Composition and stretched body

Abstract

To provide a composition having superior stretchability.SOLUTION: Provided is a composition comprising a polytetrafluoroethylene and a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I), the composition having a standard specific gravity of 2.200 or less: CX1X3=CX2R(-CZ1Z2-A0)m (I) (wherein X1 and X3 are each independently F, Cl, H, or CF3; A0 is an anionic group; X2 is H, F, an alkyl group, or a fluorine-containing alkyl group; R is a linking group; Z1 and Z2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or more).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to compositions and drawn 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. This unique property is used in applications such as clothing and separation membranes.

[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 polytetrafluoroethylene microparticles 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 (provided 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 Equation 1, R f is a perfluoroperfluoroalkylene group having 1 to 6 carbon atoms, M is an alkali metal ion or an ammonium ion, and in formula 2, X is 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, the method comprising 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 that is excellent in stretchability. [Means for solving the problem]

[0007] The present disclosure relates to a composition comprising a polymer (I) containing polytetrafluoroethylene and polymerized 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 CF; 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 greater. 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 more. 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 —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. Preferably, the anionic group is The composition of the present disclosure is preferably substantially free of fluorine-containing surfactants. The compositions of the present disclosure are preferably powders. The present disclosure also relates to an elongated body made from the above composition.

[0008] The present disclosure further relates to an elongated body comprising a polymer (I) containing polytetrafluoroethylene and polymerized 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 CF; 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 greater. 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 more. 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 —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. Preferably, the anionic group is The stretched body of the present disclosure is preferably substantially free of a fluorine-containing surfactant. [Effects of the Invention]

[0009] The composition of the present disclosure has excellent stretchability. DETAILED DESCRIPTION OF THE INVENTION

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

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

[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 sulfonamido group, an aromatic sulfonamido group, a heterocyclic sulfonamido group, an amino group, an aliphatic amino group, an These include an amino group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, and a diaromatic oxyphosphinyl group.

[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, 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 5- or 6-membered heterocycles having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

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

[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, 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, or an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, or an N-phenylcarbamoyl group.

[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 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 1 to 9 carbon atoms in total, a dialkylsulfamoyl group having 2 to 10 carbon atoms in total, an arylsulfamoyl group having 7 to 13 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 12 carbon atoms in total, more preferably a sulfamoyl group, an alkylsulfamoyl group having 1 to 7 carbon atoms in total, a dialkylsulfamoyl group having 3 to 6 carbon atoms in total, an arylsulfamoyl group having 6 to 11 carbon atoms in total, and a heterocyclic sulfamoyl group having 2 to 10 carbon atoms in total, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[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, and a methoxyethoxy group.

[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 fused with the aryl group, an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

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

[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 2 to 9 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 10 carbon atoms in total, an arylcarbamoylamino group having 7 to 13 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 12 carbon atoms in total, preferably a carbamoylamino group, an alkylcarbamoylamino group having 2 to 7 carbon atoms in total, a dialkylcarbamoylamino group having 3 to 6 carbon atoms in total, an arylcarbamoylamino group having 7 to 11 carbon atoms in total, and a heterocyclic carbamoylamino group having 3 to 10 carbon atoms in total, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0032] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (e.g., 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 includes polytetrafluoroethylene (hereinafter also referred to as "PTFE").

[0035] The PTFE generally has extensibility, fibrillation properties, and non-melt-fabricability. The non-melt-fabricability means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point in accordance with ASTM D 1238 and D 2116, i.e., the PTFE does not flow easily even in the melting temperature range.

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

[0037] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include fluoromonomers and non-fluoromonomers. The modifying monomer used may be one type or multiple types.

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

[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 examples thereof include perfluorovinyl ethers represented by the general formula (A): CF2=CF-ORf (A) (wherein Rf represents a perfluoroorganic group). In the present disclosure, the "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

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

[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 ...

[0045] [ka]

[0046] (wherein m represents 0 or an integer of 1 to 4), and 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-isomer), and CHF=CHCF3 (Z-isomer).

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

[0053] A preferred example of the modifying monomer is a 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 with high dispersion stability.

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

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

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

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

[0061] From the viewpoint of reactivity with TFE, the modifying monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene. The modifying 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 units, perfluoro(alkyl vinyl ether) units, and (perfluoroalkyl)ethylene units is preferably in the range of 0.00001 to 1.0% by mass relative to all polymerized units of PTFE. The lower limit of the total amount is more preferably 0.0001% by mass, more preferably 0.0005% by mass, 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%, 0.50%, 0.40%, 0.30%, 0.20%, 0.15%, 0.10%, 0.08%, 0.05%, 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] The presence of the modifying monomer (A) makes it possible to obtain PTFE particles having a small primary particle size, and to obtain an aqueous dispersion having high dispersion stability. In addition, the aspect ratio of the primary particles can be reduced.

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

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

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

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

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

[0069] The modified monomer (A) has a functional group capable of reacting in radical polymerization, and therefore, when used in the polymerization, it is presumed that it reacts with TFE in the early stage of the polymerization reaction, forming highly stable particles having hydrophilic groups derived from the modified monomer (A). Therefore, it is considered that the number of particles increases when polymerization is carried out in the presence of the modified monomer (A).

[0070] The polymerization may be carried out in the presence of one type of the modifying monomer (A), or in the presence of two or more types 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 represents H, a metal atom, or NR 7y 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 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. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7y The organic group in R is preferably an alkyl group. 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), with Na, K, or Li being preferred. By using the modifying monomer (A), an aqueous dispersion having a smaller average primary particle size and better stability can be obtained, and the aspect ratio of the primary particles can also be made smaller.

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

[0074] Above R a is preferably 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 acyclic. 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 in which no fluorine atoms are bonded to a carbon atom, a hydrocarbon group in which some of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, a hydrocarbon group in which all of the hydrogen atoms bonded to a carbon atom are substituted with fluorine atoms, -(C=O)-, -(C=O)-O-, or a hydrocarbon group containing -(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 -, -(C=O)-O-C6H4-, and combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[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-(CF2)-, -(C=O)-O-C6H4-, etc. a Specifically, -CF2-O-, -CF2-O-CF2-, -CF2-O-CF2CF2-, -CF2-O-CF(CF3)-, -CF2-O-CF(CF3)CF2-, -CF2 -O-CF(CF3)CF2-O-, -(C=O)-, -(C=O)-O-, -(C=O)-(CH2)-, -(C=O)-O-(CH2)-, -(C=O)-O[(CH2)2-O] n -, -(C=O)-O[(CH2)2-O] n -(CH2)-, -(C=O)-(CH2)2-O-(CH2)-, or -(C=O)-O-C6H4- is preferred. In the above formula, n is an integer of 1 to 10.

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

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

[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. Divalent groups represented by the following formula are also preferred.

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

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

[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 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 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 general formula (4), Y 3 One of the preferred embodiments is -OSO3M. 3 is -OSO3M, examples of the compound represented by general formula (4) include CF2=CF(OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(O(CF2)4CH2OSO3M), CF2=CF(OCF2CF(CF3)CH2OSO3M), CF2=CF(OCF2CF(CF3)OCF2CF2CH2OSO3M), CH2=CH((CF2)4CH2OSO3M), CF2=CF(OCF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), and the like. In the above formulas, M is the same as above.

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

[0087] In general formula (4), Y 3 -COOM is also a preferred form. 3 is -COOM, the compounds represented by general formula (4) include CF2=CF(OCF2CF2COOM), CF2=CF(OCF2CF2CF2COOM), CF2=CF(O(CF2)5COOM), CF2=CF(OCF2CF(CF3)COOM), CF2=CF(OCF2CF(CF3)O(CF2) n COOM) (n is greater than 1), CH2=CH(CF2CF2COOM), CH2=CH((CF2)4COOM), CH2=CH(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 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 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), where M is the same as above.

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

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

[0092] In the general formula (5), Y is —H, —F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

[0093] In general formula (5), Z may be the same or different and is —H, —F, an alkyl group or a fluoroalkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

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

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

[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 also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[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 organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring. R 7y The organic group in is preferably an alkyl group. R 7y As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K or Li. 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 preferred, and -COOM is more preferred.

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

[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] Among them,

[0104] [ka]

[0105] It is preferable that:

[0106] The monomer represented by general formula (5a) includes, 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 (5b) represented by the general formula (5b). CX 2 2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y 3 (5b) (In the formula, each 2 are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, and Y 3 is the same as the definition above.)

[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 the heat resistance of the resulting composition and the stretched body obtained from the composition is improved. 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 Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0114] In the general formula (6), Y is —H, —F, an alkyl group or a fluorine-containing alkyl group. The alkyl group is an alkyl group that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Y is preferably -H, -F or -CF3, and more preferably -F.

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

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

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

[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 the heat resistance of the resulting molded article is improved.

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

[0121] In the formula (6c), n3 is preferably an integer of 5 or less in terms 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 in that it provides good 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 adequate 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), n5 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM in that it provides adequate water solubility and stability of the aqueous dispersion, and the above M is preferably H or NH4.

[0125] Examples of the monomer represented by general formula (6e) include 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) (wherein 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) (wherein n2 represents an integer of 1 to 5, and Y 3 is as defined above. At least one selected from the group consisting of monomers represented by Above Y 3 is preferably -SO3M or -COOM, and M is H, a metal atom, NR 7y4. It is preferably an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 7y represents H or an organic group. 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 can provide 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 the heat resistance of the resulting composition and the stretched body obtained from the composition is improved.

[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 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. 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 the heat resistance of the resulting composition and the stretched body obtained from the composition is improved.

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

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

[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. The content of each monomer unit constituting PTFE can also be calculated from the amount of modified monomer added used in polymerization.

[0134] The PTFE preferably has a primary particle aspect ratio of less than 2.00, more preferably 1.90 or less, even more preferably 1.80 or less, even more preferably 1.70 or less, particularly 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, particularly 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 randomly selected particles, and averaging the ratio of their major axis to their minor axis. When measuring the aspect ratio using a powder, the PTFE powder is irradiated with an electron beam, then added to an aqueous fluorosurfactant solution, and re-dispersed using ultrasonic waves to obtain an aqueous PTFE dispersion. The aspect ratio is determined from this aqueous PTFE dispersion using the same method as for measuring the aqueous dispersion.

[0135] Specifically, when measuring the aspect ratio of PTFE using an aqueous PTFE dispersion, an aqueous PTFE dispersion adjusted to a polymer solids concentration of approximately 1.0% by mass is prepared, observed with a scanning electron microscope (SEM), and images of 400 or more randomly selected particles are processed. The aspect ratio can be determined from the average ratio of their major axis to minor axis. When measuring the aspect ratio of PTFE using PTFE powder, the PTFE powder is irradiated with an electron beam, added to an aqueous solution of a fluorine-containing surfactant, and redispersed in the aqueous solution under ultrasonic irradiation to prepare an aqueous PTFE dispersion. The aspect ratio can be determined using the aqueous dispersion prepared in this manner by the method described above.

[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 approximately 10 mg of PTFE powder that has not been heated to temperatures above 300°C and placing it in a special aluminum pan. The endothermic peak temperature can be determined as the temperature corresponding to the maximum value on a differential thermal (DTA) curve obtained by heating the aluminum pan in an air atmosphere over a temperature range from 25°C to 600°C at a rate of 10°C / min.

[0138] The PTFE is preferably a PTFE 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 a simple process or ease of controlling the 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. An example of unsintered PTFE is as-polymerized PTFE. The unsintered PTFE is 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 is PTFE that has no history of being heated to a temperature equal to or higher than the primary endothermic peak temperature, and is PTFE 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 first endothermic peak temperature means the maximum peak temperature of the endothermic curve that appears on the crystalline melting curve when unsintered PTFE is measured with a differential scanning calorimeter. The second endothermic peak temperature means the maximum peak temperature of the endothermic curve that appears on the crystalline melting curve when PTFE heated to a temperature equal to or higher than the first endothermic peak temperature (for example, 360°C) is measured with 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 rate of 10°C / min.

[0139] The PTFE may have a core-shell structure, which is a conventionally known structure and is the structure of primary particles in an aqueous dispersion that can be produced by the method described in U.S. Pat. No. 6,841,594 or the like. Examples of PTFE having a core-shell structure include a core-shell structure comprising a core portion of a TFE homopolymer and a shell portion of a modified PTFE, a core-shell structure comprising a core portion of a modified PTFE and a shell portion of a TFE homopolymer, and a core-shell structure comprising a core portion of modified PTFE and a shell portion of modified PTFE having a different monomer composition from the modified PTFE that constitutes 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 shell portion means a portion that constitutes a predetermined thickness from the surface of the PTFE primary particle to the interior of the particle, and the core portion means a portion that constitutes the interior of the shell portion.

[0140] In the present disclosure, the core-shell structure includes all of the following: (1) a structure in which the core and shell portions have different monomer compositions; (2) a structure in which the core and shell portions have the same monomer composition but different number-average molecular weights; and (3) a structure in which the core and shell portions have different monomer compositions but 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 preferably 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. A relatively small average primary particle diameter of the primary particles allows the polymerization of TFE in an aqueous medium to proceed smoothly, making it easy to produce PTFE. A relatively small average primary particle diameter of the primary particles can be obtained, for example, by adding a modifying monomer to the polymerization system at the initial stage of TFE polymerization. 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 PTFE primary particles can be measured by dynamic light scattering. First, an aqueous PTFE dispersion is prepared with a polymer solids concentration adjusted to approximately 1.0% by mass. Measurements can then be performed using dynamic light scattering at a measurement temperature of 25°C, a refractive index of the solvent (water) of 1.3328, a viscosity of the solvent (water) of 0.8878 mPa·s, and 70 cumulative measurements. For dynamic light scattering, an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used, for example.

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

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

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

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

[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 CF; 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 greater. X 2 is preferably F, Cl, H or CF3. 1 and Z 2 is preferably F or CF3.

[0151] In the present disclosure, the anionic group includes functional groups that provide anionic groups such as sulfate groups, carboxylate groups, acid groups such as -COOH, acid salt groups such as -COONH4, etc. The anionic group includes sulfate groups, carboxylate groups, phosphate groups, phosphonate groups, sulfonate groups, or -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 polymerized units (I) based on one type of monomer represented by general formula (I), or may contain polymerized 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, a "linking group" is an (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 ester, amide, sulfonamide, carbonyl, carbonate, urethane, urea, and carbamate. The linking group may not contain carbon atoms but may be a catenary heteroatom such as oxygen, sulfur, or nitrogen.

[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 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 atoms, a hydrocarbon group in which some of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms, or a hydrocarbon group in which all of the hydrogen atoms bonded to the carbon atoms 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 the combinations thereof. In the formula, a, b, c, and d are independently at least 1. a, b, c, and d may independently be 2 or more, 3 or more, 4 or more, 10 or more, or 20 or more. The upper limit of a, b, c, and d is, for example, 100.

[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 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 formula:

[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 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, they are 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 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, they are 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 preferable.

[0167] The polymer (I) is also preferably highly fluorinated. For example, it 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 ) except for the C—F bond, it is also preferable that the compound has no C—H bond. 1 , X 2 , and X3 are all F, and R is preferably a perfluoroalkylene group having one or more carbon atoms, and the perfluoroalkylene group may be either linear or branched, may be cyclic or acyclic, and may contain at least one catenary heteroatom. The number of carbon atoms in the perfluoroalkylene group may be 2 to 20, or may be 4 to 18.

[0169] The polymer (I) may be partially fluorinated. That is, the polymer (I) may contain 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, -SONR'CH2COOM, -CH2OP(O)(OM)2, [-CHO]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CHO]2P(O)(OM), -CH2CH2OSO3M, -P(O)(OM)2, -SONR'CH2CH2OP(O)(OM)2, [-SONR'CH2CHO]2P(O)(OM), -CH2OSO3M, -SONR'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, 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.

[0172] Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferred.

[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 polymerized units (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 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 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(OCF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), CF2=CF(OCF2CF2CF2CF2SON(CH3)CH2CH2OSO3M), CH2=CH(CF2CF2CH2OSO3M), and the like. In the above formula, M is the same as above.

[0179] In 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 formulas, M is the same as above.

[0181] In general formula (I), A 0 A is preferably a carboxylate group. 0Examples of the compound include COOM or 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 general formula (I), A 0 In one preferred embodiment, A is a phosphate group. 0 Examples of the alkyl group include -CH2OP(O)(OM)2, [-CH2O]2P(O)(OM), -CH2CH2OP(O)(OM)2, [-CH2CH2O]2P(O)(OM), [-SON2NR'CH2CH2O]2P(O)(OM) or -SON2NR'CH2CH2OP(O)(OM)2, where R' is an alkyl group having 1 to 4 carbon atoms, and M is as defined 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). In the above formula, M is the same as above.

[0184] In 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 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's are the same or different and are -H or -F; Y's are -H, -F, an alkyl group or a fluorine-containing alkyl group; Z's are the same or different and are -H, -F, an alkyl group or a fluoroalkyl group; Rf's are fluorine-containing alkylene groups having 1 to 40 carbon atoms or fluorine-containing alkylene groups having 2 to 100 carbon atoms and an ether bond; A's are -COOM, -SO3M, -OSO3M or C(CF3)2OM (M's are -H, a metal atom, -NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group, provided that at least one of X, Y, and Z contains a fluorine atom. By including the polymer (1), the composition of the present disclosure containing polytetrafluoroethylene can be produced stably and efficiently, and a composition containing high molecular weight polytetrafluoroethylene can be obtained in high yield.

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

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

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

[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 that does not contain a fluorine atom, and may have a carbon number of at least 1. The alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The fluorine-containing alkyl group is an alkyl group containing at least one fluorine atom, and may have a carbon number of at least 1. The fluorine-containing alkyl group preferably has 6 or less carbon atoms, more preferably 4 or less carbon atoms, and even more preferably 3 or less carbon atoms. The above Z is preferably -H, -F or -CF3, and more preferably -F.

[0190] In the 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 general formula (1), 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 also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5). Specific examples of the fluorine-containing alkylene group having an ether bond include -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) n Examples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0193] In the above general formula (1), A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (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. R 7 As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: 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] Examples of the monomer represented by general formula (1) include 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), 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. A is preferably -COOM in that appropriate water solubility and surface activity can be obtained, and 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 may be a copolymer with other monomers.

[0195] The 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) (wherein 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 the same as defined above). More specifically,

[0199] [ka]

[0200] Among them,

[0201] [ka]

[0202] It is preferable that:

[0203] As the monomer represented by the above general formula (1A), it is preferable that A in formula (1A) is -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's are the same or different and represent -H or F; Y represents -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf represents 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 Xs may be -F, or at least one X may be -H. For example, one X may be -F and the other may be -H, or both Xs may be -H.

[0209] In 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 fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. The fluorine-containing alkyl group is an alkyl group that contains at least one fluorine atom, and may have one or more carbon atoms. The fluorine-containing alkyl group preferably has six or fewer carbon atoms, more preferably four or fewer carbon atoms, and even more preferably three or fewer carbon atoms. Y is preferably -H, -F, or -CF3, and more preferably -F.

[0210] In 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 contain a structure in which an oxygen atom is at the terminal and that contains an ether bond between carbon atoms.

[0212] The number of carbon atoms in 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 formulas (2a), (2b), (2c), (2d) and (2e). CF2=CF-O-(CF2) n1 -A (2a) (wherein 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) (wherein 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) (wherein 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 definition above.) CF2=CF-O-(CF2CF2CFX 1 O) n5 -CF2CF2CF2-A (2e) (wherein n5 represents an integer of 0 to 10, and A and X 1 is the same as the definition above.)

[0214] In the general formula (2a), 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 general formula (2c), n3 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.

[0218] In 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] Examples of the monomer represented by general formula (2e) include CF2=CFOCF2CF2CF2COOM (wherein M represents H, NH4 or an alkali metal).

[0222] The polymer (I) is also preferably a polymer (3) containing polymerized units (3) based on a monomer represented by general formula (3). CX2=CY(-Rf-A) (3) (In the formula, X's are the same or different and represent -H or -F; Y represents -H, -F, an alkyl group or a fluorine-containing alkyl group; Rf represents 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; 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 contain 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 general formula (3) is represented by 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 preferred.

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

[0227] In general formula (3a), n1 is preferably an integer of 5 or less, 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 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 when 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 are the same as above, Q F1 and Q F2 are the same or different and are 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] The monomers represented by general formula (4a) and general formula (4b) include: [ka] etc.

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

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

[0235] The other monomer is preferably a fluorine-containing ethylenic monomer 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-isomer), CHF=CHCF3 (Z-isomer), etc. Among these, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and vinylidene fluoride (CH2=CF2) is preferred, with tetrafluoroethylene being more preferred, due to its favorable copolymerizability. Therefore, the polymerized units based on the other monomer are preferably polymerized units based on tetrafluoroethylene. The polymerized units based on the other monomers may be the same or different in each occurrence, and the polymer (I) may contain polymerized units based on two or more different types of 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 2 to 100 carbon atoms and having an ether bond).

[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] Examples of the other monomers include those of 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).

[0245] Examples of the other monomers 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 (wherein the alkyl group 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).

[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] Examples include:

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

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

[0254] [ka]

[0255] Examples of such monomers include:

[0256] The polymer (I) usually has a terminal group. The terminal group is a terminal group generated during polymerization, and typical terminal groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl 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 to form the polymer (I), or are generated during the chain transfer reaction.

[0257] The polymer (I) preferably has a content of polymerized units (I) of 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 content of polymerized units. The polymer (I) preferably contains 30 mol% or more of polymerized units (I) relative to 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%. Most preferably, the polymer (I) consists solely of polymerized units (I).

[0258] In the polymer (I), the content of polymerized 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 particularly preferably 80 mol% or less, based on the total polymerized units. In addition, in the polymer (I), the content of 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 than 1.0 × 10 4 More than 3.0 × 10 is particularly preferable. 4 The number average molecular weight of the polymer (I) is most preferably 3.1 × 10 4 It is also preferable that it is more than this. The number average molecular weight of the polymer (I) is also 75.0 × 10 4 The following is preferable: 50.0 x 10 4 Less than 40.0 x 10 is more preferable. 4 More preferably, 30.0 x 10 4 More preferably, 20.0 x 10 4 The following is particularly preferred: If the number average molecular weight is too low, the aqueous solution may have insufficient stability, and if the number average molecular weight is too high, the polymer (I) may partially settle, precipitate, or become cloudy upon storage or the addition of other additives. 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. When GPC measurement is not possible, the number average molecular weight of the polymer (I) can be determined from the correlation between the number average molecular weight calculated from the number of terminal groups obtained by NMR, FT-IR, etc. and the melt flow rate. The melt flow rate can be measured in accordance with JIS K 7210.

[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 than 1.0×10 is particularly preferable. 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 x 10 4 It is also preferable that it is more than this. The weight average molecular weight of the polymer (I) is also 150.0 × 10 4 The following is preferable: 100.0 x 10 4 Less than 60.0 x 10 is preferable. 4 More preferably, 50.0 x 10 4 The following is even more preferable: 40.0 x 10 4 The following are particularly preferred:

[0261] Preferably, polymer (I) 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., -SOF) 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 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 preferably carry ionic groups.

[0265] Preferably, polymer (I) comprises ionic groups having a pKa of less than 10, more preferably less than 7. The ionic groups of polymer (I) are 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 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 a 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 polymer (I) can be produced by a conventional method except for using the above-mentioned monomers.

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

[0270] The content 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 content of the dimer and trimer in the polymer (I) described below.

[0271] The composition of the present disclosure has a standard specific gravity (SSG) of 2.200 or less. A standard specific gravity of 2.200 or less allows the composition to be stretchable, and a stretched product with 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 standard specific gravity is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D4895 89.

[0272] In the composition of the present disclosure, the content of polymer (I) is preferably 0.0001% by mass or more and 20% by mass or less relative to polytetrafluoroethylene. In the composition of the present disclosure, the lower limit of the content of polymer (I) relative to polytetrafluoroethylene is more preferably 0.001% by mass, even more preferably 0.01% by mass, and particularly preferably 0.1% by mass. 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 can be determined by solid-state NMR measurement. The content of the polymer (I) can be measured by any of the methods 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 content of each polymer are described in JP-A-2012 / 082707, JP-A-2012 / 082703, JP-A-2012 / 082454, JP-A-2012 / 082451, JP-A-2006 / 135825, JP-A-2004 / 067588, JP-A-2009 / 068528, JP-A-2004-075978, JP-A-2001-226436, JP-A-1992 / 017635, JP-A-2014 / 069165, JP-A-11-181009, etc. As a method for measuring the content of the polymer (I), the method for measuring each polymer 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, and preferably 5.0 MPa or more, preferably 8.0 MPa or more, and more preferably 10.0 MPa or more. The 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®, manufactured by Exxon Chemical) was added to 100 g of powder of the composition of the present disclosure and mixed for 3 minutes in a glass bottle at room temperature. 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 through an orifice (diameter 2.5 mm, land length 11 mm, entrance angle 30°) at a reduction ratio of 100:1 at room temperature to obtain a uniform bead (extrudate). The extrusion speed, i.e., ram speed, was 20 in / min (51 cm / min). The extrusion pressure was determined by measuring the load when the extrusion load reached equilibrium during paste extrusion and dividing the value by the cross-sectional area of the cylinder used for paste extrusion.

[0274] Hereinafter, the breaking strengths A to D are values determined by the following method in accordance with the method described in JP-A-2002-201217. The breaking strength A of the composition of the present disclosure is preferably 10.0 N or more. The breaking strength A is more preferably 13.0 N or more, even more preferably 16.0 N or more, and even more preferably 19.0 N or more. Furthermore, it is preferably 20.0 N or more, more preferably 21.0 N or more, even more preferably 22.0 N or more, even more preferably 25.0 N or more, especially preferably 28.0 N or more, and particularly preferably 30.0 N or more. The higher the breaking strength A, the better, but the upper limit of breaking strength A may be, for example, 100 N or less, or 80.0 N or less, or 50.0 N. 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 breaking strength A. The composition of the present disclosure is heat-treated at 210°C. 21.7g of lubricant is added to 100g 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 (2.5mm diameter, 11mm land length, 30° entry angle) at room temperature with a reduction ratio of 100:1 to obtain a uniform bead (extrudate). The extrusion speed, i.e., ram speed, is 20 inches / minute (51cm / 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 an appropriate length, clamped at each end with a clamp distance of 1.5 inches (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 reached, and a stretching 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 manufacturing 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 between movable jaws with 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 break 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 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 stretched bead obtained by changing the clamp spacing to 2.0 inches (51 mm) and the stretch rate to 100% / second 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, and 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, and 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% / second to use a stretched 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 measured by the following method. Both ends of the stretched bead obtained in the above stretching test A are connected to fixtures to create 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 required from the time of insertion into the oven until the bead sample breaks is taken as the stress relaxation time.

[0284] The composition of the present disclosure is preferably stretchable. In the present disclosure, "stretchable" is determined according to the following criteria. 21.7 g of lubricant (trade name: Isopar H®, Exxon Chemical) was added to 100 g of powder of the composition of the present disclosure and mixed for 3 minutes in a glass bottle at room temperature. The 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 through an orifice (2.5 mm diameter, 11 mm land length, 30° entry angle) at room temperature at a reduction ratio of 100:1 to obtain a uniform bead. The extrusion speed, i.e., ram speed, was 20 in / min (51 cm / min). The bead obtained by paste extrusion was heated at 230°C for 30 minutes to remove the lubricant from the bead. The bead (extrudate) was then cut to an appropriate length, clamped at each end with a clamp spacing of 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. 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, and is usually expressed relative to the original length. In this production method, 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 the advantage that it can be produced stably 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 present in an amount of 1 ppm by mass or less relative to the polytetrafluoroethylene, preferably 100 ppb by mass or less, more preferably 10 ppb by mass or less, still more preferably 1 ppb by mass or less, and particularly preferably below the detection limit of the fluorine-containing surfactant when measured by liquid chromatography-mass spectrometry (LC / MS). The amount of the fluorine-containing surfactant can be quantified by known methods. 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 molecular weight information is extracted from the extract's 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 concentrations, and LC / MS analysis is performed for each concentration, creating a calibration curve with the area. The obtained aqueous dispersion or powder is subjected to Soxhlet extraction with methanol, and the extract is then subjected to LC / MS analysis to quantitatively measure the amount. The extraction solvent can be acetone or methanol. The extraction method can also be Soxhlet extraction.

[0287] That is, the content of the fluorine-containing surfactant can be determined, 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 its match with the structural formula of the candidate fluorine-containing surfactant is confirmed. Then, aqueous solutions containing five or more levels of the identified fluorine-containing surfactant are prepared, and LC / MS / MS analysis is performed on the aqueous solutions containing each level of surfactant. The relationship between the content and the area corresponding to that content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area of the LC / MS / MS chromatogram of the fluorine-containing surfactant in the extract can be converted into the content of the fluorine-containing surfactant.

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

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

[0290] Specific examples of the fluorine-containing surfactants include those described in U.S. Patent Application Publication Nos. 2007 / 0015864, 2007 / 0015865, 2007 / 0015866, 2007 / 0276103, 2007 / 0117914, 2007 / 142541, 2008 / 0015319, U.S. Patent Nos. 3,250,808, 3,271,341, and JP-A-2003-142541. -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] Examples of the fluorine-containing surfactant include anionic fluorine-containing surfactants, etc. The anionic fluorine-containing surfactant may be, for example, a surfactant containing fluorine atoms and having a total carbon number of 20 or less excluding the anionic group.

[0292] The fluorine-containing surfactant may be a surfactant containing fluorine, the molecular weight of which in the anionic moiety is 800 or less. The "anionic moiety" refers to the moiety excluding the cation of the fluorine-containing surfactant. 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 surfactants include those 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 is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H atoms have been substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H atoms may have been substituted with Cl. Y 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) and alkaline earth metals (Group 2), such as Na, K, or Li. 7 As for H or C 1-10 and may be an organic group of H or C 1-4 and may be an organic group of H or C 1-4 M may be an alkyl group of the formula: H, a metal atom, or NR 7 4, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 7 4, 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 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, and F, m1 is an integer from 3 to 15, and Y 0is as defined above, a compound represented by the general formula (N 2 ): Rf n1 -O-(CF(CF3)CF2O) m2 CFX n1 -Y 0 (N 2 ) (In the formula, Rf n1 is a perfluoroalkyl group having 1 to 5 carbon atoms, m2 is an integer of 0 to 3, and X n1 is F or CF3, and Y 0 is as defined above, a compound represented by the general formula (N 3 ): Rf n2 (CH2) m3 -(Rf n3 ) q -Y 0 (N 3 ) (In the formula, Rf n2 is a partially or fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, m3 is an integer of 1 to 3, and Rf n3 is a linear or branched perfluoroalkylene group having 1 to 3 carbon atoms, q is 0 or 1, and Y 0 is as defined above, a compound represented by the general formula (N 4 ): Rf n4 -O-(CY n1 Y n2 ) p CF2-Y 0 (N 4 ) (In the formula, Rf n4 is a linear or branched partially or fully fluorinated alkyl group having 1 to 12 carbon atoms, which may contain an ether bond; 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, a compound represented by the general formula (N 5 ): [ka] (In the formula, X n2 , X n3 and X n4 Rf may be the same or different and are H, F, or a linear or branched partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond. n5 is a linear or branched partially or fully fluorinated alkylene group having 1 to 3 carbon atoms, which may contain an ether bond; L is a linking group; Y 0 is as defined above, where X n2 , X n3 , X n4 and Rf n5 The total number of carbon atoms is 18 or less.

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

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

[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 fully fluorinated alkyl group having 1 to 13 carbon atoms which may contain an ether bond, n8 is an integer of 1 to 3, and M is as defined above.

[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 fully fluorinated alkyl group having 1 to 6 carbon atoms, which may contain an ether bond; Rf 8 is a linear or branched, partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and M is as defined above.

[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 fully 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, and 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 the formula: CF2ClO(CF2CF(CF3)O) n9 (CF2O) n10 CF2COONH4 (a mixture having an average molecular weight of 750, wherein n9 and n10 are defined above).

[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 preferable for molding, and suitable applications include tubes for hydraulic systems and fuel systems of aircraft and automobiles, flexible hoses for chemical solutions, steam, etc., and wire coating applications. It can also be used as a binder for batteries and for dust prevention purposes.

[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 the polymerization of tetrafluoroethylene and the above-mentioned modifying monomer.

[0313] The above production method may use at least one type of polymer (I), or two or more types of polymer (I) may be used simultaneously. Alternatively, other surface-active compounds 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 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, even more preferably 50°C or higher, more preferably 120°C or lower, even more 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 polymerization step, the amount of polymer (I) at the start of polymerization is preferably 1 ppm by mass or more relative to the aqueous medium. The amount of polymer (I) at the start of polymerization is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, and even more preferably 200 ppm by mass or more. There are no particular limitations on the upper limit, but for example, it is preferably 100,000 ppm by mass, and more preferably 50,000 ppm by mass. 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 polymer (I) is preferably added in a total amount of 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, while if the amount exceeds 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 determined appropriately 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 lower.

[0320] The production method may include a step of adding a polymerization terminator to the aqueous medium (hereinafter also referred to as a "polymerization terminator addition step"). The polymerization terminator addition step is carried out during the polymerization step. Adding the polymerization terminator during the polymerization step can increase the breaking strength of the resulting composition and stretched body.

[0321] The polymerization terminator is a compound that does not have the ability to restart after addition or chain transfer to free radicals in the polymerization system. Specifically, a compound that easily undergoes a chain transfer reaction with a primary radical or a propagating radical to generate a stable radical that does not subsequently react with the monomer, or a compound that easily undergoes an addition reaction with a primary radical or a propagating radical to generate a stable radical, is used. The activity of what is generally called 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. The polymerization terminator in the present disclosure is preferably at least one selected from the group consisting of aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl). Examples of aromatic hydroxy compounds include unsubstituted phenols, polyhydric phenols, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, etc. Examples of unsubstituted phenols include o-, m-, or p-nitrophenols, o-, m-, or p-aminophenols, p-nitrosophenols, etc. Examples of polyhydric phenols 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. Furthermore, it is 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, more preferably an amount corresponding to 3 to 10 ppm by mass, of the mass of the aqueous medium used.

[0323] The above production method preferably includes a step of adding a decomposing agent to the aqueous medium instead of the polymerization terminator. The addition of the decomposing agent allows the radical concentration during polymerization to be adjusted. Examples of the decomposing agent include sulfites, bisulfites, bromates, diimines, oxalic acid, copper salts, and iron salts. Examples of sulfites include sodium sulfite and ammonium sulfite. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate. The amount of the decomposer added is in the 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 (a redox initiator described below). Furthermore, it is 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, more preferably an amount corresponding to 3 to 10 ppm by mass, of the mass of the aqueous medium used.

[0324] In the 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, without interruption or in portions, rather than all at once. By continuously adding the polymer (I), a composition with even more excellent dispersion stability can be obtained.

[0325] When polymer (I) is added continuously, the amount of 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, and even more preferably 5% by mass, even more preferably 2% by mass.

[0326] In the polymerization process, 0.6 × 10 13 It is preferable to generate particles at a concentration of 0.7 × 10 or more per ml. By generating a large number of particles in the polymerization step, primary particles with 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 for example, 7.0 × 10 14 pieces / mL.

[0327] The particles generated by the polymerization of TFE are concentrated in the first half of the polymerization and are less likely to be generated 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 final aqueous dispersion.

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

[0329] The total amount of modifying 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, still more preferably 0.005% by mass or more, and particularly preferably 0.009% by mass or more, based on the PTFE to be obtained. The total amount of modifying 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 to be obtained.

[0330] In the above polymerization, it is preferable to add a modified monomer copolymerizable with TFE before the polymerization reaction is initiated or before the PTFE concentration 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. Adding the modified monomer at the beginning of the polymerization allows for the generation of more particles during polymerization, resulting in primary particles with a smaller average primary particle size and aspect ratio. The modified monomer may be added before the start of polymerization, simultaneously with the start of polymerization, or after the start of polymerization, during the period in which PTFE particle nuclei are formed. The modified monomer should be added at least before the polymerization reaction is initiated or before the PTFE concentration in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses. Further modified monomer may be added after the PTFE concentration exceeds 10.0% by mass. For example, the modified monomer may be added before the PTFE concentration reaches 10.0% by mass, and then continued even after the PTFE 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 modified monomer may be added by forcing the modified monomer into the reactor with TFE.

[0331] It can be said that polymerization has begun when the gaseous fluoromonomer in the reactor becomes PTFE and a pressure drop occurs in the reactor. U.S. Patent No. 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 involves the polymerization of the established particles. It should be noted that polymerization usually begins when both the monomer to be polymerized and the polymerization initiator are charged into the reactor.

[0332] Before the polymerization reaction is initiated, or before the PTFE concentration in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, preferably before it reaches 5.0% by mass, the amount of the modifying 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 to be obtained. Furthermore, before the polymerization reaction is initiated, or before the PTFE concentration in the aqueous dispersion reaches 10.0% by mass as the polymerization reaction progresses, preferably before it reaches 5.0% by mass, the amount of the modifying 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 to be obtained.

[0333] Furthermore, as the polymer (I), a polymer (I) in which the content of dimers and trimers of the monomer represented by general formula (I) (hereinafter sometimes referred to as monomer (I)) is 1.0 mass% or less relative to the polymer (I) may be used.

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

[0335] The polymer (I) used in the above-mentioned production method is substantially free of 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 dimers and trimers 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 dimers and trimers to the total area of each peak in the chromatogram obtained by GPC analysis.

[0337] Furthermore, when the content of dimers and trimers in polymer (I) is less than 0.5% by mass relative to polymer (I), it can be identified by measurement using liquid chromatography-mass spectrometry (LC / MS / MS). Specifically, aqueous solutions containing five or more levels of monomer (I) are prepared, and LC / MS / MS analysis is performed for each content. The relationship between the content and the area (peak integral value) for each content is plotted to create a calibration curve for monomer (I). Furthermore, calibration curves for the dimer and trimer of monomer (I) are created from the calibration curve for monomer (I). 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 (integrated value of the peak) of the chromatogram of the dimer and trimer of the monomer (I) can be converted into the content of the dimer and trimer.

[0338] When polymerizing a fluoromonomer in an aqueous medium, a polymer dispersion substantially free of dimers and trimers of the monomer (I) can be produced by using a polymer (I) substantially free of dimers and trimers.

[0339] The polymer (I) is a polymer containing polymerized units (I) based on the monomer (I). The polymer (I) used in the present disclosure is a polymer obtained by substantially removing dimers (polymers containing two polymerized units (I)) and trimers (polymers 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 400 or less. That is, the polymer (I) preferably 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, and by producing a crude composition by such a method, a crude composition in which the polymer (I) is dispersed or dissolved in an aqueous medium can be obtained.

[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 typically contains a total of more than 1.0 mass% of dimers and trimers, based on 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, or 30.0 mass% or less, or 20.0 mass% or less, based on the mass of the polymer of monomer (I). The content of dimers and trimers in the crude composition can be determined by subjecting the crude composition to gel permeation chromatography (GPC) analysis and calculating the ratio (area percentage) of the total area of the dimer and trimer peaks to the total area of each peak in the chromatogram obtained by GPC analysis.

[0346] Next, the dimers and trimers 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 dimers and trimers 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 previously known that dimers and trimers of monomer (I) are produced 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 produced is not entirely clear. However, it is speculated that dimerization and trimerization of monomer (I) occur at a non-negligible frequency, particularly in polymerization systems in which monomer (I) accounts for the majority of the monomers present in the polymerization system. The present disclosure has for the first time revealed the presence of dimers and trimers of monomer (I) in polymer (I), and has for the first time discovered that dimers and trimers of monomer (I) in polymer (I) can be highly efficiently removed 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 also removed from the crude composition. Even if the unreacted monomer (I) is incorporated into PTFE during polymerization, it does not necessarily adversely affect the functionality of PTFE, so it is not necessary to remove the unreacted monomer (I). However, by removing the unreacted monomer (I) simultaneously with the dimer and trimer, the amount of monomer to be used for polymerization can be calculated without considering the presence of the unreacted monomer (I), which has the advantage of facilitating the production of PTFE with the desired monomer composition. Even when the monomer (I) remains in the polymer (I) or when the monomer (I) is newly added as a comonomer, the dimerization and trimerization of the monomer (I) hardly progresses during the polymerization reaction in a polymerization system in which fluoromonomers (excluding the monomer (I)) account for the majority of the monomers present in the polymerization system, and therefore the dimer and trimer of the monomer (I) hardly remain in the resulting PTFE.

[0349] The crude composition obtained by polymerization of the monomer (I) may be a composition obtained by polymerization as is, or may be a composition obtained by diluting or concentrating the composition obtained by polymerization, or may be a composition that has been subjected to a dispersion stabilization treatment, etc. In order to 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 adding water to the crude composition obtained by polymerization of monomer (I), or by concentrating the crude composition obtained by polymerization of monomer (I).

[0351] The pH of the crude composition is preferably 0 to 11, more preferably 0.5 to 8.0, and even more 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 thereof include phosphates, sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0352] The viscosity of the crude composition is preferably 25 mPa s or less, since this allows for smooth ultrafiltration, microfiltration, or dialysis membrane treatment. 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, or by adjusting the temperature of the crude composition.

[0353] The ultrafiltration or microfiltration may be performed by either a cross-flow system or a dead-end system, but is preferably performed by a cross-flow system from the viewpoint of reducing clogging of the membrane.

[0354] The ultrafiltration can be carried out using an ultrafiltration membrane, for example, an ultrafiltration device having an ultrafiltration membrane, and methods such as centrifugal ultrafiltration, batch ultrafiltration, and circulating ultrafiltration can be used.

[0355] The molecular weight cutoff of the ultrafiltration membrane is usually 0.1 × 10 4 ~30×10 4 The above ultrafiltration membrane can suppress clogging of the membrane and efficiently reduce dimers and trimers, so the molecular weight cutoff is about 1.5 × 10 4 The molecular weight cutoff is preferably 2.0 × 10 Da or more. 4 Da or more is more preferable, 3.0 × 10 4 Da or more is particularly preferable, and 5.0 × 10 4 The molecular weight cutoff is most preferably 8.0 × 10 Da or more. 4 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 types, including, but not limited to, hollow fiber, flat membrane, spiral, tubular, etc. From the viewpoint of preventing clogging, the hollow fiber type is preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and preferably 0.05 to 2 m.

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

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

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

[0363] The shape of the microfiltration membrane is not limited to any particular shape, and examples thereof include hollow fiber, flat membrane, spiral, tubular, etc. From the viewpoint of preventing clogging, hollow fiber membranes are preferred. The inner diameter of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.1 to 2 mm, and preferably 0.8 to 1.4 mm. The length of the hollow fiber ultrafiltration membrane is not limited, but may be, for example, 0.05 to 3 m, and preferably 0.05 to 2 m.

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

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

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

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

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

[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 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 15°C or higher, even more preferably 20°C or higher, and particularly preferably 30°C or higher. By setting the temperature within the above range, dimers and trimers can be reduced more efficiently. The temperature is preferably 90°C or lower, more preferably 80°C or lower, even more preferably 70°C or lower, and particularly preferably 60°C or lower.

[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 may be added to the crude composition intermittently or continuously.

[0373] The endpoint of the ultrafiltration, microfiltration, or dialysis membrane treatment may be appropriately determined and is not limited. In addition, in the ultrafiltration, microfiltration, or dialysis membrane treatment, backwashing with water may be performed approximately 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 a crude composition containing a polymer of the monomer (I), an aqueous solution containing the polymer (I) substantially free of dimer and trimer is usually obtained. The polymer (I) used in the above production method may be the polymer (I) contained in the obtained aqueous solution, or may be 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 methods such as coagulation, washing, and drying of the polymer (I) in the aqueous solution.

[0375] An aqueous solution containing the polymer (I) can be used as the polymer (I). 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 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 fluoropolyether is preferably a fluoropolyether acid or its salt, and the fluoropolyether acid is preferably a carboxylic acid, a sulfonic acid, a sulfonamide, or a phosphonic acid, and more preferably a carboxylic acid. Among the fluoropolyether acids or their salts, the salt of a fluoropolyether acid is preferred, the ammonium salt of a fluoropolyether acid is more preferred, and the ammonium salt of a fluoropolyether carboxylic acid is even more preferred.

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

[0382] The fluoropolyether acid or salt thereof is selected from the group consisting of fluoropolyether acids and fluoropolyether salts having 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 (wherein 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 carboxylic acid groups or salts thereof at one or both ends. Similarly, such fluoropolyethers can have sulfonic or phosphonic acid groups or salts 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 hydrogen or chlorine atoms.

[0384] Fluoropolyethers having acid groups at one or both ends have 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 2 or 3 carbon atoms. Even more preferably, at least 50% of the fluorocarbon groups separating the ether oxygens have 2 or 3 carbon atoms. Also, preferably, the fluoropolyether has a total of at least 15 carbon atoms, and 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 acid groups 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. Because the fluoropolyether acid or its salt may be difficult to disperse in an aqueous medium, the number average molecular weight is preferably less than 6000 g / mol. The fluoropolyether acid or its salt preferably has a number average molecular weight of 800 to 3500 g / mol, 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, relative to the aqueous medium. More preferred lower limits are, in order of preference, 10 ppm, 20 ppm by mass, 30 ppm by mass, and 50 ppm by mass, and more preferred upper limits are, in order of preference, 1000 ppm by mass, 500 ppm by mass, and 100 ppm by mass.

[0387] The nonionic surfactants described above typically contain no charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains a water-soluble functional group, such as an ethylene ether chain derived from polymerization with ethylene oxide.

[0388] Examples of nonionic surfactants Polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl 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] Specific examples of glycerol esters include glycerol monomyristate, glycerol monostearate, and glycerol monooleate.

[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.

[0398] Examples of the nonionic surfactant as the nucleating agent include the nonionic surfactants mentioned above, and among them, fluorine-free nonionic surfactants are preferred. Examples include ether-type nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and polyoxyethylene alkylene alkyl ether; polyoxyethylene derivatives such as ethylene oxide / propylene oxide block copolymers; ester-type nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, and polyoxyethylene fatty acid ester; and amine-based nonionic surfactants such as polyoxyethylene alkylamine and alkylalkanolamide.

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

[0400] Examples of the nonionic surfactant include those 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, and 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 typically provided, or a broader or bimodal distribution obtained by blending. When the average number of repeating oxypropylene groups is greater than 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of 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 If the oxypropylene group has an average of 0.5 to 1.5, low foaming properties are favorable and it is preferable.

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

[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(CH 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 surfactants include Genapol X080 (product name, manufactured by Clariant), the Noigen TDS series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) such as Noigen TDS-80 (trade name), the Leocol TD series (manufactured by Lion Chemical Industries, Ltd.) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Chemical Industries, Ltd.), the T-Det A series (manufactured by Harcros Chemicals) such as T-Det A138 (trade name), and the Tergitol (registered trademark) 15S series (manufactured by The Dow Chemical Company).

[0405] Commercially available polyoxyethylene alkyl ethers include, for example, 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 The Dow Chemical Company).

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

[0408] The nonionic surfactant also includes 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, and A 6 is a polyoxyalkylene chain.

[0409] Examples of the polyoxyethylene alkylphenyl ether-based nonionic compounds 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, sucrose, maltose, lactose, raffinose, and isomaltose.

[0411] Typically, sugars suitable for use as polyol compounds include cyclic compounds containing a five-membered ring with four carbon atoms and one heteroatom (typically oxygen or sulfur, but preferably 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] (wherein x represents 0, 1, 2, 3, 4, or 5; R 1 and R 2 independently represent H or a long chain unit containing at least 6 carbon atoms, with the proviso that R 1 and R 2 and at least one of R is not H. 1 and R 2 Typical examples of the fatty alcohol include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. While the above formula represents a specific example of an alkyl polyglucoside showing glucose in the pyranose form, it is understood that other sugars or sugars that are the same sugar but in different enantiomeric or diastereomeric forms may also be used. Alkyl glucosides can be obtained, for example, by the acid-catalyzed reaction of glucose, starch, or n-butyl glucoside with aliphatic alcohols, typically resulting in a mixture of various alkyl glucosides (Alkylpolygylcoside, Rompp, Lexikon Chemie, Version 2.0, Stuttgart / New York, Georg Thieme Verlag, 1999). Examples of aliphatic alcohols include hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol (lauryl alcohol), tetradecanol, hexadecanol (cetyl alcohol), heptadecanol, octadecanol (stearyl alcohol), eicosanoic acid, and combinations thereof. Alkyl glucosides are also commercially available from Cognis GmbH, Dusseldorf, Germany, under the trade names GLUCOPON or DISPONIL.

[0413] Other nonionic surfactants include difunctional block copolymers supplied by BASF as the Pluronic® R series, and tridecyl alcohol alkoxylates supplied by BASF as 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 a 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 alkane preferably has 1 to 6 carbon atoms, more preferably 2 to 4, and even more preferably 3 to 4. The alcohol preferably has 1 to 5 carbon atoms, 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, a larger number of 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 the nucleating agents, a combination of a chain transfer agent and a nonionic surfactant is particularly preferred.

[0419] The amount of nucleating agent added is preferably 0.001 to 0.1 ppm by mass relative to the aqueous medium, since this allows for the generation of a larger number of particles during polymerization and also results in primary particles with a smaller average primary particle size and aspect ratio. The lower limit of the amount of 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 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 nucleating 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, because this allows a larger number of particles to be generated during polymerization and also allows primary particles having an even smaller average primary particle size and aspect ratio to be obtained.

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

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

[0423] The amount of nucleating agent added is preferably 0.001 to 0.1 ppm by mass relative to the amount of PTFE obtained, since this allows for the generation of more particles during polymerization and also results in primary particles with an even smaller average primary particle size and aspect ratio. The lower limit of the amount of 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 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. Polymerization methods using bromine compounds or iodine compounds include, for example, a method of polymerizing fluoromonomers in an aqueous medium in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the bromine compounds or iodine compounds used include, for example, compounds represented by the general formula: R a I x Br y (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R 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 bromine compounds or iodine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2 Examples include CFClBr, CFBrClCFClBr, BrCFCFCFBr, BrCFCFBrOCF, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl) substituted benzenes. These compounds may be used alone or in combination with each other.

[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 alkane preferably has 1 to 6 carbon atoms, more preferably 1 to 5, even more preferably 2 to 4, and particularly preferably 3 to 4. The alcohol preferably has 1 to 5 carbon atoms, 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 10,000 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 particularly preferably 0.5 ppm by mass or more relative to the aqueous medium. The amount of the chain transfer agent is more preferably 1,000 ppm by mass or less, even more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, and particularly preferably 10 ppm by mass or less.

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

[0430] In the above production method, additives for stabilizing each compound can be used in addition to the polymer (I), polymerization terminator, optional nucleating agent, etc. Examples of the additives include buffers, pH adjusters, stabilizing aids, and dispersion stabilizers.

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

[0432] The amount of the stabilizing aid used is preferably 0.1 to 12 mass % based on the mass of the aqueous medium used, more preferably 0.1 to 8 mass %. The stabilizing aid is preferably sufficiently hydrophobic so that it is completely separated from the PTFE dispersion after PTFE polymerization and does not become a contaminant. Furthermore, the stabilizing aid is preferably 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 bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium phosphate, potassium phosphate, sodium citrate, potassium citrate, ammonium citrate, sodium gluconate, potassium gluconate, and ammonium gluconate. The pH can be measured using a pH meter manufactured by Orion.

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

[0435] In the above production method, polymerization is carried out by charging an aqueous medium, the polymer (I), tetrafluoroethylene, a modified monomer added as needed, and other additives as needed into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to start the polymerization reaction. After the polymerization reaction has started, additional monomers, polymerization initiators, chain transfer agents, the polymer (I), etc. may be added depending on the purpose. The polymer (I) may also be added after the polymerization reaction has started.

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

[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 di-sec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, dialkyl peroxides such as di-t-butyl peroxide, and also 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 Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as di(ω-chlorohexafluorobutanoyl)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, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate; organic peroxides such as disuccinic acid peroxide or diglutaric acid peroxide; t-butyl permaleate; or t-butyl hydroperoxide. A reducing agent such as a sulfite or sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0440] For example, when polymerization is carried out at low temperatures below 30°C, it is preferable to use a redox initiator, which combines an oxidizing agent and a reducing agent, as the polymerization initiator. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, cerium ammonium nitrate, and bromates. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts 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, and bromate / bisulfite. Potassium permanganate / oxalic acid and ammonium persulfate / sulfite / iron(II) sulfate are preferred. When using a redox initiator, either the oxidizing agent or the reducing agent may be pre-charged into a polymerization vessel, followed by continuous or intermittent addition of the other agent to initiate polymerization. For example, when using potassium permanganate / oxalic acid, it is preferred to charge oxalic acid into a polymerization vessel and then continuously add potassium permanganate.

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

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

[0444] In the polymerization, TFE may be polymerized in the presence of an anionic hydrocarbon surfactant. The use of an anionic hydrocarbon surfactant improves the stability of the aqueous dispersion produced by the polymerization, allowing the polymerization of TFE to proceed smoothly.

[0445] In the above polymerization, TFE may also be polymerized substantially in the absence of an anionic hydrocarbon surfactant. When TFE is polymerized in the presence of polymer (I), the polymerization of TFE 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 typically have a hydrophilic portion, such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion, which is a long-chain hydrocarbon moiety, such as an alkyl.

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

[0449] The anionic hydrocarbon surfactants include RLM (wherein R is a linear or branched alkyl group having one or more carbon atoms which may have a substituent, or a cyclic alkyl group having three or more carbon atoms which may have a substituent, and when the alkyl group has three 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 - and 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. )

[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). A mixture 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, as anionic hydrocarbon surfactants, R 6 (-LM)2(wherein, R 6 is a linear or branched alkylene group having one or more carbon atoms which may have a substituent, or a cyclic alkylene group having three or more carbon atoms which may have a substituent, and when the number of carbon atoms is three or more, it may contain a monovalent or divalent heterocycle or may form a ring. -, -SO3 - , -SO4-, -PO3 - or COO - and 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. )

[0452] In addition, as anionic hydrocarbon surfactants, R 7 (-LM)3(wherein, R 7 is a linear or branched alkylidyne group having one or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having three or more carbon atoms which may have a substituent, and when the number of carbon atoms is three or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3 - or COO - and 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. )

[0453] Anionic hydrocarbon surfactants also include siloxane hydrocarbon surfactants. Examples of siloxane hydrocarbon surfactants include those described in Silicone Surfactants, R.M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of siloxane hydrocarbon surfactants includes a distinct hydrophobic portion and a hydrophilic portion. The hydrophobic portion includes one or more dihydrocarbylsiloxane units, where the substituents on the silicone atoms are entirely hydrocarbon. These siloxane surfactants can also be considered hydrocarbon surfactants in the sense that the carbon atoms of the hydrocarbyl groups are entirely substituted with hydrogen atoms, even if they may be substituted with halogens such as fluorine, i.e., the monovalent substituents on the carbon atoms of the hydrocarbyl groups are hydrogen.

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

[0455] The hydrophilic portion of the siloxane hydrocarbon surfactant may also contain a combination of ionic and nonionic moieties, such as ionically end-functionalized or randomly functionalized polyethers or polyols. Preferred are siloxanes with nonionic moieties, i.e., nonionic 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 Lankropol® K8300, a sulfosuccinate surfactant from Akzo Nobel Surface Chemistry LLC. Sulfosuccinate surfactants include sodium diisodecyl sulfosuccinate (Emulsogen® SB10 from Clariant) and sodium diisotridecyl 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 anionic hydrocarbon surfactants 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 includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. 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 carbon number is 3 or more, it may contain a monovalent or divalent heterocycle, or may form a ring. M is the same as above. ) are also included. Specifically, 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 those represented by the following formula (A): R-COO-M(A) (wherein R is an alkyl group, alkenyl group, alkylene group, or alkenylene group containing 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 5 to 23. When the alkyl group is branched, R preferably has 5 to 35 carbon atoms, and more preferably 11 to 23. When the alkenyl group is linear, R preferably has 2 to 29 carbon atoms, and more preferably 9 to 23. When the alkenyl group is branched, R preferably has 2 to 29 carbon atoms, and more preferably 9 to 23.

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

[0466] Further, examples of the anionic hydrocarbon surfactant include carboxylic acid hydrocarbon surfactants. Examples of the carboxylic acid hydrocarbon surfactants 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, myristic acid, hydroxypropyl methylcellulose ... Examples of suitable 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. Particularly preferred are at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecylic acid, palmitic acid, and salts thereof. The salts include those in which the hydrogen atom of the carboxyl group is bonded to a metal atom of the 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] Furthermore, examples of anionic hydrocarbon surfactants that can be used include those described in International Publication Nos. 2013 / 146950 and 2013 / 146947. Examples include those having a saturated or unsaturated aliphatic chain with 6 to 40 carbon atoms, preferably 8 to 20 carbon atoms, and more preferably 9 to 13 carbon atoms. 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, 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. The aliphatic carboxylic acid or a salt thereof is preferably succinic acid, decanoic acid, undecanoic acid, undecenoic acid, lauric acid, hydrododecanoic acid, or a salt thereof.

[0470] In the above polymerization, TFE can be polymerized in the presence of a fluorine-containing surfactant (excluding compounds having a functional group reactive in radical polymerization and a hydrophilic group). The use of a fluorine-containing surfactant improves the stability of the aqueous dispersion produced by the polymerization, allowing the polymerization of TFE to proceed 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 reactive in radical polymerization and a hydrophilic group). When TFE is polymerized in the presence of polymer (I), the polymerization of TFE proceeds smoothly even without the use of a fluorine-containing surfactant. In the above polymerization, by polymerizing TFE substantially in the absence of a fluorine-containing surfactant, a composition substantially free of a fluorine-containing surfactant can be easily obtained.

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

[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% by mass or less, more preferably 2.0% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.8% by mass or less, even more preferably 0.7% by mass or less, and particularly preferably 0.6% by mass or less, based on the final PTFE obtained.

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

[0476] A powder can be produced by agglomerating the PTFE contained in the aqueous dispersion. The composition of the present disclosure may be in the form of a powder. The aqueous dispersion containing PTFE and polymer (I) can be used in various applications as a powder after post-treatment such as concentration, coagulation, washing, and drying, if necessary. When coagulating the aqueous dispersion of PTFE, the aqueous dispersion obtained by polymerization of a polymer latex or the like is usually diluted with water to a polymer concentration of 10 to 25% by mass (preferably 10 to 20% by mass), and the pH is adjusted to neutral or alkaline as needed. The coagulation is then carried out in a vessel equipped with a stirrer, with stirring more vigorously than during the reaction. The coagulation may be carried out while stirring, using a coagulant such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be carried out 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 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 typically dried using a vacuum, high frequency, hot air, or other means while maintaining the wet powder in a state where it is not fluidized, preferably in a static state. Friction between powders, especially at high temperatures, generally has an undesirable effect on fine powder-type PTFE. This is because particles of this type of PTFE tend to easily fibrillate even with small shear forces, losing their original stable particle structure. The drying can be carried out at a drying temperature of 10 to 300°C (preferably 10 to 250°C), preferably 100 to 300°C (preferably 100 to 250°C).

[0479] When the composition of the present disclosure is in the form of 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 stretchability and non-melt processability, and is useful as a raw material for stretched bodies (porous bodies). By stretching the composition of the present disclosure, stretched bodies with excellent breaking strength and stress relaxation time can be obtained. For example, a powder of the composition of the present disclosure mixed with an extrusion aid is paste-extruded, optionally rolled, dried to remove the extrusion aid, and then stretched in at least one direction to obtain a stretched body. By stretching, the PTFE in the composition of the present disclosure easily fibrillates, resulting in a stretched body consisting of nodes and fibers. This stretched body is also a porous body with a high porosity.

[0482] The present disclosure also relates to an elongated body made from the above-described composition. The stretched body of the present disclosure can be produced by paste extruding and 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 using 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 using a tenter or the like. The extrudate may be subjected to semi-sintering treatment before stretching.

[0483] The stretching conditions preferably employed are a speed of 5 to 2000% / sec and a stretch ratio of 200% or more. By stretching, the PTFE in the composition is easily fibrillated, resulting in a stretched body consisting of nodes and fibers. 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 stretched films stacked together, and dividing the measured value by 5 to obtain the film thickness of one film. 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 that value by 2. 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 a stretched body comprising a polymer (I) including polytetrafluoroethylene and polymerization units (I) based on a monomer represented by the following general formula (I), and characterized by 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 CF; 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 greater.

[0486] In the stretched body of the present disclosure, the polytetrafluoroethylene and 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 more preferably has a breaking strength A of 13.0 N or more, even 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 measured by clamping and fixing the stretched body 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 break 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 even 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 connecting both ends of the stretched specimen to fixtures to create a taut, 8-inch (20 cm) long sample, and inserting the fixtures into the oven at 390°C through a (covered) slit in the side of the oven. The time required from the time of insertion into the oven until the sample breaks is taken as the stress relaxation time.

[0490] The stretched product of the present disclosure preferably has an endothermic peak temperature between 325 and 350° C. Furthermore, 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 the temperature corresponding to the maximum value in the 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 by the same method as described above.

[0492] The stretched product of the present disclosure preferably has a content of polymer (I) of 0.0001% by mass or more and 20% by mass or less relative to the polytetrafluoroethylene. In the stretched product of the present disclosure, the lower limit of the content of polymer (I) relative to the polytetrafluoroethylene is more preferably 0.001% by mass, even more preferably 0.01% by mass, and particularly preferably 0.1% by mass. 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 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 the 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 when measured by liquid chromatography-mass spectrometry (LC / MS). The fluorine-containing surfactant is a surfactant containing fluorine atoms 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 acids (I) represented by general formula (I), ω-H perfluorocarboxylic acids (II) represented by general formula (II), perfluoropolyether carboxylic acids (III) represented by general formula (III), perfluoroalkyl alkylene carboxylic acids (IV) represented by general formula (IV), alkoxy fluorocarboxylic acids (V) represented by general formula (V), perfluoroalkyl sulfonic acids (VI) represented by general formula (VII), ω-H perfluoro sulfonic acids (VII) represented by general formula (VII), perfluoroalkyl alkylene sulfonic acids (VIII) represented by general formula (VIII), alkyl alkylene carboxylic acids (IX) represented by general formula (IX), fluorocarboxylic acids (X) represented by general formula (X), alkoxy fluoro sulfonic acids (XI) represented by general formula (XI), compounds (XII) represented by general formula (XII), compounds (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 film. Furthermore, a biaxially stretched film can also be obtained by stretching the film in the width direction using a tenter or the like. It is also preferable to carry out a semi-baking treatment before stretching.

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

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

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

[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 computers 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), filters for pure water production lines (for pure water production), backwash type liquid filtration filters (for industrial wastewater treatment), etc.

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

[0503] Textile field 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 mater replacement), 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 can be made without departing from the spirit and scope of the claims. [Example]

[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 to a solid content of 0.15% by mass, and the transmittance of the diluted latex to a 550 nm incident light per unit length and the number-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 incident light for each sample. The average primary particle size can also be measured by dynamic light scattering. For 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 with an ELSZ-1000S (Otsuka Electronics Co., Ltd.) for a total of 70 measurements. 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, measurements were made 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 on the heat of fusion curve was determined as the endothermic peak temperature of PTFE.

[0511] Modified monomer unit content The HFP content was determined by press-molding PTFE powder to create a thin film disk, measuring the infrared absorbance of the thin film disk by FT-IR, and determining the HFP content at 982 cm -1 Absorbance at / 935cm -1 The absorbance ratio was calculated by multiplying the absorbance ratio by 0.3. The content of PMVE units is solid 19 It was calculated using the following formula from the spectrum obtained by F-MAS NMR measurement. X = (4B / 3) / (A+(B / 3)) × 100 X: Content of PMVE units (mol%) A: Integrated value of the signal at -120 ppm 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 content 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 It was calculated using the following formula from the spectrum obtained by F-MAS NMR measurement. Y = (4B / (5A+3B)) x 100 Y: Polymer A or Polymer D content (mol%) A: Integrated value of the signal at -120 ppm 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 according to the method described in JP 2002-201217 A, using the following method. 21.7 g of a lubricant (trade name: Isopar H (registered trademark), manufactured by Exxon) was added to 100 g of the PTFE powder obtained in the examples 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 through an orifice (diameter 2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 at room temperature to obtain a uniform bead (extrusion molded product). 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 during paste extrusion and dividing the measured value by the cross-sectional area of the cylinder used for paste extrusion.

[0515] The elongation test and the measurement of breaking strengths A to D were carried out in accordance with the method described in JP-A No. 2002-201217, as follows. 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 an appropriate length, clamped at each end with a clamp spacing of 1.5 inches (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 reached, and a stretching 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 manufacturing 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 with a gauge length of 5.0 cm, and a tensile test was performed at 25°C and a speed of 300 mm / min, and the strength at break was measured as breaking strength A.

[0517] Breaking strength B A stretched bead was obtained in the same manner as in stretching test A, except that the clamp distance was changed to 2.0 inches (51 mm) and the stretch rate was changed to 100% / sec. Breaking strength B was measured in the same manner as in measuring 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. Using the obtained PTFE powder, breaking strength D was measured 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 stretch rate 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 obtained in Stretch Test A above are connected to fixtures to create 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 required 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. Uneven: The appearance of the stretched bead was uneven, with cracks, undulations, and variations in density observed in the stretched bead.

[0522] Aspect Ratio An aqueous dispersion diluted to a solids concentration of approximately 1% by mass was observed using a scanning electron microscope (SEM). Images of more than 400 randomly selected particles were processed, and the average ratio of their major and minor diameters was calculated.

[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 polymer aqueous solution was measured, and an amount of the aqueous solution equivalent to 0.2 g of polymer solid content was weighed. Then, the 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 mixture containing the polymer, water, and methanol. Then, the obtained mixture 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 dimers and trimers of the monomer contained in the extract were determined by converting the integral values of the peaks derived from dimers and trimers of the monomer appearing in the chromatogram of the extract into the contents of dimers and trimers of the monomer using a calibration curve.

[0524] (2) Monomer calibration curve Five methanol standard solutions of known monomer contents ranging from 1 ng / mL to 100 ng / mL were prepared and analyzed 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 versus that content was plotted to create a calibration curve (first-order approximation) for each monomer. Next, using the calibration curves (first-order approximation) for each monomer, calibration curves for the dimer and trimer of each monomer were created.

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

[0526] The limit of quantitation 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 following formula was used. The number-average molecular weight and weight-average molecular weight of the polymer were measured by gel permeation chromatography (GPC) using a GPC HLC-8020 manufactured by Tosoh Corporation and Shodex columns (one GPC KF-801, one GPC KF-802, and two GPC KF-806M connected in series) with tetrahydrofuran (THF) as the solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as the standard.

[0528] Example 1 A 6 L stainless steel reactor equipped with a stirrer was charged with 3560 g of deionized water, 104 g of paraffin wax, 5.37 g of polymer A, and 77.3 mg of modified monomer A. The pH was adjusted to 9.1 by adding aqueous ammonia. The reactor contents were then heated to 70°C while evacuating and simultaneously purging with TFE to remove oxygen from the reactor, and the contents were stirred. 0.8 g of HFP was added to the reactor, followed by TFE until the pressure reached 0.73 MPaG. 17.9 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor, bringing the reactor pressure to 0.83 MPaG. After the initiator injection, a pressure drop occurred and polymerization initiation was observed. TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When approximately 180 g of TFE had been consumed in the reaction, the TFE supply and stirring were stopped. The gas in the reactor was then slowly released until the reactor pressure reached 0.02 MPaG. TFE was then added until the reactor pressure reached 0.78 MPaG, and stirring was resumed to continue the reaction. When approximately 540 g of TFE had been consumed in the reaction, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was added to the reactor, and the reaction was continued. When approximately 1250 g of TFE had been consumed in the reaction, the TFE supply was stopped, stirring was stopped, and the reaction was terminated. The reactor was then vented to atmospheric pressure, and the contents were removed and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solids concentration of the resulting PTFE aqueous dispersion was 25.7% by mass, and the average primary particle size was 249 nm. The resulting PTFE aqueous dispersion was diluted with deionized water to a solids concentration of approximately 10% by mass, coagulated under high-speed stirring, and the coagulated wet powder was dried at 210°C for 18 hours. The 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 amount of 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 solids concentration of the obtained PTFE aqueous dispersion was 24.4 mass %, and the average primary particle size was 275 nm. Furthermore, 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 the 14.3 mg of hydroquinone in Example 1 was not injected into the reactor. The solids concentration of the obtained PTFE aqueous dispersion was 25.4 mass %, and the average primary particle size was 242 nm. Furthermore, 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 A 3 L stainless steel reactor equipped with a stirrer was charged with 1800 g of deionized water, 90 g of paraffin wax, 2.70 g of polymer A, and 38.9 mg of modified monomer A. The pH was adjusted to 9.1 by adding aqueous ammonia. The reactor contents were then heated to 80°C while evacuating and simultaneously purging with TFE to remove oxygen from the reactor, and the contents were stirred. 2.3 g of HFP was added to the reactor, followed by TFE until the pressure reached 1.50 MPaG. 9.0 mg of ammonium persulfate (APS) initiator was injected into the reactor. After the initiator injection, a pressure drop occurred and the initiation of polymerization was observed. TFE was added to the reactor to maintain a constant pressure of 1.50 MPaG. When approximately 90 g of TFE had been consumed in the reaction, the TFE supply and stirring were stopped. The reactor was then slowly vented until the pressure reached atmospheric pressure, and the reactor was then held under vacuum for 1 minute. TFE was then supplied until the reactor pressure reached 2.50 MPaG, and stirring was resumed to continue the reaction. When the amount of TFE consumed in the reaction reached approximately 180 g, 14.4 mg of hydroquinone dissolved in 20 g of deionized water was added to the reactor, and the reaction was continued. When the amount of TFE consumed in the reaction reached approximately 600 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. The reactor was then vented to atmospheric pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the aqueous PTFE dispersion. The solids concentration of the resulting aqueous PTFE dispersion was 26.9% by mass, and the average primary particle size was 196 nm. The resulting aqueous PTFE dispersion was diluted with deionized water to a solids concentration of approximately 10% by mass, coagulated under high-speed stirring, and the coagulated wet powder was dried at 210°C for 18 hours. The physical properties of the resulting 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 charged with 0.5 mol % 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 polymer D aqueous solution D-1 containing polymer D, which is a homopolymer of CH2=CF(CF2OCFCF3COOH). GPC analysis of the obtained polymer D aqueous solution D-1 showed that polymer D had an Mw of 180,000, an Mn of 86,000, and a dimer and trimer content of 2.0% by mass based on polymer D.

[0535] Water was added to the obtained polymer D aqueous solution D-1 to adjust the polymer D concentration to 5.0% by mass, and then ultrafiltration was carried out by contacting the solution with an ultrafiltration membrane (molecular weight cutoff 50,000 Da, made of polyethylene) at 30°C under a water pressure of 0.1 MPa. Ultrafiltration was continued while appropriately adding water until a filtrate containing 7 times the amount of water relative to the aqueous solution was finally eluted, thereby obtaining polymer D aqueous solution D-2. GPC analysis of the obtained polymer D aqueous solution D-2 showed that polymer D had an Mw of 180,000, an Mn of 140,000, and a dimer and trimer content of less than 1 ppm relative to polymer D. The concentration of the obtained polymer D aqueous solution D-2 was 5.0% by mass.

[0536] Example 5 A 6 L stainless steel reactor equipped with a stirrer was charged with 3457 g of deionized water, 180 g of paraffin wax, 107.4 g of Polymer D aqueous solution D-2, and 1.1 g of a 1.0 wt% isopropanol aqueous solution. The pH was adjusted to 9.1 by adding aqueous ammonia. The reactor contents were then heated to 70°C while evacuating and simultaneously purging with TFE to remove oxygen from the reactor, and the contents were stirred. 0.54 g of PMVE was added to the reactor, followed by TFE addition until the pressure reached 0.73 MPaG. 17.9 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor, bringing the reactor pressure to 0.83 MPaG. After the initiator injection, a pressure drop occurred and the initiation of polymerization was observed. TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached approximately 180 g, the TFE supply and stirring were stopped. The gas in the reactor was then slowly released until the reactor pressure reached 0.02 MPaG. TFE was then supplied until the reactor pressure reached 0.78 MPaG, and stirring was resumed to continue the reaction. When the amount of TFE consumed in the reaction reached approximately 540 g, 14.3 mg of hydroquinone dissolved in 20 g of deionized water was injected into the reactor, and the reaction continued. When the amount of TFE consumed in the reaction reached approximately 1200 g, the TFE supply was stopped, stirring was stopped, and the reaction was terminated. The reactor was then vented to atmospheric pressure, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The physical properties of the resulting PTFE aqueous dispersion were measured. The results are shown in the table.

[0537] The resulting PTFE aqueous dispersion was diluted with deionized water to a solids concentration of approximately 10% by mass, coagulated under high-speed stirring, and the coagulated wet powder was dried at 210°C for 18 hours. The physical properties of the resulting 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 replaced with 1.8 g of a 0.1 mass% aqueous solution of Triton X-100 (trade name, manufactured by The Dow Chemical Company) (hereinafter referred to as "Triton aqueous solution"). Various physical properties of the resulting aqueous PTFE dispersion were measured. The results are shown in the table below. 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 placed in 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 maintained constant without stopping the TFE supply and stirring when the amount of TFE consumed in the reaction reached approximately 180 g. 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.

[0545] Example 13 Polymerization was carried out in the same manner as in Example 5, except that no aqueous isopropanol solution was placed in the reactor. 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.

[0546] [Table 4]

[0547] [Table 5]

[0548] [Table 6]

Claims

1. Polytetrafluoroethylene, A composition comprising a polymer (I) containing polymerized 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 CF ３ and 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.

2. The composition according to claim 1, which has a breaking strength of 10.0 N or more.

3. 3. The composition according to claim 1, wherein the stress relaxation time is 50 seconds or more.

4. The composition according to any one of claims 1 to 3, wherein the extrusion pressure is 10.0 MPa or more and 30.0 MPa or less.

5. 5. The composition according to claim 1, wherein the polytetrafluoroethylene has an endothermic peak temperature in the range of 333 to 347°C.

6. 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, and R ７ is H or an organic group.

7. The composition according to any one of claims 1 to 6, which is substantially free of a fluorine-containing surfactant.

8. The composition according to any one of claims 1 to 7, which is in the form of a powder.

9. A stretched body comprising the composition according to any one of claims 1 to 8.

10. Polytetrafluoroethylene, A stretched product comprising a polymer (I) containing polymerized units (I) based on a monomer represented by the following general formula (I): CX １ X ３ =CX ２ R(-CZ １ Z ２ -A ０ ) ｍ (I) (In the formula, X １ and X ３ are each independently F, Cl, H or CF ３ and 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.

11. The stretched body according to claim 10, which has a breaking strength of 10.0 N or more.

12. 12. The stretched body according to claim 10, wherein the stress relaxation time is 50 seconds or more.

13. The stretched body according to any one of claims 10 to 12, wherein the endothermic peak temperature is between 325 and 350°C.

14. 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, and R ７ The stretched body according to any one of claims 10 to 13, wherein the anionic group is

15. The stretched body according to any one of claims 10 to 14, which is substantially free of a fluorine-containing surfactant.

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