Polymer composition, binder for electrochemical device, electrode mixture, electrode, and secondary battery

Abstract

The present invention provides: a polymer composition for a binder for an electrochemical device, with which it is possible to improve the coulombic efficiency of an electrochemical device; and the like. The present invention specifically provides a polymer composition which is used for a binder for an electrochemical device, and which contains a fibrillatable polymer, a thermoplastic polymer, and at least one compound that is selected from the group consisting of a compound represented by general formula (1) and a compound represented by general formula (2). General formula (1): (H-(CF2)m−1-COO)pM1 (In the formula, m is 4 to 20, M1 is H, a metal atom, NR5 4 (wherein the R5 moieties may be the same or different, and each represents H or an organic group having 1 to 10 carbon atoms), or the like, and p is 1 or 2.) General formula (2): (H-(CF2)n-SO3)qM2 (In the formula, n is 4 to 20, M2 is H, a metal atom, NR5 4 (wherein the R5 moieties are as defined above), or the like, and q is 1 or 2.)

Description

Polymer composition, binder for electrochemical device, electrode mixture, electrode, and secondary battery

[0001] The present disclosure relates to a 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 Document 1 describes an energy storage device in which at least one of the cathode and the anode contains a polytetrafluoroethylene mixed binder material.

[0004] Patent Documents 2 to 6 describe the use of polytetrafluoroethylene as a binder for batteries.

[0005] Patent Documents 7 to 9 describe composite binders of polytetrafluoroethylene and polyvinylidene fluoride or the like.

[0006] Patent Publication No. 2017-517862 International Publication No. 2021 / 181887 International Publication No. 2021 / 181888 International Publication No. 2021 / 192541 International Publication No. 2022 / 138942 International Publication No. 2022 / 138939 International Publication No. 2023 / 286787 International Publication No. 2022 / 234227 International Publication No. 2023 / 094623

[0007] An object of the present disclosure is to provide a polymer composition for a binder for an electrochemical device that can improve the Coulombic efficiency of an electrochemical device, as well as a binder for an electrochemical device, an electrode mixture, an electrode, and a secondary battery that use the same.

[0008] The present disclosure (1) is a polymer composition used in a binder for an electrochemical device, the polymer composition comprising a fibrillating polymer, a thermoplastic polymer, and 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): 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 (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0009] The present disclosure (2) is a polymer composition used in a binder for an electrochemical device, the polymer composition comprising a fibrillating polymer and a thermoplastic polymer, wherein the thermal instability index (TII) of the fibrillating polymer is 10 or more.

[0010] The present disclosure (3) is the polymer composition according to the present disclosure (1) or (2), wherein the fibrillating polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of a tetrafluoroethylene unit and a polymerization unit based on hexafluoropropylene.

[0011] The present disclosure (4) is the polymer composition according to any one of the present disclosures (1) to (3), wherein the content of the fibrillating polymer is more than 50% by mass and not more than 97% by mass relative to the polymer composition.

[0012] The present disclosure (5) is the polymer composition according to any one of the present disclosures (1) to (4), wherein the thermoplastic polymer is at least one vinylidene fluoride-based polymer selected from the group consisting of polyvinylidene fluoride and vinylidene fluoride / tetrafluoroethylene copolymer.

[0013] The present disclosure (6) is a polymer composition according to any one of the present disclosures (1) to (5) in the form of a powder.

[0014] The present disclosure (7) is a polymer composition according to any one of the present disclosures (1) to (6), which is used as a binder for a lithium ion secondary battery.

[0015] The present disclosure (8) is a binder for electrochemical devices consisting essentially of a polymer composition, the polymer composition comprising a fibrillating polymer, a thermoplastic polymer, and 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): 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.

[0016] The present disclosure (9) is a binder for electrochemical devices consisting essentially of a polymer composition, the polymer composition including a fibrillating polymer and a thermoplastic polymer, and the thermal instability index (TII) of the fibrillating polymer is 10 or more.

[0017] The present disclosure (10) is the binder for electrochemical devices according to the present disclosure (8) or (9), wherein the polymer composition has endothermic peaks in the range of 330°C or less and in the range of more than 330°C.

[0018] The present disclosure (11) is the binder for electrochemical devices according to any one of the present disclosures (8) to (10), wherein the endothermic peak temperature of the fibrillating polymer is higher than 330°C.

[0019] The present disclosure (12) is the binder for electrochemical devices according to any one of the present disclosures (8) to (11), in which the fibrillating polymer is a tetrafluoroethylene-based polymer.

[0020] The present disclosure (13) is the binder for electrochemical devices according to any one of the present disclosures (8) to (12), wherein the fibrillating polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of a tetrafluoroethylene unit and a polymerization unit based on hexafluoropropylene.

[0021] The present disclosure (14) is the binder for electrochemical devices according to any one of the present disclosures (8) and (10) to (13), wherein the thermal instability index (TII) of the fibrillating polymer is 10 or more.

[0022] The present disclosure (15) is the binder for electrochemical devices according to any one of the present disclosures (8) to (14), wherein the amount of the thermoplastic polymer relative to the polymer composition is less than 50 mass %.

[0023] The present disclosure (16) is the binder for electrochemical devices according to any one of the present disclosures (8) to (15), wherein the content of the fibrillating polymer is more than 50% by mass and not more than 97% by mass relative to the polymer composition.

[0024] The present disclosure (17) is the binder for electrochemical devices according to any one of the present disclosures (8) to (16), wherein the polymer composition has a 0.1% mass loss temperature of 340° C. or higher.

[0025] The present disclosure (18) is the binder for electrochemical devices according to any one of the present disclosures (8) to (17), wherein the polymer composition has a 1.0% mass loss temperature of 370° C. or higher.

[0026] The present disclosure (19) is the binder for electrochemical devices according to any one of the present disclosures (8) to (16), in which the thermoplastic polymer is a vinylidene fluoride-based polymer.

[0027] The present disclosure (20) is the binder for electrochemical devices according to the present disclosure (19), in which the vinylidene fluoride-based polymer is a fluoroelastomer.

[0028] The present disclosure (21) is the binder for electrochemical devices according to the present disclosure (20), wherein the fluoroelastomer contains vinylidene fluoride units and other monomer units copolymerizable with vinylidene fluoride.

[0029] The present disclosure (22) relates to the binder for electrochemical devices according to the present disclosure (20) or (21), wherein the fluoroelastomer is at least one selected from the group consisting of vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / 2,3,3,3-tetrafluoropropylene copolymer, and vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer.

[0030] The present disclosure (23) is the binder for electrochemical devices according to any one of the present disclosures (8) to (16), wherein the polymer composition has at least an endothermic peak in the range of 130 to 200°C.

[0031] The present disclosure (24) is the binder for electrochemical devices according to any one of the present disclosures (8) to (16), wherein the thermoplastic polymer is at least one vinylidene fluoride-based polymer selected from the group consisting of polyvinylidene fluoride and vinylidene fluoride / tetrafluoroethylene copolymer.

[0032] The present disclosure (25) is the binder for electrochemical devices according to the present disclosure (24), wherein the vinylidene fluoride polymer has an average particle size of 10 μm or less and does not contain a fluorine-containing surfactant.

[0033] The present disclosure (26) is the binder for electrochemical devices according to any one of the present disclosures (8) to (25), wherein the polymer composition has an average aspect ratio of 2.5 or less in powder form.

[0034] The present disclosure (27) is the binder for electrochemical devices according to any one of the present disclosures (8) to (26), in which the powder of the fibrillating polymer is not fibrillated.

[0035] The present disclosure (28) is the binder for electrochemical devices according to any one of the present disclosures (8) to (27), which is in the form of powder.

[0036] The present disclosure (29) is a binder for electrochemical devices according to any one of the present disclosures (8) to (28), which is a binder for lithium ion secondary batteries.

[0037] The present disclosure (30) is an electrode mixture comprising the polymer composition according to any one of the present disclosures (1) to (7) or the binder for electrochemical devices according to any one of the present disclosures (8) to (29), and an electrode active material.

[0038] The present disclosure (31) is the electrode mixture according to the present disclosure (30) in the form of a sheet.

[0039] The present disclosure (32) is an electrode comprising the polymer composition according to any one of the present disclosures (1) to (7) or the binder for electrochemical devices according to any one of the present disclosures (8) to (29), an electrode active material, and a current collector.

[0040] The present disclosure (33) is a secondary battery comprising the electrode according to the present disclosure (32).

[0041] According to the present disclosure, it is possible to provide a polymer composition for a binder for an electrochemical device that can improve the Coulombic efficiency of an electrochemical device, as well as a binder for an electrochemical device, an electrode mixture, an electrode, and a secondary battery that use the same.

[0042] 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.

[0043] The present disclosure will be specifically described below.

[0044] The present disclosure provides a polymer composition for use in a binder for an electrochemical device, the polymer composition comprising a fibrillating polymer, a thermoplastic polymer, and 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) (hereinafter also referred to as polymer composition (1) of the present disclosure). 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.

[0045] The present disclosure also provides a polymer composition used in a binder for an electrochemical device, the polymer composition comprising a fibrillating polymer and a thermoplastic polymer, wherein the fibrillating polymer has a thermal instability index (TII) of 10 or more (hereinafter also referred to as polymer composition (2) of the present disclosure).

[0046] In this specification, unless otherwise specified, the polymer compositions (1) and (2) of the present disclosure will be collectively referred to as the "polymer composition of the present disclosure."

[0047] The polymer composition of the present disclosure, having the above-described configuration, can improve the Coulombic efficiency of electrochemical devices. Furthermore, a mixture sheet can be produced even with a small additive amount. Furthermore, since a mixture sheet with excellent adhesion to a substrate such as a metal foil can be obtained, the mixture sheet and the substrate can be bonded without increasing the density of the mixture layer (without compaction), allowing for processing under a wider range of molding conditions. When the polymer composition of the present disclosure is in powder form, flowability can also be improved. Furthermore, since the polymer composition of the present disclosure can be used in a dry process, there is no need to use large amounts of a dispersion medium such as water or an organic solvent, and a wide range of electrode active materials and solid electrolytes can be selected for combination, which is advantageous in terms of the production process. Furthermore, the process and costs associated with the use of a dispersion medium can be reduced. Furthermore, since the polymer composition of the present disclosure has excellent binding strength with active materials and electrolytes, the amount used can be reduced.

[0048] The polymer composition of the present disclosure includes a fibrillating polymer. A fibrillating polymer is a polymer that easily fibrillates when shear stress is applied. The higher the molecular weight, the easier it is to fibrillate. The molecular weight of the fibrillating polymer is, for example, 500,000 or more, preferably 1,000,000 or more, more preferably 5,000,000 or more, even more preferably 10,000,000 or more, even more preferably 20,000,000 or more, and may be 200,000,000 or less. The molecular weight may be a number average molecular weight (Mn), which can be calculated by the following formula: SSG = -0.0579 log Mn + 2.6113, where SSG is the standard specific gravity of the polymer, and is measured by the water displacement method according to ASTM D 792 using a sample molded in accordance with ASTM D 4895 89.

[0049] The fibrillating polymer preferably has an endothermic peak temperature of more than 330°C, more preferably 333°C or higher, even more preferably 335°C or higher, even more preferably 337°C or higher, particularly preferably 340°C or higher, and preferably 350°C or lower, more preferably 346°C or lower, in order to form a composite sheet having even greater strength. The endothermic peak temperature is the temperature corresponding to the minimum point in the heat of fusion curve obtained by performing differential scanning calorimetry (DSC) at a heating rate of 10°C / min on a fibrillating polymer that has not been heated to a temperature of 300°C or higher. When there are two or more minimum points in one melting peak, each of these is taken as the endothermic peak temperature.

[0050] In the polymer composition (1) of the present disclosure, the fibrillating polymer preferably has a thermal instability index (TII) of 10 or more. In the polymer composition (2) of the present disclosure, the fibrillating polymer has a TII of 10 or more. A fibrillating polymer having a TII of 10 or more can be obtained by using a hydrocarbon-based surfactant. In terms of further improving the Coulomb efficiency of an electrochemical device, further reducing the amount added, further improving the adhesion between a mixture sheet and a substrate, and further improving powder flowability, the TII is more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, even more preferably 30 or more, even more preferably 35 or more, even more preferably 40 or more, and preferably 200 or less, more preferably 100 or less, even more preferably 80 or less, and even more preferably 50 or less. The TII is measured in accordance with ASTM D 4895-89.

[0051] The fibrillating polymer may have a 0.1% mass loss temperature of 400°C or less. A fibrillating 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 fibrillating 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 (thermogravimetric / differential thermal analyzer). The 0.1% mass loss temperature is determined as the temperature at which a 0.1 mass% weight loss occurs when the aluminum pan is heated in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C / min.

[0052] The fibrillating polymer may have a 1.0% mass loss temperature of 492°C or lower. A fibrillating polymer having a 1.0% mass loss temperature of 492°C or lower 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 fibrillating 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 (thermogravimetric / differential thermal analyzer). The 1.0% mass loss temperature is determined as the temperature at which a 1.0 mass% weight loss occurs when the aluminum pan is heated in an air atmosphere over a temperature range of 25°C to 600°C at a rate of 10°C / min.

[0053] Examples of the fibrillating polymer include tetrafluoroethylene (TFE)-based polymers, polyethylene, polyester, liquid crystal polymers (LCP), acrylic resins, etc. As the fibrillating polymer, TFE-based polymers, polyethylene, and polyester are preferred, and TFE-based polymers are more preferred.

[0054] The TFE-based polymer may be a TFE homopolymer, or a TFE copolymer comprising a polymerized unit (TFE unit) based on TFE and a polymerized unit (modified monomer unit) based on a modified monomer copolymerizable with TFE.The TFE-based polymer may be polytetrafluoroethylene (PTFE).The PTFE includes a TFE homopolymer and a modified PTFE comprising 99.0 mass% or more of TFE units and 1.0 mass% or less of modified monomer units.The TFE-based polymer is preferably PTFE, and more preferably modified PTFE, in that it can further improve the Coulomb efficiency of electrochemical devices, can further reduce the amount of addition, can further improve the adhesion between the composite sheet and the substrate, and can further improve powder flowability.In addition, in the present disclosure, the TFE homopolymer refers to one in which the content of modified monomer units relative to the total polymerized units is less than 0.0001 mass%.

[0055] The content of the modified monomer unit is preferably in the range of 0.0001 to 10% by mass relative to the total polymerized units, from the viewpoints of further improving the Coulomb efficiency of the electrochemical device, further reducing the amount added, further improving the adhesion between the composite sheet and the substrate, and further improving the powder flowability. The lower limit of the content of the modified monomer unit is more preferably 0.001% by mass, even more preferably 0.010% by mass, even more preferably 0.015% by mass, and particularly preferably 0.020% by mass. The upper limit of the content of the modified monomer unit is preferably 5.0% by mass, more preferably 3.0% by mass, even more preferably 1.0% by mass, even more preferably 0.80% by mass, even more preferably 0.60% by mass, even more preferably 0.50% by mass, even more preferably 0.40% by mass, even more preferably 0.30% by mass, and particularly preferably 0.20% by mass. In this specification, the modified monomer unit means a part of the molecular structure of a TFE-based polymer that is derived from a modified monomer.

[0056] 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.

[0057] 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); hydrogen-containing fluoroolefin such as trifluoroethylene, vinylidene fluoride (VdF); 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 a plurality of kinds.

[0058] 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 １represents 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.

[0059] 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.

[0060] 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.

[0061] 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:

[0062]

[0063] (wherein m represents 0 or an integer of 1 to 4), Rf １ is of the following formula:

[0064]

[0065] (wherein n represents an integer of 1 to 4).

[0066] The (perfluoroalkyl)ethylene [PFAE] is not particularly limited, and examples thereof include (perfluorobutyl)ethylene [PFBE] and (perfluorohexyl)ethylene.

[0067] 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.

[0068] 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 CF ２ =CF-CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ =CF-CF ２ -O-CF ２ CF ２ CF ３ is more preferred.

[0069] 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. ４is F, Cl, Rf or O-Rf, and Rf is a perfluoroorganic group.

[0070] 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.

[0071] The polar group-containing monomer may be a fluorine-free monomer or a fluorine-containing monomer.

[0072] 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.

[0073] 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)").

[0074] 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.

[0075] 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: ａPreferably, 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.

[0076] 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.

[0077] The modifying monomer (A) may be used alone or in combination of two or more.

[0078] As the modifying monomer (A), a compound having an unsaturated bond can be used.

[0079] 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.

[0080] 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:

[0081] Examples of the perfluorovinyl alkyl compound represented by the formula (4a) include CF ２ =CFCF ２ COOM １ (In the formula, M １ is the same as the definition above.

[0082] 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:

[0083] 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:

[0084] 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 ４It is preferable that:

[0085] 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.

[0086] 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:

[0087] 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 ) COOM1 (in the formula, M １ is the same as the definition above.

[0088] The modified monomer is preferably at least one selected from the group consisting of HFP, PAVE, PFAE, and a monomer having a polar group, from the viewpoints of further improving the Coulomb efficiency of the electrochemical device, further reducing the amount added, further improving the adhesion between the composite sheet and the substrate, and further improving powder flowability. At least one selected from the group consisting of HFP, 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. At least one selected from the group consisting of HFP, PMVE, PPVE, a cyclic non-fluorinated monomer having an acid anhydride residue, and a compound represented by general formula (4e) is even more preferred. At least one selected from the group consisting of HFP, PMVE, and PPVE is even more preferred, and HFP is even more preferred.

[0089] 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.

[0090] 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 a 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 a modified PTFE, for example, there can be mentioned the PTFE described in JP-A-2005-527652.

[0091] 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.

[0092] In terms of being able to further improve the Coulomb efficiency of electrochemical device, being able to further reduce the amount of addition, being able to further improve the adhesion between the composite sheet and the substrate, and being able to further improve powder flowability, the TII of the above-mentioned TFE polymer is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, even more preferably 30 or more, even more preferably 35 or more, particularly preferably 40 or more, and preferably 80 or less, more preferably 50 or less.The TFE polymer with a TII of 10 or more can be obtained by using a hydrocarbon surfactant.

[0093] The TFE-based polymer preferably has a standard specific gravity (SSG) of 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, in order to form a composite sheet with better strength.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.

[0094] In the polymer composition of the present disclosure, it is preferable that the fibrillating polymer is not fibrillated in powder form, in order to further improve powder flowability. The fibrillating polymer being not fibrillated in powder form means that the average aspect ratio of the fibrillating polymer in powder form is 2.5 or less. The average aspect ratio is preferably 2.0 or less, more preferably 1.9 or less, even more preferably 1.8 or less, even more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, even more preferably 1.4 or less, even more preferably 1.3 or less, and even more preferably 1.2 or less. The average aspect ratio may also be 1.0 or more. The above average aspect ratio is determined by spreading the polymer composition powder thinly on a black paper surface with air without applying shear, observing the fibrillating polymer contained in the polymer composition under a microscope, processing the images of 100 or more randomly selected particles, and averaging the ratio of their major axis to their minor axis.

[0095] The content of the fibrillating polymer in the polymer composition of the present disclosure is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, and is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, even more preferably 92% by mass or less, and particularly preferably 90% by mass or less, from the viewpoints of further improving the Coulomb efficiency of the electrochemical device, further reducing the amount added, further improving the adhesion between the composite sheet and the substrate, and further improving the powder fluidity.

[0096] The polymer composition of the present disclosure comprises a thermoplastic polymer, which preferably does not have fibrillating properties.

[0097] The thermoplastic polymer may be a thermoplastic resin or an elastomer.

[0098] The thermoplastic resin preferably has a melting point of 100 ° C. or higher, more preferably 115 ° C. or higher, even more preferably 130 ° C. or higher, even more preferably 160 ° C. or higher, particularly preferably 210 ° C. or higher, even more particularly preferably 250 ° C. or higher, even more particularly preferably 255 ° C. or higher, particularly preferably 295 ° C. or higher, preferably less than 324 ° C., more preferably 310 ° C. or lower, also preferably 275 ° C. or lower, also preferably 270 ° C. or lower, also preferably 230 ° C. or lower, also preferably 225 ° C. or lower, also preferably 200 ° C. or lower, also preferably 180 ° C. or lower, also preferably 135 ° C. or lower. In this specification, the melting point is the temperature corresponding to the maximum value in the heat of fusion curve when the temperature is raised for the second time at a rate of 10 ° C. / min using a differential scanning calorimeter [DSC].

[0099] Examples of the thermoplastic resin include non-fluorinated polymers such as polyethylene, polypropylene, polyamide, polystyrene, thermoplastic polyurethane, polyimide, polyacrylate, polycarbonate, polylactic acid, polyether ether ketone, and polyethylene glycol; fluoropolymers, etc. The thermoplastic resin is preferably polyethylene or a fluoropolymer, and more preferably a fluoropolymer.

[0100] The thermoplastic resin preferably has a melt flow rate of 0.01 to 500 g / 10 min, more preferably 0.1 to 300 g / 10 min. The melt flow rate is a value obtained in accordance with ASTM D1238 using a melt indexer, as the mass (g / 10 min) of polymer flowing out of a nozzle with an inner diameter of 2 mm and a length of 8 mm at a measurement temperature determined depending on the type of fluoropolymer (e.g., 372°C for PFA and FEP, and 297°C for ETFE) and a load (e.g., 49 N (5 kg) for PFA, FEP, and ETFE).

[0101] The fluoropolymer is preferably a melt-processable fluororesin, and examples thereof include tetrafluoroethylene [TFE] / perfluoro(alkyl vinyl ether) [PAVE] copolymer [PFA], TFE / perfluoroallyl ether copolymer, TFE / hexafluoropropylene [HFP] copolymer [FEP], ethylene [Et] / TFE copolymer [ETFE], TFE / HFP / vinylidene fluoride [VdF] copolymer [THV], VdF / TFE copolymer [VT], Et / TFE / HFP copolymer [EFEP], polychlorotrifluoroethylene [PCTFE], chlorotrifluoroethylene [CTFE] / TFE copolymer, Et / CTFE copolymer, polyvinyl fluoride [PVF], polyvinylidene fluoride [PVdF], and the like.

[0102] The PFA is not particularly limited, but a copolymer having a molar ratio of TFE units to PAVE units (TFE units / PAVE units) of 70 / 30 or more and less than 99 / 1 is preferred. A more preferred molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, an even more preferred molar ratio is 80 / 20 or more and 98.9 / 1.1 or less, an even more preferred molar ratio is 90 / 10 or more and 99.7 / 0.3 or less, and an especially preferred molar ratio is 97 / 3 or more and 99 / 1 or less. If the TFE unit content is too low, mechanical properties tend to decrease, while if it is too high, the melting point tends to be too high and moldability tends to decrease. The PFA is also preferably a copolymer having 0.1 to 10 mol% of monomer units derived from monomers copolymerizable with TFE and PAVE, and a total of 90 to 99.9 mol% of TFE units and PAVE units. Monomers copolymerizable with TFE and PAVE include HFP, CZ ３ Z ４ =CZ ５ (CF ２ ) ｎ Z ６ (In the formula, Z ３ , Z ４ and Z ５ are the same or different and represent a hydrogen atom or a fluorine atom; Z ６ represents a hydrogen atom, a fluorine atom, or a chlorine atom, and n represents an integer of 2 to 10. ２ =CF-OCH２ -Rf ７ (wherein, Rf ７ represents a perfluoroalkyl group having 1 to 5 carbon atoms.

[0103] The PFA may have a functional group. The functional group may be contained in the units constituting the PFA, may be contained in the terminal group of the polymer main chain, or may be introduced into the PFA by plasma treatment or the like. Examples of PFAs containing the functional group in their constituent units include PFAs obtained by copolymerizing a monomer having a polar group. Examples of PFAs containing the functional group in the terminal group of the polymer main chain include PFAs having a functional group as an end group derived from a polymerization initiator, a chain transfer agent, or the like. The functional group is preferably a hydroxy group or a carbonyl group-containing group, more preferably a carbonyl-containing group, more preferably a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, or an acid anhydride residue, and even more preferably a carboxy group or an acid anhydride residue.

[0104] The polar group-containing monomer in the PFA may be a fluorine-free monomer or a fluorine-containing monomer.

[0105] 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.

[0106] The polar group-containing monomer preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group. Examples of such modified monomers include the modified monomer (A) described above.

[0107] The melting point of the PFA is preferably 180°C or higher, more preferably 230°C or higher, even more preferably 280°C or higher, even more preferably 290°C or higher, and particularly preferably 295°C or higher, and is preferably lower than 324°C, more preferably 320°C or lower, and even more preferably 310°C or lower.

[0108] Although the FEP is not particularly limited, a copolymer having a molar ratio of TFE units to HFP units (TFE units / HFP units) of 70 / 30 or more and less than 99 / 1 is preferred. A more preferred molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, and an even more preferred molar ratio is 80 / 20 or more and 98.9 / 1.1 or less. Furthermore, although the FEP is not particularly limited, a copolymer having a mass ratio of TFE units to HFP units (TFE units / HFP units) of 60 / 40 or more and 98 / 2 or less is preferred. A more preferred mass ratio is 60 / 40 or more and 95 / 5 or less, and an even more preferred mass ratio is 85 / 15 or more and 92 / 8 or less. Furthermore, the FEP may be modified using perfluoro(alkyl vinyl ether)s as monomers copolymerizable with TFE and HFP, within a range of 0.1 to 2 mass% of the total monomers. If the TFE unit content is too low, mechanical properties tend to decrease, while if it is too high, the melting point tends to become too high and moldability tends to decrease. It is also preferable that the FEP is a copolymer in which the monomer units derived from a monomer copolymerizable with TFE and HFP are 0.1 to 10 mol %, and the total of TFE units and HFP units is 90 to 99.9 mol %. Examples of monomers copolymerizable with TFE and HFP include PAVE and alkyl perfluorovinyl ether derivatives. The FEP may also have a functional group. Examples of the functional group include those described for PFA.

[0109] The melting point of the above-mentioned FEP is lower than the melting point of the above-mentioned PTFE, and is preferably 150°C or higher, more preferably 200°C or higher, even more preferably 240°C or higher, even more preferably 250°C or higher, and is preferably less than 324°C, more preferably 320°C or lower, even more preferably 300°C or lower, even more preferably 280°C or lower, and particularly preferably 275°C or lower.

[0110] As ETFE, a copolymer in which the molar ratio of TFE units to ethylene units (TFE units / ethylene units) is 20 / 80 or more and 90 / 10 or less is preferred. A more preferred molar ratio is 37 / 63 or more and 85 / 15 or less, and an even more preferred molar ratio is 38 / 62 or more and 80 / 20 or less. The molar ratio of TFE units to ethylene units (TFE units / ethylene units) may be 50 / 50 or more and 99 / 1 or less. ETFE may be a copolymer consisting of TFE, ethylene, and a monomer copolymerizable with TFE and ethylene. The copolymerizable monomer may be a copolymer of the following formula CH ２ =CX ５ Rf ３ , C.F. ２ = CFRf ３ , C.F. ２ =CFORf ３ , C.H. ２ = C(Rf ３ ) ２ (In the formula, X ５ is a hydrogen atom or a fluorine atom, Rf ３ represents a fluoroalkyl group which may contain an ether bond.) Among them, monomers represented by CF ２ = CFRf ３ , C.F. ２ =CFORf ３ and CH ２ =CX ５ Rf ３ Fluorine-containing vinyl monomers represented by the formula: ２ =CF-ORf ４ (wherein, Rf ４ represents a perfluoroalkyl group having 1 to 5 carbon atoms.) and perfluoro(alkyl vinyl ether) represented by Rf ３ is a fluoroalkyl group having 1 to 8 carbon atoms, CH ２ =CX ５ Rf ３The fluorine-containing vinyl monomer represented by the following formula is more preferred. The monomer copolymerizable with TFE and ethylene may be an aliphatic unsaturated carboxylic acid such as itaconic acid or itaconic anhydride. The monomer copolymerizable with TFE and ethylene may be perfluorobutylethylene, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooct-1-ene, 2,3,3,4,4,5,5-heptafluoro-1-pentene (CH ２ =CFCF ２ CF ２ CF ２ H), 2-trifluoromethyl-3,3,3-trifluoropropene ((CF ３ ) ２ C=CH ２ ) may be used. The amount of the monomer copolymerizable with TFE and ethylene is preferably 0.1 to 10 mol%, more preferably 0.1 to 5 mol%, and particularly preferably 0.2 to 4 mol% based on the total polymerized units. The ETFE may also be modified using a monomer copolymerizable with TFE and ethylene within a range of 0 to 20 mass% of the total monomers. Preferably, the ratio of TFE:ethylene:TFE and monomer copolymerizable with ethylene is (63 to 94):(27 to 2):(1 to 10). The ETFE may also have a functional group. Examples of the functional group include those described for PFA.

[0111] The ETFE may be a copolymer (EFEP) containing TFE units, ethylene units, and HFP units. The EFEP preferably has a molar ratio of TFE units to ethylene units of 20:80 to 90:10, more preferably 37:63 to 85:15, and even more preferably 38:62 to 80:20. The HFP units are preferably 0.1 to 30 mol%, more preferably 0.1 to 20 mol%, based on the total polymerized units. The EFEP preferably contains 20 to 80 mol% of tetrafluoroethylene units, 10 to 80 mol% of ethylene units, 0 to 30 mol% of hexafluoropropylene units, and 0 to 10 mol% of other monomer units.

[0112] The melting point of the above-mentioned ETFE is preferably 140 ° C or higher, more preferably 160 ° C or higher, even more preferably 195 ° C or higher, even more preferably 210 ° C or higher, particularly preferably 215 ° C or higher, and also preferably less than 324 ° C, more preferably 320 ° C or lower, even more preferably 300 ° C or lower, even more preferably 280 ° C or lower, particularly preferably 270 ° C or lower.The melting point of the above-mentioned EFEP is preferably 160 ° C or higher, and also preferably 200 ° C or lower.

[0113] The copolymerization ratio (mol % ratio) of TFE, HFP, and VdF in the THV is preferably TFE / HFP / VdF=75-95 / 0.1-10 / 0.1-19, more preferably 77-95 / 1-8 / 1-17 (molar ratio), even more preferably 77-95 / 2-8 / 2-16.5 (molar ratio), and most preferably 77-90 / 3-8 / 5-16 (molar ratio). The TFE / HFP / VdF copolymer may contain 0-20 mol % of other monomers. Examples of other monomers include perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, 2-chloropentafluoropropene, and perfluorinated vinyl ethers (e.g., CF ３ OCF ２ CF ２ CF ２ OCF = CF ２ fluorine-containing monomers such as perfluoroalkoxy vinyl ethers, perfluoroalkyl vinyl ethers, perfluoro-1,3-butadiene, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, ethylene, propylene, and alkyl vinyl ethers, BTFB(H ２ C=CH-CF ２ -CF ２ -Br), BDFE(F ２ C=CHBr), BTFE(F ２C-CFBr), and perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), BTFB(H ２ C=CH-CF ２ -CF ２ -Br), BDFE(F ２ C=CHBr), BTFE(F ２ C-CFBr) is preferred.

[0114] The melting point of the THV is preferably 110°C or higher, more preferably 140°C or higher, even more preferably 160°C or higher, even more preferably 180°C or higher, and particularly preferably 220°C or higher, and is preferably 300°C or lower, more preferably 270°C or lower, even more preferably 250°C or lower, even more preferably 200°C or lower, especially preferably 180°C or lower, even more especially preferably 160°C or lower, and particularly preferably 130°C or lower.

[0115] VT preferably contains 80.0 to 90.0 mol% of VdF-based polymerization units (also referred to as "VdF units") relative to the total polymerization units. If the VdF unit content is less than 80.0 mol%, the viscosity of the electrode mixture will change significantly over time, and if it is more than 90.0 mol%, the flexibility of the electrode obtained from the mixture will tend to be poor. The VT preferably contains 80.5 mol% or more of VdF units relative to the total polymerization units, and more preferably 82.0 mol% or more. If it contains 82.0 mol% or more, the cycle characteristics of a battery using an electrode obtained from the electrode mixture of the present disclosure tend to be better. Furthermore, the VT more preferably contains 89.0 mol% or less of VdF units relative to the total polymerization units, even more preferably 88.9 mol% or less, and particularly preferably 88.8 mol% or less.

[0116] In addition to the VdF units and TFE-based polymerized units (also referred to as "TFE units"), the VT may also contain polymerized units based on a monomer copolymerizable with VdF and TFE. To achieve the effects of the present disclosure, a copolymer of VdF and TFE is sufficient. However, the adhesiveness can be further improved by copolymerizing a monomer copolymerizable with VdF and TFE to an extent that does not impair the excellent non-aqueous electrolyte swelling property of the copolymer. The content of the polymerized units based on the VdF and TFE-copolymerizable monomer is preferably less than 3.0 mol% relative to the total polymerized units of the VT. If it is 3.0 mol% or more, the crystallinity of the VdF and TFE copolymer generally decreases significantly, resulting in a tendency for the non-aqueous electrolyte swelling property to decrease.

[0117] Examples of the monomer copolymerizable with VdF and TFE include unsaturated dibasic acid monoesters such as maleic acid monomethyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester, and vinylene carbonate as described in JP-A-6-172452, and -SO ３ M, -OSO ３ M, -COOM, -OPO ３ M (M represents an alkali metal) or an amine polar group -NHR １ , -NR ２ R ３ (R １ , R ２ , R ３ represents an alkyl group), ２ =CH-CH ２ -Y, CH ２ =C(CH ３ )-CH ２ -Y, CH ２ =CH-CH ２ -O-CO-CH(CH ２ COOR ４ )-Y, CH ２ =CH-CH ２ -O-CH ２ -CH(OH)-CH ２ -Y, CH ２ =C(CH ３ )-CO-O-CH２ -CH ２ -CH ２ -Y, CH ２ =CH-CO-O-CH ２ -CH ２ -Y, CH ２ =CHCO-NH-C(CH ３ ) ２ -CH ２ -Y (Y is a hydrophilic polar group, and R ４ represents an alkyl group), and other examples include maleic acid and maleic anhydride. ２ =CH-CH ２ -O-(CH ２ ) ｎ -OH (3≦n≦8),

[0118]

[0119] CH ２ =CH-CH ２ -O-(CH ２ -CH ２ -O) ｎ -H (1≦n≦14), CH ２ =CH-CH ２ -O-(CH ２ -CH(CH ３ )-O) ｎ Hydroxylated allyl ether monomers such as -H (1≦n≦14) and carboxylated and / or -(CF ２ ) ｎ -CF ３ (3≦n≦8) substituted aryl ether and ester monomers, such as CH ２ =CH-CH ２ —O—CO—C ２ H ４ -COOH, CH ２ =CH-CH ２ —O—CO—C ５ H １０ -COOH, CH ２ =CH-CH ２ -O-C ２ H ４ -(CF ２ ) ｎ CF ３ , C.H. ２ =CH-CH ２-CO-O-C ２ H ４ -(CF ２ ) ｎ CF ３ , C.H. ２ =C(CH ３ )-CO-O-CH ２ -CF ３ Also usable as copolymerizable monomers are compounds containing polar groups such as those mentioned above. However, previous studies have suggested that by slightly reducing the crystallinity of a copolymer of vinylidene fluoride and tetrafluoroethylene and imparting flexibility to the material, the adhesiveness to a current collector made of aluminum or copper foil can be improved. From this, it has been possible to infer that unsaturated hydrocarbon monomers (CH ２ =CHR, where R is a hydrogen atom, an alkyl group, or a halogen such as Cl), and fluorine-based monomers such as trifluorochloroethylene, hexafluoropropylene, hexafluoroisobutene, 2,3,3,3-tetrafluoropropene, CF ２ =CF-O-C ｎ F ２ｎ＋１ (n is an integer of 1 or more), CH ２ =CF-C ｎ F ２ｎ＋１ (n is an integer of 1 or more), CH ２ =CF-(CF ２ CF ２ ) ｎ H (n is an integer of 1 or more), and CF ２ =CF-O-(CF ２ CF (CF ３ ) O) ｍ -C ｎ F ２ｎ＋１ (m and n are integers of 1 or more) can also be used.

[0120]

[0121] (Wherein, Y is —CH ２ OH, —COOH, carboxylate, carboxy ester or epoxy group, X and X １ are the same or different and are all hydrogen atoms or fluorine atoms, R ｆAlso usable are fluorine-containing ethylenic monomers having at least one functional group represented by the formula (wherein ═ represents a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or a divalent fluorine-containing alkylene group containing an ether bond having 1 to 40 carbon atoms). Copolymerization of one or more of these monomers further improves adhesion to the current collector, preventing the electrode active material from peeling off from the current collector even after repeated charge and discharge, and achieving good charge and discharge cycle characteristics. Among these monomers, hexafluoropropylene and 2,3,3,3-tetrafluoropropene are particularly preferred from the viewpoints of flexibility and chemical resistance.

[0122] Thus, the VT may contain other polymer units in addition to the VdF units and TFE units, but more preferably consists of only VdF units and TFE units.

[0123] The VT preferably has a weight average molecular weight (polystyrene equivalent) of 50,000 to 2,000,000. The weight average molecular weight is more preferably 80,000 or more, even more preferably 100,000 or more, and more preferably 1,950,000 or less, even more preferably 1,900,000 or less, particularly preferably 1,700,000 or less, and most preferably 1,500,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using N,N-dimethylformamide as a solvent at 50°C.

[0124] The VT preferably has a number average molecular weight (polystyrene equivalent) of 10,000 to 1,400,000. The number average molecular weight is more preferably 16,000 or more, even more preferably 20,000 or more, and more preferably 1,300,000 or less, even more preferably 1,200,000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using N,N-dimethylformamide as a solvent at 50°C.

[0125] The melting point of the VT is preferably 120°C or higher, more preferably 130°C or higher, and is preferably 160°C or lower, more preferably 150°C or lower, even more preferably 140°C or lower, and even more preferably 135°C or lower.

[0126] The PVdF may be a homopolymer consisting of only polymerization units based on VdF, or may be a homopolymer consisting of polymerization units based on VdF and polymerization units based on a monomer (α) copolymerizable with the polymerization units based on VdF.

[0127] Examples of the monomer (α) include vinyl fluoride, trifluoroethylene, trifluorochloroethylene, fluoroalkyl vinyl ether, hexafluoropropylene, 2,3,3,3-tetrafluoropropene, propylene, etc. Also included are unsaturated dibasic acid monoesters such as maleic acid monomethyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester, and vinylene carbonate as described in JP-A-6-172452, and -SO ３ M, -OSO ３ M, -COOM, -OPO ３ M (M represents an alkali metal) or an amine polar group -NHR １ , -NR ２ R ３ (R １ , R ２ , R ３ represents an alkyl group), ２ =CH-CH ２ -Y, CH ２ =C(CH ３ )-CH ２ -Y, CH ２ =CH-CH ２ -O-CO-CH(CH ２ COOR ４ )-Y, CH ２ =CH-CH ２ -O-CH ２ -CH(OH)-CH ２ -Y, CH ２=C(CH ３ )-CO-O-CH ２ -CH ２ -CH ２ -Y, CH ２ =CH-CO-O-CH ２ -CH ２ -Y, CH ２ =CHCO-NH-C(CH ３ ) ２ -CH ２ -Y (Y is a hydrophilic polar group, and R ４ represents an alkyl group), and other examples include maleic acid and maleic anhydride. ２ =CH-CH ２ -O-(CH ２ ) ｎ -OH (3≦n≦8), CH ２ =CH-CH ２ -O-(CH ２ -CH ２ -O) ｎ -H (1≦n≦14), CH ２ =CH-CH ２ -O-(CH ２ -CH(CH ３ )-O) ｎ Hydroxylated allyl ether monomers such as -H (1≦n≦14) and carboxylated and / or -(CF ２ ) ｎ -CF ３ (3≦n≦8) substituted aryl ether and ester monomers, such as CH ２ =CH-CH ２ —O—CO—C ２ H ４ -COOH, CH ２ =CH-CH ２ —O—CO—C ５ H １０ -COOH, CH ２ =CH-CH ２ -O-C ２ H ４ -(CF ２ ) ｎ CF ３ , C.H. ２ =CH-CH ２ -CO-O-C ２ H４ -(CF ２ ) ｎ CF ３ , C.H. ２ =C(CH ３ )-CO-O-CH ２ -CF ３ Also usable as copolymerizable monomers are compounds containing polar groups such as those mentioned above. However, previous research has led to the idea that by slightly reducing the crystallinity of PVdF and imparting flexibility to the material, the adhesiveness to a current collector made of aluminum or copper foil can be improved. From this, it has been suggested that unsaturated hydrocarbon monomers such as ethylene and propylene (CH ２ =CHR, where R is a hydrogen atom, an alkyl group, or a halogen such as Cl), and fluorine-based monomers such as trifluorochloroethylene, hexafluoropropylene, hexafluoroisobutene, and CF ２ =CF-O-C ｎ F ２ｎ＋１ (n is an integer of 1 or more), CH ２ =CF-C ｎ F ２ｎ＋１ (n is an integer of 1 or more), CH ２ =CF-(CF ２ CF ２ ) ｎ H (n is an integer of 1 or more), and CF ２ =CF-O-(CF ２ CF (CF ３ ) O) ｍ -C ｎ F ２ｎ＋１ (m and n are integers of 1 or more) can also be used.

[0128] (Wherein, Y is —CH ２ OH, —COOH, carboxylate, carboxy ester or epoxy group, X and X １ are the same or different and are all hydrogen atoms or fluorine atoms, R ｆIt is also possible to use a fluorine-containing ethylenic monomer having at least one functional group represented by the formula (wherein R represents a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms and containing an ether bond). By copolymerizing one or more of these monomers, the adhesion to the current collector is further improved, and the electrode active material does not peel off from the current collector even after repeated charge and discharge, thereby achieving good charge and discharge cycle characteristics.

[0129] In the PVdF, the polymerized units based on the monomer (α) preferably account for 5 mol % or less, more preferably 4.5 mol % or less, of all polymerized units.

[0130] The PVdF preferably has a weight average molecular weight (polystyrene equivalent) of 50,000 to 2,000,000. The weight average molecular weight is more preferably 80,000 or more, even more preferably 100,000 or more, and more preferably 1,700,000 or less, even more preferably 1,500,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) at 50°C using N,N-dimethylformamide as a solvent.

[0131] The PVdF has a number average molecular weight (polystyrene equivalent) of 150,000 to 1,400,000. If it is less than 150,000, the adhesion of the resulting electrode will be reduced. If it exceeds 1,400,000, gelation will occur easily when preparing the electrode mixture. The number average molecular weight is preferably 200,000 or more, more preferably 250,000 or more, and even more preferably 300,000 or more, and is preferably 1,300,000 or less, more preferably 1,200,000 or less, even more preferably 1,000,000, and particularly preferably 800,000. The number average molecular weight can be measured by gel permeation chromatography (GPC) at 50°C using N,N-dimethylformamide as a solvent.

[0132] The melting point of the PVdF is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 160°C or higher, and is preferably 230°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0133] The content of each monomer unit in the above-mentioned copolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0134] The fluoropolymer as the thermoplastic resin is preferably a perfluoropolymer, more preferably at least one selected from the group consisting of PFA and FEP.

[0135] The fluoropolymer as the thermoplastic resin is preferably a VdF-based polymer, and more preferably at least one selected from the group consisting of PVdF and VT.

[0136] The VdF polymer preferably has an average particle size of 10 μm or less, more preferably 8 μm or less, even more preferably 5 μm or less, even more preferably 2 μm or less, and preferably 0.1 μm or more, more preferably 0.5 μm or more, in terms of being able to be uniformly dispersed and providing excellent strength and uniformity to the composite sheet. The average particle size of the VdF polymer can be adjusted, for example, by pulverization. The average particle size was measured using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320) in a dry state at a vacuum pressure of 20 mH. ２ The average particle size was determined based on the particle size distribution (volume basis) obtained. The average particle size was set to be equal to the particle size corresponding to 50% of the integrated particle size distribution.

[0137] The VdF polymer preferably does not contain a fluorine-containing surfactant. A fluorine-containing surfactant-free VdF polymer can be produced, for example, by suspension polymerization. As described in the Examples below, the absence of a fluorine-containing surfactant in a VdF polymer can be confirmed by the amount of the fluorine-containing surfactant measured using liquid chromatography-mass spectrometry being below the detection limit.

[0138] The elastomer preferably has a glass transition temperature of 25°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower, and preferably -50°C or higher, and more preferably -30°C or higher.

[0139] Examples of the elastomer include non-fluorine-containing rubbers such as nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), ethylene-α-olefin rubber, ethylene-α-olefin-non-conjugated diene rubber, chlorinated polyolefin rubber, chlorosulfonated polyolefin rubber, acrylic rubber, ethylene-based acrylic rubber, epichlorohydrin rubber, silicone rubber, butyl rubber (IIR), ethylene-vinyl ester rubber, and ethylene-methacrylate rubber; and fluoroelastomers. As the elastomer, a fluoroelastomer is preferred. The elastomer may be crosslinked or non-crosslinked.

[0140] Specific examples of the fluoroelastomer include vinylidene fluoride (VdF)-based fluoroelastomers, TFE / propylene (Pr)-based fluoroelastomers, TFE / Pr / VdF-based fluoroelastomers, ethylene (Et) / HFP-based fluoroelastomers, Et / HFP / VdF-based fluoroelastomers, Et / HFP / TFE-based fluorine-containing elastomers, fluorosilicone-based fluorine-containing elastomers, and fluorophosphazene-based fluorine-containing elastomers, and these can be used alone or in any combination within the scope that does not impair the effects of the present disclosure. Among these, it is preferable to use VdF-based fluorine-containing elastomers.

[0141] The VdF-based fluoroelastomer is a fluoroelastomer containing VdF units and other monomer units copolymerizable with VdF. The VdF-based fluoroelastomer preferably has a VdF unit content of 20 mol% or more and 90 mol% or less, more preferably 40 mol% or more and 85 mol% or less, based on the total content of the VdF units and other monomer units. A more preferred lower limit is 45 mol%, and a particularly preferred lower limit is 50 mol%. A more preferred upper limit is 80 mol%.

[0142] The comonomer in the VdF-based fluoroelastomer is not particularly limited as long as it is copolymerizable with VdF, and examples thereof include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoroalkyl vinyl ether (PAVE), chlorotrifluoroethylene (CTFE), trifluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, vinyl fluoride, iodine-containing fluorinated vinyl ether, and fluorinated vinyl ethers of the general formula (1-1) CH ２ = CFRf １ (1-1) (wherein, Rf １is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, an oxygen atom may be contained between carbon atoms.), a fluorine-containing monomer represented by the general formula (2-1): CHF=CHRf ２ (2-1) (wherein, Rf ２ is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, it may contain an oxygen atom between the carbon atoms.); fluorine-free monomers such as ethylene (Et), propylene (Pr), and alkyl vinyl ethers, monomers that provide crosslinkable groups (cure sites), and reactive emulsifiers; and one or more of these monomers or compounds can be used in combination.

[0143] In the above general formula (1-1), Rf １ is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group each have two or more carbon atoms, they can contain an oxygen atom (—O—) between carbon atoms. １ The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. １ The fluorinated alkyl group Rf may have a hydrogen atom substituted with a substituent other than a fluorine atom, but preferably does not contain any substituent other than a fluorine atom. １ The fluorinated alkoxy group of Rf may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. １The fluorinated alkoxy group of Rf may have a hydrogen atom substituted with a substituent other than a fluorine atom, but preferably does not contain any substituent other than a fluorine atom. １ The number of carbon atoms in the group is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0144] In the above formula (2-1), Rf ２ is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group each have two or more carbon atoms, they can contain an oxygen atom (—O—) between carbon atoms. ２ The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. ２ The fluorinated alkyl group Rf may have a hydrogen atom substituted with a substituent other than a fluorine atom, but preferably does not contain any substituent other than a fluorine atom. ２ The fluorinated alkoxy group of Rf may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. ２ In the fluorinated alkoxy group of formula (I), a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferable that Rf2 does not contain any substituent other than a fluorine atom. The number of carbon atoms in Rf2 is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0145] Among these, copolymerized units comprised of hexafluoropropylene (HFP), tetrafluoroethylene (TFE), 2,3,3,3-tetrafluoropropylene, 1,3,3,3-tetrafluoropropylene, or perfluoroalkyl vinyl ether (PAVE) are preferred. Furthermore, it is most preferred that at least a portion of the copolymerized units be hexafluoropropylene (HFP). Examples of vinylidene fluoride elastomers in which at least a portion of the copolymerized units are hexafluoropropylene (HFP) include binary elastomers comprised of vinylidene fluoride and hexafluoropropylene, and ternary elastomers comprised of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene.

[0146] As the PAVE, perfluoro(methyl vinyl ether) (PMVE) and perfluoro(propyl vinyl ether) (PPVE) are more preferred, and PMVE is particularly preferred. ２ = CFOCF ２ ORf ｃ (wherein, Rf ｃ is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms), and perfluorovinyl ethers represented by the formula (CF) can also be used. For example, ２ = CFOCF ２ OCF ３ , C.F. ２ = CFOCF ２ OCF ２ CF ３ , or CF ２ = CFOCF ２ OCF ２ CF ２ OCF ３ It is preferable to use

[0147] The VdF-based fluoroelastomer is preferably at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, VdF / Et / HFP copolymer, and a copolymer of VdF / a fluorine-containing monomer represented by formula (1-1) or (2-1). Furthermore, it is more preferred that the VdF-based fluoroelastomer contains at least one comonomer selected from the group consisting of TFE, HFP, and PAVE as the comonomer other than VdF.

[0148] Among these, at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / copolymer of a fluorine-containing monomer represented by formula (1-1) or (2-1), VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer and VdF / HFP / TFE / PAVE copolymer is preferred, and VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / copolymer of a fluorine-containing monomer represented by formula (1-1) or (2-1) and VdF / At least one copolymer selected from the group consisting of PAVE copolymers is more preferred, at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, and VdF / copolymer of a fluorine-containing monomer represented by formula (1-1) is even more preferred, at least one copolymer selected from the group consisting of VdF / HFP copolymer, VdF / TFE / HFP copolymer, and VdF / 2,3,3,3-tetrafluoropropylene copolymer is even more preferred, and VdF / HFP copolymer is particularly preferred.

[0149] The VdF / HFP copolymer preferably has a VdF / HFP composition of (45 to 85) / (55 to 15) (mol%), more preferably (50 to 80) / (50 to 20) (mol%), and even more preferably (60 to 80) / (40 to 20) (mol%). The VdF / HFP composition is also preferably (50 to 78) / (50 to 22) (mol%).

[0150] The VdF / TFE / HFP copolymer preferably has a VdF / TFE / HFP composition of (30-80) / (4-35) / (10-35) (mol %).

[0151] The VdF / PAVE copolymer preferably has a VdF / PAVE composition of (65 to 90) / (35 to 10) (mol %). Another preferred embodiment has a VdF / PAVE composition of (50 to 78) / (50 to 22) (mol %).

[0152] The VdF / TFE / PAVE copolymer preferably has a VdF / TFE / PAVE composition of (40-80) / (3-40) / (15-35) (mol %).

[0153] The VdF / HFP / PAVE copolymer preferably has a VdF / HFP / PAVE composition of (65 to 90) / (3 to 25) / (3 to 25) (mol %).

[0154] The VdF / HFP / TFE / PAVE copolymer preferably has a VdF / HFP / TFE / PAVE composition of (40 to 90) / (0 to 25) / (0 to 40) / (3 to 35) (mol %), and more preferably has a VdF / HFP / TFE / PAVE composition of (40 to 80) / (3 to 25) / (3 to 40) / (3 to 25) (mol %).

[0155] The VdF / fluorine-containing monomer (1-1) or (2-1)-based copolymer represented by formula (1-1) or (2-1) preferably has a VdF / fluorine-containing monomer (1-1) or (2-1) unit ratio of 87 / 13 to 20 / 80 (mol%), and monomer units other than VdF and fluorine-containing monomer (1-1) or (2-1) account for 0 to 50 mol% of the total monomer units, and more preferably has a VdF / fluorine-containing monomer (1-1) or (2-1) unit molar ratio of 80 / 20 to 20 / 80. Another preferred embodiment has a VdF / fluorine-containing monomer (1-1) or (2-1) unit composition of 78 / 22 to 50 / 50 (mol%). Also preferred are those in which the VdF / fluorine-containing monomer (1-1) or (2-1) unit ratio is 87 / 13 to 50 / 50 (mol %) and the other monomer units other than VdF and the fluorine-containing monomer (1-1) or (2-1) account for 1 to 50 mol % of all monomer units. As the other monomer other than VdF and the fluorine-containing monomer (1-1) or (2-1), preferred are the monomers exemplified above as comonomers for VdF, such as TFE, HFP, PMVE, perfluoroethyl vinyl ether (PEVE), PPVE, CTFE, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, Et, Pr, alkyl vinyl ethers, monomers that provide crosslinkable groups, and reactive emulsifiers, among which PMVE, CTFE, HFP, and TFE are more preferred.

[0156] The TFE / Pr-based fluorine-containing elastomer refers to a fluorine-containing copolymer consisting of 45 to 70 mol % of TFE and 55 to 30 mol % of Pr. In addition to these two components, it may contain 0 to 40 mol % of a specific third component (e.g., PAVE).

[0157] The Et / HFP copolymer preferably has an Et / HFP composition of (35 to 80) / (65 to 20) (mol %), more preferably (40 to 75) / (60 to 25) (mol %).

[0158] The Et / HFP / TFE copolymer preferably has an Et / HFP / TFE composition of (35 to 75) / (25 to 50) / (0 to 15) (mol %), more preferably (45 to 75) / (25 to 45) / (0 to 10) (mol %).

[0159] Examples of perfluoro fluorine-containing elastomers include those made of TFE / PAVE. The TFE / PAVE composition is preferably (50-90) / (50-10) (mol%), more preferably (50-80) / (50-20) (mol%), and even more preferably (55-75) / (45-25) (mol%). In this case, examples of PAVE include PMVE and PPVE, which can be used alone or in any combination.

[0160] The fluoroelastomer preferably has a fluorine content of 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. The upper limit of the fluorine content is not particularly limited, but is preferably 71% by mass or less. The fluorine content is a value calculated from the composition of the fluoroelastomer measured by 19F-NMR. The molecular weight was calculated from the composition ratio, and the mass of fluorine atoms contained therein was determined, and the fluorine content was calculated.

[0161] In the present disclosure, the composition ratio of each repeating unit of the fluoroelastomer is a value measured by the NMR method. Specifically, it is a value measured by the following solution NMR method. Measuring device: Varian VNMRS400 Resonance frequency: 376.04 (Sfrq) Pulse width: 30° (pw=6.8)

[0162] The non-perfluoro fluorine-containing elastomer and perfluoro fluorine-containing elastomer described above can be produced by a conventional method such as emulsion polymerization, suspension polymerization, solution polymerization, etc. In particular, a polymerization method using an iodine (bromine) compound, known as iodine (bromine) transfer polymerization, can produce a fluoroelastomer with a narrow molecular weight distribution.

[0163] The polymer may have structural units other than vinylidene fluoride units and copolymerization units (A). In this case, the content of the other structural units is preferably 50 mol% or less. The polymer may consist only of vinylidene fluoride units and copolymerization units (A). The content of the other structural units is more preferably 30 mol% or less, and even more preferably 15 mol% or less.

[0164] The polymer may contain, as the other monomer, a monomer that provides a crosslinking site.

[0165] The monomer that provides the crosslinking site is not particularly limited, and examples thereof include a monomer represented by the general formula: CX １ ２ =CX １ -Rf １ CHR １ X ２ (In the formula, X １ is a hydrogen atom, a fluorine atom, or —CH ３ , Rf １ represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, R １ is a hydrogen atom or -CH ３ , X ２ is an iodine atom or a bromine atom.) an iodine- or bromine-containing monomer represented by the general formula: CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -X ３ (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X ３ is a cyano group, a carboxy group, an alkoxycarbonyl group, an iodine atom, or a bromine atom, ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｍ (CF (CF ３ )) ｎ -X ４ (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X４ represents a cyano group, a carboxy group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ OH) may be used as the other monomer.

[0166] Among them, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, C.F. ２ = CFOCF ２ CF ２ CH ２ I, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CH ２ I, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CN, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOH and CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CH ２ It is preferable that the repeating unit is at least one selected from the group consisting of OH. Furthermore, the repeating unit may contain a repeating unit based on a monomer that provides a crosslinking site, but in one embodiment of the present disclosure, the repeating unit does not contain a crosslinking agent.

[0167] In order to provide the fluoroelastomer with good adhesion, flexibility, and solubility in solvents, the number average molecular weight (Mn) is preferably 7,000 to 5,000,000, the mass average molecular weight (Mw) is preferably 10,000 to 10,000,000, and the Mw / Mn ratio is preferably 1.0 to 30.0, and more preferably 1.5 to 25.0. The number average molecular weight (Mn), mass average molecular weight (Mw), and Mw / Mn are values ​​measured by GPC.

[0168] The Mooney viscosity at 121°C (ML1+10(121°C)) of the fluoroelastomer is preferably 2 or more, more preferably 5 or more, even more preferably 10 or more, particularly preferably 30 or more, and may be 200 or less. The Mooney viscosity at 140°C (ML1+10(140°C)) of the fluoroelastomer is preferably 2 or more, more preferably 5 or more, even more preferably 10 or more, even more preferably 30 or more, particularly preferably 50 or more, and may be 200 or less, or may be 100 or less. The Mooney viscosity is a value measured in accordance with ASTM-D1646-15 and JIS K6300-1:2013.

[0169] The fluoroelastomer has a terminal structure that satisfies the following inequality: 0.01≦([-CH ２ OH]+[-COOH]) / ([-CH ３ ]+[-CF ２ H] + [-CH ２ OH] + [-CH ２ It is preferable that the formula (wherein RH is an alkyl group having 1 to 20 carbon atoms) be satisfied: [—OC(O)RH]+[—COOH])≦0.25. By making the terminal functional group satisfy the formula, the adhesiveness and flexibility are good, and the composition has excellent functions.

[0170] In addition, satisfying the above general formula means that the fluorine-containing copolymer has a structure of [—CH ３ ], [-CF ２ H], [-CH ２ OH], [-CH ２It does not mean that the fluorocopolymer has all of the functional groups, [—I], [—OC(O)RH], and [—COOH], but it means that, among these, the ratio of the number of terminal groups present in the fluorocopolymer is within the above-mentioned range.

[0171] The amount of each terminal group present in the fluorine-containing copolymer can be measured by NMR analysis.

[0172] For example, NMR end group analysis is performed by proton solution NMR. The analysis sample is prepared as a 20% by mass solution using acetone-d6 as the solvent, and the measurement is performed. The reference peak is the acetone peak top at 2.05 ppm. Measurement device: Varian VNMRS400 Resonance frequency: 399.74 (Sfrq) Pulse width: 45° Each end corresponds to the following peak position: [-CH ３ ]: 1.72 to 1.86 ppm [-CF ２ H]: 6.1 to 6.8 ppm [-CH ２ OH]: 3.74 to 3.80 ppm [-CH ２ I]: 3.87 to 3.92 ppm [—OC(O)RH]: 1.09 to 1.16 ppm [—COOH]: 10 to 15 ppm The amount of functional groups is calculated from the intensity of each peak based on the integral value of each peak identified by the above-mentioned measurement, and the amount of functional groups is calculated using the following formula based on the results. ２ OH]+[-COOH]) / ([-CH ３ ]+[-CF ２ H] + [-CH ２ OH] + [-CH ２ I]+[-OC(O)RH]+[-COOH])

[0173] [-CH ２ The method for adjusting the [—OH] and [—COOH] to fall within the above-mentioned ranges is not particularly limited, and they can be controlled by known methods (for example, the selection and amount of initiator used in polymerization).

[0174] The thermoplastic polymer can be produced by a general radical polymerization method. The polymerization method may be any of bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, but emulsion polymerization is preferred because it is easy to carry out industrially. In the polymerization, a polymerization initiator, a chain transfer agent, a surfactant, and a solvent can be used, and conventionally known ones can be used. The copolymer can be in any form, such as an aqueous dispersion or powder. In the case of emulsion polymerization, the copolymer powder can be obtained by coagulating the dispersion after polymerization, washing with water, dehydrating, and drying. Coagulation can be performed by adding an inorganic salt or inorganic acid such as aluminum sulfate, applying mechanical shear force, or freezing the dispersion. In the case of suspension polymerization, the copolymer can be obtained by recovering the copolymer from the dispersion after polymerization and drying it. In the case of solution polymerization, the copolymer can be obtained by drying the solution containing the fluoropolymer as it is, or by purifying it by adding a poor solvent dropwise.

[0175] The thermoplastic polymer is preferably at least one selected from the group consisting of perfluoropolymers and VdF-based polymers, more preferably at least one selected from the group consisting of PFA, FEP, PVdF, VT, and VdF-based fluoroelastomers, even more preferably at least one selected from the group consisting of PFA, FEP, PVdF, VT, VdF / HFP copolymers, VdF / TFE / HFP copolymers, and VdF / 2,3,3,3-tetrafluoropropylene copolymers, even more preferably at least one selected from the group consisting of PFA, FEP, PVdF, VT, and VdF / HFP copolymers, and particularly preferably at least one selected from the group consisting of PVdF and VT. The VdF-based polymer is also preferably a fluoroelastomer.

[0176] The content of the thermoplastic polymer in the polymer composition of the present disclosure is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, even more preferably 8% by mass or more, and particularly preferably 10% by mass or more, from the viewpoints of further improving the Coulomb efficiency of the electrochemical device, further reducing the amount added, further improving the adhesion between the mixture sheet and the substrate, and further improving the powder flowability. The content is also preferably less than 50% by mass, more preferably 45% by mass or less, even more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less.

[0177] The total amount of the fibrillating polymer and the thermoplastic polymer in the polymer composition of the present disclosure may be 95.0% by mass or more, preferably 98.0% by mass or more, 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.

[0178] The polymer composition (1) 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)). The polymer composition (2) of the present disclosure may contain the above compound. 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 -SO３ ) 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.

[0179] 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.

[0180] 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.

[0181] The 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.

[0182] When the polymer composition of the present disclosure contains compound (1), the content of compound (1) (the content of each component when two or more types are present) relative to the polymer composition may be 10 ppm by mass or less, preferably 5000 ppb by mass or less, more preferably 1000 ppb by mass or less, even more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, even more preferably 25 ppb by mass or less, and particularly preferably 10 ppb by mass or less. The lower limit is not particularly limited, but may be 0.1 ppb by mass, 1 ppb by mass, 10 ppb by mass, or 50 ppb by mass.

[0183] The 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.

[0184] When the polymer composition of the present disclosure contains compound (2), the content of compound (2) (the content of each component when two or more types are present) may be 10 ppm by mass or less relative to the polymer composition, preferably 5000 ppb by mass or less, more preferably 1000 ppb by mass or less, even more preferably 500 ppb by mass or less, even more preferably 100 ppb by mass or less, even more preferably 50 ppb by mass or less, even more preferably 25 ppb by mass or less, even more preferably 10 ppb by mass or less, even more preferably 1 ppb by mass or less, even more preferably less than 1 ppb by mass, and particularly preferably less than the lower limit of quantitation. The lower limit is not particularly limited, and may be an amount less than the lower limit of quantitation.

[0185] The polymer composition containing compound (1) and / or (2) can be obtained by using a hydrocarbon surfactant. The polymer composition of the present disclosure may contain a hydrocarbon surfactant in addition to a fibrillating polymer, a thermoplastic polymer, and compound (1) and / or (2). The content of the hydrocarbon surfactant in the polymer composition is not particularly limited, but is typically 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).

[0186] The 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.

[0187] "Substantially free of compound (3)" means that the content of compound (3) is 25 mass ppb or less relative to the polymer composition.The content of compound (3) is preferably 20 mass ppb or less relative to the TFE-based polymer, 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.

[0188] The polymer composition of the present disclosure preferably 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 ppb by mass or less relative to the 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.

[0189] When the polymer composition of the present disclosure contains compound (4), the content of compound (4) is more preferably 500 mass ppb or less, even more preferably 250 mass ppb or less, even more preferably 100 mass ppb or less, even more preferably 50 mass ppb or less, even more preferably 25 mass ppb or less, even more preferably 15 mass ppb or less, and particularly preferably 10 mass ppb or less, relative to the polymer composition. The lower limit is not particularly limited, but may be 0.1 mass ppb or 1 mass ppb.

[0190] When the polymer composition of the present disclosure contains compound (4'), the content of compound (4') is more preferably 500 mass ppb or less, even more preferably 250 mass ppb or less, even more preferably 100 mass ppb or less, even more preferably 50 mass ppb or less, even more preferably 25 mass ppb or less, even more preferably 15 mass ppb or less, and particularly preferably 10 mass ppb or less, relative to the polymer composition. The lower limit is not particularly limited, but may be 0.1 mass ppb or 1 mass ppb.

[0191] The polymer composition of the present disclosure preferably 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 ppb by mass or less relative to the 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 (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.

[0192] When the polymer composition of the present disclosure contains compound (5), the content of compound (5) is more preferably 500 mass ppb or less, even more preferably 250 mass ppb or less, even more preferably 100 mass ppb or less, even more preferably 50 mass ppb or less, even more preferably 25 mass ppb or less, even more preferably 15 mass ppb or less, and particularly preferably 10 mass ppb or less, relative to the polymer composition. The lower limit is not particularly limited, but may be 0.1 mass ppb or 1 mass ppb.

[0193] When the polymer composition of the present disclosure contains compound (5'), the content of compound (5') is more preferably 500 mass ppb or less, even more preferably 250 mass ppb or less, even more preferably 100 mass ppb or less, even more preferably 50 mass ppb or less, even more preferably 25 mass ppb or less, even more preferably 15 mass ppb or less, and particularly preferably 10 mass ppb or less, relative to the polymer composition. The lower limit is not particularly limited, but may be 0.1 mass ppb or 1 mass ppb.

[0194] 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.

[0195] The 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 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 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 the values ​​are calculated for each sample, and the average is calculated. Water content (mass%)=[(mass (g) of polymer composition before heating)−(mass (g) of polymer composition after heating)] / (mass (g) of polymer composition before heating)×100

[0196] The polymer composition of the present disclosure is preferably substantially free of fluorine-containing compounds having a molecular weight of 1000 or less. "Substantially free of fluorine-containing compounds" means that the amount of the fluorine-containing compounds is 25 mass ppb or less relative to the polymer composition. The amount of the fluorine-containing compounds 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 quantitation. The lower limit is not particularly limited, and may be an amount less than the lower limit of quantitation.

[0197] 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.

[0198] Examples of the fluorine-containing compound having a molecular weight of 1000 or less include fluorine-containing compounds 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. Polymer particles obtained by polymerization in the presence of a fluorine-containing surfactant usually contain a fluorine-containing surfactant in addition to the target 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. Note that, when the fluorine-containing compound having a molecular weight of 1000 or less contains an anionic moiety and a cationic moiety, it means a fluorine-containing compound in which the molecular weight of the anionic moiety is 1000 or less. The fluorine-containing compound having a molecular weight of 1000 or less does not include fibrillating polymers or thermoplastic polymers.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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 polymer composition of the present disclosure is preferably substantially free of any of the fluorine-containing compounds represented by the above formulas.

[0203] 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:

[0204] When the polymer composition of the present disclosure is substantially free of any of the fluorine-containing compounds represented by the above formulas, gas generation and deterioration of electrochemical device properties can be further suppressed. "Substantially free of any of the fluorine-containing compounds represented by the above formulas" means that the amount of the fluorine-containing compound is 25 mass ppb or less relative to the 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 quantitation. The lower limit is not particularly limited, and may be an amount less than the lower limit of quantitation.

[0205] The polymer compositions of the present disclosure have 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 M described above. Substantially free of fluorine-containing compounds represented by the formula means that the amount of the fluorine-containing compounds is 25 mass ppb or less relative to the polymer composition. The amount of the fluorine-containing compounds 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 quantitation. The lower limit is not particularly limited, and may be an amount less than the lower limit of quantitation.

[0206] The polymer composition of the present disclosure preferably has endothermic peaks in the regions of 330°C or less and above 330°C. The presence of endothermic peaks in each of the above regions indicates that the polymer composition contains a fibrillating polymer and a thermoplastic polymer. The temperature range of the region of 330°C or less (also referred to as region (A)) is preferably less than 330°C, and is preferably 320°C or more, more preferably 324°C or more, and even more preferably 326°C or more. The temperature range of the region of above 330°C (also referred to as region (B)) is preferably 333°C or more, more preferably 335°C or more, and even more preferably 340°C or more, and is preferably 350°C or less, more preferably 348°C or less, and even more preferably 346°C or less.

[0207] The polymer composition of the present disclosure also preferably has an endothermic peak at least in the region of 130 to 200°C (also referred to as region (C)). The presence of an endothermic peak in region (C) indicates that the polymer composition contains, as a thermoplastic polymer, at least one VdF-based polymer selected from the group consisting of PVdF and VT. The temperature range of region (C) is preferably 190°C or lower, more preferably 180°C or lower, and is preferably 140°C or higher.

[0208] The endothermic peak temperatures are temperatures corresponding to the respective minimum points in the regions (A) to (C) of the heat of fusion curve when a polymer composition that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[0209] The polymer composition of the present disclosure also preferably has a 0.1% mass loss temperature of 340°C or higher. A 0.1% mass loss temperature within the above range indicates that the polymer composition contains a perfluoropolymer such as PFA or FEP as a thermoplastic polymer. The 0.1% mass loss temperature is more preferably 350°C or higher, even more preferably 370°C or higher, and is preferably 400°C or lower, and more preferably 390°C or lower. The 0.1% mass loss temperature is measured using the following method. Approximately 10 mg of a polymer composition that has not been heated to temperatures above 300°C is precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (differential thermal analysis / thermogravimetry) analyzer. The 0.1% mass loss temperature is determined by heating the aluminum pan in an air atmosphere from 25°C to 600°C at a rate of 10°C / min, and the temperature corresponds to the point at which a 0.1 mass% weight loss occurs.

[0210] The polymer composition of the present disclosure also preferably has a 1.0% mass loss temperature of 370°C or higher. A 1.0% mass loss temperature within the above range indicates that the polymer composition contains a perfluoropolymer such as PFA or FEP as a thermoplastic polymer. The 1.0% mass loss temperature is more preferably 400°C or higher, even more preferably 420°C or higher, even more preferably 440°C or higher, even more preferably 460°C or higher, and preferably 492°C or lower. The 1.0% mass loss temperature is measured by the following method. Approximately 10 mg of a polymer composition that has not been heated to temperatures above 300°C is precisely weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (differential thermal analysis / thermogravimetry) analyzer. The 1.0% mass loss temperature is determined by the temperature at which a 1.0 mass% weight loss occurs when the aluminum pan is heated in an air atmosphere from 25°C to 600°C at a rate of 10°C / min.

[0211] In order to further improve powder flowability, the polymer composition of the present disclosure preferably has an average aspect ratio in powder form of 2.5 or less, more preferably 2.0 or less, even more preferably 1.9 or less, even more preferably 1.8 or less, even more preferably 1.7 or less, even more preferably 1.6 or less, even more preferably 1.5 or less, even more preferably 1.4 or less, even more preferably 1.3 or less, and particularly preferably 1.2 or less. The average aspect ratio may also be 1.0 or more. The average aspect ratio is determined by thinly spreading the polymer composition powder on a black paper surface with air without applying shear, observing the polymer composition with an electron microscope, and processing the images of 100 or more randomly selected particles, and averaging the ratios of their major axis to minor axis.

[0212] The polymer composition of the present disclosure may have an average secondary particle size of 350 μm or more, preferably 400 μm or more, more preferably 450 μm or more, even more preferably 500 μm or more, even more preferably 550 μm or more, and particularly preferably 600 μm or more, and is preferably 1000 μm or less, more preferably 900 μm or less, even more preferably 800 μm or less, and even more preferably 700 μm or less. The average secondary particle size is measured in accordance with JIS K 6891.

[0213] In terms of excellent handleability, the polymer composition of the present disclosure preferably has an apparent density of 0.40 g / ml or more, more preferably 0.43 g / ml or more, even more preferably 0.45 g / ml or more, even more preferably 0.48 g / ml or more, and particularly preferably 0.50 g / ml or more. The upper limit is not particularly limited, but may be 0.70 g / ml. The apparent density is measured in accordance with JIS K 6892.

[0214] The form of the 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 or molding.

[0215] The polymer composition of the present disclosure can be produced by mixing a fibrillating polymer and a thermoplastic polymer. The mixing method is not limited, and both the fibrillating polymer and the thermoplastic polymer may be mixed in the form of powder, both may be mixed in the form of aqueous dispersion, or both may be mixed in the form of aqueous dispersion and powder. In terms of enabling more uniform mixing, it is preferable to mix both in the form of aqueous dispersion or to mix the form of aqueous dispersion and powder, and it is more preferable to mix both in the form of aqueous dispersion.

[0216] The polymer composition of the present disclosure can be suitably produced, for example, by a production method including the steps of: (A) mixing an aqueous dispersion of a fibrillating polymer with an aqueous dispersion or powder of a thermoplastic polymer; (B) coagulating the mixed aqueous dispersion to obtain a wet powder; and (C) drying (heat treating) the wet powder.

[0217] The aqueous dispersion of the fibrillating polymer can be produced, for example, by a production method including a step of emulsion polymerization of necessary monomers in an aqueous medium in the presence of a hydrocarbon surfactant. Hereinafter, the production method of the aqueous dispersion when the fibrillating polymer is a TFE-based polymer will be described in detail.

[0218] 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).

[0219] 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.

[0220] 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 specific hydrocarbon surfactants and other compounds having surface activity, such as -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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] 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.

[0228] The surfactant (a) can be produced, for example, by the production method described in WO 2020 / 022355.

[0229] The surfactant (b) can be produced, for example, by the production method described in WO 2020 / 022355.

[0230] The surfactant (c) can be produced, for example, by the production method described in WO 2020 / 022355.

[0231] The surfactant (d) can be produced, for example, by the production method described in WO 2020 / 022355.

[0232] The surfactant (e) can be produced by a known production method.

[0233] 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).

[0234] 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.).

[0235] 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).

[0236] The 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 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 are volatile or can remain in the molded body made of TFE polymer, etc.

[0237] 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.

[0238] 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).

[0239] 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).

[0240] 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).

[0241] 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).

[0242] 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.

[0243] 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).

[0244] Siloxane hydrocarbon surfactants are also disclosed in US Pat. No. 6,841,616.

[0245] 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.

[0246] 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.

[0247] The compound (α) may be R１０２ -COOM (in the formula, R １０２ is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the carbon number is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above. ) are also included. Specifically, CH ３ - (CH ２ ) ｎ -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0248] 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 NR１０１ 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.

[0249] The compound (β) includes 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).

[0250] 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.

[0251] Compound I exhibits low reactivity with polymerization initiators and / or propagating fluoropolymer radicals in emulsion polymerization of fluoromonomers.

[0252] 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.

[0253] 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.

[0254] As Compound II, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0255] 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.

[0256] As the compound III, for example, the following compounds are preferred. Y in the above formula ＋ may be hydrogen, ammonium, or an alkali metal.

[0257] Even if the 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 polymerizing tetrafluoroethylene alone or tetrafluoroethylene and the modified monomer copolymerizable with tetrafluoroethylene in an aqueous medium having a pH of 4.0 or more in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain a TFE polymer.Conventionally, the polymerization step for producing a 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 adjusting the pH of the aqueous medium used for polymerization to 4.0 or more, the stability of polymerization can be improved, and a TFE polymer with high molecular weight can be produced.The above-mentioned production method comprises polymerizing tetrafluoroethylene alone or tetrafluoroethylene and the modified monomer copolymerizable with tetrafluoroethylene in an aqueous medium having a pH of 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.

[0258] Even if the polymer composition of the present disclosure does not use the specific hydrocarbon surfactant, it can also be obtained by a polymerization step of polymerizing tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with tetrafluoroethylene in an aqueous medium in the presence of an anionic hydrocarbon surfactant and a polymerization initiator to obtain a TFE polymer, wherein the hydrocarbon surfactant contains a salt of the hydrocarbon surfactant. In other words, at least a portion of the anionic hydrocarbon surfactant in the polymerization step is in the form of a salt. As a result of extensive research by the present inventors, it was unexpectedly found that the stability of polymerization is improved by including a salt of the anionic hydrocarbon surfactant in the anionic hydrocarbon surfactant, and a TFE polymer with a large molecular weight can be produced. This is thought to be because the inclusion of a salt improves the water solubility of the anionic surfactant, making it easier to exhibit emulsification performance. The anionic hydrocarbon surfactant will be described later. The presence of a salt of the hydrocarbon surfactant in the anionic 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.

[0259] The polymer composition of the present disclosure can be suitably produced by a production method including an addition step of adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator. The addition step is carried out during the above-mentioned emulsion polymerization step in an aqueous medium. The radical concentration during polymerization can be adjusted by adding a radical scavenger or a decomposer of a polymerization initiator. From the viewpoint of reducing the radical concentration, a radical scavenger is preferred.

[0260] 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.

[0261] Examples of the radical scavenger in the present disclosure include aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxyamine, 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 the unsubstituted phenol 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 the 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.

[0262] 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).

[0263] 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).

[0264] 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.

[0265] 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.

[0266] The polymerization step may further comprise polymerizing tetrafluoroethylene in the presence of a nucleating agent.

[0267] 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.

[0268] The fluoropolyether is preferably a perfluoropolyether.

[0269] 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.)

[0270] 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.

[0271] 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.

[0272] 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.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] 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.

[0279] 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.

[0280] 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).

[0281] 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).

[0282] 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).

[0283] 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.

[0284] 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.

[0285] 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.

[0286] 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.

[0287] 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.

[0288] 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.

[0289] 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.

[0290] 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.

[0291] As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

[0292] 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.

[0293] 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.

[0294] 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.

[0295] 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.

[0296] 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.

[0297] 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.

[0298] 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.

[0299] 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.

[0300] 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.

[0301] 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.

[0302] In the emulsion polymerization, a known chain transfer agent may be added depending on the purpose to adjust the polymerization rate and molecular weight.

[0303] 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.

[0304] 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.

[0305] 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.

[0306] 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.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] The aqueous dispersion or powder of the thermoplastic polymer in step (A) can be produced by a known method such as suspension polymerization, emulsion polymerization, solution polymerization, etc. Among these, suspension polymerization and emulsion polymerization are preferred, and emulsion polymerization is more preferred.

[0311] The coagulation in step (B) can be carried out by a known method. When coagulating an aqueous dispersion of a TFE-based polymer, the aqueous dispersion obtained by polymerization of a polymer latex or the like is usually diluted with water to a polymer concentration of 10 to 25% by mass (preferably a polymer concentration of 10 to 20% by mass), and in some cases, the pH is adjusted to neutral or alkaline, and then the mixture is stirred more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be carried out while stirring while adding a water-soluble organic compound such as methanol or acetone, an inorganic salt such as potassium nitrate or ammonium carbonate, or an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid as a coagulant. The coagulation may also be carried out continuously using an in-line mixer or the like.

[0312] The drying (heat treatment) in step (C) is usually carried out by means of vacuum, high frequency, hot air, or the like, while keeping the wet powder in a state where it is not fluidized much, preferably in a static state. Friction between powders, especially at high temperatures, generally has an undesirable effect on fine powder fibrillating polymers. This is because particles made of this type of fibrillating polymer tend to easily fibrillate even with a small shear force, losing their original stable particle structure.

[0313] The drying temperature in step (C) is preferably 130° C. or higher, more preferably 140° C. or higher, even more preferably 150° C. or higher, even more preferably 160° C. or higher, even more preferably 180° C. or higher, even more preferably 200° C. or higher, particularly preferably 220° C. or higher, and is preferably 300° C. or lower, more preferably 280° C. or lower, and even more preferably 250° C. or lower, from the viewpoint of more efficiently removing moisture and fluorine-containing compounds.

[0314] The drying time in step (C) is preferably 2 hours or more, more preferably 5 hours or more, even more preferably 10 hours or more, and even more preferably 15 hours or more, from the viewpoint of more efficiently removing moisture and the fluorine-containing compound. The upper limit is not particularly limited, but is, for example, preferably 100 hours, more preferably 50 hours, and even more preferably 30 hours.

[0315] The air velocity in step (C) is preferably 0.01 m / s or more, more preferably 0.03 m / s or more, even more preferably 0.05 m / s or more, and even more preferably 0.1 m / s or more, from the viewpoint of more efficiently removing moisture and fluorine-containing compounds, and is preferably 50 m / s or less, more preferably 30 m / s or less, and even more preferably 10 m / s or less, from the viewpoint of suppressing scattering of powder.

[0316] The drying in step (C) can be carried out using an electric furnace or a steam furnace. For example, it can be carried out using an electric furnace such as a parallel-flow box-type electric furnace, a ventilated box-type electric furnace, a ventilated conveyor-type electric furnace, a band furnace, a radiant conveyor-type electric furnace, a fluidized-bed electric furnace, a vacuum electric furnace, an agitator-type electric furnace, an airflow-type electric furnace, or a hot-air circulation electric furnace, or a steam furnace corresponding to the above (an apparatus obtained by replacing the electric furnace in the apparatus name of each of the above electric furnaces with a steam furnace). In terms of being able to remove moisture and fluorine-containing compounds more efficiently, a parallel-flow box-type electric furnace, a ventilated box-type electric furnace, a ventilated conveyor-type electric furnace, a band furnace, a fluidized-bed electric furnace, a hot-air circulation electric furnace, or a steam furnace corresponding to the above (an apparatus obtained by replacing the electric furnace in the apparatus name of each of the above electric furnaces with a steam furnace) is preferred.

[0317] The drying in step (C) is preferably carried out by placing the wet powder in a container whose bottom and / or sides are breathable, since this allows for more efficient removal of moisture and fluorine-containing compounds. The container whose bottom and / or sides are breathable may be any container that can withstand the drying temperature, but is preferably made of a metal such as stainless steel. As the container whose bottom and / or sides are breathable, a tray (bath) whose bottom and / or sides are breathable is preferred, and a tray whose bottom and / or sides are made of mesh (mesh tray) is more preferred. The mesh is preferably either a woven mesh or a punched metal. The mesh opening is preferably 2000 μm or less (ASTM standard 10 mesh or more), more preferably 595 μm or less (30 mesh or more), even more preferably 297 μm or less (50 mesh or more), even more preferably 177 μm or less (80 mesh or more), particularly preferably 149 μm or less (100 mesh or more), and particularly preferably 74 μm or less (200 mesh or more). Furthermore, it is preferably 25 μm or more (500 mesh or less). When the mesh is a woven net, the weaving method may be, for example, plain weave, twill weave, plain dutch weave, or twill dutch weave. When the mesh is a punched metal, the opening rate is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. Furthermore, it is preferably 95% or less.

[0318] In the step (C), the amount of the wet powder to be placed is 10 g / cm from the viewpoint of more efficiently removing moisture and fluorine-containing compounds. ２ Preferably, it is 8 g / cm or less. ２ More preferably, it is 5 g / cm or less. ２ More preferably, it is 3 g / cm or less. ２ It is particularly preferable that the density is 0.01 g / cm or less. ２ It is preferable that the density is 0.05 g / cm or more. ２ More preferably, it is 0.1 g / cm or more. ２ More preferably, it is equal to or greater than this.

[0319] The moisture content of the wet powder to be dried in step (C) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the wet powder, in order to more efficiently remove moisture and the fluorine-containing compound, and is preferably 150% by mass or less, and more preferably 100% by mass or less.

[0320] The polymer composition of the present disclosure can also be suitably produced by a production method including step (D) of mixing a powder of a fibrillating polymer with a powder of a thermoplastic polymer.

[0321] The fibrillating polymer powder in step (D) can be produced, for example, by coagulating an aqueous dispersion of the fibrillating polymer obtained by emulsion polymerization, followed by drying. The aqueous dispersion can be produced by the same method as the aqueous dispersion of the fibrillating polymer obtained by emulsion polymerization in step (A). The coagulation and drying can be carried out by the same methods as in steps (B) and (C).

[0322] The thermoplastic polymer powder in step (D) can be produced by the same method as that for the thermoplastic polymer powder in step (A).

[0323] The mixing in step (D) can be carried out by a dry mixing method. From the viewpoint of improving powder flowability, it is preferable to adopt a mixing method that applies a weak shear force so as to suppress fibrillation of the fibrillating polymer. For example, it is preferable to adopt a mixing method that does not use a stirring blade, such as airflow mixing or mixing using a V-blender.

[0324] The polymer composition of the present disclosure is used in a binder for electrochemical devices. In the binder for electrochemical devices, the polymer composition of the present disclosure may be used alone or in a mixture with other materials. However, it is preferable to use the polymer composition of the present disclosure substantially alone, and more preferably to use it alone. Note that using the polymer composition of the present disclosure substantially alone means that the amount of the polymer composition in the binder for electrochemical devices is used within the range described below.

[0325] The present disclosure also provides a binder for electrochemical devices consisting essentially of a polymer composition, the polymer composition including a fibrillating polymer, a thermoplastic polymer, and 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) (hereinafter also referred to as binder (1) of the present disclosure). 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, NR５ ４ (R ５ is the same as above), optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. q is 1 or 2.

[0326] The present disclosure also provides a binder for electrochemical devices consisting essentially of a polymer composition, wherein the polymer composition contains a fibrillating polymer and a thermoplastic polymer, and the thermal instability index (TII) of the fibrillating polymer is 10 or more (hereinafter also referred to as binder (2) of the present disclosure).

[0327] In this specification, unless otherwise specified, binders (1) and (2) of the present disclosure will be collectively referred to as "binders of the present disclosure."

[0328] The binder of the present disclosure, by containing a specific polymer composition, can improve the Coulombic efficiency of electrochemical devices. Furthermore, a mixture sheet can be produced even with a small additive amount. Furthermore, since a mixture sheet with excellent adhesion to a substrate such as a metal foil can be obtained, the mixture sheet and the substrate can be bonded without increasing the density of the mixture layer (without compaction), allowing for processing under a wider range of molding conditions. When the binder of the present disclosure is in powder form, it can also improve flowability. Furthermore, since the binder of the present disclosure can be used in a dry process, there is no need to use large amounts of a dispersion medium such as water or an organic solvent, and a wide range of electrode active materials and solid electrolytes can be selected for combination, which is advantageous in the production process. Furthermore, the process and costs associated with the use of a dispersion medium can be reduced. Furthermore, since the binder of the present disclosure has excellent binding strength with active materials and electrolytes, the amount used can be reduced.

[0329] As the polymer composition in the binder of the present disclosure, the same polymer composition as the above-described polymer composition of the present disclosure can be used, and the preferred embodiments are also the same.

[0330] The binder of the present disclosure consists essentially of the polymer composition. This allows the effects of the polymer composition to be significantly exhibited. "Consisting essentially of the polymer composition" means that the content of the polymer composition is 95.0% by mass or more relative to the binder. The content of the 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 consists essentially of the polymer composition.

[0331] 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.

[0332] The binder of the present disclosure is preferably in the form of a powder, but may be in a form other than a powder, for example, a dispersion or a molded body.

[0333] 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.

[0334] 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. 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.

[0335] The present disclosure also provides an electrode mixture comprising the polymer composition or binder of the present disclosure described above and an electrode active material. The use of the electrode mixture of the present disclosure can improve the Coulombic efficiency of an electrochemical device. Furthermore, because the electrode active material can be held in place even with a small amount of binder, it is possible to add more materials that improve electrochemical device characteristics, such as active materials and conductive additives. Furthermore, because a mixture sheet with excellent adhesion to a substrate such as a metal foil can be obtained, the mixture sheet and substrate can be bonded without increasing the density of the mixture layer (without compaction), allowing processing under a wider range of molding conditions.

[0336] Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0337] 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.

[0338] Examples of the alkali metal-containing transition metal composite oxide include those represented by the formula: M ａ Mn ２－ｂM 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 ３ is 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.

[0339] 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.

[0340] 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 ４ represents 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.

[0341] 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 LiCoPO４ 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.

[0342] 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.

[0343] 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.

[0344] 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.

[0345] 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 O ２ 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.

[0346] 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.

[0347] 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.

[0348] 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.

[0349] 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.

[0350] 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.

[0351] 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.

[0352] 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 Mn ０．３３ 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.

[0353] 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.

[0354] 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.

[0355] 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.

[0356] 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.

[0357] 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.

[0358] 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.

[0359] 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.

[0360] 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.

[0361] The electrode mixture of the present disclosure preferably further contains a conductive aid. Any known conductive material can be used as the conductive aid. Specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and carbon materials such as needle coke, carbon nanotubes, fullerenes, and amorphous carbon such as VGCF. These materials may be used alone or in any combination and ratio of two or more.

[0362] The conductive additive is used in an amount of typically 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and typically 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less, in the electrode mixture. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0363] The electrode mixture of the present disclosure may further contain a thermoplastic resin. Examples of the thermoplastic resin include polyvinylidene fluoride, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, and polyethylene oxide. One type may be used alone, or two or more types may be used in any combination and ratio.

[0364] The ratio of the thermoplastic resin 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 resin can improve the mechanical strength of the electrode. Furthermore, if the ratio exceeds this range, the ratio 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.

[0365] 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.

[0366] In the electrode mixture of the present disclosure, the binder component preferably consists essentially of the polymer composition, more preferably consists essentially of the polymer composition. The binder component consisting essentially of the polymer composition means that the content of the 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 polymer composition is preferably 98.0% by mass or more, 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 relative to the binder component.

[0367] The electrode mixture of the present disclosure is preferably in the form of a sheet.

[0368] 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.

[0369] 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, 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.

[0370] 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: (1) mixing a raw material composition containing an electrode active material, a binder, and, if necessary, a conductive additive; (2) forming the raw material composition obtained in the step (1) into a bulk; and (3) rolling the bulk raw material composition obtained in the step (2) into a sheet.

[0371] At the stage where the raw material composition is mixed in the above step (1), the raw material composition is simply a mixture of the electrode active material, binder, etc. and exists in a state without a definite shape. 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, an agitator mixer, a planetary mixer, a Henschel mixer, a high-speed mixer, etc.

[0372] In the above step (1), the binder mixing condition is preferably 3000 rpm or less. It is preferably 10 rpm or more, more preferably 15 rpm or more, and even more preferably 20 rpm or more, and is preferably 2000 rpm or less, more preferably 1500 rpm or less, and even more preferably 1000 rpm or less. If the mixing speed is below the above range, it takes a long time to mix, which affects productivity. Furthermore, if the speed is above the above range, fibrillation may proceed excessively, resulting in an electrode mixture sheet with poor strength and flexibility.

[0373] In the above step (2), forming into a bulk form refers to forming the raw material composition into a single mass. Specific methods for forming into a bulk form include extrusion molding, press molding, etc. Furthermore, the term "bulk form" does not specify a particular shape, and may refer to a state in which the raw material composition is in the form of a single mass, including rod-like, sheet-like, spherical, cube-like, and other shapes.

[0374] Specific examples of the rolling method in the step (3) include rolling methods using a roll press, a plate press, a calender roll, or the like.

[0375] It is also preferable to include a step (4) after step (3), 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 (4). 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 (4) 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.

[0376] From the viewpoint of adjusting the fibril diameter, it is also preferable to include a step (5) after step (3) or step (4) in which the rolled sheet is roughly crushed, then re-formed into a bulk form, and rolled into a sheet. It is also preferable to repeat step (5). The number of times step (5) is performed is preferably from 1 to 12 times, more preferably from 2 to 11 times.

[0377] In step (5), specific methods for roughly crushing the rolled sheet and forming it into a bulk form include folding the 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 (3) or (4) into a different form in order to roll it into a sheet in the next step, and also includes simply folding the rolled sheet.

[0378] Furthermore, step (4) may be performed after step (5), or may be repeated. Furthermore, uniaxial or biaxial stretching may be performed in steps (2), (3), (4), and (5). Furthermore, the fibril diameter can be adjusted by the degree of crushing in step (5).

[0379] In the above steps (3), (4), or (5), 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 time and affects productivity. If the rolling ratio is above the above range, fibrillation may proceed excessively, resulting in an electrode mixture sheet with poor strength and flexibility. The rolling ratio here refers to the reduction rate of the thickness of the sample after processing relative to the thickness before rolling. The sample before rolling may be a bulk raw material composition or a sheet-like raw material composition. The thickness of the sample refers to the thickness in the direction in which a load is applied during rolling.

[0380] 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 raw material mixture obtained in step (a1) to prepare the electrode mixture.

[0381] 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.

[0382] 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.

[0383] 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.

[0384] 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.

[0385] 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).

[0386] In the step (a2), the raw material 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 powdery raw material mixture obtained in the step (a1) to prepare a paste.

[0387] 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).

[0388] 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.

[0389] When the above-mentioned lubricant is used, it is particularly preferable that the lubricant is a solvent with low polarity such as butyl butyrate, or an ether compound.

[0390] When the above-mentioned lubricant is used, the amount thereof may be 5.0 to 35.0 parts by weight, preferably 10.0 to 30.0 parts by weight, more preferably 15.0 to 25.0 parts by weight, based on the total weight of the composition subjected to step (a1).

[0391] It is preferable that the raw material composition substantially does not contain a 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 preparing an electrode mixture sheet by applying and drying the slurry. In this case, a solvent that disperses or dissolves the binder is used. However, solvents that can dissolve binder resins that have been commonly used in the past are limited to specific solvents such as N-methylpyrrolidone. Because of their high polarity and the need for a drying process, the use of solvents incurs additional steps and costs. Furthermore, these solvents react with electrolytes, such as electrolytic solutions and solid electrolytes, degrading the electrolyte, and residual components during slurry preparation or after drying can cause a decrease in battery performance. Furthermore, low-polarity solvents such as heptane dissolve very limited binder resins, and their low flash points can make handling difficult.

[0392] By using a powder binder with low moisture content without using a solvent when forming the electrode mixture sheet, a battery with little electrolyte deterioration can be manufactured. Furthermore, in the manufacturing method described above, an electrode mixture sheet containing a binder with a fine fibrous structure can be manufactured, and by not preparing a slurry, the burden on the manufacturing process can be reduced.

[0393] 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.

[0394] 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.

[0395] 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.

[0396] The step (b) is preferably carried out at 30 to 150° 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.

[0397] Furthermore, calendering or extrusion applies shear force, which causes the PTFE to fibrillate and form.

[0398] 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.

[0399] 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.

[0400] 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.

[0401] 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).

[0402] 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, which increases the time required 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 raw material composition or a sheet-like raw material 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 150°C or lower.

[0403] 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.

[0404] The present disclosure also provides an electrode comprising the polymer composition or binder of the present disclosure, an electrode active material, and a current collector. The electrode of the present disclosure can improve the Coulombic efficiency of an electrochemical device. Furthermore, because the electrode active material can be held in place even with a small amount of binder, it is possible to add more materials that improve electrochemical device properties, such as active materials and conductive additives. The electrode also exhibits excellent adhesion between the composite sheet and a substrate such as a metal foil.

[0405] 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.

[0406] The electrodes of the present disclosure may be positive electrodes or negative electrodes.

[0407] 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.

[0408] 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.

[0409] 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.

[0410] 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.

[0411] 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.

[0412] 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.

[0413] 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.

[0414] 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.

[0415] 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.

[0416] 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.

[0417] The present disclosure also provides a secondary battery comprising the electrode of the present disclosure described above.

[0418] 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.

[0419] 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.

[0420] 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.

[0421] 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.

[0422] 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.

[0423] 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.

[0424] 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.

[0425] 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.

[0426] 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.

[0427] 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] 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.

[0432] 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 etc.), 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.

[0433] 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.

[0434] 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.

[0435] 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.

[0436] 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.

[0437] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0438] Various physical properties were measured by the following methods.

[0439] <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.

[0440] <Polymer solid content concentration> 1 g of the aqueous polymer dispersion was dried in a blower dryer at 150°C for 60 minutes, and the ratio of the mass of the heating residue to the mass (1 g) of the aqueous dispersion was expressed as a percentage and used as the solid content concentration.

[0441] <Content of modified monomer in PTFE> The HFP content was determined by press-molding a polymer composition into a thin film disk, measuring the infrared absorbance of the thin film disk by FT-IR, and determining the HFP content at 982 cm －１ Absorbance at / 935 cm －１ The absorbance ratio was calculated by multiplying the absorbance ratio at 0.3.

[0442] <Endothermic Peak Temperature> A 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.

[0443] <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.

[0444] <Average aspect ratio of polymer composition (powder)> The polymer composition powder was thinly spread on a black paper surface using air without applying shear, and the polymer composition was observed under an electron microscope. 100 or more randomly selected particles were subjected to image processing, and the average aspect ratio of the major axis to the minor axis was determined.

[0445] <Presence or absence of fibrillation> The powder of the polymer composition was thinly spread on a black paper surface using air without applying shear, and the fibrillating polymer (PTFE) contained in the polymer composition was observed under an electron microscope. Images of 100 or more randomly selected particles were processed, and the average aspect ratio of the fibrillating polymer powder was calculated from the average ratio of their major axis to their minor axis. If the average aspect ratio was 2.5 or less, the fibrillating polymer powder was determined to be not fibrillated.

[0446] <Thermoplastic polymer composition> １ H-NMR analysis, １９ It was measured by F-NMR analysis.

[0447] <MFR> In accordance with ASTM D1238, the mass (g / 10 min) of polymer flowing out per 10 min from a nozzle having an inner diameter of 2 mm and a length of 8 mm was measured using a melt indexer at a measurement temperature and load determined depending on the type of fluoropolymer.

[0448] <Melting Point of Thermoplastic Polymer> The melting point was determined as the temperature corresponding to the maximum value on the heat of fusion curve when the temperature was increased for the second time at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[0449] <Weight-average molecular weight of VT> Measured by gel permeation chromatography (GPC). Calculations were made from data measured at 50°C using a Tosoh HLC-8320GPC column (three SuperAWM-H columns connected in series) and dimethylformamide (DMF) as a solvent (reference: polystyrene).

[0450] <Average particle size of PVdF and VT powders> Using a Beckman Coulter laser diffraction particle size distribution analyzer (LS13 320), the average particle size was measured in a dry state at a vacuum pressure of 20 mH. ２The average particle size was determined based on the particle size distribution (volume basis) obtained. The average particle size was set to be equal to the particle size corresponding to 50% of the integrated particle size distribution.

[0451] <Amount of Fluorine-Containing Surfactant in PVdF and VT Powders> 1 g of each powder was weighed, 10 g (12.6 ml) of methanol was added, and ultrasonic treatment was performed for 60 minutes to obtain an extract. The obtained extract was measured by LC / MS / MS. The fluorine-containing compounds in the extract were measured using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The measurement equipment configuration and LC-MS measurement conditions are shown in Table 1. Using aqueous solutions of fluorine-containing compounds with known concentrations, aqueous solutions with five or more levels of content were prepared, and LC / MS analysis of the aqueous solutions with each content was performed. The relationship between the content and the area area relative to the content was plotted to draw a calibration curve. Using the calibration curve, the area area of ​​the LC / MS chromatogram of the fluorine-containing compounds in the extract was converted to the content of the fluorine-containing compounds. Note that the lower limit of detection in this measurement method is 10 ppb by mass.

[0452]

[0453] <Mooney viscosity of fluoroelastomer (ML1+10 (121°C, 140°C))> Measured in accordance with ASTM D1646-15 and JIS K6300-1:2013. Measuring instrument: MV2000E model manufactured by ALPHA TECHNOLOGIES, Inc. Rotor rotation speed: 2 rpm Measurement temperature: 121°C, 140°C Measurement time: After 1 minute of preheating, the rotor was immediately rotated and the value after 10 minutes was measured.

[0454] <Heat of fusion of fluoroelastomer> A differential scanning calorimeter (X-DSC823e, manufactured by Hitachi Technoscience Co., Ltd.) was used to obtain a DSC curve by heating 10 mg of a sample at a rate of 20°C / min, and the heat of fusion was calculated from the magnitude of the melting peak (ΔH) that appeared in the DSC curve.

[0455] <Glass transition temperature (Tg) of fluoroelastomer> A DSC curve was obtained by heating 10 mg of a sample at a rate of 20°C / min using a differential scanning calorimeter (X-DSC823e, manufactured by Hitachi Technoscience Co., Ltd.), and the glass transition temperature was determined as the temperature at the intersection of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

[0456] <Weight-average molecular weight of fluoroelastomer> Measured by gel permeation chromatography (GPC). Calculations were made from data measured using Tosoh AS-8010, CO-8020, a column (three GMHHR-H columns connected in series) and Shimadzu RID-10A, using dimethylformamide (DMF) as a solvent at a flow rate of 1.0 ml / min (reference: polystyrene).

[0457] <Water Content> Approximately 20 g of the polymer composition was heated at 150°C for 2 hours, and the mass was measured before and after the heating, 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 polymer composition before heating) - (mass (g) of polymer composition after heating)] / (mass (g) of polymer composition before heating) x 100

[0458] <0.1% Mass Loss Temperature> Approximately 10 mg of a 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 0.1 mass% weight loss occurred when the aluminum pan was heated in an air atmosphere over a temperature range from 25° C. to 600° C. at a rate of 10° C. / min.

[0459] <1.0% Mass Loss Temperature> Approximately 10 mg of a 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 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 over a temperature range from 25° C. to 600° C. at a rate of 10° C. / min.

[0460] <Thermal Instability Index (TII)> Measured in accordance with ASTM D 4895-89.

[0461] <Content of specific fluorine-containing compounds> The content was measured using liquid chromatography mass spectrometry under the following conditions.

[0462] [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.

[0463] 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.

[0464] 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)

[0465] Measurement equipment configuration and LC-MS measurement conditions

[0466] MRM measurement parameters

[0467] 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.

[0468] MRM measurement parameters

[0469] 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.

[0470] 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.

[0471] [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.

[0472] 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.

[0473] 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)

[0474] Measurement equipment configuration and LC-MS measurement conditions

[0475] MRM measurement parameters

[0476] 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.

[0477] MRM measurement parameters

[0478] 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.

[0479] 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.

[0480] A white solid A was obtained by the method described in Synthesis Example 1 of WO 2021 / 045228.

[0481] 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.

[0482] 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 removed from the reactor, cooled, and the paraffin wax was separated to obtain an aqueous PTFE dispersion. The pH of the obtained aqueous PTFE dispersion was 8.8, the solid content was 27.1 mass%, and the primary particle size was 220 nm.

[0483] The resulting PTFE aqueous dispersion was diluted with deionized water to a solids concentration of 13% by mass, vigorously stirred in a container equipped with a stirrer, and then coagulated. The water was then filtered off to obtain a wet powder. The resulting wet powder was placed on a stainless steel mesh tray and heat-treated in a hot air circulating electric furnace at 210°C. After 18 hours, the mesh tray was removed and air-cooled to obtain a PTFE powder. The resulting PTFE powder had a moisture content of 0.002% by mass, a standard specific gravity of 2.170, a thermal instability index of 44, an HFP content of 0.002% by mass, a 0.1% mass loss temperature of 391°C, and a 1.0% mass loss temperature of 491°C. The resulting PTFE powder contained 67 ppb by mass of compounds represented by general formula (1) with carbon number m (4-20), and less than 10 ppb by mass of compounds represented by general formula (2) with carbon number n (4-20).

[0484] Preparation Example 2: 3,580 g of deionized water and 7.56 g of white solid A were placed in a 6 L stainless steel reactor equipped with a stirrer. The contents of the reactor were then heated to 70°C while simultaneously evacuating and purging with TFE to remove oxygen from the reactor, and the contents were stirred. 0.5 g of ethane and 71 g of perfluoropropyl vinyl ether (PPVE) were added to the reactor, followed by the addition of TFE until the pressure reached 2.4 MPaG. 306 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor. After the initiator was injected, a pressure drop occurred, and the initiation of polymerization was observed. TFE was added to the reactor to maintain a constant pressure of 2.4 MPaG. After the initiation of polymerization, 108 mg of ammonium persulfate and 84 g of PPVE were continuously added. When the amount of TFE consumed in the reaction reached about 1600 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the pressure in the reactor was vented to normal pressure, and PFA aqueous dispersion 1 was obtained. PFA aqueous dispersion 1 was taken out of the reactor into the atmosphere and cooled, and PFA aqueous dispersion 2 was obtained. The solids concentration of the obtained PFA aqueous dispersion 2 was 30.5% by mass. The obtained PFA aqueous dispersion 2 was stirred, coagulated, and dried to obtain PFA powder. The PPVE content of the obtained PFA powder was 6.5% by mass, the MFR was 2.1 g / 10 min, and the melting point was 295 ° C.

[0485] Production Example 3 Into a 1000L capacity SUS reactor equipped with a stirrer, 655L of deionized water and 6kg of white solid A were charged, followed by nitrogen substitution and vacuum degassing to remove oxygen from the reactor and stirring the contents. Then, 100kg of HFP monomer was charged, and further, a mixed monomer of TFE and HFP (TFE:HFP = 86:14 (mass%)) was charged, and the temperature was increased while stirring, and the contents of the reactor were heated to 95 ° C. and pressurized to 1.5 MPaG. 70kg of a 10% by mass aqueous solution of ammonium persulfate (APS) was charged as an initiator, and the reaction was initiated. The above mixed monomer was continuously fed so as to maintain 1.5 MPaG in the reaction system. 30 minutes after the start of the reaction, stirring was stopped, the reaction was terminated, and the gas in the reactor was released to normal pressure to obtain a TFE / HFP binary polymer aqueous dispersion. The solids concentration of the resulting TFE / HFP dipolymer aqueous dispersion was 4.5% by mass.

[0486] Separately, 600 L of deionized water and 20 kg of the above binary polymer emulsion dispersion were charged into a similar SUS reactor, and nitrogen substitution and vacuum degassing operations were performed to remove oxygen from the reactor, and the contents were stirred. Then, 138 kg of HFP monomer and 4 kg of PPVE were charged, and the temperature was increased while stirring. The contents of the reactor were heated to 95 ° C., and a mixed monomer of TFE and HFP (TFE:HFP = 87.3:12.7 (mass%)) was injected to raise the pressure to 4.2 MPaG. 2.8 kg of a 10 mass% APS aqueous solution was charged as an initiator to initiate the reaction. After the reaction started, the 10 mass% APS aqueous solution was continuously added at a rate of about 20 g / min. During the reaction, 180 g of PPVE was charged each time the amount of the mixed monomer reached 25 mass%, 50 mass%, and 75 mass% of the total amount of monomer supplied. The above-mentioned mixed monomers were continuously fed so as to maintain the pressure in the reaction system at 4.2 MPaG. 51 minutes after the start of the reaction, the addition of 10% by mass APS aqueous solution was stopped, stirring was stopped to terminate the reaction, and the gas in the reactor was released to normal pressure, obtaining an aqueous FEP dispersion of TFE / HFP / PPVE. The solid content concentration of the obtained aqueous FEP dispersion of TFE / HFP / PPVE was 20.2% by mass. The obtained polymer had an MFR of 35.7 g / 10 min, a composition ratio (mass%) of TFE / HFP / PPVE=87.6 / 11.5 / 0.9, and a melting point of 257 ° C.

[0487] Production Example 4 A PVdF aqueous dispersion was obtained with reference to Example 1 of JP 2014-141673 A. That is, 1700 g of pure water and 0.85 g of H—(CF) ２ CF ２ ) ３ -CH ２ —O—CO—CH ２ CH(-SO ３ Na)-CO-O-CH ２ -(CF ２ CF ２ ) ３ The reactor was charged with 17 g of H-(CF) (surface tension 22 mN / m) and paraffin wax, and the atmosphere was replaced with nitrogen to remove oxygen. 150 g of vinylidene fluoride (VdF) was added, and the temperature inside the reactor was raised to 115°C. While stirring the contents, 0.5 g of acetone and 5.6 g of di-t-butyl peroxide were added to initiate the reaction. 427 g of vinylidene fluoride was added over 9 hours to maintain the pressure inside the reactor at 4.0 MPaG, and 1.45 g of H-(CF) was added during the reaction. ２ CF ２ ) ３ -CH ２ —O—CO—CH ２ CH(-SO ３ Na)-CO-O-CH ２ -(CF ２ CF ２ ) ３ -H was added to obtain a PVdF aqueous dispersion. The solids concentration of the obtained PVdF aqueous dispersion was 20.6% by mass. The obtained PVdF aqueous dispersion was coagulated, dried at 120°C, and pulverized to obtain a PVdF powder. The PVdF had a melting point of 161°C, an average particle size of 1.1 μm, and a fluorine-containing surfactant content of 110 ppb by mass.

[0488] Production Example 5: 1.3 kg of pure water was charged into a 4 L reactor, and nitrogen substitution was performed to remove oxygen. Then, 0.88 kg of octafluorocyclobutane was charged, and the system was heated to 37 ° C and stirred. A mixed gas of TFE / VdF = 5 / 95 mol% was then charged until the system pressure reached 1.3 MPaG, after which 1.5 g of a 50 mass% methanol solution of di-n-propyl peroxydicarbonate was added to initiate the reaction. Since the system pressure decreased as the reaction progressed, a mixed gas of TFE / VdF = 15 / 85 mol% was continuously supplied to maintain the system pressure at 1.3 MPaG. The reaction was continued for 44 hours. The stirring was stopped to terminate the reaction, and the pressure was released to atmospheric pressure. The reaction product was then washed with water and dried at 120 ° C to obtain a white powder. The resulting white powder was pulverized in a high-speed mill to obtain a VT powder. The melting point of the obtained VT powder was 136° C., the composition ratio was VdF / TFE=85.0 / 15.0 (mol %), the weight average molecular weight was 1,100,000, and the average particle size of the powder was 1.0 μm. Since no fluorine-containing surfactant was used, the powder did not contain any fluorine-containing surfactant.

[0489] Production Example 6 Into a 3 L stainless steel polymerization vessel equipped with a stirrer, 1500 g of deionized water, 4.8 g of a fluorine-containing surfactant (white solid A), 0.3 g of CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４The vessel was then sealed. After purging with nitrogen, the vessel was evacuated and 400 cc of isopropyl alcohol as a chain transfer agent was introduced into the vessel while vacuum suction was performed using a syringe. Then, while stirring at 70°C, a mixed gas monomer having a vinylidene fluoride (VdF) / tetrafluoroethylene (TFE) composition ratio of 67 / 33 mol% was introduced into the vessel up to 0.8 MPaG. Then, an aqueous solution containing 0.15 g of ammonium persulfate was introduced under nitrogen pressure to initiate the reaction. An additional mixed monomer having a VdF / TFE composition ratio of 67 / 33 mol% was introduced to maintain the pressure inside the vessel. When the amount of added monomer reached 346 g, stirring was stopped, and the gas inside the vessel was released to terminate the reaction. The vessel was then cooled to obtain a VT aqueous dispersion. The solids concentration of the obtained VT aqueous dispersion was 20% by mass. The resulting VT aqueous dispersion had a composition ratio of VdF / TFE = 67.0 / 33.0 (mol %), a weight-average molecular weight of 1,300,000, and a melting point of 160°C. The resulting VT aqueous dispersion was stirred, coagulated, and dried at 120°C to obtain a powder. The resulting powder was pulverized in a high-speed mill to obtain a VT powder. The resulting VT powder had an average particle size of 1.1 μm and a fluorine-containing surfactant content of 340 ppb by mass.

[0490] Production Example 7 1650 ml of pure water was placed in a 3 L SUS autoclave and purged with nitrogen, slightly pressurized with hexafluoropropylene (HFP), and the temperature was adjusted to 80 ° C. while stirring. HFP was injected up to 0.23 MPaG, and further a mixed monomer solution of vinylidene fluoride (VdF) and HFP in a molar ratio of 78.2 / 21.8 was injected up to 1.472 MPaG. 0.097 ml of 2-methylbutane was injected with nitrogen, and a solution of 36.4 g of ammonium persulfate dissolved in 80 ml of pure water was injected with nitrogen to start the reaction. When the pressure dropped to 1.44 MPaG, the pressure was increased to 1.50 MPaG with continuous monomer and maintained. After about 9.3 hours had passed since the start of the reaction, 607 g of continuous monomer was charged, and stirring was stopped. The gas in the autoclave was released, and 2299 g of dispersion was recovered after cooling. The solids concentration of the resulting aqueous elastomer dispersion was 26.9% by mass. The composition of the resulting elastomer was VdF / HFP = 77.9 / 22.1 (mol %). The Mooney viscosity (ML1+10 (140°C)) of the resulting elastomer was 77, the weight average molecular weight was 850,000, and the Tg was -18°C as measured by DSC. No heat of fusion was observed in the second run.

[0491] Production Example 8: A 6-liter SUS reactor equipped with a stainless steel 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 reactor was heated to 70 ° C. while the atmosphere inside the reactor was replaced 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 the paraffin wax was separated to obtain a PTFE aqueous dispersion. The average primary particle diameter of the obtained PTFE aqueous dispersion was 310 nm, and the solid content concentration was 25.3 mass%. The obtained PTFE aqueous dispersion was coagulated and dried to obtain a PTFE powder. The SSG of the obtained PTFE powder was 2.156, and the endothermic peak temperature was 343 ° C.

[0492] 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.

[0493] Production Example 9: 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.

[0494] The obtained TFE-based polymer aqueous dispersion B was diluted with deionized water to a solids concentration of 13% by mass, and vigorously stirred in a container equipped with a stirrer to solidify, and then filtered to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray, and the mesh tray was heat-treated in a hot air circulation electric furnace at 210 ° C. After 18 hours, the mesh tray was removed and air-cooled to obtain a PTFE powder. The obtained PTFE powder had a water content of 0.003% by mass, a standard specific gravity of 2.151, a thermal instability index of 42, a 0.1% by mass loss temperature of 397 ° C, and a 1.0% by mass loss temperature of 492 ° C. Compounds represented by general formula (1) with carbon numbers m = 15 and 16 were detected in the obtained PTFE powder, and the content of the compound represented by general formula (1) with carbon number m = 15 was 73 ppb by mass, and the content of the compound represented by general formula (1) with carbon number m = 16 was 141 ppb by mass. In addition, compounds represented by general formula (2) having carbon atoms n=4, 6, 8, 10, 12, and 14 were detected, and the content of the compound represented by general formula (2) having carbon atoms n=8 was 1413 ppb by mass.

[0495] Preparation Example 1: 886g of the PTFE aqueous dispersion obtained in Preparation Example 1 and 197g of the PFA aqueous dispersion 2 obtained in Preparation Example 2 are placed in a container, diluted with deionized water to a solid content of 13% by mass, and the PTFE / PFA mixture is co-coagulated under high-speed stirring, and then filtered out from the water to obtain wet powder.The obtained wet powder is placed on a stainless steel mesh tray, and the mesh tray is heat-treated in a hot air circulation electric furnace at 240 ° C.After 20 hours, the mesh tray is removed, and the mesh tray is air-cooled, and then a PTFE / PFA mixed powder is obtained.The mixing ratio (mass ratio) of the obtained PTFE / PFA mixed powder is PTFE / PFA=80 / 20.The obtained PTFE / PFA mixed powder is called polymer composition A. Polymer composition A had endothermic peak temperatures of 295°C and 342°C, a thermal instability index of 56, a 0.1% mass loss temperature of 385°C, a 1.0% mass loss temperature of 486°C, and a water content of 0.000% by mass. The content of the compound represented by general formula (1) having a carbon number m (4 to 20) contained in polymer composition A was less than 10 ppb by mass, and the content of the compound represented by general formula (2) having a carbon number n (4 to 20) was less than 10 ppb by mass.

[0496] Preparation Example 2: 886g of the PTFE aqueous dispersion obtained in Preparation Example 1 and 297g of the FEP aqueous dispersion obtained in Preparation Example 3 are placed in a container, diluted with deionized water to a solid content of 13% by mass, and the PTFE / FEP mixture is co-coagulated under high-speed stirring, and then filtered off from the water to obtain wet powder.The obtained wet powder is placed on a stainless steel mesh tray, and the mesh tray is heat-treated in a hot air circulation electric furnace at 210 ° C.After 20 hours, the mesh tray is removed, and the mesh tray is air-cooled, and a PTFE / FEP mixed powder is obtained.The mixing ratio (mass ratio) of the obtained PTFE / FEP mixed powder is PTFE / FEP = 80 / 20.The obtained PTFE / FEP mixed powder is called polymer composition B. Polymer composition B had endothermic peak temperatures of 257°C and 342°C, a thermal instability index of 64, a 0.1% mass loss temperature of 382°C, a 1.0% mass loss temperature of 484°C, and a water content of 0.000% by mass. The content of the compound represented by general formula (1) having a carbon number m (4 to 20) contained in polymer composition B was 67 ppb by mass, and the content of the compound represented by general formula (2) having a carbon number n (4 to 20) was less than 10 ppb by mass.

[0497] Preparation Example 3: 775 g of the PTFE aqueous dispersion obtained in Preparation Example 1 and 437 g of the PVdF aqueous dispersion obtained in Preparation Example 4 were placed in a container and diluted with deionized water to a solids concentration of 13% by mass. Nitric acid was added as a coagulant, and the PTFE / PVdF mixture was co-coagulated while stirring. The mixture was then filtered to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray and heat-treated in a hot air circulating electric furnace at 120 ° C. After 30 hours, the mesh tray was removed and air-cooled to obtain a PTFE / PVdF mixed powder. The mixture ratio (mass ratio) of the obtained PTFE / PVdF mixed powder was PTFE / PVdF = 70 / 30. The obtained PTFE / PVdF mixed powder was designated as polymer composition C. The endothermic peak temperatures of polymer composition C were 161 ° C and 342 ° C, and the water content was 0.003% by mass. The content of the compound having the carbon number m (4 to 20) and represented by the general formula (1) contained in the polymer composition C was 3786 ppb by mass, and the content of the compound having the carbon number n (4 to 20) and represented by the general formula (2) was less than 10 ppb by mass.

[0498] Preparation Example 4: 886 g of the PTFE aqueous dispersion obtained in Preparation Example 1, 60 g of the VT powder obtained in Preparation Example 5, and 960 g of deionized water were placed in a container, and nitric acid was added as a coagulant. The mixture was co-coagulated and dried in the same manner as in Preparation Example 3 while stirring to obtain a mixed powder. The resulting PTFE / VT mixed powder had a mixing ratio (mass ratio) of PTFE / VT = 80 / 20. This PTFE / VT mixed powder was designated Polymer Composition D. Polymer Composition D had endothermic peak temperatures of 136°C and 342°C, a moisture content of 0.005% by mass, and an average aspect ratio of 1.1. The PTFE powder was not fibrillated. The content of the compound represented by general formula (1) with carbon number m (4-20) contained in Polymer Composition D was 4326 ppb by mass, and the content of the compound represented by general formula (2) with carbon number n (4-20) was less than 10 ppb by mass.

[0499] Preparation Example 5: 996 g of the PTFE aqueous dispersion obtained in Preparation Example 1, 30 g of the VT powder obtained in Preparation Example 6, and 1,080 g of deionized water were placed in a container, and nitric acid was added as a coagulant. The mixture was co-coagulated and dried in the same manner as in Preparation Example 3 while stirring to obtain a mixed powder. The mixing ratio (mass ratio) of the resulting PTFE / VT mixed powder was PTFE / VT = 90 / 10. The resulting PTFE / VT mixed powder was designated Polymer Composition E. The endothermic peak temperatures of Polymer Composition E were 160°C and 342°C, the water content was 0.003% by mass, and the average aspect ratio was 1.2. The PTFE powder was not fibrillated. The content of the compound represented by general formula (1) with carbon number m (4 to 20) contained in Polymer Composition E was 4,867 ppb by mass, and the content of the compound represented by general formula (2) with carbon number n (4 to 20) was less than 10 ppb by mass.

[0500] Preparation Example 6: 135 g of the PTFE powder obtained in Preparation Example 1 and 15 g of the VT powder obtained in Preparation Example 6 were placed in a V-type mixer (VK-1, manufactured by Irie Shokai Co., Ltd.) and mixed for 10 minutes at 30 rpm. The resulting PTFE / VT mixed powder had a mixing ratio (mass ratio) of PTFE / VT = 90 / 10. The resulting PTFE / VT mixed powder was designated Polymer Composition F. Polymer Composition F had endothermic peak temperatures of 160°C and 342°C, a water content of 0.001% by mass, and an average aspect ratio of 1.5, indicating that the PTFE powder was not fibrillated. The content of the compound represented by General Formula (1) having a carbon number m (4 to 20) in Polymer Composition F was 60 ppb by mass, and the content of the compound represented by General Formula (2) having a carbon number n (4 to 20) was less than 10 ppb by mass.

[0501] Preparation Example 7: 886 g of the PTFE aqueous dispersion obtained in Preparation Example 1 and 223 g of the elastomer aqueous dispersion obtained in Preparation Example 7 were placed in a container and diluted with deionized water to a solids concentration of 15% by weight. Nitric acid was added as a coagulant, and the PTFE / elastomer mixture was co-coagulated under high-speed stirring. The water was then filtered off to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray and heat-treated in a hot air circulating electric furnace at 120°C. After 30 hours, the mesh tray was removed and air-cooled to obtain a PTFE / elastomer mixed powder. The mixture ratio (mass ratio) of the obtained PTFE / elastomer mixed powder was PTFE / elastomer = 80 / 20. The obtained PTFE / elastomer mixed powder was designated Polymer Composition G. The endothermic peak temperature of polymer composition G was 342°C, the water content was 0.005% by mass, and the average aspect ratio was 1.1. The PTFE powder was not fibrillated. The content of the compound represented by general formula (1) having a carbon number m (4 to 20) contained in polymer composition G was 4846 ppb by mass, and the content of the compound represented by general formula (2) having a carbon number n (4 to 20) contained in polymer composition G was less than 10 ppb by mass.

[0502] Preparation Example 8: 830 g of the PTFE aqueous dispersion obtained in Preparation Example 8 and 437 g of the PVdF aqueous dispersion obtained in Preparation Example 4 were placed in a container, diluted with deionized water to a solids concentration of 13% by mass, and nitric acid was added as a coagulant to co-coagulate the PTFE / PVdF mixture while stirring, and then filtered off from the water to obtain wet powder. The obtained wet powder was placed on a stainless steel mesh tray, and the mesh tray was heat-treated in a hot air circulation electric furnace at 120 ° C. After 30 hours, the mesh tray was removed, and the mesh tray was air-cooled, and then a PTFE / PVdF mixed powder was obtained. The mixture ratio (mass ratio) of the obtained PTFE / PVdF mixed powder was PTFE / PVdF = 70 / 30. The obtained PTFE / PVdF mixed powder was designated as polymer composition X. The endothermic peak temperatures of polymer composition X were 161°C and 343°C, the water content was 0.003% by mass, and the average aspect ratio was 1.1, and the PTFE powder was not fibrillated. Since polymer composition X used PTFE without a hydrocarbon surfactant, it did not contain the compounds represented by general formulas (1) and (2). Therefore, the content of the compound represented by general formula (1) having a carbon number m (4 to 20) in polymer composition X was less than 10 ppb by mass, and the content of the compound represented by general formula (2) having a carbon number n (4 to 20) was less than 10 ppb by mass.

[0503] Preparation Example 9: 811 g of the PTFE aqueous dispersion obtained in Preparation Example 9 and 437 g of the PVdF aqueous dispersion obtained in Preparation Example 4 were placed in a container and diluted with deionized water to a solids concentration of 13% by mass. Nitric acid was added as a coagulant, and the PTFE / PVdF mixture was co-coagulated while stirring. The mixture was then filtered to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray and heat-treated in a hot air circulating electric furnace at 120 ° C. After 30 hours, the mesh tray was removed and air-cooled to obtain a PTFE / PVdF mixed powder. The mixture ratio (mass ratio) of the obtained PTFE / PVdF mixed powder was PTFE / PVdF = 70 / 30. The obtained PTFE / PVdF mixed powder was designated as Polymer Composition H. The endothermic peak temperatures of Polymer Composition H were 161 ° C. and 344 ° C., and the water content was 0.004% by mass. The content of the compound represented by general formula (1) having the carbon number m=15 contained in polymer composition H was 31,460 mass ppb, and the content of the compound represented by general formula (2) having the carbon number n=8 contained in polymer composition H was less than 1,425 mass ppb.

[0504] Each of the polymer compositions obtained above was evaluated by the following methods.

[0505] Evaluation of Electrolyte-Containing Battery Electrode Mixture Sheets Mixture sheets of Examples A1 to A8 and Comparative Example A1 were produced and evaluated according to the following procedures.

[0506] <Preparation of Negative Electrode Mixture Sheet> The active material and binder (TFE-based polymer composition) were weighed and placed in a container. The active material and binder were sufficiently heated in a thermostatic bath at 80°C, and then treated in a Henschel mixer at 3000 rpm for 30 minutes to promote fibrillation, resulting in a mixture. The mixture was further kneaded (50 rpm, 10 minutes) in a tabletop kneader (PN-1, manufactured by Irie Shokai) to promote fibrillation. The mixture was then pulverized in a Henschel mixer at 3000 rpm for 5 minutes to promote fibrillation and improve dispersibility, resulting in an electrode mixture. The electrode mixture was placed between metal rolls arranged in parallel and rolled to obtain a negative electrode mixture sheet with a density of 1.3 g / cc and a thickness of approximately 250 μm (left and right roll temperatures: 200°C, left roll rotation speed: 1 m / min, right roll rotation speed: 0.4 m / min). Table 8 shows the types of binders used and the amounts added in the mixture.

[0507] <Evaluation of the performance of the mixture sheet> The negative electrode mixture sheet prepared under each condition was cut out to prepare a 5 mm wide strip-shaped test piece. The strip was evaluated based on whether it was possible to lift it as a free-standing film without tearing. Conditions where this was possible were marked with a circle, and conditions where this was not possible were marked with an ×. The results are shown in Table 8.

[0508]

[0509] The polymer composition E was used in the smallest amount to produce a sheet.

[0510] Mixture sheets of Examples B1 to B8 and Comparative Example B1 were prepared and evaluated according to the following procedures.

[0511] <Preparation of Negative Electrode> A negative electrode mixture sheet prepared with a binder addition amount of 2.6% by mass and 3.2% by mass was bonded to a current collector. Commercially available carbon-coated copper foil (thickness 10 μm) was prepared as a current collector. The negative electrode mixture sheet was placed on the carbon-coated copper foil, and the negative electrode mixture sheet and current collector were bonded together using a roll press. The sheet was then cut to the desired size to form a negative electrode. The processing conditions using the roll press were a roll temperature of 300°C for Examples B1 and B2, and a roll temperature of 200°C for the other polymer compositions, a speed of 0.1 m / min, and a pressure of 6 KN. The gap was adjusted so that the electrode mixture density was 1.5 g / cc.

[0512] <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 3 mass % of 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 salt was dissolved to obtain a non-aqueous electrolyte solution.

[0513] <Preparation of Coin Cell> The negative electrode was placed opposite a positive electrode (lithium metal foil) via a 20 μm-thick microporous polyethylene film (separator), and the nonaqueous electrolyte solution obtained above was poured in. After the nonaqueous electrolyte solution sufficiently permeated the separator, the coin cell was sealed to prepare a lithium ion secondary battery.

[0514] <Evaluation of Battery Characteristics (Coulomb Efficiency)> The lithium ion secondary batteries produced above were tested at 30°C. After constant current-constant voltage charging (0.05C cut) to 0.01 V at a current equivalent to 0.1 C, the batteries were discharged to 1.5 V at a constant current of 0.1 C. The results of the initial coulomb efficiency at this time are shown in Table 9. Coulomb efficiency is a value expressed as a percentage of the ratio of the discharge capacity during discharge to the charge capacity charged during charge. Since coulomb efficiency decreases due to side reactions in the battery system, batteries with high efficiency exhibit less deterioration during the initial charge and discharge stages.

[0515]

[0516] Mixture sheets of Examples C1 to C8 and Comparative Example C1 were prepared and evaluated according to the following procedures.

[0517] <Preparation of Negative Electrode> A negative electrode mixture sheet prepared with a binder addition amount of 3.2% was bonded to a current collector. Commercially available carbon-coated copper foil (thickness 10 μm) was prepared as the current collector. The negative electrode mixture sheet was placed on the carbon-coated copper foil, and the negative electrode mixture sheet and current collector were bonded together using a roll press to prepare a negative electrode sheet. The processing conditions using the roll press were a roll temperature of 300°C for Examples C1 and C2, and a roll temperature of 200°C for the other polymer compositions, a speed of 0.1 m / min, and a pressure of 6 KN. The gap was adjusted to achieve an electrode mixture density of 1.30 to 1.50 g / cc. The bonded electrode sheet was then punched into a round shape using a Φ15 hand punch. The punched cut surface was observed, and samples that showed no peeling / lifting from the current collector were rated "OK," while samples that showed peeling / lifting were rated "NG." The results are shown in Table 10.

[0518]

[0519] Although the electrode mixture layer needs to be crushed (consolidated) to adhere to the foil, the use of a specific fibrillating polymer in combination with a thermoplastic polymer can enhance adhesion to the foil. Therefore, adhesion can be achieved without increasing the density of the electrode mixture layer, allowing processing under a wider range of molding conditions. Furthermore, by including...

Claims

1. A polymer composition used as a binder for an electrochemical device, the polymer composition comprising a fibrillatable polymer, a thermoplastic polymer, and 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). General formula (1): (H-(CF ２ )) ｍ－１ -COO) ｐ M １ (In the formula, 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 (In the formula, 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. A polymer composition used as a binder for an electrochemical device, comprising a fibrillatable polymer and a thermoplastic polymer, wherein the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

3. The polymer composition according to claim 1 or 2, wherein the fibrillatable polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of polymerization units based on tetrafluoroethylene units and hexafluoropropylene.

4. The polymer composition according to any one of claims 1 to 3, wherein the content of the fibrillatable polymer is more than 50% by mass and 97% by mass or less with respect to the polymer composition.

5. The polymer composition according to any one of claims 1 to 4, wherein the thermoplastic polymer is at least one vinylidene fluoride-based polymer selected from the group consisting of polyvinylidene fluoride and a vinylidene fluoride / tetrafluoroethylene copolymer.

6. The polymer composition according to any one of claims 1 to 5, which is a powder.

7. The polymer composition according to any one of claims 1 to 6, which is used as a binder for a lithium ion secondary battery.

8. A binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition contains a fibrillatable polymer, a thermoplastic polymer, and 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). 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.) 9. A binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition comprises a fibrillatable polymer and a thermoplastic polymer, and the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

10. The binder for an electrochemical device according to claim 8 or 9, wherein the polymer composition has endothermic peaks in regions of 330 °C or lower and above 330 °C, respectively.

11. The binder for an electrochemical device according to any one of claims 8 to 10, wherein the endothermic peak temperature of the fibrillatable polymer is above 330 °C.

12. The binder for an electrochemical device according to any one of claims 8 to 11, wherein the fibrillatable polymer is a tetrafluoroethylene-based polymer.

13. The binder for an electrochemical device according to any one of claims 8 to 12, wherein the fibrillatable polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of polymerization units based on tetrafluoroethylene units and hexafluoropropylene.

14. The binder for an electrochemical device according to any one of claims 8, 10 to 13, wherein the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

15. The binder for an electrochemical device according to any one of claims 8 to 14, wherein the amount of the thermoplastic polymer relative to the polymer composition is less than 50% by mass.

16. The binder for an electrochemical device according to any one of claims 8 to 15, wherein the content of the fibrillatable polymer is more than 50% by mass and 97% by mass or less with respect to the polymer composition.

17. The binder for an electrochemical device according to any one of claims 8 to 16, wherein the 0.1% mass loss temperature of the polymer composition is 340 °C or higher.

18. The binder for an electrochemical device according to any one of claims 8 to 17, wherein the 1.0% mass loss temperature of the polymer composition is 370 °C or higher.

19. The binder for an electrochemical device according to any one of claims 8 to 16, wherein the thermoplastic polymer is a vinylidene fluoride-based polymer.

20. The binder for an electrochemical device according to claim 19, wherein the vinylidene fluoride-based polymer is a fluoroelastomer.

21. The binder for an electrochemical device according to claim 20, wherein the fluoroelastomer contains a vinylidene fluoride unit and other monomer units copolymerizable with vinylidene fluoride.

22. The binder for an electrochemical device according to claim 20 or 21, wherein the fluoroelastomer is at least one selected from the group consisting of a vinylidene fluoride / hexafluoropropylene copolymer, a vinylidene fluoride / 2,3,3,3-tetrafluoropropylene copolymer, and a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer.

23. The binder for an electrochemical device according to any one of claims 8 to 16, wherein the polymer composition has an endothermic peak in at least the range of 130 to 200 °C.

24. The binder for an electrochemical device according to any one of claims 8 to 16, wherein the thermoplastic polymer is at least one vinylidene fluoride-based polymer selected from the group consisting of polyvinylidene fluoride and a vinylidene fluoride / tetrafluoroethylene copolymer.

25. The vinylidene fluoride-based polymer has an average particle diameter of 10 μm or less and does not contain a fluorine-containing surfactant, and is a binder for an electrochemical device according to claim 24.

26. The binder for an electrochemical device according to any one of claims 8 to 25, wherein the average aspect ratio of the polymer composition in powder form is 2.5 or less.

27. The binder for an electrochemical device according to any one of claims 8 to 26, wherein the powder of the fibrillatable polymer is not fibrillated.

28. The binder for an electrochemical device according to any one of claims 8 to 27, which is in powder form.

29. The binder for an electrochemical device according to any one of claims 8 to 28, which is a binder for a lithium-ion secondary battery.

30. An electrode mixture containing the polymer composition according to any one of claims 1 to 7, or the binder for an electrochemical device according to any one of claims 8 to 29, and an electrode active material.

31. The electrode mixture according to claim 30, which is in sheet form.

32. An electrode containing the polymer composition according to any one of claims 1 to 7, or the binder for an electrochemical device according to any one of claims 8 to 29, an electrode active material, and a current collector.

33. A secondary battery including the electrode according to claim 32.

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