Tetrafluoroethylene-based polymer composition, binder for electrochemical device, electrode mixture, electrode, and secondary battery

Abstract

The purpose of the present invention is to provide a tetrafluoroethylene (TFE)-based polymer composition for a binder for an electrochemical device capable of reducing the resistance of a mixture sheet. This TFE-based polymer composition is used for a binder for an electrochemical device, contains a TFE-based polymer, at least one compound selected from the group consisting of compounds represented by general formulas (1) and (2), and a conductive carbon material. The amount of the TFE-based polymer with respect to the solid content is 10 mass% or more. General formula (1): (H-(CF2)m−1-COO)pM1 (In the formula, m is 4-20, M1 is H, a metal atom, NR5 4 (the R5 moieties may be the same or different, and each represents H or a C1-10 organic group), or the like, and p is 1 or 2.) General formula (2): (H-(CF2)n-SO3)qM2 (In the formula, n is 4-20, M2 is H, a metal atom, NR5 4 (the R5 moieties are as defined above), or the like, and q is 1 or 2.)

Description

Tetrafluoroethylene-based polymer composition, binder for electrochemical device, electrode mixture, electrode, and secondary battery

[0001] The present disclosure relates to a tetrafluoroethylene-based polymer composition, a binder for an electrochemical device, an electrode mixture, an electrode, and a secondary battery.

[0002] Secondary batteries such as lithium-ion secondary batteries are used in small, portable electrical and electronic devices such as notebook computers, mobile phones, smartphones, tablet computers, and ultrabooks because of their high voltage, high energy density, low self-discharge, low memory effect, and the ability to be ultra-lightweight, and are also being put into practical use as a wide range of power sources, including on-board power sources for driving automobiles and large-scale stationary power sources. Demand is now being placed on secondary batteries to achieve even higher energy densities, and further improvements in their battery characteristics are being sought.

[0003] Patent Documents 1 to 4 describe binders in which polytetrafluoroethylene and a conductive carbon material are mixed.

[0004] International Publication No. WO 2018 / 175465 International Publication No. WO 2022 / 138939 International Publication No. WO 2022 / 138940 International Publication No. WO 2022 / 138942

[0005] An object of the present disclosure is to provide a tetrafluoroethylene-based polymer composition for a binder for an electrochemical device that can reduce the resistance of a composite sheet, as well as a binder for an electrochemical device, an electrode composite, an electrode, and a secondary battery that use the same.

[0006] The present disclosure (1) is a tetrafluoroethylene-based polymer composition used in a binder for an electrochemical device, the tetrafluoroethylene-based polymer composition comprising a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of compounds represented by the following general formula (1) and compounds represented by the following general formula (2), and a conductive carbon material, wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10 mass % or more. ２ )ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ ) ｎ -SO ３ ) ｑ M ２ (wherein n is 4 to 20. M ２ is H, metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0007] The present disclosure (2) is the tetrafluoroethylene-based polymer composition according to the present disclosure (1), wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a tetrafluoroethylene homopolymer and a modified polytetrafluoroethylene consisting only of tetrafluoroethylene units and polymerization units based on hexafluoropropylene.

[0008] The present disclosure (3) is the tetrafluoroethylene-based polymer composition according to the present disclosure (1) or (2), in which the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 55% by mass or more and 96% by mass or less.

[0009] The present disclosure (4) is the tetrafluoroethylene-based polymer composition according to any one of the present disclosures (1) to (3) in the form of powder.

[0010] The present disclosure (5) is a tetrafluoroethylene-based polymer composition according to any one of the present disclosures (1) to (4), which is used as a binder for a lithium-ion secondary battery.

[0011] The present disclosure (6) is a binder for electrochemical devices consisting essentially of a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition contains a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of compounds represented by the following general formula (1) and compounds represented by the following general formula (2), and a conductive carbon material, and the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10 mass % or more. ２ ) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ ) ｎ -SO ３ ) ｑ M ２ (wherein n is 4 to 20. M ２ is H, metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0012] The present disclosure (7) is the binder for electrochemical devices according to the present disclosure (6), wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 30 mass % or more.

[0013] The present disclosure (8) is the binder for electrochemical devices according to the present disclosure (6) or (7), wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 55 mass % or more and 96 mass % or less.

[0014] The present disclosure (9) is the binder for electrochemical devices according to any one of the present disclosures (6) to (8), wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.

[0015] The present disclosure (10) is the binder for electrochemical devices according to any one of the present disclosures (6) to (9), wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a tetrafluoroethylene homopolymer and a modified polytetrafluoroethylene consisting only of tetrafluoroethylene units and polymerization units based on hexafluoropropylene.

[0016] The present disclosure (11) is the binder for electrochemical devices according to any one of the present disclosures (6) to (10), wherein the conductive carbon material is a carbon nanotube.

[0017] The present disclosure (12) is the binder for electrochemical devices according to any one of the present disclosures (6) to (11), wherein the amount of the conductive carbon material relative to the solid content in the tetrafluoroethylene-based polymer composition is 1 to 70 mass%.

[0018] The present disclosure (13) is the binder for electrochemical devices according to any one of the present disclosures (6) to (12), wherein the tetrafluoroethylene-based polymer composition is substantially free of moisture.

[0019] The present disclosure (14) is the binder for electrochemical devices according to any one of the present disclosures (6) to (13), wherein the tetrafluoroethylene-based polymer composition is substantially free of a compound represented by the following general formula (3): General formula (3): (H—(CF ２ ) ８ -SO ３ ) ｑ M ２ (In the formula, M ２ is H, metal atom, NR ５ ４ (R５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent; and q is 1 or 2.

[0020] The present disclosure (15) is the binder for electrochemical devices according to any one of the present disclosures (6) to (14), wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of compounds represented by the following general formula (4) and compounds represented by the following general formula (4'), and the content of each of the compounds is 1000 mass ppb or less relative to the tetrafluoroethylene-based polymer composition. ２ ) １５ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different, and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (4'): (H-(CF ２ ) １６ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. p is 1 or 2.

[0021] The present disclosure (16) is the binder for electrochemical devices according to any one of the present disclosures (6) to (15), wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of compounds represented by the following general formula (5) and compounds represented by the following general formula (5'), and the content of each of the compounds is 1000 mass ppb or less relative to the tetrafluoroethylene-based polymer composition. ２ ) １３ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different, and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (5'): (H-(CF ２ ) １４ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. p is 1 or 2.

[0022] The present disclosure (17) is the binder for electrochemical devices according to any one of the present disclosures (6) to (16), wherein the thermal instability index (TII) of the tetrafluoroethylene-based polymer composition is 5 or more.

[0023] The present disclosure (18) is the binder for electrochemical devices according to any one of the present disclosures (6) to (17), which is in the form of powder.

[0024] The present disclosure (19) is the binder for electrochemical devices according to any one of the present disclosures (6) to (18), which is for use in lithium ion secondary batteries.

[0025] The present disclosure (20) is an electrode mixture comprising the tetrafluoroethylene-based polymer composition according to any one of the present disclosures (1) to (5) or the binder for electrochemical devices according to any one of the present disclosures (6) to (19), and an electrode active material.

[0026] The present disclosure (21) is the electrode mixture according to the present disclosure (20) in the form of a sheet.

[0027] The present disclosure (22) is an electrode comprising the tetrafluoroethylene-based polymer composition according to any one of the present disclosures (1) to (5) or the binder for electrochemical devices according to any one of the present disclosures (6) to (19), an electrode active material, and a current collector.

[0028] The present disclosure (23) is a secondary battery comprising the electrode according to the present disclosure (22).

[0029] According to the present disclosure, it is possible to provide a tetrafluoroethylene-based polymer composition for a binder for an electrochemical device that can reduce the resistance of a composite sheet, as well as a binder for an electrochemical device, an electrode composite, an electrode, and a secondary battery that use the same.

[0030] In the present disclosure, the term "organic group" refers to a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. The organic group is preferably an alkyl group which may have one or more substituents.

[0031] The present disclosure will be specifically described below.

[0032] The present disclosure provides a tetrafluoroethylene (TFE)-based polymer composition for use in a binder for electrochemical devices, the TFE-based polymer composition comprising a TFE-based polymer, at least one compound selected from the group consisting of compounds represented by the following general formula (1) and compounds represented by the following general formula (2), and a conductive carbon material, wherein the amount of the TFE-based polymer relative to the solid content in the TFE-based polymer composition is 10% by mass or more. ２ ) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ ) ｎ -SO ３ ) ｑ M ２ (wherein n is 4 to 20. M ２ is H, metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0033] The TFE polymer composition of the present disclosure has the above-mentioned structure, so that the resistance of the composite sheet can be reduced.In addition, when it is made into a powder form, it can also improve flowability.The TFE polymer composition of the present disclosure can also be used in a dry process, so that it is not necessary to use a large amount of dispersion medium such as water or organic solvent, and it is possible to widely select the electrode active material and solid electrolyte to be combined, which is advantageous in production process.In addition, it can reduce the process and cost due to the use of dispersion medium.Furthermore, the TFE polymer composition of the present disclosure has excellent binding strength with active material and electrolyte, so that it can reduce the amount used.

[0034] The TFE polymer in the TFE polymer composition of the present disclosure may be a TFE homopolymer, or may be a TFE copolymer comprising TFE-based polymerization units (TFE units) and TFE-based polymerization units (modified monomer units) copolymerizable with modified monomers.The TFE polymer may be polytetrafluoroethylene (PTFE).The PTFE includes TFE homopolymers and modified PTFE comprising 99.0 mass% or more TFE units and 1.0 mass% or less modified monomer units.The TFE polymer is preferably PTFE, more preferably modified PTFE, in that it can obtain a composite sheet with lower resistance and further improve powder flowability.In addition, in the present disclosure, the TFE homopolymer refers to the content of modified monomer units relative to the total polymerization units is less than 0.0001 mass%.

[0035] The content of the modified monomer unit is preferably in the range of 0.0001 to 10 mass% relative to the total polymerized units, in order to obtain a composite sheet with lower resistance and further improve powder flowability.The lower limit of the content of the modified monomer unit is more preferably 0.001 mass%, more preferably 0.010 mass%, even more preferably 0.015 mass%, and particularly preferably 0.020 mass%.The upper limit of the content of the modified monomer unit is preferably 5.0 mass%, more preferably 3.0 mass%, more preferably 1.0 mass%, even more preferably 0.80 mass%, even more preferably 0.60 mass%, even more preferably 0.50 mass%, even more preferably 0.40 mass%, even more preferably 0.30 mass%, and particularly preferably 0.20 mass%.In this specification, the modified monomer unit refers to a part of the molecular structure of the TFE polymer that is derived from the modified monomer.

[0036] The content of each of the above-mentioned polymerized units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0037] As the above-mentioned modified monomer, as long as it can be copolymerized with TFE, there is no particular limitation, for example, can be listed perfluoroolefin such as hexafluoropropylene (HFP); trifluoroethylene, vinylidene fluoride (VDF) etc. hydrogen-containing fluoroolefin; perhaloolefin such as chlorotrifluoroethylene (CTFE); perfluorovinyl ether; perfluoroallyl ether; (perfluoroalkyl) ethylene, ethylene, the monomer with polar group etc. In addition, the modified monomer used can be one kind or multiple kinds.

[0038] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the following general formula (A): CF ２ =CF-ORf １ (A) (wherein, Rf １ represents a perfluoroorganic group. ) and perfluorounsaturated compounds represented by the following formula: In this specification, 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.

[0039] The perfluorovinyl ether is, for example, perfluoro(alkyl vinyl ether) [PAVE], preferably, Rf １ is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0040] 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.

[0041] The perfluorovinyl ether further includes a compound represented by the general formula (A) below, wherein Rf １ is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf １ is of the following formula:

[0042]

[0043] (wherein m represents 0 or an integer of 1 to 4), Rf １ is of the following formula:

[0044]

[0045] (wherein n represents an integer of 1 to 4).

[0046] The (perfluoroalkyl)ethylene [PFAE] is not particularly limited, and examples thereof include (perfluorobutyl)ethylene [PFBE] and (perfluorohexyl)ethylene.

[0047] Examples of perfluoroallyl ethers include those represented by the general formula (B): CF ２ =CF-CF ２ -ORf ２ (B) (wherein, Rf ２ represents a perfluoroorganic group.

[0048] The above Rf ２ is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. ２ =CF-CF ２ -O-CF ３ , C.F. ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF ２ =CF-CF ２ -O-C ４ F ９ At least one selected from the group consisting of CF ２ =CF-CF ２ -O-C ２ F ５ , C.F. ２ =CF-CF ２ -O-C ３ F ７ , and CF２ =CF-CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ =CF-CF ２ -O-CF ２ CF ２ CF ３ is more preferred.

[0049] The modified monomer is represented by the following general formula (i): CX １ X ２ =CX ３ X ４ (i) (wherein, X １ ~X ３ are each independently H or F. ４ is F, Cl, Rf or O-Rf, and Rf is a perfluoroorganic group.

[0050] Rf in general formula (i) is preferably a perfluoroalkyl group having 1 to 10 carbon atoms, more preferably a perfluoroalkyl group having 1 to 5 carbon atoms, and even more preferably a perfluoroalkyl group having 1 to 4 carbon atoms.

[0051] The polar group-containing monomer may be a fluorine-free monomer or a fluorine-containing monomer.

[0052] Examples of the fluorine-free monomer include hydroxyl group-containing fluorine-free monomers such as hydroxyalkyl vinyl ethers, such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; carboxyl group-containing fluorine-free monomers, such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, fumaric acid, crotonic acid, maleic acid, citraconic acid, undecylenic acid, and acetylenedicarboxylic acid; itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2, Examples of suitable monomers include 3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), succinic anhydride, fumaric anhydride, maleic anhydride, and other fluorine-containing monomers having an acid anhydride residue; fluorine-containing monomers having a sulfo group such as vinyl sulfonic acid; fluorine-containing monomers having an epoxy group (glycidyl group) such as glycidyl vinyl ether and glycidyl allyl ether; fluorine-containing monomers having an amino group such as aminoalkyl vinyl ether and aminoalkyl allyl ether; fluorine-containing monomers having an amide group such as (meth)acrylamide and methylolacrylamide; and fluorine-containing monomers having a nitrile group such as acrylonitrile and methacrylonitrile. Among these, preferred are fluorine-containing monomers having a carboxy group and fluorine-containing monomers having an acid anhydride residue, more preferred are fluorine-containing monomers having an acid anhydride residue, and even more preferred are cyclic fluorine-containing monomers having an acid anhydride residue.

[0053] The polar group-containing 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)").

[0054] The hydrophilic group in the modified monomer (A) is, for example, —NH ２ , -PO ３ M, -OPO ３ M, -SO ３ M, -OSO ３ M, -COOM (in each formula, M is H, a metal atom, NR ７ ４, optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ are H or organic groups and may be the same or different. Any two of them may be bonded to each other to form a ring.) Among the above hydrophilic groups, -SO ３ M or -COOM is preferred. ７ As the group, H or C １－１０ is preferably an organic group represented by the formula: １－４ More preferred are organic groups represented by the formula: １－４ The metal atom is preferably a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), and more preferably Na, K, or Li.

[0055] 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- (wherein, X ｅ , X ｆ and X ｇ are each independently F, Cl, H, or CF ３ , C.F. ２ H, C.F.H. ２ , or CH ３ and R is a linking group. The linking group of R can be represented by the formula: ａ Preferably, the linking group is -CH=CH ２ , -CF=CH ２、 -CH=CF ２、 -CF = CF ２ , -CH ２ -CH=CH ２ , -CF ２ -CF=CH ２ , -CF ２ -CF = CF ２ , -(C=O)-CH=CH ２ , -(C=O)-CF=CH ２ , -(C=O)-CH=CF ２, -(C=O)-CF=CF ２ , -(C=O)-C(CH ３ ) = CH ２ , -(C=O)-C(CF ３ ) = CH ２ , -(C=O)-C(CH ３ ) = CF ２ , -(C=O)-C(CF ３ ) = CF ２ , —O—CH ２ -CH=CH ２ , —O—CF ２ -CF=CH ２ , —O—CH ２ -CH=CF ２ , —O—CF ２ -CF = CF ２ Examples of groups having an unsaturated bond include the following.

[0056] The modified monomer (A) has a functional group capable of reacting by radical polymerization, so when used in polymerization, it is assumed that it will react with the fluorine-containing monomer at the initial stage of the polymerization reaction, and form particles having hydrophilic groups derived from the modified monomer (A) and having high stability.Therefore, it is thought that when polymerization is carried out in the presence of the modified monomer (A), the number of particles will increase.

[0057] The modifying monomer (A) may be used alone or in combination of two or more.

[0058] As the modifying monomer (A), a compound having an unsaturated bond can be used.

[0059] The modifying monomer (A) is preferably at least one selected from the group consisting of compounds represented by the following formulas (4a) to (4e): CF ２ =CF-(CF ２ ) ｎ１ -Y ３ (4a) (wherein n1 represents an integer of 1 to 10, and Y ３ is -SO ３ M １ or -COOM １ represents M １ , H, NH ４ or an alkali metal.) CF ２=CF-(CF ２ C (CF ３ ) F) ｎ２ -Y ３ (4b) (wherein n2 represents an integer of 1 to 5, and Y ３ is the same as the definition above.) CF ２ =CF-O-(CFX １ ) ｎ３ -Y ３ (4c) (wherein, X １ is F or CF ３ n3 represents an integer of 1 to 10; Y ３ is the same as the definition above.) CF ２ =CF-O-(CF ２ CFX １ O) ｎ４ -CF ２ CF ２ -Y ３ (4d) (wherein n4 represents an integer of 1 to 10, and Y ３ and X １ is the same as the above definition.) CX ２ ２ =CFCF ２ -O-(CF(CF ３ )CF ２ O) ｎ５ -CF (CF ３ )-Y ３ (4e) (In the formula, each ２ are the same and represent F or H. n5 represents 0 or an integer of 1 to 10, Y ３ is the same as defined above.) Examples of the alkali metal include Na and K.

[0060] In the formula (4a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. ３ is advantageous in that it can provide adequate water solubility and surface activity. １ Preferably, M １ is preferred because it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0061] Examples of the perfluorovinyl alkyl compound represented by the formula (4a) include CF２ =CFCF ２ COOM １ (In the formula, M １ is the same as the definition above.

[0062] In the formula (4b), n2 is preferably an integer of 3 or less from the viewpoint of emulsifying ability, and Y ３ is preferred in that it provides adequate water solubility and surface activity. １ Preferably, M １ is preferred because it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0063] In the formula (4c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y ３ is preferred in that it provides adequate water solubility and surface activity. １ It is preferable that the above M １ is H or NH in that dispersion stability is improved. ４ It is preferable that:

[0064] In the formula (4d), the X １ In terms of surfactant activity, -CF ３ In terms of water solubility, n4 is preferably an integer of 5 or less, and Y ３ COOM has the advantage of providing adequate water solubility and surface activity. １ It is preferable that the above M １ is H or NH ４ It is preferable that:

[0065] Examples of the perfluorovinyl ether compound represented by the formula (4d) include CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOM １ (In the formula, M １ , H, NH ４ or an alkali metal.

[0066] In the formula (4e), n5 is preferably 0 or an integer of 1 to 5, more preferably 0, 1 or 2, and even more preferably 0 or 1, in terms of emulsifying ability. ３ COOM has the advantage of providing adequate water solubility and surface activity. １ It is preferable that the above M １ is preferred in that it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved. ４ It is preferable that:

[0067] Examples of the perfluorovinyl alkyl compound represented by the formula (4e) include CH ２ =CFCF ２ OCF (CF ３ ) COOM １ , C.H. ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM １ (In the formula, M １ is the same as the definition above.

[0068] As the modified monomer, from the viewpoint of obtaining a composite sheet having lower resistance and further improving powder fluidity, at least one selected from the group consisting of HFP, CTFE, PAVE, PFAE, and a monomer having a polar group is preferred, and at least one selected from the group consisting of HFP, CTFE, perfluoro(methyl vinyl ether) [PMVE], perfluoro(propyl vinyl ether) [PPVE], PFBE, a non-fluorinated monomer having an acid anhydride residue, and the modified monomer (A) is more preferred, and at least one selected from the group consisting of HFP, CTFE, PMVE, PPVE, a cyclic non-fluorinated monomer having an acid anhydride residue, and a compound represented by general formula (4e) is even more preferred, and at least one selected from the group consisting of HFP, CTFE, and PPVE is even more preferred, and HFP is even more preferred.

[0069] The TFE-based polymer is preferably at least one selected from the group consisting of a TFE homopolymer and a modified PTFE containing TFE units and polymerization units based on HFP, and more preferably at least one selected from the group consisting of a TFE homopolymer and a modified PTFE consisting only of TFE units and polymerization units based on HFP.

[0070] The TFE polymer may have a core-shell structure.As the TFE polymer having a core-shell structure, for example, there can be mentioned a TFE polymer that contains a core of a high molecular weight TFE polymer in particles and a shell of a lower molecular weight TFE polymer or TFE copolymer.Also, there can be mentioned modified PTFE that contains a core of a high molecular weight PTFE in particles and a shell of a lower molecular weight PTFE or modified PTFE.As such modified PTFE, for example, there can be mentioned the PTFE described in JP-A-2005-527652.

[0071] Preferably, above-mentioned TFE polymer is non-melt processable.In this specification, non-melt processable means that melt flow rate (MFR) is less than 0.25g / 10min, preferably less than 0.10g / 10min, more preferably 0.05g / 10min or less, even more preferably 0.01g / 10min or less.Above-mentioned MFR is the value (g / 10min) of the polymer mass that flows out per 10 minutes from a nozzle with an inner diameter of 2.095mm and a length of 8mm according to ASTM D1238, at 372 ℃ and a load of 5kg, using a melt indexer.

[0072] The TFE polymer may have a 0.1% mass loss temperature of 400°C or less. A TFE polymer having a 0.1% mass loss temperature of 400°C or less can be obtained by using a hydrocarbon surfactant. The 0.1% mass loss temperature is a value measured by the following method. Approximately 10 mg of a TFE polymer that has not been heated to a temperature of 300°C or higher is precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (differential thermal / thermogravimetric simultaneous analyzer). The 0.1% mass loss temperature is determined as the temperature at which a weight loss of 0.1 mass% occurs when the aluminum pan is heated in an air atmosphere in a temperature range from 25°C to 600°C at a rate of 10°C / min.

[0073] The TFE polymer may have a 1.0% mass loss temperature of 492°C or less. A TFE polymer having a 1.0% mass loss temperature of 492°C or less can be obtained by using a hydrocarbon surfactant. The 1.0% mass loss temperature is a value measured by the following method. Approximately 10 mg of a TFE polymer that has not been heated to a temperature of 300°C or higher is precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (differential thermal / thermogravimetric simultaneous analysis) apparatus. The 1.0% mass loss temperature is determined as the temperature at which a weight loss of 1.0 mass% occurs when the aluminum pan is heated in an air atmosphere in a temperature range from 25°C to 600°C at a rate of 10°C / min.

[0074] The TFE polymer may have a thermal instability index (TII) of 20 or more. A TFE polymer having a TII of 20 or more can be obtained by using a hydrocarbon surfactant. The TII is preferably 25 or more, more preferably 30 or more, even more preferably 35 or more, and particularly preferably 40 or more. The TII is also preferably 50 or less. The TII is measured in accordance with ASTM D 4895-89.

[0075] The content of the TFE polymer is 10% by mass or more relative to the solid content in the TFE polymer composition.From the viewpoint of obtaining a composite sheet with lower resistance and further improving powder flowability, it is preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, particularly preferably 55% by mass or more, and also preferably 99% by mass or less, more preferably 96% by mass or less, more preferably 91% by mass or less, more preferably 85% by mass or less, more preferably 80% by mass or less, more preferably 75% by mass or less, particularly preferably 70% by mass or less.In the present disclosure, the amount of solid content in the TFE polymer composition is the value obtained by drying 1g of the TFE polymer composition in a blower dryer under the conditions of 150 ℃ and 60 minutes, and expressing the mass ratio of heating residue to the mass (1g) of the TFE polymer composition as a percentage.

[0076] The TFE-based polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (1) (hereinafter also referred to as compound (1)) and a compound represented by the following general formula (2) (hereinafter also referred to as compound (2)). General formula (1): (H—(CF ２ ) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ ) ｎ -SO ３ ) ｑ M ２ (wherein n is 4 to 20. M ２ is H, metal atom, NR ５ ４ (R５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0077] The above M １ and M ２ The metal atom as R may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), and specific examples thereof include Na, K, and Li. ５ may be the same or different. ５ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms. ５ The organic group as the aryl group is preferably an organic group containing no fluorine.

[0078] In general formula (1), m is preferably 6 or more, more preferably 8 or more, even more preferably 11 or more, even more preferably 13 or more, particularly preferably 15 or more, and is preferably 18 or less, more preferably 16 or less. In general formula (2), n is preferably 6 or more, more preferably 8 or more, even more preferably 11 or more, even more preferably 13 or more, particularly preferably 15 or more, and is preferably 18 or less, more preferably 16 or less.

[0079] The TFE polymer composition of the present disclosure may contain one or more types of compound (1), but may also contain two or more types, or may also contain three or more types.

[0080] When the TFE polymer composition of the present disclosure comprises compound (1), the content of compound (1) (when two or more exist, the content of each component) can be 10 mass ppm or less with respect to the TFE polymer composition, preferably be 5000 mass ppb or less, more preferably be 1000 mass ppb or less, more preferably be 500 mass ppb or less, more preferably be 150 mass ppb or less, more preferably be 100 mass ppb or less, more preferably be 50 mass ppb or less, more preferably be 25 mass ppb or less, particularly preferably be 10 mass ppb or less.Lower limit is not particularly limited, but can be 0.1 mass ppb, can be 1 mass ppb, can be 10 mass ppb, can be 15 mass ppb.

[0081] The TFE polymer composition of the present disclosure may contain one or more types of compound (2), but may also contain two or more types, or may also contain three or more types.

[0082] When the TFE polymer composition of the present disclosure comprises compound (2), the content of compound (2) (when two or more exist, the content of each component) can be 10 mass ppm or less relative to the TFE polymer composition, preferably be 5000 mass ppb or less, more preferably be 1500 mass ppb or less, more preferably be 1000 mass ppb or less, more preferably be 500 mass ppb or less, more preferably be 100 mass ppb or less, more preferably be 50 mass ppb or less, more preferably be 25 mass ppb or less, more preferably be 10 mass ppb or less, more preferably be 1 mass ppb or less, more preferably be 1 mass ppb or less, more preferably be less than 1 mass ppb, and particularly preferably be less than the lower limit of quantification.Lower limit is not particularly limited, and can be the amount less than the lower limit of quantification.

[0083] The TFE polymer composition containing compound (1) and / or (2) can be obtained by using a hydrocarbon surfactant. The TFE polymer composition of the present disclosure may contain a hydrocarbon surfactant in addition to the TFE polymer and compound (1) and / or (2). The content of the hydrocarbon surfactant in the TFE polymer composition is not particularly limited, but is usually 100 ppm by mass to 10% by mass. In the hydrocarbon surfactant, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0084] The TFE polymer composition of the present disclosure preferably does not substantially contain a compound represented by the following general formula (3) (hereinafter also referred to as compound (3)). General formula (3): (H—(CF ２ ) ８ -SO ３ ) ｑ M ２ (In the formula, M ２ is H, metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms (preferably an organic group not containing fluorine), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent; and q is 1 or 2.

[0085] "Substantially not containing compound (3)" means that the content of compound (3) is 25 mass ppb or less relative to the TFE polymer composition.The content of compound (3) is preferably 20 mass ppb or less relative to the TFE polymer composition, more preferably 15 mass ppb or less, and even more preferably 10 mass ppb or less.The lower limit is not particularly limited, but may be 0 mass ppb, 0.1 mass ppb, or 1 mass ppb.

[0086] The TFE polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (4) (hereinafter also referred to as compound (4)) and a compound represented by the following general formula (4') (hereinafter also referred to as compound (4')), and the content of each of these compounds is preferably 1000 mass ppb or less relative to the TFE polymer composition. ２ ) １５ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms (preferably an organic group not containing fluorine)), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (4'): (H-(CF ２ ) １６ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. p is 1 or 2.

[0087] When the TFE polymer composition of the present disclosure comprises compound (4), the content of compound (4) is more preferably 500 mass ppb or less relative to above-mentioned TFE polymer composition, more preferably 250 mass ppb or less, more preferably 150 mass ppb or less, more preferably 100 mass ppb or less, more preferably 50 mass ppb or less, more preferably 25 mass ppb or less, more preferably 15 mass ppb or less, particularly preferably 10 mass ppb or less.Lower limit is not particularly limited, but can be 0.1 mass ppb, can be 1 mass ppb, can be 20 mass ppb, can be 50 mass ppb.

[0088] When the TFE polymer composition of the present disclosure comprises compound (4 '), the content of compound (4 ') is more preferably 500 mass ppb or less, more preferably 250 mass ppb or less, more preferably 150 mass ppb or less, more preferably 100 mass ppb or less, more preferably 50 mass ppb or less, more preferably 25 mass ppb or less, more preferably 15 mass ppb or less, particularly preferably 10 mass ppb or less.The lower limit is not particularly limited, but can be 0.1 mass ppb, can be 1 mass ppb, can be 20 mass ppb, can be 50 mass ppb.

[0089] The TFE polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (5) (hereinafter also referred to as compound (5)) and a compound represented by the following general formula (5') (hereinafter also referred to as compound (5')), and the content of each of these compounds is preferably 1000 mass ppb or less relative to the TFE polymer composition. ２ ) １３ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５may be the same or different and are H or an organic group having 1 to 10 carbon atoms (preferably an organic group not containing fluorine)), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (5'): (H-(CF ２ ) １４ -COO) ｐ M １ (In the formula, M １ represents H, a metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. p is 1 or 2.

[0090] When the TFE polymer composition of the present disclosure comprises compound (5), the content of compound (5) is more preferably 500 mass ppb or less, more preferably 250 mass ppb or less, more preferably 100 mass ppb or less, more preferably 50 mass ppb or less, more preferably 25 mass ppb or less, more preferably 15 mass ppb or less, particularly preferably 10 mass ppb or less.Lower limit is not particularly limited, but can be 0.1 mass ppb, can be 1 mass ppb, can be 10 mass ppb.

[0091] When the TFE polymer composition of the present disclosure comprises compound (5 '), the content of compound (5 ') is more preferably 500 mass ppb or less, more preferably 250 mass ppb or less, more preferably 100 mass ppb or less, more preferably 50 mass ppb or less, more preferably 25 mass ppb or less, more preferably 15 mass ppb or less, particularly preferably 10 mass ppb or less, relative to the TFE polymer composition.The lower limit is not particularly limited, but can be 0.1 mass ppb, can be 1 mass ppb, or can be 10 mass ppb.

[0092] The contents of compounds (1), (2), (3), (4), (4'), (5) and (5') are values ​​measured using liquid chromatography mass spectrometry as described in the Examples below.

[0093] As the conductive carbon material in the TFE-based polymer composition of the present disclosure, any known material can be used.Specific examples include graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, needle coke, carbon nanotube, carbon nanohorn, carbon nanofiber, fullerene and graphene, amorphous carbon such as VGCF, and other carbon materials.Acetylene black, VGCF, and carbon nanotube are particularly preferred.As carbon nanotube, multi-walled carbon nanotube is particularly preferred.It should be noted that these materials can be used alone, or two or more can be used in any combination and ratio.

[0094] Examples of commercially available carbon black include Toka Black #4300, #4400, #4500, #5500, etc. (furnace black, manufactured by Tokai Carbon Co., Ltd.), Printex L, etc. (furnace black, manufactured by Degussa), Raven 7000, 5750, 5250, 5000ULTRAIII, 5000ULTRA, etc., Conductex SC ULTRA, Conductex 975ULTRA, etc., PUER BLACK 100, 115, 205, etc. (furnace blacks manufactured by Colombian Chemical), #2350, #2400B, #2600B, #30050B, #3030B, #3230B, #3350B, #3400B, #5400B, etc. (furnace blacks manufactured by Mitsubishi Chemical Corporation), MONARCH 1400, 1300, 900, Vulcan XC-72R, BlackPearls 2000, LITX-50, LITX-200, etc. (furnace blacks manufactured by Cabot Corporation), Ensaco 250G, Ensaco 260G, Ensaco 350G, Super-P Examples of suitable carbon blacks include Li (furnace black, manufactured by IMERYS), Ketjenblack ECP, ECP-600JD, Lionite CB, etc. (Ketjenblack, manufactured by Lion Specialty Chemicals), Denkablack HS-100, Li-100, Li-200, Li-250, Li-400, and FX-35 (acetylene black, manufactured by Denka Co., Ltd.). The purity of the carbon black is preferably such that the fixed carbon content is 99.00% by mass or more, and more preferably 99.50% by mass or more. The ash content is preferably 0.50% by mass or less, and more preferably 0.30% by mass or less. Examples of commercially available VGCF include VGCF-H (manufactured by Showa Denko K.K.). Examples of commercially available multi-walled carbon nanotubes include FT7000 (manufactured by CNano Corporation). The multi-walled carbon nanotubes preferably have an average outer diameter of 4 nm to 20 nm, more preferably 6 nm to 12 nm, an average fiber length of 1 to 30 μm, more preferably 3 μm to 20 μm, and a specific surface area of ​​10 to 800 m. ２ / g, and 100 to 400m ２ / g is more preferable. This makes it possible to obtain good electrical conductivity.

[0095] The content of the conductive carbon material is preferably 1% by mass or more, more preferably 4% by mass or more, even more preferably 9% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, particularly preferably 30% by mass or more, and may be less than 100% by mass, preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, particularly preferably 45% by mass or less, in terms of obtaining a composite sheet with lower resistance and further improving powder fluidity.

[0096] The total amount of the TFE-based polymer and the conductive carbon material is preferably 11% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, and may be less than 100% by mass, 90% by mass or less, or 80% by mass or less, based on the solid content of the TFE-based polymer composition.

[0097] The TFE polymer composition of the present disclosure may contain other components as necessary.The other components include polymers other than the above-mentioned TFE polymers, conductive materials other than carbon materials, dispersants, thickeners, etc.For example, as thickeners, celluloses such as carboxymethyl cellulose (CMC) and methyl cellulose (MC) can be suitably used.

[0098] The TFE-based polymer composition of the present disclosure may be free of an electrode active material and a solid electrolyte.

[0099] The TFE-based polymer composition of the present disclosure is preferably substantially free of water. This can suppress gas generation and deterioration of electrochemical device properties. Furthermore, a wide range of electrode active materials and solid electrolytes can be combined, which is advantageous in terms of production processes. Being substantially free of water means that the water content of the TFE-based polymer composition is 0.050% by mass or less. The water content is preferably 0.030% by mass or less, more preferably 0.010% by mass or less, even more preferably 0.005% by mass or less, even more preferably 0.003% by mass or less, even more preferably 0.002% by mass or less, and particularly preferably 0.001% by mass or less. The water content is measured by the following method. The mass of the TFE-based polymer composition is measured before and after heating at 150°C for 2 hours, and calculated according to the following formula. A sample is taken three times, and after each calculation, the average is calculated and the average value is adopted. Water content (mass%)=[(mass (g) of TFE polymer composition before heating)−(mass (g) of TFE polymer composition after heating)] / (mass (g) of TFE polymer composition before heating)×100

[0100] The TFE polymer composition of the present disclosure preferably does not substantially contain the fluorine-containing compound with molecular weight of 1000 or less.The above-mentioned "does not substantially contain fluorine-containing compound" means that the amount of the above-mentioned fluorine-containing compound is 25 mass ppb or less relative to the TFE polymer composition.The amount of the above-mentioned fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, even more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, even more preferably 1 mass ppb or less, even more preferably less than 1 mass ppb, and particularly preferably less than the lower limit of quantification.The lower limit is not particularly limited, and may be an amount less than the lower limit of quantification.

[0101] The amount of the fluorine-containing compound having a molecular weight of 1,000 or less is measured by the following method. 1 g of sample is weighed, 10 g (12.6 ml) of methanol is added, and ultrasonic treatment is performed for 60 minutes to obtain an extract. The obtained extract is concentrated using a nitrogen purge as appropriate, and the fluorine-containing compounds in the concentrated extract are measured by LC / MS / MS. Molecular weight information is extracted from the obtained LC / MS spectrum, and a match with the structural formula of the candidate fluorine-containing compound is confirmed. Aqueous solutions with five or more levels of content of the standard substance are prepared, and LC / MS analysis is performed on the aqueous solutions with each content. The relationship between the content and the area area relative to that content is plotted, and a calibration curve is drawn. Using the calibration curve, the area area of ​​the LC / MS chromatogram of the fluorine-containing compound in the extract is converted to the content of the fluorine-containing compound. The lower limit of quantitation in this measurement method is 10 ppb by mass.

[0102] The fluorine-containing compound having a molecular weight of 1000 or less can be exemplified by a fluorine-containing compound having a hydrophilic group with a molecular weight of 1000 g / mol or less.The molecular weight of the fluorine-containing compound is preferably 800 or less, more preferably 500 or less.The polymer particles obtained by polymerization in the presence of a fluorine-containing surfactant usually contain a fluorine-containing surfactant in addition to a TFE-based polymer.In this specification, the fluorine-containing surfactant is used during polymerization.The fluorine-containing compound having a molecular weight of 1000 or less may be a compound that is not added during polymerization, for example, a compound that is by-produced during polymerization.In addition, when the fluorine-containing compound having a molecular weight of 1000 or less contains an anionic moiety and a cationic moiety, it means a compound containing fluorine, the molecular weight of which of the anionic moiety is 1000 or less.The fluorine-containing compound having a molecular weight of 1000 or less does not include a TFE-based polymer.

[0103] Examples of the hydrophilic group include -COOM and -SO ２ M or -SO ３ M, -COOM, -SO ３ M (in each formula, M is H, a metal atom, NR １ ４, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １ is H or an organic group.

[0104] As the fluorine-containing surfactant, a surfactant containing fluorine (anionic fluorine-containing surfactant) in which the molecular weight of the anionic part is 1000 or less can also be used. The "anionic part" means the part of the fluorine-containing surfactant excluding the cation. For example, F(CF ２ ) ｎ１ In the case of COOM, "F(CF ２ ) ｎ１ The anionic fluorine-containing surfactant is a surfactant represented by the following general formula (N ０ ): X ｎ０ -Rf ｎ０ -Y ０ (N ０ ) (wherein, 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 are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H atoms may be substituted with Cl. ０ is an anionic group. ０ The anionic group is -COOM, -SO ２ M or -SO ３ M, -COOM or -SO ３ M. M may be H, a metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １ is H or an organic group. The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., such as Na, K, or Li. １ As the group, H or C １－１０ and may be an organic group of the formula: １－４and may be an organic group of the formula: １－４ M may be H, a metal atom, or an alkyl group of the formula NR １ ４ may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR １ ４ may be H, Na, K, Li or NH ４ The above Rf ｎ０ may be one in which 50% or more of H is substituted with fluorine.

[0105] The above fluorine-containing surfactant may be one type of fluorine-containing surfactant or a mixture containing two or more types of fluorine-containing surfactants.

[0106] Examples of the fluorine-containing surfactant include compounds represented by the following formula: F(CF ２ ) ７ COOM, F(CF ２ ) ５ COOM, C.F. ３ O (CF ２ ) ３ OCHFCF ２ COOM, C. ３ F ７ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ CF ２ OCF (CF ３ ) COOM, C.F. ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C ２ F ５ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ３ OCF (CF ３ )CF ２ OCF (CF ３ ) COOM, C.F. ２ ClCF ２CF ２ OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF ２ CF ２ OCF ２ CF (CF ３ ) OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF (CF ３ )CF ２ OCF ２ COOM, C.F. ２ ClCF(CF ３ ) OCF ２ CF (CF ３ ) OCF ２ COOM, and (In each formula, M is H, metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. １ is H or an organic group.) The TFE-based polymer composition of the present disclosure is preferably substantially free of any of the fluorine-containing compounds represented by the above formulas.

[0107] In each of the above formulas, M is H, a metal atom, or NR １ ４ may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR １ ４ may be H, Na, K, Li or NH ４ R １ is H or C １－１０ and may be an organic group of the formula: １－４ and may be an organic group of the formula: １－４ The alkyl group may be:

[0108] If the TFE polymer composition of the present disclosure does not substantially contain any of the fluorine-containing compounds represented by the above formula, it can further suppress gas generation and the deterioration of electrochemical device properties.Does not substantially contain any of the fluorine-containing compounds represented by the above formula means that the amount of the fluorine-containing compound is 25 mass ppb or less relative to the TFE polymer composition.The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, even more preferably 1 mass ppb or less, even more preferably less than 1 mass ppb, and particularly preferably less than the lower limit of quantification.The lower limit is not particularly limited, and can be an amount less than the lower limit of quantification.

[0109] The TFE-based polymer composition of the present disclosure has the following general formula: ｎ－１ F ２ｎ－１ COO － ]M ＋ (wherein n is an integer of 9 to 14, preferably an integer of 9 to 12; M ＋ It is also preferable that the composition is substantially free of a fluorine-containing compound represented by the formula (I). This makes it possible to further suppress gas generation and deterioration of the electrochemical device properties. ＋ The M constituting the formula is the same as the above-mentioned M. Substantially not containing the fluorine-containing compound represented by the formula means that the amount of the fluorine-containing compound is 25 mass ppb or less relative to the TFE-based polymer composition. The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, even more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, even more preferably 1 mass ppb or less, even more preferably less than 1 mass ppb, and particularly preferably less than the lower limit of quantification. The lower limit is not particularly limited, and may be an amount less than the lower limit of quantification.

[0110] The TFE-based polymer composition of the present disclosure may have a thermal instability index (TII) of 5 or more, preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, and preferably 30 or less. The TII is measured in accordance with ASTM D 4895-89.

[0111] The TFE polymer composition of the present disclosure can form a composite sheet with more excellent strength, so that the endothermic peak temperature is preferably 333°C or higher, more preferably 335°C or higher, even more preferably 337°C or higher, even more preferably 340°C or higher, and preferably 350°C or lower, more preferably 346°C or lower.The endothermic peak temperature is the temperature corresponding to the minimum point in the heat of fusion curve obtained by carrying out differential scanning calorimetry (DSC) at a heating rate of 10°C / min for the TFE polymer composition that has no history of being heated to a temperature of 300°C or higher.When there are two or more minimum points in one melting peak, each of them is regarded as the endothermic peak temperature.

[0112] The TFE polymer composition of the present disclosure preferably has a melting point of 315° C. or higher, more preferably 320° C. or higher, even more preferably 323° C. or higher, even more preferably 325° C. or higher, and preferably 335° C. or lower, more preferably 330° C. or lower, in order to form a composite sheet having even greater strength. The melting point is the temperature corresponding to the minimum point in the heat of fusion curve obtained by carrying out differential scanning calorimetry (DSC) at a heating rate of 10° C. / min on a TFE polymer composition that has a history of being heated to a temperature of 300° C. or higher.

[0113] The TFE polymer composition of the present disclosure can form a composite sheet having better strength, so that its standard specific gravity (SSG) is preferably 2.280 or less, more preferably 2.250 or less, even more preferably 2.220 or less, even more preferably 2.200 or less, even more preferably 2.190 or less, especially preferably 2.180 or less, and particularly preferably 2.170 or less.The SSG is also preferably 2.130 or more.The SSG is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895 89.

[0114] The TFE polymer composition of the present disclosure can have an average secondary particle diameter of 350 μ m or more, preferably 400 μ m or more, more preferably 450 μ m or more, even more preferably 500 μ m or more, even more preferably 550 μ m or more, particularly preferably 600 μ m or more, and also preferably 1000 μ m or less, more preferably 900 μ m or less, even more preferably 800 μ m or less, even more preferably 700 μ m or less.Above-mentioned average secondary particle diameter is measured in accordance with JIS K 6891.

[0115] In terms of excellent handling, the TFE polymer composition of the present disclosure can have an average aspect ratio of 2.0 or less, preferably 1.8 or less, more preferably 1.7 or less, more preferably 1.6 or less, more preferably 1.5 or less, more preferably 1.4 or less, particularly preferably 1.3 or less, particularly preferably 1.2 or less, and most preferably 1.1 or less.Above-mentioned average aspect ratio can also be 1.0 or more.Above-mentioned average aspect ratio is obtained by observing TFE polymer composition with scanning electron microscope (SEM), carrying out image processing for 200 or more particles randomly selected, and averaging the ratio of long diameter to short diameter thereof.

[0116] In terms of excellent handling, the TFE polymer composition of the present disclosure has apparent density of preferably 0.40g / ml or more, more preferably 0.43g / ml or more, even more preferably 0.45g / ml or more, even more preferably 0.48g / ml or more, and particularly preferably 0.50g / ml or more.The upper limit is not particularly limited, but can be 0.70g / ml.Above-mentioned apparent density is measured in accordance with JIS K 6892.

[0117] The form of the TFE polymer composition of the present disclosure is not limited, but is preferably powder, because it can be mixed with electrode active material or solid electrolyte without using a large amount of dispersion medium.It should be noted that the above-mentioned TFE polymer composition can also be in the form other than powder, for example, can be dispersion liquid or molding.As molding, for example, sheet, pellet, rod etc. can be mentioned.

[0118] The TFE-based polymer composition of the present disclosure can be produced by mixing a TFE-based polymer with a conductive carbon material. Mixing the TFE-based polymer with the conductive carbon material before mixing with an electrode active material or a solid electrolyte improves the dispersibility of the TFE-based polymer. This allows the TFE-based polymer and the conductive carbon material to be uniformly dispersed when mixed with an electrode active material or a solid electrolyte to prepare a composite, thereby improving resistance and other electrochemical device properties. Although the details of the principle are unclear, it is believed that by creating a mixed state of the TFE-based polymer and the conductive carbon material in advance, fibrils are generated while the soft TFE-based polymer is dispersed when mixed with the electrode active material or the solid electrolyte, and at the same time, the conductive carbon material can be efficiently dispersed. If the TFE-based polymer and the conductive carbon material are added separately without being mixed in advance, the polymer disperses preferentially, resulting in insufficient dispersion of the conductive carbon material.

[0119] The method for producing the TFE polymer composition of the present disclosure is not particularly limited, and can be produced by any method, among which the method for producing can be suitably carried out by the method comprising the step (A) of mixing TFE polymer and conductive carbon material in the presence of liquid medium.In this case, the method of adding powdery conductive carbon material into the liquid dispersion of TFE polymer and mixing, the method of mixing the liquid dispersion of TFE polymer and the liquid dispersion of conductive carbon material, etc. can be mentioned.Mixing can be carried out by a general method.For example, mixers such as disperser, homomixer, planetary mixer, homogenizer, wet jet mill, etc. can be mentioned, but are not limited thereto.

[0120] In the step (A), a dispersion containing a TFE-based polymer, a conductive carbon material, and a liquid medium is used. In such a dispersion, the total amount of the TFE-based polymer and the conductive carbon material is preferably 1 to 60% by mass relative to the total amount of the TFE-based polymer, the conductive carbon material, and the liquid medium. The lower limit is more preferably 2% by mass, and even more preferably 3% by mass. The upper limit is more preferably 50% by mass, and even more preferably 30% by mass.

[0121] Mixing them in a liquid medium is preferred because it allows the TFE-based polymer and the conductive carbon material to be mixed with high uniformity. The liquid medium used in such mixing is preferably water.

[0122] In this case, the TFE polymer used as the raw material is preferably an aqueous dispersion obtained by emulsion polymerization.

[0123] The aqueous dispersion of the TFE polymer can be produced, for example, by a production method including a step of emulsion-polymerizing TFE in an aqueous medium in the presence of a hydrocarbon surfactant.

[0124] In the hydrocarbon surfactant, the proportion of hydrogen atoms bonded to carbon atoms that are substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms at all).

[0125] The hydrocarbon surfactant is preferably a carboxylic acid type hydrocarbon surfactant. The carboxylic acid type hydrocarbon surfactant is not limited as long as it has a carboxy group (—COOH) or a group in which the hydrogen atom of the carboxy group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.), and for example, a hydrocarbon surfactant having a carboxy group or a group in which the hydrogen atom of the carboxy group is substituted with an inorganic cation can be used from among the specific hydrocarbon surfactants described below and other compounds having surface activity.

[0126] The hydrocarbon surfactant is preferably a sulfonic acid hydrocarbon surfactant. ３ H group, -OSO ３ The surfactant is not limited as long as it has an H group or a group in which the hydrogen atom of such a group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.), and examples thereof include —SO ３ H group, -OSO ３ Hydrocarbon surfactants having an H group or a group in which the hydrogen atom of such a group is substituted with an inorganic cation can be used.

[0127] The hydrocarbon surfactant is preferably water-soluble in view of improving emulsification performance. The hydrocarbon surfactant being water-soluble means that the maximum concentration in water at which the hydrocarbon surfactant dissolves at 85°C is 100 mass ppm or more. The maximum concentration in water is preferably 500 mass ppm or more, more preferably 1000 mass ppm or more, even more preferably 2000 mass ppm or more, even more preferably 3000 mass ppm or more, even more preferably 5000 mass ppm or more, even more preferably 1 mass% or more, even more preferably 3 mass% or more, even more preferably 5 mass% or more, particularly preferably 10 mass% or more, and may be 50 mass% or less.

[0128] The emulsion polymerization preferably includes a step of carrying out emulsion polymerization of tetrafluoroethylene alone, or emulsion polymerization of tetrafluoroethylene and a modified monomer copolymerizable with tetrafluoroethylene, in an aqueous medium in the presence of a specific hydrocarbon surfactant, and a step of continuously adding the specific hydrocarbon surfactant in the above step.

[0129] The continuous addition of a specific hydrocarbon surfactant means, for example, adding the specific hydrocarbon surfactant over time, without interruption, or in portions, rather than all at once. The specific hydrocarbon surfactant is, for example, a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxy groups), or a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxy groups) that has been subjected to radical treatment or oxidation treatment. The radical treatment may be any treatment that generates radicals in a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxy groups). For example, the radical treatment may be a treatment in which deionized water and a hydrocarbon surfactant are added to a reactor, the reactor is sealed, the system is purged with nitrogen, the reactor is heated and pressurized, a polymerization initiator is added, the mixture is stirred for a certain period of time, and the reactor is depressurized to atmospheric pressure and then cooled. Above-mentioned oxidation treatment is the treatment that oxidizing agent is added to hydrocarbon surfactant that has one or more carbonyl groups (but excluding the carbonyl group in carboxyl group).As oxidizing agent, for example, oxygen, ozone, hydrogen peroxide water, manganese oxide (IV), potassium permanganate, potassium dichromate, nitric acid, sulfur dioxide etc. can be enumerated.By above-mentioned production method, even if no conventional fluorine-containing surfactant is used, it is possible to produce TFE polymer that has the same molecular weight as that of the production method that uses conventional fluorine-containing surfactant.

[0130] In the above-mentioned production method, the step of continuously adding the specific hydrocarbon surfactant is preferably that when the solid content of the TFE polymer formed in aqueous medium is less than 0.60 mass%, the hydrocarbon surfactant is started to be added into aqueous medium.When the solid content is 0.5 mass% or less, the specific hydrocarbon surfactant is preferably started to be added into aqueous medium.When the solid content is 0.3 mass% or less, the specific hydrocarbon surfactant is more preferably started to be added when the solid content is 0.2 mass% or less, even more preferably started to be added when the solid content is 0.1 mass% or less, and particularly preferably started to be added at the start of polymerization.The solid content is the concentration relative to the total of aqueous medium and TFE polymer.

[0131] In the step of continuously adding the specific hydrocarbon surfactant, the amount of the specific hydrocarbon surfactant added is preferably 0.01 to 10% by mass relative to 100% by mass of the aqueous medium, more preferably 0.05% by mass at the lower limit, even more preferably 0.1% by mass at the lower limit, more preferably 5% by mass at the upper limit, and even more preferably 1% by mass at the upper limit.

[0132] In the process of emulsion polymerization of tetrafluoroethylene alone or emulsion polymerization of tetrafluoroethylene and a modified monomer copolymerizable with tetrafluoroethylene in an aqueous medium in the presence of the specific hydrocarbon surfactant, the amount of the specific hydrocarbon surfactant is preferably large, and is preferably 0.0001 to 10 mass% relative to 100 mass% of the aqueous medium.A more preferred lower limit is 0.001 mass%, and a more preferred upper limit is 1 mass%.If it is less than 0.0001 mass%, the dispersing force may be insufficient, and if it exceeds 10 mass%, the effect commensurate with the amount cannot be obtained, and instead, the polymerization rate may decrease or the reaction may stop.The amount of the specific hydrocarbon surfactant is appropriately determined depending on the type of monomer used, the molecular weight of the target TFE polymer, etc.

[0133] The specific hydrocarbon surfactants include those represented by the formula: R-X (wherein R is a fluorine-free organic group having 1 to 2000 carbon atoms and one or more carbonyl groups (excluding carbonyl groups in carboxy groups), and X is -OSO ３ X １ , -COOX １ or -SO ３ X １ (X １ represents H, a metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １ is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. )) and at least one selected from the group consisting of surfactants (e) described below are preferred. R preferably has 500 or less carbon atoms, more preferably 100 or less, even more preferably 50 or less, and even more preferably 30 or less. The specific hydrocarbon surfactant is preferably a surfactant represented by the following formula (a): (In the formula, R １ａ is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond (preferably an organic group not containing fluorine), and when it has 2 or more carbon atoms, it may contain a carbonyl group, and when it has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ａ and R ３ａ are independently a single bond or a divalent linking group. １ａ , R ２ａ and R ３ａ has a total of 6 or more carbon atoms. ａ represents H, a metal atom, NR ４ａ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ａare H or organic groups (preferably fluorine-free organic groups), and may be the same or different. １ａ , R ２ａ and R ３ａ any two of which may be bonded to each other to form a ring; a surfactant (a) represented by the following formula (b): (In the formula, R １ｂ R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｂ and R ４ｂ are independently H or a substituent. ３ｂ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. n is an integer of 1 or more. p and q are independently integers of 0 or more. X ｂ represents H, a metal atom, NR ５ｂ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｂ are H or organic groups (preferably fluorine-free organic groups), and may be the same or different. １ｂ , R ２ｂ , R ３ｂ and R ４ｂ Any two of the groups may be bonded to each other to form a ring. L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｂ -B-*, -NR ６ｂ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｂ -B-, -NR ６ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｂ is H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. * represents -OSO ３ X ｂ (b) a surfactant represented by the following formula (c): (In the formula, R １ｃ is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond (preferably an organic group not containing fluorine), and when it has 2 or more carbon atoms, it may contain a carbonyl group, and when it has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｃ and R ３ｃ are independently a single bond or a divalent linking group. １ｃ , R ２ｃ and R ３ｃ has a total of 5 or more carbon atoms. ｃ Ha, -COOX ｃ or -SO ３ X ｃ (X ｃ represents H, a metal atom, NR ４ｃ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ４ｃ R is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. １ｃ , R ２ｃ and R ３ｃ any two of which may be bonded to each other to form a ring; a surfactant (c) represented by the following formula (d): (In the formula, R １ｄ R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the alkyl group has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｄ and R ４ｄ are independently H or a substituent. ３ｄ is an alkylene group having 1 to 10 carbon atoms which may have a substituent. n is an integer of 1 or more. p and q are independently integers of 0 or more. A ｄ is -SO ３ X ｄ or -COOX ｄ (X ｄrepresents H, a metal atom, NR ５ｄ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ５ｄ R is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. １ｄ , R ２ｄ , R ３ｄ and R ４ｄ Any two of the groups may be bonded to each other to form a ring. L represents a single bond, —CO ２ -B-*, -OCO-B-*, -CONR ６ｄ -B-*, -NR ６ｄ CO-B-* or -CO- (where -CO ２ -B-, -OCO-B-, -CONR ６ｄ -B-, -NR ６ｄ (excluding the carbonyl group contained in CO—B—), B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R ６ｄ is H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. ｄ and a surfactant (d) represented by the following formula (e): (In the formula, R １ｅ ~R ５ｅ represents H or a monovalent substituent, provided that R １ｅ and R ３ｅ At least one of the groups represented by the general formula: -Y ｅ -R ６ｅ a group represented by R ２ｅ and R ５ｅ At least one of the groups represented by the general formula: -X ｅ -A ｅ or a group represented by the general formula: -Y ｅ -R ６ｅ In addition, X represents a group represented by the formula: ｅ A is the same or different in each occurrence and is a divalent linking group or bond; ｅ is the same or different in each occurrence and represents -COOM ｅ , -SO ３ M ｅ or -OSO３ M ｅ (M ｅ represents H, a metal atom, NR ７ｅ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ７ｅ is H or an organic group (preferably an organic group not containing fluorine); Y ｅ is the same or different in each occurrence and represents -S(=O) ２ -, -O-, -COO-, -OCO-, -CONR ８ｅ - and -NR ８ｅ a divalent linking group selected from the group consisting of CO—, or a bond, R ８ｅ is H or an organic group (preferably a fluorine-free organic group); R ６ｅ R may be the same or different in each occurrence and represents an alkyl group having two or more carbon atoms which may contain at least one group selected from the group consisting of a carbonyl group, an ester group, an amide group and a sulfonyl group between carbon atoms; １ｅ ~R ５ｅ Any two of the groups may be bonded to each other to form a ring.

[0134] The surfactant (a) can be produced, for example, by the production method described in WO 2020 / 022355.

[0135] The surfactant (b) can be produced, for example, by the production method described in WO 2020 / 022355.

[0136] The surfactant (c) can be produced, for example, by the production method described in WO 2020 / 022355.

[0137] The surfactant (d) can be produced, for example, by the production method described in WO 2020 / 022355.

[0138] The surfactant (e) can be produced by a known production method.

[0139] The specific hydrocarbon surfactant is also preferably a carboxylic acid hydrocarbon surfactant. The carboxylic acid hydrocarbon surfactant is not limited as long as it has a carboxy group (-COOH) or a group in which the hydrogen atom of the carboxy group is substituted with an inorganic cation (e.g., a metal atom, ammonium, etc.). For example, from the specific hydrocarbon surfactants described above, a hydrocarbon surfactant having a carboxy group or a group in which the hydrogen atom of the carboxy group is substituted with an inorganic cation can be used. In the carboxylic acid hydrocarbon surfactant, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0140] The carboxylic acid type hydrocarbon surfactant is preferably at least one selected from the group consisting of surfactant (c) represented by the above formula (c) and surfactant (d) represented by the above formula (d), which has a carboxy group (—COOH) or a group in which the hydrogen atom of the carboxy group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.).

[0141] The specific hydrocarbon surfactant is also preferably a sulfonic acid hydrocarbon surfactant. ３ H group, -OSO ３ There are no particular limitations on the surfactants as long as they have an H group or a group in which the hydrogen atom of such a group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.), and examples thereof include, among the specific hydrocarbon surfactants described above, -SO ３ H group, -OSO ３ Hydrocarbon surfactants having an H group or a group in which the hydrogen atoms of these groups have been substituted with inorganic cations can be used. In the sulfonic acid hydrocarbon surfactant, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms at all).

[0142] The TFE polymer composition of the present disclosure can be produced efficiently by using at least one of the above-mentioned specific hydrocarbon surfactants.In addition, the TFE polymer composition of the present disclosure can be produced by simultaneously using two or more of the above-mentioned specific hydrocarbon surfactants, or can be produced by simultaneously using other surfactant compounds other than the above-mentioned specific hydrocarbon surfactants, as long as they have volatility or can remain in the molded article etc. that is made of TFE polymer.

[0143] As the other compounds having surface activity, for example, those described in JP-T-2013-542308, JP-T-2013-542309, and JP-T-2013-542310 can be used.

[0144] The other surfactant compounds may be surfactants having a hydrophilic portion and a hydrophobic portion on the same molecule, such as hydrocarbon surfactants (excluding the specific hydrocarbon surfactants described above). These may be cationic, nonionic, or anionic. In the compounds described above, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0145] Cationic surfactants typically have a positively charged hydrophilic portion, such as an alkylated ammonium halide, such as an alkylated ammonium bromide, and a hydrophobic portion, such as a long-chain fatty acid. In the cationic surfactant, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0146] Anionic surfactants typically have a hydrophilic portion such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion that is a long-chain hydrocarbon portion such as an alkyl. In the anionic surfactant, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0147] Nonionic surfactants generally do not contain 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. In the nonionic surfactant, the proportion of hydrogen atoms bonded to carbon atoms that are substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0148] Other compounds having surface activity include R-L-M (wherein R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when R has 3 or more carbon atoms, it may contain a monovalent or divalent heterocycle or may form a ring; L is -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５ ４ (R ５ may be the same or different and are H or an organic group (preferably an organic group not containing fluorine)), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. ３ － is an aryl sulfonate. ５is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms. Specifically, CH ３ - (CH ２ ) ｎ -LM (wherein n is an integer of 6 to 17, and L and M are the same as above). Mixtures in which R is an alkyl group having 12 to 16 carbon atoms and L-M is sulfate or sodium dodecyl sulfate (SDS) can also be used. Other surfactant compounds include those represented by R ６ (-L-M) ２ (In the formula, R ６ is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５ is H or an organic group (preferably an organic group not containing fluorine), -ArSO ３ － is an aryl sulfonate. ) Other examples of compounds having surface activity include anionic surfactants represented by the formula: R ７ (-L-M) ３ (In the formula, R ７ is a linear or branched alkylidyne group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. ３ － , -SO３ － , -SO ４ -, -PO ３ － or -COO － and M is H, a metal atom, or NR ５ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５ is H or an organic group (preferably an organic group not containing fluorine). ３ － is an aryl sulfonate.

[0149] Examples of siloxane hydrocarbon surfactants include those described in Silicone Surfactants, R. M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of the siloxane surfactant comprises a distinct hydrophobic portion and a hydrophilic portion. The hydrophobic portion comprises one or more dihydrocarbylsiloxane units, in which 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, although these may be substituted with halogens such as fluorine; that is, the monovalent substituents on the carbon atoms of the hydrocarbyl groups are hydrogen. In the above siloxane surfactants, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is preferably 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (no substitution with fluorine atoms).

[0150] Siloxane hydrocarbon surfactants are also disclosed in US Pat. No. 6,841,616.

[0151] The other surfactant compound is preferably an anionic hydrocarbon surfactant. As the anionic hydrocarbon surfactant, those described above can be used, but for example, the following hydrocarbon surfactants can be suitably used.

[0152] Examples of the anionic hydrocarbon surfactant include those represented by the following formula (α): １００ -COOM (α) (wherein, R １００ is a monovalent organic group containing one or more carbon atoms (preferably an organic group not containing fluorine); M is H, a metal atom, NR １０１ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １０１ R is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. １０１ The organic group in R is preferably an alkyl group. １０１ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. １００ The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. １００ The number of carbon atoms in is preferably 29 or less, more preferably 23 or less. The metal atom of M includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M is H, a metal atom, or NR １０１ ４ is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR １０１ ４ is more preferred, and H, Na, K, Li or NH ４ is more preferred, and Na, K or NH ４ is even more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred.

[0153] The compound (α) may be R １０２ -COOM (in the formula, R １０２is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above. ) are also included. Specifically, CH ３ - (CH ２ ) ｎ -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0154] The anionic hydrocarbon surfactant may also be, for example, a surfactant represented by the following formula (β): １００ -SO ３ M (β) (wherein, R １００ is a monovalent organic group containing one or more carbon atoms (preferably an organic group not containing fluorine); M is H, a metal atom, NR １０１ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R １０１ R is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. １０１ The organic group in R is preferably an alkyl group. １０１ is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. １００ The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. １００ The number of carbon atoms in is preferably 29 or less, more preferably 23 or less. The metal atom of M includes alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferred. M is H, a metal atom, or NR １０１ ４is preferred, and H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR １０１ ４ is more preferred, and H, Na, K, Li or NH ４ is more preferred, Na, K or NH ４ is even more preferred, Na or NH ４ is particularly preferred, and NH ４ is most preferred.

[0155] The compound (β) is R １０２ -SO ３ M (wherein, R １０２ is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above. ) are also included. Specifically, CH ３ - (CH ２ ) ｎ -SO ３ M (wherein n is an integer of 2 to 28; M is the same as above).

[0156] The anionic hydrocarbon surfactant may be a surfactant represented by the following formula I: R-(XZ) ｎ (I) wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of groups is at least about 70%, and the hydrophobic moiety does not include a siloxane unit. Each X, which may be the same or different, represents an ionic hydrophilic moiety. Each Z, which may be the same or different, represents one or more counterions of the ionic hydrophilic moiety. n is 1 to 3.

[0157] Compound I exhibits low reactivity with polymerization initiators and / or propagating fluoropolymer radicals in emulsion polymerization of fluoromonomers.

[0158] Compound I has the following formula: (In the formula, Y ＋ is hydrogen, ammonium, quaternary ammonium, a nitrogen heterocycle, an alkali metal, or an alkaline earth metal.

[0159] Compound I has the following formula II: (In the formula, R ２’ and R ２’’’ are the same or different and are saturated or unsaturated, acyclic or cyclic aliphatic groups having 4 to 16 carbon atoms; R ２’ and R ２’’’ CH in the group ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of groups is at least about 70%, or R ２’ and R ２’’’ may be bonded to each other to form a saturated or unsaturated aliphatic ring which may contain ether or ester bonds, provided that CH ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of R groups is at least about 70%. １ is hydrogen, methoxy, ethoxy or phenoxy. ＋ is hydrogen, ammonium, quaternary ammonium, a nitrogen heterocycle, an alkali metal, or an alkaline earth metal.

[0160] As Compound II, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0161] Compound I has the following formula III: (In the formula, R ３ , R ４’ , and R ４’’are the same or different and are hydrogen or a saturated or unsaturated, acyclic or cyclic aliphatic group having 4 to 16 carbon atoms; R ３ , R ４’ , and R ４’’ CH in the group ３ , C.H. ２ and CH relative to the total of CH groups ３ The total percentage of R is at least about 70%. ３ , R ４’ , and R ４’’ At least one of R is not hydrogen; ４’ and R ４’’ is hydrogen, R ３ is not hydrogen, but R ３ is hydrogen, R ４’ and R ４’’ is not hydrogen. ＋ is hydrogen, ammonium, quaternary ammonium, a nitrogen heterocycle, an alkali metal, or an alkaline earth metal.

[0162] As the compound III, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0163] Even if the TFE polymer composition of the present disclosure does not use the above-mentioned specific hydrocarbon surfactant, it can be obtained by a production method comprising the polymerization step of obtaining TFE polymer by polymerizing only tetrafluoroethylene or tetrafluoroethylene and the modified monomer copolymerizable with the above-mentioned tetrafluoroethylene in an aqueous medium with pH 4.0 or more in the presence of hydrocarbon surfactant and polymerization initiator.Conventionally, the polymerization step for producing TFE polymer has used an acidic polymerization initiator, so the pH of the aqueous medium used in polymerization is less than 4.0.Through intensive research, the present inventors have unexpectedly found that by making the pH of the aqueous medium used for polymerization 4.0 or more, the stability of polymerization can be improved, and the TFE polymer with high molecular weight can be produced.The above-mentioned production method comprises the polymerization of only tetrafluoroethylene or tetrafluoroethylene and the modified monomer copolymerizable with the above-mentioned tetrafluoroethylene in an aqueous medium with pH 4.0 or more. The pH may be 4.0 or higher, preferably greater than 4.0, more preferably 4.5 or higher, even more preferably 5.0 or higher, even more preferably 5.5 or higher, particularly preferably 6.0 or higher, particularly preferably 6.5 or higher, particularly preferably 7.0 or higher, particularly preferably 7.5 or higher, and particularly preferably 8.0 or higher. The upper limit of the pH is not particularly limited, but may be, for example, 13.0 or lower. From the viewpoint of corrosion of the polymerization vessel, it is preferably 12.0 or lower, more preferably 11.5 or lower, and even more preferably 11.0 or lower. The pH can be measured using a pH meter.

[0164] Even if the TFE polymer composition of the present disclosure does not use the specific hydrocarbon surfactant, it can also be obtained by a polymerization step comprising the steps of polymerizing tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium in the presence of an anionic hydrocarbon surfactant and a polymerization initiator to obtain a TFE polymer, and the hydrocarbon surfactant comprises a salt of the hydrocarbon surfactant.In other words, at least a part of the anionic hydrocarbon surfactant in the polymerization step is in the form of a salt.Through intensive research, the present inventors have unexpectedly found that the stability of polymerization is improved by the anionic hydrocarbon surfactant comprising a salt of the anionic hydrocarbon surfactant, and a TFE polymer with a large molecular weight can be produced.This is thought to be due to the fact that the anionic surfactant comprises a salt, improving the water solubility of the anionic surfactant, and making it easier to exhibit emulsification performance.The anionic hydrocarbon surfactant will be described later.The fact that the anionic hydrocarbon surfactant comprises a salt of the hydrocarbon surfactant can be confirmed by measuring conductivity. In the above-mentioned production method, the concentration of the salt of the anionic hydrocarbon surfactant is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to the total mass of the anionic hydrocarbon surfactant. The proportion of the salt can be measured by the solution concentration and conductivity. In the above-mentioned production method, the hydrocarbon surfactant is more preferably a carboxylic acid-type hydrocarbon surfactant. The hydrocarbon surfactant does not contain fluorine. In the salt of the anionic hydrocarbon surfactant, the cation (excluding hydrogen atoms) replacing the hydrogen atom of the acid can be, for example, a metal atom, NR ｙ ４ (R ｙmay be the same or different and are H or an organic group (preferably an organic group not containing fluorine)), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. ｙ is preferably H or an alkyl group, more preferably H or an alkyl group having 1 to 10 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. The cation in the salt of the anionic hydrocarbon surfactant may be a metal atom or NR ｙ ４ is preferred, and NR ｙ ４ is more preferred, and NH ４ Since the conductivity is greatly affected by temperature, the temperature of the sample liquid is kept at 25°C using a thermostatic bath, and the temperature of the pH meter cell is also kept at the same temperature before measuring the conductivity.

[0165] The TFE polymer composition of the present disclosure can be suitably produced by a production method comprising the addition step of adding at least one selected from the group consisting of radical scavengers and decomposers of polymerization initiators.The above-mentioned addition step is carried out during the step of carrying out the above-mentioned emulsion polymerization in an aqueous medium.By adding radical scavengers or decomposers of polymerization initiators, the radical concentration during polymerization can be adjusted.From the viewpoint of reducing radical concentration, radical scavengers are preferred.

[0166] The radical scavenger is a compound that does not have the ability to reinitiation after addition or chain transfer to the free radicals in the polymerization system. Specifically, a compound that easily undergoes 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, and among chain transfer agents, those with a reinitiation efficiency of almost 0% are called radical scavengers. The radical scavenger can also be described as, for example, a compound whose chain transfer constant with TFE at the polymerization temperature is greater than the polymerization rate constant and whose reinitiation efficiency is essentially 0%. "Reinitiation efficiency is essentially 0%" means that the generated radical turns the radical scavenger into a stable radical. Preferably, the compound has a chain transfer constant (Cs) (= chain transfer rate constant (kc) / polymerization rate constant (kp)) with TFE at polymerization temperature of more than 0.1, and the chain transfer constant (Cs) of the compound is more preferably 0.5 or more, even more preferably 1.0 or more, even more preferably 5.0 or more, and particularly preferably 10 or more.

[0167] Examples of the radical scavenger in the present disclosure include aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl ２) is preferred. Examples of aromatic hydroxy compounds include unsubstituted phenol, polyhydric phenol, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, etc. Examples of unsubstituted phenols include o-, m-, or p-nitrophenol, o-, m-, or p-aminophenol, p-nitrosophenol, etc. Examples of polyhydric phenols include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, naphthresorcinol, etc. Examples of aromatic amines include o-, m-, or p-phenylenediamine, benzidine, etc. Examples of quinone compounds include o-, m-, or p-benzoquinone, 1,4-naphthoquinone, alizarin, etc. Examples of thiocyanates include ammonium thiocyanate (NH ４ Examples of the radical scavenger include potassium thiocyanate (KSCN), sodium thiocyanate (NaSCN), etc. Among these, aromatic hydroxy compounds are preferred, unsubstituted phenols or polyhydric phenols are more preferred, and hydroquinone is even more preferred.

[0168] From the viewpoint of reducing the standard specific gravity, the amount of radical scavenger added is preferably an amount corresponding to 3 to 500% (molar basis) of the polymerization initiator concentration. A more preferred lower limit is 5% (molar basis), even more preferably 8% (molar basis), even more preferably 10% (molar basis), even more preferably 15% (molar basis), especially even more preferably 20% (molar basis), particularly preferably 25% (molar basis), especially preferably 30% (molar basis), especially preferably 35% (molar basis). A more preferred upper limit is 400% (molar basis), even more preferably 300% (molar basis), even more preferably 200% (molar basis), especially even more preferably 100% (molar basis).

[0169] The polymerization initiator decomposer may be any compound capable of decomposing the polymerization initiator used. For example, at least one selected from the group consisting of sulfites, bisulfites, bromates, diimines, diimine salts, oxalic acid, oxalates, copper salts, and iron salts is preferred. 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 polymerization initiator decomposer added is in the range of 25 to 300% by mass relative to the amount of the oxidizing agent combined as the polymerization initiator (the redox initiator described below). This is preferably 25 to 150% by mass, more preferably 50 to 100% by mass. The amount of the polymerization initiator decomposer added is preferably an amount equivalent to 3 to 500% (molar basis) of the polymerization initiator concentration in order to reduce the standard specific gravity. A more preferred lower limit is 5% (molar basis), even more preferably 8% (molar basis), even more preferably 10% (molar basis), even more preferably 13% (molar basis), even more preferably 15% (molar basis).A more preferred upper limit is 400% (molar basis), even more preferably 300% (molar basis), even more preferably 200% (molar basis), and especially preferably 100% (molar basis).

[0170] At least one selected from the group consisting of radical scavengers and decomposers of polymerization initiators is preferably added when the concentration of the TFE-based polymer formed in the aqueous medium is 5% by mass or more, more preferably 10% by mass or more, and is preferably added when the concentration of the TFE-based polymer formed in the aqueous medium is 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0171] The addition step may be a step of continuously adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator. Continuously adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator means, for example, adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator over time, without interruption, or in portions, rather than all at once.

[0172] The polymerization step may further comprise polymerizing tetrafluoroethylene in the presence of a nucleating agent.

[0173] As the nucleating agent, for example, it is preferred to be at least one selected from the group consisting of fluoropolyether, nonionic surfactant and chain transfer agent.In this case, it is preferred that the polymerization step is the step of obtaining TFE polymer by polymerizing tetrafluoroethylene in aqueous medium under the presence of hydrocarbon surfactant and the nucleating agent.

[0174] The fluoropolyether is preferably a perfluoropolyether.

[0175] The fluoropolyether preferably has repeating units represented by formulas (1a) to (1d): (-CFCF ３ -CF ２ -O-) ｎ (1a) (-CF ２ -CF ２ -CF ２ -O-) ｎ (1b) (-CF ２ -CF ２ -O-) ｎ -(-CF ２ -O-) ｍ (1c) (-CF ２ -CFCF ３ -O-) ｎ -(-CF ２ -O-) ｍ (1d) (In formulas (1a) to (1d), m and n are integers of 1 or more.)

[0176] 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.

[0177] The fluoropolyether acids or salts thereof can have any chain structure in which the oxygen atoms in the backbone of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. More than one type of fluorocarbon group can be present in the molecule.

[0178] The fluoropolyether acid or salt thereof may be a fluoropolyether acid represented by the following formula: CF ３ -CF ２ -CF ２ -O(-CFCF ３ -CF ２ -O-) ｎ CFCF ３ -COOH, CF ３ -CF ２ -CF ２ -O(-CF ２ -CF ２ -CF ２ -O-) ｎ -CF ２ -CF ２ COOH or HOOC-CF ２ -O(-CF ２ -CF ２ -O-) ｎ -(-CF ２ -O-) ｍ CF ２ COOH (wherein m and n are the same as above) or a salt thereof is preferred.

[0179] These structures are discussed by Kasai in J. Appl. Polymer Sci., 57, 797 (1995). As disclosed therein, such fluoropolyethers can have a carboxylic acid group or its salt at one or both ends. Similarly, such fluoropolyethers can have a sulfonic acid or phosphonic acid group or its salt at one or both ends. In addition, fluoropolyethers with acid functional groups at both ends can have different groups at each end. For monofunctional fluoropolyethers, the other end of the molecule is usually perfluorinated, but may contain a hydrogen or chlorine atom.

[0180] 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.

[0181] 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 more preferably has a number average molecular weight of 800 to 3500 g / mol, and even more preferably 1000 to 2500 g / mol.

[0182] The amount of the fluoropolyether is preferably 5 to 3000 ppm, more preferably 5 to 2000 ppm, with a more preferred lower limit of 10 ppm and a more preferred upper limit of 100 ppm relative to the aqueous medium.

[0183] Examples of the nonionic surfactant as the nucleating agent include the nonionic surfactants described above, and preferably nonionic surfactants that do not contain fluorine. For example, the nonionic surfactant may be a nonionic surfactant represented by the following general formula (i): ３ -O-A １ -H (i) (wherein, R３ is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A １ is a polyoxyalkylene chain. ３ The number of carbon atoms in R is preferably 10 to 16, and more preferably 12 to 16. ３ When the carbon number of R is 18 or less, good dispersion stability of the aqueous dispersion is easily obtained. ３ If the carbon number of R exceeds 18, the flow temperature is high and it is difficult to handle. ３ If the number of carbon atoms is less than 8, the surface tension of the aqueous dispersion increases, and the permeability and wettability tend to decrease.

[0184] The polyoxyalkylene chain may be composed of oxyethylene and oxypropylene. It is a polyoxyalkylene chain having an average repeat number of 5 to 20 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution as is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is 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. In particular, A １ When the number of oxypropylene groups is 0.5 to 1.5 on average, low foaming properties are favorable, and this is preferred.

[0185] More preferably, R ３ is (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.

[0186] Specific examples of the polyoxyethylene alkyl ether include C １３ H ２７-O-(C ２ H ４ O) １０ -H, C １２ H ２５ -O-(C ２ H ４ O) １０ -H, C １０ H ２１ CH (CH ３ ) CH ２ -O-(C ２ H ４ O) ９ -H, C １３ H ２７ -O-(C ２ H ４ O) ９ -(CH(CH ３ ) CH ２ O) -H,C １６ H ３３ -O-(C ２ H ４ O) １０ -H, HC(C ５ H １１ ) (C ７ H １５ )—O—(C ２ H ４ O) ９ -H, etc. Examples of commercially available polyoxyethylene alkyl ethers 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 Corporation) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Corporation), the T-Det A series (manufactured by Harcros Chemicals) such as T-Det A138 (trade name), and the Tergitol (registered trademark) 15S series (manufactured by Dow).

[0187] Also preferred is an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, or a mixture thereof. Nonionic surfactants of this type are also commercially available, for example, under the trade names TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all manufactured by The Dow Chemical Company).

[0188] The hydrophobic group of the nonionic surfactant may be any of an alkylphenol group, a linear alkyl group, and a branched alkyl group. For example, a polyoxyethylene alkylphenyl ether-based nonionic compound may be, for example, a compound represented by the following general formula (ii): ４ -C ６ H ４ -O-A ２ -H (ii) (wherein, R ４ is a linear or branched primary or secondary alkyl group having 4 to 12 carbon atoms, A ２ is a polyoxyalkylene chain. Specific examples of the polyoxyethylene alkylphenyl ether-based nonionic compounds include Triton (registered trademark) X-100 (product name, manufactured by Dow Chemical Company).

[0189] Other nonionic surfactants include difunctional block copolymers supplied by BASF as their Pluronic® R series, tridecyl alcohol alkoxylates supplied by BASF Corporation as their Iconol® TDA series, hydrocarbon-containing siloxane surfactants, preferably hydrocarbon surfactants, wherein the hydrocarbyl groups, which may be substituted by halogens such as fluorine, are fully substituted by hydrogen atoms, whereby these siloxane surfactants can also be considered hydrocarbon surfactants, i.e., the monovalent substituents on the hydrocarbyl groups are hydrogen.

[0190] In the above production method, in addition to the specific hydrocarbon surfactant and other surface-active compounds used as desired, additives can be used to stabilize each compound, such as buffers, pH adjusters, stabilizing aids, and dispersion stabilizers.

[0191] Preferred stabilizing aids include paraffin wax, fluorine-based oil, fluorine-based solvent, and silicone oil. The stabilizing aids may be used alone or in combination of two or more. Paraffin wax is more preferred as the stabilizing aid. Paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons having 12 or more carbon atoms are preferred. The melting point of the paraffin wax is generally preferably 40 to 65°C, more preferably 50 to 65°C.

[0192] The amount of the stabilizing aid used is preferably 0.1 to 12% by mass, more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing aid is sufficiently hydrophobic so that it is completely separated from the aqueous TFE polymer emulsion after emulsion polymerization of TFE and does not become a contaminating component.

[0193] In the above production method, emulsion polymerization can be carried out by charging an aqueous medium, the hydrocarbon surfactant, monomers, and other additives as necessary into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to initiate the polymerization reaction. After the polymerization reaction has started, additional monomers, polymerization initiators, chain transfer agents, the surfactants, etc. may be added depending on the purpose. The hydrocarbon surfactant may also be added after the polymerization reaction has started.

[0194] In the emulsion polymerization, the polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the target TFE-based polymer, and the reaction rate. Usually, the polymerization temperature is 5 to 150 ° C, preferably 10 ° C or higher, more preferably 30 ° C or higher, and even more preferably 50 ° C or higher. Also, it is more preferably 120 ° C or lower, and even more preferably 100 ° C or lower. The polymerization pressure is 0.05 to 10 MPaG. The polymerization pressure is more preferably 0.3 MPaG or higher, and even more preferably 0.5 MPaG or higher. Also, it is more preferably 5.0 MPaG or lower, and even more preferably 3.0 MPaG or lower. In particular, from the viewpoint of improving the yield, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, more preferably 1.5 MPaG or higher, even more preferably 1.8 MPaG or higher, and particularly preferably 2.0 MPaG or higher.

[0195] In the emulsion polymerization, the hydrocarbon surfactant is preferably added when the concentration of the TFE polymer formed in the aqueous medium is less than 0.60 mass%.More preferably, the concentration is 0.50 mass% or less, even more preferably 0.36 mass% or less, even more preferably 0.30 mass% or less, particularly preferably 0.20 mass% or less, and particularly preferably 0.10 mass% or less, and most preferably added at the start of polymerization.The above concentration is the concentration relative to the total of the aqueous medium and the TFE polymer.In addition, in the emulsion polymerization, the amount of the hydrocarbon surfactant at the start of polymerization is preferably 1 ppm or more relative to the aqueous medium.The amount of the hydrocarbon surfactant at the start of polymerization is preferably 10 ppm or more, more preferably 50 ppm or more, even more preferably 100 ppm or more, and even more preferably 200 ppm or more.The upper limit is not particularly limited, but for example, it is preferably 100,000 ppm, and more preferably 50,000 ppm. By setting the amount of hydrocarbon surfactant at the start of polymerization within the above range, an aqueous dispersion having a smaller average primary particle size and better stability can be obtained.

[0196] The polymerization initiator is not particularly limited as long as it can generate radicals in the above-mentioned polymerization temperature range, and can use known oil-soluble and / or water-soluble polymerization initiator.Furthermore, it can also be combined with reducing agent etc. to initiate polymerization as redox.The concentration of the polymerization initiator is suitably determined according to the type of monomer, the molecular weight of the target TFE polymer and reaction rate.

[0197] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0198] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, and representative examples thereof include dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, and dialkyl peroxides such as di-t-butyl peroxide.

[0199] 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, 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.

[0200] For example, when polymerization is carried out at a low temperature of 30°C or less, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of 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. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0201] The redox initiator preferably has an oxidizing agent that is permanganic acid or a salt thereof, a persulfate, manganese triacetate, a cerium (IV) salt, or a bromic acid or a salt thereof, and a reducing agent that is a dicarboxylic acid or a salt thereof, or a diimine. More preferably, the oxidizing agent is permanganic acid or a salt thereof, a persulfate, or a bromic acid or a salt thereof, and the reducing agent is a dicarboxylic acid or a salt thereof.

[0202] Examples of the redox initiator include combinations such as potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, manganese triacetate / oxalic acid, manganese triacetate / ammonium oxalate, cerium ammonium nitrate / oxalic acid, and cerium ammonium nitrate / ammonium oxalate. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into a polymerization vessel in advance, followed by continuous or intermittent addition of the other agent to initiate polymerization. For example, when potassium permanganate / ammonium oxalate is used, it is preferable to charge ammonium oxalate into a polymerization vessel and then continuously add potassium permanganate thereto. Note that, in this specification, the term "potassium permanganate / ammonium oxalate" refers to a combination of potassium permanganate and ammonium oxalate. The same applies to other compounds. As the redox initiator, it is preferable to use an oxidizing agent or reducing agent capable of adjusting the pH of the redox initiator aqueous solution to 4.0 or higher. The redox initiator aqueous solution refers to a 0.50% by mass aqueous solution of an oxidizing agent or a 0.50% by mass aqueous solution of a reducing agent. That is, it is sufficient that the pH of at least one of the 0.50% by mass aqueous solution of an oxidizing agent and the 0.50% by mass aqueous solution of a reducing agent is 4.0 or higher, and it is preferable that the pH of both the 0.50% by mass aqueous solution of an oxidizing agent and the 0.50% by mass aqueous solution of a reducing agent is 4.0 or higher. The pH of the redox initiator aqueous solution (the 0.50% by mass aqueous solution of an oxidizing agent or the 0.50% by mass aqueous solution of a reducing agent) is more preferably 5.0 or higher, even more preferably 5.5 or higher, and particularly preferably 6.0 or higher.

[0203] The redox initiator is preferably a combination of an oxidizing agent that is a salt and a reducing agent that is a salt. For example, the oxidizing agent that is a salt is more preferably at least one selected from the group consisting of persulfates, permanganates, cerium (IV) salts, and bromates, more preferably permanganates, and particularly preferably potassium permanganate. The reducing agent that is a salt is more preferably at least one selected from the group consisting of oxalates, malonates, succinates, glutarates, and bromates, more preferably oxalates, and particularly preferably ammonium oxalate.

[0204] Specifically, the redox initiator is preferably at least one selected from the group consisting of potassium permanganate / ammonium oxalate, potassium bromate / ammonium sulfite, manganese triacetate / ammonium oxalate, and cerium ammonium nitrate / ammonium oxalate, and more preferably at least one selected from the group consisting of potassium permanganate / ammonium oxalate, potassium bromate / ammonium sulfite, and cerium ammonium nitrate / ammonium oxalate.

[0205] By using a redox initiator in the polymerization step, the molecular weight of the resulting TFE-based polymer can be increased. Therefore, the SSG can be reduced, making the polymer stretchable. Furthermore, by using a redox initiator in the polymerization step, the number of TFE-based polymer particles produced in the aqueous dispersion can be increased. Furthermore, the yield of the TFE-based polymer can be increased. When a redox initiator is used, the oxidizing agent and the reducing agent may be added all at once at the beginning of polymerization, or the reducing agent may be added all at once at the beginning of polymerization and the oxidizing agent may be added continuously, or the oxidizing agent may be added all at once at the beginning of polymerization and the reducing agent may be added continuously, or both the oxidizing agent and the reducing agent may be added continuously. When a redox initiator is used as a polymerization initiator, the amount of the oxidizing agent added is preferably 5 to 10,000 ppm, more preferably 10 to 1,000 ppm, relative to the aqueous medium, and the amount of the reducing agent added is preferably 5 to 10,000 ppm, more preferably 10 to 1,000 ppm. When a redox initiator is used in the polymerization step, the polymerization temperature is preferably 100° C. or lower, more preferably 95° C. or lower, and even more preferably 90° C. or lower. The polymerization temperature is preferably 10° C. or higher, more preferably 20° C. or higher, and even more preferably 30° C. or higher.

[0206] The amount of polymerization initiator 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 reduce 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. More specifically, for example, the amount is preferably 1 ppm or more relative to the aqueous medium, more preferably 10 ppm or more, and even more preferably 50 ppm or more. Also, the amount is preferably 100,000 ppm or less, more preferably 10,000 ppm or less, and even more preferably 5,000 ppm or less.

[0207] 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, an ether, or a ketone, and / or a fluorine-containing organic solvent having a boiling point of 40° C. or lower.

[0208] In the emulsion polymerization, a known chain transfer agent may be added depending on the purpose to adjust the polymerization rate and molecular weight.

[0209] 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.

[0210] Bromine compounds or iodine compounds may be used as chain transfer agents. The polymerization method using a bromine compound or an iodine compound may, for example, be a method of polymerizing a fluoromonomer 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 compound or iodine compound to be 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.

[0211] Examples of 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, CF ２ Br ２ , BrCF ２ CF ２ Br, CF ３ CFBrCF ２ Br, CFClBr ２ , BrCF ２ CFClBr, CFBrClCFClBr, BrCF ２ CF ２ CF ２ Br, BrCF ２ CFBrOCF ３ , 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, and these compounds may be used alone or in combination with each other.

[0212] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0213] The amount of the chain transfer agent used is usually 1 to 50,000 ppm, preferably 1 to 20,000 ppm, based on the total amount of fluoromonomers supplied.

[0214] 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.

[0215] An aqueous dispersion of a TFE-based polymer can be obtained by the emulsion polymerization. The aqueous dispersion usually contains a TFE-based polymer, compound (1) and / or (2), and an aqueous medium. The solids concentration of the aqueous dispersion is not limited, but may be, for example, 1.0 to 70% by mass. The solids concentration is preferably 8.0% by mass or more, more preferably 10.0% by mass or more, and preferably 60.0% by mass or less, more preferably 50.0% by mass or less. In the production method, the adhesion amount 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 TFE-based polymer finally obtained.

[0216] The TFE polymer used as the raw material of the above-mentioned TFE polymer composition is preferably 150nm or more in average primary particle diameter, because it can obtain a composite sheet with higher strength and excellent homogeneity.More preferably, it is 180nm or more, even more preferably, it is 210nm or more, and particularly preferably, it is 220nm or more.The larger the average primary particle diameter of the TFE polymer, the more suppress the increase of extrusion pressure when using its powder for extrusion molding, and the more excellent moldability.The upper limit is not particularly limited, but may be 500nm.From the viewpoint of productivity in polymerization process, the upper limit is preferably 350nm.

[0217] The average primary particle diameter can be determined by preparing a calibration curve of the transmittance of 550 nm projected light per unit length of an aqueous dispersion of a TFE-based polymer obtained by polymerization, the polymer concentration of which is adjusted to 0.22% by mass, and the average primary particle diameter determined by measuring the unidirectional diameter in a transmission electron microscope photograph, and measuring the transmittance of the aqueous dispersion to be measured, based on the calibration curve.

[0218] The mixture of the TFE-based polymer and the conductive carbon material mixed in the liquid medium in the above step (A) is then preferably dried by spray drying (step (B)) to remove the liquid medium. Examples of drying methods include a tray dryer, a vacuum dryer, a freeze dryer, a hot air dryer, a drum dryer, and a spray dryer. Spray drying is particularly preferred. Spray drying is a method of spraying a liquid and solid mixture into a gas and rapidly drying it to produce a dry powder. This allows for a powder-state composition in which the TFE-based polymer and the conductive carbon material are uniformly mixed. Spray drying is a commonly known method and can be performed by a general method using any known device. The above step (B) can be performed by a general method using known, general device. The drying temperature is preferably in the range of, for example, 100°C or higher and 250°C or lower. At 100°C or higher, the solvent can be sufficiently removed, and at 250°C or lower, energy consumption can be further reduced, which is preferable. The drying temperature is more preferably 110°C or higher and more preferably 220°C or lower. The amount of the liquid supplied may vary depending on the scale of production, but may be, for example, in the range of 0.1 L / h to 2 L / h. The size of the nozzle for spraying the prepared solution may vary depending on the scale of production, but may be, for example, in the range of 0.5 mm to 5 mm in diameter.

[0219] The TFE polymer composition of the present disclosure is used in the binder for electrochemical device.In the binder for electrochemical device, the TFE polymer composition of the present disclosure can be used alone, or can be mixed with other materials and used, but the TFE polymer composition of the present disclosure is preferably used substantially alone, and more preferably used alone.It should be noted that, "substantially use the TFE polymer composition of the present disclosure substantially alone" means that the amount of the TFE polymer composition in the binder for electrochemical device is used within the range described below.

[0220] The present disclosure also provides a binder for electrochemical devices consisting essentially of a TFE-based polymer composition, the TFE-based polymer composition comprising a TFE-based polymer, at least one compound selected from the group consisting of compounds represented by the following general formula (1) and compounds represented by the following general formula (2), and a conductive carbon material, wherein the amount of the TFE-based polymer relative to the solid content in the TFE-based polymer composition is 10 mass % or more. ２ ) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ represents H, a metal atom, NR ５ ４ (R ５ may be the same or different and are H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ ) ｎ -SO ３ ) ｑ M ２ (wherein n is 4 to 20. M ２ is H, metal atom, NR ５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0221] The binder of the present disclosure contains a specific TFE-based polymer composition, thereby reducing the resistance of the composite sheet. Furthermore, when the binder is in powder form, it can also improve flowability. The binder of the present disclosure can also be used in a dry state, eliminating the need to use a large amount of a dispersion medium such as water or an organic solvent, allowing for a wide selection of electrode active materials and solid electrolytes to be combined, which is advantageous in terms of the production process. Furthermore, the process and cost associated with the use of a dispersion medium can be reduced. Furthermore, the binder of the present disclosure has excellent binding strength with active materials and electrolytes, allowing for a reduction in the amount used.

[0222] As the TFE-based polymer composition in the binder of the present disclosure, the same TFE-based polymer composition as the above-mentioned TFE-based polymer composition of the present disclosure can be used, and the preferred embodiments are also the same.

[0223] The binder of the present disclosure is substantially composed of the TFE-based polymer composition. This allows the effects of the TFE-based polymer composition to be significantly exhibited. "Substantially composed of the TFE-based polymer composition" means that the content of the TFE-based polymer composition is 95.0% by mass or more relative to the binder. The content of the TFE-based polymer composition is preferably 98.0% by mass or more relative to the binder, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the binder of the present disclosure is composed of the TFE-based polymer composition alone.

[0224] The binder of the present disclosure is preferably substantially free of organic solvents. This allows for reduction in steps and costs associated with the use of organic solvents. "Substantially free of organic solvents" means that the organic solvent content relative to the binder is 5% by mass or less. The organic solvent content is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and particularly preferably 0.001% by mass or less.

[0225] The binder of the present disclosure is preferably in the form of a powder, but may be in a form other than a powder, such as a dispersion or a molded body. Examples of the molded body include a sheet, pellet, and rod.

[0226] The binder of the present disclosure is used in electrochemical devices such as batteries and capacitors. Examples of batteries include secondary batteries such as lithium ion batteries. The capacitor is not particularly limited, but is preferably an electrochemical capacitor. Examples of electrochemical capacitors include electric double layer capacitors, hybrid capacitors, and redox capacitors. Examples of hybrid capacitors include sodium ion capacitors, lithium ion capacitors, and magnesium ion capacitors. Among these, electric double layer capacitors are particularly preferred.

[0227] The binder of the present disclosure can be suitably used as a battery binder, and particularly suitably used as a binder for secondary batteries such as lithium ion batteries. It is particularly preferred to use it as a binder for lithium ion secondary batteries. The binder of the present disclosure may be used to prepare electrochemical device components, preferably battery components. The binder of the present disclosure can be particularly suitably used as an electrode binder. The binder of the present disclosure can also be suitably used as a binder in the solid electrolyte layer of a solid secondary battery.

[0228] The present disclosure also provides an electrode mixture comprising the TFE-based polymer composition or binder of the present disclosure and an electrode active material. The use of the electrode mixture of the present disclosure allows for a low-resistance mixture sheet to be obtained. Furthermore, even with a small amount of conductive carbon material (conductive additive), good electronic conductivity can be maintained, allowing for the addition of more materials that improve the properties of electrochemical devices, such as active materials and electrolytes.

[0229] Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0230] The positive electrode active material is not particularly limited as long as it can electrochemically absorb and release alkali metal ions, but for example, a material containing an alkali metal and at least one transition metal is preferred. Specific examples include alkali metal-containing transition metal composite oxides and alkali metal-containing transition metal phosphate compounds. Of these, alkali metal-containing transition metal composite oxides that generate high voltage are particularly preferred as the positive electrode active material. Examples of the alkali metal ions include lithium ions, sodium ions, and potassium ions. In a preferred embodiment, the alkali metal ions may be lithium ions. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery.

[0231] Examples of the alkali metal-containing transition metal composite oxide include those represented by the formula: M ａ Mn ２－ｂ M １ ｂ O ４ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0.9≦a; 0≦b≦1.5; M １ is at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), alkali metal-manganese spinel composite oxides (such as lithium-manganese spinel composite oxides) represented by the formula: MNi １－ｃ M ２ ｃ O ２ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦c≦0.5; M ２ is at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), or an alkali metal-nickel composite oxide (such as a lithium-nickel composite oxide) represented by the formula: MCo １－ｄ M ３ ｄ O ２ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦d≦0.5; M ３is at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li.

[0232] Among these, MCoO is preferred because it can provide a secondary battery with high energy density and high output. ２ , M MnO ２ , MNiO ２ , M.M. ２ O ４ , MNi ０．８ Co ０．１５ Al ０．０５ O ２ , or MNi １／３ Co １／３ Mn １／３ O ２ and the like are preferred, and a compound represented by the following general formula (3) is preferred: MNi ｈ Co ｉ Mn ｊ M ５ ｋ O ２ (3) (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ５ represents at least one selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h+i+j+k)=1.0, 0≦h≦1.0, 0≦i≦1.0, 0≦j≦1.5, 0≦k≦0.2.

[0233] Examples of the alkali metal-containing transition metal phosphate compound include those represented by the following general formula (4): ｅ M ４ ｆ (P.O. ４ ) ｇ (4) (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ４represents at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni, and Cu, and 0.5≦e≦3, 1≦f≦2, and 1≦g≦3. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li. That is, the alkali metal-containing transition metal phosphate compound is preferably a lithium-containing transition metal phosphate compound.

[0234] The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, or the like, and specific examples thereof include LiFePO ４ , Li ３ Fe ２ (P.O. ４ ) ３ , LiFeP ２ O ７ Iron phosphates such as LiCoPO ４ and lithium transition metal phosphate compounds in which a part of the transition metal atoms constituting the main component of these compounds is substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc. The lithium-containing transition metal phosphate compounds preferably have an olivine structure.

[0235] Other examples of the positive electrode active material include lithium-nickel composite oxides. The lithium-nickel composite oxides are represented by the following general formula (5): Li ｙ Ni １－ｘ M ｘ O ２ (5) (wherein x is 0.01≦x≦0.7, y is 0.9≦y≦2.0, and M is a metal atom (excluding Li and Ni)) is preferred.

[0236] Other positive electrode active materials include MFePO ４ , MNi ０．８ Co ０．２ O ２ , M １．２ Fe ０．４ Mn ０．４ O ２, MNi ０．５ Mn １．５ O ２ , M.V. ３ O ６ , M ２ MnO ３ In particular, M ２ MnO ３ , MNi ０．５ Mn １．５ O ２ (wherein M is at least one metal selected from the group consisting of Li, Na, and K) are preferred in that the crystalline structure does not collapse even when the secondary battery is operated at a voltage exceeding 4.4 V or a voltage of 4.6 V or higher. Therefore, electrochemical devices such as secondary batteries using a cathode material containing the above-mentioned cathode active materials are preferred because the remaining capacity is less likely to decrease and the rate of increase in resistance is less likely to change even when stored at high temperatures, and the battery performance does not deteriorate even when operated at high voltages.

[0237] Other positive electrode active materials include M ２ MnO ３ and M.M. ６ O ２ (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ６ Examples of the material include solid solution materials with transition metals such as Co, Ni, Mn, and Fe.

[0238] The solid solution material may be, for example, a material represented by the general formula M ｘ [Mn （１－ｙ） M ７ ｙ ]O ｚ In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, and M ７ is composed of at least one metal element other than M and Mn, and contains, for example, one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr and Sn. The values ​​of x, y and z in the formula are in the ranges of 1<x<2, 0≦y<1 and 1.5<z<3. Among them, Li １．２ Mn ０．５ Co ０．１４ Ni ０．１４ O２ Li like ２ MnO ３ Based on LiNiO ２ and LiCoO ２ A manganese-containing solid solution material containing manganese is preferred in that it can provide an alkali metal ion secondary battery having a high energy density.

[0239] Furthermore, it is preferable to include lithium phosphate in the positive electrode active material, since this improves continuous charging characteristics. Although there is no limitation on the use of lithium phosphate, it is preferable to use a mixture of the positive electrode active material and lithium phosphate. The amount of lithium phosphate used, based on the total amount of the positive electrode active material and lithium phosphate, is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0240] The shape of the particles of the positive electrode active material may be any of the conventional shapes such as block, polyhedron, sphere, oval sphere, plate, needle, column, etc. Furthermore, primary particles may aggregate to form secondary particles.

[0241] The median diameter d50 of the particles of the positive electrode active material (the secondary particle diameter when primary particles are aggregated to form secondary particles) is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more, and is preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it is below the lower limit, a high tap density product may not be obtained, and if it exceeds the upper limit, it may take a long time for lithium to diffuse within the particles, resulting in problems such as a decrease in battery performance. Here, by mixing two or more types of the above positive electrode active materials having different median diameters d50, the filling ability during positive electrode production can be further improved.

[0242] The median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using a HORIBA LA-920 particle size distribution analyzer, the measurement is performed using a 0.1% by mass aqueous solution of sodium hexametaphosphate as the dispersion medium, and after ultrasonic dispersion for 5 minutes, the measurement is performed with a refractive index set to 1.24.

[0243] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m ２ / g or more, more preferably 0.2m ２ / g or more, more preferably 0.3m ２ / g or more, and the upper limit is preferably 50m ２ / g or less, more preferably 40m ２ / g or less, more preferably 30m ２ / g or less. If the BET specific surface area is smaller than this range, battery performance is likely to decrease, while if it is larger, it is difficult to increase the tap density, which may lead to problems with processability when forming the positive electrode active material layer. The BET specific surface area is defined as a value measured by a nitrogen adsorption BET single-point method using a surface area meter (e.g., a fully automatic surface area measuring device manufactured by Ohkura Riken Co., Ltd.) after pre-drying a sample at 150°C for 30 minutes under a nitrogen flow, using a nitrogen-helium mixed gas accurately adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0244] The particles of the positive electrode active material are preferably mainly secondary particles. The particles of the positive electrode active material preferably have an average secondary particle size of 40 μm or less and contain 0.5 to 30.0 volume % of fine particles having an average primary particle size of 1 μm or less. By including fine particles having an average primary particle size of 1 μm or less, the contact area with the electrolyte is increased, which can speed up the diffusion of lithium ions between the electrode mixture and the electrolyte, thereby improving the output performance of the battery.

[0245] For the production of a positive electrode, the positive electrode active material may be used alone, or two or more types of different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO ２ and LiNi ０．３３ Co ０．３３ Mn０．３３ O ２ combination with ternary systems such as LiCoO ２ and LiMn ２ O ４ Or a combination of this with a material in which a part of Mn is replaced with another transition metal, or LiFePO ４ and LiMn ２ O ４ A combination of is mentioned.

[0246] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, more preferably 80 to 99% by mass, in terms of high battery capacity. The content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0247] The negative electrode active material is not particularly limited, and examples thereof include carbonaceous materials such as lithium metal, artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; Li ４ Ti ５ O １２ Among these, those containing at least a carbonaceous material and silicon-containing compounds are particularly suitable.

[0248] The negative electrode active material used in the present disclosure preferably contains silicon as a constituent element, which allows the production of a high-capacity battery.

[0249] The silicon-containing material is preferably silicon particles, particles having a structure in which silicon fine particles are dispersed in a silicon-based compound, silicon oxide particles represented by the general formula SiOx (0.5≦x≦1.6), or a mixture thereof. By using these, a negative electrode mixture for a lithium ion secondary battery having higher initial charge / discharge efficiency, high capacity, and excellent cycle characteristics can be obtained.

[0250] The physical properties of the silicon-containing particles can be appropriately selected depending on the desired composite particles. For example, the average particle size is preferably 0.1 to 50 μm, with the lower limit being more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and even more preferably 20 μm or less. The average particle size is expressed as the weight-average particle size measured by particle size distribution measurement using a laser diffraction method.

[0251] BET specific surface area: 0.5 to 100 m ２ / g is preferred, and 1 to 20m ２ / g is more preferable. ２ If the adhesive strength is 100 m / g or more, there is no risk of the adhesive strength decreasing when processed into an electrode, and the battery characteristics decreasing. ２ / g or less, the proportion of silicon dioxide on the particle surface is large, and there is no risk of a decrease in battery capacity when used as a negative electrode material for a lithium ion secondary battery.

[0252] The silicon-containing particles are coated with carbon to impart conductivity, thereby improving battery performance. Methods for imparting conductivity include mixing the silicon-containing particles with conductive particles such as graphite, coating the surfaces of the silicon-containing particles with a carbon coating, and combining both methods. The carbon coating method is preferred, and chemical vapor deposition (CVD) is more preferred.

[0253] In order to increase the capacity of the resulting electrode mixture, the content of the negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more, of the electrode mixture, and the upper limit is preferably 99% by mass or less, more preferably 98% by mass or less.

[0254] The electrode mixture of the present disclosure may contain a thermoplastic polymer. Examples of the thermoplastic polymer include polyvinylidene fluoride, vinylidene fluoride copolymer, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and polyethylene oxide. The thermoplastic polymer may be a resin or an elastomer. One type may be used alone, or two or more types may be used in any combination and ratio.

[0255] The content of the thermoplastic polymer relative to the electrode active material is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and usually 3.0% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass or less. Adding the thermoplastic polymer can improve the mechanical strength of the electrode. Furthermore, if the content exceeds this range, the proportion of the electrode active material in the electrode mixture decreases, which may cause problems such as a decrease in battery capacity or an increase in resistance between the active materials.

[0256] In the electrode mixture of the present disclosure, the binder content may be 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and may be 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 3% by mass or less. If the binder content is too low, the electrode mixture active material may not be sufficiently retained, resulting in insufficient mechanical strength of the electrode mixture sheet and deterioration of battery performance such as cycle characteristics. On the other hand, if the binder content is too high, it may lead to a decrease in battery capacity and conductivity. Because the binder of the present disclosure has excellent binding strength, even a small content can sufficiently retain the electrode active material.

[0257] In the electrode mixture of the present disclosure, the binder component is preferably substantially composed of the TFE polymer composition, more preferably of the TFE polymer composition.The binder component is substantially composed of the TFE polymer composition, meaning that the content of the TFE polymer composition in the binder component constituting the electrode mixture is 95.0% by mass or more relative to the binder component.The content of the TFE polymer composition is preferably 98.0% by mass or more relative to the binder component, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more.

[0258] The electrode mixture of the present disclosure is preferably in the form of a sheet.

[0259] The electrode mixture of the present disclosure can be suitably used as an electrode mixture for secondary batteries. In particular, the electrode mixture of the present disclosure is suitable for lithium ion secondary batteries. When used in secondary batteries, the electrode mixture of the present disclosure is usually used in the form of a sheet.

[0260] The electrode mixture sheet preferably has a thickness of 300 μm or less, more preferably 250 μm or less, even more preferably 200 μm or less, even more preferably 180 μm or less, and particularly preferably 150 μm or less, and preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and even more preferably 50 μm or more.

[0261] An example of a specific method for producing an electrode mixture sheet containing an electrode mixture is shown below. The electrode mixture sheet can be obtained by a production method including the steps of: (0) preparing a mixture containing an electrode active material and, if necessary, a conductive additive; (1) mixing a binder with the mixture obtained in the step (0) to prepare a composition for electrode preparation; (2) applying a shear force while mixing the composition for electrode preparation; (3) forming the electrode mixture obtained in the step (2) into a bulk shape; and (4) rolling the bulk electrode mixture obtained in the step (3) into a sheet shape.

[0262] In the above step (1), a TFE-based polymer or a conductive carbon material may be additionally added and mixed.

[0263] At the stage where shear force is applied while mixing the composition for electrode preparation in the above step (2), the resulting composition for electrode preparation is simply a mixture of the electrode active material, binder, etc. and exists in a formless state. Specific mixing methods include mixing methods using a drum mixer, a conical screw mixer, a single-screw kneader, a twin-screw kneader, a mix muller, a stirring mixer, a planetary mixer, a Henschel mixer, a high-speed mixer, etc.

[0264] In the above step (2), the mixing conditions may be appropriately set by the rotation speed and mixing time. For example, the rotation speed is preferably 2200 rpm or less. It is preferably 10 rpm or more, more preferably 15 rpm or more, and even more preferably 20 rpm or more. It is also preferably 2000 rpm or less, more preferably 1800 rpm or less, and even more preferably 1500 rpm. If the rotation speed is below the above range, mixing will take a long time, which will affect productivity. If the rotation speed is above the above range, fibrillation will proceed excessively, and the electrode mixture sheet may have poor strength and flexibility.

[0265] In the above step (3), forming into a bulk refers to forming the electrode-forming composition into a single mass. Specific methods for forming into a bulk include extrusion molding, press molding, and the like. The term "bulk" does not particularly specify a shape, and may refer to a single mass, including rods, sheets, spheres, cubes, and the like. The size of the mass is preferably such that the cross-sectional diameter or the shortest side is 10,000 μm or more, more preferably 20,000 μm or more.

[0266] Specific examples of the rolling method in the step (4) include rolling using a roll press, a plate press, a calender roll, or the like.

[0267] It is also preferable to include a step (5) after step (4), in which a larger load is applied to the obtained rolled sheet to roll it into an even thinner sheet. Repeating step (5) is also preferable. In this way, by rolling the rolled sheet little by little in stages rather than thinning it all at once, flexibility is improved. The number of times step (5) is performed is preferably 2 to 10 times, more preferably 3 to 9 times. Specific rolling methods include, for example, rotating two or more rolls and passing the rolled sheet between them to process it into an even thinner sheet. It is desirable to heat the sheet during rolling. The lower limit of the temperature range is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. Heating softens the sheet, making it easier to roll.

[0268] From the viewpoint of adjusting the fibril diameter, it is also preferable to include a step (6) after step (4) or step (5) in which the rolled sheet is roughly crushed, re-formed into a bulk form, and rolled into a sheet. It is also preferable to repeat step (6). The number of times step (6) is performed is preferably from 1 to 12 times, more preferably from 2 to 11 times.

[0269] In step (6), specific methods for roughly crushing the rolled sheet and forming it into a bulk form include folding the rolled sheet, forming it into a rod or thin film sheet, chipping, etc. In the present disclosure, "rough crushing" means changing the form of the rolled sheet obtained in step (4) or step (5) into a different form in order to roll it into a sheet in the next step, and also includes simply folding the rolled sheet.

[0270] Furthermore, step (5) may be performed after step (6), or may be repeated. Furthermore, uniaxial or biaxial stretching may be performed in steps (3), (4), (5), and (6). Furthermore, the fibril diameter can be adjusted by the degree of crushing in step (6).

[0271] In the above steps (4), (5), or (6), the rolling ratio is preferably 10% or more, more preferably 20% or more, and preferably 80% or less, more preferably 65% ​​or less, and even more preferably 50% or less. If the rolling ratio is below the above range, the number of rolling operations increases, which takes more time and affects productivity. If the rolling ratio is above the above range, excessive fibrillation may occur, resulting in an electrode mixture sheet with poor strength and flexibility. The rolling ratio here refers to the reduction in thickness of the sample after rolling relative to the thickness before rolling. The sample before rolling may be a bulk electrode composition or a sheet electrode composition. The thickness of the sample refers to the thickness in the direction in which a load is applied during rolling.

[0272] The electrode mixture sheet can also be suitably produced by a production method comprising: step (a): mixing powder components (such as an electrode active material) and a binder to form an electrode mixture; and step (b): calendaring or extrusion-molding the electrode mixture to produce a sheet, wherein the mixing in step (a) comprises: (a1) homogenizing the powder components and the binder to form a powder; and (a2) mixing the powdered electrode-making composition obtained in step (a1) to prepare an electrode mixture.

[0273] For example, PTFE has two transition temperatures at about 19° C. and about 30° C. Below 19° C., PTFE can be easily mixed while maintaining its shape. However, above 19° C., the structure of the PTFE particles becomes looser and more sensitive to mechanical shear. At temperatures above 30° C., a greater degree of fibrillation occurs.

[0274] For this reason, the homogenization of (a1) is preferably carried out at a temperature of 19°C or lower, preferably 0°C to 19°C. That is, in such (a1), it is preferable to mix and homogenize while suppressing fibrillation. The subsequent mixing in (a2) is preferably carried out at a temperature of 30°C or higher to promote fibrillation.

[0275] Preferably, step (a2) is carried out at a temperature of 30° C. to 150° C., more preferably 35° C. to 120° C., even more preferably 40° C. to 100° C. In one embodiment, the calendering or extrusion of step (b) is carried out at a temperature between 30° C. and 150° C., preferably between 35° C. and 120° C., more preferably between 40° C. and 100° C.

[0276] The mixing in step (a) is preferably carried out while applying a shear force. Specific mixing methods include mixing using a drum mixer, a conical screw mixer, a single-screw kneader, a twin-screw kneader, a mix muller, a stirring mixer, a planetary mixer, a Henschel mixer, a high-speed mixer, etc.

[0277] The mixing conditions may be appropriately set by the rotation speed and mixing time. For example, the rotation speed is preferably 15,000 rpm or less. It is preferably 10 rpm or more, more preferably 50 rpm or more, even more preferably 100 rpm or more, and is preferably 12,000 rpm or less, more preferably 10,000 rpm or less, and even more preferably 8,000 rpm or less. If the rotation speed is below the above range, mixing will take a long time, which will affect productivity. If the rotation speed is above the above range, fibrillation will proceed excessively, which may result in an electrode mixture sheet with inferior strength. It is preferable to perform step (a1) with a weaker shear force than step (a2). It is also desirable to perform step (a1) for a shorter time than step (a2).

[0278] In the step (a2), the electrode-forming composition preferably does not contain a liquid solvent, but a small amount of a lubricant may be used. That is, a lubricant may be added to the powdered electrode-forming composition obtained in the step (a1) to prepare a paste.

[0279] The lubricant is not particularly limited, and examples thereof include water, ether compounds, alcohols, ionic liquids, carbonates, aliphatic hydrocarbons (low-polarity solvents such as heptane and xylene), isoparaffinic hydrocarbon compounds, and petroleum fractions (gasoline (C4-C10), naphtha (C4-C11), kerosene / paraffin (C10-C16), and mixtures thereof).

[0280] The lubricant preferably has a water content of 1000 ppm or less. A water content of 1000 ppm or less is preferable in that it reduces deterioration of the electrochemical device. The water content is more preferably 500 ppm or less, and even more preferably 100 ppm or less.

[0281] When the lubricant is used, the amount thereof may be 5.0 to 35.0 parts by weight based on the total weight of the composition subjected to step (a1).

[0282] It is preferable that the electrode preparation composition and electrode mixture sheet substantially contain no liquid medium. Conventional electrode mixture formation methods generally involve preparing a slurry in which powders, which are electrode mixture components, are dispersed using a solvent in which a binder is dissolved, and then applying and drying the slurry to prepare an electrode mixture sheet. In conventional methods, the binder must be dissolved, which requires processing time for slurry preparation. Furthermore, a large amount of energy is required to thoroughly dry the solvent after application. By using a powder binder with low moisture content without using a solvent when forming the electrode preparation composition and electrode mixture sheet, the burden on the manufacturing process can be reduced without causing deterioration of battery components such as the active material and electrolyte.

[0283] Step (b) is calendering or extrusion. Calendering and extrusion can be performed by well-known methods. This allows the electrode mixture to be formed into the shape of an electrode mixture sheet. Step (b) preferably includes (b1) a step of forming the electrode mixture obtained by step (a) into a bulk form, and (b2) a step of calendering or extrusion-molding the bulk electrode mixture.

[0284] Forming into a bulk state means forming the electrode mixture into a single mass. Specific methods for forming into a bulk state include extrusion molding, press molding, and the like. The term "bulk state" does not particularly specify a shape, and may refer to a state in which the electrode mixture is in the form of a single mass, including rods, sheets, spheres, cubes, and the like. The size of the mass is preferably such that the diameter or the shortest side of its cross section is 10,000 μm or more, more preferably 20,000 μm or more.

[0285] Specific examples of the calendering or extrusion molding method in the step (b2) include a method of rolling the electrode mixture using a roll press, a calender roll machine, or the like.

[0286] The above step (b) is preferably carried out at 30 to 200° C. As mentioned above, PTFE has a glass transition temperature around 30° C., and therefore, is easily fibrillated at temperatures above 30° C. Therefore, the step (b) is preferably carried out at such a temperature.

[0287] Furthermore, calendering or extrusion applies shear force, which causes the PTFE to fibrillate and form.

[0288] It is also preferable to have a step (c) after step (b) in which a larger load is applied to the obtained rolled sheet to roll it into an even thinner sheet. It is also preferable to repeat step (c). In this way, by rolling the rolled sheet little by little in stages rather than thinning it all at once, flexibility is improved. The number of times step (c) is performed is preferably from 2 to 10 times, and more preferably from 3 to 9 times. Specific rolling methods include, for example, a method in which two or more rolls are rotated and the rolled sheet is passed between them to process it into an even thinner sheet.

[0289] From the viewpoint of adjusting the sheet strength, it is also preferable to include a step (d) after step (b) or step (c) in which the rolled sheet is crushed, re-formed into a bulk form, and rolled into a sheet. It is also preferable to repeat step (d). The number of times step (d) is performed is preferably from 1 to 12 times, more preferably from 2 to 11 times.

[0290] In step (d), specific methods for crushing the rolled sheet and forming it into a bulk form include folding the rolled sheet, forming it into a rod or thin film sheet, chipping, etc. In the present disclosure, "crushing" means changing the form of the rolled sheet obtained in step (b) or (c) into another form in order to roll it into a sheet in the next step, and also includes simply folding the rolled sheet.

[0291] Furthermore, step (c) may be performed after step (d), or these steps may be repeated. Furthermore, uniaxial or biaxial stretching may be performed in steps (a), (b), (c), and (d). Furthermore, the sheet strength can be adjusted by the degree of crushing in step (d).

[0292] In the above steps (b), (c), or (d), the rolling ratio is preferably 10% or more, more preferably 20% or more, and preferably 80% or less, more preferably 65% ​​or less, and even more preferably 50% or less. If the rolling ratio is below the above range, the number of rolling operations increases, resulting in a longer time and affecting productivity. If the rolling ratio is above the above range, excessive fibrillation may occur, resulting in an electrode mixture sheet with poor strength and flexibility. The rolling ratio here refers to the reduction in thickness of the sample after rolling relative to the thickness before rolling. The sample before rolling may be a bulk electrode composition or a sheet electrode composition. The thickness of the sample refers to the thickness in the direction in which a load is applied during rolling. The above steps (c) to (d) are preferably performed at 30°C or higher, more preferably 60°C or higher. Furthermore, they are preferably performed at 200°C or lower.

[0293] The electrode mixture sheet can be used as an electrode mixture sheet for a secondary battery. It can be used for either a negative electrode or a positive electrode. The electrode mixture sheet is particularly suitable for a lithium ion secondary battery.

[0294] The present disclosure also provides an electrode comprising the TFE-based polymer composition of the present disclosure or the binder of the present disclosure, an electrode active material, and a current collector. The electrode of the present disclosure has low resistance. Furthermore, even with a small amount of conductive carbon material (conductive additive), good electronic conductivity can be maintained, allowing for the addition of more materials that improve the properties of electrochemical devices, such as active materials and electrolytes.

[0295] The electrode of the present disclosure may include the above-described electrode mixture (preferably an electrode mixture sheet) of the present disclosure and a current collector.

[0296] The electrodes of the present disclosure may be positive electrodes or negative electrodes.

[0297] The positive electrode is preferably composed of a current collector and an electrode mixture sheet containing the positive electrode active material. Examples of materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0298] The density of the positive electrode mixture sheet is preferably 2.80 g / cm ３ More preferably, 3.00 g / cm ３ More preferably, 3.20 g / cm ３ or more, and preferably 3.80 g / cm ３ or less, more preferably 3.75 g / cm ３ More preferably, 3.70 g / cm or less ３ The range is as follows. If the temperature exceeds this range, cracks may easily occur within the sheet. If the temperature falls below this range, the conductivity between the active materials may decrease, increasing the battery resistance and making it difficult to obtain high output.

[0299] The thickness of the positive electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit, and is also preferably 500 μm or less, more preferably 450 μm or less, on one side of the current collector.

[0300] The negative electrode is preferably composed of a current collector and an electrode mixture sheet containing the negative electrode active material. Examples of materials for the negative electrode current collector include metals such as copper, nickel, titanium, tantalum, and stainless steel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly copper, nickel, and alloys thereof, are preferred.

[0301] The density of the negative electrode mixture sheet is preferably 1.3 g / cm ３ More preferably, 1.4 g / cm ３ More preferably, 1.5 g / cm ３ or more, and preferably 2.0 g / cm ３ or less, more preferably 1.9 g / cm３ More preferably, 1.8 g / cm or less ３ The range is as follows. If the temperature exceeds this range, cracks may easily occur within the sheet. If the temperature falls below this range, the conductivity between the active materials may decrease, increasing the battery resistance and making it difficult to obtain high output.

[0302] The thickness of the negative electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit, and is also preferably 500 μm or less, more preferably 450 μm or less, on one side of the current collector.

[0303] Examples of the shape of the current collectors for the positive and negative electrodes include metal foil, expanded metal, punched metal, and foamed metal. Among these, metal foil is preferred. The metal foil may be formed into a mesh shape as appropriate. The thickness of the metal foil is optional, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and is usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, handling may be impaired.

[0304] In addition, it is also preferable that the surface of the current collector is roughened, from the viewpoint of improving the adhesion between the current collector and the positive electrode active material layer and reducing the electrical contact resistance. The surface roughness of the current collector, expressed as Sa (arithmetic mean height), is preferably about 260 nm or more, more preferably about 280 nm or more, and even more preferably about 300 nm or more.

[0305] In addition, it is also preferable that a conductive additive is applied to the surface of the current collector in order to reduce the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive additive include carbon and precious metals such as gold, platinum, and silver. Carbon is particularly preferable because of its small weight.

[0306] The positive and negative electrodes may be produced by a conventional method, for example, by laminating the electrode mixture sheet and a current collector with an adhesive therebetween and pressing the laminate.

[0307] The present disclosure also provides a secondary battery comprising the electrode of the present disclosure described above.

[0308] The secondary battery of the present disclosure may be a secondary battery that uses an electrolytic solution or may be a solid-state secondary battery. Note that in this specification, the solid-state secondary battery may be a secondary battery that contains a solid electrolyte, may be a semi-solid-state secondary battery that contains a solid electrolyte and a liquid component as the electrolyte, or may be an all-solid-state secondary battery that contains only a solid electrolyte as the electrolyte.

[0309] The secondary battery using the above-mentioned electrolyte solution can use the electrolyte solution, separator, etc. used in known secondary batteries, which will be described in detail below.

[0310] The electrolyte is preferably a non-aqueous electrolyte, which may be prepared by dissolving a known electrolyte salt in a known organic solvent for dissolving electrolyte salts.

[0311] The organic solvent for dissolving the electrolyte salt is not particularly limited, and one or more of known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used.

[0312] The electrolyte salt is, for example, LiClO ４ , LiAsF ６ , LiBF ４ , LiPF ６ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２ F ５ ) ２ In particular, LiPF is preferred because of its excellent cycle characteristics. ６ , LiBF ４ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２F ５ ) ２ Or a combination of these is preferred.

[0313] The concentration of the electrolyte salt is preferably 0.8 mol / L or more, more preferably 1.0 mol / L or more. The upper limit depends on the organic solvent used to dissolve the electrolyte salt, but is usually 4.0 mol / L or less.

[0314] A secondary battery using the above-mentioned electrolyte solution preferably further includes a separator. The material and shape of the separator are not particularly limited as long as it is stable to the electrolyte solution and has excellent liquid retention properties, and any known separator can be used. Among them, it is preferable to use a material that is stable to the electrolyte solution, such as resin, glass fiber, or inorganic material, and that is in the form of a porous sheet or nonwoven fabric with excellent liquid retention properties.

[0315] The solid secondary battery is preferably an all-solid-state secondary battery. The solid secondary battery is preferably a lithium-ion battery, and is also preferably a sulfide-based solid secondary battery. The solid secondary battery preferably includes a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode. In the solid secondary battery, the binder of the present disclosure may be used in the electrode layer or the solid electrolyte layer. A solid secondary battery mixture (preferably a mixture sheet) containing the binder and solid electrolyte of the present disclosure, and a solid electrolyte layer (preferably a solid electrolyte layer sheet) containing the binder and solid electrolyte of the present disclosure are also suitable aspects of the present disclosure.

[0316] The solid electrolyte used in the solid secondary battery mixture may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, when a sulfide-based solid electrolyte is used, it has the advantage of being flexible.

[0317] The sulfide-based solid electrolyte is not particularly limited, and may be Li ２ S-P ２ S ５ , Li ２ S-P ２ S ３ , Li ２ S-P ２ S ３ -P ２ S５ , Li ２ S-SiS ２ , LiI-Li ２ S-SiS ２ , LiI-Li ２ S-P ２ S ５ , LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , LiI-Li ２ S-SiS ２ -P ２ S ５ , Li ２ S-SiS ２ -Li ４ SiO ４ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ３ P.S. ４ -Li ４ GeS ４ , Li ３．４ P ０．６ Si ０．４ S ４ , Li ３．２５ P ０．２５ Ge ０．７６ S ４ , Li ４－ｘ Ge １－ｘ P ｘ S ４ (x=0.6~0.8), Li ４＋ｙ Ge １－ｙ Ga ｙ S ４ (y=0.2-0.3), LiPSCl, LiCl, Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦-0.25x+0.5), Li １０ SnP ２ S １２ Any one selected from the above, or a mixture of two or more thereof, can be used.

[0318] The sulfide-based solid electrolyte preferably contains lithium. Sulfide-based solid electrolytes containing lithium are used in solid-state batteries that use lithium ions as a carrier, and are particularly preferred in terms of electrochemical devices having high energy density.

[0319] The oxide-based solid electrolyte is preferably a compound that contains oxygen atoms (O), has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0320] Specific examples of the compound include Li ｘａ La ｙａ TiO ３ [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li ｘｂ La ｙｂ Zr ｚｂ M ｂｂ ｍｂ O ｎｂ (M ｂｂ is at least one element selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, where xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20.), Li ｘｃ B ｙｃ M ｃｃ ｚｃ O ｎｃ (M ｃｃ is at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, where xc satisfies 0≦xc≦5, yc satisfies 0≦yc≦1, zc satisfies 0≦zc≦1, and nc satisfies 0≦nc≦6.), Li ｘｄ (Al, Ga) ｙｄ (Ti, Ge) ｚｄ Si ａｄ P ｍｄ O ｎｄ (where 1≦xd≦3, 0≦yd≦2, 0≦zd≦2, 0≦ad≦2, 1≦md≦7, 3≦nd≦15), Li （３－２ｘｅ） M ｅｅ ｘｅ D ｅｅ O(xe represents a number between 0 and 0.1, and M ｅｅrepresents a divalent metal atom. ｅｅ represents a halogen atom or a combination of two or more halogen atoms.), Li ｘｆ Si ｙｆ O ｚｆ (1≦xf≦5, 0<yf≦3, 1≦zf≦10), Li ｘｇ S ｙｇ O ｚｇ (1≦xg≦3, 0<yg≦2, 1≦zg≦10), Li ３ BO ３ -Li ２ SO ４ , Li ２ Alumni ２ O ３ -P ２ O ５ , Li ２ O—SiO ２ , Li ６ BaLa ２ Ta ２ O １２ , Li ３ P.O. （４－３／２ｗ） N ｗ (w is w<1), Li having a LISICON (Lithium super ionic conductor) type crystal structure ３．５ Zn ０．２５ GeO ４ , La having a perovskite crystal structure ０．５１ Li ０．３４ TiO ２．９４ , La ０．５５ Li ０．３５ TiO ３ , LiTi having a NASICON (sodium super ionic conductor) type crystal structure ２ P ３ O １２ , Li １＋ｘｈ＋ｙｈ (Al, Ga) ｘｈ (Ti, Ge) ２－ｘｈ Si ｙｈ P ３－ｙｈ O １２ (where 0≦xh≦1, 0≦yh≦1), Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２Also, ceramic materials in which elements are substituted for LLZ are known. For example, Li ６．２４ La ３ Zr ２ Al ０．２４ O １１．９８ , Li ６．２５ Al ０．２５ La ３ Zr ２ O １２ and Li substituted with Ta ６．６ La ３ Zr １．６ Ta ０．４ O １２ , Nb-substituted Li ６．７５ La ３ Zr １．７５ Nb ０．２５ O １２ Other examples include LLZ-based ceramic materials in which at least one element of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) is substituted for LLZ. Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ P.O. ４ ), LiPON, LiPOD, in which some of the oxygen in lithium phosphate is replaced with nitrogen １ (D １ is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. １ ON (A １ is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used. ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ -GeO ２ , Li ２ O-Al ２ O ３ -SiO ２ -P２ O ５ -TiO ２ etc.

[0321] The oxide-based solid electrolyte preferably contains lithium. The oxide-based solid electrolyte containing lithium is used in a solid-state battery that uses lithium ions as a carrier, and is particularly preferred in terms of electrochemical devices having a high energy density.

[0322] The oxide-based solid electrolyte is preferably an oxide having a crystalline structure. Oxides having a crystalline structure are particularly preferred in terms of good Li ion conductivity. Examples of oxides having a crystalline structure include perovskite-type (La ０．５１ Li ０．３４ TiO ２．９４ ), NASICON type (Li １．３ Al ０．３ Ti １．７ (P.O. ４ ) ３ etc.), garnet type (Li ７ La ３ Zr ２ O １２ (LLZ), etc. Among these, garnet type is preferred.

[0323] The solid secondary battery may include a separator between the positive electrode and the negative electrode. Examples of the separator include a porous membrane such as polyethylene or polypropylene; a nonwoven fabric made of a resin such as polypropylene; and a nonwoven fabric such as a glass fiber nonwoven fabric.

[0324] The solid secondary battery may further include a battery case. The shape of the battery case is not particularly limited as long as it can accommodate the above-mentioned positive electrode, negative electrode, solid electrolyte layer, etc., but specific examples include a cylindrical shape, a square shape, a coin shape, and a laminate shape.

[0325] The solid secondary battery can be produced, for example, by stacking a positive electrode, a solid electrolyte layer sheet, and a negative electrode in this order and pressing them together.

[0326] 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.

[0327] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0328] Various physical properties were measured by the following methods.

[0329] <Average primary particle size> Measured by dynamic light scattering. An aqueous fluoropolymer dispersion adjusted to a fluoropolymer solids concentration of approximately 1.0% by mass was prepared, and measurements were taken at 25°C using an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) for a total of 70 measurements. The refractive index of the solvent (water) was 1.3328, and the viscosity of the solvent (water) was 0.8878 mPa s.

[0330] <Polymer Solids Concentration> 1 g of the TFE-based polymer aqueous dispersion was dried in a blower dryer at 150°C for 60 minutes, and the ratio of the mass of the heating residue to the mass (1 g) of the aqueous dispersion was expressed as a percentage and used as the solids concentration.

[0331] <Endothermic Peak Temperature> A TFE-based polymer composition that had not been heated to a temperature of 300° C. or higher was subjected to differential scanning calorimetry (DSC) at a heating rate of 10° C. / min, and the temperature corresponding to the minimum point in the heat of fusion curve obtained was taken as the endothermic peak temperature. When there were two or more minimum points in one melting peak, each of them was taken as the endothermic peak temperature.

[0332] <Standard Specific Gravity (SSG)> Using a sample molded in accordance with ASTM D4895 89, the standard specific gravity was measured by the water displacement method in accordance with ASTM D 792.

[0333] <Water Content> About 20 g of a TFE-based polymer composition was heated at 150°C for 2 hours, and the mass was measured before and after, and the water content was calculated according to the following formula. A sample was taken three times, and the water content was calculated for each sample, and the average water content was calculated and used. Water content (mass%) = [(mass (g) of TFE-based polymer composition before heating) - (mass (g) of TFE-based polymer composition after heating)] / (mass (g) of TFE-based polymer composition before heating) x 100

[0334] <0.1% Mass Loss Temperature> Approximately 10 mg of a TFE-based polymer composition that had not been heated to a temperature of 300° C. or higher was precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (thermogravimetric simultaneous differential thermal analyzer). The 0.1% mass loss temperature was determined as the temperature at which a weight loss of 0.1 mass% occurred when the aluminum pan was heated in an air atmosphere in a temperature range from 25° C. to 600° C. at a rate of 10° C. / min.

[0335] <1.0% Mass Loss Temperature> Approximately 10 mg of a TFE-based polymer composition that had not been heated to a temperature of 300° C. or higher was precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (differential thermal / thermogravimetric simultaneous analyzer). The 1.0% mass loss temperature was determined as the temperature at which a weight loss of 1.0 mass% occurred when the aluminum pan was heated in an air atmosphere in a temperature range from 25° C. to 600° C. at a rate of 10° C. / min.

[0336] <Thermal Instability Index (TII)> Measured in accordance with ASTM D 4895-89.

[0337] <Content of specific fluorine-containing compounds> The content was measured using liquid chromatography mass spectrometry under the following conditions.

[0338] [Method for measuring the content of the compound represented by general formula (1)] Extraction from composition 10 g (12.6 mL) of methanol was added to 1 g of the composition, and the mixture was subjected to ultrasonic treatment for 60 minutes to extract the supernatant containing the compound represented by general formula (1). The obtained extract was appropriately concentrated with a nitrogen purge to obtain a concentrated extract.

[0339] Measurement of the Content of the Compound Represented by General Formula (1) in the Extract The content of the compound represented by general formula (1) in the extract was determined by converting it into perfluorooctanoic acid.

[0340] Calibration curve of perfluorooctanoic acid Five levels of methanol standard solutions of perfluorooctanoic acid with known concentrations ranging from 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). Using a first-order approximation from the concentration of each sample and the peak integral value, a and b were calculated using the following relational expression (1): A = a × X + b (1) A: peak area of ​​perfluorooctanoic acid X: concentration of perfluorooctanoic acid (ng / mL)

[0341] Measurement equipment configuration and LC-MS measurement conditions

[0342] MRM measurement parameters

[0343] Content of Compounds Represented by General Formula (1) Having 4 to 20 Carbon Numbers in the Extract Using a liquid chromatograph mass spectrometer, the amount of compounds represented by general formula (1) having 4 to 20 carbon atoms was measured. For the extracted liquid phase, the peak areas of the compounds represented by general formula (1) having each carbon number were determined using the MRM method.

[0344] MRM measurement parameters

[0345] The content of the compound represented by general formula (1) and having a carbon number of (m+1) in the extract was calculated using the following formula (3). a and b in formula (3) were determined from formula (1). XCm = ((ACm-b) / a) x ((50 x m+45) / 413) (3) XCm: content (ng / mL) of the compound represented by general formula (1) and having a carbon number of (m+1) in the extract solution ACm: peak area of ​​the compound represented by general formula (1) and having a carbon number of (m+1) in the extract solution The quantitation limit for this measurement is 1 ng / mL.

[0346] Content of Compounds Represented by General Formula (1) and Having Carbon Number (m+1) Included in Composition The content of compounds represented by general formula (1) and having carbon number (m+1) included in the composition was calculated by the following formula (4): YCm=XCm×12.6 (4) YCm: Content of compounds represented by general formula (1) and having carbon number (m+1) included in the composition (ppb relative to TFE-based polymer) The lower limit of quantitation is 10 ppb by mass.

[0347] [Method for measuring the content of the compound represented by general formula (2)] Extraction from composition 10 g (12.6 mL) of methanol was added to 1 g of the composition, and the mixture was subjected to ultrasonic treatment for 60 minutes to extract the supernatant containing the compound represented by general formula (2). The obtained extract was appropriately concentrated with a nitrogen purge to obtain a concentrated extract.

[0348] Measurement of the Content of the Compound Represented by General Formula (2) in the Extract The content of the compound represented by general formula (2) in the extract was determined by converting it into perfluorooctanesulfonic acid.

[0349] Calibration curve of perfluorooctanesulfonic acid Five levels of methanol standard solutions of perfluorooctanesulfonic acid with known concentrations ranging from 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). Using a first-order approximation from the concentration of each sample and the peak integral value, a and b were calculated using the following relational expression (1): A = a × X + b (1) A: peak area of ​​perfluorooctanesulfonic acid X: concentration of perfluorooctanesulfonic acid (ng / mL)

[0350] Measurement equipment configuration and LC-MS measurement conditions

[0351] MRM measurement parameters

[0352] Content of Compounds Represented by General Formula (2) Having 4 to 20 Carbon Numbers in the Extract The amount of compounds represented by general formula (2) having 4 to 20 carbon atoms was measured using a liquid chromatograph mass spectrometer. The peak areas of the compounds represented by general formula (2) having each carbon number were determined for the extracted liquid phase using the MRM method.

[0353] MRM measurement parameters

[0354] The content of the compound represented by general formula (2) and having carbon number n in the extract was calculated using the following formula (3). a and b in formula (3) were determined from formula (1). XSn = ((ASn - b) / a) × ((50 × n + 81) / 499) (3) XSn: content (ng / mL) of the compound represented by general formula (2) and having carbon number n in the extract solution ASn: peak area of ​​the compound represented by general formula (2) and having carbon number n in the extract solution The quantitation limit for this measurement is 1 ng / mL.

[0355] Content of Compound Represented by General Formula (2) and Having Carbon Number n Included in Composition The content of the compound represented by General Formula (2) and having carbon number n included in the composition was calculated by the following formula (4): YSn=XSn×12.6 (4) YSn: Content of compound represented by General Formula (2) and having carbon number n included in the composition (ppb relative to TFE-based polymer) The lower limit of quantitation is 10 ppb by mass.

[0356] In Preparation Examples 1 to 5, multi-walled carbon nanotubes (manufactured by Sigma-Aldrich, diameter 10-20 nm, surface area 233 m) were used as the conductive carbon material. ２ / g or more, length 10-30 μm), and in Preparation Example 7, carbon black (Super-P Li manufactured by IMERYS, surface area 62 m ２ / g) was used.

[0357] Preparation Example 1: 0.273 g of lauric acid was added to 16 g of deionized water, and 2.77 g of a 2.8% aqueous solution of ammonia was gradually added while stirring to obtain aqueous solution C. 10 g of lauric acid was added to 100 g of deionized water, and 25 g of a 10% aqueous solution of ammonia was gradually added while stirring to obtain aqueous solution D. The pH at this time was 9.6.

[0358] Production Example 1: 1748 g of deionized water, 90 g of paraffin wax, the aqueous solution C obtained in Preparation Example 1, and 0.5 g of ammonium oxalate were added to a 3 L stainless steel reactor equipped with a stirrer. The pH of the aqueous dispersion at this time was 9.0. The reactor was sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 70°C, 2.0 g of HFP was added, and the pressure was increased to 2.70 MPa with TFE. When a 0.5% by mass aqueous potassium permanganate solution was continuously charged into the reactor as a polymerization initiator, a decrease in pressure occurred, and the reaction began. TFE was charged so that the reaction pressure was constant at 2.70 MPa. When 80 g of TFE was charged, stirring was stopped, and the reaction pressure was reduced to atmospheric pressure. Immediately, the reactor was filled with TFE, the reaction pressure was adjusted to 2.70 MPa, stirring was resumed, and the reaction was continued. At the same time, the aqueous solution D obtained in Preparation Example 1 was continuously charged into the reactor. When 680 g of TFE was charged, stirring was stopped, and the reactor was depressurized to atmospheric pressure. By the end of the reaction, 56.0 g of an aqueous potassium permanganate solution and 26.2 g of aqueous solution D were charged. The aqueous dispersion was taken out of the reactor, cooled, and the paraffin wax was separated to obtain a TFE-based polymer aqueous dispersion A. The pH of the obtained TFE-based polymer aqueous dispersion A was 8.8, the solid content was 27.1 mass%, and the primary particle size was 220 nm.

[0359] The obtained TFE-based polymer aqueous dispersion A was diluted with deionized water to a solids concentration of 13% by mass, and the dilution was vigorously stirred in a container equipped with a stirrer to solidify, and then the water was filtered off to obtain a wet powder. The obtained wet powder was dried at 210°C for 18 hours to obtain a TFE-based polymer powder. The obtained TFE-based polymer powder had a standard specific gravity of 2.170, a thermal instability index of 44, an HFP content of 0.002% by mass, a 0.1% by mass loss temperature of 391°C, a 1.0% by mass loss temperature of 491°C, and an endothermic peak temperature of 342°C. (H-(CF ２ ) ｎ -SO ３ The H content (where n is 4 to 20) was less than 10 ppb by mass / polymer.

[0360] Preparation Example 1 A conductive carbon material and pure water were added and stirred for 3 minutes using a rotary / revolving mixer (KK-100W, manufactured by KURABO) under conditions of revolution 680 rpm / rotation 511 rpm, to prepare a conductive carbon material dispersion with a solids concentration of 10% by mass. The conductive carbon material dispersion was mixed with the TFE-based polymer aqueous dispersion A obtained in Preparation Example 1 so that the mass ratio of the TFE-based polymer to the conductive carbon material was 95:5, and deionized water was further added to adjust the solids concentration (total of the conductive carbon material and the TFE-based polymer) to 10% by mass. The prepared aqueous dispersion was added to a coagulation tank equipped with a stirring blade and a baffle, and nitric acid was added as a coagulant. The mixture was stirred and coagulated to obtain a wet powder. The obtained wet powder was dried at 210°C for 18 hours to obtain TFE-based polymer composition 1. The obtained TFE-based polymer composition 1 had a water content of 0.001% by mass and a water content of (H-(CF ２ ) ｎ -SO ３ The (H—(CF) content (where n is 4 to 20) of TFE-based polymer composition 1 was less than 10 mass ppb / polymer. ２ ) ｍ－１ The content of —COO)H (where m is 14 to 17) is shown in Table 7.

[0361] Preparation Example 2 A TFE-based polymer composition 2 was obtained in the same manner as in Preparation Example 1, except that the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 80:20. The water content of the obtained TFE-based polymer composition 2 was 0.002 mass%, and the (H-(CF ２ ) ｎ -SO ３ The (H—(CF) content (where n is 4 to 20) of TFE-based polymer composition 2 was less than 10 mass ppb / polymer. ２ ) ｍ－１ The content of —COO)H (where m is 14 to 17) is shown in Table 7.

[0362] Preparation Example 3 A TFE-based polymer composition 3 was obtained in the same manner as in Preparation Example 1, except that the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 60:40. The water content of the obtained TFE-based polymer composition 3 was 0.002 mass%, and the (H-(CF ２ ) ｎ -SO３ The (H—(CF) content (where n is 4 to 20) of TFE-based polymer composition 3 was less than 10 mass ppb / polymer. ２ ) ｍ－１ The content of —COO)H (where m is 14 to 17) is shown in Table 7.

[0363] Preparation Example 2 A mixture of 10-undecen-1-ol (16 g), 1,4-benzoquinone (10.2 g), DMF (160 mL), water (16 mL), and PdCl2 (0.34 g) was heated and stirred at 90°C for 12 hours. The solvent was then distilled off under reduced pressure. The resulting residue was purified by liquid separation and column chromatography to obtain 11-hydroxyundecan-2-one (15.4 g). A mixture of 11-hydroxyundecan-2-one (13 g), sulfur trioxide triethylamine complex (13.9 g), and tetrahydrofuran (140 mL) was stirred at 50°C for 12 hours. A solution of sodium methoxide (3.8 g) / methanol (12 mL) was added dropwise to the reaction solution. The precipitated solid was filtered under reduced pressure and washed with ethyl acetate to obtain sodium 10-oxoundecyl sulfate (15.5 g) (hereinafter referred to as surfactant A). 588.6 g of deionized water and 70.0 g of surfactant A were added to a 1 L glass reactor equipped with a stirrer, the reactor was sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 90 ° C and pressurized to 0.4 MPaG with nitrogen. 41.4 g of ammonium persulfate (APS) was added and stirred for 3 hours. Stirring was stopped, and the reactor was depressurized to atmospheric pressure and cooled to obtain an aqueous surfactant solution B.

[0364] Production Example 2 3600 g of deionized and degassed water, 180 g of paraffin wax, and 0.540 g of surfactant A were added to a 6 L stainless steel reactor equipped with a stirrer, the reactor was sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 70 ° C., TFE was charged into the reactor, and the reactor pressure was adjusted to 2.70 MPa. 0.620 g of ammonium persulfate (APS) and 1.488 g of disuccinic acid peroxide (DSP) were charged as polymerization initiators. TFE was charged so that the reaction pressure was constant at 2.70 MPa. Simultaneously with the start of charging TFE, continuous charging of surfactant aqueous solution B was started. When 540 g of TFE was charged, 20 g of deionized and deaerated water dissolving 0.76 g of hydroquinone was added, and when 1,200 g of TFE was charged, stirring was stopped and the reactor was depressurized until atmospheric pressure was reached. By the end of the reaction, 103 g of aqueous surfactant solution B had been charged. The contents were removed from the reactor and cooled, and then the paraffin wax was separated to obtain a TFE-based polymer aqueous dispersion B. The solid content of the obtained TFE-based polymer aqueous dispersion B was 25.9 mass %, and the average primary particle diameter was 290 nm.

[0365] The TFE polymer aqueous dispersion B obtained is diluted with deionized water to a solid content concentration of 13% by mass, and is vigorously stirred in a container equipped with a stirrer to be solidified, and then is filtered out from water to obtain wet powder.The obtained wet powder is dried at 210 ℃ for 18 hours to obtain TFE polymer powder.The standard specific gravity of the obtained TFE polymer powder is 2.151, the thermal instability index is 42, the 0.1% mass reduction temperature is 397 ℃, the 1.0% mass reduction temperature is 492 ℃, and the endothermic peak temperature is 344 ℃.

[0366] Preparation Example 4 A TFE-based polymer composition 4 was obtained in the same manner as in Preparation Example 1, except that the TFE aqueous dispersion prepared in Preparation Example 2 was used and the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 80:20. The water content of the obtained TFE-based polymer composition 4 was 0.002 mass%, (H-(CF ２ ) ８ -SO ３ The (H-(CF) content of TFE-based polymer composition 4 was 1,130 mass ppb. ２ ) ｍ－１The content of —COO)H (where m is 14 to 17) is shown in Table 7.

[0367] Preparation Example 3 A white solid A was obtained by the method described in Synthesis Example 1 of WO 2021 / 045228.

[0368] Production Example 3: A 6-liter SUS autoclave equipped with a stirring blade and a temperature-controlling jacket was charged with 3,480 g of deionized water, 100 g of paraffin wax, and 5.3 g of white solid A. The autoclave was heated to 70 ° C. while purging with nitrogen gas to remove oxygen. TFE was injected to adjust the system pressure to 0.78 MPaG, and the system temperature was maintained at 70 ° C. while stirring. Next, an aqueous solution containing 15.0 mg of ammonium persulfate dissolved in 20 g of water was injected with TFE to initiate the polymerization reaction. As the polymerization reaction progressed, the system pressure decreased, but TFE was added to maintain the system temperature at 70 ° C. and the system pressure at 0.78 MPaG. When 400 g of TFE had been consumed from the start of polymerization, an aqueous solution containing 18.0 mg of hydroquinone dissolved in 20 g of water as a radical scavenger was injected with TFE. The polymerization continued thereafter, and when the polymerization amount of TFE reached about 1200 g from the start of polymerization, stirring and the supply of TFE were stopped, and the gas in the system was immediately released to normal pressure, and the polymerization reaction was terminated. The aqueous dispersion was taken out and cooled, and then the paraffin wax was separated, to obtain a TFE-based polymer aqueous dispersion X. The average primary particle diameter of the obtained TFE-based polymer aqueous dispersion X was 310 nm, and the solid content concentration was 25.3 mass%.

[0369] The obtained TFE-based polymer aqueous dispersion X is diluted with deionized water to a solid content concentration of 13% by mass, and is vigorously stirred in a container equipped with a stirrer to solidify, and then filtered out from the water to obtain wet powder.The obtained wet powder is dried at 210 ° C for 18 hours to obtain TFE-based polymer powder.The standard specific gravity of the obtained TFE-based polymer powder is 2.156, and the thermal instability index is 0.

[0370] Preparation Example 5 A TFE-based polymer composition X having a mass ratio of TFE-based polymer to conductive carbon material of 95:5 was obtained in the same manner as in Preparation Example 1, except that the TFE aqueous dispersion X prepared in Preparation Example 3 was used. The water content of the obtained TFE-based polymer composition X was 0.000 mass% and the (H-(CF２ ) ｍ－１ -COO)H content (where m is 4 to 20), (H-(CF ２ ) ｎ -SO ３ The content of H (where n is 4 to 20) was less than 10 ppb by mass.

[0371] Preparation Example 6 The TFE aqueous dispersion X prepared in Preparation Example 3 was diluted to a solids concentration of 13% by mass, stirred and coagulated to obtain a wet powder. The obtained wet powder was dried at 180°C for 18 hours to obtain a TFE-based polymer composition Y. The water content of the obtained TFE-based polymer composition Y was 0.000% by mass, and the (H-(CF ２ ) ｍ－１ -COO)H content (where m is 4 to 20), (H-(CF ２ ) ｎ -SO ３ The content of H (where n is 4 to 20) was less than 10 ppb by mass.

[0372] Preparation Example 7 TFE-based polymer composition 5 was obtained in the same manner as in Preparation Example 1, except that the conductive carbon material was changed from multi-walled carbon nanotubes to carbon black and the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 33:67. The water content of the obtained TFE-based polymer composition 5 was 0.002 mass% and (H-(CF ２ ) ｎ -SO ３ The (H—(CF) content (where n is 4 to 20) of TFE-based polymer composition 5 was less than 10 mass ppb / polymer. ２ ) ｍ－１ The content of —COO)H (where m is 14 to 17) is shown in Table 7.

[0373]

[0374] Table 8 shows the composition ratio of the TFE polymer compositions obtained in each production example.

[0375] Each of the TFE polymer compositions obtained above was evaluated by the following methods.

[0376] The powder fluidity of Examples A1 to A5 and Comparative Examples A1 and A2 was evaluated according to the following procedure. <Powder fluidity evaluation> Powder fluidity was measured using a TFE-based polymer composition. Stainless steel funnels with different diameters were prepared. The TFE-based polymer compositions (50 g each) were passed through the funnels, and an evaluation was made as to whether the compositions fell without clogging. The results are shown in Table 9.

[0377]

[0378] Evaluation of Electrode Mixture Sheets for Electrolyte-Containing Batteries Mixture sheets of Examples B1 to B5 and Comparative Examples B1 and B2 were prepared and evaluated according to the following procedures.

[0379] <Preparation of Positive Electrode Mixture Sheet> The active material, conductive carbon material, and binder (TFE-based polymer composition) were weighed and placed in a container. The mixture was heated sufficiently in a constant temperature bath at 50 ° C., and immediately placed in a high-speed fluid mixer and stirring was initiated. By processing at 3000 rpm for 30 minutes, the dispersion of each material and fibrillation of the TFE-based polymer composition were performed, and a mixture was obtained. The mixture was then placed in a mixer (WDL-1 manufactured by Osaka Chemical Co., Ltd.) and processed for 2 minutes to pulverize the mixture and obtain an electrode mixture. The electrode mixture was placed between metal rolls arranged in parallel left and right, and an electrode mixture sheet was obtained by rolling while applying shear force (left and right roll temperature: 120 ° C., left roll rotation speed: 1 m / min, right roll rotation speed: 0.4 m / min). Table 10 shows the material type and composition.

[0380] *The composition ratio of the TFE-based polymer composition was adjusted so that the total amount of the conductive carbon material was 1.7 mass %.

[0381] <Preparation of Positive Electrode> A commercially available carbon-coated aluminum foil with a thickness of 20 μm was prepared as a current collector. A positive electrode mixture sheet was placed on the carbon-coated aluminum foil, and the positive electrode mixture sheet and the current collector were bonded together using a roll press heated to 100° C. The sheet was then cut to a desired size and tabbed to form a positive electrode.

[0382] <Preparation of Negative Electrode> 98 parts by mass of a carbonaceous material (graphite) was mixed with 1 part by mass of an aqueous dispersion of sodium carboxymethyl cellulose (concentration of sodium carboxymethyl cellulose: 1% by mass) and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) as a thickener and binder, and the mixture was mixed in a disperser to form a slurry. The resulting slurry was applied to a copper foil with a thickness of 10 μm, dried, rolled in a press, cut to the desired size, and tabbed to form a negative electrode.

[0383] <Preparation of Electrolyte Solution> A mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC:EMC = 30:70 (volume ratio)) was weighed into a sample bottle as an organic solvent, and 1% by mass each of fluoroethylene carbonate (FEC) and vinylene carbonate (VC) was dissolved therein to prepare a mixed solution. LiPF was added to this mixed solution so that the concentration in the electrolyte solution was 1.1 mol / L. ６ The salts were mixed at 23° C. to obtain a non-aqueous electrolyte solution.

[0384] <Preparation of Aluminum Laminate Cell> The above positive electrode was placed opposite to the negative electrode via a 20 μm-thick microporous polyethylene film (separator), and the nonaqueous electrolyte solution obtained above was poured into the cell. After the nonaqueous electrolyte solution had sufficiently permeated the separator and the like, the cell was sealed to prepare a lithium ion secondary battery.

[0385] <DC Resistance Evaluation> The lithium-ion secondary battery fabricated as described above was sandwiched between plates and pressurized. At 25°C, it was subjected to constant-current-constant-voltage charging (hereinafter referred to as CC / CV charging) at a current equivalent to 0.1 C up to 4.2 V. After a 0.05 C cut, it was discharged to 3 V at a constant current of 1 C. This cycle constituted one cycle, and three charge / discharge cycles were performed. Here, 1 C represents the current value required to discharge the battery's reference capacity in one hour; for example, 0.2 C represents one-fifth of that current value. After three cycles, the battery was fully charged, rested for 30 minutes, and then discharged at 1 C for five seconds. From the voltage drop ΔV, the battery's DC resistance (DC-IR) was calculated using Ohm's law: R [Ω] = ΔV [V] / 1 C current [A]. The resistance value of Comparative Example B2 was set to 100, and Examples B1 to B5 and Comparative Example B1 were evaluated relative to each other. The results are shown in Table 11.

[0386]

Claims

1. A tetrafluoroethylene-based polymer composition used as a binder for an electrochemical device, comprising a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. General formula (1): (H-(CF ２ )) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ )) ｎ -SO ３ )) ｑ M ２ (wherein n is 4 to 20. M ２ is H, a metal atom, NR ５ ４ (R ５ is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.) 2. The tetrafluoroethylene-based polymer composition according to claim 1, wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of a polymerization unit based on tetrafluoroethylene units and hexafluoropropylene.

3. The tetrafluoroethylene-based polymer composition according to claim 1 or 2, wherein the amount of the tetrafluoroethylene-based polymer with respect to the solid content in the tetrafluoroethylene-based polymer composition is 55% by mass or more and 96% by mass or less.

4. The tetrafluoroethylene-based polymer composition according to any one of claims 1 to 3, which is a powder.

5. The tetrafluoroethylene-based polymer composition according to any one of claims 1 to 4, which is used as a binder for a lithium-ion secondary battery.

6. A binder for an electrochemical device consisting essentially of a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition comprises a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, and the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. General formula (1): (H-(CF ２ )) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different, and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ )) ｎ -SO ３ )) ｑ M ２ (wherein n is 4 to 20. M ２ is H, a metal atom, NR ５ ４ (R ５ is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.) 7. The binder for an electrochemical device according to claim 6, wherein the amount of the tetrafluoroethylene-based polymer with respect to the solid content in the tetrafluoroethylene-based polymer composition is 30% by mass or more.

8. The binder for an electrochemical device according to claim 6 or 7, wherein the amount of the tetrafluoroethylene-based polymer with respect to the solid content in the tetrafluoroethylene-based polymer composition is 55% by mass or more and 96% by mass or less.

9. The binder for an electrochemical device according to any one of claims 6 to 8, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.

10. The binder for an electrochemical device according to any one of claims 6 to 9, wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of a polymerization unit based on tetrafluoroethylene units and hexafluoropropylene.

11. The binder for an electrochemical device according to any one of claims 6 to 10, wherein the conductive carbon material is a carbon nanotube.

12. The binder for an electrochemical device according to any one of claims 6 to 11, wherein the amount of the conductive carbon material with respect to the solid content in the tetrafluoroethylene-based polymer composition is 1 to 70% by mass.

13. The binder for an electrochemical device according to any one of claims 6 to 12, wherein the tetrafluoroethylene-based polymer composition is substantially free of moisture.

14. The binder for an electrochemical device according to any one of claims 6 to 13, wherein the tetrafluoroethylene-based polymer composition substantially does not contain a compound represented by the following general formula (3). General formula (3): (H-(CF ２ )) ８ -SO ３ )( ｑ M ２ (In the formula, M ２ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.) 15. The tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of the compound represented by the following general formula (4) and the compound represented by the following general formula (4'), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. The binder for an electrochemical device according to any one of claims 6 to 14. General formula (4): (H-(CF ２ )) １５ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (4'): (H-(CF ２ )) １６ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) 16. The tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of the compound represented by the following general formula (5) and the compound represented by the following general formula (5'), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. The binder for an electrochemical device according to any one of claims 6 to 15. General formula (5): (H-(CF ２ ) １３ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (5'): (H-(CF ２ ) １４ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) 17. The binder for an electrochemical device according to any one of claims 6 to 16, wherein the thermal instability index (TII) of the tetrafluoroethylene-based polymer composition is 5 or more.

18. The binder for an electrochemical device according to any one of claims 6 to 17, which is a powder.

19. The binder for an electrochemical device according to any one of claims 6 to 18, which is for a lithium-ion secondary battery.

20. An electrode mixture containing the tetrafluoroethylene-based polymer composition according to any one of claims 1 to 5, or the binder for an electrochemical device according to any one of claims 6 to 19, and an electrode active material.

21. The electrode mixture according to claim 20, which is a sheet.

22. An electrode containing the tetrafluoroethylene-based polymer composition according to any one of claims 1 to 5, or the binder for an electrochemical device according to any one of claims 6 to 19, an electrode active material, and a current collector.

23. A secondary battery comprising the electrode according to claim 22.

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