not flow easily even in the melting temperature range.

[0036] The PTFE may be a homopolymer of tetrafluoroethylene (TFE), or a modified PTFE obtained by copolymerizing TFE with a modified monomer. From the viewpoint of the stability and yield of the aqueous dispersion, the PTFE is more preferably a modified PTFE.

[0037] The above-mentioned modified monomer is not particularly limited as long as it is copolymerizable with TFE, and includes fluoromonomers and non-fluoromonomers. The modified monomer used may be one type or multiple types.

[0038] The non-fluoromonomer is not particularly limited and may be represented by the general formula: CH2=CR Q1 -LR Q2 (In the formula, R Q1 represents a hydrogen atom or an alkyl group. L represents a single bond, -CO-O-*, -O-CO-* or -O-. * represents R Q2 R represents the bond position. Q2 represents a hydrogen atom, an alkyl group or a nitrile group.

[0039] Examples of non-fluoromonomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, vinyl methacrylate, vinyl acetate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, ethyl vinyl ether, cyclohexyl vinyl ether, etc. Of these, butyl methacrylate, vinyl acetate, and acrylic acid are preferred as non-fluoromonomers.

[0040] 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.

[0041] The perfluorovinyl ether is not particularly limited, and may be, for example, a perfluorovinyl ether represented by the general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoro organic group). In the present disclosure, the "perfluoro organic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms. The perfluoro organic group may have an ether oxygen.

[0042] An example of the perfluorovinyl ether is perfluoro(alkyl vinyl ether) [PAVE], which is represented by the general formula (A) and in which Rf is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0043] Examples of the perfluoroalkyl group in the PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0044] The perfluorovinyl ether further includes those in which Rf in the general formula (A) is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf is the following formula:

[0045] [ka]

[0046] (wherein m represents 0 or an integer of 1 to 4), Rf is a group represented by the following formula:

[0047] [ka]

[0048] (wherein n represents an integer of 1 to 4).

[0049] Examples of hydrogen-containing fluoroolefins include CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-form), and CHF=CHCF3 (Z-form).

[0050] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0051] Examples of perfluoroallyl ethers include General formula: CF2=CF-CF2-ORf (wherein Rf represents a perfluoro organic group).

[0052] Rf in the above general formula is the same as Rf in general formula (A). Rf is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. As the perfluoroallyl ether, at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is preferable, at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is more preferable, and CF2=CF-CF2-O-CF2CF2CF3 is even more preferable.

[0053] A preferred example of the modifying monomer is the comonomer (3) having a monomer reactivity ratio of 0.1 to 8. The presence of the comonomer (3) makes it possible to obtain PTFE particles having a small average primary particle size and aspect ratio, and to obtain an aqueous dispersion having high dispersion stability.

[0054] Here, the monomer reactivity ratio in copolymerization with TFE is the value obtained by dividing the rate constant of the reaction of the growing radical with TFE by the rate constant of the reaction of the growing radical with comonomer when the growing radical is less than the repeating unit based on TFE. The lower this value, the higher the reactivity of the comonomer with TFE. The monomer reactivity ratio can be calculated by the composition in the polymer produced immediately after the start of copolymerization of TFE with comonomer and using the Feynman-Ross equation.

[0055] The copolymerization is carried out in a 6.0L stainless steel autoclave using 3600g of deionized degassed water, 1000 mass ppm of ammonium perfluorooctanoate relative to the water, and 100g of paraffin wax at a pressure of 0.78 MPaG and a temperature of 70°C. 0.05g, 0.1g, 0.2g, 0.5g, and 1.0g of comonomer are added to the reactor, respectively, and 0.072g of ammonium persulfate (20 mass ppm relative to water) is added, and TFE is continuously fed to maintain the polymerization pressure of 0.78 MPaG. When the amount of TFE charged reaches 1000g, stirring is stopped and the reactor is depressurized until atmospheric pressure is reached. After cooling, the paraffin wax is separated to obtain an aqueous dispersion containing the produced polymer. The aqueous dispersion is stirred to coagulate the produced polymer, and then dried at 150°C. The composition of the resulting polymer is calculated by an appropriate combination of NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0056] The comonomer (3) having a monomer reactivity ratio of 0.1 to 8 is preferably at least one selected from the group consisting of comonomers represented by formulas (3a) to (3d). CH2=CH-Rf 1 (3a) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 10 carbon atoms. CF2=CF-O-Rf 2 (3b) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 2 carbon atoms. CF2=CF-O-(CF2) n CF=CF2(3c) (In the formula, n is 1 or 2.)

[0057] [ka] (In the formula, X 3 and X 4 is F, Cl or a methoxy group, and Y is of formula Y1 or Y2.

[0058] [ka] (In formula Y2, Z and Z' are F or a fluorinated alkyl group having 1 to 3 carbon atoms.)

[0059] The content of the comonomer (3) unit is preferably in the range of 0.00001 to 1.0% by mass based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001% by mass, more preferably 0.0005% by mass, even more preferably 0.001% by mass, and even more preferably 0.005% by mass. The upper limit is, in order of preference, 0.90% by mass, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0060] The modified monomer is preferably at least one selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, perfluoro(alkyl vinyl ether), (perfluoroalkyl)ethylene, ethylene, and modified monomers having a functional group capable of reacting by radical polymerization and a hydrophilic group, because it can obtain an aqueous dispersion having a small average primary particle size, a small aspect ratio of the primary particles, and excellent stability.By using the modified monomer, it is possible to obtain an aqueous dispersion of PTFE having a smaller average primary particle size, a small aspect ratio of the primary particles, and excellent dispersion stability.

[0061] From the viewpoint of reactivity with TFE, the modified monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether) and (perfluoroalkyl)ethylene. The modified monomer more preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene and (perfluorooctyl)ethylene. The total amount of the hexafluoropropylene unit, the perfluoro(alkyl vinyl ether) unit and the (perfluoroalkyl)ethylene unit is preferably in the range of 0.00001 to 1.0% by mass based on the total polymerized units of PTFE. The lower limit of the total amount is more preferably 0.0001% by mass, more preferably 0.0005% by mass, more preferably 0.001% by mass, even more preferably 0.005% by mass, and particularly preferably 0.009% by mass. The upper limit is, in order of preference, 0.90% by mass, 0.50% by mass, 0.40% by mass, 0.30% by mass, 0.20% by mass, 0.15% by mass, 0.10% by mass, 0.08% by mass, 0.05% by mass, and 0.01% by mass.

[0062] The above-mentioned modified monomer preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group (hereinafter referred to as "modified monomer (A)").

[0063] By using the modified monomer (A), it is possible to obtain PTFE particles having a small primary particle size, and to obtain an aqueous dispersion having high dispersion stability. In addition, it is possible to reduce the aspect ratio of the primary particles.

[0064] The amount of the modified monomer (A) used is preferably more than an amount equivalent to 0.1 ppm by mass of the aqueous medium, more preferably more than 0.5 ppm by mass, even more preferably more than 1.0 ppm by mass, even more preferably 5 ppm by mass or more, and particularly preferably 10 ppm by mass or more. If the amount of the modified monomer (A) used is too small, the average primary particle size of the obtained PTFE may not be reduced. The amount of the modified monomer (A) used may be within the above range, but the upper limit may be, for example, 5000 mass ppm. In the above production method, the modified monomer (A) may be added to the system during the reaction in order to improve the stability of the aqueous dispersion during or after the reaction.

[0065] Since the above-mentioned modifying monomer (A) is highly water-soluble, even if unreacted modifying monomer (A) remains in the aqueous dispersion, it can be easily removed in the concentration step or the coagulation and washing steps.

[0066] The above-mentioned modifying monomer (A) is incorporated into the produced polymer during the polymerization process. However, since the concentration of the modifying monomer (A) itself in the polymerization system is low and the amount incorporated into the polymer is small, there is no problem of a decrease in the heat resistance of PTFE or coloration after baking.

[0067] Examples of the hydrophilic group in the modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7yare H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. Of these, -SO3M or -COOM is preferred as the hydrophilic group. R 7y The organic group in R is preferably an alkyl group. 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (group 1) or an alkaline earth metal (group 2), with Na, K or Li being preferred.

[0068] Examples of the "functional group capable of reacting by radical polymerization" in the above-mentioned modifying monomer (A) include groups having an ethylenically unsaturated bond, such as a vinyl group and an allyl group. The group having an ethylenically unsaturated bond is represented by the following formula: CX e X g =CX f R- (In the formula, X e , X f and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group. The linking group of R can be represented by the formula: a Preferred are -CH=CH2 and -CF=CH 2、 -CH=CF 2、 Examples of groups having unsaturated bonds include -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CF=CH2, -(C=O)-CF=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, and -O-CF2-CF=CF2.

[0069] The modified monomer (A) has a functional group that can react with radical polymerization, so it is assumed that when used in the polymerization, it reacts with TFE at the beginning of the polymerization reaction, and forms highly stable particles that have hydrophilic groups derived from the modified monomer (A).Therefore, it is believed that the number of particles increases when polymerization is performed in the presence of the modified monomer (A).

[0070] The above polymerization may be carried out in the presence of one type of the modifying monomer (A), or in the presence of two or more types thereof.

[0071] In the above polymerization, a compound having an unsaturated bond can be used as the modifying monomer (A).

[0072] The modifying monomer (A) is represented by the general formula (4): CX i X k =CX j R a -(CZ 1 Z 2 ) k -Y 3 (4) (In the formula, X i , X j and X k are each independently F, Cl, H, or CF; Y 3 is a hydrophilic group; R a is a linking group; Z 1 and Z 2 are each independently H, F or CF3, and k is 0 or 1). Examples of the hydrophilic group include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M is H, a metal atom, or NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7yare H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. Of these, -SO3M or -COOM is preferred as the hydrophilic group. R 7y The organic group in R is preferably an alkyl group. 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (group 1) or an alkaline earth metal (group 2), with Na, K or Li being preferred. By using the modifying monomer (A), it is possible to obtain an aqueous dispersion having a smaller average primary particle size and excellent stability, and also to reduce the aspect ratio of the primary particles.

[0073] Above R a is a linking group. In the present disclosure, the "linking group" refers to a divalent linking group. The linking group may be a single bond, and preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less. The linking group may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of esters, amides, sulfonamides, carbonyls, carbonates, urethanes, ureas, and carbamates. The linking group may not contain carbon atoms, but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0074] Above R a is preferably, for example, a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group. R aWhen R is a divalent organic group, the hydrogen atoms bonded to the carbon atoms may be replaced with halogens other than fluorine, such as chlorine, and may or may not contain a double bond. a may be either linear or branched, and may be either cyclic or noncyclic. a may contain functional groups (eg, esters, ethers, ketones, amines, halides, etc.). R a may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group. R a Examples of the hydrocarbon group include a hydrocarbon group having no fluorine atoms bonded to a carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, a hydrocarbon group in which all of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, -(C=O)-, -(C=O)-O-, or a hydrocarbon group containing -(C=O)-, which may contain an oxygen atom, a double bond, or a functional group.

[0075] R a is preferably -(C=O)-, -(C=O)-O-, or a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond and may contain a carbonyl group, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine. R a Preferably, -(CH2) a -, -(CF2) a -, -O-(CF2) a -, -(CF2) a -O-(CF2) b -, -O(CF2) a -O-(CF2) b -, -(CF2) a -[O-(CF2) b ] c -, -O(CF2) a -[O-(CF2) b ] c -,-[(CF2) a -O]b -[(CF2) c -O] d -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b -, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2) a -, -(C=O)-(CF2) a -, -(C=O)-O-(CH2) a -, -(C=O)-O-(CF2) a -, -(C=O)-[(CH2) a -O] b -, -(C=O)-[(CF2) a -O] b -, -(C=O)-O[(CH2) a -O] b -, -(C=O)-O[(CF2) a -O] b -, -(C=O)-O[(CH2) a -O] b -(CH2) c -, -(C=O)-O[(CF2) a -O] b -(CF2) c -, -(C=O)-(CH2) a -O-(CH2) b -, -(C=O)-(CF2) a -O-(CF2) b -, -(C=O)-O-(CH2) a -O-(CH2) b -, -(C=O)-O-(CF2) a -O-(CF2) b At least one selected from the group consisting of -, -(C=O)-O-C6H4-, and combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may be independently 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0076] R a Specific examples suitable as -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3) CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CH2-, -(C=O)-, -(C=O)-O-, -(C=O)- (CH2)-, -(C=O)-(CF2)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CF2)-, -(C=O)-[(CH2)2-O] n -, -(C=O)-[(CF2)2-O] n -, -(C=O)-O[(CH2)2-O] n -, -(C=O)-O[(CF2)2-O] n -, -(C=O)-O[(CH2)2-O] n -(CH2)-, -(C=O)-O[(CF2)2-O] n -(CF2)-, -(C=O)-(CH2)2-O-(CH2)-, -(C=O)-(CF2)2-O-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-, -(C=O)-O-(CF2)2-O-(CH2)-, -(C=O)-O-(CF2)2-O-(CF2)-, -(C=O)-O-C6H4- and the like are included. a Specifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2 -O-CF(CF3)CF2-O-, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2)-, -(C=O)-O-(CH2)-, -(C=O)-O[(CH2)2-O] n -, -(C=O)-O[(CH2)2-O] n Preferred are -(CH2)-, -(C=O)-(CH2)2-O-(CH2)-, or -(C=O)-O-C6H4-. In the above formula, n is an integer of 1-10.

[0077] -R in general formula (4)a -(CZ 1 Z 2 ) k -としては、-CF2-O-CF2-、-CF2-O-CF(CF3)-、-CF2-OC(CF3)2-、-CF2-O-CF2-CF2-、-CF2-O-CF2-CF(CF3)-、-CF2-O-CF2-C(CF3)2-、-CF2-O-CF2CF2-CF2-、-CF2-O-CF2CF2-CF (CF3)-、-CF2-O-CF2CF2-C(CF3)2-、-CF2-O-CF(CF3)-CF2-、-CF2-O-CF(CF3)-CF(CF 3)-、-CF2-O-CF(CF3)-C(CF3)2-、-CF2-O-CF(CF3)-CF2-、-CF2-O-CF(CF3)-CF(CF3) -、-CF2-O-CF(CF3)-C(CF3)2-、-CF2-O-CF(CF3)CF2-CF2-、-CF2-O-CF(CF3)CF2-CF( CF3)-、-CF2-O-CF(CF3)CF2-C(CF3)2-、-CF2-O-CF(CF3)CF2-O-CF2-、-CF2-O-CF(CF 3)CF2-O-CF(CF3)-、-CF2-O-CF(CF3)CF2-OC(CF3)2-、-(C=O)-、-(C=O)-O-、-(C=O)- (CH2)-、-(C=O)-(CF2)-、-(C=O)-O-(CH2)-、-(C=O)-O-(CF2)-、-(C=O)-[(CH2)2-O] n -(CH2)-、-(C=O)-[(CF2)2-O] n -(CF2)-、-(C=O)-[(CH2)2-O] n -(CH2)-(CH2)-、-(C=O)-[(CF2)2-O] n -(CF2)-(CF2)-、-(C=O)-O[(CH2)2-O] n -(CF2)-、-(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-、-(C=O)-O[(CF2)2-O] n -(CF2)-、-(C=O)-O[(CF2)2-O] n-(CF2)-(CF2)-, -(C=O)-(CH2)2-O-(CH2)-(CH2)-, -(C=O)-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-(CH2)-, -(C=O )-O-(CF2)2-O-(CF2)-(CF2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2-, -(C=O)-O-(CF2)2-O-(CF2)-C(CF3)2-, or -(C=O)-O-C6H4- C(CF3)2- is preferred, -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(C F3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, -(C=O)-, -(C=O)-O-(CH2)-, -(C=O)-O-(CH2)-(CH2)-, -(C=O)-O[(CH2)2-O] n -(CH2)-(CH2)-, -(C=O)-O-(CH2)2-O-(CH2)-C(CF3)2- or -(C=O)-O-C6H4-C(CF3)2- are more preferred. In the above formula, n is an integer of 1-10.

[0078] Specific examples of the compound represented by formula (4) include: [ka] (In the formula, X j and Y 3 is the same as above. n is an integer from 1 to 10.

[0079] R a As the general formula (r1): -(C=O) h -(O) i -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6are each independently H, F or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1), and a divalent group represented by the general formula (r2): -(C=O) h -(O) i -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, and i is 0 or 1.) is also preferred.

[0080] -R in general formula (4) a -(CZ 1 Z 2 ) k - may also be represented by the following formula (t1): -(C=O) h -(O) i -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (t1) (In the formula, X 6 are each independently H, F, or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z 1 and Z 2 are each independently F or CF3), and in formula (t1), Z 1 and Z 2 More preferably, one is F and the other is CF3. In addition, in the general formula (4), -R a -(CZ 1 Z 2 ) k - is represented by the following formula (t2): -(C=O) h -(O) i-CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (t2) (In the formula, X 7 are each independently H, F, or CF3, e is an integer of 0 to 3, g is 0 or 1, h is 0 or 1, i is 0 or 1, and Z 1 and Z 2 are each independently F or CF3), and in the formula (t2), Z 1 and Z 2 More preferably, one is F and the other is CF3.

[0081] The compound represented by the general formula (4) is a hydrophilic group (Y 3 ), it is also preferable that the compound has a C—F bond and does not have a C—H bond. That is, in the general formula (4), i , X j , and X k All of the are F and R a is preferably a perfluoroalkylene group having 1 or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be either cyclic or noncyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0082] The compound represented by the general formula (4) may be partially fluorinated. That is, the compound represented by the general formula (4) may have a hydrophilic group (Y 3 ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0083] The compound represented by the general formula (4) is also preferably a compound represented by the following formula (4a): CF2=CF-O-Rf 0 -Y 3 (4a) (In the formula, Y3 is a hydrophilic group, and Rf 0 is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0084] The compound represented by the general formula (4) is also preferably a compound represented by the following formula (4b). CH2=CH-O-Rf 0 -Y 3 (4b) (In the formula, Y 3 is a hydrophilic group, and Rf 0 is a perfluorinated divalent linking group defined by formula (4a).

[0085] In the general formula (4), Y 3 In one preferred embodiment, Y is -OSO3M. 3 is -OSO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), and the like. In the above formula, M is the same as above.

[0086] In the general formula (4), Y 3 Another preferred form is -SO3M. 3When is -SO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CH2=CH(CF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH(CF2CF2SO3M), CH2=CH((CF2)3SO3M), etc. In the above formula, M is the same as above.

[0087] In the general formula (4), Y 3 It is also a preferred form for Y to be -COOM. 3 is -COOM, the compound represented by the general formula (4) is, for example, CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) n COOM) (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH(CF2CF2COOM), CH2=CH((CF2)3COOM), CF2=CF(OCF2CF2SO2NR'CH2COOM), CF2=CF(O(CF2)4SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)SO2NR'CH2COOM), CF2=CF(OCF2 CF(CF3)OCF2CF2SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)3SO2NR'CH2COOM), etc. In the above formula, R' is H or C 1-4 is an alkyl group, and M is the same as above.

[0088] In the general formula (4), Y 3 In another preferred embodiment, Y is -OPO3M or -OP(O)(OM)2. 3 is -OPO3M or -OP(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OP(O)(OM)2), CF2=CF(O(CF2)4CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OP(O)(OM)2), CF2=CF(OCF2CF2S O2N(CH3)CH2CH2OP(O)(OM)2), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)4CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)3CH2OP(O)(OM)2), etc. In the above formula, M is the same as above.

[0089] In the general formula (4), Y 3 In another preferred embodiment, Y is -PO3M or -P(O)(OM)2. 3 is -PO3M or -P(O)(OM)2, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2P(O)(OM)2), CF2=CF(O(CF2)4P(O)(OM)2), CF2=CF(OCF2CF(CF3)P(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)4P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), and CH2=CH((CF2)3P(O)(OM)2), and the like, where M is the same as above.

[0090] The compound represented by the general formula (4) includes the compound represented by the general formula (5): CX2=CY(-CZ2-O-Rf-Y 3 ) (5) (In the formula, X may be the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z may be the same or different and is -H, -F, an alkyl group or a fluorine-containing alkyl group. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms. Y 3 is the same as above.) A monomer represented by general formula (6): CX2=CY(-O-Rf-Y 3 ) (6) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above.) and a monomer represented by general formula (7): CX2=CY(-Rf-Y 3 ) (7) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. Y 3 is the same as above. The above-mentioned fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0091] In general formula (5), X is -H or -F. Both X's may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both X's may be -H.

[0092] In formula (5), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0093] In formula (5), Z may be the same or different and is -H, -F, an alkyl group or a fluoroalkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[0094] In the general formula (5), it is preferable that at least one of X, Y and Z contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0095] In the general formula (5), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. Also, the number is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0096] The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, and even more preferably 12 or less. Examples of the fluorine-containing alkylene group having an ether bond include a group represented by the following formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0097] In the general formula (5), Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7y are H or an organic group and may be the same or different. Any two of them may be bonded to each other to form a ring. R 7y The organic group in is preferably an alkyl group. R 7y As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. The above M is -H, a metal atom, or -NR 7y 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7y 4 is more preferred, -H, -Na, -K, -Li or -NH4 is even more preferred, -Na, -K or -NH4 is even more preferred, -Na or -NH4 is especially preferred, and -NH4 is most preferred. Above Y 3 As the alkyl group, -COOM or -SO3M is preferable, and -COOM is more preferable.

[0098] The monomer represented by the general formula (5) is preferably a monomer represented by the general formula (5a). CH2=CF(-CF2-O-Rf-Y 3 ) (5a) (Wherein, Rf and Y 3 is the same as above.)

[0099] Specific examples of the monomer represented by the general formula (5a) include those represented by the following formula:

[0100] [ka]

[0101] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F or CF3; p1+q1+r1 are integers between 0 and 10; s1 is 0 or 1; t1 is an integer between 0 and 5; Y 3 is the same as above, except for Z 3 and Z 4 are both H, then p1+q1+r1+s1 is not 0). More specifically,

[0102] [ka]

[0103] The following are preferred, among which:

[0104] [ka]

[0105] It is preferable that:

[0106] The monomer represented by the general formula (5a) is, for example, Y 3 is preferably -COOM, and particularly preferably at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above), and more preferably CH2=CFCF2OCF(CF3)COOM.

[0107] The monomer represented by the general formula (5) is preferably a monomer represented by the general formula (5b). CX 2 2 = CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y 3 (5b) (In the formula, each 2 are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, Y 3 is the same as the above definition.)

[0108] In the general formula (5b), n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in that PTFE particles having a small primary particle size can be obtained. 3 is preferably -COOM in that it provides suitable water solubility and surface activity, and the above M is preferably H or NH4 in that it is less likely to remain as an impurity and improves the heat resistance of the resulting composition and the drawn body obtained from the composition. The polymer (5) may be a homopolymer of the fluoroallyl ether compound represented by the general formula (5b) or a copolymer with other monomers.

[0109] Examples of the perfluorovinyl alkyl compound represented by the above formula (5b) include CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above).

[0110] Further, examples of the monomer represented by the general formula (5) include a monomer represented by the general formula (5c).

[0111] CF2=CFCF2-O-Rf-Y 3 (5c) (Wherein, Rf and Y 3 is the same as above)

[0112] More specifically, [ka] etc.

[0113] In general formula (6), X is -H or -F. Both X's may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both X's may be -H.

[0114] In formula (6), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0115] In the general formula (6), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0116] In the general formula (6), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0117] The monomer represented by the general formula (6) is preferably at least one selected from the group consisting of monomers represented by the general formulae (6a), (6b), (6c), (6d) and (6e). CF2=CF-O-(CF2) n1 -Y 3 (6a) (In the formula, n1 represents an integer of 1 to 10, and Y 3 is -COOM, -SO3M or -OSO3M (M is H, a metal atom, NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7y are H or an organic group and may be the same or different. Any two of them may be bonded to each other to form a ring. CF2=CF-O-(CF2C(CF3)F) n2 -Y 3 (6b) (In the formula, n2 represents an integer of 1 to 5; Y 3 is the same as the above definition.) CF2=CF-O-(CFX 1 ) n3 -Y 3 (6c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, Y 3 is the same as the above definition.) CF2=CF-O-(CF2CFX 1 O) n4 -(CF2) n6 -Y 3 (6d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and Y 3 and X 1 is the same as the above definition.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-Y 3 (6e) (In the formula, n5 represents an integer of 0 to 10, and Y 3 and X 1 is the same as the above definition.)

[0118] In the formula (6a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less.3 is preferably -COOM in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0119] Examples of the monomer represented by the above formula (6a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), and CF2=CF(OCF2CF2CF2COOM) (wherein M is as defined above).

[0120] In the above formula (6b), n2 is preferably an integer of 3 or less from the viewpoint of the stability of the resulting aqueous dispersion, and Y 3 is preferably -COOM in that it provides suitable water solubility and stability of the aqueous dispersion, and M is preferably H or NH4 in that it is less likely to remain as an impurity and improves the heat resistance of the resulting molded article.

[0121] In the above formula (6c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM in terms of obtaining suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4 in terms of improving dispersion stability.

[0122] In the above formula (6d), the above X 1 is preferably -CF3 from the viewpoint of stability of the aqueous dispersion, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, and Y 3 is preferably -COOM in that it provides suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0123] Examples of the monomer represented by the above formula (6d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, and CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM (wherein M represents H, NH4, or an alkali metal).

[0124] In the general formula (6e), the n5 is preferably an integer of 5 or less in terms of water solubility, and the Y 3 is preferably -COOM in that it provides suitable water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0125] An example of the monomer represented by general formula (6e) is CF2=CFOCF2CF2CF2COOM (wherein M represents H, NH4 or an alkali metal).

[0126] In general formula (7), Rf is preferably a fluorine-containing alkylene group having a carbon number of 1 to 40. In general formula (7), at least one of X and Y preferably contains a fluorine atom.

[0127] The monomer represented by general formula (7) is represented by general formula (7a): CF2=CF-(CF2) n1 -Y 3 (7a) (In the formula, n1 represents an integer of 1 to 10, and Y 3 is the same as defined above.) and a monomer represented by general formula (7b): CF2=CF-(CF2C(CF3)F) n2 -Y 3 (7b) (In the formula, n2 represents an integer of 1 to 5; Y 3 is as defined above. Preferably, at least one selected from the group consisting of monomers represented by Above Y 3 is preferably -SO3M or -COOM, where M is H, a metal atom, NR 7y4. It is preferable that the R is an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7y represents H or an organic group. 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.

[0128] In the formula (7a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. 3 is preferably -COOM in that it provides suitable water solubility and surface activity, and M is preferably H or NH4 in that it is less likely to remain as an impurity and improves the heat resistance of the resulting composition and the drawn body obtained from the composition.

[0129] An example of the perfluorovinyl alkyl compound represented by the above formula (7a) is CF2=CFCF2COOM (wherein M is as defined above).

[0130] In the above formula (7b), n2 is preferably an integer of 3 or less, since this allows the production of PTFE particles having a small primary particle size, and Y 3 is preferably -COOM in that it provides suitable water solubility and surface activity, and M is preferably H or NH4 in that it is less likely to remain as an impurity and improves the heat resistance of the resulting composition and the drawn body obtained from the composition.

[0131] The above-mentioned modified monomer preferably includes modified monomer (A), and preferably includes at least one selected from the group consisting of compounds represented by general formula (5a), general formula (5c), general formula (6a), general formula (6b), general formula (6c), and general formula (6d), and more preferably includes a compound represented by general formula (5a) or general formula (5c).

[0132] When the modified monomer contains the modified monomer (A), the content of the modified monomer (A) unit is preferably in the range of 0.00001 to 1.0 mass% based on the total polymerized units of PTFE. The lower limit is more preferably 0.0001 mass%, further preferably 0.0005 mass%, further more preferably 0.001 mass%, and particularly preferably 0.005 mass%. The upper limit is, in order of preference, 0.90 mass%, 0.50 mass%, 0.40 mass%, 0.30 mass%, 0.20 mass%, 0.15 mass%, 0.10 mass%, 0.08 mass%, 0.05 mass%, and 0.01 mass%.

[0133] In the present disclosure, the content of each monomer unit constituting PTFE can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer. In addition, the content of each monomer unit constituting PTFE can also be calculated from the amount of modified monomer added used in polymerization.

[0134] The aspect ratio of the primary particle of the PTFE is preferably less than 2.00, more preferably 1.90 or less, even more preferably 1.80 or less, even more preferably 1.70 or less, especially preferably 1.60 or less, and particularly preferably 1.50 or less. The aspect ratio is more preferably 1.45 or less, even more preferably 1.40 or less, even more preferably 1.35 or less, especially preferably 1.30 or less, particularly preferably 1.20 or less, and most preferably 1.10 or less. When measuring in an aqueous dispersion, the above aspect ratio is determined by observing an aqueous PTFE dispersion diluted to a solids concentration of approximately 1% by mass with a scanning electron microscope (SEM), processing the images of 400 or more particles randomly selected, and averaging the ratio of the long axis to the short axis. When measuring the aspect ratio in powder form, the PTFE powder is irradiated with an electron beam, then added to an aqueous fluorosurfactant solution, and redispersed by ultrasonic waves to obtain an aqueous PTFE dispersion. The aspect ratio is determined from this aqueous PTFE dispersion in the same manner as in the aqueous dispersion.

[0135] That is, when the aspect ratio of PTFE is measured using an aqueous PTFE dispersion, an aqueous PTFE dispersion adjusted to have a polymer solid content of about 1.0% by mass is prepared, observed with a scanning electron microscope (SEM), and randomly selected 400 or more particles are subjected to image processing, and the aspect ratio can be calculated from the average ratio of the long diameter to the short diameter. When the aspect ratio of PTFE is measured using a powder of PTFE, the PTFE powder is irradiated with an electron beam, then added to an aqueous solution of a fluorine-containing surfactant, and ultrasonic waves are applied to redisperse the powder in the aqueous solution to prepare an aqueous PTFE dispersion. The aspect ratio can be calculated by the above-mentioned method using the aqueous dispersion thus prepared.

[0136] The PTFE preferably has an endothermic peak temperature in the range of 333 to 347° C. More preferably, it is 335° C. or higher and 345° C. or lower. The endothermic peak temperature is the temperature corresponding to the maximum value on the heat of fusion curve when PTFE that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[0137] The endothermic peak temperature of PTFE can be measured using a TG / DTA (thermogravimetric / differential thermal analyzer) by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and measuring it. The endothermic peak temperature can be determined as the temperature corresponding to the maximum value in a differential thermal (DTA) curve obtained by heating the aluminum pan in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C / min.

[0138] The PTFE is preferably one that has no history of being heated at a temperature equal to or higher than the first endothermic peak temperature. The PTFE may be unsintered or semi-sintered. From the viewpoint of simple process or easy control of thickness and pore size, unsintered PTFE is preferred. For example, when producing a biaxially stretched membrane from the composition of the present disclosure, semi-sintered PTFE is preferred from the viewpoint of increasing the strength of the biaxially stretched membrane or reducing the pore size. As an example of unsintered PTFE, as-polymerized PTFE can be mentioned. The above-mentioned unsintered PTFE refers to PTFE that has no history of being heated to a temperature equal to or higher than the secondary endothermic peak temperature, and the semi-sintered PTFE refers to PTFE that has no history of being heated to a temperature equal to or higher than the primary endothermic peak temperature, and that has been heated to a temperature equal to or lower than the primary endothermic peak temperature and equal to or higher than the secondary endothermic peak temperature. The above-mentioned first endothermic peak temperature means the maximum peak temperature of an endothermic curve appearing on a crystal melting curve when unsintered PTFE is measured by a differential scanning calorimeter. The second endothermic peak temperature means the maximum peak temperature of the endothermic curve appearing on the crystal melting curve when PTFE heated to a temperature equal to or higher than the first endothermic peak temperature (for example, 360°C) is measured by a differential scanning calorimeter. In the present disclosure, the endothermic curve was obtained by using a differential scanning calorimeter and raising the temperature at a heating rate of 10° C. / min.

[0139] The PTFE may have a core-shell structure. The core-shell structure is a conventionally known structure, and is a structure of primary particles in an aqueous dispersion that can be produced by the method described in U.S. Patent No. 6,841,594. Examples of PTFE having a core-shell structure include a core-shell structure comprising a core portion of a TFE homopolymer and a shell portion of a modified PTFE, a core-shell structure comprising a core portion of a modified PTFE and a shell portion of a TFE homopolymer, and a core-shell structure comprising a core portion of modified PTFE and a shell portion of modified PTFE having a different monomer composition from the modified PTFE constituting the core portion. The PTFE having the core-shell structure can be obtained, for example, by first polymerizing TFE and, if necessary, a modified monomer to produce a core portion (TFE homopolymer or modified PTFE), and then polymerizing TFE and, if necessary, a modified monomer to produce a shell portion (TFE homopolymer or modified PTFE). The above-mentioned shell portion means a portion constituting a predetermined thickness from the surface of the PTFE primary particle to the inside of the particle, and the core portion means a portion constituting the inside of the shell portion.

[0140] In the present disclosure, the core-shell structure includes all of the following: (1) a core portion and a shell portion having different monomer compositions; (2) a core portion and a shell portion having the same monomer composition and different number average molecular weights; and (3) a core portion and a shell portion having different monomer compositions and different number average molecular weights.

[0141] When the shell portion is modified PTFE, the content of the modifying monomer in the shell portion is preferably 0.0001 to 1% by mass, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more, and more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less.

[0142] When the core part is modified PTFE, the content of the modifying monomer in the core part is preferably 0.00001 to 1.0% by mass, more preferably 0.0001% by mass or more, and even more preferably 0.001% by mass or more, and more preferably 0.50% by mass or less, and even more preferably 0.30% by mass or less.

[0143] The PTFE has an average primary particle diameter of 500 nm or less, more preferably 400 nm or less, and even more preferably 350 nm or less. The relatively small average primary particle diameter of the primary particles allows the polymerization of TFE in an aqueous medium to proceed smoothly, and PTFE can be easily produced. The relatively small average primary particle diameter of the primary particles can be obtained, for example, by adding a modified monomer to the polymerization system at the beginning of the polymerization of TFE. The lower limit of the average primary particle diameter is not particularly limited, but may be, for example, 50 nm or 100 nm. From the viewpoint of molecular weight, it is preferably 100 nm or more, and more preferably 150 nm or more.

[0144] The average primary particle size of the PTFE primary particles can be measured by dynamic light scattering. First, a PTFE aqueous dispersion with a polymer solids concentration adjusted to about 1.0 mass% is prepared, and the average primary particle size can be measured using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and an accumulation number of 70. For example, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for the dynamic light scattering method.

[0145] The PTFE may have a thermal instability index (TII) of 20 or more. The thermal instability index (TII) of PTFE can be adjusted to within the above range, for example, by producing PTFE using polymer (I). The TII is preferably 25 or more, more preferably 30 or more, and even more preferably 35 or more. It is particularly preferably 40 or more. The TII is measured in accordance with ASTM D 4895-89.

[0146] The 0.1% mass loss temperature of PTFE may be equal to or lower than 400° C. The 0.1% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using polymer (I).

[0147] The 0.1% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer). The 0.1% mass loss temperature can be determined as the temperature at which the mass has decreased by 0.1% by mass when the aluminum pan is heated in the air in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0148] The 1.0% mass loss temperature of PTFE may be equal to or lower than 492° C. The 1.0% mass loss temperature of PTFE can be adjusted to fall within the above range, for example, by producing PTFE using the polymer (I).

[0149] The 1.0% mass loss temperature can be measured by precisely weighing out about 10 mg of PTFE powder that has not been heated to a temperature of 300°C or higher, placing it in a dedicated aluminum pan, and using a TG / DTA (thermogravimetric / differential thermal analyzer). The 1.0% mass loss temperature can be determined as the temperature at which the mass has decreased by 1.0% by mass when the aluminum pan is heated in an air atmosphere in the temperature range from 25°C to 600°C at a rate of 10°C / min.

[0150] The composition of the present disclosure contains a polymer (I) containing polymerized units (I) based on a monomer represented by general formula (I). The polymer (I) preferably contains two or more polymerized units (I). CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; A 0 is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more. X 2 is preferably F, Cl, H or CF3. 1 and Z 2 As the substituent, F or CF3 is preferable.

[0151] In the present disclosure, the anionic group includes functional groups that provide an anionic group, such as a sulfate group, a carboxylate group, an acid group such as -COOH, an acid salt group such as -COONH4, etc. The anionic group includes a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or a -C(CF3)2OM (wherein M is -H, a metal atom, -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.) is preferred, with a sulfate group, a carboxylate group, a phosphate group, a phosphonate group or a sulfonate group being more preferred.

[0152] The polymer (I) may contain only polymerization units (I) based on one type of monomer represented by general formula (I), or may contain polymerization units (I) based on two or more types of monomers represented by general formula (I).

[0153] R is a linking group. In the present disclosure, the "linking group" is a (m+1)-valent linking group, and when m is 1, it is a divalent linking group. The linking group may be a single bond, and preferably contains at least one carbon atom, and the number of carbon atoms may be 2 or more, 4 or more, 8 or more, 10 or more, or 20 or more. There is no upper limit, but it may be, for example, 100 or less, or 50 or less.

[0154] The linking group may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and may optionally contain one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen, and may optionally contain one or more functional groups selected from the group consisting of esters, amides, sulfonamides, carbonyls, carbonates, urethanes, ureas, and carbamates. The linking group may not contain carbon atoms, but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[0155] m is an integer of 1 or more, preferably 1 or 2, and more preferably 1. When m is an integer of 2 or more, Z 1 , Z 2 and A 0 may be the same or different. Next, a preferred structure when m is 1 in general formula (I) will be described.

[0156] R is preferably a catenary heteroatom such as oxygen, sulfur, or nitrogen, or a divalent organic group.

[0157] When R is a divalent organic group, the hydrogen atom bonded to the carbon atom may be replaced with a halogen other than fluorine, such as chlorine, and may or may not contain a double bond. R may be either linear or branched, and may be either cyclic or acyclic. R may also contain a functional group (e.g., ester, ether, ketone, amine, halide, etc.).

[0158] R may also be a non-fluorinated divalent organic group, or a partially fluorinated or perfluorinated divalent organic group.

[0159] R may be, for example, a hydrocarbon group in which no fluorine atoms are bonded to the carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or a hydrocarbon group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, and these may contain an oxygen atom, a double bond, or a functional group.

[0160] R is preferably a hydrocarbon group having 1 to 100 carbon atoms which may contain an ether bond, and in the hydrocarbon group, some or all of the hydrogen atoms bonded to the carbon atoms may be substituted with fluorine.

[0161] R is preferably -(CH2) a -, -(CF2) a -, -O-(CF2) a -, -(CF2) a -O-(CF2) b -, -O(CF2) a -O-(CF2) b -, -(CF2) a -[O-(CF2) b ] c -, -O(CF2) a -[O-(CF2) b ] c -,-[(CF2) a -O] b -[(CF2) c -O] d -, -O[(CF2) a -O] b -[(CF2) c -O] d -, -O-[CF2CF(CF3)O] a -(CF2) b -, -[CF2CF(CF3)O] a -, -[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -, -(CF2) a -O-[CF(CF3)CF2O] a -(CF2) b- and at least one selected from combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may be independently 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[0162] R is represented by the following general formula (r1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g - (r1) (In the formula, X 6 are each independently H, F or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, and g is 0 or 1), and is preferably a divalent group represented by the following general formula (r2): -CF2-O-(CX 7 2) e -(O) g - (r2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, and g is 0 or 1), and a divalent group represented by the following formula is preferred.

[0163] Specific examples of suitable R include -CF2-O-, -CF2-O-CF2-, -CF2-O-CH2-, -CF2-O-CH2CF2-, -CF2-O-CF2CF2-, -CF2-O-CF2CH2-, -CF2-O-CF2CF2CH2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2-O-CF(CF3)CF2-O-, -CF2-O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CH2-, and the like. Among these, the above R is preferably a perfluoroalkylene group which may contain an oxygen atom, specifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, or -CF2-O-CF(CF3)CF2-O-.

[0164] -R-CZ of the above general formula (I) 1 Z 2 - is represented by the following formula (s1): -CF2-O-(CX 6 2) e -{O-CF(CF3)} f -(O) g -CZ 1 Z 2 - (s1) (In the formula, X 6 are each independently H, F, or CF3, e is an integer of 0 to 3, f is an integer of 0 to 3, g is 0 or 1, and Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s1), Z 1 and Z 2 More preferably, each is F or CF3, and even more preferably, one is F and the other is CF3.

[0165] In addition, in the general formula (I), -R-CZ 1 Z 2 - is represented by the following formula (s2): -CF2-O-(CX 7 2) e -(O) g -CZ 1 Z 2 - (s2) (In the formula, X 7 are each independently H, F or CF3, e is an integer of 0 to 3, g is 0 or 1, and Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group), and in formula (s2), Z 1 and Z 2 More preferably, each is F or CF3, and even more preferably, one is F and the other is CF3.

[0166] -R-CZ of general formula (I) 1 Z 2- as -CF2-O-CF2-, -CF2-O-CF(CF3)-, -CF2-OC(CF3)2-, -CF2-O-CF2-CF2-, -CF2-O-CF2-C F(CF3)-, -CF2-O-CF2-C(CF3)2-, -CF2-O-CF2CF2-CF2-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-C F2CF2-C(CF3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF 3)2-, -CF2-O-CF(CF3)-CF2-, -CF2-O-CF(CF3)-CF(CF3)-, -CF2-O-CF(CF3)-C(CF3)2-, -CF2- O-CF(CF3)CF2-CF2-, -CF2-O-CF(CF3)CF2-CF(CF3)-, -CF2-O-CF(CF3)CF2-C(CF3)2-, -CF2- O-CF(CF3)CF2-O-CF2-, -CF2-O-CF(CF3)CF2-O-CF(CF3)-, or -CF2-O-CF(CF3)CF2-OC(CF3)2 - is preferred, -CF2-O-CF(CF3)-, -CF2-O-CF2-CF(CF3)-, -CF2-O-CF2CF2-CF(CF3)-, -CF2-O-CF(CF 3) -CF(CF3)-, -CF2-O-CF(CF3)CF2-CF(CF3)-, or -CF2-O-CF(CF3)CF2-O-CF(CF3)- is more preferred.

[0167] It is also preferred that the polymer (I) is highly fluorinated. For example, the polymer (I) may contain anionic groups (A) such as phosphate moieties (e.g., CH2OP(O)(OM)2) and sulfate moieties (e.g., CH2OS(O)2OM). 0 ), it is preferred that 80% or more, 90% or more, 95% or more, or 100% of the C-H bonds in the polymer (I) are substituted with C-F bonds.

[0168] The polymer (I) contains an anionic group (A 0 ), it is also preferable that the compound has a C-F bond and does not have a C-H bond. That is, in the general formula (I), 1 , X 2 , and X3 are all F, and R is preferably a perfluoroalkylene group having 1 or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be either cyclic or noncyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0169] The polymer (I) may be partially fluorinated. That is, the polymer (I) may have an anionic group (A 0 ), it is also preferred that the alkyl group has at least one hydrogen atom bonded to a carbon atom and at least one fluorine atom bonded to a carbon atom.

[0170] Anionic group (A 0 ) may be -SO3M, -OSO3M, -COOM, -SON2NR'CH2COOM, -CH2OP(O)(OM)2, [-CH2O]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CH2O]2P(O)(OM), -CH2CH2OSO3M, -P(O)(OM)2, -SON2NR'CH2CH2OP(O)(OM)2, [-SON2NR'CH2CH2O]2P(O)(OM), -CH2OSO3M, -SON2NR'CH2CH2OSO3M, or -C(CF3)2OM. Among these, -SO3M, -COOM, or -P(O)(OM)2 is preferred, -SO3M or -COOM is more preferred, and -COOM is even more preferred.

[0171] M is H, a metal atom, or NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7 is H or an organic group.

[0172] The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li.

[0173] M is -H, a metal atom, or -NR7 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7 4 is more preferred, -H, -Na, -K, -Li or -NH4 is even more preferred, -Na, -K or -NH4 is even more preferred, -Na or -NH4 is especially preferred, and -NH4 is most preferred.

[0174] In the polymer (I), each polymer unit (I) may have a different anionic group or may have the same anionic group.

[0175] The polymer (I) is also preferably a polymer containing a polymer unit (Ia) based on a monomer represented by the following formula (Ia). CF2=CF-O-Rf 0 -A 0 (Ia) (In the formula, A 0 is an anionic group, and Rf 0 is a perfluorinated divalent linking group which may be linear or branched, cyclic or acyclic in structure, saturated or unsaturated, substituted or unsubstituted, and which optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, and nitrogen.

[0176] The above polymer (I) is also preferably a polymer containing polymerized units (Ib) based on a monomer represented by the following formula (Ib). CH2=CH-O-Rf 0 -A 0 (Ib) (In the formula, A 0 is an anionic group, and Rf 0 is a perfluorinated divalent linking group defined by formula (Ia).

[0177] In the general formula (I), A 0 is a sulfate group. 0 is, for example, -CH2OSO3M, -CH2CH2OSO3M, or -SO2NR'CH2CH2OSO3M, where R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0178] A 0 is a sulfate group, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), and the like. In the above formula, M is the same as above.

[0179] In the general formula (I), A 0 In one preferred embodiment, A is a sulfonate group. 0 An example is -SO3M, where M is the same as above.

[0180] A 0 is a sulfonate group, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2SO3M), CF2=CF(O(CF2)3SO3M), CF2=CF(O(CF2)4SO3M), CF2=CF(OCF2CF(CF3)SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2SO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO3M), CH2=CH((CF2)4SO3M), CH2=CH(CF2CF2SO3M), CH2=CH((CF2)3SO3M), etc. In the above formula, M is the same as above.

[0181] In the general formula (I), A 0 In one preferred embodiment, A is a carboxylate group. 0Examples of the alkyl group include COOM and SO2NR'CH2COOM, where R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above. 0 is a carboxylate group, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2COOM), CF2=CF(O(CF2)3COOM), CF2=CF(O(CF2)4COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) n COOM) (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH(CF2CF2COOM), CH2=CH((CF2)3COOM), CF2=CF(OCF2CF2SO2NR'CH2COOM), CF2=CF(O(CF2)4SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)SO2NR'CH2COOM), CF2=CF(OCF2 CF(CF3)OCF2CF2SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CF2=CF(OCF2CF(CF3)OCF2CF2CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), CH2=CH(CF2CF2SO2NR'CH2COOM), CH2=CH((CF2)4SO2NR'CH2COOM), etc. In the above formula, R' is H or an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0182] In the general formula (I), A 0 In one preferred embodiment, A is a phosphate group. 0 Examples of such a group include -CH2OP(O)(OM)2, [-CH2O]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CH2O]2P(O)(OM), [-SO2NR'CH2CH2O]2P(O)(OM) or -SO2NR'CH2CH2OP(O)(OM), where R' is an alkyl group having 1 to 4 carbon atoms, and M is the same as above.

[0183] A0 is a phosphate, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2CH2OP(O)(OM)2), CF2=CF(O(CF2)4CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)CH2OP(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OP(O)(OM)2), CF2=CF(OCF2CF2SO2N(CH3 )CH2CH2OP(O)(OM)2), CF2=CF(OCF2CF2CF2CF2SO2N(CH3)CH2CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)4CH2OP(O)(OM)2), CH2=CH(CF2CF2CH2OP(O)(OM)2), CH2=CH((CF2)3CH2OP(O)(OM)2), etc. In the above formula, M is the same as above.

[0184] In the general formula (I), A 0 In one preferred embodiment, A is a phosphonate group. 0 is a phosphonate group, examples of the monomer represented by general formula (I) include CF2=CF(OCF2CF2P(O)(OM)2), CF2=CF(O(CF2)4P(O)(OM)2), CF2=CF(OCF2CF(CF3)P(O)(OM)2), CF2=CF(OCF2CF(CF3)OCF2CF2P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)4P(O)(OM)2), CH2=CH(CF2CF2P(O)(OM)2), CH2=CH((CF2)3P(O)(OM)2), where M is the same as above.

[0185] The above polymer (I) is preferably a polymer (1) containing polymerized units (1) based on a monomer represented by the following general formula (1). CX2=CY(-CZ2-O-Rf-A) (1) (In the formula, X may be the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Z may be the same or different and is -H, -F, an alkyl group or a fluoroalkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having 2 to 100 carbon atoms and having an ether bond; A is -COOM, -SO3M, -OSO3M or C(CF3)2OM (M is -H, a metal atom, -NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7 is H or an organic group, provided that at least one of X, Y, and Z contains a fluorine atom. By including the polymer (1), the composition of the present disclosure containing polytetrafluoroethylene can be produced stably and efficiently. Also, a composition containing high molecular weight polytetrafluoroethylene can be obtained in high yield.

[0186] The above-mentioned fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0187] In the above general formula (1), X is -H or -F. Both X's may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both X's may be -H.

[0188] In the above general formula (1), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0189] In the above general formula (1), Z may be the same or different and is -H, -F, an alkyl group or a fluoroalkyl group. The alkyl group is an alkyl group containing no fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has a carbon number of at most 6, more preferably at most 4, and even more preferably at most 3. The above-mentioned fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and the carbon number may be at least 1. The above-mentioned fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[0190] In the above general formula (1), at least one of X, Y and Z contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0191] In the above general formula (1), the above Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond. The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0192] The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The carbon number of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, and even more preferably 12 or less. For example, the following formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0193] In the above general formula (1), A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is -H, a metal atom, -NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7 is H or an organic group. R 7 As the 1-10 is preferably an organic group represented by the formula: 1-4 More preferred is an organic group represented by the formula: 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. The above M is -H, a metal atom, or -NR7 4 is preferred, and -H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or -NR 7 4 is more preferred, -H, -Na, -K, -Li or -NH4 is even more preferred, -Na, -K or -NH4 is even more preferred, -Na or -NH4 is especially preferred, and -NH4 is most preferred. The above A is preferably -COOM or -SO3M, and more preferably -COOM.

[0194] The monomer represented by the general formula (1) may, for example, be a monomer represented by the following formula (1a): CX2 = CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-A (1a) (wherein each X is the same and represents F or H, n5 represents 0 or an integer of 1 to 10, and A is as defined above). In the above formula (1a), the above n5 is preferably 0 or an integer from 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in that PTFE particles having a small primary particle size can be obtained, and is preferably 0, 1 or 2, and even more preferably 0 or 1. The above A is preferably -COOM in that appropriate water solubility and surface activity can be obtained, and the above M is preferably H or NH4 in that it is less likely to remain as an impurity and the heat resistance of the obtained composition and the drawn body obtained from the composition is improved. The polymer (1) may be a homopolymer of the fluoroallyl ether compound represented by the general formula (1a) or a copolymer with other monomers.

[0195] The above polymerized units (1) are preferably polymerized units (1A) based on a monomer represented by the following general formula (1A). CH2=CF(-CF2-O-Rf-A) (1A) (In the formula, Rf and A are the same as above.) The polymer (1) may be a homopolymer of the monomer represented by the general formula (1A) or a copolymer with other monomers.

[0196] Specific examples of the monomer represented by formula (1A) include those represented by the following formula:

[0197] [ka]

[0198] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is H, F or CF3; p1+q1+r1 are integers from 0 to 10; s1 is 0 or 1; t1 is an integer from 0 to 5, except for Z 3 and Z 4 are both H, then p1+q1+r1+s1 is not 0; A is as defined above). More specifically,

[0199] [ka]

[0200] The following are preferred:

[0201] [ka]

[0202] It is preferable that:

[0203] As the monomer represented by the above general formula (1A), A in formula (1A) is preferably -COOM, and in particular, at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above) is preferred, with CH2=CFCF2OCF(CF3)COOM being more preferred.

[0204] Further, examples of the monomer represented by the general formula (1) include the monomer represented by the following formula:

[0205] CF2=CFCF2-O-Rf-A CF2=CF-Rf-A (wherein Rf and A are the same as above)

[0206] More specifically, [ka] etc.

[0207] The polymer (I) is also preferably a polymer (2) containing polymerized units (2) based on a monomer represented by general formula (2). CX2=CY(-O-Rf-A) (2) (In the formula, X is the same or different and is -H or F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms; and A is the same as defined above.)

[0208] In general formula (2), X is -H or -F. Both X's may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both X's may be -H.

[0209] In the general formula (2), Y is -H, -F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have one or more carbon atoms. The alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or less carbon atoms, more preferably four or less, and even more preferably three or less. Y is preferably -H, -F or -CF3, and more preferably -F.

[0210] In the general formula (2), it is preferable that at least one of X and Y contains a fluorine atom. For example, X may be -H, and Y and Z may be -F.

[0211] In general formula (2), Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms. The fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms is an alkylene group that does not include a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0212] The carbon number of the fluorine-containing alkylene group of Rf is preferably 2 or more. Also, it is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group.

[0213] The monomer represented by general formula (2) is preferably at least one selected from the group consisting of monomers represented by general formulae (2a), (2b), (2c), (2d) and (2e). CF2=CF-O-(CF2) n1 -A (2a) (In the formula, n1 represents an integer of 1 to 10, and A is the same as defined above.) CF2=CF-O-(CF2C(CF3)F) n2 -A (2b) (In the formula, n2 represents an integer of 1 to 5, and A is as defined above.) CF2=CF-O-(CFX 1 ) n3 -A (2c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and A is as defined above. CF2=CF-O-(CF2CFX 1 O) n4 -(CF2)n6 -A (2d) (In the formula, n4 represents an integer of 1 to 10, n6 represents an integer of 1 to 3, and A and X 1 is the same as the above definition.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-A (2e) (In the formula, n5 represents an integer of 0 to 10; A and X 1 is the same as the above definition.)

[0214] In the general formula (2a), the above n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less.

[0215] Examples of the monomer represented by general formula (2a) include CF2=CF-O-CF2COOM, CF2=CF(OCF2CF2COOM), and CF2=CF(OCF2CF2CF2COOM) (wherein M is as defined above).

[0216] In general formula (2b), n2 is preferably an integer of 3 or less from the viewpoint of the dispersion stability of the resulting composition.

[0217] In the general formula (2c), n3 is preferably an integer of 5 or less from the viewpoint of water solubility, the above A is preferably -COOM, and the above M is preferably H or NH4.

[0218] In the general formula (2d), X 1 is preferably -CF3 from the viewpoint of dispersion stability of the composition, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM, and M is preferably H or NH4.

[0219] Examples of the monomer represented by general formula (2d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, and CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM (wherein M represents H, NH4, or an alkali metal).

[0220] In general formula (2e), n5 is preferably an integer of 5 or less from the viewpoint of water solubility, A is preferably -COOM, and M is preferably H or NH4.

[0221] An example of the monomer represented by the general formula (2e) is CF2=CFOCF2CF2CF2COOM (wherein M represents H, NH4 or an alkali metal).

[0222] The polymer (I) is also preferably a polymer (3) containing polymerization units (3) based on a monomer represented by general formula (3). CX2=CY(-Rf-A) (3) (In the formula, X is the same or different and is -H or -F; Y is -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms or a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms; and A is the same as defined above.)

[0223] The fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond is an alkylene group that does not include a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0224] In general formula (3), Rf is preferably a fluorine-containing alkylene group having a carbon number of 1 to 40. In general formula (3), at least one of X and Y preferably contains a fluorine atom.

[0225] The monomer represented by the general formula (3) is represented by the general formula (3a): CF2=CF-(CF2) n1 -A (3a) (wherein n1 represents an integer of 1 to 10, and A is as defined above), and a monomer represented by general formula (3b): CF2=CF-(CF2C(CF3)F) n2 -A (3b) (wherein n2 represents an integer of 1 to 5, and A is as defined above), is preferable.

[0226] In the general formula (3a) and the general formula (3b), A is preferably -SO3M or -COOM, and M is H, a metal atom, NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent is preferable. 7 represents H or an organic group.

[0227] In general formula (3a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. A is preferably -COOM, and M is preferably H or NH4.

[0228] An example of the monomer represented by the general formula (3a) is CF2=CFCF2COOM (wherein M is as defined above).

[0229] In general formula (3b), n2 is preferably an integer of 3 or less from the viewpoint of dispersion stability of the resulting composition, A is preferably -COOM, and M is preferably H or NH4.

[0230] Next, a preferred configuration in which m in general formula (I) is an integer of 2 or more will be described.

[0231] It is also preferable that the polymer (I) is a polymer (4) containing polymerization units (4) based on at least one monomer selected from the group consisting of monomers represented by general formula (4a) and general formula (4b). CF2=CF-CF2-OQ F1-CF(-Q F2 -CZ 1 Z 2 -A)2(4a) (In the formula, Z 1 , Z 2 and A is the same as above, Q F1 and Q F2 are the same or different and each is a single bond, a fluorine-containing alkylene group which may contain an ether bond between carbon atoms, or a fluorine-containing oxyalkylene group which may contain an ether bond between carbon atoms. CF2=CF-OQ F1 -CF(-Q F2 -CZ 1 Z 2 -A)2(4b) (In the formula, Z 1 , Z 2 , A, Q F1 and Q F2 is the same as above)

[0232] As the monomers represented by the general formula (4a) and the general formula (4b), [ka] etc.

[0233] The polymer (I) is preferably at least one selected from the group consisting of the polymer (1), the polymer (2) and the polymer (3), and more preferably the polymer (1).

[0234] The polymer (I) may be a homopolymer consisting of only the polymerized unit (I), or may be a copolymer containing the polymerized unit (I) and a polymerized unit based on another monomer copolymerizable with the monomer represented by the general formula (I). From the viewpoint of solubility in the polymerization medium, a homopolymer consisting of only the polymerized unit (I) is preferred. The polymerized unit (I) may be the same or different in each occurrence, and the polymer (I) may contain two or more different polymerized units (I) based on the monomer represented by the general formula (I).

[0235] The other monomers are preferably fluorine-containing ethylenic monomers having 2 or 3 carbon atoms, such as CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-form), CHF=CHCF3 (Z-form), etc. Among them, in terms of good copolymerizability, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and vinylidene fluoride (CH2=CF2) is preferred, and tetrafluoroethylene is more preferred. Therefore, the polymerization units based on the other monomer are preferably polymerization units based on tetrafluoroethylene. The polymerization units based on the other monomer may be the same or different in each occurrence, and the polymer (I) may contain polymerization units based on two or more different other monomers.

[0236] The other monomers include those represented by the following formula (n1-2):

[0237] [ka]

[0238] (In the formula, X 1 , X 2 are the same or different H or F;X 3 is H, F, Cl, CH3 or CF3;X 4 , X 5 are the same or different and are H or F; a and c are the same or different and are 0 or 1. Rf 3 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having ether bonds having 2 to 100 carbon atoms).

[0239] Specifically, CH2=CFCF2-O-Rf 3 , CF2=CF-O-Rf 3 , CF2=CFCF2-O-Rf 3 , CF2=CF-Rf 3, CH2=CH-Rf 3 , CH2=CH-O-Rf 3 (In the formula, Rf 3 is the same as the above formula (n1-2)).

[0240] As the other monomer, there may be mentioned a monomer represented by the formula (n2-1):

[0241] [ka]

[0242] (In the formula, X 9 is H, F or CH3; Rf 4 Also included are fluorine-containing acrylate monomers represented by Rf (a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and an ether bond). 4 The base is

[0243] [ka]

[0244] (wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10), etc. can be mentioned.

[0245] Examples of the other monomer include those represented by the general formula (n2-2): CH2=CHO-Rf 5 (n2-2) (In the formula, Rf 5 Also included are fluorine-containing vinyl ethers represented by the formula (I) (a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0246] Specific examples of the monomer of general formula (n2-2) include:

[0247] [ka]

[0248] (wherein e6 is an integer of 1 to 10) are preferred.

[0249] More specifically,

[0250] [ka]

[0251] etc.

[0252] Others, general formula (n2-3): CH2=CHCH2O-Rf 6 (n2-3) (In the formula, Rf 6 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms), a fluorine-containing allyl ether represented by the general formula (n2-4): CH2=CH-Rf 7 (n2-4) (In the formula, Rf 7 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0253] Specific examples of the monomers represented by the above formulas (n2-3) and (n2-4) include:

[0254] [ka]

[0255] and the like monomers.

[0256] The polymer (I) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and representative terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl group or fluoroalkyl group preferably has 1 to 20 carbon atoms. These terminal groups are generally generated from the initiator or chain transfer agent used in the formation of the polymer (I), or are generated during the chain transfer reaction.

[0257] The content of the polymer (I) of the polymerization unit (I) is preferably 1.0 mol % or more, more preferably 3.0 mol % or more, even more preferably 5.0 mol % or more, even more preferably 10 mol % or more, particularly preferably 20 mol % or more, and particularly preferably 30 mol % or more, based on the total amount of the polymerization units. The polymer (I) preferably has a content of the polymerized unit (I) of 30 mol% or more based on the total polymerized units. More preferably, it is 40 mol% or more, even more preferably, it is 60 mol% or more, even more preferably, it is 80 mol% or more, particularly preferably, it is 90 mol% or more, and it is especially preferably substantially 100 mol%. Furthermore, it is most preferable that the polymer (I) is composed only of the polymerized unit (I).

[0258] In the polymer (I), the content of polymerization units based on other monomers copolymerizable with the monomer represented by general formula (I) is preferably 99.0 mol % or less, more preferably 97.0 mol % or less, even more preferably 95.0 mol % or less, even more preferably 90 mol % or less, and especially preferably 80 mol % or less, based on the total polymerization units. In addition, in the polymer (I), the content of the polymerization units based on other monomers copolymerizable with the monomer represented by general formula (I) is preferably 70 mol% or less, more preferably 60 mol% or less, even more preferably 40 mol% or less, even more preferably 20 mol% or less, particularly preferably 10 mol% or less, and even more preferably substantially 0 mol%. It is most preferable that the polymer (I) does not contain polymerization units based on other monomers copolymerizable with the monomer represented by general formula (I).

[0259] The number average molecular weight of the polymer (I) is 0.1×10 4 More than 0.2×10 is preferable. 4 More preferably, 0.3×10 4 More preferably, 0.4×10 4 More than 0.5×10 is particularly preferable. 4 More preferably, 1.0×10 4 More than 3.0×10 is particularly preferable. 4 The number average molecular weight of the polymer (I) is preferably 3.1×10 4 It is also preferable that the number is equal to or larger than this. The number average molecular weight of the polymer (I) is also 75.0×10 4 Less than 50.0×10 is preferable. 4 Less than 40.0×10 is more preferable. 4 More preferably, 30.0×10 4 More preferably, 20.0×10 4 The following is particularly preferred. If the number average molecular weight is too low, the stability of the aqueous solution may be insufficient. If the number average molecular weight is too high, the polymer (I) may partially settle, precipitate, or become cloudy during storage or when other additives are added. The number average molecular weight and the weight average molecular weight described below are values ​​calculated by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. In addition, when the measurement by GPC is not possible, the number average molecular weight of the polymer (I) can be obtained from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[0260] The weight average molecular weight of the polymer (I) is 0.2×10 4 More than 0.4×10 is preferable. 4 More preferably, 0.6×10 4 More preferably, 0.8×10 4 More preferably, 1.0×10 4The weight average molecular weight of the polymer (I) is particularly preferably 5.0×10 4 That's it, 10.0 x 10 4 That's it, 15.0 x 10 4 That's it, 20.0 x 10 4 or more, or 25.0×10 4 It is also preferable that the number is equal to or larger than this. The weight average molecular weight of the polymer (I) is also 150.0×10 4 The following is preferable: 100.0×10 4 Less than 60.0×10 is more preferable. 4 Less than 50.0×10 is more preferable. 4 The following is even more preferable: 40.0×10 4 The following are particularly preferred:

[0261] The polymer (I) preferably has an ion exchange ratio (IXR) of 53 or less, where IXR is defined as the number of carbon atoms in the polymer backbone relative to the ionic group. Precursor groups that become ionic upon hydrolysis (e.g., -SO2F) are not considered ionic groups for purposes of determining IXR.

[0262] IXR is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and particularly preferably 8 or more. IXR is more preferably 43 or less, more preferably 33 or less, and particularly preferably 23 or less.

[0263] The ion exchange capacity of the polymer (I) is, in order of preference, 0.80 meg / g or more, 1.50 meg / g or more, 1.75 meg / g or more, 2.00 meg / g or more, 2.50 meg / g or more, 2.60 meg / g or more, 3.00 meg / g or more, and 3.50 meg / g or more. The ion exchange capacity is the content of ionic groups (anionic groups) in the polymer (I) and is calculated from the composition of the polymer (I).

[0264] In the polymer (I), the ionic (anionic) groups are typically distributed along the polymer backbone. The polymer (I) comprises a polymer backbone with recurring side chains attached to the backbone, which side chains preferably carry ionic groups.

[0265] The polymer (I) preferably comprises an ionic group having a pKa of less than 10, more preferably less than 7. The ionic group of the polymer (I) is preferably selected from the group consisting of sulfonate, carboxylate, phosphonate and phosphate.

[0266] The terms "sulfonate, carboxylate, phosphonate, and phosphate" are intended to refer to the respective salts or to the respective acids capable of forming salts. When salts are used, preferably the salts are alkali metal or ammonium salts. A preferred ionic group is the sulfonate group.

[0267] The polymer (I) is preferably water-soluble. Water-soluble means the property of being easily dissolved or dispersed in an aqueous medium. The particle size of the water-soluble polymer (I) cannot be measured by, for example, dynamic light scattering (DLS). On the other hand, the particle size of the water-insoluble polymer (I) can be measured by, for example, dynamic light scattering (DLS).

[0268] The above polymer (I) can be produced by a conventional method except for using the above monomers.

[0269] The content of dimers and trimers of the monomer represented by general formula (I) in the composition is preferably 1.0 mass% or less, more preferably 0.1 mass% or less, even more preferably 0.01 mass% or less, particularly preferably 0.001 mass% or less, and most preferably 0.0001 mass% or less, based on the polymer (I).

[0270] The contents of the dimer and trimer of the monomer represented by general formula (I) in the composition can be measured by the same method as that for the dimer and trimer contents in the polymer (I) described below.

[0271] The composition of the present disclosure has a standard specific gravity (SSG) of 2.200 or less. By having a standard specific gravity of 2.200 or less, it is possible to obtain a composition that can be stretched, and a stretched body having excellent stretchability and breaking strength can be obtained. The standard specific gravity is preferably 2.195 or less, more preferably 2.190 or less, and even more preferably 2.185 or less. The lower limit of the standard specific gravity is not limited, but is, for example, 2.130. The above standard specific gravity is measured by a water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89.

[0272] The composition of the present disclosure preferably has a content of polymer (I) of 0.0001% by mass or more and 20% by mass or less based on polytetrafluoroethylene. In the composition of the present disclosure, the lower limit of the content of polymer (I) is more preferably 0.001% by mass, even more preferably 0.01% by mass, and particularly preferably 0.1% by mass based on polytetrafluoroethylene. The upper limit is more preferably 10% by mass, even more preferably 6% by mass, even more preferably 4% by mass, particularly preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1% by mass or less. The content of polymer (I) in the composition of the present disclosure is determined by solid-state NMR measurement. Methods for measuring the content of the polymer (I) include those described in WO 2014 / 099453, WO 2010 / 075497, WO 2010 / 075496, WO 2011 / 008381, WO 2009 / 055521, WO 1987 / 007619, JP 61-293476 A, WO 2010 / 075494, WO 2010 / 075359, WO 2012 / 082454, WO 2006 / 119224, WO 2013 / 085864, and the like. Methods for measuring the respective polymers described in JP2012 / 082707, JP2012 / 082703, JP2012 / 082454, JP2012 / 082451, JP2006 / 135825, JP2004 / 067588, JP2009 / 068528, JP2004-075978, JP2001-226436, JP1992 / 017635, JP2014 / 069165, JP11-181009, etc. are described. As a method for measuring the content of the polymer (I), the methods for measuring the respective polymers described therein can be used.

[0273] The composition of the present disclosure has an extrusion pressure of preferably 40.0 MPa or less, more preferably 35.0 MPa or less, more preferably 30.0 MPa or less, preferably 5.0 MPa or more, preferably 8.0 MPa or more, and more preferably 10.0 MPa or more. The above extrusion pressure is a value determined by the following method according to the method described in JP 2002-201217 A. 21.7 g of lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon Corp.) is added to 100 g of powder of the composition of the present disclosure and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste-extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead (extrusion molded body). The extrusion speed, i.e., the ram speed, is 20 in / min (51 cm / min). The extrusion pressure is the load measured when the extrusion load reaches equilibrium in the paste extrusion and divided by the cross-sectional area of ​​the cylinder used for the paste extrusion.

[0274] Hereinafter, breaking strengths A to D are values ​​determined by the following method in accordance with the method described in JP-A-2002-201217. The composition of the present disclosure preferably has a breaking strength A of 10.0N or more. The breaking strength A is more preferably 13.0N or more, more preferably 16.0N or more, and even more preferably 19.0N or more. Furthermore, it is preferably 20.0N or more, more preferably 21.0N or more, even more preferably 22.0N or more, even more preferably 25.0N or more, especially preferably 28.0N or more, and particularly preferably 30.0N or more. The higher the breaking strength A, the better, but the upper limit of the breaking strength A may be, for example, 100N or less, 80.0N or less, or 50.0N. In the present disclosure, when simply referring to "breaking strength", it means "breaking strength A".

[0275] The breaking strength A is a value determined by the following method. First, an extrusion bead stretching test A is carried out by the following method to prepare a sample for measuring the breaking strength A. The composition of the present disclosure is heat treated at 210°C. 21.7 g of lubricant is added to 100 g of the heat treated powder and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste extruded through an orifice (diameter 2.5 mm, land length 11 mm, entry angle 30°) at room temperature with a reduction ratio of 100:1 to obtain a uniform beading (extrusion molded body). The extrusion speed, i.e., ram speed, is 20 inches / minute (51 cm / minute). The bead obtained by the above paste extrusion is heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) is then cut to the appropriate length, clamped at each end with a clamp distance of 1.5 inches (38 mm) apart, and heated to 300°C in an air circulating oven. The clamps are then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) is achieved, and a stretch test is performed. This stretching method essentially follows the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. In the above preparation method, the stretch rate is 1000% / sec and the total stretch is 2400%. The stretched bead (produced by stretching the bead) obtained in the above stretching test A is clamped and fixed in a movable jaw having a gauge length of 5.0 cm, and a tensile test is performed at 25°C and a speed of 300 mm / min. The strength at which it breaks is defined as breaking strength A.

[0276] The composition of the present disclosure preferably has a breaking strength B of 10.0 N or more. The breaking strength B is, in order of preference, 13.0 N or more, 15.0 N or more, 18.0 N or more, 20.0 N or more, 22.0 N or more, 25.0 N or more, 28.0 N or more, and 30.0 N or more. The higher the breaking strength B, the better, but the upper limit of the breaking strength B may be, for example, 100 N or less, 80.0 N or less, or 50.0 N or less.

[0277] Breaking strength B is a strength measured in the same manner as breaking strength A, except that a stretch bead obtained by changing the clamp distance to 2.0 inches (51 mm) and the stretch rate to 100% / sec is used.

[0278] The composition of the present disclosure preferably has a breaking strength C of 10.0 N or more. The breaking strength C is, in order of preference, 15.0 N or more, 20.0 N or more, 22.0 N or more, 25.0 N or more, 28.0 N or more, 30.0 N, 33.0 N, or 35.0 N or more. The higher the breaking strength C, the better, but the upper limit of the breaking strength C may be, for example, 100 N or less, 80.0 N or less, or 50.0 N or less.

[0279] Breaking strength C is a strength measured in the same manner as breaking strength A, except that a powder obtained by heat treatment at 240°C is used.

[0280] The composition of the present disclosure preferably has a breaking strength D of 10.0 N or more. The breaking strength D is, in order of preference, 13.0 N or more, 16.0 N or more, 20.0 N or more, 22.0 N or more, 25.0 N or more, 28.0 N or more, 30.0 N, or 35.0 N or more. The higher the breaking strength D, the better, but the upper limit of the breaking strength D may be, for example, 100 N or less, 80.0 N or less, or 50.0 N or less.

[0281] Breaking strength D is a strength measured in the same manner as breaking strength A, except that a powder obtained by heat treatment at 240°C is used, the clamp distance is changed to 2.0 inches (51 mm), and the stretch rate is changed to 100% / sec to obtain a stretch bead.

[0282] Hereinafter, the stress relaxation time is a value determined by the following method in accordance with the method described in JP-A-2002-201217. The composition of the present disclosure preferably has a stress relaxation time of 50 seconds or more, more preferably 80 seconds or more, even more preferably 100 seconds or more, and may be 150 seconds or more.

[0283] The stress relaxation time is a value measured by the following method. Both ends of the stretched bead obtained in the above stretch test A are connected to a fixture to make a taut bead sample with a total length of 8 inches (20 cm). The oven is kept at 390°C and the fixture is inserted into the oven through a (covered) slit in the side of the oven. The time required from the time of insertion into the oven until the bead sample breaks is the stress relaxation time.

[0284] The composition of the present disclosure is preferably extensible. In the present disclosure, "extensible" is determined according to the following criteria. 21.7 g of lubricant (trade name: Isopar H (registered trademark), Exxon) is added to 100 g of powder of the composition of the present disclosure and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin is paste extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead. The extrusion speed, i.e., ram speed, is 20 in / min (51 cm / min). The bead obtained by paste extrusion is heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrusion molded body) is then cut to an appropriate length, clamped at each end so that the clamp spacing is 1.5 in (38 mm), and heated to 300°C in an air circulating oven. The clamps are then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) is achieved, and a stretch test is performed. The stretch method essentially follows that disclosed in U.S. Pat. No. 4,576,869, except for the difference in extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, and is usually expressed relative to the original length. In the above preparation, the stretch rate is 1000% / sec, and the total stretch is 2400%. This means that the stretch test results in a stretched bead with a uniform appearance without breakage.

[0285] In one embodiment of the composition of the present disclosure, a fluorine-containing surfactant is contained. A composition containing a fluorine-containing surfactant and PTFE has an advantage that it can be stably produced with high productivity using the fluorine-containing surfactant.

[0286] The composition of the present disclosure is preferably substantially free of fluorine-containing surfactant. In the composition of the present disclosure, "substantially free of fluorine-containing surfactant" means that the fluorine-containing surfactant is 1 mass ppm or less relative to polytetrafluoroethylene, preferably 100 mass ppb or less, more preferably 10 mass ppb or less, even more preferably 1 mass ppb or less, and particularly preferably the fluorine-containing surfactant is below the detection limit by measurement by liquid chromatography-mass spectrometry (LC / MS). The amount of the fluorine-containing surfactant can be quantified by a known method. For example, it can be quantified by LC / MS analysis. First, the obtained aqueous dispersion or powder is extracted with an organic solvent such as methanol, and the molecular weight information of the extract is extracted from the LC / MS / MS spectrum to confirm whether it matches the structural formula of the candidate surfactant. Then, aqueous solutions of the confirmed surfactant are prepared at five or more levels of concentration, and LC / MS analysis is performed for each concentration, and a calibration curve with respect to the area is created. The obtained aqueous dispersion or powder is subjected to Soxhlet extraction with methanol, and the extract is subjected to LC / MS analysis to quantitatively measure the amount. The extraction solvent may be acetone in addition to methanol. The extraction method may be the Soxhlet extraction method.

[0287] That is, the content of the fluorine-containing surfactant can be quantified, for example, by LC / MS / MS analysis. First, methanol is added to the composition to perform extraction, and the resulting extract is analyzed by LC / MS / MS. To further increase the extraction efficiency, treatments such as Soxhlet extraction and ultrasonic treatment may be performed. Molecular weight information is extracted from the obtained LC / MS / MS spectrum, and a match with the structural formula of the candidate fluorine-containing surfactant is confirmed. Then, aqueous solutions containing five or more levels of the confirmed fluorine-containing surfactant are prepared, and LC / MS / MS analysis is performed on the aqueous solutions containing each level of the fluorine-containing surfactant. The relationship between the content and the area for each content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area of ​​the LC / MS / MS chromatogram of the fluorosurfactant in the extract can be converted into the content of the fluorosurfactant.

[0288] The fluorine-containing surfactant is a surfactant containing a fluorine atom and having a molecular weight of 800 or less.

[0289] The above-mentioned fluorosurfactant may have a LogPOW of 3.5 or less. The LogPOW is a partition coefficient between 1-octanol and water, and is expressed as LogP [wherein P represents the ratio of the fluorosurfactant concentration in octanol to the fluorosurfactant concentration in water when a 1:1 octanol / water mixture containing the fluorosurfactant undergoes phase separation]. The LogPOW is calculated from the HPLC elution time of the sample solution using a calibration curve of each elution time and the known octanol / water partition coefficient, which is prepared by performing HPLC on standard substances (heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid) having known octanol / water partition coefficients under the following conditions: column: TOSOH ODS-120T column (φ4.6 mm×250 mm, manufactured by Tosoh Corporation), eluent: acetonitrile / 0.6% by mass HClO4 water=1 / 1 (vol / vol%), flow rate: 1.0 ml / min, sample amount: 300 μL, column temperature: 40° C., and detection light: UV 210 nm.

[0290] Specific examples of the fluorine-containing surfactant include those described in U.S. Patent Application Publication No. 2007 / 0015864, U.S. Patent Application Publication No. 2007 / 0015865, U.S. Patent Application Publication No. 2007 / 0015866, U.S. Patent Application Publication No. 2007 / 0276103, U.S. Patent Application Publication No. 2007 / 0117914, U.S. Patent Application Publication No. 2007 / 142541, U.S. Patent Application Publication No. 2008 / 0015319, U.S. Patent No. 3,250,808, U.S. Patent No. 3,271,341, JP 2003-233662, and the like. Examples of such applications include those described in WO-119204, WO 2005 / 042593, WO 2008 / 060461, WO 2007 / 046377, WO 2007 / 119526, WO 2007 / 046482, WO 2007 / 046345, U.S. Patent Application Publication No. 2014 / 0228531, WO 2013 / 189824, and WO 2013 / 189826.

[0291] The fluorine-containing surfactant may be an anionic fluorine-containing surfactant, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms having a total carbon number of 20 or less excluding the anionic group.

[0292] The fluorine-containing surfactant may be a surfactant containing fluorine, the molecular weight of the anionic portion of which is 800 or less. The "anionic portion" refers to the portion of the fluorine-containing surfactant excluding the cation. For example, F(CF2) represented by the formula (I) described below may be used. n1 In the case of COOM, "F(CF2) n1 The "COO" part.

[0293] The anionic fluorine-containing surfactant may be represented by the general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 Y is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. 0 is an anionic group.

[0294] Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, where M is H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., such as Na, K, or Li. R 7 As for the 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 1-4 M may be H, a metal atom or NR 7 4, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 7 4, and may be H, Na, K, Li or NH4. n0 may be one in which 50% or more of H is substituted with fluorine.

[0295] General formula (N 0 As the compound represented by the general formula (N 1 ): X n0 -(CF2) m1 -Y 0 (N 1 ) (In the formula, X n0 is H, Cl, or F; m1 is an integer from 3 to 15; Y 0is as defined above.) 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X n1 is F or CF3, and Y 0 is as defined above.) 3 ): Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 ) (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, m3 is an integer of 1 to 3, Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is as defined above.) 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond; Y n1 and Y n2 are the same or different and are H or F, p is 0 or 1, and Y 0 is as defined above.) 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf may be the same or different and are H, F, or a linear or branched partially or completely fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched, partially or completely fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y 0 is as defined above, where X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less.

[0296] Examples of the anionic surfactant include carboxylic acid surfactants and sulfonic acid surfactants. Examples of these surfactants include perfluorocarboxylic acid (I) represented by the following general formula (I), ω-H perfluorocarboxylic acid (II) represented by the following general formula (II), perfluoropolyether carboxylic acid (III) represented by the following general formula (III), perfluoroalkyl alkylene carboxylic acid (IV) represented by the following general formula (IV), alkoxy fluorocarboxylic acid (V) represented by the following general formula (V), perfluoroalkyl sulfonic acid (VI) represented by the following general formula (VII), ω-H perfluoro sulfonic acid (VII) represented by the following general formula (VII), perfluoroalkyl alkylene sulfonic acid (VIII) represented by the following general formula (VIII), alkyl alkylene carboxylic acid (IX) represented by the following general formula (IX), fluorocarboxylic acid (X) represented by the following general formula (X), alkoxy fluoro sulfonic acid (XI) represented by the following general formula (XI), compound (XII) represented by the following general formula (XII), compound (XIII) represented by the following general formula (XIII), and the like.

[0297] The perfluorocarboxylic acid (I) is represented by the following general formula (I): F(CF2) n1 COOM (I) (In the formula, n1 is an integer of 3 to 14, and M is H, a metal atom, or NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0298] The ω-H perfluorocarboxylic acid (II) is represented by the following general formula (II): H(CF2) n2 COOM (II) (wherein n2 is an integer of 4 to 15, and M is as defined above).

[0299] The perfluoropolyether carboxylic acid (III) is represented by the following general formula (III): Rf 1 -O-(CF(CF3)CF2O) n3 CF(CF3)COOM (III) (In the formula, Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms, n3 is an integer of 0 to 3, and M is as defined above.

[0300] The perfluoroalkyl alkylene carboxylic acid (IV) is represented by the following general formula (IV): Rf 2 (CH2) n4 Rf 3 COOM (IV) (In the formula, Rf 2 is a perfluoroalkyl group having 1 to 5 carbon atoms, and Rf 3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, n4 is an integer of 1 to 3, and M is as defined above.

[0301] The alkoxyfluorocarboxylic acid (V) is represented by the following general formula (V): Rf 4 -O-CY 1 Y 2 CF2-COOM (V) (In the formula, Rf 4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0302] The perfluoroalkylsulfonic acid (VI) is represented by the following general formula (VI): F(CF2) n5 SO3M (VI) (wherein n5 is an integer of 3 to 14, and M is as defined above).

[0303] The ω-H perfluorosulfonic acid (VII) is represented by the general formula (VII): H(CF2) n6 SO3M (VII) (wherein n6 is an integer of 4 to 14, and M is as defined above).

[0304] The perfluoroalkyl alkylene sulfonic acid (VIII) is represented by the following general formula (VIII): Rf 5 (CH2) n7 SO3M (VIII) (In the formula, Rf 5 is a perfluoroalkyl group of 1 to 13, n7 is an integer of 1 to 3, and M is as defined above.

[0305] The alkyl alkylene carboxylic acid (IX) is represented by the following general formula (IX): Rf 6 (CH2) n8 COOM (IX) (In the formula, Rf 6 is a linear or branched partially or completely fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer from 1 to 3, and M is as defined above.

[0306] The fluorocarboxylic acid (X) is represented by the following general formula (X): Rf 7 -O-Rf 8 -O-CF2-COOM (X) (In the formula, Rf 7 is a linear or branched, partially or completely fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond; Rf 8 is a linear or branched, partially or completely fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[0307] The alkoxyfluorosulfonic acid (XI) is represented by the following general formula (XI): Rf 9 -O-CY 1 Y 2 CF2-SO3M (XI) (In the formula, Rf 9 is a linear or branched alkyl group having 1 to 12 carbon atoms, which may contain an ether bond, and which may contain chlorine, and which is partially or completely fluorinated; Y 1 and Y 2 are the same or different and are H or F, and M is as defined above.

[0308] The compound (XII) is represented by the following general formula (XII): [ka] (In the formula, X 1 , X 2 and X 3 Rf may be the same or different and are H, F and linear or branched partially or completely fluorinated alkyl groups having 1 to 6 carbon atoms, which may contain ether bonds; 10 is a perfluoroalkylene group having 1 to 3 carbon atoms, L is a linking group, and Y 0 is an anionic group. 0may be -COOM, -SO2M, or -SO3M, and may be -SO3M or COOM (wherein M is as defined above). Examples of L include a single bond, or a partially or fully fluorinated alkylene group having 1 to 10 carbon atoms which may contain an ether bond.

[0309] The compound (XIII) is represented by the following general formula (XIII): Rf 11 -O-(CF2CF(CF3)O) n9 (CF2O) n10 CF2COOM (XIII) (In the formula, Rf 11 is a fluoroalkyl group containing chlorine and having 1 to 5 carbon atoms, n9 is an integer of 0 to 3, n10 is an integer of 0 to 3, and M is as defined above.) Compound (XIII) is represented by CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, where n9 and n10 are defined above).

[0310] Thus, examples of the anionic fluorine-containing surfactant include carboxylic acid surfactants and sulfonic acid surfactants.

[0311] The powder of the composition of the present disclosure is preferably used for molding, and suitable applications include tubes for hydraulic and fuel systems in aircraft and automobiles, flexible hoses for chemicals and steam, wire coating, etc. It can also be used as a binder for batteries and for dust prevention.

[0312] The composition of the present disclosure can be obtained by a production method including a step of obtaining polytetrafluoroethylene by polymerizing tetrafluoroethylene in an aqueous medium in the presence of a polymer (I) containing polymerization units (I) based on a monomer represented by general formula (I) (hereinafter also referred to as a "polymerization step"). The composition of the present disclosure can be obtained by polymerizing tetrafluoroethylene in an aqueous medium in the presence of a polymer (I) containing polymerization units (I) based on a monomer represented by general formula (I). The polymerization may be a polymerization of tetrafluoroethylene and the above-mentioned modified monomer.

[0313] The above-mentioned production method requires the use of at least one type of the polymer (I), and may use two or more types of the polymer (I) simultaneously. In addition, other compounds having surface activity may be used simultaneously, as long as they are volatile or may remain in a molded product (e.g., a stretched product) made of the above-mentioned composition.

[0314] In the above polymerization, the polymerization temperature is usually 5 to 120° C., and the polymerization pressure is usually 0.05 to 10 MPaG. The polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0315] The polymerization temperature is preferably 10 to 150°C, more preferably 30°C or higher, further preferably 50°C or higher, more preferably 120°C or lower, further preferably 100°C or lower.

[0316] The polymerization pressure is preferably 0.05 to 10 MPaG, more preferably 0.3 MPaG or more, even more preferably 0.5 MPaG or more, more preferably 5.0 MPaG or less, and even more preferably 3.0 MPaG or less. In particular, from the viewpoint of improving the yield of PTFE, the polymerization pressure is preferably 1.0 MPaG or more, more preferably 1.2 MPaG or more, even more preferably 1.5 MPaG or more, particularly preferably 1.8 MPaG or more, and most preferably 2.0 MPaG or more.

[0317] In the above polymerization step, the amount of polymer (I) at the start of polymerization is preferably 1 mass ppm or more relative to the aqueous medium. The amount of polymer (I) at the start of polymerization is preferably 10 mass ppm or more, more preferably 50 mass ppm or more, even more preferably 100 mass ppm or more, and even more preferably 200 mass ppm or more. The upper limit is not particularly limited, but for example, it is preferably 100000 mass ppm, and more preferably 50000 mass ppm. By having the amount of polymer (I) at the start of polymerization within the above range, an aqueous dispersion with even more excellent dispersion stability can be obtained.

[0318] The total amount of the polymer (I) is preferably 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium. A more preferred lower limit is 0.001% by mass, and a more preferred upper limit is 1% by mass. If the amount is less than 0.0001% by mass, the dispersing power may be insufficient, and if the amount is more than 10% by mass, the effect commensurate with the amount added may not be obtained, and instead the polymerization rate may decrease or the reaction may stop. The amount of the compound added is appropriately determined depending on the type of monomer used, the molecular weight of the desired fluoropolymer, etc.

[0319] The aqueous medium is a reaction medium for polymerization, and refers to a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as an alcohol, ether, or ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or less.

[0320] The above-mentioned production method may include a step of adding a polymerization terminator to the aqueous medium (hereinafter also referred to as a "polymerization terminator adding step"). The polymerization terminator adding step is carried out during the polymerization step. By adding the polymerization terminator during the polymerization step, the breaking strength of the obtained composition and stretched body can be increased.

[0321] The polymerization terminator is a compound that does not have the ability to restart after addition or chain transfer to the free radical in the polymerization system. Specifically, a compound that easily undergoes a chain transfer reaction with a primary radical or a growing radical, and then generates a stable radical that does not react with a monomer, or a compound that easily undergoes an addition reaction with a primary radical or a growing radical, and generates a stable radical, is used. Generally, the activity of a chain transfer agent is characterized by the chain transfer constant and the reinitiation efficiency, but among chain transfer agents, those with a reinitiation efficiency of almost 0% are called polymerization terminators. As the polymerization terminator in the present disclosure, for example, at least one selected from the group consisting of aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl2) is preferable. Examples of the aromatic hydroxy compound include unsubstituted phenol, polyhydric phenol, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, etc. Examples of the unsubstituted phenol include o-, m- or p-nitrophenol, o-, m- or p-aminophenol, p-nitrosophenol, etc. Examples of the polyhydric phenol include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, naphthresorcinol, etc. Examples of aromatic amines include o-, m- or p-phenylenediamine, benzidine, and the like. Examples of the quinone compound include hydroquinone, o-, m- or p-benzoquinone, 1,4-naphthoquinone, and alizarin. Examples of thiocyanates include ammonium thiocyanate (NH4SCN), potassium thiocyanate (KSCN), and sodium thiocyanate (NaSCN). Of the above polymerization terminators, quinone compounds are preferred, and hydroquinone is more preferred.

[0322] From the viewpoint of reducing the standard specific gravity, the polymerization terminator is preferably added before 90% by mass of the total tetrafluoroethylene consumed in the polymerization reaction is polymerized, more preferably before 85% by mass, and even more preferably before 80% by mass of the total tetrafluoroethylene is polymerized. It is also preferable to add the tetrafluoroethylene after 5% by mass of the total tetrafluoroethylene consumed in the polymerization reaction has been polymerized, and it is more preferable to add the tetrafluoroethylene after 10% by mass has been polymerized. The amount of the polymerization terminator added is preferably an amount corresponding to 0.1 to 20 ppm by mass, and more preferably an amount corresponding to 3 to 10 ppm by mass, based on the mass of the aqueous medium used.

[0323] The above-mentioned production method preferably includes a step of adding a decomposer to the aqueous medium instead of the polymerization terminator. By adding the decomposer, the radical concentration during polymerization can be adjusted. Examples of the decomposer include sulfite, bisulfite, bromate, diimine, oxalic acid, copper salt, iron salt, etc. Examples of the sulfite include sodium sulfite and ammonium sulfite. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate. The amount of the decomposer added is within a range of 25 to 300% by mass, preferably 25 to 150% by mass, and more preferably 50 to 100% by mass, based on the amount of the oxidizing agent combined as a polymerization initiator (redox initiator described below). It is also preferable to add the tetrafluoroethylene after 5% by mass of the total tetrafluoroethylene consumed in the polymerization reaction has been polymerized, and it is more preferable to add the tetrafluoroethylene after 10% by mass has been polymerized. The amount of the polymerization terminator added is preferably an amount corresponding to 0.1 to 20 ppm by mass, and more preferably an amount corresponding to 3 to 10 ppm by mass, based on the mass of the aqueous medium used.

[0324] In the above polymerization step, it is also preferable to continuously add the polymer (I) during the polymerization of TFE. Continuously adding the polymer (I) means, for example, adding the polymer (I) over time, not all at once, and continuously or in portions. By continuously adding the polymer (I), a composition having even better dispersion stability can be obtained.

[0325] When the polymer (I) is added continuously, the amount of the polymer (I) added is preferably 0.001 to 10% by mass relative to 100% by mass of the aqueous medium, more preferably 0.005% by mass, even more preferably 0.01% by mass, more preferably 5% by mass, and even more preferably 2% by mass.

[0326] In the above polymerization process, 0.6×10 13 It is preferable to generate particles at a concentration of 0.7×10 particles / ml or more. By generating a large number of particles in the polymerization step, primary particles having a small average primary particle size and a small aspect ratio can be obtained, and an aqueous dispersion with excellent stability can be obtained. The number of particles to be generated is, in order of preference, 0.7×10 13 pcs / mL or more, 0.8×10 13 pcs / mL or more, 0.9×10 13 pcs / mL or more, 1.0×10 13 pcs / mL or more, 1.5×10 13 The upper limit of the number of particles to be generated is not particularly limited, but is, for example, 7.0 × 10 14 pieces / mL.

[0327] The particles generated by the polymerization of TFE are generated intensively in the first half of the polymerization and are not generated easily in the second half of the polymerization, so the number of particles in the polymerization process is almost the same as the number of particles generated in the first half of the polymerization. Therefore, the number of particles in the polymerization process can be predicted by measuring the number of primary particles in the finally obtained aqueous dispersion.

[0328] In the above polymerization step, it is also preferable to polymerize TFE and a modified monomer. The modified monomer can be one that can be copolymerized with TFE. By polymerizing TFE and a modified monomer, primary particles having smaller average primary particle size and smaller aspect ratio can be obtained, and an aqueous dispersion with better dispersion stability can be obtained.

[0329] The total amount of modified monomers added during polymerization of TFE is preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, even more preferably 0.005% by mass or more, and particularly preferably 0.009% by mass or more, based on the PTFE obtained. The total amount of modified monomers added during polymerization is, in order of preference, 1.0% by mass or less, 0.90% by mass or less, 0.50% by mass or less, 0.40% by mass or less, 0.30% by mass or less, 0.20% by mass or less, 0.15% by mass or less, 0.10% by mass or less, and 0.05% by mass or less, based on the PTFE obtained.

[0330] In the above polymerization, it is preferable to add a modified monomer copolymerizable with TFE before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, preferably before it reaches 5.0% by mass. The modified monomer is usually added to a reactor. By adding the modified monomer at the beginning of the polymerization, more particles can be generated during the polymerization, and primary particles having a smaller average primary particle size and aspect ratio can be obtained. The modified monomer may be added before the start of the polymerization, may be added at the same time as the start of the polymerization, or may be added during the period in which the nuclei of PTFE particles are formed after the start of the polymerization. The modified monomer may be added at least before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, and further modified monomer may be added after the concentration of PTFE exceeds 10.0% by mass. For example, the modified monomer may be added before the concentration of PTFE reaches 10.0% by mass, and the modified monomer may be added continuously even after the concentration exceeds 10.0% by mass. Alternatively, the modified monomer may be added at least once before the PTFE concentration reaches 10.0% by mass, and then added at least once more after the PTFE concentration exceeds 10.0% by mass. The method of adding the modified monomer may be to push the modified monomer into the reactor by TFE.

[0331] It is said that polymerization is initiated when the gaseous fluoromonomer in the reactor becomes PTFE and the pressure in the reactor drops. US Patent 3,391,099 (Punderson) discloses dispersion polymerization of TFE in an aqueous medium, which consists of two distinct stages of the polymerization process: first, the formation of polymer nuclei as nucleation sites, and then, the growth stage, which includes the polymerization of the established particles. It is said that polymerization is usually initiated when both the monomer to be polymerized and the polymerization initiator are charged into the reactor.

[0332] Before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass, preferably before it reaches 5.0% by mass, the amount of the modified monomer added is preferably 0.00001% by mass or more, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, and particularly preferably 0.003% by mass or more, based on the PTFE obtained. Also, before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 10.0% by mass, preferably before it reaches 5.0% by mass, the amount of the modified monomer added is, in order of preference, 1.0% by mass or less, 0.90% by mass or less, 0.50% by mass or less, 0.40% by mass or less, 0.30% by mass or less, 0.20% by mass or less, 0.15% by mass or less, 0.10% by mass or less, and 0.05% by mass or less, based on the PTFE obtained.

[0333] In addition, as the polymer (I), a polymer (I) having a content of dimers and trimers of a monomer represented by general formula (I) (hereinafter, sometimes referred to as monomer (I)) of 1.0 mass% or less based on the polymer (I) may be used.

[0334] That is, the composition of the present disclosure is A step of polymerizing a monomer (I) represented by general formula (I) in an aqueous medium to obtain a crude composition containing a polymer of the monomer (I); a step of removing dimers and trimers of the monomer (I) contained in the crude composition from the crude composition to obtain a polymer (I) having a content of dimers and trimers of the monomer (I) of 1.0 mass% or less based on the polymer (I); A step of obtaining polytetrafluoroethylene by polymerizing tetrafluoroethylene in an aqueous medium in the presence of the polymer (I); Adding a polymerization terminator to the aqueous medium It is also preferable to produce the composition by a production method including the steps of:

[0335] The polymer (I) used in the above-mentioned production method does not substantially contain dimers and trimers of the monomer (I). The dimers and trimers of the monomer (I) are usually generated when the monomer (I) is polymerized to obtain the polymer (I). The content of the dimers and trimers in the polymer (I) is 1.0% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0001% by mass or less, based on the polymer (I).

[0336] The contents of dimer and trimer in polymer (I) can be determined by subjecting polymer (I) to gel permeation chromatography (GPC) analysis and calculating the ratio (area percentage) of the total peak area of ​​dimer and trimer to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0337] When the content of dimers and trimers in polymer (I) is less than 0.5% by mass relative to polymer (I), the content can be identified by measurement using liquid chromatography-mass spectrometry (LC / MS / MS). Specifically, aqueous solutions with five or more levels of monomer (I) content are prepared, LC / MS / MS analysis is performed for each content, and the relationship between the content and the area (peak integral value) for that content is plotted to create a calibration curve for monomer (I). Furthermore, from the calibration curve for monomer (I), calibration curves for the dimer and trimer of monomer (I) are created. Methanol is added to the polymer (I) to prepare a mixture, and an extract (supernatant) is recovered from the mixture by centrifugation, and the obtained extract is subjected to LC / MS / MS analysis. Then, using the calibration curve, the area (peak integral value) of the chromatogram of the dimer and trimer of the monomer (I) can be converted into the content of the dimer and trimer.

[0338] By using a polymer (I) that is substantially free of dimers and trimers during polymerization of a fluoromonomer in an aqueous medium, a polymerization dispersion that is substantially free of dimers and trimers of the monomer (I) can be produced.

[0339] The polymer (I) is a polymer containing a polymerized unit (I) based on the monomer (I). The polymer (I) used in the present disclosure is a polymer obtained by substantially removing a dimer (a polymer containing two polymerized units (I)) and a trimer (a polymer containing three polymerized units (I)) from a polymer (I) containing two or more polymerized units (I).

[0340] The molecular weight of the monomer (I) is preferably not more than 400. That is, it is preferable that the polymer (I) does not substantially contain dimers and trimers having a molecular weight of 1,200 or less.

[0341] The dimer and trimer of polymer (I) may be a polymer formed from one type of monomer (I) represented by general formula (I), or may be a copolymer formed from two or more types of monomer (I) having different structures.

[0342] The polymerization of the monomer (I) can be carried out by a known method. By producing a crude composition by such a method, it is possible to obtain a crude composition in which the polymer (I) is dispersed or dissolved in an aqueous medium.

[0343] The polymerization of the monomer (I) is preferably carried out substantially in the absence of a fluorine-containing surfactant (excluding the monomer (I) represented by general formula (I)). In the present disclosure, "substantially in the absence of a fluorine-containing surfactant" means that the amount of the fluorine-containing surfactant relative to the aqueous medium is 10 ppm by mass or less. The amount of the fluorine-containing surfactant relative to the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and even more preferably 1 ppb by mass or less.

[0344] The fluorine-containing surfactant will be described later in the explanation regarding the polymerization of TFE.

[0345] The crude composition thus obtained contains, as the polymer of monomer (I), a total of more than 1.0 mass% of dimers and trimers relative to the mass of the polymer of monomer (I). The content of dimers and trimers in the polymer of monomer (I) may be, for example, 2.0 mass% or more, 3.0 mass% or more, 30.0 mass% or less, or 20.0 mass% or less relative to the polymer of monomer (I). The content of dimers and trimers in the crude composition can be determined by performing gel permeation chromatography (GPC) analysis of the crude composition and calculating the ratio (area percentage) of the total peak area of ​​dimers and trimers to the total area of ​​each peak in the chromatogram obtained by GPC analysis.

[0346] Next, the dimer and trimer of the monomer (I) contained in the crude composition obtained by polymerization of the monomer (I) are removed from the crude composition. The means for removing the dimer and trimer is not particularly limited, but at least one means selected from the group consisting of ultrafiltration, microfiltration and dialysis membrane treatment is preferred, at least one means selected from the group consisting of microfiltration and dialysis membrane treatment is more preferred, and ultrafiltration is even more preferred.

[0347] It has not been known that dimers and trimers of monomer (I) are generated by polymerization of monomer (I), and as a result, the dimers and trimers of monomer (I) are contained in polymer (I). The mechanism by which dimers and trimers of monomer (I) are generated is not necessarily clear, but it is speculated that dimerization and trimerization of monomer (I) occur at a non-negligible frequency due to a polymerization reaction in a polymerization system in which monomer (I) accounts for the majority of the monomers present in the polymerization system. In the present disclosure, the presence of dimers and trimers of monomer (I) in polymer (I) has been revealed for the first time, and it has been found for the first time that dimers and trimers of monomer (I) in polymer (I) can be removed with high efficiency from polymer (I) (crude composition) by at least one means selected from the group consisting of ultrafiltration, microfiltration, and dialysis membrane treatment.

[0348] When removing the dimer and trimer, the unreacted monomer (I) is usually removed from the crude composition at the same time. Even if the unreacted monomer (I) is incorporated into PTFE by polymerization, it does not necessarily have a negative effect on the function of PTFE, so the unreacted monomer (I) does not necessarily need to be removed. However, by removing the unreacted monomer (I) together with the dimer and trimer, the amount of monomer to be subjected to polymerization can be calculated without considering the presence of the unreacted monomer (I), and PTFE having a desired monomer composition can be easily produced. Even if the monomer (I) remains in the polymer (I) or the monomer (I) is newly added as a comonomer, the dimerization and trimerization of the monomer (I) hardly progresses depending on the polymerization reaction in the polymerization system in which the fluoromonomer (excluding the monomer (I)) occupies the majority of the monomers present in the polymerization system, and the dimer and trimer of the monomer (I) hardly remain in the obtained PTFE.

[0349] The crude composition obtained by polymerization of the monomer (I) may be a composition obtained by polymerization as-polymerized, or may be a composition obtained by diluting or concentrating the composition obtained by polymerization as-polymerized, or may be a composition that has been subjected to a dispersion stabilization treatment, etc. In order to smoothly proceed with ultrafiltration, microfiltration, or dialysis membrane treatment, it is also preferable to adjust the viscosity of the crude composition by these treatments.

[0350] The content of the polymer of monomer (I) in the crude composition is not particularly limited, and may be, for example, 0.1 to 20% by mass. From the viewpoint of the efficiency of removing dimers and trimers, the content of the polymer of monomer (I) in the crude composition is preferably 18.0% by mass or less, more preferably 15.0% by mass or less, even more preferably 12.0% by mass or less, particularly preferably 10.0% by mass or less, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, and particularly preferably 1.5% by mass or more. The content of the polymer of monomer (I) in the crude composition can be adjusted, for example, by a method of adding water to the crude composition obtained by polymerization of monomer (I), a method of concentrating the crude composition obtained by polymerization of monomer (I), or the like.

[0351] The pH of the crude composition is preferably 0 to 11, more preferably 0.5 to 8.0, and further preferably 1.0 to 7.0. The pH of the crude composition can be adjusted by adding a pH adjuster to the crude composition obtained by polymerization of the monomer (I). The pH adjuster may be an acid or an alkali, and examples of the pH adjuster include phosphate, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0352] The viscosity of the crude composition is preferably 25 mPa s or less, since this allows the ultrafiltration, microfiltration or dialysis membrane treatment to proceed smoothly. The viscosity of the crude composition can be adjusted, for example, by adjusting the number average molecular weight of the polymer of monomer (I), by adjusting the concentration of the polymer of monomer (I) in the crude composition, by adjusting the temperature of the crude composition, or the like.

[0353] The above-mentioned ultrafiltration or microfiltration may be performed by either a cross-flow system or a dead-end system without any particular limitation, but the cross-flow system is preferred from the viewpoint of reducing clogging of the membrane.

[0354] The ultrafiltration can be carried out using an ultrafiltration membrane. For example, the ultrafiltration can be carried out using an ultrafiltration device having an ultrafiltration membrane, and centrifugal ultrafiltration, batch ultrafiltration, circulation ultrafiltration, etc. can be adopted.

[0355] The molecular weight cutoff of the ultrafiltration membrane is usually 0.1×10 4 ~30×10 4 The molecular weight cutoff of the ultrafiltration membrane is about 1.5 × 10 Da because it can suppress clogging of the membrane and efficiently reduce dimers and trimers. 4 The molecular weight cutoff is preferably 2.0×10 Da or more. 4 Da or more is preferable, 3.0×10 4 Da or more is particularly preferable, and 5.0×10 4 Da or more is most preferable. The molecular weight cutoff is 8.0×10 4 From the viewpoint of the efficiency of removing dimers and trimers, the molecular weight cutoff may be 20×10 Da or more. 4 Da or less is preferable, 10×10 4 Da or less is more preferable.

[0356] The molecular weight cutoff of the ultrafiltration membrane can be determined by, for example, passing polystyrene with a known weight average molecular weight through the membrane and determining the molecular weight at which 90% of the polystyrene is rejected. Quantitative determination of polystyrene can be performed using gel permeation chromatography.

[0357] The shape of the ultrafiltration membrane may be any of the conventionally known shapes, but is not limited thereto. For example, hollow fiber type, flat membrane type, spiral type, tubular type, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and is preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and is preferably 0.05 to 2 m.

[0358] The material of the ultrafiltration membrane is not particularly limited, but examples thereof include organic materials such as cellulose, cellulose ester, polysulfone, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, chlorinated polyethylene, polypropylene, polyolefin, polyvinyl alcohol, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, and polytetrafluoroethylene; metals such as stainless steel; and inorganic materials such as ceramics. The material of the ultrafiltration membrane is preferably an organic material, more preferably chlorinated polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polysulfone, or polyethersulfone, and even more preferably polyacrylonitrile or polyvinylidene fluoride.

[0359] Specific examples of the ultrafiltration membrane include G-5 type, G-10 type, G-20 type, G-50 type, PW type, and HWS UF type manufactured by DESAL; HFM-180, HFM-183, HFM-251, HFM-300, HFM-116, HFM-183, HFM-300, HFK-131, HFK-328, MPT-U20, MPS-U20P, and MPS-U20S manufactured by KOCH; SPE1, SPE3, SPE5, SPE10, SPE30, SPV5, SPV50, and SOW30 manufactured by Synder; Microza (registered trademark) UF series manufactured by Asahi Kasei Corporation; and NTR7410 manufactured by Nitto Denko Corporation.

[0360] From the viewpoint of the efficiency of removing dimers and trimers, the ultrafiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0361] From the viewpoint of the efficiency of removing dimers and trimers, the ultrafiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0362] The above-mentioned microfiltration can be carried out using a microfiltration membrane. The microfiltration membrane usually has an average pore size of 0.05 to 1.0 μm. The microfiltration membrane preferably has an average pore size of 0.1 μm or more, more preferably 0.075 μm or more, and even more preferably 0.1 μm or more, in order to efficiently remove dimers and trimers. The average pore size is preferably 1.00 μm or less, more preferably 0.50 μm or less, and even more preferably 0.25 μm or less. The average pore size of the microfiltration membrane can be measured in accordance with ASTM F316 03 (bubble point method).

[0363] The shape of the microfiltration membrane is not limited to any particular one and may be any of the conventionally known shapes, such as hollow fiber type, flat membrane type, spiral type, tubular type, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and is preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and is preferably 0.05 to 2 m.

[0364] Examples of materials for the microfiltration membrane include cellulose-based, aromatic polyamide, polyvinyl alcohol, polysulfone, polyethersulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, polytetrafluoroethylene, ceramics, metals, etc. Among these, aromatic polyamide, polyvinyl alcohol, polysulfone, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polypropylene, polycarbonate, or polytetrafluoroethylene is preferred, and polyacrylonitrile or polyvinylidene fluoride is particularly preferred.

[0365] Specific examples of microfiltration membranes include Cefilt manufactured by NGK Insulators, Ltd.; Microza U series and Microza P series manufactured by Asahi Kasei Corporation; Poreflon SPMW, Poreflon OPMW, and Poreflon PM manufactured by Sumitomo Electric Industries, Ltd.; Torayfil manufactured by Toray Industries, Inc.; NADIR MP005 and NADIR MV020 manufactured by Microdyne Nadia, Inc.; and X-flow manufactured by Norit.

[0366] From the viewpoint of the efficiency of removing dimers and trimers, the microfiltration is preferably carried out at a pressure of 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. From the viewpoint of pressure resistance, the pressure is preferably 0.5 MPa or less, more preferably 0.25 MPa or less, and even more preferably 0.2 MPa or less.

[0367] From the viewpoint of the efficiency of removing dimers and trimers, the above-mentioned microfiltration is preferably carried out at a flow rate of 10 mL / min or more, more preferably at a flow rate of 50 mL / min or more, and is preferably carried out at a flow rate of 5000 mL / min or less, more preferably at a flow rate of 1000 mL / min or less.

[0368] The dialysis membrane treatment is carried out using a dialysis membrane. 4 ~100×10 4 It has a molecular weight cutoff of Da. The above dialysis membrane suppresses clogging of the membrane and can efficiently remove dimers and trimers, so the molecular weight cutoff is 0.3 × 10 4 The molecular weight cutoff is preferably 0.5×10 Da or more. 4 Da or more is preferable, 1.0×10 4 Da or more is more preferable, and 1.5×10 4 Da or more is even more preferable, and 2.0×10 4 Da or more is particularly preferred, and 3.0×10 4 Da or more is particularly preferable, and 5.0×10 4 Da or more is most preferable. The above molecular weight cutoff is 8.0 × 10 4 It may be more than Da. From the viewpoint of the efficiency of removing dimers and trimers, the above molecular weight cutoff is set to 20×10 4 Da or less is preferable, 10×10 4 Da or less is more preferable. The molecular weight cutoff of the dialysis membrane can be measured, for example, in the same manner as that for the ultrafiltration membrane.

[0369] The material of the dialysis membrane is not particularly limited, but examples thereof include cellulose, polyacrylonitrile, polymethyl methacrylate, ethylene-vinyl alcohol copolymer, polysulfone, polyamide, and polyester-based polymer alloy.

[0370] Specific examples of dialysis membranes include Spectra / Por (registered trademark) Float-A-Lyzer, Tube-A-Lyzer, Dialysis tubing, 6Dialysis tubing, and 7Dialysis tubing manufactured by Spectrum Laboratories.

[0371] The ultrafiltration, microfiltration or dialysis membrane treatment is preferably carried out at a temperature of 10° C. or higher. More preferably, it is 15° C. or higher, even more preferably, it is 20° C. or higher, and particularly preferably, it is 30° C. or higher. By setting the temperature within the above range, dimers and trimers can be reduced more efficiently. The temperature is preferably 90° C. or lower, more preferably 80° C. or lower, even more preferably 70° C. or lower, and particularly preferably 60° C. or lower.

[0372] The ultrafiltration, microfiltration or dialysis membrane treatment can be carried out while adding water to the crude composition or while adjusting the pH of the crude composition. Water can be added to the crude composition intermittently or continuously.

[0373] The end point of the ultrafiltration, microfiltration or dialysis membrane treatment may be appropriately determined and is not limited. In addition, the ultrafiltration, microfiltration or dialysis membrane treatment may be backwashed with water about once every 1 to 24 hours of filtration time to improve the durability of the filtration membrane.

[0374] By removing the dimer and trimer of the monomer (I) from the crude composition containing the polymer of the monomer (I), an aqueous solution containing the polymer (I) that does not substantially contain the dimer and trimer is usually obtained. The polymer (I) used in the above-mentioned production method may be the polymer (I) contained in the obtained aqueous solution, or the polymer (I) obtained by separating it from the aqueous solution. The method for separating the polymer (I) from the aqueous solution is not particularly limited. For example, the polymer (I) can be separated by a method such as coagulation, washing, or drying of the polymer (I) in the aqueous solution.

[0375] As the polymer (I), an aqueous solution containing the polymer (I) can be used. The preferred content of the dimer and trimer of the monomer (I) relative to the polymer (I) in the aqueous solution is the same as the content of the dimer and trimer in the polymer (1).

[0376] The polymerization step may further comprise polymerizing tetrafluoroethylene in the presence of a nucleating agent.

[0377] The nucleating agent is preferably at least one selected from the group consisting of, for example, fluoropolyethers, nonionic surfactants, and chain transfer agents. In this case, the polymerization step is preferably a step of obtaining PTFE by polymerizing tetrafluoroethylene (and a modified monomer, if necessary) in an aqueous medium in the presence of the polymer (I) and the nucleating agent.

[0378] The fluoropolyether is preferably a perfluoropolyether.

[0379] The above fluoropolyether preferably has repeating units represented by formulas (1a) to (1d). (-CFCF3-CF2-O-) n (1a) (-CF2-CF2-CF2-O-) n (1b) (-CF2-CF2-O-) n -(-CF2-O-) m (1c) (-CF2-CFCF3-O-) n -(-CF2-O-) m (1d) (In formulas (1a) to (1d), m and n are integers of 1 or more.)

[0380] The above-mentioned fluoropolyether is preferably fluoropolyether acid or its salt, and the above-mentioned fluoropolyether acid is preferably carboxylic acid, sulfonic acid, sulfonamide or phosphonic acid, and more preferably carboxylic acid.Among the fluoropolyether acid or its salt, the salt of fluoropolyether acid is preferred, the ammonium salt of fluoropolyether acid is more preferred, and the ammonium salt of fluoropolyether carboxylic acid is even more preferred.

[0381] The fluoropolyether acids or salts thereof can have any chain structure in which the oxygen atoms in the backbone of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. Two or more types of fluorocarbon groups can be present in the molecule.

[0382] The fluoropolyether acid or its salt is represented by the following formula: CF3-CF2-CF2-O(-CFCF3-CF2-O-) n CFCF3-COOH, CF3-CF2-CF2-O(-CF2-CF2-CF2-O-) n -CF2-CF2COOH, or HOOC-CF2-O(-CF2-CF2-O-) n -(-CF2-O-) m CF2COOH (In the formula, m and n are the same as above.) or a salt thereof.

[0383] These structures are discussed by Kasai in J. Appl. Polymer Sci., 57, 797 (1995). As disclosed therein, such fluoropolyethers can have a carboxylic acid group or salt thereof at one or both ends. Similarly, such fluoropolyethers can have a sulfonic acid or phosphonic acid group or salt thereof at one or both ends. In addition, fluoropolyethers with acid functional groups at both ends can have different groups at each end. For monofunctional fluoropolyethers, the other end of the molecule is usually perfluorinated, but may contain a hydrogen or chlorine atom.

[0384] The fluoropolyether having an acid group at one or both ends has at least two ether oxygens, preferably at least four ether oxygens, and even more preferably at least six ether oxygens. Preferably, at least one of the fluorocarbon groups separating the ether oxygens, more preferably at least two of such fluorocarbon groups, has two or three carbon atoms. Even more preferably, at least 50% of the fluorocarbon groups separating the ether oxygens have two or three carbon atoms. Also, preferably, the fluoropolyether has at least 15 carbon atoms in total, for example, the preferred minimum value of n or n+m in the above repeating unit structure is at least 5. Two or more fluoropolyethers having an acid group at one or both ends can be used in the method according to the present disclosure. Typically, unless special care is taken in the preparation of a single specific fluoropolyether compound, the fluoropolyether may contain multiple compounds in various proportions within the molecular weight range relative to the average molecular weight.

[0385] The fluoropolyether preferably has a number average molecular weight of 800 g / mol or more. The fluoropolyether acid or its salt is preferably less than 6000 g / mol because it may be difficult to disperse it in an aqueous medium. The fluoropolyether acid or its salt is more preferably 800 to 3500 g / mol, even more preferably 900 to 3500 g / mol, and even more preferably 1000 to 2500 g / mol.

[0386] The amount of the fluoropolyether is preferably 5 to 5000 ppm by mass, more preferably 5 to 3000 ppm by mass, and even more preferably 5 to 2000 ppm by mass, with the lower limit being, in this order of preference, 10 ppm, 20 ppm by mass, 30 ppm by mass, and 50 ppm by mass, and the upper limit being, in this order of preference, 1000 ppm by mass, 500 ppm by mass, and 100 ppm by mass.

[0387] The nonionic surfactants have a hydrophobic portion that is usually free of charged groups and is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains water-soluble functional groups such as ethylene ether chains derived from polymerization with ethylene oxide.

[0388] Examples of nonionic surfactants Polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, glycerol esters, and derivatives thereof.

[0389] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene behenyl ether.

[0390] Specific examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether.

[0391] Specific examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and polyethylene glycol monostearate.

[0392] Specific examples of sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0393] Specific examples of polyoxyethylene sorbitan alkyl esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate.

[0394] Examples of glycerol esters include glycerol monomyristate, glycerol monostearate, glycerol monooleate, etc.

[0395] Specific examples of the above derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like.

[0396] The ethers and esters may have an HLB value of 10-18.

[0397] Examples of nonionic surfactants include the Triton (registered trademark) X series (X15, X45, X100, etc.), the Tergitol (registered trademark) 15-S series, the Tergitol (registered trademark) TMN series (TMN-6, TMN-10, TMN-100, etc.), and the Tergitol (registered trademark) L series, all manufactured by The Dow Chemical Company; the Pluronic (registered trademark) R series (31R1, 17R2, 10R5, 25R4 (m-22, n-23), and the Iconol (registered trademark) TDA series (TDA-6, TDA-9, TDA-10), all manufactured by BASF Corporation.

[0398] The nonionic surfactant as the nucleating agent may be any of the above-mentioned nonionic surfactants, and among them, it is preferable to use a nonionic surfactant that does not contain fluorine. For example, it may be ether-type nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkylene alkyl ether, etc.; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, etc.; amine-based nonionic surfactants such as polyoxyethylene alkylamine, alkyl alkanolamide, etc.; etc.

[0399] In the above nonionic surfactants, the hydrophobic group may be any one of an alkylphenol group, a linear alkyl group, and a branched alkyl group.

[0400] The nonionic surfactant may be, for example, a surfactant represented by the following general formula (i): R 3 -OA 5 -H(i) (In the formula, R 3 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms; A 5 is a polyoxyalkylene chain. 3 The number of carbon atoms is preferably 10 to 16, more preferably 12 to 16. The polyoxyalkylene chain may be composed of oxyethylene and oxypropylene. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average number of repetitions of oxypropylene groups is more than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block form or a random form. From the viewpoint of viscosity and stability of the aqueous dispersion, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. 1 It is preferable that the oxypropylene group has an average of 0.5 to 1.5, since this results in good low foaming properties.

[0401] R 3 is more preferably (R')(R'')HC-, where R' and R'' are the same or different linear, branched, or cyclic alkyl groups having a total of at least 5, preferably 7 to 17 carbon atoms. Preferably, at least one of R' or R'' is a branched or cyclic hydrocarbon group.

[0402] Specific examples of the nonionic surfactant include C 13 H 27 -O-(C2H4O)10 -H, C 12 H 25 -O-(C2H4O) 10 -H, C 10 H 21 CH(CH3)CH2-O-(C2H4O)9-H, C 13 H 27 -O-(C2H4O)9-(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) 10 -H, HC(C5H 11 )(C7H 15 )-O-(C2H4O)9-H, etc.

[0403] For example, the nonionic surfactant may be a polyethylene glycol-polypropylene glycol-polyethylene glycol block copolymer.

[0404] Commercially available examples of the nonionic surfactant include Genapol X080 (product name, manufactured by Clariant), the Noigen TDS series, such as Noigen TDS-80 (trade name) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), the Leocol TD series, such as Leocol TD-90 (trade name) (manufactured by Lion Corporation), the Lionol (registered trademark) TD series (manufactured by Lion Corporation), the T-Det A series, such as T-Det A138 (trade name) (manufactured by Harcros Chemicals), and the Tergitol (registered trademark) 15S series (manufactured by Dow Chemical Co.).

[0405] Commercially available examples of the polyoxyethylene alkyl ether include Genapol X080 (product name, manufactured by Clariant), Tergitol 9-S-15 (product name, manufactured by Clariant), Noigen TDS-80 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Leocol TD90 (product name, manufactured by Lion Corporation), and Pronon 104 (product name, manufactured by NOF Corporation).

[0406] The nonionic surfactant is preferably an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, or a mixture thereof. Nonionic surfactants of this type are also commercially available, for example, as TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all product names, manufactured by Dow Chemical Company).

[0407] The hydrophobic group of the nonionic surfactant may be any of an alkylphenol group, a straight-chain alkyl group, and a branched alkyl group.

[0408] The nonionic surfactant may also be a surfactant represented by the following general formula (ii): R 4 -C6H4-OA 6 -H (ii) (In the formula, R 4 is a linear or branched primary or secondary alkyl group having 4 to 12 carbon atoms; A 6 is a polyoxyalkylene chain.

[0409] Examples of the polyoxyethylene alkylphenyl ether nonionic compound include Triton (registered trademark) X-100 (trade name, manufactured by Dow Chemical Company).

[0410] The nonionic surfactant also includes a polyol compound, specifically, those described in WO 2011 / 014715. Typical examples of polyol compounds include compounds having one or more sugar units as polyol units. The sugar units may be modified to contain at least one long chain. Suitable polyol compounds containing at least one long chain moiety include, for example, alkyl glycosides, modified alkyl glycosides, sugar esters, and combinations thereof. Sugars include, but are not limited to, monosaccharides, oligosaccharides, and sorbitan. Monosaccharides include pentoses and hexoses. Typical examples of monosaccharides include ribose, glucose, galactose, mannose, fructose, arabinose, and xylose. Oligosaccharides include oligomers of 2 to 10 identical or different monosaccharides. Examples of oligosaccharides include, but are not limited to, saccharose, maltose, lactose, raffinose, and isomaltose.

[0411] Typically, suitable sugars for use as polyol compounds include cyclic compounds containing a five-membered ring with four carbon atoms and one heteroatom (typically oxygen or sulfur, but preferably an oxygen atom), or a six-membered ring with five carbon atoms and one heteroatom, preferably an oxygen atom, as described above. These further contain at least two or at least three hydroxy groups (-OH groups) attached to the carbon ring atoms. Typically, the sugars are modified in that one or more of the hydrogen atoms of the hydroxy groups (and / or hydroxyalkyl groups) attached to the carbon ring atoms are replaced by a long-chain residue, such that an ether or ester bond is created between the long-chain residue and the sugar moiety. The sugar-based polyol may contain one or more sugar units. The sugar unit or units may be modified with long chain moieties as described above. Specific examples of sugar-based polyol compounds include glycosides, sugar esters, sorbitan esters, and mixtures and combinations thereof.

[0412] A preferred class of polyol compounds are the alkyl or modified alkyl glucosides. These classes of surfactants contain at least one glucose moiety. [ka] (In the formula, x represents 0, 1, 2, 3, 4, or 5; R 1 and R 2 independently represent H or a long chain unit containing at least 6 carbon atoms, with the proviso that R 1 and R 2 At least one of R is not H. 1 and R 2 Representative examples of the fatty alcohol include fatty alcohol residues. Examples of fatty alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. The above formula represents a specific example of an alkyl polyglucoside showing glucose in the pyranose form, however, it is understood that other sugars or the same sugar but in a different enantiomeric or diastereomeric form may be used. Alkyl glucosides are available, for example, by acid-catalyzed reaction of glucose, starch, or n-butyl glucoside with fatty alcohols, which typically result in mixtures of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, Georg Thieme Verlag, 1999). Examples of fatty alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. Alkyl glucosides are also commercially available under the trade names GLUCOPON or DISPONIL from Cognis GmbH, Dusseldorf, Germany.

[0413] Other nonionic surfactants include difunctional block copolymers supplied by BASF as part of the Pluronic® R series, and tridecyl alcohol alkoxylates supplied by BASF as part of the Iconol® TDA series.

[0414] The nonionic surfactant is preferably at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii).

[0415] The amount of the nonionic surfactant is preferably 0.1 to 0.0000001% by mass relative to the aqueous medium. The lower limit of the amount of the nonionic surfactant is, in order of preference, 0.000001% by mass, 0.000005% by mass, and 0.00001% by mass. The upper limit of the amount of the nonionic surfactant is, in order of preference, 0.01% by mass, 0.005% by mass, 0.001% by mass, 0.0005% by mass, and 0.0001% by mass.

[0416] As the nucleating agent, a chain transfer agent, which will be described later, can also be used.

[0417] The chain transfer agent used as the nucleating agent is preferably at least one selected from the group consisting of alkanes and alcohols in terms of polymerization reactivity, crosslinking reactivity, availability, etc. The number of carbon atoms in the alkane is preferably 1 to 6, more preferably 2 to 4, and even more preferably 3 to 4. The number of carbon atoms in the alcohol is preferably 1 to 5, more preferably 1 to 4, and even more preferably 3 to 4. The chain transfer agent is preferably at least one selected from the group consisting of alcohols having 1 to 4 carbon atoms and alkanes having 2 to 4 carbon atoms, and more preferably at least one selected from the group consisting of isopropanol, sec-butanol, and tert-butanol. In particular, by using a chain transfer agent containing a tertiary carbon, more particles can be generated during polymerization.

[0418] As the nucleating agent, a chain transfer agent is preferred, and a chain transfer agent and one or both of a nonionic surfactant and a fluoropolyether are more preferred.When a chain transfer agent and one or both of a nonionic surfactant and a fluoropolyether are used as the nucleating agent, the nucleating agent includes a combination of a chain transfer agent and a nonionic surfactant, a combination of a chain transfer agent and a fluoropolyether, and a combination of a chain transfer agent, a nonionic surfactant and a fluoropolyether.Among them, a combination of a chain transfer agent and a nonionic surfactant is preferred as the nucleating agent.

[0419] The amount of the nucleating agent to be added is preferably 0.001 to 0.1 ppm by mass relative to the aqueous medium, since more particles can be generated during polymerization, and primary particles with smaller average primary particle diameter and aspect ratio can be obtained. The lower limit of the amount of the nucleating agent is, in order of preference, 0.01 ppm by mass, 0.05 ppm by mass, and 0.1 ppm by mass. The upper limit of the amount of the nucleating agent is, in order of preference, 2000 ppm by mass, 1000 ppm by mass, 500 ppm by mass, 100 ppm by mass, 50 ppm by mass, and 10 ppm by mass.

[0420] When a chain transfer agent and a nonionic surfactant are used as the nucleation agent, the mass ratio of the chain transfer agent to the nonionic surfactant (chain transfer agent / nonionic surfactant) is preferably 1000 / 1 to 1 / 5, more preferably 200 / 1 to 1 / 2, 100 / 1 to 1 / 1, and even more preferably 50 / 1 to 2 / 1, since more particles can be generated during polymerization and primary particles having an even smaller average primary particle size and aspect ratio can be obtained.

[0421] In the above polymerization, it is preferable to add a nucleating agent to the aqueous medium before the polymerization reaction is started, or before the concentration of PTFE in the aqueous dispersion reaches 5.0 mass% as the polymerization reaction progresses. By adding a nucleating agent at the beginning of polymerization, more particles can be generated during polymerization, and primary particles with smaller average primary particle size and aspect ratio can be obtained. That is, the nucleating agent may be added before the start of polymerization, may be added at the same time as the start of polymerization, or may be added during the period when the nuclei of PTFE particles are formed after the start of polymerization.

[0422] The timing for adding the nucleating agent is before the start of polymerization or before the polymerization reaction progresses and the PTFE concentration in the aqueous dispersion reaches 5.0 mass%, preferably before the start of polymerization or before the PTFE concentration reaches 3.0 mass%, more preferably before the start of polymerization or before the PTFE concentration reaches 1.0 mass%, even more preferably before the start of polymerization or before the PTFE concentration reaches 0.5 mass%, and particularly preferably before the start of polymerization or simultaneously with the start of polymerization.

[0423] The amount of the nucleating agent to be added is preferably 0.001 to 0.1 ppm by mass relative to the amount of the PTFE obtained, since more particles can be generated during polymerization, and primary particles having smaller average primary particle diameter and aspect ratio can be obtained. The lower limit of the amount of the nucleating agent is, in order of preference, 0.01 ppm by mass, 0.05 ppm by mass, and 0.1 ppm by mass. The upper limit of the amount of the nucleating agent is, in order of preference, 2000 ppm by mass, 1000 ppm by mass, 500 ppm by mass, 100 ppm by mass, 50 ppm by mass, and 10 ppm by mass.

[0424] The polymerization step may further comprise polymerizing tetrafluoroethylene in the presence of a chain transfer agent. Examples of the chain transfer agent include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as isopentane, methane, ethane, propane, isobutane, methanol, ethanol, isopropanol, acetone, various mercaptans, various halogenated hydrocarbons such as carbon tetrachloride, and cyclohexane.

[0425] Bromine compounds or iodine compounds may be used as chain transfer agents. Examples of polymerization methods using bromine compounds or iodine compounds include a method of polymerizing a fluoromonomer in an aqueous medium in the presence of a bromine compound or iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the bromine compounds or iodine compounds used include, for example, compounds represented by the general formula: R a I x Br y (In the formula, x and y are each an integer of 0 to 2, and 1≦x+y≦2 is satisfied; R a is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom). By using a bromine compound or an iodine compound, iodine or bromine is introduced into the polymer and functions as a crosslinking point.

[0426] Examples of the bromine compound or iodine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2 Examples of the iodoperfluoroalkyl group include CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl)-substituted benzene. These compounds may be used alone or in combination with each other.

[0427] Among these, the chain transfer agent is preferably at least one selected from the group consisting of alkanes and alcohols in terms of polymerization reactivity, crosslinking reactivity, availability, etc. The number of carbon atoms in the alkane is preferably 1 to 6, more preferably 1 to 5, even more preferably 2 to 4, and particularly preferably 3 to 4. The number of carbon atoms in the alcohol is preferably 1 to 5, more preferably 1 to 4, and even more preferably 3 to 4. The chain transfer agent is preferably at least one selected from the group consisting of alcohols having 1 to 4 carbon atoms and alkanes having 2 to 4 carbon atoms, and particularly preferably at least one selected from the group consisting of methane, ethane, propane, isobutane, methanol, ethanol, and isopropanol.

[0428] The amount of the chain transfer agent is preferably 0.001 to 10000 ppm by mass relative to the aqueous medium. The amount of the chain transfer agent is more preferably 0.01 ppm by mass or more, even more preferably 0.05 ppm by mass or more, even more preferably 0.1 ppm by mass or more, and especially preferably 0.5 ppm by mass or more, relative to the aqueous medium. The amount of the chain transfer agent is more preferably 1000 ppm by mass or less, even more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, and especially preferably 10 ppm by mass or less, relative to the aqueous medium.

[0429] The chain transfer agent may be added to the reaction vessel all at once before the initiation of polymerization, may be added all at once after the initiation of polymerization, may be added in several divided portions during the polymerization, or may be added continuously during the polymerization.

[0430] In the above-mentioned production method, additives for stabilizing each compound can be used in addition to the above-mentioned polymer (I), polymerization terminator, optional nucleating agent, etc. Examples of the additives include a buffer, a pH adjuster, a stabilizing assistant, and a dispersion stabilizer.

[0431] As the stabilizing aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil, etc. are preferable. The stabilizing aid may be used alone or in combination of two or more. As the stabilizing aid, paraffin wax is more preferable. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but is preferably a saturated hydrocarbon having 12 or more carbon atoms. The melting point of the paraffin wax is usually preferably 40 to 65°C, more preferably 50 to 65°C.

[0432] The amount of the stabilizing aid used is preferably 0.1 to 12% by mass, more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing aid is sufficiently hydrophobic and completely separated from the PTFE dispersion after PTFE polymerization so as not to become a contaminating component. In addition, it is preferable that the stabilizing aid is removed from the aqueous dispersion obtained by polymerization.

[0433] Examples of pH adjusters that can be used include ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, ammonium gluconate, etc. The pH can be measured using a pH meter manufactured by Orion.

[0434] The pH of the aqueous medium when TFE is polymerized is preferably basic. The pH of the aqueous medium may be adjusted by adding a pH adjuster to the aqueous medium. The pH of the aqueous medium when TFE is polymerized is preferably 7.1 or more, more preferably 7.5 or more. By adjusting the pH to basic, the effect of improving the stability of the aqueous dispersion due to the presence of the polymer (I) is further enhanced, and the polymerization of TFE in the aqueous medium proceeds more smoothly.

[0435] In the above-mentioned production method, the polymerization is carried out by charging an aqueous medium, the above-mentioned polymer (I), tetrafluoroethylene, a modified monomer added as required, and other additives as required into a polymerization reactor, stirring the contents of the reactor, and maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to start the polymerization reaction. After the polymerization reaction starts, a monomer, a polymerization initiator, a chain transfer agent, the above-mentioned polymer (I), etc. may be additionally added according to the purpose. The above-mentioned polymer (I) may be added after the polymerization reaction starts.

[0436] The polymerization initiator is not particularly limited as long as it can generate radicals in the above polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, it can also be combined with a reducing agent or the like to initiate polymerization as a redox. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the desired fluoropolymer, and the reaction rate.

[0437] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0438] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and the like. In addition, di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetradecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluorovaleryl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro) peroxide, and the like. Representative examples of the di[perfluoro(or fluorochloro)acyl]peroxides include di(ω-hexafluorobutyryl)peroxide, di(ω-chloro-decafluorohexanoyl)peroxide, di(ω-chloro-tetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0439] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, and sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, and percarbonic acid, organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide, t-butyl permaleate, and t-butyl hydroperoxide. A reducing agent such as sulfites and sulfites may also be contained, and the amount used may be 0.1 to 20 times that of the peroxide.

[0440] For example, when polymerization is carried out at a low temperature of 30° C. or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of the oxidizing agent include persulfates, organic peroxides, potassium permanganate, manganese triacetate, cerium ammonium nitrate, and bromates. Examples of the reducing agent include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of the persulfates include ammonium persulfate and potassium persulfate. Examples of the sulfites include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of the redox initiator. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate.

[0441] Examples of the redox initiator include potassium permanganate / oxalic acid, ammonium persulfate / bisulfite / iron(II) sulfate, ammonium persulfate / sulfite / iron(II) sulfate, ammonium persulfate / sulfite, ammonium persulfate / iron(II) sulfate, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, bromate / sulfite, bromate / bisulfite, and the like, with potassium permanganate / oxalic acid and ammonium persulfate / sulfite / iron(II) sulfate being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged in advance into a polymerization tank, 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 tank and continuously add potassium permanganate thereto.

[0442] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously in an amount (for example, several ppm relative to water concentration) at least at which the polymerization rate does not drop significantly. The upper limit is a range in which the reaction temperature may be increased while removing heat from the equipment side by the polymerization reaction heat, and a more preferable upper limit is a range in which the polymerization reaction heat can be removed from the equipment side.

[0443] In the above polymerization, a decomposing agent or the like may be further added depending on the purpose, so as to adjust the polymerization rate and molecular weight.

[0444] In the above polymerization, TFE may be polymerized in the presence of an anionic hydrocarbon surfactant. By using the anionic hydrocarbon surfactant, the stability of the aqueous dispersion produced by the polymerization is improved, and the polymerization of TFE proceeds smoothly.

[0445] In the above polymerization, TFE may be polymerized substantially in the absence of an anionic hydrocarbon surfactant. The polymerization of TFE in the presence of polymer (I) proceeds smoothly even without the use of an anionic hydrocarbon surfactant.

[0446] In the present disclosure, "substantially in the absence of anionic hydrocarbon surfactant" means that the anionic hydrocarbon surfactant is present in an amount of 10 ppm by mass or less relative to the aqueous medium, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and even more preferably 1 ppb by mass or less.

[0447] Anionic hydrocarbon surfactants have a hydrophilic portion, typically a carboxylate, sulfonate or sulfate, and a hydrophobic portion which is a long chain hydrocarbon moiety such as an alkyl.

[0448] Examples of the anionic hydrocarbon surfactant include Versatic (registered trademark) 10 manufactured by Resolution Performance Products and Avanel S series (S-70, S-74, etc.) manufactured by BASF.

[0449] The anionic hydrocarbon surfactant includes RLM (wherein R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 - is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0450] Specifically, CH3-(CH2) such as lauric acid and lauryl sulfate n -LM (wherein n is an integer of 6 to 17, and L and M are the same as above). Mixtures in which R is an alkyl group having 12 to 16 carbon atoms and LM is sulfate or sodium dodecyl sulfate (SDS) can also be used.

[0451] In addition, the anionic hydrocarbon surfactant R 6 (-LM)2(wherein, R 6 is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. -, -SO3 - , -SO4-, -PO3 - or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group, -ArSO3 - is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0452] In addition, the anionic hydrocarbon surfactant R 7 (-LM)3(wherein, R 7 is a linear or branched alkylidyne group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3 - or COO - where M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group. -ArSO3 - is an aryl sulfonate. Also included are anionic surfactants represented by the following formula:

[0453] The anionic hydrocarbon surfactant also includes siloxane hydrocarbon surfactant. The siloxane hydrocarbon surfactant includes those described in Silicone Surfactants, RM Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of siloxane hydrocarbon surfactant includes a distinct hydrophobic portion and a hydrophilic portion. The hydrophobic portion includes one or more dihydrocarbylsiloxane units, where the substituents on the silicone atom are completely hydrocarbon. These siloxane surfactants can also be considered as hydrocarbon surfactants in the sense that the carbon atoms of the hydrocarbyl group are completely replaced by hydrogen atoms, i.e., the monovalent substituents on the carbon atoms of the hydrocarbyl group are hydrogen, where they may be replaced by halogens such as fluorine.

[0454] The hydrophilic portion of the siloxane hydrocarbon surfactant may include one or more polar moieties that include ionic groups such as sulfates, sulfonates, phosphonates, phosphate esters, carboxylates, carbonates, sulfosuccinates, taurates (as free acids, salts or esters), phosphine oxides, betaines, betaine copolyols, quaternary ammonium salts, etc. The ionic hydrophobic portion may also include ionically functionalized siloxane grafts. Such siloxane hydrocarbon surfactants include, for example, polydimethylsiloxane-graft-(meth)acrylates, polydimethylsiloxane-graft-polyacrylate salts, and polydimethylsiloxane-grafted quaternary amines. The polar portion of the hydrophilic portion of the siloxane hydrocarbon surfactant may include nonionic groups formed by polyethers such as polyethylene oxide (PEO) and mixed polyethylene oxide / propylene oxide polyethers (PEO / PPO); monosaccharides and disaccharides; and water-soluble heterocycles such as pyrrolidinone. The ratio of ethylene oxide to propylene oxide (EO / PO) can be varied in mixed polyethylene oxide / propylene oxide polyethers.

[0455] The hydrophilic portion of the siloxane hydrocarbon surfactant may also contain a combination of ionic and non-ionic moieties, such as ionically end-functionalized or randomly functionalized polyethers or polyols. Preferred are siloxanes with non-ionic moieties, i.e., non-ionic siloxane surfactants.

[0456] 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.

[0457] Siloxane hydrocarbon surfactants are also disclosed in US Pat. No. 6,841,616.

[0458] 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.

[0459] Anionic hydrocarbon surfactants include the sulfosuccinate surfactant Lankropol® K8300 from Akzo Nobel Surface Chemistry LLC. Sulfosuccinate surfactants include diisodecyl sodium sulfosuccinate (Emulsogen® SB10 from Clariant) and diisotridecyl sodium sulfosuccinate (Polirol® TR / LNA from Cesapinia Chemicals).

[0460] Anionic hydrocarbon surfactants include PolyFox (registered trademark) surfactants from Omnova Solutions, Inc. TM PF-156A, PolyFox TM PF-136A, etc.)

[0461] Examples of the anionic hydrocarbon surfactant include those represented by the general formula (α): R 10 -COOM (α) (In the formula, R 10 is a monovalent organic group containing one or more carbon atoms. M is H, a metal atom, NR 11 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 11 R is H or an organic group, and may be the same or different. 11 As H or C 1-10 is preferably an organic group represented by the formula: 1-4 From the viewpoint of surface activity, the organic group R 10 The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. 10 The number of carbon atoms in is preferably 29 or less, more preferably 23 or less. The metal atom of M may be an alkali metal (group 1) or an alkaline earth metal (group 2), and is preferably Na, K or Li. M may be H, a metal atom or NR 11 4 is preferred, H, an alkali metal (group 1), an alkaline earth metal (group 2) or NR 11 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, Na, K or NH4 is even more preferred, Na or NH4 is especially preferred, and NH4 is most preferred.

[0462] Compound (α) includes R 12 -COOM(in the formula, R 12is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms, which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms, which may have a substituent, and these may contain an ether bond. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle, or may form a ring. M is the same as above. ) is also included. Specifically, CH3-(CH2) n -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0463] From the viewpoint of emulsion stability, the compound (α) may be one that does not contain a carbonyl group (excluding the carbonyl group in a carboxyl group). Examples of the hydrocarbon-containing surfactant that does not contain a carbonyl group include a surfactant represented by the following formula (A): R-COO-M(A) (wherein R is an alkyl group, an alkenyl group, an alkylene group, or an alkenylene group having 6 to 17 carbon atoms, which may contain an ether bond. M is H, a metal atom, NR 11 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 11 are the same or different and are H or an organic group having 1 to 10 carbon atoms.) is a preferred example. In the above formula (A), R is preferably an alkyl group or an alkenyl group (which may contain an ether group). The alkyl group or alkenyl group in the above R may be linear or branched. The number of carbon atoms in the above R is not limited, but is, for example, 2 to 29.

[0464] When the alkyl group is linear, R preferably has 3 to 29 carbon atoms, and more preferably has 5 to 23 carbon atoms. When the alkyl group is branched, R preferably has 5 to 35 carbon atoms, and more preferably has 11 to 23 carbon atoms. When the alkenyl group is linear, R preferably has 2 to 29 carbon atoms, and more preferably has 9 to 23 carbon atoms. When the alkenyl group is branched, R preferably has 2 to 29 carbon atoms, and more preferably has 9 to 23 carbon atoms.

[0465] Examples of the alkyl and alkenyl groups include a methyl group, an ethyl group, an isobutyl group, a t-butyl group, and a vinyl group.

[0466] The anionic hydrocarbon surfactant also includes a carboxylic acid type hydrocarbon surfactant. Examples of the carboxylic acid type hydrocarbon surfactant include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, (9,12,15)-linolenic acid, (6,9,12) linolenic acid, eleostearic acid, arachidic acid, 8,11-eicosadienoic acid, mead acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, cerotic acid, montanic acid, melissic acid, crotonic acid, myrisic acid, methyl methacrylate ... Examples of the salts include oleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, linoleic acid, eicosadienoic acid, docosadienoic acid, linolenic acid, pinolenic acid, α-eleostearic acid, β-eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, eicosapentaenoic acid, osbondoic acid, sardine acid, tetracosapentaenoic acid, docosahexaenoic acid, herring acid, and salts thereof. In particular, at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof is preferred. As the salts, those in which the hydrogen of the carboxyl group is a metal atom of the above formula M, NR 11 4. Examples include, but are not limited to, imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent.

[0467] In addition, as the anionic hydrocarbon surfactant, for example, anionic hydrocarbon surfactants described in WO 2013 / 146950 and WO 2013 / 146947 can be used. For example, anionic hydrocarbon surfactants having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, more preferably 9 to 13 carbon atoms can be used. The saturated or unsaturated aliphatic chain may be either a straight chain or a branched chain, or may have a cyclic structure. The hydrocarbon may be aromatic or may have an aromatic group. The hydrocarbon may have a heteroatom such as oxygen, nitrogen, or sulfur.

[0468] Examples of anionic hydrocarbon surfactants include alkyl sulfonates, alkyl sulfates, alkylaryl sulfates, and salts thereof; aliphatic (carboxylic) acids and salts thereof; alkyl phosphates, alkylaryl phosphates, and salts thereof; and among these, alkyl sulfonates, alkyl sulfates, and aliphatic carboxylic acids and salts thereof are preferred.

[0469] As the alkyl sulfate or its salt, ammonium lauryl sulfate and sodium lauryl sulfate are preferred. As the aliphatic carboxylic acid or a salt thereof, succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or a salt thereof is preferred.

[0470] In the above polymerization, TFE can be polymerized in the presence of a fluorine-containing surfactant (excluding compounds having a functional group capable of reacting in radical polymerization and a hydrophilic group). By using a fluorine-containing surfactant, the stability of the aqueous dispersion produced by polymerization is improved, and the polymerization of TFE proceeds smoothly.

[0471] In the above polymerization, it is also preferable to polymerize TFE substantially in the absence of a fluorine-containing surfactant (excluding compounds having a functional group and a hydrophilic group that can react in radical polymerization). The polymerization of TFE in the presence of polymer (I) proceeds smoothly even without the use of a fluorine-containing surfactant. In the above polymerization, a composition that is substantially free of a fluorine-containing surfactant can be easily obtained by polymerizing TFE substantially in the absence of a fluorine-containing surfactant.

[0472] In the present disclosure, "substantially in the absence of a fluorinated surfactant" means that the fluorinated surfactant is present at 10 ppm by mass or less relative to the aqueous medium, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and even more preferably 1 ppb by mass or less.

[0473] Examples of the fluorine-containing surfactant include those described above as fluorine-containing surfactants that are preferably not substantially contained in the composition of the present disclosure.

[0474] In the method for producing PTFE, the amount of adhesion is preferably 3.0 mass% or less, more preferably 2.0 mass% or less, more preferably 1.0 mass% or less, even more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, and particularly preferably 0.6 mass% or less, based on the finally obtained PTFE.

[0475] By the above polymerization, polytetrafluoroethylene and an aqueous dispersion containing the polymer (I) are obtained. The composition of the present disclosure can further include a step of recovering the aqueous PTFE dispersion obtained by the above-mentioned method, A step of agglomerating PTFE in the PTFE aqueous dispersion; recovering the agglomerated PTFE; and A process of drying the recovered PTFE at 100 to 300 ° C. The compound can be suitably obtained by a production method including at least one of the steps.

[0476] A powder can be produced by agglomerating the PTFE contained in the aqueous dispersion. The composition of the present disclosure may be a powder. The aqueous dispersion containing PTFE and polymer (I) can be used for various applications as a powder after being subjected to post-treatment such as concentration as necessary, coagulation, washing, and drying. When coagulation is performed on the aqueous dispersion of PTFE, the aqueous dispersion obtained by polymerization of polymer latex or the like is usually diluted with water to a polymer concentration of 10 to 25% by mass (preferably a polymer concentration of 10 to 20% by mass), and the pH is adjusted to neutral or alkaline in some cases, and then the mixture is stirred more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be performed while stirring while adding water-soluble organic compounds such as methanol and acetone, inorganic salts such as potassium nitrate and ammonium carbonate, and inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid as coagulants. The coagulation may also be performed continuously using an in-line mixer or the like.

[0477] By adding pigments for coloring or various fillers for improving mechanical properties before or during the above-mentioned aggregation, it is possible to obtain a pigmented or filled powder composition in which the pigments and fillers are uniformly mixed.

[0478] The wet powder obtained by agglomerating the PTFE and polymer (I) is usually dried using a means such as vacuum, high frequency, or hot air while keeping the wet powder in a state where it is not very fluid, preferably in a state where it is left stationary. Friction between powders, especially at high temperatures, generally has an undesirable effect on fine powder-type PTFE. This is because particles made of this type of PTFE have the property of easily fibrillating even with a small shear force and losing the original stable particle structure. The drying can be performed at a drying temperature of 10 to 300°C (preferably 10 to 250°C), preferably 100 to 300 (preferably 100 to 250°C)°.

[0479] When the composition of the present disclosure is a powder, the 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 above average particle size is a value measured in accordance with JIS K 6891.

[0480] When the composition of the present disclosure is in the form of a powder, the composition of the present disclosure preferably contains polymer (I) and polytetrafluoroethylene in total at 90% by mass or more, preferably at 99% by mass or more, and more preferably substantially 100% by mass.

[0481] The composition of the present disclosure has extensibility and non-melt processability, and is useful as a raw material for an extruded body (porous body). The composition of the present disclosure can be stretched to obtain an extruded body having excellent breaking strength and stress relaxation time. For example, a powder of the composition of the present disclosure mixed with an extrusion aid is paste-extruded, rolled as necessary, and dried to remove the extrusion aid, and then stretched in at least one direction to obtain an extruded body. By stretching, the PTFE of the composition of the present disclosure is easily fibrillated, and the composition becomes an extruded body consisting of nodes and fibers. This extruded body is also a porous body with a high porosity.

[0482] The present disclosure also relates to an extruded body comprising the above-described composition. The stretched body of the present disclosure can be produced by paste extrusion rolling the above-mentioned composition, followed by unsintering or semi-sintering, and stretching in at least one direction (preferably by roll stretching in the rolling direction and then stretching in the width direction with a tenter). That is, the stretched body of the present disclosure may be a uniaxially stretched film obtained by roll stretching the extrudate in the extrusion direction, or a biaxially stretched film obtained by stretching the uniaxially stretched film in the width direction with a tenter or the like. The extrudate may be subjected to semi-sintering treatment before stretching.

[0483] As the stretching conditions, a speed of 5 to 2000% / sec and a stretching ratio of 200% or more are preferably adopted. By stretching, the PTFE in the composition is easily fibrillated, and a stretched body consisting of nodes and fibers is obtained. The stretched body of the present disclosure may contain only PTFE and polymer (I), or may contain PTFE, polymer (I) and the above-mentioned pigment or filler, but is preferably one containing only PTFE and polymer (I).

[0484] The stretched body of the present disclosure preferably has a porosity in the range of 30% to 99%. The porosity is more preferably 40% or more, even more preferably 50% or more, even more preferably 60% or more, and particularly preferably 70% or more. If the proportion of PTFE in the stretched body is too small, the strength of the stretched body may be insufficient, so the porosity is preferably 95% or less, more preferably 90% or less. The porosity of the stretched body can be calculated from the following formula using the density ρ of the stretched body. Porosity (%)=[(2.2-ρ) / 2.2]×100 In the above formula, 2.2 is the true density of PTFE (g / cm 3 ). When the stretched body is in the form of a film or sheet, the mass of a sample cut to a specific size is measured using a precision balance, and the density of the sample is calculated from the measured mass and film thickness using the following formula. ρ=M / (4.0×12.0×t) ρ=density (film density) (g / cm3) M=mass (g) t = film thickness (cm) The above measurements and calculations are carried out at three locations, and the average value is taken as the film density. The film thickness is measured by using a film thickness meter to measure the total film thickness of five stacked stretched bodies, and dividing the measured value by five to obtain the film thickness of one sheet. When the elongated body is cylindrical, the density ρ of the elongated body is determined by measuring the mass of a sample cut to a certain length using a precision balance, and calculating the density of the sample from the measured mass and outer diameter of the sample using the following formula. ρ=M / (r×r×π)×L ρ=density (g / cm3) M=mass (g) r=radius (cm) L=Length(cm) π=pi The outer diameter of the elongated body is measured using a laser displacement sensor, and the radius is calculated by dividing the outer diameter by two. The above measurements and calculations are carried out at three locations, and the average value is taken as the density.

[0485] The present disclosure further provides an elongated body comprising a polymer (I) including polytetrafluoroethylene and polymerization units (I) based on a monomer represented by the following general formula (I), and having a breaking strength A of 10.0 N or more: CX 1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (I) (In the formula, X 1 and X 3 are each independently F, Cl, H or CF3; A 0 is an anionic group; X 2 is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

[0486] In the stretched body of the present disclosure, the polytetrafluoroethylene and the polymer (I) are the same as those described for the composition of the present disclosure, and suitable embodiments of each can be adopted.

[0487] The stretched body of the present disclosure preferably has a breaking strength A of 13.0 N or more, more preferably 16.0 N or more, and even more preferably 19.0 N or more. The higher the breaking strength A, the better, but the upper limit of the breaking strength A is, for example, 50.0 N.

[0488] The breaking strength of the stretched body was clamped and fixed between movable jaws having a gauge length of 5.0 cm, and a tensile test was carried out at 25° C. and a speed of 300 mm / min. The strength at which the stretched body broke was taken as breaking strength A.

[0489] The stretched body of the present disclosure preferably has a stress relaxation time of 50 seconds or more, more preferably 80 seconds or more, even more preferably 100 seconds or more, and may be 150 seconds or more. The stress relaxation time is a value measured by the following method. The stress relaxation time of the above-mentioned stretched specimen is measured by attaching both ends of the stretched specimen to fixtures to create a taut sample of 8 inches (20 cm) in length, holding the specimen at 390°C in an oven and inserting the fixtures into the oven through a (covered) slit in the side of the oven. The time required for the sample to break from the time of insertion into the oven is the stress relaxation time.

[0490] The stretched product of the present disclosure preferably has an endothermic peak temperature between 325 and 350° C. In addition, the stretched product of the present disclosure preferably has an endothermic peak temperature between 325 and 350° C. and between 360 and 390° C. The endothermic peak temperature is a temperature corresponding to a maximum value in a heat of fusion curve when the stretched product is heated at a rate of 10° C. / min using a differential scanning calorimeter [DSC].

[0491] The stretched body of the present disclosure preferably has a porosity in the range of 30% to 99%. The porosity is more preferably 40% or more, even more preferably 50% or more, even more preferably 60% or more, and particularly preferably 70% or more. If the proportion of PTFE in the stretched body is too small, the strength of the stretched body may be insufficient, so the porosity is preferably 95% or less, more preferably 90% or less. The porosity of the stretched body can be calculated from the following formula using the density ρ of the stretched body. Porosity (%)=[(2.2-ρ) / 2.2]×100 In the above formula, 2.2 is the true density of PTFE (g / cm 3 ). The density ρ of the stretched body is measured in the same manner as described above.

[0492] In the stretched product of the present disclosure, the content of polymer (I) is preferably 0.0001% by mass or more and 20% by mass or less based on polytetrafluoroethylene. In the stretched product of the present disclosure, the lower limit of the content of polymer (I) is more preferably 0.001% by mass, even more preferably 0.01% by mass, and particularly preferably 0.1% by mass, based on polytetrafluoroethylene. The upper limit is more preferably 10% by mass, even more preferably 6% by mass, even more preferably 4% by mass, especially preferably 2% by mass or less, particularly preferably 1.5% by mass or less, and most preferably 1% by mass or less. The content of the polymer (I) can be determined by solid-state NMR measurement.

[0493] The stretched body of the present disclosure is preferably substantially free of fluorine-containing surfactant. In the present disclosure, "substantially free of fluorine-containing surfactant" means that the fluorine-containing surfactant is 1 ppm by mass or less relative to polytetrafluoroethylene. The content of the fluorine-containing surfactant is preferably 100 ppb by mass or less, more preferably 10 ppb by mass or less, even more preferably 1 ppb by mass or less, and particularly preferably, the fluorine-containing surfactant is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS). The fluorine-containing surfactant is a surfactant containing a fluorine atom and has a molecular weight of 800 or less. Examples of the fluorine-containing surfactant include the fluorine-containing surfactants described in the composition of the present disclosure. Specifically, fluorine-containing surfactants having a LogPOW of 3.5 or less can be mentioned, for example, carboxylic acid surfactants, sulfonic acid surfactants, etc., and examples of these surfactants include perfluorocarboxylic acid (I) represented by general formula (I), ω-H perfluorocarboxylic acid (II) represented by general formula (II), perfluoropolyether carboxylic acid (III) represented by general formula (III), perfluoroalkyl alkylene carboxylic acid (IV) represented by general formula (IV), alkoxy fluorocarboxylic acid (V) represented by general formula (V), perfluoroalkyl sulfonic acid (VI) represented by general formula (VII), ω-H perfluoro sulfonic acid (VII) represented by general formula (VII), perfluoroalkyl alkylene sulfonic acid (VIII) represented by general formula (VIII), alkyl alkylene carboxylic acid (IX) represented by general formula (IX), fluorocarboxylic acid (X) represented by general formula (X), alkoxy fluoro sulfonic acid (XI) represented by general formula (XI), compound (XII) represented by general formula (XII), compound (XIII) represented by general formula (XIII), etc.

[0494] The stretched body of the present disclosure can be obtained by stretching the composition of the present disclosure.

[0495] The elongated body of the present disclosure is also preferably in the form of a film, a tube, a fiber, or a rod.

[0496] When the stretched body of the present disclosure is a membrane (stretched membrane or porous membrane), it can be stretched by a known PTFE stretching method. Preferably, a sheet-like or rod-like paste extrudate is roll-stretched in the extrusion direction to obtain a uniaxially stretched membrane. Furthermore, a biaxially stretched film can also be obtained by stretching the film in the width direction using a tenter or the like. It is also preferable to carry out a semi-baking treatment before stretching.

[0497] The stretched body of the present disclosure is a porous body having a high porosity, and can be suitably used as a filter medium for various precision filtration filters such as air filters and chemical filters, a support material for polymer electrolyte membranes, etc. It is also useful as a material for products used in the fields of textiles, medical care, electrochemicals, sealing materials, air filtration, ventilation / internal pressure adjustment, liquid filtration, general consumer goods, etc. Specific applications are given below as examples.

[0498] Electrochemical Field Dielectric material prepreg, EMI shielding material, heat transfer material, etc. More specifically, printed wiring board, electromagnetic shielding material, insulating heat transfer material, insulating material, etc. Sealing materials field Gaskets, packings, pump diaphragms, pump tubes, aircraft sealing materials, etc.

[0499] Air Filtration Field ULPA filters (for semiconductor manufacturing), HEPA filters (for hospitals and semiconductor manufacturing), cylindrical cartridge filters (for industrial use), bag filters (for industrial use), heat-resistant bag filters (for exhaust gas treatment), heat-resistant pleated filters (for exhaust gas treatment), SINBRAN filters (for industrial use), catalyst filters (for exhaust gas treatment), adsorbent filters (for HDD installation), adsorbent vent filters (for HDD installation), vent filters (for HDD installation and others), vacuum cleaner filters (for vacuum cleaners), general-purpose multi-layer felt material, GT cartridge filters (for GT compatible products), cooling filters (for electronic equipment housings), etc.

[0500] Ventilation / internal pressure regulation field Freeze-drying materials such as freeze-drying containers, automotive ventilation materials for electronic circuits and lamps, container applications such as for container caps, protective ventilation applications for electronic devices including small devices such as tablet terminals and mobile phones, medical ventilation applications, etc.

[0501] Liquid Filtration Semiconductor liquid filtration filters (for semiconductor manufacturing), hydrophilic PTFE filters (for semiconductor manufacturing), chemical filters (for chemical liquid treatment), pure water production line filters (for pure water production), backwash type liquid filtration filters (for industrial wastewater treatment), etc.

[0502] General consumer goods field Clothing, cable guides (movable wires for motorcycles), motorcycle clothing, cast liners (medical supports), vacuum cleaner filters, bagpipes (musical instruments), cables (signal cables for guitars, etc.), strings (for stringed instruments), etc.

[0503] Textiles PTFE fiber (textile material), sewing thread (textile), weaving thread (textile), rope, etc.

[0504] Medical field Implants (extended products), artificial blood vessels, catheters, general surgery (tissue reinforcement materials), head and neck products (dura substitutes), oral health (tissue regenerative medicine), orthopedics (bandages), etc.

[0505] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0506] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0507] The values ​​in the examples were measured by the following methods.

[0508] Average primary particle size The 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 length average primary particle diameter determined by measuring the unidirectional diameter using a transmission electron microscope were measured to prepare a calibration curve. Using this calibration curve, the average primary particle diameter was determined from the measured transmittance of the 550 nm projected light for each sample. The average primary particle size can be measured by dynamic light scattering. In dynamic light scattering, an aqueous fluoropolymer dispersion adjusted to a fluoropolymer solids concentration of approximately 1.0% by mass is prepared, and measurements are taken at 25°C and 70 cumulative times using an ELSZ-1000S (Otsuka Electronics Co., Ltd.). The refractive index of the solvent (water) is 1.3328, and the viscosity of the solvent (water) is 0.8878 mPa s.

[0509] Standard specific gravity (SSG) Using samples molded in accordance with ASTM D 4895 89, the measurement was performed by the water displacement method in accordance with ASTM D 792.

[0510] Endothermic peak temperature For the PTFE powder obtained in the examples, a heat of fusion curve was drawn using a differential scanning calorimeter (DSC) at a temperature rise rate of 10°C / min, and the temperature corresponding to the maximum value of the endothermic peak appearing in the heat of fusion curve was determined as the endothermic peak temperature of PTFE.

[0511] Modified monomer unit content The HFP content was calculated by pressing PTFE powder to produce a thin film disk, measuring the infrared absorbance of the thin film disk by FT-IR at 982 cm -1 Absorbance at / 935cm -1 The absorbance ratio was calculated by multiplying the absorbance ratio at The PMVE unit content is solid 19 The following formula was used to calculate the F-MAS NMR spectrum. X = (4B / 3) / (A+(B / 3)) x 100 X: Content of PMVE units (mol%) A: -120ppm signal integral B: Integrated value of the CF signal at -52 ppm The chemical shift value was determined by setting the peak top of the signal derived from the main chain of PTFE at −120 ppm. The content of CH2=CF(CF2OCFCF3COONH4) (hereinafter also referred to as "modified monomer a") units was calculated from the total amount of modified monomer a charged.

[0512] Solid concentration 1 g of the aqueous dispersion is 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 is expressed as a percentage.

[0513] Content of polymer A and polymer D The contents of polymer A and polymer D contained in the PTFE powder are 19 The following formula was used to calculate the F-MAS NMR spectrum. Y = (4B / (5A+3B)) x 100 Y: Polymer A or Polymer D content (mol%) A: -120ppm signal integral B: Sum of integrals of CF2 and CF3 signals at -83 ppm The chemical shift value was determined by setting the peak top of the signal derived from the main chain of PTFE at −120 ppm.

[0514] Extrusion pressure measurement The extrusion pressure was determined by the following method in accordance with the method described in JP 2002-201217 A. 21.7 g of a lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon Corp.) was added to 100 g of the PTFE powder obtained in the example, and mixed in a glass bottle at room temperature for 3 minutes. The glass bottle was then left at room temperature (25°C) for at least 1 hour before extrusion to obtain a lubricated resin. The lubricated resin was paste-extruded at room temperature through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 to obtain a uniform bead (beading; extrusion molded body). The extrusion speed, i.e., the ram speed, was 20 inches / min (51 cm / min). The extrusion pressure was determined by measuring the load when the extrusion load reached equilibrium in the paste extrusion and dividing it by the cross-sectional area of ​​the cylinder used for the paste extrusion.

[0515] The elongation test and the measurement of breaking strengths A to D were performed in accordance with the method described in JP-A-2002-201217, as described below. Stretching test A The bead obtained by the above paste extrusion is heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) is then cut to the appropriate length, clamped at each end with a clamp distance of 1.5 inches (38 mm) between the clamps, and heated to 300°C in an air circulating oven. The clamps are then separated at a desired speed (stretch rate) until a separation distance corresponding to the desired stretch (total stretch) is achieved, and a stretch test (stretch test) is performed. This stretching method essentially follows the method disclosed in U.S. Pat. No. 4,576,869, except for the extrusion speed (51 cm / min instead of 84 cm / min). "Stretch" is the increase in length due to stretching, usually expressed as a percentage of the original length. In the above preparation method, the stretch rate is 1000% / sec and the total stretch is 2400%.

[0516] Breaking strength A The stretched bead obtained in stretching test A (produced by stretching the bead) was clamped and fixed between movable jaws having a gauge length of 5.0 cm, and a tensile test was performed at 25°C and a speed of 300 mm / min. The strength at the time of break was measured as breaking strength A.

[0517] Breaking strength B A stretched bead was obtained in the same manner as in stretch test A, except that the clamp distance was changed to 2.0 inches (51 mm) and the stretch speed was changed to 100% / sec. Breaking strength B was measured in the same manner as in the measurement of breaking strength A, except that the obtained stretched bead was used.

[0518] Breaking strength C The wet PTFE powder obtained in the example was dried at 240° C. for 18 hours to obtain a PTFE powder. Breaking strength C was measured in the same manner as in the measurement of breaking strength A, except that the obtained PTFE powder was used.

[0519] Breaking strength D The wet PTFE powder obtained in the example was dried at 240° C. for 18 hours to obtain a PTFE powder. The obtained PTFE powder was used to measure the breaking strength D in the same manner as in the measurement of breaking strength A, except that the clamp distance in the stretching test was changed to 2.0 inches (51 mm) and the stretching speed was changed to 100% / sec.

[0520] Stress relaxation time It was determined by the following method in accordance with the method described in JP-A-2002-201217. Both ends of the stretched bead from stretch test A above are attached to a fixture to produce a taut bead sample with a total length of 8 inches (20 cm). The oven is maintained at 390°C and the fixture is inserted into the oven through a (covered) slit in the side of the oven. The time it takes for the bead sample to break from the point of insertion into the oven is measured as the stress relaxation time.

[0521] Appearance of the stretched body The appearance of the stretched bead (produced by stretching the bead) obtained in the above stretching test A is visually observed. Uniform: The appearance of the stretched bead was uniform. Non-uniform: The appearance of the stretched bead was non-uniform, with cracks, ripples, and uneven density observed in the stretched bead.

[0522] Aspect Ratio An aqueous dispersion diluted to a solids concentration of approximately 1% by mass was observed with a scanning electron microscope (SEM), and images of more than 400 randomly selected particles were processed to determine the average ratio of their long diameter to their short diameter.

[0523] Method for measuring the content of dimer and trimer of monomer D in polymer D (1) Extraction from aqueous solution The solid content of the aqueous solution of the polymer was measured, and an amount of the aqueous solution equivalent to 0.2 g of the solid content of the polymer was weighed. Then, the aqueous solution was combined with the water contained in the aqueous solution, and water and methanol were added so that the volume ratio of water to methanol was 50 / 50 (volume %) to obtain a mixed solution containing the polymer, water, and methanol. Then, the obtained mixed solution was centrifuged at 4000 rpm for 1 hour, and the supernatant containing the polymer was collected as an extract. The extract was analyzed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD) to obtain a chromatogram of the extract. The contents of dimer and trimer monomers contained in the extract were determined by converting the integral values ​​of the peaks derived from dimer and trimer monomers appearing in the chromatogram of the extract into the contents of dimer and trimer monomers using a calibration curve.

[0524] (2) Monomer calibration curve Five levels of methanol standard solutions of monomers with known contents ranging from 1 ng / mL to 100 ng / mL were prepared, and measurements were performed using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The relationship between the content of each monomer and the peak integral value for that content was plotted to create a calibration curve (first order approximation) for each monomer. Next, the calibration curves (first order approximation) for each monomer were used to create calibration curves for the dimers and trimers of each monomer.

[0525] Measurement equipment configuration and LC-MS measurement conditions [Table 1]

[0526] The limit of quantification for this measurement configuration is 1 ng / mL.

[0527] In the examples, the compound of the formula: CH2=CF(CF2OCFCF3COONH4) A homopolymer (number average molecular weight 90,000, weight average molecular weight 190,000) (hereinafter referred to as "polymer A") of a monomer (modified monomer a) represented by the formula: was used. The number average molecular weight and weight average molecular weight of the polymer were measured by gel permeation chromatography (GPC) using GPC HLC-8020 manufactured by Tosoh Corporation, columns manufactured by Shodex Corporation (one GPC KF-801, one GPC KF-802, and two GPC KF-806M connected in series) and tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as a standard.

[0528] Example 1 In a 6L SUS reactor equipped with a stirrer, 3560g of deionized water, 104g of paraffin wax, 5.37g of polymer A, and 77.3mg of modified monomer a were placed. Ammonia water was added to adjust the pH to 9.1. The contents of the reactor were then heated to 70°C while being aspirated, and simultaneously purged with TFE to remove oxygen from the reactor, and the contents were stirred. 0.8g of HFP was added to the reactor, and then TFE was added until the pressure reached 0.73MPaG. 17.9mg of ammonium persulfate (APS) initiator dissolved in 20g of deionized water was injected into the reactor, and the reactor was brought to a pressure of 0.83MPaG. After the injection of the initiator, a drop in pressure occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 0.78MPaG. When the amount of TFE consumed in the reaction reached about 180g, the supply of TFE and stirring were stopped. The gas in the reactor was then slowly released until the pressure in the reactor reached 0.02 MPaG. TFE was then fed until the pressure in the reactor reached 0.78 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 1250 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented until it reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solid content concentration of the obtained PTFE aqueous dispersion was 25.7 mass%, and the average primary particle size was 249 nm. The resulting PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, coagulated under high-speed stirring conditions, and the coagulated wet powder was dried at 210°C for 18 hours. The various physical properties of the resulting PTFE powder were measured. The results are shown in the table.

[0529] Example 2 Polymerization was carried out in the same manner as in Example 2, except that the modified monomer a in Example 1 was changed from 77.3 mg to 9.7 mg, and 0.8 g of HFP was changed to 0.27 g of PMVE. The solid content concentration of the obtained PTFE aqueous dispersion was 24.4 mass%, and the average primary particle size was 275 nm. In addition, a PTFE powder was obtained in the same manner as in Example 1, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0530] Example 3 Polymerization was carried out in the same manner as in Example 1, except that 14.3 mg of hydroquinone in Example 1 was not injected into the reactor. The solid content concentration of the obtained PTFE aqueous dispersion was 25.4 mass%, and the average primary particle size was 242 nm. In addition, a PTFE powder was obtained in the same manner as in Example 1, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0531] Example 4 In a SUS reactor with a 3L capacity and a stirrer, 1800g of deionized water, 90g of paraffin wax, 2.70g of polymer A, and 38.9mg of modified monomer a were placed. Ammonia water was added to adjust the pH to 9.1. The reactor contents were then heated to 80°C while being aspirated, and simultaneously purged with TFE to remove oxygen from the reactor, and the contents were stirred. 2.3g of HFP was added to the reactor, and then TFE was added until the pressure reached 1.50MPaG. 9.0mg of ammonium persulfate (APS) initiator was injected into the reactor. After the initiator was injected, a drop in pressure occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 1.50MPaG. When the amount of TFE consumed in the reaction reached about 90g, the supply of TFE and stirring were stopped. Next, the gas in the reactor was slowly released until the pressure in the reactor reached atmospheric pressure, and the reactor was further held under vacuum for 1 minute. Then, TFE was supplied until the pressure in the reactor reached 2.50 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 180 g, 14.4 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 600 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented until it reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solid content concentration of the obtained PTFE aqueous dispersion was 26.9 mass%, and the average primary particle size was 196 nm. The obtained PTFE aqueous dispersion was diluted with deionized water to a solid content concentration of about 10 mass%, coagulated under high-speed stirring conditions, and the coagulated wet powder was dried at 210 ° C for 18 hours. Various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0532] [Table 2]

[0533] [Table 3]

[0534] Preparation Example 1 A reactor was charged with 220 g of monomer D represented by CH2=CF(CF2OCFCF3COOH) and 513 g of water, and further added with 0.5 mol % of ammonium persulfate (APS) based on monomer D. The mixture was heated and stirred at 60°C for 24 hours under a nitrogen atmosphere to obtain an aqueous solution of polymer D D-1 containing polymer D, which is a homopolymer of CH2=CF(CF2OCFCF3COOH). As a result of GPC analysis of the aqueous solution of polymer D D-1 obtained, polymer D had Mw of 180,000, Mn of 86,000, and the content of dimers and trimers was 2.0% by mass based on polymer D.

[0535] Water was added to the obtained polymer D aqueous solution D-1 to adjust the concentration of polymer D to 5.0% by mass, and then ultrafiltration was performed by contacting the solution with an ultrafiltration membrane (molecular weight cutoff 50,000 Da, made of polyethylene) at 30 ° C. and a water pressure of 0.1 MPa. Ultrafiltration was continued while appropriately injecting water until the filtrate was finally dissolved in an amount of water 7 times the amount of the aqueous solution, to obtain a polymer D aqueous solution D-2. As a result of GPC analysis of the obtained polymer D aqueous solution D-2, the polymer D had Mw of 180,000, Mn of 140,000, and the content of dimers and trimers was less than 1 ppm relative to the polymer D. The concentration of the obtained polymer D aqueous solution D-2 was 5.0% by mass.

[0536] Example 5 In a 6L SUS reactor equipped with a stirrer, 3457g of deionized water, 180g of paraffin wax, 107.4g of polymer D aqueous solution D-2, and 1.1g of 1.0% by mass aqueous isopropanol solution were placed. Ammonia water was added to adjust the pH to 9.1. The contents of the reactor were then heated to 70°C while being aspirated and purged with TFE at the same time to remove oxygen from the reactor, and the contents were stirred. 0.54g of PMVE was added to the reactor, and then TFE was added until the pressure reached 0.73MPaG. 17.9mg of ammonium persulfate (APS) initiator dissolved in 20g of deionized water was injected into the reactor, and the reactor was brought to a pressure of 0.83MPaG. After the injection of the initiator, a drop in pressure occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 0.78MPaG. When the amount of TFE consumed in the reaction reached about 180 g, the supply of TFE and stirring were stopped. The gas in the reactor was then slowly released until the pressure in the reactor reached 0.02 MPaG. TFE was then supplied until the pressure in the reactor reached 0.78 MPaG, and stirring was started again to continue the reaction. When the amount of TFE consumed in the reaction reached about 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached about 1200 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. After that, the pressure in the reactor was vented until it reached normal pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table.

[0537] The obtained PTFE aqueous dispersion was diluted with deionized water to a solid content of about 10% by mass, coagulated under high-speed stirring conditions, and the coagulated wet powder was dried at 210°C for 18 hours. Various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0538] Example 6 Polymerization was carried out in the same manner as in Example 5, except that the amount of the aqueous isopropanol solution added was changed to 2.1 g. Various physical properties of the resulting aqueous PTFE dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0539] Example 7 Polymerization was carried out in the same manner as in Example 5, except that the isopropanol aqueous solution was changed to 1.8 g of an aqueous solution of Triton X-100 (trade name, manufactured by Dow Chemical Company) with a concentration of 0.1% by mass (hereinafter referred to as "Triton aqueous solution"). Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0540] Example 8 Polymerization was carried out in the same manner as in Example 5, except that 0.9 g of a 0.1 mass% Triton aqueous solution was further added to the reactor together with the isopropanol aqueous solution. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in Table 1. The measurement results of the breaking strength are also shown in Table 1.

[0541] Example 9 Polymerization was carried out in the same manner as in Example 5, except that 1.8 g of a 0.1 mass% Triton aqueous solution was further added to the reactor together with the isopropanol aqueous solution. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0542] Example 10 Polymerization was carried out in the same manner as in Example 5, except that PMVE was changed to 2.4 g of HFP. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0543] Example 11 Polymerization was carried out in the same manner as in Example 10, except that 1.8 g of a 0.1 mass% Triton aqueous solution was further added to the reactor together with the isopropanol aqueous solution. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0544] Example 12 Polymerization was carried out in the same manner as in Example 8, except that the Triton aqueous solution put into the reactor was changed to 1.25 g of a 0.1 mass% Triton aqueous solution, the amount of PMVE added was changed to 0.27 g, and the pressure was kept constant without stopping the supply of TFE and stirring when the amount of TFE consumed in the reaction reached about 180 g. Various physical properties of the obtained PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0545] Example 13 Polymerization was carried out in the same manner as in Example 5, except that the aqueous isopropanol solution was not placed in the reactor. Various physical properties of the resulting PTFE aqueous dispersion were measured. The results are shown in the table. A PTFE powder was obtained in the same manner as in Example 5, and various physical properties of the obtained PTFE powder were measured. The results are shown in the table.

[0546] [Table 4]

[0547] [Table 5]

[0548] [Table 6]

Claims

1. Polytetrafluoroethylene, The polymerized unit (I) based on the monomer represented by the following general formula (I) has a number average molecular weight of 0.3×10 ４ The polymer (I) is The content of the polymerized unit (I) in the polymer (I) is 60 mol% or more, The content of the polymer (I) is 0.001% by mass or more and 20% by mass or less based on the polytetrafluoroethylene, Substantially free of fluorine-containing surfactants A stretched body characterized by: CX １ X ３ =CX ２ R(-CZ １ Z ２ -A ０ ) ｍ (I) (In the formula, X １ and X ３ are each independently F, Cl, H or CF ３ and ０ is an anionic group; X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; and m is an integer of 1 or more.

2. 2. The stretched body according to claim 1, wherein the stretched body is clamped and fixed between movable jaws having a gauge length of 5.0 cm, and a tensile test is carried out at 25° C. and a speed of 300 mm / min., and the breaking strength, which is the strength at which the stretched body breaks, is 10.0 N or more.

3. 3. The stretched body according to claim 1 or 2, wherein both ends of the stretched body are connected to a fixture to form a taut sample having a total length of 8 inches (20 cm), an oven is maintained at 390°C, the fixture is inserted into the oven through a covered slit in the side of the oven, and the stress relaxation time, which is the time required from the time of insertion into the oven until the sample breaks, is 50 seconds or more.

4. The stretched body according to any one of claims 1 to 3, wherein an endothermic peak temperature, which is a temperature corresponding to a maximum value in a heat of fusion curve when the stretched body is heated at a rate of 10°C / min using a differential scanning calorimeter [DSC], is between 325°C and 350°C.

5. The anionic group may be a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or a -C(CF ３ ) ２ OM (wherein M is -H, a metal atom, -NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium; R ７ The stretched body according to any one of claims 1 to 4, wherein the anionic group is

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